Wood Use: U.S. Competitiveness and Technology—Vol. II

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Wood Use: U.S. Competitiveness and Technology—Vol. II

November 1984

NTIS order #PB85-156081



Recommended Cita t ion:

Wood Use: U.S. Competitiveness and Technology—Volume II-Technical Report (Wash-ington , DC: U.S. Congress, Office of Technology Assessment, OTA-M-224, November1984).

Library of Congress Catalog Card Number 83-600567

For sale by the Superintendent of DocumentsU.S. Government Printing Office, Washington, DC 20402



Preface

The Office of Technology Assessment assessed the role of wood in the U.S.economy at the request of Senator Mark Hatfield, Chairman of the Senate Com-mittee on Appropriations, and Senator Thad Cochran, Chairman of the Subcom-

mittee on Agriculture, Rural Development, and Related Agencies, RepresentativeJames Weaver, Chairman of the Subcommittee on Forests, Family Farms, andEnergy, joined in support of the assessment in the House of Representatives. Thefinal report of this assessment w as pu blished as volum e I of Wood Use: U.S. Com-petitiveness and Technology, Representative Weaver requested that this secondvolume, a technical report on wood technologies and wood use, be prepared.

Volume II reviews the status of wood manufacturing technologies and surveysthe current and future uses of wood products. It explores the existing or develop-ing technologies and manufacturing processes that can enable the United Statesto benefit from its vast timber resource. Technologies for increasing the growthand production from the forest and the efficiency of harvesting and transportingtimber were treated in volume I.

-J O H N H . G I B B O N S

Director

,., ///





OTA Wood Use: U.S. Competitiveness and Technology Project Staff

Lionel S. Johns, Assistant Director, OTA Energy, Materials, and International Security Division

Audrey Buyrn, Industry, Technology, and Employment Program Manager

James W, Curlin, Project Director

Julie Fox Gorte, Assistant Project Director

W. Wendell Fle tcher Kathryn Hutcherson Robie

Nicholas A. Sundt* William F. Davidson*

Carol A. Drohan, Administrative Assistant

Patricia A. Canavan, Secretary

Kathleen D. Frakes, Research Assistant

Kathryn M. White, Editor

“(3TA c.ontractor





Contents

Chapter Page

I.

II .

III.

Findings and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Characteristics of Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,,. 10

Microstructure of Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Chemical Characteristics of Wood....,,....,.. . . . . . . . . . . . . . . . . . . . . . . . 11Physical Character istics of Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Energy Con sum pt ion in Wood Prod ucts Manu facture . . . . . . . . . . . . . . . . . . . 13

Presen t an d Prospective Uses of Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Wood as a Fuel. .,... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Ind ustr ial Wood -Fuel Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Residential and Commercial Fuelwood Use,,..,,., . . . . . . . . . . . . . . . . . . . . 19Second ary Fuels an d Chem icals From Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Wood Technology and the Resource Base... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Research and Development on the Use of Wood . . . . . . . . . . . . . . . . . . . . . ..,, 23

Federal Government R&D Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

R&D in Academic Institutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Industrial R&D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Solid Wood and Panel Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Sum mary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Profile of the Lum ber and Panel Prod ucts Ind ustry . . . . . . . . . . . . . . . . . . . . . . . 34

Raw Materials...,.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Product Demand ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,,. 35Industry Size and Distribution of Production . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Use of Solid Wood and Panel Prod ucts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Industry Trends and Potentials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Product Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Forest Resource Use., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Efficient End Use of Wood Products, , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Lum ber Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Lum ber Manu factu re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Potential Imp rovements in Milling Efficiencies and Lumber Manu facture . . 42

Consu mp tion and Use of Lum ber Prod ucts in the United States . . . . . . . . . . 48Plywood and Panel Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Plywood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Particleboard ,.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Structural Com posite Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Fiberboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Present an d Fu ture Use and Consu mp tion of Panel Prod ucts. . . . . . . . . . . . . 58

Wood Use in Light Frame Construction. . . . . . . . . . . . . . . . . . . . . . . . . . . 61Wood Conservation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61New Uses for Solid Wood Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Com posites of Wood and Oth er Materia ls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Pulp, Paper, and Fiber Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67Sum mary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68Profile of the Pulp and Paper Industry , . . . . . . , . . . , . , , , , . . . , , , , , , , . , . 68Uses of Pulp, Paper, and Paperboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69Advanced Paper Materials . . . . . . . . . . . . . . . . . . . . . . . ...,.,..,.,,,,,,,,, 71

Role of Paper and Cellulosic Materials in the U.S. Material Mix . . . . . . . . . . . 72Competition From Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74Competition From Electronic Technologies, .....,,, . . . . . . . . . . . . . . . . . . . 76

vii





Contents–continued

List of Figures

Figure No.. Page

I. Three Characteristic Directions of Wood That Are Influenced byWood Propert ies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2. U.S. Wood Energy Consumption, 1850-1980. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3. Estim ated Wood -Fuel Consumption , 1961-81 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164. Timber Supply to and Product Output From PrimaryProcessing Plants, 1976 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5. Chemicals From Wood. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216. Historical Research and Developmen t Expen ditu res . . . . . . . . . . . . . . . . . . . . . . . 297. U.S. Trade in Lumber and Panel Products, 1976. . . . . . . . . . . . . . . . . . . . . . . . . . 358. Flow Diagram of a Typ ical State-of-the-Art Small-Log Sawm ill, Indicating

Process Waste Streams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 429. Present and Predicted Materials Balance for Softwood Lumber Based on

Ovendry Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4310. The Maximum Yield of Lumber From Conventional and

Innovative Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4511. Per Capita Consumption of I.umber 1950-79 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4812. The Truss Frame System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

13. Flow Diagr am of a Small-Log Plyw ood Mill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5114. Material Balance for Softw ood Plywood Based on O vend ry Weigh t . . . . . . . . . 5215. Materials Balance for the Manufacture of Underpayment Particleboard Based

on Ovendry Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5416. Materials Balance for the Manufacture of Structural Particleboard Based

on Ovend ry Weight of Chipp ing an d Flaking of Sound Wood . . . . . . . . . . . . . . 5517. Idealized Typical Waferboard Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5618. Idea lized Typical Orien ted Strand Board Process . . . . . . . . . . . . . . . . . . . . . . . . 5719. Historical Production of Major Panel Products, 1970-79 . . . . . . . . . . . . . . . . . . . 5920. Offcenter, In-line Joint Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6121. Wooden I-Beam Constru ction, Cross-Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6222. Propor tions of Woodpu lp Prod uced by Comm ercial Pulp ing Processes . . . . . . . 8023. Schematic Flow Diagram of Alternat ive Mechan ical Pulping Processes . . . . . . 8124. Wood and Energy Flows in Mechanical Pulping Mills in

Conjunction With Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8225. Material an d Energy Flow into a Kra ft Pu lpm ill . . . . . . . . . . . . . . . . . . . . . . . . . . 8626. Overall View of Papermaking From Chemical Pulp by the Kraft

Pulping Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

ix



Findings and Conclusions



Findings and Conclusions

1. Technologies for wood use could aff ect f uture U.S. ti mberrequirements in two ways: 1 ) by extending the wood re-source through improved product recovery and 2) by sub-stituting wood for nonrenewable materials.

The United States currently has abundantproductive timber resources compared to thoseof most other industrialized countries. How-ever, the U.S. Department of Agriculture’s(USDA) Forest Service forecasts p ossible shor t-falls in the year 2030 of domestic timber speciesand sizes currently used for structural mate-rials, pulp, and paper. At the same time, theU.S. forest products industry sees a potentialfor increased export of wood products and amore active U.S. role in world wood trade,Technology will play a major role in both ex-

tending timber resources and developing newand improved ways to use wood,

Il. Existing and emerging manufacturing t echnologies couldincrease wood product yield signific antly and may re-sult i n increased util ization of forest residues for indus-trial energy production.

Because nearly half of all industrial forestproducts are lumber and structural panels, in-creased yield of these products alone couldhave a major impact on domestic timber de-mand. H owever, increased yield of solid woodproducts also could reduce the amount of wastewood available for energy generation in lumbermills and pu lpmills, a situation th at could stim-ulate greater use of forest residues and otherbiomass in the forest prod ucts industry, Lumberproducts, generally used for structural support,are long, thin, rectangular pieces of solid wood.Panel products often are used for structuralsheathing and generally are manufactured in4-by 8-ft sheets usually less than 1 inch thick.Pulp products include paper and paperboard,films, and fabrics,

The amount of roundw ood required for lum-ber production could be reduced 20 to 40 per-

cent by u sing current ly available technologiessuch as Best Opening Face (BOF), saw-dry-rip(SDR), or edge-glue and rip (EGAR), althoughit will take several years to achieve even a 20-percent reduction. Such savings would be sig-nificant, since lumber consum ption of over 50

million tons in 1979 accounted for about half of all wood products consumed.

Composi tes— such as parallel-laminated

veneer (PLV) and corn-ply-are probably themost material-efficient lumber products.They are manufactured by gluing veneers orparticles together and sawing the resultingboards into a variety of prod ucts. Use of theseprocesses can increase lumber recoveries 40to 90 percent or more. However, this technol-ogy is not yet u sed on a large commercial scale(probably less than 1 percent of all lumberproducts are composites]; such technologywould require new facilities entirely differentfrom those in conventional lum ber m ills. Eventhough composite lumber products offer in-

creased lumber recovery and use of lower qual-ity wood, they are unlikely to replace conven-tional sawn lumber to any great extent du ringthe next tw o decades because of the large cap-ital investment requirements, high variablecosts (e. g., glue costs), and possible problemsresulting from formaldehyde emissions fromadhesives.

Adoption of several new technologies couldincrease lumb er recovery of existing m ills upto 30 percent with out m ajor plant alterations.Among these are the BOF program and theEGAR process. BOF is a computer-assistedmethod for increasing lumber volume andgrad e by optimizing saw lines. Laboratory testsand some inservice tests indicate that BOFcould increase lumber yields by more than 20percent. EGAR is an innovative sawing-and-gluing technique that reduces loss of wood inthe saw ing p rocess, can increase lumber r ecov-ery 10 to 13 percent, and permits the use of lower quality raw material.

Product yields in the manufacture of com-posite wood panels are 75 to 80 percent byweight, compared with the average current

plywood recovery of about 50 percent. Com-posite wood-panel products (particleboard) aremanufactured from wood chips, flakes, wafers,or strands that are glued and formed into ply-wood-like sheets. Composite panels with thestrength of plywood are now being produced

3



4 q Wood Use: U.S. Competitiveness and Technology

and eventually will substitute for plywood inmany structural uses.

Substitution of composite wood panels forplywood already has begun, and substantialadditions to waferboard and oriented strandboard (OSB) production capacity has been com-

pleted, Comp osite panels will begin to replacesignificant amounts of plywood in structuraluse by the middle of the decade, Within 10 to20 years, it is likely that these pr odu cts will re-place most construction plywood, Limits onproduction of composite panels probably willhave more to do with access to investment cap-ital in processing facilities than with institu-tional or technological constraints.

Increased use of improved mechanicallyproduced pulps can increase fiber yields fromabou t 50 percent to almost 95 percent, reduc-

ing wood requirements to 1.05 tons per tonof paper. Over 75 percent of current U.S. pulpand paper production is from the relativelylow-yielding kraft chemical pulping process.Since about one-third of indu strial roun dw oodin the United States is used for pulp and pa-per (53.5 million ton s in 1979), a significant im-provement in overall fiber recovery would re-sult if highly efficient mechanical pulpingreplaced chemical pu lping. For example, ther-momechanical pulping (TMP)—an improvedmechanical pulping process that produceshigher quality paper than other mechanical

processes—could disp lace about 300 pound s of the kraft paper currently used in each ton of newsp rint. Oppor tun ities also may exist for re-du cing the amount of kraft pu lp used in otherprinting papers. There probably are practicallimits, however, on the extent to which me-chanical pulps can substitute for chemicalpulps, because high-strength and permanentlybright papers cannot yet be manufactured frommechanically produced pulps.

Opportunities for improved mechanical pulpsto make significant contributions to pulp con-

sumption over the next two decades are rea-sonably good. Production of improved mechan-ical pulps already has begun and is expectedto expand.

Ill . Technology could expand the use of currently abundanthardwood species, enabling use of wood material nowunderutilized.

Over one-third of the total volume of exist-ing U.S. timber is hardwood. Hardwood inven-tories are increasing at a rate over six times thatof softwoods, which have been more heavilyutilized because of their superior properties forthe manufacture of many conventional woodproducts. In the Eastern United States, hard-woods comprise over 62 percent of the stand-ing timber, yet account for only 44 percent of the har vest. Thu s, in th e East, and particularlyin the South, hardwoods are a significant andunderutilized wood resource. Because of theirwood qualities, softwoods currently are pre-ferred for manufacture of lumber, plywood,and some types of paper, However, existingand emerging technologies may be capable of

using hardw oods to make many p rodu cts thatare now produced mostly from softwoods.

Composi te lumber and par t ic leboard ,which can be m anufactured from h ardwoods,could substitute for softwood lumber and ply-wood. In addition, SDR technology couldenable the manufacture of high-quality sawnlumber from underutilized and abundant hard-wood species, SDR is a modification of the nor-mal sequence of lumber processing that mayreduce defects and w aste in hard wood lumbermanufacture. The SDR pr ocess maybe ad optedwithout major equipment changes or additionsto existing mills.

Increased use of hardwoods for pulp andpaper may be possible with the adoption of mechanical and chemimechanical pulpingtechnologies. Hardwood species are used ex-tensively for the production of newsprint andfine printing papers. However, papers manu-factured from hardwoods are weaker thanthose made from softwoods, which have longfibers; thu s, their end use is limited to app lica-tions where paper strength is not of prime im-portance. Chemimechanical pulping (CMP),

which involves chemical treatment of woodprior to grinding, may be able to producestrong hardw ood p apers that could displace orsupp lement the u se of some softwood pap ers,



Findings and Conclusions q 5

Press-dry papermaking technology offersperhaps the greatest opportunity to expandfuture hardwood utilization. Press drying,which produces paper from hardwood pulpusing high pressure and high temperatures dur-ing part of the papermaking process, could

produce heavy-duty linerboard with strengthproperties generally superior to those of con-ventional kraft linerboard. Linerboard cur-rently uses about one-fourth of the wood pu lpproduced in the United States (approximately13 million tons/ y r), and p rospects are good forincreasing linerboard exports. Response to themarkets and a combination of press-dry tech-nology and hardw ood CMP in the produ ctionof linerboard, could expand significantly theuse of several currently underutilized hard-wood species. Softwood pu lps also can be proc-essed by press drying, but the principal ad-

vantage of the technology is that it enablesmanufacture of high-strength papers fromhardwoods. The press-dry process was devel-oped by the U.S. Forest Products Laboratory(FPL) and requires further modification andtesting before it can be commercialized.

IV. Conservation of solid wood materials through increasedrecycling of waste paper and improved structural de-sign could reduce demands for wood.

Approximately one-fourth of the total paperpulp produced in the United States annuallycomes from recycled paper. Recycling presents

some opportunities for energy conservation.The use of 14 percent recycled fiber for themanufacture of newsprint, for example, couldreduce electricity consumption in paper mak-ing by 7 to 10 percent. Two major barriers toincreasing recycling remain, however, in theUnited States: 1) used paper usually is contami-nated with glue, ink, and other materials thatare expensive and difficult to remove; and 2)the economics of waste-paper collection andtransportation make recycling generally un-profitable, except in metropolitan areas. Onlya few paper mills operate with recycled paperalone; most often, they blend it with virginpulp, which lends strength to the weaker, re-cycled fibers. The practical upper limit forusing recycled fiber in furnished paper is about40 percent.

Some construction techniques and designscan reduce structural wood products require-ments in residential construction by nearlyone-third. Since over 50 percent of the lumberand panel products consumed in the UnitedStates are used for residential and nonresiden-

tial construction or structural maintenance,significant savings in total wood consumptioncould be realized from a modest reduction inconstruction wood use. Designs that r ely on theinteraction of individual building componentsfor structural streng th–e.g., truss framing, w alland floor assemblies, and sandwich panels thatreplace framing and sheathing—also conservewood. Penetration of these innovations intoconstruction markets is likely to be slow, how -ever, due to the conservatism of building codes,the construction industry, and home buyers.Also, some current trends, such as the use of

wider framing lumber for increased energyefficiency, may result in increased structuralrequirements.

V. New pulping technologies could reduce energy require-ments for pulp and paper making and even produce ad-ditional energy for outside sale.

An estimated one-half of the wood (both in-dustrial roundwood and other wood) removedfrom U.S. forests, over 120 million ovendriedtons, eventually is consumed for energy pro-duction. Almost two-thirds of the wood fuelburned in 1981 was consumed by the wood

products industry. The pulp and paper sectoralone accounted for about 3 percent of totalU.S. energy consumption. As a result of thislarge energy usage, pulp an d pap er manu fac-turers have become industrial leaders in energyconservation and electric cogeneration.

Innovations could boost waste heat recov-ery in mechanical pulping for use in paperdrying, space heating, and water treatment.In addition, use of pulping technologies suchas pressurized groundwood (PGW] pulping,CMP, and chemithermomechanical pulping

(CTMP), wou ld resu lt in lower energy requ ire-ments than those of TMP and chemical pulp-ing technologies.

Process improvements in chemical pulpingmay allow mills to approach energy self-suf-




ficiency. Amon g the strategies available to re-duce energy consumption are: 1) increasing theuse of wood waste in cogeneration, 2) usingspent pulping liquor more efficiently for fuel,and 3) recovering low-quality energy more effi-ciently through heat pumps and heat ex-

changers.

Improvements in drying technology offerthe greatest opportunities for reducing energyconsumption in lumber and panel manufac-turing because about 70 percent of the aver-age energy consump tion is used in kiln op er-ations and panel drying. Solar kilns, vacuumkilns, and microwave drying are current op-tions for reducing energy consumption. Im-proved operation of conventional steam-heatedkilns through use of sensors and computer con-trols also provide opportunities for reducingenergy consumption.

Improvements in residential stove and fur-nace design and in technologies for produc-ing industrial wood energy could probablyraise the efficiency of d irect w ood-fuel com-bustion to 80 percent of the heat-producingpotential of the wood. Conversion from openfireplaces to efficient wood stoves could changewood fuel-use efficiency from negative values(heat loss) to as h igh as 50 percent. Use of self-stoking furnaces, heat storage d evices, and cir-

culating systems could raise residential wood-use efficiencies to 80 percent of the fuel’s heatpotential. In larger commercial and industrialapplications, fluidized-bed burners can achieveefficiencies of up to 80 percent, though currentefficiency averages 70 percent. Gas turbinetechnologies coupled with fluidized-bed burn-ers could efficiently cogenerate electricity if

technologies were developed to cleanse thecombustion gases.

It is feasible (but uneconomical using ex-isting chemical technologies) to convert forestbiomass to chemical feedstocks and inter-

mediate products that are currently extractedfrom petroleum. These may be transformedinto nearly all the major industrial organicchemicals. Optim istic pr ojections ind icate thatliquefaction, gasification, pyrolysis, andhyd rolysis of less than 60 million tons of woodand wood residues theoretically could supplya significant proportion of the synthetic polymerscurrently consumed in the United States. How -ever, the complex processes required for theirman ufacture are un econom ic at this time. Pro-duction of ethanol and methanol from woodand the oxygen gasification of wood could re-

sult in production of liquid fuels and syngasfor energy conversion.

VI. New wood products may serve as substitutes or com-plements for materi als derived from nonrenewableresources.

For example, composite materials made of wood and fiberglass, plastics, or metal havedemonstrated superior performance in someapplications, although these composites cur-rently account for only a small proportion of the total wood materials used. Experiments atFPL have demonstrated the technical feasibil-

ity of producing very stiff, high-strength paper,which, with further development, may someday be used for wall sheathing or modularstructural panels. Tests of paper constructionmaterials have yielded mixed results, and a sig-nificant amount of add itional work is pr obablyneeded before paperboard could become amajor structural material.



CHAPTER

Introduction



CHAPTER 1

Introduction —

Few materials are as widely used or as ver-satile as wood. For millenia, wood’s extensive

natu ral occurrence and its adap tability, renew-ability, and workability have combined to makeit a material of choice in a wide range of ap-plications. When abundant, wood has helpedbuild and fuel many great civilizations. Scar-city of wood has sometimes contributed to acivilization’s decline.

For many pu rposes, wood has required com-paratively little alteration from its natural state,

More recently, technology has helped trans-form w ood into an expanding variety of prod-

ucts bearing little resemblance to wood as itappears in trees or is used in conventionallumber (table 1). In addition to lumber andfirewood, products that can be made fromwood now include chemical feedstocks andplastics, reconstituted wood-building materials,liquid and gaseous fuels, food supplements,and 14,000 kinds of paper,

Table 1 .—Taxonomy of Major Forest Products

Status of Product Description Major end use

Lumber type products B o a r d s

a --

Dimension a lumber

Timbers

Parallel laminatedveneer (PLV)

Utility poles

Panel type products Plywood

Hardwood

Particleboard

Medium-densityfiberboard

Semirigid insulationboard

Rigid insulationboard

Waferboard

Oriented strandboard (OSB)

Corn-Ply

1“ thick, 4“ to 16’, > 1“ wide2“ to < 5“ thick, > 2" wide, usually 4’ to 16’long solid wood, sometimes edge glued

5 + thick, > 4“ wide, various lengths;solid or laminated wood

Usually same dimensions as lumber andtimbers, made from wood veneerslaminated with parallel grains

9“ to 14” diameter, 50’ to 80’

Flat panels, usually 4’ x 8’, less than 1.5”thick, made from wood veneers laminatedwith grains of adjacent veneers

perpendicular, Usually 3 to 5 plies (veneers)Flat panels made of individual wood fibers,usually glued together

Flat panels, less than 1.5” thick, cut tosize of 4’ x 8’, composed of very smallwood particles glued together

Same as hardboard, with extremely flat,smooth surface and edges

Flat panels made of individual wood fibers,usually loosely matted, fibers bonded byinterfelting

Same as semirigid insulation board

Flat plywood-like panels made with flat,nonalined wafers or large chips of woodglued and pressed together

Flat plywood-like panels made with alignedstrands or ribbon-shaped pieces of wood,Sometimes crossbanded (strands indifferent layers oriented perpendicular toadjacent layers), sometimes veneered

Flat plywood-like panels or lumber-likepieces, with particleboard cores andwood veneer faces

MM

M

G

M

M

M

M

M

D

D

G

G

General purposeStructural framing

Structural framing beams, and largesupports

Structural framing and supports, Canbe used in millwork and molding

Transmission lines

also

Structural sheathing, flooring, and a varietyof semistructural uses

Floor underpayment, facing for architecturalconcrete, wall linings, door inserts, stereo,radio and TV cabinetry, and furniture

Underlay merit, furniture core

Furniture, wall siding

Insulation, cushioning

Interior walls and ceilings, exterior sheathing

Paneling, substitute for plywood instructural use, wallboard

Same as plywood

B Same as lumber and plywood

9




Table I.–Taxonomy of Major Forest Products (continued)

Product Description —

Paper products Unbleachedkraft paper

Bleachedkraft paper

Newsprint andgroundwoodprinting papers

Corrugating medium

Linerboard

Paperboard

Coated paper

Specialty papers

Tissue paper

Other productsRayon

Acetate

Cellulosic films

Brown, somewhat coarse, stiff papermanufactured primarily by the kraft sulfate

process from hardwoods and softwoodsWhite fine textured paper manufactured byeither the kraft sulfite process or the kraftsulfate process from either softwoods orhardwoods. The better papers areprovided from softwoods

Coarse textured paper of low strength andlimited durability, which tends to yellowwith age. It is manufactured frommechanical and semimechanical (particularlychemically treated) pulp, which uses eitherhardwoods or softwoods

Coarse, low-strength paper producedprimarily from sulfite pulping of hardwoods

Stiff, durable, thick paper made primarilyfrom unbleached kraft paper made by thesulfate process

Stiff paper of moderate thickness madeprimarily from bleached sulfate kraft pulp

Printing papers that have been coated withmaterials that improve printability andphoto reproduction

Diverse group of products ranging fromthin filter papers to stiff card stock

Thin, soft, absorbent papers manufacturedprimarily from chemical groundwood pulps

Synthetic fiber produced by the viscoseprocess using pure cellulose produced bythe dissolving pulp process. Rayon hasproperties similar to cotton

Synthetic fibers produced from dissolvingpulp-like rayon, but further chemical

treatment make them water resistant withproperties more like nylon or orlonFilm made from dissolving pulp by therayon and acetate processes, butextruded as sheets of various thicknesses

Status oflifecycle

M

M

M

M

M

M

M

M

M

M

M

D

Major end use .

Heavy packaging, bags, and sacks

Fine writing and printing papers andpaperboard for packaging

Printing of newspaper and for otherprinting uses not requiring durability

Corrugated boxes as dividers andstiffeners between the paperboard liners

Heavy duty shipping containers andcorrugated boxes

Milk cartons, folding boxes, and individualpackaging

Magazines, annual reports, and books

Cigarettes, filter papers, bonded papers(with cotton fibers) index cards, tags, filefolders, and postcards

Toweling, tissues, and hygenic products

Woven cloth as a cotton substitute

Woven cloth as a substitute for nylon andother petroleum-derived synthetic fibers

Packaging (cellophane) protectivecoverings, photographic applications,transparent drafting and graphic materials

NOTE: B

SOURCE Office of Technology Assessment

Characterist ics of Wood

Wood is grouped into hardwoods and soft- characteristics are significant between andwoods. Hardwoods generally are broad-leaved within species and even between pieces of

deciduou s trees, while softwood s are conifers, wood from different parts of a single tree.with needles or scalelike leaves that generallyare evergreen. Although there are broad dif-ferences in the characteristics of wood from

Microstructure of Wood

hardwoods and softwoods, variations in micro- Differences in microstructure between soft-structural, p hysical, chemical, and mechanical woods and hardwoods give the wood from



Ch. 1—Introduction q 1 1

these species different properties, Softwoodshave fewer cell types, generally longer fibers,thinner cell walls, and more uniform cellulararrangements than d o hard woods. Because of their strength, softwoods often are preferredin structural applications. Hardwoods varyconsiderably in their machining and dryingcharacteristics, which makes the commercialuse of hardwoods more complex, However,grain patterns and color make them attractivefor furniture and cabinetry.

There also can be microstructural differenceswithin species of wood. Leaning trees containcompression wood (softwoods) or tensionwood (hardw oods), apparently a result of thetree’s microstructure changing to accommo-date the u neven load d istribution as it grows.Fertilization, pruning, and other silvicultural*

practices also change the microstructure of wood. These changes, currently under inves-tigation by wood technologists, may have someeffect on the u tilization of wood grow n in con-trolled environments (the so-called plantationwood).

Chemical Characteristics of Wood

The major chemical constituents of wood in-clude: 1) cellulose, 2) lignin, 3) hemicellulose,and 4) extractives. Cellulose, which comprisesapproximately 50 percent of wood by weight

(ovend ry), is the primary structural component.The exceptionally strong chemical bonds with-in cellulose molecules give wood great strengthrelative to its weight, Cellulose fibers are themajor component of paper and can be alteredchemically to produce a wide range of prod-ucts such as chemicals, plastics, syntheticfibers, and films, Lignin, which cements thefiber together, is a complex organic chemicalthe structure and properties of which are notfully understood. Theoretically, lignin could beconverted into a number of chemicals. Cur-rently, however, it is burned to produce energyas a waste produ ct from pu lp and p aper man-ufacturing, Hemicellulose is similar to cellu-

lose in composition and function. It plays animportant role in fiber-to-fiber bonding in pa-permaking. Finally, several extractives arecontained in wood but d o not contribute to itsstrength properties,

Physical Characteristics of Wood

Physical properties of wood vary consider-ably, both between and within species. Someof the more important physical properties of wood are: 1) den sity (or specific gravity); 2) me-chanical properties (strength and stiffness aremost important); 3) shrinking and swelling dueto changes in moisture content; 4) thermalproperties; 5) electrical properties; 6) machin-ing or working qualities; 7) susceptibility todecay; 8) degree of resistance to chemicals;

9) combustibility; 10) weathering; and 11) ap-pearance, such as grain, texture, and sheen,The range of values for some of these proper-ties and their importance is shown in table 2.

Density (mass per unit volume] is generallya good indicator for other properties (includingmechanical, thermal, and electrical). Specificgravity varies with different locations in thetree and is influenced by silvicultural practices;hence, it influences a tree’s other properties,Manipulation of growth factors is one of thefew controls available to “manufacture” thewood substance to desired properties. This

contrasts with other materials, in which manyvariables can be manipulated to achieve de-sired properties,

Wood moisture content (the ratio of theamount of water in the wood to its dry weight)is another important variable. This moisture,bound in the cell walls, influences wood prop-erties. Stiffness and strength decrease, andthermal and electrical conductivity increase,as moisture content increases, The moisturecontent of living trees u sually is above 50 per-cent but varies considerably by species, time

of year, and associated weather conditions.Once felled, however, the wood dries and tendstoward an equilibrium moisture content (EMC)corresponding to prevailing relative humidityand temperature conditions. Air or kiln dry-ing is used to reduce the moisture content of




Table 2.— Physical Properties of Wood

Property Range or average Importance

Density (specific gravity) 20-45 lb/ft3

(0.3 to 0.7)

Shrinkage and swelling Hardwood: 10-19 percentby volume

Softwood: 7-14 percentby volume

Thermal properties

Electrical properties

Decay and chemicalresistance

Combustibility

Working qualities

Weathering

Appearance

Resistance: R= 1.25[ft 2 h“ F/Btu/in]

Diffusivity: D=O.25 x 10-3

(in2 /s)

Dielectric constant: 2-5Resistivity: 10

10to 10

13ohm-m

(103to 10

4when saturated)

—

Density can affect the ability of wood to hold coatings suchas paint, stain, and adhesives. It affects the machinabilityand other working qualities and the weight and ease ofhandling the products.

Shrinkage upon drying can result in warping, crooking, andbowing in lumber. Some woods have a greater tendencytoward internal stresses caused by shrinkage, which maymake them less suitable for lumber or may requirespecial treatment to avoid deformities. Shrinkage alongthe grain is only 10 percent of shrinkage across thegrain.

Wood is a good thermal and electrical insulator. Because itsthermal conductivity is a fraction of that of most metals,wood tends to gain heat slowly from its surroundings.

Wood is a poor electrical conductor, though its conductivityincreases with increasing moisture content.

Different species vary in resistance to decay and chemicals.Wood deteriorates more rapidly in warm humid

environments than in other conditions. It is often used inchemical processing operations where exposure to mildacids and acidic salt solutions would corrode ordinarysteel or cast iron.

Two important aspects of wood combustibility are flamespread and char development. Rate of charring into largewood members is very slow; hence, strength is retainedfor a long time in a fire situation.

Working qualities refers to the ease and quality of planing,shaping, turning, mortising, sanding, steam bending, andnail and screw splitting. They affect appearance, usefullife, and range of use of wood products.

Weathering causes boards to warp, pull out fasteners, checkor split, and turn gray. Sometimes weathered appearanceis desirable for decorative use.

Color, grain, texture, sheen, and surface roughness affect

the appearance of wood. Fine furniture woods requirespecial characteristics, as do woods used for panelingand cabinetry. The appearance of structural material isless important.

SOURCE Adapted from U S Department of Agriculture, Forest Service, Forest Products Laboratory,Wood Handbook Wood as an Engineering Material (Washington,D C U S Government Printing Off Ice, 1974)

green lumber to approach the EMC to meet theend-use requirement.

In contrast to most other structural materialssuch as ceramics, concrete, and metals, whichhave the same properties in all directions,wood is naturally anisotropic, having d ifferent

mechanical and physical properties along itsthree dimensions. The three mutually perpen-dicular, characteristic dimensions of wood arecalled: longitudinal (along the grain), radial(across the grain, out from the center), and tan-gential (across the grain, tangent t o the annual

rings) (fig. 1). Stiffness an d streng th, as w ell asother properties, vary considerably in the threedirections.

Strength, p articularly along th e grain, is oneof the most important mechanical propertiesof wood. Wood’s strength is compared on astrength-to-weight basis with other materialsin table 3.

During use, wood is subjected to a numberof different loading modes including bending,compression, shear, and tension. Most impor-



Ch. I—Introduction q 1 3

Figure 1 .—Three Characteristic Directions of WoodThat Are Influenced by Wood Properties

tantly, wood is a very efficient material forbending applications, and designers can com-pensate for its relatively low shear strength p ar-allel to the grain by m aking long, slend er struc-tural members that stand u p w ell to bending. *In addition, because its compression strength

is relatively high, wood is an excellent mate-rial for columns. Its inherent strength is lessimportant in the d esign of columnar su pp ortsthan its geometry and stiffness. Clear woodalso has high tensile strength. As a result,higher grad e (clear] material is used in tension

members of trusses or in the outer layers of laminated beams.

Energy Consumption in

Wood Products Manufacture

The amount of energy required to produceconstruction materials and paper from woodgenerally is less than th at required for produc-ing prod ucts from metals, plastics, or masonryon a weight basis (table 4). Production of paper,for examp le, uses less than h alf the energy per

ton than does the production of plastics andless than 10 percent as much as the produc-tion of aluminum foil for packaging. Thus,wood, being a renewable resource, could sub-stitute for other materials that require largeamounts of energy for their manufacture.

Table 3.—Structural Properties of Some Wood, Metals, and Masonries



14 . Wood Use: U.S. Competitiveness and Technology

Table 4.—Energy Requirements for Primary Commodities (million Btu (oil-equivalent)/ton))

Available residueCommodity Extraction Processing Transport energy N e t

atotal

Softwood lumber . . . . . . . . . . . . . . . . . 0.943 4.846 1.966 8.313 2.909Softwood sheathing plywood . . . . . . 0.747 6.871 2.081 3.697 6.002Structural flakeboard . . . . . . . . . . . . . 0.956 7.511 1.314 8.616 2,270

Underpayment particleboard. . . . . . . . 4.6172

b

8.1011.198

1.529 12.387Concrete . . . . . . . . . . . . . . . . . . . . . . . . 0.52 7.60 0.40 — 8.52Concrete block . . . . . . . . . . . . . . . . . . 0.52 7.60 0.65 — 8.77Clay brick . . . . . . . . . . . . . . . . . . . . . . . 0.57 7.73 0.76 — 9,06Steel studs . . . . . . . . . . . . . . . . . . . . . . 2.45 46.20 1.67 — 50.32Steel joists . . . . . . . . . . . . . . . . . . . . . . 2.45 46.20 1.67 — 50.32Aluminum siding . . . . . . . . . . . . . ....26.80 172.00 1.67 — 200.47

Present and Prospective Uses of Wood

Domestic production of wood has increasedby about one-third since 1950. Much of thegrowth in d emand for wood has been in high-value wood p rodu cts such as lum ber, plywoodand veneer, and pulp, while the declines havebeen in lower value products, such as railroadties and mine timbers. Wood is used for a va-riety of purposes, including shelter and otherconstruction, communication, packaging, in-formation storage, energy, textiles, and chem-icals.

The chemical constituents of wood, primar-ily carbon and hydrogen, may be converted toforms that can be used to manu facture a w iderange of products currently derived from petro-leum—although few now are so used, Chemi-cals recovered from w ood throu gh p ulping areused in turpentine, rosins, pine oils, furfural,and other commonly used chemical products.Lignin, although currently burned as a wasteproduct to produce energy within pulpmills,shows promise as an adhesive, dispersingagent, binder, and source of vanillin anddimethyl sulfoxide (DMSO). Rayon, celluloseacetate, and cellulose esters, manufactured

from wood pu lp, maybe used for cloth, packag-ing films, and explosives. Sawdust and woodflour are used as cattle feed and as bulkingagents in human food.

As an energy source, wood’s historical im-portance is difficult to overstate. Until 1870,

wood was the p rimary fuel for both indu strialand residential heating in the United States.i

Even in 1940, when coal had long supplantedwood as a residential heating fuel, more house-holds were heated with wood than with gas,electricity, and oil combined. The recent resur-gence of wood in home heating—brought aboutby the rising costs and potential shortages inother energy sources—has both stimulated andbeen stimulated by technological innovationsin wood-burning stoves and other devicesadapted to home heating.

The forest products industry itself has be-come an industrial leader in the use of woodas an alternative energy source. Roughly half of the energy needs of the industry are pro-du ced from w ood residu es and byp roducts. Insome cases, mills have become virtually energyself-sufficient. In addition, a few wood-fueledcentral electric-generating stations of modestsize have been constructed by utility com-panies. Gasification technologies offer poten-tial for converting wood into energy productsthat are easily transported and may be usedin conventional gas combustion equipment.

Wood may also be converted to liquid fuels,such as ethanol and methanol. In the event of

I U. S. Department of Commerce, Bureau of the Census, His-torical Statistics of the United States: Colonial Times to 1970(Washington, D. C.: U.S. Government Printing Office, 1975), pp.587-588.



an oil supply interruption or larger increasesin the price of petroleum , wood could back updomestic supplies of coal and other fossil fuels.

Wood has been the paper industry’s majorsource of raw m aterial for w ell over a centur y.

Paper may also be manufactured from a vari-ety of natural cellulose materials, including cot-ton, bagasse, and other agricultural crops, andfrom recycled waste paper, By removing ligninand other extractives and separating the strongindividual wood fibers through chemical ormechanical processes, paper may be formedinto a variety of prod ucts, ranging from tissuesand newsprint to construction board.

Some of the oldest and still major uses of wood are framing, sheathing, cabinetry, anda variety of semistructural and decorative pur-

poses in construction. The most notable newdevelopments in wood utilization involve re-ducing wood to smaller integral components,such as chips, strands, flakes, wafers, or fibersand reconstituting them into products with per-formance characteristics different and fre-quently superior to those made from solid nat-ura l wood. Recent developments includewaferboard and oriented-strand board (OSB)

mad e from a variety of species into compositesthat can substitute for conventional plywood.

Modern materials science also has made itpossible to combine different materials in a

way that can produce composite products withperformance characteristics superior to thoseof either of the parent materials, Wood andmetal have been laminated to p rovide not onlya more durable finished furniture panel, butalso one that resists cigarette burns by dispers-ing heat throu gh m etal foils. Comp osite panelsfaced with plastics are widely used for counter-tops, desktops, and tabletops. Plastic-impreg-nated papers are used for various types of packages that must resist or contain liquids.

In the futu re, wood maybe combined in very

different w ays at the fiber level to produce en-tirely new materials. For example, wood ma-terials could be extrud ed, molded , and formedinto complex shapes by combining wood fiberswith bind ers, adh esives, and resins. Wood alsomay be combined with other fibrous materialssuch as fiberglass or graphite to produce newhigh-strength, lightweight materials with spe-cial properties.

Wood as a Fuel

This section updates information on woodenergy use and summ arizes several importantaspects of wood energy explored in detail ina 1980 OTA report, Energy From BiologicalProcesses.

2

The rapid growth in coal and petroleum asenergy sources since 1870 resulted in a rapiddecline of wood’s contribution to total energyuse. Since the 1973 oil embargo, wood energyuse has grown rapidly, so that it again is thelargest use for wood by volume (fig. 2).

(government Printing office, 1980).


Figure 2.– U.S. Wood Energy Consumption, 1850-1980

3.0

2.5

2,0

1.5

1.0

Year

SOURCE Charles E Hewett, et al“Wood Energy in theUntted States, ” AnnualRewew of Energy, Jack M Hollander (ed ) (Palo Alto, Cal if AnnualReviews, tnc ), 1981




Wood-fuel consumption totaled 2,2 quadril-lion Btu (2.2 Quad s) in 19803—about 3 percentof U.S. energy u se (74 Quads).

4The forest prod -

ucts ind ustry accoun ted for 63 percent of 1980wood energy use.

5Nearly all the remaining

wood energy consump tion w as for residentialhome heating (fig. 3).

OTA estimates that energy accounted forabout 55 percent of the wood removed fromU.S. lands in 1980, the first year for which com-prehensive survey data is available (table 5). A

1981, op. cit.

partial explanation for the high proportion of fuelwood compared with other wood used in1980 is that demand for other forest productswas low due to recession. However, use of wood as a fuel has increased rapidly since the1%0’s, even during periods when demand forforest products was high.

The potential exists for significantly greaterwood energy production. OTA’s Energy From Biological processes assessment concludedthat w ood has the greatest potential to contrib-ute to the Nation’s energy sup ply amon g alter-native biomass energy sources. The studyfound that 4 Quad s/ yr of wood energy couldbe prod uced from wood by the year 2000 with-out significant Governmen t action. With incen-tives and improved forest management, asmuch as 10 Quads/ yr could be produced. Much

Figure 3.— Estimated Wood-Fuel Consumption, 1961-81

11



Ch.1—Introduction q 17

of this amount could be produced from byprod-ucts of wood processing, logging residues, andwoody biomass removed during thinning of

timber stands, stand conversions, and othermanagerncnt activities.

6

Industrial Wood-Fuel UseThe forest products industry consumed 81

mill ion ovend ry tons (81 million cords) of woodin 1981. Industrial wood energy consumptiontotaled 1.4 Quads of wood fuel, of which about1.0 Quad was consumed by the energy-inten-sive pulp and paper industry and the remain-der by the solid-wood-products sector. Thepulp and paper indu stry now d erives about half of its energy needs from w ood fuels and ligninbyprodu cts produced during pu lping,

7An esti-

mated 73 percent of the solid-wood-products

industry energy needs were supplied fromwood in 1981, up from 69 percent in 1978.

8

Most wood fuels used by the indu stry comefrom wood residues and processing wastes,rather than from trees specifically harvestedfor energy use, How ever, some firms now har-

vest wood for energy use, and some residuesare traded am ong businesses within the indus-try as a marketable commodity.

Continued increases in w ood-fuel use by theforest products industry are probable but willgrow more slowly in the future. The industrynow u ses over 96 percent of the wood y raw m a-terials that enter mills for either products orenergy (fig. 4). Opp ortun ities to increase w oodenergy further may depend on: 1) increased re-covery of woody materials at harvest, and2) capital investment in more energy-efficient

manufacturing processes.




Figure 4.—Timber Supply to and Product Output From Primary Processing Plants, 1976 (million cubic feet)

Supply to primaryprocessing plants

Domestic roundwood 12.815hardwoods 3,297 q

softwoods 9,518

Imported roundwood

+

100

and chips

SOURCE: T. Ellis and C. D Risbrudt. Unpublished manuscript



Ch. 1—/ntroduction q 19

Over the long term, as new facilities andtechnologies designed for energy conservationgradually are introduced, it is possible thatsome forest product firms will produce moreenergy than they consume, thus becoming net

energy producers. The pulp and paper indus-try already is a leader in cogeneration—thesimultaneous generation of useful heat andelectricity. The industry has the largest num-ber of cogeneration facilities among U.S. in-dustries and currently accounts for 29 percentof the U.S. cogeneration capacity, ranking sec-ond to the primary-metals industry in cogen-erated electrical power, g At one Maine pulpand paper mill, total self-sufficiency in electri-city reportedly has been achieved through anewly constructed biomass powerplant andcompany-operated hydroelectric stations. Sur-

plus power is sold to a local utility.10

Residential and Commercial Fuelwood Use

The U.S. Department of Energy (DOE) esti-mates that about 48,2 million ovendry tons(48.2 million cords) of wood was consumed inresidential heating in 1981.

11Residential fuel-

wood consum ption has at least doubled sincethe 1973 oil embargo, according to the DOEsurvey. Other indications, such as a fourfoldincrease in the use of wood stoves (from 2.6million in 1973 to nearly 11 million in 1981),

also suggest rapid growth in residential fuel-wood use

12(table 6).

Home fuelwood use may continue to in-crease, although probably not as rapidly as inthe 1970’s. Factors that will affect home fuel-wood use include: 1) price and availability of wood relative to alternative fuels, 2) proximityof fuelwood users to wood supplies, 3) home-owner willingness to cut and transport fuel-wood and maintain wood-burning stoves andfurnaces, and 4] introduction of technologicallysuperior wood-burning stoves and furnaces

Table 6.—Estimated Wood Stove Shipments andInventory (thousands)

Wood stoveYear shipments

1970 ... . . . . 2241971 . . . . . . . 220

1972 ... 2251973 ... . 2351974 ... . 4741975 ... . . 8531976 . . 8351977 . . . . . . 1,3021978 . . . 1,6811979 ... . . 2,1161980 . . . 2,116

Wood stoveimports

NANA

202080

280200240380437437

Wood stoveinventory

3,0792,866

2,7512,6302,7443,2953,8504,8076,0887,8689,531

1981 . 2,116 437 10,960

SOURCE U S Department of Energy Estfrnafes of U S Wood Energy Consurnp-t(on From 1949 to 1981 (Washington, D C Department of Energy 1982)

that burn wood more efficiently or conven-iently.

Comm ercial sector (nonforest prod ucts busi-nesses) wood-fuel use also is increasing, al-though currently it comprises less than 1 per-cent of total wood-fuel consumption. In manyareas, market prices for wood fuel currentlyare competitive with fuel prices for oil, natu-ral gas, and coal. Commercial wood-fuel usemay continue to grow, especially in areas likethe South, which have abundant wood sup-plies. Some States actively encourage commer-cial use of wood fuels. The Georgia ForestryComm ission, for examp le, finances wood -fuel

demonstration projects in hospitals, schools,and other public institutions.

13

In a few instances, public utilities have estab-lished wood -fueled central electric-generatingstations, as in Burlington, Vt., and Eugene,Oreg. Limitations on wood-fuel generating sta-tions include large capital costs and difficultiesin assuring wood supplies from timbershedsat economic transportation distances fromplants.

Secondary Fuels and Chemicals From Wood

Almost all wood fuels are directly burned.A variety of long-established and emerging




technologies can process wood and wood-based residu es into “second ary fuels” (gas, liq-uid , and solid). Similar technologies and proc-esses can be used to produce chemical feed-stocks for the m anu facture of a high p roportion

of chemicals, plastics, and other p roducts nowproduced from petroleum (fig. 5).

Bioconversion processes such as sacchari-fication, fermentation, and gasification wereused to p rodu ce fuels and/ or chemicals com-mercially on a minor scale during both WorldWar I and World War II, but they w ere not ableto compete with petroleum fuels and petro-chemicals in peacetime,

14Recent developments

have focused renewed attention on prod uctionof secondary fuels and chemicals from wood.The technologies for conversion of wood andother forms of biomass to energy and chem-

icals are discussed fully in OTA’s Energy From Biological Processes repor t .

15

The potential for w ood to be u sed as an alco-hol fuel is discussed in DOE’s Alcohol FuelsPolicy Review.

18If used on a widespread basis,

methanol and ethanol could offset somewhatU.S. gasoline consumption (about 101 billion

— ... -Iq’rhe history of wood chemical and secondary fuel use through

World War II is discussed in Egon Glesinger, The Corning Age

of Wood (New York: Simon & S[;huster, 1949). Another book byGlesinger, Nazis in the Woodpile: Hit~er’s Plot fi)r Essential Ra~%’

Material (Indianapolis; New York: Bobbs-Merril, 1942) discusses

the military and strategic importance of wood as a fuel and chem-ical to the Third Reich,IsEnergy From Biological Processes, vol. II: Technical and

Environmental Analyses (Washington, D. C.: office of Technol-ogy Assessment, 1980),ISU,S, Department of Energy, Report of the Alcohol Fue/s pol-

ic~ Review (Washington, D. C.: U.S. Government Printing Of-fice, 1979].

gal in 1981).17

How ever, there are econom ic dif-ficulties in commercializing processes to con-vert woody biomass to alcohol.

Wood curren tly is used to prod uce silvichem-icals valued at over $5OO million per year.

Silvichem icals include naval stores (oleoresins,tall oil, turpentine, rosins, and the like) andchemicals derived from pulping byproducts,such as lignin products, vanillin, DMSO, anda variety of other useful substances,

Use of wood as a substitute for petroleumfeedstocks is technically possible but will de-pend on the price of petroleum and coal (whichcan also be used as a petrochemical substitute)and capital expenditures for new plant con-struction. Coal is widely viewed by the chem-ical industry as a more likely short-term sub-

stitute for petroleum feedstocks than wood.Nonetheless, evolutionary growth in woodchemical use is probable—especially whenwood can be used in less highly processedforms or to produce chemicals not readilyderived from coal or petroleum.

Lignin chemistry is one p romising area of re-search.

18Lignin has a complex structure that

makes it difficult to process, but, left intact, itcan be used in plastics, adhesives, and variousother compou nd s, About 3 percent of the ligninbyproducts produced d uring pu lping are recov-ered for production of chemicals; the rest isburned for energy.

17Figure derived from Monthly Energy Review: November

1982, op. cit., p. 36.‘BHenry J. Bungay, “Biomass Refining, ” Science, vol. 218, Nov.

12, 1982, p. 643.

Wood Technology and the

While an ext raord inary range of wood prod- of the

Resource Base

national materials mix, economics anducts exists, they must compete with other ma- market forces generally determine which ma-

terials for their share of an often highly spe- terial is predominantly used for any specificcialized market. Just as wood can be substituted purpose, But other factors, including existingfor many other materia ls , those mater ia ls can plant equipm ent and capita l investment,substitut e for wood in some app lications, with energy consumption, raw material availabilitylittle change in p roduct performan ce. In term s and secur i ty of supply, and inst i tut ional



Ch. /—lntroduct/on q 21

1 Separation via I

Wood

- 1t

Organic compounds

- Methane






considered worthless. The introduction of panel products and hardboard opened avenuesfor wood from limbs, branches, treetops, roots,hardw oods, and even dead or defective woodand bark. New technologies for paper manu-facture offer enormous potential for using

hardw oods to prod uce strong pap ers for pack-aging and communication, Even in lumber andplywood manufacture, which still depend onwood cut from the trunk of the tree, the abilityto utilize smaller logs has expanded signifi-cantly. Possibilities also exist for increased useof hardw oods. Regardless of future levels of de-man d, wood -utilization technology has the po-tential to ease pressu res on the timber resou rcebase (table 7).

Significantefficient end

The futureefficiency inon research

opp ortun ities also exist for moreuse, particularly in construction.

It maybe possible to reduce the amount of lum-ber and panel products used (through im-proved integrated structural design) withoutadversely affecting the quality and strength of the structure. Present commercial techniquescould red uce wood consump tion in framing by

nearly one-third, for example.

Recycling technologies also may extend thetimber resource base. Recycled wastepaper canreduce not only the amount of virgin wood fi-ber needed for pu lp and paper m anufacturing,but also the amount of energy consumed in thepulping process. Little solid wood is reusedcurrently, but with appropriate designs andnew methods of fastening, it also might berecycled.

Research and Development on the Use of Wood

uses of wood and the degree of wood utilization largely dependand development (R&D). Three

major institutional groups in the United Statesare involved in R&D on the u se of wood: 1) theFederal Government, which funds as well asperforms R&D; 2) the forest industry, which isinstrumental in developing products and im-

proving manufacturing processes; and 3) aca-demic institutions that conduct training andbasic research. Each plays an important rolein the activities that lead to the invention, de-velopment, and eventual commercialization of wood products and processes.

The relative proportions of ind ustry an d Gov-ernment funding for al l R&D in the UnitedStates have sh ifted in the past 30 years. In th e1950’s and 1960’s, the Federal Government wasthe m ajor fund ing sour ce for R&D, but the gapbetween industrial contributions and Govern-ment funding began to narrow in the early1970’s, Industry outspent the Government forthe first time in 1980. The National ScienceFoundation (NSF) estimates that over $69 bil-lion was expended for all R&D in the UnitedStates in 1981. Forty-nine percent of the ex-

penditures were made by industry, while 47percent came from Federal agencies. The re-maining 4 percent originated from found ationsand other private sources.

Current trends suggest that indu stry fund ingas a percentage of total funding will continueto advance, while the Federal sector’s contri-bution will decline.

19The funding structure for

research alone (excluding the developmentfunction) is the reverse, how ever. In 1981, over53 percent of the expenditures for basic andapplied research were derived from the Fed-eral Government, while industry contributedapproximately 37 percent. z” The private sectoractually performed more of the total R&D un-dertaken in the United States than it funded,because some private research was Govern-ment supported. In 1981, 71.2 percent of theR&D (measured by d ollars expended) was per-formed by industry. The Federal Government

19J. Eluga, Probable l.eLels of R&D Expenditures in 1982: Fore-cast and Anal~’sis (Columbus, Ohio: 13attelle Columbus Labora-tories, 1981), p. 2.ZONationa] Sclerlce Board, Science indicators 1980 (Washing-

ton, D. C.: .National Science Foundation, 1981), p, 253,

, ~~• 1 -r



Table 7.—Status of Selected Technological Developments in Wood Utilization

. .Pulp and paper industry: Pressurized groundwoodpulping (PGW)

Chemithermomechanical pulping

(CTMP)

Hardwood chemimechanicalpulping (CMP)

Press drying paper

Pyrolytic recovery

Organosolv pulping

Oxygen pulping

Solid wood products: Best opening face

Saw-dry-rip

Edge glue and rip

Parallel laminated veneer

Rationale for or advantage of technology ——.

End-use product Status of commercial izat ion Wood type

Reduced energy requirements and higherquality paper in comparison with traditionalgroundwood pulping processes; less kraftpulp needed for mixing

Reduced energy requirements; higher quality

paper than in traditional mechanical pulpingtechnologies because long fibers are leftrelatively intact; less kraft pulp needed formixingPermits utilization of low-value hardwoodssuch as red oak and poplar; reduced energyconsumption in comparison with othermechanical techniques; less kraft pulpneeded for mixingPermits utilization of hardwoods in produc-tion of linerboard that is superior in qualityto conventionally dried softwood kraft paper,except in tear strength; reduced energy re-quirements and chemical processing needsReduced energy requirements in recoveringpuIping chemicalsReduced energy requirements; expandedhardwood utilizationOxidation of pulping liquors reduces needfor bleaching chemicals and facilities; mayreduce need-for water polIution control ex-penditures due to less chlorine in bleaching

Higher lumber recovery factor; permitsproduct yield improvements of 4 to 21 0 / 0

Higher lumber recovery reduces defects inproduct by 19 to 87°/0Higher recovery of product, higher lumberqualityPermits higher recovery of lumber fromlogs, improves lumber quality; fasterprocessing at the mill

Newsprint, printingpapers

News print

pages

Newsprintpapers

Linerboard

, printing

printing

Process efficiency

Process efficiency

Process efficiency

Lumber uses

Lumber uses

Lumber uses

Lumber and timberuses

Five mills worldwide as of 1980; Softwoods15 mills ordered (4 in U.S.); rapidgrowth expected

Installed at some thermo-

mechanical pulpmills

Two small mills in U. S.; rapidexpansion possible

Feasible, but commercial-scalefacility has yet to be developed

Demonstrated

Yet to be demonstrated;possible in next two decadesYet to be demonstrated;possible in next two decades

Mill-tested but not widely used

Used by some mills, but notwidely acceptedNone

Some manufacturing currentlyin production

Softwoods

Hardwoods

Hardwoods

Any

Hardwoods orsoftwood

Primarilysoftwoods

Hardwoodsand softwoodsHardwoodsand softwoodsHardwoodsand softwoods



.Ch. 1 —Introduction q 25

I In

(uE

o-1

Q

I

co

0

c

uo03

.




conducted 13 percent; universities and col-leges, 12 percent; and the balance was per-formed by miscellaneous nonprofit organi-zations.

Within the forest products sector, the struc-

ture of R&D funding is obscured by the lack of reliable and sufficiently detailed informationon Government and industry outlays for wood-utilization R&D. NSF reports an estimated ag-grega te expenditur e in 1979 of $148 million forlumber and wood products R&D and $454 mil-lion for pulp and pap er prod ucts R&D, but d oesnot provide a breakdown of funding by con-tributor.

21Funding levels for R&D within the

forest products sector remained about the samefor 1977 through 1979, wh en m easured in con-stan t d ollars. Between 1970 and 1980, R&D ex-penditures for lumber and wood products grew

app roximately 62 percent, and p ulp an d paperR&D increased 70 percent, when measured inactual dollars.occurred in thetion during the

211t)id., p. 279.

However, little real growthR&D budget because of infla-past decade.

Federal Government R&D Activities

Wood-utilization research conducted by theFederal Government is concentrated in the For-est Service of the U.S. Department of Agricul-ture (USDA), In fiscal year 1981, the Forest

Service funded over $16.8 million of in-housewood science and utilization research, about72 percent of which was performed at the For-est Products Laboratory (FPL) in Madison, Wis.The balance was conducted at the regional For-est Experiment Stations and at various re-search centers throughout the United States,(University research funded by the Forest Serv-ice is discussed in a following section,) TheForest Service tend s to concentrate its in-housewood science and utilization research on proj-ects that generally are regarded as beneficialto the United States—i.e., that are long-term,high-risk, and therefore unlikely to be under-taken by the private sector,

FPL’s fiscal year 1981 R&D program in-cluded 18 activities involving approximately 97scientist-years of effort, funded for $12,1 mil-lion (table 8). Its fiscal year 1982 budget wastargeted at $13.7 million to support an effortof 104 scientist-years. The laboratory’s researchefforts are centered on the p rotection of wood

Table 8.—Funding and Man-Year Commitments by Activities at the U.S. Forest Service,

Forest Products Laboratory, Madison, Wis.: Fiscal Year 1981

Funds Scientist-

Activity (thousand dollars) Percent years —

Protection of wood in adverse environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $ 1,178.5Engineered wood structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,149.1

Wood fiber products and processing development . . . . . . . . . . . . . . . . . . . . . . . . . . . 942.9

Engineering properties of wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888.3Improved chemical utilization of wood ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 869.1

Structural composite products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 840.5

National timber and wood products requirements and utilization economics . . . 822.7

Improved adhesive systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791.0

High-yield, nonpolluting pulping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 758.0

Quality and yield improvement in wood processing . . . . . . . . . . . . . . . . . . . . . . 690.0

Criteria for fiber-product design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., . . . . . . . 641.0Microbial technology in wood utilization. ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525.0

Improvements in drying technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .503.7

Fire-design engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371.0

Engineering design criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370.0

Corrugated-package engineering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341.5

Center for anatomy research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293.0

Pioneering research unit in descriptive wood anatomy . . . . . . . . . . . . . . . . . . . . . . 141.0

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $12,116.3

SOURCE Cooperative Research Information Service (CRIS), U S Department of Agriculture —

9.8

9.5 7.8 7,3 7,2

6.9 6.8 6.5 6.2 5.7

5.3 4.3 4.2

3.1

3.02.82.41.2

100.0

8

6

5

7

7

7

8

6

6

6

5

4

5

4

4

4

4

1

97




from decay and insects and on the engineer-ing of structural wood products, wood fiberproducts, and manufacturing processes. Ap-pr oximately 35 percent of FPL’s bud get is usedfor fundamenta l research—e.g., properties andanatomy of wood—and 65 percent is used forapplied research. The level of research efforthas been approximately the same since 1978,based on constant dollars expended. From 5to 10 percent of the laboratory’s annu al bud getis devoted to cooperative research with aca-demic institutions.

In addition to research centered at FPL, theForest Service supported an R&D program of $4.7 million and 40 scientist-years in fiscal year1981 at the research centers of the region al for-est range and experiment stations (table 9).Most of this research centered on the utiliza-

tion of hard wood species and on the econom-ics of improving the performance of the re-gional wood products industries,

R&D on w ood energy and wood as a substi-tute for petroleum products is conducted by

DOE at its national laboratories, although fund-ing for these activities was reduced in the fiscalyear 1982 and 1983 budgets. At its peak in fiscalyear 1981, DOE spent $11 million on R&D re-lated to wood combustion, gasification, and liq-uefaction. This work is funded in fiscal year1983 at $2.2 million. Other research related towood science and utilization, such as r esearchon toxic preservatives and adhesives, may oc-cur incidentally to the missions of other R&Dagencies, but its size in relation to the total Gov-ernment effort is small.

R&D in Academic Institutions

Academic research plays a unique role incomplementing the research in wood scienceand utilization undertaken by industrial and

Government laboratories. Funding for aca-demic research in fiscal year 1981 was approx-imately $9.5 million (table 10). Less than one-third of the academic research bu dgets in 1981came from the Federal Governm ent; State andindustrial contributions accounted for 71,6 per-

Table 9.— 1981 Funding and Scientist-Years by Activities at the U.S. Forest Service Experiment Stations

Actlv ity

Improving wood-resource harvesting and

utilization . . . . . . . . .

New and improved systems, methods, andtechniques for processing hardwoods ... .

Regional economics of forest resources ...

Low-grade hardwood utilization . . . . . . . . . . . . .

Timber quality and product-yield potential ofWestern softwood resources ., ... ... .

Developing more productive markets and uses

for forest resources of the Central and

Southern Rocky Mountains ... . . . . .

U t i l i z a t i o n o f S o u t h e r n t i m b e r. . . . . . . .

Wood products research . . . . . . . . ...

Process ing Sou thern woods . . . . . . . . .

Total ., . ... . ... . . . . . . .

FundsLocation (thousand dollars) Percent Man-years

—

Forest Sciences

LaboratoryMissoula, Mont. $ 447,0 9.5 4.0

Carbondale, Ill, 361.0 7.7 3.0Duluth, Minn. 512.0 10.9 4.1

Princeton, W.Va. 418.5 8.9 2.1

Pacific NorthwestRange Exp. Sta.Portland, Oreg. 573.3 12.2 5.0

Ft. Collins, Colo. 286.8 6.1 4,0Southern Forest

Exp. Sta.

Athens, Ga. 594.2 12.7 6,0Southern Forest

Exp. Sta.Athens, Ga. 500.3 10.7 6.0

Alexandria, La, 998.9 21.3 6.0

$4.692.0 100.0 ‘40.2SOURCE Cooperatlve Research Information System (CR IS) U S Department of AgrlcuIture ‘

- -




Table 10.— Funding of Wood Utilization R&D Performed by U.S. Academic Institutions in Fiscal Year 1980

Source (thousand dollars)

Mclntyre-Activity Stennis

Structural panels (including plywood andcomposites) . . . . . . . . . . . . . . . . . . $ 278.1

Economic analysis and data/information . . . . . . 76.2Properties and performance of wood and

wood products . . . . . . . . . . . . . . . . . . . . . 376.0Energy and chemical production from wood. 181.3Protection, preservatives, and coatings . . 78.8Pulp and paper technology. . . . . . . . . . . . . . . . . . 125.6General and miscellaneous wood utilization . . 42.6Adhesives and bonding . . . . . . . . . . . . . . . . . . . . . 109.0Structural design and fasteners. . . . . . . . . . . . . . 78,1Drying and moisture characteristics ... . . . . . 119,1Composite and laminated beams/lumber. . . . . . 54.8Sawmill design and process technology . . . . . . 22.7Wood anatomy and fiber quality . . . . . . . . . . . . . 40.7Sawing and machining . . . . . . . . . . 3.2Whole-tree chipping and chip processing . . . . 14.8Species utilization . . . . . . . . . . . . . . . . . . . . . . 22.0

Total ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $1,623.0Percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.0

Other Federal Non-Federal

$ 103.7 $1,505.1

165,5 1,076.8

80,7257,4

94.568.047,238.852.046.9

5.923.4

016.7

61.218.6

610.4458.4523.5394.8399.2338,1335,9292,0233,6164.0158.5163.0106,138,4

Total Percent

$1,886.9

1,318.5

1,067.1897.1696.8588.4489.0485.9466.0458,0294,3210.1199.2182.9182.179.0

19.9

13,9

11,29.47,36.25.25.14.94.83.12.22.11,91.90.9

$1,080.411.4

$6,797.871.6

$9,492.3100.0

100,0

cent of the total. Major emphasis was placedon R&D related to composite structural pan els(19.9 percent), economic analysis and woodproducts data (13.9 percent), and propertiesand p erformance of wood and wood p rodu cts(11.2 percent).

Within the federally funded portion of theacademic research budget, 17 percent of thefunds originate from McIntyre-Stennis Act pro-grams (76 Stat. 806), which are administeredby the USDA’s Cooperative State ResearchService. The Forest Service, NSF, DOE, andother agencies provided 11 percent of the totalacademic bud get devoted to w ood science andutilization research in 1981. The remaining 72percent came from State and ind ustry sou rces.

While the prop ortions of R&D fun ds contrib-uted by industry and the States are not iden-tified by USDA in its Cooperative Research In-formation System (CRIS) (table 10), a recentsurvey of forest-prod ucts research in the South

suggests that industry contributed approx-imately 15 percent of the academic researchfunds in that region, with the States account-

SOURCE Cooperative Research Information System (CRIS), U S Department of Agriculture

ing for 47 percent of the fund s expended ,22

Theremaining 38 percent was funded by variousFederal agencies. The Southern colleges anduniversities included in the survey receivedhalf (48.8 percent) of the total wood science andutilization R&D funds provided to all U.S. aca-demic institutions in 1981. To the extent thatthe South reflects the national situation, theStates appear to be the major funding source

for wood-utilization R&D at colleges and uni-versities.

Industrial R&D

Because of the proprietary nature of muchof the forest products industry’s R&D and thereluctance of the private sector to disclose R&Dbudgets, a detailed assessment of industrialR&D is not p ossible, althou gh the informationavailable suggests that major emphasis withinthe indu stry is aimed at process improvementrather than basic research.

ZZK. Thompson , s ta tu s of Forest products Research at public

Institutions in the South (Mississippi State, Miss.; MississippiForest Products Laboratory, 1982), p. 12.



Ch. 1 —Introduction q 29

In terms of both dollars and scientist man-years allocated, the forest products indu stry isthe largest supporter of wood science and uti-lization R&D in the United States. NSF esti-mates that in 1979 the industry spent a totalof $148 million on lumber, wood products, andfurnitu re R&D, and $454 million on pap er andallied products R&D, Of the funds expendedby the pulp and paper industry, 4 percent werefor basic research, 25 percent for applied re-search, and 71 percent for product and proc-ess developm ent. Accord ing to NSF, the solid-wood-products manufacturers spent 68 percentof their R&D budgets on d evelopment, 28 per-cent on applied research, and 4 percent onbasic research. ’s

A recent McGraw-Hill survey estimated thepu lp and pap er indu stry’s 1980 R&D expendi-

tures at $508 million and its 1981 expend ituresat $584 million,24 An estimated 40 percent of the R&D funds were spent for improving exist-ing products, 27 percent for developing newproducts, and 31 percent for developing newmanufacturing pr ocesses, Indu stry analysts ex-pect greater emphasis on new processes in thefuture and a slight increase in emphasis on newproducts by the pulp and paper industrythrough 1985,

While actual-dollar R&D expenditures by theforest products industry increased at a signif-

icant rate betw een 1969 and 1979 (fig. 6), fund-ing remained nearly level, measured in con-stant dollars. Between 1977 and 1981, R&Dexpenditures by the pulp and paper industry(fig. 6) increased approximately 10 percent an-nually in actual dollars, compared with anaverage ann ual increase of 15 percent in all in-dustries.

25

Z~I n~ust r} Stllr] ie$ Groul), Science Resources Studies Hi.gh - iight.s: Reaj Growth in Industrial R&D Performance Continues

in 1979 (Washington, D. C.: National Science Foundation, 1981),NSF 81-313, p. 2,Zq~C[)nomiCs D~partm~nt, ,?Yth Annual McGra w’-Hill .!urtreJr

of flusine.s.s Plans for Research and Development Expenditures(New York: hlc~raw-}lil] Publications Co., 1982], p. 8.

25” A Research Spending Surge Defies Recession, ” Business

I%reek, July 5, 1982, p. 68.

Historical Research and DevelopmentExpenditures

160

150 “R&D expenditures by the

140 “ lumber and furniture industry130 — /

(1972)

40 “

30

2010 I I I I I I I 1 I I

SOURCE Economics Department, 27fh ,4rmua/ McGrawWI// Survey of Bus/nessHans for Rese@rch and Development Expenditures (New York McGrawHIII Publlcatlon Co , 1982)

The manner in which the forest products in-dustry reports R&D activities may mask thenatu re of ind ustrial R&D progr ams, For exam-ple, many of the large pulp and paper pro-ducers and integrated forest products firmshave extensive forest management researchprograms in addition to wood-utilization R&D.NSF, the Federal Trade Commission, and theSecurities and Exchange Commission reportaggregate R&D fund ing and do n ot report theproportion of corporate funds devoted to for-

est management versus that spent on wood-utilization R&D. For this reason, the R&D fund-ing statistics quoted in this report include for-est man agement research; therefore, the actualamoun t spent on wood utilization R&D prob-ably is less than reported.

Other industrial sectors also perform R&Dthat is used by the forest products industry;likewise, some forest products industry R&Daffects other industries. The major R&D effortrelated to wood utilization is funded directlyby the forest products industry. A relatively

small proportion of the total wood-utilizationR&D effort appears to come from machinerysuppliers, coating (paints) and resin manufac-turers (chemicals), and users of wood products.It appears that most R&D performed by lumberfirms is specifically u sed by the lum ber indus-





Chapter II

Solid Wood and Panel Products



Chapter II

Solid Wood and Panel Products —

Summary and Conclusions

33



34 qWood Use: U.S. Competitiveness and Technology

Introduction

Panels have been replacing lumber in con-struction for the past three decades. Plywoodhas been prod uced commercially in the United

States since the turn of the century, but ply-wood manufacture, like lumber manufacture,relies on large-diameter, high-quality softwoodtimber, which is becoming increasingly scarce.As a result, technologies for panel manufacturehave concentrated on expanding the resourcebase, Newer panels, made from wood wafersor strands, can be made from small logs, resi-dues, and hardwoods and can substitute forplywood in construction applications, Twonew p anel produ cts, waferboard and orientedstrand board (OSB), already have capturedsome plywood markets and are expected to

continue expanding. Most new, planned panelmanufacturing capacity in the United Statesis in OSB or waferboard. Because these prod-ucts can be made from hardwoods and fromlower quality softwoods than can plywood,production facilities are located in the GreatLakes States and North east, closer to construc-tion markets and suitable wood supplies.

Advances in plywood manufacture also haveexpanded small log utilization through im-provements in log peeling technology. Otherchanges in plywood production include in-

creasing automation and improving dryingprocesses to redu ce energy u se, accelerate dry-ing, and produce more stable panels.

These improvements in primary manufactur-ing have been aimed principally at expandingthe usable resource base: increasing the abil-

ity t o use hardwoods and a greater proportionof the tree. Increasing the efficiency of wooduse in construction also has potential to redu cethe pressure on domestic timber resources, par-ticularly the softwoods. Engineering analyseshave shown that many houses are overbuilt, orcapable of withstanding far greater stressesthan required by housing codes. More carefulmatching of construction members—framingand sheathing—to the engineering require-ments of the structure could help reduce theamount of wood required to build a home.

New construction technologies also haveshown some promise in reducing wood re-quirements. In particular, the use of factory-mad e wood tru sses for floor, wall, ceiling, androof framing reduces lumber requirementsand, at the same time, speeds up housing con-struction and reduces labor costs. Factory-made housing components, such as wall panelsthat combine framing and sheathing, also canreduce wood waste and construction labor re-quirements. Construction technologies, how-ever, are slow to change, and the impact of these technologies on wood utilization is un-

likely to be significant in the short run,

Profile of the Lumber and Panel Products Industry

As the world’s largest consumer of industrialwood

l(including pulp), the United States uses

over one-fourth of the world’s timber products,more than half of which is lumber, plywood,and veneer, In 1979, the United States con-

sumed approximately 50 million air-dry tonsof lumber, 12 million tons of plywood , and 10million tons of panel products, accounting fornearly half the U.S. consumption of industrial

1 Industrial wood includes all commer(; ial roundwood productseY(:ept fuelwood”

roundwood.2In add ition, the United States pro-

du ces over 20 percent of the w orld’s softwoodlumber, 15 percent of its hardwood lumber,nearly 45 percent of its plywood, 1.5 percentof its particle board, and 40 percent of its

fiberboard,’— — —2U S DA Forest Service, U.S. Timber Production, Trade, Con-

sumption, and Price Statistics, 1950-1980, Miscellaneous Publica-tion No, 1408, 1981.3Roger A. Sed jo and Samuel J. Radcliffe, Postwar 7“rends in

1 l,s, Forest products Trade: A Global, National, and Regional

l’iettr, Research Paper R-22 (Washington, E).(; ,: Resources Forthe Future, 1980).






du stry, produ ction of lumber and panel prod-ucts follows the general pattern of housingstarts. In 1976, construction-related activity ac-counted for three-fifths of the lum ber and two-thirds of the plywood consumed in the UnitedStates.

5New home construction is the major

market for lumber and plywood, although res-idential upkeep and improvement and n onres-idential construction also consume significantamounts. Periodic depressions in the housingindustry create soft mar kets that g reatly affectlumber, plywood, and panel demand, resultingin mill closures and curtailments in pro-duction.

Other major uses of wood—manufacturingand shipping—account for 18 percent of thelumber and 10 percent of the plywood con-sumed in the United States. Furniture making

accoun ts for the bulk of the wood used in m an-ufacturing, and pallet manufacturing is the major market for wood in shipping. A summaryof lum ber and p anel products use is shown intable 11.

Industry Size and Distribution of Production

The lumber and forest products industry con-sists of 35,000 establishments and employsnearly 700,000 workers, or nearly 4 percent of those employed in U.S. manufacturing.

6Ma-

jor wood products manufacturing sectors of

the lumber and wood products group em-ployed 219,000 people in 1981 (table 12).

Although the indu stry is dominated by a fewlarge firms, some segments are made up of small, competitive firms (table 13). The lum berindustry is the most competitive component of the lumber and wood products sector. Of its8,184 establishments, 80 percent employ fewerthan 21 people, ’ Over 50 percent of the U.S.lumber output is produced by 10 percent of themills (table 14).

5USDA E’orest Service, An Analysis of the 7’in]ber Situation

in the United States 1952-2030, review draft, 1980.‘U.S. Department of Commerce, Bureau of Industrial Econom-

ics, 1982 U.S. Industrial Outlook for 200 Industries With Pro- jections for 1986 (Washington, D. C.: U.S. Government PrintingC)ffi[;e, January 1982].

Lumber production is concentrated in theSouth and the West, where most of the soft-wood, sawtimber growing stock is located.While the South contains more sawmills thanthe West, its mills generally are mu ch smaller.The West prod uces over two-third s of the lum-

ber output (table 15). Mills in the North andEast produ ce only 6 percent of the annu al lum-ber output.

The plywood and panel products industriesare more concentrated than th e lumber indu s-try and have fewer mills. Their 232 softwoodveneer and plywood mills, 366 hardwood ve-neer and plywood mills, and 68 particleboardmills employ about 77,OOO people,

Because construction, like lumber, dependson high-value, large softwood logs, the Southand West are major plywood-producing re-

gions. In 1979, the South and West produced42 percent and nearly 47 percent, respectively,of [J. S. plywood man ufactured; the remaind erwas produced in the northern Rocky MountainStates. Plywood production has been shiftingto the South since the early 1960’s, primarilybecause of its lower wood prices.

In 1979,96 percent of th e panel m anu factur -ing capacity was in plywood. A few plywoodplants also produced corn-ply, a structuralpanel with veneer faces and a particle core.Only two waferboard plants existed in the

United States in 1980, although there wereplans to ad d several more p lants between 1981and 1983 in the Great Lakes States or Maine.

8

Unlike the plywood and lumber industries,which require sawtimber-quality trees, com-posite structural panels use hardwoods; small,lower quality trees; and, occasionally, millwaste. The nonplywood p anel products indus-try, therefore, probably will continue to be con-centrated in the East, particularly in the GreatLakes States, and the Northeast, where majorconstruction markets are located,

—.—

7See note 6.‘Kidder, Peabody and Co., 1 nc., “Corn-ply, Waferboard, Or]-

ented Strand Board: Revolution in the Structural Panel Market?”,I)e(; 24, 1980







.

Ch. //—Solid Wood and Panel Products q 3 9

Use of Solid Wood and Panel Products

Three sectors of the lum ber and wood prod -ucts industry group are among the 45 rapid-growth industries whose compound annual

growth rates ranged from 6 to 20 percent be-tween 1972 and 1978: 1) wood pallets and skids;

2) wood kitchen cabinets; and 3) structuralwood members, such as laminated or fabri-cated trusses, arches, and other structuralmembers of lumber (not including standardsoftwood or hardwood dimension lumber). Al-though three-fourths of the rap id-growth indu s-tries attributed their success to new productdevelopment, of the three rapid-growth, wood-using industries, only “structural wood mem-bers” listed new products as a key growth fac-tor.

9Two of these new products, laminated

beams and roof trusses, actually were intro-duced into the market during the 1950’s.

Two new developments, however, are trussesthat can be used to frame entire houses andtechniques for producing laminated beams, joists, and girders of many sizes and shapes.Such large, laminated beams and arches, fre-quently bent into specified shapes, have pene-trated new mar kets, includ ing the constru ctionof large indoor sports arenas, convention cen-ters, and domes. Trusses, on the other hand,have not opened man y new markets for wood

products but have replaced larger dimensionlumber in light frame construction.

Other new produ cts recently introdu ced in-clud e various typ es of fiberboard and particle-board. A medium-density fiberboard (MDF),first produced in the mid-1970’s, has rapidlyexpanded into furniture corestock marketsformerly held by particleboard an d other pan-els. New types of particleboard include panels

fI [ I,s, [)~;~):l rl m f ! n t of (;0 m m Crc e, op. [: it.

made from strands (thin shavings or slivers of wood), flakes, or wafers, sometimes with ve-neer faces. These panels, first introduced in

Canada and the United States in the mid-1970’s, now strongly compete with softwoodplywood for structural use.

The amount of lumber used in homes has re-mained fairly constant for several decades,while the amount of plywood and structuralpane ls has inc reased . Pane ls for sheathing

(walls) have replaced sheathing lumber. Now,however, plastic-foam sheathing is replacingwood-based sheathing in some markets owingto its superior insulation properties. New pane]products are expected to replace plywood for

sheathing and underpayment (floors). The sametrend seems to have occurred in furniture man-ufacturing, where plywood and particleboardhave replaced lumber as furniture corestock and have themselves been replaced by MDF.

Shipping pallets have been replacing woodboxes and containers for materials handling.New types of pallets, made with plywood deck-ing, particleboard , or MDF, are expected to re-place some of the existing hardwood lumberpallets in the future.

In general, new produ cts introduced by the

lumber and panel industries replace otherwood products already in use, rather than com-pete with other materials. If the forest indus-try hopes to expand the uses of wood, it prob-ably will have to develop new p rodu cts that cancompete with steel, aluminum, plastics, andother structural materials, rather than productsthat simply replace other wood products. Thisprobably will require greater interaction of other professions involved in the constructionindustry: building code offices and testing or-ganizations, architects, and building contrac-tors.




Industry Trends and Potentials

Most of the wood (over 96 percent in 1976)entering mills for primary processing is usedas products or as an energy source. Wastes

from lum ber and veneer or plywood mills areused for fuel or for manufacturing particle-board, composite panels, pulp, or paper.

10

While the wood products industry as a wholeis quite resource-efficient, opportunities for in-creasing efficiency still exist in three areas:1) increasing the recovery of high-value pri-mary products (lumber, plywood, particle-board); 2) expanding the use of underutilizedspecies, wood residues, and defective materialsnow left in the woods after harvest; and 3) in-creasing the efficiency of the end use of woodproducts.

Product Recovery

The efficiency of product recovery in lumbermills, described as the “lumber recovery fac-tor” (LRF), is measured by the number of boardfeet (12 inches by 12 inches by 1 inch) of lumberrecovered from a cubic foot of log. Because thenominal dimensions of finished lumber arelarger than the actual dimensions (a standardfinished 2- by 4-inch stud, for instance, meas-ures app roximately 1½ by 3½ inches), there areactually 16, rather than 12, board feet of lumber

in a cubic foot of solid wood,

Lumber recovery efficiencies in the UnitedStates currently average about 41 percent (LRFof 6.5). With new technologies and processes,the product recovery in lumber mills couldreach 60 to 88 percent (LRF of 10.0 to 13.0) formedium-sized logs.

11The product recovery in

plywood mills averages around 50 percent.New processes may improve efficiency slightlyby enabling the use of materials which at onetime were rejected as veneer stock. Finally,

wood for structural panel manufacture, Engineered panel prod-ucts require roundwood to produce high-qua] ity flakes of specified dimensions.

“Jerome Saeman, “Solving Resource and Environment Prob-lems by the More Efficient Utilization of Timber, ” Report of thePresident’s AdL’isorJ’ Panel on ‘rimber and the L’ n L’irunrnent,

April 1973.

product recovery in particleboard, compositepan el, and fiberboard mills approaches 75 per-cent on a weight basis.

12Improvements are

aimed at reducing processing time, improvingpanel quality, and increasing automation.

Since 53 percent of the wood entering saw-mills is used to manufacture particleboard, fi-berboard, paper, or energy, any increase inlumber outpu t for one use tends to redu ce theamount of wood available for other uses. Thesetradeoffs can be imp ortant in ba lancing lum berrecovery efficiency with other production proc-esses, including the need for energy.

Forest Resource Use

The forest products industry continuallyseeks ways to use a larger proportion of thewood y biomass left in the forest after the mar -ketable material is removed , Softwoods, whichare intensively utilized, could provide evenmore wood mater ia l i f the tops, l imbs,branches, and d ead, dying, or defective timberwere used. The volume of dead and dying tim-ber in 1977 was estimated to be 21 ft

3—almost

double the amount harvested—and the volumeof residues left from logging came to 8 billionft

3in 1976. New products and technologies,

particularly in composite panel manufacture,could use these materials, although the amountthat would be economically recoverable is un-known. As second-growth timber replaced oldgrowth and utilization standard s changed, thelumber and panel industries adjusted theirprocesses to use smaller logs. This trend prob-ably will continue, Moreover, as the price of high-quality softwood stum page increases, ad-vances in lumber processing and the develop-ment of composite panel products have in-creased the industry’s ability to use the vast andlargely untapped U.S. hardwood species.

IZ1~f;rsonal (communication w ith John Haygreen and Ja}’ Jo bn -

son with OTA staff member Julie K, Gorte.



Ch. I/—So/id Wood and Pane/ Products q 4 1

Efficient End Use of Wood Products

The greatest opportunity to increase the ef-ficiency of wood use may be in construction.Current techniques could reduce substantiallythe amount of wood used for home construc-tion—particularly in single-family detached

dwellings–without reducing the quality of thestructure. Two developments are particularlynoteworthy: 1) truss framing and 2) engineeredpanel assemblies, which combine sheathingand framing. Increased use of single trusses toframe floors, walls, ceilings, and roofs togethercould yield greater wood savings. Some ana-lysts estimate that tru ss framing could achieveas much as 30 percent redu ction in lum ber useover conventional construction practices.

Engineered assemblies or stressed-skin pan-els used for floors, walls, or ceilings, which

combine sheathing and framing in sandwichpanels or with adhesives, also may increaseefficiency of wood use. Such assemblies arefactory-built, as are trusses, and their u se couldreduce the wood wastes on construction sitesfrom cutting and custom fitting, resulting inless wood use while providing structural

strength and stiffness.

Improvements in wood use in manufactur-ing and shipping are more limited. Major im-provements probably exist in the manufactureof particleboard pallets or of pallets withplywood or composite-panel decking. Althoughconstruction techniques now being used mayproduce a more durable and versatile pallet,they probably will not replace traditional pal-lets to any significant extent. Conven tional pal-let manufacture requires lower capital invest-ment than particleboard facilities.

Lumber Products

Lumber p roducts are of three basic types: 1] Softwooddimension lumber, 2) boards and finish lumber, the lumber

dim ension lum ber, the mainstay of industrv, is manufactured in five

and 3) timbers. Boards* and finish lumber areless than 2 inches thick and 1 inch or more inwidth. Dimension lumber is between 2 and 5inches thick and at least 2 inches w ide. Lumberthat is 5 inches or more is classified as a timber.

* For purposes of this report, the term “hoard” is used onlyin reference to panel productt, one-in(:h lumber will be referredto ;is “f]nish lumber. ”

types of sawmills: 1)small-log mill; 2) stud mill;3) large, common-log mill; 4) large, grade-logmill; and 5) high -deduct, 1arge-log mill. Distin-guishing factors among these sawmill types arelog diameter and typ e of lum ber prod uct (table16). The most common mill is the small-logmill, which produces dimension lumber forlight frame construction.

Table 16.—Types of Softwood Sawmills and Their Primary Products

Sawmill type “- ‘ -- ‘ - Typical log diameter Primary products produced

Small-log dimension mill ., .. .5” to 16” Random length dimension -

lumberStud mills, ... ... ... , ... ,4” to 9” Studs 2” x 4” X 8‘ nominalLarge, common-log mill ... , 16” to 30” Random length dimension

lumberLarge, grade-log mill ., ... . . 15” and larger Common, shop, and clear

lumberHigh-deduct, large-log mill . . Large logs with greater than Clears and high-grade

30 percent deduct

a

commonsA d a p t e d f r o m Wllllston 1-9;; – “aDeduct[on In recoverable lumber volume due to defects (n the logs

SOURCE Envlrosphere Co Wood /ts Present and Poten(/a/ Uses contractor report to OTA 1982



42 . W OO d Use: U.S. Competitiveness and Technology

Lumber Manufacture

The basic processing steps for lumber man-ufacturing are shown in figure 8. Materials andenergy flows of a typical sawmill are shownin figure 9. The efficiency of lumber recoverytends to vary with mill size, with larger mills

achieving higher recoveries.

Potential Improvements in Milling Efficiencies

and Lumber Manufacture

In 1979, lumber constituted almost 70 per-cent of the weight of all lumber and panel prod-ucts produced in the United States and 53 per-cent of all wood products, except pulp andpaper, consumed in that year.

13Thus, even

small improvements in milling efficiency can

result in significant savings of the Nation’stimber resources, particularly softwood. Sev-eral such improvements can be made in lumbermanufacture by: 1) improving lumber recoveryor wood-use efficiency in sawmilling, 2) de-creasing energy requirements, and 3) improv-ing grading procedures.

Improving Lumber Recovery and Wood Use

The following existing technologies probablyhave the potential to more than double the ef-ficiency of converting rou nd wood into lumberproducts (table 17). By installing or adoptingtechnologies such as BOF, PLV, and SDR, theefficiencies of sawmills probably could be in-creased su bstantially, The p otential increase inlumber recovery efficiency for PLV, EGAR,and BOF is shown in figure 10. In add ition, sev-eral new technologies, such as SDR, corn-ply,

and composite lumber, probably can reduce

Figure 8.— Flow Diagram of a Typical State-of-the-Art Small-Log Sawmill, Indicating Process Waste Streams

r F

Log * >1e Stabber * Twin - Trl-1

band mill

Bucking Chips Sawdust Chips Sawdust Sawdust

Wood J

Chips

Productsorter

NOTE” A log profile is shown ateach machine (top) The shaded areas Indicate material which is chipped away, whileerticle I!nes in other cross-sections indicate saw Ilnes

SOURCE” E M Williston, Lumber Manufacfurlng The Design and Operation of Sawmi//s arrd Paper Mi//s (San Francisco. M!ller Freeman Publications, 1976).



Ch. II-Solid Wood and Panel Products . 43 ——. —.

Figure 9.— Present and Predicted Materials Balance for Softwood Lumber Based on Ovendry Weight(OD wt.) (sawlog weight includes bark)

Sawdust

the lumber industry’s dep endence on high-val-ue softwood timber, whose scarcity (deflatedprice] has increased at the rate of about 2 per-cent per year (compounded) over the last cen-tury . The SDR process and th e manu factur e of

composite lumber and timbers allow manufac-turers to utilize hardwoods, defective timber,and wood residues formerly considered un-merchantable,

Expan ding th e resource base by using largerproportions of the wood produced in the for-est is one of two major opportunities that ex-ist to improve total utilization efficiency of wood in the United States. The other is increas-ing the efficiency in the way lumber is used(conservation). However, increasing the effi-ciency of mills may not significantly reduce the

dem and on the forest resource, un less increas-ing amou nts of forest residu es can be harvestedeconom ically and transp orted to m ills. For ex-

ample, the efficiency of lumber recovery mayreduce the amount of residue available to pro-duce energy, and pulp, paper, particleboard,and other fiber-based panels. Nationwide, theunused wood from primary processing consists

of 52 percent softwoods and 48 percent hard-woods and represents 7.1 million tons of ma-terial, A significant portion of this materialprobably comes from lumber manufacturing,although the exact quantity is unknown.

Improving Yields in Traditional Sawmills

There is a practical limit to the amount of lumber that can be recovered from any log,However, some new processes can increase thelumber-recovery efficiency of dimension lum-ber w ithout major sawm ill modifications; e.g.:

1) the BOF program, which can produce highergrades and increase recovery of lum ber; 2) theSDR process, which enables the use of hard-



Table 17.—Summary of Major Technologies for Improved Lumber Manufacture —

ogy Stage of development

- Commercially available

Process IS developed; no

significant commercial use.

Process is developed; no

significant commercial use.

Commercially available.

mber

-

Commercial availability limited —to a few specialty products.

Ef fect on resource base Ef fect on recovery

None Theoretical increase of 20°/0over conventional

sawmilling.Possible increased small log Increases recovery 10-130/0

utiIization,

Increased hardwood utilization. Reduces defects in hardwood

lumber; increases lumber

value.

None Reduces variability withinlumber grades, allowing

more efficient use of lumber

in construction.

Theoreti cal yield of 70-90°/0

Lumber Not commercially available

Drying (solar No significant commercial

gh temperature development.vapor

ession,

fication)

E: Office of Technology Assessment

Allows use of hardwoods, Theoreti cal %O/. recovery,

wood residue, defective

wood. — Lower energy requirements;

reduction in defects.

Barriers to implementation

Field results have shownaverage 40/0 Increase over

conventional sawmilling.More costly to manufacture;

more labor-intensive.

Higher drying costs; requires

high-temperature kilns.

Modification of codes to allowmost efficient use of MSR

lumber.

Development of continuous

laminating presses; lack of

accepted method for

assigning product strengthvalues; requires new milling

facilities.

Requires new milling facilities

or combination of veneer

and particleboard facilities,

Usually higher capital

investment and/or longerdrying time.

Estimated timescale to

significantcontribution

—.

o

15-20

10-20

0-5

15-20

15-20

15-25



Ch. II—So/id Wood and Panel Products . 45

Figure 10.—The Maximum Yield of Lumber FromConventional and Innovative Processes

I

5 6 7 8 ‘j 10 11 12 13 14 15 16 17 lb 19 20

Log diameter

wood s, previously limited by th eir tendency towarp; and 3) the EGAR process, wh ich red uceswaste and can produ ce higher quality lumber,

Best Opening Face.—The initial sawline, or theopening face cut, sets the position of all othersawlines and therefore has a significant effecton lumber recovery efficiencies and grades.Deciding how to make the initial cut often isleft to the judgment of the head saw op erator.While a skillful operator can achieve high ef-ficiencies, a computer can simulate varioussawing patterns and more quickly choose theoptimal opening face. The BOF, a computerprogram for selecting th e best first cut, was d e-veloped by FPL nearly 10 years ago. In 1973,the Forest Service initiated a sawm ill improve-ment program to demonstrate the BOF con-cept. Under laboratory conditions, BOF yields6 to 90 percent more lum ber from 5- to 20-inchlogs and averages 21 percent more lumber re-covery than does conventional sawing.

Saw-Dry -Rip .—The SDR process can increasethe amou nt of sound , defect-free lumber recov-ered from hardwood timber by modifyingslightly the conventional milling practices of

sawing, ripping into lumber, and then drying,With SDR, crooks, bows, and twists in hard-wood lumber may be redu ced by first sawing,then high-temperature drying, and finally rip-ping” into lum ber. Drying larger pieces at hightemperatures by SDR minimizes the effect of the stresses that develop within wood as itgrows, SDR may result in a lower LRF of green(undried) lumber than conventional milling,but this is generally more than compensatedfor by the reduction in warp.

Edge-Glue and Rip.—With EGAR, logs are sawn

into flitches* * and lightly edged prior to drying.* Kipplng is sawing lengthwlsr or [)a ra 1 lel to gra 1 n, a 10 I)g the

l[)ngitudina] axis of the lumber,* * A flitch is a crosswise slice from a log, with two sawn faces

and two ro’u nded, or u nsaw n edges.




They are then glued edgewise into panels, andthe panels are ripped into lumber. This reducesthe amount of wood lost in edging, which usu-ally sacrifices some sound wood from lumberedges in order to produce solid lumber of standard widths. Ripping can be done to yield

the highest grade and strongest lumber byavoiding knots near the edges of the lumber.The EGAR process theoretically can increaselumber recovery from 35 to 77 percent fromlogs of 5 to 20 inches in diameter.

14It is esti-

mated that EGAR can increase the output of finished dim ension lum ber by 10 to 13 percentby eliminating edging loss.

15Moreover, EGAR

lumber has greater strength and less warp thanstandard lumber. However, the process itself is more labor-intensive than conventional lum -ber manufacture and requires additional dry-ing, which may increase manufacturing costs.

Several new lumber-drying processes thatcould reduce energy consumption may comeinto w ide use in th e future, Because the lumberindustry is a small energy consumer, savingsin energy use by the lumber manufacturing in-du stry probably w ill not contribute significant-ly to national energy conservation; they could,however, become more important to lumbermanufacturers as energy prices increase. (Thelumber industry, however, is a minor energypurchaser and is capable of producing muchof its own energy through the use of mill

wastes. )

Produci ng Composite Lumber and Timber Products

BOF, SDR, and EGAR are marginal modifi-cations to conventional sawmilling. Lumber,or lum berlike prod ucts, also can be m ade fromwood part icles or veneer, as well as from solidwood or edge-glued pieces, Manufacturingsuch composite lumber can dramatically in-crease lumber recovery efficiency and extendthe timber resource base through use of woodwaste material and hardwoods, It is unlikely,however, that composite lumber products willreplace conventional 2 by 4 framing lumber.

‘V-hernan, op. cit.Is(j[:orge B. Harpo]e, Ed Williston, an d Hir am H. Hallock,

“E(lAK Process hlakes Wide-Dimension Lumher From Small],ogs, ” ,$c)uthern I,umberman, Dec. 15, 1977.

Most opportunities for using composite lumberare in larger applications—for girders andbeams-or for specialty applications. Two major processes have been developed to manu-facture composite lumber and timber products:PLV and corn-ply.

Parallel Laminated Veneer.—Also known aspress-lam and laminated veneer lum ber (LVL),the PLV process consists of laminat ing (gluing)veneers w ith all plies parallel (as contrasted toplywood, where the veneers are laminated withgrains perpendicular) to make dimension lum-ber or timbers. Like plywood veneers, theveneer sheets are press-dried, coated withadhesives, laminated in overlapping fashion,pressed, and ripped to desired dimensions.PLV has a number of advantages:

q it produces high-quality products from

low-quality raw material or hardwoods;. lumber or timber dimensions are not lim-

ited by log size; andq it can convert logs into ready-to-use prod-

ucts in 1 hour.

In general, PLV produces higher grade lum-ber than does conventional lumber manufac-turing. Moreover, PLV specialty products andlarge structural timbers from PLV might be at-tractive commercially; at least one firm nowmarkets a joist, called Micro-Lam, * made fromPLV. PLV also can be used to manufacture

nonstructural wood products like millwork andcabinetry. Lumber recovery efficiency fromPLV can be increased from an efficiency of 53to 91 percent for 9- to 20-inch logs, an effi-ciency significantly greater than that theoreti-cally attainable from any other lumbermakingprocess.

Despite its advantages, PLV may not makesignificant penetration into conventional di-mension lumber markets in the near future.PLV manufacture requires equipment that can-not readily be adapted to conventional saw-mills; thus, shifting to PLV probably will re-quire entirely new mills with high capital costs.As existing sawmills are depreciated, PLV fa-cilities may be built as replacements, particu-

*Trademark of the Trus-Joist (lot-p,



Ch. II-Solid Wood and Panel Products . 47

larly if real stumpage values increase and if building codes are mod ified to r ecognize fullythe superior properties of PLV lumber. How-ever, it may be p ossible to mod ify plyw ood orpanel mills to produce composite lumber andproducts such as composite timbers (beams,

joists, arches, girders, and the like), The sub-stitution of composites for dimension lumbermay occur slowly unless the price of high-qual-ity softwood logs significantly increases. PLVcan be used for large structural elements, suchas beams or timbers, that var y in cross sectionacross their length to meet s trength re-quirements.

Com-ply.—Com-ply consists of a structuralcomposite core, like p articleboard, w ith ven eerfaces. It can be m ade into stu ds, larger dim en-sion lumber, or panels. Corn-ply studs are

strong enough to substitute for standard studson a one-for-one basis in exterior house fram-ing. The particleboard core constitutes 70 to80 percent of the product and can be madefrom hardwoods. Because a corn-ply mill canuse n early all of its residues to p rodu ce the corematerial, it can operate with only 5 percentwaste, a lumber-recovery efficiency of 95 per-cent. Economic analysis of corn-ply lumberproduction shows, however, that it is unlikelythat corn-ply lumber will be very competitivewith either conventional or PLV lumber,

Decreasing Energy Requirements

Up to 90 percent of the heat energy requiredin lumber processing is consumed in dryinglumber to a moisture content of 13 to 16 per-cent. Lumber nor mally is dried in a steam kiln(although air drying is used sometimes) inwhich heated air is circulated. Kilns may beheated by natural gas or propane directly or,more commonly, by steam coils. Softwood lum-ber requires from 2 million to 4 million Btu/ thousand board feet while hardw oods requireup to 6.5 million Btu. Several new dry ing tech-

nologies have been developed, including: 1)high-temperature kiln drying, 2) continuous-feed dry ing, 3) dehu mid ification, 4) pred rying,5) pressure d rying, 6) solar d rying, 7) solar de-humidification, 8) vacuum, 9) vacuum-radiofrequency, and 10) vapor recompression dry-

ing, Of these, continuous-feed, dehumidifica-tion, pressure, solar dehumidification, vacuum,and vapor recompression drying may gainsome commercial acceptance by 2000, althoughnone seems likely to replace conventionalsteam kilns.

Improving Grading and Quality

Dimension lumber is graded according tostrength and stiffness, Grades determine whatend u ses may be mad e of construction lum ber,Improved grading systems are being developedto better determine the end-use properties andcharacteristics of lumber and thereby avoidoverbuilding with lumber products or usinghigh-quality material where lower grades aresuitable. Because different defects such astwist, bow , crook, rot, or knots affect mechan-

ical properties differently, current practices of visual grad ing often result in a w ide variabilityin lumber properties within each grade. Build-ers often use lumber of better quality than isneeded for constru ction to accoun t for this var-iability in meeting building codes and avoidingliability.

Improved ability to determine the strengthand stiffness of lum ber, together with bu ildingcode acceptance of better design practicesbased on m ore precise grading, could resu lt insignificant resource savings. Since lumberstrength is related to the presence of knots, asystem that can determine precisely the effectof each knot on each board w ould be qu ite val-uable. As yet, it is unavailable, Another d evel-opment that could aid in making more efficientuse of framing lu mber is a more pr ecise und er-standing of the strength required in end-useapplications, so that lumber strength can bematched to design specifications. Two majorefforts are under way to improve grading inthe United States: 1) MSR, an alternative grad-ing technology; and 2) ingrade testing, a re-search program,

Machine Stress Rating is a mechanical grad-ing system that measures lumber stiffness ina nondestructive, stress-rating machine. It doesnot eliminate the use of visual grading but in-stead gau ges the stiffness before visual grad ersdetermine the grade based on defects.




MSR lumber, with a narrower range of vari-ability than visually graded lumber, redu ces theamount of high-quality lum ber needed to meetparticular design specifications. The primarymarket for MS R-grad ed lumber is in tru ss fab-rication, where lumber is used for roof, floor,

and wall framing. The amou nt of lumber thatcould be saved using MSR varies and dependson the design of the truss.

The In-Grade Testing Program w as initiatedin l977 by FPL to develop more precise dataon mechanical properties of various grades andspecies of lum ber and to assess the importan ceof these properties on the design and engineer-ing of structures. Tests of wa lls, floors, and fullscale indicate that houses generally are over-designed . Information from the In-Grade Test-ing Program may be used in conjunction with

engineering structural analysis to improve theefficiency of lumber use in light frame con-struction.

Consumption and Use of Lumber Products

in the United States

Lumber consumption in the United Stateshas been relatively stable for several decades,increasing from just over 5 billion ft

3in 19.50

to almost 6 billion ft3in 1979.

16At the same

time, per capita consumption of lumber has de-clined by over 20 percent over the past three

decades (fig. 11).

Construction (including new residential con-struction, upkeep, improvement, and nonres-idential construction) uses about 60 percent of all lum ber consumed in the United States. Theremaining 40 percent is used in sh ipping , man-ufacturing, and other uses, with shippingaccounting for 43 percent of lumber used fornonconstruction purposes. New residentialconstruction alone accounts for 40 percent of all lumber consumption.

New Residential Constructi onHistorically, the housing industry has expe-

rienced wide swings in residential construc-tion activity, and th ere are ind ications that that

I%ee note 2.

Figure 11 .—Per Capita Consumption of Lumber1950-79

activity may continue to be erratic and uncer-tain. An upturn in homebuilding could drivesoftwood log prices up, increasing the incen-tives for lumber manufacturers to streamlineoperations and to increase product yields to re-main competitive. Low rates of residential con-struction could force many small lumber millsout of business, concentrating the industry inthe larger mills, which tend to be more effi-cient. Other developments in the homebuildingindustry also affect the lumber industry, such

as trends toward smaller houses and multifam-ily dwellings,

The amount of lum ber used per u nit dependslargely on th e type of d welling constructed an d,to a lesser extent, on building techniques anddesign. Single-family detached dwellings useapproximately twice the amount of lumberused in mu ltifamily d wellings an d 4.5 times theamount used in mobile homes. Most single-family dwellings and small clustered units (e.g.,duplexes) are built onsite. Preassembled lum-ber p rodu cts, such as trusses, have successfully

penetrated the market for roofs in light frameconstruction and now account for the majorityof roof framing. Floor trusses have been lesssuccessful, although they are gaining in accept-ance in some areas. Trusses used to framewhole houses (fig. 12) recently have been de-



Figure 12.— The Truss Frame System

Th IS truss framed system combl nes floor, wal Is, and roofInto a u r] !t Ized f ramp for st r uct L ra I cent I n u It y from the fou nd a t I o n u p t o the r I (j q e

S(JU RCE USDA Forest SFrV Ice Forosl Products Laboratory

veloped by the FPL and are in limited usetoday.

Residential Upkeep and Improvement

Home upkeep and improvement accountedfor 14 percent of the lumber consumed in theUnited States in 1976

17and almost 8 billion

board feet of softwood lumber in 198018

com-pared with 4.7 billion in 197o. Indications arethat su ch use ma y increase. The u se of lum berper thousand dollars of expenditures on up-keep and improvement may have declinedslightly, how ever, primarily because of substi-tution of panel products for lumber.

New Nonresidential Construction

New nonresidential construction accountedfor just under 10 percent of the lumber con-sum ed in the Un ited States in 1976 for a ran ge

IB( ;h 1 rl(; (It t I I, u m her a n{i PI }IW ood

F’ore\t I)rodu[,ts I ndustrj’ and theA[:apulco, Llcxlco; Apr. 3-4, 1982.

Panel products are used

Forecasting, Inc., “The80’s. Think Tank #l ,“

Plywood and

for many things,mainly in construction, Single-family housingconstruction uses 43 percent of the plywoodand 25 percent of the particleboard and other

Ch. II—Solid Wood and Panel Products q 49

of public, private, and commercial projects.Building construction, including commercialand other buildings, accounted for about two-thirds of the lumber used in new nonresiden-tial construction in the early 1970’s.* Totallumber use for new nonresidential construc-

tion, which normally responds to general eco-nomic activity, is expected to double in the next50 years, primarily because of economicgrowth.

19

Manufacturing

Manufacturing, primarily of furniture, ac-counted for 11 percent of the lumber consumedin 1976. Much of the lumber once used forcorestock has been displaced—first by particle-board, then, more recently, by medium-densityfiberboard.

Shipping

Shipping accounted for 17 percent of thelumber consumed in 1976. Two-thirds of thelumber in shipping was used for pallets, withthe remainder used for dunnage, blocking,bracing, and wooden boxes. These latter useshave been declining for two decades and areexpected to continue declining.

Most pallets are made of low-grade hard-wood lumber, usually rough (unsurfaced) lum-ber. Pallet markets, which consum e the m ajor-

ity of the hardwood lumber produced in theUnited States, expanded rapidly during the1970’s for materials handling, and some fur-ther expansion is expected. The rate of increasein industrial pallet use, however, is expectedto decline as the market becomes saturated.

* Utilities, water and sewer systems, high ~tays, and other non-

t)uilrling construction accounted for the remaining one-third.‘@.See note 5.

Panel Products

structural panels produced in the United States(table 18), Panel products also are popular inresidential upkeep and repair, accounting for23 percent of the plywood and approximately




Table 18.—Plywood and Panel Products Consumed inNew Residential Construction in the United States,

1962-80

Type of home (ft2, 3/8” basis)

Year Single family Multifamily Mobile

1962 . . . . 3,010 1,800 “ 1,840

1970 . . . . . . . . 5,385 1,910 1,3001976 ., . . . . . . . 5,815 3,255 1,6101978. , ... . . . 5,600

a2,650 550

1980 . . . . . . . . 5,640 3,105 555.-

aF[gUT~~ for I ip 76 Include only Plywood

SOURCES USDA Forest Service, An Ar?a/ys/s of the T(rnber S(tuatlon In theUn/fed States, 1952-2030, Review draft, 1980 (Includes ftgures from1962, 1970, and 1976)Thomas P Clephane, Out/ook for T/mber Supp/y/Dernarrd Through 1990, Morgan Stanely Investment Research, 1982 (Includes figuresfrom 1978 and 1980)

40 percent of the structural panel market in1976. The remaind er is used in man ufacturing,shipping, and other uses.

There are three types of plywood and panelproducts:

q

q

q

q

Plywood —a flat panel mad e of laminated,crossbanded wood veneers, where eachlayer is arranged with the grain at rightangles to its adjoining layers.Structural composite panel—a panel madeof wood particles—e. g., chips, flakes, wa-fers, and strands—pressed into a flat paneland simultaneously bonded with a thermo-setting adhesive.Particleboard—a nons t r uc tu r a l pa ne l

made from small wood particles bondedinto a flat panel with adhesives under heatpressure.Fiberboard—a flat panel made of individ-ual woodpulp fiber (like paper) bonded t o-gether. Insulation board and hardboardsare special kinds of fiberboards.

Plywood

Current Plywood-Manufacturing Processes

Plywood manufacture consists of two proc-esses: veneer production, and layup and glu-

ing of the veneers into plywood (figs, 13 and14). The five methods for manufacturing ve-neers for plywood include: 1) rotary cut, 2) stay-log cutting, 3) cone cutting, 4) sliced veneers,and 5) sawn veneers. Over 90 percent of the

veneer produced is rotary cut, i.e., peeled ona lathe. Other methods produce specialty hard-wood veneers used in furniture and cabinetry.

To produ ce plywood, the veneer logs first aresteamed and then are sent to a lathe that p eels

off a thin, continu ous ribbon of veneer. The re-maining core of about 4 to 5 inches subsequent-ly is used for dimension lumber or is chippedto produce pulp and paper, particleboard, orfuel. The veneer sheet itself is cut into sheetsby a clipper, wh ich also removes knots and d e-fects. After drying, the veneer is placed on anassembly line, where adhesives (usually phe-nol formaldehyde) are applied, and the veneersare stacked to form plywood. A typical five-plyplyw ood layup line can pr odu ce 6 to 8 five-plypan els or 12 to 16 three-ply p anels per m inute.Following layup, a panel is cold-pressed to con-

solidate it before loading the press, It is thenhot-pressed under pressures of about 15opounds per square inch (psi) at temperaturesranging from 2400 to 3000 F. After the panelscool, they are trimmed and squared, sometimessanded, and then graded and prepared forshipment,

Potential Improvements in Plywood Manufacture

Current plywood recovery rates run between47 and 53 percent and probably average 50 per-cent.

20Less than 1 percent of all roundwood

used in plywood manufacture ends up aswaste. Residues from plywood mills are usedto produce lumber, particleboard, pulp and pa-per, fiberboard, or energy.

Because plywood mills now are capable of using smaller logs than in the past, increasedefforts are being made to use hardwood forstructural plywood, Technical developmentsin plywood manufacture are aimed primarilyat: 1] expanding the number of species andquality of the timber that can be used forplywood; 2) increasing automation; 3) reduc-ing energy r equirements; and 4) increasing the

degree of computer-assisted process control,particularly in peeling and clipping.

20See note 8.



Ch. II—Solid Wood and Panel Products q 51

Figure 13.— Flow Diagram of a Small-Log Plywood Mill

Bucking Lathe Peeling~ Clipping

Sawdust

Debarking

Chips

IL u m b e r Ch ip s Ch ip s —Drying

Log yard

Expanding the Range of Usable Material.–The ply-wood industry historically has d epended on aplentiful supply of large-diameter, straight, rot-free softwood timber. However, over the years,large softwood logs have become very costly,and future supplies are uncertain. As a result,in the early 1960’s, the plywood industry beganto move to the South, attracted by inventoriesof largely unutilized Southern pine. By 1980,the South w as produ cing nearly as mu ch p ly-wood as the West, generally u sing smaller logs.Technology still is being sough t to han dle andprocess small logs and expand the range of logsthat can be peeled.

Currently, 25 percent of the veneer logs are

considered unpeelable. 21 Some mills lose 40percent of their logs from splintering, crack-

‘4] }J1.,l [~ h J I;rfJr]\/,CiA, “ I)r(’i f’nt in~ [’(III(;(JI Holt S1] inollt, ’” .llo(i-(‘[ 1 1’/\ LI ( )(){1 /“(’( h/) /(/ L]( ‘5 , ~) 1’( )( ,(’( ‘( I I 1) g> ( t t hll ,s(JI”[~l) t 11 1’1 \“ \i”[ )()(i(:1 1[}1( . I’ortlrll)(l. ( )1’(’ . hldrl t) 1 (17’)

ing, and breakage on the lathe caused by too-small logs or internal defects. Because of thehigh value of veneer logs, increasing theamount of peelable material can greatly im-prove the productivity and profitability of themill. Some techniques used to prevent woodlosses include: 1) better chuck design to holdand rotate the logs against the knife; 2) newpressure-bar designs to position the knife onthe log; 3) heating the log, which some believecan reduce the torque needed to peel the log;and 4) using backup torque rollers to increasedeliverable torque at the lathe.

New types of pressure bars mounted on thelathe to control veneer thickness and peeling

performance show some promise, Roller barsproduce lower forces needed for peeling thando conventional, fixed bars, but initially costmore and have higher maintenance costs. Therecently developed steam-heated, contoured




Figure 14.—Material Balance for Softwood Plywood Based on Ovendry Weight (OD wt.) (veneer log weight includes bark)

Phenol-formaldehyde resin0.01 \

1.0 ton

o

00

0

Panel trim and reject

0.07

Shavings and end trim

0.01

Chips

0.04

Sheathing plywood

0.45

Part ic leboard furn ish

0.08

Studs

0.06

0.30

Total 1,01

SOURCE C W Boyd, et al Wood and F/t,er Ml ) 1 72 1976

fixed bar, however, may be as effective as theroller bars without the high cost.

Increasing the chuck* diameter could in-crease the amoun t of peelable roundw ood, butlarger chucks increase minimum core size aswell. Furth er chu ck mod ification is u nlikely toproduce significant increases in veneer recov-ery, and the backup roller was developed as ameans of providing this auxiliary torque. Re-

search on the optimum design and location of the backup roller is under way.

Finally, some efforts are being made to ex-plore the potential of hardw oods in structuralplywood p rodu ction. Results of several studiesindicate that construction-grade hardwood ply-wood mad e from a mixture of high- and low-density species could be competitive econom-ically with softwood construction plywood.

22



Ch. II-Sol/d Wood and Panel Products q 53 .




Particleboard

Current Particleboard Manufacturing Processes

Other than p lywood, most structural panelscurrently manufactured in the United Statesare particleboard m ade from a variety of wood

particle types. The basic steps involved instandard particleboard manufacture (calleddry-forming), are shown in figures 15 and 16,During the process, wood first is reduced tothe d esired p article geometry by flaking, disk-ing, hogging, or h amm ermilling. The particlesare dried using rotary-dru m d ryers or horizon-tal fixed dryers and classified according to size,They are blended then with adhesives andwaxes and formed into a mat, sometimes withcoarse particles at the core and finer particlesat the surface.

27The mat then usually is hot-

pressed to the desired thickness and density,

allowing the adhesive to cure. Panels then arecooled, trimmed, sanded, and graded.

A small proportion of the particleboard pro-du ced is wet formed, or extrud ed, wherein ad-hesive-coated particles are forced throu gh a hotdie. The extrusion process prod uces a particle-

‘-~[!rlt; ~1’[;[l~~rt ;]lIc1 ~“r[;ci IdInh , “Arl ()~wrview’ of (:omposite1100 [’(1s, “ F’urniturc l~c.sign ,~nd .lfanufa[:turing 54(3), M a r c h1982,

Figure 15.— Materials Balance forParticleboard Based on

board that is weak in bending and stiffness andlow in dimensional stability and generally isused for specialty purposes. To overcomestrength problems, extruded particleboardoften are honeycomb-shaped or fluted,

Potential Improvements in Particleboard Manufacture

Many particleboard markets have been de-clining du e to comp etition from new stru cturalpanel products in construction and from me-dium-density fiberboard in furniture corestock.Some particleboard probably will continue tobe employed in n onloadbearing structural useand in a variety of home and miscellaneoususes, but only if it is cost-competitive with otherproducts. Particleboard manufacturers havebeen facing increased competition for raw m a-terials—largely planer shavings and other saw-

mill residu es—from pu lpmills, As a result, theparticleboard industry may focus on improv-ing the u tilization of forest residu es and on d e-veloping economical harvesting and transpor-tation methods.28

the Manufacture of UnderpaymentOvendry Weight(OD wt.)

Urea-formaldehyde resin Wax

0.08 0.007

1.0 tonplaner shavings, sawdustplywood and lumber trim

(OD wt.)

Particleboard(5/8 in. thick)

0.979

Sander dust 0.094

Kerf from panel saws 0.014

vx }

J

Total

Fuel0.108

1.087

NOTE Total IS more than 10 because of resin and waxes percentages may vary

SOURCE C W Boyd, et al , “Wood for Structural and Architectural Purposes, ” Wood and F/ber 6(1)’ 1-72, 1976



Ch II. -Solid Wood and Panel Products q 5 5

Figure 16.—Materials Balance for the Manufacture of Structural Particleboard Based(OD wt.) of Chipping and Flaking of Sound Wood

on Ovendry Weight

NOTE Va\ues !n parentheses are those associated with chlpplng and flak!ng cull logs or other forms of residue with some rot Total IS more than 10 because of theaddltlon of resin and waxes Percentages may vary

SOURCE C W Boyd, et al “Wood for Structural and Architectural Purposes, ” Wood and Ftber 6(1) 1.72 1976

Structural Composite Panels

Struct ural Composite-Panel Manufacturi ng Processes

Structural composite panels were developedin an effort to get more out of the wood re-

source, a focus still primary in the industry.Nearly all the new panel products developedin the last two or three decades can use hard-woods and some defective wood material aswell, although high-quality structural panelsusually require roundwood for raw material.In the 1980’s, R&D efforts likely will be aimedat imp roving th e efficiency and engineering of particleboard-panel products made from flakes,chips, particles, and strand s to meet d esign re-quirements.

There are three general types of new panel

products, the first two of which are expectedto provide competition to plywood in structuraluse: 1) waferboard; 2) OSB; and 3) veneer-faced,composite-core panels.

Waferboard, or flakeboard, originally intro-du ced in Canada, is a panel made of wood wa-

fers or large, flat flakes. High-qua lity flakeboardcan be made using as much as 8 percent bark (although too much bark can cause problems)and 12 percent decayed wood. It also can bemade from all hardwood and thus offers op-portunities to extend the resource base and pro-duce sheathing-quality panels at lower costthan possible with softwood plywood. Thealignment of particles has proved difficult inwaferboard, however, and the n onaligned p ar-ticles produce a product with much lowerstrength and stiffness than plywood. However,waferboard is strong enough to substitute forplywood in many sheathing applications. Wa-ferboard has been accepted widely in Canada,and there are several waferboard plants oper-ating in the United States. A basic manufac-turing flow diagram is shown in figure 17.

Oriented strand b oard is made from strandsor ribbon-like pieces that can be laid down inlayers to produce a three- or five-layer boardwith crossbanded construction much like ply-wood (fig. 18). The stru cture of OSB may over -come the strength problems of waferboard,




Figure 17.— Idealized Typical Waferboard Process

Rawmaterial

Press

Institute of Technology, June 1982

OSB, unlike waferboard, uses liquid resins,which could reduce adhesive costs. These res-ins also may provide flexibility in the type of resins used, which may be useful if the indus-try moves to isocyanate (similar to Crazy Glue)binders in the future.

29

Veneer-faced composite-core panels (com-ply) use p articleboard cores with veneer faces,like plywood. These products have engineer-ing prop erties similar to those of plywood , but

sometimes are stronger and stiffer. However,their dimensional stability is somewhat lessthan that of plywood, and they are more dense,Corn-ply may be manufactured to a limited ex-. —

29Se~ note 8.

tent in existing plywood or veneer facilities;however, it probably will not compete withwaferboard and OSB.

Potential Improvements in Structural

Composite Panel Manufacture

In addition to extending the resource base,primary emphasis in R&D on structural panelproducts is in improving product performance,improving processing, and conserving energy.

Improving Product Performance.—Plywood re-tains much of the natural strength and physi-cal characteristics of the original wood. Parti-cleboard cannot match the performance of plywood in many high-stress, structural appli-



Ch. Ii—Solid Wood and Panel Products • 57

Figure 18.—ldealized Typical Oriented Strand Board Process

Rawmaterial

Flake

1resin

Form andalign 4

surface

J

SOURCE Henry M Montrey Ill Current Status and Future of Structura/ Pane/s In the Wood Products /ndustry, M S the.ws, MassachusettsInstitute of Technology, June 1982

cations and therefore has been used m ainly forfloor underpayment and furniture corestock ra-ther than sheathing, Research in producingstructural panels that can substitute for ply-wood in sheathing and other structural applica-tions has been a m ajor R&D focus. Efforts havecentered on controlling particle geometry andalignment during mat formation.

Improving Processes .—Developments in proc-esses for aligning particles and p ressing p anelsshow future promise. Particle alignment [ori-

enting wood particles with parallel grain) with-in a composite structural panel helps retainmore of the d esirable mechanical properties of solid wood, but allows the use of a variety of wood raw materials. This is a major factor in

producing composite panel products suitablefor high-stress, structural applications.

Both mechanical and electrostatic processesare used to align the particles, Mechanicalalignment is used to produce OSB. Electrosta-tic alignmen t polarizes wood fibers or p articlesthat become aligned with the electrical linesof force. These technologies are not developedfully; how ever, work on fiber alignment is con-tinuing. Wafers historically have proven diffi-cult to align. Equipment that could produce

aligned waferboard may provide additionalstimulus to this growing industry,

Developments in pressing panels have notbeen dramatic, but there is an ongoing inter-




est in continuous presses to speed processingand reduce bottlenecks associated withconventional presses. Although continuouspresses are available for pr odu cing thin boardsand medium -density boards, those that can beused to produce a wider variety of structural

panel products have yet to be developed,Another trend in board-pressing is toward theuse of closed-liquid heating systems rather thanthe conventional, steam-heating systems. Liq-uid heating systems provide higher tempera-tures, have less temperature variability, are lesslikely to have “cold spots, ” and save at least20 percent of the energy required to operatea comparable steam-heated system.

Conserving Energy .—Particle drying is a majorenergy consumer in the manufacture of panelproducts. Innovations in drying have been

modest.

Fiberboard

Current Fiberboard Manufact uring Processes

Fiberboard, insulation board, and hardboardare manufactured from individual fibers or fi-ber bundles, rather than from wood particles.The wet process, which can be used to manu-facture any of these products, was first devel-oped in 1924 by W. H. Mason and is knownas the Masonite process. The prepared woodis heated by steam in a pressure vessel calleda “gun .” The pr essure in the gun is raised from600 to 1,000 psi and then su dd enly is reduced,causing the chips to explode into a coarse massof fiber which is reduced further by milling.The fibers are formed into a m at, much like pa-per, and finally pressed in a hot press.

Hardboard also can be manufactured usinga dry process in which the chips are pre-steamed and grou nd in a mill. Most fiberboardcurrently is produced using mechanical disk refiners and thermomechanical pulping. Usu-ally, resin and wax are applied to the fibers

prior to m illing, and the fibers are formed intoa mat and hot-pressed like particleboard. Thedry process uses resin to bond the fibers to-gether, while the wet process relies on the com-bination of natural bonding action of the lignin

in the fibers and the contact of the fibers to pro-duce a cohesive panel and a synthetic resinbond.

Fiberboards are not used generally in load-bearing ap plications because of their tendency

to creep under load. Also, they tend to be lessstiff than other w ood p anels of similar density.

Potential Improvements in Fiberboard Manufacture

There have not been many recent develop-ments in the fiberboard field in the UnitedStates, with the exception of MDF, Some ef-forts have focused on using lower grade rawmaterials and hard wood s, but since fiberboardis not a major consum er of wood raw materi-als, gains in this area would affect only mod-estly overall dema nd s on th e resource base. Inaddition, many fiberboard products have beenreplaced p artially by vinyl, plastics, aluminu m,and other types of insulation.

MDF was developed in the United Statesaround 1970, and growth of its manufacturingcapacity and markets has been significant, By1981, the United States w as capable of prod uc-ing 668 million ft

2of corestock MDF.

30M D F

can be prod uced using either wet or d ry proc-esses, and high-quality MDF corestock for fur-niture can be made from hardwoods. MDFprobably will be used more for interior panel-ing and nonstructural uses, such as trim, door

jambs, furniture, and casegoods. However,when produced with an exterior resin it canbe used for exterior siding on houses,

Present and Future Use and Consumption

of Panel Products

During the last 30 years, the decline in percapita consumption of wood products (includ-ing pulp ) was offset partially by the increasingper capita consumption of plywood and ve-neer. Per capita use of plywood and veneerrose from 2.3 ft

3in 1950 to 7.0 ft

3in 1979, Over-

all consump tion rose from 2,2 million tons (air-

sONat iOna] partic]~oard Association, “1 ndustry Board cawCl-ty by State and Product, ” Furniture Design and Manufacturing54(3), Mar. 11, 1982.



Ch. II--Solid Wood and Panel Products q 5 9

dried) to 11.8 million tons. During the same pe-riod, use of panel products (including fiber-board) rose from 1.3 million air-dry tons to 10.1million. Statistics on per capita consumptionof structural panel p rodu cts, exclusive of hard -board and fiberboard, are not available.

Although conventional plywood probablywill continue for another 10 to 20 years to bethe major structural panel produ ct u sed in theUnited States, the greatest growth in panelproducts markets in the past few years hasbeen in particleboard and MDF (fig. 19).

31In

1979, unveneered structural panel products(waferboard, OSB) accounted for only 1.5 per-cent of the demand for structural panels. TheAmerican Plywood Association estimates thatthis demand will grow to 6.1 percent by 1984,and other sources forecast even higher de-

mands, perhaps up to 20 percent. Because of .——.—— —.‘ 1 S(!(! [lOt(: 8

the slow housing m arket since 1978, the ap par-ent consump tion of panel produ cts (and mostother wood products used primarily in lightframe construction) dropped. Any resurgencein the housing market is expected to provideample opportunities for growth of structural

pan el markets. Moreover, structural pan els areexpected to compete strongly with softwoodplywood for most end uses (table 19).

The striking feature of panel products mar-kets has been the displacement of lumber andplywood by composite panels. Structural pan-els probably will continue to increase marketshares relative to plywood and may begin tocompete with nonwood materials such as steel,aluminum, and plastics for some structuralproducts.

A summary of major technical improvementsis shown in table 20. Improvements in proc-essing efficiency have reduced labor require-

Figure 19.— Historical Production of Major Panel Products, 1970-79

25,00(

20,000

15,000

co —

o

10,000

5,000

0

Softwood

Particleboard(million square

Insulating \ board

(thousand tons) \

(thousand tons)Hardwoodplywood

(million square feet,

\

Med. densitysurface measure) fiberboard

\ (million squarefeet. 3/4a basis)

I I I 1 . . - . * Uq

I

1970 1971 1972 1973 1974 1975 1976 1977 1978 1979

Year




ments, increased productivity, improved qual- already are using almost all the wood wastes

ity control, a nd he lpe d r e duc e e ne r gy for electricity and heating requirements, a

requirements. Larger panel products mills trend expected to continue.

Table 19.— Plywood End Uses and Their Susceptibility to Penetration by “New” Panels

1976 End-market plywood susceptibility

Millions of Percent ofsquare feet

New residential construction: Roofs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Floors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Siding and trim. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Wall sheathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3,0912,660

960505

Total new residential construction . . . . . . . . . . . . . . . .

Repair and remodeling: Structural additions, alterations, and repairs . . . . . . . . .Shelving and furniture. . . . . . . . . . . . . . . . . . . . . . . . . . . . .Small building and construction . . . . . . . . . . . . . . . . . . . .

Total repair and remodeling . . . . . . . . . . . . . . . . . . . . . .

Industrial markets:

Products made for sale . . . . . . . . . . . . . . . . . . . . . . . . . . .Materials handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Plant repair and maintenance . . . . . . . . . . . . . . . . . . . . . .Repair and wholesale trade . . . . . . . . . . . . . . . . . . . . . . . .

Total industrial markets . . . . . . . . . . . . . . . . . . . . . . . . .

Nonresidential construction: Nonresidential building . . . . . . . . . . . . . . . . . . . . . . . . . . .Auxiliary uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Concrete forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Farm building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Total nonresidential construction . . . . . . . . . . . . . . . . .

Other uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7,712

2,333768322

3,780

1,688440421381

2,970

1,338280807360

2,785

1,153

18,400

to penetration by “new” panels-

—total High Medium Low —

1 6 . 8 % x14.5 x5.22.7

xx

41 .9 ”/0

12.7

4,21.7

20.50/o

9.22.42.32.1

1 6 . 2 0 / ,

x

xx

x

x

xx

x

7.3 x1.5 x4.4 x1.9 x

15.1 %

6 . 3 0 / o x

100.0% 4 8 . 2 0 / o 4 2 . 0 0 / , 9 . 8 0 / o-. — —

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 20.—Summary of Major Technologies for Plywood and Panel Product Manufacture

Estimated time scale toBarriers to significant c ontribution

implementation (years) — — .

Stage of Effect onTechnology development resource base

———.——.

New pressure nosebar Commercially available Increases ability to peel High capital costs o-1odesign small logs; reduces

number of unpeelable

logs —

Backup torque roller In development Same as above None o-5

Waferboard Commercially available Allows hardwood and None o-5residue use

Veneer-faced composite

—

Commercially available on Allows hardwood and

——— .—

Requires integration of 10-20- - -

core panels small scale residue use veneer and particle-

board facility

Oriented strand board

—

Commercially available

—

Allows use of residue None o-1o — — —

SOURCE Off Ice of Technology Assessment



Ch. II-Solid Wood and Panel Products q 6 1

Wood Use in Light Frame Construction

Wood Conservation

In general, houses probably are overde-

signed, even considering the severe and un-usu al stresses to which they m ay be subjected.Failures are unusual in the wood members, butdo occur at joints and edges. More sparing u seof materials that are designed to providestrength an d stiffness, based on new engineer-ing designs, could improve the efficiency of wood use. Three areas where conservation of wood materials is possible are in conventionalconstruction, framing and attaching assem-blies, and substitutions for individual framingmembers,

Conventional Construction

Conventional construction techniques com-monly waste 3 to 7 percent of the lumber andplywood used in a home. This waste could bereduced through n ew d esign, and the value of the waste material could be reduced throughselection of lowest quality and smallest size ma-terial required. Door and window framing innonloadbearing walls possibly could be elim-inated. Proper positioning of framing mem-bers, such as joists, studs, and windows anddoor framing, could further redu ce the 1umber

required. Off-center, in-line joist splicing (re-placing overlapping joists over the center beamor sup port) could m inimize the size and gradeof joist required (fig. 20).

Framing and Attaching Assemblies

Panel assemblies consist of framing and

sheathing nailed or glued together, often incombination with insulation, siding, and fin-ishing materials. The strength and stiffness of a panel assembly is greater than the framingor sheathing alone; assemblies can be engi-neered so that each component enhances thestrength of the others. Add itional developm entis probably needed to develop this conceptfully.

Factor construction of engineered panel as-semblies has two advantages: 1) it allows theuse of rigid ad hesives, wh ich increase the abil-ity of individual pieces to share loads to agreater extent than occur s with mechanical fas-teners or adhesives applied onsite; and 2) it re-duces the scrap and shortens constructiontime. Factory-made assemblies are of twotypes: stressed-skin panels and sandwichpanels.

Stressed-skin panels are made of framingfastened (usually w ith rigid adh esive) to a skin,or sheath. In Germany, stressed-skin panelsusing particleboard for skins are used in con-structing one- and two-family homes. Stressed-skin panels can be made with stringers of 2-

inch d imension lumber w ith plywood or otherpanels bonded to either or both sides to act asa series of I-beams, Factory-fabricated stressed-skin floor panels have been in use since 1965

Figure 20.—Offcenter, In-Line Joint Spacing

w -

,.”

End joints properly located




and have performed satisfactorily. They haveyielded savings in floor material of 20 to 30 per-cent compared with conventional methods.

Even greater efficiencies may be possibleusing sandwich panels constructed to bear the

loads requ ired on walls, floors, and roofs, Sand -wich panels can use plywood or other panelproduct facings, and their cores can be madeof a variety of materials, such as foamed plas-tic, honeycomb paper, or bark. These panelsuse about 40 percent less wood than conven-tional construction,

Substitutions for Individual Framing Members

Some wood products can substitute for in-dividual framing members. Two types of prod-ucts that use less wood and provide neededstructural strength are engineered wood beamsand trusses.

At least one firm m anu factur es a wooden I-beam, which is made with solid softwoodflanges and a plywood web and can be usedas a grider, joist, or center beam (fig. 21). Sim-ilar products composed of particleboard orhardboard webs have been used in Europe formany years for structural framing of walls,roofs, ceilings, and floors. These do not use as

Figure 21 .—Wooden l-Beam Construction,

Cross-SectionFlange

4(solid wood)

—

,

Web (ply

SOURCE Off Ice of Technology Assessment

mu ch wood as a solid wood en beam does andcan be used in place of steel I-beams in lightframe construction,

Trusses, or p ieces of lumber joined togetherto form framing members, were developed in

Germany as early as 1830. The widesp read u seof trusses for roof framing is at least three dec-ades old, Floor trusses, although slower thanroof trusses to gain wide acceptance, now ac-count for a minor portion of floor constru ction,Use of trusses to frame w hole hou ses—consist-ing of floor, wall, roof, and ceiling members,all joined by truss plates—is a recent devel-opment.

Truss framing designs could further reducethe amount of wood required for constructionand may provide other benefits as well (table21), Trusses—which are joined with conven-

tional truss plates, plywood gusset plates, ormetal fasteners to distribute forces amongmembers-increase the structure’s rigidity andreduce the risk of failure. Truss frames elimi-nate the need for immediate supports and re-quire 30 percent less structural framing lumberthan conventional construction. A truss framesystem, for example, could consist of an openweb floor system, trussed rafters, and wallstuds tied together into a unitized frame.

Although the use of trusses and panel assem-blies or sandwich panels offers many oppor-

tun ities to increase the efficiency of wood usein housing, the housing industry is interestedin cost savings, not in m aterials savings per se.The truss frame system and panel assembliesoften are simpler and faster to erect on site andmay save labor,

32which can account for over

30 percent of construction costs. Wood mate-rials, on the other hand, account for a muchsmaller proportion of construction cost, andwood products designed to make light frameconstruction less costly therefore are morelikely to be accepted if they also are labor-saving. The housing industry historically has

been fairly conservative in adopting new build-ing technologies. Part of this reluctance can beattributed to the need for building-code recog-

Framed System, ” no date,



Ch. II—Solid Wood and Panel Products Ž 63

Table 21 .— Benefits of Truss Framing

Economic benefitsq

q

q

q

q

q

q

Labor savlngs

Material savings

Qutck assembly

Faster buyer occupancy

Weather protection of equipment and materials.

good working environment, and securityAdaptable to high-volume processes and inventoriesof standard size lumberMany energy-savings features

Fabrication and erection flexibility:• Uses existing truss-manufacturing technologyqCan use a variety of truss-fabrication methods and

equipmentq Time flexibility in completing finished buiIdings Flexibility in subcontractor schedulingqPotential for relocatable structures

Design flexibility.qEngineering design services readily availableqFlexible space utilization from clearspan con-

struct ionq Variety and flexibility in housing design

Safety and quality:Increased quality without added costStrength through controlled assemblyStrong connections between floors, walls, and roofReduced opportunity for human error in constructionOvercomes major weakness of conventional con-struction (malted Joints)Meets or exceeds current structural, architectural,and safety provisions I n model codes

T rar> sfer PI an

nition of new construction products and tech-niques, but buyer acceptan ce and resistance of building labor trades to adoption of new sys-

tems probably are also significant factors.

New Uses for Solid Wood Material

Two new w ood p rodu cts could replace con-crete, stone, or cinderblock in new home con-struction: 1 ) the all-weather w ood foun dationa n d 2 ] the und erfloor plenum system.

The all-weather wood foundation is a ply-wood-sheathed, stud wall made of preservative-t mated plywood and lumber that is at least par-tially below grad e. Watertightness is prov ided

by a sump in the gravel pad beneath the woodfooting, polyethylene film covering the exteriorof the foundation, and caulking between ply-wood panel joints. The National Association

of Homebuilders Research Foundation, whichhelped d evelop th e all-weather w ood found a-tion, estimates that the system uses 33 percentmore w ood than does a typical two-story dwell-ing built on a cinderblock found ations. .

The underfloor plenum system, designed toreplace the concrete slab now used extensivelyin the south, provides a n underfloor areathrou gh w hich warm or cool air can be distrib-uted throughout the house for heating or airconditioning, eliminating ductwork, Properlyconstructed, the plenum has shown no tenden-cy to rot from excessive moisture or to pre-

sent insect problems. Because it can be buried,it does not detract from the appearance of thehome. It is cost competitive with concretestructures.

The all-weather wood foundation has beenaccepted by building-code authorities, andthere is no specific code prohibition against theunderfloor wood plenum. Though both are costcompetitive with conventional foundationbuilding practices, they have not significant}penetrated the market. Again, the reason forthis probably has to do with the conservatismof the building construction industry and buyeracceptance.

Composites of Wood and Other Materials

In general, the wood industry has not in-vested much time or resources in developingprod ucts that combine wood w ith other mate-rials. Since the 1960’s, however, composites of metal or plastic skins laminated to a wood corehave met a number of industrial uses becausethey are strong, durable, and corrosion-resist-ant, The metal-skinned wood panel has beenused in the past in aircraft, housings, partitions,truck and trailer d oors, train interiors, cabinetsand cases, pallets, and escalator balustrades.Wood composites also may be combined withfoal insulation for cold-storage facilities. Al-

though composite dimension lumber madefrom wood particles that incorporate contin-uous strands of high tensile-strength glassfibers have been developed, they have not p er-




formed satisfactorily to date because of tech- of wood and mineral-based products, such asnical problems that arise when materials with cement boards made from excelsior anda great deal of d ifference in stiffness are “m ar- cement.ried. ” Some composite panels are composed



CHAPTER II

Pulp, Paper, and Fiber Products



CHAPTER Ill

Pulp, Paper, and Fiber Products

Summary and ConclusionsPulp and paper manufacturing is moving

toward the produ ction of higher quality pu lpsthat require less wood inpu t per ton of pulp andpaper produced. Increased energy costs, in-creasing raw material costs (for both round-wood and sawmill residues), a market that nowemphasizes printability and other nonstrengthfactors, and the availability of immenseamounts of less expensive hardwood timberhave promp ted the U.S. pulp and paper indu s-try to consider more energy-efficient and ma-

terials-efficient manufacturing technologies.

The adop tion of mechanical pulping technol-ogies could r edu ce the amou nt of fiber requiredto produce a ton of paper from about 2.5 tonsof wood, for the kraft chemical pulping proc-ess, to about 1.05 tons for thermomechanicalpulping. With this reduction, it is estimatedthat each future increase of 2 percent in pulp-ing capacity would necessitate an increase of only 1.7 percent in wood fiber feedstocks.

1

These potential increases in pulping efficiencyand fiber yield can effectively extend the Na-

tion’s usable wood sup ply, redu cing th e likeli-hood of raw materials shortages and relaxingthe p ressures on the shrinking U.S. timberlandbase. Expanded use of hardwood species thatare presently underutilized may further extendthe domestic timber supply.

Pulping technologies like organosolv holdprospects for the industry to become a netenergy producer. The organosolv process mayalso permit utilizing hardwood species and ob-taining high fiber yields with little sacrifice inprod uct strength . Such p rocesses are still in thedevelopmental stages but may be commerciallyavailable in 25 years. Meanwhile, the pu lp andpaper indu stry could redu ce the amount of en-

‘G. Styan, “Impa{.t of North American Tlrnber Supply on In-

novat ions i n Paper Ttx:hnology, “ pa~}er Tra~~ Journal, VC)I . 164,

Ma y 30, 1980,

ergy required by increasing th e use of mechan-ical pu lping and expand ing the u se of recycledpaper. In addition, the efficiency of chemicalpu lping may be increased by ad opting pyrolytictechnologies for the recovery of spent pu lpingliquor, autocaustisizing to reduce the energyrequired in th e lime-kiln p rocess, and u sing an-thraquinone as a catalyst for chemical kraftpulping to increase fiber yields.

Press-drying technology, while still in devel-opmental stages, shows promise for both re-ducing the amount of energy required in thepapermaking process and enabling the use of hardwood species not currently used in largequantities. In some respects, the quality of thepaper produced by this method exceeds thatof unbleached kraft paper produced by conven-tional processes. It may also afford an oppor-tunity for the U.S. pulp and paper ind ustry tocapitalize on a growing export market in liner-board and other heavy-duty packaging ma-terials.

Advanced research and development (R&D)

on improving the strength and stiffness of pa-per could lead to development of structural fi-ber products able to compete with a numberof metallic, ceramic, and plastic materials. Inaddition, paper may be combined with othermaterials such as plastics, coatings, and syn-thetic fibers to produce composite materialswith superior qualities.

Although plastics have made significant in-roads in certain types of packaging, and havesignificantly displaced paper sacks for light-du ty uses, paper still command s a m ajor pro-

portion of this market and will probably con-tinue to do so. Moreover, increases in energycosts could improve paper’s competitive posi-tion relative to petroleum-based plastics, whichrequire larger energy inputs in production. Thepaper industry could further strengthen its

67




competitive position if it continued to adoptexisting energy-efficient technologies.

Electronic telecommunications technology,on the other hand, could have significant im-pacts on demand for printing and writing pa-

per in the future. While the magnitude of itseffect on paper is yet uncertain, the introduc-tion of advanced electronic devices such aselectronic filing (the “paperless” office), videomagazines, electronic newspapers, and video

catalogs and directories may increasingly af-fect the use of paper now and du ring the nexttwo decades. Recently, the use of word proc-essors and office copying equipment has in-creased the demand for paper products, a trendthat m ay d ecline as electronic commu nicationsgain increased acceptance in offices. In thefinal analysis, the long-term effects of telecom-munications technologies on paper require-ments are unknown,

Introduction

Profile of the Pulp and Paper Industry

The United States has the largest per capitapaper and paperboard consumption in theworld, averaging more than 600 pound s annu -ally. It is also the world’s largest producer of paper and paper products, accounting for ap-proximately 35 percent of the world’s total out-put. The U.S. pulp and paper industry is ninthin size of tons produced and 11th in gross as-sets among the domestic manufacturing ind us-tries. In 1981, U.S. production of pulp, paper,and pap er prod ucts was estimated at $82.1 bil-lion (current dollars).’

Raw MaterialsIn 1978 the pulp and paper industry used ap-

proximately 77 million tons of pulpwood (ovendried). Forty-four percent of this came fromchips and sawmill residues, which are woodwastes from the manufacture of lumber andother solid wood products. About 26 percentof the pu lpwood used in 1978 was hard wood.(Trends in wood use in the past 40 years havebeen toward increased use of hardwood spe-cies and increased reliance on chips and saw-mill residues.) In addition, the U.S. pulp andpaper industry used approximately 15 milliontons of recycled wastepaper for pulp and pa-per production in 1978.

3

‘IJ. S. D e p a r t m e n t of (lommerCe, 1982 ]n~~st~ja] uut]~~k(Washington, D. C.: U.S. Government Printing Office, 1982), p. 39.

‘Joan E. H uher, The A’line Guide to the Paper Industr}r (Fair-fie]d, NJ.: (Jharlcs H. Kline & (j{),, 1980), pp. (j6-67,

The pulp and paper indu stry also uses aboutone-quarter ton of chemicals for each ton of

paper or paperboard produced, ranking sixthamong all industries in dollar value of chemi-cal products purchased. It is also the largestuser of water for processing among all manu-facturing industries. Finally, the industry is oneof the leading industrial consumers of energy,using roughly 7,2 percent of the Nation’s in-dustrial energy requirements and 2,8 percentof the total energy used in the United States.Approximately half of the energy used by theindustry is p roduced internally from w ood res-idu es and oth er waste prod ucts. Because of thelarge energy requirements and the sensitivity

of production costs to energy prices, the pulpand paper industry has become an industrialleader in energy conservation and cogenera-tion (internal generation of electricity fromsteam heat),

Product Demand

Demand for paper and paper products isclosely tied to economic growth and disposableincome levels. Although year-to-year fluctua-tions occur, correlating with economic trends,the industry is relatively free from the cyclical

variations experienced by other primary indus-tries such as mining, metals, and solid woodproducts.

Capital

The pulp and paper industryally high capital requirements

has exception-for plant and



Ch. Ill—Pulp, Paper, and Fiber Products • 69

equipment, Capi ta l inves tment cur ren t lyran ges from $350,000 to $1 million per installedton of d aily capacity, depend ing on a m ill’s de-sign and whether the investment is an additionto the existing mill or a new facility.

4The pa-

per industry invested $6.8 billion in capital ex-

penditures in 1980; however, $369 million, or5 percent, was spent on pollution controlequipment that did not increase produ ction ca-pacity.’

Industry Size and Production

With over 4,000 f i r m s e m p l o y i n g a b o u t

626,000 workers, the pulp and paper productsindustry is an important comp onent of the U. S.economy. It produces over 14,000 different pa-per products, and its potential for developingnew and even better paper and fiber produ cts

in the future is high. At the same t i me, moreefficient manufacturing processes could re-duce energy use and lead to increased use of presently underutilized, but prevalent, hard-wood species.

It is estimated that paper products accountfor almost three-fourths of the wood-basedsales of the top 40 firms in the forest prod uctsindustry.

6While the pu lp and p aper sector con-

sists of a large number of competing firms, the10 largest firms manufacture over half of thepulp, paper, and paperboard products pro-

duced in North America. In addition, a num-ber of the major pulp and paper manufacturersproduce a variety of secondary products, in-cluding solid wood items, containers, writingpap ers, and sanitary pap er prod ucts (table 22).Fifteen companies that produce both paper andsol id wood products are prominent among thewood-based industries, but together they ac-counted for only 24 percent of all wood-basedsales in the United States in 1978.7

In 1976, the South produced 67 percent of the Nation’s wood pulp. Southern forests areparticularly attractive to the industry becauseof the abundance of both softwoods and hard-woods, The pulp and paper industry has ex-panded its capacity in the South in recent

years; while the South’s share of total pulp pro-duction was only 48 percent in 1947, it is nowover two-thirds, The West produced 17 percentof the Nation’s wood pulp in 1976. The remain-ing 14 percent was produced i n the East andin the North Central States.

B

While pulpmills are located near raw mate-rials, the manufacturing sector of the ind ustry,which makes containers, bags, sanitary prod-ucts, and stationery, is concentrated near themarkets. Thus, the New England Middle At-lantic, and North Central States produce 62

percent of all paper products. Much of thetimber resource in these regions is hardwood,which has not been used extensively for paperprodu ction in the past. Wood p ulp p roductionin these regions currently constitutes only 16

percent of total U.S. wood pulp production.

Uses of Pulp, Paper, and Paperboard

Total U.S. pulp production has been projected to increase from 53.2 million short tonsin 1981 to 54.8 million short tons in 1982. However, the actual volume may be low er as a re-

sult of the 1981-82 recession.g

In addition to thedomestic products used, approximately 4.3 mil-lion short tons of pulp were imported in 1981,primarily from Canada. Pulp exports totaled3,7 million tons, most of which was shippedto Europe, Mexico, Japan, and Korea. The total53.8 million shor t tons of pu lp u sed w ere con-verted into over 66 million tons of paper andpaperboard. Imp orts of primary pap er and p a-perboard products were about 8 million tonsin 1981, while exports slightly exceeded 4 mil-lion tons,

Wood pulp is converted into a variety of pa-per products (table 23). The major uses of pa-per, w hich accoun ts for 49 percent of the w ood




-“ I

vK

I



Ch. Ill—Pulp, Paper, and Fiber Products q 7 1

Table 23.—U.S. Production of Paper and Paperboardin 1981 and Projected for 1984 (thousand tons)

1981- 1984a-

Paperboard ... ... ..-.. ., . : 14,558 15,360Kraft fiberboard ... ... . . 1,067 1,140O th e r k ra f t p a p e rb o a rd . , . . . 4 ,7 1 7 5,070

Bleached paperboard ., ... ... . 3,926 4,100Recycled paperboard . 7,070 7,150

To ta l p a p e rb o a rd . , . . . . . . 3 1 ,3 3 8 33,020

Paper:Uncoated free sheet . . . . . . . . . . . . . 7,882 8,720Coated free sheet and groundwood . 4,951 5,340Uncoated groundwood ... 1,440 1,540Bristols and other ... ... ... . 1,530 1,580

Total printing and writ ing . . 15,803 17,180

Newsprint ... ... . . ... . . . . 5,238 5,730

Unbleached kraft ., . ... ... ... . 3,891 3,760

Bleached regular and industrial . . 1,603 1,670

Tissue ., . . ... ... . . . . ... 4,485 4,730

Total paper ., . . ... ... ... . . . 31,020 33,070

Total paperboard and paper ... 62,358 66,090aMorgan Stanley estimates

—

SOURCE Thomas P Clephane and Jeanne Carroll Linerboard Industry Outlook (New York Morgan Stanley & Co 1982) p 25

pulp produced, are for printing and writing pa-pers [50.9 percent), newsprint (16.9 percent),tissue (14.5 percent), and packaging (17.7 per-cent). Over 51 percent of U.S. wood pu lp p ro-duction is converted to paperboard (a stiff,heavy paper). Linerboard, which is kraft paper-board used for boxes, shipp ing containers, andpackaging, accounted for 46.4 percent of thepaperboard produced in 1981. Overall, packag-

ing materials (both paper and paperboard)made up 59 percent of all paper and paper-board p rodu ced in the United States, and w asone of the most rapidly expanding pu lp uses.

Since the price elasticity of demand (thechange in demand resulting from a change inprice) for paper products is generally small, therecent decline of relative prices has probablyhad only a small positive impact on apparentpaper consumption.

10The U.S. Department of

Commerce projects shipments of primary pa-per and pap erboard p rodu cts to rise at the rate

of 3 percent annu ally for the next 5 years. Mar-ket projections through 1986 suggest a steadyincrease in domestic and worldwide demand

1 O(; a ] ~u la t j(j ns 1)F. the K ldd~r, Peilhodj’ E c o n o m i c s G r~up ill-

d ic. ate that the relative price elastic it~’ of demand for paper isapproxi miitely 0.5 percent.

for paper prod ucts in general. Demand for pri-mary pap er and board prod ucts is expected tobe exceptionally strong. Economic factors af-fecting d emand s for comm un ications, packag-ing and shipping papers, and boards, however,will ultimately determ ine actual deman d levels.

The most promising m arkets during the en-suing 5 years are expected to be for linerboardand high-quality printing papers. An increaseof 6 percent in the trend line of 1982 linerboardexports is forecast by some analysts,

lland the

demand for high-grade printing and publish-ing pap ers is projected to increase at an annu alrate of about 7 percent.

12Demand for both

printing paper and linerboard is expected toexpand at rates twice that for products of thepaper industry overall. While domestic con-sumption will probably increase gradually in

response to a stronger economy, the demandfor exports is expected to increase even mor e,in response to expansion of the indu strial econ-omies of the People’s Republic of China, Japan,Malaysia, Indonesia, the Philippines, Taiwan,and Korea.

Advanced Paper Materials

The development of stiff, durable p aper, w ithstrength characteristics currently achievableonly at the experimental level, offers futureprospects for new structural building products,

Paperboard has been tested for use as sheath-ing and wall modules in buildings with mixedresults.

13The effects of moistur e on th e dim en-

sional stability and stiffness of the pap erboardis a major factor limiting the usefulness of pa-per as a structural material. New high-strengthpapers with protective coatings, coupled withinnovative designs for paper-based structuralmaterials, are a possibility, But considerableR&D remains to be d one p rior to commercial-ization.

I] Thomas p, C]epha ne and Jeanne Ca rrol ], Linerboard Indus’-

try Outlook (NewYork: Morgan Stanley &

Co,, 1982],

p.I Z

.IZCorp~rate Strategies, “A Narrowed Boise Cascade F’ocuscs

on Paper, ” l?usiness il’eek, Apr. 26, 1982, p. 81.13’’ Emergency Housing for $2,500, ” Technology Re\Fie~t”, Ma\’/

June 1982, p. 86. “Paperboard Houses Now Approved for all Ex-posures by FHA, ” Paper Trade Journal (Aug. 23, 1971], p. 53;

“Paper Houses Buyers, ” Chemica) Engineering, Sept. 8, 1969,

RP 76-71.




Wood pulp may be converted into paperproducts ranging in character from superab-sorbent fluffy tissue to extremely hard, board-like materials. Wood pulp’s versatility resultsfrom the ability to vary paper’s stiffness overa wide range. Wood fibers are extremely flex-

ible, strong, and durable. When brought intoclose contact, they form a durable fiber webas a result of hydrogen bonds, strong bondswhich provide the strength and stability of pa-per. Hemicellulose acts as an adhesive betweenthe fibers and adds strength.

Stiffness is the major quality that makes pa-pers so suitable for boxes, shipping containers,and, possibly, structural building materials. Al-though strength is also important, it is morefrequently lack of stiffness that limits thechoice of materials for these products. Because

cellulose fibers attract w ater, moistur e can af-fect paper’s structural integrity by softening thefibers and reducing their stiffness, Tests inmodifying paper to enhance stiffness and mois-ture resistance, performed at the U.S. ForestService Forest Products Laboratory (FPL), havedemonstrated that super-strength paper may,on a weight basis, be capable of matching theperformance of other solid m aterials like solidwood, aluminum, and steel.

14

The major factors affecting stiffness that aresubject to control by the papermaker are fiber

orientation, density and fiber bonding, and

IAv . se t t e rho]m, ‘ ‘Factors That Affect the Stiffness of Paper,

The Fundamental Properties of Paper Related to Its Uses, vol.1 , F. Bolam (cd.) (London, England: The British Paper and Paper-board Industry Federation, 1976), pp. 253-266.

shrinkage control during the drying cycle. *sThe prospects for improving paper stiffnessthrou gh the u se of synthetic resin add itives arenot considered as promising as improved bond-ing and fiber orientation in the papermakingprocess.

Researchers at FPL hypothesize that anelastic modulus of approximately 1.5 millionpounds per square inch (psi), with a specificgravity of 0.4, could be achieved in paper inwhich the fibers are parallel and shrinkage iscarefully controlled during drying. This levelof stiffness is app roximately equivalent to th atof wood parallel to the grain at the same spe-cific gravity. Laboratory tests have producedpaper sheets of specific gravity of 0.75, witha tensile strength of 38,000 psi and an elasticmodulus of 3.8 million psi.

16These values sub-

stantially exceed the specific strength and stiff-ness-to-weight ratios of all common structuralmaterials, including solid wood. Only certaingraphite and boron fiber composites surpassthe strength of this “super paper” at the spe-cific gravity tested. Laboratory researchersconclude that paper can be produced that isstiffer and stronger than the wood from whichit is made, If high-strength papers can be de-veloped that are capable of maintaining stiff-ness and dimensional stability in high humid-ity, they may be used for a range of structuralapplications now being served by wood, plas-

tics, or metals—e.g., housing, furniture, andcontainers,

.IsIbid., p, 266.lelbid., p. 260.

Role of Paper and Cellulosic Materials in the U.S. Material Mix

Competition with traditional paper commod-ities for U.S. markets comes primarily from

two areas: plastics and electronic communica-tions. Competition from plastics is often in theform of substitution of plastic products forpaper products and, occasionally, compositeproducts made from paper and plastics, Elec-tronic communications, on the other hand,

have the potential for displacing a share of thepaper market by reducing the need for writing,

copying, printing, and business forms. So far,how ever, electronic comm un ications has p rob-ably resulted in greater consumption of paper,owing to increased use of word processors,high-speed computing systems, and inexpen-sive office copiers.




The impact of competition from p lastics and prod ucts, in contrast to linerboard an d paper-the electronics media on paper materials will boards used in shipping containers, will be seri-vary among paper products. Newsprint, writ- ously affected by competition from plasticing and printing papers, business forms, paper products and the electronic media. The print-

bags, and wrap ping p apers constituted 47 per- ing and writing paper sector, which constitutes

cent of paper consump tion in the United States one-third of U.S. paper consumption, will likely

in 1979 (table 24). Some anticipate that these experience the greatest impact from th e expan-

Table 24.—Uses, Grades, Production, and Consumption of Paper Products in the United States in 1979

ApparentProduct ion consumption

Market Grade (thousand tons) Percent (thousand tons) Percent

Newspapers . . ... . . . ... , . ... . ...Magazines, directories, catalogs . . . . . . . . . . .

NewsprintUncoated

groundwoodCoated papersUncoated book

4,062

1,5304,526

7,868

376125

1,114

3,934

1,791

4,525

29,851

14,076

1,127

4,721

4,023

4,883

31,631

3,466 —

6

27

12

<1<1

2

6

3

11,215

2,2544,640

16

37

11

<1<1

2

6

2

6

54

18

1

7

5

11

42

5 —

100

Magazines, annual reports, other periodicals . .Books . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . .Commercial printing, envelopes, business

forms, Iables, duplicator covers, and text . . Writing andrelated

Thin paperCotton fiber

7,913

391126

1,116

Cigarettes, carbonizing condensers . . . . . . .Bond, writing, other business, and technical .,Tabulating index, tag and file folder,

post card ... ... . . . . . . . . . . . . . . .Wrapping, bag, sack, shipping sack . . . . . .

Bleached bristolsUnbleached kraft

packaging andindividualconverting 3,937

Bleached bags, wrapping glassine,greaseproof ., . . . . . ... , . . . . . . . . . . . . . . Other packaging

and industrialconvertingpaper

Special industrialpaper

1.729Industrial converting . ... . . . . . . . . . . . . . .

Sanitary tissue papers, waxing, and wrappingtissues . . . . . . . . . . . . . . . .

Total paper ... . . . . . . . . . . . . . ... .Facing for corrugated or solid fiber boxes . . . .

7

46

Tissues 4,514

37,835

12,611Unbleached kraft

Iinerboard 22Tube, can, drum, file folder, shipping

containers . . . . . . . . . . Other unbleachedkraftfiberboard 2 1,050

Recycled corrugating medium, chip and fillerboard boxes, partitions and dividers . . . . . Semichemical

paperboard 7 4,737Folding cartons, milk cartons, paper plates,

cups, posters . . . . . . . . . . . . . . . . Solid bleachedpaperboard 6 3,310

Folding cartons, setup boxes, gypsumwallboard facing . . . . . . . . . . . Recycled

paperboard 12

49

7,533

29,241Total paperboard ., . . . . . . . . ... . . . . .Construction products, insulating board,

binder, and shoe board . . . . . . . . . . . . . . . . . . Building and wetmachine board 5

—

100

3,763(462)Other . . . . . . . . . . . . . . . . . . . . . . . . . .

Total paper ., ... . . . ... , ... ... , . . . . . . .—

64,947 70.340SOURCE Adapted from G Boyd Ill and H Dudley, Paper Industry Outlook for 1980 Through 1982, Part // (New York K!dder , Peabody & Co 1980) p 10




sion of electronic communication if telecom-munications technology is accepted by thebusiness community and home use expandssignificantly in the future. Plastic substitutesfor paper bags, wrapping papers, and miscel-laneous office supplies could displace 10 per-

cent of the paper consumed in the UnitedStates annually,

Competition From Plastics

The use of low-density polyethylene film(LDPE) for packaging, wrap ping, and sacking,and high-density polyethylene film (HDPE) forprinting and wrapping paper, is a comparative-ly recent trend that began during the past dec-ade and continues to expand at a steady rate.Plastics claimed only a l-percent share of thegrocery sack market (small sacks used for in-

dividual items) in 1979, but within 2 years ex-pan ded to 5 percent of the market. The p lasticsindu stry projects that p lastics could capture asmuch as 25 percent of the grocery sack mar-ket by 1985,’

7but, according to some analysts,

the penetration of plastics into the traditionalkraft pap er markets w ill proba bly be selective,For example, the grocery bag market (larger,multiwalled, heavy-duty bags) may be less vul-nerable to inroads by plastics, at least duringthe intermediate term (10 to 15 years).

l8

Several factors will determine the future

competitiveness of plastics in relation to pa-per products: 1) relative production costs, in-cluding raw material (resin for plastics andwood , and chemicals for paper), labor (in gen-eral, the paper industry is more labor-inten-sive), and energy consum ption; 2) rate of tech-nical innovation; and 3) consumer acceptance.

Sack/Bag Market

Plastics’ share of the merchandise bag mar-ket w as estimated to be 35 percent in 1981, anincrease of 10 percent over the previous year,Investment analysts at Morgan Stanley & Co.estimate that plastic bags will control 60 per-cent of the merchandise bag market by 1985.

19

“Clephane , p. 18.InIbid., p. 17.

lgIbid., p. 16 .

Prod uction of 275,000 tons of finished bags an -nually account for only 5 percent of the totalproduction of unbleached kraft paper. MorganStanley estimates that by 1985, merchandisebags will require no more tha n 3 percent of thetotal production of unbleached kraft paper pro-

duction.

Large grocery bags consumed 12 percent(467,000 tons) of the unbleached kraft paperproduced in 1981, Small grocery sacks ac-counted for 95 percent of the 1.3-million-tontotal grocery sack market in 1981 and u sed ap -proximately 34 percent of the u nbleached kraftpaper p rodu ced du ring that year. Until recent-ly, plastics were not considered to be seriouscompetitors of kraft paper for the grocery bag/ sack market; how ever, some analysts now p re-dict that plastics may be able to capture rap idly

an increasing an d significant shar e of the mar-ket, The paper industry confirms that plasticsnow compete at p rices ranging from $0,029 to$0.031 per sack and sell for 10 to 15 percentless than unbleached kraft sacks. The majorplastic sack p rodu cers include several oil com-panies and chemical companies: Mobil, Exxon,and Union Carbide,

One reason for plastics’ current success incompeting with kraft paper in the bag and sack market is the availability of low-cost resins.Another is technological developments in poly-ethylene that permit substantial reduction inplastic thickness and volum es withou t sacrific-ing strength. For examp le, developm ent of theUnipol p rocess for making linear, low-density,polyethylene resin in 1979 constituted a major breakthrough for the plastics industry be-cause it required considerably lower capital in-vestment and consumed less energy per unitof resin produced.

Paper currently possesses properties that aresuperior to plastics as a material for bags andsacks. The rigidity of pap er sacks enable themto stand freely for filling in grocery and retail

stores. To compensate for lack of sidewall rig-idity, plastic sacks must be mounted in racksfor ease of filling. Although such technologydoes not yet exist, it might eventually be pos-sible to d evelop a r igid-wall plastic sack capa-ble of competing economically with paper




sacks. The conversion from LDPE to newerlow-density polyethylene film could provideeven greater price advantages for plasticsacking.

Multiwall Sacks

One major segment of the paper sack mar-ket that has not yet been seriously challengedby plastics is the multiwall, bulk shipping sack.Plastics have not made significant inroads inthis sector because the strength properties re-quired put plastics at a cost disadvantage rela-tive to kraft paper. Plastics currently occupy10 percent of the multiwall sack market, andsome industry analysts assume that this mar-ket penetration w ill remain stable over the longterm u nless unforeseen technological develop-ments occur. Product developments in the pulpand paper industry may reinforce paper’s shareof the m ultiwall sack mar ket. For examp le, St.Regis Paper Co. recently introduced StressKraft, a superior-strength paper permitting a20-percent reduction in the weight of the pa-per used for multiwall sack construction.

20

Multiwalled sacks consumed approximately 26percent of the unbleached kraft paper pro-duced in 1981.

Liquid Containers and Packaging

Plastic containers for liquidnificant gains in competition

have mad e sig-with glass and

coated-paper containers. Plastic l-gallon milk containers now d ominate the market, althoughmost sm aller l-quar t and l-pint containers con-tinue to be coated p aper. Technological innova-tion accoun ts for the current inroads of plasticsin the packaging sector, yet plastics have stillcaptured only a small proportion of the packag-ing and container market. Because p lastics arepetroleum derivatives that are not biodegrad-able, and in some cases may produce toxicfumes if incinerated, plastic packaging prod-ucts have met opposition from environmen-talists.

21

The market for tissue w rapping papers andglassine and parchment papers has not beensignificantly penetrated by plastics, althoughplastic bakery bags and cereal box liners arein wide use, The major limitations to the useof plastics in these areas are primarily linked

to the d ifficulty of ada pting au tomatic packag-ing machines for the new materials. HDPFshave properties similar to the cellulose filmsand may some day challenge conventional pa-per materials in this area.

While plastic and aluminum foil trays havesignificantly challenged pap erboard fiber traysfor packaging meats, fish, and prepared andfrozen vegetables, recent trends in microwavecooking (wh ich cannot u se aluminu m foil con-tainers and requires heat-resistant receptacles)have resulted in a new generation of oven-re-sistant packaging. Polyester coatings have been

joined with m olded p aper trays to create a com-posite product suited for microwave cookingconditions.

22

A nu mber of comp osites, which combine pa-per with plastics and metals, provide a prod-uct sup erior to those mad e with one m aterial.Amon g these are collapsible plastic bags insidepap erboard cartons equipped w ith a spout fordispensing liquids, thermoplastic-coated paper-boards for water-resistant food containers,paper meat trays coated with plastics, paper-boards treated with clay-adhesive mixtures and

bonded with metal foils, and paper cartonslaminated with plastic foams.

Printing and Writing Papers

Plastic films have not significantly displacedprinting and writing p apers, except for special-ized uses. The properties of paper (printability,flexibility, wearability, and price) are wellsuited for printing, recordkeeping, businessforms, magazines, and books. The durabilityof plastics (e. g., in Mylar and waterproof pa-pers) makes them useful for transparent repro-

du cible graph ics, children’s books, and outd ooruse, However, the cost of printable plastic filmsis approximately twice that of the highest

‘z~lr, l,onl~ i re, 4’ I’al)crboar(l Packages fOr ot’ens,’” Fm[i Ellglneering, ]an~]ary I $)78, [). 6 2 ,




grades of paper.23

Paper industry analysts be-lieve the probab ility is low that p lastics w ill beable to displace paper in general business andcommercial use, except for the highly special-ized applications named above.

Synthetic FibersThe major petroleum-based synthetic fibers

that compete with rayon and acetate are thepolyesters, nylons, acrylics, and olefins. In1968, the w orldw ide volu me of cellulosic man-made fiber produced was about the same asthat of noncellulosic manmade fibers (3.9 mil-lion tons).

24Since that time, the noncellulosic

fibers have dominated the artificial fiber mar-ket. This trend may continue, although the m ar-ket shares for rayon and acetates appear tohave stabilized. Some predict that a slight re-surgence in the use of rayon may occur if pe-

troleum prices increase significantly.

Improvements in the viscose rayon processor the d evelopm ent of new p rocesses that couldredu ce the cost of rayon m anu facture m ay alsoreinforce the market position of cellulosic prod-ucts. Some claim that the rayon industry hassuffered from a r edu ction in R&D in the 1950’sand 1960’s, the period when petroleum-derivedsynthetics displaced rayon as the predominantmanmade fibers.

The rayon and acetate industries, however,

consider their major competitor not to be thepetroleum synthetics but natural cotton fibers,Cotton an d rayon have similar p roperties withregard to moisture absorption and other wearcharacteristics, making possible developmentof improved, cottonlike rayon fibers that aredirectly substitutable for cotton. The rayon in-du stry sees an opportu nity to expand its mar-ket without meeting competition from petro-leum synthetics, based on the forecast thatworldwide demand for cotton will increase at

———-— —“’(Where Plastic Papers Stand in Printing, Bags and Tissues, ”

Modern Plastics, March 1973, p. 55.

Z4Committee on Renewab]e Resources for Industrial Materials(CORRI M), Fibers as Renewable Resources for Industrial Ma-teriais [Washington, D. C.: National Academy of Sciences, 1976],p. 234.

a rate exceeding the capacity of the agriculturalindustry to meet the requirements. ’s

Competition From Electronic Technologies

Recent developments in large-scale, inte-grated circuitry are revolutionizing the com-munications and information fields by reduc-ing the size of computers and microprocessors,expanding their capacities and flexibilities, re-ducing costs, and increasing availability to awider range of potential users.

26Through the

use of satellite communications, microwave,and interfacing d evices on home television re-ceivers, electronic communications may belinked with large centralized information sys-tems that are capable of providing a w ide rangeof user services. Further developments in op-tical digital-disk technology (a specially coated

plastic disk on which information is encodedby a high-pow ered laser beam) may enable thepermanent storage and relatively cheap retriev-al of immense amounts of information.

27Fun-

damental research on new concepts of datastorage and retrieval may pave the w ay in thefuture for even greater expansion of informa-tion technology.

Achievements in telecommunications tech-nology during the past two decades offer anumber of opportunities for improving thespeed and flexibility of communications, Elec-tronic mail is being considered by the U.S.Postal Service and private firms as a way tospeed textual communications and eliminatethe need for handling and physically transport-ing mail.

28Some foresee electronic filing lead-

ing to the paperless office.29

Video magazines,which may be transmitted directly into the

Z5 c ; . DaU], o p . Cit., P, 84’

z6LJ.S. congress, office of Technology Assessment, COmputer-

Based National Information Systems: Technology and PublicPolicy’ Issues, OTA-CIT-146 (Washington, D. C.: U.S. GovernmentPrinting Office, September 1981), pp. 3-12.“C. Goldstein, “Optical Disk Technology and Information, ”

Science, vol. 215, Feb. 12, 1982, p. 862.

“J, Free, “Electronic Mail: Good-bye to Paper?” Popular Science, September 1980, pp. 78-141.

‘e’’ Electronic Filing to Threaten Cut Size Paper Markets, ” Fi-

ber Market News, No. 72, Dec. 14, 1981, p. 1,




home via satellite and conventional televisionreceiver, are in the early stages of develop-ment.

30

Television-adapted versions of the phone d i-rectory, retail catalogs, and other m erchand is-ing devices, which can be viewed on home tel-

evisions, are currently being evaluated forpu blic use.

31Also, a number of major newspa-

per publishers are interested in producing elec-tronic newspapers; in the United Kingdom atleast three such teletexts are already operat-ing.

32Futurists consider as long-range pros-

pects the use of vast central information sys-tems—’’hypertex capableable of retrieving, dis-playing, and manipulating information from“grand libraries” through personal consoles.

33

Such broad-scale application of electroniccommunications could affect dramatically the

use and demand for paper in the future. Al-though telecommunications has experiencedrapid growth du ring the past decade, its appli-cation for office and home use is still in its in-fancy, Thus, uncertainties regarding the rateof commercialization and public acceptanceand forecasts of its impacts on paper must beconsidered speculative. While there is littledisagreement among analysts that electroniccommunications may ultimately displace theneed for some writing and printing papers, thetiming and extent of the impacts are subjectsof debate.

Euro-Data Analysts, a British-based marketconsulting group specializing in the paper,board, and packaging indu stry, forecasts a major shift from the use of paper toward increasedreliance on electronic media.

34Over the long

term, Euro-Data considers it likely that the de-veloped countries will achieve a nearly paper-

30’’Tips on Tiipe: (;assette Magazines Arrive, ” Time, June 14,

1982, p. 78.314

’ Paper Chases the EIectron i{; Age, ” Bosjness Week, Apr. 5,

1982, pp. 112-115,

32K. Edwards, “The Ele(;tmnic Newspaper, ” CommunicationsTomorrow (Bethesda, ~ld,: World Future Society, 1981), pp.

54-59.“H. Freedman, “Paper’s Role in an E]ec,tronic World, ” Com-

munications Tomorrow’ (Bethesda, Md,: World Future Society,1981), pp. 60-65.

34Eu rO-Data Analyst S, The Impact of Communications Tech-

nologies on llemand for Printing and Writing Papers (Ashtead,

Surrey, U. K.: Euro-Data Analysts, 1980),

less society as the rate of commercializationof electronic communications accelerates. Eu-ro-Data forecasts that during the current dec-ade, paper will lose a share of the market tothe electronic media through video telephonedirectories, office commun ications, telex, video

books, video newspapers, consumer maga-zines, and electronic funds transfers.

The American Paper Institute (API) sees im-med iate comp etition w ith the electronic mediain electronic fund transfers, office reproduc-tions that require less paper, electronic mail,and electronic storage and microforms .35 Be-yond 1985, API anticipates competition d evel-oping in d irect-mail advertising; voice m essagesystems that would reduce the requirementsfor envelopes and business forms; expandeduse of home video catalogs and directories;video publication of periodicals; interactivevideotext, which might reduce book publish-ing; and video systems displaying t ime-criticalnews, which could displace some newsprint.

By 1995 and beyond, portable handheld vid-eo displays could displace printed magazines,books, and newspapers (table 25). API notesthat the electronic media accounted for over60 percent of the total communications ex-penditures during the 1970’s. If the trend con-tinues, its share could exceed 70 percent by th eyear 2000, while the paper-based media’s sharemay drop to less than 30 percent.

36

Other a nalysts agree that electronics technol-ogy will probably reduce the demand for print-ing and writing papers du ring the next decade,International Resource Development, Inc.(IRD), a technology consulting firm, sees homevideo as p otentially flattening the grow th in d e-man d for pap er directories and catalogs within6 years.

37IRD projects that by 1991, electronic

filing could reduce dem and for office paper by300,000 tons per year (5 percent of current of-fice consumption). Data Resources Inc. (DRI)estimates that home video systems could start

affecting newsprint demand by 1985.38

If elec-

ssAmerican Paper ] n st itute, Information Technolog~’ and pa-

per Demand (New York: API, 1981], p. 52.j~Ibid

“’’Paper Chases in the Electronic Age, ” op . cit., p. 112.‘eIbid.




Table 25.—New Information Technologies and Their Potential Impact on Paper Construction

Paper end-use categories/relevant information techniques Paper end-use categories/relevant information techniques

Commercial business and printing papers: . Printing papers.”

—Advertising: direct mail— Home video information (vid-eotex and teletext) may open new avenues for advertis-ing and could thereby adversely impact print-based ad-

vertising, including direct mail. Timeframe: beyond 1985.—Printing: financial and legal— Expanded use of wordprocessors and intelligent printer/copiers will encouragemore in-house production of forms. Electronic fundstransfers will continue to grow, subtracting from the useof printed forms in financial transactions.

q Office graphic reproduction —Growth i n the use of intel -Iigent copier/printers will encourage more in-house offsetprinting. Timeframe: currently taking place; trend is ex-pected to continue.

Duplexing and reduction capabilities, both of which oper-ate to conserve paper, will become common features ofoffice copiers, including those positioned at the low endof the price scale. Timeframe: currently taking place; trendis expected to continue.

Converting papers: q

q

q

Envelopes- Expanded use of electronic mail and voice-

message systems may hold down the number of envelopesused by businesses and individuals. (Voice-message sys-tems are not expected to come into widespread use before1985.)Business forms—An increased proportion of businessforms will be produced in-house using intelligent copier-printers. Electronic storage and microforms will continueto displace paper forms in selected applications.Stationery and tab/et—A modest, negative impact fromelectronic mail, electronic pads, and voice-message sys-tems appears possible. Timeframe: beyond 1985.

Magazine publishing: Modest, negative impact possible fromhome video information. The future development of a full-page portable display for reading electronically stored in-formation could also impact paper consumption by maga-zines. (The advent of portable displays is not anticipated

until the 1985-95 timeframe, or beyond.)Other periodical publishing: Home video information mayhold down paper consumption for catalogs and direc-tories. The future use of videodiscs as a storage mediumfor reference materials may have a negative influence onpaper consumption for catalogs and directories. Time-frame: beyond 1985.

Book publishing: Possible use of home and office videodiscsto store large quantities of infrequently examined infor-mation could limit future demand for reference bookssuch as encyclopedias. Interactive videotex may Iikewisehave a negative influence on the demand for referencebooks. Timeframe: beyond 1985.

As noted above, next to magazines, the advent of a por-table, full-page display possessing adequate image qualityfor prolonged periods of reading may lead to reductionsi n the demand for paper-based, printed materials, includ-

ing books. Timeframe: 1985-95, or beyond.Computerized printers reduce the need for special labelsin certain applications.

Newspaper publishing: Home video information may drawclassified advertising and financial listings away fromnewspapers. It may also compete with newspapers bybecoming an efficient transmitter of time-critical news in-formation. Timeframe: beyond 1985.

Advent of compact display could also have repercus-sions on newsprint consumption. Timeframe: 1985-95,or beyond.

SOURCE American Paper Institute, Information Technology and Paper Demand (New York, API, 1981), pp 10-11

tronic media affect newspaper advertising astelevision has, by 1995 they could displace800,000 metric tons (tonnes) of newsprint an-nually (15 percent of current U.S. production),

In the short term, demand for writing andprinting paper seems to have increased withthe p roliferation of word processors and officecopiers, which enable fast and inexpensivecopies of texts and graphics to be made, Al-though this phenomenon is considered bysome industry analysts to be temporary, othersforecast that paper will continue to dominateoffice communications, magazines, and news-papers.

39How ever, both International Business

Machines (IBM) and American Telephone andTelegraph (AT&T) have stepped up activitiesin the field of information storage an d transmit-

SQFree~ rn ~ n, op . (: it., P. Go .

tal, and some analysts consider th eir entry into

the market as the harbinger of rapid progressand expansion in electronic comm unications.M

With 30 percent of U.S. paper p roduction be-ing used for storage and transmission of infor-mation, the short-term trend in increased pa-per usage as a result of electronic officeequipment is expected by some industry ana-lysts to give way to sharp decreases in paperuse d uring the next 20 years .*1

The futu re impact of electronic media on p a-per demand may depend on its effects on theattitudes of a generation of children accus-

40(;. 11 rown, “Tomorrow in the Pulp and Paper Industry: AnOutsider’s v’iew, ” speech to 1982 Annual Employee RegulationsConferen(;e of the American Paper Institute and Fiber Box Asso-ciation, St. Louis, Me., ]an. 27, 1982 (New York: Kidder Peabody’

and Co., Inc., 1982), p. 4.41 ibid.



Ch. Ill—Pulp, Paper, and Fiber Products . 79

tomed to the p artial substitution of electronicsfor paper. While many older p eople, not so ac-customed, find acceptance of nonprinted me-dia difficult, the present school-age generation,who u se nonprinted comm unications through-out their educational careers, will accept elec-

tronic communications for business and homeuse more readily. In add ition, although current

technology limits the u se of electronic commu -nication to desktop consoles and large comput-er and word processing installations, the devel-opment of handheld portable devices withreadable screens—and microelectronic p roces-sors capable of storing entire books and mag-

azines—could have a significant impact on thesubstitution of electronic media for print.

Pulp, Paper, and Cellulose Fiber Manufacturing

Paper was supposedly invented in 105 A.D.by Ts’ai Lun, a member of the Chinese imperialcourt.

42Ts’ai Lun’s method for papermaking

involved soaking tree bark, hemp, rags andother cellulosic materials in water to soften

them and then beating the softened materialuntil the fibers separated and swelled. He dis-persed the fibers in a wet suspension andformed a thin sheet that was transferred to afelt cloth and pressed. The resulting web wasdried in the sun.

Paper is still made by essentially the sameprocess: 1) pulping, to separate and clean thefibers; 2) beating and refining the fibers; 3) di-luting, to form a thin fiber slurry, suspendedin solution; 4) forming a w eb of fibers on a th inscreen; 5) pressing the w eb to increase the den -sity of the material and remove excess liquid;

6) drying to remove remaining moisture; and7) finishing, to provide a suitable surface forthe end use. The three methods for pulpingwood and other cellulose materials includechemical pulping, mechanical pulping, andsemichemical or chemim echanical pu lping—acombination of the first two methods.

In mechanical pulping, wood chips from de-barked logs are ground , or are passed throu gha m ill, and in some versions of the p rocess aretreated with high-pressure steam (thermo-mechanical) to separate the individual fibers,

which can then be formed into sheets of pa-per. Mechanically sep arated fibers contain lig-

4z F , F, Wa ngaa rd, WOOd: lf s Structure and properties ((] nl ~’er-

sity Park, Pa.: Pennsylvania State Uni\’ersity, 1981), p. 335,

nin, which makes them remain stiff, bond poor-ly, and yellow with age.

Chemical pulping is done by cooking woodchips in acid, alkaline, or neutral salt solutionsunder pressure and high temperatures, which

breaks dow n the w ood structure and d issolvessome or most of the lignin and hemicellulosecontents. Delignification by chemicals causesthe ind ividual fibers to become flexible and in-creases contact and binding among the fibersforming the paper mat, thus increasing thestrength of the p aper. Semichemical and chem-imechanical pulping first breaks down thewood chemically, then by grinding.

The range of commercial pulping processescurrently used by the pulp and paper indu stryis shown in table 26. Nearly three-fourths of

the wood pulp is produced by the kraft proc-ess (fig. 22).

Mechanical Pulping

Commercial Mechanical Pulping Technologies

There are four basic mechanical pulpingprocesses: 1) stone ground wood pu lping, 2) re-finer mechanical pulping, 3) thermomechani-cal pulping, and 4) the recycling of paper. Flowdiagrams of the three mechanical pulping proc-esses are shown in figure 23. Mechan ical pu lp-ing is generally used with softwoods because

of the added strength imparted by the long fi-ber length of softwood species. Mechanicalpulps are used principally to manufacturenewsprint, printing p apers, and tissues that d onot require high-strength paper. Secondary



80 • Wood Use: U.S. Competitiveness and Technology

Table 26.—Major Commercial Wood-Pulping Methods, Grades of Pulp, and End-Products

Pulp grades

Chemical pulps: Sulfite pulp . . . .

Kraft sulfate pulp

Dissolving pulp

Percent yield perWood type dry weight of wood End-products, utilizing grade

. . . . . . . . . . . . . . Softwoods and hardwoods 53-56 bIc

45-50a’d

. . . . . . . . . . . . . Softwoods and hardwoods 40-50a

52-53b

. . . . . . . . . . . .Softwood 33-35

Semichemical pulps: Cold-caustic process . . . . . . . . . . . Hardwoods and softwoods 80-95

Neutral sulfite process . . . . . . . . Hardwoods 70-80

Mechanical pulps: Stone groundwoode . . . . . . . . . . . . Softwoods 95Refiner mechanical (RMP)

e. . . . . . Softwoods 95

Thermomechanical (TMP)e . . . . . .Softwoods 95

Fine and printing papers

Bleached—printing and writing

papers, paperboard. Unbleached—heavy packaging papers,paperboard

Viscose rayon, cellophane, acetatefibers, and film

Newsprint and groundwood printingpapers

Newsprint and groundwood printingpapers

Corrugating mediumNewsprint and groundwood printing

papersNewsprint and groundwood printing

papers —

aBleached pulps made from softwoods

bun bleached pulps made from softwoods.cUnbleached pulps made from hardwoodsdBleached pUIpS made from hardwoods

‘For paper and board

SOURCE George H Boyd Ill and Chad E Brown, Paper /r?dusfry. Ouf/ook for Market Pu/p (New York Kidder, Peabody & Co , 1981), p 5

Figure 22.— Proportions of Woodpulp Producedby Commercial Pulping Processes

Unbleached kraft380/o

Sulfite40 / 0

\ - - ’

Ground wood90 /

0

uses include wallpaper and paperboard. Re-

cycled pulp is used mainly for the manufactureof folding boxboard (grayboard), tissue, cor-rugated board, and newsprint.

In the stone groundwood (SG) process, de-barked short logs (round wood) are fed w holeinto grinders. The abrasion of the grinding

wheel against the wood physically separatesthe wood fibers. The grinding process usuallyis automatic and continuous, although some-times it is semicontinuous, Refiner mechani-cal pu lping (RMP) uses chips in lieu of round -wood and produces paper w ith higher strengththan conventional groun dw ood because of lessdamage to the fibers in the pulping process, A

wider range of species, including hardwoods,can be processed by the ref iner pulpingprocess.

The most advanced commercial mechanicalpulping system is the thermomechanical proc-ess (TMP), which was developed as a modifica-tion of the RMP process. In TMP, wood chipsare steamed for several minutes under pres-sures ranging from 4 to 45 psi and subsequentlyrefined in one or two stages.

Recycled pulp is manufactured from waste-paper, which is processed into paper stock forfurther use in making pap er. A small propor-tion of the paper stock (5 to 10 percent) is de-inked, usually with caustic, soda-based chem-icals. Most recycled pap er, however, is pulpedwithout de-inking. Pulping is accomplishedthrough violent agitation and shearing action






Figure 24.—Wood and Energy Flows in Mechanical Pulping Mills in ConjunctionWith Recycling

twaste paper

I

I

I

I 400 Ibs , ~

310 Ibs

wastepaper I

I

I

of kraft pulp to improve its wet strength andprocessing on the paper machine. While paperusing TMP consumes 11 to 13 percent lesschemical pulp than ordinary newsprint, im-proved materials efficiency is gained at the ex-pense of higher energy consumption. When thecost of energy is considered as w ell as the costof wood , TMP is actually m ore costly than SG.

Pulp yields from all the mechanical pulping

processes typically are near 95 percent recov-ery, which is a higher yield per unit of woodthan with the chemical pulping methods. Theprincipal variables that influence the choice of mechanical pulping methods are: 1) furnish(raw material) requirements or wood species,2) pu lp strength , 3) expected gross energy con-sumption, and 4) expected net energy con-

sumption.



Ch. III—Pulp, Paper, and Fiber Products q 8 3

The process variables that affect the qualityof mechanically produced pulp are listed intable 27. Increases in p aper strength are gainedby increases in energy consump tion, but bright-ness and opacity, qualities that affect the useof paper for printing, are largely independent

of the pulping pr ocess. Recycling can effective-ly reduce the consumption of both wood rawmaterial and energy when used in conjunctionwith other mechanical pulping processes.How ever, it does so at th e sacrifice of some p a-per strength.

Improvements in Mechanical Pulping

Technical improvements in mechanical pulp-ing have largely been directed at reducingenergy consumption and improving the qualityof mechanical pulps. Pulp yield is approaching

the practical upper limit, since all of the ligninand most of the hemicelluloses remain in thefiber, and fiber recovery from mechanical pulp-ing is frequently twice as high as that fromcompetitive chemical pulping. By reducingenergy costs, mechanical pulping has remainedcost competitive, and improvements in paperquality have enabled mechanical pulps to dis-place some of the more costly, higher qualitypulps produced by chemical processes. Asnoted in table 27, although improvements inquality result in some increases in the con-sumption of energy, the higher quality pulp

produced more than offsets the higher costs of energy.

Three major developments in mechanicalpulping technologies show promise for improv-ing pulp quality and/ or reducing energy con-sump tion: 1) pressurized ground wood (PGW)pulping, 2) chemithermomechanical pulping(CTMP), and 3) hardwood chemimechanical

pulping (CMP). Each of these new processeshas reached some stage of commercialization.A fourth major development is waste-heat re-covery.

PRESSURIZED GROUNDWOOD PULPING

In PGW pulping, debarked logs are fed to thegrinding w heel through a heated, p ressurizedchamber. The heat and pressure help separatethe fibers, breaking down fewer fibers in thegrinding process and improving pu lp qu ality.The longer fibers give the end p roduct a highertear index than paper made from SG, but it is

slightly inferior to that of TMP. The tear resist-ance for PGW pulp is 5.6, compared with 3.9for SG and 7.1 for TMP (table 27), The tensileindex for PGW p ulp (35) also lies between thatfor SG pulp (32) and TMP (37). In addition toimproved strength, PGW promises some reduc-tion in energy consumption. It is estimated thatthe energy requirement m ay be reduced by 40percent from th at required for the th ermome-chanical process, or from 1,833 to 2,417 kWh/ ton of pulp to approximately 1,100 to 1,450kWh/ ton.

43

43C;, \ V. E\ans, “Pressured Process for Grounciwoo[] Pr{jdl]( -

tion Making Health~’ Progress, “ })ujp a~]d }~a[}(~r, [’()] 54. 1980,pp. 76-78.

Table 27.—Summary of Process Variables for Mechanical Pulping (based on the production of 1 ton of ovendry pulp)

Process

Ground wood Refiner mechan ica l Thermomechan ica lVariable pulping pulping pulping Recycle

F u r n i s h t y p e . , Debarked logs Residual chips, Residual chips, Waste papersawdust sawdust

Furnish requirements . . . . . 2,100 lb 2,100 lb 2,100 lb 2,200 lb

Energy requirements (kWh/ton) . 1,340-1,790 1,800-2,400 1,800-2,000 360

Strength:

Burst . . . . . . . . . . . . . . . 1.4 1.8 2,0Tear . . . . . . . . . . . . . . . . . . . . 3.9 5,7 7.1

Tensile, . . . . . . . 32.0 35.0 37.0

Other:Brightness . 60.0 57.0 57.0Opacity . ., . 95.0 95.0 94.0




By 1980, five mills worldwide had installedPGW systems. Fifteen more plants have beenordered, including four to be located in theUnited States. Some ind ustry analysts considerPGW technology to have significant potentialfor reducing mechanical pulping energy re-

quirements and for displacing some high-qual-ity chemical pu lps in the man ufacture of new s-print and other printing papers.

CHEMITHERMOMECHANlCAL PULPING

CTMP involves treating softwood chips withmild sulfite solutions prior to pulping. This“sulfonation” treatment results in paper withhigher tear indices than do TMP, RMP, or SGpulping processes.

44Energy consumption for

CTMP may ran ge from 1,360 kWh/ ton to 2,000kWh/ ton, depend ing on the strength of thesulfite solution. Thus, energy consumption of

CTMP lies within the range of SG pulping, isless than that required for RMP or TMP, andresults in a higher quality paper. Pulp yieldsdecrease slightly to between 85 and 95 percentwith CTMP, but these yields are still large com-pared to chemical pulping and to mechanicalchemical pulp blends. Some TMP pulpmillshave begun to add sulfite chemicals in theiroperations to improve pu lp quality and redu ceenergy consumption.

HARDWOOD CHEMIMECHANICAL PULPING

Mechanical methods for producing pulpfrom underutilized hardwood species involvepretreating hardwood chips with hydrogenperoxide or sodium hydroxide and processingthem like RMP. Both poplar [softwood) and redoak (hardwood) have been pulped successfullyby th ese techniqu es. How ever, fiber recoveriesare lower for hardwood CMP than for soft-wood CMP. Pulp recoveries of 80 to 85 percenthave been reported for pop lar, 90 to 95 percentfor red oak.

Energy consumption for CMP ranges from500 to 1,500 kWh/ ton using hyd rogen perox-

ide for chemical pretreatm ent an d 700 to 1,100

.44~ A t a c k , et ~]., “Sulphite Chemimechanical Refiner Pulp-Another Option for Newsprint, ” Pulp and Paper, vol. 54, 1980,

Pp. 70-72.

kWh/ ton using sodium h ydroxide.45

HardwoodCMP consumes significantly less energy thando either SG or other chemimechanical hard-wood pulping technologies.

Pulp and paper technologists expect hard-wood CMP to expand significantly during the

next 10 to 25 years because of the large volumesof inexpensive hardw ood available, a phenom-enon that could have a profound impact on theutilization of presently underutilized speciessuch as poplars, red alder, and American syc-amore that are abundan t throughou t the East-ern United States. Pulp produced by hardwoodCMP can be used to produce newsprint andprinting papers. Two small U.S. mills, whichrange in capacity from 200 to 250 tons of pulpper day, have already installed CMP systemsto process hardwood species.

WASTE HEAT RECOVERY SYSTEMS

Mechanical pulping systems create a largeamount of frictional heat during the grindingand refining p rocesses. Heat recovery systemsthat enable use of waste heat (for drying pa-per, space heating, and water treating) are im-portant to the reduction of energy costs in thepu lping p rocess. Such systems are p articularlyimportant in TMP, which requires large quan-tities of mechanical energy and p roduces high-quality heat (i.e., high heat under temperatureand adequate pressure) .46 Because of the higher

temperature of waste heat from TMP proc-esses, a higher percentage of usable waste heatcan be recovered from TMP than from conven-tional groundwood pulping,

Heat recovery technologies currently recap-tur e 3 million to 5 million Btu/ ton of pulp p ro-duced.” For mills consuming 1,800 to 2,400kWh/ ton, 95 percent efficiency in heat recoverywould represent a total of 5.8 million to 7.8 mil-

45J, D. Sinkey, ‘lCMP and C’I’MP-A Review,” paper presentedat Forest Products Resear[;h Society Conference, St. Paul, Minn.,1981.

4EP, J. Walker and E, J. 13atsis, “Heat Recovery From TMP Oper-ations Results in linergy Consert’ation, Pulp and Paper, vol.52, 1978, pp. 146-148.‘T’rhe Fossj) ~’nerg~, ~’onser~,atjon Potential Associated W’iih

Producing Wood Pr’oducts From Managed Stands (Bellekwe,

Wash.: Envirosphere Co., 1981).



Ch. Ill—Pulp. Paper, and Fiber Products . 85

lion Btu.48

With current technology, the indus-try captures 50 to 65 percent of the theoreti-cally recoverable waste heat, Widespreadadop tion of these efficient systems has not yetoccurred because of the problems of retrofit-ting and high capital costs.

Future Prospects for Mechanical Pulping

The three major new mechanical pulping tech-nologies—PGW pulping, CTMP, and CMP—have improved pulp quality and reduced en-ergy consum ption compared with convention-al ground wood processes. The resulting higherquality mechanical pulps will displace the kraftpu lps that are currently mixed with m echani-cal pulps to improve paper strength. For ex-ample, the shift from SG pulping to TMP dis-placed 300 pounds of kraft pulp per ton of newsprint. Use of the new technologies willfurther reduce the amount of kraft pulp re-quired in newsprint and printing papers, re-ducing the demand for softwood timber be-cause the pulp yield from these processes isnearly twice that of kraft processes.

The configuration of mechanical pulpmillsfor newsprint manufacturing will likely changesignificantly during the next 10 to 20 years.By employing CMP and CTMP technologies,using a h igher percentage of hardw ood as rawmaterial, and installing highly efficient heatrecovery systems (85 percent recovery), the me-

chanical pulpmill of the future could reduceits heat requirements by 1.0 million Btu [300kWh/ ton of heat) and redu ce electrical energyconsump tion by 97o kWh/ ton of newsprintfrom that currently required by TMP mills.Savings of this magnitude of purchased elec-tric power is equ ivalent to a savings of 11 mil-lion Btu of heat inpu t at the pow erplant. In ad -dition, 3.5 million Btu of usable heat could berecovered, offsetting over 50 percent of thatcurrently required in the pulp and papermak-ing process.

Further improvements in energy efficiencyand wood utilization could result if a recyclepulpmill were integrated with either SG orTMP pulpmills (fig. 25). The practical upper

limit of recycled fiber in the pulp mix is esti-mated to be about 40 percent. A small propor-tion of kraft pulp is required in the mix tostrengthen the n ewsprint if larger p roportionsof recycled pulp are used.

49The major gains

in energy efficiency between a wholly round-

wood C M P or CT M P mill and one integratedwith a recycle pulpmill are in reduced electri-cal-energy consump tion. Redu ctions in energyconsump tion of between 179 and 358 kWh/ tonof pu lp m ay be achieved by recycling, so Proc-ess heat requirements remain approximatelythe same when recycling is used, but theamou nt of recoverable waste heat is d ecreasedfrom 3.5 million to 2,2 million Btu.

Substan tial techn ical improvements are p os-sible in mechanical pulping processes withinthe next 20 years, providing that economic in-centives exist an d capital formation is possible.

Chemical Pulping

Commercial Chemical Pulping Technologies

Chemical pulping processes involve treatingwood chips with chemicals to remove the lig-nin and hemicellulose, thus separating anddelignifying the fibers, Delignification gives thefibers greater flexibility, resulting in a substan-tially stronger sheet of paper—because of great-er contact between the fibers in the finishedsheet—than can be manufactured from fibers

with lignin produced by mechanical pulping.Two major chemical pulping technologies

are currently in use: 1) kraft (sulfate) pulpingand 2) sulfite pulping. The kraft process dom-inates the pulp and paper industry, account-ing for over 75 percent of all pulp producedfor paper and paperboard in 1979.

51O the r

chemical pulping processes, such as acid sul-fite pu lping, bisulfite pu lping, and n eutral sul-fite semichemical pu lping account for ap prox-imately 3 percent (the remainder was producedby mechanical pulping), Paper made from pulp




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produced by the kraft process accounts formost of the bleached boxboard and linerboardused by the packaging industry (which con-sumes 58 percent of the paper in the UnitedStates).

In addition, bleached softwood kraft pulpsoften are mixed with mechanical pulps to addstrength to newsprint and printing papers.Bleached hardwood kraft pulps are added tobleached softwood pulp to improve printabilityfor specialty paper products like magazinestock and coated papers.

KRAFT (SULFATE) PULPING

The kraft process involves treating woodchips and sawdust with a sodium sulfide andsodium hydroxide solution. The highly alkalinechemical mixture is cooked in a digester for

1 to 3 hou rs at temp eratu res ranging from 320°to 3500F (fig. 25). The complete pulp and pa-

per making process is shown in figure 26.

Fiber recovery from the kraft pulping proc-ess is largely a function of the wood speciesused, the amount of chemicals used, the timeand temperature of cooking, the degree of bleaching, and the paper strength required.Generally, kraft pulp recoveries from soft-woods are approximately 47 percent for un-bleached pulp and 44 percent for bleached. s’Hard wood recoveries range from 50 to 52 per-cent for unbleached kraft pulp and 45 to 50 per-cent for bleached.

Energy is used in a mill in different forms(as chemical heat of reaction, as thermal ener-gy, and as electrical energy), and these typ icallyare expressed in different units (Btu for ther-mal and for heat of reaction in fuel combus-tion, and kWh for electricity). While the unitsmay be converted simply (i.e., 1 kwh = 3,412Btu), the actual forms of energy may not be con-verted without loss of energy available for do-ing useful work. Thus, in a typical pow erplant,it takes 10,000 Btu of heat input to produce 1

kWh of electricity (in contrast to the u nit con-version above), and two-thirds of the input is

szp, J Hu~~ey, Comparison of Mills Energy Balance: Effects

of Conventional Hydropyrolysis and Dry Pyrolysis Recovery Sys-tems (Appleton, Wis.: Institute of Paper Chemistry, 1978).

lost as exhaust. There are, then, two ways tocompare a m ill’s energy u ses: 1) simple unitconversions, representing all uses in a commonun it; or 2) representing all uses in terms of theheat values of their original forms, while recog-nizing energy conversion losses.

The different conclusions reached by theseapproaches is illustrated by the following: thefirst method gives rise to the conclusion thatself-generation in today’s typical kraft papermill provides about 50 percent of the mill’s en-ergy need s, wh ile the second method (table 28)

shows that 82 percent of the primary fuel sup-plying the total energ y need s of a typical kraftmill is self-generated. The first m ethod relatesbetter to concerns for fossil-fuel avoidance,while the second helps relate the fuel value of wood -process residua ls to other p otential uses.

Of the two approaches, the latter is the moreuseful for assessing process efficiency.

Energy consumption is a major cost in themanufacture of kraft pulp and paper. The com-bined process requires approximately 30 mil-lion Btu of primary fuel per ton of bleachedkraft paper (table 29). This energy value in-cludes fossil fuel burned at an outside power-plant to provide purchased electricity as wellas the thermal energy derived from the w oodresource. Approximately 78 percent of the en-ergy demand is for thermal energy used in theplant, the major portion of which is used for

pap er m aking an d self-generation of electricityrather than in the pulping process. While thecombined kraft pulp and paper making proc-ess requires approximately 1,050 kWh/ ton of electricity, mostly for drive motors, all but 101kWh generally is produced internally throughcogeneration (table 29). Burning waste liquorsand bark provides 82 percent of a mill’s pri-mary energy needs.

The kraft process is suitable for pu lping bothsoftwoods and hardwoods. Wood chips, saw-du st, and wood residu es from sawm ills and ve-

neer m ills can be used as furnish, Over 35 per-cent of the total wood supp lied for kraft pap erare wood residues. In the Pacific Northwest,nearly 90 percent of the wood originates fromsawmill or veneer mill residues. Whole treechips, including bark and branches, currently



are used in limited quantities, although their

proportion of the total furnish is increasing. Be-cause of the density, extractive content, andchemical nature of these materials, increasesin their use may cause the pulping liquors(chemicals) to react more slowly, resulting ina need for longer digestion periods and in-creased energy expenditures.

SULFITE PULPING

The four fundamental sulfite pulping proc-esses currently in commercial use are: 1) acidsulfite, 2) bisulfite, 3) neu tral su lfite, and 4) al-

kaline sulfite. The major differences betweenthe sulfite processes are the levels of acidityand alkalinity of th e sulfite chemical solutionsused to break down the wood and remove thelignins. The cooking liquor consists of a saltbase—generally calcium, magnesium, sodium

or am moniu m—and sulfuric acid. Sulfite proc-

esses are suitable only for species with low ex-tractive contents, i.e., those low in tannins,polyphenols, pigments, resins, fats, and thelike, because of the interference of these sub-stances with the sulfur pulping process. Al-though calcium is the cheapest base available,it forms insoluble compounds that cannot bereclaimed economically or disposed of easily.Thus, calcium-based pulping is seldom used.Because magn esium - and sodiu m-based chem-icals are recoverable, and ammonium-basedchemicals can be burned without harmful envi-ronm ental effects, they are the most frequen tly

used.

Sodium-based sulfite pulping can consist of multistage cooking, successive stages of whichdiffer in acidity. Because one stage optimizeschemical liquor penetration and the other the




Table 28.—Energy Demand Per Ton of Kraft Paper

Thermal: Process:

Digester. ... .

Bleach plant .Paper machineEvaporation. .,Liquid heatingOther . . . . . . . .

Subtotal ... . .Lime kiln . .

Total . ... . .

Electric: Self -generated:

Energy demands

Million Btu

. . . . . . . . . . . . . 3.8

. . . . . . . . . . . . . . 2.4

. . . . . . . . . . 6.8

. . . . . . . . . . . . . 3.0

. . . . 2.9

. . . . . . . . . . . . 2,5

. . . . . . . . . . . . 21,4

. . . . . . . . . . . . . . 2,0

. . . 23.4

. . . .Fuel-value material recovered inplant and burned for electricity 5.7

b

Purchased f rom ou ts ide : . . . . . .Fuel used by outside powerplantto produce electricity . . . . . . . . 1 .0

c

Totals:

Total electricity . ... . ...Total fossil fuel consumed . . . . . . 30.1

—

aHurley, P J

kWh

949a

101 a

1,050

blncremental heat ra[e tO generate electricity In plant 6000 BtulkWh

cAssumes out SI de electrlc PI ant IS fess! l-fueled at 10,000 BtulkWh

SOURCES J J Watkins and W S Adams, “The St Regls Hydrolysis Processas an Approach to Energy Conservation In the Pu 1P & Paper Industry, ”Proceed~ngs of TAPP/ ’78 Engfr?eenrrg Corrference Book /// P J Hurley, Corrrpar/son of Mi//s Energy Rdar?ce Effects of Conven

f /ona/ H y d r o p y ro / y s / s and Dry Pyrolysls Recovery Sys(erns (Appleton,WIS Institute of Paper Chemistry, 1978)

removal of lignin, more lignin may be rem ovedwith less fiber degrad ation, so that fiber yieldsare higher, fibers are stronger, and a widerrange of wood species may be used. Neutral

sulfite pu lping, using sodium and ammoniumbases, recovers the largest proportion of fiber(75 to 90 percent) of all the sulfite pulpingmethods.

Improvements i n Chemical Pulping

Two kinds of improvements have been madein chemical pulping technologies: 1) better effi-

ciency of current processes and 2) developmentof new pulping technologies that depart fromthe conventional commercial processes. Thegreatest potential for dramatically improvingpulp and paper manufacturing lies in new tech-nologies. Such innovations could enable the

use of large quantities of currently underuti-lized hardwood species and may even haveprospects for d eveloping sup erior new papersfor future specialized uses. At the same time,new concepts in energy use and cogenerationcould achieve new levels of energy efficiencies.Among the most promising new pulping andpapermaking processes are: 1) press-dried pa-per, 2) green liquor pulping, 3] autocausticiz-ing, and 4) pyrolytic recovery of chemicals inspent pulping liquor. These developing tech-nologies are not yet commercially available.

PROCESS IMPROVEMENTS

Major efforts in process improvements, ormeans in which the efficiency of existing com-mercial processes is improved, have centeredon increasing fiber recovery and energy effi-ciency. Most such efforts have focused on thekraft process, wh ich p rodu ces 90 percent of allchemical pulps manufactured. Greatest empha-sis has been placed on reducing energy con-sumption because it is the largest cost factor.

Anthraquinone (AQ) recently has been testedas a catalyst in kraft pulping. When added in

small quantities to the cooking liquor, AQspeeds up the pulping process and can improvefiber recovery by as much as 2 to 4 percent.Although the percentage increase in yield mayseem small, the increases in a bsolute yield areconsidered substantial because of the verylarge volumes involved. AQ pulping was de-veloped by Canadian Industries, Inc., and is

Table 29.—Energy Consequences of Pyrolytic Recovery (basis: 1 ton pulp)

Recovery methodEnergy required Conventional hydropyrolysis Dry pyrolysis

Process yield (percent ovendried) . . . . . . . . . . . . 47.5 48.75 47.5Electricity (kWh):

Internally generated . . . . . . . . . . . . . . . . . . . . . . . . . 949 850 812Purchased . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 256 258

Inplant fossil fuel (thousand Btu) ... . . . . . . . . . . . . . . . 10,411 5,458 6,296Inplant fossil-fuel savings (percent). . . . . . . . . . . . . . . . . . . . 48 0/0 40 ”/0

Paper Chemistry 1978)




used commercially in both Japan and theUnited States. Its potential broad-scale applica-tion in the Un ited States, however, maybe lim-ited by its cost and the lack of technology torecover the used AQ.

53The U.S. Food and Drug

Administration (FDA) recently has approved

AQ for use in paper packing for food, open-ing new market potentials for AQ pulp.

The industry’s goal is for the kraft pulpingprocess to become as energy self-sufficient aspossible. Substantial gains in energy efficiencyare expected within the next 20 years, but itis not known whether total self-sufficiency isattainable. Kraft mills may approach self-suf-ficiency if some modifications are made; forexample: 1) the temperatures in boilers thatburn wood residues and black (lignin) liquorcan be reduced (primarily by adding more ef-

ficient heat exchangers for heat recovery, and2) lime kilns maybe fueled w ith dried saw du stwithout seriously contaminating the calcinedlime used for making the pulping liquor. Thelatter has been demonstrated successfully inSweden.

54These system modifications are ex-

pensive and may increase the operating costsof a plant. Their adoption will depend on thefuture costs of energy and the availability of capital.

GREEN LIQUOR PULPING AND AUTOCAUSTICIZATION

Economy in chemical pulping depends on ef-

fective recovery of chemicals from the usedcooking liquor. Upon interaction with w ood inthe cooking process, the “white liquor, ” thatis, the original sodium sulfide and sodium hy-droxide solution, becomes “black liquor,” richin lignin salts and other organics removed fromthe w ood in th e pu lping p rocess. The black liq-uor is pum ped to evaporators that remove thewater and concentrate the remaining salts andorganic solids. The resulting viscous solutionis burned in a recovery furnace to remove theorganic residues (fig. 26).

The remaining salts—mostly sulfides and car-bonates of soda—form a molten stream re-

ferred to as “smelt” and are recombined withwater to form “gr een liquor . ” The sodiu m car-bonates in the green liquor normally are con-verted into hydroxides for reuse by the addi-tion of calcium hyd roxide in a p rocess referredto as “causticizing.”

Pulping of hardw oods and softwoods usinggreen liquor, which eliminates the causticiz-ing process, is now an accepted commercialtechnology for prod ucing semichemical pu lps.In this process, disodium borate is used insteadof sodium hydroxide in the original white liq-uor, and the liquor p roduced by d issolving thesmelt can be reused d irectly in the digester. Inthis way, the entire regeneration loop, includ-ing the lime kiln, is removed. As much as 18percent of the fossil energy required for pulp-ing can be eliminated by autocausticization.

Elimination of the lime kiln not only reducesenergy consumption, but reduces capital costsby $35/ annu al ton of capacity and operatingcosts by $3/ ton.

55Industry experts give auto-

causticizing a high probability of commercialacceptance.

PYROLYTIC RECOVERY

Technology for pyrolytic recovery of black liquor has been d eveloped in tw o pr ocesses: 1)a hydrop yrolysis method d eveloped by the St.

Regis Paper Co., and 2) a dry pyrolysis methoddeveloped by Weyerhauser Corp. Pyrolytic re-

covery consists of applying h eat in the absenceof oxygen (anaerobic combustion) to decom-pose the organic compounds in the black liq-uor. These new spent-liquor recovery tech-niques, designed to extract energy from thespent liquor while retaining the chemicals forreuse, are more energy efficient than are cur-rent p rocesses. They are importa nt because re-generation of the pulping chemicals requiresa large share of the energy used in th e pulp ingprocess.

Hydropyrolysis technology currently is be-

ing evaluated on a pilot basis in St, Regis’ Pen-sacola, Fla., mill. The process shows potential

53Hub~r, op. cit., P. 85.

WK . Lappe, “Advanced Drying Process is Key to Burning Peat,

Wood Byproducts, ” Energy Systems Guidebook (New York:McGraw-Hill, 1980).

‘5]. Jansen, “Pulping Processes Based on Autocausticizable

Borate, ” The Delignification Methods of the Future (Helsinki,Finland: Europa Symposium, 1980).




for reducing the energy requirements for evap-orating weak black liquor, i.e., that recoveredin the initial washing stage, and for aiding inthe energy recovery process. It is estimated thatfossil-fuel energy required for generation of process heat may be reduced by 50 percent

with the application of hydropyrolysis technol-og y.

56

St. Regis’ experience with its pilot plant in-dicates that application of hydropyrolysis tech-nology results in a tradeoff between purchasedfossil fuel and purchased electricity. Loweredheat requ irements for liquor recovery result inless process steam; thus, the potential for co-generating electricity along with the steamneeded is limited. The results of these trade-offs are shown in table 29, wh ere the data su g-gest that an in-mill fossil fuel savings of up to

48 percent can be achieved with hydropyroly-sis and approximately 40 percent with drypyrolysis. How ever, considering the fossil fuelused to generate the purchased electricity, thenet fossil fuel savings are 28 percent and 20percent, respectively.

OTHER CHEMICAL PULPING TECHNOLOGIES

Attempts to develop alternative pulping tech-nologies that increase yields, energy efficiency,and pulp quality of the kraft process have ledto two new chemical pulping concepts thatshow some promise: 1) organosolv (alcoholysis)

pu lping and 2) oxygen pu lping. Since both stillare under development, and nei ther hasreached the demon stration stage, they mu st beconsidered long-range (25 + years) prospectsfor commercial application,

Organosolv Pulping.-Organosolv pulping is atwo-stage process involving hydrolysis (decom-position of the wood by dilute acids or en-zymes) and the removal of lignin with an or-ganic solvent, usu ally a mixture of alcohol andwater. The still-experimental process is suitablefor both hardwoods and softwoods. Pulp recov-

ery from organosolv pulping ranges between50 and 60 percent for hardwoods, and 40 and45 percent for softwoods. Typical hardwood-fiber recoveries compar e favorably with those

from kraft pulping: approximately 50 percentfor red alder, sweetgum, and American syca-more, and 60 percent for cottonwood and trem-bling aspen.

Fibers produced by the organosolv processare weaker than those recovered by the kraftprocess, Thus, the papers produced fromorganosolv pulp are suitable for uses wherestrength is not the most important property,such as for printing papers, fluff pulps, anddissolving pulp,

Reaction temperatures are low—between320° and 370° F for hardwoods and 360° to390

0F for softwood s if acid catalysts are u sed.

Little waste is produced by the process, andlow alcohols are recovered easily by distilla-tion, thus requiring relatively low capital in-vestment .57

Oxygen Pulping.—An extension of existing ox-ygen bleaching technologies, oxygen pulpingmay reduce or eliminate the need for bleachingplants in the paper mill. Oxygen pulping in-volves the introdu ction of gaseous oxygen intothe pulping liquor to stimulate oxidative frac-ture of the cellulose-lignin bonds. This proc-ess could save capital and operating costsbecause equipment costs are lowered, lessbleaching chemicals are used, and pollutioncontrol expense is cut by eliminating chlorinefrom the bleaching process.

The cost of oxygen pu lping is largely a func-tion of the cost of oxygen. Oxygen prod uctionrequires ap proximately 400 lbs of oxygen and54 kWh/ ton of pu lp produ ced (based on 1.2kWh/ hu nd red cubic feet(H3),or0.135 kWh/ lb.Several manufacturers currently are develop-ing plant equipment capable of applying oxy-gen pulping commercially.

PRESS DRYING PAPER

Press drying technology developed at FPLshows promise for both reducing the amount

of energy required in the paper-making proc-ess and enabling the use of underutilized hard-

57N Sa ~, b. er , .$ta tcls of N~t%F Pulping Processes; Problems (i tl[]pe~s~ectjl,es (~fa~ison, Wis,: U.S. Forest Pro d u c t I.aborat(}r},

1982], p. 10,




wood species. Press drying uses high-yieldhardwood or softwood kraft pulp to producelinerboard with strength superior to that of conventional softwood kraft paper in every re-spect except tear strength (table 30). At thesame time, press drying can reduce the amount

of energy used in the d rying pr ocess by app ly-ing pressure to the fiber (pulp) mat as it is dried.With conventional drying technology, pressureand heat are applied separately.

The superior strength of press-dried papercomes from the combined effects of heat andpressure, which force the fibers into closer con-tact and cause stronger bonds to be formed be-tween them. The heat and pressure also causenatural polymer flow and cross-linkages amongthe fibers as a result of the hemicellulose con-tained in the pu lp. Paper produced from press-

drying kraft red oak pulp has been shown tohave burst strength and tensile strength ap-proximately 13 percent higher, and compres-sion strength 50 percent better, than that of conventionally dried pine kraft paper. Thelower tear strength of press-dried hardwoodpaper may limit its use for wrapping or sack paper; however, its higher burst strength andtensile strength make it su itable for linerboard.

Estimates of the p otential net energy savingsfrom using press-drying technology are about19 percent for the papermaking process,

58Al-

though a commercial-scale, press-dried paper-making machine has not been built yet, pressdrying may actually reduce equipment require-ments and capital investment in both the d ry-ing section and the pulping process because

it can use unrefined pulp.59

The major limita-tion to press drying paper, which must be over-come before the technology can be appliedcommercially, is the low speed of the paper-making machine and the resulting slow pro-duction rate of the pilot-scale equipment used

at the FPL.

Dissolving Pulp Technologies

Dissolving pu lp technologies are not pulp ingtechnologies as such, but secondary processesthat produce nearly pure cellulose (alpha-cel-lulose) for conversion to rayon, plastics, andother chemicals. Pulps mad e by either the kraftor sulfite process are purified further chemi-cally to remove all hemicellulose and leave onlypure cellulose, which then can be transformedinto products like viscose rayon, cellophane,

and acetate fibers and film. The largest singleuse for dissolving pulp is in the viscose rayonprocess, which accounts for over 99 percentof the world’s rayon production.

A variety of hard wood and softwood speciesis suitable for the production of dissolvingpulp, including pine, hemlock, spruce, oak,birch, and gum. Highly resinous wood, suchas Southern yellow pine, normally is not usedfor dissolving pu lp because of the difficulty of removing extractives in the purification proc-ess. The highest grades of dissolving pulp are

called cord, acetate, and nitrate pulps, whichapproach 98 percent pure cellulose; normalgrades of viscose rayon pulp contain somehemicellulose and maybe only 93 percent pure.Because of the need for nearly pure cellulose,

“v. Setterholm and Peter Ince, “The Press Drying Conceptfor Papermaking, ” Southern Lumberman, Dec. 15, 1980.

59P. J. Ince, “FPL Press Drying Process: Wood Savings in Liner-

board Manufacture,” TAPPI, vol. 64, 1981, p, 109,

Table 30.—Strength Properties of Press-DriedHardwood Paper and Conventional Softwood Paper

Anticipated Present Conventional

strength strength strengthwith oak with oak with pine

Burst strength (lb/in w)a. . . . . . . . . . . . . . . . 155 145 97

Tensile strength (lb/in w) . . . . . . . . . . . . . . . 100 68 54Compression (lb/in w) . . . . . . . . . . . . . . . . . . 45 30 20aPounds per inch of width

SOURCE U S. Forest Products Laboratory, 1981



Ch. lIl—Pulp, Paper, and Fiber Products q 9 3

pulping yields for the kraft and sulfite proc-esses are reduced to approximately 28 to 38

percent, depending on the p ulp p urity desired.The low yield of high-quality, alpha-cellulosepulps makes them expensive to produce—en-ergy and pulpwood costs account for 50 to 60

percent of the manufacturing costs.60

Total U.S. production of dissolving woodpulp was approximately 1.5 million short tonsin 1979 (23 percent of world production). Ap-proximately 61 percent of the dissolving pulpproduced was used for textile fibers; the re-mainder w as used for the manu facture (in d e-scending order) of chemicals and plastics, cel-lophan e, cellulose nitrate (for prop ellants), andspecialty papers for use in ind ustrial and au to-motive filters.

In addition to the viscose rayon process forthe p rodu ction of fibers and celloph ane (whichis made by the same viscose process but is ex-trud ed throu gh a slot to form film rather thanthrough holes to form threads), cellulose maybe converted into acetate forms (acetyl esters)that can be manufactured into cellulose ace-tate, cellulose diacetate, and cellulose triacetatefor conversion into fibers. Cellulose nitratecontinues to be produced in significant quan-tities as an explosive and a propellant. Otherproducts manufactured from dissolving pulpinclude ice cream thickeners, detergents, car-

bon fibers of high strength and stiffness, andgels used in hand lotions and food products.

Rayon Manufacture

Rayon, first made in 1881, is the oldest man-made synthetic fiber. The success of rayon inth e

q

q

market is due to several factors:

Cellulose continues to be the cheapestpolymer for fabrics.Rayon’s m oisture absorp tion, capacity forabsorbing dyes, and ability to swell makesit suitable for clothing. Rayon also can be

blended with other synthetic fibers, likenylon, to improve their moisture-absorbingqualities.

OOC , B. Metz, “Dissolving Pulps-The Future Economic Situ-ation, ” Proceedings of the 5th International Dis.~ol~in,g Pulp.s

C o n f e r e n c e (~’ienna, Austria: Oct. 8-10, 1980).

q properties of the dissolving pulp can bevaried to prod uce pulp s suited for specificend uses. For example, ITT Rayonier, aleading U.S. producer of dissolving p ulps,offers 16 grades of pulp matched to theproperties of the rayon to be produced.

Rayon is made by dissolving cellulose xan-thate in alkali and spinning the fiber throughsmall pinhole jets into a sulfuric acid bath,which coagulates the fiber into final form. If the same xanthate-viscose solution is forcedthrough a narrow slit, a cellophane film isformed.

Major developments in rayon technologyhave been aimed at:

improving the efficiency of rayon pro-duction;

reducing energy requirements;controlling or eliminating environmentalpollutants generated by the viscose rayonprocess;developing m ore cottonlike rayons to sup -plement cotton production; anddeveloping a completely new system forconverting chemical cellulose to fiberby a nonviscose, environmentally sound,more efficient process using recoverablecellulose solvents.

6l

Major emphasis has been placed on devel-

oping a rayon w ith a high wet-strength to rem-edy the shortcomings of conventional rayonand to compete with cotton more effectively.A number of new fibers outperform conven-tional rayon; they include Courtauld’s “Cor-val, ” a cross-linked fiber; American Viscose’s“Avril”; and Enka’s “Fiber 700. ”

Process developments within the rayon in-du stry seem to be moving toward au tomationand computer control. Experts foresee new,versatile rayons made by solvent-extrusionprocesses similar to those used for making ny-lon and polyester. These may lead to a futureo n e - s t e p process from pulp to viscose solution;

h o w e v e r , m a n y o f t h e c u r r e n t d e v e l o p m e n t s i n

t h i s a r e a a r e t r e a t e d a s p r o p r i e t a r y a n d a r e n o t

o p e n t o i n s p e c t i o n .

“G, Daul, “Rayon Revisited, ” Chemtech, Februarj 1981, p. 84.




The viscose process is one of the most ver-satile for manufacturing textile fibers. Modi-fication of the viscose manufacturing processeasily can accomm odate stretching an d orient-ing the fiber and building certain desired prop-erties into it. For examp le, it is known that th e

addition of metallic salts, such as zinc andother modifiers, will delay the reformation torayon to allow time for spinning and manipu -lating the fiber. Formaldehyde also has beenfound to be an effective modifier for the pro-duction of super-strong fibers; however, envi-ronmental problems associated with it muststill be overcome.

62

Research to improve the strength and per-formance of rayon materials continues. Theseefforts includ e the search for new solvents foruse in the spinning (forming) process. One suchprocess that show s prom ise uses a special sol-vent (methyl-morpholine-N-oxide, MMNO) toorient the m olecules in solution to form rayonwith high-strength cellulose fibers. Success of the MMNO process may depend on develop-ment of a solvent recovery system needed tomake th e manufacturing p rocess econom icallycompetitive.

63Some experts see the testing of

other new solvents lead ing to a major new sys-tem for manufacturing rayon.

64

Other Cell ulosic Products

A number of other

from dissolving pulp.

‘Z1bid., l]. M.

products can be made

For example, cellulose

L33R, N. A rms t r ong , C. C. McCorsky, and J. K. Varoa, ‘‘Spin-

nable Solutions of Cellulose Dissolved in Amine Oxides, ” f%o-

ctxxiings of the 5th International llissol~’ing PUII>S Conference[Vienna, Austria: oct. 8-10, 1980).

~411, I,. Hergert, R. B. Hammer, and A. F. Turbak, ‘‘New Meth-

ods for Preparing Rayon, ’ Proceedings of the 4th InternationalDissol~ing Pulps Conference (Chicago, 111.: Sept. 28-30, 1977),

acetate is produced by steeping dissolving pulpor cotton liners in acetic acid to prep are fibersfor conversion to acetate, This same processmay be used to p rodu ce cellulose butyrate andcellulose propionate for the production of plastics.

An acetate of slightly different chemicalform, cellulose triacetate, also can be madefrom d issolving pulp . Unlike rayon, it is water-repellent like nylon, orlon, and terylene. Itswater repellency is attributable to the degreeof acetylation of the fibers. It has good ther-mal properties and wear characteristics, andfrequently is used in fabric blends with nylon,wool, and rayon in women’s clothing.

Cellulose esters—acetate ester, acetate butyr-ate, and acetate propionate—are a family of plastic materials derived from d issolving pu lp

that can be formed, molded, and extruded bya variety of thermoplastic processes. Higherforms of these materials also maybe prepared;however, their high production costs restrictthem to highly specialized applications suchas cellulose acetate ph thalate, which is used asa coating on pharmaceuticals. Cellulose esterpow ders are used in fluid ized-bed and electro-static coating p rocesses, as well as in rotationalmolding processes. Modified cellulosic poly-mers are used in preparation of films, coatings,fibers, lacquers, and adhesives,

Finally, dissolving pu lps also may be u sed toproduce a variety of chemical products, includ-ing m ethyl- and carboxymethy l-cellulose, thatare used as thickeners in latex paints and icecream; ethylcellulose, used as a thermoplasticmolding compound; and nitrocellulose, usedas a propellant/ explosive.