Textile glass output climbs in 1969

Production (millions of pounds)

CERAMICS:

"Polycrystar Armor The Air Force Materials Laboratory has fabricated a transparent magne­sium oxide "polycrystal" that may see double-duty as windshield and ar­mor on U.S. combat helicopters.

The prototype ceramic sheet, meas­uring 11 inches in diameter and 3 / 1 6

inch thick, is the largest piece of optically transparent ceramic ever pro­duced, AFML says. The disk—several more of which have now been made— was formed by hot pressing magne­sium oxide at 4000 p.s.i. at a maxi­mum temperature of about 1100° C. About 0.3% lithium fluoride was added as a "densification agent," proj­ect engineer Lawrence Kopell notes. Although the exact mechanism of the fluoride action is unknown, the com­pound promotes sintering and helps eliminate residual porosity.

An annealing step (1000° C. for 60 hours) follows hot pressing to drive off the lithium fluoride and any other gaseous components that might reduce transparency. The resulting ceramic-free of trapped pores and gases—is then ready for polishing.

Currently, the polishing step is the chief roadblock in the way of a re­liable manufacturing process. If grain size is greater than 25 microns, polish­ing results in crystal pullout. And even when the proper grain size has been achieved, putting optical finish on the magnesium oxide ceramic is difficult. Eastman Kodak, using its own proprietary technology, polished the prototype sheet but AFML is con­tinuing its own research on this phase of production.

Ultimately, AFML hopes to hot press several ceramic "tiles" at once, and produce optically transparent tiles of polycrystalline magnesium oxide up to 8 X 8 inches square with thick­nesses of 3 / 4 inch. Though the armor­ing capabilities of such tiles are classi­fied, Mr. Kopell says that they would certainly be capable of turning 30-caliber, armor-piercing small arms fire. The plexiglass now used in helicopter windshields affords crews no protec­tion, Mr. Kopell notes.

GLASS FIBER:

PPG Optimistic Last week, PPG Industries conducted a press tour of its glass fiber plant at Shelby, N.C., on the completion of an expansion program there. The com­pany tripled the capacity of that plant to 25 million pounds a year of resin-coated textile glass fiber for tire cord. The magnitude of the expan­sion and the company's marketing op­

timism for glass-belted tires suggest a bright future for the textile glass fiber industry.

X&EN estimates that the 10 U.S. textile glass fiber producers, led by Owens-Corning Fiberglas and PPG Industries, will make about 490 mil­lion pounds of fiber in 1969, up 22% from 399 million pounds in 1968. Latest production figures from the Textile Economics Bureau support this estimate. Production of textile glass fiber for the first three quarters of this year is 357 million pounds, If production in the fourth quarter reaches 133 million pounds from the third quarter level of 128 million pounds, then the year-end output will total 490 million pounds.

Looking ahead, most producers are forecasting an average annual pro­duction growth rate of 16% for the 1969-74 period. C&EN estimates that the industry's sales will total about $220 million this year, based on an average selling price of 45 cents a pound for all fibers.

The current success of the glass-belted tire will continue to enlarge what is now a 45 million pound-a-year market to a ceiling of about 90 mil­lion pounds in the mid-1970's. Dur­ing the press tour, Robert A. Mc­Laughlin, vice president and general manager of PPG's fiber glass division, indicated that nearly 60% of all 184 million tires to be shipped domesti­cally this year are glass-belted. By 1975, he estimates, about 85% of the 228 million tires to be shipped that year will be glass-belted. Most of this penetration will come in the re­placement tire market since more than 90% of all original equipment tires this year are made with glass belts and biased polyester cord.

The future of glass fiber in tire constructions is clouded, however, by

the competitive and strategic business of selling tires and tire cord fiber. Firestone, for example, recently de­veloped a rayon-biased rayon-belted tire, partly to free itself from having to follow Goodyear's technological and marketing lead with its Polyglas tire. Other tire makers as well as fiber pro­ducers are continuing to test other combinations of fibers and construc­tions. Du Pont, for example, is test­ing congener forms of Qiana nylon as a tire cord material. Certainly, the use of textile glass fiber is not guaran­teed forever, but the fiber does ap­pear to have a stronghold in the market at least through the mid-1970's.

SEALANTS:

GE's Low-Cost Silicone General Electric is coming out of its premium-priced corner of the big and growing building sealants market to take on the number one seller, poly-sulfide. The weapon is a new low-cost silicone called sealant 1600. The two-part elastomeric sealant is priced a full $10 per gallon below what GE was selling before, two one-part seal­ants in the $24 to $27 range.

The new silicone's price range, $14.50 (for large jobs) to $17.50 per gallon, still exceeds the polysulfide range, which GE figures at $11 to $14 per gallon. GE manager of construc­tion materials marketing Donald V. Brown states that two-part polysulfides make up as much as 50% of the total synthetic sealants market. He feels that silicones, with the best overall value-price relationship, could capture at least 30% of the field in the 1970's.

Other synthetic sealants now sold are one-part polysulfide at $15 to $18, one-part acrylic at $10 to $12, one-

DEC. 8, 1969 C & E N 15

Source: Textile Economics Bureau