•riÉMiÉo;i«RiiiSl| NEWS the newsmagazine

of the chemical world VOLUME 35, NUMBER 52 | DECEMBER 30, 1957

ΜψΜ.

United States Patent Office 2,816,883 Patented Dec. 17, 1957

2.81M83 PRODUCT AND PROCESS OF POLYMERIZING

ETHYLENE Arthur W. Larchar, Mendenhall, P · . , and Donald C.

Pease, Wilmington, Deln assignor* to E. I. da Poot de Nemours SL Company, Wilmington, Del., a corporation of Delaware

No Drawing. Application August 2, 1951, Serial No. 240,044

6 Claims. (CL 260—94.9)

This invention relates to new macromolecular poly­mers of ethylene and to methods for tbeir preparation. The application is a continuation-in-part of copending application, S. N. 739,264, filed April 3, 1947, now aban­doned. Subject matter described and claimed herein was disclosed in applicants* copending continuation appiica- 20 reaction

Unity. Other objects and advantages will hereinafter ap­pear.

This invention provides new ethylene polymers pos­sessing a combination of properties unatlamed in any huherto known ethylene polymer. These ethylene poly­mers melt in the range of 127* to 132* O , have a stiff­ness modulus of from 137,000 to 215.00O lbs./in.a, a breaking strength, based on the drawn dimensions, of 40,000 to 55,000 ib./in.a, an elongation at break of 1200

ι to 1300%, a relative viscosity of from 1.0 to 1.5, measured at 0.125% concentration in xylene at 85* C., a degree of chain branching corresponding to less than one side chain per 200 carbon atoms in the main polymer chain, and an amorphous content of not more than 10%.

> The novel ethylene polymers of this invention are made by subjecting ethylene to pressures of from about 5,000 to 20,000 atmospheres at temperatures above 45* C. but below 200* C , preferably in the presence of a material which yields reactive free radicals under the conditions of

tion, Serial Number 563,699, filed February 6r 1956, and now abandoned.

It is known that when ethylene is subjected to pressures in the range of 500 to 3000 atmospheres, at temperatures of 100" to 300° C , it polymerizes to products ranging 25 from oily liquids to wax-uke solids. As generally pro­duced, the wax-like solids melt in the range of 100* to 120" C , have an average density of 0.925, an elongation at break of 550 to 700%, a tensile strength on final cross-

In a preferred method for preparing the novel ethylene polymers of this invenuon, a pressure reactor is charged with a solvent, such as an aromauc, cycloaliphauc, or paraffmic hydrocarbon, or an alcohol, and from 0.01 to 1%, based on the charge, of a substance wâich yields re-acuve free radicals under the condiuons of reacuon, such as an organic peroxy compound or azonitrile, the reactor is connected to a source of ethylene and pressured to the selected pressure with ethylene. The reactor is. then

section of 16,000 lbs./in.a, a stiffness modulus in the 30 closed and heated to between 45 and 200* C , preferably range of 16,000 to 21,000 lb./in.a, an amorphous content of the order of 22%, a degree of chain branching corre­sponding to about one side «chain per 20 carbon atoms m the chain, and an inherent viscosity of 0.92 measured at 0.125% concentration in xylroe at 85* C. Although this represents a remarkably combination of properties, for many industrial u«s they fall short of meeting even mini­mum requirements.

It is al«o known that in the presence of specific catalysts,

to between 40 and 100* C , and the pressure within the reactor maintained by further compression. After the desired degree of reaction has been attained, the reactor is allowed to cool to room temperature, opened, and the contents discharged. The polymer is then isolated by convenuonal methods. The polymers produced m ac­cordance with the process of tJbu> invcauon have melting points ranging from 127* to 132* C

Melting point is determined under a microscope having and under certain conditions of temperature and pressure, 40 a micro-heating stage provided with controlled means for „arbon monoxide and hydrogen react to give methanol and branched chain higher alcohoU (U. S. Patent 1,770,165). It is also well known that under certain other conditions

1 involving the use of certain cobalt-containing or ruthenium-contaimog catalysts, the reaction between carbon monox­ide and hydrogen leads to the formation of paraffin waxes

cher et aL» Brennstoff-Chemie 19, 226-30 (1938); , 20, 247-50 (1939); cf. also Briu 468,434).

_ ι molecular weight straight chain alcohols and other ^Jslssn-cootaining organic compounds have also been oo-

isj""*~ hydrogénation of carbon monoxide in the pres-*"~~ '^suspended in paraffin

the Field of Fis-fol. II, 1948, tr? ir^ung the folk '~~* -106.8' *

•Ses

heating films of polymer of about 100-300 microns m thickness to the fusion temperature. The melting point is taken as the temperature at which there is disappearance of double refraction.

The examples which follow are submitted to illustrate and not to limit this invention.

Example 1.—Eighty-nine parts of benzene, 0.425 part of 2,2*-azobis-2,4-dimethylvaleronitrile, and 78 parts of ethylene are charged into a pressure vessel capable of withstanding internal pressures of at least 1000 atm. One end of the vessel is fitted with a needle valve for admitting compressed ethylene, for example, at 1000 atm., and the other end is fitted with a removable closure which makes

- -Λ '?* , Jgn l ***' when subjected to o-^nt/ynal pressure of sev-

4 5

50

Bombshell Drops in Polyethylene Du Pont gets composition of matter patent on linear poly­ethylene, will offer licenses to low pressure process producers

1 m s WEEK, polyethylene executives are wondering what to do about Du Pont. While a few knew it was com­ing, many of the industry's top brass are still confused over the spanner tossed into the works by Du Pont's an­

nouncement that it has a composition of matter patent (U. S. Patent No. 2,816,883) covering linear polyethyl­ene, "no matter how it is manufac­tured" (C&EN, Dec. 23, page 15) .

The result could be that every

domestic producer may end up having to get a Du Pont manufacturing license. Company officials say that Du Pont will offer such licenses. In fact, it has al­ready started discussions. The poten­tial list includes Phillips, Celanese,

DEC. 3 0, 1957 C & E N 1 7

Legal Upheaval in

Polyethylene

Μ α ν erupt

O v e r TSias

**K^kfUi • JES B l l <

Grace, and Hercules, already in pro­duction; Carbide and Koppers, soon to be on stream; plus Dow, which is due later. In addition, several other com­panies are in various development stages, and Allied makes polyethylene pipe resin by a low pressure process.

Du Pont says it hasn't decided on license price, and won't until final ne­gotiations are over. To date, the firm has not issued licenses on linear poly­ethylene to any other company.

The question ye t to be answered is just how broad the patent will prove to be. A solution probably won't come without some complicated legal moves. Obviously, D u Pon t thinks it's broad enough in specifying polymer molecule physical propert ies. Polychemicals Department general manager, Robert L. Hershey, notes that D u Pont has spent more than $6 million on the spe­cific research objective of linear polv-ethylene since the middle 1930'"

Most producers have adopted a wait and see—and s tudy the patent—attitude. As a Hercules spokesman notes, "The patent problems in this field, are so complex, it will take a substantial period of time to determine what problems exist."

• Phillips Ques t ions Validity. Phil­lips, on the other hand, does not believe its position is severely threatened. A corporate spokesman gives the manage­ment view as follows: "The Du Pont patent does not interfere with nor af­fect Phillips' low pressure process uti­lizing a Phillips catalyst. The Du Pont patent is based on the old high pressure process which is entirely different from the Phillips process. The Du Pont pat­ent has polyethylene product claims which contain a number of limitations. As it is doubtful that these claims cover Phillips polyethylene or that they are valid and sustainable, it is believed that Phillips and its licensees will not be ad­versely affected."

However, to show that even in this quarter there still is some doubt, h e adds that, "In the event that this pat­ent should b e determined to be valid and infringed, the effect on the produc­tion cost of Phillips polyethylene would b e minor and its selling price would not be increased."

Phillips could be in a particularly vulnerable position as a licensor of many companies now operating plants. Several of these licensees feel tha t Phillips has the problem in its lap, and are referring all questions there. Ε. Ε .

Winne, vice president of Grace's Poly­mer Chemical Division, notes, "If there is any patent problem involved here , our license agreement with Phillips p ro ­vides that it is their responsibility to take care of it . . . I n the meantime, we are continuing to produce. . . . "

In Europe, Karl Ziegler says he was aware of the D u Pont pa tent situation, but that it does \ot affect his licensees. Du Pont, itself, is a Ziegler licensee. And Ziegler licenses held by others p ro­vided protection against the eventuality that Du Pont might get a composition of matter patent, Ziegler says. If Ziegler licensees want to deal directly with D u Pont, it's up to them, says Ziegler. He adds, however, that there is no reason for any Ziegler licensee to be disturbed. It may be worth men­tioning that composition of matter pa t ­ents don't exist in Germany—only proc­ess patents.

No one can say just what the even­tual outcome will be. D u Pont now has a group of ethylene polymerization pa t ­ents resulting from research by Arthur W. Larchar, Donald C. Pease, and Mil­ton J. Roedel. These applications w e r e filed during the years 1947 to 1951 .

Actually, issuance of the patent ends some lengthy litigation. This includes several appeals to Patent Office t r ibu­nals and an appeal filed by Du Pont in the U. S. District Court (District of Columbia) . This last appeal was dis­missed by stipulation. But all the for­mer legal activity may prove only a small forerunner of things to ~ome in this complex legal picture.

• Du Pont's View. Here are D u Pont's thoughts on the subject, as ex­pressed by a company spokesman: "Our composition of matter claims, which are free of any process limita­tion, define linear polyethylene in terms of its chemical structure and several typical physical properties. The physi­cal properties which the claims specify are the physical properties of l inear polyethylene. Under U. S. law, p rod­ucts are patentable as novel composi­tions of matter, and separate patents which in effect are dominated by the product patent may issue on individual processes for making the patented prod­uct. D u Pont, during the 1940*5, de­veloped low pressure and high pres­sure processes for making linear poly­ethylene. Other low pressure processes have since heen developed at other re­search installations, but so long as t he product which is formed meets the terms of the product claim, it is domi­

nated by the composition of mat ter patent ."

Du Pout's patent , in the first claim, describes an "exceptionally stiff*' poly­ethylene with an amorphous content of not more than 1 0 % . I t contains less than one side chain per 200 carbon atoms in the main chain, as determined by infrared absorption analysis. Melt­ing point is above 127° C. Tensile strength, based on original dimensions, is between about 2900 and about 1 1 , -800 p.s.i. Relative viscosity is above 1.0 and u p to about 1.5, measured a t 0 .125% concentration in xylene a t 85° C. Specific gravity (annealed) is in the range of 0.95 to 0.97.

T h e second claim in the D u Pont pa tent gives the same properties de ­scribed in the first claim, with two ex­ceptions. I t does not give tensile strength. And it puts relative viscosity between 1.127 and about 1.5, measured at 0 .125% concentration in xylene a t 85° C.

These, then, are the composition of matter claims upon which Du Pont takes its s tand. Fur ther illumination of Du Pont 's views turns u p in a descrip­tion (I&EC, July 1957, page 1071) of some of the company's research in this area: ". . . i s shown a comparison of a typical sample of linear polyethylene prepared in the laboratories of the D u Pont Co. at 7000 atm., with a sample of linear polyethylene prepared in t h e same laboratories at atmospheric pres­sure under conditions described b y Ziegler. These linear polyethylenes are compared with typical, commercial, Fawcett- type branched polyethylene.

"The two linear polyethylenes have approximately t he same weight-average molecular weight . . . They are com­parable in all physical properties, al­though the lower melt-index value for the Ziegler-type product may indicate a somewhat different molecular weight distribution. It is obvious that the two linear polyethylenes are essentially identical in these properties and con­trast sharply with the branched poly­ethylene.'*

The D u Pont patent has four process claims, bu t these are apparendy aca­demic. In any case, they mention proc­ess pressures between 5000 and 20,000 atmospheres. D u Pont will use a low-pressure process in the linear poly­ethylene plant it plans to build at La ­place, La., and D u Pont of Canada will soon be building a low pressure process plant at Sarnia, Ont., for linear poly­ethylene.

1 8 C & E N D E C . 3 0, 1957