C H E M I C A L S

PMDA Attracts New Producers Hopes for pyromellitic dianhydride based on interest in high-temperature-resistant polyimide resins

Although Du Pont has stopped offer­ing pyromellitic dianhydride to cus­tomers, other companies are becom­ing interested in making it. Hexagon Laboratories now offers commercial quantities, and by the end of the year Princeton Chemical Research should have its PMDA plant in operation.

The new entrants into PMDA pro­duction are entering a small market, but one they think has excellent growth possibilities because of the in­terest in high-temperature-resistant polyimide resins (C&EN, Aug. 24, page 24) . Polyimide resin consump­tion currently is probably under 250,-000 lb. per year, but could grow into a 25 million lb. market in 10 years.

PMDA's growth seems pretty well geared to the polyimide resins. Some is also used as a curing agent for epoxy resins. PMDA esters are excel­lent plasticizers, but in the cutthroat plasticizer business, where a sale may depend on a price a fraction of a cent

Among PMDA's competitors for some applications are:

TRIMELLITIC ANHYDRIDE (TMA) Made by Amoco

DURENE (from C-10 aromatic streams in petroleum refineries) Made by En jay and Sinclair

can be oxidized t o . . .

per pound lower than that of a com­petitor, an expensive plasticizer does not seem to have great potential. The new plasticizer would need some very special advantages, probably for small-volume application. However, the PMDA molecule is an interesting one and other uses for it, as well as for pyromellitic acid, which Hexagon now makes, may develop as the price comes down.

For polyimide and related resins PMDA has some competitors. Co­polymer Rubber & Chemical Corp. of­fers an aliphatic compound, 1,2,3,4-cyclopentanetetracarboxylic acid and the corresponding dianhydride. Gulf Oil offers the dianhydride of 3,3',4,4'-benzophenone tetracarboxylic acid. Amoco's trimellitic anhydride, used in making polyimide-polyamide resins, also competes in some applications.

Small Market. The market for PMDA today is undoubtedly very small, but it could grow to 400,000 lb. in six months. At present prices of about $5.00 per pound, PMDA is likely to remain a small-volume, spe­cialty item. But if producers can im­prove their manufacturing processes

PYROMELLITIC ACID Made by Hexagon

and develop bigger markets, the price will undoubtedly come down. Pro­ducers feel the price may eventually be about $1.00 or even 50 cents per pound.

Because it felt it had failed to de­velop a large enough market to make a continued effort worthwhile, Du Pont has stopped offering PMDA. It first brought PMDA on the market in 1960, and by 1961 decided to discon­tinue offering the material to its cus­tomers. However, because of cus­tomer protests it reversed itself and decided to continue to sell PMDA. But by 1963 the company decided that it would stop offering PMDA, and today supplies only a few cus­tomers who have uncompleted proj­ects based on PMDA. It does con­tinue to make PMDA for captive use.

The two newcomers to the PMDA business have relatively modest pro­duction facilities. Hexagon Labora­tories can probably produce about 150,000 lb. per year. When Prince­ton Chemical Research's new plant is ready about the end of the year it should be able to produce about 400,-000 lb. per year.

52 C&EN OCT. 5, 1964

PYROMELLITIC DIANHYDRIDE (PMDA) Made by Hexagon, Du Pont, and Princeton Chemical Research

1,2:3,4—CYCLOPENTANETETRACARBOXYLIC

ACID, DIANHYDRIDE (CPDA)

Made by Copolymer Rubber & Chemical

3,4:3',4'-BENZ0PHEN0NE TETRACARBOXYLIC ACID,

DIANHYDRIDE (BTDA) Made by Gulf Oil

GOOD READING-Neville's New Unichlor Brochure.. Formulators of vinyl plastisols, paints, printing inks, flame-retardant compounds, adhesives, metal-cutting oils, rubber products and caulking compounds will find much of interest in Neville's new technical booklet describing its Unichlor brand of chlorinated paraffins. The booklet outlines typical properties and physical

Neville Products

Resins — Coumarone-lndene, Hydrocarbon— Thermoplastic and Heat Reactive, Hydroxy • Oils — Plasticizing, Rubber Reclaiming, Shingle Stain • Solvents • Antioxidants—Non-Staining Rubber • High Purity Indene • Indene Chemicals • Paving Materials • Chlorinated Paraffins Ortho and Para Dichlorobenzenes.

characteristics of the various grades of Unichlor and describes their many applications with ample illustra­tions. Also contained in the text are a large number of sample formulations. For your copy of this new Unichlor booklet, write without obligation to: Chlorinated Prod­ucts Division, Neville Chemical Co., Pittsburgh, Pa. 15225.

NEVILLE CHEMICAL CO. PITTSBURGH, PENNSYLVANIA • 15225 ANAHEIM AND SANTA FE SPRINGS, CALIF.; UITHOORN, HOLLAND

We were here when the techniques of splitting and distilling fatty acids were first introduced to the United States, and have been manufacturing fatty acids for industry ever since. Through the years we've set the standards for pro­duction and quali ty. . . served practically every major user—you, perhaps. And we look forward to being around in the future: working with you on product development and improvement; making raw material surveys; advising on FDA regulations, storage and ma­terials handling. Call any time. Write today for a copy of our "Fatty Acids in Modem Industry."

54 C&EN OCT. 5, 1964

295 Madison Ave., N. Y. 17. Ν. Υ. MANUFACTURERS SINCE 1837

If, as they hope, PMDA sales vol­ume rises, both would consider putting up entirely new plants at new sites to take care of the market. Both pro­ducers are subject to competition from other companies which may enter the business, even at present levels. If the outlook is such that volume prom­ises to be very large, some of the pe­troleum companies who produce, or could produce, the raw material, du-rene, might enter the business. Both of the present suppliers of durene, Enjay Chemical and Sinclair Oil, have done development work on the oxidation of durene. Their chief in­terest is in selling durene, but either one might well move into PMDA if the market grew large enough.

Oxidize Durene. The technology of making PMDA is not simple. It is made by oxidizing durene (tetra-methyl benzene). Oxidizing the first methyl group is easy, but it becomes increasingly difficult to oxidize the succeeding groups, especially the fourth one. This means that yields are low, and that the PMDA that is finally produced must be separated from a large amount of various other compounds. Getting a high-purity product is a major problem.

Du Pont uses a liquid-phase oxida­tion process, with nitric acid as the oxidizing agent. Hexagon Laborato­ries uses a "wet" process different from Du Pont's. Princeton Chemical Research, on the other hand, has de­veloped a vapor-phase oxidation process. PCR, as well as some of the petroleum companies, feels that for large-scale production, the vapor-phase process will be the most eco­nomical route.

While he does not exclude the va­por-phase process for really large-scale production, Murray K. Près ter, president of Hexagon Laboratories, believes that his company's process is basically a good one and that it can continue to be improved. At present Hexagon uses equipment which is also used for other processes in the com­pany's flexible plant. Converting the process to continuous operation would increase efficiency and make a price reduction possible.

If the PMDA market grew consid­erably larger and increased the vol­ume of durene required to justify, say, a 10 million lb.-per-year plant, the price of durene could be dropped from its present 60 cent-per-pound level to the neighborhood of 25 cents, and the price of PMDA lowered.

G r o c o f a t t y a c i d s a r e b a c k e d by m o r e t h a n a c e n t u r y o f e x p e r i e n c e

we ve been

around

BRIEFS

Four dicyclo chemicals are now of­fered by Velsicol Chemical Corp., Chicago, 111. They are hexachlorocy-clopentadiene (an intermediate for use in synthesizing germicides, pesti­cides, and pharmaceuticals), chloren-dic anhydride (a difunctional acid an­hydride for fire-retardant paints or plastic films), dicyclopentadiene (for use in resins and insecticides), and dicyclopentadiene dioxide (a cross-linking agent for epoxy resin formula­tions and an intermediate in the syn­thesis of cyclic glycols). C30

Two styrene-acrylonitrile molding and extrusion compounds are offered by Union Carbide's Plastics Division, New York, N.Y. These are a general-

purpose compound, RMDA-4400 (crystal 07) , and a high-flow com­pound, RMDA-4420 (crystal 07) . Neither compound requires much color correction, because they are al­most colorless. C31

Diphenyl sulfone and sodium hydroxy-acetate are available from Fallek Products Co., New York, N.Y. Di­phenyl sulfone is used in chemical syn­theses. Sodium hydroxy acetate can be used in nickel plating. C 32

Further information on keyed | Chemical items is readily I available . . .

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