E.i. Dupont De Nemours and Company

Clare A Stewart

Donna Lynn Visioli

David J Lowe

Albert L Moore

Isadore Swerlick

Robert C Di Luccio

Linda R Bateman

Joseph F Englert, Jr

Louis J Maurin, Iii

Roy Jackson

David P Beach-Coffin

Economic and efficient process for preparing an oligomer of poly(butylene terephthalate) or an oligomer of poly(butylene isophthalate) from a transesterification reaction mass by using a countercurrent column reactor system wherein the transesterification reaction mass is fed into the countercurrent column reactor and continuously flows downward while simultaneously a heated inert gas stream continuously flows upward to scrub out volatiles from the transesterification reaction mass, thereby yielding from the bottom of the countercurrent column reactor an oligomer of poly(butylene terephthalate) or an oligomer of poly(butylene isophthalate) suitable for use in a polycondensation reaction. Butanediol is recycled throughout the process through an absorber column.

Continuous process for preparing poly(butylene terephthalate) oligomer

Method of making tablets for active ingredient delivery by compressing a mixture of active ingredient and granular, high viscosity, fully hydrolyzed polyvinyl alcohol or copolymer of vinyl alcohol with methyl acrylate or methyl methacrylate. By use of a crystalline, heat treated polymer, a tablet providing quick active ingredient release is obtained. By using an amorphous, non-heat treated polymer a tablet providing prolonged active ingredient release is obtained. By using blends of crystalline and amorphous polymers, tablets having a range of active ingredient release characteristics can be obtained. The granular, high viscosity, fully hydrolyzed polymers provide flowability, compressibility and processing versatility advantages over conventional tablet binders.

Use of vinyl alcohol homopolymer and copolymers for tableting active

An improved process for the catalytic dehydrochlorination of 3,4-dichlorobutene-1 with aqueous alkali, wherein the effluent from the dehydrochlorination reactor is separated into phases, and the organic phase is steam-stripped at low temperature (below about 80.degree. C.) to recover chloroprene product, while the steam stripper heels are returned to the dehydrochlorination reactor. A small portion of the heels are purged prior to being recycled. Most of the catalyst is recovered and returned to the reaction, but a small amount of make-up catalyst is added. Chloroprene made in this process is a valuable monomer which finds use in the manufacture of a broad line of synthetic elastomers of considerable industrial interest.

Process for the manufacture of chloroprene

Terpolymer consisting of 12 to 48% by weight TFE units, 7 to 24% by weight HFP units and 30 to 81% by weight VF.sub.2 units, provided that when the content of TFE units is less than 42% by weight, the content of HFP units is less than 15% by weight. Heat-stable films such as polyimide film can be coated with a coating comprising the terpolymer to provide heat-sealable film useful as wire insulation.

Fluoropolymer hexafluoropropene, tetrafluorethene and 1,1-difluoroethene

An elastomeric fluoropolymer having improved low temperature properties is provided. The composition contains polymerized units of 57-61 weight % vinylidene fluoride, 27-31 weight % hexafluoropropene, and 10-14 weight % tetrafluoroethylene.

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Wilmington, DE, United States of America

Clare A Stewart