John A Kreuz, Richard F Sutton Jr: Copolyimide film with improved properties. E I Du Pont de Nemours and Company, November 24, 1992: US05166308 (26 worldwide citation)

Disclosed is an aromatic copolyimide film prepared by chemical conversion of a copolyamide acid solution obtained by copolymerization of an aromatic tetracarboxylic acid component comprising from 30 to 50 mole % of biphenyltetracarboxylic acid dianhydride, 50 to 70 mole % of pyromellitic acid dianhy ...

Richard F Sutton Jr: Polyimide manufacture. E I Du Pont de Nemours and Company, November 9, 1982: US04358581 (17 worldwide citation)

A process is disclosed for manufacturing high molecular weight polyimide from a chilled solution which includes a polyamide acid prepolymer, a finishing component, and a converting system wherein, when the solution is heated, polyamide acid polymer is formed and converted to polyimide.

John A Kreuz, Richard F Sutton Jr, Stuart N Milligan: Tetrapolyimide film containing benzophenone tetracarboxylic dianhydride. E I du Pont de Nemours and Company, March 23, 1993: US05196500 (16 worldwide citation)

Tetrapolyimide films derived from 3,3',4,4'-benzophenone tetracarboxylic dianhydride, pyromellitic acid dianhydride, p-phenylene diamine and 4,4'-diaminodiphenyl ether, and their preparation, are described. The tetrapolymer films have low water absorption, low coefficients of thermal and hygroscopic ...

Richard F Sutton Jr: Process for preparing polyimides. E I Du Pont de Nemours and Company, May 3, 1988: US04742153 (15 worldwide citation)

An improved process for preparing polyimides is disclosed which involves end capping intermediate polyamic acids with dicarboxylic acid monoanhydrides and thermally converting to high molecular weight polyimides.

Richard F Sutton Jr: Polyimide molecular weight enhancement by solvent extraction. E I Du Pont De Nemours and Company, Paul R Steyermark, March 6, 1990: US04906731 (1 worldwide citation)

Extraction of polyamic acid-polyimide gel in bipolymerized polyimide manufacturing process with a solvent containing an extraction-enhancing agent, which is a pyridine, picoline, or quinoline, leads to a polyimide film having increased molecular weight. Polyimides are valuable materials used in fabr ...