Toray Industries, Inc.

Toshiya Yoshi-i

Masaru Kurihara

Chiaki Tanaka

Takashi Kubota

Saburo Fujita

Naoya Yoda

Noriaki Dokoshi

Hiroshi Mochizuki

Hirosuke Yumoto

A process is provided for manufacturing heat resistant polymeric film. A concentrated polymer composition containing solvent is provided, which composition is a solid at room temperature. The composition comprises (a) a polymer having in the repeating units thereof a member selected from the group consisting of precursor units which on heat curing form heterocyclic rings, and a mixture of said precursor units and heterocyclic rings formed from said precursor units and (b) 25-130% by weight of an organic solvent for said polymer, the composition being a solid at room temperature. According to the process, the solid composition is heated to a temperature above room temperature and is extruded into film at this high temperature to form film at a temperature above room temperature and below the curing temperature of the polymer. The resulting film, prior to curing, is subjected to an extraction step using an extraction compound selected from the group consisting of water, aliphatic and aromatic hydrocarbons, hydrocarbon halide, ketones and hydroxyhydrocarbons, and such curing is achieved by maintaining contact for a time sufficient to extract some of the solvent from the film. The resulting film is thereafter cured with an effective amount of heat sufficient to cause ring closure of said precursor units, thereby forming the heat resistant polymeric film.

Process for the production of a shaped article of a heat resistant

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Otsu, Japan

Toshiya Yoshi-i