The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 01, 1976
Filed:
Aug. 01, 1973
Naoya Yoda, Otsu, JA;
Toshiya Yoshi-i, Otsu, JA;
Saburo Fujita, Otsu, JA;
Hiroshi Mochizuki, Otsu, JA;
Hirosuke Yumoto, Otsu, JA;
Masaru Kurihara, Otsu, JA;
Takashi Kubota, Otsu, JA;
Noriaki Dokoshi, Otsu, JA;
Chiaki Tanaka, Otsu, JA;
Toray Industries, Inc., Tokyo, JA;
Abstract
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.