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:
Feb. 25, 1992
Filed:
Jan. 31, 1991
Toshinori Ishii, Okayama, JP;
Masanori Sato, Osaka, JP;
Kuraray Co., Ltd., Kurashiki, JP;
Abstract
A wholly aromatic polyester film, (A) which is made of a wholly aromatic polyester consisting essentially of the following recurring units I and II ##STR1## wherein the aromatic ring may be optionally substituted with at least one substituent selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom and a phenyl group, said wholly aromatic polyester comprising 10 to 90 mol % of the recurring unit I and 90 to 10 mol % of the recurring unit II, being capable of forming an optically anisotropic melt phase, and having a melt strength at a temperature 20.degree. C. higher than its transition temperature to liquid crystal of at least 2.0 g/mm.sup.2 ; (B) said film having an oxygen permeability of not more than 1.0 cc.20.mu./m.sup.2.day.atm at a temperature 20.degree. C. and a relative humidity 65%; and (C) said film having thermal shrinkages both in the machine direction and in a direction perpendicular thereto of not more than 1% at a temperature 250.degree. C. Said wholly aromatic polyester film can be produced by melt-extruding a wholly aromatic polyester to form into a film under conditions that a shear rate applied to the wholly aromatic polyester in a molten state at the exit of the molding die is not less than 500 sec.sup.-1.