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:
Nov. 09, 1993
Filed:
Jul. 09, 1990
Masumi Saruwatari, Nagoya, JP;
Yasuhiko Ohta, Nagoya, JP;
Yasuhiro Fujii, Nagoya, JP;
Yasuko Honji, Ichinomiya, JP;
Shoichi Tsuji, Tanashi, JP;
Shinobu Moriya, Nagoya, JP;
Mitsui Toatsu Chemicals, Incorporated, Tokyo, JP;
Abstract
A polyimide film essentially consisting of polyimide having recurring units of the formula (I): ##STR1## which has a density of 1.335 to 1.390 g/cm.sup.3 at 23.degree. C. and/or a refractive index of 1.605 to 1.680 at 23.degree. C. in the direction of thickness and is transparent; and a preparation process of the polyimide film by extruding the polyimide having recurring units of the above formula (I) through a common melt-extrusion process, casting in a chill-roller to obtain an unstretched film, uniaxially or biaxially stretching the unstretched film to cause molecular orientation, and successively setting the stretched film through heat-treatment.