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:
Dec. 02, 2025
Filed:
Mar. 08, 2021
Unitika Ltd., Osaka, JP;
Hiroshi Ashihara, Kyoto, JP;
Takayoshi Okuzu, Tokyo, JP;
Ken Akamatsu, Kyoto, JP;
Akiko Kurosawa, Kyoto, JP;
Goro Araki, Kyoto, JP;
Akito Kajita, Kyoto, JP;
UNITIKA LTD., Osaka, JP;
Abstract
A polyester film includes a polyester (A) composed mainly of polybutylene terephthalate and a polyester (B) composed mainly of polyethylene terephthalate, wherein a mass ratio (A/B) between the polyesters (A) and (B) is 70/30 to 55/45, a dry heat shrinkage rate (B) through heat treatment at 200° C. for 15 minutes is 35% or less in any of four directions (0°, 45° 90° and 135°) on the film surface, a difference between a maximum value and a minimum value of these dry heat shrinkage rates is 5% or less, a thickness variation in the four directions is 10% or less, and a crystallization index shown in DSC measurement is 25 to 55 J/g.