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:
Sep. 15, 2026
Filed:
Sep. 30, 2022
Toyobo Co., Ltd., Osaka, JP;
TOYOBO CO., LTD., Osaka, JP;
Abstract
Provided is a biaxially oriented polyester film in which poor flatness that may be caused during heat processing is suppressed. In the biaxially oriented polyester film, the content rate of an ester constituting unit derived from an isophthalic acid component is 0.5-5.0 mol % with respect to 100 mol % of all ester constituting units, the amount of change in haze of the film is 5.0% or less, the intrinsic viscosity of constitutional polyester resins is 0.59-0.65 dl/g, the average value of storage moduli is 5.0-7.6×10[Pa], the acid value of the film is 40-60 eq/ton, and the relational expression is satisfied: X×(Ymax−Ymin)≤0.0591×(X×Ymin)+0.005, where X is the storage modulus at 170° C., and Y is the film thickness per 1000 mm in the transverse direction with Ymax as the maximum value and Ymin as the minimum value.