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:
Apr. 11, 2006
Filed:
Mar. 07, 2000
Tetsuya Tsunekawa, Otsu, JP;
Shozi Nakajima, Otsu, JP;
Yukari Nakamori, Shiga, JP;
Masaaki Kotoura, Otsu, JP;
Tetsuya Tsunekawa, Otsu, JP;
Shozi Nakajima, Otsu, JP;
Yukari Nakamori, Shiga, JP;
Masaaki Kotoura, Otsu, JP;
Toray Industries, Inc., Tokyo, JP;
Abstract
The present invention provides a polyester film particularly useful as a base film for a magnetic recording medium such as cassette-type magnetic tape of a digital recording mode and a production process thereof. The polyester film is produced by irradiating UV light onto a surface of a film in a non-stretched stage or a stage prior to the completion of stretching to form fine protrusions on the surface. The fine protrusions on the film surface are specified by the ratio of 10-point average roughness Rz to center line average roughness Ra (Rz/Ra) on the surface (less than 20), the difference in concentration of carboxyl groups between the surface layer part and the inside of the film, and the number of fine protrusions.