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. 14, 1989
Filed:
May. 09, 1988
Kazunari Otsubo, Ichihara, JP;
Motonobu Ezoe, Ichihara, JP;
Hideo Ago, Ichihara, JP;
Koji Yamamoto, Ichihara, JP;
Idemitsu Petrochemical Co., Ltd., Tokyo, JP;
Abstract
Polycarbonate for production of disc substrates, a process for efficiently producing said polycarbonate, and a disc substrate made of said polycarbonate are disclosed. This polycarbonate has a low molecular weight polymer content of not more than 3% by weight, an unreacted bisphenol content of not more than 20 ppm, and a methylene chloride content of not more than 20 ppm, and can be obtained by extracting impurity-containing powdery polycarbonate with an organic solvent such as acetone and methyl ethyl ketone. This polycarbonate is particularly suitable for production of high quality disc substrates.