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:
Jan. 09, 1990
Filed:
Dec. 21, 1988
Kazuyoshi Shigematsu, Sodegaura, JP;
Takashi Nakagawa, Sodegaura, JP;
Shuji Sakamoto, Sodegaura, JP;
Idemitsu Kosan Co., Ltd., Tokyo, JP;
Abstract
A polycarbonate polymer containing repeating units represented by the following general formula ##STR1## wherein: X is selected from single bond, ##STR2## wherein: R.sup.1 and R.sup.2 are each independently selected from hydrogen atom; alkyl radical of 1 to 6 carbon atoms; cycloalkyl radical of 5 to 6 carbon atoms; ##STR3## wherein p is an integer having a value of from 0 to 3; phenyl radicals substituted at para position by a substituent selected from alkoxy radicals of 1 to 5 carbon atoms, phenoxy radicals, or halogen radicals; or p-biphenylyl radical, --CH.sub.2).sub.q wherein q is an integer having a value of from 2 to 10; or ##STR4## wherein r is an integer having a value of from 4 to 8, and having a reduced viscosity [.eta.sp/c] of at least 0.2 dl/g as measured in methylene chloride at a concentration of 0.5 g/dl at 20.degree. C. Such polycarbonates exhibit excellent optical properties such as high birefringence, and are useful as materials for optical devices. Also, a process for preparing the polycarbonates and novel dihydric phenols which can be used as materials for the polycarbonates are disclosed.