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:
Oct. 19, 2004
Filed:
Jul. 15, 2003
Kiyonari Hashizume, Yamaguchi, JP;
Nobuaki Kido, Yamaguchi, JP;
Shunichi Matsumura, Yamaguchi, JP;
Takeshi Sasaki, Yamaguchi, JP;
Other;
Abstract
The present invention relates to a hydrogenated styrene polymer that has excellent transparency, can be used suitably for an optical application such as an optical disk substrate, has stability and transparency in a hot and humid environment, and has excellent heat resistance; and a process for producing same; etc. The hydrogenated styrene polymer of the present invention has a hydrogenated polymerized styrene unit content of at least 70 wt %, a content of fine particulate foreign matter having a particle size of 0.2 &mgr;m or more and less than 0.5 &mgr;m of at most 1×10 per g of the hydrogenated styrene polymer, and a phosphorus atom content of at most 0.01 parts by weight in 100 parts by weight of the hydrogenated styrene polymer. Furthermore, the process for producing a hydrogenated styrene polymer of the present invention includes steps of filtering, with a filter having a pore size of 0.3 &mgr;m or less, a hydrogenated styrene polymer having a hydrogenated polymerized styrene unit content of at least 70 wt %, at a temperature at which the solution viscosity thereof is at most 10 Pa·sec (100 poise) at a shear rate of 1 (1/s), and then removing a solvent from the filtrate thus obtained.