Polycarbonate for making extruded films that are virtually free of surface defects

US8084570B2 · kind B2 · utility

Assignee

• Bayer MaterialScience AG · DE

Inventors

• Heinz Pudleiner · Krefeld, DE
• Wolfgang Ebert · Krefeld, DE
• Alexander Meyer · Mülheim an der Ruhr, DE
• Klaus Meyer · Dormagen, DE
• Alexander Karbach · Krefeld, DE
• Franky Bruynseels · Sint-Gillis-Waas, BE

Key dates

• Filing date: Oct 25, 2007
• Grant date: Dec 27, 2011
• Expiry date: Jan 20, 2030

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08J2369/00
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Linear polycarbonate resin virtually free of surface defects that impair the suitability of the resin for demanding optical application is disclosed. Also disclosed is a process for the manufacture of the resin. The surface defects included in the resin are in the form of transparent fluorescing particles, the particle count of which portion that are 15 and 250 μm in size, is up to 1.8 counts/g, said count being determined by exciting the residue remaining after filtering a solution of said polycarbonate in methylene chloride through a Teflon filter of 5 μm pore size at a wavelength of 400-440 nm, 25× overall magnification and illumination time of 40 millisec. The polycarbonate is suitable for making films of improved optical properties.