# US 5,350,790 A · Polycarbonate resin composition for optical use > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,350,790 A - Document ID: US5350790A - Status: Granted - Kind: A - Application number: 08/041,189 - Filed: 1993-04-01 - Granted: 1994-09-27 - Earliest claimed: 1990-06-08 - Assignees: Mitsubishi Kasei Corporation - Inventors: Yoshitomi Urabe; Hironori Hayashida; Yoshiaki Ohtani - Web page: https://patentgrep.com/patent/US5350790A ## CPC - G11B 7/253: of substrates - C08K 5/09: Carboxylic acids; Metal salts thereof; Anhydrides thereof - G11B 7/2534: polycarbonates [PC] - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) ## Abstract This invention provides a polycarbonate resin composition for optical use and an optical disc substrate manufactured therefrom. Polycarbonate resin is mixed with at least one kind of carboxylic acid selected from aliphatic carboxylic acids having 1 to 10 carbon atoms in which hydrogen atoms of aliphatic group may be substituted by hydroxyl groups; or aromatic carboxylic acids in which hydrogen atoms of the aromatic ring may be substituted by low alkyl groups, hydroxyl groups, or halogen atoms. The amount of the carboxylic acids is 5 to 1000 ppm based on the polycarbonate resin. ## Claims ### Claim 1 A transparent polycarbonate resin composition for optical use comprising a polycarbonate resin and at least one aromatic carboxylic acid in which hydrocarbon atoms of the aromatic ring may be substituted by lower alkyl groups, hydroxyl groups, or halogen atoms, the amount of which is 5 to 1000 ppm based on the polycarbonate resin. ### Claim 2 (depends on 1) A transparent polycarbonate resin composition for optical use, as claimed in claim 1, where the aromatic carboxylic acid is a bivalent or trivalent carboxylic acid. ### Claim 3 (depends on 1) A transparent polycarbonate resin composition for optical use, as claimed in claim 1, where the aromatic carboxylic acid has its carboxylic group substituted to an aromatic benzene ring. ### Claim 4 (depends on 2) A transparent polycarbonate resin composition for optical use, as claimed in claim 2, where the aromatic carboxylic acid is trimellitic acid. ### Claim 5 (depends on 1) A transparent polycarbonate resin composition for optical use, as claimed in claim 1, where the amount of the aromatic carboxylic acid is 10 to 800 ppm based on the polycarbonate resin. ### Claim 6 (depends on 1) A transparent polycarbonate resin composition for optical use, as claimed in claim 1, where the polycarbonate resin is manufactured using 2,2-bis (4-hydroxyphenyl) propane as a monomer constituent. ### Claim 7 (depends on 1) A transparent polycarbonate resin composition for optical use, as claimed in claim 1, where the viscosity average molecular weight of the polycarbonate resin is 12,000 to 20,000. ### Claim 8 (depends on 1) A transparent polycarbonate resin composition for optical use, as claimed in claim 1, where the viscosity average molecular weight of the polycarbonate resin is 13,000, to 18,000. ### Claim 9 (depends on 1) A transparent optical disc substrate made of the polycarbonate resin composition as claimed in claim 1. ### Claim 10 (depends on 9) A transparent optical disc substrate, as claimed in claim 9, obtained by the injection molding process. ### Claim 11 (depends on 9) A transparent optical disc substrate, as claimed in claim 9, where the number of point defects having the diameter of 20 microns or more which developed in the substrate is less than one, when the substrate was retained at a temperature of 88.degree. C. and humidity of 88% for 500 hours. ### Claim 12 (depends on 1) A transparent polycarbonate resin composition for optical use, as claimed in claim 1, where the aromatic carboxylic acid is selected from the group consisting of benzoic, hydroxybenzoic, bromobenzoic, methylbenzoic, phthalic, terephthalic, isophthalic, trimellitic, trimesic, naphthoic and naphthalenedicarboxylic acids. ### Claim 13 (depends on 1) A transparent polycarbonate resin composition for optical use, as claimed in claim 1, wherein the aromatic carboxylic acid is terephthalic acid. ### Claim 14 (depends on 1) A transparent polycarbonate resin composition for optical use, as claimed in claim 1, where the aromatic carboxylic acid is isophthalic acid. ### Claim 15 (depends on 1) A transparent polycarbonate resin composition for optical use, as claimed in claim 1, where the aromatic carboxylic acid is trimesic acid.