Patent ID: 7803900
Filing Date: 2010-09-28
Classification: B29C,B29L,C08J,G02B,Y10T

Abstract:
1. A method for producing a thermoplastic resin film, comprising a step of: heat treating an unstretched thermoplastic resin film not having undergone stretching treatment in a stretching step, at a glass transition temperature of the thermoplastic resin Tg° C. or higher and (Tg+50)° C. or lower for 10 seconds or longer and 600 seconds or shorter while conveying the thermoplastic resin film at a low tension of 2 N/cm whereby an occurrence of an in-plane retardation (Re) and a retardation in the thickness direction (Rth) in the thermoplastic resin film is prevented by this step, and the thermoplastic resin film after the heat treatment has |Re| of 0 to 10 nm and |Rth| of 0 to 20 nm.