US Patent 7993562 Method of producing a thermoplastic film

A method for producing a thermoplastic film, comprising cooling and solidifying a filmy thermoplastic melt resin, by holding it between a metallic presser and a metallic casting roll for cooling; wherein the temperature of the filmy thermoplastic resin just before being held between the metallic presser and the casting roll for cooling is from Tg+20° C. to Tg+90° C. and a difference between a surface temperature (Tt) of the metallic presser and a surface temperature (T1) of the casting roll for cooling satisfies the formula (1) and a contact length Q satisfies the following formula (2)0.5° C.≦T1−Tt≦20° C.  (1)0.1 cm≦Q≦8 cm  (2)