Patent ID: 8470223

Claim:
A method for manufacturing a thermoplastic resin film comprising: a film formation step for forming a film by extruding a molten thermoplastic resin from a die in the form of sheet and cooling and solidifying the resin sheet by sandwiching the resin sheet between a pair of rollers having a cooling roller and a press roller which is provided so as to be pressure contact with the cooling roller; and a drawing step for drawing a film of the thermoplastic resin uniaxially or biaxiall, wherein the thermoplastic resin film drawn in the drawing step has thickness variations in the width direction and length direction within the range of 10% or less by the pair of rollers satisfying the following formulas (1) to (3); (1) 0.0043X 2 +0.12X+1.1<Y<0.019X 2 +0.73X+24 where X (degrees C)=the glass transition temperature of the molten thermoplastic resin Tg (.degree. C.)−the temperature of the press roller, and Y (in/min) is film forming speed; (2) 0.05 mm≦Z≦7.0 min where Z is the wall thickness of a metal cylinder constituting an outer shell of the press roller; and (3) 3 kg/cm 2 <P/Q<50 kg/cm 2 where Q (cm) is the length of contact of the pair of the rollers via the sheet, and P (kg/cm) is line pressure for sandwiching the molten thermoplastic resin sheet between the pair of rollers.