Polyethylene terephthalate resin film roll and method for producing the same

摘要

PPROBLEM TO BE SOLVED: To provide a polyethylene terephthalate resin film roll which has good film transparency in a heat treatment process during post-processing over the whole length of the roll irrespective of the conditions of the post-processing and high practicability. PSOLUTION: In the polyethylene terephthalate resin film roll, the difference nSBab/SBbetween the refractive index in the angle direction at 45 in the winding direction and the refractive index in the angle direction perpendicular to the winding direction is 0.015-0.060, the thermal shrinkage rate HS180 in the longitudinal direction at 180C for 30 min is 0.7-1.5%, and a difference (difference in thermal shrinkage) in HS180 in the width direction is 0.15% or below. A method for producing the film roll is also disclosed. PCOPYRIGHT: (C)2009,JPO&INPIT