Patent ID: 6368532
Filing Date: 2002-04-09
Classification: B29C,B29K,C08J

Abstract:
A method of producing a biaxially stretched polyester film by stretching a cast film sequentially first in the longitudinal direction and then in the lateral direction, which comprises stretching the longitudinally stretched cast film laterally at a temperature higher than the glass transition temperature of the polyester film from by 5Â° C. to by 50Â° C., staying the laterally stretched film in an intermediate zone for a period from 3 to 30 seconds which has been controlled at a temperature from higher than the lateral stretching temperature by 20Â° C. or more to lower than a heat setting temperature by 20Â° C. or less, and then heat-setting at the heat setting temperature which is lower than the melting point of the polyester film from by 30Â° C. to by 5Â° C. to form a biaxially stretched polyester film.