Patent ID: 6517762
Filing Date: 2003-02-11
Classification: B29C,B29K,G11B,Y10T

Abstract:
A method for producing a polyester film, in which a film made of a resin mainly composed of polyester chains is stretched by a simultaneously biaxially stretching tenter oven, comprising consecutively performing the step of effecting small-ratio stretching at a film area stretching ratio of 1.0005 to 2.0 times three times or more to disentangle the polyester chains and ease the microstructure of the film so that the total area stretching ratio of the film is enhanced such that a polymer film having a high Young's modulus and small heat shrinkage is obtained, to achieve a total area stretching ratio of 25 to 150 times, wherein the high Young's modulus is 8 to 30 Gpa and the heat shrinkage is 2% or less.