Patent ID: 6287667
Filing Date: 2001-09-11
Classification: H01G,Y10S,Y10T

Abstract:
A biaxially oriented polyester film for capacitor, which polyester film comprises a polyester having structural repeating units constituted from polyethylene terephthalate units of 80 mol % or more in the structural repeating units, has at least one coating layer of a thickness of 0.005 .mu.m to 0.5 .mu.m on the polyester film comprising water soluble or water dispersible resin, has a total thickness of 1.0 to 21 .mu.m, and has a heat shrinkage stress satisfying the following formulae (1) to (3):S.sub.150 <200 g/mm.sup.2S.sub.150 -S.sub.120 <100 g/mm.sup.2S.sub.max <500 g/mm.sup.2where S.sub.150 and S.sub.120 represent the values of heat shrinkage stress per unit cross section area of the film at 150.degree. C. and 120.degree. C., respectively, and S.sub.max represents the maximum value of the heat shrinkage stress at the temperature within a range of not less than 150.degree. C. and not more than the melting point of the film.