Patent ID: 6136420
Filing Date: 2000-10-24
Classification: B32B,Y10S,Y10T

Abstract:
A laminated polyester film which contains not more than 0.05% by weight of a fluorescent whitening agent and comprises:a fine cell-containing polyester film comprising 55 to 95% by weight of polyester which has an intrinsic viscosity in the range of 0.45 to 1.0 when measured after being shaped into a film, and 5 to 45% by weight of an immiscible thermoplastic resin, said fine cell-containing polyester film having a density of 0.40 to 1.30 g/cm.sup.3 ; andat least one other polyester film laminated as an outermost layer on at least one surface of said fine cell-containing polyester film,said other polyester film having a density of not less than 0.40 g/cm.sup.3,said other polyester film containing not less than 0.01% by weight of a fluorescent whitening agent, andthe concentration of the fluorescent whitening agent in said other polyester film being higher than that in said fine cell-containing polyesterwherein the ratio of thickness of said fine cell-containing polyester film to the thickness of said other polyester film is represented by the formul a10.ltoreq.T.sub.A /T.sub.B .ltoreq.500where T.sub.A represents a thickness of the fine cell-containing polyester film and T.sub.B represents a total thickness of said other polyester film.