BIAXIALLY STRETCHED POLYESTER FILM AND ITS MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a biaxially stretched polyester film capable of being subjected to heating sterilizing or particularly steam sterilizing (retort sterilizing) and having excellent adhesive properties to a metal layer. SOLUTION: The biaxially stretched polyester film can heating sterilize and has good adhesive properties to the metal. The polyester film comprises a base layer B made of a thermoplastic polyester, and at least one adhesive layer containing a component I and a component II. The component I contains a polyester copolymer having four types of monomer units of (a) an isophthalic acid unit, (b) an aliphatic dicarboxylic acid unit, (c) a sulfomonomer unit and (d) a glycol unit. The component II contains (e) an acrylic and/or methacrylic monomer unit, and (f) an acrylic copolymer containing a copolymerizable monomer unit and for bringing about an internal crosslinking by heating a copolymerizable monomer unit.