| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyester resin composition excellent in the capability of direct high-speed extrusion lamination on a metallic sheet and in other properties, wherein the polyester consists mainly of ethylene terephthalate containing a specified amount of a compound having a specified number of ester-bond- forming functional groups and has a specified melting point and a specified die swell. SOLUTION: The polyester is based on ethylene terephthalate containing 0.1-2.0 mol% compound having 3 or 4 ester-bond-forming functional groups and has a melting point of at least 220 deg.C and a die swell SD of at least 1.3, wherein SD=Dp/Dc and is measured at a temperature equal to the melting point +40 deg.C, wherein Dp is the diameter of the polymer extruded from a capillary, and Dc is the diameter of the capillary. The extrusion shear rate from the capillary is 121.6/sec. It is desirable that the polyester has a content of bishydroxyethyl terephthalate(BHET) of at most 60 ppm and a content of a dimer of BHET of at most 300 ppm. The polyester is excellent also in heat resistance, ductility, flavor retention, etc.
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