PURPOSE: To obtain the titled film which is significantly excellent in easily cuttable properties, also excellent in a heat resistance and a waterproofness, etc., by biaxially stretching the polyester which contains the specified amount of a trifunctional phosphorus compound, trifunctional boron compound as a copolymerization component.
CONSTITUTION: A polyester is obtained by adding 0.02W5mol% of (A) a trifunctional phosphorus compound (a trimethyl phosphate, etc. is suitable,) or (B) a trifunctional boron compound (a dimethyl borate, etc. is suitable,) as a copolymerization component suitably in the period from the prepolymer stage in which a product is obtained by an esterification reaction to the oligomer stage of an initial polymerization time. After the obtained polyester film is biaxially stretched usually by the stretch ratio of 2W5 times, it is heat treated suitably at 200W240°C, thereby obtaining the purpose film which has a Charpy impact value of less than 1.5kg.cm/mm2.
EFFECT: An ink printability is excellent.
OOTAKI TOSHIHIRO
KANAI KICHIJIROU
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