| 摘要 |
PURPOSE: To enable good perforation plate making and to obtain a printing image of high quality excellent in substance stability with the elapse of time, in a biaxially stretched film specified in thickness composed of a thermoplastic polyester resin, by specifying the max. value of heat shrinkage stress or stress retentivity. CONSTITUTION: A thermal perforable film is formed from a biaxially stretched film with a thickness of 5-15μm composed of a thermoplastic polyester resin. The max. value of the heat shrinkage stress of the film is specified to 500-1000g/mm<2> at 70 deg.C and 300-800g/mm<2> at 140 deg.C and the stress retentivity thereof is specified to 0.10-0.40. The film may be constituted of a compsn. consisting of a substantially amorphous thermoplastic polyester resin and a crystalline thermoplastic polyester resin with a softening point of 150-200 deg.C. At this time, crystal melting energy measured by DSC (temp. rising speed; 10 deg.C/min according to JIS K7121) is specified to 10-20J/g and a melting temp. range is specified to 50-80 deg.C. |
