PURPOSE: To obtain a film useful for tracing or the like at a specified haze value having numerous convexes on the surface thereof without use of special device at a low cost by crystalizing and drawing a polyester film containing an ethylenetelephthalate unit.
CONSTITUTION: A crystalizing polyester having at least 70mol% of ethylenetelephthalate in repetitive unit is extruded from T die to obtain a non-oriented amorphous film. Then, the film thus obtained is crystalized with a heating oven or the like so as to reach 0.5W5.0μ in the diameter of spherical crystal and then, is stretched more than 1.5 times at least in one direction at the temperature of above the glass transition temperature of the film but not exceeding 140°C. In the manner, the intended film can be obtained which covers 20 or more per 1mm of convexes over 0.2μ high in any direction on the surface thereof with a haze value exceeding 10%.
TANAKA HIROSHI
NAGANO HIKOICHI
| JPS5197677A | 1976-08-27 | |||
| JPS5473877A | 1979-06-13 | |||
| JPS5766936A | 1982-04-23 | |||
| JPS57167216A | 1982-10-15 |