PRODUCTION OF THERMOFORMED ARTICLE FROM POLYESTER TBERMOPLASTIC RESIN SHEET

摘要

PROBLEM TO BE SOLVED: To obtain a thermoformed article excellent in heat resistance and appearance such as a surface state or form from a polyester resin sheet. SOLUTION: A substantially unstretched polyester sheet is selectively preheated so that the part to be thermoformed is set to a temp. of 60-95 deg.C and the other part thereof is set to temp. lower than the temp. of 60-95 deg.C by 10 deg.C or higher and thermoformed within a thickness range satisfying the formula: 3<=t0 /t1 <=20 to form a thermoformed article and this article is heated to 130-270 deg.C to be heat-treated within a thickness range satisfying the formula: 0.5<=t1 /t2 <=2. In the formulae, t0 is the average thickness (mm) of the polyester resin sheet before thermoforming; t1 is the average thickness (mm) of the thermoformed article before heat treatment; and t2 is the average thickness (mm) of the thermoformed article after heat treatment.