PRODUCTION OF THERMOPLASTIC POLYESTER RESIN FOAMED SHEET

摘要

PROBLEM TO BE SOLVED: To make surface beautiful and to lower a degree of crystallization by holding the surface temp. of a foamed sheet to specific temp. or lower during the period immediately after extrusion to the molding of the sheet by a mandrel. SOLUTION: The surface temp. of a thermoplastic polyester resin foamed sheet is held to 180 deg.C or higher until the sheet reaches the mandrel from an extruder. For example, the foamed sheet from the extruder to the mandrel is covered with a hood made of aluminum or the like. Or, air with a temp. of 180 deg.C or higher is blown on the foamed sheet immediately after extrusion to prevent the surface temp. of the foamed sheet from lowering. When the foamed sheet is cooled to below 180 deg.C until it reaches the mandrel from the extruder, the foaming of a low temp. part is stopped and wrinkles are formed on the surface of the foamed sheet or a part partially generating crystallization is present by the irregularity of foaming magnification and wrinkles or tearing is generated by the irregularity of crystallization.