THERMOPLASTIC POLYESTER-BASED RESIN FOAM AND PRODUCTION THEREOF

摘要

PURPOSE:To obtain the title foam suitable as a structural material by bringing the surface of a melt-extruded thermoplastic polyester-based resin containing a foaming agent and keeping surface temperature being melting point of crystal or above into contact with a liquid having a specific temperature to specify degree of crystallinity of the surface part. CONSTITUTION:A foaming agent such as azodicarbon amide is added to a thermoplastic polyester-based resin previously dried and the resin is melt- extruded at >=200 deg.C to foam the resin and while the surface temperature of the foam is kept at a high temperature higher than the melting point of crystal, the resin surface is brought into contact with a liquid (preferably water) or solid (e.g. copper) at a temperature not higher than glass transition point of the resin and quickly cooled to provide the aimed foam being <=30% in the degree of crystallinity of skin part being within 0.5mm depth from the surface of foam and having a degree of crystallinity >=1% lower than that of resin in central part, >=3mm thickness and 0.1-0.7g/cm<3> apparent density to provide the aimed foam.