| 摘要 |
PURPOSE:To improve the formability of extension-foaming and the heat resistance of a foam by a method in which thermoplastic polyester resin, fusion property-modifier and foaming agent are mixed and are extrusion-foamed, and then the heat quantity of the cooled crystallization of the secondary foam having been obtained by heating said foam again, is set at a specified value or less. CONSTITUTION:Thermoplastic polyester resin, fusion property-modification and foaming agent are mixed and are extrusion-foamed. Next, this foam is again heated and is secondarily foamed, and then the heat quantity of the cooled crystallization of said secondary foam is caused to be 3000 joule/mol or less. The mixing of the fusion property-modification modifies the viscosity in molten state, die swell, and melt tension of the thermoplastic polyester resin, whereby the formability of extrusion-foaming is improved. Further the temperature of heat treatment to cause the heat quantity of the cooled crystallization of the secondary foam to be at most 3000 joule/mol, is set so that the temperature from the surface to the central part of the foam immediately after extrusion-foaming is at least glass transition temperature, preferably the temperature higher than the glass transition temperature of at least 50 deg.C and under fusion-starting temperature. |
