| 摘要 |
PURPOSE:To highten the multiplying ratio of foaming and also to improve the foaming condition by a method wherein crystallinity index of molten foaming resin is made under 10% by rapidly cooling it, and it is heated and foamed after being dipped in foaming agent of which boiling point is under 100 deg.C at the specified temperature. CONSTITUTION:Crystallizable polyester resin is rapidly cooled and the whole crystallinity index of it is made under 10%, after it is melted and foamed in any shape. Foaming agent of which boiling point is under 100 deg.C at the normal pressure is dipped in the closed vessel at the temperature of glass transformation temperature plus 50 deg.C of said resin. And, said foaming agent impregnated resin is heated and foamed at the temperature above glass transformation temperature of the resin, and under melting temperature of crystal resin. As for foaming agent, the boiling point at the normal pressure is under 100 deg.C, preferably under 50 deg.C. And it is necessary to avoid the material of which SP value is near to using resin. |
