| 摘要 |
PURPOSE:To obtain the shape, which has a smooth surface, a gloss and no indentation among grains, and a thermal secular contraction rate thereof is small, by a method wherein the foaming grains, grain themselves thereof have expansion capability, are further provided with foaming capability, and heated and foamed within a time when expansion capability does not lower. CONSTITUTION:Spherical foaming grains, which have surfaces, the degree of smoothness S thereof is 1.05 or lower, foaming magnification D thereof is 20-40 and a damping coefficient T of air pressure pressurized into grains thereof satisfies D/1,500>=T>=D/2,500, are prepared by using the cross-linked polyethylene resin as a blank. The inner pressure of the grains is governed up to 0.05-3kg/cm<2> (gauge pressure), and the grains are filled in a mold, and heated and foamed within the time when the expansion capability does not lower. When the grains are matured for 6hr or more at 60 deg.C, a product, the thermal secular contraction rate thereof is small, and which is thick excellent in water absorbency resistance, superior in surface glossy property and heat-creep resistance, has no shrink and wrinkle, and no indentation among the grains, is obtained. |
