| 摘要 |
PURPOSE:To obtain a tubular foam with uniform, constant wavy patterns in place by a method wherein expandable thermoplastic resin is throttled by a mold consisting of a specified inner mold core and a similar outer mold so as to be extruded in a tubular body with odd-shaped section. CONSTITUTION:Thermoplastic resin composition 1 sent in a molding die 5 is extruded while being throttled by an opening side outer mold 9 and finally expands itself freely because the pressure is released after passing through an opening 10. Because the foaming direction of the extruded molding body 11 is directed from inside to outside, the inside of the section of the molding body 11 expands while keeping a shape nearly similar to the odd-shape of an inner mold core 7 and similarly its outside expands while keeping a shape nearly similar to the odd-shape of the section of the opening side outer mold 9. The molding body is taken up after being extruded at a speed expressed by means of a formula in the attached figure. In the formula, V0= linear speed (m/ min) when the composition expands freely, R1= maximum distance (mm.) from the center of the section of a foam when the composition expands freely R2= minimum distance (mm.) from the center of the section of the foam when the composition expands freely wherein R2>t, X= density (g/cm<3>) of the foam where 0.07>x>0.025 and 150= constant. |
