| 摘要 |
PURPOSE:To easily obtain a high-quality hollow molding with a simple equipment by inserting a gas-generating substance inside a metal mold cavity, injecting a thermoplastic forming material into the cavity so as to enclose the gas-generating material and causing the generation of gas. CONSTITUTION:After closing a mold, a gas-generating material 26 (aliphatic azo compound, nitrose compound, hydrazine derivative, sodium bicarbonate, etc.) is inserted into a cavity 19. Next, a small quantity, e.g. approximately 1/2-2/3 of the capacity of the cavity is injected into the cavity 19 from a nozzle on a molding machine to enclose the gas-generating material 26. The gas-generating material 26 is decomposed by the heat of the molding material to generate a gas. The molding material injected into the cavity is cured starting from its part touching the cavity wall and the uncured molding material is extruded by the gaseous pressure in to the part where it is not yet filled, thus a hollow part is formed. |
