| 摘要 |
PURPOSE:To produce a polypropylene resin crosslinked foam improved in surface strength. CONSTITUTION:A foamable resin composition containing polypropylene resin, a thermal decomposition type foaming agent and a crosslinking auxiliary is crosslinked and subsequently heated in a liquid phase or gas phase stepwisely set from a low temperature side to a high temperature side to foam the resin composition. When the foamable resin composition is heated in the liquid phase, the resin composition is subjected to the first heating treatment within a temperature range of -10 to +20 deg.C and subsequently to the second heating treatment within +20 to +50 deg.C on the basis of the decomposition point of the thermal decomposition type foaming agent. When the resin composition is heated in the gas phase, the resin composition is subjected to the first heating treatment within a temperature range of +20 to +50 deg.C and subsequently to the second heating treatment within a temperature range of +50 to +200 deg.C. |
