| 摘要 |
PURPOSE: To produce a polypropylene resin foam having a high content of fine and uniform closed cells and high rigidity with excellent moldability and high productivity by blending a specific ethylene-propylene block copolymer with a blowing agent and foaming the blend by extrusion. CONSTITUTION: This polypropylene resin foam is obtained by blending (A) an ethylene-propylene block copolymer having 1-10g/10 minutes melt flow rate, 1-10wt.% of ethylene content, >=6dl/g intrinsic viscosity [η] of p-xylene soluble content at 23 deg.C and the ratio of the weight-average molecular weight Mw/the number-average molecular weight Mn of >=10 with (B) a blowing agent (preferably a thermal decomposition type blowing agent such as azobisisobutyronitrile, etc.) in the ratio of preferably 0.1-30 pts.wt. of the component B based on 100 pts.wt. of the component A and foaming the blend by extrusion. The component A is preferably obtained by combining a process for polymerizing propylene in the presence of a stereospecific polymerization catalyst to give a crystalline propylene-based polymer with a process for copolymerizing propylene with ethylene to give a noncrystalline propylene-ethylene copolymer. |
