| 摘要 |
PROBLEM TO BE SOLVED: To obtain a foam having a specified structure by extruding a foamable melt prepared by kneading a base resin containing a silyl-modified polypropylene resin or a mixture thereof with an unmodified polypropylene resin and a blowing agent under applied heat and pressure into a lower pressure zone to form a foam and bringing the foam into contact with water in the presence of a silanol condensation catalyst. SOLUTION: A base resin containing 20-100 pts.wt. silyl-modified polypropylene resin and 0-80 pts.wt. unmodified polypropylene resin, a volatile blowing agent and a cell modifier are kneaded under applied heat and pressure to form a foamable melt. This melt is extruded into a lower pressure zone to form a foam, and this foam is crosslinked by contact with steam in the presence of a silanol condensation catalyst such as dibutyltin dilaurate to obtain a crosslinked foam having a mean cell diameter of 0.5-2.0 mm, a density of 0.025-0.3 g/cm<3> , a thickness of 1,5-10 mm and a gel fraction of 15% or above. The silyl-modified polypropylene resin is obtained by grafting an unsaturated silane compound onto a polypropylene resin satisfying the formula in the presence of a peroxide and an antioxidant. |
