| 摘要 |
PURPOSE:To carry out foaming, sliding well in the inner surface of a mold, hard to generate cracks in foamed material even in a violent foaming, having a thick non-foaming skin layer of foamed material itself and of good product and material efficiency by heat foaming a foamable crosslinked composition in the state of being covered with a plastic sheet. CONSTITUTION:A foaming agent, a crosslinking agent and, if necessary, an auxiliary foaming agent, a filler, a pigment and the like are added to polyolefin, which is mixed by a heated mixing roll or the like. Then, a foamable crosslinked composition thus prepared is put into a mold and formed at 115-155 deg.C corresponding to the kinds of resin and the crosslinking agent under pressure, and also the composition and a plastic sheet are welded by heating and the sheet is covered on the surface of composition. The formed foamable crosslinked composition is then heated under normal pressure, and decomposition of the crosslinking agent and the foaming agent is carried out simultaneously. Membranes of the foamed material thus prepared is destroyed by compression deforming by means of a uniform rate twin roll or the like, and the foams are connected to manufacture a continuous foamed material. |
