| 摘要 |
PURPOSE:To obtain a crosslinked highly expanded laminate having uniform cell structure by a method wherein crosslinking agent, which reacts with the reactive group of a mixed stock, and foaming agent are added in an extruder so as to knead them by heating at a temperature of the decomposition temperature of resin or lower and then formed into a sheet and, after the sheet is heat-treated, a thermoplastic synthetic resin layer is laminated onto the surface of the sheet. CONSTITUTION:Polyvinyl chloride-based resin, which has reactive group in molecule, or mixture of polyvinyl chloride-based resin, which does not have reactive group in molecule, and thermoplastic resin, which has reactive group in molecule, are fully homogeneously dispersed in other compounding stocks. Just after dispersion, crosslinking agent and foaming agent are charged in an extruder so as to be kneaded. The resultant composition is fully kneaded under the processing condition of the temperature, which is below the reaction temperature of the crosslinking agent contained and below the decomposition temperature of the foaming agent contained, so as to become homogeneous and, after that, extruded from a T-die in order to form a solid resin sheet. After that, said sheet is heated up to the temperature not lower than the reaction temperature of the crosslinking agent and the decomposition temperature of the foaming agent so as to crosslink said sheet and expand it, resulting in obtaining a highly expanded lower layer foamed sheet. Finally, a skin layer made of thermoplastic synthetic resin is formed on the top surface of said lower layer foamed sheet. |
