| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a multi-layered expanded sheet which no longer appears unpresentable with a scaly surface, by virtue of a multi-layered circular die co-extrusion process. SOLUTION: This method for manufacturing a multi-layered expanded sheet uses a multi-layered circular die co-extrusion process for manufacturing a multi- layered expanded sheet with an expanded layer and a non-expanded layer, each of which exhibits a shear stress of 5,000 to 50,000 Pa in the interface. In addition, this method for manufacturing a multi-layered expanded sheet uses a straight-chain propylene resin with a melt flow rate of 5 to 30 g/10 min. as the non-expanded layer. Further, the method for manufacturing the multi-layered expanded sheet uses a propylene polymer having a melt tension(MT) at 190 deg.C and a melt flow rate(MFR) at 230 deg.C which satisfy formula (A) MT>=7.52×MFR<(-0.576)> . |
