| 摘要 |
PROBLEM TO BE SOLVED: To obtain a composite foamed sheet having high compressive strength by laminating a sheet which inhibits the foaming force in the direction of plane on at least either surface of a sheety thermoplastic resin material containing a heat-decomposable blowing agent and forming the laminate. SOLUTION: It is desirable that the long axis of the foamed cell is oriented approximately in the direction of the thickness of the sheet, the ratio of the long axis to the short axis of the cell is 2 or above, and the density of the central part in the direction of thickness is smaller than that of a surface part. This composite sheet is obtained by laminating and integrating a sheety material which inhibits the foaming force of the sheet on a thermoplastic resin sheet containing a heat-decomposable blowing agent and foaming the laminate by heating. It is desirable that the lamination and integration is performed by a method comprising passing a blowing-agent-containing resin sheet extruded from a T-die and lightly laminated with a sheety material on each side between a pair of opposed cooling rolls. |
