| 摘要 |
PURPOSE:To obtain high internal loss and high flexural rigidity with light weight constitution, and to obtain watertightness and wear resistance, by using a foamed material for a core material sheet, and laminating a surface material sheet on the surface of this core material sheet. CONSTITUTION:A surface material sheet 1 while superposed upon the surface of a core material sheet 2 is passed between heater-incorporated rollers 3 and 3'. Then, since those rollers 3 and 3' are heated at low temperature, polyethylene which is the base material of the core material sheet 2 is molten to heat-seal the core material sheet 2 and surface material sheet 1. A composite sheet 6 of the core material sheet 2 and surface material sheet 1 laminated by being heated by the rollers 3 and 3' is heated at high temperature by heaters 4 and 4' for several seconds to be foamed, and the polyehtylene short fiber of the surface material sheet 1 and polyethylene which is the base material of the core material sheet 2 are molten. The softened composite sheet 6 are treated by cold press between dies 5 and 5' to be formed in a diaphragm shape. |
