| 摘要 |
PURPOSE:To obtain high internal loss and high flexural rigidity with light weight constitution by heat-sealing different surface material sheets, consisting essentially of thermoplastic resin, on both surfaces of a foamed core material sheet consisting essentially of thermoplastic resin. CONSTITUTION:While superposed upon the surface of a core material sheet 2, a surface material sheet 1 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. The laminated composite sheet 6 is heated at high temperature by heaters 4 and 4' for several seconds, and a foamed material in the core material sheet 2 is heated above its foaming start temperature to be foamed, and polyehtylene short fiber of the surface material sheet 1 and polyethylene which is the base material of the core material sheet 2 are molten. This composite sheet 6 is treated by cold press between dies 5 and 5' to be formed in a diaphragm shape. |
