| 摘要 |
<p>PURPOSE:To obtain a PVC plate for thermal processing having surface glossiness or transparency not inferior to that of a press plate produced by a calender press method and suppressed from such a phenomenon that the surface of the PVC plate loses surface glossiness to become a cloudy state even if affected by heat at the time of welding. CONSTITUTION:Transparent extruded sheets 2, 2' each thinner than a laminate of a plurality calender sheets 1' made of transparent PVC are superposed on both surfaces of the laminate and the whole is integrated under heating and pressure to form an inner layer 1 and outer layers 2, 2 each thinner than the layer 1. The thickness of the inner layer 1 is set to about 3mm and that of each of the outer layers 2, 2 is set to about 1 mm. By this constitution, even when case reversion is generated on the surface of the PVC plate for thermal processing by the effect of heat, since the case reversion surface state is the surface state at the time when the sheet is extruded from a die at the time of the production of the extruded sheet, the surface gloss of the PVC plate is hardly damaged.</p> |
