| 摘要 |
PURPOSE:To obtain a polystyrenic resin foam sheet excellent in surface appearance after secondary molding within a short ageing period by applying pressure treatment to a specific sheet like foam within the temp. range from the normal temp. to the thermal deformation temp. of a polystyrenic resin under predetermined pressure for a predetermined treatment time. CONSTITUTION:A polystyrenic resin foam sheet is produced by applying pressure treatment to a sheet like foam obtained by subjecting a polystyrenic resin to extrusion molding along with a physical foaming agent within the temp. range from the normal temp. to the thermal deformation temp. of the polystyrenic resin under gauge pressure of 0.5-20kg/cm<2> for 0.1-2hr. In this case, when the pressure is below 0.5kg/cm<2> as gauge pressure and the treatment time is below 0.1hr, pressure is insufficient and, when the pressure exceeds 20kg/cm<2> as gauge pressure and the treatment time exceeds 2hr, the surface smoothness of the sheet is damaged and, further, secondary foaming is lowered. When atmospheric temp. exceeds the thermal deformation temp. of the polystyrenic resin, secondary foaming is started and the surface smoothness of the sheet is damaged. |
