| 摘要 |
PURPOSE:To obtain a thick foamed synthetic resin sheet wherein even a thick one is free from occurrence of a crease on a fringe side part and little in variation of thickness owing to aging in a method for manufacture of the thick foamed synthetic resin sheet by a method wherein a foamed synthetic resin sheet tubularly extruded from a circular die, and pinched to weld two sheets by fusion thereby. CONSTITUTION:When a foamed synthetic resin sheet of a two-ply combined thick product is obtained by extruding synthetic resin as a tubular sheet 4 from a circular die 2 and welding an inner surface by fusion by pinching the tubular sheet 4 with pinch rolls 6, the tubular sheet is pinched with the pinch rolls 6 while it is being controlled so that it becomes of an elliptical form wherein its sectional form has major axis/minor axis=1.1-3.0 at a neighboring point when foaming ends, density after pinching becomes 0.2g/cc-0.04g/cc, and 0.5wt.%-8wt.% of isobutane is contained in remaining gas. |
