| 摘要 |
PURPOSE: To obtain plate-shaped foam extremely reduced in warpage and excellent in flatness by pressing cylindrical foam obtained by foaming a non- crosslinked propylene resin with drawdown properties of a specific value or less to form the same into a plate shape and holding the pressed foam between conveyor belts to transfer the same under cooling. CONSTITUTION: A non-crosslinked propylene resin with drawdown properties of 60m/min or less is melted in an extruder 1 and kneaded along with a foaming agent at high temp. under high pressure to form a foamable resin compsn. which is, in turn, extruded from the annular die 2 provided to the leading end of the extruder 1 under pressure lower than the pressure in the extruder to be foamed in a cylindrical form and this cylindrical foam 3 is pressed to fuse the inner surface thereof to obtain plate-shaped foam with a thickness of 2-15mm and density of 0.06-0.3g/cm<3> Next, the plate-shaped foam 4 is held between conveyor belts 5 and transferred to be cooled. As a result, the warpage of the plate-shaped foam can be set to 10mm or less. The cylindrical foam 3 is formed into a plate shape by pressing the foam 3 by pinch rolls 7 set to a temp. of 50-150 deg.C. |
