| 摘要 |
PURPOSE: To form a smooth surface free from wrinkles and to especially improve gloss or surface decoration properties due to embossing by extruding a resin from a flat sheet die equipped with a lip wherein the open angle of lip opening part is set to a specific angle and the distance from the start point of the lip opening part to the leading end thereof is set to a specific dimension to foam the same and cooling the foamed sheet over the specific distance from the leading end of the die. CONSTITUTION: The lip 2 of a die 1 is formed so as to have such a shape that the open angleθof the opening part of the lip 2 is 5-30 deg. and the distance L from the start point 3 of the opening part to the leading end 4 thereof is 2-40mm. Further, the cooling of a foamed sheet 5 is performed by cooling rolls 6, 7:8, 9:10, 11 and the interval between each pair of the rolls is set to 200-700mm. The cooling rolls 6, 7 are set so that the distance D from the leading end 4 of the die 1 to the center line of the upper and lower cooling rolls 6, 7 becomes 5-50mm. When the distance D exceeds 50mm, volumetric expansion is generated after emission to become easy to cause vertical wrinkles. As a result, sudden volumetric change after the release to atmospheric pressure is prevented and the surface of the foamed sheet is made smooth by the cooling rolls and the internal structure thereof can be made uniform. |
