| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a product having improved compression strength and rigidity in high productivity, in a method for producing a plastic foam sheet in which a cap sheet having numbers of caps is molded by vacuum forming, and a flat back sheet is laminated on the bottom surfaces of the caps to form numbers of closed air cells. SOLUTION: A crystalline polyolefin is used as a plastic material for the cap sheet. Immediately before a sheet for the cap sheet contacts a vacuum forming roll, the sheet is cooled by spraying cold air from an air knife to the sheet, or bringing the sheet into contact with a temperature-adjusted cooling roll to decrease the temperature of the sheet to a crystallization temperature area. Since the temperature of the sheet is decreased slowly due to heat generation associated with the advance of crystallization, the cap sheet is obtained by vacuum forming during the cooling. In this way, the caps uniform in thickness and additionally having an orientation effect are molded. |
