| 摘要 |
1420798 Repairing surface crazing of foamed polystyrene sheets OWENS-ILLINOIS Inc 19 Dec 1973 [20 Dec 1972] 58764/73 Heading C3C [Also in Division F2] Crazing damage to the surface of expanded polystyrene sheet, which sheet has been formed with a solidified central region of density smaller than its surfaces, is repaired by heating the damaged surface of the sheet sufficiently to soften and fuse damaged areas of the surface, and cooling the heated surface of the sheet before the heat penetrates sufficiently into the sheet to cause expansion of blowing agent contained in the central region of the sheet. Expanded, general purpose, high density polystyrene containing residual pentane and having a crazed surface, W, may be passed over a heated roller 12 with idler roller 13 controlling the angle of wrap between W and 12, which is also controlled by cooled roller 14. Take off rollers 15 and 16 also control the angle of wrap between W and 14. |
