| 摘要 |
Cuspidal sheet has two faces each having a gp of peaks of hollow projections the part of the sheet connecting the peaks having a minimum area, and the peak of each projection being thicker than the parts of the sheet connecting them, the ratio of the height of the cusps to their diameter bing above 2:1 pref. 2:1-3:1. The sheet has high resistance to compression vertical to the plane of the cuspids, is extremely flexible. Specif. the sheet is made of a thermoplastic material which can be melt spun, soda glass, borosilicate glass, low density polyethylene, high density polyethylene, polypropylene high impact polystyrene, nylon 6, nylon 6.6, or nylon 6.10. and is produced by (a) defoaming a sheet of thermoplastic material by pressing against a face of the heated sheet a group of cold projections, and (b) pressing simultaneously against the second face of the sheet, a second group of cold projections, so that the gps. overlap or interpenetrate and the projections of the second gp are spaced from the projections of the first gp. by a distance greater than the thickness of the sheet. |
