| 摘要 |
A method of making a watermarked polymeric sheet includes forming a web (22) of a polymeric material, selectively irradiating portions of the web (22) with electromagnetic radiation, and stretching the web to form a sheet (26) having increased length and/or width. The watermarked polymeric sheet (26) has a plurality of indentations in at least one surface thereof, in areas corresponding to the irradiated portions ofthe web. The indentations form a watermark comprising areas of increased translucency, which is visible by transmitted light. <IMAGE> |
