| 摘要 |
The impression of the microengravings is achieved by means of an embossing process wherein the paper is passed through an embossing group (17, 18), consisting of an embossing cylinder (17) carrying said microengravings and a counterthrust cylinder (18), said process being carried out, after humidification of the paper, at a temperature and a pressure on the paper passing between said cylinders included within the ranges of 90-220 degree C and 20-120 kg/mm2 respectively, preferably 130-170 degree C and 40-100 kg/mm2 respectively.
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