Process for marking a paperweb, paperweb having a watermark pattern

摘要

The marking procedure, for use on paper with at least one layer of cellulose wadding, consists of deforming the paper under pressure between a first rigid roller (1) with a smooth surface, and at least one secondary rigid roller (2) with relief elements, and includes the cold application of an additive coating that promotes the formation of a watermark on at least one surface of the paper or rollers during the marking operation. The additive is based on mineral oil, e.g. a white mineral oil with a dynamic viscosity of 15 - 80 mPa.s. at about 25 deg C, and can be applied by spraying, atomisation or coating at a preferable rate of 0.2 and 0.5 per cent by weight in relation to the paper. The motifs formed by the roller relifs are preferably between 30 and 40 sq mm in area each.