COUNTERFEIT-PROOF PAPER INCLUDING WATER SIGNS WITH MULTITONE EFFECT, AND MESH TO PRODUCE THIS PAPER Russian patent published in 2010 - IPC B41M3/10 B42D15/00 

FIELD: textile, paper.

SUBSTANCE: invention relates to pulp and paper industry, in particular to production of paper, with water sign, to make banknotes and secure documents that require higher counterfeit protection. Counterfeit-proof paper includes water signs with multitone effect, having light and dark elements, visually perceived in passing light in the form of raster image, besides, light elements are characterised by smaller weight per unit of paper area, compared to dark elements. At the same time total area of light elements of water sign, optical density of which is less than optical density of paper, makes at least 1% of total area of paper, and depth of light elements of water sign does not exceed 70% of paper thickness. Mesh to manufacture counterfeit-proof paper comprises masks to form water sign, which are solid elements arranged between perforated sections of mesh, besides, at least on one mask there are microholes with diametre of not more than 0.25 mm, and total area of microholes makes not more than 15% of overall area of mask.

EFFECT: invention increases strength of paper with preservation of good graded conveying of image tones.

4 cl, 3 dwg