Device for creating multitone watermarks and methods of manufacture and use thereof

摘要

The present invention relates to the field of paper and relates to a sheet including a high-definition high-contrast multitone watermark having areas of pronounced brightness. Such watermark is particularly obtained by means of a part (4) including a surface (5) having a raised area and perforations (6). The perforations (6) are such that making the cross-section thereof, at a given distance from the draining surface, directly depends on said distance. The present invention also relates to the method for manufacturing said part that is used for forming one such watermark, to the part itself, and to the use of said part when forming a watermark.

主权项

1. A method of manufacturing a device for creating multitone watermarks in a substrate by drainage of a fibrous suspension, said device comprising a body having a profiled surface and a drainage surface, said surfaces being opposite, a relief on the profiled surface, and a plurality of perforations within the body, each perforation comprising a through-channel with an inlet on the profiled surface and an outlet on the drainage surface, the method comprising the steps of:
forming said relief on said profiled surface; forming said plurality of perforations within said body, wherein the cross-sectional area of the through-channel at a given distance from the drainage surface is a function of the distance from the cross-sectional location to the drainage surface; and subjecting said device for creating watermarks during manufacture to an at least one sintering step.