Process for watermarking paper - uses patterned suction to draw a fluid suspension through the wet pulp

Abstract

Abstract The process to develop a watermark in a paper web, during paper mfr. uses a patterned support surface for the wet paper pulp, with suction applied through this pattern to extract pulp water partially. A fluid suspension is applied before the pulp leaves the suction pattern surface so that it is drawn through the pulp and integrated in it before it is dried fully to form the paper. The process allows a distinctive marking to be introduced into a wide range of papers by a simple modification of the existing machinery. The material in the fluid suspension is designed to increase or decrease the translucency of the finished paper in the patterned zones, or to introduce a pigment to show the watermark pattern. Pref. materials are titanium oxide calcium carbonate or chalk whiting, in water. A thickening agent such as CMC and a foaming agent can be added.

Inventors

• 👤 Bronislaw Radvan
• 👤 Peter George Davis
• 👤 Christopher John Hardstaff

Bibliographic Details