Web coating system for fiber web surface of paper-making machine

摘要

To apply a liquid or paste coating to the surface of a moving web, of paper fibers, an applicator system (14-17, 35,28,31,32) applies a further coating of the liquid or paste, after the first press unit (13) of the press section (34). The additional coating is applied at the end of the press section (34) and within the drying section (35). The initial and additional coating materials, as a fine fiber suspension, contain an agent to bond the web surface. The coating medium also contains components recovered as a fraction from extracted water at the fourdriniers. The application in the double fourdrinier zone is supported by fourdrinier guides (S,F,7-9), using at least one roller (S,F) and one unit (7-9) without rotation. The coating is delivered in the wet section (33) by applicators (5,10) and, in the press section (34), by applicators or spray jets or press rollers (15). The pressure applied at the application systems is 0.05-0.5 bar and pref. 0.1-0.4 bar. The fiber web (38) has a solid matter content of 5-50% at the end of the double fourdrinier zone, and pref. 8-17%. The first coating application is at a rate of 1-10 g/m<2> dry weight. The coating contains additives of ink or mineral bulking agents such as kaolin, clay, talcum, zeolite, CaCO3 or TiO2.