Rolls for the press section of machines for manufacturing and/or refining fibrous webs

Abstract

A roll for a press section of a machine for making and / or finishing a fibrous web, such as a paper, board, or tissue machine, includes a roll body or roll shell and, disposed on the roll body or roll shell, a roll covering which has at least one functional layer which is suitable for entering into contact with the fibrous web or with a paper machine fabric. The functional layer is formed of a polymer which is a mixture of at least one prepolymer, a curing agent, a crosslinking agent, and an additive. The additive is selected from the following: perfluoropolyethers, bifunctional perfluoropolyether, or mixtures thereof.

Description

technical field [0001] The invention relates to a roll for use in a machine for processing web and / or finishing web, such as a paper, board or tissue machine. Background technique [0002] In the above-mentioned machines, press rolls or suction press rolls are generally used in the press section, which after the primary dewatering are removed from the fiber web in the forming section, in particular by mechanical pressure and / or by suction. Drain other liquids. [0003] The press rolls or suction press rolls used are often coated with polyurethane. The dewatering capacity of press rolls or suction press roll covers depends primarily on the surface design of the roll covers. Usually there is a pattern of blind holes and grooves which provide open spaces into which the water expressed by the fibrous web can be diverted. [0004] In the case of suction press rolls, there are usually additional suction holes which penetrate the roll shell. Water is sucked out of the fiber web...

AI Technical Summary

Problems solved by technology

Wrong choice of opening area can lead to roll cover instability and lead to hydrological or mechanical porosity

[0007] Disadvantages of the press roll and suction press roll coverings known from the prior art are, in particular, that they become contaminated by prolonged use, whereby the surface shape is contaminated by fillers, fiber aggregates and resinous impurities present in the fiber suspension. Penetrates and no longer provides open space for dewatering the paper web

Furthermore, through irregular contaminants, undesired fluctuations in the humidity distribution may occur

[0008] As a remedy, mechanical cleaning devices only provide an insufficient effect for the adjustment of the roll coating, since the holes cannot be cleaned, for example, by hanging knives and brushes, while the treatment of the roll with washing liquid can lead to the input of undesirable substances into the in the fibrous web and causes its rewetting