Papermachine fabric

Abstract

The invention relates to a papermachine fabric, in particular a press felt, having a carrier layer on which, at least in some sections, fibers with exposed fiber ends are arranged, the fibers forming a contact surface with which a paper web can be brought into contact, and wherein the contact surface is substantially formed by the exposed fiber ends.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 10 2004 056 319.5 filed on Nov. 22, 2004, the disclosure of which is expressly incorporated by reference herein in its entirety. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The invention relates to a papermachine fabric, in particular a press felt for the press section of a paper machine. [0004] 2. Discussion of Background Information [0005] In U.S. Pat. No. B2-6,605,188 a trasport belt for a paper machine is disclosed which, on its paper-side surface, has a layer comprising at least two fibers with different surface properties. This paper-side layer has hydrophilic and hydrophobic regions, in order to improve the separation properties of the belt from the paper web. The additional surface having the at least two different fibers is ground flat in a suitable way, the fibers being to some extent exposed on the surface and...

AI Technical Summary

Benefits of technology

[0008] The invention is based on the object of providing a papermachine fabric of the type mentioned at the beginning with which a high paper quality can be achieved and in which, in particular, imprints on the paper web are prevented. A further object of the invention is to produce a papermachine fabric having improved paper removal properties.

[0011] In this case, it is advantageous that, by means of a papermachine fabric of this type, the contact surface on an even and flat level with respect to the paper web is increased and the dimensions of each individual contact point between the fabric on the paper web are kept as small as possible. Overall, the result is thus a high number of contact or supporting points on the paper-side surface of the fabric which do not press into the paper web, precisely because of their large number and respectively small area. As previously mentioned, fiber indentations or impressions normally constitute a reason that printed dots are missing in the finished product, for example in a graphic paper such as a newspaper page printed in the gravure printing process, which can be attributed to the incompletely even structure of the paper web. As a result of the large number of relatively small contact points, the result is thus a very even and uniform surface of the papermachine fabric, that is to say for example a press felt, and therefore a likewise uniform surface of the paper web, which therefore has a very high quality.

[0012] Furthermore, as a result of the high number of relatively small contact points of the contact surface coming into contact with the paper web, the ability to remove the paper web simply from the papermachine fabric, for example when transferring the paper web to another fabric, is improved considerably.

[0019] According to another development to the invention, the ends of the fibers project beyond the surface of the carrier layer or the binder layer by less than ten times the fiber diameter, preferably less than five times, particularly preferably less than three times the fiber diameter. This relation can also be important for reducing indentations on sides of the paper web. Viewed generally, in order to reduce indentations, the relation between the extent of the projection of the fibers beyond the surface of the fabric relative to the fiber diameter and to the flat resting of the fibers in the case of the prior art can be decisive. According to the invention, this relationship is decisively important for fiber diameters >3 dtex. Fibers with a fineness index <3 dtex do not have to follow this relationship because of the fact that they cannot cause any indentations on the paper web which influence the subsequent printing of the paper.

[0022] According to another development of the invention, the binder layer is softer than the fiber material and preferably formed from a thermoplastic elastomer. This ensures flexibility, which also contributes to reducing indentations on the paper. However, it is also possible for the binder layer to be similarly hard or harder than the fiber material, depending on the construction of the complete structure of the papermachine fabric.

Problems solved by technology

Loops of this type or fibers lying flat can impair the quality of the paper produced in the paper machine because of indentations in the paper, in particular if these indentations or impressions lead to missing dots on the paper later when the paper is printed, for example in the gravure printing process.

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