Press felt for papermaking

Abstract

This invention provides a press felt (10) for papermaking, comprising a substrate (30), a wet paper-side vat layer (20) and a press-side vat layer (23). The wet paper-side vat layer (20) comprises a wet paper contact-side vat layer (21) and a substrate-side vat layer (22). The wet paper contact-side vat layer (21) comprises a core-sheath composite fiber (41) comprising a core component of a high-molecular weight nylon having an absolute viscosity of not less than 80 mPas and a sheath component of a nylon having a lower melting point than the core component. The substrate-side vat layer (22) comprises a layer of a nylon fiber (42) free from the core-sheath composite fiber (41). The sheath component of the core-sheath composite fiber (41) is melted to render the wet paper contact-side vat layer (21) dense, and, consequently, moisture in the press-side vat layer (23) is less likely to be moved to the wet paper side, whereby a remoistening phenomenon can be suppressed. Further, since the substrate-side vat layer (22) comprises a nylon layer free from the core-sheath composite fiber, the balance among smoothness, defiber resistance, abrasion resistance, compression fatigue resistance, and water drainage is good.

Description

technical field [0001] The present invention relates to a papermaking press felt (hereinafter simply referred to as "press felt") used in a papermaking machine. Background technique [0002] Conventionally, in the papermaking process, a press device has been used to dehydrate wet paper. In the press unit, the wet paper forming the ply is dewatered in the press nip through the press felt. In addition, the pressing device usually consists of a plurality of pressing nips. [0003] Figure 5 It is a schematic diagram of the pressing nip in the pressing device. [0004] The press nip includes a pair of press rolls P', P' and a pair of press felts 11', 11' clamping the wet paper W'. , 11' and wet paper W' apply pressure, and the moisture in wet paper W' is squeezed out and absorbed by press felts 11', 11'. [0005] However, since the pressure applied to the wet paper W' and the press felts 11', 11' is suddenly released from the center of the press section (nip section) to the ...

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Problems solved by technology

[0005] However, since the pressure applied to the wet paper W' and the press felts 11', 11' is suddenly released from the center of the press section (nip section) to the exit, the volume of the press felts 11', 11' Rapid expansion

As a result, a negative pressure is generated in the press felts 11', 11', and furthermore, since the wet paper W' is composed of fine fibers and accompanied by capillary phenomenon, the moisture absorbed by the press felts 11', 11' will reappear. The phenomenon of moving to the wet paper side, that is, re-wetting phenomenon (re-wetting)

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