US 5,298,124 AGranted

Transfer belt in a press nip closed draw transfer

AssigneeAlbany International Corp.

InventorsNils O. Eklund, Lars E. C. Fagerholm, Lynne R. Muscato

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Abstract

A transfer belt for eliminating an open draw between a press in a papermachine and a transfer point has a supporting base with a particle-filled polymer coating. The coating, which constitutes the paper side of the transfer belt, carries the paper sheet from a press nip in a closed draw to a transfer point without sheet flutter or drop-off. At the transfer point, the paper sheet is readily released to another sheet-conveying papermachine-clothing product. The transfer belt may carry the sheet through more than one press nip. The transfer belt surface has a pressure-responsive recoverable degree of roughness, which is made relatively smooth by compression in the press nip, allowing the thin, almost continuous water film to form between the transfer belt and the paper sheet. When leaving the press nip, the paper sheet is held to the transfer belt by the thin, almost continuous water film. Following exit from the press nip, the transfer belt surface recovers its uncompressed roughness, breaking up the water film, so that, by the time the paper sheet reaches the transfer point, it is readily released by the transfer belt to the next sheet-conveying papermachine-clothing product, which might be a felt, a belt, or a fabric.

Claims38

Dependent claims

In a papermaking or boardmaking machine, a transfer belt for carrying a paper web from a first transfer point, at which said transfer belt is subjected to compression in a press nip, in a closed draw to a second transfer point, said transfer belt comprising:

a reinforcing base, said reinforcing base having a back side and a paper side;
and
a polymer coating on said paper side of said reinforcing base, said polymer coating having a hardness in the range from Shore A 50 to Shore A 97, said polymer coating having a web-contacting surface with a pressure-responsive, recoverable degree of roughness throughout the lifetime of said transfer belt on said papermaking or boardmaking machine, said polymer coating having an uncompressed roughness in the range from R.sub.z =2 microns to 80 microns, and being compressed to the range from R.sub.z =0 microns to 20 microns when said transfer belt is in the press nip, and said polymer coating returning to its substantially uncompressed roughness after exit from the press nip,
wherein said polymer coating includes a particulate filler, said particulate filler being a plurality of discrete particles incorporated within said polymer coating, and said discrete particles in said plurality thereof having a hardness different from that of said polymer coating,
said transfer belt being substantially impermeable to air and water the permeability to air being less than 20 cubic feet per square foot per minute.

2 more elements

Dependencies are inferred from the claim text.