Paper making and fiber liberation – Processes and products – Non-uniform – irregular or configured web or sheet
Reexamination Certificate
2001-07-27
2003-04-15
Griffin, Steven P. (Department: 1731)
Paper making and fiber liberation
Processes and products
Non-uniform, irregular or configured web or sheet
C162S361000, C162S362000, C162S205000, C162S358200, C162S358400, C162S901000, C442S218000
Reexamination Certificate
active
06547924
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to papermaking machines and methods of making paper, and more particularly relates to machines and methods for making textured soft paper, such as tissue.
BACKGROUND OF THE INVENTION
A paper machine for the production of tissue paper is disclosed in U.S. Pat. No. 5,393,384, see particularly FIG.
6
. The paper machine shown therein has a belt impermeable to water, which runs in a loop through an extended press nip formed by a shoe press roll and a counter roll. A press felt is conveyed directly to the press nip, where it is brought together with the impermeable belt and the paper web. The paper web is transferred from a forming fabric to the impermeable belt which is to carry the paper web on its under side up to the press nip and thence to the drying cylinder. The impermeable belt thus carries the paper web a relatively long distance after the paper web has been transferred from the forming fabric to the impermeable belt. There is therefore a risk of the paper web not adhering sufficiently strongly along the entire distance and thus becoming detached from the impermeable belt. According to the patent specification the adhesion force between the impermeable belt and the paper web is greater than that between the press felt and the paper web. The impermeable belt under discussion here is not compressible and has a smooth, web-carrying surface.
It is generally known that such a smooth, impermeable belt obtains a film of liquid on its smooth, web-carrying surface when belt, press felt and paper web pass together through a press nip and that, after the press nip, the paper web therefore adheres to the impermeable belt instead of to the press felt which does not have a smooth surface, when the press felt and the impermeable belt run away from each other. This situation is also utilized in U.S. Pat. No. 4,483,745. Since, however, both the impermeable belt and the drying cylinder in the paper machine according to U.S. Pat. No. 5,393,384 have smooth surfaces with which the paper web is intended to come into contact, there is considerable risk of the paper web continuing to adhere to the smooth surface of the impermeable belt after it has passed the nip at the drying cylinder instead of being transferred to the smooth surface of the drying cylinder as desired. Probably not even the application of large quantities of adhesive on the envelope surface of the drying cylinder would ensure adhesion of the paper web to the drying cylinder. U.S. Pat. No. 5,393,384 mentions nothing about texturing the paper web before the drying cylinder.
DE-195 48 747 discloses a paper machine for manufacturing creped tissue paper which is provided with a press comprising a shoe press roll, a counter roll and a suction roll, the counter roll forming a first press nip with the suction roll and a second extended press nip with the shoe press roll. A felt passes through the two press nips together with the paper web and then carries the paper web with it to a Yankee dryer, to which the paper web is transferred when the felt and the paper web pass around a transfer roll forming a non-compressing nip with the Yankee dryer. Suction zones are provided before and after the first press nip, the suction zone before the press nip being situated within the suction roll whereas the suction zone after the press nip is in a side loop in which the felt runs alone and joins the paper web again at the entry to the second press nip. One drawback with such a paper machine is that the paper web is exposed to re-wetting by the wet felt before it reaches the Yankee dryer. The paper machine has no impermeable belt, nor does the patent specification mention anything about texturing the paper web.
U.S. Pat. No. 5,298,124 discloses a compressible transfer belt for use in a paper or board making machine in order to eliminate open draws in the paper web and to easily release the paper web so that it can be transferred to a fabric or belt. The transfer belt carries the paper web through the press section, which comprises one or more press nips, and on to the drying section which comprises a plurality of drying cylinders and a belt passing in a loop around a transfer roll which forms a nip with the transfer-belt. Each press is also provided with a felt passing through its press nip and enclosing the paper web between it and the transfer belt. The impermeable transfer belt is also so designed that a liquid film formed in a press nip between the transfer belt and the paper web breaks up when the pressure on the transfer belt ceases after the press nip so that its release properties increase and the paper web can thus more easily be transferred to a fabric or another belt running in a loop. There is no suggestion or intimation in the patent specification that the transfer belt should be allowed to carry the paper web to a drying cylinder in a tissue machine. Nor is there any mention of texturing the paper web.
U.S. Pat. No. 5,298,124 offers an excellent description of the tasks a transfer belt cooperating with a press felt shall perform in a satisfactory manner, and also of the properties and design of such transfer belts which then were disclosed in patent specifications U.S. Pat. Nos. 4,483,745, 4,976,821, 4,500,588, 5,002,638, 4,529,643 and CA-A-1,188,556.
According to U.S. Pat. No. 5,298,124, for a transfer belt intended for cooperation with a press felt the critical tasks are a) to remove the paper web from the press felt without causing instability problems; b) to cooperate with the press felt in one or more press nips to ensure optimal dewatering and high quality of the paper web, and c) to transfer the paper web in a closed draw from a press in the press section to a paper web receiving fabric or belt in the following press or presses of the press section or to a pick-up fabric in the drying section.
As mentioned, the transfer belt for the press section of a paper machine disclosed in U.S. Pat. No. 5,298,124 has a web-contacting surface which is substantially impermeable to water and air and has a pressure-responsive microscale topography. Under influence of the pressure in a press nip in the press section, the transfer belt is compressed so that the microscale roughness of said surface is decreased, whereupon the surface becomes much smoother and allows the formation of a thin, continuous film of water thereon.
Paper machines for manufacturing soft paper with high bulk are known through a plurality of patent specifications. An imprinting fabric or felt is generally used which passes, together with the paper web formed, through a press nip in which the paper web is pressed into the imprinting fabric, thus acquiring a texture pattern on one side. Paper machines having such texturing fabrics and press nips are disclosed in U.S. Pat. Nos. 3,301,746, 3,537,954, 4,309,246, 4,533,437, 5,569,358, 5,591,305 and WO 91/16493. The drawback with the paper machines disclosed in these publications is that dewatering in the press nip is relatively low and the dry solids content of the paper web is therefore low when the paper is transferred to the drying cylinder. The production rate of the paper machine is thus relatively low.
U.S. Pat. No. 4,849,054 discloses a machine for manufacturing an imprinted fabric web with high bulk without the use of a press nip. A roll, e.g., a transfer roll or felt-carrying roll, forms a nip with an imprinting fabric at a transfer point for the web where the imprinting fabric passes around a suction tube with a slit opening facing the transfer point. The nip is so wide that the web is not compressed when it passes through. The suction effect from the suction tube via the narrow slit opening is sufficient to ensure that the web is not only transferred to the imprinting belt but is also shaped in compliance with the surface of the imprinting belt facing the web, this belt having a three-dimensional pattern. Prior to the transfer point the speed of the fabric web is greater than that of the imprinting fabric. The roll carrying the web to the non-compressing nip has a sm
Ampulski Robert S.
Klerelid Ingvar B.E.
Linden Anders T.
Ostendorf Ward W.
Polat Osman
Alston & Bird LLP
Metso Paper Karlstad AB
Walls Dionne A.
LandOfFree
Paper machine for and method of manufacturing textured soft... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Paper machine for and method of manufacturing textured soft..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Paper machine for and method of manufacturing textured soft... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3033355