Paper making and fiber liberation – Apparatus – Web creping or crinkling type
Reexamination Certificate
1998-05-18
2001-09-11
Fiorilla, Christopher A. (Department: 1731)
Paper making and fiber liberation
Apparatus
Web creping or crinkling type
C162S109000, C162S117000, C162S296000, C162S309000
Reexamination Certificate
active
06287425
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to processes and apparatuses for making strong, soft, absorbent fibrous webs. More particularly, the present invention is concerned with foreshortened fibrous webs.
BACKGROUND OF THE INVENTION
Fibrous structures, such as paper webs, are produced by a variety of processes. For example, paper webs may be produced according to commonly-assigned U.S. Pat. No. 5,556,509, issued Sept. 17, 1996 to Trokhan et al.; U.S. Pat. No. 5,580,423, issued Dec. 3, 1996 to Ampulski et al.; U.S. Pat. No. 5,609,725,issued Mar. 11, 1997 to Phan; U.S. Pat. No. 5,629,052, issued May 13, 1997 to Trokhan et al.; U.S. Pat. No. 5,637,194, issued Jun. 10, 1997 to Ampulski et al.; and U.S. Pat. No. 5,674,663, issued Oct. 7, 1997 to McFarland et al., the disclosures of which are incorporated herein by reference. Paper webs may also be made using through-air drying processes as described in commonly-assigned U.S. Pat. No. 4,514,345, issued Apr. 30, 1985 to Johnson et al.; U.S. Pat. No. 4,528,239, issued Jul. 9, 1985 to Trokhan; U.S. Pat. No. 4,529,480, issued Jul. 16, 1985 to Trokhan; U.S. Pat. No. 4,637,859, issued Jan. 20, 1987 to Trokhan; and U.S. Pat. No. 5,334,289, issued Aug. 2, 1994 to Trokhan et al. The disclosures of the foregoing patents are incorporated herein by reference.
Foreshortening of a fibrous web may be used to increase the web's caliper, absorbency and softness. Foreshortening refers to reduction in length of a dry web, resulting from application of energy to the web. Typically, during foreshortening, rearrangement of the fibers in the web occurs, accompanied by at least partial disruption of fiber-to-fiber bonds. As a result of foreshortening, micro-folds, commonly called “crepe” are formed in the web.
It has been discovered that the increase in caliper, or bulk, of the foreshortened web may further be achieved by relaxing, at least partially, the crepe in the web. It has been further found that the crepe can be relaxed in pre-selected portions of the web such that the rest of the web, not affected by the crepe relaxation, retains the quality of the foreshortened web.
Accordingly, it is a subject of the present invention to provide a novel process for increasing bulk of the foreshortened web by relaxing the web's crepe in the selected portions of the web. It is another object of the present invention to provide an apparatus for increasing bulk of the foreshortened web by relaxing the web's crepe in the selected portions of the web.
SUMMARY OF THE INVENTION
The present invention provides a process and an apparatus for 25 increasing caliper/bulk of a foreshortened fibrous web by causing selected micro-regions, or portions, of the foreshortened web to relax crepe therein, thereby expanding outwardly from the general plane of the web. The process comprises the steps of providing a foreshortened web comprising crepe and having a general plane; and adding moisture to the web or to at least the web's selected portions, thereby causing relaxation of the crepe in the selected portions and their expansion outwardly from the general plane of the web, while retaining the crepe in the rest of the web. The preferred apparatus comprises two mutually opposite surfaces designed to receive and restrain the foreshortened web therebetween, at least one of the surfaces having a plurality of fluid-permeable expansion conduits therethrough; a means for moistening the web or at least its selected portions corresponding to the expansion conduits when the foreshortened web is disposed between the two surfaces; and a means for creating a temperature differential between the two surfaces such that when the web is restrained between the surfaces, the temperature differential is sufficient to cause the moisture added to the web to move through the web in the direction from one surface toward the other, thereby relaxing crepe in the selected portions of the web and causing the selected portions to expand through the expansion conduits.
A first step of the process of the present invention comprises providing a foreshortened, and preferably fibrous, web. The term “foreshortened” web refers to a web which has been reduced in length, i.e., substantially proportionally contracted along its length, in a machine direction. The first step of providing a fibrous web may be preceded by the steps of forming such a web and then foreshortening the web. The fibrous web suitable for the present invention may be made by any papermaking process known in the art, including, but not limited to, a conventional process and a through-air drying process. The present invention also contemplates the use of the web that has been rewetted prior to being foreshortened. The foreshortened web is generally characterized by a plurality of micro-folds running across the web's length, which is known in the art as “crepe.” Foreshortening may be accomplished by any method known in the art, for example, by creping, by transferring the web from the first press surface to a slower-moving transfer fabric, or by the combination thereof.
Preferably, the foreshortened web is disposed on a working surface. The preferred working surface has a plurality of fluid-permeable expansion conduits therethrough. One preferred working surface is formed by a belt comprising a (preferably resinous) framework joined to a fluid-permeable reinforcing structure and protruding outwardly from the reinforcing structure, thereby forming the network area. The framework may comprise an essentially continuous and macroscopically monoplanar network area, in which case the plurality of expansion conduits preferably comprises a plurality of discrete orifices, or holes, which are dispersed throughout and encompassed by the continuous network area of the working surface. Alternatively or additionally, the work surface may comprise a plurality of discrete areas formed by discrete protrusions extending from the reinforcing structure, in which case an essentially continuous expansion conduit encompasses the plurality of discrete protrusions.
Preferably, the expansion conduits and/or protrusions are arranged in a pre-selected pattern, and more preferably, the pattern of the arrangement of the expansion conduits and/or protrusions is non-random and repeating. If the patterned working surface comprises discrete areas formed by the individual protrusions, the work surface's discrete areas may have the discrete expansion conduits therethrough, analogous to the discrete expansion conduits in the continuous work surface. The working surface may comprise a surface of a fluid-permeable platen or—in a preferred continuous process—a fluid-permeable endless belt or band capable of traveling in a machine direction.
The steps of disposing the foreshortened web on the working surface and moistening the web may be performed either sequentially or simultaneously. If the dry foreshortened web is being first disposed on the working surface, the moisture can subsequently be added to the web disposed on the working surface. Various means may be used for moistening the foreshortened web, such as, for example, spraying the web with water or penetrating the web by steam under pressure. A plurality of jets discharging water onto the selected portions of the web according to a pre-determined pattern may also be used. Preferably, the web, or its selected portions, is/are moistened to have a moisture content from about 95% to about 25%, i.e., the web's preferred fiber-consistency is from about 5% to about 75%. More preferably, the moisture content of the selected portions of the web, after they have been moistened, is from 85% to 35%, i.e., the web's more preferred fiber-consistency is from about 15% to about 65%.
The moisture may be added primarily to the selected portions of the foreshortened web, i.e., those portions which correspond to the expansion conduits of the working surface, and which are not in direct and immediate contact with the working surface. The moisture is added to the selected portions of the web prefera
Fiorilla Christopher A.
The Procter & Gamble & Company
Vladimir Vitenberg
LandOfFree
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