Paper making and fiber liberation – Processes and products – With printing and/or variegated coloring
Reexamination Certificate
2000-03-17
2002-10-15
Fortuna, Jose (Department: 1731)
Paper making and fiber liberation
Processes and products
With printing and/or variegated coloring
C162S109000, C162S116000, C428S218000, C428S219000
Reexamination Certificate
active
06464831
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to paper structures having a decorative pattern, and more particularly to such a paper structure having regions of different basis weight arranged in a predetermined, nonrandom pattern.
BACKGROUND OF THE INVENTION
Cellulosic fibrous structures, such as paper webs, are well known in the art. Such paper webs can be used for facial tissues, toilet tissue, paper towels, bibs, and napkins, each of which is in frequent use today. If these products are to perform their intended tasks and find wide acceptance, the fibrous structure should exhibit suitable properties in terms of absorbency, bulk, strength, and softness. Wet and Dry Tensile strengths are measures of the ability of a fibrous structure to retain its physical integrity during use. Absorbency is the property of the fibrous structure which allows it to retain contacted fluids. Both the absolute quantity of fluid and the rate at which the fibrous structure will absorb such fluid must be considered when evaluating one of the aforementioned consumer products. Further, such paper webs have been used in disposable absorbent articles such as sanitary napkins and diapers.
Attempts have been made in the art to provide paper having two different basis weights, or to otherwise rearrange fibers. Examples include U.S. Pat. No. 795,719 issued Jul. 25, 1905 to Motz; U.S. Pat. No. 3,025,585 issued Mar. 20, 1962 to Griswold; U.S. Pat. No. 3,034,180 issued May 15, 1962 to Greiner et al; U.S. Pat. No. 3,159,530 issued Dec. 1, 1964 to Heller et al; U.S. Pat. No. 3,549,742 issued Dec. 22, 1970 to Benz; and U.S. Pat. No. 3,322,617 issued May 30, 1967 to Osborne.
Separately, there is a desire to provide tissue products having both bulk and flexibility. Improved bulk and flexibility may be provided through bilaterally staggered compressed and uncompressed zones, as shown in U.S. Pat. No. 4,191,609 issued Mar. 4, 1980 to Trokhan, which patent is incorporated herein by reference.
Several attempts to provide an improved foraminous member for making such cellulosic fibrous structures are known, one of the most significant being illustrated in U.S. Pat. No. 4,514,345 issued Apr. 30, 1985 to Johnson et al., which patent is incorporated herein by reference.
Another approach to making tissue products more consumer preferred is to dry the paper structure to impart greater bulk, tensile strength, and burst strength to the tissue products. Examples of paper structures made in this manner are illustrated in U.S. Pat. No. 4,637,859 issued Jan. 20, 1987 to Trokhan, which patent is incorporated herein by reference. U.S. Pat. No. 4,637,859 shows discrete dome shaped protuberances dispersed throughout a continuous network, and is incorporated herein by reference. The continuous network can provide strength, while the relatively thicker domes can provide softness and absorbency.
One disadvantage of the papermaking method disclosed in U.S. Pat. No. 4,637,859 is that drying such a web can be relatively energy intensive and expensive, and typically involves the use of through air drying equipment. In addition, the papermaking method disclosed in U.S. Pat. No. 4,637,859 can be limited with respect to the speed at which the web can be finally dried on the Yankee dryer drum. This limitation is thought to be due, at least in part, to the pattern imparted to the web prior to transfer of the web to the Yankee drum. In particular, the discrete domes described in U.S. Pat. No. 4,637,859 may not be dried as efficiently on the Yankee surface as is the continuous network described in U.S. Pat. No. 4,637,859. Accordingly, for a given consistency level and basis weight, the speed at which the Yankee drum can be operated is limited.
Conventional tissue paper made by pressing a web with one or more press felts in a press nip can be made at relatively high speeds. The conventionally pressed paper, once dried, can then be embossed to pattern the web, and to increase the macro-caliper of the web. For example, embossed patterns formed in tissue paper products after the tissue paper products have been dried are common.
However, embossing processes typically impart a particular aesthetic appearance to the paper structure at the expense of other properties of the structure. In particular, embossing a dried paper web disrupts bonds between fibers in the cellulosic structure. This disruption occurs because the bonds are formed and set upon drying of the embryonic fibrous slurry. After drying the paper structure, moving fibers normal to the plane of the paper structure by embossing breaks fiber to fiber bonds. Breaking bonds results in reduced tensile strength of the dried paper web. In addition, embossing is typically done after creping of the dried paper web from the drying drum. Embossing after creping can disrupt the creping pattern imparted to the web. For instance, embossing can eliminate the creping pattern in some portions of the web by compacting or stretching the creping pattern. Such a result is undesirable because the creping pattern improves the softness and flexibility of the dried web.
PCT Publication WO 96/35018 discloses a paper sheet having a decorative pattern corresponding to areas having a translucent appearance corresponding to a relatively lower basis weight. It is believed that one problem associated with such paper is that tissue paper webs with translucent areas can be considered unfavorable by consumers. For instance, consumers can perceive such low basis weight regions as indicating weakness and/or lack of softness. Further, an excessive amount of low basis weight area can reduce the strength of the paper, making it unsuitable for the task the paper web is intended to perform.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it would be desirable to overcome such problems, and particularly to overcome such problems as they relate to a single lamina of paper. Specifically, it would be desirable to provide a non-through air dried paper web having a decorative pattern without compromising the strength, absorbency, and softness characteristics of the paper web. It would also be desirable to provide a paper web having a non-embossed decorative pattern without requiring translucent areas, as well as such a paper web having a multi-region background, as well as providing a method for forming such a paper web on a conventional, non-through air dry paper without the need for substantial modification of the papermaking machine.
The present invention provides a paper web having a first surface and an oppositely facing second surface. The paper web has a background portion and a non-embossed decorative pattern. The decorative pattern includes at least one high basis weight region having a basis weight which is greater than the average basis weight of the surrounding background portion.
The decorative pattern can comprise one or more low basis weight regions. The relatively low basis weight regions have a basis weight less than the average basis weight of the surrounding background portion, and the low basis weight regions can substantially circumscribe one or more high basis weight regions. At least some of the low basis weight regions can be disposed intermediate the background portion and the high basis weight regions, and at least some of the low basis weight regions can separate adjacent high basis weight regions. By substantially circumscribing one or more high basis weight regions, the low basis weight regions help to accentuate the visual appearance of the decorative indicia.
The term “decorative pattern” as used herein refers to a recognizable shape or shapes imparted to the web, preferably during initial formation of the web. Such shapes include, but are not limited to, floral shapes, animal shapes, geometric shapes, and the like.
The background portion preferably comprises at least 50 percent of the surface area of the first surface of the paper web, and in one embodiment the background portion comprises at least 70 percent of the first surface of the paper web.
In one embodiment, the decorative pattern can comprise le
Deason Howard Thomas
Kleinwächter Jörg
Phan Dean Van
Trokhan Paul Dennis
Bullock Roddy M.
Fortuna Jose
Huston Larry L.
Mattheis David K.
The Procter & Gamble & Company
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