Textiles: weaving – Fabrics – Drier felts
Reexamination Certificate
1999-06-15
2001-05-29
Calvert, John J. (Department: 3741)
Textiles: weaving
Fabrics
Drier felts
C139S38300A
Reexamination Certificate
active
06237644
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to fabrics for use in making patterned paper (e.g., tissue, towel stock and other wet formed cellulosic sheets) or nonwoven materials, and which are especially suitable for use as forming wires, transfer fabrics and dryer fabrics, particularly through-air-dryer (TAD) fabrics in tissue making machines.
The fabrics are intended primarily for use in wet forming processes, but may also be used for dry forming methods, e.g., wherein fibers are air-laid onto the fabric. Reference throughout this application to “wet forming processes” or “wet forming apparatus” refers to a complete web forming process or apparatus, respectively, which may include the patterning, transferring, drying and creping of an initially laid slurry of fibers from a head box or other delivery device or system onto a forming wire.
The structure of the fabric may be used to form patterns in the wet or dry formed sheet by shaping the sheet and/or by influencing the density or thickness of fiber deposits in a controlled manner.
BACKGROUND ART
Kimberly-Clark publication WO-96/35018 describes the formation of patterns in a paper or tissue sheet using additional structures on the surface of a woven fabric. The imprint in this case is caused by providing systematically distributed areas of restricted drainage in the fabric. As disclosed in the publication, the drainage may be impeded by incorporation of additional filaments or fibers on top of or within the forming fabric weave pattern, or by a film or coating which blocks or fills void space within the fabric through which water could otherwise drain. Over the areas of impeded drainage, a thinner layer of relatively long fibers tends to be deposited, whilst shorter fibers migrate and are concentrated in the areas of more rapid drainage producing a thicker, less translucent tissue over the faster drainage areas.
Gusums Bruk AB Swedish Patent 427,053 discloses a forming fabric structure wherein areas of different density are created by providing relatively dense areas wherein there is a high frequency of yarn interweavings, and relatively porous regions wherein there is a low frequency of yarn interweavings, which are dominated by weft floats. In certain disclosed embodiments the areas of low frequency interweavings provide physically raised areas that shape the tissue.
Chiu U.S. Pat. No. 5,429,686 discloses a TAD fabric with a distinct load-bearing woven fabric layer and an additional sculpture layer formed by additional long-floated machine direction yarns, with the floats standing proud of the main body of the load-bearing fabric layer to shape the formed sheet.
OBJECTS OF THE INVENTION
It is a general object of this invention to provide forming fabrics, transfer fabrics or dryer fabrics, particularly TAD fabrics, for use in forming paper (e.g., tissue, towel stock and other wet formed cellulosic sheets) or nonwoven sheet materials having an improved embossed or patterned structure.
It is another object of this invention to provide forming fabrics, transfer fabrics or dryer fabrics, particularly TAD fabrics, for use especially in a tissue making machine to form improved embossed or patterned tissue products.
It is another object of this invention to employ a forming, transfer or dryer fabric in a web forming apparatus to form a patterned fibrous web having a desired balance of properties and a cloth-like appearance and texture.
It is another object of this invention to provide a web shaping or embossing woven fabric without the incorporation of additional filaments or other structures therein.
It is yet another object of this invention to provide a web shaping or embossing woven fabric without the need to employ additional processing steps to introduce additional elements into the woven fabric structure.
SUMMARY OF THE INVENTION
The above and other objects of this invention are achieved by fabrics employed as forming, transfer or dryer fabrics in web forming apparatus, said fabrics being employed in making embossed or patterned fibrous web products, such as paper (e.g., tissue, towel stock and other wet formed cellulosic sheets) or non wovens. The fabrics of this invention comprise both single and multi-layer woven structures.
In accordance with preferred embodiments of this invention, the fabrics include at least one layer of yarns oriented in both first and second directions, said yarns being woven to provide a lattice, said lattice defining marginal edges of adjacent systematically distributed surface areas, with the distribution pattern, configuration and dimensions of said adjacent surface areas being dictated by the pattern of the lattice. The systematically distributed surface areas, which can, but are not required to be of the same configuration, weave pattern and/or dimensions, preferably include at least three yarns oriented in each of said first and second directions, and more preferably include at least four yarns oriented in each of said first and second directions.
In accordance with certain aspects of this invention, each yarn that is in both the lattice and in one or more systematically distributed surface areas defined by the lattice has an interlacing density in the lattice that is less than or equal to the interlacing density of that yarn in the systematically distributed surface areas. In connection with these aspects of the invention, the lattice most preferably is, but is not required to be within the definition of “lattice” set forth hereinafter. Throughout this application, applicants, when they do not intend to be limited to the definition of “lattice” set forth hereinafter, will refer to “lattice arrangement.” However, the “lattice arrangement,” like the “lattice,” is required to define, or provide, marginal edges of adjacent systematically distributed surface areas.
In other aspects of this invention, wherein a yarn located in both the lattice and in one or more systematically distributed areas has an interlacing density in the lattice that is greater than the interlacing density in said one or more of the systematically distributed areas, the lattice must meet the definition of “lattice” set forth hereinafter.
The “lattice,” which is of a chain link-like construction, in addition to defining marginal edges of adjacent systematically distributed surface areas, unless more specifically limited, means a weave pattern in which, in the fabric surface adjacent the formed sheet (hereinafter referred to as “the forming surface”) more than 50% of the yarns defining the marginal edges of adjacent, systematically distributed areas have a zero interlacing density and wherein either all of the warp yarns or all of the weft yarns float over one, or continuously over more than one weft yarn or warp yarn, respectively, to form either a chain link-like array of warp floats or a chain link-like array of weft floats throughout the fabric on the forming surface; wherein when an array of warp floats is formed throughout the forming surface each warp float in the array either floats over the same weft yarn and/or over one or more adjacent weft yarns as adjacent warp floats in the array, and when an array of weft floats is formed throughout the forming surface each weft float in the array either floats over the same warp yarn and/or over one or more adjacent warp yarns as adjacent weft floats in the array.
More preferably, more than 75% of the yarns in the lattice that define the marginal edges of adjacent, systematically distributed areas have a zero interlacing density and most preferably 100% of such yarns have a zero interlacing density.
Reference to “zero interlacing density” in the lattice means that the warp or weft yarns that float over one or more weft yarns or warp yarns, respectively, remain on the forming surface and move out of the forming surface only at the perimeter of adjacent systematically distributed surface areas to define marginal edge segments of said areas.
Most preferably the lattice is “continuous” throughout the fabric, i.e., it defines the marginal edges of the systematically distributed
Brewster James Loy
Hay Stewart Lister
Herman Jeffrey Bruce
Strom Jan
Caesar Rivise Bernstein Cohen & Pokotilow Ltd.
Calvert John J.
Muromoto Jr. Robert H.
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