Textiles: weaving – Fabrics – Materials
Reexamination Certificate
2001-10-26
2003-12-23
Vanatta, A. (Department: 3765)
Textiles: weaving
Fabrics
Materials
C002S002500, C442S203000, C139S42000D
Reexamination Certificate
active
06666235
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a lightweight and durable high-performance denim fabric. More particularly, the present invention relates to a lightweight durable denim comprising at least one high-performance high strength fiber and a natural fiber component, wherein these are used to ultimately construct a fabric having at least a 15% lighter weight and at least a 15% higher durability than standard denim.
BACKGROUND OF THE INVENTION
Denim fabrics are well known and typical commercially available denim varies according to its particular application, such as its use in various types of garments or apparel. However, typical commercially available denim does not possess the requisite properties allowing it to be comfortably worn on a daily basis while retaining sufficient tear and breaking strength.
With regard to denim or any given fabric, comfort is generally dependent upon three variables, namely, fiber type, fabric weight and fabric construction, while fabric strength or durability can be described by tear strength and breaking strength, both of which are vital for denim fabric that undergoes daily use. Proper balancing of these variables is critical. Attempts to manufacture lightweight cotton denim have proven unsuccessful because the lighter weight was obtained by utilizing a thinner or lighter fabric made from cotton having a loose weave. The desirable properties such as durability and strength were compromised, thereby resulting in a less wearable garment because the material would prematurely deteriorate or disintegrate due to daily use and/or laundering. Fabrics constructed having a looser weave, allow for greater moisture transport as well as flexibility, however such fabrics result in poor performance and lower strength.
Generally, it is well known in the art that the enhancement of properties of a denim fabric can occur by including aramid fibers in the fabric. For example Kevlar®, an aramid fiber, is a high modulus fiber that is known for its high strength, but is also well known to be an uncomfortable fabric component to use for garments or apparel due to its stiffness.
Fabrics consisting of cotton and/or synthetic fibers are known in the art, as described by U.S. Pat. Nos. 4,900,613 (Green), 5,223,334 (Green), 4,941,884 (Green), 5,077,126 (Green), 5,918,319 (Baxter) and 5,628,172 (Kolmes et al.).
Industrial fabrics containing Kevlar® are described in U.S. Pat. No. 5,025,537 (Green), which discloses denim fabric containing a high shrinkage staple fiber. However, the Greene patent discloses fabric having a very high tightness factor and is directed towards industrial protective apparel rather than casual garments or fabrics designed for daily use. Such industrial clothing lacks the comfort necessary for conventional attire.
In a prior publication, namely U.S. Pat. No. 5,625,537 (Green), it is known to manufacture a denim twill employing cotton, poly(p-phenylene terephthalate) (PPD-T) and nylon as shown in Example 1 of that patent. However the example is directed to a fabric which lies outside the scope of the present invention, e.g., the PPD-T is only present in the warp direction.
There is a need within the industry to provide a fabric having a high degree of strength and a high level of performance in order to address the demands required for daily use, while also retaining the necessary amount of comfort and the present invention fulfills this industry need. The present invention incorporates the strength of the high strength fiber into a fabric, without compromising the original comfort of the fabric itself. Still further, the present invention addresses those problems in manufacturing processes that improperly incorporate the fibers or yarn into the fabric, which deny the fabric the proper levels of durability, strength and comfort.
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a durable denim fabric comprising a yarn having an intimate blend of cotton and high strength fibers or comprising a yarn having a sheath/core configuration comprising a natural fiber, preferably cotton, sheath and a high strength fiber core. The fabric or yarn comprises at most about 30% of a high strength fiber and a corresponding portion of a natural fiber.
More particularly, the present invention relates to a denim fabric suitable for leisure wear comprising:
(a) warp yarns comprising:
(i) 75 to 98 parts by weight of a natural fiber, preferably cotton, and
(ii) 2 to 25 parts by weight of a high strength fiber, preferably a para-aramid, and
(b) fill yarns comprising
(i) 75 to 98 parts by weight of a natural fiber, preferably cotton, and
(ii) 2 to 25 parts by weight of a high strength fiber, preferably a para-aramid, wherein the fabric has at least a 15% lighter weight and at least a 15% higher tear strength and at least a 15% higher breaking strength than standard denim, however a fabric having at least a 20% lighter weight, at least a 20% higher tear strength and at least a 20% higher breaking strength is preferred.
The present invention may optionally further include about 1-5% by weight of a conductive fiber or filament wherein the conductive fiber or filament comprises carbon black or its equivalent dispersed within it, which provides the anti-static conductance to the fiber.
The present invention relates to articles of clothing made from yarns comprising natural fibers and high strength fibers, such that the high strength fiber is in both the warp and fill directions, wherein the articles of clothing include pants, shirts, jackets and the like.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides several advantages over other currently manufactured denims. Due to its construction, the present invention allows for the retention of the desirable properties of denim while also providing a lightweight garment for daily use as well as other applications. Another advantage conferred by the present invention is its versatility. The present invention, due to properties such as drape ability, allows clothing designers as well as other fabric consumers (e.g. the public) and/or designers (e.g. furniture designers or interior decorators) greater versatility where the denim may be used in a manner to which the designers and consumers were previously unaccustomed because of its heavier weight.
The present invention relates to a fabric having a looser weave, which along with a lower weight, provides a high degree of comfort and increased levels of tear and breaking strength, which are attributes not seen in the art. The fabrics of the present invention may be knitted, woven or the like.
The fibers of the present invention can be spun staple yarns produced by a number of different spinning methods that are well known within the art, including but not limited to, ring spinning, open end spinning, air jet spinning and friction spinning.
The term “lightweight denim fabric”, as used herein, for example with regard to pants refers to a denim fabric that is up to approximately 11 ounces per square yard (373 grams per square meter) when compared to standard natural denim in the range of 13.5-15 ounces per square yard (460-510 grams per square meter), however, since different types of garments such as shirts employ denims of different weights, “lightweight denim fabric” also refers to denim fabric article that is at least 15% lighter than a similar article made from standard natural denim in the range of 6-8 ounces per square yard (200-270 grams per square meter).
As used herein, the term “high strength fibers” means fibers having a tenacity of at least 10 grams per dtex and a tensile modulus of at least 150 grams per dtex.
By “aramid” is meant a polyamide wherein at least 85% of the amide (—CO—NH—) linkages are attached directly to two aromatic rings. Examples of aramid fibers are described in Man-Made Fibers—Science and Technology, Volume 2, Section titled Fiber-Forming Aromatic Polyamides, page 297, W. Black et al., Interscience Publishers, 1968. Aramid fibers are, also, disclosed in U.S. Pat. Nos. 4,172,938; 3,869,429; 3,819,587; 3,673,143
Chi Cheng-Hang
Prickett Larry John
E. I. du Pont de Nemours and Company
Muromoto Jr. Robert H.
Vanatta A.
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