Textiles: spinning – twisting – and twining – Strand structure – Staple fiber blends
Reexamination Certificate
2001-01-11
2002-11-12
Calvert, John J. (Department: 3765)
Textiles: spinning, twisting, and twining
Strand structure
Staple fiber blends
Reexamination Certificate
active
06477826
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to open end spinning and, more particularly, to an apparatus and method for economically producing a cotton/rayon blended yarn, which provides an improved hand and drape in knitted fabrics and articles of apparel sewn therefrom, particularly after washing the article of apparel.
(2) Description of the Prior Art
Many fabrics for articles of apparel, such as Tee-shirts, are made of 100% ring spun cotton yarn. Ring spun yarn when knitted into fabric produces a relatively soft fabric with a good “hand,” which is highly desirable from a consumer point of view. The soft hand associated with fabric made from ring spun yarn is the result of the relative “hairiness” of the surface of ring spun yarn. Upon magnification, it can be seen that ring spun yarn has fibers that protrude from the yarn surface. These protruding fibers are the result of the “fibrillation” of the yarn, that is, after the fibers are spun into yarn, some fibers, particularly at the surface, break apart and the broken ends protrude from the surface of the fiber. These protruding ends give fabric knit from ring spun yarn a softer hand.
Another widely used spinning process is open end spinning. Open end spun yarn, is significantly less expensive to produce than yarn produced via a ring spinning process. This is because the ring spinning process takes substantially more time to produce the same amount of yarn as the open end rotor spinning process. A significant disadvantage associated with fabric knitted from open end spun yarn is that the fabric has a harsher hand than fabric knitted from ring spun yarn. This is because there is less fibrillation associated with open end rotor yarn.
A significant economic market exists for articles of apparel, such as Tee-shirts, that are printed with images and/or embellished with decorative designs. There are problems, however, associated with printing or embellishing apparel made from ring spun cotton yarn. As a result of fibrillation, which contributes to the softness of fabric made from ring spun yarn, printed images tend to appear less bright and vivid because of the protrusion of fibers through the printed image over time due to washing and wear. For example, the color black printed on a white Tee-shirt may appear gray in color over time because of the fibrillation of the white fibers and their protrusion through the black portion of the printed image.
Cotton is a fiber that is commonly used to produce ring or open end spun yarn from which fabric is knit and articles of apparel, such as Tee-shirts, are made. Fabric knitted from 100% cotton yarn has the desirable characteristic of being made from all natural fibers, as opposed to synthetic fibers, such as polyester, which is desirable from a consumer point of view. Another advantage of cotton is that it is a relatively inexpensive fiber.
Rayon is a fiber well known in the textile industry and is used widely in the manufacture of apparel. Rayon is a man made fiber that is produced by forcing a cellulose solution that is made from wood pulp through fine spinnerets and solidifying the resulting filaments. The filament can be cut into staples and then spun into yarn using conventional ring or open end rotor spinning techniques. However, rayon is not usually used in manufacturing Tee-shirts and similar articles of apparel because it is relatively higher in cost than cotton. In addition, fabric knitted from 100% rayon yarn appears to have a slick, shiny, synthetic look, which is undesirable to some consumers.
Thus, there remains a need for a yarn made of natural fibers that can be economically produced using conventional open end rotor spinning while, at the same time, has a good soft hand and drape, particularly after washing, that is comparable to ring spun 100% cotton and that minimizes undesirable fibrillation inherent in ring spun.
SUMMARY OF THE INVENTION
The present invention is directed to an apparatus for forming a cotton/rayon blended yarn. The apparatus includes a supply of cotton fibers and a supply of rayon fibers. A blending operation line blends the cotton fibers and the rayon fibers. The fibers are then spun in an open end spinning turbine having a twist multiple of less than about 3.7 at a rotor speed of less than about 112,000 RPM. A roughing navel downstream from the open end spinning turbine distresses the surface of the cotton/rayon blended yarn to further improve the hand of yarn. The yarn is then knitted and the fabric finished.
In the preferred embodiment, the finishing of the fabric includes a finishing range for applying a finishing mix composition to the fabric. The finishing mix composition includes a cationic polyethylene softener mixed with a silicone finish. The finishing range applies a wet pickup of the finishing mix composition of about 20 wt. % and between about 1½ and 3 wt. % solids. A dryer for drying the fabric is downstream from the finishing range. The fabric is then taken up and subsequently cut and sewn into articles of apparel, such as Tee-shirts.
In the preferred embodiment, the staple length of the cotton fibers is between about ¾ and 1½ inches with about 1¼ inches being preferred. Preferably, the Micronaire value of the cotton fiber is less than about 4.
In the preferred embodiment, the staple length of the rayon fibers is also between about ¾ and 1½ inches with about 1¼ inches being preferred. The denier of the rayon fibers is less than about 1 with about 0.9 being preferred.
The blending operation line includes a blending feeder, a carding station, and a drawing station. The blending feeder combines the cotton fibers and the rayon fibers at a ratio of less than about 50% rayon with a ratio of cotton/rayon fibers of about 75/25 being preferred.
In the preferred embodiment, the twist multiple is about 3.2 and the rotor speed of the open end spinning turbine is between about 60,000 and 95,000 RPM with a rotor speed of the open end spinning turbine of about 95,000 RPM being preferred.
Yarn spun according to the present invention from a blend of cotton and rayon can be knitted or woven into fabric, and the resulting fabric, and apparel made therefrom, has the advantage of having a particularly soft and luxurious hand, particularly compared to fabric knit from 100% cotton yarn. Fabric knitted from the cotton/rayon blend of the present invention also has the advantage of retaining its softness and hand after washing. Cotton, in contrast, tends to become stiff and “board-like” after washing.
Yet another advantage associated with the fabric made from the yarn of the present invention is the improved drape of the fabric. Drape is a property associated with the aesthetic appearance of garments and other textile structures. Drape is the deformation of the fabric produced by gravity when only part of the garment or textile structure is directly supported. The drape of fabric made with the blend of cotton and rayon yarn of the present invention is better than fabric made of 100% cotton yarn, particularly after washing.
Accordingly, one aspect of the present invention is to provide an apparatus for forming a cotton/rayon blended yarn. The apparatus includes: a supply of cotton fibers; a supply of rayon fibers; a blending operation line for blending the cotton fibers and the rayon fibers; and an open end spinning turbine, wherein the open end spinning turbine uses a twist multiple of less than about 3.7 at a rotor speed of less than about 112,000 RPM.
Another aspect of the present invention is to provide an apparatus for forming a cotton/rayon blended yarn. The apparatus includes: an open end spinning turbine having a twist multiple of less than about 3.7 at a rotor speed of less than about 112,000 RPM; and a roughing navel downstream from the open and spinning turbine for distressing the surface of the cotton/rayon blended yarn.
Still another aspect of the present invention is to provide an apparatus for forming a cotton/rayon blended yarn. The apparatus includ
Calvert John J.
Hurley Shaun R
Sara Lee Corporation
Womble Carlyle Sandridge & Rice PLLC
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