WO2006071688A2

WO2006071688A2 - Yarns spun from olefin and cotton fibers and products made therefrom

Info

Publication number: WO2006071688A2
Application number: PCT/US2005/046416
Authority: WO
Inventors: Edward J. Negola
Original assignee: Negola Edward J
Priority date: 2004-12-23
Filing date: 2005-12-20
Publication date: 2006-07-06
Also published as: WO2006071688A3; US20060150610A1

Abstract

A textile yarn consisting of a blend lightweight olefin fibers that has a specific gravity of .91 to 1.0 blended with cotton fibers that have a specific gravity of more that 1.0 made using commercially available cotton spinning systems, and the textile articles manufactured using said yarn. This invention takes advantage of the fact that during the spinning process, centrifugal force slings most of the heavier cotton fiber to the outside while the lighter weight olefin remains mostly in the core of the yarn thus formed. The system is especially useful when using cotton open end or air jet spinning systems. Novel fabrics can be made from the new yarns.

Description

YARNSSPUN FROMOLEFINANDCOTTON FIBERS ANDPRODUCTSMADETHEREFROM

Related Applications: This application is based on and claims priority of provisional application

No. 60/638,525, filed December 23, 2004.

Background of the Invention:

Cotton fiber has been the predominant choice of textile fibers through the ages. When used to make yarn, cotton fiber is versatile enough to be used in almost any type of knitted or woven cloth or fabric. It is soft to the touch, and comfortable to wear. Cotton absorbs moisture and is easily washed. Blue Jeans, pants and "T" shirts are the most common articles made using cotton yam. Cotton yarn is produced in most parts of the world and is consumed as apparel in almost every country in the world. In recent years as shortages of cotton started to occur, cotton fiber has been successfully blended with polyester fibers to make yarn. This yarn is a good substitute for 100% cotton yarn and is used extensively world wide to make textile articles. Cotton fiber and polyester fiber have the same relative specific gravity (1.38) and therefore blend into a uniform yarn. A blend of cotton fibers and polyester fibers is made into yarn using commercially available spinning equipment such as ring spun, open end and air jet texturing.

Cotton yarn is produced by various spinning methods. Ring spinning, open-end spinning and air jet spinning are the most common methods. The spinner receives the cotton fiber in bale form. The bales contain cotton staple fiber. The staple fiber is baled according to size. Sizes of staple length are available in lengths of 3/4" up to 1-1M6 "in length. Longer staple lengths of cotton fibers are the most desirable and are used to make the most expensive cotton yarn. Long staple length cotton fiber is only available in limited quantities and is more expensive than the shorter length cotton fibers. Cotton yarn that is comprised of long staple length fibers is the strongest yam and it is used to make fine luxurious fabric. Longer length cotton staple fiber is usually referred to as "pima" or "Egyptian" cotton. Extensive information is available from the Cotton Council. This organization keeps a running list of various cotton fibers by name and price. The cotton council maintains a non-profit corporation, called Cotton Inc., that is supported by the worldwide growers of cotton. Cotton Inc. is well known to one skilled in the art. Its purpose is to promote fabrics using predominantly cotton yarns.

The manufacturer or spinner of cotton yarn often blends a polyester synthetic staple fiber having a denier per filament of 2 or less and a length of 1.5" to 2" with the short less expensive cotton staple fiber to achieve a yarn that is similar to an expensive long staple length cotton yarn. Because polyester staple fiber is available in unlimited quantities and is usually less expensive than the long staple length cotton fiber, the yam made using this blend is less expensive than a yam made using 100% long staple length cotton yarn. The result is pleasing and the yarn almost feels like it was made using 100% cotton fibers. This blended yarn is made using the same commercially available equipment required to make 100% cotton yarn. In addition to long staple length yarn polyester is blended with all lengths of cotton fibers to create a common blend of polyester/cotton yarn.

In addition to saving money in the manufacture of 100% cotton yarn, the spinner has unlimited quantities of short length cotton staple fibers available.

When combined with an unlimited supply of long length staple polyester fibers the blended yarn is acceptable to the textile trade. The cotton fibers and the polyester fibers have similar specific gravity and therefore when spun, create a yarn that is intimately blended when manufactured on any of the common cotton systems used to spin yarn. The finished yarn looks and feels almost like a long staple length cotton yarn. While the blend of polyester fibers and cotton fibers is generally acceptable, the yarn is not generally used to make Indigo dyed Blue Jeans. This blended yarn feels too harsh. In addition, only the cotton portion accepts Indigo Blue dye, which is the preferred color of "blue jeans". This is the dye that will fade over many types of washing and has become the worldwide hallmark of denim fabric used to make the jeans. Blue Jeans is the most widely used pants in the world. Many versions of blue jeans are manufactured and are usually made from 100% cotton yarn. Other Denim textile articles made using the same indigo dyed cloth include Jackets, Vests, Hand Bags and Pillows. In addition, the denim weave is used to make non-indigo fabrics used for the same purpose. These products are either solid dyed using conventional cotton dyes or printed to make novel wearing apparel.

While many attempts have be made to make a yarn that would feel just like 100% cotton yarn using the blend of cotton and polyester staple fibers, the blended yarn falls short of feeling like 100% cotton yarn. This is due to the fact that the specific gravity of the two fibers is so similar, that they become intimately blended during the spinning process. When textile articles are handled, one can feel the polyester fiber portion as well as the cotton fibers. Polyester does not absorb as much moisture as does the cotton and feels dry to the touch. Also,

Polyester does not absorb any indigo or cotton dye and remains colorless when the jeans or other textile articles are dyed using cotton dyes or indigo dyes.

It is desirable to make a yarn that looks and feels just like cotton using a blend of synthetic fibers and cotton fibers. This enables the one skilled in the art to use readily available short length cotton fibers efficiently in many ways. Short length cotton fibers of % inch are available to spinners of cotton yarn in most parts of the world. Having a suitable synthetic fiber to easily blend with short length cotton fibers is very desirable as the yarn spun using the cotton system is strong and enough to knit or weave into almost any type to textile fabric. Dyeing and finishing: A drawback in dyeing and finishing exists using a yarn made from an intimate blend of cotton fibers and polyester fibers. The dyer has to prepare two separate formulas to dye the fabric. The dyer first dyes the polyester portion of the fabric using the high temperature polyester dye method. The polyester dye bath is drained and a new cotton dye bath is introduced into the same dye machine to dye the cotton content of the fabric. This is a two-step process and is well known by one skilled in the art. Since it is a two-step process and uses two different dye methods, the process is more time consuming and expensive than using a one step cotton dye process. The dyer usually has to dye the cotton and the polyester to the same shade using different dye methods. In addition to being expensive, dyeing uniform shades is difficult and requires great skill. Unfortunately the finished fabric while acceptable still does not feel like 100% cotton. This is due to the fact that the blend is an intimate blend of polyester fibers and cotton fibers that have the same relative specific gravity. The polyester fiber feels harsher than cotton due to the fact that is does not hold moisture when dry.

It is desirable to produce a yarn using the commercially available cotton spinning system that will look and feel like 100% cotton. It is a great advantage to the dyer if the yarn can be used to create fabrics that would dye in one dye bath. It is also desirable to achieve the colors using commercially available cotton dye systems. The fabric could then be dyed worldwide by anyone skilled in the art of dyeing cotton.

Description of Preferred Embodiments of the Invention:

Using a blend of cotton fibers with a specific gravity of 1.35+ and olefin staple fibers with a specific gravity of .91 to 1.0 is ideal to create a yarn that looks and feels like 100% cotton yarn when produced using any of the common cotton spinning systems such as ring, open end or air jet spinning. Open end or air jet spinning is preferred because it is less expensive to make yarn using these systems and creates a yarn using air pressure to blend the fibers. While this is a preferred method making yarn that uses the blend of the invention, ring spinning will also produce satisfactory cotton-like yarn.

A surprising effect is achieved because during the spinning process of a blend of cotton fibers and olefin fibers, centrifugal force slings the heavier cotton staple fibers to the outside of the yarn being formed. When yarn is made using the air jet spinning process air pressure is usually 100 psi mingling and spinning the fibers together. During this process the heavier fiber migrates to the outside of the core portion of the yarn. This effect creates a yarn that has a covering of mostly cotton fiber that completely wraps around a core of olefin fiber. A blend using 25% to 80% cotton fibers and 75% to 20% olefin fibers is desirable to create the effect. The use of more of the cotton fiber creates a yam that feels and dyes mostly like 100% cotton.

This is due to the fact that the cotton fiber has a much higher specific gravity than the olefin fiber. Cotton has a specific gravity of 1.38 while olefin has a specific gravity of .91 to 1.0. It is this difference in specific gravity that the invention uses to make a unique and novel yarn. When textile articles are made using the yarn of this invention the "hand" feels just like 100% cotton due to the fact that most of the outer portion of the yarn is cotton.

Yarn comprised of a blend of between 25%to 80%cotton fibers with 75% to 20% olefin fibers can be spun into yarn using the cotton spinning system. I found a preferred blend to be 60% cotton fibers blended with 40% olefin fibers. This blend of fibers makes a yarn that feels like 100% cotton and also qualifies the yarn to receive promotional efforts of the cotton council. It is important when spinning the fibers into yarn that the staple length of each component be kept in the same range of lengths. Cotton fibers averaging ³A " to 1.16" in length should be blended with olefin fibers of no more than 1.5" staple length.

The olefin preferably used in this invention is polypropylene. However, any olefin fiber is suitable, as long as the fiber dpf and the specific gravity remain within the ranges of the invention. Using 60% cotton fibers in the blend results in most of the olefin fibers being located predominantly in the core of the spun yarn.

It is preferred to use a 1.5-inch staple length olefin fiber to blend with ³A to 1 1/16" length of cotton. When 1.5" staple length of olefin is used, the yarn is strong and allows most of the cotton fiber to form on the outside of the core of yarn structure.

It should be noted that the yarn is limited to sizes up through 40/1 cotton count.

Finer yarns are difficult to make using the procedures of this invention because spinning speed has to be slowed to uneconomical levels.

When yarn is made comprising a blend of cotton and olefin fibers, the blended yarn looks and feels like 100% cotton. The specific gravity of a yam made with a 60% blend of cotton fibers and a 40% blend of olefin fibers is 1.15. The specific gravity of the yarn creates a pleasing soft feel or hand. While this blend is the preferred blend one skilled in the art could use less or more cotton in the blend to achieve satisfactory cotton like "hand". It is important to note that when 60% cotton fibers is used, Cotton Inc. will certify the yarn and allow its official cotton blend symbol to be used to help sell the fabric. Also, all the chemistry developed to enhance the cotton, such as stain defenders, mercerizing, shrinking etc. work very well when this blend is used.

Bulky Coverage: Fabrics made using cotton-olefin yarn according to the invention feel as soft as cotton when the dpf of the synthetic is close to that of cotton. A further and surprising advantage of the yarn thus made is the fact that the olefin always bulks more than cotton and creates a thicker-feeling fabric than fabrics made of 100% cotton. A good rule of thumb would be to use a yarn that is 10% smaller in size than one skilled in the art would normally use to make a fabric. When the fabric is dyed, the yarn will bulk to the size originally intended. Fabrics made using the yarn of the invention can contain less yarn because of the fact of bulking more in weaving or knitting, and it will cost less to produce a similar fabric that is made from 100% cotton. The reason less yarn can be used in the manufacture of the textile fabrics is the fact that core of predominantly olefin fiber swells or bulks and provides better coverage. This will be well understood by those skilled in the art. It is expected that at least 10% less yarn can be used to make a given fabric, as compared to those made using 100% cotton or 100% blend of cotton polyester.

Dying and Finishing: Due to the surprising effect of the blend, yarns made according to the invention have mostly cotton fiber on the outside. The dyer thus can prepare a cotton dye bath to achieve a pleasing shade using just one dye method. While the olefin in the core remains undyed, it is barely detectable to the human eye. Only the color of the dyed cotton is predominant. This results in a further savings due to the fact that the dyer can achieve a shade in less time using less energy, water and dyestuffs than if he were dyeing 100% cotton fabric or a blend of cotton and polyester fabric. Less dyestuff and chemical is used because only the cotton component (e.g., 60%) of the yarn will absorb the cotton dyestuff. Nevertheless, the color coverage is such that when examining the fabric the human eye does not perceive that the uncolored olefin core is present. Textile garments and especially jackets, pants and "T" shirts of any shade can be manufactured using fabric having a yarn made according to this invention. The fabric is woven or knitted into greige goods and is then dyed to order according to the color required by the customer.

The yarn of this invention is especially advantageous in the denim weaving process. Fabric produced using this yarn can easily be indigo dyed to create the more popular shades of "blue" used in the manufacture of blue jeans. The added benefit of dye cost savings becomes apparent when using indigo dye systems as 40% less dye will be needed when using the preferred 60/40 blend of cotton and olefin. This will results in great savings in dye cost to the producer. Savings in energy also result because time to dry the fabric is significantly reduced by the presence of the olefin component. Any special effect such as stone washing or bleaching effects, commonly used when finishing blue jeans, will be just as effective using denim fabrics made using the yarn of this invention.

Novel Dyeing Effects: Another interesting and advantageous use of the yarn of this invention is to create multiple colors using one dye bath. This is achieved by using two or even three yarns blended with varying amounts of cotton fibers in relation to the olefin fibers. A yarn that has a blend of 25% cotton fiber portion, knitted with a yarn that has a blend of 60% cotton fiber portion, will dye lighter in shade than the one containing more cotton when immersed in the same cotton dye bath. One skilled in the art will use this characteristic to advantage when creating desirable fabrics combining multiple shades. Twisting single ends of varying blends also creates a pleasing two or three tone effect.

Savings When Using Additives: During the dyeing process many types of additives such as softeners, optical brighteners, and stain resistant finishes are currently being applied when processing cotton textile fabrics. A great savings is achieved using this invention because additives, commonly used to treat cotton fabrics, are effective using 40-50% less of the costly chemical additives, as only the cotton portion of the yarn has to be treated.

An especially pleasing and money-saving effect is achieved when white cotton cloth, with softener and optical brighter in the finish, is desired. The cloth is usually run through a chlorinated bath with a detergent, softener and an optical brightener. This cloth is commonly used to make white "T" shirts which accounts for over 50% of the use of white cotton knit fabric. A savings of 40-50% in chemicals and additives can be achieved, as well as the savings at drying and finishing. The resultant "T" shirt looks and feels like it was made using 100% cotton yarn. The same bleaching process will be used to make white twill or woven textile garments such as jackets or slacks. Also, a white fabric used to create a novel fabric base for printing is created in this manner. Printed fabrics using the aqueous cotton dye system are less expensive to produce as only the cotton portion of the fabric will accept the dye.

Blue Jeans: Typical Denim Dye Technique: Fabric dyeing of denim is a relatively new technique. The yarn of this invention can also be indigo dyed using the conventional indigo dye system. Indigo dye is typically applied to a warp of 100% cotton rope. Using this invention, the rope is made using yarn made using a blend of cotton fibers and olefin fibers. A preferred blend is 60% cotton blended with 40% olefin.

The Indigo:

Vat dye is reduced and the rope yarn goes through a series of applications or dips. The rope is submerged at least four times by dipping into reduced vat indigo dye tanks one at a time. Each time the rope is lifted out of a dip (called skying), oxygen turns the color of the reduced dye to a shade of blue. Each subsequent dip on the rope warp makes the shade deeper after the vat dye is exposed to oxygen in the air.

Indigo dye adheres the outside surface of the rope and can be rubbed off.

It is also chlorine sensitive. The rope is dyed and dried. It is then re-beamed, separating each strand of yarn. The beamed yarn is fed to a weaving machine to create a typical twill denim indigo blue fabric. The fill yam is left undyed. Indigo Dyeing Woven Fabric: One of the largest single uses of woven cotton fabric is in the production of blue jeans. Denim fabric is made by weaving using the warp portion of the fabric up. The denim fabric is then exposed to the indigo dye system. The same system used to indigo dye rope can be modified to dye woven fabric. The yarn of this invention is especially advantageous to use in the denim weaving process. Fabric produced using this yarn can easily be indigo dyed to create the more popular "blue" used when manufacturing blue jeans.

Only the cotton portion of the blended yarn in the denim fabric will accept the indigo dye. This makes it economical to dye because only the cotton component (e.g., 60%) of the yarn used to manufacture the blue jean fabric is exposed. The added benefit of dye cost savings becomes apparent when using indigo dye systems. Less dye will be used, affecting a great savings in dye cost to the producer. Savings in energy used to dry the fabric result because time to dry the fabric is reduced significantly because the olefin component does not absorb moisture.

Denim made with yarns of the invention look and feel like denim made using 100% cotton yarn. Any special effect such as stone washing or bleaching effects commonly used when finishing blue jeans will be as effective when using denim fabrics made using the yarn of this invention. Also, the indigo dyed denim will fade with multiple washings which is very desirable to the users of blue jeans.

Shrinkage: Another surprising effect that is achieved using the cotton /olefin blend yarn of the invention is the reduction in shrinkage after finishing. The bulky nature of the olefin allows good coverage in the fabric, and once dyed and finished, the fabric has had most of the shrink potential removed and is very stable. It shrinks 40% less than fabric made using 100% cotton and is easier to cut and sew. The fabric width is stable after dyeing and finishing. This fact creates a significant advantage when the fabric is cut for sewing, as each piece is essentially identical to the other making uniform sewing is more economical.

Moisture Absorption-Comfort Wear: Fabrics knitted and woven using the preferred (i.e., 60/40 blend) yarn of the invention will absorb 40% less moisture than fabrics made using 100% cotton yarn. The fabrics will dry 40-50% faster than fabrics made using 100% cotton yam, resulting in energy savings used to dry the fabric. Olefin fiber is unique, because it will not absorb any moisture.

The cotton portion of the blended yarn will quickly wick moisture from the body allowing the moisture to evaporate 40-50% faster than fabric made using 100% cotton. This makes the fabric more comfortable to wear and reduces the

"clammy" feeling of perspiration when wearing fabrics made using 100% cotton.

Knit Stretch: Another surprising result of the new yarn is that knit fabrics made therefrom have more "stretch" than fabrics knit using 100% cotton or 100% cotton polyester. Using yarn of the invention containing at least 40% or more of olefin fiber has a pleasing stretch and recovery without the use of expensive elastic yarns such as spandex. This is because the olefin shrinks or bulks more than cotton. If more stretch is desired, then a smaller-than-normal amount of spandex can be used, resulting in a reduction in cost for the fabric manufacturer.

Drying Time: Procedures for washing fabrics manufactured using yarns of this invention are the same as those for washing cotton fabrics. However, the time required to dry the fabric made using the yarn of the invention is reduced by the amount of olefin used to make the blended yarn, as olefin does not absorb or hold water and only the cotton portion of the yarn has to be dried. The heat required to dry the fabric at the finishing step is greatly reduced, as only the cotton portion has to be dried. This is a significant cost advantage to the dyer and finisher as the energy required to dry the fabric is substantially reduced. This fact also is beneficial to the consumer who uses a home system of washing and drying.

It should be noted that when it is desirable to iron a fabric manufactured using yarn of the invention, the iron has to be set on medium as a cotton setting on most household irons or a steam setting becomes too hot and will melt the olefin in the blend. A warning on the care label for any fabric made using the yarn of the invention must always address this fact.

Example 1 : Using the cotton open end spinning system, fiber is blended together using 60% by weight of cotton and 40% by weight of olefin. The roving is collected into containers and fed to an open end spinning system. The roving is spun at high speeds to form a resultant blended yarn. Due to the centrifugal force that occurs during the open end spinning process, the cotton fiber slings to the outside of the yarn while the core of the yam is mostly olefin. The blended yarn is taken up on three-pound packages or cones. The blended yarn is shipped to the knitter or weaver to be made into greige goods.

Example 2: Using the cotton air jet spinning system, fiber is blended together using 60% by weight of cotton and 40% by weight of olefin. The roving is collected into containers and fed to an air jet spinning system. The roving is spun at high speeds and blended by high-pressure air to form a resultant blended yarn. Air pressure of 100 psi is used to interlace the fibers and to cause vortex spinning. Due to the centrifugal force that occurs during the air jet spinning process, the cotton fiber slings to the outside of the yarn while the core of the yarn is mostly olefin. The blended yarn is taken up on three-pound packages or cones. The blended yarn is shipped to the knitter or weaver to be made into greige goods. Example 3: Using a cotton ring spinning system, bales of fiber are blended using 60% cotton and 40% olefin. Roving is made and collected into containers. The roving is then combined and put up on roving packages. The roving packages are then fed to a twisting machine where they are twisted together to make a yarn. The blended yarn is taken up on three-pound packages and is shipped to the knitter or weaver to be made into fabric called greige goods. The ring spinning system does not have the same centrifugal force as the open end or the air jet spinning system. While the sheath-core effect is still achieved, more of the predominantly olefin core is visible to the eye when the fabric is dyed. The sheath is still predominately cotton and the fabric can be treated as a cotton fabric when dyed.

One skilled in the art can vary the blend or the size of yarn but it should be noted that when using the blend of cotton and olefin, the yarn size should not be manufactured below the 40/1 size. Therefore the blended cotton and olefin yarn typically would not be used to manufacture fine count items such as white dress shirting material or similar lightweight textile articles.

Example 4: A blend using 35% cotton fibers and 65% olefin fibers is made into a yarn on the air jet spinning system according to the invention. This is called blend A. This yarn is knitted with a yam of the invention that is a blend of 60% cotton fibers and 40% olefin fibers called blend B. A fabric is formed that has one end of blend A knitted with one end of blend B. The knitted fabric is dyed black using the cotton dye system. The dyed fabric is rinsed, dried and finished. The resultant fabric is two tones of black. One tone is a pure black and the other is a grey tone. The fabric looks and feels like it was made using 100% cotton.

Denim Cloth: Blended yarn comprising 60% cotton fiber and 40% olefin fiber is made according to the invention. The yarn is slashed and put up on a warp beam known to one skilled in the art. The warp beam is set on to a weaving machine and a fill yarn made according to examples above is combined with the warp on the weaving machine to produce a denim fabric that would be suitable to further manufacture into Blue Jeans. The denim fabric is dyed using the indigo dye system. The cotton portion of the blended yarn will absorb the indigo dye, the olefin portion of the yarn will not absorb the indigo dye. The denim fabric will appear as though it were a conventional Blue Jean fabric made using 100% cotton. The denim fabric is then cut and sewn into a Blue Jean pant.

Example 5: A plain woven cloth: A blended yarn comprising 60% cotton fiber and 40% olefin fiber is made according to the invention. The yarn is slashed and put up on a warp beam known to one skilled in the art. The warp beam is set on to a weaving machine and a fill yarn made according to examples above is combined with the warp on the weaving machine to produce a twill fabric that would be suitable to further manufacture into leisure slacks commonly referred to as "ducks". The fabric is solid dyed to a kaki color using the cotton dye system.

Anyone skilled in the art of cotton dyeing could dye the fabric to any shade attainable using the cotton dye method. The fabric can be further treated with stain blocker or any other chemicals commonly used by one skilled in the art.

Only the cotton portion of the yarn will absorb the chemicals. Olefin is basically inert and will not absorb any of the chemicals. The fabric is then further cut and sewn into leisure slacks that look and feel as if they were made using 100% cotton.

Example 6: Knitted Fabric: A blended yam comprising 60% Cotton Fiber and 40% olefin fiber is put up on three-pound packages. The yarn size is 16/1. The yarn is knitted on a 30" circular knitting machine into a tube suitable for dyeing.

The fabric is dyed to a black shade using the cotton dyeing system. The fabric is dried and finished on a standard open width finishing range. It is cut and sewn into a black sweater type garment. One skilled in the art will discover that any circular knit fabric can be made with the yarn of this invention. The limiting size of yarn is 40/1. The garments made will feel and look like 100% cotton articles. Only the cotton will absorb the cotton dyes and the fabric can be dyed to any cotton shade.

Example 7: Printed Fabric: The fabrics made using yarn if this invention can be either knitted or woven. These fabrics are then printed with any pleasing patterns using the aqueous cotton-printing systems well known to those skilled in the art.

While the above examples are good suggestions as to use, one skilled in the art will discover other applications using the yarn made according to the invention. Cotton fabrics are the most common fabrics in the world. By using the blended yarn of this invention, almost any system designed to process 100% cotton fabrics can be used to process fabrics made using the blended yam of this invention.

While most of the examples described herein have used the preferred blend of 60% cotton fibers blended with 40% olefin fibers, it should be understood that a blend using less cotton fibers and more olefin fibers, or less olefin fibers and more cotton fibers can be used to make a yarn and to manufacture woven or knitted textile articles. Blends using 25% to 80% cotton fibers blended with 75% to 20% olefin fibers were successfully made into satisfactory yarns. Those skilled in the art of spinning will choose their preferred blends. It was noticed that when the cotton content of the blend was reduced the olefin fibers became more visible. Also, when increasing the blend to cotton fibers beyond 60%, the yarns were not noticeably improved.

Example 8: Indigo rope dyeing.

Cotton Rotor spinning system: Bales of fiber are blended using 60% cotton and 40% olefin. Roving is made and collected into cans or containers. The roving is put up on roving packages. The roving is further processed using the rotor spinning system to make a twisted yarn. Multiple ends of yarn are made into a ball. The balls of yarn are fed to a rope-dyeing indigo dye range having at least four dipping stations. The blended cotton olefin rope is dipped into a reduced vat dye then elevated to be exposed to air or oxygen in the air. The rope turns from a yellow to a pleasing blue. The vat dye only adheres to the cotton surfaces of the rope. The rope is further dipped into three more stations and then elevated each time to expose it to air or oxygen in the air. The indigo vat dye turns to a darker shade of blue with each pass through the dips and elevations. The rope is dried and taken up on a beam. The beam is used as the warp section, to be made into a denim twill fabric. The ideal fabric is made using the indigo dyed yarn in the warp and using an undyed yarn of cotton and olefin in the fill. The resultant fabric looks like a typical blue jean fabric. It is lighter in weight and is more stable than a fabric made of 100% cotton. Regular short cotton staple can be used or a pima cotton long staple fiber can be blended with the olefin to make a more luxurious yarn.

One skilled in the art can vary the blend or the size of yarn but it should be noted that when using the blend of cotton and olefin, the yarn size should not be manufactured below the 40/1 size. Therefore the blended cotton and olefin yarn would not be used to manufacture fine count items such as white dress shirting material or similar lightweight textile articles.

It should be understood, of course, that the several embodiments of the invention herein described are intended to be representative only as certain variations thereof may be made without departing from the clear teachings of the invention. Accordingly, reference should be made to the appended claims in determining the full scope of the invention.

Claims

I Claim:

1. A spun yarn comprising a blend of cotton and olefin fibers, wherein at least 25% of the blend comprises cotton fibers and at least 20% of the blend comprises olefin fibers, said cotton fibers being predominantly in an outer sheath of the yarn and said olefin fibers being predominantly in a inner core of said yarn.

2. A spun yarn according to claim 1 , wherein said yarn is comprised substantially exclusively of cotton and olefin fibers.

3. A spun yarn according to claim 1 , wherein

(a) said cotton fibers comprise from 25% to 80% of the blend, and

(b) said olefin fibers comprise from 20% to 75% of the blend.

4. A spun yarn according to claim 1 , wherein (a) said cotton fibers comprise about 60% of the blend, and (b) said olefin fibers comprise about 40% of the blend.

5. A spun yarn according to claim 1 , wherein the yarn is spun by open end, air jet or cotton ring spinning systems.

6. A spun yarn according to claim 1 , wherein said yarn is dyed with cotton dyes.

7. A spun yarn according to claim 1 , wherein said yarn is at least 40/1 -cotton count.

8. A spun yarn according to claim 1 , wherein

(a) said cotton fibers are predominantly in the range of 0.75 inch to 1.06 inch in length, and (b) said olefin fibers are predominantly about 1.5 inches in length.

9. A spun yarn according to claim 1 , wherein said olefin fibers have a specific gravity of from about 0.91 to about 1.0.

10. A knitted or woven fabric constructed with the yarn of claim 1.

11. A fabric according to claim 10, wherein the fabric has been dyed using a cotton dye system.

12. A fabric according to claim 11 , wherein the fabric is a denim fabric and has been dyed using an indigo dye system.

13. A fabric according to claim 12, wherein (a) said yarn comprises at least 60% cotton.

14. A fabric according to claim 11 , which comprises

(a) at least one end of yarn of a first blend of cotton and olefin fibers, and

(b) at least one end of yarn of a second blend of cotton and olefin fibers different from said first blend, and (c) said fabric is dyed using a cotton dye system to achieve a multi-color effect.

15. A woven fabric made with the yarn of claim 1 , wherein

(a) warp yarns of said fabric are dyed using a cotton dye system, and (b) fill yarns of said fabric are undyed.

16. A woven fabric according to claim 15, wherein

(a) said yarns comprise at least 60% cotton and at least 20% olefin.

17. A woven fabric according to claim 16, wherein said fabric is dyed using an indigo dye system.