DENIM FABRIC AND ITS USE

Abstract

This invention relates to a fabric consisting of at least a first yarn containing cellulosic fibers modified by a cationic modifier and a second yarn containing cellulosic fibers not modified by a cationic modifier, and to the use of this fabric in order to obtain a denim appearance.

Claims

1. A fabric comprising a. a first yarn comprising cellulosic fibers modified by a cationic modifier, and b. a second yarn comprising cellulosic fibers not modified by a cationic modifier.

2. The fabric according to claim 1, wherein the construction of the fabric is such that on a first surface of the fabric mainly the first yarn is visible and on a second surface mainly the second yarn is visible.

3. The fabric according to claim 1, wherein the fabric is either a knit fabric or a woven fabric.

4. The fabric according to claim 3, wherein the knit fabric is a tuck and miss stich construction.

5. The fabric according to claim 3, wherein the woven fabric is denim.

6. The fabric according to claim 1, wherein the fabric is a greige fabric.

7. The fabric according to claim 1, wherein the fabric is dyed to a denim appearance.

8. The fabric according to claim 1, wherein the first yarn comprises between 30 and 80% (w/w) of lyocell fibers.

9. The fabric according to claim 1, wherein the second yarn consists of cellulosic fibers.

10. The fabric according to claim 1, further comprising a third yarn, wherein the third yarn is an elastane yarn.

11. A method of making the fabric of claim 1 having a denim appearance, comprising dyeing the fabric with a reactive dyestuff at a pH of between 6.0 and 8.0, in the absence of salt.

12. The method according to claim 11, wherein the reactive dyestuff is a composition comprising a mixture of several dyestuffs.

13. A tailored garment comprising the fabric according to claim 1.

14. A garment comprising the fabric according to claim 1.

15. The fabric according to claim 3, wherein the fabric is a knit fabric.

16. The fabric according to claim 9, wherein the second yarn is 100% lyocell fibers.

17. The method according to claim 11, wherein the pH of the reactive dyestuff is between 6.5 and 7.5.

18. The garment of claim 14, wherein the garment is a pair of jeans, a jacket, a shirt or a blouse.

Description

DESCRIPTION

[0013] It is an object of the present invention to provide a fabric consisting of at least

[0014] a. A first yarn containing cellulosic fibers modified by a cationic modifier,

[0015] b. A second yarn containing cellulosic fibers not modified by a cationic modifier.

[0016] The yarn containing cellulosic fibers modified by a cationic modifier can be manufactured by treating it in a package dyeing machine using a substantially colorless cationic crosslinking modifying agent in an aqueous system. “Substantially colorless” means in the context of this invention that it has no colour visible by the human eye.

[0017] A suitable colorless cationic crosslinking modifier has at least two, but no more than six functional groups reactive with cellulose. Preferably the colorless cationic crosslinking modifier is one out of the group containing trimethylammonium compounds and cationic triazin compounds. A suitable cationic crosslinking modifier is commercially available under the trade name “Ecofast™ CR-2000” from The Dow Chemical Company. The liquid ratio is 1:4˜1:10. The dosage of the cationic modifier (calculated on dry substance) is 1%˜10% on weight of fabric (“o.w.f”) with 2-4 g/L of sodium hydroxide. The treatment temperature is 40-80° C. for 20-40 minutes.

[0018] Preferably the construction of the fabric is such that on the first surface of the fabric mainly the first yarn is visible and on the second surface mainly the second yarn is visible. This is typical for the optical appearance of a denim fabric.

[0019] The fabric may contain a third yarn, in particular an elastane yarn. A typical yarn may be a yarn containing 100% Roica™ elastane fiber with yarn count 20 denier.

[0020] The fabric according to the invention is either a knit fabric or a woven fabric, preferably a knit fabric.

[0021] In a preferred embodiment of the present invention the fabric is a knit fabric of the tuck and miss stich construction type knitted according to the tuck and miss cam technology; this is crucial to achieve the inventive denim effect by a knit technology.

[0022] For this embodiment of the present invention the general process route would be as follows:

[0023] Preparation of the yarns (first yarn being modified by a cationic modifier, second yarn not being modified by a cationic modifier)->circular knitting of the first and second yarn by tuck and miss cam technology->fabric dyeing->enzyme treatment->softening->Stenter dressing.

[0024] A typical knitting machine and machine specification may be a Terrot Single jersey jacquard machine, model SHS-90, with Cylinder Diameter: 26″, Needle gauge: 28 G, number of feeder: 42, rotation: Anticlockwise. However machine types and specifications may work as well, if the features according to the invention are realized.

[0025] In a preferred embodiment the first yarn may have a lyocell content of between 30 and 80%. Below 30% lyocell the wanted “fading” or “wash down” effect is not visible; above 80% lyocell the fabric or garment looks dirty upon fibrillation. A typical composition may be 50% of Lyocell fibers and 50% of cotton fiber. However variations within the range outlined above are possible and effective, as well.

[0026] The type of yarn (spinning method, yarn count etc.) is very much depending on the type of the final fabric to be achieved and the skilled in the art will know which yarn to choose. For knit denim a ring spin yarn may be a good choice and for example a yarn count of the first yarn may be Ne 30/2.

[0027] The first yarn may be treated with a cationic modifier. The concentration of the cationic modifier may be between 0.5 and 5% (w/w) in aqueous solution, preferably between 1.0 and 3.5% (w/w), most preferably between 1.5 and 2,5% (w/w). By this treatment the first yarn is able to absorb reactive dyestuff without using sodium sulphate, sodium carbonate and other dyeing auxiliaries.

[0028] In a preferred embodiment the second yarn is composed of 100% Lyocell fibers. Blends with other cellulosic fibers like cotton, modal etc. are also possible, depending on the touch which should be obtained. The yarn count may be Ne 10, spun according to the MVS spinning method. The second yarn yarn is not able to absorb reactive dyestuff without using sodium sulphate, sodium carbonate and other dyeing auxiliary.

[0029] FIG. 2 shows a preferred embodiment of the invention: A circular single jersey weft knitting machine using the knit, tuck and miss cam is used to construct a even twilling pattern on the fabric and produces a dual-plied denim including a back side and a face side of the fabric. The back side is loosely knitted with variable tension/tensile force and a different stitch length than that of face side by adjusting the circular weft-knitting machine. Cam arrangements are set for creating terry twill effect and only twill effect on the fabric. The face side is compactly constructed with high tension/tensile force by adjusting the machine to a high-density program.

[0030] FIG. 2 shows (from the left to the right):

[0031] a. photos of the face side (dark color) and the back side (bright color);

[0032] b. a cross-section of the fabric (B=yarn 1=first yarn; W=yarn 2=second yarn);

[0033] c./d. a knitting machine program to control the movement action of the knitting needles.

[0034] In another preferred embodiment of the present invention the fabric is a woven fabric of the denim type. Preferably the first yarn is the warp yarn and the second yarn is the weft yarn.

[0035] In a particularly preferred embodiment this fabric is a greige, i.e. an essentially colorless or undyed fabric.

[0036] In another particularly preferred embodiment this fabric is dyed to a denim appearance. Therefore a preferred embodiment of the invention is a fabric of essentially blue color, preferably a shade of blue comparable to indigo-dyed cotton fabric. However also other colors (like red, black, green, etc.) are accepted as having a kind of denim appearance. An important aspect of denim appearance in general is the wash-out effect.

[0037] Preferably the first yarn contains between 30 and 80% (w/w) of lyocell fibers, the remainder being preferably cotton.

[0038] Preferably the second yarn consists of cellulosic fibers, more particularly Lyocell fibers. Blends with other cellulosic fibers like cotton, modal etc. are also possible, depending on the touch which should be obtained. In a particularly preferred embodiment the second yarn consists of 100% lyocell fibers.

[0039] In a further preferred embodiment the fabric according to the invention contains a third yarn, in particular made of elastane fibers.

[0040] It is a further object of the present invention to use the fabric described above in a process for making a fabric with denim appearance by dyeing the fabric described above with a reactive dyestuff at a pH of between 6.0 and 8.0, preferably at a pH of between 6.5 and 7.5 in the absence of salt (i.e. the dye bath consists essentially only of water (with only natural mineral content like tab water)) and the reactive dyestuff or mixture of reactive dyestuffs. Depending on the water source it may be necessary to adjust the pH of the water to the range mentioned above first before using it in the process according to the invention.

[0041] According to the invention the reactive dyestuff may be either a single reactive dyestuff or a composition consisting of a mixture of several reactive dyestuffs blended in a way suitable to obtain the requested color on the fabric.

[0042] In a preferred embodiment the use according to the invention is in particular piece dyeing of the tailored garment containing the fabric according to the invention.

[0043] It is yet a further object of the present invention to provide a use of a fabric according to the invention for the manufacture of garments, in particular jeans, jackets, shirts and blouses. Those garments then will show a denim appearance.

[0044] The invention will now be illustrated by examples. These examples are not limiting the scope of the invention in any way. The invention includes also any other embodiments which are based on the same inventive concept

EXAMPLES

Example 1

[0045] Cationic Treatment (Yarn):

[0046] The first yarn was composed of 50% of Lyocell fibers (from Lenzing Aktiengesellschaft, Austria, under the trade name TENCEL™ Lyocell) and 50% of cotton fiber. The yarn count was Ne 30/2 with ring spun method.

[0047] The first yarn is treated in a package dyeing machine. The cationic crosslinking modifier is commercially available under the trade name “Ecofast™ CR-2000” from The Dow Chemical Company. The concentration of the cationic modifier is 3% o.w.f (i.e. “on weight of fabric”) of yarn with 2 g/L of sodium hydroxide in the treatment liquid. The liquid ratio is 1:6. The treatment temperature is 80° C. for 30 min.

Example 2

[0048] Knitting of the Fabric:

[0049] The first yarn was the yarn of Example 1. The second yarn was composed of 100% Lyocell fibers (from Lenzing Aktiengesellschaft, Austria, under the trade name TENCEL™ Lyocell). The yarn count is Ne 10 with MVS spinning method. The third yarn was 100% Roica spandex, yarn count 20 denier.

[0050] The knitting machine specification was as follows: Terrot Single jersey jacquard machine, model SHS-90, with Cylinder Diameter: 26″, Needle gauge: 28 G, number of feeder: 42, rotation: Anticlockwise. The knitting program and the structure of the fabric thus obtained were as in FIG. 2.

Example 3

[0051] Dyeing and Finishing Process (Fabric)

[0052] The greige fabric will be heat set at a stenter at 190° C. for 2 minutes before the dyeing process. The dyeing process is done by garment dyeing method with the conditions as follows:

TABLE-US-00001 Liquid ratio: 1:10 Scouring process: 60° C. × 20 minutes Dyeing process: 60° C. × 30 minutes Dyeing recipe: Avitera Deep Blue SE: 2% on weight of fabric Avitera Red SE: 0.2% on weight of fabric Enzyme wash process: 50° C. × 30 minutes Enzyme wash recipe: 1 g/l Tanazyme CM 0.2 ml/l acetic acid Softening Process: 40° C. × 30 minutes Softening recipe: 1% Persoftal Nano SIL