KR20210122294A - Denim fabric and uses thereof - Google Patents

Abstract

The present invention relates to a fabric comprising at least a first yarn containing cellulosic fibers modified with a cationic modifier, and a second yarn containing cellulosic fibers not modified with a cationic modifier, and for obtaining a denim appearance. to the use of such fabrics.

Description

Denim fabric and uses thereof

The present invention relates to a fabric comprising at least a first yarn containing cellulosic fibers modified with a cationic modifier and a second yarn containing cellulosic fibers not modified with a cationic modifier; and to the use of this fabric to obtain a denim appearance.

Denim is a kind of comfortable, stylish, durable, casual textile fabric and is popular in all ages and in all countries. Due to their typical and distinctive appearance, particularly their wash-out effect and their reputation as durable fabrics, garments made from denim have the status of a cult item.

For this, dyeing with indigo and fabric construction are essential, and in garments the outer surface of the fabric is typically blue and the inner surface is predominantly white.

Conventional denim is a fabric in which warp and weft features are woven to create a fabric structure with fade characteristics, and is generally stiff, heavy, and dense fabric. Fabric constructions are generally 3/1 or 2/1 twill and 1/1 chambray constructions. 1 shows a typical fabric structure.

To achieve the typical denim appearance of a garment that is predominantly colored on the outside and predominantly white on the inside, colored and white yarns should be used for weaving. In general, colored yarn is used for warp and white yarn for weft. When weaving denim, 60% of the material's colored warp is on the outside of the garment, 40% of the white weft is on the inside, and so on. This means, among other things, that the weaver must have at least two types of yarn. If different colored fabrics are required, additional yarns already dyed in the target fabric color must be retained. Yarn dyeing is usually carried out in specific dyeing equipment and is therefore more expensive than, for example, fabric dyeing or piece dyeing. Also, only a very limited number of colors suitable for denim-like dyeing are available.

Traditionally, indigo dyestuff is commonly used for dyeing denim. Indigo pigment is a kind of water-insoluble vat dye. It has no affinity for cellulosic fibers. Many chemicals, such as sodium hydroxide and sodium bisulfite, are required to convert indigo into a water-soluble form, a type of fiber-friendly leuco. In order to convert 1 kg of indigo granules into leuco form, 0.8 kg of sodium bisulfite and 0.67 kg of sodium hydroxide are required for the reduction process. The workflow of a typical indigo yarn dyeing process is as follows: pre-wetting - rinsing - scouring - rinsing - yarn indigo dyeing (rope dyeing) - rinsing/softening - rebeaming.

Indigo dyeing is still done today in dye plants with wastewater treatment plants, making water treatment expensive. In addition, the fabric exhibits low wet rubbing fastness. A typical indigo yarn dyeing plant, which dyes 10 tonnes of indigo yarn per day, dyes with the following recipe: Indigo Pigment: 4 g/l; sodium bisulfite 3.2 g/l; sodium hydroxide 2.68 g/l; Pickup rate 70%, 10 soaks, consumption is 280 kg indigo, 224 kg sodium bisulfite and 188 kg sodium hydroxide per day, most of which must be treated before entering the water stream. There are over a thousand indigo yarn dyeing factories in the world.

Because of the stiff feel of woven denim, its application is limited in fashion design, especially in the field of tight or seamless garments. However, consumers these days want not only a denim look, but also softness, comfort, and lightness. Knit denim can provide these characteristics much better than woven denim.

The workflow of a typical denim fabric knitting process is as follows: introduction of indigo-dyed and non-indigo-dyed yarns into the knitting machine - knitting - fabric scouring - enzymatic treatment - softening - stenter dressing.

Knitted denim requires the use of special indigo knit yarns, but the availability of such yarns is one of the major obstacles to developing this market besides cost. Secondly, during the knitting step, the use of indigo knit yarns will cause contamination by colored fiber dust on the guiding rollers and feeders due to the poor rub fastness of the indigo dyed fibers and the yarn surface. The machine downtime required for cleaning is significantly reducing production efficiency. If the resulting contamination is not completely removed before the next production step, the resulting yarn will cause significant degradation of the fabric made therefrom.

Conventional reactive dyeing of cotton does not solve this problem. Reactive dyes on cotton do not tolerate wash-out effects, nor do the common problems with yarn dyeing go away.

assignment

In view of this prior art, the problem to be solved was to provide a method for producing a fabric having a typical denim appearance in an economical way without environmental pollution.

Explanation

The object of the present invention is at least

a. a first yarn containing cellulosic fibers modified with a cationic modifier;

b. It is to provide a fabric consisting of a second yarn containing cellulosic fibers that have not been modified by a cationic modifier.

Yarns containing cellulosic fibers modified by cationic modifiers can be made by treating them in a package dyeing machine using a substantially colorless cationic crosslinking modifier of an aqueous system. "Substantially colorless" in the context of the present invention means that there is no color visible to the human eye.

Suitable colorless cationic crosslinking modifiers have at least 2, but no more than 6 functional groups reactive with cellulose. Preferably, the colorless cationic crosslinking modifier is one of the group containing a trimethylammonium compound and a cationic triazine compound. Suitable cationic crosslinking modifiers are commercially available under the trade designation “Ecofast™ CR-2000” (from The Dow Chemical Company). The liquid ratio is 1:4 to 1:10. Dosage of cationic modifier (calculated for dry matter) is from 1% to 10% by weight of fabric (“o.w.f”) with 2-4 g/L sodium hydroxide. The treatment temperature is 40-80° C. for 20-40 minutes.

Preferably the structure of the fabric is such that the first yarn is primarily visible on the first surface of the fabric and the second yarn is primarily visible on the second surface. This is typical of the visual appearance of denim fabric.

The fabric may contain a third yarn, in particular an elastane yarn. A typical yarn may be a yarn containing 100% Roica™ elastane fibers having a yarn count of 20 denier.

The fabric according to the invention is a knit fabric or a woven fabric, preferably a knitted fabric.

In a preferred embodiment of the present invention, the fabric is a knitted tuck and miss stitch construction type knitted according to tuck and miss cam technology; This is important to achieve a unique denim effect by knitting techniques.

A general process route for this embodiment of the invention would be as follows:

Preparation of yarn (first yarn modified with cationic modifier, second yarn not modified with cationic modifier) -> circular knitting of first and second yarns by tuck and miss cam technique -> Fabric dyeing -> enzymatic treatment -> softening -> stenter dressing.

Typical knitting machine and machine specifications are Terrot Single jersey jacquard machine, model SHS-90 (cylinder diameter: 26", needle gauge: 28 G, number of feeders: 42, rotation: clock in the opposite direction) However, machine types and specifications may also be valid when the features according to the invention are realized.

In a preferred embodiment, the first yarn may have a lyocell content of 30-80%. At less than 30% lyocell, the desired "fading" or "wash down" effect is not seen; More than 80% of lyocell fibers or garments appear dirty upon fibrillation. A typical composition would be 50% lyocell fibers and 50% cotton fibers. However, variations within the ranges described above are also possible and effective.

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

The first yarn may be treated with a cationic modifier. The concentration of the cationic modifier may be 0.5 to 5% (w/w) in aqueous solution, preferably 1.0 to 3.5% (w/w), most preferably 1.5 to 2.5% (w/w). This treatment allows the first yarn to absorb reactive dyes without the use of sodium sulfate, sodium carbonate and other dyeing aids.

In a preferred embodiment, the second yarn consists of 100% lyocell fibers. Blends with other cellulosic fibers, such as cotton, modal, etc., are also possible, depending on the tactile feel to be achieved. The count may be Ne 10 spun according to the MVS spinning method. The second yarn cannot absorb reactive dyes without the use of sodium sulfate, sodium carbonate and other dyeing aids.

Figure 2 shows a preferred embodiment of the present invention: a circular single jersey weft knitting machine using knit, tuck and miss cams is used to construct a uniform twill weave pattern in the fabric, and We produce dual-plied denim with back and front sides. The back side is loosely knitted with varying tension/tensile forces by adjusting a circular weft knitting machine, providing a different stitch length than the front side. The cam arrangement is set up to produce only a terry twill effect and a terry twill effect to the fabric. The front side is compactly constructed with high tension/tensile force by adjusting the machine to a high-density program.

Figure 2 shows (from left to right):

a. Photos of the front (dark) and back (light);

b. cross-section of the fabric (B = yarn 1 = first yarn, W = yarn 2 = second yarn);

CD. A knitting machine program that controls the movement of the knitting needles.

In another preferred embodiment of the invention, the fabric is a fabric of denim type. Preferably the first yarn is warp and the second yarn is weft.

In a particularly preferred embodiment, the fabric is grey, ie essentially colorless or undyed.

In another particularly preferred embodiment, this fabric is dyed to a denim appearance. Accordingly, a preferred embodiment of the present invention is a blue tint similar to an essentially blue fabric, preferably an indigo dyed cotton fabric. However, other colors (such as red, black, green, etc.) are also considered a kind of denim look. An important aspect of denim appearance in general is the wash out effect.

Preferably, the first yarn contains 30 to 80% (w/w) lyocell fibers, the balance being preferably cotton.

Preferably, the second yarn consists of cellulosic fibers, more particularly lyocell fibers. Blends with other cellulosic fibers, such as cotton, modal, etc., are also possible, depending on the tactile feel to be achieved. In a particularly preferred embodiment, the second yarn consists of 100% lyocell fibers.

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

It is a further object of the present invention to prepare the fabric as described above in the absence of salts (i.e. the dye bath consists essentially of only water (which has only a natural mineral content, such as tap water) and a reactive dye or a mixture of reactive dyes 6.0 to 8.0 The use of the fabric described above in a process for producing a fabric having a denim appearance by dyeing it with a reactive dye at a pH of 6.5 to 7.5. Depending on the water source it may be necessary to first adjust the pH of the water to the above-mentioned range before using it in the process according to the invention.

According to the present invention, the reactive dye may be a single reactive dye or a composition consisting of a mixture of several reactive dyes blended in a suitable manner to obtain the desired color for the fabric.

In a preferred embodiment, the use according to the invention is in particular piece-dying of tailored garments containing the fabric according to the invention.

Another object of the present invention is to provide the use of the fabric according to the invention for the production of garments, in particular jeans, jackets, shirts and blouses. After that, such garments will show a denim appearance.

The present invention will now be illustrated by way of examples. These examples do not limit the scope of the present invention in any way. Furthermore, the present invention includes any other embodiments based on the same inventive concept.

Example

Example 1:

Cationic treatment (yarn):

The first yarn consisted of 50% lyocell fibers (from Lenzing Aktiengesellschaft (Austria) under the trade designation TENCEL™ Lyocell) and 50% cotton fibers. The count was Ne 30/2 by ring spun method.

The first yarn is processed in a package dyeing machine. Cationic crosslinking modifiers are commercially available from The Dow Chemical Company under the trade designation “Ecofast™ CR-2000”. The concentration of cationic modifier is 3% o.w.f of yarn (ie "by weight of fabric") with 2 g/L sodium hydroxide in the treatment solution. The liquid ratio is 1:6. The treatment temperature is 80° C. for 30 minutes.

Example 2:

Knitting the fabric:

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

The knitting machine specifications were as follows: Terrot single jersey jacquard machine, model SHS-90, cylinder diameter: 26", needle gauge: 28 G, number of feeders: 42, rotation: counterclockwise. The structure was the same as in FIG. 2 .

Example 3:

Dyeing and finishing process (fabric)

The gray fabric is heat-set at 190° C. for 2 minutes in a stenter before the dyeing process. The dyeing process is carried out as a garment dyeing method using the following conditions.

Claims (14)

At least
a. a first yarn containing cellulosic fibers modified with a cationic modifier;
b. A fabric consisting of a second yarn containing cellulosic fibers that have not been modified with a cationic modifier. The fabric of claim 1 wherein the structure of the fabric is such that a first yarn is predominantly visible on a first surface of the fabric and a second yarn is predominantly visible on a second surface of the fabric. The fabric according to claim 1 , wherein the fabric is a knit fabric or a woven fabric, preferably a knitted fabric. The fabric of claim 1 , wherein the fabric is a knit of a tuck and miss stitch construction type. The fabric of claim 1 , wherein the fabric is a denim type of fabric. The fabric of claim 1 , wherein the fabric is a greige fabric. The fabric of claim 1 , wherein the fabric is dyed to a denim appearance. The fabric of claim 1 wherein the first yarn contains 30 to 80% (w/w) lyocell fibers. The fabric according to claim 1 , wherein the second yarn consists of cellulosic fibers, preferably 100% lyocell fibers. The fabric of claim 1 , wherein the fabric contains a third yarn, in particular an elastane yarn. Use of a fabric according to claim 1 for producing a fabric having a denim appearance by dyeing the fabric with a reactive dye at a pH of 6.0 to 8.0, preferably a pH of 6.5 to 7.5 in the absence of salts. Use according to claim 11, wherein the reactive dye is a composition consisting of a mixture of several dyes to obtain the desired color for the fabric. Use according to claim 11 , wherein the dyeing is piece dyeing in particular of a tailored garment containing the fabric according to claim 1 . Use of the fabric according to claim 1 for the production of garments, in particular jeans, jackets, shirts and blouses.

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