MXPA04006794A - Production of cotton warp yarns having inverse denim effect. - Google Patents

Abstract

The present invention relates to a process for producing cotton warp yarns having an inverse denim effect, which comprises using an indigo dyeing range to perform a dyeing step whereby the cotton warp yarn is through-dyed with indigo in one pass at a dyeing temperature of 30 to 90 DEG C. and an indigo concentration of 5-500 g/l and a subsequent bleaching step whereby the indigo is selectively decolorized on the surface of the cotton warp yarn.

Description

PRODUCTION OF COTTON URDIMER THREADS THAT HAVE EFFECT-D € IE € idhbA-i ^ lVERS DESCRIPTIVE MEMORY The present invention relates to a process for producing indigo-dyed cotton warp yarns, which have a reverse jean effect and also textile articles comprising said cotton warp yarns. Denim refers to a relatively thick woven cotton fabric which was originally used for sturdy workwear, but is currently used particularly to manufacture fashionable denim articles. The warp yarns necessary to produce denim may be dyed with indigo or with sulfur dyes, especially sulfur black, although dyeing in blue with indigo is predominantly predominant. Traditionally, the warp yarn is dyed with indigo as a rope or as a sheet of warp yarn in specific dyeing trains consisting of a combination of one or more trays with squeezing rollers and a subsequent sector of laying in the air. The reduced dye is applied to the racks and oxidized in the air laying sector (see for example Technical Information Tl / T 0 7 d of BASF AG dated June, 1995, title: Continuous dyeing with indigo). The dyeing is usually carried out in a dye bath at room temperature or slightly elevated temperatures of about 20-35 ° C, a pH of about 10.5 a can be used wetting agents in a concentration of about 0.1 to 5 g / l. A redox potential in the dyebath is maintained using an excess of hydrosulfite reducing agent in amounts of about 0.1 to 5 g / l. The contact time of the yarn with the dye bath is generally from 8 to 30 seconds per pass. Multi-pass dyeing, ie the repeated application of dye from the dyebath by immersion with subsequent squeezing in the dyeing pan and laying to the next air, makes it possible to obtain darker tones (see for example ITB Veredlung 2 / 90, title: Indigo-Fárberei: Verfahrens- und maschinentechnische Lósungen, author: Dipl. Ing. L. Haas). German patent application DE 196 29 985 describes single-pass dyeing where, in order to overcome the low affinity of indigo, the dyebath additionally has added to the same salt in the form of sodium chloride in order that it can be adjusted an electrolyte concentration of 200 to 350 g / l. These processes produce a dye called a ring, that is, the fiber is dyed only on the surface, leaving the inside of the fiber, the core, unstained. The ring dyeing makes it possible to provide the manufactured denim articles with a high contrast appearance in particular washing and / or bleaching processes by means of a wash of the initially dark blue fabric. An example is the familiar effect of washing with stone, which is achieved by washing the article made with enzymes and pumice stones, - However, denim fashion is now demanding items which no longer present this wash effect or modifications obtained using this effect. On the contrary, the demand is for items that become darker in washing operations or other treatment operations instead of becoming clearer. To put it in some way, these items behave inversely to conventionally dyed denim. The ring-dyed denim of the prior art can not provide such effects. Accordingly, there is a need for a process to produce an inverse denim effect that is economical and does not require additional cost and inconvenience on the part of the dyers, which is simple to perform, ideally on existing dyeing equipment of the dyers. The present invention then provides said method. The present invention relates to a process for producing cotton warp yarns having a reverse jean effect, which comprises using an indigo dyeing train to perform: - a dyeing step through which the cotton warp yarn is thoroughly dyed with indigo in one pass and a dyeing temperature of 30 to 90 ° C and a indigo concentration of 5-500 g / l - a subsequent bleaching step or etching step, is surface dyed where the dye is locally destroyed, as described by M. Peter, HK Rouette in "Grundiagen der Textilverediung" page 633 et seq., so that the indigo is selectively bleached on the surface of the cotton warp yarn. This selective discoloration can in principle be carried out oxidatively or reductively, with oxidative discoloration being preferred. The method of the invention, in this way ideally provides a colorless product which can be modified to be dark blue by removing the colorless ring and extending the color core in the open. An indigo dyeing train within the scope of the present invention is a train which consists of a dyeing pan or a combination of multiple dyeing trays with squeezing rollers and subsequent air laying sectors (see for example ITB Veredlung 2 / 90, title: Indigo-Fárberei: Verfahrens- und maschinentechnische Lósungen, author: Dipl. Ing. L. Haas). Any commercially available indigo can be used. The indigo preferably is used in amounts of 10-50 g / l and preferably in amounts of 20 to 40 g / l. It is particularly advantageous to use pre-reduced indigo to carry out the process of the invention. The pre-reduced indigo used is ideally produced from indigo without the use of reducing agent, such as sodium dithionite for example, but by catalytic hydrogenation. It is more convenient to use indigo in the form of a solution from the market by DyStar Textilfarben GmbH &; Co. Deutschland KG. To stabilize indigo leuco, that is, to reduce the indigo leuco which has been oxidized in the dyebath, it is preferable to use an excess of hydrosulfite of 0.1 to 5 g / l and preferably 0.2 to 2 g / l. It will be appreciated that instead of hydrosulfite, it is possible to use other suitable reducing agents, such as glucose or hydroxyacetone, or combinations of various reducing agents such as glucose / hydrosulfite. The temperature at which the process of the invention is preferably carried out is 30-90 ° C and preferably on the scale of 50 to 70 ° C. The process of the invention can be carried out with or without a wetting agent, but preferably it is carried out in the presence of a wetting agent. Examples of suitable wetting agents are anionic wetting agents, for example ethoxylated fatty alcohol, alkanesulfonate, sulfosuccinate, alkyl phosphate or paraffins and hydrocarbons or mixtures thereof, and preference is given to the use of phosphoric ester salts. The amounts in which the aforementioned wetting agents are used are preferably in the range of 5 to 50 g / l and preferably in the range of 10 to 25 g / l.

The pH of the dyebath in the preferred process of the invention is that of the T5-a-43r5 The process of the invention surprisingly leads in a single pass to yarns which are thoroughly dyed, that is, stained in the nucleus as well as the surface region. The contact time with the dye bath preferably is 8 to 30 seconds and preferably 15 to 20 seconds. The laying to the rear air preferably takes from 90 to 130 seconds and preferably from 100 to 10 seconds. The dyeing step is followed by a bleaching step wherein the indigo is selectively bleached on the surface of the cotton warp yarn leaving the core of the yarn unchanged. Useful bleaching agents include all systems which oxidize indigo, for example hypochlorites, such as sodium hypochlorite or permanganate. But particular preference is given to permanganate, which exists for example in the form of an alkali metal salt and preferably in the form of potassium permanganate. A particular preference is given to a bleaching bath containing potassium permanganate in an alkaline medium, potassium permanganate being used in amounts which are preferably from 5 to 100 g / l and preferably from 20 to 50 g / l. The pH is preferably in the range from 8 to 10 and can be adjusted, for example, with NaOH, for example with NaOH 8 or Bé. It is preferable to adjust the bleach bath to a viscosity of about 12 to 50 seconds as measured using a Ford cup (DIN 5321 1-4) and preferably 25 to 45 seconds by means of a -bass moderator. The moderators of glassware, for example, include theological additives such as polyvinylcaprolactam, polyvinylpyrrolidone and also copolymers thereof, polyetherpolyol, associative thickeners, polyurea, polyurethane, sodium alginates, modified galactomannans, polyetherurea, polyurethane, cellulose ethers. ionic The bleaching step is performed from 15 to 90 ° and preferably at room temperature. The contact time with the bleaching bath is preferably 10 to 30 seconds and particularly 12 to 20 seconds. In a preferred embodiment of the process according to the invention, the thorough dyeing of the cotton warp yarn in the dyeing step is followed by rinsing with water, bleaching with permanganate, another rinsing and a subsequent treatment with a bisulfite solution and the cycle of bleaching, rinsing and bisulfite treatment is repeated at least once. It is particularly advantageous that there are four to six cycles of bleaching, rinsing and bisulfite treatment. An intermediate drying between the dyeing and bleaching step can be used to further increase the ring effect achieved by the bleaching. The rinsing between the bleaching bath and the bisulfite bath can be carried out in 1 to 3 passes and can be associated with an air laying of 0 to 120 seconds.

The bisulfite bath preferably contains 10 to 100 g / l and followed by laying in the air from 0 to 120 seconds. It is a particular advantage for the dyers that the dyeing step of the process according to the invention is completed after a single pass. The reason is that this leaves the dyers the option of using the other dyeing trays of the indigo dyeing train which are not necessary for the dyeing to perform the subsequent bleaching step with or without rinsing and with or without bisulfite treatment . In this way, the team needs, if at all, to be modified only minimally. The cotton warp yarns dyed through the process can be subjected to subsequent processing steps to obtain certain effects and then be woven in a conventional manner and processed into consumer textiles, such as particular garments. However, it is also possible that the dyed and bleached cotton warp yarns of surface are processed into textile articles without further treatment and, if desired, then only that they undergo other processing steps, i.e., modify the already made merchandise. Of course, it is also possible to subject not only the dyed and bleached cotton warp yarns, but also the textile articles produced therefrom to additional processing steps.

The warp threads of cotton dyed through the processed additionally in consumer goods, in combination with other materials. The elastane combinations can be mentioned by way of example. The reverse denim effect of the dyed and bleached cotton warp yarns according to the invention can be made visible, for example, by removing the non-dyed outer ring of the yarn through washing or some other mechanical tensioner and appearing as a result a dark dye core. In another implementation of the method according to the invention, the surface of the decolorized cotton warp yarn in the bleaching step is stabilized in a third step. In this way, the reverse denim effect can be reinforced by treating the surface with for example Ti02 in the presence of binders, such as acrylate or polyurethane copolymer. In the same way, the surface can be modified not only to be white but also to be colored, for example with color pigments, such as dyes to the vat in the form of pigment, or else disperse dyes. Of course, it is also possible that the aforementioned third step is not carried out until after the cotton warp yarn has been woven, for example in the finished textile product.

The present invention also provides textile articles comprising cotton warp yarns of the invention Examples of said textile articles are denim fabrics which have not been made, but in particular garments such as trousers , skirts, shirts, jackets, etc. or other articles of textile type The examples below illustrate the invention The parts in the examples of the table are by weight.

EXAMPLE 1 A) Dyeing step A commercially available non-pretreated dry cotton warp yarn was dyed from a dyeing liquor of the following composition: 20 g / l indigo as a 40% solution of DyStar Indigo Vat commercially available 2 g / l hydrosulfite (BASF Hydrosulfit konz.) 20 g / l wetting agent (Primasol NF) The pH of the solution was 13. The yarn was dyed at 50 ° C in the course of an immersion time of 25 seconds . The subsequent air dyeing took 120 seconds. This was followed by two rinses with water at 20 ° C.

Thoroughly dyed yarn having a high level of applied indigo was obtained. A dye analysis of the Tinted Philo revealed a level of ^ 6% B) Bleaching step The dyed yarn obtained according to A) was stained with potassium permanganate (20 g / l) at a temperature of 25 ° C and a pH of 8.5. The contact time with the bleaching bath was 18 seconds. The yarn was then conducted directly to a bath of 30 g / l hydrosulfite (pH: 8.5, temperature: 25 ° C) and subsequently rinsed at 20 ° C. The cycle of bleaching, hydrosulfite treatment and rinsing was repeated twice later.

EXAMPLE 2 A yarn dyed according to step A) of example 1 was treated at a temperature of 25 ° C with a bath containing 200 g / l of thickener (Monagum, 10%) 150 g / l of etchant (Magnatrop W ), 80 g / l of moisture donor (Átzverstárler HN), 10 g / l of aqueous solution of sodium hydroxide and 150 g / l of Rongalit C for 17 seconds, dried and steam-treated intermediate to I02 ° ~ C for 1 minute. This was followed by a laafctec a ^ fP and then at 20 ° C.

EXAMPLE 3 Example of dyeing in sizing application A yarn treated according to steps A) and B) of example 1 was dried in an intermediate manner in a contact dryer and then treated at a temperature of 30 ° C with a size bath containing: 200 g / l of binder (Perapret PU), 30 g / l of thickener (Primasol AMK), 100 g / l of white pigment (Acramin Weip DRN 01) and subsequently adjusted in a contact dryer.

EXAMPLE 4 Example of dyeing in sizing application A yarn treated according to steps A) and B) of example 1 was dried in an intermediate manner in a contact dryer and then treated at a temperature of 30 ° C with a size bath containing: 200 g / l of starch ether 350 g / l of titanium dioxide 300 g / l of binder (Perapret PU),? ßß-g / l of Imperan Orang &-R = G ^ rAmar \\\ o Pigment 5) and subsequently adjusted to a contact dryer.

EXAMPLE 5 Example of dyeing in sizing application A yarn treated according to steps A) and B) of example 1 was dried in an intermediate manner in a contact dryer and then treated at a temperature of 30 ° C with a size bath containing: 200 g / l of starch ether 300 g / l binder (Perapret PU), 50 g / l Indanthren Gelb 5GF-D (Cl Yellow Tub 46) and subsequently adjusted in a contact dryer.

EXAMPLE 6 Example of dyeing in sizing application A yarn treated according to steps A) and B) of example 1 was dried in an intermediate manner in a contact dryer and then treated at a temperature of 30 ° C with a sizing bath containing 200 g / l of ether of starch 400 g / l titanium dioxide 300 gl binder (Perapret PU) and subsequently adjusted in a contact dryer. The examples in the table below describe other embodiments of the method of the invention. They are carried out in a manner similar to the aforementioned examples 1 to 3.

Example of bleaching Example after treatment Product 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 9 20 Potassium permanganate 5 50 30 Sodium hypochlorite 20 10 Sodium persulfate 30 10 Inorganic salt 40 Starch ether 20 40 20 40 200 200 200 Acrylate copolymer 50 50 50 30 Moisture donor 80 Reducer agent 150 30 Sodium bisulphite 30 20 30 Titanium dioxide 100 400 150 Polyurethane 200 300 100 300 Pigment of color * 00 200 Temperature (° C) 30 40 25 30 25 60 50 25 40 40 40 40 30 30 30 PH 1 1 1 1.2 12 1 1 10.6 6.5 1 1 .5 6.5 8.5 8.5 8.5 6.5 6.5 8 8 8 * Pigment color not only refers to pigment dyes, but also to dyes to the vat, which are present in their oxidized form, as a pigment, but also scattered dyes.

Claims (10)

NOVELTY OF THE INVENTION CLAIMS

1. A process for producing cotton warp yarns having an inverse denim effect, which comprises using an indigo dyeing train to perform a dyeing step through which the cotton warp yarn is thoroughly dyed with indigo in one pass at a dyeing temperature of 30 to 90 ° C and an indigo concentration of 5-500 g / l and a subsequent bleaching step through which the indigo is selectively bleached on the surface of the cotton warp yarn.

2. The process according to claim 1, further characterized by using indigo in the form of a solution of leuco indigo.

3. The process according to claim 2, further characterized in that the indigo leuco has been produced from indigo by catalytic hydrogenation.

4. The method according to one or more of claims 1 to 3, further characterized in that it is carried out in the presence of a wetting agent.

5. The process according to claim 4, further characterized in that the wetting agent is used in amounts of 5 to 50 g / l and preferably 10 to 25 g / l.

6. The process according to one or more of the processes carried out by means of a bleaching bath containing potassium permanganate as a bleaching agent.

7. The process according to one or more of claims 1 to 6, further characterized in that the bleaching step is carried out by means of a bleaching bath containing a thickener.

8. The process according to one or more of claims 1 to 7, further characterized in that the thorough dyeing of the cotton warp yarn in the dyeing step is followed by rinsing with water, bleaching with permanganate, another rinsing and a subsequent treatment with a bisulfite solution and the cycle of bleaching, rinsing and bisulfite treatment is repeated at least once.

9. - The method according to one or more of claims 1 to 8, further characterized in that the bleaching step is followed by a third step through which the surface of the decolorized cotton warp yarn in the bleaching step is treated with a pigment suitable for cotton.

10. - A textile article comprising cotton warp yarns dyed through a process of one or more of claims 1 to 9.