DE10332164A1 - Process for the production of cotton warp yarns with "inverse denim" effect - Google Patents

Abstract

The present invention relates to a process for the production of cotton warp yarns having an "inverse denim" effect, characterized in that in an indigo dyeing plant DOLLAR A - in a dyeing step the cotton warp yarn with indigo at a dyeing temperature of 30 to 90 ° C and is dyed indigo concentration of 5-500 g / l in one go and DOLLAR A - is selectively decolorized in a subsequent bleaching step of the indigo on the surface of the cotton warp yarn.

Description

The The present invention relates to a process for the preparation of dyed with indigo Cotton warp yarns that have an "inverse Denim effect, and textile articles containing such cotton warp yarns.

When Denim is a relatively coarse cotton fabric that was originally used for heavy-duty workwear, but today used especially for the production of fashionable jeans products becomes. The need to produce denim warp yarns can with Indigo, but also with sulfur dyes, in particular sulfur black, colored be, with the blue coloration with indigo far outweighs.

Traditionally The warp yarn is used as a cable or warp with Indigo on special dyeing colored, which comes from a combination of one or more troughs Crushing and subsequent Air passage exist. In the troughs the reduced dye is applied and oxidized in the aisle (see, for example, Technical Information TI / T 017 d of BASF AG of June 1995, title: Continuous Dyeing with Indigo).

Usually becomes the coloring in a dyebath at room temperature or slightly elevated temperatures of about 20-35 ° C, one pH of about 10.5 to 14 and an indigo concentration of about 0.5 to 10 g / l performed. In addition, you can Wetting agents are used in a concentration of about 0.1 to 5 g / l become. To maintain a redox potential in the dyebath is a surplus of hydrosulfite (reducing agent) in amounts of about 0.1 to 5 g / l used. The contact time of the yarn with the dyebath is per turn usually 8 to 30 seconds. Dyeing in several passes, i. the repeated application of dye from the dyebath by Diving followed by Squeezing in the dyeing trough and the subsequent aisle, allows the achievement of greater depths of color (see, for example, ITB Finishing 2/90, title: Indigo Dyeing: Process and Mechanical Solutions, Author: Dipl. Ing. L. Haas).

The German Patent Application 196 29 985 describes dyeing with a train in which to overcome the low absorption capacity from indigo to the dyebath additionally Salt in the form of sodium chloride is added to an electrolyte concentration from 200 to 350 g / l.

To all of these methods will give a so-called ring-dyeing, i. the fiber is only on the surface stained, whereas the interior of the fiber, the core, remains undyed. The ring dyeing allowed it, ready-made denim article in special washing and / or Bleaching process to give a high-contrast appearance in which a Brightening of the initially dark blue dyed fabric is achieved (wash-down). As an example, the well-known stone-wash effect called by Washing the finished article with enzymes and pumice stones is achieved.

Of the However, fashionable jeans market now demands items that are no longer this wash-down effect or by utilizing this effect achieved modifications exhibit. Rather, articles are required in washing or other treatment processes are not brighter, but darker. These articles are supposed to behave in the opposite direction to conventionally dyed denim - inverse -, one speaks of "invers Denim".

With According to the prior art ring-dyed denim can such Effects can not be achieved.

It Thus, there is a need for a method of making "inverse Denim "that can be cost-effective must, that is the dyer no additional may demand equipment and technical effort, but simply and ideally be practicable in its existing dyeing machine park got to.

With The present invention now provides such a method.

• – in einem Färbeschritt das Baumwollkettgarn mit Indigo bei einer Färbetemperatur von 30 bis 90°C und einer Indigo-Konzentration von 5–500 g/l in einem Zug durchgefärbt wird und
• – in einem sich anschließenden Bleichschritt, oder Ätzschritt, wobei man unter Ätzen eine Behandlung einer gefärbten Oberfläche versteht, bei dem der Farbstoff lokal zerstört wird, wie von M. Peter, H.K. Rouette in „Grundlagen der Textilveredlung" S.633 ff. beschrieben, der Indigo auf der Oberfläche des Baumwollkettgarns selektiv entfärbt wird. Diese selektive Entfärbung kann grundsätzlich oxidativ oder reduktiv erfolgen, wobei die oxidative Entfärbung bevorzugt ist.

The invention relates to a method for the production of cotton warp yarns having an "inverse denim" effect, characterized in that in an indigo dyeing plant

• - In a dyeing step, the cotton warp yarn is dyed with indigo at a dyeing temperature of 30 to 90 ° C and an indigo concentration of 5-500 g / l in one go and
• In a subsequent bleaching step or etching step, etching being understood to mean a treatment of a colored surface in which the dye is locally destroyed, as described by M. Peter, HK Rouette in "Grundlagen der Textilveredlung" p. 633 ff. The selective decolorization can in principle be carried out oxidatively or reductively, the oxidative decolorization being preferred.

To the method according to the invention is thus ideally a colorless product obtained by Remove the colorless ring and expose the colored core dark blue can be modified.

Under Indigo dyeing are understood in the context of the present invention facilities, consisting of one or a combination of several coloring troughs with squeezing and subsequent air passages exist (see, for example, ITB Finishing 2/90, title: Indigo Dyeing: Process and Machine Engineering Solutions, Author: Dipl. Ing. L. Haas).

When Indigo can be any commercial Indigo can be used. It is preferred in amounts of 10-30 g / l, particularly preferably used in amounts of 20 to 25 g / l.

It is particularly advantageous to carry out the process according to the invention with prereduced indigo. It is ideally used prereduced indigo, which has been prepared without the use of reducing agents, such as sodium dithionite, but by catalytic hydrogenation of indigo. Indigo is particularly advantageously used in the form of a solution of leucoindigo, as described, for example, in US Pat EP 1 097 184 B1 is described and offered by the company DyStar Textile dyes GmbH & Co. Germany KG in the market.

to Stabilization of leucoindigo, i. for the re-reduction of oxidized in dyebath Leukoindigo is preferably an excess of hydrosulfite from 0.1 to 5 g / l, more preferably from 0.2 to 2 g / l used. Of course can instead of the hydrosulfite, other suitable reducing agents, For example, glucose or hydroxyacetone, are used.

The inventive method is preferably carried out at a temperature of 30-70 ° C, with temperatures of 50 to 60 ° C are preferred.

The inventive method can be carried out with and without wetting agent, is preferred it performed in the presence of a wetting agent. Suitable wetting agents are for example anionic wetting agents, for example fatty alcohol ethoxylate, Alkanesulfonate, sulfosuccinate, alkyl phosphate or paraffins and hydrocarbons, or mixtures of these wetting agents, Very particular preference is given to salts of phosphoric esters The wetting agents mentioned are preferred in quantities from 10 to 50 g / l, more preferably 20 to 25 g / l used.

Of the pH of the dyebath lies in the method according to the invention preferably in the range of 10.5 to 13.5.

The inventive method surprisingly leads already dyed through in one go, i.e. also colored in the core, Yarns. It is the contact time with the dyebath preferably 8 to 30 seconds, more preferably 15 to 20 seconds. The ensuing Aeration is preferably 90 to 130 seconds, more preferably 100 up to 110 seconds.

in the to the dyeing step subsequent bleaching step, becomes the indigo on the surface of the cotton warp yarn is selectively decolorized, the core of the yarn unchanged remains.

To suitable bleaches are all systems that oxidize indigo, for example, hypochlorites, such as sodium hypochlorite or permanganate. In particular, however, is permanganate, which, for example, in Form of an alkali metal salt, particularly preferably in the form of potassium permanganate, is present. Very particularly preferred is a bleaching bath, the potassium permanganate in alkaline medium wherein potassium permanganate is preferred in amounts of 5 to 30 g / l, especially is preferably used in amounts of 5 to 25 g / l.

Of the pH is preferably 8 to 10 and can, for example, with NaOH, such as NaOH 38 ° Bé, set become.

It is preferred to adjust the bleaching bath by means of viscosity moderators to a viscosity of about 12 to 50 seconds measured with Ford cup (DIN 5321 1-4) particularly preferably 25 to 45 seconds. Suitable viscosity moderators are rheological additives, for example:
Polyvinylcaprolactam, polyvinylpyrrolidone and their co-polymers polyether polyol, associative thickener, polyurea, polyurethane,
Sodium alginates, modified galactomannans, polyetherurea, polyurethane, nonionic cellulose ethers.

Of the Bleaching step is at 15 to 90 ° C, preferably at rum temperature, executed.

The Contact time with the bleaching bath is preferably 10 to 30 seconds, more preferably 12 to 20 seconds.

In a preferred embodiment the method according to the invention will after dyeing of the cotton warp yarn in the dyeing step is preferred rinsed several times with water, then bleached with permanganate as described, then rinsed again and then with a bisulfite solution treated and the cycle of bleaching, rinsing and treatment with bisulfite repeated at least once.

It is particularly beneficial to the cycle of bleaching, rinsing and Treat with bisulfite four to six times to go through.

By an intermediate drying between dyeing step and bleaching can the ring effect achieved by bleaching is further enhanced.

The do the washing up between bleach and Bisulfitbad can be done in 1 to 3 trains and be associated with an aisle of 0 to 120 seconds.

The Bisulfite contains Bisulfite preferably in amounts of 10 to 60 g / l, more preferably 20 to 40 g / l. Also to the Bisulfitbad can be an aisle of 0 to 120 seconds connect.

It is for the dyer particularly advantageous that the dyeing step of the method according to the invention finished after only one turn. Thus, he has the opportunity, the subsequent bleaching step, if necessary, including rinsing and, if appropriate, treatment with bisulfite in the other, not for dyeing required Dyeing troughs of his indigo dyeing plant perform. Thus, no or only minor modifications of the system are needed.

The according to the inventive method colored Cotton warp yarns can subjected to further treatment steps to achieve certain effects and then in usual woven and known to textile articles for the end user, in particular articles of clothing, are processed.

It but it is also possible the colored ones and on the surface Bleached cotton warp yarns without further treatment into textile articles to process and if necessary, then further treatment steps to make, that is to modify the already made-up goods. Of course it is it also possible both the colored and Bleached cotton warp yarns, as well as those made from them Textile articles subject to further treatment steps.

Of course, the according to the inventive method colored Cotton warp yarns also interwoven in mixture with other materials and to articles for be further processed by the end user. As an example Mixtures with spandex called.

The "inverse denim" effect of the invention colored and For example, bleached cotton warp yarns may be visible be made that the uncolored outer ring of the yarn by washing or other mechanical stress is removed and thereby the dark colored core comes to light.

In a further embodiment of the method according to the invention, the surface of the cotton warp yarn which has been decolorized in the bleaching step is stabilized in a third step. Thus, the "inverse-denim" effect can be enhanced by treating the surface with, for example, TiO ₂ in the presence of binders such as acrylate copolymer or polyurethane.

It is self-evident also possible, the said third step only at a time after the weaving of the cotton warp yarn, for example only on the ready-made textile product, make.

object The present invention also relates to textile articles, the cotton warp yarns contained, which are obtained by the process according to the invention. Such textile articles are, for example, unprocessed denim fabrics, but especially clothes like pants, skirts, Shirts, jackets etc. or other textile articles.

The The following examples serve to illustrate the invention. The Parts in the table examples are parts by weight.

example 1

A) dyeing step

A commercial, non-pretreated dry cotton warp yarn was dyed from a dyeing liquor of the following composition:
20 g / l indigo as commercial DyStar indigo cake 40% solution
2 g / l hydrosulfite (BASF hydrosulfite conc.)
20 g / l wetting agent (Primasol NF)
The pH of the liquor was 13.

The Yarn was dried at a temperature of 50 ° C in a dipping time of 25 Seconds dyed. Of the subsequent Aerial course lasted 120 seconds. It was then rinsed twice at 20 ° C with water.

It became a through colored Yarn with a high amount of indigo applied. A Dye analysis on the stained Yarn yielded 5.8%.

B) Bleaching step

The obtained according to A) colored Yarn was at a temperature of 25 ° C and a pH of 8.5 stained with potassium permanganate (20g / l). The contact time with the Bleaching bath was 18 seconds.

Subsequently, the yarn was fed directly into a bath of 30 g / l hydrosulfite (pH 8.5, temperature: 25 ° C) and then rinsed at 20 ° C. The cycle of bleaching, treating with hydrosulfite and rinsing was then repeated twice.

Example 2

A yarn dyed according to step A) of Example 1 was contained at a temperature of 25 ° C with a bath
200 g / l thickener (Monagum, 10%),
150 g / l caustic (Magnatrop W),
80 g / l moisturizer (etching enhancer HN),
10 g / l sodium hydroxide solution and
150 g / l Rongalit C
treated for 17 seconds, inter-dried and steamed for 1 minute at 102 ° C. It was then washed out at 60 ° C and then at 20 ° C.

Example 3

A yarn dyed according to step A) of Example 1 was intermediately dried on a contact dryer and then containing at a temperature of 30 ° C with a sizing bath
200 g / l binder (Perapret PU),
30 g / l thickener (Primasol AMK),
100 g / l white pigment (Acramin White DRN 01)
treated and then fixed on a contact dryer

The The following table examples describe further embodiments the method according to the invention. They are carried out analogously to the abovementioned Examples 1 to 3.

Claims (10)

Method for producing cotton warp yarns, the one "inverse Denim "effect, thereby characterized in that in an indigo dyeing plant in a dyeing step the cotton warp yarn with indigo at a dyeing temperature of 30 to 90 ° C and a Indigo concentration of 5 to 500 g / l is dyed in one go and in a subsequent one Bleaching step of indigo selectively on the surface of the cotton warp yarn discolored becomes. Method according to claim 1, characterized in that indigo in the form of a solution of leucoindigo is used. Method according to claim 2, characterized in that the leucoindigo by catalytic Hydrogenation has been made from indigo. Method according to one or more of the claims 1 to 3, characterized in that it in the presence of a wetting agent carried out becomes. Method according to claim 4, characterized in that the wetting agent in amounts of 10 to 50 g / l, more preferably 20 to 25 g / l is used. Method according to one or more of the claims 1 to 5, characterized in that the bleaching step means a bleaching bath, the potassium permanganate as a bleaching agent contains. Method according to one or more of the claims 1 to 6, characterized in that the bleaching step means a bleaching bath containing a thickener. Method according to one or more of the claims 1 to 7, characterized in that after Durchfärben the Cotton warp yarn in the dyeing step rinsed with water, bleached with permanganate, rinsed again and then with a bisulfite solution and the cycle of bleaching, rinsing and treating with bisulfite is repeated at least once. Method according to one or more of the claims 1 to 8, characterized in that in a to the bleaching step subsequent third step with the decolorized in the bleaching step surface of the cotton warp yarn one for Cotton suitable dye or pigment is dyed. Textile article, characterized in that it comprises cotton warp yarns contains according to a method according to a or more of claims 1 dyed to 9 are.