WO1993019240A1 - Process for dyeing textiles made from cellulose fibres by means of vat dyes and without reducing agents - Google Patents

Abstract

Process for dyeing and printing textile materials which consist of cellulose fibers or which contain cellulose fibers in admixture with other fibers, in an aqueous bath at pH values above 12 and at temperatures of at least 100 ° C, with vat dyes and in the absence of the reducers usually used for vat dyes, at alkali hydroxide concentrations in the bath of between 20 and 50 ml of aqueous alkaline detergent at 38 ° Bé per liter of bath. Completion of the dye in the usual way.

Description

Process for dyeing textile materials from cellulose fibers

description

The invention relates to a process for dyeing textile materials which consist of cellulose fibers or contain cellulose fibers in a mixture with synthetic fibers in an aqueous liquor at pH values above 12 and temperatures of at least 100 ° C. with viable dyes.

When dyeing cellulose fibers with vat dyes, in particular with indigo, sodium dithionite (hydrosulfite), thiourea dioxide (formamidinesulfinic acid) or hydroxyacetone are used as reducing agents. In all cases one works in the presence of alkali and at pH values of at least 12. Sodium dithionite and thiourea dioxide are very effective reducing agents, but they also have disadvantages. For example, the use of hydrosulfite or thiourea dioxide in dyeing places a load on the wastewater with sulfite and sulfate ions.

From DE-A-2 011 387 it is known to use thiourea dioxide as a reducing agent in the dyeing of textiles containing cellulose fibers. The reduction of vat dyes can additionally be carried out in the presence of glucose in order to prevent sensitive dyes from being reduced too much.

EP-A-0 364 752 discloses a process for dyeing cellulose fibers with vat dyes in alkaline aqueous medium, in which mixtures of, for example, sodium dithionite and α-hydroxycarbonyl compounds, e.g. Hydroxyacetone, in a weight ratio of 1: 1 to 1:15, and the dyeing is carried out at pH values of at least 13 and at temperatures above 75 ° C.

EP-A-0 357 548 also discloses a process for dyeing textile materials made from cellulose fibers with vat dyes in the presence of reducing agents and alkali, in which ent to reduce vat dyes used diols and additionally used organic water-miscible solvents, such as alcohols, acetone, cyclohexanone, formamide or acetamide. As can be seen from the two recently discussed literature references, a further component is additionally required for the safe reduction of vat dyes, in particular of In¬ digo, with α-hydroxycarbonyl compounds. If the vat dyes are reduced solely with α-hydroxycarbonyl compounds, dyeings in practice result in precipitations of incompletely reduced dyes, in particular reoxidized indigo.

DE-B-2 164 463 discloses a process for dyeing and printing textile materials with vat dyes, in which the reduction of the vat dyes in aqueous

Medium at a pH of at least 12 with hydroxyacetone in the presence of quinoid compounds which are water-soluble under staining conditions.

As is apparent from the prior art described above, in the known dyeing processes with vat dyes, a reducing agent is added to the alkaline dye bath in order to convert the insoluble dye pigment into the reduced, water-soluble leuco compound. Only this leuco compound is absorbed on the cellulose fibers and is anchored there as a pigment after the reoxidation.

The object of the present invention is to provide an improved process for dyeing cellulose fibers with combinable dyes compared to the prior art described above, which is ecologically more favorable than the known processes. The wastewater from the dyeing plant should not be contaminated to the same extent with sulfur compounds or organic compounds as the wastewater that occurs in the conventional vat dyeing process.

The object is achieved according to the invention with a process for dyeing and printing textile materials which consist of cellulose fibers or contain cellulose fibers in a mixture with other fibers, which can be combined in an aqueous liquor at pH values above 12 and temperatures of at least 100 ° C. Dyes, if the dyeing in the absence of the usual reducing agents for the combinable dye Substances with a concentration of alkali metal hydroxide in the liquor of 20 to 500 ml of aqueous alkali metal solution at 38 ° Be / 1 liquor and the dyeing is then completed in the usual way.

The textile materials consist of cellulose fibers or contain cellulose fibers in a mixture with other fibers. They can be in any processing state, e.g. as a flake, card sliver, yarn, skein, fabric or knitted fabric. The cellulose fibers can either be natural or regenerated cellulose, such as cellulose, viscose or poly- nosic fibers. The process according to the invention can be used to dye both mercerized cotton as raw cotton and raw yarn which is present as a package or as a skein. Synthetic fibers which are present in the textile materials in a mixture with cellulose fibers are, for example, polyester fibers, polyacrylonitrile fibers or synthetic polyamide fibers.

The cellulose fibers are dyed with viable dyes, such as vat dyes, in particular indigo, or sulfur dyes. The vat dyes are either indigo or anthraquinone or indigoide dyes. Vat dyes and sulfur dyes have been commercially available for a long time and are documented in the Color Index (C.I.), cf. Color Index, 3rd edition 1971, volume 3, pages 3719 to 3844 and volume 4, C.I. 58000 to 74000, Soc. Dyers and Coluristes, England.

In the process according to the invention, the combinable dyes are used in the amounts which have hitherto been customary in dyeing, for example in the range from 0.01 to 10% by weight, based on the textile material. A single or a mixture of two or more combinable dyes can be used here. The textile materials can be dyed, for example, from a long aqueous liquor at a liquor ratio of 1: 5 to 1:40, preferably 1: 8 to 1:20, or else in the continuous process, for example padding process. The liquor ratios used here are from 1: 0.5 to 1: 3. Textile materials can also be printed using the process according to the invention. The pH of the aqueous liquors is above 12. It is adjusted by adding alkali metal hydroxides to the aqueous dyeing medium. Suitable alkali metal hydroxides are sodium hydroxide and potassium hydroxide, preference being given to using sodium hydroxide solution as the alkali metal hydroxide. The concentration of the alkali metal hydroxide in the aqueous dye liquor is 20 to 500, preferably 40 to 300 ml of aqueous alkali metal solution at 38 ° Be / l liquor. For most practical applications, alkali hydroxide amounts of 40 to 80 ml of 38 ° Be aqueous alkali hydroxide per liter of liquor are sufficient.

For dyeing, the textile materials are introduced into the aqueous alkaline liquor which contains at least one combinable dye and, if appropriate, other customary dyeing aids. According to the invention, the dyeing with the viable dyes takes place in the absence of the customary reducing agents for these dyes at temperatures of at least 100 ° C., preferably at temperatures of 110 to 160 ° C. In most cases the dyeing temperatures are in the range of 120 to 135 ° C. Due to the high dyeing temperatures, the dyeings must be carried out in closed, pressure-tight dyeing machines. The printing devices that are suitable for this are known. Compared to the known vat dyeing process, a higher amount of alkali metal hydroxide is required in the process according to the invention. Under the dyeing conditions described above, i.e. Temperatures of at least 100 ° C and a relatively high amount of alkali hydroxide, the combinable dyes - surprisingly without the addition of the usual reducing agents required - are converted into the leuco form, which is soluble in the aqueous alkaline liquor and onto the cellulose fibers of the textile materials is raising. To date, no studies have been carried out on the reaction mechanism of the formation of the leuco compounds from the combinable dyes.

The dyeing can be combined with a lye of the textile materials made of cellulose fibers. In addition, it is possible to dye textile materials made from cellulose fibers, the warp threads of which are sized with starch, without first removing the size film. During the dyeing process there is a detachment of the sizing films from the warp yarns of the fabrics, so that one too It is possible to dye the warp yarns. It has also proven to be advantageous to carry out the process according to the invention in the presence of polysaccharides, for example cellulose, starch and degraded starch. As cellulose, which is added to the dyeing bath, also paper or pulp can encrypt ^'applies.

In order to accelerate the dyeing process, it has proven advantageous in some cases that the dyeing or printing is additionally carried out in the presence of chinoid compounds which are water-soluble at pH values above 12. These compounds are dissolved in the aqueous liquor under the dyeing conditions. Suitable chinoid compounds which are suitable for this purpose are known from DE-B-2 164 463 described at the beginning. Quinoid compounds are, for example, derivatives of benzoquinone, naphthoquinone, acenaphthoquinone or anthraquinone, such as hydroxyanthraquinones, e.g., hydroxy, carboxylic acid and / or sulfonic acid groups. 2-hydroxyanthraquinone and 1,4-dihydroxyanthraquinone, anthraquinone carboxylic acids, anthraquinone sulfonic acids such as anthraquinone-2-sulfonic acid and 1,4-diaminoanthraquinone-2-sulfonic acid. These compounds are common as accelerators in vat dyeing. The chinoid compounds are used in amounts of 1 to 10% by weight, based on the amount of the dye used.

In addition to at least one combinable dye, the alkaline-aqueous dyeing liquor can additionally contain polymers of mono-ethylenically unsaturated carboxylic acids as dyeing aids. Such coloring aids are known for example from DE-B-2 444 823. It is about this. essentially homo- and copolymers of monoethylenically unsaturated carboxylic acids. The copolymers contain at least 10% by weight of a monoethylenically unsaturated carboxylic acid copolymerized. Individual compounds of this type are, for example, polyacrylic acid, polymethacrylic acid, copolymers of acrylic acid and acrylamide, copolymers of acrylic acid and acrylonitrile, methacrylonitrile, acrylic acid esters and / or methacrylic acid esters. Copolymers of acrylic acid and maleic acid, copolymers of acrylic acid and itaconic acid, copolymers of maleic acid and vinyl esters, copolymers of maleic acid are also suitable and Vin ether. It is only essential that the copolymers contain at least 10, preferably at least 50 mol% of a monoethylenically unsaturated carboxylic acid in copolymerized form. The copolymers can be used as coloring aids in the form of the free acids or, preferably, in a form already neutralized with alkali metal solutions. The K- ^' values of the homo- and copolymers of monoethylenically unsaturated carboxylic acids are 15 to 90 and are preferably in the range from 20 to 65. The .K values are determined according to H. Fikentscher, Cellulosechemie, Volume 13 , 58-64 and 71-74 (1932) in aqueous solution at a temperature of 25 ° C and a concentration of 1 wt .-% at pH 7 on the sodium salt of the polymers. The polymers are used in amounts of 0.05 to 2% by weight, based on the textile materials to be dyed.

The textile material, which after the treatment in the dyebath contains the linked dye in the leuco form, is treated in the usual way to complete the dyeings. For this purpose, the textile material is first oxidized according to the methods used in vat dyeing, e.g. Staying in the air of the material containing the leuco dye or treating this material with an aqueous liquor which contains hydrogen peroxide or another oxidizing agent. After the oxidation, the dyed textile material is rinsed and soaped. However, the dyeing can also be completed in such a way that the textile material which contains the vat dye in the leuco form is first rinsed, then oxidized and then soaped. A soap-containing aqueous solution is usually used for soaping, which may also contain dissolved soda. One obtains rubbing and washable dyeings, the wastewater from the dyeing plants not being contaminated with sulfate or sulfite ions or other compounds derived from reducing agents.

Examples

example 1

A bleached cotton jersey in an aqueous dye liquor containing 0.5 g / l of the blue vat dye of CI no. 69825 and Contains 60 ml aqueous sodium hydroxide solution 38 ° Be per liter of liquor, colored at a liquor ratio of 1:20. For this purpose, the material to be dyed is brought into the bath at a temperature of 25 ° C., the dyeing apparatus is closed in a pressure-tight manner and the contents are heated to a temperature of 130 ° C. within 20 minutes, this temperature is kept approximately constant for 30 minutes and the contents are cooled Dyeing apparatus then to a temperature of 60 ° C within 20 minutes. The cotton jersey is removed from the fleet and hung on a line. The leuco form of the vat dye is oxidized by the action of air-oxygen. The blue-colored cotton jersey is then rinsed with cold water and then soaped by treating it with a liquor which contains 1 g / 1 of a commercially available anionic surfactant and 0.5 g / 1 soda. In this way, a rubbing and washable blue color is obtained.

The coloring is not over-reduced despite the high dyeing temperature and despite the absence of substances to protect against over-reduction (glucose).

Example 2

A bleached cotton jersey is placed in a pressure-sealable laboratory dyeing machine in which an aqueous dye liquor has been placed which contains 0.5 g / l of the green vat dye of C.I. 59825 and 60 ml of aqueous sodium hydroxide solution containing 38 ° Be / l liquor. The dyeing apparatus is sealed pressure-tight and its contents are heated from a temperature of 25 to 130 ° C. within 20 minutes. The coloring itself is carried out at a temperature of 130 ° C within 30 minutes. The contents of the dyeing apparatus are then cooled to a temperature of 60 ° C. within 20 minutes and the cotton jersey is removed. The oxidation of the leuco compound of the vat dye, which is due to the

Cotton jersey is put on, then takes place in a liquor that contains 2 ml of 30% hydrogen peroxide per liter of liquor. The oxidation is complete after about 15 minutes at a temperature of 30 ° C. The material to be dyed is then rinsed cold and soaped with a liquor containing 1 g / 1 of a commercially available anionic surfactant and 0.5 g / 1 Contains soda. You get a rubbing and washable green color of the cotton jersey.

Example 3

Example 1 is repeated with the only exception that the black vat dye of C.I. 69525 currently You get a black dyed cotton jersey that is dyed rub and washable.

Example 4

Example 2 is repeated with the only exception that the concentration of aqueous sodium hydroxide solution is increased to 300 ml sodium hydroxide solution, 38 ° Be / l liquor. You get a rubbing and washable green color.

Comparative Example 1

A bleached cotton jersey is made within 45 minutes using the known dyeing process. dyed at a temperature of 60 ° C. in an aqueous liquor, the 15 ml aqueous sodium hydroxide solution 38 ° Be per liter liquor, 6 g / 1 sodium dithionite and 0.5 g / 1 of the green vat dye of C.I. 59825. included. This coloration has approximately the same depth of color as the coloration obtained according to Example 4.

Example 5

Example 3 is repeated with the only exception that the concentration of the sodium hydroxide solution is increased to 300 ml of aqueous sodium hydroxide solution at 38 ° Be. A rubbing and washable black color is obtained.

Comparative Example 2

A bleached cotton jersey is at a temperature of 60 ° C within 45 min. dyed with an aqueous liquor containing 0.5 g / 1 of the black vat dye of CI No. 69525, 15 ml of 38 ° Be aqueous sodium hydroxide solution per liter of liquor and 6 g / 1 of sodium dithionite. The coloring is completed as described in Example 1. A comparison of the coloring thus obtained with that of Example 5 shows that the Coloring according to Example 5 is more than 20% deeper than that obtained by the known method.

Claims

Claims 1. Process for dyeing and printing textile materials, which consist of cellulose fibers or contain cellulose fibers in a mixture with other fibers, in an aqueous liquor at pH values above 12 and temperatures of at least 100 ° C with viable dyes, characterized in that the dyeing is carried out in the absence of the customary reducing agents for the viable dyes at a concentration of alkali metal hydroxide in the liquor of 20 to 500 ml of aqueous alkali metal hydroxide solution at 38 ° Be per liter of liquor and the dyeing is then carried out in the customary manner Way completed. 2. The method according to claim 1, characterized in that the concentration of the alkali metal hydroxide is 50 to 300 ml of aqueous alkali metal hydroxide solution at 38 ° Be per liter of liquor. 3. The method according to claim 1 or 2, characterized gekennzeich¬ net that sodium hydroxide solution is used as alkali hydroxide and the dyeing is carried out at temperatures from 120 to 135 ° C. 4. The method according to any one of claims 1 to 3, characterized ge indicates that the dyeing or printing is additionally carried out in the presence of quinoid compounds which are water-soluble at pH values above 12. 5. The method according to any one of claims 1 to 4, characterized ge indicates that the liquor additionally contains polymers of monoethylenically unsaturated carboxylic acids as colorants.