GB1579994A - Process for dyeing and printing textile materials - Google Patents

Description

(54) PROCESS FOR DYEING AND PRINTING TEXTILE MATERIALS (71) We, CASSELLA AKTIEN GESELLSCHAFT, formely Cassella Farbwerke Mainkur Aktiengesellschaft, a body corporate organised under the laws of the Federal Republic of Germany, of Hanauer Landstrasse 526, 6000 Fran kfurt(Main)- Fechenheim, Federal Republic of Germany, do hereby declare the invention for which we pray that a patent may be granted to us, and the method be which it is to be performed, to be particularly described in and by the following statement:- The invention relates to processes for dyeing or printing textile materials with sulphur dyestuffs or sulphur vat dyestuffs, in which the textile materials are treated with an alkali metal nitrate during or after the dyeing or printing operation, and are thereafter treated with an acid.

Sulphur dyestuffs and sulphur vat dyestuffs are applied in the reduced form to textiles to be dyed or printed. The dyeings or prints must be further treated with an oxidising agent in order to develop colour shade or to convert the reduced dyestuff into its original, water-insoluble oxidised form. Correctly executed reoxidation is a determining factor for the shade and, above all, for fastness properties, in particular for the fastness of the dyeings and prints towards wet processing and rubbing.

Reoxidation is therefore an important component of the entire dyeing and printing process. The customary oxidising agents are alkali metal bichromate/acetic acid, hydrogen peroxide and peroxide compounds, such as sodium perborate, sodium percarbonate or ammonium persulphate, sodium hypochlorite, alkali metal chlorite and bromite. alkali metal iodate and sodium tetrathionate. It is also customary, especially in the case of staple goods, to finish the dyeing only by rinsing.

Atmospheric oxygen acts as the oxidising agent here.

The oxidation processes used hitherto have various disadvantages: In the case of oxidation using chromate/acetic acid, bichromate/acetic acid or bichromate/copper sulphate, considerable dulling of the colour shade must frequently be put up with. A hardening or embrittlement of the dyed fibre material occurs through incorporation of chromiun atoms in the dyestuff which takes place, by chelate formation, alongside the oxidation, and this can lead to losses in strength and difficulties during the further processing and use of the dyed material.

Furthermore, in addition to the dyed materials becoming hydrophobic in the case of a number of dyestuffs, oxidation using bichromate has, above all, the disadvantage of polluting the effluents with toxic chromium-VI compounds, as a result of which these oxidation methods are increasingly abolished through legal effluent restrictions.

In the case of dyeing with sulphur dyestuffs, hydrogen peroxide and its derivatives in most cases significantly decrease the fastness of the dyeings to wet processing, especially if they are used in an alkaline medium.

The use of alkali metal hypochlorites as the oxidising agent is already problematic because of the poor fastness of most sulphur dyestuffs to chlorine.

In the case of alkali metal chlorites, the amount added and the oxidation temperature must be maintained precisely, which can cause problems in the case of a continuous process.

Alkali metal bromites have the disadvantage that the oxidation achieved is frequently incomplete and the fastness of the dyeings to wet processing are noticeably inferior to those of dyeings which have been oxidised using bichromate.

Alkali metal iodates give, in the acid range, good oxidation effects with fastness to washing, for example, in the case of bichromate oxidation. However, it is very expensive to use alkali metal iodates.

Oxidation using sodium tetrathionate is also too expensive.

Oxidation by means of atmospheric oxygen by "skying" or correspondingly productive rinsing processes proceeds relatively slowly and is associated with high consumption of water and is usually incomplete.

Attempts have also already been made to oxidise dyeings of reduce sulphur dyestuffs, after rinsing, in an aqueous sodium nitrite solution containing sulphuric acid (Egger, Joos, Aspland and Tigler "Die Oxidation reduzierter Schwefelfarbstoffe" ("The Oxidation of reduced Sulphur dyestuffs"), Textilveredelung 9 (1974), No. 8, pages 358-364). However, compared with other processes, in this process the poorest results are obtained both at 200C and at 700C, so that nitrite/sulphuric acid oxidation has been described as unsuitable.

According to the present invention there is provided a process for dyeing and printing a textile material with a sulphur dyestuff or a sulphur vat dyestuff, and thereafter treating the material with an oxidising agent, the textile material being treated with alkali metal nitrite during or after the dyeing or printing operation, and thereafter treated with an acid.

Outstanding results can be obtained using the present invention.

The present invention can be used both for dyeing piece goods, yarns and loose material (flocks), and for printing piece goods, either by discontinuous or halfcontinuous or continuous processes.

In the case of a discontinuous dyeing operation, for example in the case of machine dyeing, dyeing in ajig, a winch vat, or a jet, the treatment with alkali metal nitrite can be carried out after the actual dyeing operation. However, it has proved advantageous, in the case of a discontinuous dyeing operation, to add the alkali metal nitrite directly to the dyebath during the last minutes of the dyeing operation. For example, the last 5 to 20 minutes of the dyeing can be carried out with the addition of alkali metal nitrite to the dyebath. The alkali metal nitrite will, in general, be added to the dyebath about 10 minutes before expiry of the normal dyeing time. The alkali metal nitrite addition and the addition of sodium sulphate decahydrate which customarily takes place for better exhaustion of the bath carried out simultaneously.

In the case of continuous dyeing processes, a differentiation is essentially made between one-bath processes and twobath processes. In the case of one-bath processes, the padding liquor contains the reduced dyestuff, and in the case of twobath processes, the first padding liquor contains the dispersed or dissolved dyestuff and the second padding liquor contains the reducing agent. In these processes, fixing of the dyestuff takes place through a steaming process. In the case of the known continuous dyeing processes, it is possible to carry out the treatment according to the invention, of the textiles with sodium nitrite before or after the steaming process.It is usually advisable to carry out the treatment with sodium nitrite before the steaming process, because the alkali metal nitrite can then be added directly to the padding liquors and additional baths or treatment steps can thereby be avoided. In the case of the two-bath processes, the alkali metal nitrite is usually added to the second padding liquor, which contains the reducing agent.

In a printing operation it is preferable to add the alkali metal nitrite to the printing paste. In the case of printing pastes which are free from reducing agents, after drying, the print is preferably slop-padded with an alkaline solution of a reducing agent, then steamed and further processed.

In the case of printing pastes containing reducing agents, the print preferably is dried, steamed and further processed.

Sodium nitrite, potassium nitrite, rubidium nitrite and caesium nitrite can be used as the alkali metal nitrite for processes according to the invention. Sodium nitrite or potassium nitrite are usually used, for reasons of cost. It is also possible, of course, to use mixtures of two or more alkali metal nitrates, in particular mixtures of sodium nitrite and potassium nitrite. If the treatment of the textiles with alkali metal nitrite is carried out after the actual dyeing process or after any steaming process in the case of dyeing processes and after printing in the case of printing processes, this treatment can be effected by impregnating the textile materials with aqueous solution which usually contains 1 to 50 g/l, preferably 5 to 20 g/l, of alkali metal nitrite. If, in accordance with the invention, textiles are treated with an alkali metal nitrite during the dyeing operation, the alkali metal nitrite is preferably added to the dye bath or reducing agent bath, also in amounts of 1 to 50 g/l, preferably 5 to 20 g/l. If the alkali metal nitrite is added to a printing paste, amounts of 1 to 50 g/kg, preferably of 5 to 20 g/kg, are also preferably used.

Dyed or printed textiles are treated with an acid immediately after the treatment with an alkali metal nitrite. Depending on the process used, a further padding with reducing agents, drying or fixing of the dyestuff, for example by steaming, can optionally be carried out between the treatment with alkali metal nitrite and the acid treatment. However, rinsing between the nitrite treatment and the acid treatment should be omitted. The actual oxidation of the dyestuffs is effected by the acid treatment. In the treatment with the acid, the dyed or printing textiles are brought into contact with an aqueous acid solution, for example an aqueous solution of a mineral acid or a carboxylic acid. Examples of suitable mineral acids are sulphuric, phosphoric or hydrochloric acids.

Examples of suitable carboxylic acids are formic, acetic and propionic acids.

Aqueous solutions of acetic acid are preferred. The aqueous acid solution usually contains 1 to 20 ml/l, preferably 5-10 ml/l, of acid. The treatment with the acid is usually carried out at temperatures from 10 to 700 C. Textiles will generally be immersed only briefly, that is to say for 5 to 20 seconds, in the aqueous acid bath. The textiles are then preferably rinsed and neutralised of strong acids, such as sulphuric acid, and then finished.

The process according to the invention are preferably carried out as continuous one-bath or two-bath pad-steam processes, the alkali metal nitrite being added to the liquor of the reduced dyestuff in the case of a one-bath process and to the reducing liquor in the case of a two-bath process and the impregnated goods being steamed in the customary manner, for example for 3060 seconds at 102--1100C. Departing from the oxidation processes known hitherto, after leaving the steaming operation the goods are not rinsed but are oxidised in a bath containing dilute aqueous acid, for example about 5-20 seconds.

They can then be rinsed, appropriately neutralised and finished.

Processes according to the invention can be carried out with sulphur dyestuffs or sulphur vat dyestuffs. Sulphur dyestuffs are preferably used.

Sulphur dyestuffs can be manufactured by heating a sulphur melt or an aromatic nitrogen-containing compound and elemental sulphur or by boiling a sulphur melt of an aromatic compound with a polysulphide, an aliphatic alcohol and/or water. Insoluble sulphur dyestuffs, the structures of which are not known in detail, are thus obtained. The insoluble sulphur dyestuffs can be converted into watersoluble derivatives of thiosulphuric acid or their sodium salts, the so-called Bunte salts, using sulphite or bisulphite. In additon to the water-soluble and water-insoluble sulphur dyestuffs, sulphur dyestuff formulations which already contain the reducing agent necessary for dyeing are also commercially available. All the known modifications of sulphur dyestuffs can be employed in processes according to the invention.

Sodium sulphide is usually used as the reducing agent for converting waterinsoluble sulphur dyestuffs into the leuco form, which has an affinity for fibres.

Water-soluble sulphur dyestuffs are preferably reduced with sodium bisulphide (hydrosulphide). In the case of sulphur dyestuffs of the C.I. 53,630 Vat Blue 43 and C.I. 53,190 Sulphur Black 10 type, the reducing agent is usually hydrosulphite (sodium dithionite), which is also used as the reducing agent in vat dyeing. Sulphur dyestuffs of this type which are reduced with hydrosulphite are frequently summarised by the expression sulphur vat dyestuffs.

Examples of suitable sulphur dyestuffs for processes according to the invention are C.I. Sulphur Blue 1, C.I. Leuco Sulphur Blue 1, C.I. Sulphur Blue 3, C.I. Leuco Sulphur Blue 3, C.I. Sulphur Blue 4, C.I.

Solubilised Sulphur Blue 4, C.I. Sulphur Blue 5, C.I. Leuco Sulphur Blue 5, C.I.

Solubilised Sulphur Blue 5, C.I. Sulphur Blue 7, C.I. Leuco Sulphur Blue 7, C.I.

Solubilised Sulphur Blue 7, C.I. Sulphur Blue 10, C.I. Solubilised Sulphur Blue 10, C.I. Sulphur Blue 15, C.I. Leuco Sulphur Blue 15, C.I. Solubilised Sulphur Blue, C.I.

Sulphur Yellow 2, C.I. Leuco Sulphur Yellow 2, C.I. Solubilised Sulphur Yellow 2, C.I. Sulphur Yellow 4, C.I. Leuco Sulphur Yellow 4, C.I. Solubilised Sulphur Yellow 4, C.I. Leuco Sulphur Yellow 7, C.I. Sulphur Yellow 9, C.I.

Leuco Sulphur Yellow 9, C.I. Sulphur Green 2, C.I. Leuco Sulphur Green 2, C.I.

Solubilised Sulphur Green 2, C.I. Sulphur Green 3, C.I. Leuco Sulphur Green 3, C.I.

Solubilised Sulphur Green 3, C.I. Sulphur Green 5, C.I. Sulphur Brown 5, C.I. Leuco Sulphur Brown 5, C.I. Solubilised Sulphur Brown 5, C.I. Sulphur Brown 10, C.I.

Leuco Sulphur Brown 10, C.I. Sulphur Brown 16, C.I. Solubilised Sulphur Brown 16, C.I. Sulphur Brown 51, C.I. Solubilised Sulphur Brown 51, C.I. Sulphur Black 8, C.I. Sulphur Red 3, C.I. Solubilised Sulphur Red 3, C.I. Sulphur Red 7 and C.I.

Solubilised Sulphur Red 7.

Examples of suitable sulphur vat dyestuffs for processes according to the invention are C.I. Vat Blue 42, C.I.

Reduced Vat Blue 42, C.I. Vat Blue 43, C.I.

Reduced Vat Blue 43, C.I. Vat Blue 44, C.I.

Vat Blue 45, C.I. Vat Blue 47, C.I. Vat Blue 49, C.I. Vat Blue 50, C.I. Sulphur Black 10 and C.I. Leuco Sulphur Black 10.

Within the scope of the present invention, so-called "pseudo-sulphur dyestuffs" are also understood by the term sulphur dyestuffs. This term summarises organic pigments which can belong to various dyestuff classes and into which functional groups (for example thiocyano or mercapto groups) which impart the coloristic properties of a sulphur dyestuff to the dyestuff, have been introduced by a preparative route, that is to say not by boiling a sulphur melt or heating a sulphur melt. Examples of such suitable "Pseudosulphur dyestuffs" are: C.I. Sulphur Green 25 with a copper phthalocyanine molecule, the dyestuff of the formula

and C.I. Solubilised Sulphur Green 26.

Instead of the customary reducing agents for sulphur dyestuffs (sodium sulphide and sodium bisulphide) it is also possible to use other reducing agents for reducing the dyestuffs. Examples of reducing agents of this type are sodium hydroxide solution/glucose, sodium hydroxide solution/hydrosulphite or sodium hydroxide solution/hydrosulphitealdehyde compounds, such as formaldehyde-sodium sulphoxylate.

The formation of hydrogen sulphide during the acid treatment is prevented by using reducing agents of this type.

Any fibres which can customarily be dyed or printed with sulphur dyestuffs or sulphur vat dyestuffs can be dyed and printed by a process according to the invention, that is to say, for example, polyamide and modified acrylic fibres, but in particular cellulose fibres or mixtures containing cellulose fibres.

The advantages of processes according to the invention are, compared with oxidation using bichromate/sulphuric acid, that pollution of the effluent with chromium-VI compounds ceases and, compared with oxidation using peroxide, that the fastness to wet processing properties, in particular the fastness to washing, are significantly improved. A further advantage of processes according to the invention is the very short oxidation time required. Processes according to the invention can be carried out simply, rapidly and very safely: there is no danger at all of over-metering. In contrast to many other oxidation operations, no additional energy need be expended. The chemicals used and the products obtained are in all cases familar and do not add to the cost of the total dyeing process.

Unless otherwise indicated, the percentage data given in the Examples are data in per cent by weight. In Examples 8 and 9, "Leonil" and "Solegal" are registered Trade Marks.

Example 1 19 g of the dyestuff C.I. No. 53,327, Leuco Sulphur Brown 51, were dissolved with 10 g of sodium nitrite, 5 g of sodium bisulphide, 4 g/l of sodium carbonate and 5 g of a sodium polysulphide solution (average S content of 2-5 atoms of S per molecule) and the solution was made up to a total volume of 1 litre. A light cotton twill was padded with this solution with a liquor pick-up of 80% and then steamed at 102--105"C for I minute. Immediately thereafter, the material was passed at room temperature through a bath containing 20 ml/l of concentrated sulphuric acid, rinsed, neutralised and finished. A medium-depth clear brown dyeing resulted. Slightly better results are obtained if a bath containing 20 ml/l of 60% strength acetic acid is used for the acid treatment.

If the padding is carried out without the addition of 10 g/l of sodium nitrite and, after steaming, the goods are treated with 2 g/l of bichromate and 5 ml/l of 60% strength acetic acid at 7--800C instead of with sulphuric acid, a somewhat duller dyeing results.

Examples 2 to 4 Cotton material was dyed with the dyestuffs listed in the table which follows by the same process as indicated in Example 1.

2. 20 g/l of the dyestuff C.I. No. 53,285, Leuco Sulphur Brown 16, grey-brown; 3. 14 g/l of the dyestuff of the structural formula indicated on page 11 and 4. 18 g/l of the dyestuff C.I. No. 53,720, Leuco Sulphur Red 6, red-brown.

Deep level dyeings were obtained in all cases.

Example 5 12 g of the sulphur vat dyestuff C.I. No.

53,630 are vatted with 40 g of sodium hydroxide solution of degree Bé strength 38 and 35 g of sodium dithionite, 10 g of sodium nitrite are also added to this solution and the solution is made up to a total volume of 1 1. Cotton nettle is padded with this solution (liquor pick-up 78%) and the procedure followed is otherwise as in Example 1.

A blue dyeing which is suprisingly clear for sulphur vat dyestuffs results.

Example 6 16 g of the dyestuff C.l. No. 53,010, Sulphur Yellow 9, are boiled 1+ times the amount of industrial sodium sulphide and the sodium polysulphide solution indicated in Example I are added and the procedure followed is as in Example 1. A perfect uniform yellow dyeing results.

Example 7 Similar results are obtained in accordance with the instructions of Example 1 if a combination of 10 g/l of the dyestuff C.I. No. 53,175, Sulphur Green 8, and 1 g/l of the dyestuff C.I. No. 53,010, Sulphur Yellow 9, is used. A perfectly uniform olive dyeing is obtained.

Example 8 A liquor containing 80 g/l of C.I.

solubilised Sulphur Brown 16 and 5 ml/l of Leonil AH (padding auxiliary) is padded onto a cotton fabric. The liquor pick-up is 80%. The padded fabric is dried at 10-120"C and then impregnated with a reducing liquor which contains 80 ml/l of Sulfhydrat F 150, 20 g/l of sodium carbonate at 15 g/l of sodium nitirite. The fabric is then steamed at 100--1030C for 1 minute and oxidised in a bath containing 20 mV1 of 60% strength acetic acid at 200C for 10 seconds. It is then rinsed and finished. A strong, uniform brown dyeing results.

Example 9 Cotton yarn is dyed, at a liquor ratio of 1:10, in a dyebath containing 4.5% of Immedial Direct Blue RL extra concentrated, C.I. 53,235 Sulphur Blue 11, and 7% of Na2S (60% strength) at 900C for 50 minutes. 5 g/l of sodium nitrite and 20 g/l of sodium sulphate decahydrate are then added to the dyebath and dyeing is continued for a further 10 minutes. The bath is then drained off and the goods are treated in a bath containing 5 ml/l of acetic acid (60% strength) and I g/l of Solegal A for 20 seconds. The goods are then rinsed and finished. A clear, level dyeing was obtained.

WHAT WE CLAIM IS: 1. A process for dyeing and printing a textile material with a sulphur dyestuff or a sulphur vat dyestuff, and thereafter treating the material with an oxidising agent, the textile material being treated with alkali metal nitrite during or after the dyeing or printing operation, and thereafter with an acrid.

2. A process according to claim 1, which is carried out continuously.

3, A process according to either of claims 1 to 2, wherein sodium nitrite is used as the alkali metal nitrite.

4. A process according to either of claims 1 or 2, wherein potassium nitrite is used as the alkali metal nitrite.

5. A process according to any one of claims I to 4, wherein the textile materials are treated with an aqueous solution containing 1 to 50 g of the alkali metal nitrite per litre.

6. A process according to any one of claims 1 to 4, wherein the textile material is treated with an aqueous solution containing 5 to 20 g of the alkali metal nitrite per litre.

7. A process according to any one ot claims I to 6, wherein the acid treatment is carried out with an aqueous sulphuric acid solution.

8. A process according to any one of claims 1 to 6, wherein the acid treatment is carried out with an aqueous acetic solution.

9. A process according to any one of claims 1 to 8, wherein the acid treatment is affected using an aqueous solution which contains 1 to 20 ml/l of acid.

10. A process according to any one of claims 1 to 8, wherein the acid treatment is effected using an aqueous solution which contains 5 to 10 ml/l of acid.

11. A process according to any one of claims 1 to 10, wherein the dyestuff is fixed on the textile before the acid treatment.

12. A process according to claim 1, substantially as herein described.

13. A process for dyeing and printing a textile material, substantially as herein described in any of the Examples.

14. A textile material treated by a process according to any one of the preceding

Claims (1)

1. claims.