GB2032965A - Process for the Uniform Fast Dyeing of Wool Having an Anti-felt Finish With Metal-complex Dyes - Google Patents

Abstract

A process for the uniform fast dyeing of wool coated with a polyimine resin or a polyacrylic resin as anti-felting agents using metal- complex dyes containing sulphonic acid groups comprises dyeing such wool in a slightly acid medium with an aqueous solution of one or several 1:2 metal complex compounds of non- fibre reactive azo dyes having at most two sulphonic acid or sulphonate groups in the molecule or in which the sulphonic acid or sulphonate groups have been partially replaced by carboxylic acid or carbonate groups that do not participate in the complex formation at a temperature of from 100 to 106 DEG C according to the exhaustion process and subjecting the resulting dyeings upon completion of the actual dyeing operation to an after treatment with a diluted aqueous solution of ammonia for 10 to 30 minutes at a temperature of from 40 to 60 DEG C.

Description

SPECIFICATION Process for the Uniform Fast Dyeing of Wool having an Anti-felt Finish with Metal-complex Dyes The present invention relates to the uniform fast dyeing of wool coated with a polyimine resin or a polyacrylic resin as anti-felting agent using metal-complex dyes containing sulphonic acid groups.

Hitherto, wool fibres which have been subjected to an "anti-felt" finishing process, generally designated "superwash" treated wool, could only be dyed uniformly with reactive dyes in deep shades having satisfactory fastness properties to wetting. A textile article pre-treated in the above manner resists the rather severe strain imposed thereon during repeated washes at 600C with perborate-containing household detergents without felting and hence, it must have satisfactory colour-fastness. This property is not required of untreated wool that would not behave in this way.Wool fibers coated, for example with plastics such as a polyimine or polyacrylic resin (cf. inter alia Melliand Textilberichte 9/1971, page 1100 or Journal of the Society of Dyers and Colourists, volume 88, No. 3/1972, pages 93-100) have a completely different behaviour during dyeing compared with a wool fibre not coated with the above-specified resins. This different behaviour can be attributed to the fact that new groups are formed by the anti-felt finish which have an affinity for the saltlike or reactive bonds of dyestuffs.

The finish applied to the fibre as a film distinctly increases the dyestuff affinity. This means that to obtain dyeings having a good fibre and surface leveiness a special dyeing process must be developed together with the selection of suitable auxiliaries and dyestuffs having optimum properties for the dyeing. This prerequisite is the mors important, since the differences in affinity due to the material used, which are characteristic of polyamide fibres, are increased by the conventional anti-felt finishing operations or by felting-impairing treatments of the wool.

However, when using for this purpose metalcomplex dyes which have generally proved advantageous when deep shades are required, the fastness properties to wear and tear of the dyeings obtained on this special wool fibre are generally considered to be unsatisfactory. In particular black, navy-blue or dark-brown shades do not meet the specifications obligatory for "Superwash" knitted goods and for hand knitting yarn of the International Wool Secretariat, Department IWS Mark AG, in the case of IWS-TM 174 (test method for alkaline fasntess to perspiration) and of IWS-TM 1 93 (test method for fastness to washing). However, as is commonly known very good fastness properties can be obtained when applying this class of dyestuffs to normal wool, i.e. wool without an anti-felt finish.

It is also known from Melliand Textilberichte 12/1968, pages 1444-1448, from Textilveredlung 11/1976, pages 250-254 and from the relevant pattern cards of the dyestuffs manufacturers, to subject both untreated wool fibres and those having an anti-felt finish that have been dyed with specified reactive dyes, to an aftertreatment with ammonia to improve their fastness properties to wetting (reactive bond).

This aftertreatment is carried out to remove dyestuff particles that have not been completely bound to the fibre orto complete the reactive bond of the dyestuffs to the fibre. Ammonia is either added before the end of the dyeing or to the exhausted dye bath, generally for a period of 1 5 minutes at from 80 to 1000C, at well defined pH values between 7.5 and 8.5. Ammonia and soap have been used for a long time for the aftertreatment of wool, but ammonia has been used exclusively for the improvement of the fastness to wetting with reactive dyes in recent years only.Analogous measures also aiming at improving the fastness to wetting using alkaline compounds at the boiling temperature of the dyebath or at a slightly lower temperature have been proposed in German Patent 1,258,821 for dyeings of wool without an anti-feit finish using non-reactive, sulphonated copper phthalocyanine dyes.

The present invention seeks to provide for the use of metal-complex dyestuffs on wool fibres treated with an anti-felt finish consisting of a polyimine or polyacrylic resin. The use of this class of dyestuffs is intended in particular to produce by the exhaustion process dark shades complying with the requirements for the fastness properties to wetting imposed by IWS.

This task is achieved according to the invention by dyeing wool having an anti-felt finish in a slightly acid medium with an aqueous solution of one or several 1:2 metal complex compounds of non-fibre reactive azo dyes having at most two sulphonic acid or sulphonate groups in the molecule, at a temperature of from 100 to 1060C according to the exhaustion process and subjecting the resulting dyeings upon completion of the actual dyeing operation to an aftertreatment with a diluted aqueous solution of ammonia for 10 to 30 minutes at a temperature of from 40 to 600C.

The process according to the present invention is performed either in one bath or in two baths.

The exhaustion dyeing phase using metalcomplex dyes containing sulphonic acid groups is carried out under the usual conditions for dyeing untreated wool at boiling temperature or in the higher temperature range of from 103 to 1060C, followed, generally without intermediate drying, by an aftertreatment which is carried out either in the exhausted dyebath without change of the bath, or in a fresh aftertreatment bath. If desired, dispersing agents may be added to the aftertreatment bath. The feed quantity of ammonia is in the range of from 0.1 to 3 cm3/1, preferably of from 0.5 to 2 cm3/l of ammonia (25%). Thus a slightly alkaline medium is obtained during the latter process. After the aftertreatment the dyed material is rinsed and acidified.

The aftertreatment of the dyeings according to the invention using metal-complex dyes containing sulphonic acid groups was by no means obvious. It has never before been applied in practice to normal, untreated wool, when the above kind of dyestuffs have been used. The reason therefore is that dyeings obtained with the above type of dyestuffs on untreated wool have satisfactory fastness properties to wetting and thus subsequent measures for improving these properties were considered superfluous. However, the situation changed as the use of wool provided with an anti-felt finish proceeded, since the polyimine or polyacrylic resin film applied to the wool fibre substantially modifies the said fastness properties to wetting.Consequently, the fastness values listed on the pattern cards for dyeings, which are guaranteed for dyeings on normal wool, cannot be transferred to wool having an anti-felt finish. An aftertreatment with ammonia of dyeings on normal wool fibres carried out with metal-complex dyestuffs on the other hand does not result in an improvement of the said fastness properties. On the contrary, the shade is even somewhat brightened and thus the after treatment rather adversely affects the resulting dyeings.

The quality-improving effect of dyeings on wool having anti-felt finish by an aftertreatment with ammonia is far more pronounced when using metal-complex dyestuffs containing sulphonic acid groups than when using reactive dyes. It is extremely surprising and was not to be expected that the fastness to wetting would be improved to such a degree in accordance with the present invention. This improvement depends on the shade and on the colour depth and it may be equal to one and a half to two fastness values with medium shades and up to three and a half fastness values with navy-blue and black shades.

Thus the level required by IWS for fastness properties is obtained in all cases and even sometimes exceeded.

Aftertreatment with ammonia is certainly known in the state of the art but hitherto it has only been carried out at boiling temperature or at a temperature slightly below and it is thus extremely surprising that the process of the invention enables this aftertreatment to be carried out at a temperature between 40 and 600 C, i.e.

under conditions that are very mild for wool fibres, but nevertheiess this enormous improvement in fastness to wetting can be achieved.

Owing to the use of metal-complex dyes containing sulphonic acid groups that are very easily soluble in water the range of suitable dyestuffs becomes wider and it is much easier to produce deep shades. A particular advantage of the process of the invention is that shades for example dark-blue, navy-blue, black-brown, antracite and black need no longer be produced only with reactive dyes. The metal-complex dyes give deeper shades than the reactive dyes hitherto used for this purpose and consequently, lower quantities thereof are needed. Thus the process is more economic and safer, since the quantity of dyestuff in the dyebath is reduced. The dyebath is less polluted in the process of the invention owing to the reduced consumption of dyestuff, in particular with deep shades, than in the hitherto used common dyeing processes using reactive dyes.

Moreover it was not to be expected that exhaustion dyeings according to the invention using metal-complex dyes containing sulphonic acid groups could be carried out without the addition of auxiliaries. Owing to the nature of these dyes, the use of the levelling agents currently employed for the dyeing of wool can be dispensed with. Nevertheless very level dyeings are obtained. The use of retarding agents inhibiting the fixation of the dyestuffs, can also be dispensed with in this process. It goes without saying that under particular circumstances the presence of small quantities of auxiliaries as indicated above may be advantageous. In such cases, this addition would not be injurious and would not impair the fastness properties of the wool dyeings obtained in this manner. Under the conditions of the invention the dyebath is far more stable and the dyeing process is easier to carry out.Moreover the waste water pollution is greatly reduced since metal-complex dyes containing sulphonic acid groups, contrary to the hitherto used reactive dyes, exhaust the dyebath more or less completely. From this fact it can be deduced that the residual bath contains practically none of the feed dyestuffs unconsumed by the exhaustion process and, consequently, the new process can be widely used.

Suitable dyestuffs for the process of the invention are 1:2 metal-complex compounds of non-fibre reactive azo dyes, in particular monoazo dyes, i.e. complex compounds wherein 2 molecules of an azo dye or one molecule each of two different azo dyes are bound in complex manner to a metal atom. The complex compound may contain, for example, one disazo dye and one monoazo dye or preferably two identical or different monoazo dyestuff molecules. These dyestuffs have one to at most two sulphonic acid (-SO3H) or sulphonate (-SO3Me) groups per molecule which can be spread over the complex in any manner, preferably however, they are bound to aromatic radicals of the chromophore.

The metal-complex-forming groups in these azo dyes are preferably o,o'-dihydroxyazo groupings or o-hydro-o'-carboxyazo groupings, but ohydroxy-o'-carboxymethoxy or o-hydroxy-o'aminoazo groupings are also suitable. Suitable metal atoms bound in complex manner in these dyestuffs are chromium, cobalt, copper or nickel.

Dyestuffs of this kind are currently known and are listed in the Colour Index, 3rd edition 1 971 as "Acid Dyes".

In principle. 1:2 metal-complex dyes may alternatively be used in the process of the invention, wherein the above-mentioned sulphonic acid or sulphate groups have been partially replaced by carboxylic acid (--COOH) or carbonate groups (-COOMe), which do not participate in complex formation and must hence be considered as hydrosolubilizing groups.

According to the process of the invention yarns or tops treated with polyimine or polyacrylic resins or any textiles produced with these wool fibres may be dyed. The process is also suitable for the dying of the wool fibre portion of fibre blends treated in the above-specified manner.

The following examples illustrate the invention: Example 1: Knitting yarn consisting of wool having an antifelt finish in accordance with the method specified in ISDC, volume 88/3, pages 93-100, was dyed at a good-to-liquor ratio of 1:20 in the following manner: An aqueus dyebath at 400C was supplemented with 4% of ammonium sulphate (referred to the weight of the dry goods) and subsequently the pH of the bath was adjusted to a value of approximately 5 with acetic acid. The goods to be dyed were introduced into the bath and contacted with the bath in motion for about 5 minutes at 400C; 2% (referred to the weight of the goods) of the 1:2 chrome-complex dye containing sulphonic acid grous Acid Violet 90 (C.I. No. 18,762) were then dissolved in water and added to the dyebath.The dyebath was heated to the boil for 45 minutes and the fibrous material dyed for 60 minutes at boiling temperature. The actual dyeing process is thus complete.

The aftertreatment comprised the following steps: a) Conventional treatment as for untreated wool: The dyebath and the dyed material were cooled to 700C, the bath is withdrawn from the dyeing vessel and the dyed yarn rinsed with water at 700C. The aftertreatment was terminated by rinsing the resulting dyeing until clear by slowly adding cold water into the overflow.

b) Treatment according to the invention: The dyebath and the dyed material were cooled to 50"C, and subsequently without changing the bath about 4% (referred to the weight of the goods) of aqueous ammonia solution (25%) were added. The yarn was treated therewith for 30 minutes at 500C. Finally the resulting dyeing was rinsed with warm and with cold water and the aftertreatment carried to completion.

c) Treatment according to the invention: The dyebath and the dyed material were cooled to 70"C and the bath withdrawn from the dyeing vessel. The dyed yarn was rinsed with water at 700C, cold water added until the bath temperature was 400C about 2% (referred to the weight of the goods) of aqueous ammonia solution (25%) were then added and the goods treated for 30 minutes at 400C. Finally the dyeing was rinsed with warm and with cold water and the after treatment completed.

According to the above procedure a bordeaux dyeing having a standard depth of 1/1 was obtained on the wool yarns having an anti-felt finish.

The dyeings aftertreated by the different methods a), b), c) were subjected to fastness tests according to IWS standards and showed improved fastness properties to wetting of the dyeings b) and c) aftertreated with ammonia.

-The aftertreatment with ammonia b) and c) obviously greatly improved the fastness properties to wetting as compared to the conventional aftertreatment without impairing the shade or the colour depth. The improvement in the fastness properties to wetting amounted to two degrees of the grey card.

No diminution of the fibre quality during the treatment with ammonia under said conditions occurred, since the resin coating additionally acted as a protective layer for the wool having an anti-felt finish.

When using for the above dyeing process 3.3% (referred to the weight of the goods) of the blue 1:2 chrome-complex dye containing sulphonic acid groups Acid Blue 193 (C.l. No. 1 5,707), instead of the above-mentioned dyestuff a blue coloration having similar characteristics was obtained.

Example 2 The dyeing was carried out as in Example 1, except that wool tops were dyed that had been treated with an anti-felt finish according to the method described in Textilveredlung 11, (1976), No. 6, pages 214-219, and in Wool Science Review, volume 54, pages 2 et seq., and volume 55, pages 23 et seq., at a goods-to-liquor-ratio of 1:1 5, in the form of packages in a dyeing deviceused for this purpose with 2% (referred to the weight of the goods) of the yellow, 1:2 cobaltcomplex compound containing sulphonic acid groups of the dyestuff of the formula

and the dyed tops were subjected to aftertreatment processes as described in Example 1 a), b), or c).

Level dyeings of a somewhat dull yellow shade of a standard depth of about 1/1 were obtained that advantageously differed from the dyeings without aftertreatment a) in terms of fastness properties.

The improvement of the fastness properties to wetting in steps b) and c), too, was considerable and the shade and the colour depth were not impaired.

Example 3 The wool dyeing was carried out as described in Example 1, but using made-up knitted garments having an anti-felt finish according to the method described in Textilveredlung 11 (1976), No. 6. pages 214-219 and in Wool Science Review, volume 54, pages 2 etseq. and volume 55, pages 23 et seq., which were dyed at a goods-to-liquor ratio of 1:18 in a paddle dyeing machine using 2% (referred to the weight of the goods) of the brown, 1:2 chrome-complex compound containing sulphonic acid groups of the dyestuff of the formula

The dyed material was aftertreated according to the steps a), b) and c) of Example 1. These methods gave level brown colorations of medium colour depth.

Claims (12)

Claims

1. A process for the uniform fast dyeing of wool coated with a polyimine resin or a polyacrylic resin as anti-felting agents using metal-complex dyes containing sulphonic acid groups, which comprises dyeing wool having an anti-felt finish in a slightly acid medium with an aqueous solution of one or several 1:2 metal complex compounds of non-fibre reactive azo dyes having at most two sulphonic acid or sulphonate groups in the molecule, at a temperature of from 100 to 1 060C according to the exhaustion process and subjecting the resulting dyeings upon completion of the actual dyeing operation to an aftertreatment with a diluted aqueous solution of ammonia for 10 to 3G minutes at a temperature of from 40 to 600C.

2. A process as claimed in claim 1, wherein the exhaustion dyeing phase is carried out in the absence of auxiliary agents.

3. A process as claimed in claim 2 wherein the dyeing is carried out in the absence of a retarding agent.

4. A process as claimed in claim 2 or 3 which is carried out in the absence of a levelling agent.

5. A process as claimed in any one of claims 1 to 4, wherein from 0.1 to 3 cam3/1 of ammonia (25%) is used for the aftertreatment.

6. A process as claimed in Claim 5 wherein from 0.5 to 2 cm3/l is used.

7. A process as claimed in any one of claims 1 to 6, wherein the aftertreatment with ammonia is carried out after exhaustion of the dyebath in the same bath.

8. The process as claimed in any one of claims 1 to 6, wherein the aftertreatment is carried out in a freshly prepared bath.

9. A process as claimed in any one of Claims 1 to 8 wherein any one of the metal-complex dyestuffs specifically mentioned herein is used.

10. A process as claimed in any one of claims 1 to 9, wherein 1:2 metal-complex dyes are used in which the sulphonic acid or sulphonate groups present in the molecule have been partially replaced by carboxylic acid, or carbonate groups that do not participate in the complex formation.

11. A process as claimed in Claim 1 conducted substantially as described herein or in any one of the Examples.

12. Wool coated with a polyimine or polyacrylic resin whenever dyed by a process claimed in any one of claims 1 to 11.