GB2033433A - Process for dyeing wool having an anti-felt finish with reactive dyes - Google Patents

Abstract

A process for dyeing wool having a polyimine resin or polyacrylic resin anti-felt finish comprises dyeing the wool at a temperature in the range of from 100 to 106 DEG C according to an exhaustion process using a slightly acid aqueous solution of one or more non-substantive, fibre-reactive metal-complex azo dyestuffs containing in the molecule at least three groups selected from sulfonic acid and sulfonate groups, and subjecting the resulting dyeing to an aftertreatment with a dilute aqueous ammonia solution for a period of from 10 to 30 minutes at a temperature of from 40 to 60 DEG C. Modifications of the process are provided, wherein either sulfonic acid or sulfonate groups of the dyestuff are partially replaced by carboxylic acid or carbonate groups, or the dyestuff is formed during dyeing from corresponding metal-free azo dyestuffs and a compound which liberates polyvalent metal ions.

Description

SPECIFICATION Process for dyeing wool having an anti-felt finish with reactive dyes The present invention relates to the dyeing of wool coated with a polyimine resin or a polyacrylic resin anti-felting agent.

Hitherto, wool fibers that had been subjected to an "anti-felt" finishing process (wool of this type generally being designated "superwash" treated wool) could be dyed uniformly, in deep shades and with satisfactory fastness properties to wetting, only with reactive -dyes. Since a textile article which has been pretreated in the above-manner is able to stand up to the rather severe strains imposed thereon during repeated washes with the use of perborate-containing household detergents at 60"C without felting, it must have a satisfactory color-fastness under those conditions, which property is not required for untreated wool that could not be washed in this way.Wool fibers which are coated, for example, with a plastic 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 than wool fibers which have not been coated with the mentioned resins. This different behaviour can be attributed to the fact that new groups are formed by the anti-felt finish, which groups have an affinity for the salt-like or reactive bonds of the dyestuffs.

The finish applied to the fibres as a film distinctly increases the dyestuff affinity. This means that to obtain a good fiber and surface levelness of the dyeings always requires the use of a very specific dyeing process and the selection of suitable auxiliaries and dyestuffs having optimum properties for the dyeing. This prerequisite is the more imperitive, since the differences in affinity resulting from the material used, which characteristically occur with polyamide fibers, are increased by the conventional anti-felt finishing operations or felting-reducing treatments of the wool.

It is known from Melliand Textilberichte 12/1968, pages 1444-1448, from Textilveredlung 11/1976, pages 250-254, and from relevant pattern cards of dyestuff manufacturers, that both untreated wool fibers and those provided with an anti-felt finish, that have been dyed with specific reactive dyes, may be subjected to an aftertreatment with ammonia to improve their fastness to wetting (reactive bond). By this after-treatment it is intended to remove any dyestuff particles that have not been completely bound to the fiber or to complete the reactive bond of the dyestuffs to the fiber. Ammonia is either added before the end of the dyeing period or to the exhausted dye bath, and the treatment generally carried out for a period of 1 5 minutes at 80 to 100"C and at a pH value from 7.5 to 8.5.Ammonia and soap have been used for a long time for the aftertreatment of wool; however, only in recent years has ammonia alone been used for the improvement of the fastness to wetting of reactive dyes. Analogous measures for 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 specification No.

1,258,821 for dyeings of wool without an anti-felt finish using non-reactive, sulfonated copper phthalocyanine dyes.

It is, furthermore, known that not all reactive dyes can be used for the dyeing of animal polyamide fibers, even if applied from an acid medium; this is similar to the situation with acid dyes. Very often reactive compounds of this type yield only light shades because of their lack of substantivity. Thus this type of reactive dyes is closer to the substantive dyes than to the acid dyes, in terms of their affinity behaviour. Some of the reactive dyes, however, are known to be fixable onto wool only in an unsatisfactory manner.

Whether or not a dyestuff is suitable for dyeing wool depends partially on the number of sulfonic acid groups in the molecule, and partially on the agglomeration state of the dyestuff in the dyebath. Wool dyestuffs which are designated as acid dyes are generally present in the dyebath in a monomolecular state, that is really dissolved. Substantive dyestuffs, however, are generally agglomerated to such a degree that a partially colloidal system may be obtained in the aqueous medium. According to H. Rath, "Lehrbuch der Textilchemie" 3rd edition, 1972, pages 384 and 395, anionic monoazo dyes generally belong to the group of wool dyestuffs which are fixed onto the fibers from a strongly acid medium.The author reports (on page 540) the following: "The cellulose fiber dyestuffs are characterized in that they have a tendency to associate more or less on dissolution, contrary to most of the wool dyestuffs that are present in the molecular state in solution"; and furthermore: "Owing to the fact that the cellulose dyestuffs are absorbed on the fiber in an undissociated state, the least dissociated dyestuffs have' the best substantivity; in the case of wool fibers, the conditions are reversed".

It is surprising that this reduced dyeing effect does not occur when dyeing wool which has been provided with a polyimine or polyacrylic resin anti-felt finish. In this case the resin coating on the wool is first coloured and the dyestuff affinity of the fiber simultaneously changes.

The present invention provides a process for dyeing wool coated with a polyimine resin or polyacrylic resin as an anti-felting agent, which comprises dyeing the wool at a temperature in the range of from 100 to 106"C according to the exhaustion process from a slightly acid medium with an aqueous solution of one or more metal-complex compounds of non-substantive fibre-reactive azo dyestuffs containing at least three sulfonic acid or sulfonate groups in the molecule, inclusive of any sulfonic acid or sulfonate group(s) in the fibre-reactive group(s), and subjecting the resulting dyeing to an aftertreatment with a dilute aqueous solution of ammonia for a period of from 10 to 30 minutes at a temperature of from 40 to 60"C.

By the process according to the invention there may be obtained with this type of dyestuffs many shades and color depths, even relatively clear shades, in accordance with the requirements of the International Wool Secretariat, Department IWS Mark AG, for Superwash knitted goods and hand knitting yarns, in particular in terms of the fastness properties to wetting according to IWS-TM 1 74 (Test method for alkaline fastness to perspiration), and IWS-TM 1 93 (Test method for fastness to washing).

The process according to the invention may be performed either in one bath or in two baths.

The exhaust dyeing phase using the reactive dye(s) is generally carried out under the conditions usual for dyeing untreated wool, either at boiling temperature or in the high temperature range of from 103 to 106 C. It is followed, generally without an intermediate drying, by the aftertreatment, which is carried out either in the exhausted dyebath (without changing the bath) or in a fresh aftertreatment bath. If desired dispersing agents may be added to the aftertreatment bath. The quantity of ammonia in the bath is generally in the range of from 0.1 to 3 cm3/iitre, preferably from 0.5 to 2 cm3/litre, calculated on 25% strength ammonia. Thus a slightly alkaline medium is obtained in the course of the aftertreatment step. After the aftertreatment the dyed material may be rinsed and acidified.

The practicability of the process of the invention is surprising because metal-complex dyes containing sulfo groups and fiber-reactive groups have only a low affinity towards untreated wool. It was not expected that reactive dyes of this nature, which have been used hitherto exclusively as printing dyes or only for dyeing by padding processes, would be suitable for dyeing wool fibers provided with a polyimine or polyacrylic resin anti-felt finish by an exhaustion process, because the constitution or the associated state of these dyestuffs only indicated a suitability for deep colorations on cellulose.

Furthermore, corresponding dyeings obtained on normal wool fibers with dyestuffs of the above type are always skittery, that is they have a rather glittering aspect, and are not at all level; these disadvantages are not overcome by the addition of levelling agents. The fastness to wetting of these dyeings is so low that they are not suitable for textile use. Moreover, very often only light shades can be obtained.

An aftertreatment with ammonia is known, but only when carried out at boiling temperature or a slightly lower temperature; it was therefore extremely surprising that by the process of the invention this aftertreatment can be carried out at temperature from 40 to 60"C, i.e. under conditions that are very mild for wool fibers, and yet a considerable improvement of the fastness to wetting can be achieved.

A particular advantage of the process of the invention using metai-complex reactive dyes is that shades such as dark-blue, navy-blue, black-brown, anthracite and black can be obtained without having to use the triple-combinations of metal-free reactive dyes usually hitherto for this purpose. Moreover, smaller quantities of the metal-complex dyes need be used, as they have a high tinctoriai strength. This makes the process of the invention more economic and safer; dyeings produced with triple-combinations of dyestuffs involve somewhat greater expenditure, and because of the reduced dyestuff consumption, in particular in the case of dark shades, the dyebath is less polluted than in previous dyeing processes.

Moreover, it was not expected that the exhaust dyeing according to the invention, using the above specified metal-complex compounds of reactive dyes, could be carried out without the addition of auxiliaries. In the process of the invention the use of levelling agents currently employed in the dyeing of wool can be dispensed with; nevertheless very level dyeings are obtained. The use of retarding agents in the fixation of the dyestuffs can also be dispensed with in this process. In particular circumstances the presence of small quantities of auxiliaries as specified above may be advantageous. In this case such an addition would not be detrimental and it would not impair the fastness properties of the wool dyeings obtained by the process.

Under the conditions of the process 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 the reactive metal-complex dyes containing sulfo groups, contrary to the hitherto used reactive dyes, exhaust from the dyebath more or less completely. Therefore the residual bath is practically free from dyestuffs, and consequently the process can be used widely.

Dyestuffs for the process of the invention are metal-complex compounds of fiber-reactive azo dyes, in particular monoazo dyes, generally complex compounds wherein 2 molecules of an azo dye or one molecule of each of two different azo dyes are bound in complex manner to a metal atom (1:2 metal-complex compounds). These complex compounds may contain, for example, one disazo dyestuff molecule and one monoazo dyestuff molecule or, preferably, two identical or different monoazo dyestuff molecules. Also suitable are water-soluble metallized azo dyes containing one metal atom bound in complex manner per dyestuff molecule (1:1 metal-complex compounds).These dyestuffs contain altogether at least three sulfonic acid groups (-SO3H) or sulfonate groups (-SO3M) in the molecule, inclusive of any sulfonic acid groups or sulfonate groups present in the fiber-reactive groupings, these groups being distributed in 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 ohydroxy-o'-carboxyazo groupings; o-hydroxy-o'-carboxymethoxy or o-hyd roxy-o'-aminoazo groupings are also suitable. Suitable metal atoms bound in complex manner in these dyestuffs are chromium, cobalt, copper or nickel.Many dyestuffs of this kind are known, and are listed in the Colour Index, 3rd edition (1971) as "Reactive Dyes". These dyestuffs are mainly those that contain at least one group which is capable of reacting with the amino groups of polyamide fibers, a precursor thereof or a substituent which is capable of reacting with the amino groups of polyamide fibers. Examples of reactive groups and precursors forming these reactive groups are epoxy groups, the ethylene imide group, the vinyl grouping in the vinylsulfonyl or in the acrylic acid radical, the ss-sulfatoethyl-sulfonyl group, the ss-chloroethyisufonyl group or the b-dialkylami noethylsulfonyl group. Furthermore, there may be used derivatives of the tetrafluorocyclobutyl series, for example of tetrafluorocyclobutylacrylic acid.Reactive substituents in reactive dyes are those that can be split off easily to leave an electrophilic radical. These substituents may be halogen atoms (from 1 to 3) on following ring systems: quinoxaline, triazine, pyrimidine, phthalazine, pyridazine and pyridazone. Dyestuffs having two or more identical or different reactive groups may be used.

The present invention also provides a modification of the above process, wherein metalcomplex dyes are used as above but wherein the sulfonic acid or sulfonate groups are partially replaced by carboxylic acid (-COOH) or carbonate (-COOM) groups which do not participate in complex formation, and must hence be considered as water-solubilizing groups.

The present invention provides a further modification of the dyeing process, which comprises using, instead of the metal-complex dyes, one or more corresponding metal-free azo dyes which are capable of forming metal complexes, in the presence of a compound which liberates polyvalent metal ions, for example a heavy metal salt of chromium, cobalt, nickel, or copper.

Dyestuffs of this type are characterized in that they carry in their molecule adjacent to the azo bridge, preferably on both sides, substitutents such as -OH, -OCH3, -OC2H5, -NH2 or COOH.

The complex formation, or the complex-like formation, of the metal atom with the dyestuff and the wool fiber is brought about during the exhaustion dyeing process. This does not involve considerable expenditure for the dyeing process; the water-soluble heavy metal salts of the above type are generally added to the dyebath at the beginning of the dyeing process and the rest of the process is carried out in the normal manner. Particular dyeing conditions are not required.

The process of the invention makes it possible to dye wool yarns or tops which have been treated with polyimine or polyacrylic resins, or any textiles produced with these wool fibers. The process is also suitable for dyeing the wool fiber portion, treated in the above-specified manner, of fiber blends.

The following Examples illustrate the invention: Example 1: Knitting yarn of wool provided with an anti-felt finish in accordance with the method specified in the ISDC, volume 88/3, pages 93-100, was dyed at a goods-to-liquor ratio of 1:20 in the following manner: the aqueous dyebath at 40'C was supplemented with 4% (referred to the weight of the dry goods) of ammonium sulfate and subsequently the pH of the bath was adjusted to a value of approximately 5 with acetic acid.Then the goods to be dyes were introduced into the bath and contacted with the moving bath for about 5 minutes at 40"C. Next, the reactive dyestuff of the formula

dissolved in water was added to the dyebath in an amount of 1% (referred to the weight of the goods), the dyebath was heated to the boil within 45 minutes and the fiber material was dyed for 60 minutes at boiling temperature.

The dyed goods were aftertreated in the following manner: 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 50"C. Finally the resulting dyeing was rinsed with warm and with cold water, and the aftertreatment was carried to completion.

A dark-grey or anthracite dyeing on the wool yarn, having goo'd to very good fastness properties to washing and to perspiration, was obtained.

Similarly good results were obtained when carrying out the aftertreatment in the following manner: The dyebath and the dyed material were cooled to 70"C and the bath was withdrawn from the dyeing vessel. The dyed yarn was rinsed with water at 70"C, and cold water was added until a bath temperature of 40"C was obtained; next about 2% (referred to the weight of the goods) of aqueous ammonia solution (25%) were added and the goods were treated for 30 minutes at 40"C. Finally the dyeing was rinsed with warm and with cold water and the aftertreatment was thereafter carried to completion.

The aftertreatment operation with ammonia greatly improves the fastness properties to wetting as compared to the conventional aftertreatment, without impairing the shade or the color depth.

The improvement of the fastness properties to wetting amounts up to two degrees of the grey card.

A reduction of the fiber quality during the treatment with ammonia under the above conditions did not occur, since the resin coating additionally acts as a protective layer for the wool with anti-felt finish.

When the above-described aftertreatment was omitted, the resulting fastness properties did not comply with the requirements of the International Wool Secretariat, Department IWS Mark AG.

When an analogous dyeing was carried out on normal wool without a "Hercosett" finish, a medium-grey dyeing, which was not at all level, was obtained.

When using, instead of the above-described dyestuff quantity, 3.5% (referred to the weight of the goods) of the same dyestuff, there was obtained a good level black dyeing whose fastness properties fully comply with the requirements of the International Wool Secretariat.

Example 2: The dyeing was carried out as described in Example 1, except that wool tops, that had been provided 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., were dyed at a goods-to-liquor-ratio of 1 :1 5, as packages in a dyeing device usual for this purpose using 3% (referred to the weight of the goods) of the blue reactive 1:1 copper-complex dyestuff of the formula

and the dyed tops were subjected to the aftertreatment steps described in Example 1.

Level navy-blue dyeings of a standard depth of about 1/1 were obtained that advantageously differed from the dyeing without aftertreatment in terms of fastness properties.

The improvement of the fastness properties to wetting was pronounced and the shade and the color depth were not impaired.

Example 3: The wool dyeing was carried out in the manner described in Example 1, but using made-up knitted garments provided 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., which were dyed at a goods-to-liquor ratio of 1:1 8 in a paddle dyeing machine using 2% (referred to the weight of the goods) of the blue reactive 1:1 copper-complex dyestuff of the formula

A level solid blue dyeing was obtained.

Example 4: Knitting yarn made of wool that had been provided with an antifelt finish according to the method described in ISDC vol. 88/3, pages 93-100, was dyed at a goods-to-liquor ratio of 1:20 in the following manner: To the aqueous dyebath at 40"C there was added 4% (referred to the weight of dry goods) of ammonium sulfate and the pH of the dyebath was adjusted to a value of approximately 5 with acetic acid. Next, the goods to be dyed were introduced into the dyebath and contacted with the moving dyebath for about 5 minutes. Next, the reactive dyestuff of the formula

dissolved in water was added in an amount of 0.9% (referred to the weight of the goods).After satisfactory dispersion of the dyestuff in the dyebath there was added 0.5% (referred to the weight of the goods) of cobalt chloride (CoCl2.6 H20), the red crystals being added directly into the overflow of the hank yarn dyeing apparatus since they are readily soluble in water.

Thereafter the bath was heated to the boil within 45 mintues and the fiber material was dyed for 60 minutes at boiling temperature. This completed the actual dyeing process.

Thereafter the dyebath and the dyed goods were cooled to 70"C and the bath was withdrawn from the dyeing vessel. Subsequently the dyed yarn was rinsed with water of 70"C, cold water was added until a bath temperature of 40"C was obtained; about 2% (referred to the weight of the goods) of aqueous ammonia solution (25%) were added and the goods were treated therewith for 10 minutes at 60"C. Next, the resulting dyeing was rinsed with warm and with cold water and the aftertreatment was carried to completion.

A heavy, dark-red dyeing was obtained, having the good fastness properties as specified hereinbefore.

When using for metallizing the reactive dye, instead of the above-specified cobalt chloride, potassium bichromate in an amount of approximately 1 % (referred to the weight of the goods), there was likewise obtained a heavy red dyeing. The shade had however, shifted somewhat towards brown, while the fastness properties were unchanged.

Similar results, both as regards the shade and the fastness properties, were obtained when using the reactive dyestuff of the formula

Example 5: Knitting yarn made of wool that had been provided with an anti-felt finish according to the method described in ISDC vol. 88/3, pages 93-100, was dyed at a goods-to-liquor ratio of 1:1 2 in the following manner: To the aqueous dyebath at 40"C there was added 4% (referred to the weight of the dry goods) of ammonium sulfate and the pH of the bath was adjusted to approximately 5 with acetic acid. Thereafter the goods were introduced into the dyebath and contacted with the moving bath for about 5 mintues. Next, the reactive dyestuff of the formula

dissolved in water, was added in an amount of 1.5% (referred to the weight of the goods).After satisfactory dispersion of the dyestuff in the dyebath there was directly added 0.7% (referred to the weight of the goods) of copper sulfate (CuS04.5 H20). The bath was heated to the boil within 45 minutes and the fiber material was dyed at boiling temperature for 60 minutes.

The dyebath and the dyed goods were cooled to 70"C and the liquor was thereafter withdrawn from the dyeing vessel. The dyed yarn was rinsed thereafter with water of 70"C, and cold water was added until a bath temperature of 40"C was obtained, whereupon about 2% (referred to the weight of the goods) of aqueous ammonia solution (25%) were added. The goods were treated therewith for 10 minutes at 50"C. Finally the resulting dyeings were rinsed with warm and with cold water and the aftertreatment was carried to completion.

A reddish navy-blue dyeing was obtained having good levelness and good fastness properties.

Claims (16)

1. A process for dying wool having a polyimine resin or polyacrylic resin anti-felt finish, which comprises dyeing the wool at a temperature in the range of from 100 to 106"C according to an exhaustion process using a slightly acid aqueous solution of one or more non-substantive, fiber-reactive metal-complex azo dyestuffs containing in the molecule at least three groups selected from sulfonic acid and sulfonate groups, and subjecting the resulting dyeing to an aftertreatment with a dilute aqueous ammonia solution for a period of from 10 to 30 minutes at a temperature of from 40 to 60"C.

2. A process as claimed in claim 1, wherein the exhaust dyeing step is carried out at boiling temperature or a temperature in the range of from 103 to 106"C.

3. A process as claimed in claim 1 or claim 2, wherein the exhaust dyeing step is carried out in the absence of levelling or retarding agents.

4. A process as claimed in any one of claims 1 to 3, wherein the aftertreatment is carried out using ammonia in an amount of from 0.1 to 3 cm3 per litre of bath, calculated on 25% strength ammonia.

5. A process as claimed on claim 4, wherein from 0.5 to 2 cm3 of ammonia is used per litre of bath, calculated on 25% strength ammonia.

6. A process as claimed in any one of claims 1 to 5, wherein the aftertreatment is carried out in the presence of one or more dispersing agents.

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

8. A process as claimed in any one of claims 1 to 6, wherein the wool is separated from the exhausted dyebath and the aftertreatment is carried out in a separate bath.

9. A process as claimed in any one of claims 1 to 8, wherein a chromium, cobalt, copper or nickel complex dyestuff is used.

10. A process as claimed in any one of claims 1 to 9, wherein the dyestuff contains one or two monoazo dyestuff molecules.

11. A process as claimed in claim 1, conducted substantially as described herein.

1 2. A process as claimed in claim 1, conducted substantially as described in any one of Examples 1 to 3.

1 3. A modification of a process as claimed in any one of claims 1 to 11, wherein the sulfonic acid or sulfonate groups of the dyestuff have been partially replaced by carboxylic acid or carbonate groups which do not participate in the complex formation.

14. A modification of a process as claimed in any one of claims 1 to 11, wherein the exhaust dyeing step is carried out using one or more corresponding metai-free azo dyestuffs, which are capable of forming metal complexes, in the presence of a compound which liberates polyvalent metal ions, and the metal-complex azo dyestuff as defined in claim 1 is formed during the exhaust dyeing step.

1 5. A process as claimed in claim 14, conducted substantially as described herein.

16. A process as claimed in claim 14, conducted substantially as described in Example 4 or Example 5.

1 7. Wool having a polyimine resin or polyacrylic resin anti-felt finish, whenever dyed by a process as claimed in any one of claims 1 to 1 6.