GB2212175A - Aftertreatment of dyed or optically brightened substrates with cationic polymer plus anionic and nonionic assistants - Google Patents

Abstract

A process for the aftertreatment of a substrate to which a dye or optical brightener has been applied, comprises treatment with a cationic or protonatable polymeric product A, B or C in the presence of both an anionic assistant I and a nonionic or weakly cationic assistant II, where:- A) is a polymeric reaction product of a monofunctional or polyfunctional amine having one or more primary and/or secondary and/or tertiary amino groups with cyanamide, dicyanamide, guanidine or bisguanidine in which up to 50 mole percent of the cyanamide, dicyanamide, guanidine or bisguanidine may be replaced by a dicarboxylic acid or a mono- or di-ester thereof, with the splitting off ammonia, optionally in the presence of a catalyst; Product A containing at least one free hydrogen atom linked to a nitrogen atom; B) is the polymeric reaction product of Product A with - (i) epichlorohydrin or a precursor thereof; or (ii) an N-methylol derivative of a urea, melamine, guanamine, triazinone, urone, carbamate or acid amide optionally in the presence of a catalyst for crosslinking N-methylol compounds; C) is a water-soluble homo- or co-polymer of monoallylamines, diallylamines and/or triallylamines; I) is selected from C11-18 alkanesulphonic acids, aryl C8-22 alkylbenzenesulphonic acids, C1-22 fatty amido amine sulphonic acids; amidobenzenesulphonic acids, Turkey red oil, C1-22 alkyl-aryl disulphonic acids; C1-22 alkyl arylaryl sulphonic acids and sulphonated or sulphated products of phenols, phenolC1-6alkyl ethers; naphthol, naphthalene, benzylnaphthalenes, phenylether sulphones, tolylether sulphone, novolak products and dinaphthylmethanes; and sulphonated aromatic formaldehyde-condensation products; and II) is the addition product of C2-4 alkylene oxide with a saturated or unsaturated C8-22fatty alcohol, a C8-22fatty aminopropylamine, a C3-22 secondary alcohol, C1-22 alkylphenol or a carboxylic acid. e

Description

AFTERTReCTHENT OF DYED SUBSTRATES The invention relates to a process for aftertreating of dyed, printed or padded substrates.

According to the invention, there is provided a process for the aftertreatment of a substrate to which a dyestuff or optical brightener has been applied, comprising aftertreating the dyed,printed or padded substrates with a cationic or protonatable polymeric product (hereinafter defined as Product P) selected from: A) a polymeric reaction product (hereinafter defined as Product A) of a monofunctional or polyfunctional amine having one or more primary and/or secondary and/or tertiary amino groups with cyanamide, dicyanamide, guanidine or bisguanidine in which up to 50 mole percent of the cyanamide, dicyanamide, guanidine or bisguanidine may be replaced by a dicarboxylic acid or a mono- or di-ester thereof, with the splitting off ammonia, optionally in the presence of a catalyst (hereinafter defined as K1);Product A containing at least one free hydrogen atom linked to a nitrogen atom; or B) the polymeric reaction product (hereinafter defined as Product B) of Product A with a) epichlorohydrin or a precursor thereof; or b) an N-methylol derivative of a urea, melamine, guanamine, triazinone, urone, carbamate or acid amide optionally in the presence of a catalyst (hereinafter defined as K2) for crosslinking N-methylol compounds; or C) a water-soluble homo- or co-polymer (hereinafter defined as Product C) of monoallylamines, diallylamines and/or triallylamines; Product P being applied in the presence of a non-ionic assistant (hereinafter defined as the "assistant") comprising an anionic component (hereinafter defined as Component I) and a non-ionic or very weakly cationic component (hereinafter defined as Component II); Component I being selected from C1l~l8alkane sulphonic acids, arylC1~22alkylbenzene sulphonic acids, C822 fatty amido amine sulphonic acids; amidobenzenesulphonic acids, Turkey red oil, C122alkyl-aryl disulphonic acids; C122alkyl arylaryl suiphonic acids and sulphonated or sulphated products of phenols, phenolC1~6alkyl ethers; naphthol, naphthalene, benzylnaphthalenes.

phenylether sulphones, tolylether sulphone, novolak products (for example diphenyl methane); dinaphthylmethanes; and sulphonated aromatic formaldehyde-condensation products; and Component II being the addition product of C2~4alkyleneoide with a compound selected from saturated or unsaturated CE-22 fatty alcohol, C8-22 fatty aminopropylamine a C32 secondary alcohol, C1~22alkylphenol and a carboxylic acid.

In this Specification, preferably any aryl group is phenyl.

By the term "C8~22fatty" is meant C8~22alkyl or C8~22alkenyl.

Products A and B are well known and are described in USP 4,764,585 (= DOS 3,525,104) and USP 4,410,652 (= DOS 3,105,897); the contents and preferences of which are incorporated herein by reference. K1 is described in USP 4,764,585 (as Catalyst K) and K2 is described in USP 4,410,652 (as Catalyst C in US Patent 4,410652). K1 is preferably selected from metals, metal salts and heterocyclic nitrogen - containing organic bases, more preferably zinc chloride.

K2 is preferably a Lewis acid catalyst and includes nitrates, sulphates, chlorides, tetrafluoroborates and dihydrogen orthophosphates of aluminium, magnesium and zinc as well as aluminium hydroxychloride, zirconyloxychloride and mixtures thereof. More preferably K2 magnesium chloride or sodium sulphate.

Product C is also well known and is described in EP 140,309; EP 145,220, EP 95,233 and EP 142,337 the contents of which are incorporated herein by reference.

Preferably 0.1 to 6 %, more preferably 0.5 to 3 % based on the dry weight of substrate of Product P is used in a process according to the invention.

Preferably Product A is Product A' where Product A' is the product of reacting a C25alkylenediamine or a poly-C2~4alkylene- polyamine having 3 to 6 nitrogen atoms with cyanamide, dicyandiamide, guanidine or bisguanidine. More preferably Product A is Product At' where Product A" is the product of reacting diethylene triamine or triethylene tetraamine with dicyandiamide Preferably Product B is Product B' where Product B' is the reaction product of A', with epichlorohydrin or a compound selected from N,N'-dimethylol4,5-dihydroxyethylene urea, N,N'-dimethylol-4,5-dimethoxyethylene urea, an N,N'-dimethylol carbamate or a Cl,lalkyl ether thereof.

Preferably Product P is Product P' where Product P' is Product A' or B'.

Preferably the ratio of Component I to Component II is 1-4:1 (weight ratio).

Preferably the assistant is present in an amount of 0.1 to 6 %, more preferably 0.5 to 3 Z based on the dry weight of substrate.

Preferably Component I is selected from Turkey red oil, the condensation product of formaldehyde and an aromatic mixture sulphonated with H2 SO4 having an average molecular weight of 130 to 160 derived from naphtha; a sodium salt of dinaphthylenemethane disulphonic acid or a compound of formula III, IV or V

in which each R1, independently, is selected from C~l2alkyl (preferably isooctyl, nonyl or dodecyl); R3 is -(-CH2CH20),,-R5; -(-C3H60-),,-R5 or -(-C4H80)X-R5; R4 is hydrogen or a group -(CH2CH20-)p-R5; -(-C3H6-O-)p-R5 or -(C4H8O)p-R5-; one group R5 is -S03R6, and the second R5 when present is hydrogen or -S03R6;; each R6, independently, is hydrogen or an alkali metal, alkaline earth metal, NH4, hydroxyalkyl ammonium or alkyl ammonium group; both groups R2 are hydrogen or when both groups R5 are S03R6, R2 can be selected from hydrogen or -SO3R6; m is an integer from 1 to 3 inclusive; p is 1 or 2; whereby the sum of m + p is not greater than 4; each R, independently, is hydrogen or methyl (preferably methyl); n is O or an integer of from 1 to 6 inclusive; x and y, independently, are zero or 1; the sum of x + y being 1 or 2; M is sodium, potassium or NH4O+; Rlo is C1521alkyl; and R11 is C1~3alkyl.

Preferred compounds of formula IV is that of formula IVa.

where R11' is C16-18alkyl (preferably C17H35).

Preferred compounds of formula V are those of formula Va

Preferably the sulphonated condensation product of formaldehyde with the aromatic mixture is the product of reacting 0.35 moles of formaldehyde with 1 mol of the aromatic mixture which has been sulphonated (1 mol of aromatic mixture to 2 moles of H2S04).

Preferably Component II is a C14-22 fatty alcohol poly- C2~3~ alkyleneoxide (preferably having 20 to 60 alkyleneoxide group per molecules) or the condensation product of 1 mol of a C1522alkyl or Cls-22 alkenylamino-propylamine and 70 to 110 moles of a C2 - 3alkyleneoxide.

More preferably Component II is a mixture of 1 mol C1618 fatty alcohol ethoxylated with about 40 moles ethyleneoxide units or the condensation product of 1 mol of stearylaminopropylamine with 90 moles of ethyleneoxide.

Most preferably Component II is a mixture of 1 mol of a C16-18 fatty alcohol ethoxylated with about 40 moles of ethyleneoxide.

The process according to the invention is preferably an exhaust, dipping, spraying foam application, padding or other conventional application process, more preferably an exhaust process.

Preferably in a process according to the invention, an electrolyte is used.

The preferred electrolyte added is sodium or potassium carbonate, sodium or potassium hydroxide or sodium or potassium sulphate.

Preferably the process according to the invention is carried out in an aqueous medium. Preferably the pH is from 6 to 12 inclusive, the alkaline pH being adjusted by the addition of electrolyte.

Preferably, when the process according to the invention is an exhaust process, the bath has a goods to liquor ratio of 1:2 to 1:50.

Preferably the process according to the invention is carried out at a temperature of 20 to 700C inclusive.

A preferred process according to the invention comprises: a) placing a dyed or brightened substrate in an aqueous after treatment bath at room temperature (20-250C) containing: 0.1 to 6 X based on the dry weight of substrate of Product P; and 0.1 to 6 X based on the dry weight of substrate of Assistant (as herein defined) together with 5 to 10 g/l of electrolyte at a goods to liquor ratio of 1:2 to 1:50; b) raising the temperature of the bath over 10-20 minutes to a temperature in the range 40 to 600C inclusive; and c) maintaining the substrate in the bath at this temperature for 15-25 minutes (preferably 20 minutes).

The substrate can then be taken out of the bath, washed, neutralized if necessary and dried.

Preferred substrates include hydroxy group-containing-, amino-group-containing or thiol-group-containing substrates. Such substrates include leather and preferably cellulose containing substrates including paper. More preferred substrates include textile fibre material, especially cellulose fibres alone or in combination with synthetic or natural fibres, for example polyester, polyamide and polyacrylonitrile fibres or wool. By cellulose is meant natural and/or regenerated cellulose, for example cotton, viscose or cellulose acetate. The textile material can be in different forms for example yarn, woven fabric or knitted material.

The term "dyeing" in this Specification includes exhaust dyeing, padding or printing. Exhaust dyeing, padding or printing of the substrates can be carried out by conventional methods. In the case of a mixed fibre substrate, one part can be dyed before the other part.

In such a case, dyeing may be carried out in a single bath, one stage or in single bath, two or more stage process.

However, in the case of a fibre mixture consisting of cellulose and a part which is dyeable with basic dyes, the after-treatment according to the invention can take place after dyeing the cellulose part and before dyeing the other part of the fibre mixture with the basic dyes in a further stage. In this case, the process is a three-stage one: the cellulose part is firstly dyed by known methods, the after-treatment according to the invention is carried out in a 2nd stage, and finally, the other part of the fibre mixture, for example poly-acrylonitrile fibres or polyester fibres modified by acid groups, is dyed with basic dyes in a 3rd stage or bath.

The dyes which are used for dyeing fibres of the substrate used in a process according to the invention depend on the substrate, and may belong to various classes, for example the class of acid dyes, metal complex dyes, reactive dyes, direct dyes, basic dyes or disperse dyes.

The cellulose part is advantageously dyed with direct or reactive dyes. Basically, the reactive dyes used may similarly be any water-soluble dyes which contain at least one fibre-reactive group, whose presence in the dyestuff molecule enables the dyestuff to undergo a chemical reaction with the hydroxy groups present in the textile materials. The direct dyes employed may be those which are used for dyeing cellulose or wool, preferably those which are called "reactant fixable". It is advantageous to use reactive dyes or direct dyes which exist as metal complexes.

Dyeing assistants which are otherwise usual for dyeing, pad-dyeing or printing may be used. When dyeing with direct dyes, an electrolyte such as sodium chloride or Glauber's salt is used, and in the case of reactive dyes, an alkaline fixing agent such as sodium or potassium hydroxide, carbonate, bicarbonate, silicate, borate or phosphate, or mixtures thereof, is used.

After dyeing, the substrate is rinsed, dried if required and then after-treated according to the invention.

By using a process according to the invention, dyeings and prints with good wet fastness and in particular good rubbing fastness are obtained. The process is especially suitable for dyeing yarn, of mixed fibres or mixed yarns; level dyeings and good penetration are attained. The results are particularly noticeable in the sensitive range of dark shades, for example with black dyeings.

In the following Examples, all percentages are by weight and all temperatures are given in degrees Centigrade, unless indicated to the contrary. All X are based on the dry weight of substrate being dyed.

Example 1 Polyester/cotton yarn (67:33) which is wound on cross-wound spools is placed at 500 in a dye bath containing: 3.5 X of the dyestuff C.I. Direct Black 117 25 g/l of Glauber's salt and 2 m/l of a commercial complexing agent based on a citrate.

After dyeing for 10 minutes, the pH value is adjusted to 5 by adding sodium carbonate and the bath is then heated to 900.The following dyes are added to the dye bath: 0.016 X of the C.I. Disperse Yellow 235 0.064 % of the C.I. Disperse Red 73 1.6 X of a commercial rapid dyeing black disperse dye and the temperature of the bath is raised to 1300 at a rate of 1.50/min. Dyeing takes place for 20 minutes at 1300, followed by cooling over 45 minutes to 700.The dye bath is drained and the yarn rinsed. The dyed yarn is then after-treated for 20 minutes at 600 with a bath containing 1 % of a compound of Example 1 of DOS 3,525,104 (= USP-4,764,585), 1.5 X of a mixture (2:1) of Turkey red oil and C16-le fatty alcohol poly(40-60)glycol ether, and 5 g/l of Glauber's salt, and the yarn is finally rinsed with cold water.

The black dyeing thus after-treated has good rubbing fastness properties.

Example 2 Polyester/cotton (67:33) yarn is dyed by the dyeing process of Example 1, rinsed and subsequently after-treated for 20 minutes at 400 in a bath containing 2 X of a compound of Example 10 of DOS 3,525,104 (= USP 4,764,585), 1.5 X of the anionic/non-ionic mixture of Example 1, 5 g/l of Glauber's salt and 2 m/l of sodium hydroxide.

The yarn is then rinsed and neutralised.

The resultant dyeing has good rubbing fastness.

Example 3 Wool/cotton mixed yarn is dyed at boiling temperature with a dye bath containing: 1.00 % of the dyestuff C.I. Acid Blue 206 0.1 X of the dyestuff C.I. Acid Violet 128 0.4 Z of the dyestuff C.I. Acid Blue 227 1.5 Z of the dyestuff C.I. Direct Blue 151 0.32 % of the dyestuff C.I. Direct Black 62 2.00 % of a commercial synthetic tannin based on a 4,4' -dihydroxydiphenylsulphone-m-xylene-sulphonic acid-formaldehyde condensation product 30.00 % of Glauber's salt 3.00 % of ammonium sulphate and 1.00 % of 40 % acetic acid.

The liquor to goods ratio is 1:25. At the end of dyeing, the dye bath is cooled over the course of 45 minutes to 600, drained and the yarn rinsed. The dyed yarn is subsequently after-treated as described in Example 1. A mixed yarn which is dyed in a marine-blue shade and has good rubbing fastness is obtained.

Example 4 Polyamide/cotton (PAC/CV) mixed yarn on a package is dyed in a single bath in one stage at a liquor to goods ratio of 1:30, whereby the following dyes are used: 1.00 % of the dyestuff C.I. Direct-Brown 240 0.35 % of the dyestuff C.I. Acid Orange 127 0.13 % of the dyestuff C.I. Acid Red 299 0.22 % of the dyestuff C.I. Acid Blue 280 (calculated on the weight of the substrate).

After dyeing, the yarn is rinsed and subsequently after-treated for 20 minutes at 60C with a bath containing 1 % of a compound of Example 1 of DOS 3,525,104 (= USP 4,764,585), 2 X of the anionic/non-ionic mixture of Example 1 and 10 g/l of sodium chloride, and it is finally rinsed.

The resultant brown dyeing has good rubbing fastness.

Example 5 PAC/CV (50:50) mixed yarn on a package is dyed at 900 for 95 minutes with the following bath: 60 g/l Glauber's salt 2 g/l of sodium salt of m-nitrobenzenesulphonic acid 15 g/l of soda (metered) 0.18 % of C.I. Reactive Yellow 58 0.12 % of C.I. Reactive Yellow 29 2.2 X of C.I. Reactive Blue 18 and is subsequently given a hot and a cold rinse. This dyed yarn is then after-treated for 10 minutes at 600 in a 2nd bath containing 1.5 % of a compound of Example 1 of DOS 3,525,104 (= USP 4,764,585), 1.5 % of the anionic/non-ionic mixture of Example 1 and 10 g/l of sodium chloride, and the yarn is given a cold rinse.

The mixed yarn is then dyed at 1050 in a 3rd bath containing 0.05 X of the dyestuff C.I. Basic Yellow 13, 0.02 Z of the dyestuff C.I. Basic Yellow 82, 0.12 % of the dyestuff C.I. Basic Blue 3, 1 ml/l of a commercial anti-precipitant; and 1 g/l of sodium acetate.

At the end of dyeing, the dye bath is cooled to 600 and the dyed substrate is rinsed.

A green dyeing with good rubbing fastness is obtained.

Examples 5 to 35 Examples 1 to 5 can be repeated using instead of the cationic fixing agent of Example, an equivalent amount of the compound of Example 4 of DOS 3,525,104 (=USP 4,764,585).

Examples 1 to 5 can be repeated using, instead of Turkey Red Oil, the same amount of the compound of Example 1 of DOS 3,110,411 or the compound of Example "Phenylsulphone K" of DOS 1,619,635 or the compound of Example 6 of DOS 3,442,888 or the condensation product of 0.35 moles formaldehyde with 1 mole of an aromatic mixture derived from naphtha having a M.W. of about 145, sulphonated with 2 moles of H2 SO4 or the sodium salt of dinaphthyl-methane disulphonic acid.

Examples 1 to 5 can be repeated using, instead of the glycol ether, the same amount of the condensation product of 1 mole of stearylaminopropylamine and 90 moles of ethyleneoxide.

The dyeings of Examples 5 to 35 have good fastness to rubbing.

Claims (12)

CLAIMS:

1. A process for the aftertreatment of a substrate to which a dyestuff or optical brightener has been applied, comprising aftertreating the dyed, printed or padded substrate with a cationic or protonatable polymeric product (hereinafter defined as Product P) selected from: A) a polymeric reaction product (hereinafter defined as Product A) of a monofunctional or polyfunctional amine having one or more primary and/or secondary and/or tertiary amino groups with cyanamide, dicyanamide, guanidine or bisguanidine in which up to 50 mole percent of the cyanamide, dicyanamide, guanidine or bisguanidine may be replaced by a dicarboxylic acid or a mono- or di-ester thereof, with the splitting off ammonia, optionally in the presence of a catalyst (hereinafter defined as K1);Product A containing at least one free hydrogen atom linked to a nitrogen atom; or B) the polymeric reaction product (hereinafter defined as Product B) of Product A with a) epichlorohydrin or a precursor thereof; or b) an N-methylol derivative of a urea, melamine, guanamine, triazinone, urone, carbamate or acid amide optionally in the presence of a catalyst (hereinafter defined as K2) for crosslinking N-methylol compounds; or c) a water-soluble homo- or co-polymer (hereinafter defined as Product C) of monoallylamines, diallylamines and/or triallylamines; Product P being applied in the presence of a non-ionic assistant (hereinafter defined as the "assistant") comprising an anionic component (hereinafter defined as Component I) and a non-ionic component (hereinafter defined as Component II); Component I being selected from C1118alkane sulphonic acids, arylC1~22alkylbenzene sulphonic acids, C8-22 fatty amidQ amino sulphonic acids; amido -- benzenesulphonic acids, Turkey red oil, C122alkyl-aryl disulphonic acids; C122alkyl arylaryl sulphonic acids and sulphonated or sulphated products of phenols, phenolC1alkyl ethers; naphthol, naphthalene, benzylnaphthalenes, phenylether sulphones, tolylether sulphone, novolak products and dinaphthylmethanes; and sulphonated aromatic formaldehyde - condensation products; and Component II being the addition product of C2~4alkyleneoxide with a compound selected from saturated or unsaturated C822 fatty alcohol, a Ct-22 fatty aminopropylamine, C3-22 secondary alcohol, C122alky1pheno1 and a carboxylic acid.

2. A process according to Claim 1, in which Product A is Product A' where Product A' is the product of reacting a C2~salkylenediamine or a poly-(C24alkylene) polyamine having 3 to 6 nitrogen atoms with cyanamide, dicyandiamide, guanidine or bisguanidine.

3. A process according to Claim 2, in which Product A is Product A" where Product A" is the product of reacting diethylene triamine or triethylene tetraamine with dicyandiamide.

4. A process according to any one of the preceding claims, in which Product B is Product B' where Product B' is the reaction product of Product A', where Product A' is the product of reacting a C,salkylenediamine or a poly-(C24alkylene) polyamine having 3 to 6 nitrogen atoms with cyanamide, dicyandiamide, guanidine or bisguanidine, with epichlorohydrin or a compound selected from N,N'-di methylol-4,5-dlhydroxyethylene urea, N,N'-dimethylol-4,5-dimethoxyethylene urea, an N,N'-dimethylol carbamate or a C1~4alkyl ether thereof.

5. A process according to any one of the preceding claims, in which Product P is Product P' where Product P' is Product A', where Product A' is the product of reacting a C2~salkylenediamine or a poly-(C24alkylene) polyamine having 3 to 6 nitrogen atoms with cyanamide, dicyandiamide, guanidine or bisguanidine; or Product B', where Product B' is thezreaction product of Product A' with epi chlorohydrin or a compound selected from N,N'-dimethylol-4,5-di- hydroxyethylene urea, N,N'-dimethylol-4,5-dimethoxyethylene urea, an N,N'dimethylol carbamate or a C14alkyl ether thereof.

6. A process according to any one of the preceding claims, in which Component I is selected from Turkey red oil, the condensation product of formaldehyde and an aromatic mixture sulphonated with H2 SO4 having an average molecular weight of 130 to 160 derived from naphtha; a sodium salt of dinaphthylenemethane disulphonic acid or a compound of formula III, IV or V

(HO S), SO 50-0 0 2'2(SO }0f 3y R & R n ('I') /R l R1 0 CO-NHC2 4a l kyl eneNRll (Iv) C2~5al kyl ene-sO3M R2+CH2+ R2 ( V ) OR3 OR4 in which each R1, independently, is selected from C8~12alkyl;; R3 is -(-CH2CH2O)1-R5; -(-C3H60-).-R5 or -(-C4H80)1-R5; R4 is hydrogen or a group -(CH2CH20-),-RS; -(-C3H6-O-)-R5; one group R5 is -SO3R6, and the second R5 when present is hydrogen or -S03R6; each R6, independently, is hydrogen or an alkali metal, alkaline earth metal, NH4, hydroxyalkyl ammonium or alkyl ammonium group; both groups R2 are hydrogen or when both groups R5 are S03R6, R2 can be selected from hydrogen or -SO3R6; m is an integer from 1 to 3 inclusive; p is 1 or 2; whereby the sum of m + p is not greater than 4; each R, independently, is hydrogen or methyl (preferably methyl); n is O or an integer of from 1 to 6 inclusive; x and y, independently, are zero or 1; the sum of x + y being 1 or 2; M is sodium, potassium or NH4@ R10 is C1521alkyl; and R11 is C1~3alkyl.

7. A process according to any one of the preceding claims in which Compound II is a C14-22 fatty alcohol poly-C7,3alkylene oxide or the condensation product of 1 mole of a C15-22alkyl or C15-12- alkenylamino-propylamine with 70-110 moles of a C23alkylene oxide.

8. A process according to any one of the preceding claims, in which 0.1 to 6 % based on the dry weight of substrate to be treated of Product P is applied.

9. A process according to any one of-the preceding claims, in which 0.1 to 6 X based on the dry weight of substrate to be treated of the assistant is applied.

10. A process for aftertreating a substrate comprising a) placing a dyed or brightened substrate in an aqueous after treatment bath at room temperature containing: 0.1 to 6 % based on the dry weight of substrate of Product P; and 0.1 to 6 X based on the dry weight of substrate of Assistant (as herein defined) together with 5 to 10 g/l of electrolyte at a goods to liquor ratio of 1:2 to 1:50; b) raising the temperature of the bath over 10-20 minutes to a temperature in the range 40 to 60eC inclusive; and c) maintaining the substrate in the bath at this temperature for 15-25 minutes.

11. A process substantially as herein described with reference to any one of Examples 1 to 35.

12. A dyed substrate aftertreated by a process according to any one of the preceding claims.