This invention relates to dyes, their preparation and use in the coloration of substrates.

Over the years there have been many different dyes and dyeing methods invented for textile materials. Reactive dyes, direct dyes, vat dyes and their use are well known in dyestuff art.

The dyes of the present invention contain certain nucleophilic and electrophilic groups v±άch enable molecules of the dye to join together when an aqueous solution of the dye is heated and/or basified. In this way the dye's molecular weight increases, its water solubility can decrease, and its affinity for any textile materials present may be increased, leading to high levels of exhaustion of the dye from the dyebath, good fixation to textiles and good wash-fastness properties for textiles dyed therewith.

According to a first aspect of the present invention there is provided a water-soluble dye comprising molecules which contain a nucleophilic group and an electrcphilic group characterised in that (i) the molecules are capable of joining together by formation of a covalent band between the nucleophilic group of one molecule and the electrcphilic group of another molecule when the dye is heated or basified; and (ii) the nucleophilic group is or comprises an alkylthiol or a thiophenol.

The term "nucleophilic group" as used hereinafter means a πuclecphilic group comprising an alkylthiol or thiophenol.

Embodiments of the present invention and terms used are illustrated by reference to the accoπpanying drawings in which:

Fig. 1 is a flow chart showing schematically how dye molecules are joined together when heated or basified; and Fig. 2 is a flow chart showing how several dye molecules containing the nucleophilic group and a specific electrcphilic group are joined together on basification through a combination of elimination and addition reactions.

Figure 1 illustrates the result of heating or basifying a water-soluble dye according to the invention. The dye comprises n molecules (wherein n is >l) comprising a chrornqphore D, the nucleophilic group Nu and an electrcphilic group EL and the molecules are joined together by formation of a covalent bond between the nucleophilic group of one molecule and the electrcphilic group of another molecule vdien the dye is heated or basified. An oligomerised or polymerised dye results in which the Nu' and EL ¹ are residues of the nuclecphiles and electrqphiles joined together.

Figure 2 illustrates the result of basifying or heating a water-soluble dye according to the invention containing the nucleophilic group and an electrcphilic group. Basificaticn or heating in the presence of base causes gradual elimination of sulphato groups to give electrcphilic vinylsulphαnyl groups whic form a covalent bond with the -S" groups of other molecules of the dye to give -S-CH _J CH _J -SO--. Where the sulphato groups in the molecules are the only or the major water-solubilising groups, elimination thereof causes a decrease in water-solubility and this assists the affinity and/or fixation of the dye to any substrates which are present.

As will be understood from the drawings and description, the aforementioned molecules contain at least one of the nucleophilic groups and at least one electrophilic group and they join together by formation of covalent bonds between the nucleophilic group in each molecule and the electrcphilic group of another molecule to give a product of higher molecular weight.

The water-soluble dye molecules contain a chromophore which absorbs radiation at a wavelength in the region from the ultraviolet to the infra-red, preferably in the visible region of the spectrum, especially light of a wavelength from 400 to 700nm. Preferably the chromophore has an extinction coefficient of at least 5,000, more preferably at least 10,000, especially from 10,000 to 300,000, more especially from 10,000 to 150,000. The chro ophore preferably is as hereinafter described for D. Examples of water-soluble dyes according to the invention are those which have a maximum absorption (i.e. λmax) in the region 400- 700nm occurring in the range 400-425nm, 425-450nm, 450-475nm, 475-500nm, 500-525nm, 550-575nm, 575-600nm, 600-625nm, 625-650nm, 650-675nm or 675- 700nm. The preferred extinction coefficient at the maximum absorption is as hereinbefore described.

In one embodiment the nucleophilic and electrcphilic groups in the molecules of water-soluble dye are on different ends of the molecule, thereby facilitating the molecules joining together in a 'head- o-tail' manner. The electrophilic group must be capable of forming a covalent bond with the nucleophilic group when the dye is heated or basified and this will necessarily lead to one selecting appropriate pairs of nucleophilic and electrcphilic groups which satisfy this requirement. The words "are capable of joining" used when describing the present invention may therefore be replaced by "join". A skilled person may determine which pairs of nucleophilic and electrophilic groups are appropriate by heating or basifying a dye containing than and analysing the product, for example by ion spray mass spectrometry, HPLC

or by gel permeation chromatography (GPC) , to determine whether or not molecules of the dye have joined together to give a higher molecular weight product.

The nucleophilic group is preferably a thiophenol capable of forming a covalent bond with the electrcphilic group of another molecule of the dye when heated or basified.

The alkylthiol is preferably an optionally substituted primary or secondary alkylthiol. The optional substituents are preferably selected from alkyl and aryl. A Preferred alkylthiol is of Formula (1) :

R ¹

[ 1) wherein R ¹ and R ² are each independently H, optionally substituted alkyl or optionally substituted aryl, preferably H, C _1-4 -alkyl or optionally substituted phenyl, especially H or C _1-4 -alkyl. When only one of R ¹ and

R ² is H the alkylthiol is a secondary alkylthiol, and when both R ¹ or R ² are H the alkylthiol is a primary alkyl thiol.

Examples of alkylthiol groups are -CH,SH, -OHCSζJSH,

-CHCCH _J CH _J JSH, -C(CH _j ) ₂ -SH and -CHODCHjSH. The thiophenol is preferably a pheπylene group having an -SH substituent and optionally further substituents, for example amino, hydroxy, C _1-4 -alkyl, C _1-4 -alkoxy, sulpho, carboxy or -SH. A preferred thiophenol is of the Formula (2)

wherein, each R ³ independently is H, -SH, amino, hydroxy, C _1-4 -alkyl, C _1-4 -alkoxy, sulpho or carboxy.

Examples of thiophenol groups include 2-, 3- and 4-thiophenol. The electrcphilic group may be any group capable of forming a covalent band with the nucleophilic group of another molecule of the dye when heated or basified. Preferably said electrcphilic group is a group capable of undergoing 1) a substitution reaction, 2) an addition

reaction or 3) an elimination and addition reaction with the aforementioned nucleophilic group.

Groups which are capable of undergoing a substitution reaction preferably comprise a carbon or sulphur atom having an electron withdrawing displaceable atom or group attached thereto, for example in the case of carbon a halo, sulpho, quaternary ammonium or a mesylate, tosylate or acetate group and in the case of sulphur an acyl group or -SO ₃ -.

As examples of groups which are capable of undergoing a substitution reaction there may be mentioned halides, anhydrides of acids and heterocyclic coπpσunds which contain at least one or preferably 2 or 3 nitrogen atoms in the heterocyclic ring and a substituent which is sufficiently labile to be removed by nucleophilic substitution by the nucleophilic group. Preferred groups capable of undergoing a substitution reaction include groups of the formula -OOCE^-X ¹ , -CDCHR ⁴ CH ₂ -X ¹ , -COCHX ⁱ CHX ¹ C0 ₂ R ^s , -O0CHX ¹ CHX ¹ COR ⁴ , -O^-X ¹ and -NHCXXI^-X ¹ wherein:

X ¹ is a labile group; R ⁴ is H or a labile ^' group,- and

R? is H or optionally substituted alkyl, aryl or heteroaryl; A labile group is a group displaceable by the aforementioned nucleophilic group when the dye is heated or basified.

X ¹ is preferably halo, especially chloro, bromo or iodo. When R ⁴ is a labile group it is preferably halo, especially chloro.

The optional substituents which may be present on R ^s are preferably as mentioned hereinafter for L ¹ . R ⁵ is preferably H, phenyl or C _1-4 -alkyl, especially methyl or ethyl. Groups v άch are capable of undergoing an addition reaction preferably comprise an epoxide group, an aziridine, aziridinium, azetidine or cyclopropane group or, more preferably, an activated alkene (e.g. alkenyl sudphαne) or alkyne capable of undergoing a Michael-type addition with the aforementioned nucleophilic group. A preferred activated alkene is or comprises a group of formula -Z ¹ -CR ⁷ =CR ⁸ R ⁹ , -CR ⁷ =CR ⁹ -Z ² or -CZ ² =CR ⁷ R ⁹ wherein Z ¹ and Z ² are electron withdrawing groups and R ⁷ , R ⁸ and R ⁹ are each independently H, C _1-4 -alkyl or halo. ~- is preferably -SO-, -S0 ₂ -, -00-, especially -S0 ₂ -, and Z ² is preferably -CN, -N0 ₂ , or an alkyl- or arylsulphonyl group or an acyl group. The activated alkene of formula -Z ¹ -CR ⁷ =CR ⁸ R ⁹ may be attached to a group of formula -NR ⁵ - (wherein R ^s is as hereinbefore defined) to give a group of formula -NR ⁵ -S0-CR ⁷ =CR ⁸ R ⁹ , -NR ^s -S0 ₂ -CR ⁷ =CR ⁸ R ⁹ or -NR ^s -00- CR ⁷ =CR ⁸ R ⁹ . Preferred alkylsulphonyl groups are -S0 _; - (C _1-4 -alkyl) and

preferred arylsulphonyl groups are phenylsulphcnyl and tosyl. Preferred acyl groups are of the formula -G0-R ⁵ wherein R ^s is as hereinbefore defined, especially C _1-4 -alkyl or phenyl. It is preferred that R ⁷ and R ⁸ are both H.

Examples of activated alkenes include the following:

I I

-OO-C=CH, , -Ml D~Br=CH _{2 r} -CO-CBr=CHBr, -SO;,^^ , -S0 ₂ -03=01, , -30-03=03 ₂ , -ODCCl=CCl ₂ , -S0 ₂ CH=CHC1 , -CH=CH-CN, -CH=CH-N0 ₂ , -C (CN) =CH ₂ , -NHSO.-αfcCH, ,

-N(CH ₃ ) SO,CH=CH ₂ , and

A preferred group capable of undergoing an elimination and addition reaction is or comprises a group of the formula

-Z ¹ -NR ^s -(CR ¹¹ R ¹¹ ) _m -2? or -Z ¹ (CR ¹¹ R ¹¹ ) _m -X ² , especially -Z ¹ -NH-CH ₂ -CH.- and -Z ¹ -CH ₂ -CH ₂ -X ² wherein X ² is a labile group and Z ¹ is as hereinbefore defined, especially -S0 ₂ -, R ⁵ is as hereinbefore described, each R ¹¹ independently is halo, -NHj, carboxy or a group described above for R ^s ; and m is 2, 3 or 4. Preferably the labile group represented by X ² is

-OSOjH, -SS0 ₃ H, -OPO^, or a salt thereof, halo (especially chloro) or acetoxy. The groups of formula -Z ¹ (CR ¹¹ R ¹¹ ) _m -X ² may be attached to a group of formula -NR ^S - as defined above, in which case the CR ¹ ^ ¹¹ groups may be replaced by CHR ¹¹ groups.

In one embodiment the aforementioned groups of formula

-Z ¹ -NR ⁵ -(CR ¹¹ R ¹¹ ) _m -X ² , -NR ^s -Z ¹ (CR ¹¹ R ¹¹ ) _π ,-X ² , -Z ¹ (CHR ¹¹ ),,-X ² , -Z ¹ -CR ⁷ =CR ⁸ R ⁹ , -CR ⁷ =CR ⁹ -Z ² and -CZ=CR ⁷ " ^< are attached directly to an aromatic carbon atom, for example the atom of an aromatic ring such as a benzene ring, in molecules of the water-soluble dye.

Examples of groups capable of undergoing an elimination and addition reaction include the following: -SO-CH-CH.OSO.H, -SO, (CH ₂ ) ₃ OS0 ₃ H, -SOjCHjCHjCl, -S0 ₂ CH ₂ CH,OP0 ₃ H ₂ ,

-NHCOOiOLOSOsH, -S0 ₂ C ₂ H ₂ OCΩCR ₃ , -S0Cli,αi,0S0 ₃ H, -S0 ₂ CH ₂ CH ₂ SS0 ₃ H, -

NHS0 ₂ CH,CH,0S0 ₃ H, -NHSO, (CH ₂ ) ₃ SS0 ₃ H, -NHS0 ₂ (CH ₂ ) ₄ OS0 ₃ H _/

-N(CH,)SPiCEtCHjOSOjH, -SO^ H-CHtCH,)OΪ,-0S0iH,

-S0 ₂ NH-CH(CEI ₂ Cfl ₃ )CH ₂ -OS0 ₃ H, -SO _j NH-CfOH) (CH ₃ )CH ₂ -0S0 ₃ H, -SO _j NH-CH(CH,)CH(Ph) -0S0 ₃ H, -S0,NHCH(0S0 ₃ H)CH,-OSC^H,

-S0 ₂ NHCH (COOH) O^OSO^, -SQjNHCH (Ph) CHjOSOjH,

-S0,NHC (CH, ) ₂ CH,OS0 ₃ H, -SOjNHC (0£,QSq,H) ₃ , -S0,NHC (CH, ) (OH) CH.OSO ₃ H,

-S0,NH (CH ₂ ) ₃ -0S0 ₃ H and salts thereof .

The dye molecules according to the present invention preferably contain 1 or 2 to 6, for example 1, 2 or 3 of the nucleophilic groups and 1 or 2 to 6, for example 1, 2 or 3, of the electrophilic groups. The number of nucleophilic groups may be the same as or different from the number of electrophilic groups, for example the number of nucleophilic groups may be greater than or less than the number of electrcphilic groups.

In a preferred embodiment the dye molecules of the present invention contain at least 2 of the nucleophilic groups and/or at least 2 of the electrcphilic groups because this can lead to an iπprσvement in the fixation and/or wash-fastness of the dyes to or on textile materials, possibly by providing the dye with points for crosslinking thereby enhancing immobilisation of the dye on the textile.

To improve storage stability the dyes can have a protecting group en the sulphur atom in the alkylthiol or thiophenol group to give what is called a protected alkylthiol or protected thiophenol. Typically the protecting group is acid or base labile or removable on treatment with a reducing agent. Preferably the aforementioned sulphur atom in the alkylthiol or thiophenol group has a base labile protecting group,- in this way the dye is particularly storage stable and dyeing of textiles under alkaline conditions causes removal of the protecting group and polymerisation of the dye in a single step.

Preferred acid labile protecting groups for the sulphur atom are p-methαxybenzyl, 2-picolyl-N-oxide and triphenylmethyl. Preferred base labile protecting groups for the sulphur atom are 2,4-dinitrσphenyl, 2-nitro-1-phenylethyl, the residue of thiolesters, for example groups of formula -C0(C _1-4 -alkyl) , more preferably carbαnamides, especially carbσnamides of the formula -CONR ² wherein R ¹ and R ² are as hereinbefore defined. Preferred protecting groups for the sulphur atcm which are removable on treatment with a reducing agent include cyano and the residue of disulphide groups, for example groups of formula -S-C(R) (R? ³ ) (R ^c ) wherein R ^a , R? ^> and R ^c are each independently H, alkyl or aryl. Alternatively, dye molecules may protect one another through formation of disulphide links which act as their own protecting groups. In the case of dimer formation, treatment with a reducing agent cleaves the disulphide bend to give two molecules of dye, each having a free -SH group.

Further examples of acid labile and base labile protecting groups for sulphur and protecting groups which are removable an treatment with a reducing agent are described in the book by T.W. Greene & P.G.M. Wuts entitled "Protective Groups in Organic Synthesis", 2nd Edition.

The dyes of the present invention preferably have a water- solubility of at least 1%, more preferably at least 2%, especially at least 4%, more especially at least 8%. Preferred dyes have a water- solubility of up to 10%, more preferably up to 50%, especially up to 100%. All percentages are by weight of dye relative to weight of water (at 20°C) .

It is preferred that the joining together of the molecules by a covalent bond gives a product of lower water-solubility, more preferably less than 80%, especially less than 50%, more especially less than 25% and especially preferably less than 10% of the water-solubility of the original dye. In a particularly preferred embodiment joining together of two or more of the water-soluble molecules results in a product having less than 5%, more preferably less than 1%, especially negligible solubility in water (at 20°C) , wherein all percentages are by weight. The aforementioned product is oligomeric or polymeric.

The joining together of the molecules to give a product having lower solubility than the original dye may be achieved by the presence of temporary solubilising groups in the άye, that is to say groups which enhance solubility of the dye in water which are convertible by heating or basifying the dye into a group which does not enhance the solubility of the dye in water. It is preferred that at least 50%, more preferably at least 75% and especially that all solubilising groups, e.g. carboxy and/or sulpho groups, in the dye are temporary solubilising groups because the lowering of water-solubility which occurs tfιen the temporary solubilising groups are removed can greatly enhance exhaustion of the dye from a dyebath leading to high depths of shade and high wash-fastness.

Preferred examples of such a temporary solubilising groups are β-sulpihatoethylsulphαπyl, β-thiosulphatoethylsuilphσnyl and β-phosphatoethylsulphαπyl, which may also act as electrophilic groups. Basificaticn and/or heating causes elimination of a solubilising group, for example an inorganic solubilising group such as a sulpho group (in the form of sulphate) , bisulphate, thiosulphate or phosphate, to give a ye having fewer solubilising groups. In this way solubility of the dye may be reduced significantly thereby greatly enhancing the affinity and/or fixation of the dye for any substrate present.

When the molecules are capable of joining together when the dye is heated it is preferred that the heating is from a first temperature to a second temperature at least 20°C higher than the first teπperature, more preferably at least 30°C higher, especially at least 41°C higher and optionally up to 199°C or 299°C higher than the first temperature. The first teπperature is preferably between 0°C and 40°C, more preferably between 5°C and 40°C, especially between ll°C and 29°C.

The dye may be heated by any means, for example by an electrical means such as a heating mantle, infra-red, microwave or ultrasound or by using steam.

Examples of irst and second temperatures as referred to above are as follows:

First Temperature in the range Second Temperature in the range

11°C-29°C 45°C-170°C

11°C-29°C 50°C-160°C

11°C-29°C 50°C-130°C 11°C-29°C 45°C-110°C

11°C-29°C 61°C-109°C

When the molecules described above are capable of joining together when the dye is basified it is preferred that the basifying is from a first pH to a second pH at least 0.6 pH units higher than the first pH, more preferably at least 1 pH unit higher, especially at least 2 pH units higher, more especially at least 3 pH units higher and optionally up to 6.9 pH units higher than the first pH. The first pH is preferably between pH 0 and pH 8.5, more preferably between pH 2 and pH 8, especially between i 4 and pH 8, more especially between pH 6 and pH 8 and especially preferably approximately pH 7.

Examples of first and second pHs as referred to above are as follows:

First pH Second pH in the range

6-8 8-15 6-8 8-13

6-8 ^■ 8.1-10.9

7 8-15

7 8-13

7 8.1-10.9 The dye is preferably basified using an alkaline earth or alkali metal, base or salt, more preferably an alkali metal hydroxide, carbonate or bicarbonate, especially a sodium or potassium hydroxide, carbonate, bicarbonate or mixture thereof.

A preferred pair of nucleophilic and electrophilic groups capable of joining together by formation of a covalent bond therebetween when the dye is heated or basified are respectively (a) the alkylthiol groups of formula (1) defined above; and (b) the aforementioned activated alkenes and groups capable of undergoing an elimination and addition reaction, especially groups of formula -Z ¹ -CR ⁷ =CR ⁸ R ⁹ , -CR ⁷ =CR ⁹ -Z ² , -CZ ² =CR ⁷ R ⁹ , -Z CHR^-X , -Z^NR ⁵ (CR^R ¹¹ ),,,-X ² or -NR^Z ¹ - (CR ¹¹ R ¹¹ )„-X ² as defined above, more especially

-SO _j -OfoCH,, -SO-CH _J CELOSO _J H, -S0 ₂ NH(CH ₂ ) ₃ OS0 ₃ H, -NHCXXH ₂ CH,OS0 ₃ H, -N(CH,)SQ ₂ CH _! αi _! OS0 ₃ H ^' _/

-S0 ₂ O^CH ₂ -OP0 ₃ H, and salts thereof.

According to a second aspect of the present invention there is provided a water-soluble dye comprising molecules which contain a nuclecphilic group and an electrcphilic group wherein: (i) the nuclecphilic group is -C R ¹ ) (R ² ) -SH as described above,- (ii) the electrophilic group is an activated alkene or a group capable of undergoing an elimination and addition reaction,- and (iii) preferably the dye has at least two of the nuclecphilic and/or electrophilic groups.

The preferred activated alkenes and groups capable of undergoing an elimination reaction are as mentioned above. When there are at least two of the nuclecphilic or electrcphilic groups there are preferably 2 to 6, more preferably 2 or 3 of these groups. In dyes of the second aspect of the present invention it is preferred that the molecules are capable of joining together by formation of a covalent bond between the nucleophilic group of one molecule and the electrcphilic group of another molecule when the dye is heated or basified. Preferred dyes according to the invention comprise molecules which are capable of being joined together in the absence of a free radical.

The water-soluble dyes according to the invention may contain conventional diluents found in dyes, for exaπple salts remaining from vdien the dye was prepared or dedusting agents, and the dye may be mixed with other dyes. The dye may also contain a-colourless compound having the nucleophilic and electrophilic groups as hereinbefore defined, however this is not preferred.

In the first and second aspects of the present invention it is preferred that at least 10%, more preferably at least 40%, especially at least 60%, more especially at least 80% and especially preferably substantially all of the dye molecules join together by formation of a covalent bond between the nuclecphilic and electrcphilic groups when the dye is heated or basified. The water-soluble dye may contain or be free from molecules of other dyes, for exaπple dyes which have an electrcphilic group but no nuclecphilic group, dyes which have a nucleophilic group but no electrophilic group, and dyes which lack electrcphilic and nuclecphilic groups. Preferably the aforementioned other dyes, when present, constitute less than 40%, more preferably less than 20%, especially less than 10%, more especially less than 1.9% of the water-soluble dye (% by weight) .

A preferred water-soluble dye according to the invention comprises molecules of the Formula (3) :

wherein: each Nu independently is a group of Formula (1) or (2) as hereinbefore described; D comprises a chromophore; q and r are each independently a positive integer greater than or equal to 1; and each EL independently is an electrcphilic group as hereinbefore described. The molecules of Formula (3) are generally capable of joining together by formation of a covalent bend between a group Nu in one molecule and a group EL of another molecule when the dye is heated or basified. q and r are the same or different and are preferably each independently 1, 2, 3, 4 or 5, more preferably 1 or 2. Exaπples include dyes vftierein q is 1 and r is 1; q is 1 and r is 2, q is 2 and r is 1; q is 2 and r is 2; q is 3 and r is 1; q is 3 and r is 2; q is 3 and r is 3,- q is 2 and r is 3,- and q is 1 and r is 3.

The electrcphilic group represented by EL may be any of the aforementioned electrophilic groups provided it is capable of forming a covalent bend with the nuclecphilic group of another molecule of the dye when it is heated or basified. Preferably each EL independently is a group of formula -SOjCHjCH.OSO.H, -S0 ₂ CH,CH,SS0 ₃ H, -SOjCH.CH.OPOjH,, -S0 ₂ NHCH ₂ αi ₂ OSθ ₃ H, -NHO HjCH.OSOjH or -NfCH,)SO,CH ₂ CH ₂ OS0 ₃ H or a salt thereof.

The chromophore represented by D is preferably of the azo, ant±iraquinαne, phthalocyanine, triphenodioxazine, triphenylmethane, formazan, xanthene or benzodifuranone (BDF) series or a combination thereof, especially a chromophore of the azo series. In one embodiment D is free from sulpho groups.

Preferred chrσmophores of the azo series are monoazo and disazo chromqphores. Preferred monoazo chromophores are of the formula -L ¹ -N=N-L ¹ - wherein each L ¹ independently is an optionally substituted arylene or heteroarylene radical.

It is preferred that each arylene radical independently is mono- or di-cyclic. Preferred arylene radicals are optionally substituted phenylene and naphthylene. Preferred heteroarylene radicals are optionally substituted pyridαnylene, pyrazolonylene, benzthiazolene, isothiazolene, thiazolene and thiqphene. The optional substituents which may be present an L ¹ are preferably selected from C _1-4 -alkyl,

especially methyl; cyano; C _1-4 -alkαxy, especially methoxy,- hydroxy,- thio,- thiαne,- amino,- halo, especially chloro,- and amido, especially acetamido, benzamido or sulphαnamido,- ureido,- halomethyl; carboxy,- carbαxymethyl,- cyclohexyl; phenyl; and mono- and dialkylamino.

A preferred monoazo compound according to the invention is of the Formula (4) or a tautomer or salt thereof:

V-L -N=N-L^ -K—(L ¹ —K—) _n —Nu

Formula (4) therein:

V is or comprises a group capable of undergoing an addition reaction or an elimination and addition reaction,- n has a value of 0 or 1,- and each L ¹ , L ² , K and Nu independently is as hereinbefore defined.

Preferably each V independently is or comprises a group of the formula -Z ¹ -C ^r" =CR ⁸ R ⁹ , -CR ⁷ =CR ⁹ -Z ² , -CZ ² =CR ⁷ R ⁹ , -Z^NR ⁵ - (CR ¹¹ R ¹¹ ) _ra -X ² , -NR ⁵ - Z ¹ - (CR ¹¹ R ¹¹ ) _m -X ² or Z ¹ (CHR ¹¹ ) _m -X ² as hereinbefore defined, especially a group of formula Z-CH^O^-O^- wherein : „s B^SO-, H0 ₃ SS- or HAPO-. A preferred disazo dye is o_ Formula (5) :

V-tf-Ns -tf-NsN-tf-Nu (5) wherein: each L ¹ independently is as hereinbefore defined.

A preferred water-soluble dye of Formula (3) wherein D is a triphenodioxazine chromophore is of the Formula (6) :

wherein: each Y independently is a covalent bond, C^-alkylene, -C(=0) - (C _1-4 -alkylene) -, phenylene -C(=0) -phenylene- or sulphqphenylene,- each U is H, S0 ₂ NR ⁵ R ^B , SQ _j R ⁵ , -SO _s . HCHjCH.OSOjH or -SO^C-^-OL-X ² ; T ¹ and T° are H, halo, C _1-4 -alkyl, or C _1-4 -alkαxy,- X ² and each R ^s independently is as hereinbefore defined;

Nu is or comprises a nucleophilic group of formula (2) or (3) as hereinbefore defined; and

B is H or is or comprises an electrcphilic group;

provided that when B is H one or both of the groups represented by U is -S0 ₂ -CH ₂ -CH ₂ -X ² or -S0 ₂ NHO3 ₂ CH,-X ² .

Each Y is preferably -CΑ, - or -cy^-. T ¹ and T ² are preferably Cl or methyl.

B is preferably H or -S0 ₂ -CH ₂ CH ₂ -X ² wherein X ² is as hereinbefore defined.

A preferred water-soluble dye of Formula (3) wherein D is a formazan chromophore is of the Formula (7) :

wherein Nu and El are as hereinbefore defined. The benzene rings shown in Formula (7) optionally are substituted by a sulpho group.

A preferred water-soluble dye of Formula (3) vherein D is a BDF chromophore is of the Formula (8) :

vherein: each Nu and El independently is as hereinbefore defined and each K independently is 0, S or NR ⁵ ,- provided that two or more molecules of

Formula (8) are capable of joining together by formation of a covalent bond between the nuclecphilic group of one molecule and the electrcphilic group of another molecule when the dye is heated or basified.

Eyes according to the invention may be prepared by analogous methods to those described in the dvestuff art except that intermediates are selected which will result in the dye having the aforementioned nuclecphilic and electrophilic groups, for exaπple condensation of a coπpσund having a nuclecphilic group with a compound having an

electrophilic group, therein one or both of the compounds contains a chromophore. It is preferred that the condensation is performed at 10- 90°C, especially 20-90°C, more especially 40-90°C. Preferably the condensation is performed in a liquid medium, more preferably an aqueous medium or dimethylsulphcod.de. Precise conditions used will depend upon the nuclecphilic and electrcphilic group and will be selected so as to prevent premature polymerisation of the desired dye.

The condensation is preferably performed in the presence of an acid-binding agent. The function of the acid-binding agent is to neutralise any acid formed during the condensation. Accordingly any acid-bindi g agent may be used provided that it is not present in such a concentration that it causes hydrolysis of the reactants or causes some other side-reaction. It is preferred to use an alkali metal hydroxide, carbonate or bicarbonate, added at such a rate that the pH of the mixture stays within the range of 5.0 to 6.0.

Alternatively dyes according to the invention containing an azo chromophore may be prepared by coupling two suitable precursors, for exaπple coupling an azo component and a coupling component, one having an alkylthiol or thiophenol nuclecphilic group and the other having an electrophilic group. Such a coupling will normally be performed at below 5°C, in water using NaN0 ₂ and mineral acid to form the azo component from an amine.

Although formulae have generally been shown in their unionised or free acid form in this specification, the invention and formulae also include the dyes in the salt form, particularly their H _j - salts and their salts with alkali metals such as the sodium, potassium, lithium or mixed sodium/lithium salt. Thus groups shown as -SH include -S ^" .

A further feature of the present invention provides a composition comprising an inert carrier and a water-soluble dye according to the invention, preferably in a weight ratio of 99:1 to 1:99, more preferably 10:1 to 1:50, especially 5:2 to 1.1:10. The inert carrier preferably comprises inorganic salts and optionally a de-dusting agent. Exaπples of inorganic salts include alkali and a]kali earth metal halides, carbonates, bicarbαnates, nitrates and mixtures thereof. Dodecylbenzene may be used as a de-dusting agent.

According to a further aspect of the present invention there is provided a process for the coloration of a substrate comprising the steps of: (a) applying to the substrate a mixture comprising an aqueous solvent and a water-soluble dye coπprising molecules which contain an electrcphilic group and a thiophenol group or a protected alkylthiol or a protected thiophenol; and

(b) heating or basifying or heating and basifying the dye thereby causing molecules of the dye to join together. As there is no need for a free-radical initiator in this process it is preferred that no such initiator is added to the mixture and the mixture is free from or substantially free from organic free radicals or such an initiator. Similarly, there is no need to add Na _j S to the mixture and it is preferred that the mixture is free from or substantially free from Na,S, particularly since this compound can lead to unpleasant odours. In this way the process advantageously does not smell of H _j S.

As will be understood, when the nucleophilic group is a protected thiophenol or a protected alkylthiol it is usually necessary to remove the protecting group before molecules of the dye are capable of joining together in the manner specified. This may be dene before, during or after the dye is applied to a substrate.

Preferably the water-soluble dye is completely dissolved in the aqueous solvent. The nuclecphilic group, electrcphilic group and water-soluble dye are as described in the first aspect of the present invention. It is preferred that heating and/or basifying the dye causes molecules of the dye to join together by formation of a covalent band between the nuclecphilic group of one molecule and the electrophilic group of another molecule of the dye. Preferably heating and/or basifying the dye forms a dye of lower water-solubility and higher affinity for the substrate. The heating and basificaticn can be from first to second temperatures and pH's as described above in relation to the water-soluble dyes.

The mixture used in Step (a) preferably comprises 0.01 to 20 parts of dye per 100 parts of water, more preferably 0.15 to 9.9 parts of dye per 100 parts of water. The water-solubility of the dye used in step (a) and the percentage of dye molecules which join together in step (b) are preferably as hereinbefore described in relation to dyes of the invention. The mixture may also contain NaCl, for example 0 to 20 parts, more preferably 4 to 16 parts of NaCl per 100 parts of water. All parts are by weight. Preferably the water-soluble dye used in step (a) is as described in the first or second aspect of the present invention.

The preferred substrate is a metal or plastic, more preferably a porous material, and especially good results are found for leather, paper and textile materials. Porous materials are preferred because the dye may permeate therein before being heated and/or basified to fix the dye. The textile material is preferably a natural, semi- synthetic or synthetic material.

The water-soluble dyes of the invention may be in solid or liquid form. The solid form is, advantageously, more storage stable because there is less opportunity for the nucleophilic and electrcphilic groups to react with one another during storage. The solid form is also cheaper to transport because it weighs less than a water-containing liquid form.

Exaπples of natural textile materials include wool, silk, hair and cellulosic materials, particularly cotton, jute, hemp, flax and linen. Exaπples of semi-synthetic textiles include nitrocellulose, viscose rayon including TENCEL available from Cσurtaulds, England, cuprammσnium raycn and cellulose acetates.

Examples of synthetic fibres include polyamides, polyesters, polyacrylαnitriles and polyurethanes. The preferred coloration process according to the invention is a pad-batch, continuous, semi-continuous, or exhaust dyeing process or a printing process. During exhaust dyeing the dyes can demonstrate particularly efficient exhaustion from the dyebath. Suitable printing methods include applying the dye to a substrate which has, where necessary, been pretreated, for exaπple using an alkali. Alternatively the dye may be printed to the fibre and fixed by heating. Ink jet printing is one method of printing and this is of particular value where the substrate is a paper or cotton.

In a preferred pad batch dyeing process the mixture comprising an aqueous solution of the dye according to the invention is padded an a substrate at a temperature in the range 5°C to 40°C and the dye is heated to a second teπperature 10°C to 75°C higher, preferably 20°C to 30°C higher than the first teπperature, preferably for a period of at least 2 hours, e.g. 2.5 to 47.5 hours. In a second coloration process the mixture described in Step

(a) is alkaline and the mixture is padded onto the substrate and remains in contact therewith for at least 1 hour, e.g. 2.5 to 47.5 hours.

Dyes of the invention may be used to prepare inks used in ink jet printing. Preferred inks comprise a dye according to the invention and a liquid medium, for exaπple an aqueous medium.

The ink preferably contains from 0.5% to 20%, more preferably 0.75% to 15%, especially from 1.1% to 4.9% by weight of the dye, based an the total weight of ink.

The liquid medium and aqueous solvent are preferably water or a mixture comprising water and a water-soluble organic solvent, preferably in the range 99:1 to 1:99, more preferably 95:1 to 50:50, especially 89:11 to 61:39.

The water-soluble organic solvent preferably comprises a . ₄ -alkanol, especially methanol or ethanol; a ketone, especially acetone or methylisάbutylketαne; a glycol, especially diethylene glycol; 2- pyrrolidαne,- N-methylpyrrolidone; or a mixture thereof. In a third variation of the coloration process the mixture in step (a) comprises a solution of the dye in water and the mixture is applied to the substrate by immersing the substrate in a vessel containing said mixture. Heating, basifying or heating and basifying the solution in Step (b) , preferably forms a dye of lower water- solubility and higher affinity for the substrate.

In this third variation a substrate may be dyed with a mixture comprising water and a dye according to the invention at a substantially constant taiperature, for exaπple at a teπperature in the range 15 to 140°C, and the pH raised from a first to second pH as described above, preferably from a first pH in the range 4 to 8, more preferably 6.1 to 7.9, to a second pH 0.5 to 7 pH units higher, more preferably from 2 to 5 pH units higher than the first pH.

If desired in this third variation one may dye at substantially constant pH, for exaπple at a pH in the range 8 to 11, the temperature may be raised from a first taiperature in the range 10 to

50°C, preferably 16 to 29°C, to a second teπperature 15 to 130°C higher, preferably 20 to 50°C higher than the first taiperature.

Alternatively both the pH and taiperature may be raised during the third coloration process, preferably from the first to second teπperatures and from the first to second pHs described in the preceding two paragraphs. Conventional dye bath additives may be added to assist coloration of the substrate, for exaπple salt or dyeing auxiliaries.

In a fourth variation of the coloration process the mixture in Step (a) preferably contains a humectant and in Step (b) the dye is heated to a teπperature in the range 90°C to 230°C, preferably 95°C to 220°C, preferably for a period of 0.25 minutes to 45 minutes, more preferably 0.6 minutes to 29 minutes. Preferably the humectant is present in an amount of 0 to 25 parts, more preferably 2 to 20 parts per 100 parts of water, wherein all parts are by weight. In one aspect of the fourth variation the mixture has a pH of 8.5 to 14, more preferably pH 9 to 11. Another aspect of the fourth variation contains the extra step of drying the product of Step (a) before performing Step (b) .

As humectant there may be used polyprcpyleneglycol, dicyandiamide or preferably urea.

It is preferred that the water-solubility of the molecules joined together by Step (b) is less than 10%, more preferably less than 5%, especially less than 0.9%, of the water-solubility of the original

dye (at 20°C, all percentages by weight relative to water) because this leads to improved wash-fastness for the dyed substrate. This can be achieved by using dyes wherein any sulpho groups present in the molecules are removed by Step (b) , e.g. all the sulpho groups are tarporary solubilising groups. Preferably the molecules joined together by Step (b) are free from sulpho groups. One may assess the solubility of the molecules when joined together simply by performing the above process in the absence of a substrate, isolating the product and measuring its solubility in the normal manner. Alternatively the process may be performed in the presence of a cellulosic substrate and, after dyeing, the cellulosic matter is digested by a cellulase enzyme to free the polymerised dye whose solubility may be measured in the normal manner. The extent to which dye molecules join together may be measured by HPLC or GPC.

A further feature of this invention comprises a polymer or oligomer (and a process for their preparation) obtained or obtainable by heating or basifying or heating and basifying a water-soluble dye according to the present invention. The aforanentiαned oligomer and polymer preferably are free from sulpho groups preferably have negligible solubility in water at 20°C, and preferably have a molecular weight of 2 to 1000 times, more preferably 6 to 99 times the molecular weight of the original dye molecules before heating or basificaticn. Preferably the heating and/or basifying is from first to second temperatures and pHs as described hereabσve.

Use of a dye according to the present invention to form an oligomerised or polymerised compound (i.e. an oligomer or polymer) forms a further feature of the invention.

A still further feature of the invention is a substrate, especially a textile material, coloured using a water-soluble dye or by a coloration process according to the invention.

The invention is further illustrated by the following exaπples in which all parts and percentages are by weight unless specified otherwise. Example 1

Preparation of:

Stage (a)

2,2'-Dithiosalicylic acid (15.Og, 0.049 mole) and N,N- dimethyl formamide (0.5g, 0.007 mole) were dissolved in dry toluene (150ml) and the solution was heated to 50°C. Thionyl chloride (11.lg, 0.093 mole) was added dropwise over 30 minutes and then the mixture was heated at 80°C for 3 hours, 111°C for 30 minutes and then cooled to room taiperature.

Half of the resultant solution of 2,2'-dithiosalicylic bis (acid chloride) was added with stirring at 0°C to a solution of N- phenylpiperazine (6.48g, 0.040 mole) and triethylamine (3.94g, 0.039 mole) in dichloromethane (100ml) . After stirring at 0°C for 30 minutes, the mixture was allowed to warm to room temperature overnight. The mixture was diluted with dichloromethane (100ml) , washed with water (2 x 250ml) and 10% aqueous brine (100ml) and then dried over anhydrous magnesium sulphate, filtered and evaporated under reduced pressure to give the following compound as a white solid.

Stage (b)

4- (p-sulphatoethylsulphαnyl)aniline (2.81g, 0.01 mole) was stirred in a mixture of water (50ml) , ice (50g) and hydrochloric acid (35%; 5ml) . To this mixture was added 2N sodium nitrite solution (5ml, 0.01 mole) at 0-5°C over 5 minutes and the mixture was stirred for a further 2 hours. Excess nitrous acid was then destroyed by addition of 10% sulphamic acid solution. Stage (c)

The product from stage (a) (2.73g, 0.0046 mole) was dissolved in a mixture of 2N hydrochloric acid (20ml) , acetone (25ml) , acetic acid (5ml) , ice (25g) and water (50ml) . The product solution from stage (b) was added with stirring at 0-5°C and the pH was raised to 4.3 using sodium acetate to complete the coupling. Sodium chloride (lOg) was added to precipitate the dye.

The product was collected by filtration and dried to give the title product. The identity of the product was confirmed by ^X H n.m.r. spectroscopy and F.A.B. mass spectrcmetry.

The title product is illustrative of dyes having a protecting group on the sulphur atom which is ranσvable on treatment

with a reducing agent. In this case the protecting group is another molecule of the same dye attached through a disulphide link. Example 2

Preparation and polymerisation of:

The product of Example 1 (0.15g, 1.27 x 10 ^-4 mole) , sodium chloride (2.5g) and dithioerythritol (0.04g, 2.6 x 10 ^"4 mole, a reducing agent) were dissolved in water (50ml) in a 1 litre flask. A single piece of unmercerised cotton (5.0g) was added and the mixture was agitated by rotation at 30°C for 1 hour, thereby yielding the title product in situ as free thiol. Sodium carbonate (l.Og) was added and the taiperature ramped to 90°C over 1 hour. The dye molecules joined together and passed from the aqueous phase onto the cotton leaving the dyebath essentially colourless.

A sample of the title dye was dissolved in water, heated under alkaline conditions and the resultant solid filtered off. Analysis of the solid by gel permeation chromotography confirmed it was polymeric. Example 3

Preparation of:

Stage (a)

The product of Exaπple 1, stage (a), (11.88g, 0.02 moles) was dissolved in 1,4-diαxane (80ml) and water (20ml) . Triphenylphosphine (6.24g, 0.024 mole) and concentrated hydrochloric acid (4 drops) were added and the mixture was stirred under a nitrogen atmosphere at 20°C. Thin Layer Chromatography (silica gel plates, ethyl acetate eluant) confirmed that complete reduction of the disulphide band had occurred after 3 hours. Ethyl isocyanate (3.12g, 0.04 mole) was added and the mixture was stirred for a further 18 hours, under nitrogen at 20°C.

The solvent was removed on a rotary evaporator to leave a crude product mixture. A portion of pure thiocyanate product was separated from the triphenylphosphine oxide by-product by column chromotography (silica gel, ethyl acetate eluant) to give 5.25g, (0.014 mole) of a solid. Stage (b)

4- (β-sulphatoethylsulphonyl) aniline (3.93g, 0.014 mole) was stirred in a mixture of water (50ml) , ice (50g) and hydrochloric acid (35%; 5ml) . Sodium nitrite solution (2 ; 7.5ml, 0.015 mole) was added and the mixture was stirred at 0-5°C for 2 hours. Excess nitrous acid was then destroyed by the addition of 10% sulphamic acid solution. Stage (c)

The product from stage (a) (4.43g, 0.012 mole) was added to a mixture of hydrochloric acid (2M; 20ml) , ice/water (100ml) and acetic acid (5ml) . The product solution from stage (b) was added and the pH of the mixture was raised to 4 using solid sodium acetate. The coupling reaction was completed by stirring the mixture for 16 hours. NaCl (20g) was added to precipitate the dye.

The product was collected by filtration and dried to give the title compound. The identity of the product was confirmed by ^X H NMR and F.A.B. mass spectrosccpy.

The title product is illustrative of dyes having a protecting group an the sulphur atcm which is removable on treatment with aqueous base. A sample of the title dye was dissolved in aqueous alkali and heated in the absence of cloth. A precipitate formed which, according to gel permeation chromatography, ^X H- NMR and mass spectrosccpy, was a polymer. Example 4 The title product of Exaπple 3 (0.15g, 2.3 x 10' ⁴ mole) and sodium chloride (2.5g) were dissolved in water (50ml) in a one litre flask. A single piece of uπmercerised cotton (5g) was added and the mixture was agitated by rotation for 30 minutes at 30°C. Sodium carbonate (lg) was then added and the taiperature was raised to 90°C over 1 hour. The basic conditions caused rapid hydrolysis of the thiocarbamate group, releasing the free thiol, and causing polymerisation. The dye molecules joined together and passed from the aqueous phase onto the cotton leaving the dyebath essentially colourless. Examples 5 to 28

The method of Exaπple 1 may be repeated except that in place of the compound specified in the first column of Table 1 there is used the compound specified in the second column.

Table 1

t

Examples 29 to 34

The method of Exaπple 3 may be repeated except that in place of the compound specified in the first column of Table 2 there is used the coπpound specified in the second column.

Table 2

Examples 35 to 40

Further dyes according to the invention may be prepared having the structures shown in Table 3 below.

Table 3

Table 3 Cont'd

Table 3 Cont'd

Example 41 Preparation of:

Stage (a)

N-2-c± orcethyl-N-ethylaniline (25.93g) and potassium thiocyanate (68.5g) were dissolved in dimethylformamide (400ml) and stirred at 100°C for 20 hours. The solvent was removed under reduced pressure and water was added to the residue. The solution was extracted three times using ether and the combined ethereal solutions were washed with water and then dried over MgS0 ₄ . After filtration the solution was evaporated to dryness to give an oil. Flash chromatography (silica gel; 10% ethyl acetate in hexane) gave a solid (13.65g). Stage (b)

4- (β-sulphatoethylsulphαnyl) aniline (2.81g) was stirred in a mixture of ice-water (60ml) and hydrochloric acid (35%; 10ml) . Sodium nitrite solution was added (2 ; 5.5ml) and the mixture was stirred at 0-5°C for 30 minutes. Excess nitrous acid was then destroyed by the addition of solid sulphamic acid. Stage (c)

The product from stage (a) (2.06g) was dissolved in a mixture of water (100ml) and acetone (50ml) and cooled to 0-5°C. The product solution from stage (b) was added and the pH of the mixture was raised to 5.5 by addition of sodium carbonate solution (2M) . The mixture was stirred for 2 hours at 0-5°C and then allowed to rise to room taiperature. NaCl solution (10% w/v) was added and the precipitate collected by filtration and dried to give the title dye (4.2g) . The identity of the title dye was confirmed by 'H-NMR and F.A.B. mass spectrosccpy.

The title product is illustrative of dyes having a protecting group on the alkylthiol sulphur atom which is ranovable on treatment with a reducing agent. Stage (d) - Dyeing

The title dye (0.2g) was dissolved in water (50ml) . A piece of υnmercerised cotton (5g) was added and the mixture was agitated by rotation for 15 minutes at 50°C. Sodium chloride (2.5g) was added and the mixture was stirred for a further 30 minutes at 50°C. Sodium borohydride (0.02g) and sodium carbonate (l.Og) were then added and the mixture was agitated at 50°C for 30 minutes. The dye liquors were left essentially colourless. Stage (e) - Comparative Dyeing

The dyeing method of stage (d) was repeated except that sodium borohydride was omitted. In contrast to the dyeing method of stage (d) the dye liquors remained highly coloured.