This invention relates to dyes, their preparation and use in the coloration of substrates, particularly leather.
Over the years there have been many different dyes and dyeing methods invented for leathers and textile materials. Reactive dyes, direct dyes, vat dyes and their uses are well known in dyestuff art.
Co-pending International Patent Application No. PCT/GB93/02344, published 9 June 1994, describes a process for coloring substrates in which a dye having a nucleophilic group and an electrophilic group is applied to a substrate and heating and/or basification causes the dye to polymerise. We have now devised polymerisable dyes in which the nucleophilic group is a secondary amino group which is free from aryl substituents. These dyes are particularly valuable for dyeing at neutral and acidic pH, a property which is particularly valuable when dyeing substrates which cannot tolerate high temperatures or pH, for example leathers.
According to a first aspect of the present invention there is provided a dye comprising molecules which contain a nucleophilic group and an electrophilic group characterised in that (i) the molecules are capable of joining together by formation of a cava lent bond between the nucleophilic group of one molecule and the electrophilic group of another molecule when the dye is heated, acidified or basified; and (ii) the nucleophilic group is or comprises a secondary amino group which is free from aryl substituents.
The phrase "secondary amino group which is free from aryl substituents" means that the N atom in the amino group is not directly attached to an aryl group, e.g., phenyl, but there can be aryl groups separate from the N atom, for example as found in N-benzyl groups.
A preferred secondary amino group which is free from aryl substituents is of the Formula (1):
wherein: R3
is optionally substituted alkyl and R1 and R- are each independently H, optionally substituted alkyl or optionally substituted aryl; or
is H, optionally substituted alkyl or optionally substituted aryl and R2 and R3, taken together with the C and N atoms to which they are attached, form a 5- or 6-membered ring.
The term "nucleophilic group" is used hereinafter as an abbreviation for the secondary amino group which is free from aryl substituents.
Embodiments of the present invention and terms used are illustrated by reference to the accompanying 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
a specific nucleophilic group and a specific electrophilic
group are joined together on heating.
Figure 1 illustrates the result of heating a dye according to the invention. The dye comprises n molecules (wherein n is >1) comprising a chromophore D, the nucleophilic group Nu .and an electrophilic group EL and the molecules are joined together by formation of a covalent bond between the nucleophilic group of one molecule and the electrophilic group of another molecule when the dye is heated or basified. An oligomerised or polymerised dye results in which the Nu' and EL' are residues of the nucleophiles and electrophiles joined together.
Figure 2 illustrates the result of heating a dye according to the invention containing a -OijNHCHj nucleophilic group and an electrophilic H^CHSO;,- group. Heating causes oligomerisation or polymerisation.
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 togetlier by formation of covalent bonds between the nucleophilic group in each molecule and the electrophilic group of another molecule to give a product of higher molecular weight.
The 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 chromophore preferably is as hereinafter described for D.
Examples of dyes according to the invention are those which have a maximum absorbtion (i.e. Xmax) 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 electrophilic groups in the molecules of dye are on different ends of the molecule, thereby facilitating the molecules joining together in a 'head-to-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 electrophilic 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 them 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.
When R1, R2 or R3 is optionally substituted alkyl it preferably contains up to 10 carbon atoms, more preferably it is Cx_£-alkyl, especially Cx_4-alkyl, more especially methyl, ethyl or propyl.
When R1 or R2 is optionally substituted aryl it is preferably optionally substituted phenyl.
The 5- or 6-membered ring which may be formal by R2 and R3, taken together with the C and N atom to which they are attached, is preferably an optionally substituted morpholine, piperazine or piperidine ring. The substituents which may be present on R1, R2, R3 or on the morpholine, piperazine or piperdine ring are preferably selected from Q^-alkyl, C^-alkoxy, sulpho, carboxy, nitro, cyano, halo, -SH, amino, hydroxy, phenyl and vinyl sulphonyl and the ring optionally is fused to an aromatic ring.
Examples of nucleophilic groups comprising a secondary amino group which is free from aryl substituents includes -CHJNHCBj, -aMMCKCH,, -a^NHO^CH,, -OiJNHOljCgHs, -CHCH-^NHCH,, -C (CH3) 2NHCH3, - (NHCH2ai:)3-NH2, -NtCHjOySK,) (CH2CH2NHCH:,CH2NH2) and
(Formula Removed)
The electrophilic group may be any group capable of forming a covalent bond with the nucleophilic group of another molecule of the dye when heated, acidified or basified. Preferably said electrophilic 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 -SO3".
As examples of groups which are capable of undergoing a substitution reaction there may be mentioned halides, anhydrides of acids and heterocyclic groups 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. Examples of such heterocyclic groups include dihalotriazines and triazines having a quaternary ammonium or a sulpho group.
Preferred groups capable of undergoing a substitution reaction include groups of the formula –COCH2-X1, -COCH2CH2-X1, -CDCHX1CHX1CD;;R5, -COCHX1CHX1C0R4, -CPL-X1 and –NHCCO2-X1 wherein:
X1 is a labile group;
R4 is H or a labile group,- and
R5 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.
X1 is preferably halo, especially chloro, bromo or iodo.
When R4 is a labile group it is preferably halo, especially chloro.
The optional substituents which may be present on R5 are preferably as mentioned hereinafter for L1. R5 is preferably H, phenyl or C^4-alkyl, especially methyl or ethyl.
Groups which 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 sulphone) 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 -ZL-CR7=CR8R9 -CR7=CR9-Z2 or -CZ2=CR7R2 wherein Z1 and Z2 are electron withdrawing groups and R7, R8 and R' are each independently H, C1-4-alkyl or halo. Z1 is preferably -SO-, -SO2-, -CO-, especially -SO.-, and Z2 is preferably -CN, -NO2, or an alkyl- or arylsulphonyl group or an acyl group. The activated alkene of formula -Z1-CR7=CR"Ry may be attached to a group of formula -NR5- (wherein R5 is as hereinbefore; defined) to give a group of formula -NR5-SO-CR7=CR8R9, -NR5-SO2-CR~=CRBR9 or -NR5-CO-CR7-CR8R9. Preferred alkyl sulphonyl groups are -SO2- (C1,- alkyl) and preferred arylsulphonyl groups are phenylsulphonyl and tosyl. Preferred acyl groups are of the formula -CO-R5 wherein R5 is as hereinbefore defined, especially C1-4-alkyl or phenyl. It is preferred that R7 and R8 are both H.
Examples of activated alkenes include the Eollowing:
-CO-C=CH2, -NHCOCBr=CH2, -CO-CBr=CHBr, -SO2-C=CH2, -SO2-CH=CH2, -SO-CH=CH,, -COCCI =CCl2,, -SO2CH=CHC1, -CH=CH-CN, -CH=CH-NO2/ -C(CN)=CH2, -NHSO,-CH=CH2, -N(CH3)SO2CH=CH2/ and
(Formula Removed)
A preferred group capable of undergoing an elimination and addition reaction is or comprises a group of the formula -Z^NR5-(CR11R11)m-X2 or -Z1 (CR11R11)m-X2, especially -Z1-NH-CH.-CH2-X2 and -Z1-CH2-CH2-X2 wherein X2 is a labile group and Z1 is as hereinbefore defined, especially -SO,-, R5 is as hereinbefore described, each R11 independently is halo, -NH2, carboxy or a group described above for R5; and m is 2, 3 or 4. Preferably the labile group represented by X2 is -OSO3H, -SSO3H, -OP03H2, or a salt thereof, halo (especially chloro) or acetoxy. The groups of formula -Z1 (CR11R11)m-X2 may be attached to a group of formula -NR5- as defined above, in which case the CR^R11 groups may be replaced by CHR11 groups.
In one embodiment the aforementioned groups of formula -Z^NR5-(CRliR11)m-X2, -NR5-Z1(CR11R11)m-X2, -Z1 (CHRn) m-X2, -Zl-CR7=CR8R9, -CR7=CR9-Z2 and -CZ2=CR7R9 are attached directly to an aromatic carbon atom, for example the carbon 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: -SO2CH2CH2OSO2H, -SO2(GH2)3OSO3H, -SO2CH2CH2C1, -SO2OH2CH2OPO3H2,
-iNHCH2CH2OSO3H, -SO2CH2CH2C)COCH3 , -SOCH2CH2OSO3H,
-SO2CH2CH2SSO3H, -NHSO2CH2CH2OSO3H, -NHSO2 (CH2)3SSO3H,
-NHSO2(CH3)4OSO3H, -N(CH3) SO2CH2OH2OSO3H, -SO2NH-CH (CH3) CH.-OSO.H, -SO2NH-
CH(CH2,CH2) CH2)-OSO3H, -SO2NH-C(OH) (CH3) CH2-OSO3H,
-SO2NH-CH(CH3) CH(Ph) -OSO3H, -SO2NHCH(OSO3H) OH2-OSO2H,
-SO2NHCH (COOH) CH2OSO3H, -SO2NHCH (Ph) OH2OSO3H,
-SO2NHC (CH3) CH2OSO3H, -SO2NHC (CH2OSO3H) 3,
-SO2NHC(CH3) (OH) CH2OSO3H, -SO2NH(CH2)3-OSO3H and salts thereof.
The dye molecules according to the present invention preferably contain I 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 electrophilic 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 electrophilic groups because this can lead to an improvement in the fixation and/or wash-fastness of the dyes to or on a substrate, possibly by providing the dye with points for crosslinking thereby enhancing immobilisation of the dye on the substrate.
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 dye 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 dye, 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 m 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 when 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 ß-sulphatoethylsulphonyl, ß-thiosulphatoethylsulphonyl and ß-phosphatoethylsulphonyl, which may also act as electrophilic groups. Basification 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 dye 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 temperature, 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 temperature is preferably between 0°C and 40°C, more preferably between 5°C and 40°C, especially between 11°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 first and second temperatures as referred tc above are as follows:
First Temperature in the rancre Second Temperature in the range
110029°C 35°C-170°C
11°C-29°C 40°C-160°C
11°C-29°C 50°C-130°C
11°C-29°C 4500110°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 pH 4 and pH 8, more especially between pH 6 and pH 8 and especially preferably approximately pH
Examples of first and second pHs as referred to above are as follows:
First pH Second pH in the range
1-4 5-7
6-8 8-15
6-8 8-13
6-8 8.1-10.9
7 8-15
7 8-13
7 8.1-10.3
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 nucleophilic 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:
-Z1-CR7=CR8R9, -CR7=CR9-Z2, -CZ2=CR7R9, -Z1-(CHR11) m-X2, -Z1-NR5 (CR11R11)M-x2 or -NR5-Z1- (CR1lR11)m-X2 as defined above, more especially -SO2-CH=CH2,
-sO2CH2CH2OsO3H, -sO2CH2CH2ssO3H, -SONHCH2CH2OSO3H, -SO2NH(CH2)3OSO3H,
-NHCOCH2CH2OSO3H, -N(CH3)SO2CH2OSO3H, -SO2CH2VH2-OPO3H2 and salts thereof.
According to a second aspect of the present invention there is provided a water-soluble dye comprising molecules which contain a nucleophilic group and an electrophilic group wherein:
(i) the nucleophilic group is of Formula (1) 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 nucleophilic
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 nucleophilic or electrophilic 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 electrophilic 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 example salts remaining from when 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 nucleophilic and electrophilic groups when the dye is heated or basified.
The water-soluble dye may contain or be free from molecules of other dyes, for example dyes which have an electrophiLic group but no nucleophilic group, dyes which have a nucleophilic group but no electrophilic group, and dyes which lack electrophilic and nucleophilic 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 (2) :
(Formula Removed)
wherein:
each Nu independently is a group of Formula (1) 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 electrophilic group as hereinbefore described. The molecules of Formula (2) are generally capable of joining together by formation of a covalent bond 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. Examples include dyes wherein 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 electrophilic group represented by EL may be any of the aforementioned electrophilic groups provided it is capable of forming a covalent bond with the nucleophilic group of another molecule of the dye when it is heated or basified. Preferably each EL independently is a group of formula:
-SO^O^OijOSC^H, -SC^CHaCHjSSOaH, -SO2CH2ai,OP03H,, -SO2NHCH2ai2OSO3H, -NHCOCH^CHjOSC^H or -N(CH3)SO2CH:CH2OSO3H or a salt thereof.
The chromophore represented by D is preferably of the azo, anthraquinone, 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 chromophores of the azo series are monoazo, disazo and trisazo chromophores. Preferred monoazo chromophores are of the formula -L1-N=N-L1- wherein each L1 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 pyridonylene, pyrazolonylene, benzthiazolene, isothiazolene, thiazolene and thiophene. The optional substituents which may be present on L1 are preferably selected from C^-alkyl, especially methyl; cyano; C^-alkoxy, especially methoxy,- hydroxy; thio; thione; amino; halo, especially chloro; and amido, especially acetamido, benzamido or sulphonamido; ureido; halomethyl; carboxy,- carboxymethyl ; cyclohexyl; phenyl; and mono- and dialkylamino.
A preferred monoazo compound according to the invention is of the Formula (3) or a tautomer or salt thereof:
wherein:
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 L1, L2, K and Nu independently is as hereinbefore defined.
Preferably each V independently is or comprises a group of the formula -Z1-CR7=CR8R9, -CR7=CR9-Z2, -CZ2=CR7R9, -Z1-NR5- (CR11R11)m-X2, -NR5-Z1-(CR11R11)m-X2 or -ZMCHR11)-X2 as hereinbefore defined, especially a group of formula Z-CH2CH2-O2S- wherein Z is HO3SO-, HO3SS- or H2O3PO-. A preferred disazo dye is of Formula (4):
(Formula Removed)
wherein each L1 independently and V and Nu are as hereinbefore defined.
A preferred trisazo dye is of Formula (5): V-L1 -N=N-I/ -N=N=L1 -NzrN-L1 - Nu (5) wherein each L1 independently and V and Nu are as hereinbefore defined.
A preferred water-soluble dye of Formula (2) wherein D is a triphenodioxazine chromophore is of the Formula (6)
(Formula Removed)
wherein:
each Y independently is a covalent bond, C1-4-alkylene,
-C(=O) - (C1-4-alkylene) -, phenylene -C(=O)-phenylene- or sulphophenylene ,• each U is H, SO2NR5R5, SO3R5, -SO2NHCH2CH2OSO3H or -SO2-CH2-CH2-X2; T1 and T2 are H, halo, C1-4-alkyl, or C1-4-alkoxy; X2 and each R5 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 electrophilic group,-provided that when B is H one or both of the groups represented by U is -SO2-CH2-CH2-X2 or -SO2NHCH2CH2-X2;
Each Y is preferably -C2H4- or -C3H6-. T1 and T2 are preferably CL or methyl.
B is preferably H or -SO2-CH2CH2-X2 wherein X2 is as hereinbefore defined.
A preferred water-soluble dye of Formula (2) wherein D is a formazan chromophore is of the Formula (7):
(Formula Removed)
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 {2) wherein D is a BDF chromophore is of the Formula (8):
(Formula Removed)
wherein:
each Nu and El independently is as hereinbefore defined and each K independently is 0, S or NR5; provided that two or more molecules of Formula (8) are capable of joining together by formation of a covalent bond between the nucleophilic group of one molecule and the electrophilic group of another molecule when the dye is heated or basified.
Dyes according to the invention may be prepared by analogous methods to those described in the dyestuff art except that intermediates are selected which will result in the dye having the aforementioned nucleophilic and electrophilic groups, for example condensation of a compound having a nucleophilic group with a compound having an electrophilic group, wherein 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. Pi:eferably the condensation is performed in a liquid medium, more preferably an aqueous medium or dime thy lsulphoxide. Precise conditions used will depend upon the nucleophilic and electrophilic 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-binding 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 example coupling an azo component and a coupling component, one having an alkylthiol or thiophenol nucleophilic group and the other having an
electrophilic group. Such a coupling will normally be performed at below 5°C, in water using NaNO2 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 NH/ 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. Examples of inorganic salts include alkali and alkali earth metal halides, carbonates, bicarbonates, 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 dye comprising molecules which, contain an electrophilic group and a secondary amino group which is free from aryl substituents; 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 Na2S to the mixture and it is preferred that the mixture is free from or substantially free from Na2S, particularly since this compound can lead to unpleasant odours. In this way the process advantageously does not smell of HjS.
Preferably the dye is completely dissolved in the aqueous solvent. The nucleophilic group, electrophilic 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 bond between the nucleophilic 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 basification 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 paper, textile materials and especially leather. 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.
Where the substrate is leather it is preferred that the heating is from a first temperature in the range 5°C to 35°C to a second temperature below 50°C. The basification is preferably from a first pH in the range 1 to 4 to a second pH below 7.
The 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 electrophilic 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. Examples of natural textile materials include wool, silk, hair and cellulosic materials, particularly cotton, jute, hemp, flax and linen.
Examples of semi-synthetic textiles include nitrocellulose, viscose rayon including TENCEL available from Courtaulds, England, cuprammonium rayon and cellulose acetates.
Examples of synthetic fibres include polyamides, polyesters, polyacrylonitriles and polyurethanes.
Examples of leathers include wet full chrome leather, retanned side leather, suede (dried chrome retanned) , nappa sheepskin and vegetable tanned leather.
The preferred coloration process for textiles 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 example 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 on a substrate at a temperature in the range 5°C to 40°C and the dye is heated to a second temperature 10°C to 75°C higher, preferably 20°C to 30°C higher than the first temperature, 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 example 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 on 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 Q. 4-alkanol, especially methanol or ethanol; a ketone, especially acetone or methylisobutyIketone; a glycol, especially diethylene glycol; 2-pyrrolidone,- 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 temperature, for example at a temperature 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 example at a pH in the range 8 to 11, the temperature may be raised from a first temperature in the range 10 to> 50°C, preferably 16 to 29°C, to a second temperature 15 to 130°C higher, preferably 20 to 50°C higher than che first temperature.
Alternatively both the pH and temperature may be raised during the third coloration process, preferably from the first to second temperatures 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 example 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 temperature 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 polypropylene glycol, 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 temporary 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 aforementioned, 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 basification.
Preferably the heating and/or basifying is from first t:o second temperatures and pHs as described hereabove.
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 or leather, coloured using a dye or a coloration process according to the invention.
The invention is further illustrated by the following examples in which all parts and percentages are by weight unless specified otherwise. Example 1
Preparation of
(Formula Removed)
Stage (a)
4 - Aminophenyl vinyl sulphone (3.66g,- 0 . 02M) was stirred in a mixture of water (50ml), ice (50g) and hydrochloric acid (35%; 5ml). To this mixture was added 2N sodium nitrite solution (10ml, 0.02M) at 0-5°C over 10 minutes and the mixture stirred for a further 10 minutes. Excess nitrous acid was then destroyed by addition of 10% sulphamic acid solution. Stage (b)
N-Phenylpiperazine (3.4g,- 0.021M) was dissolved in water (50ml) and added to the product of stage (a) at 0-5°C over 5 minutes. The pH was raised to 4.5 using 2N sodium carbonate solution and the yellow mixture stirred at 0-5°C and pH 4.5 for 1 hour to complete the coupling.
The product was collected by filtration, washed with water (5 x 100ml) and dried to give the title product (6g,- 0.0167M; strength = 99%)
Elemental analysis gave (%) : C, 59.6; H, 5.3; N, 15.2; S, 9.3.
Theory : C, 60.6; H, 5.6; N, 15.7; S, 9.0. Dyeing
A dyeing drum containing water (150g) at pH 5.5 - 6.0, wet full chrome leather (50g) and the title dye (1.5% by weight relative to the leather) was heated at 60°C + 5°C for 35 minutes. After 35 minutes emulsified anionic fat liquor (i.e. a water-oil emulsion, 1.5%) was added, followed 15 minutes later by formic acid (equivalent to half the weight of dye used). After a further 15 minutes the dyed leather pieces were removed from the dyebath, rinsed for 5 minutes with cold, soft running water, sammed (squeezed to remove water) , dried at 55°C + 5C'C and staked (staked means that the leather is softened by working it over a
blunt blade). The leather was dyed an attractive yellow shade with very good fastness properties,
Example 2
Preparation of
(Formula Removed)
5-Hydroxy-4- (2-methylamino-acetylamino) -naphthalene-2, 7-disulphonic acid (7.8g; 0.02M) was dissolved in water (100ml) at pH 7. This solution was added to a diazo suspension prepared according to the method of Example 1, Stage (a) at 0-5°C over 5 minutes. The pH was raised to pH 4.5 using 2N sodium carbonate solution and the red mixture stirred 2 hours at 0-5°C.
The title product was collected by filtration and dried to give 14g solid.
A sample of the title product was heated for 1 hour at 50°C and pH 7. A comparison of the 1H and 13C NMR spectra before and after heating showed a shift in frequencies for hydrogen and carbon atoms in the former vinyl sulphonyl group consistent with polymer/oligomer formation. Negative ion FAB and Ionspray MS spectra confirmed the formation of higher molecular weight species.
Example 3
Preparation of:
(Formula Removed)
The product of Example 1, Stage (a), was added to a suspension of 4-amino-5-hydroxy-naphthalene-2,7-disulphonic acid (7.8g; 0.02M) in water (30ml) and hydrochloric acid (35%; 5ml) at 0-5°C. The resultant suspension was stirred for 18 hours, allowing the temperature to rise slowly to 15°C. The product was collected by filtration, washed with dilute hydrochloric acid (2%; 3 x 35ml) and dried to give llg of solid.
Stage (b)
N-methyl-3-aminobenzylamine (2.72g,- 0.02M) was stirred in a mixture of water (80ml) and hydrochloric acid (35%; 7ml) . This solution was cooled to 0-5°C, 2N sodium nitrite (10.5ml; 0.021M) was added over 10 minutes and the mixture stirred for a further L0 minutes. Excess nitrous acid was then destroyed by addition of 10% sulphamic acid solution. Stage (c)
A monoazo product prepared using the method of stage (a) (12.35g; 0.02M) was dissolved in water (200ml) at pH 7 by the addition of 2N sodium carbonate solution (25ml; 0.05M). The solution was then cooled to 10°C and added to the product of stage (b) at 0-5°C over 15 minutes. The pH was raised to 4.8 using 2N sodium carboinate solution and the blue mixture stirred for 2 hours at 0-5°C. Hydrochloric acid (35%; 7ml) was added and the precipitate was collected by filtration, washed with dilute hydrochloric acid (2%; 3 x 50ml) and dried to give the title product (11.6g; strength = 92.9%) .
Elemental analysis and 1H-NMR confirmed the structure.
A solution of the title product was heated for 1 hour at 50°C and pH 7. Examination by Ion Spray LCMS confirmed polymer/oligomer formation.
Example 4
Preparation of:
(Formula Removed)
4,4'-Diaminodiphenylamine-2 -sulphonic acid (6.06g; 0.02M) was stirred in a mixture of water [70ml) and hydrochloric acid (35%; 12ml) for 1.5 hours. The suspension was cooled to 0-5°C and 2N sodium nitrite solution (2:0.7ml; 0.0414M) added over 15 minutes. The mixture was stirred a further 15 minutes at 0-5°C and excess nitrous acid was destroyed by the addition of 10% sulphamic acid solution. Naphthalene-1, 3, 6-trisulphonic acid (8.7g,- 0.02M) was added and the pH raised to 4 using 2N sodium carbonate solution. Stage (b)
A monoazo compound (12.25g,- 0.02M) prepared according to the method of Example J, stage (a), was dissolved in water (250ml) at pH 7 by the addition of 2N sodium carbonate; solution. This solution was
added to the tetrazo product of Example 4, stage (a), at 0-5°C over 15 minutes, maintaining the pH at 6.5 with small additions of 2N hydrochloric acid solution. The blue mixture was then stirred for 2 hours at 0-5°C and the product collected by filtration. The wet past was then res lurried in water (250ml) at 0-5°C and pH 6 to give a blue suspension. Stage (c)
N- (3 -Diethylaminophenyl) -2 -methylamino-acetamide (5.27g ; 0.021M) was dissolved in a mixture of water (70ml) and hydrochloric acid (35%; 3.5ml) . This solution was added at 0-5°C to the product of stage (b) over 10 minutes and the pH raised to 6 using 2N sodium carbonate solution. The black mixture was stirred for 18 hours at 20°C. The product was precipitated by the addition of hydrochloric acid (35%; 7ml) and then collected by filtration, washed with dilute hydrochloric acid (2%; 2 x 100ml) and dried to give the title product (16.5g; 80.5% strength).
A solution of the title product was heated for 1 hour at 50°C and pH 7. Ion Spray LCMS sprectra were consistent with the formation of higher molecular weight species. Examples 5 to 12
The method of Example 1 may be repeated except that in place of the compounds indicated in the first column of Table 1 there is used the compound indicated in the second column:
Table 1

(Table Removed)
Examples 13 to 20
The method of Example 2 may be repeated except that in place of the compounds indicated in the first column of Table 2 there is used the compound indicated in the second column:
Table 2
(Table Removed)
Examples 21 to 28
The method of Example 3 may be repeated except that in place of the compounds indicated in the first column of Table 3 there is used the compound indicated in the second column:
Table 3

(Table Removed)
Examples 29 to 41
The method of Example 4 may be repeated except that in place of the compounds indicated in the first column of Table 4 there is used the compound indicated in the second column:
Table 4

(Table Removed)
Examples 42 to 49
Further dyes may be prepared having the structures shown in Table 5 below:
Table 5

(Table Removed)

We Claim :
1. A dye comprising molecules which contain a nucleophilic group and an electrophilic group characterised in that (i) the molecules are capable of joining together by formation of a covalent bond between the nucleophilic group of one molecule and the electrophilic group of another molecule when the dye is heated, acidified or basified; and (ii) the nucleophilic group is or comprises a secondary amino group which is free from aryl substituents.
2. A dye according to Claim 1 wherein the nucleophilic group is of Formula (1):
wherein:
R3 is optionally substituted alkyl and R1 and R2 are each
independently H, optionally substituted alkyl or optionally
substituted aryl; or R1 is H, optionally substituted alkyl or optionally substituted
aryl and R2 and R3, taken together with the C and N atoms to
which they are attached, form a 5- or 6-membered ring.
3. A dye according to any one of the preceding claims wherein the electrophilic group is an activated alkene or a group capable of undergoing an elimination and addition reaction.
4. A dye according to any one of the preceding claims wherein at least 40% of the dye molecules join together by formation of a covalent bond between the nucleophilic and electrophilic group when the dye is heated, acidified or basified.
5. 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 dye comprising molecules which contain an electrophilic group and a secondary amino group which is free from aryl substituents; and
(b) heating, acidifying or basifying or heating and basifying or heating and acidifying the dye thereby causing molecules of the dye to join together.
6. A process according to Claim 5 wherein the substrate is leather.
7. A process according to Claim 6 wherein said heating is from a first temperature in the range 5°C-35°C to a second temperature below 50°C and said basifying is from a first pH in the range 1-4 to a second pH below 7.
8. A process according to any one of Claims 5 to 7 wherein the water-solubility of the molecules joined together by step (b) is less than 10% of the water-solubility of the original dye.
9. A polymer or oligomer obtained or obtainable by heating or basifying a water-soluble dye according to any one of Claims 1 to 4.
10. Use of a dye according to any one of Claims 1 to 4 to form an < oligomerised or polymerised compound.
11. A dye substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
12. A process for the coloration of a substrate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.