WO2009101428A1

WO2009101428A1 - Polyazo compounds and their use in ink jet printing

Info

Publication number: WO2009101428A1
Application number: PCT/GB2009/050062
Authority: WO
Inventors: Clive Foster; Toshiki Fujiwara; Zyta Morgan
Original assignee: Fujifilm Imaging Colorants Limited; Fujifilm Corporation
Priority date: 2008-02-16
Filing date: 2009-01-23
Publication date: 2009-08-20
Also published as: GB201013118D0; GB2468830A; GB2468830B; GB0802874D0

Abstract

A compound of Formula (1) or a salt thereof: A-N=N-M1-N=N-M2-N=N-E wherein A is an optionally substituted carbocyclic or optionally substituted heterocyclic aromatic group; M1is either: (i) an optionally substituted naphthylene group, or (ii) an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups; M2 is an optionally substituted heterocyclic aromatic group; and E is an optionally substituted heterocyclic aromatic group. Also compositions, inks, ink-jet printing processes and ink-jet cartridges.

Description

POLYAZO COMPOUNDS AND THEIR USE IN INK JET PRINTING

This invention relates, among other things, to polyazo compounds and their salts, processes for preparing the same, compositions derived therefrom (e.g. ink compositions), printing processes using the same (e.g. ink jet printing processes), cartridges, printed substrates and ink sets.

Ink Jet printing ("IJP") is a non-impact printing technique in which droplets of ink are ejected through a fine nozzle onto a substrate without bringing the nozzle into contact with the substrate. There are many demanding performance requirements for inks used in IJP. For example, it is desirable that they provide sharp, non-feathered images having good optical density, water-fastness, light- fastness, resistance to fading in the presence of oxidising air pollutants (e.g. ozone) and low bronzing (i.e. showing a bronze-like appearance). The inks are often required to dry quickly when applied to a substrate to prevent smudging, but they should not form a crust over the tip of an ink jet nozzle because this will stop the printer from working. The inks should also be stable to storage over time without decomposing or forming a precipitate which could block the fine nozzle. Accordingly, the dyes for use in inks for IJP therefore desirably should have an acceptable solubility in the liquid medium (e.g. water, organic solvent or mixture of water and organic solvent) and storage stability as an ink, as well as a satisfactory capability of providing an attractive print shade (hue), good optical density, good fastness to light and/or oxidising air pollutants (e.g. ozone) and good fastness to water.

In the prior art various types of dyes are disclosed for use in ink jet printing. The following documents disclose azo dyes for use in ink jet printing: EP 1391488 A, WO 2004/016699, EP 1403338 A, EP 1403339 A, WO 2004/029166, US 2004/0154496, WO 2004/113463, WO 03/106572, WO 03/087238, US 2005/0243151 A, EP 1437387 A and JP 2007/099823 A.

US 2005/0243151 A and EP 1437387 A, for example, describe disazo dyes having two heterocyclic aromatic groups and a carbocyclic aromatic group. WO 03/087238 and WO 2004/113463 discloses mostly disazo dyes but also discloses a trisazo dye having two heterocyclic aromatic groups and two carbocyclic aromatic groups (phenyl).

However, there remains a need for dyes and inks which are improved in one or more of the above performance requirements.

In particular, it is among the objects of the present invention to provide dyes and inks which impart one or more of the following properties to prints made by ink jet printing: a neutral colour shade (e.g. neutral black shade), good fastness to oxidising air pollutants (e.g. ozone), good light fastness, low bronzing and a long wavelength of absorption (λ_max). Other objects of the present invention will be apparent from the following description.

In view of the above considerations the present invention has been made. In one aspect, the present invention provides a compound of Formula (1 ) or a salt thereof:

A-N=N-MI -N=N-M2-N=N-E

Formula (1 ) wherein

A is an optionally substituted carbocyclic or optionally substituted heterocyclic aromatic group;

M1 is either:

(i) an optionally substituted naphthylene group, or (ii) an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups;

M2 is an optionally substituted heterocyclic aromatic group; and

E is an optionally substituted heterocyclic aromatic group.

The compound of Formula (1 ) or a salt thereof has been found to be useful as a dye in inks for ink jet printing. In another aspect the present invention provides a composition comprising a compound of Formula (1 ) or a salt thereof and a liquid medium or a low melting point solid medium. The composition has been found to be useful as an ink composition, especially one for use in ink jet printing. The composition is preferably a black ink. In still another aspect, the present invention provides a process for printing an image on a substrate comprising applying thereto a composition according to the present invention. The printing is desirably ink jet printing, i.e. wherein the composition is applied to the substrate by means of an ink jet printer.

In yet another aspect, the present invention provides a substrate printed with a composition according to the present invention. The substrate is desirably a paper or other recordation substrate known in the art. The composition is preferably printed on the substrate by an ink jet printer.

In a further aspect, the present invention provides an ink jet printer cartridge, optionally refillable, comprising one or more chambers wherein in at least one of the chambers there is present a composition according to the present invention.

Further details including preferred features of the present invention will now be described. The compound of Formula (1 ) or salt thereof has been found to be useful as a black dye, especially a black dye for use in an ink composition and more especially for use in an ink composition for ink jet printing. The compounds and salts thereof of the present invention have been found to be capable of providing prints of attractive, neutral black shades that are particularly well suited for the ink jet printing of text and images. Furthermore, compounds of Formula (1 ) or salts thereof may be used to provide printed images having good optical density and/or good fastness properties (e.g. light-fastness, wet-fastness and/or ozone-fastness, i.e. resistance to fading in the presence of oxidising air pollutants such as ozone). The prints may exhibit excellent colour due to the long wavelength of absorption by the compound of Formula (1 ) or salt thereof.

The compound of Formula (1 ) is a polyazo compound, i.e. it contains at least 3 azo groups. In some embodiments the compound of Formula (1 ) may comprise more than 3 azo groups (e.g. 4 or 5). Preferably the compound of Formula (1 ) does not contain more than 3 azo groups (i.e. it is a trisazo compound).

The term carbocyclic aromatic group herein means any aromatic group in which all of the atoms in the aromatic ring of the aromatic group are carbon atoms. Preferred examples of carbocyclic aromatic groups include benzene radicals such as phenyl (monovalent benzene radical) and phenylene (divalent benzene radical) and naphthalene radicals such as naphthyl (monovalent naphthalene radical) and naphthylene (divalent naphthalene radical).

The term heterocyclic aromatic group herein means any aromatic group in which at least one of the atoms in the aromatic ring of the aromatic group is a hetero atom, i.e. other than a carbon atom. Preferred heteroatoms include sulfur, nitrogen and oxygen.

Herein, the terms carbocyclic and heterocyclic aromatic groups include unfused aromatic groups and fused aromatic groups. Unfused aromatic groups comprise one aromatic ring, e.g. benzene, thiophene, furan, pyrrole, thiazole, oxazole, imidazole, pyrazole rings and the like. Fused aromatic groups comprise two or more rings fused together. Examples of fused carbocyclic aromatic groups include naphthalene and anthracene radicals and the like. Examples of fused heterocyclic aromatic groups include benzothiophene, benzofuran, indole, benzothiazole, benzoxazole, benzimidazole and thienothiazole radicals and the like. Carbocyclic aromatic groups for A are not particularly limited. Those known in the art may be used. However, preferred carbocyclic aromatic groups for A are optionally substituted benzene and optionally substituted naphthalene radicals. Such radicals include optionally substituted phenyl and optionally substituted phenyl naphthyl. These aromatic groups are shown below:

Heterocyclic aromatic groups for A, M2 and E are not particularly limited. Those known in the art may be used. However, preferred heterocyclic aromatic groups for A, M2 and E may be selected from the monovalent or divalent radicals of the following optionally substituted ring systems; thiophene, furan, pyrrole, pyridine, pyhmidine, pyrazine, triazine, imidazole, thiazole, oxazole, pyrazole, triazole, indole, benzothiophene, benzimidazole, benzothiazole, benzoxazole, thienothiazole, purine, quinoline and isoquinoline. Examples of these heterocyclic rings are shown below

Substituents for A, M1 , M2 and E are not particularly limited. Those known in the art may be used. However, preferred substituents for A, M1 , M2 and E are each independently selected from the following general list of substituents: optionally substituted alkyl; optionally substituted alkenyl; optionally substituted alkynyl; optionally substituted alkoxy; optionally substituted carbocyclic aromatic; optionally substituted heterocyclic aromatic; optionally substituted oxyaromatic (i.e. -O-Ar, where Ar is an optionally substituted carbocyclic or heterocyclic aromatic); optionally substituted amino; hydroxy; halogen; cyano (i.e. -CN); nitro (i.e. -NO₂); silyl; silyloxy; azo (especially carbocyclic or heterocyclic aromatic azo, i.e. -N=N- Ar); sulfo; carboxy; phosphato; -COOR¹; -OCOOR¹J -OCOR¹; -COR¹; -CONR¹R²; -OCONR¹R²; -SR¹; -SO₂NR¹R²; and -SO₂R¹; wherein R¹ and R² each independently represent H, optionally substituted alkyl, or optionally substituted aryl. Preferred substituents for A, M1 , M2 and E are, however, selected from optionally substituted alkyl; optionally substituted alkoxy; optionally substituted carbocyclic aromatic; optionally substituted heterocyclic aromatic; sulfo; -SO₂NR¹R²; carboxy; -CONR¹R²; nitro; and cyano. Where any substituent in the list is mentioned as being optionally substituted, that substituent may be substituted with any substituent including any substituent from the above list.

Herein, the following additional preferences apply to substituents: optionally substituted alkyl includes cycloalkyl and bicycloalkyl; preferably optionally substituted alkyl is optionally substituted Ci_-8 alkyl, more preferably optionally substituted Ci-6 alkyl, still more preferably optionally substituted Ci_-4 alkyl, especially optionally substituted methyl, ethyl and propyl; preferred optional substituents for the optionally substituted alkyl include hydroxy, amino, sulfo, carboxy, phosphato, Ci_-4-alkoxy and halogen (especially fluoro and chloro); optionally substituted alkenyl includes cycloalkenyl; preferably optionally substituted alkenyl is optionally substituted Ci-S alkenyl, more preferably optionally substituted Ci_-6 alkenyl, still more preferably optionally substituted Ci_-4 alkenyl; preferred optional substituents for the optionally substituted alkenyl include hydroxy, amino, sulfo, carboxy, phosphato, Ci_-4-alkoxy and halogen (especially fluoro and chloro); optionally substituted alkynyl includes cycloalkynyl; preferably optionally substituted alkynyl is optionally substituted Ci-S alkynyl, more preferably optionally substituted Ci-6 alkynyl, still more preferably optionally substituted Ci_-4 alkynyl; preferred optional substituents for the optionally substituted alkynyl include hydroxy, amino, sulfo, carboxy, phosphato, Ci_-4-alkoxy and halogen (especially fluoro and chloro); optionally substituted alkoxy is preferably optionally substituted Ci_-8 alkoxy, more preferably optionally substituted Ci-6 alkoxy, still more preferably optionally substituted Ci_-4 alkoxy, especially optionally substituted methoxy, ethoxy and propoxy; preferred optional substituents for the optionally substituted alkoxy include hydroxy, amino, sulfo, carboxy, phosphato, Ci_-4-alkoxy and halogen (especially fluoro and chloro); optionally substituted carbocyclic aromatic is preferably optionally substituted phenyl or naphthyl (especially phenyl); preferred optional substituents for the optionally substituted phenyl or naphthyl are 1 to 3 substituents selected from sulfo, carboxy, phosphato, Ci_-4-alkoxy, hydroxy, amino and N carrying one or two Ci-4-alkyl groups optionally carrying a sulfo, carboxy, phosphato, Ci_-4-alkoxy, amino or hydroxy group; optionally substituted heterocyclic aromatic is preferably an optionally substituted thiophene, furan, pyrrole, pyridine, pyrimidine, pyrazine, triazine, imidazole, thiazole, oxazole, pyrazole, indole, benzothiophene, benzimidazole, benzothiazole, benzoxazole, thienothiazole, purine, quinoline or isoquinoline radical; preferred optional substituents for the optionally substituted heterocyclic aromatic are 1 to 3 substituents selected from sulfo, carboxy, phosphato, Ci_-4- alkoxy, amino, hydroxy and N carrying one or two Ci_-4-alkyl groups optionally carrying a sulfo, carboxy, phosphato, Ci_-4-alkoxy, amino or hydroxy group; optionally substituted oxyaromatic is preferably optionally substituted phenoxy; preferred optional substituents for the optionally substituted oxyaromatic are 1 to 3 substituents selected from sulfo, carboxy, phosphato, Ci_-4-alkoxy, amino, hydroxy and N carrying one or two Ci_-4-alkyl groups optionally carrying a sulfo, carboxy, phosphato, Ci_-4-alkoxy, amino or hydroxy group; optionally substituted amino is preferably amino (i.e. -NH₂) or amino substituted with one or two groups independently selected from optionally substituted alkyl, optionally substituted aryl (especially phenyl) and acyl (i.e. -COR¹) (said optionally substituted alkyl, aryl and acyl preferably each optionally carrying a sulfo, carboxy, phosphato, Ci_-4-alkoxy, amino or hydroxy group, especially a sulfo or carboxy); halogen is preferably fluoro, chloro or bromo. Preferably fluoro or chloro; azo includes optionally substituted carbocyclic or heterocyclic aromatic azo, preferably optionally substituted phenyl azo. Any two suitable substituents on A, M1 , M2 or E may link together to form a ring, i.e. a fused ring on A, M1 , M2 or E. Such a fused ring may be an aliphatic or aromatic (including carbocyclic or heterocyclic) ring.

Unless the context clearly indicates otherwise, a group herein which comprises a chain of three or more atoms signifies a group in which the chain wholly or in part may be linear, branched and/or form a ring.

Preferably A is an optionally substituted carbocyclic aromatic group. More preferably, A is an optionally substituted carbocyclic aromatic group selected from optionally substituted phenyl and optionally substituted naphthyl. In certain preferred embodiments, A is optionally substituted naphthyl (especially optionally substituted naphthyl substituted with at least 1 , more preferably 1 to 3, sulfo group(s)).

Substituents for A are not particularly limited. However, preferred substituents for A are those generally listed above, i.e. in the general list. Accordingly, among the possible substituents for A are carbocyclic or heterocyclic aromatic azo. Most preferred substituents for A are ionic groups which tend to increase water solubility (herein termed water solubilising groups), such as sulfo (- SO₃H), carboxy (-CO₂H), phosphato (-PO₃H₂) and sulfonamide (-SO₂NH₂), more especially sulfo and carboxy and most especially sulfo. Preferably, A carries one or more of such groups. Preferably, A is substituted with at least 1 , more preferably 1 to 3 sulfo groups.

In view of the foregoing, in particularly preferred embodiments, A is an optionally substituted phenyl or naphthyl group substituted with one or more water solubilising groups. In more particularly preferred embodiments A is an optionally substituted phenyl or naphthyl group substituted with one or more groups independently selected from the group consisting of: sulfo, carboxy, phosphato and sulfonamide. In particularly preferred embodiments A is most particularly preferably a phenyl or naphthyl group substituted with 1 to 3 sulfo groups. M1 is either: i) an optionally substituted naphthylene group, or ii) an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups. In case i) wherein the group represented by M1 in Formula (1 ) is an optionally substituted naphthylene group, preferably the optionally substituted naphthylene group is para connected to the azo groups in Formula (1 ) as shown by Formula i:

Formula i

Substituents for M1 , where M1 is an optionally substituted naphthylene group, are not particularly limited. However, preferred substituents for M1 in that case are those generally listed above, i.e. in the general list of substituents. Accordingly, among the possible substituents for M1 are carbocyclic or heterocyclic aromatic azo, water solubilising groups as mentioned for A above (i.e. sulfo, carboxy, phosphato and sulfonamide), optionally substituted alkyl and optionally substituted alkoxy groups. More preferred substituents for M1 are independently selected from water solubilising groups (especially sulfo and carboxy), optionally substituted alkyl (especially optionally substituted Ci_-4 alkyl (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen)) and optionally substituted alkoxy groups (especially optionally substituted Ci_-4 alkoxy (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen)). Still more preferably, M1 is substituted with at least 1 , more preferably 1 or 2 groups independently selected from sulfo, carboxy, optionally substituted Ci_-4 alkyl (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen) and optionally substituted Ci_-4 alkoxy (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen). Especially, M1 is substituted with at least 1 , more preferably 1 or 2 groups independently selected from sulfo, carboxy, methyl, ethyl, methoxy, ethoxy and substituted forms thereof (especially hydroxy substituted forms thereof).

In view of the foregoing, in particularly preferred embodiments of case i), M1 is an optionally substituted naphthylene substituted with 1 or 2 groups independently selected from sulfo, carboxy, optionally substituted Ci_-4 alkyl (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen) and optionally substituted Ci_-4 alkoxy (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen).

In case ii) wherein the group represented by M1 in Formula (1 ) is an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups, preferably the optionally substituted phenylene group is para connected to the azo groups in Formula (1 ) as shown by Formula ii:

Formula ii

wherein D is an electron donating group in the ortho position and the phenylene is optionally substituted in the remaining positions (with one or more electron donating groups and/or one or more other substituents). In the M1 optionally substituted phenylene group, for example of Formula ii, the phenylene may be substituted with two or more electron donating groups provided that at least one electron donating group is in a position ortho to one of the azo groups. Where the phenylene group of M1 has two or more electron donating groups, preferably each electron donating group is in a position ortho to one of the azo groups. Preferably, the M1 optionally substituted phenylene group has two electron donating groups and more preferably each electron donating group is in a position ortho to one of the azo groups. Such embodiments may be as shown by Formula iia

Formula iia wherein each D is an electron donating group in the ortho position and the phenylene is optionally substituted in the remaining positions.

In case ii) wherein the group represented by M1 in Formula (1 ) is an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups, preferably the electron donating group is/are independently selected from optionally substituted alkyl (especially optionally substituted Ci_-4 alkyl (preferably where an optional substituent on the alkyl is selected from sulfo, carboxy, hydroxy, amino and halogen)) and optionally substituted alkoxy (especially optionally substituted Ci_-4 alkoxy (preferably where an optional substituent on the alkoxy is selected from sulfo, carboxy, hydroxy, amino and halogen)). In certain embodiments, in case ii) wherein the group represented by M1 in

Formula (1 ) is an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups, the phenylene may be optionally substituted with one or more other substituents in addition to the at least one electron donating group. The one or more other substituents for M1 , where M1 is an optionally substituted phenylene group, are not particularly limited. However, preferred substituents for M1 in that case are those generally listed above, i.e. in the general list of substituents. The one or more other substituents may, for example, be independently selected from: carbocyclic or heterocyclic aromatic azo groups and water solubilising groups as mentioned for A above (i.e. sulfo, carboxy, phosphato and sulfonamide). More preferred one or more other substituents for M1 in case ii) are independently selected from water solubilising groups (especially sulfo and carboxy). However, most preferably, M1 is not substituted by groups other than the electron donating groups. It has been found that if M1 is an optionally substituted naphthylene group or if M1 is an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups that fastness properties of the compound or salt thereof may be excellent whilst at the same time the wavelength of absorption (λ_max) may be beneficially provided at a longer wavelength than if M1 was a simple phenylene group. Shifts in absorption to longer wavelength can be beneficial in applications where the dye is blended with one or more other dyes having a shorter wavelength of absorption, e.g. to form an ink for ink jet printing.

The group represented by M2 in Formula (1 ) is an optionally substituted heterocyclic aromatic group. Preferred optionally substituted heterocyclic aromatic groups are listed above. More preferably, M2 is an optionally substituted 5-membered heterocyclic aromatic group. Still more preferably, M2 is an optionally substituted thiazole, optionally substituted thiophene, or optionally substituted imidazole radical. Even more preferably, M2 is an optionally substituted thiazole or optionally substituted thiophene radical. Substituents for M2 are not particularly limited. However, preferred substituents for M2 are those generally listed above, i.e. in the general list of substituents. More preferred substituents for M2 are alkyl, electron withdrawing groups or optionally substituted carbocyclic or heterocyclic aromatic groups (especially optionally substituted phenyl, naphthyl, thiazole, thiophene, imidazole, benzothiazole, benzothiophene or benzimidazole radicals). Preferably, M2 is substituted with one or more (especially 1 or 2) electron withdrawing groups or optionally substituted carbocyclic or heterocyclic aromatic groups. Preferred electron withdrawing groups include cyano, nitro, -COR¹, -COOR¹, halogen (especially F and Cl). More preferably M2 is substituted with 1 or 2 groups independently selected from cyano, -COR¹, -COOR¹, optionally substituted phenyl, optionally substituted naphthyl, thiazole radical and thiophene radical. Most preferably M2 is substituted with 1 or 2 groups independently selected from the group consisting of optionally substituted phenyl, optionally substituted naphthyl and cyano, especially the group consisting of optionally substituted phenyl and optionally substituted naphthyl. M2 may additionally be substituted with one or more other substituents, e.g. optionally substituted Ci_-4 alkyl, especially methyl.

In view of the foregoing, in particularly preferred embodiments, M2 is an optionally substituted thiazole or thiophene radical substituted with 1 or 2 groups independently selected from cyano, -COR¹, -COOR¹, phenyl, naphthyl, thiazole radical and thiophene radical and optionally substituted with one or more other substituents (e.g. optionally substituted Ci_-4 alkyl, especially methyl).

The group represented by E in Formula (1 ) is an optionally substituted heterocyclic aromatic group. Preferred optionally substituted heterocyclic aromatic groups are listed above. More preferably, E is an optionally substituted pyridine, optionally substituted pyrimidine or optionally substituted pyrazole radical. Most preferably, E is an optionally substituted pyridine or optionally substituted pyrimidine radical. Preferred substituents for E are those generally listed above, i.e. in the general list of substituents. Preferably, E is substituted with one or more (especially 1 to 4, more especially 1 to 3) groups. Such groups may be selected from electron withdrawing groups and electron donating groups. Preferred electron withdrawing groups for E include cyano, nitro, -COR¹, -COOR¹ and halogen. Preferred electron donating groups for E include optionally substituted alkyl and optionally substituted amine (especially amine substituted with an optionally substituted carbocyclic or heterocyclic aromatic group). The amine substituted with an optionally substituted carbocyclic or heterocyclic aromatic group is preferably an optionally substituted phenylamine group. Preferably, E is at least substituted with 1 or 2, especially 2, optionally substituted phenylamine groups. The phenylamine groups especially are substituted with one or more (especially one) water solubilising groups selected from sulfo, carboxy and phosphato (especially sulfo). More preferably, E is substituted with 1 to 4 groups independently selected from optionally substituted alkyl, optionally substituted amine (especially optionally substituted phenylamine group), cyano, -COR¹, and -COOR¹ wherein R¹ independently represents H, optionally substituted alkyl, or optionally substituted aryl. Especially, E is substituted at least with 1 or 2 (especially 2) optionally substituted phenylamine groups and optionally an electron withdrawing group (especially cyano). E may additionally be substituted with one or more other substituents, e.g. optionally substituted Ci_-4 alkyl, especially methyl.

In view of the foregoing, in particular preferred embodiments, E is an optionally substituted pyridine or optionally substituted pyrimidine radical substituted with 1 to 4 groups independently selected from optionally substituted alkyl, cyano, -COR¹, -COOR¹ and optionally substituted amine (especially optionally substituted phenylamine, more especially sulfo substituted phenylamine) wherein R¹ independently represents H, optionally substituted alkyl, or optionally substituted aryl. It is especially preferred that E is an optionally substituted pyridine or optionally substituted pyrimidine radical at least substituted with 1 or 2 optionally substituted phenylamine groups.

Embodiments listed (1 )-(3) below represent very preferred embodiments of the compound of Formula (1 ) or salt thereof: (1 ) A compound of Formula (1 ) or a salt thereof wherein A is an optionally substituted phenyl or optionally substituted naphthyl group substituted with one or more water solubilising groups; M1 is either: i) an optionally substituted naphthylene group substituted with O, 1 or

2 groups independently selected from water solubilising groups, optionally substituted Ci_-4 alkyl and optionally substituted Ci_-4 alkoxy; or ii) an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups which is either an optionally substituted Ci_-4 alkyl or an optionally substituted Ci_-4 alkoxy group;

M2 is an optionally substituted thiazole or optionally substituted thiophene radical substituted with 1 or 2 groups independently selected from electron withdrawing groups, optionally substituted phenyl, optionally substituted naphthyl, optionally substituted thiazole radical and optionally substituted thiophene radical; and

E is an optionally substituted pyridine or optionally substituted pyhmidine radical substituted with 1 to 4 groups selected from optionally substituted alkyl, optionally substituted amine or electron withdrawing groups.

(2) A compound of Formula (1 ) or a salt thereof wherein: A is an optionally substituted phenyl or optionally substituted naphthyl group substituted with one or more groups independently selected from the group consisting of: sulfo, carboxy, phosphato and sulfonamide; M1 is either: i) an optionally substituted naphthylene group substituted with 0, 1 or

2 groups independently selected from sulfo, carboxy, optionally substituted Ci_-4 alkyl (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen) and optionally substituted Ci_-4 alkoxy (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen); or ii) an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups which is either an optionally substituted Ci_-4 alkyl (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen) or an optionally substituted Ci_-4 alkoxy (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen); M2 is an optionally substituted thiazole or optionally substituted thiophene radical substituted with 1 or 2 groups independently selected from cyano, - COR¹, -COOR¹, optionally substituted phenyl, optionally substituted naphthyl, optionally substituted thiazole radical and optionally substituted thiophene radical; and E is an optionally substituted pyridine or optionally substituted pyrimidine radical substituted with 1 to 4 groups independently selected from optionally substituted Ci_-4 alkyl, cyano, -COR¹, -COOR¹ and optionally substituted amine.

(3) A compound of Formula (1 ) or a salt thereof wherein

A is an optionally substituted phenyl or optionally substituted naphthyl group substituted with 1 to 3 sulfo groups; M1 is either: i) an optionally substituted naphthylene group substituted with 0, 1 or

2 groups independently selected from optionally substituted Ci_-4 alkyl (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen) and optionally substituted Ci_-4 alkoxy (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen); or ii) an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups which is either an optionally substituted Ci_-4 alkyl (preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen) or an optionally substituted Ci_-4 alkoxy

(preferably where an optional substituent is selected from sulfo, carboxy, hydroxy, amino and halogen);

M2 is an optionally substituted thiazole or optionally substituted thiophene radical substituted with 1 or 2 groups independently selected from cyano, - COR¹, -COOR¹, optionally substituted phenyl, optionally substituted naphthyl, thiazole radical and thiophene radical; and

E is an optionally substituted pyridine or optionally substituted pyrimidine radical substituted with 1 to 4 groups independently selected from optionally substituted Ci_-4 alkyl (especially methyl), cyano, -COR¹, -COOR¹ and optionally substituted sulfo substituted phenylamine.

Examples of the present invention include the following compounds A-F and especially salts thereof (more especially lithium, sodium and mixed lithium- sodium salts thereof). It will be appreciated that these compounds and salts are merely illustrative of the present invention and are not limiting on the scope thereof.

Further examples of compounds and salts thereof according to the present invention may be provided by coupling the components indicated in the Table below. It will be appreciated that the components shown and the resultant compounds and salts are merely illustrative of the present invention and are not limiting on the scope thereof. The table below shows examples of components that may be used to provide the A, M1 , M2 and E components. Any of the components shown for A, M1 , M2 and E may be coupled together. It will be understood by those skilled in the art that A components require at least an amine substituent that can be diazotised whereas M1 and M2 components require both a position suitable for azocoupling to take place and an amine substituent that can be diazotised, whereas E components require a position suitable for azocoupling. In some cases the amino groups may be masked, for example, as nitro groups that require reduction, before further reaction.

The salts of compounds of Formula (1 ) are preferred. Preferred salts are alkali metal salts, especially lithium, sodium and potassium salts, ammonium and substituted ammonium salts and mixed salts thereof (i.e. of at least two of these). Especially preferred salts are selected from ammonium, substituted ammonium, lithium and sodium salts and mixed salts thereof (i.e. of at least two of these). Accordingly, any groups shown herein in a free acid form may be provided in a salt form. For instance, SO3H groups are preferably provided in salt form, e.g. SOsLi, SOsNa etc., and similarly for carboxy (COOH), phosphato (PO3H2) and any other groups that are capable of forming salts. The compound may be converted into a salt using known techniques.

The compound of formula (1 ) or salt thereof may exist in tautomeric forms (tautomers) other than those shown in this specification and, accordingly, the Formulae herein include all possible tautomeric forms of the compound or salt. Thus, all other tautomeric forms are included within the scope of the present invention and the claims of this patent specification.

For the avoidance of doubt, the Formulae herein, including in the claims, encompass the compounds and salts in all possible isotopic, isomeric and/or enantiomeric forms and conformations. Compounds of Formula (1 ) and salts thereof are preferably free from fibre reactive groups because such groups tend to reduce the long-term storage stability of inks for IJP. The term fibre reactive group is well understood in the art and is used for example in EP 0356014 A1. Fibre reactive groups are capable, under suitable conditions, of reacting with the hydroxy groups present in cellulosic fibres or with the amino groups present in natural fibres to form a covalent linkage between the fibre and the compound.

Compounds of the present invention and salts thereof have been found particularly to exhibit excellent light fastness and ozone fastness as well as have a long wavelength of absorption (λ_max). This makes them especially suitable as dyes for inks for ink jet printing.

The invention also provides a process for the preparation of a compound of Formula (1 ) or salt thereof, as hereinbefore defined. The process may, for example, comprise the following reaction scheme, which is by way of illustration only and not limiting on the scope of the invention. The reaction scheme utilises reaction types well known to those skilled in the art of azo dye synthesis and heterocycle synthesis. It will be appreciated that variation of the components A, M1 , M2 and E in the scheme below can be achieved according to the choice of starting materials.

In another aspect, the present invention provides a composition comprising a compound of Formula (1 ) or a salt thereof and a liquid medium or a low melting point solid medium.

The composition of the present invention is preferably an ink composition, more preferably an ink composition for ink jet printing.

The compositions of the present invention have been found to be capable of providing prints of attractive, neutral black shades that are particularly well suited for the ink jet printing of text and images. The compositions have good storage stability and low tendency to block the very fine nozzles used in ink jet printers. Furthermore, the compositions may be used to provide printed images having good optical density, good fastness properties (e.g. light-fastness, wet-fastness and/or ozone-fastness, i.e. resistance to fading in the presence of oxidising air pollutants such as ozone).

The composition of the present invention, which may be used in the printing process of the invention, preferably comprises:

(a) from 0.01 to 30 parts of a compound of Formula (1 ) or salt thereof; and (b) from 70 to 99.99 parts of a liquid medium or a low melting point solid medium; wherein all parts are by weight and the number of parts of (a)+(b)=100.

The number of parts of component (a) is preferably from 0.1 to 20, more preferably from 0.5 to 15, further preferably from 1 to 10 and especially from 1 to 5 parts. The number of parts of component (b) is preferably from 99.9 to 80, more preferably from 99.5 to 85, further preferably from 99 to 90 and especially from 99 to 95 parts.

When the medium is a liquid, preferably component (a) is completely dissolved in component (b). Preferably component (a) has a solubility in component (b) at 20°C of at least 10%. This allows the preparation of liquid dye concentrates (i.e. concentrates of the compound or salt in a liquid medium) which may be used to prepare inks and reduces the chance of the compound or salt precipitating if evaporation of the liquid medium occurs during storage.

Preferred liquid media include water or a mixture of water and an organic solvent. Alternatively, the liquid medium may comprise an organic solvent and be substantially free from water. Compositions comprising such liquid media may be suitable as ink compositions and more preferably as ink compositions for use as an ink jet printing ink.

When the liquid medium comprises a mixture of water and an organic solvent, the weight ratio of water to organic solvent is preferably from 99:1 to 1 :99, more preferably from 99:1 to 50:50 and especially from 95:5 to 80:20.

It is preferred that the organic solvent present in the mixture of water and organic solvent is a water-miscible (water soluble) organic solvent or a mixture of such solvents. Preferred water-miscible organic solvents include Ci-6-alkanols, preferably methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert- butanol, n-pentanol, cyclopentanol and cyclohexanol; linear amides, preferably dimethylformamide or dimethylacetamide; ketones and ketone-alcohols, preferably acetone, methyl ether ketone, cyclohexanone and diacetone alcohol; water- miscible ethers, preferably tetrahydrofuran and dioxane; diols, preferably diols having from 2 to 12 carbon atoms, for example pentane-1 ,5-diol, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol and thiodiglycol and oligo- and poly-alkyleneglycols, preferably diethylene glycol, thethylene glycol, polyethylene glycol and polypropylene glycol; triols, preferably glycerol and 1 ,2,6-hexanetriol; mono-Ci_-4 alkyl ethers of diols, preferably mono-Ci_-4 alkyl ethers of diols having 2 to 12 carbon atoms, especially 2-methoxyethanol, 2-(2- methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)-ethanol, 2-[2-(2- methoxyethoxy)ethoxy]ethanol, 2-[2-(2-ethoxyethoxy)-ethoxy]-ethanol and ethyleneglycol monoallylether; cyclic amides, preferably 2-pyrrolidone, N-methyl-2- pyrrolidone, N-ethyl-2-pyrrolidone, caprolactam and 1 ,3-dimethylimidazolidone; cyclic esters, preferably caprolactone; sulfoxides, preferably dimethyl sulfoxide and sulfolane. Preferably the liquid medium comprises water and 2 or more, especially from 2 to 8, water-soluble organic solvents.

Especially preferred water-soluble organic solvents are cyclic amides, especially 2-pyrrolidone, N-methyl-pyrrolidone and N-ethyl-pyrrolidone; diols, especially 1 ,5-pentane diol, ethyleneglycol, thiodiglycol, diethyleneglycol and thethyleneglycol; and mono- Ci_-4 alkyl and Ci_-4 alkyl ethers of diols, more preferably mono- Ci_-4 alkyl ethers of diols having 2 to 12 carbon atoms, especially ((2-methoxy-2)-ethoxy)-2-ethoxyethanol. Examples of further suitable liquid media comprising a mixture of water and one or more organic solvents are described in US 4,963,189, US 4,703,113, US 4,626,284 and EP 42515OA.

When the liquid medium comprises an organic solvent substantially free from water, (i.e. less than 1 % water by weight) the solvent preferably has a boiling point of from 30° to 200°C, more preferably of from 40° to 150°C, especially from 50 ° to 125°C. The organic solvent may be water-immiscible, water-miscible or a mixture of such solvents. Preferred water-miscible organic solvents are any of the hereinbefore described water-miscible organic solvents and mixtures thereof. Preferred water-immiscible solvents include, for example, aliphatic hydrocarbons; esters, preferably ethyl acetate; chlorinated hydrocarbons, preferably CH₂CI₂; and ethers, preferably diethyl ether; and mixtures thereof.

When the liquid medium comprises a water-immiscible organic solvent, preferably a polar solvent is included because this enhances solubility of the compound in the liquid medium. Examples of polar solvents include Ci_-4-alcohols. In view of the foregoing preferences it is especially preferred that where the liquid medium is an organic solvent free from water it comprises a ketone (especially methyl ethyl ketone) and/or an alcohol (especially a Ci_-4-alkanol, more especially ethanol or propanol). The organic solvent free from water may be a single organic solvent or a mixture of two or more organic solvents. It is preferred that when the medium is an organic solvent free from water it is a mixture of 2 to 5 different organic solvents. This allows a medium to be selected which gives good control over the drying characteristics and storage stability of the ink composition.

Liquid media comprising an organic solvent free from water are particularly useful where fast drying times are required and particularly when printing onto hydrophobic and non-absorbent substrates, for example plastics, metal and glass.

In one embodiment, the liquid medium comprises an oxidant. We have found that the presence of an oxidant in the liquid medium may further improve the stability of the composition. Preferred oxidants include KIO3, KIO₄, K2S2O8, 1 ,4- benzoquinone, tetrachloro benzoquinone and mixtures thereof.

Preferred low melting solid media have a melting point in the range from 6O⁰C to 125°C. Suitable low melting point solids include long chain fatty acids or alcohols, preferably those with C18-24 chains, and sulfonamides. The compound of Formula (1 ) or salt thereof may be dissolved in the low melting point solid or may be finely dispersed in it.

In one preferred embodiment, the pH of the composition is from 4 to 11 , more preferably from 5 to 9. The desired pH may be obtained by the addition of a pH-adjusting agent such as an acid, base or pH buffer. The amount of pH adjusting agent used will vary according to the desired pH of the ink and is preferably present in an amount of up to 10% by wt of the total composition, more preferably from 0.1 to 6% by wt of the total composition. Preferred pH adjusting agents are pH buffers which, in embodiments, are more preferably pH buffers which maintain a pH of 4 to 8. In one preferred embodiment, the composition comprises a pH buffer and has a pH of 4 to 8.

The viscosity of the composition at 25⁰C is preferably less than 5OcP, more preferably less than 2OcP and especially less than 5cP. When the composition according to the invention is used as an ink jet printing composition, the composition preferably has a concentration of less than 500 parts per million, more preferably less than 100 parts per million of halide ions. It is especially preferred that the composition has less than 100, more preferably less than 50 parts per million of divalent and thvalent metals, wherein parts refer to parts by weight relative to the total weight of the composition. We have found that purifying the compositions to reduce the concentration of these undesirable ions reduces nozzle blockage in ink jet printing heads, particularly in thermal ink jet printers. Similarly low levels as divalent and thvalent metals are also preferred. Preferably, compositions of the present invention suitable for use as ink compositions in an ink-jet printer have been filtered through a filter having a mean pore size below 10μm, more preferably below 3μm, especially below 2μm, more especially below 1μm. This filtration removes particulate matter that could otherwise block the fine nozzles found in many ink-jet printers.

The compounds or salts of the invention may be used as the sole colorant in inks because of their attractive black shade. However, if desired, one may combine the present compounds or salts with one or more further colorants if a slightly different shade is required for a particular end use. The further colorants are preferably dyes. When further colorants are included in the composition these are preferably selected from black, magenta, cyan, yellow, red, green, blue and orange colorants and combinations thereof. Suitable black, magenta, cyan, yellow, red, green, blue and orange colorants for this purpose are known in the art. The compositions of the present invention may also contain additional components known for use in ink jet printing inks, for example viscosity and surface tension modifiers, corrosion inhibitors, biocides, kogation reducing additives, metal chelators and surfactants which may be ionic or non-ionic.

In still another aspect, the present invention provides a process for printing an image on a substrate comprising applying thereto a composition according to the present invention.

In yet another aspect, the present invention provides a substrate printed with a composition according to the present invention. The substrate is preferably printed with the composition by the process according to the preset invention. The term image herein includes both a graphic image and text.

Preferably, the printing is ink jet printing, i.e. the composition is applied to the substrate by means of an ink jet printer. The ink jet printer preferably applies the composition to the substrate in the form of droplets which are ejected through a small orifice onto the substrate. Preferred ink jet printers are piezoelectric ink jet printers and thermal ink jet printers. In thermal ink jet printers, programmed pulses of heat are applied to the composition in a reservoir by means of a resistor adjacent to the orifice, thereby causing the composition to be ejected in the form of small droplets directed towards the substrate during relative movement between the substrate and the orifice. In piezoelectric ink jet printers the oscillation of a small crystal causes ejection of the composition from the orifice.

The substrate is not particularly limited and may be any recordation substrate known in the art. The substrate is preferably paper, plastic, a textile, metal or glass (typically paper). The substrate, more preferably, is a coated substrate such as a coated paper or coated plastic, especially coated paper. Preferred plain or coated papers are papers which may have an acid, alkaline or neutral character. Photographic papers are particularly preferred.

In a further aspect, the present invention provides an ink jet printer cartridge, optionally refillable, comprising one or more chambers wherein in at least one of the chambers there is present a composition according to the present invention. The cartridge may be any suitable design of cartridge for an ink jet printer.

In this specification, unless the context clearly indicates otherwise, as used herein plural forms of the terms herein are to be construed as including the singular form and vice versa.

Throughout the description and claims of this specification, unless the context clearly indicates otherwise, the words "comprise" and "contain" and the like

(e.g. "have", "include" etc.) and variations of the words, for example "comprising" and "comprises", mean "including but not limited to", and are not intended to (and do not) exclude other components.

The use of any and all examples, or exemplary language (including, but not limited to, "for instance", "such as", "for example" and the like) provided herein, is intended merely to better illustrate the invention and does not indicate a limitation on the scope of the invention unless otherwise claimed. It will be appreciated that variations to the foregoing embodiments of the invention can be made while still falling within the scope of the invention. Each feature disclosed in this specification, unless stated otherwise, may be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

All of the features disclosed in this specification may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. In particular, the preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Likewise, features described in non-essential combinations may be used separately (not in combination).

It will be appreciated that many of the features described above, particularly of the preferred embodiments, are inventive in their own right and not just as part of an embodiment of the present invention. Independent protection may be sought for these features in addition to or alternative to any invention presently claimed.

The invention is further illustrated by the following Examples in which all parts and percentages are by weight unless specified otherwise. The Examples are only illustrative of the invention and are not limiting on the scope of the invention.

Example 1 Preparation of the Dye:

Stage 1 Preparation of monoazo (An example of A-N=N-MI -NH?)

2,5-Disulfo aniline (0.2mol) was stirred in water (300ml) at pH 7.5. Sodium nitrite (0.22mol, 15.2g) in water (60ml) was added. This solution was added dropwise, at 0 to 5⁰C to a slurry of concentrated hydrochloric acid (60ml, 0.69m) in ice (5Og) over 10 to 15 minutes, adding ice as required to maintain the temperature. The reaction mixture was stirred with 1 hour at 0-5⁰C. The excess nitrite was then destroyed using sulfamic acid solution.

Cleve's acid (0.2mol) was dissolved in water at room temperature and this solution was added to the diazonium mixture at 0-5⁰C over 5 min. The reaction mixture was stirred at pH 1 overnight, filtered, washed with 2mol dm^"3 HCI, then acetone and dried at room temperature then at 5O⁰C.

Stage 2

Preparation of 2-Amino-3-cvano-4-(4-chlorophenyl)thiophene

2-Amino-3-cyano-4-(4-chlorophenyl)thiophene was prepared using the methods as described in Barnes et al, Tetrahedron (2006) 62, 11311.

Preparation of disazo (An example of A-N=N-MI -N=N-M2-NH2)

The monoazo compound prepared in stage 1 (5.4g, 0.01 mol) was suspended in water (100ml). Lithium hydroxide was added to facilitate solution pH = 8. Concentrated HCI (5ml) was added (pH = 1.5), and the reaction mixture was cooled to 0-5⁰C. A solution of sodium nitrite (0.76g, 0.011 mol) in water (20ml) was added and the reaction was stirred at 0-5⁰C for 30 min. The excess nitrite was destroyed with sulfamic acid solution, and the diazonium salt was added to a solution of 2-amino-3-cyano-4-(4-chlorophenyl)thiophene (3.1 g, 1.1 mol) in methanol (200ml) at 4O⁰C with lithium acetate (5g) added to keep the pH at 5-6. The reaction mixture was stirred at 5O⁰C for 2 hours and at room temperature for 14 hours. Hydrochloric acid (2mol dm^"3) was added to lower the pH to 1.5. The mixture was then filtered, and washed with acetone and dried. Yield 4.6g

Stage 3

Preparation of 3-cyano-2,6-diamino(4-sulfophenyl)-4-methyl pyridine

2,6-Dianilino-4-methylnicotinonitrile was prepared analogously to the methods described in US3853895, incorporated herein by reference, from 2,6- dichloro-4-methylnicotinonithle and an excess of aniline at 12O⁰C. 2,6-Dianilino-4- methylnicotinonithle (24.Og, 0.08g mole) was added to a stirred mixture of sulfolane (56ml) and ethyl acetate (24ml). Chlorosulfonic acid (41.9g; 0.36g mole) was added to the slurry at 5 to 25⁰C in an exothermic reaction. After the addition was complete, the reaction mixture was heated to 4O⁰C for 4.5 hours. The reaction mixture was cooled to room temperature. The resultant viscous, amber oil was added to water (72ml) at less than 25⁰C to form a greenish/yellow solution which was stirred at room temperature for 30 minutes during which time a cream precipitate formed. The reaction mixture was cooled to 1 O⁰C, stirred for 30 minutes an then filtered. The filter cake was washed with acetonitrile (2 x 60ml). and dried in a vacuum oven at 6O⁰C to constant weight 34.7g (yield 94%)

Stage 4

Preparation of the Title Compound

The coupler 3-cyano-2,6-diamino(4-sulfophenyl)-4-methyl pyridine (from Stage 3) (4.56g) was stirred in water (50ml) at 36⁰C. The disazo prepared in stage 2 (5.8g) was added followed by LiOH (2mol dm^"3 ) solution to raise the pH to 7.4. The pH increased to 8.2 after stirring for 1 hour at 4O⁰C. 40% Lithium chloride solution (0.6ml) was added, followed by concentrated HCI (3ml). The temperature was raised to 5O⁰C and amyl nitrite (1.25ml) was added. The reaction mixture was stirred at 50 to 65⁰C for 1 hour then allowed to cool to 3O⁰C. LiOH (2mol dm^"3) was added to raise the pH to 8 and the solution was filtered. 40% LiCI solution (1 ml) was added to the filtrate followed by isopropanol (250ml). The suspension was stirred at 50-60⁰C for 1 hour, cooled to room temperature, filtered, washed with isopropanol, then acetone. The yield after dialysing to low conductivity was 0.77g. λ_max = 638nm Example 2 Preparation of the Dye:

This dye was prepared in an analogous fashion to the dye of Example 1 , substituting components as required to give the general structure A-N=N-MI - N=N-M2-N=N-E. λ_max = 644nm.

Example 3 Preparation of the Dye:

Stage 1

Preparation of the monoazo intermediate (An Example of A-N=N-MI -NH?)

2,5-Disulfo aniline (0.2mol) was stirred in water (300ml) at pH 7.5. Sodium nitrite (0.22mol, 15.2g) in water (60ml) was added. This solution was added dropwise, at 0-5⁰C to a slurry of concentrated hydrochloric acid (60ml, 0.69m) in ice (5Og) over 10-15 minutes, adding ice as required to maintain the temperature. The reaction mixture was stirred for 1 hour at 0 to 5⁰C. The excess nitrite was then destroyed using sulfamic acid solution. Cresidine (0.2mol) was dissolved in acetone at room temperature and this solution was added to the diazonium mixture at 0 to 5⁰C over 5 min. The mixture was stirred at pH 1 overnight, filtered, washed with 2mol dm^"3 HCI, then acetone and dried at room temperature then at 5O⁰C.

Stage 2

Preparation of 2-Amino-4-Naphthyl Thiazole (An Example of M2-NH?)

Ethyl acetate (120ml) was stirred at room temperature and 2- acetonaphthone (20.49g, 0.12mol) was added followed by tetrabutylammonium bromide (7.7g 0.024mol). Bromine (6.8ml 21.1g, 0.132mol) was then added dropwise, over 1 hour, at 30-35⁰C. The mixture was stirred at 30 to 40° C for 30min. Water (90ml) was then added dropwise over 5 min. The temperature was raised to 35⁰C and thiourea (8.2g. 0.11 mol) added portion-wise over 10 min. The reaction mixture was then stirred for 30 min at 35 to 4O⁰C. The white precipitate which formed was filtered, washed with ethyl acetate (60ml) then distilled water (30ml) to give 50.57g of a wet solid.

The above solid was then added to a solution of sodium hydroxide (12.9g. 0.32mol) in water (240ml) and stirred at 25-3O⁰C for 2 hour. The resultant beige solid was filtered, washed with water then isopropanol and dried at 6O⁰C. The yield was19.29g (71 %)

Stage 3 Preparation of the the Disazo Intermediate (An Example of A-N=N-MI -N=N-M2- NH?)

The monoazo compound prepared in stage 1 (5.4g, 0.01 mol) was suspended in water. The monazo compound was solubilised by adding lithium hydroxide to adjust the pH to 6. Concentrated HCI (5ml) was then added to adjust the pH to 2, the reaction mixture was cooled to 0 to 5⁰C and a thick gelatinous precipitate formed. A solution of sodium nitrite (0.76g, 0.011 mol) in water (20ml) was added and the reaction stirred at 0 to 5⁰C for 30 min. The excess nitrite was destroyed with sulfamic acid solution, and the diazonium salt added to a solution of 2-amino-4-naphthyl thiazole (2.5g, 1.1 mol) in methanol (100ml) at 5O⁰C with lithium acetate added to keep the pH in the range 5 to 6. The reaction mixture was stirred at 5O⁰C for 2 hours and at room temperature for 14 hour. It was then filtered, and washed with acetone and dried. Yield 8.8 g. (55%)

Stage 4

Preparation of the Title Dye The coupler 3-cyano-2,6-diamino(4-sulfophenyl)-4-methyl pyridine

(prepared as in stage 3 of Example 1 ) (7.9g, 0.016mol) was stirred in water (48ml) at 3O⁰C. The disazo intermediate prepared in Stage 2 (9.8g, 0.013M) was added followed by 2mol dm^"3 LiOH solution (17.5ml) to raise the pH to 10. The pH fell to pH 8 after stirring for 1 hour at 4O⁰C. 40% Lithium chloride solution (1 ml) was added, followed by concentrated HCI (3ml). The temperature was raised to 5O⁰C and amyl nitrite (2.25ml 0.016mol) was added. The reaction mixture was stirred a 50 to 6O⁰C. After 90 min. further aliquots of amyl nitrite were added, at intervals of 30 min, until no disazo could be seen on TLC or HPLC. The reaction was stirred at 50 to 6O⁰C for 1 hour after the final addition then allowed to cool to 3O⁰C. LiOH (2mol dm^"3) was added to raise the pH to 7.8 and the solution was filtered. LiCI solution (40%, 1 ml) was added to the filtrate followed by isopropranol (250ml). The suspension was stirred at 50-60⁰C for 1 hour, cooled to room temperature, filtered, washed with IPA, then acetone. The yield after dialysing to low conductivity was 5.9g. (36%)

Examples 4 to 47

The dyes in Table 1 were prepared using analogous procedures to Example 3. Table 1

Comparative Examples C1 and C2

Comparative Example C1 and C2 were prepared as described as synthesis Examples 1 and 2 of WO2004113463 which is incorporated herein by reference.

C1 C2

Example 48 Preparation of Inks

Inks were prepared from the comparative dyes and the dyes of Example 3 and 9 by dissolving 3.5g of a dye in 96.5ml of a liquid medium consisting of 5 parts 2-pyrrolidone; 5 parts thiodiethylene glycol; 1 part Surfynol^R™ 465 and 89 parts water and adjusting the pH to between pH 8 to 9 with sodium hydroxide. Surfynol^R™ 465 is a surfactant from Air Products. Inks such as this would have a viscosity of less than 20 cP 25⁰C; a surface tension in the range 20-65 dynes/cm at 25⁰C; less than 500ppm in total of divalent and thvalent metal ions (other than any divalent and trivalent metal ions bound to a colorant of Formula (1 ) or any other component of the ink); and less than 500ppm in total of halide ions. Table 2

Example 49 Ink-jet Printing

Inks prepared as described above were filtered through a 0.45 micron nylon filter and then incorporated into empty print cartridges using a syringe. These inks were then printed on to Canon Professional Photo Paper PR101.

The prints so formed were tested for ozone fastness by exposure to 1 ppm ozone at 25°C, 50% relative humidity for 24hrs in a Hampden 903 Ozone cabinet. Fastness of the printed ink to ozone is judged by the difference in the optical density before and after exposure to ozone, measured at two print depths. The prints were tested for light fastness by exposure to 70kl_ux for 100 hours in an Atlas Ci5000 Weatherometer.

Optical density measurements were performed using a Gretag spectral ino spectrophotometer set to the following parameters :

Measuring Geometry 0745°

Spectral Range 400 - 700nm

Spectral Interval 20nm llluminant D65

Observer 2° (CIE 1931 )

Density Ansi A

External Filler None

Ozone fastness and light fastness were assessed by the percentage change in the optical density of the print, where a lower figure indicates higher fastness. Results are shown in Table 3 Table 3

Table 3 shows that the inks of the present invention have a higher ozone fastness and light fastness than the comparative inks.

Further Ink Formulations

Further inks described in Tables I, II, III, IV may be prepared wherein the Dye described in the first column is the compound or salt of the present invention made in the above example of the same number. Numbers quoted in the second column onwards refer to the number of parts of the relevant ingredient and all parts are by weight. The inks may be applied to paper or other substrate as herein described by thermal or piezo ink jet printing.

The following abbreviations are used in Table I, II, III, IV:

PG = propylene glycol

DEG = diethylene glycol

NMP = N-methyl pyrollidone

DMK = dimethylketone

IPA = isopropanol

MEOH = methanol

2P = 2-pyrollidone

MIBK = methylisobutyl ketone

P12 = propane-1 ,2-diol

BDL = butane-2,3-diol

CET= cetyl ammonium bromide

PHO = Na₂HPO₄

TBT = tertiary butanol

TDG = thiodiglycol TABLE I

TABLE

TABLE

TABLE IV

Claims

1. A compound of Formula (1 ) or a salt thereof:

A-N=N-MI -N=N-M2-N=N-E

Formula (1 ) wherein A is an optionally substituted carbocyclic or optionally substituted heterocyclic aromatic group; M1 is either:

(i) an optionally substituted naphthylene group, or (ii) an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups; M2 is an optionally substituted heterocyclic aromatic group; and

E is an optionally substituted heterocyclic aromatic group.

2. A compound or salt as claimed in claim 1 wherein A is selected from optionally substituted phenyl and optionally substituted naphthyl.

3. A compound or salt as claimed in claim 1 or 2 wherein A is an optionally substituted phenyl or naphthyl group substituted with one or more groups independently selected from the group consisting of: sulfo, carboxy, phosphato and sulfonamide.

4. A compound or salt as claimed in any one preceding claim wherein M1 is an optionally substituted naphthylene group which is para connected to the azo groups in Formula (1 ) as shown by Formula i:

Formula i

5. A compound or salt as claimed in any one preceding claim wherein M1 is an optionally substituted naphthylene group which is substituted with one or more groups independently selected from sulfo, carboxy, optionally substituted Ci_-4 alkyl and optionally substituted Ci_-4 alkoxy.

6. A compound or salt as claimed in any one preceding claim wherein M1 is an optionally substituted phenylene group, having at least one electron donating group in a position ortho to one of the azo groups, para connected to the azo groups in Formula (1 ).

7. A compound or salt as claimed in any one preceding claim wherein M1 is an optionally substituted phenylene group wherein the at least one electron donating group is/are independently selected from optionally substituted alkyl and optionally substituted alkoxy.

8. A compound or salt as claimed in any one preceding claim wherein M2 is an optionally substituted 5-membered heterocyclic aromatic group.

9. A compound or salt as claimed in claim 8 wherein M2 is an optionally substituted thiazole, optionally substituted thiophene, or optionally substituted imidazole radical.

10. A compound or salt as claimed in any one preceding claim wherein E is an optionally substituted pyridine, optionally substituted pyrimidine or optionally substituted pyrazole radical.

11. A compound or salt as claimed in any one preceding claim wherein E is substituted with 1 to 4 groups.

12. A compound or salt as claimed in claim 11 wherein E is an optionally substituted pyridine or optionally substituted pyrimidine radical substituted with 1 to 4 groups independently selected from: optionally substituted alkyl, cyano, - COR¹, -COOR¹ and optionally substituted amine, wherein R¹ independently represents H, optionally substituted alkyl, or optionally substituted aryl.

13. A compound or salt as claimed in claim 12 wherein E is at least substituted with 1 or 2 optionally substituted phenylamine groups.

14. A compound of Formula (1 ) or a salt thereof as claimed in claim 1 wherein

A is an optionally substituted phenyl or optionally substituted naphthyl group substituted with one or more water solubilising groups; M1 is either: (i) an optionally substituted naphthylene group substituted with 0, 1 or 2 groups independently selected from water solubilising groups, optionally substituted Ci_-4 alkyl and optionally substituted Ci_-4 alkoxy; or (ii) an optionally substituted phenylene group having at least one electron donating group in a position ortho to one of the azo groups which is either an optionally substituted Ci_-4 alkyl or an optionally substituted Ci_-4 alkoxy group;

M2 is an optionally substituted thiazole or optionally substituted thiophene radical substituted with 1 or 2 groups independently selected from electron withdrawing groups, optionally substituted phenyl, optionally substituted naphthyl, thiazole radical and thiophene radical; and

E is an optionally substituted pyridine or optionally substituted pyrimidine radical substituted with 1 to 4 groups selected from optionally substituted alkyl, optionally substituted amine or electron withdrawing groups.

15. A salt as claimed in any one preceding claim wherein the salt is a lithium salt, sodium salt or mixed lithium-sodium salt.

16. A composition comprising a compound of Formula (1 ) or a salt thereof as claimed in any one preceding claim and a liquid medium or a low melting point solid medium.

17. A process for printing an image on a substrate comprising applying thereto a composition as claimed in claim 16.

18. A substrate printed with a composition as claimed in claim 16.

19. An ink jet printer cartridge, optionally refillable, comprising one or more chambers wherein, in at least one of the chambers, there is present a composition as claimed in claim 16.