GB2351292A - Compositions containing a water-dissipatable polymer, e.g. for an ink-jet ink - Google Patents

Abstract

A composition comprising a colorant, liquid medium and a water-dissipatable polymer obtainable from the reaction of a polymer carrying carboxyl groups with a polyalkylene oxide carrying carbodiimide group(s).

Description

SIVIC 60365 2351292 INK-JET COMPOSITIONS COMPRISING A WATER-DISSIPATABLE

POLYMER The invention relates to compositions containing colorants and to their use in inks for ink-jet printing.

Ink-jet printing involves printing an image onto a substrate using ink droplets ejected through a fine nozzle onto a substrate without bringing the fine nozzle into contact with the substrate.

There are many demanding performance requirements for colorants and inks used in ink-jet printing. For example they desirably provide sharp, nonfeathered images having good water-fastness, light-fastness and optical density. The inks are often required to dry quickly when applied to a substrate to prevent smudging, but they should not form a crust which would block the tip of the fine nozzle. The inks should also be stable to storage over time without decomposing or forming a precipitate which could also block the fine nozzle.

Thermal and piezoelectric ink-jet printers are widely used, thus there is a need for inks, suitable for use in both types of printers, having high colour strength and giving images having a high light-fastness and water-fastness when printed on a typical substrate, especially plain paper.

According to the present invention there is provided a composition comprising the components:

(a) a water-dissipatable polymer; (b) colorant; and (c) liquid medium; wherein the water-dissipatable polymer is obtainable from the reaction of a polymer carrying carboxyl groups with polyalkylene oxide carrying carbodiimicle group(s).

The number average molecular weight (Mn) for component (a) may be measured by any of the well known techniques, preferably by gel permeation chromatography ("gpc!'). The gpc method used for determining Mn preferably comprises applying the polymer to a chromatography column packed with cross-linked polystyrene/divinyl benzene, eluting the column with tetrahydrofuran at a temperature of 401C and assessing the Mn of the polymer compared to a number of a polystyrene standards of a known Mn.

Suitable cross-linked polystyrene/divinyl benzene chromatography columns are commercially available from Polymer Laboratories.

As an alternative to the gpc method for determining Mn one may use other methods, for example multi-angle light scattering.

Preferably the Mn of component (a) is less than 1,000,000 more preferably less than 100,000 and especially less than 10,000. Preferably the Mn of component (a) is greater than 1,000.

SMC60365 2 The polyalkylene oxide carrying carbodiimide group(s) is preferably a compound of the Formula (1):

A-N=C=N-D Formula (1) wherein:

A is a polyalkylene oxide; and D is a polyalkylene oxide or optionally substituted alkyl or aryl.

When D is an optionally substituted alkyl group it is preferably an optionally substituted C1-30-alkyl group, more preferably an optionally substituted Cl-20 alkyl group, especially an optionally substituted C,-,(, alkyl group. When D is an optionally substituted alkyl group it may be linear or branched. When D is an optionally substituted aryl group it is preferably an optionally substituted phenyl or naphthyl group.

The optional substituents which may be present on D may be substituents which are not water-dispersing substituents, water-dispersing substituents or a combination of is such substituents. Examples of substituents which are not water- dispersing include alkyl groups (especially C1.4-alkyl), nitro and amino groups. Examples of water- dispersing substituents include quaternary ammonium groups and non-ionic dispersing groups (especially polyalkylene oxide groups). Furthermore D may contain further groups, for example ether, thioether and/or -N=C=N- groups. Preferably D contains less than four, more preferably less than three -N=C=N- groups so as reduce crosslinking between the resultant polymers carrying polyethylene oxide groups. However if a dispersion of component (a) is required then D may contain four or more -N=C=N- groups.

The polyalkylene oxide groups represented by A and/or D; or present as a substituent on D, preferably contain from 5 to 100, more preferably 5 to 80 alkylene oxide units. The alkylene oxide units in each polyalkylene oxide may all be the same, for example as in polyethylene oxide, polypropylene oxide and polybutylene oxide, or they may be different, for example as in copolymers of polyethylene oxide and polypropylene oxide, polyethylene oxide containing polypropylene oxide section(s) and polypropylene oxide containing polyethylene oxide sectio n(s). The polyalkylene oxide groups include those which are terminated with any group, although the preferred terminating groups are hydroxy and alkoxy (especially Cl-4-alkoxy).

In a preferred embodiment the polyalkylene oxide carrying carbodiimide group(s) is of the Formula (2):

0 0 11 11 A-C_ N+L-N=C=N+L-N-C-D x Formula (2) SMC60365 3 wherein:

each L independently is a divalent organic linking group; x has a value of 1 to 20; and A and D are as hereinbefore defined.

The divalent organic linking group represented by L is preferably optionally substituted alkylene or arylene, more preferably optionally substituted C2-30 alkylene, or optionally substituted phenylene or napthylene. The optional substituents which may be present on L are as described above in relation to D.

To assist in the formation of a solution x is preferably 1 to 5, and more preferably x is 1 to 4, so as to avoid any crosslinking between the resultant polymers carrying polyethylene oxide groups. However if a dispersion of component (a) is required the value of x may be greater than 5.

In a preferred embodiment one or both of A and D in Formula (2) are polyalkylene oxide. Such compounds are preferably represented by Formulas (3) or (4):

0 0 11 11 R OCmH2 O-C-N L-N=C=N- L-N-C-R 2 + m+n H+ H X Formula (3) 0 0 11 11 R OCmH2m+O-C-N L-N=C=N- L-N-C O-C P H2 - OR I n 1+ n H+ H + Pn X Formula (4) wherein:

each R, independently is H or C, alkyl; R2 is H or an optionally substituted alkyl or aryl; m has a value of 2 to 4; p has a value of 2 to 4; each n independently has a value of 5 to 100; and X and each L independently are as hereinbefore defined.

Preferably each n independently has a value of 5 to 80, more preferably 5 to 60, especially 5 to 50.

When R2 is an optionally substituted alkyl, R2 is preferably aC, to C20 alkyl. The optional substituents for R2are preferably as described above in relation to the optional substituents for D. A number of processes for preparing compounds carrying carbodiimides are well known in the art. The polyethylene oxides carrying carbodiimide group(s) may be prepared by reacting an excess of a diisocyanate with a polyethylene SMC60365 4 carrying an isocyanate-reactive group(s) such as -OH, >NH, -NH2 and -SH to give a monoisocyanate carrying a polyethylene oxide group. The monoisocyanate carrying a polyethylene oxide group may then be reacted further with a diisocyanate to give a polyethylene oxide carrying a carbodiimide group and an isocyanate group, or may be reacted with a monoisocyanate to give a polyethylene oxide carrying a carbodiimide group. The polyethylene oxide carrying a carbodiimide group and an isocyanate group may optionally be reacted with more polyethylene oxide carrying an isocyanate-reactive group or other optionally substituted reactive species.

The polymer carrying carboxyl groups may carry a few or many carboxyl groups.

The polymer carrying carboxyl groups may have its hydrophilicity increased further by virtue of the presence of additional water-dispersing groups in the polymer. A polymer carrying carboxyl groups is preferably prepared by polymerising one or more monomers carrying carboxyl groups, optionally in the presence of one or more monomers which are free from water-dispersing groups and/or in the presence of one or more monomers which carry a water-dispersing group other than a carboxyl group. The nature and level of water-dispersing groups in the water-dissipatable polymer influences whether a solution, dispersion, emulsion or suspension is formed on dissipation of the polymer in aqueous media. Preferably the level of monomers having water-dispersing groups is from 1 to 100% by weight, more preferably 1 to 80% by weight of the hydrophilic polymer.

The water-dispersing groups are preferably as described above on relation to the optional substituents for D.

The anionic water-dispersing groups are preferably fully or partially in the form of a salt. Conversion to the salt form is optionally effected by neutralisation of the polymer, preferably during the preparation of the hydrophilic polymer and/or during the preparation of the composition of the present invention. If non-ionic water- dispersing groups are used in addition to the carboxyl group then neutralisation may not be required.

Preferably the base used to neutralise anionic water-dispersing groups is ammonia, an amine or an inorganic base. Suitable amines include tertiary amines, for example triethylamine or triethanolamine. Suitable inorganic bases include alkaline hydroxides and carbonates, for example lithium hydroxide, sodium hydroxide, or potassium hydroxide. A quaternary ammonium hydroxide, for example N(CH3)40H-, can also be used. Generally a base is used which gives the required counter ion desired for the composition. For example, preferred counter ions include Li", Na+, K+, NH4+ and substituted ammonium salts.

The polymer carrying carboxyl groups is preferably an acrylic or polyurethane polymer, especially a hydrophilic acrylic or hydrophilic polyurethane polymer.

When the polymer carrying carboxyl groups is an acrylic polymer it preferably has a glass transition temperature (Tg) greater than -100C. Tg is the temperature at which the SMC60365 polymer changes from a glassy, brittle state to a plastic, rubbery state, and may be measured by differential scanning calorimetry.

Preferred acrylic polymers carrying carboxyl groups have an acid value from 5 to 500mgKOH/g, more preferably from 5 to 300mgKOH/g and especially from 5 to 200mgKOH/g.

The acrylic polymer carrying carboxyl groups has preferably been obtained from the polymerisation of one or more olefinically unsaturated monomers carrying carboxyl groups, optionally in the presence of one or more olefinically unsaturated monomers which are free from water-dispersing groups and/or in the presence of one or more olefinically unsaturated monomers which carry a water-dispersing group other than a carboxyl group.

Preferred olefinically unsaturated monomers carrying carboxyl groups include but are not limited to acrylic acid, methacrylic acid, itaconic acid, [3- carboxy ethyl acrylate, maleic acid, monoalkyl itaconates (for example, monomethyl maleate, monoethyl is maleate, monobutyl maleate and monooctyl maleate) and citraconic acid. Especially preferred olefinically unsaturated monomers carrying carboxyl groups include acrylic acid, methacrylic acid, itaconic acid, P-carboxy ethyl acrylate, and / or maleic acid.

Preferred olefinically unsaturated monomers carrying ionic waterdispersing groups other than a carboxyl group include styrenes u lp honic acid, vinylbenzylsulphonic acid, vinylsulphonic acid, acryloyloxyalkyl sulphonic acids (for example, acryloyloxymethyl sulphonic acid, acryloyloxyethyl sulphonic acid, acryloyloxypropyl sulphonic acid and acryloyloxybutyl sulphonic acid), methacryloyloxymethyl sulphonic acid, methacryloyloxyethyl sulphonic acid, methacryloyloxypropyl sulphonic acid and methacryloyloxybutyl sulphonic acid), 2-acrylamido-2-alkylalkane sulphonic acids (for 2S example, 2-acrylamido-2-methylethanesulphonic acid, 2-acrylamido-2 methylpropanesul phonic acid and 2-acrylamido-2-methyl butane sulphonic acid), 2 methacrylamido-2-alkylalkane sulphonic acids (for example, 2methacrylamido-2 methylethanesulphonic acid, 2-methacrylamido-2-methylpropanesulphonic acid and 2 methacrylamido-2-methylbutanesulphonic acid), mono(acryloyloxyalkyl)phosphates (for example, mono(acryloyloxyethyl)phosphate and mono(3- acryloyloxypropyl)phosphates) and mono(methacryloyloxyalkyl)phosphates (for example, mono(methacryloyloxyethyl)phosphate and mono(3methacryloyloxypropyl)phosphate).

Preferred olefinically unsaturated monomers carrying non-ionic waterdispersing groups include alkoxy polyethylene glycol (meth)acrylates, preferably having a Mn of from 350 to 2000. Examples of such monomers which are commercially available include co-methoxypolyethylene glycol acrylate.

Preferred olefinically unsaturated monomers which are free from waterdispersing groups include alkyl(meth)acrylates, optionally substituted styrenes, methacrylarn ides, pyrrolidones, and allyl compounds.

SMC60365 6 Preferred alkyl(meth)acrylates contain less than twenty carbon atoms. Examples include rnethyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethyihexyl acrylate, octyl acrylate, tert-octyl acrylate, 2-phenoxyethyl acrylate, 2chloroethyl acrylate, 2-bromoethyl acrylate, 4-chlorobutyl acrylate, cyanoethyl acrylate, 2- acetoxyethyl acrylate, dimethylaminoethyi acrylate, benzy] acrylate, methoxybenzy] acrylate, 2-chlorocyclohexyl acrylate, acylate, acetoacetate, cyclohexyl acylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, 5-hydroxypentyl acrylate, 2,2-dimethy]-3-hydoxypropyl acrylate, 2-methoxyethyl acrylate, 3methoxybutyl acrylate, 2-ethoxyethyl acrylate, 2-iso-propoxyethyl acrylate, 2-butyoxyethyl acrylate, 2-(2-methoxyethoxy)ethyl acrylate, 2-(2-butoxyethoxy)ethyl acrylate, 1 -bromo-2-methoxyethyl acrylate, 1, 1 -dichloro-2-ethoxyethyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyi methacrylate, sec- butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate benzyimethacrylate, chlorobenzyl methacrylate, octyl methacrylate, WethylN phenylaminoethyl methacrylate, 2-(3-phenylpropyloxy)ethyl methacrylate, dimethylarninophenoxyethyl methacrylate and furfuryl methacrylate. Aromatic examples include but are not limited to 4-alkyl phenylacrylate or methacrylate, phenyl methacrylate, phenyl acrylate, and P-napthyl methacrylate, Preferred optionally substituted styrenes include styrene, methylstyrene, dimethylstyrene, trimethyistyrene, ethylstyrene, diethylstyrene, isopropyistyrene, butylstyrene, hexylstyrene, cyclohexylstyrene, decylstyrene, chloromethylstyrene, trifluoromethyistyrene, ethoxymethyistyrene, acetoxyrnethylstyrene, methoxystyrene, 4-methoxy-3-methylstyrene, dimethoxystyrene, chlorostyrene, dichlorostyrene, trichlorostyrene, tetra ch lorostyrene, pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, trifluorostyrene and 2-bromo-4-tri-fluoromethyistyrene.

Preferred methacrylamides contain less than 12 carbon atoms. Examples include methyl methacrylamide, tert-butyimethacrylamide, tert-octylmethacrylamide, benzy] methacryla mid e, cyclohexyimethacryfamide, phenyimethacrylamide, dimethyimethacrylamide, dipropyimethacrylamide, hydroxyethyi-N- methyimethacrylamide, N-methylphenyimethacrylamide, N-ethyi-N-phenyimethacrylamide and methacrylhydrazine. Optionally difunctional monomers that can be crosslinked may be used. Preferred difunctional monomers include divinylbenzene and allyl methacrylate.

Preferred allyl compounds include ally[ acetate, allyl caprylate, allyl caprylate, allyl laurate, ally[ palmitate, allyl stearate, allyl benzoate, ally] acetoacetate, allyl lactate, allyloxyethanol, allyl butyl ether and ally[ phenyl ether.

The polymerisation method used to make the acrylic polymer carrying carboxyl groups is preferably performed at a temperature of from 200C to 1801C. The SMC60365 1 1 7 polymerisation may be continued until reaction between the monomers is complete or the desired Mn has been reached.

Preferred polymerisation methods include solution polymerisation, emulsion polymerisation, suspension polymerisation and solution/dispersion polymerisation and such general methods as are well known in the art.

If desired, an initiator may be used to assist acrylic polymer formation. Suitable initiators include free-radical generators. Examples of initiators include azobis compounds, peroxides, hydroperoxides, redox catalysts, potassium persulphate, ammonium persulphate, tert-butyl peroctoate, benzoyl peroxide, isopropyl percarbonate, 2,4-dichlorobenzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, dicurnyl peroxide, azobisisobutyronitrile, azobis(2-amidino- propane)hydrochloride and the like. Typically 0.05 to 5% by weight of initiator is used relative to the total weight of the monomers. Preferably the polymerisation is performed in the presence of an emulsifying agent when the polymerisation is performed in an aqueous reaction.

is Optionally the acrylic polymer carrying carboxyl groups is prepared by a process in which the Mn is controlled by the addition of chain transfer agents andlor through the adjustment of the ratio of the concentration of monomers relative to the concentration of initiator during the course of the polymerisation. Typical chain transfer agents are thiols, halocarbons and cobalt macrocycles.

The polyurethane carrying carboxyl groups is preferably crosslinked, branched or, more preferably, linear. The Mn is preferably less than 12,500, more preferably less than 10,000 especially less than 7,500 and more especially less than 5,000.

The polyurethane carrying carboxyl groups is preferably obtained from the reaction of at least one organic polyisocyanate and at least one isocyanate-reactive compound carrying a carboxyl group, optionally in the presence of isocyanate-reactive compounds which have water-dispersing groups other than a carboxyl group andlor isocyanate-reactive compounds which are free from water-dispersing groups.

The organic polyisocyanate may be any known in the art, preferably having two isocyanate groups, and may for example be an aliphatic, cycloaliphatic, aromatic or araliphatic isocyanate. Examples of suitable organic polyisocyanates include ethylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, tetramethyixylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenyi-methane diisocyanate and its hydrogenated derivative, 2,4'-d iphenyl methane diisocyanate and its hydrogenated derivative, and 11,5-naphthylene diisocyanate. Mixtures of the polyisocyanates can be used, particularly isomeric mixtures of the toluene diisocyanates or isomeric mixtures of the diphenyimethane diisocyanates (or their hydrogenated derivatives), and also organic polyisocyanates which have been modified by the introduction of urethane, allophanate, urea, biuret, carbodiimide, uretonimine or isocyanurate residues.

SMC60365 8 Preferred organic polyisocyanates include cycloaliphatic polyisocyanates, especially isophorone diisocyanate, and aliphatic isocyanates, especially 1, 6-hexa methylene diisocyanate or hydrogenated 4,4-diphenyl methyl diisocyanate.

The isocyanate-reactive compounds preferably have at least one, more preferably two isocyanate-reactive groups. Optionally isocyanate-reactive compounds having three isocyanate-reactive groups may be present, preferably in low levels not exceeding 5% by weight relative to the total weight of the isocyanate-reactive compound. Preferred isocyanate-reactive groups are selected from -OH, -NH2, -NH- and -SH. These isocyanatereactive groups are capable of reacting with an isocyanate (- NCO) group.

Preferred isocyanate-reactive compounds carrying carboxyl groups include low molecular weight poiyols or polyamines carrying carboxyl groups, for example 2,2-dimethylol propionic acid.

Preferred isocyanate-reactive compounds carrying one or more waterdispersing group other than a carboxyl group include low molecular weight polyols or polyamines is carrying ionic andlor non-ionic water-dispersing groups other than a carboxyl group.

Preferred isocyanate-reactive compounds having anionic water-dispersing groups other than a carboxyl group are dials having one or more sulphonic acid groups, more preferably dihydroxy alkanoic acids, especially 2,2-dimethyiol propionic acid. Preferred isocyanate-reactive compounds carrying a non-ionic water-dispersing group are dials carrying one or more of the non-ionic water-dispersing groups described above as an optional substituent for D, especially polyethyleneoxide and/or polypropyleneoxide groups.

Preferred isocyanate-reactive compounds which are free from waterdispersing groups include organic polyol(s) and /or poiyamine(s). Preferred organic polyols and polyamines have an Mn up to 3000, more preferably up to 2000, especially from 400 to 2000. Preferred organic polyols are dials. The dials include members of any of the chemical classes of dials used or proposed to be used in polyurethane formulations. In particular, the dials are preferably polyesters, polyesteram ides, polyethers (other than ones providing polyethyleneoxide andlor polypropyleneoxide groups), polythioethers, polycarbonates, polyacetals, polyolefins or polysiloxanes. Further examples of optional dials which are free from water-dispersing groups include organic dials having an Mn below 400. Examples of such dials include ethylene glycol, diethylene glycol, tetraethylene glycol, bis(hydroxyethyl) terephthalate, cyclohexane dimethanol and furan dimethanol.

The polyurethane carrying carboxyl groups may be prepared in a conventional manner by reacting the components having isocyanate groups with the components having isocyanate-reactive groups. Substantially anhydrous conditions are preferred.

Temperatures of from 301'C and 1300C are preferred and the reaction is preferably SMC60365 9 continued until the reaction between the isocyanate groups and the isocyanate-reactive groups is substantially complete.

The relative amounts of the organic polyisocyanate and the isocyanatereactive compounds are preferably selected such that the mole ratio of isocyanate groups to isocyanate-reactive groups is about 2:1 to 12, preferably from about 1. 4:1 to 1:11.4.

Alternatively an isocyanate-group terminated polyurethane prepolymer may be prepared in a two stage process either in solvent or as a melt, wherein the ratio of isocyanate groups to isocyanate-reactive groups is from about 1.1:1 to 2:1, preferably from about 1.11:1 to 1.M.

Terminating compounds, for example compounds having one isocyanate group or one isocyanate-reactive group, may be used to cap-off any excess isocyanate or isocyanate-reactive end groups in the polyurethane resulting from the reaction of the organic polyisocyanate and isocyanate-reactive compound. Compounds having one isocyanate-reactive group include, for example, monoalcohols, monoamines and is monothiols, especially isopropanol. Compounds having one isocyanate group include alkyl monoisocyanates. The Mn of the polyurethane may be controlled through the use of terminating compounds. The terminating compounds may also bear ionic and/or non-ionic water-dispersing groups, for example those hereinbefore described.

If desired a catalyst may be used to assist polyurethane formation. Suitable catalysts include di-butyl tin dilaurate, stannous octoate and tertiary amines as known in the art.

The polymer carrying carboxyl groups is preferably reacted with polyalkylene oxide carrying carbodiimide groups in a solvent. The solvent may be organic, aqueous or comprise a mixture of water and organic solvents. The organic solvent may be water miscible or immiscible. Preferably the reaction is performed in an aqueous solvent. The reaction is preferably performed at a temperature of 100C to 800C, more preferably at a temperature of 1 OOC to 600C.

It is not important for every carboxyl group carried by the polymer to react with polyalkylene oxide carrying carbodiimides group(s). Preferably the reaction is such that at least 1 % preferably at least 3% and more preferably at least 5% of the carboxyl groups carried by the polymer are reacted with polyalkylene oxide carrying carbodiimide group(s).

Component (a) optionally comprises a mixture of polymers obtainable from the reaction of a polymer carrying carboxyl groups with a polyalkylene oxide carrying carbodiimide group(s). For example the polymer carrying carboxyl groups may be a mixture of polymers carrying carboxyl groups (e.g. a mixture of polyurethane carrying carboxyl groups and acrylic polymers carrying carboxyl groups) andlor the polyalkylene oxide carrying carbodUmide group(s) may also be a mixture, as described above for A in Formula 1.

SMC60365 An advantage of using component (a) rather than a blend of polymer carrying carboxyl groups with a polyalkylene oxide is that this helps to reduce the viscosity of the composition, making it more suitable for ink jet printing where low viscosities are required.

Component (a) may be purified if desired in an analogous method to the method used for purifying colorants used in ink jet printing inks, for example by ion-exchange, filtration, reverse osmosis, dialysis, ultra-filtration or a combination thereof. In this way one may remove co-solvents used for the polymerisation, low molecular weight salts, impurities and free monomers.

The colorant may be a single component colorant or multi-component colorant, for example it may be a mixture of different dyes. By using a mixture of different dyes as the colorant one may achieve greater flexibility in colour of the inks.

Useful classes of colorants include anthraquinones, phthalocyanines, pyrrolines, triphenodioxazines, methines, benzoldifuranones, coumarins, indoanilines, benzenoids, xanthenes, phenazines, solvent soluble sulphur dyes, quinophthalones, pyridones, is aminopyrazoles, pyrollidines, styrylics and azoics. Examples of preferred azoics are monoazo, disazo and trisazo disperse dyes each, of which are optionally metallised and solvent soluble dyes; especially preferred azoics contain heterocyclic groups. The Colour Index International lists suitable disperse and solvent soluble dyes, examples of which include Solvent Blue 63, Disperse Blue 24, Solvent Black 3, Solvent Black 35 and Disperse Red 60.

Further examples of disperse dyes are given in the Colour Index, 3d Edition, Volume 2, pages 2483 to 2741 and further examples of solvent soluble dyes are given in Volume 3, pages 3566 to 3647 and each of these dyes is included herein by reference.

In an alternative embodiment the colorant is a pigment, preferably a water insoluble pigment, more preferably an inorganic or organic pigment. Preferred inorganic pigments include carbon black, titanium dioxide, zinc oxide, zirconium oxide, chromium oxide, iron oxide and combinations thereof.

Preferred organic pigments include phthalocyanine, anthraquinone, perinone, indigoid, perylene, azo, carbon black pigments carrying ionic groups, azomethine, condensed ring pigments and pigments as mentioned in the Colour Index International, Third Edition (1982) Pigments and Solvent dyes, pages 10 to 143, which are incorporated herein by reference thereto. Preferred organic pigments are yellows, reds, oranges, violets, blue and 1 or black.

The carbon black pigment optionally carries ionic groups, for example anionic and/or cationic groups. The anionic group preferably comprises a carboxylic, sulphonic or phosphonic acid group. The cationic group preferably comprises a quaternary ammonium group. Carbon black pigments carrying ionic groups are commercially available from a number of sources, including Mitsubishi and Cabot Corporation for example the Cabojet,' range of carbon black pigments. Particularly preferred is carbon black pigment having a SMC60365 11 mean particle size of from 5 to 100 nm, more preferably of from 10 to 30 nm. The carbon black pigment preferably has a pH of from 3 to 9.

The pigment used in the composition of the present invention is optionally mixture comprising of two or more pigments. Pigments are present in any effective amount in the composition, typically from about 1 to about 10percent by weight of the composition.

The liquid medium (component (c)) preferably comprises water and an organic solvent. The organic solvent preferably comprises a water-miscible organic solvent and/ or a water-immiscible organic solvent.

Suitable water-miscible organic solvents include methanol, ethanol, npropanol, isopropanol, n-butanol, sec-butanol, tert-butanol, isobutanol, dimethylformamide, dimethylacetamide, acetone, diacetone alcohol, tetrahydrofuran, dioxane, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, diethylene glycol, thiodiglycol, polyethylene glycol, polypropylene glycol, glycerol, 1,2,6-hexanetriol, 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, is 2-(2-butoxyethoxy)ethanol, 3-butoxypropan-l-ol, 2-[2-(2-methoxyethoxy)- ethoxy]ethanol, 2-[2-(2-ethoxyethoxy)ethoxy]-ethanol, optionally substituted pyrrolidones, sulpholane and mixtures containing two or more of the aforementioned water-miscible organic solvents.

Preferred water-miscible organic solvents are tetrahydrofuran, dioxane, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, optionally substituted pyrrolidones, and sulpholane.

Suitable water-immiscible organic solvents include toluene, xylene, naphthalene, tetra hyd ronap htha lene, methyl naphthalene, chlorobenzene, fluorobenzene, chloronaphthalene, bromonaphthalene, butyl acetate, ethyl acetate, methyl benzoate, ethyl benzoate, benzyl benzoate, butyl benzoate, phenylethyl acetate, butyl lactate, benzyl lactate, diethyleneglycol dipropionate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di (2-ethy[hexyl) phthalate, hexanol, octanol, benzy] alcohol, phenyl ethanol, phenoxy ethanol, phenoxy propanol, phenoxy butanol, anisole, phenetole, nitrocellulose, cellulose ether, cellulose acetate, low odour petroleum distillates, turpentine, white spirits, naphtha, isopropylbiphenyl, terpene, vegetable oil, mineral oil, essential oil, natural oil, CCC12 substituted pyrrolidones and mixtures of any two or more thereof. Benzyl alcohol is especially preferred.

When a mixture of water-miscible organic solvent and a water-immiscible organic is used the weight ratio of water-miscible organic solvent to water- immiscible organic solvent in the composition is preferably 19:1 to 1A, more preferably 8:1 to 1:11, especially 5:1 to 1A.

The composition according to the present invention may be prepared by combining components (a), (b), (c) and any additional components in any order. Suitable techniques are well known in the art, for example agitation, grinding, milling, ultrasonication or stirring of all the components. Preferably the composition is prepared SMC60365 12 by mixing components (a) and (c) and optionally further components until the composition is homogenous. The mixture may then be added slowly with stirring to component (b) before adjusting the pH by addition of a base. Components (a), (b) and (c) are preferably combined together under conditions which retain stability and avoid flocculation. The preferred pH range of the composition is of from 7 to 11, more preferably of from 9 to 10.

Preferably the composition comprises:

(i) from 0.1 to 30 parts, more preferably 0.5 to 20 parts, especially 2 to 4 parts of component (a); (ii) from 0. 1 to 15 parts, more preferably 2 to 10 parts, especially 4 to 8 parts 10 of component (b); and (iii) from 75 to 98 parts, more preferably 75 to 90 parts, especially 80 to 90 parts of component (c); wherein all the parts are by weight and the parts by weight of (i) + (ii) + (iii) add up to 100.

The composition optionally comprises an additional polymer(s) (component (d)) which may be incorporated in a number of ways. For example, component (a) and component (d) can be prepared separately, followed by combination by simple blending.

Alternatively, component (d) can be prepared by aqueous polymerisation in the presence of component (a), or component (a) can be prepared by in-situ polymerisation in component (d), which may be prepared by emulsion polymerisation. For example when component (d) is a hydrophobic acrylic polymer, the hydrophobic acrylic polymer may be prepared by aqueous polymerisation, using component (a) as a polymeric surfactant or dispersant. Optionally additional surfactant may be used to aid dispersion. Preferably the aqueous polymerisation is carried out at a pH above 7.

Alternatively when component (d) is a hydrophobic acrylic polymer it may be prepared by emulsion polymerisation at a low pH followed by in-situ preparation of an acrylic polymer carrying carboxyl functional groups at a low pH, with subsequent neutralisation with a base to pH 7 and reaction with a polyalkylene oxide carrying carbodiimide groups to give component (a). The composition optionally contains a biocide, for example Proxel GXL (Proxel is a trade mark of Avecia Limited) or KathonTm (Kathon is a trade mark of Rohm and Haas), a fungicide, a rheological agent, e.g. a wax (e.g. beeswax), a clay (e.g. bentonite), an IR absorber, or a fluorescent brightener, for example C.I.Fluorescent Brightener 179 and/or UV absorber, for example hydroxy phenylbenzotriazole. Furthermore the compositions optionally contain a surface active agent, wetting agent andlor an emulsifier, for example those described in McCutcheon's Emulsifiers and Detergents 1996 International Edition or in Surfactants Europa 3' Edition 1996 each of which is incorporated herein by reference.

Preferably the composition is an ink, more preferably an ink suitable for use in an ink jet printer.

SMC60365 13 The viscosity of the composition is preferably less than 100cp, more preferably less than 50cp, especially less than 20cp and more especially less than 15cp, at 200C.

Preferably the composition has been filtered through a filter having a mean pore size below 10 Itm, preferably below 5 prn, more preferably below 2 gm, especially below 0.45 Itm. In this way particulate matter is removed which could otherwise block fine nozzles in an ink-jet printer.

The compositions according the invention have the advantage that they are suitable not only for the use in piezoelectric ink jet printers but also in thermal and continuous ink jet printers. Such compositions form discrete droplets on the substrate with little tendency for diffusing. Consequently sharp images with excellent print quality and little if any bleed between colours printed side by side Gan be obtained. Furthermore the compositions show good storage stability, wet and light fastness and fastness to both acidic and alkaline highlighter pens.

A third aspect of the invention provides a process for printing an image on a substrate comprising applying thereto a composition according to the invention 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 nozzle 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 compositions in a reservoir by means of a resistor adjacent to the nozzle, thereby causing the compositions to be ejected in the form of small droplets directed towards the substrate during relative movement between the substrate and the nozzle. In piezoelectric ink-jet printers the oscillation of a small crystal causes ejection of the compositions from the nozzle.

The substrate is preferably a paper, plastic, or textile material, more preferably a paper, an overhead projector slide or a textile material, especially paper.

Preferred papers are plain, coated or treated papers which may have an acid, alkaline or neutral character. Most preferably the substrate is a coated paper.

According to a further feature of the invention there is provided an inkjet printer cartridge comprising a chamber and a composition, wherein the composition is present in the chamber and the composition is as hereinbefore defined. Preferably the cartridge is refillable.

The invention will now be described by example only. All parts and percentages are by weight unless specified otherwise.

Preparation of Ac[ylic Polymer 1 car[ying carboL(yl grougs = (AP 1) AP 1 comprising MAA/MMAIBA (10/69.5/20.5) was prepared with components as listed in Table 1 below.

SMC60365 14 Table 1

Materials Weight (9) De-ionised Water 436.5 monomer shot Methyl methacrylate 25.9 Butyl acrylate 7.6 3 Mercaptoproprionic acid 1.1 monomer feed Methaerylic acid (MAA) 37.4 Methyl methaerylate (MMA) 233.7 Butyl acryiate (BA) 68.8 3-Mercaptoproprionic acid 10.0 initiator shot Ammonium persulphate 0.75 De-ionised water 24.1 Sodium lauryl sulphate 1.1 initiator feed Ammonium persulphate 3.0 De-ionised water 96.4 Sodium lauryl sulphate 4.5 burn-up Ascorbic acid 2.2 co-initiator De-ionised water 42.6 burn-up t-Butyl hydrogen peroxide (70% solids) 3.2 initiator De-ionised water 41.6 odourreducer Hydrogen peroxide solution (30% solids) 2.5 De-ionised water to take up to 30% 2.5 solids neutralisatign Ammonia solution 20% 36.9 Water was added to a reactor and heated to 800C with continuous stirring. The S reactor was purged with N2- The monomer shot was added to the reactor and stirred for 5 minutes. The initiator shot was added to seed the reaction and stirred for 15 minutes. Monomer and initiator feeds were then added over 90 minutes whilst maintaining the temperature at 80 8311C for a further hour.

Subsequently the emulsion was cooled to 500C to commence burn-up by adding the burn-up co-initiator dropwise over 30 minutes. The burn-up initiator was added in 3 equal shots at 1, 10 and 20 minutes after addition of the burn-up co- initiator.

The mixture was stirred for 30 minutes before adding the odour reducer dropwise over 10 minutes. De-ionised water was added to take the emulsion to 30% solids w/w and the temperature increased to 600C.

SMC60365 The emulsion was then neutralised with ammonia solution and stirred until the solution had gone clear. The resultant carboxyi-functionalised polymer was cooled and filtered through a 50gm mesh.

Analysis The resultantacrylic polymer carrying carboxyl groups solution (AP 1) had a pH of 7.0, a weight average molecular weight of 12,400 and an Mn of 5,800.

The Tg average was 770C and the average particle size was 35.5 nm.

Preparation of a mixture comprising Acrylic Polymer 1 carEying carboh(yi groups and polystyrene [component (dfl = (AP 1/ST) Preparation of polystyrene was carried out by emulsion polymerisation in the presence of the Acrylic Polymer 1 carrying carboxyl groups with components as listed below in Table 2.

is Table 2 f Materials 1 Weight (9) initial cbaL AP 1 386.7 qe De-ionised water 379.8 Ammonia solution 35% 10.0 emulsified feed Styrene 217.7 De-ionised water 108.9 Ammonium persulphate 1.1 Sodium lauryl sulphate 1.1 De-ionised water for rinse 18.75 The initial charge was added to a reactor with enough ammonia solution to ensure that the pH of the initial charge was greater than 8.5, and heated to 80- 850C with continuous stirring under nitrogen.

10% of the emulsified feed was added to the reactor from a dropping funnel and left to nucleate for about 5 minutes. After nucleation the remainder of the emulsified feed was added over an hour while the temperature of 85 20C was maintained. Once all the feed was added the dropping funnel was rinsed with de-ionised water which was subsequently added to the reactor. The reaction was left for a further 30 minutes at 850C before cooling the resultant composition to room temperature and filtering the composition through a 50gm mesh.

SMC60365 16 The pH of the resultant composition was 9.3, the particle size was 38 rim The resultant composition comprised the acrylic polymer carrying carboxyl groups (AP 1) of Mn 5,800 and polystyrene of Mn greater than 40,000, in a weight ratio of approximately 35:65.

Preparation of AcEyfic Polymer 2 carrying carboxyl grou12s = (AP 2) AP 2 comprising MANIVIMA (10190) was prepared with components as listed in Table 3 below:

Analysis: The resultant AP 2 had a Mn of 5735, MW of 20634 and a Tg of 89. 40C.

Table 3

Component 1 Materials F- Weight (g) 1 Methylethyl ketone (MEK) 665 2 Methyl methacrylate (MMA) 270 3 Methacrylic acid (MAA) 30 4 3-mercapto proprionic acid 9 Initiator V59 5 6 MEK 35 7 Initiator V59 1 8 MEK 35 is Components 1 to 4 were placed in a nitrogen purged flask, and stirred under nitrogen to give a homogeneous solution. The solution was then heated to 650C, a solution of component 5 in 6 was added and the mixture was stirred at 650C for four hours after which a solution of component 7 in 8 was added. Stirring was continued for a further hour before the resultant carboxyi-functionalised polymer (AP 2) was cooled and filtered through a 50 gm mesh.

Preparation of a polyethylene oxide carrying carbodiimide group(s) = (PEOCD1) To a 1-litre round bottomed flask, equipped with a condenser, overhead stirrer, thermocouple, sampling port and pressure equalised dropping funnel, was added under nitrogen; isophorone diisocyanate (124g), polyethylene glycol mono methyl ether (Mn about 750, 36.9g) and dibutyl tin dilaurate (0.06g). The mixture was stirred and heated to 5811C, and held at 55-601>C for 105 minutes, then allowed to cool overnight. 16 hours later the mixture was reheated to 1250C, and methyl phenyl phospholene oxide (1. 15g) in methoxy propyl acetate (MPA), (4.5g) was added via the pressure equalised dropping SMC60365 17 funnel, The mixture was then heated rapidly to 150.60C and maintained at 145-1500C.

The mixture was cooled to 56'C, and methoxy propyl acetate (46.13g) was added. A sample for measuring residual isocyanate was taken. (14.65g, 3.34% NCO).

Polyethylene glycol mono methyl ether (Mn about 2000, 254.8g) in methoxy propyl acetate, (109.2g) was added via the pressure equalised dropping funnel, and the mixture reheated to 800C, and held until Infra Red spectroscopy gave no evidence of isocyanate (peak absorbance at 2250 cm-' was absent).

Yield: 514.8g Solids content: 69.1 % by weight in methoxy propyl acetate (MPA).

Carbodiimide content: 0.378 meqg-I molecular weights: Mn 1100 Mw 4000 Preparation of a mixture comprising Ac[ylic Polymer 1 car[ying carboul groups and polystyrene where 1 % of the carboxyl groups are rel?laced by l2olvethylene oxide, (AP 1/ST + 1 % PEO-CDI) The AP1/ST prepared above (30% solids, 300g) was stirred at room temperature and the PEO-CDI prepared above (69.1% solids in MPA, 1.3g) was added over 5 minutes and left stirring for 2 hours, to give a product with a 1 % conversion of the carboxyl groups on the Acrylic Polymer 1 with polyethylene oxide.

Preparation of a mixture comgrisinq Ac[ylic Polymer 1 carrying carboxyl grougs and polys!yrene where 3% of the carboL(yl grouns are replaced by 12olyethylene oxide.

AP 1/ST + 3% PEO-CDI) The AP1/ST prepared above (30% solids, 300g) was stirred at room temperature and the PEO-CDI (69.1% solids in MPA, 3.9g) was added over 5 minutes and left stirring for 2 hours, to give a product with a 3% conversion of the carboxyl groups carried on the Acrylic Polymer 1 with polyethylene oxide.

SMC60365 18 Table 4

Analysis Surface Tension mN/m TgPC AP 1 / ST 42.2 46.6 and 94.9 AP 1 / ST + 1 % PEO-CID1 42.05 47.2 and 99.8 AP 11 ST + 3% PEO-CID1 42.75 47.7 and 99.7 1 Preparation of a mixture comprising AcL)Llic Polymer 2 car[yinqcarboxyl groui:)s Where 5% of the carboxyl groul2s are reglaced by polyethylene oxide, = (AP 2 + 5% PEO-CDD The Acrylic Polymer 2 prepared above (30% solids, 300 g) was stirred at room temperature and PEO-CDI prepared above (69.1% solids in MPA, 6.5g) was added over minutes and left stirring for 2 hours to give a product with a 5% conversion of the carboxyl groups on the Acrylic Polymer 2 with polyethylene oxide.

AnaIvsis The Mn of (AP 2 + 5% PEO-CDI) was 5647, the Mw was 10436 and the Tg was 81.50C.

Corngonent (d): Latexes A, B and C is Acrylic polymer latexes comprising components styrene (ST), ethyl hexylacrylate (EHA) and acrylic acid (AA), as described below in Table 5 were prepared as described for Acrylic Polymer 1 above.

Table 5

LATEX -7 A -7 B c STIEHA/AA 58.5137.514 7811814 961014 Analysis:

% solids 39.7 39.4 39.7 pH 8.9 9.3 9.6 particle size nm 85 102 101 Tg 'C 31.4 73.7 107.0 Mn 85700 86700 103700 MW 223200 266900 285800 r- SMC60365 19 Latexes A, B and C were subsequently blended with (AP 2) and (AP 2 + 5% PEO-CID1) respectively, and adjusted with de-ionised water to 25% by weight solids and with aqueous ammonia to a pH of approximately 9.4 to 9. 5 in ratios as shown in Table 6 below.

Table 6

Blen B Blend D Blend F Blend A Blend C Blend E AP2 25 15 25 - - - AP2 + 5% CD1 - - - 25 15 25 LATEX A 75 - 75 - - LATEX B - 85 - - 85 - LATEX C - _5 Preparation of Aqueous Compositions: Examples 1 to 5 and Comparative Examples CE 1 to 5 Components 1 to 14 as listed in Table 7 below were mixed until homogenous. The respective mixtures were added slowly with stirring to CabojetTm 300 millbase at 15.3 w/w % solids in water.

The resultant compositions were adjusted to approximately pH 9.5 using 35% ammonia solution, and subsequently filtered through a 1Ogm mesh.

4 SMC60365 Table 7

Evaluation of Examples 1 to 5 and Comparative Examples 1 to 4 The inks prepared in Examples 1 to 5 and comparative Examples 1 to 4 were fired from an Epson 600 thermal ink-jet printer onto Conqueror High White Wove 1 OOg/M2 plain paper from Arjo Wiggins Ltd.

The control was an ink comprising a polymer free formulation. Prints were evaluated for highlighter smear and wet rubfastness. Inks were evaluated for stability.

The evaluation test results are shown below in Table 8 and Table 9.

Highlighter smear This is a test performed 5 minutes after printing.

A yellow highlighter pen was used to draw a horizontal line across a series of printed vertical bars. The amount of ink smear between the vertical bars was assessed visually against controls.

1 Examples Comparative Examples 1 1 2 1 3 1 4 1 5 1 1 2 1 3 4 1. Diethylene Glycol 10 10 10 10 10 10 2. U rea 5 5 5 5 5 5 3. Butyl digol 2 2 2 2 2 2 4. Surfynol 465 0.1 0.1 0.1 0.1 0.1 0.1 5. De-ionised water 49.6 49.6 49.6 49.6 49.6 49.6 6. AP 1/ST - - 33.1 - - - 7. AP 1 /ST 33.1 - + 1% PEO-CID1 8. AP 1/ST - 33.1 - + 3% PEO-CID1 9. Blend A - - 33.1 10. Blend B - - 33.1 11. Blend C 33.1 12. Blend D 33.1 - 13. Blend E 33.1 - 14. Blend F - 33.1 21 Wet rubfastness This is a test performed 5 minutes after printing.

A finger was wetted and rubbed on the corner of a printed solid black block. The amount of ink transferred to white paper is assessed visually against controls.

Ink Stability The inks and the control were stored in an incubator at a range of temperatures for one week. The temperature cycle was a 24 hour cycle (-1 011C to 250C).

The stability was evaluated by optical microscopy and the stability was ranked as follows:

Rank Description

No change, good mobile dispersion 4 Good, a few 1 micron particles present, still mobile 3 An increase in the amount of particles greater than 1 micron 2 Large (greater than 2 micron) flocculates present, ink less mobile 1 Flocculated, immobile, unstable Ogtical Density The optical density is a measure of the colour strength of a printed image and is expressed as a number without units. The higher the value, the stronger the print is.

Optical density is measured using an X-Rite 938 Spectrodensitomer.

Table 8 Evaluation Test Results Ink Stability data Printed Ink Performance Polymer Wet rub Room 60% 7M Temperature fastness Highlighter Temperature Cycle 5_min Smear Control No polymers -- -- -- -- Smeared Smeared Comparative AP 1 IST 5 5 2 5 very little no smear 100% Example 1 smear Example 1 AP 1 /ST 5 5 415 5 very little no smear 100% + 1% PEO-CID1 smear AP1 1 ST Example 2 + 3% PEO-CID1 5 5 5 5 very little no smear 100% smear Key. not measured.

_v Table 9 Evaluation Test Results Ink Stability data Printed Ink Performance Optical Density Polymer 700C Wet rub Highlighter dots per dots per fastness Smear 360 1440 min inch inch Example 3 Blend A 3 very little smear I no smear 100% 1.01 1.42 Comparative Blend B not stable Did not print well -- - Example 2

Example 4 Blend C 5 very little smear I no smear 100% 1.23 1.71 Comparative Blend D 4 Did not print well -- - Example 3

Example 5 Blend E 4 very little smear I no smear 100% 1.21 1.53 Comparative Blend F 2 Did not print well -- - Example 4

N) W Key: -- =not measurable SMC60365 24 1 A composition comprising the components:

(a) a water-dissipatable polymer; (b) colorant; and (c) liquid medium; wherein the water-dissipatable polymer is obtainable from the reaction of a polymer carrying carboxyl groups with polyalkylene oxide carrying carbodiimide group(s).

2. A composition according to claim 1 wherein component (a) has a Mn less than 1,000,000.

3. A composition according to claim 1 wherein component (a) is a waterdissipatable acrylic or a water-dissipatable polyurethane polymer.

is 4. A composition according to any one of the preceding claims wherein the composition additionally comprises component (d) where component (d) is a hydrophobic polymer.

5. A composition according to any one of the preceding claims having a viscosity less than 1 00cp at 20 OC.

6. A composition according to any one of the preceding claims which comprises:

(i) from 0.1 to 30 parts of component (a); (ii) from 0.1 to 15 parts of component (b); and (iii) from 75 to 98 parts of component (c) wherein ail the parts are by weight and the parts by weight of (i) + (ii) + (iii) add up to 100.

7. A composition according to any one of the preceding claims wherein the colorant comprises a dye or a pigment.

8. An ink comprising a composition according to any one of the preceding claims.

9. Use of a composition according to claims 1 to 7 as an ink for ink-jet printing.

10. A process for printing an image on a substrate comprising applying thereto a composition according to any one of claims 1 to 7 by means of an ink-jet printer.

SMC60365 11. An ink-jet printer cartridge comprising a chamber and a composition, wherein the composition is present in the chamber and the composition is as defined in any one of claims 1 to 7.