WO2003052000A1

WO2003052000A1 - Method for producing fine-particle azo colorant preparations for ink jet printing

Info

Publication number: WO2003052000A1
Application number: PCT/EP2002/012599
Authority: WO
Inventors: Martin Alexander Winter; Hans Joachim Metz; Franz Schui
Original assignee: Clariant Gmbh
Priority date: 2001-12-14
Filing date: 2002-11-12
Publication date: 2003-06-26
Also published as: DE10161609A1

Abstract

The invention relates to a method for producing fine-particle dispersions consisting of water-insoluble to slightly soluble azo colorants. The invention is characterized in that a diazonium salt, which is capable of coupling, is coupled to a coupling constituent in the presence of at least 45 wt. %, with regard to the theoretically expected quantity of colorants, of a surface-active agent.

Description

description

Process for the production of finely divided azo colorant preparations for ink-jet printing

The present invention relates to a process for the production of particularly fine-particle azo colorant dispersions which can be processed into inkjet inks without additional grinding processes.

To date, inks are used for thermal and piezoelectric ink-jet printing, which are based on solutions of water-soluble dyes, which is why the prints have high brilliance and optical density, but have insufficient light fastness and poor water resistance. The mentioned disadvantages of dye-based ink jet inks can only be partially overcome with the help of special papers. One way to overcome these drawbacks is to use pigmented inks.

A number of requirements are imposed on pigmented inks for inkjet printing: they must have a suitable viscosity and surface tension for printing, they must be stable in storage, i.e. they should not coagulate and the dispersed pigment should not settle, they should not clog the printing nozzles, which can be particularly problematic with the inks containing pigment particles, and they should be environmentally friendly, i.e. are largely based on water and contain the lowest possible concentrations of organic solvents. High demands are also placed on the purity of the preparations, since excessive concentrations of inorganic or organic salts and ions, in particular chloride ions, cause corrosion and thus premature destruction of the print heads or, in the case of bubble jet printers, harmful deposits on the heating elements to lead.

The fine division of the pigment preparations is a basic requirement for them Use in ink jet printing, because in order not to clog the nozzles, the average particle size of the pigment particles should not exceed 200 nm and the particle size distribution should be very narrow, so that the maximum particle size does not exceed 500 nm. In addition to the fine particle size, the flocculation resistance is particularly important

Quality criterion of an ink jet preparation, which is why suitable additives must effectively prevent crystal growth or agglomeration of the pigment particles. This is usually done using certain dispersing agents. The storage stability of the pigment dispersions is closely related to the flocculation resistance, because the pigment particles must not agglomerate during prolonged storage, even at temperatures which are increased or decreased relative to room temperature.

The conventional production of pigmented preparations for ink-jet printing is characterized in that at least one colorant, either as a powder or as a press cake, together with at least one dispersing aid, optionally with at least one organic solvent and optionally with other customary additives in preferably deionized water pasted and then homogenized and predispersed with a dissolver or other suitable apparatus. If necessary, fine dispersion is then carried out using a bead mill or another suitable dispersing unit, fine dispersion and grinding to the desired particle size distribution. Following the fine dispersion, the dispersion is diluted to the desired colorant concentration with deionized water.

Overall, this type of preparation is very complex because it comprises the steps of synthesis, finish, filtration, drying and grinding. All of these process steps are very labor-intensive and involve a high expenditure of energy. It would therefore be very advantageous if the synthesis of the colorants could be carried out in such a way that a sufficiently fine-particle colorant dispersion is formed directly. EP 0 136 619 A2 describes a process for the preparation of azo dye dispersions which is based on the fact that simultaneous diazotization and coupling is carried out with thorough mixing of the corresponding reactant suspension in the presence of 0.2 to 30% by weight of a surface-active agent. This method directly produces dye dispersions, which are worked up by means of a membrane separation process and further processed without grinding directly into a liquid formulation or a pasty or solid colorant preparation. The cited patent describes primarily the synthesis of those azo dyes which belong to the group of disperse dyes and are suitable for dyeing and printing hydrophobic fiber materials. The use of the dispersions for ink-jet printing is not described and is also not possible since the particle sizes of about 2 μm which are formed are too large for ink-jet inks. However, the fine particle size (maximum particle sizes of the colorant particles smaller than 500 nm) of the colorant preparations is a basic requirement for them

Use in ink-jet printing, otherwise the nozzles would clog up immediately.

Another disadvantage of the process described in EP-0 136 619 is the preparation of the azo colorants described by simultaneous diazotization and coupling in one reaction vessel. With this approach, the reaction between the coupler and the diazonium compound is uncontrolled, which prevents the production of high quality azo pigments.

For the process described, intensive mixing of the reactants during the synthesis is also essential to the invention using stirrers with strong shear action, if appropriate with the aid of flow breakers in the reaction vessel. However, this can lead to technical problems due to the strong foam formation.

It was therefore the task of avoiding the disadvantages mentioned above to carry out the synthesis of azo colorants in such a way that a aqueous, stable and finely divided azo dye preparation is created, which is particularly suitable for applications in ink-jet printing. In this way, the time-consuming and labor-intensive process steps involved in the conventional manufacture of preparations for ink-jet applications, such as drying and wet grinding of the colorants, can be dispensed with.

Surprisingly, the task could be solved by the following procedure.

The invention relates to a process for the production of finely divided dispersions of insoluble to poorly soluble azo colorants, characterized in that a diazonium salt capable of coupling with a coupling component in the presence of at least 45% by weight, based on the theoretically expected amount of colorant, of a surface-active agent , couples.

The colorant dispersions of the invention are extremely finely divided, the maximum particle sizes that are below 500 nm, 300 nm usually below, more preferably below 200 nm, where d ₅ o values are achieved nm 100th They are therefore suitable for the production of ink-jet inks without any further distribution processes. They are stable in storage over longer periods, even at elevated temperatures, and show no flocculation. A very high purity can be achieved by membrane filtration downstream of the synthesis, so that the content of inorganic salts and in particular the content of halides is very low. A low concentration of halide ions, especially chloride ions, reduces the corrosion of the ink jet printheads.

The insoluble to poorly soluble azo colorants are primarily azo pigments and azo disperse dyes. The azo pigments are monoazo, disazo, β-naphthol, naphtol AS,

Acetoacetylamino-benzimidazolone, acetoacetylamino-quinazolinedione and acetoacetylamino-quinoxalinedione pigments in question. Diazonium salts of aromatic or heteroaromatic amines are used as reactants for the azo coupling reaction, such as, for example, aniline, 2-nitroaniline, methyl anthranilate, 2,5-dichloro-aniline, 2-methyl-4-chloroaniline, 2-trifluoromethyl-4-chloroaniline, 2, 4.5-Trichloroanilin; 3-amino-4-methylbenzamide, 4-amino-3-chloro-N'-methylbenzamide, o-toluidine, o-dianisidine, 2,2 ', 5,5'-tetrachlorobenzidine, 2-amino-5-methyl -benzenesulfonic acid and 2-amino-4-chloro-5-methyl-benzenesulfonic acid.

The following amine components are of particular interest for azo pigments: 4-methyl-2-nitro-phenylamine, 4-chloro-2-nitro-phenylamine, 3,3-dichlorobiphenyl-4,4'-diamine, 3,3-dimethyl- biphenyl-4,4'-diamine, 4-methoxy-2-nitro-phenylamine, 2-methoxy-4-nitro-phenylamine, 4-amino-2,5-dimethoxy-N-phenylbenzenesulfonamide, 5-amino-isophthalic acid dimethyl ester , Anthranilic acid, 2-trifluoromethyl-phenylamine, 2-amino-terephthalic acid, dimethyl ester, 1, 2-bis- (2-amino-phenoxy) -ethane, 2-amino-4-chloro-5-methyl-benzenesulfonic acid, 2-methoxyphenylamine, 4 - (4-Amino-benzoylamino) benzamide, 2,4-dinitro-phenylamine, 3-amino-4-chloro-benzamide, 4-nitrophenylamine, 2,5-dichlorophenylamine, 4-methyl-2-nitro-phenylamine , 2-chloro-4-nitro-phenylamine, 2-methyl-5-nitro-phenylamine, 2-methyl-4-nitro-phenylamine, 2-methyl-5-nitro-phenylamine, 2-amino-4-chloro-5 -methyl-benzenesulfonic acid, 2-amino-naphthalene-1-sulfonic acid, 2-amino-5-chloro-4-methyl-benzenesulfonic acid, 2-amino-5-chloro-4-methyl-benzenesulfonic acid, 2-amino-5 -methyl-benzenesulfonic acid, 2,4,5-trichlorophenylamine, 3-amino-4-methoxy-N-phenyl-benzamide, 4-amino-benzamide, 2-amino-benzoic acid methyl ester, 4-amino-5-methoxy -2, N-dimethylbenzenesulfonamide, 2-amino-N- (2,5-dichloro-phenyl) terephthalic acid monomethyl ester, 2-amino-benzoic acid butyl ester, 2-chloro-5-trifluoromethyl-phenylamine, 4- (3-amino -4-methyl-benzoylamino) -benzenesulfonic acid, 4-amino-2,5-dichloro-N-methyl-benzenesulfonamide, 4-amino-2,5-dichloro-N, N-dimethyl-benzenesulfonamide, 6-amino-1H- quinazolin-2,4-dione, 4- (3-amino-4-methoxy-benzoylamino) benzamide and 4-amino-2,5-dimethoxy-N-methyl-benzenesulfonamide. The following coupling components are of particular interest for azo pigments: acetoacetic arylides of the general formula (I),

in which n is a number from 0 to 3, and R ^{1 is} a CrC ₄ alkyl group, such as methyl or ethyl; a CrC alkoxy group such as methoxy or ethoxy; a trifluoromethyl group; a nitro group; a halogen atom such as fluorine, chlorine or bromine; an NHCOCH ₃ group; a S0 ₃ H group; a SO ₂ NR ¹⁰ R ¹¹ group in which R ¹⁰ and R ^{11 are} identical or different and denote hydrogen or dC -alkyl; a COOR ¹⁰ group in which R ^{10 has} the meaning given above; or can be a C00NR ¹² R ¹³ group in which R ¹² and R ¹³ independently of one another represent hydrogen, C 1 -C ₄ -alkyl or phenyl, the phenyl ring being substituted by two or three identical or different substituents from the group C 1 - C ₄ alkyl, -CC ₄ -A! Koxy, trifluoromethyl, nitro, halogen, COOR ¹⁰ , where R ^{10 has} the meaning given above, COONR ¹⁰ R ¹¹ , where R ¹⁰ and R ^{11 are the} same or different and the above have the abovementioned meaning, can be substituted, where n> 1 R can be identical or different;

2-hydroxynaphthalenes of the general formula (II),

in which

X represents hydrogen, a COOH group or a group of the general formula (III),

in which n and R ^{1 are} as defined above;

bisacetoacetylated diaminophenyls and biphenyls, the phenyl or biphenyl ring being unsubstituted or having 1, 2, 3 or 4 identical or different radicals CH ₃ , C ₂ H ₅ , OCH ₃ , OC ₂ H ₅ , NO ₂ , F, Cl, CF. ₃ can be substituted;

Acetoacetic acid arylides of dinuclear heterocycles of the general formula (IV),

in which n and R ^{1 are} as defined above,

Q ¹ , Q ² and Q ^{3 can be the} same or different and N, NR ² , CO, N-CO,

NR ² -CO, CO-N, CO-NR ² , CH, N-CH, NR ² -CH, CH-N, CH-NR ² , CH ₂ , N-CH ₂ , NR ² -CH _2> CH ₂ -N, CH ₂ -NR ² or S0 ₂ , mean, wherein

R ^{2 represents} a hydrogen atom; for a -CC ₄ alkyl group, such as methyl or ethyl; or represents a phenyl group which is unsubstituted or by halogen,

C 1 -C ₄ alkyl, CrC ₄ alkoxy, trifluoromethyl, nitro, cyano can be substituted one or more times, with the proviso that the combination of Q ¹ , Q ² and Q ³ with the two carbon atoms of the phenyl ring is a saturated or unsaturated one , five or six-membered ring results;

and pyrazolones of the general formula (V)

in which

R ^{3 is} a group CH ₃ , C00CH ₃ or COOC ₂ H _5! R ^{4 is} a group CH ₃ , S0 ₃ H or a chlorine atom, and p is a number from 0 to 3, where p> 1 R ^{4 may be the} same or different.

Monoazo, disazo, isoindoline and benzimidazolone pigments are selected as particularly preferred azo pigments, in particular the color index pigments Pigment Yellow 17, Pigment Yellow 74, Pigment Yellow 83, Pigment Yellow 97, Pigment Yellow 120, Pigment Yellow 128, Pigment Yellow 151 , Pigment Yellow 155, Pigment Yellow 180, Pigment Yellow 213, Pigment Red 57: 1, Pigment Red 146, Pigment Red 176, Pigment Red 184, Pigment Red 185 or Pigment Red 269, but without the invention only for these pigments restrict.

In order to achieve the success according to the invention, the surface-active agent is used in an amount of at least 45% by weight, preferably at least 50% by weight, in particular at least 60% by weight, particularly preferably at least 75% by weight, based on the Azo colorants used. In principle, there are no technical limits on the maximum amount, but 500% by weight, preferably 400% by weight, in particular 300% by weight, particularly preferably 200% by weight, based on the azo colorant, are expedient and economically sensible.

Anionic, cationic, nonionic and amphoteric surface-active compounds are suitable as surface-active agents. Examples of nonionic surfactants are alkyl or aryl alkoxylates, such as, for example, alkoxylates of castor oil rosin esters, fatty alcohols, fatty amines, fatty acids or fatty acid amides and alkoxylation products of alkylphenols or their oligomeric or polymeric derivatives, for example aldehyde condensation products. Alkoxylates of styrene-phenol addition products such as 2,4,6-tris (1-phenylethyl) phenol and of diglycerol and polyglycerol esters of long-chain acids are also possible. Amphiphilic polymers or copolymers can also be used as dispersants, for example block-polymethacrylic acid ester block-polyethylene oxide copolymers, block-polystyrene-block-polyethylene oxide copolymers, block-polyethylene oxide-block-polypropylene oxide copolymers, block-polyethylene-diamine-block-polyethylene oxide - Block polypropylene oxide copolymers, polyvinylpyrrolidones or polyvinyl alcohols.

Anionic and cationic surfactants are suitable as ionic surface-active compounds. Examples are surfactants which can be obtained by chemical modification of the nonionic surfactants, for example compounds with the groups -0-S0 ₃ H, -S0 ₃ H, -COOH, -0-PO (OH) ₂ , -0-PO (OH) -0-, -0-CO-CH = CH-COOH, -0-COCH (S0 ₃ H) CH ₂ COOH, -COCH ₂ CH (S0 ₃ H) COOH. These surfactants are expediently used in the form of the alkali metal salts, ammonium salts and / or the water-soluble amine salts. In addition, sulfonates of alpha-olefins, sulfonates of polynaphthalenes, lignin sulfonates, dialkyl sulfosuccinates and sulfated fatty acids or oils and their salts can also be used.

In addition, cationic surfactants from the group of the alkyl or arylammonium salts, as well as zwitterionic surfactants or mesoionic surfactants, such as e.g. Amine oxides.

According to the invention, it is also preferred to use polymeric surface-active compounds, for example acrylate resin copolymers with an average molecular weight M _v between 1000 and 50,000 g / mol, consisting essentially of monoalkenyl aromatics and acrylates. Monoalkenyl aromatics are understood in particular to mean monomers from the group consisting of styrene, σ-methyl styrene, vinyl toluene, tert-butyl styrene, o-chlorostyrene and mixtures thereof.

Acrylates are monomers from the group consisting of acrylic acid, methacrylic acid and esters of acrylic or methacrylic acid. Examples are:

Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, iso-amyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, t-butylaminoethyl methacrylate, 2-sulfoethyl methacrylate, trifluoroethyl methacrylate, glycidyl methacrylate, benzyl methacrylate, allyl methacrylate, 2-n-butoxyethyl methacrylate, 2-chloroethyl methacrylate, sec.-butyl methacrylate, tert.-butyl methacrylate, 2-ethylbutyl methacrylate, cinnamyl methacrylate, crotyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, Furfuryl methacrylate, hexafluoroisopropyl methacrylate, methallyl methacrylate, 3-methoxybutyl methacrylate, 2-methoxybutyl methacrylate, 2-nitro-2-methylpropyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, 2-phenoxyethyl methacrylate 2-phenylethyl methacrylate, phenyl methacrylate lat, propargyl methacrylate, tetrahydrofurfuryl methacrylate and tetrahydropyranyl methacrylate.

Acrylate resins composed of the monomers styrene and (meth) acrylic acid are particularly preferred according to the invention.

The acrylate resin is expediently used in the form of the alkali metal salts, ammonium salts or the water-soluble amine salts, preferably as a 1 to 35% by weight, in particular 5 to 30% by weight, aqueous solution.

The acrylate resins described above can be produced, for example, as described in US Pat. No. 4,529,787. The acrylate resin used according to the invention can contain small amounts, such as 0.5 to 2 mol%, of a surface-active compound capable of polymerization in the copolymer. The diazonium salts of the amines described above are used for the process according to the invention.

Alkali metal nitrites or the alkyl nitrites of short-chain alkanes, together with sufficiently strong mineral acids, are usually suitable for the diazotization reaction. Sodium nitrite and hydrochloric acid are particularly suitable. The reaction can be carried out in a temperature range from -5 ° C to 80 ° C, preferably between 5 ° C and 25 ° C. Although not necessary, non-ionic, anionic or cationic surface-active compounds can already be present during the diazotization. If necessary, other auxiliaries, such as natural or synthetic resins or resin derivatives, can also be used.

The coupling component can either be suspended or dissolved in water, in the presence of one or more of the surface-active agents described above and, if appropriate, various buffer and auxiliary substances and organic solvents customary in pigment chemistry. Preferably the coupling component is first dissolved in a base and then by adding acid, e.g. Hydrochloric acid or acetic acid, finely dispersed. The amount of surfactants according to the invention can be added to the reaction mixture before and / or after the coupling component has been precipitated.

The azo coupling reaction is preferably carried out in aqueous solution or suspension, but it is also possible to use organic solvents, if appropriate in a mixture with water, for example alcohols having 1 to 10 carbon atoms, such as, for example, methanol, ethanol, n-propanol, isopropanol, butanols, such as n-butanol, sec-butanol, tert-butanol, pentanols, such as n-pentanol, 2-methyl-2-butanol, hexanols, such as 2-methyl-2-pentanol, 3-methyl-3-pentanol, 2- Methyl-2-hexanol, 3-ethyl-3-pentanoI, octanols such as 2,4,4-trimethyl-2-pentanol, cyclohexanol; or glycols, such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, or glycerin; Polyglycols, such as polyethylene glycols or polypropylene glycols; Ethers, such as methyl isobutyl ether, tetrahydrofuran or dimethoxyethane; Glycol ethers, such as monomethyl or monoethyl ether of ethylene or propylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, butyl glycols or methoxybutanol, ketones, such as acetone, diethyl ketone, methyl isobutyl ketone, methyl ethyl ketone or cyclohexanone; aliphatic acid amides such as formamide, dimethylformamide, N-methylacetamide or N, N-dimethylacetamide; Urea derivatives such as tetramethyl urea; or cyclic carboxamides, such as N-methylpyrrolidone, valero- or caprolactam; Esters, such as C 1 -C 6 -carboxylic acid alkyl esters, such as butyl formate, ethyl acetate or propyl propionate; or carboxylic acid CrC-6 glycol ester; or glycol ether acetates, such as 1-methoxy-2-propyl acetate; or phthalic or benzoic acid -CC ₆ alkyl esters, such as ethyl benzoate; cyclic esters such as caprolactone; Nitriles such as acetonitrile or benzonitrile; aliphatic or aromatic hydrocarbons, such as cyclohexane or benzene; or benzene substituted by alkyl, alkoxy, nitro or halogen, such as toluene, xylenes, ethylbenzene, anisole, nitrobenzene, chlorobenzene, o-dichlorobenzene, 1, 2,4-trichlorobenzene or bromobenzene; or other substituted aromatics such as benzoic acid or phenol; aromatic heterocycles such as pyridine, morpholine, picoline or quinoline; and hexamethylphosphoric triamide, 1, 3-dimethyl-2-imidazolidinone, dimethyl sulfoxide and sulfolane. The solvents mentioned can also be used as mixtures. Water-miscible solvents are preferably used.

The coupling is possible by the direct or indirect procedure, but is preferably carried out directly, ie the diazonium salt is added to the coupling component. Depending on the pigment and the surface-active substances used, the coupling reaction can be carried out in a temperature range between -5 ° C and 80 ° C, preferably between 5 ° C and 25 ° C, and at a pH between pH 4 and pH 14. in particular between pH 4.5 and pH 12. In general, the coupling component, based on the amount of diazonium compound, is used in a slight excess. It is also possible to add all or part of the amount of surface-active agents according to the invention to the reaction mixture only during the coupling. A subsequent temperature treatment to temperatures of up to 100 ° C is possible to accelerate the complete coupling.

The resulting azo colorant dispersion advantageously has a colorant concentration of 0.1 to 10% by weight. Although not necessary in most cases, the dispersion can first be roughly filtered and then cleaned and desalinated to the desired degree by membrane filtration. The colorant dispersion can then be concentrated either by distilling off the water or organic solvent and / or by membrane filtration, e.g. to a concentration of 2 to 25 wt .-%, and thus be converted into a storage-stable liquid formulation. Complete drying, e.g. Spray drying, into a redispersible solid

Azo colorant preparation is possible. The concentration by distilling off the

Water or organic solvent can also be used before membrane filtration.

Ultrafiltration or is preferred for cleaning, desalting and concentration of the colorant dispersion prepared according to the invention

Membrane filtration applied. The membranes used for this can be constructed either from organic materials or from inorganic materials. As organic membrane materials such. B. polyvinylidene fluoride, cellulose acetate, polytetrafluoroethylene, copolymers of polyacrylonitrile and vinyl pyrrolidone, polysulfone, polyamide or hydrophilized polyolefins in question. Inorganic materials are, for example, those made of porous carbon, the surface of which is covered with a thin layer of zirconium oxide or aluminum oxide, or of porous glass. The membranes are expediently used in tubular form, so that several tubes can be combined in tubular membrane modules. The colorant dispersions produced according to the invention can contain an organic solvent or mixtures of such solvents as an additional component, these solvents optionally having a water-retaining effect. Suitable solvents are, for example, monohydric or polyhydric alcohols, their ethers and esters, for example alkanols, in particular with 1 to 4 carbon atoms, for example methanol, ethanol, propanol, isopropanol, butanol, isobutanol; di- or trihydric alcohols, in particular with 2 to 6 carbon atoms, for example ethylene glycol, propylene glycol, 1,3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1,6-hexanediol, 1, 2,6- Hexanetriol, glycerin, diethylene glycol, dipropylene glycol, triethylene glycol, polyethylene glycol, tripropylene glycol, polypropylene glycol; lower alkyl ethers of polyhydric alcohols, such as, for example, ethylene glycol monomethyl or ethyl or butyl ether, triethylene glycol monomethyl or ethyl ether; Ketones and ketone alcohols, such as, for example, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl pentyl ketone, cyclopentanone, cyclohexanone, diacetone alcohol; Amides such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone.

Furthermore, the colorant dispersions produced according to the invention may also contain further additives, in particular those customary for ink-jet inks, these likewise being added either directly before, in the course of and / or after the azo coupling or only after the concentration and / or purification step. These additives are, for example, preservatives, antioxidants, degassers / defoamers and agents for regulating the viscosity, for example polyvinyl alcohol, cellulose derivatives or water-soluble natural or artificial resins and polymers as film formers or binders to increase the adhesive and abrasion resistance. Organic or inorganic bases and acids are used as pH regulators. Preferred organic bases are amines, such as, for example, ethanolamine, diethanolamine, triethanolamine, N, N-dimethylethanolamine, diisopropylamine, aminomethylpropanol or dimethylminomethylpropanol. Preferred inorganic bases are lithium, sodium, potassium hydroxide or ammonia. Other constituents can be hydrotropic compounds, such as formamide, Urea, tetramethyl urea, e-caprolactam, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, butyl glycol, methyl cellosolve, glycerin, sugar, N-methylpyrrolidone, 1, 3-diethyl-2-imidazolidinone, thiodiglycol, sodium benzenesulfonol sulfonate Toluene sulfonate, Na cumene sulfonate, Na benzoate, Na salicylate or Na butyl monoglycol sulfate.

Ink-jet inks are understood to mean both inks on an aqueous (including microemulsion inks) and non-aqueous ("solvent-based") basis, UV-curable inks and those inks which work according to the hot-melt process.

Ink-jet inks on an aqueous basis essentially consist of 0.5 to 100% by weight, preferably 1 to 50% by weight, of one or more of the colorant dispersions according to the invention, 0 to 30% by weight of one or more hydrotropes, ie water-retaining compounds and / or organic solvents and possibly the rest water. If necessary, the water-based ink jet inks may also contain water-soluble binders and other additives, such as e.g. Surfactants and wetting agents, degassers / defoamers, preservatives and antioxidants.

Solvent-based ink jet inks essentially consist of 0.5 to 30% by weight of one or more of the colorant dispersions according to the invention, 70 to 95% by weight of an organic solvent and / or a hydrotropic compound. Optionally, the solvent-based ink-jet inks can contain carrier materials and binders which are soluble in the "solvent", such as e.g. Polyolefins, natural and synthetic rubber, polyvinyl chloride, vinyl chloride / vinyl acetate copolymers, polyvinyl butyrals, wax / latex systems or combinations of these compounds.

UV-curable inks essentially contain 0.5 to 30% by weight of one or more of the colorant dispersions according to the invention, 0.5 to 95% by weight

Water, 0.5 to 95% by weight of an organic solvent, 0.5 to 50% by weight a radiation-curable binder and optionally 0 to 10% by weight of a photoinitiator.

Hot-melt inks are usually based on waxes, fatty acids, fatty alcohols or sulfonamides, which are solid at room temperature and become liquid when heated, the preferred melting range being between approx. 60 and approx. 140 ° C. Hot melt ink jet inks essentially consist of 20 to 90% by weight of wax and 1 to 15% by weight of one or more of the colorant dispersions produced according to the invention. Furthermore, 0 to 20% by weight of an additional polymer (as a "dye dissolver"), 0 to 5% by weight of dispersing aid, 0 to 20% by weight of viscosity regulators, 0 to 20% by weight of plasticizer, 0 to 10% by weight % Stickiness additive, 0 to 10% by weight transparency stabilizer (prevents, for example, the crystallization of the wax) and 0 to 2% by weight antioxidant. Typical additives and auxiliaries are e.g. in U.S. Patent 5,560,760.

The ink jet inks can be produced by adding the colorant dispersion into the microemulsion medium or into the aqueous or non-aqueous medium or into the medium for producing the UV-curable ink or into the wax for producing a hot-melt ink jet Ink is dispersed.

In addition to printing on paper, natural or synthetic fiber materials, foils or plastics, the colorant dispersions produced according to the invention can be used for printing a wide variety of different types of coated or uncoated substrate materials. for printing on cardboard, cardboard, wood and wood-based materials, metallic materials, semiconductor materials, ceramic materials, glasses, glass and ceramic fibers, inorganic materials, concrete, leather, food, cosmetics, skin and hair. The substrate material can be two-dimensionally flat or spatially extended, that is to say three-dimensionally designed, and can be completely or only partially printed or coated. It was found that the colorant dispersions according to the invention have advantageous overall application properties and optimally fulfill the above-mentioned tasks and requirements in ink-jet printing. The viscosity remains stable both at room temperature and when stored at 60 ° C for one week, and the particle size distribution changes only insignificantly during storage. The inks made from the dispersions are characterized above all by extremely good behavior in ink-jet printing, good stability during storage and in the ink-jet printing process. Furthermore, the prints produced are characterized by their high light and water fastness.

The colorant dispersions prepared according to the invention are also suitable as colorants in electrophotographic toners and developers, such as e.g. One-component and two-component powder toners (also called one- or two-component developers), magnetic toners, liquid toners, polymerization toners and other special toners. Typical toner binders are polymerization, polyaddition and polycondensation resins, such as e.g. Styrene, styrene-acrylate, styrene-butadiene, acrylate, polyester or phenol-epoxy resins, polysulfones or polyurethanes, individually or in combination, as well as polyethylene and polypropylene, which may also contain other ingredients, such as charge control agents, waxes or flow agents, or afterwards can get hurt.

Furthermore, the colorant dispersions prepared according to the invention are also suitable as colorants in powder coatings, in particular in triboelectrically or electrostatically sprayed powder coatings, which are used for the surface coating of objects made of, for example, metal, wood, plastic, glass, ceramic, concrete, textile material, paper or rubber , Epoxy resins, carboxyl- and hydroxyl-containing polyester resins, polyurethanes and acrylic resins are typically used as powder coating resins together with conventional hardeners. Combinations of resins are also used. For example, epoxy resins are often used in combination with carboxyl- and hydroxyl-containing polyester resins. typical Hardener components (depending on the resin system) are, for example, acid anhydrides, imidazoles and dicyandiamide and their derivatives, blocked isocyanates, bisacyl urethanes, phenolic and melamine resins, triglycidyl isocyanurates, oxazolines and dicarboxylic acids.

In addition, the colorant dispersions prepared according to the invention are also suitable as colorants for color filters, both for additive and for subtractive color production.

Furthermore, those produced according to the invention are suitable

Colorant dispersions for pigmenting paints and dispersion paints, dispersion paints, for printing inks, e.g. textile printing, flexographic or gravure printing inks, for wallpaper paints, for water-borne paints, for wood preservation systems, for viscose spin dyeing, for paints, for sausage casings, for seeds, for glass bottles , for the mass coloring of roof tiles, for plasters, for wood stains, for paper masses, for colored pencil leads, fiber pens, inks, pastes for ballpoint pens, chalks, washing and cleaning agents, shoe care products, coloring of latex products, abrasives as well as for coloring plastics and high molecular weight Materials.

In the examples below, "parts" mean parts by weight and percentages by weight.

example 1

a) dispersant

An aqueous solution (30% w / w) of a novolak polyoxyethylene sulfosuccinate of the structure given is used:

b) diazotization

69.9 ml of a hydrochloric acid 3,3'-dichlorobenzidine dihydrochloride suspension (contains 32.6 parts of 3,3'-dichlorobenzidine dihydrochloride) are stirred in 31.7 parts of aqueous hydrochloric acid (31% w / w) and 50 parts of water. 1.4 parts of ^® Tonsil are added to this suspension, then this mixture is cooled to 0 ° C. with ice, and then mixed with 34.2 parts of aqueous sodium nitrite solution (40% w / w) and 2 hours at 10 to 15 ° C. touched. The finished diazonium salt solution is then clarified via a filter and used immediately for coupling.

c) clutch

263.4 parts of the novolak polyoxyethylene described under a)

Sulfosuccinate solution is stirred with 54.4 parts of acetoacetyl-2,5-dimethoxy-4-chloroanilide (© Naphtol AS-IRG) (100% w / w) over a period of about 12 h. Then this suspension is cooled to 5 ° C. with ice. The diazonium salt solution from b) is then metered in within 1 hour at a temperature of 5 ° C. below the surface of the Naphtol AS-IRG suspension, the pH being between pH 4 by metered addition of an aqueous sodium hydroxide solution (6% w / w) , 5 and pH 5.0 is maintained. The dispersion (P.Yellow 83) is then filtered (pore size of the filter approx. 100 μm) to rule out coarse impurities. Example 2

a) dispersant

The dispersant solution described in Example 1 is used as the dispersant.

b) diazotization

An equal amount of diazonium salt solution is prepared as described in Example 1.

c) clutch

For the preparation of the coupler suspension, 182.8 parts of the novolak-polyoxyethylene-sulfosuccinate solution described under a), 50 parts of water, 33.74 parts of acetoacetanilide (100% w / w) and 4.35 parts of acetoacetic-p-anisidide ( 100% w / w) over a period of approx. 12 h.

The entire amount of diazonium salt solution from b) is then added dropwise under the surface of the coupler suspension at a temperature of 20 ° C. in the course of 1 hour, the pH being between pH 4.5 by metered addition of an aqueous sodium hydroxide solution (6% w / w) and pH 5.0 is maintained. The nanodisperse pigment dispersion obtained (P.Yellow 126) is adjusted to a pH of 7.0 with aqueous sodium hydroxide solution (6% w / w) and filtered (pore size of the filter approx. 100 μm) in order to exclude coarse impurities.

Example 3

a) dispersant

An aqueous solution of an acrylate resin neutralized with sodium hydroxide is used, which is characterized by the following features: Structure: random copolymer of styrene and acrylic acid

Specific mass: 1290 kg / m ³

Acid number: 215 Glass transition temperature Tg: 95 ° C molecular weight (weight average): 8500 g / mol

To prepare the acrylate solution, 61 parts of sodium hydroxide are first dissolved in 1080 parts of deionized water. Then 400 parts of the polyacrylate resin are added at 60 ° C. and the mixture is stirred at this temperature until it is completely dissolved.

b) Diazotization In 100 parts of water at 70 ° C., 24.37 parts of 1,2-bis (2-aminophenoxy) ethane are stirred for 10 minutes at 70 ° C. and mixed with 23 parts of aqueous hydrochloric acid at the same temperature (31% w / w) solved. A further 34.5 parts of aqueous hydrochloric acid (31% w / w) are added to this solution, followed by stirring for 30 minutes; during this subsequent stirring time, the temperature is slowly reduced to approx. 30 to 40 ° C. The reaction mixture is then cooled to 0 ° C. with ice and 34 parts of aqueous sodium nitrite solution (40% w / w) are added below the surface within 10 minutes, the temperature remaining in a range between 0 ° C. and 10 ° C. After adding the sodium nitrite solution, the mixture is stirred at a temperature between 10 ° C. and 18 ° C. for about 15 minutes. The excess nitrite is then removed by adding amidosulfonic acid, and the solution obtained is clarified using a filter.

c) clutch

500 parts of water are introduced, then 50 parts of acetolone (100 w / w) are stirred in and then at room temperature with 54 parts of aqueous

Sodium hydroxide solution (33 w / w) dissolved. This solution is first cooled to 10 ° C. with ice, then a solution of 29.4 parts of acetic acid (100% w / w) in 100 parts of water is added dropwise at 10 ° C. in the course of 10 minutes. The suspension thus obtained should then have a pH in the range from pH 6.9 to pH 7. 453 parts of the aqueous acrylate solution described under a) are added to this suspension as a dispersant, a pH of 8.2 being established. The suspension described under b) is then added Diazonium salt solution was added dropwise at 10 ° C. within 10 minutes. The nanodisperse pigment dispersion obtained, which has a pH of 6.2, is stirred at about 10 to 20 ° C. for about 1 hour until there is no longer any excess diazo. The dispersion (P.Yellow 180) is then adjusted to pH 8 with aqueous sodium hydroxide solution (33 w / w) and filtered (pore size of the filter approx. 100 μm) to rule out coarse impurities.

Example 4

a) dispersant

The acrylate resin solution described in Example 3 is used as the dispersant. Furthermore, a tallow fatty alcohol alkoxylate, made from 1 mol tallow fatty alcohol and 25 mol ethylene oxide, is used.

b) diazotization

20.9 parts of dimethyl aminoterephthalate are stirred in 27 parts of water. 40 parts of aqueous hydrochloric acid (31% w / w) are then added and the mixture is stirred for 2 hours. The suspension obtained is cooled to 10 ° C. with ice, and then 18.05 parts of an aqueous sodium nitrite solution (40% w / w) are dropped under the surface within 20 to 30 minutes, the temperature being in a range between 10 ° C. and 15 ° C. After the addition of the sodium nitrite solution, the mixture is stirred at a temperature between 15 and 18 ° C for 45 minutes. The excess nitrite is then removed by adding amidosulfonic acid. The solution obtained is then clarified using a depth filter.

c) clutch

30 parts of N-acetoacetyl-6-methoxy-7-amino-quinoxaline-2,3-dione are stirred in 400 parts of water within about 12 hours and then dissolved in 45 parts of aqueous sodium hydroxide solution (33% w / w). In a further vessel, a mixture of 1000 parts of demineralized water, 22.8 parts of acetic acid (100% w / w) and 16 parts of that described under a) Tallow fatty alcohol ethoxylates (10% w / w) submitted. The N-acetoacetyl-6-methoxy-7-amino-quinoxaline-2,3-dione solution is added dropwise to this template at a temperature between 0 ° C. and 10 ° C. within 15 minutes. 160 parts of aqueous sodium acetate solution (4N) are added to the suspension obtained in this way, a pH of 8 being established. Then 102.2 parts of the aqueous polyacrylate solution described under a) are added as a dispersant, and the mixture is stirred at 10 ° C. for 30 minutes. To the suspension thus produced, which has a pH of 8.0, the diazonium salt solution b) is added dropwise below the surface within 1 hour at 10 to 20 ° C., the pH being determined by metered addition of a mixture of 408.8 parts of the a) described aqueous acrylate solution in 600 parts of water and 65 parts of aqueous sodium hydroxide solution (6% w / w) is kept between pH 7.4 and pH 7.5. The nanodisperse pigment dispersion obtained (P.Yellow 213), which has a pH of 7.3, is stirred at 20 ° C. for about 1 hour until the excess diazo is no longer detectable.

The dispersion is then filtered (pore size of the filter approx. 100 μm) to exclude coarse impurities.

Example 5

a) dispersant

The same polyacrylate solution is used as the dispersant as in

Example 3 has been described.

b) diazotization

An equal amount of diazonium salt solution is prepared as described in Example 4.

c) Coupling Within a period of about 12 hours, 30 parts of N-acetoacetyl-6-methoxy-7-amino-quinoxaline-2,3-dione are stirred in 400 parts of water and then with 35 parts of aqueous sodium hydroxide solution (33% w / w) solved. In one a mixture of 1000 parts of water and 16.3 parts of acetic acid (100% w / w) is placed in the second vessel. The N-acetoacetyl-6-methoxy-7-amino-quinoxaline-2,3-dione solution is added dropwise to this template at a temperature between 0 ° C. and 10 ° C. within 15 minutes. The suspension obtained is mixed with 102.2 parts of the aqueous polyacrylate solution described under a) as a dispersant, a pH of about 9.2 being established. The mixture is then stirred for a further 30 minutes at 20 ° C. The entire amount of the diazonium salt solution from b) is then added dropwise to the dispersion prepared in this way, which has a pH of 9.2, below the surface at 20 ° C. in the course of 1 hour. The pH is determined by the metered addition of a mixture

408.8 parts of the aqueous acrylate solution described under a) in 1600 parts of water, which was also adjusted to pH 12.5 with an aqueous sodium hydroxide solution (33% w / w), kept between pH 7.3 and pH 7.4 , The colloidal dispersion obtained (P.Yellow 213), the pH of which is 7.3, is stirred for about 1 hour at 20 ° C. until no excess diazo is detectable. Then the dispersion is roughly filtered (pore size of the filter approx. 100 μm) in order to exclude coarse impurities.

Cleaning and concentration of pigment dispersions

The pigment dispersions prepared according to Examples 1 to 5 above are purified, desalted and concentrated by means of membrane filtration (ultrafiltration: commercially available polysulfone membrane with a selectivity of 3500 daltons; area: 16 cm ² ). In order to achieve a sufficient desalination rate, the filtration system is connected to an N ₂ compressed gas bottle and pressurized with 30 bar. 200 ml of saline solution are eluted per process step, then the system is depressurized and filled with 200 ml of deionized water. The desalination process is monitored by measuring the conductivity of the eluate. Typically, the conductivity of freshly made pigment or

Dye dispersions in a range between 5 and 7 mS / cm. When the conductivity has dropped to a value of 0.2 mS / cm, ie after approx. If 2000 ml of water are eluted, the desalination is stopped. If necessary, the dispersion can be concentrated by a factor of approx. 4-8 by no longer adding to the ultrafiltrate; the concentration of colorant can thus be increased from 0.4 - 3% to 3 - 25%.

Examination of the physical properties of the pigment dispersions mentioned in the examples:

a) Viscosity measurement (dynamic viscosity) The viscosity was determined using a cone-plate viscometer (Roto Visco 1) from Haake (titanium cone: 0 60 mm, 1 °), the dependence of the viscosity on the shear rate in a range between 0 and 700 1 / s was examined. Depending on the pigment and dispersant concentration, the pigment preparations listed in the examples have viscosities between 1 mPas and 50 mPas and thus show excellent flowability. Even during long storage periods there are no or only very slight changes in viscosity, i.e. the dispersions are all very stable.

b) particle sizes

The particle sizes of the preparations were determined using the CHDF method (capillary hydrodynamic fractioning).

In Table 1, D are prepared ₅ o values in Examples 1 to 5

Pigment dispersions, each before and after desalination and concentration, determined. The measurements show that in all cases there are only slight changes in the mean particle sizes. In the course of desalination and

Concentration, there is no coagulation of the pigment particles, which indicates very good stability of the dispersions. Table 1 :

To check the long-term storage stability, some of the dispersions were stored at 25 ° C for a long time. No signs of sedimentation were observed even after 3 to 6 months, which indicates a very high stability of the dispersions produced. Testing the printing properties of the pigment preparations

Knowing the physical properties of the pigment preparations is not sufficient to make a statement about their suitability for ink-jet printing. The behavior of the pigment dispersions during the printing process in the nozzles plays an important role, especially for thermal inkjet printing (bubble jet). Due to the large, if only brief, thermal loads, there must be no decomposition of the pigment dispersion, e.g. one

Desorption of the dispersant molecules from the pigment surface, which would lead to agglomeration of the pigment particles. Such decomposition processes could lead to deposits on the heating elements (cogation), on the other hand, the decomposition products can clog the nozzles over time (nozzle clogging).

The suitability of pigment preparations for the production of inks for ink-jet printing can therefore only be decided by printing tests be undertaken. In order to assess the printing properties of the pigment dispersions, test inks were produced from them and their printability was examined with a thermal inkjet printer (Table 2).

For the preparation of the test inks, the pigment dispersions were first filtered through a 1 μm filter to remove any coarse particles, e.g. To separate dust particles. The filtered preparations were then optionally diluted with water and mixed with other low molecular weight alcohols and polyols. The composition of the test inks was chosen so that the viscosity was in a range from 1.5 to 5 mPas. In order to adjust the surface tension of the inks to a value required for optimal printing behavior, small amounts of surfactant can also be added if necessary.

The test inks were characterized using the following methods and devices:

a) The behavior of the ink during jet formation on the printhead With the help of a special measuring arrangement (HP Print RIG with Optica System from Vision Jet) the behavior of the test inks during ink jet printing with a thermal ink jet printer from HP (HP 420) examined. The behavior of the ink jets during the printing process at individual nozzles of the ink jet print head can be examined by means of a video camera. The video images provide information on how the pigmented ink behaves during the formation of the ink jets, whether the ink is ejected in the form of straight, linear jets from the nozzles of the printhead, whether individual drops are formed or whether the drops have satellites. The investigations provide additional information on the shape of the ink drops and show irregularities in the drop formation, which are caused, for example, by clogging of individual nozzles. The investigated inks have a very good jet formation behavior, which can be seen from the fact that the individual ink jets are aligned in parallel and leave the nozzles perpendicular to the surface. None of the nozzles are clogged. The jet and drop formation is very regular, with individual drops forming from the ink jets over time, smaller satellite drops are not observed.

b) Examination of the pressure behavior

In addition, test images were printed on commercially available normal paper (copy paper) and special paper (premium quality from HP) using a commercially available printer (HP 420). The printouts were assessed visually with regard to the quality and quality of the printed image. It was examined whether the paper was excessively moistened, whether the pigment penetrated the paper or whether it adhered to the surface of the paper. Furthermore, it was examined how exactly fine lines were reproduced, whether the ink ran on the paper, which resulted in low resolution, or whether high-resolution prints could be produced. After longer pauses in printing, the pressure behavior was examined, i.e. whether a good and error-free printout was guaranteed immediately or whether individual nozzle channels were blocked due to drying of the ink, which led to a poor print image.

Criteria a) and b) were used to assess the printing behavior and the printing quality of the inks on the basis of the following evaluation scale with the marks from 1 to 6 (see Table 2):

Grade 1 - very good printed image, nice and even

Jet and drop formation! Grade 2 - very good print, uniform jet, but uneven drop formation! Grade 3 - good print quality, uneven jet and drop formation! Note 4 - Uneven, fuzzy print image, random orientation of the ink jets and drops! Grade 5 - Bad, streaky print image, individual nozzles are blocked! Note 6— Ink cannot be printed, after a short time all nozzles are blocked!

Table 2:

The pigment preparations thus meet the requirements of ink-jet printing in terms of the physical and printing properties in an excellent manner and are therefore particularly suitable for applications in ink-jet printing.

Claims

claims:

1. A process for the production of finely divided dispersions of insoluble to poorly soluble azo colorants, characterized in that a diazonium salt capable of coupling is coupled with a coupling component in the presence of at least 45% by weight, based on the theoretically expected amount of colorant, of a surface-active agent.

2. The method according to claim 1, characterized in that coupling in the presence of at least 50 wt .-%, based on the theoretically expected amount of colorant, of a surface-active agent.

3. The method according to claim 1 or 2, characterized in that one adds the diazonium salt to the coupling component presented.

4. The method according to at least one of claims 1 to 3, characterized in that the finely divided dispersion obtained after the coupling is purified by filtration, desalted and optionally concentrated.

5. The method according to claim 4, characterized in that after the filtration, the finely divided dispersion is incorporated into an aqueous, aqueous-organic or organic medium customary for ink-jet inks.

6. The method according to at least one of claims 1 to 5, characterized in that the insoluble to poorly soluble azo colorant

Azo pigment is.

7. The method according to at least one of claims 1 to 6, characterized in that the azo pigment is a monoazo, disazo, ß-naphthol, naphtol AS, acetoacetylamino-benzimidazolone, acetoacetylamino-quinazolinedione or acetoacetylamino-quinoxalinedione pigment ,

8. The method according to at least one of claims 1 to 7, characterized in that the surface-active agent is a nonionic surfactant from the group of alkyl or aryl alkoxylates, or alkoxylation products of alkyl phenols.

9. The method according to at least one of claims 1 to 8, characterized in that the surface-active agent is an acrylic resin copolymer or a block-polymethacrylic acid ester block-polyethylene oxide copolymer, block-polystyrene block-polyethylene oxide copolymer, block-polyethylene oxide block - Polypropylene oxide copolymer, block polyethylene diamine block polyethylene oxide block polypropylene oxide copolymer, polyvinyl pyrrolidone or polyvinyl alcohol.

10. The method according to at least one of claims 1 to 9, characterized in that the surface-active agent is a cationic or anionic surfactant.

11. The method according to at least one of claims 1 to 10, characterized in that the finely divided dispersion is prepared in the absence of a grinding step.