CA2207666A1 - Electrophotographic toner and developer comprising a magenta azo pigment - Google Patents

Abstract

Electrophotographic toner and developer comprising a magenta azo pigment The use of an azo pigment of the formula (1)

Description

~ CA 02207666 1997-06-12 .

, HOECHST AKTIENGESELLSCHAFT HOE 96/F 148 Dr.HU/we Description 5 Electrophotographic toner and developer comprising a magenta azo pigment The present invention relates to an electrophotographic toner and developer based on C.l. Pigment Red 57:1 as colorant.

10 In electrophotographic recording techniques a "latent charge image" is produced on a photoconductor. This latent charge image is developed by applying an electrostatically charged toner which is then transferred, for example to paper,textiles, foils or plastic, and is fixed by means, for example, of pressure, radiation, heat or the action of a solvent. Typical toners are one- or two-component powder15 toners (also called one- or two-component developers); furthermore, special toners are also employed, examples being magnetic or liquid toners and polymerization toners (L.B. Schein, "Electrophotography and Development Physics"; Springer Series in Electrophysics 14; Springer-Verlag, 2nd edition, 1992).

20 One measure of the quality of a toner is its specific charge q/m (charge per unit mass). In addition to the sign and level of the electrostatic charge, the rapid obtainment of the desired charge level and the constancy of this charge over a prolonged activation period, in particular, is a decisive quality criterion. Moreover, the insensitivity of the toner to climatic effects such as temperature and atmospheric 25 humidity is another important suitability criterion.

Both positively and negatively chargeable toners are used in photocopiers, laserprinters, LEDs (light-emitting diodes), LCS (liquid crystal shutter) printers or other digital printers based on electrophotography, depending on the type of process and 30 type of equipment.

To obtain electrophotographic toners or developers with either a positive or negative charge it is common to add charge control agents. As the color-imparting component in color toners use is typically made of organic color pigments. Relative to dyes, ~ CA 02207666 1997-06-12 color pigments have considerable advantages on account of their insolubility in the application medium, examples being improved thermal stability and light fastness.

On the basis of the principle of subtractive colour mixing it is possible, with the aid of the three primary colors yellow, cyan and magenta, to reproduce the entire spectrum of colors visible to the human eye. Exact color reproduction is only possible if the particular primary color satisfies the precisely defined color requirements. If this is not the case, some shades cannot be reproduced and the color contrast is inadequate.
In the case of full color toners the three toners yellow, cyan and magenta must not only meet the precisely defined color requirements but must also be matched exactly to one another in their triboelectric properties, since they are transferred one after another in the same device.
It is known that colorants may have a long-term effect in some cases on the triboelectric charging of toners (H.-T. Macholdt, A. Sieber, Dyes & Pigments 9 (1988), 1 19-127). Because of the different triboelectric effects of colorants and, as a result, their sometimes highly pronounced effect on toner chargeability it is not 20 possible simply to add the colorants to a toner base formulation once prepared.
Rather, it may be necessary to prepare a specific formulation for each colorant, with the nature and amount of the required charge control agent being tailored specifically. This approach is correspondingly laborious and in the case of color toners for process color is just another difficulty to add to those already described 25 above.

Furthermore, it is important for practical use that the colorants possess high thermal stability and good dispersibility. Typical temperatures for incorporation of colorants in the toner resins are between 100~C and 200~C when using compounders or 30 extruders. Accordingly, a thermal stability of 200~C, or even better 250~C, is a great advantage. It is also important that the thermal stability is maintained over a prolonged period (about 30 minutes) and in different binder systems. Typical toner binders are resins formed by addition polymerization, polyaddition and poly-, ~ CA 02207666 1997-06-12 condensation, such as styrene, styrene-acrylate, styrene-butadiene, acrylate, polyester, phenolic and epoxy resins, polysulfones and poly-urethanes, individually or in combination, which may also include further ingredients, such as charge control agents, waxes or flow assistants, or may have these ingredients added 5 subsequently.

Magenta pigments for electrophotographic toners and developers are employed in numerous forms. Typically employed magenta pigments are C.l. Pigment Red 122 based on quinacridone compounds, C.l. Pigment Red 48, C.l. Pigment Red 57:1, C.l. Pigment Red 146 and C.l. Pigment Red 184 based on azo compounds and C.l.
Pigment Violet 1 and C.l. Pigment Red 8 based on triarylcarbonium compounds.

The magenta colorant C.l. Pigment Red 57:1 is of particular interest since it corresponds to the standard magenta shade. An alternative to C.l. Pigment Red 15 57:1 on account of its color is C.l. Pigment Violet 1, although this has poorer fastness properties, especially light fastness properties, so that in practical use in toners it usually has to be blended with the very much more lightfast C.l. Pigment Red 122 (2,9-dimethyl-quinacridone).

20 Fundamentally there is a need for a magenta pigment possessing a very high degree of transparency, blueness, good dispersibility and an extremely stable inherent triboelectric effect.

The term stable inherent triboelectric effect is understood as meaning that the 25 pigment reaches its maximum triboelectric effect on the toners after a very short activation time, and that this level remains stable over a very long activation period.
Toners and developers which exhibit unstable q/m values, i.e. whose level of charge depends greatly on the activation period, are correspondingly difficult to control.

30 Transparency is of central importance since, in the case of full color copiers or in printing, the colors yellow, cyan and magenta are copied or printed over one another, the sequence of the colors depending on the device. Consequently, if anoverlying color is not sufficiently transparent, the underlying color is unable to show , ' CA 02207666 1997-06-12 through to a sufficient extent and the color reproduction is distorted. In the case of copying or printing on sheets for overhead projection use, transparency is even more important, since in this case a lack of transparency even in just one colormakes the whole of the projected image appear gray.

The object of the present invention was to provide an extremely strongly colored, transparent and bluish magenta colorant with a very stable inherent triboelectric effectl good dispersibility and high thermal stability for use in electrophotographic toners and developers, powders and powder coatings, inkjet inks and in electret 1 0 materials.

This object has surprisingly been achieved by the azo pigment described below.
The present invention provides for the use of an azo pigment of the formula (1 ) SO (~) ~ , N--N ~ ca2+

coo (-) ( 1 ) as colorant in electrophotographic toners and developers, powders and powder coatings, electret materials and in inkjet inks, wherein the azo pigment powder has a specific surface area of more than 70 m2/g, preferably more than 80 m2/g, especially more than 85 m2/g, and wherein the azo pigment particles have a length-to-width ratio of on average less than 2.8:1 and a mean particle size d50 ~f less than 130 nm.
The pigment powder may have a specific surface area of up to 200 m2/g, in particular up to 150 m2/g.

A pigment having the structure according to formula (1 ) is already known and is on the market under the designation C.l. Pigment Red 57:1. What is new and surprising, however, is that a Pigment Red 57:1 having the novel particle morphology, particle size and specific surface area represents a significant improvement over the C.l. Pigment Red 57:1 that has been customary to date in , ~ CA 02207666 1997-06-12 respect of transparency and blueness, which are coupled with good color strengthand dispersibility and a stable inherent electrostatic effect. In particular, the length-to-width ratio is on average less than 2.7:1 and the particle size d25 is less than 100 nm and d75 is less than 180 nm.

Conventional C.l. Pigment Red 57:1 possesses a strong negative electrostatic effect (JA-A 62-71 966, P.Gregory "High Technology Applications of Organic Colorants", Plenum Press, New York 1991, pp. 99-102). US-A-4 957 841 describes how, by adding appropriate ammonium, iminium, phosphonium, arsonium or stibonium 10 compounds, it is possible to eliminate wholly or in part the strong negative triboelectric effect, it being necessary to add these additives alternatively during the coupling reaction, during laking or during the pigment finish.

A description has also been given of how by means of specific master-batches, i e.
15 highly concentrated preliminary dispersions of pigment in selected resins, it is possible to suppress the inherent triboelectric effect of C.l. Pigment Red 57:1 (V.
Schlosser et al., Society of Imaging Science and Technology, 11 th Congress on Advances in Non-lmpact Printing Technologies, Hilton Head, SC, Oct. 29-Nov. 11, 1995, Proceedings pp. 110-112.). In addition to the additional operating step, this 20 method has the disadvantage that it is necessary to use a tailor-made masterbatch for each toner resin, which is highly complex and uneconomic. If only the masterbatch based on the standard resin indicated is used, then the toner systembecomes contaminated by foreign resin.

25 By using the novel azo pigment, the disadvantages of such additional operating steps are avoided.

The preparation of conventional C.l. Pigment Red 57:1 is described, for example, in "Ullmanns Encyklopadie der Technischen Chemie", Volume 18, pp. 661~95, Verlag 30 Chemie, Weinheim 1979; or in W. Herbst, K. Hunger, "Industrial Organic Pigments", VCH Weinheim 1993 or in "Pigment Handboo~', editor: T.C. Patton, J.Wiley + Sons,New York, 1973. The azo pigment used in accordance with the invention is prepared by adding, at any desired point in time during the synthesis, an auxiliary based on _ , ~ CA 02207666 1997-06-12 nonionogenic alkoxylates of alcohols, fatty alcohols, phenols, alkylphenols, naphthols, alkylnaphthols or fatty amines and ethylene oxide and/or propylene oxide, and also block polymers of ethylene oxide and propylene oxide; compounds with a poly(ethyleneoxy) chain or a poly(ethyleneoxy)-poly(methylethyleneoxy) chain 5 which are attached via an oxygen or a nitrogen atom to radicals of the following kind: primary or secondary alkyl radicals having 6 to 26 carbon atoms, particularly preferably alkyl radicals with a chain length of 9 to 18 carbon atoms, specifically nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, 2-butyloctyl, 2-phenyloctyl, 2-hexyldecyl, 2-heptylundecyl, 10 2-octyldodecyl, 2-nonyltridecyl, 2-decyltetradecyl, 10-undecenyl, oleyl, 9-octadecenyl, linoleyl or linolenyl radicals; cycloaliphatic radicals having 6 to 30 carbon atoms; aromatic radicals, such as the substituted or unsubstituted phenylradical or the alkylphenyl radical having up to three primary or secondary alkylradicals, preferably the hexylphenyl, heptyl-phenyl, octylphenyl, nonylphenyl, 1~ undecylphenyl, dodecylphenyl, isononyl-phenyl, tributylphenyl or dinonylphenyl radical, it being possible for the phenyl radical to be substituted by further aromatic radicals, such as the benzyl-p-phenyl-phenyl radical; naphthyl or alkylnaphthyl radicals, preferably the a-naphthyl or ~-naphthyl radical or the alkyl-~-naphthyl radical having 1 to 3 unbranched or branched alkyl groups, examples being methyl, 20 butyl, octyl, nonyl, decyl, dodecyl and tetradecyl; unsubstituted or alkyl-substituted heterocyclic radicals or alkyl radicals substituted by heterocyclic radicals, for example the 2-[2-(8-heptadecen-1-yl)-4,5-dihydro-1-imidazolyl]ethyl radical.
It is also possible to employ mixtures of the abovementioned compounds and, in particular, mixtures as are produced in the alkoxylation, using ethylene oxide and/or 25 propylene oxide, of synthetic fatty alcohols from the oxo synthesis or of fatty alcohols from natural raw materials (after fat cleavage and reduction). Natural raw materials include coconut oil, palm oil, cottonseed oil, sunflower oil, soybean oil, linseed oil, rapeseed oil, tallow and fish oil. Also suitable are corresponding fatty amine alkoxylates of these natural raw materials, especially coconut fatty amine, 30 tallow amine, oleylamine or dialkyl-fatty amine oxides, for example dimethylcoconut-alkylamine oxide.
Mention may also be made of alkoxylated surface-active auxiliaries of relatively high molecular weight (surfactants) as are described, for example, in the following _ _ _ _ _ , ~ CA 02207666 1997-06-12 documents: DE-A1-27 30 223, DE-B2-21 56 603, DE-A1-30 26 127, DE-B2-24 21 606 and EP-A1-00 17 189.

Also possible, furthermore, is the use of modern nonionic surfactants based on 5 renewable raw materials, for example sugar alkylates, it being possible to employ all of the abovementioned nonionic surfactants as a mixture with anionic or cationicsurfactants as well. Anionic surfactants of particular interest are those whose polar hydrophilic group comprises sulfonic acid, sulfuric monoester, phosphoric partial ester or carboxylate functions, such as, for example, with particular preference10 rosin, its salts and derivatives and abietic acid, its salts and derivatives. The cationic surfactants generally comprise a quaternary amine function (phosphonium functions are also possible) and corresponding counterions such as halide or anions derived from oxygen acids of the main group elements, it also being possibie for the counterions to be present in intramolecular form (betaine-type surfactants). Primary, 15 secondary and tertiary amines can likewise be employed; their surfactant effect is a function of the pH during the addition. Particular preference in the context of the present invention is given to rosins and abietic acids.

The auxiliary can be added before, during or after the azo coupling and/or before, 20 during or after the pigment finish. It is expedient to add the auxiliary in an amount such that the ready-prepared powder pigment contains from 20 to 50% by weight, preferably from 25 to 40% by weight of auxiliary, based on the overall weight.

By means of the preparation process described said azo pigment is obtained in the 25 novel form, said auxiliary being loaded on the pigment crystallites.

Other than in electrophotographic toners and developers, an inherent triboelectrically altered effect of a pigment can also lead to an improvement in the electrostatic charging of powders and coating materials, especially in 30 triboelectrically or electrokinetically sprayed powder coatings as are employed for the surface coating of articles made, for example, from metal, wood, plastic, glass, ceramic, concrete, textile material, paper or rubber. Powder coating technology is employed, for example, in the coating of small articles such as garden furniture, _ , ~ CA 02207666 1997-06-12 camping equipment, domestic appliances, vehicle parts, refrigerators and shelving, and in the coating of workpieces having complex shapes. The powder coating or the powder obtains its electrostatic charge, in general, by one of the two followingmethods:
5 a) in the case of the corona method the powder coating or the powder passes a charged corona and in doing so is charged;
b) in the triboelectric or electrokinetic method, the principle of frictional electricity is utilized.

10 In the spraying device the powder coating or the powder receive an electrostatic charge which is opposite to the charge of the friction partner, generally a hose or spraypipe made, for example, of polytetrafluoro-ethylene. A combination of both methods is also possible.

15 Typical powder coating resins employed are epoxy resins, carboxyl- and hydroxyl-containing polyester resins, polyurethane resins and acrylic resins, together with the customary hardeners. Combinations of resins are also used. For example, epoxy resins are often employed in combination with carboxyl- and hydroxyl-containing polyester resins. Examples of typical hardener components for epoxy resins are acid 20 anhydrides, imidazoles and also dicyandiamide and derivatives thereof. For hydroxyl-containing polyester resins, examples of typical hardener components are acid anhydride, capped isocyanates, bisacylurethanes, phenolic resins and melamine resins. For carboxyl-containing polyester resins, examples of typical hardener components are triglycidyl isocyanurates or epoxy resins. In acrylic resins 25 typical hardener components employed are, for example, oxazolines, isocyanates, triglycidyl isocyanurates or dicarboxylic acids.
The disadvantage of inadequate charging is observed in particular in the case oftriboelectrically or electrokinetically sprayed powders and powder coatings which have been prepared on the basis of polyester resins, especially carboxyl-containing 30 polyesters, or on the basis of so-called mixed powders, also referred to as hybrid powders. Mixed powders are understood to be powder coatings whose resin basis consists of a combination of epoxy resin and carboxyl-containing polyester resin.
The mixed powders form the basis for the powder coatings which are most , . CA 02207666 1997-06-12 frequently encountered in practical use. Inadequate charging of these powders and power coatings causes the deposition ratio and throwing power on the workpiece that is to be coated to be inadequate, it being known that, in certain circumstances, the inherent triboelectric effect of a pigment can also be responsible for the loss of chargeability of a resin system which per se is suitable (H-T. Macholdt, "Ladungssteuermittel als Konzept fur die triboelektrische Aufladung" [Charge control agents as a concept for triboelectric charging]; EPS-Schriftenreihe "Praxis Forum, Fachbroschure Oberflachentechnik 27/91" page 102-1 11; Technik +
Kommunikations Verlags GmbH, Berlin (1991)). The term "throwing power7' is a 10 measure of to what extent a powder or powder coating is deposited on the workpiece to be coated, including its reverse sides, cavities, in gaps and, in particular, on inside edges and corners.

Furthermore, an altered inherent triboelectric effect of a pigment can lead to an 1~ improvement in the electret properties in the case of colored (pigmented) electret materials, typical electret materials being based on polyolefins, halogenated polyolefins, polyacrylates, polyacrylonitriles, polystyrenes or fluoropolymers, for example polyethylene, polypropylene, polytetrafluoroethylene and perfluorinated ethylene and propylene, or on polyesters, polycarbonates, polyamides, polyimides, 20 polyether ketones, on polyarylene sulfides, especially polyphenylene sulfides, on polyacetals, cellulose esters, polyalkylene terephthalates and also mixtures thereof.
Electret materials have numerous fields of application and can receive their charge as a result of corona or triboelectric charging (literature reference: G.M. Sessler, "Electrets", Topics in Applied Physics, Vol. 33, Springer Verlag, New York, 25 Heidelberg, 2nd ed., 1987).

Furthermore, an altered inherent triboelectric effect of a pigment can lead to improved separation properties of colored (pigmented) polymers that are separated by electrostatic methods (Y. Higashiyau, J. of Electrostatics, 30, pages 203-212, 30 1993; and J.A. Cross "Electrostatics - Principles, Problems and Applications", Adam Hilger, Bristol, 1987, especially Section 5.3 "Electrostatic Separation" and theliterature cited therein). Accordingly, the inherent triboelectric effect of pigments is also of importance for the mass coloring of plas~ics. Similarly, the inherent CA 02207666 l997-06-l2 triboelectric effect is important in the case of process or processing steps which involve intensive frictional contact, for example spinning processes, calendering processes or other shaping techniques.

5 Moreover, the novel Pigment Red 57:1 is suitable as a colorant in inkjet inks on both an aqueous and a nonaqueous basis, especially in those inks which operate in accordance with the hot melt process. The invention provides an inkjet ink comprising from 0.01 to 50% by weight, preferably from 0.5 to 20% by weight, of the azo pigment defined in claim 1 or 2.
The particular advantage of the novel azo pigment, especially in toner binders, can be seen in comparison with what to date has been the standard for C.l. Pigment Red 57:1 (~Permanent Rubin L6B02).
For instance, the novel Pigment Red 57:1 (Example 1) exhibits a substantially 15 improved transparency (more transparent by 5 evaluation units and a blueness increased by 5 evaluation units), which means a very considerable improvement for practical use. It is worth noting in particular that the novel pigment, in comparison with the known standard, not only has a smaller particle size but also has a particle morphology which is improved in terms of an alteration from pronounced acicularity 20 in the direction of cubicity. This improvement brings about much easier dispersibility and suspendability in polymeric materials and (organic) solvents.

The improvement that is achieved in transparency is of great advantage for practical use and is also immediately evident to the human eye. Furthermore, it is surprising 25 that in spite of the strong improvement in transparency as a result of the very much higher specific surface area there is no loss in the other advantageous color properties of the pigment such as shade, thermal stability and light fastness. This becomes evident from the fact, for example, that in the X-ray diffraction diagram both the crystal modification and the position and mid-peak width of the reflection 30 bands remain virtually unchanged.

Furthermore, there is a clearly evident improvement in the inherent triboelectric effect of the novel pigment relative to the prior art to date. Whereas the C.l. Pigment _ _ _ r ~ CA 02207666 1997-06-12 Red 57:1 set out in the comparison example shows a hi~hly unstable triboelectriccharging effect, this effect is highly stable in the case of the novel pigment, i.e. the maximum charging value is attained rapidly and then remains virtually constant over 24 hours. Accordingly, a test toner containing 5% of the novel pigmen~ (Example 5 1.3.1) charges up after just 5 minutes to a peak level, whereas a comparable test toner containing a prior art pigment (Comparison Example 1.3.1) shows no constant final value even after 24 hours of frictional charging.

The novel azo pi~ment can be combined with numerous charge control agents, i.e.
10 with those providing both positive and negative control, and is able to attain good performance chargeabilities.

Suitable Gharge control agents which can be combined with the novel azo pigment are triphenylmethanes; ammonium and iminium compounds (immonium 15 compounds); fluorinated ammonium and iminium compounds; biscationic acid amides; polymeric ammonium compounds; diallyl-ammonium compounds; aryl sulfide derivatives; phenol derivatives; phosphonium compounds and fluorinated phosphonium compounds; calix(n)arenes; cyclically linked oligosaccharides (cyclodextrins); polyester salts; metal complex compounds, especially salicylate-20 metal and salicylate-nonmetal complexes and a(-hydroxy carboxylic acid-metal and -nonmetal complexes; benzimidazolones; azines, thiazines or oxazines, which are listed in the Colour Index as Pigments, Solvent Dyes, Basic Dyes or Acid Dyes.

Particular preference is given to the charge control a~ents indicated below, which 25 are combined individually, or in combination with one another, with the novel azo pigment.
Triarylmethane derivatives, for example:
Colour Index Pigment Blue 1, 1:2, 2, 3, 8, 9, 9:1, 10, 10:1, 11, 12, 14, 18, 19, 24, 53, 56, 57, 58, 59, 61, 62, 67 or, for example, Colour Index Solvent Blue 2, 3, 4, 5, 6, 30 23, 43, 54, 66, 71, 72, 81, 124, 125, and also the triarylmethane compounds listed in the Colour Index under Acid Blue and Basic Dye, provided they are suitable in terms of their temperature stability and processability, examples being Colour Index Basic Blue 1, 2, 5, 7, 8, 11, 15, 18, 20, 23, 26, 36, 55, 56, 77, 81, 83, 88, 89, Colour Index . CA 02207666 1997-06-12 Basic Green 1, 3,4,9, 10, with Colour Index Solvent Blue 125,66 and 124 in turn being of very particular suitability.
A particularly highly suitable pigment is Colour Index Solvent Blue 124 in the form of its highly crystalline sulfate or in the form of the 5 trichlorotriphenylmethyltetrachloroaluminate.

Very particular preference is given to metal complexes having CAS numbers 84179-66-8 (chromium azo complex), 115706-73-5 (iron azo complex), 31714-55-3 (chromium azo complex), 84030-55-7 (chromium salicylate complex), 42405-40-3 10 (chromium salicylate complex) and also the quaternary ammonium compound CAS
No. 11681046-9.

Examples of charge control agents of the triphenylmethane series which are highly suitable for preparing electret fibers are the compounds described in DE-A-1 91915 724 and in DE-A-1 644619.

Also suitable are triphenylmethanes as described in US-A-5 051 585, especially those of the formula ~2) R 1 ~( ~ R 3 ( 2 ) 2~ 8 ~R ~ . X ( - ) R

in which 30 R1 and R3 are identical or different and are -NH2, a mono- or dialkylamino group whose alkyl groups have 1 to 4, preferably 1 or 2, carbon atoms, a mono- or di-omega-hydroxyalkylamino groùp whose alkyl groups have 2 to 4, preferably 2, carbon atoms, an unsubstituted or N-alkyl-substituted phenylamino or , . CA 02207666 1997-06-12 phenalkylamino group whose alkyl has 1 to 4, preferably 1 or 2, carbon atoms whose phenalkyl group has 1 to 4, preferably 1 or 2, carbon atoms in the aliphatic bridge and whose phenyl nucleus can carry one or two of the following substituents:
alkyl having 1 or 2 carbon atoms, alkoxy having 1 or 2 carbon atoms, and the 5 sulfonic acid group, R2 is hydrogen or has one of the meanings specified for R1 and R3, R4 and R5 are hydrogen, halogen, preferably chlorine, or a sulfonic acid group or R4 together with R5 forms a fused-on phenyl ring, R6, R7, R9 and R10 are each hydrogen or an alkyl radical having 1 or 2 carbon 10 atoms, preferably methyl, and R3 is hydrogen or halogen, preferably chlorine, and X is a stoichiometric equivalent of an anion, especially a chloride, sulfate, molybdate, phosphoromolybdate or borate anion.

15 Particular pre~erence is given to a charge control agent of the formula (2) in which R1 and R3 are phenylamino groups, R2 is an m-methylphenylamino group and the radicals R4 to R10 are all hydrogen.

Suitability extends to ammonium and iminium compounds as described in US-A-5 015 676.

Also suitable are fluorinated ammonium and iminium compounds, as described in US-A-5 069 994, especially those of the formula (3) R13--CF=CH--CH2--N~--R33 ~ Y~~) ( 3 ) R ~ 3 in which R13 is perfluorinated alkyl having 5 to 11 carbon atoms, R23, R33 and R43 are identical or different and are alkyl having 1 to 5, preferably 1 to , CA 02207666 1997-06-12 2, carbon atoms, and Y~ is a stoichiometric equivalent of an anion, preferably a tetrafluoroborate ortetraphenylborate anion.
Preferably, 5 R13 is perfluorinated alkyl having 5 to 11 carbon atoms, R23 and R33 are ethyl, and R43 is methyl.

Also suitable are biscationic acid amides as described in US-A-5 342 723, 10 especially those of the formula (4) R14 R~4 R 2 4 _ N~- ( C H 2 ) n - N H - C 0 -~ C 0 - N H - ( C H 2 ) n ~ N ~- R 2 4 ( 4 R3~ . 2 Z R34 in which R14, R24 and R34 are identical or different alkyl radicals having 1 to 5 carbon atoms, preferably methyl, 20 n is an integer from 2 to 5, and Z~ is a stoichiometric equivalent of an anion, preferably a tetraphenylborate anion.

Also suitable are diallylammonium compounds, as described in US-A-5 475 119, especially those of the formula (5) Rls R2s ~CH\ / \ /CH~ .AQ
C H 2 C H 2 C H 2 C H 2 ( 5 ) 30 in which R15 and R25 are identical or different alkyl groups having 1 to 5, preferably 1 or 2, carbon atoms, but in particular are methyl groups, and A- is a stoichiometric equivalent of an anion, preferably a tetraphenylborate anion, and also the polymeric -CA 02207666 l997-06-l2 ammonium compounds of the formula (6), obtainable from these, as described in DE-A4 029 652 or US-A-5 187 038.

H2C~CH2--( 6 ) /N\
R l 5 R 2 s --n in which n has a value which corresponds to molecular weights of from 5000 to 500,000. Particular preference, however, is given to compounds of the formula (6) having molecular weights of from 40,000 to 400,000.

Also suitable are aryl sulfide derivatives, as described in US-A-5 378 571, especially those of the formula (7) R17- N~ - R37 ~ Rs7 ~ ( 7 ) 1 ~7 in which R17, R27, R37 and R47 are identical or diKerent alkyl groups having 1 to 5, preferably 2 or 3, carbon atoms and R57 is one of the divalent radicals -S-, -S-S-, -SO- or -SO2-.
For example, R17 to R47 are propyl groups and R57 is the group -S-S-.

Also suitable are phenol derivatives, as described in US-A~ 795 690, especially those of the formula (8) HO~S02~0H ( 8 ) CA 02207666 l997-06-l2 in which R18 and R38 are alkyl or alkenyl groups having 1 to 5, preferably 1 to 3, carbonatoms and R23 and R48 are hydrogen or alkyl having 1 to 3 carbon atoms, preferably methyl.
5 Examples which may be mentioned are the compounds in which R18 to R48 are methyl groups or in which R23 and R43 are hydrogen and R13 and R38 are the group -CH2-CH=CH2 Also suitable are phosphonium compounds and fluorinated phosphonium 10 compounds, as described in US-A-5 021 473 and in US-A-5 147 748, especially those of the formulae (9) R 1 9 _ p~_ R 3 9 E

in which R19, R29, R39 and R49 are identical or different alkyl groups having 1 to 8, preferably 20 3 to 6, carbon atoms and E~ is a stoichiometric equivalent of an anion, preferably a halide anion;
and (10) R~10 ( 1 0 ) R1 1Q-P~-R3l0 E~
I

R 41o 30 in which R110 is a highly fluorinated alkyl radical having 5 to 15, preferably 6 to 10, carbon atoms, R210, R310 and R410 are alkyl having 3 to 10 carbon atoms or phenyl.

, ~ CA 02207666 1997-06-12 An example of a compound of the formula (9) which may be mentioned is tetrabutylphosphonium bromide; examples o~ compounds of the formula (10) which may be mentioned are the compounds where R110 = C8F17-CH2-CH2-, R210=R310=R410= phenyl and E~ = PF~ or the tetraphenylborate anion.

Also suitable are calix(n)arenes as described in US-A-5 049 467 and as describedin EP-A-O 516 434, especially those of the formula (11 ) _ OH
~CH2 ~ 1 1 ) 15 in which R is hydrogen, halogen, preferably chlorine, straight-chain or branched alkyl having 1 to 12 carbon atoms, aralkyl, for example benzyl or phenethyl, -N02l -NH2 or NHR111, where R111 is alkyl having 1 to 8 carbon atoms, unsubstituted or C1-C4-alkyl-substituted phenyl or-Si(CH3)3.
Also suitable are metal complex compounds, such as chromium, cobalt, iron, zinc or aluminum azo complexes or chromium, cobalt, iron, zinc or aluminum salicylic or boric acid complexes of the formulae (12), (13) and (14) 0\,/0 ( l 2) 0/' \o . mG~

Z '--N =N--Y ' in which CA 02207666 l997-06-l2 M is a metal atom with a valency of 2 or 3, preferably chromium, cobalt, iron, zinc or aluminum, or else a nonmetal such as boron or Si, and Z' are divalent aromatic rings, preferably of the formulae N ~ 2 ~, H a I ~ H 0 3 S t~

10 andm is 1 or2;

0 /~~

R 2 ~ ~ ~M ~ R 2 1 3 in which 25 M' is a metal atom with a valency of 2 or 3, pre~erably chromium, cobalt or, iron, R113 is hydrogen, halogen, preferably Cl, nitro or amidosulfonyl, R213 is hydrogen or nitro, R313 is hydrogen, the sulfonic acid group or -Co-NH-R413 where R413 is phenyl, alkyl having 1 to ~ carbon atoms which is unsubstituted or substituted by a mono-, 30 di- or trialkylamino group, and G in formula (12) and (13) is in each case a counterion which brings about the neutrality of the complex, preferably one or more protons or one or more alkali metal or ammonium ions;

O H
'~o ,o~R2~4 R2l4~0 o~ ( l 4 ) R~
in which 10 M is a divalent central metal atom, preferably a zinc atom, R114 and R214 are identical or different, straight-chain or branched alkyl groups having 1 to 8, preferably 3 to 6, carbon atoms, for example tert-butyl.

Compounds of this sort are described in EP-A-0 162 632, US-A-4 908 225, EP-A-393 479,EP-A-0 360 617, EP-A-0 291 930, EP-A-0 280 272, EP-A- 0 255 925, EP-A-0 251 326, EP-A-0 180 655, EP-A-0 141 377, US-A4 939 061, US-A-4 623 606, US-A-4 590 141 and/or characterized by the CAS Nos 31714-55-3, 10481 S-18-1, 84179-68-8, 110941-75-8, 32517-36-5, 38833-00-00, 95 692-86-7, 85414-43-3, 136709-14-3, 135534-82-6, 135534-81 -5, 127800-82-2, 114803-10-0, 114803-08-6.
Examples of particularly preferred metal complex compounds of the formula (13) are given in Table 1 below.

Table 1 25 R113 R213 R313 R413 M' G
Cl H H - Cr H+
NO, NO7 -CoNHR413 Phenyl crH+/Na+/NH~,+
Cl H -CoNHR413 Phenyl FeH+/Na+/NH4+
Cl H -CoNHR413 -(CH2)3- cr Cl--N+(CH~)~
30-SO~NH~, H H - CoH '/Na+/NH4+

. CA 02207666 1997-06-12 Also suitable are benzimidazolones, as described in EP-A-0 347 695, especially those of the formula (15) /~N L~

R 2 l s in which R115 is an alkyl having 1 to 5 carbon atoms and R215 is an alkyl having 1 to 12 carbon atoms and L is a stoichiometric equivalent of an anion, especially a chloride or tetrafluoroborate anion.
An example which may be mentioned is the compound where R115= CH3 and R215 =

Also suitable are cyclically linked oligosaccharides as described in US-A-5 585 216, especially those of the formula (16) x16 ~0 (16) _o~

R2l6 Rl16 in which n16 is a number between 3 and 100, R116 and R216 have the meaning of OH or oR316, where R316 is substituted or unsubstituted alkyl-(C1-C18), aryl-(C6-C12) or tosyl, and X16 has the meaning CH2OH or CH2CoR316. Examples which may be mentioned are:
n16 = 6, R116 and R216 = OH, X16 = CH2OH
n16 = 7 R116 and R216 = OH, X16 = CH2OH
n16 = 8R"6 and R216 = OH, X16 = CH2OH.

, . CA 02207666 1997-06-12 Also suitable are polymer salts, as described in US-A-5 502 118, whose anionic component is a polyester which consists of the reaction product of the individual components a), b) and c) and, if used, d) and, if used, e), where a) a dicarboxylic acid or a reactive derivative of a dicarboxylic acid, which are free from sulfo groups, b) a difunctional aromatic, aliphatic or cycloaliphatic sulfo compound whose functional groups are hydroxyl or carboxyl, or hydroxyl and carboxyl, c) an aliphatic, cycloaliphatic or aromatic diol, a polyetherdiol or a poiycarbonate diol, 10 d) a poly~unctional compound (functionality ~ 2), whose functional groups are hydroxyl or carboxyl, or hydroxyl and carboxyl, and e) a monocarboxylic acid and whose cationic component comprises hydrogen atoms or metal cations.

15 Also suitable are azines of the following Colour Index Numbers: C l. Solvent Black 5, 5:1, ~:2, 7, 31 and 50; C.l. Pigment Black 1, C.l. Basic Red 2 and C.l. Basic Black 1 and 2.

In principle the novel pigment is suitable for combinations with positive and negative 20 charge control agents (CCAs). Judicious amounts in this context are from 0.01 to 20% by weight, preferably from 0.1 to 5% by weight, of charge control agent, based on the overall weight of the electrophotographic toner or developer, powder or powder coating, in order to establish the desired polarity. A particular advantage in this context is the rapid attainment of the peak charge value and its very good 25 constancy. Since good triboelectric (toner) charging requires a high toner breakdown resistance (= low conductivity), the dielectric characteristics of the novel magenta pigment contribute to the good triboelectric properties (Ku/Liepins "Electrical Properties of Polymers", Hanser Publishers, Munich-Vienna-New York, 1 987).
The combination of pigment and charge control agent can be effected subsequentlyby physical mixing during the pigment synthesis, during the finishing operation or by means of corresponding application to the pigment surface (pigment coating).

_ _ _ _ _ _ . CA 02207666 1997-06-12 The invention additionally provides an electrophotographic toner or developer comprising a customary toner binder, from 0.01 to 50% by weight, preferably from0.5 to 20% by weight, of the novel azo pigment and from 0 to 20% by weight, preferably from 0.1 to 5% by weight, of a charge control agent from the class of the 5 triphenylmethanes, ammonium and iminium compounds; fluorinated ammonium and iminium compounds; biscationic acid amide; polymeric ammonium compounds;
diallylammonium compounds; aryl sulfide derivatives; phenol derivatives;
phosphonium compounds and fluorinated phosphonium compounds; calix(n)arenes;
cyclodextrins; polyester salts; metal complex compounds; benzimidazolones;
10 azines, thiazines or oxazines.

Particular preference is given to electrophotographic toners or developers which as charge control agent comprise a compound of the formula (17) 15~NH~C~NH ~

. l / 2 So2~ ( l 7 ) ;
N H
20[~C H 3 or a compound of the abovementioned formula (3);
or a compound of the abovementioned formula (5), in which R15 and R25 are each methyl and A~ is a tetraphenylborate anion;
or a compound of the abovementioned formula (6), in which R15 and R25 are each methyl, A~ is a tetraphenylborate anion and n has a value which corresponds to the molecular weights of from 5000 to 500,000;
or a compound of the abovementioned formula (7);
or a compound of the abovementioned formula (13), in which R113 is chlorine, R213 and R313 are hydrogen, M' is chromium, cobalt or iron and G is one or two protons;
or an abovementioned polymer salt whose anionic component is a polyester.

. CA 02207666 1997-06-12 The ready suitability of the novel azo pigment for the powder coating utility isevident from the high charging current (1.2 ,uA in Example 1.3.2) which can be achieved at a spray pressure of only 3 bar, a charging current of 1 ,uA typically being regarded as the minimum requirement for satisfactory charging. The high charging current goes hand in hand with a good deposition ratio of markedly above 70% in every case.

The invention additionally provides a powder or powder coating comprising an acrylic resin or polyester resin which contains epoxide, carboxyl or hydroxyl groups, or a combination of such resins, from 0.01 to 50% by weight, preferably from 0.1 to 5% by weight, of the novel azo pigment and from 0 to 20% by weight, preferably from 0.1 to 5% by weight, of a charge control agent from the classes and preferred compounds mentioned above for electrophotographic toners.

The pigment used in accordance with the invention is incorporated homogeneously,for example by extrusion or kneading, in a concentration of from 0.01 to 50% by weight, preferably from 0.5 to 20% by weight, with particular preference from 0.1 to 5.0% by weight, based on the overall mixture, into the binder of the respective toner, developer, coating material, powder coating, electret material or of the polymer that is to be separated electrostatically. In this context the pigment employed in accordance with the invention can be added as a dried and ground powder, as a dispersion or suspension in organic or inorganic solvents, as a filtercake, masterbatch, finished preparation, made-up paste, as a compound adsorbed onto appropriate carriers, for example kieselguhr, TiO2, Al2O3, from aqueous or nonaqueous solution, or in some other form. The pigment used in accordance with the invention can likewise, in principle, also be added during the actual preparation of the respective binders, i.e. in the course of their addition polymerization, polyaddition or polycondensation.

The level of the electrostatic charge of the electrophotographic toners or of the powder coatings into which the novel pigment is homogeneously incorporated cannot be predicted and is measured on standard test systems under identical conditions (identical dispersing times, identical particle size distribution, identical r CA 02207666 1997-06-12 particle morphology) at about 20~C and 50% relative atmospheric humidity. The electrostatic charging of the toner is effected by fluidization with a carrier, i.e. with a standardized friction partner (3 parts by weight of toner per 97 parts by weight of carrier), on a roller bench (1~0 revolutions per minute). The electrostatic charge is then measured on a customary q/m measurement stand (J.H. Dessauer, H.E. Clark, "Xerography and related Processes", Focal Press, N.Y., 1965, page 289; J.F.
Hughes, "Electrostatic Powder Coating", Research Studies Press Ltd., Letchworth,Hertfordshire, England, 1984, Chapter 2). In determining the q/m value or the triboelectl-ic charge of powder coatings, the particle size exerts a great effect, which is why in the case of the toner samples or powder coating samples obtained by screening strict attention is paid to a uniform particle size distribution. Thus for toners a mean particle size of 10 ~m is aimed at, whereas for powder coatings a mean particle size of 50 ,um is practicable.

The triboelectric spraying of the powders (powder coatings) is carried out using a spraying device having a standard spray pipe and internal rod of star-shaped cross-section at maximum power throughput and with a spraying pressure of 3 bar. For this purpose the article to be sprayed is suspended in a spray booth and is sprayed from the front from a distance of about 20 cm with no further movement of the spraying device. The respective charging of the sprayed powder is subsequently measured using a "Mel3gerat zur Messung von triboelektrischer Ladung von Pulvern" [Powder triboelectric charge meter] from Intec (Dortmund). For the measurement, the measuring antenna of the measurement device is held directly inthe cloud of powder emerging from the spraying device. The current strength resulting from the electrostatic charge of powder coating or powder is indicated in ,uA. The deposition ratio is subsequently determined, in %, by differential weighing of the sprayed and the deposited powder coating.

The transparency of the novel azo pigment in toner binder systems is investigated as follows: 30 parts by weight of the pigmented test toner (for preparation see Example 1.3.1 ) are stirred with a dissolver (5 min at 5000 rpm) into 70 parts by weight of a raw varnish (consisting of 15 parts by weight of the respective toner resin and 85 parts by weight of ethyl acetate).

The resulting test toner varnish is knife-coated against a similarly produced standard pigment varnish onto suitable paper (e.g. Ietterpress paper) using a Handcoater (from RK Chemical Co. Ltd, England). An appropriate size of doctor blade is for example K bar N 3 (= 24 llm knife coating thickness). To aid determination of the transparency the paper is printed with a black bar and the differences in transparency are determined in dL values in accordance with DIN 55 98~ or in accordance with the test procedure from Pigments Marketing, Hoechst AG'~isuelle und Farbmetrische Bewertung" [Visual and colorometric evaluation] of 09.13.1990 (No. 1/1).
The residual salt content indicated in connection with the characterization of the pigment describes the specific conductivity of the extract of an aqueous pigmentsuspension (in accordance with test procedure Pigments Marketing, Hoechst AG
No. 1/10 (2/91 ) "Bestimmung der spezifischen Leitfahigkeit am Extrakt einer 15 wfil3rigen Pigmentsuspension") [Determining the specific conductivity of the extract of an aqeuous pigment suspension], and the pH indicated correspondingly is determined in accordance with the test procedure Pigments Marketing, Hoechst AG,1/9 (2/91 ) "Bestimmung des pH-Wertes am Extrakt einer wal3rigen Pigmentsuspension" [Determining the pH o~ an extract of an aqueous pigment 20 suspensionl, both of which determination methods use double-distilled water instead of the deionized water specified in the test procedure document.

The novel C.l. Pigment Red 57:1 named in Example 1 below contains, as auxiliary,abietic acid in the form of its calcium salt (CAS No. 13463-98~) (about 30 %). The 25 Pigment 57:1 specified in Comparison Example 1 is '~'Permanent Rubin L6B02 (Hoechst AG).

In the examples below, parts and percentages are by weight.

Example 1 Synthesis 37.4 parts of 4-aminotoluene-3-sulfonic acid were dissolved in 500 parts of water and 26.1 parts of sodium hydroxide solution (33 %). After cooling with ice to 0~C, 56 parts of hydrochloric aGid (31 %) were added and the mixture was then diazotized in 10 minutes at from 0 to 5~C with 34.5 parts of sodium nitrite solution (40 %).

Furthermore, 39 parts of 13-hydroxynaphthoic acid were dissolved in 1000 parts of 10 water and 70 parts of sodium hydroxide solution (33 %) at 20~C. The diazo suspension was then added to this solution over the course of 30 minutes at 20~C.
Following the addition of a solution of 37.8 parts of abietic acid in 380 parts of water and 15 parts of sodium hydroxide solution (33 %), the pH was adjusted with dilute hydrochloric acid to 9Ø For laking, a solution of 35 parts of calGium chloride (77-15 80%) in 100 parts of water was then added dropwise over 5 minutes. Following the adjustment of the pH to 6.0 with dilute hydrochloric acid the pigment suspensionwas initially heated to 80 to 85~C, stirred at this temperature for 30 minutes and then filtered with suction, and the solid product was washed with water until neutral and free of salt and was dried at 80~C to constant weight. 126.2 parts of a red color lake 20 were obtained.

1.1 Pigment characteristics BET surface area: 90 m2/g Residual moisture content (heating bulb): 1.0 % (Karl Fischer: 4.9 %, including water of crystallization) Residual salt content: 0.4 mS/cm pH: 7.4 30 Thermal stability: DTA (differential thermal analysis), 3~C/min heating rate, closed glass ampule, shows a thermal stability of markedly greater than 250~C.

. CA 02207666 1997-06-12 r Particle size and morphology (mass distribution counted by electron microscopy):the particle size and particle morphology were determined by electron micrographs of the pigment powder. For this purpose the pigment was dispersed in water for 15 minutes and then sprayed on. The micrographs are taken at magnifications of 13,000 and 29,000.

Particle size:
d50 =120 nm; d25 = 88 nm; d7s = 160 nm Particle morphology:
The length-to-width ratio was determined as 2.65:1.

Dielectric characteristics:
Qcm: 4 1015 ~: (1 kHz) 3.7 tan o ~1 kHz) 4 10-3 X-ray diffraction diagram (CuKc~ radiation):
2 theta (s= strong, m= moderate, w= weak):
4.72 (s); 11.06 (w); 13.74 (w); 15.07 (m); 15.62 (m); 18.34 (s); 18.70 (s); 19.42 (w);
21.44 (m); 26.05 (s); 27.31 (m).

1.2 Transparency In a toner resin (polyester based on bisphenol A) an improved transparency was measured (24 ,um coat thickness), the pigmented test toner having been prepared as in Example 1.3.1.
Relative to the standard indicated in the comparison example, a transparency raised by 5 evaluation units and a blue color intensified by 5 evaluation units are found at the same color strength.
Evaluation of the differences in transparency in accordance with the test procedure 1/1: 1 _ a trace, . CA 02207666 1997-06-12 2 A slightly; 3 _ noticeably; 4 _ distinctly; 5 _ substantially; 6 _ significantly more transparent.

1.3 Electrostatic properties 1 .3.1 5 parts of the pigment from Example 1.1 are incorporated homogeneously into 95 parts of a toner binder (polyester based on bisphenol A) over the course of 45 minutes using a compounder. The mixture is then ground on a universal laboratory10 mill and is subsequently classified in a centrifugal classifier. The desired particle fraction (4 to 25 ,um) is activated with a carrier consisting of silicone-coated ferrite particles with a size from 50 to 200 ,um (bulk density 2.75 g/cm3) (FBM 96-100; from Powder Techn.).

15 Measurement takes place on a customary q/m measuring stand. The use of a sieve with a mesh size of ~5 llm ensures that no carrier is entrained when the toner is blown out. The measurements are carried out at a re1ative atmospheric humidity of from 40 to 60 %. As a function o~ the activation period, the following q/m values [,uCIg] are measured:

Activation period Charge q/m [I~C/g]
5 min - 1 7 10 min -17 30 min - 16 2 h - 1 6 24h -15 1 .3.2 5 parts of the pigment are incorporated homogeneously, as described in Example 1.3.1, into 95 parts of a powder coating binder based on a TGIC polyester, for example 'l9Uralac P 5010 (DSM, The Netherlands). To determine the deposition ratio, 30 9 of the test powder coating are sprayed through a triboelectric gun at a . CA 02207666 1997-06-12 _ defined pressure. By differential weighing it is possible to determine the amount of powder coating deposited and to define a deposition ratio, in %, and a current flux value (,uA) can be derived from the charge transfer.

5 Pressure [bar] Current[,uA] Deposition ratio [%]

3 1.2 78 1 .3.3 5 parts of the novel magenta pigment and 1 part of the charge control agent described in Example 5 of DE-A4 031 705, of the formula COOH cooQ

~S S~ ~3N(CH2CH2CH3)4 are incorporated, as described in Example 1.3.1, into a toner binder (polyester based on bisphenol A) and measurements are carried out. As a function of the activation period, the following q/m values [,uC/g] are measured:

20Activation periodCharge q/m [IJC/g]
5 min - 1 10 min + 1 30 min ~ 2 2 h +3 25 24h +2 1 .3.4 5 parts of the novel magenta pigment and 1 part of the charge control agent mixture described in Preparation Example 1 of DE-A-3 901 153, (highly fluorinated 30 ammonium salt with n = 2 - 5), of the formula l2H5 F3C-(CF2-CF2)n-CF=cH-cH2-N-cH3~ B(C6H5)4 are incorporated, as described in Example 1.3.1, into a toner binder (polyester based on bisphenol A) and measurements are carried out. As a function of the activation period the following q/m values [,uC/g] are measured:

Activation period Charge q/m [~C/g]
5 min - 1 4 1 0 min - 1 8 30 min - 20 2 h -21 24 h - 21 1 .3.5 20 5 parts of the novel pigment and 1 part of the charge control agent mixture described in Preparation Example 2 of US-A-5 187 038, (cationic polymer where x = 150 - 800), of the formula H2c~cH2 ~0~ xB(C6H5)4 30 are incorporated, as described in Example 1.3.1, into a toner binder (polyester based on bisphenol A) and measurements are carried out. As a function of the activation period, the following qtm values [,uC/g] are measured:

. CA 02207666 1997-06-12 Activation period Charge qJm [IJC/g]
5 min - 9 1 0 min - 9 5 30 min - 9 2h 9 24 h - 9 10 Comparison Example 1 The conventional C.l. Pigment Red 57:1 employed in Comparison Example 1 is characterized by the following properties:

1.1 Pigment characteristics 15 BET surface area: 35 m2/g Residual moisture content: 0.5 % (Karl Fischer: 3.6 %, including water of crystallization Residual salt content: 0.1 mS/cm pH: 7. 1 Thermal stability: decomposition temperature > 250~C (DTA) 25 Particle size:
d50 =160 nm; d2s = 103 nm; d7s = 187 nm Particle morphology:
The length-to-width ratio was determined as 2.85:1 , , CA 02207666 1997-06-12 Dielectric characteristics Qcm: 3.1o15 ~: (1 kHz) 4.2 tan o (1 kHz) 310-2 X-ray diffraction diagram (CuK~ radiation):
2 theta (s= strong, m= moderate, w= weak):

4.85 (s); 1 1.94 (w); 15.09 (m); 15.66 (m); 18.34 (s); 18.68 (s); 21 .44 (m); 26.06 (s);
27.31 (m).
Comparison Example 1.2 The preparation and measurement of the test toner were carried out as described in Example 1.2.

15 Comparison Example 1.3 - Electrostatic properties Comparison Example 1.3.1 5 parts of the pigment were incorporated into the toner binder, as described in Example 1.3.1, and measurements were carried out:

Activation period Charge q/m [,uC/g]
~ min ~ 7 10 min - 8 30 min - 10 2 h - 1 3 24 h - 23

Claims (9)

1) The use of an azo pigment of the formula (1) (1) as a colorant in electrophotographic toners and developers, powders and powder coatings, in inkjet inks and in electret materials, wherein the azo pigment powder has a specific surface area of more than 70 m2/g and wherein the azo pigment particles have a length-to-width ratio of on average less than 2.8:1 and a mean particle size d50 of less than 130 nm.

2) The use as claimed in claim 1, wherein the specific surface area of the pigment powder is greater than 80 m2/g, preferably greater than 85 m2/g.

3) The use as claimed in claim 1 or 2, wherein the azo pigment comprises from 20 to 50% by weight, preferably from 25 to 40% by weight, based on the overall weight of auxiliary and azo pigment, of an auxiliary from the group of the rosins or abietic acids.

4) The use as claimed in at least one of claims 1 to 3, wherein use is made additionally of a charge control agent from the group of the triphenylmethanes, ammonium and iminium compounds; fluorinated ammonium and fluorinated iminium compounds; biscationic acid amides; polymeric ammonium compounds;
diallylammonium compounds; aryl sulfide derivatives; phenol derivatives;
phosphonium compounds and fluorinated phosphonium compounds; calix(n)arenes;
cyclically linked oligosaccharides; polyester salts; metal complex compounds;
benzimidazolones; azines, thiazines and oxazines.

5) The use as claimed in claim 4, wherein the charge control agent is employed in an amount of from 0.01 to 20% by weight, preferably from 0.1 to 5% by weight,based on the overall weight of the electrophotographic toner or developer, powder or powder coating.

6) An electrophotographic toner or developer comprising a customary toner binder, from 0.01 to 50% by weight, preferably from 0.5 to 20% by weight, of the azo pigment defined in claim 1 or 2 and from 0 to 20% by weight, preferably from 0.1 to 5% by weight, of a charge control agent from the class of the triphenylmethanes,ammonium and iminium compounds; fluorinated ammonium and fluorinated iminium compounds; biscationic acid amides; polymeric ammonium compounds;
diallylammonium compounds; aryl sulfide derivatives; phenol derivatives;
phosphonium compounds and fluorinated phosphonium compounds; calix(n)arenes;
cyclodextrins; polyester salts; metal complex compounds; benzimidazolones;
azines, thiazines and oxazines.

7) A powder or powder coating comprising an acrylic resin or polyester resin containing epoxide, carboxyl or hydroxyl groups, or a combination of these resins, from 0.01 to 50% by weight, preferably 0.1 to 5% by weight, of the azo pigment defined in claim 1 or 2 and from 0 to 20% by weight, preferably from 0.1 to 5% by weight, of a charge control agent from the class of the triphenylmethanes, ammonium and iminium compounds; fluorinated ammonium and fluorinated iminium compounds; biscationic acid amides; polymeric ammonium compounds;
diallylammonium compounds; aryl sulfide derivatives; phenol derivatives;
phosphonium compounds and fluorinated phosphonium compounds; calix(n)arenes;
cyclodextrins; polyester salts; metal complex compounds; benzimidazolones;
azines, thiazines and oxazines.

8) A process for preparing an electrophotographic toner or developer, powder or powder coating as claimed in claim 6 or 7, which comprises incorporating the azopigment and, if desired, the charge control agent homogeneously into the binder or resin of the respective toner, developer, powder or powder coating.

9) An inkjet ink comprising from 0.01 to 50% by weight, preferably from 0.5 to20% by weight, of the azo pigment defined in claim 1 or 2.