Use of novel naphthol AS-pigment-mixtures in printing-materials

Abstract

The invention relates to the use of pigment mixtures which contain at least one pigment of formulas (la) and (lb), wherein variables X.sup.1, X.sup.2, X.sup.3, X.sup.4, Y.sup.1, Y.sup.2, Z.sup.1 and Z.sup.2 are as ##STR00001##
defined and wherein the pigment mixtures are useful as dyes in printing methods.

Claims

1. A colorant comprising a pigment mixture, wherein the pigment mixture comprises at least one pigment of each of the formulae (IIIa) and (IIIb) ##STR00010## wherein, independently of one another, X.sup.1 is C.sub.1-C.sub.2-alkylcarbannoyl or di(C.sub.1-C.sub.2)-alkylcarbamoyl; Y is methyl, methoxy, ethyl or ethoxy; Z.sup.1 is phenyl or a phenyl substituted by one, two or three radicals selected from the group consisting of methyl, ethyl, methoxy, ethoxy and chlorine; Z.sup.2 is nitrophenyl or cyanophenyl, and wherein the pigments of the formulae (IIIa) and (IIIb) are different.

2. The colorant as claimed in claim 1, wherein X.sup.1 is methylcarbamoyl; Y is methoxy; Z.sup.1 is methylphenyl; and Z.sup.2 is nitrophenyl.

3. The colorant as claimed in claim 1, wherein the pigment mixture contains 1% to 99% by weight of a component of the formula (IIIa) and 99% to 1% by weight of a component of the formula (IIIb) based in each case on the total weight of the pigment mixture.

4. The colorant as claimed in claim 1, further comprising at least one auxiliary selected from the group consisting of surfactants, pigmentary dispersants, nonpigmentary dispersants, fillers, suspending agents, resins, waxes, defoamers, dust suppressants, extenders, shading colorants, preservatives, drying retardants, rheology control additives, wetting agents, antioxidants, UV absorbers, light stabilizers and combinations thereof.

5. The colorant as claimed in claim 4, wherein the shading colorant is a quinacridone pigment or an azo pigment.

6. An ink comprising the colorant as claimed in claim 1.

7. A printing ink comprising a pigment mixture including at least one pigment of each of the formulae (IIIa) and (IIIb) ##STR00011## wherein, independently of one another, X.sup.1 is C.sub.1-C.sub.2-alkylcarbannoyl or di(C.sub.1-C.sub.2)-alkylcarbamoyl; Y is methyl, methoxy, ethyl or ethoxy; Z.sup.1 is phenyl or a phenyl substituted by one, two or three radicals selected from the group consisting of methyl, ethyl, methoxy, ethoxy and chlorine; Z.sup.2 is nitrophenyl or cyanophenyl, and wherein the pigments of the formulae (IIIa) and (IIIb) are different.

8. The printing ink as claimed in claim 7, wherein X.sup.1 is C.sub.1-C.sub.2-alkylcarbamoyl; Y is methoxy; Z.sup.1 is methylphenyl; and Z.sup.2 is nitrophenyl.

9. An electrophotographic toner or developer comprising a pigment mixture including at least one pigment of each of the formulae (IIIa) and (IIIb) ##STR00012## wherein, independently of one another, X.sup.1 is C.sub.1-C.sub.2-alkylcarbamoyl or di(C.sub.1-C.sub.2)-alkylcarbamoyl; Y is methyl, methoxy, ethyl or ethoxy; Z.sup.1 is phenyl or a phenyl substituted by one, two or three radicals selected from the group consisting of methyl, ethyl, methoxy, ethoxy and chlorine; Z.sup.2 is nitrophenyl or cyanophenyl, and wherein the pigments of the formulae (IIIa) and (IIIb) are different.

10. The electrophotographic toner or developer as claimed in claim 9, wherein X.sup.1 is C.sub.1-C.sub.2-alkylcarbamoyl; Y is methoxy; Z.sup.1 is methylphenyl; and Z.sup.2 is nitrophenyl.

11. An inkjet ink comprising a pigment mixture including at least one pigment of each of the formulae (IIIa) and (IIIb) ##STR00013## wherein, independently of one another, X.sup.1 is C.sub.1-C.sub.2-alkylcarbannoyl or di(C.sub.1-C.sub.2)-alkylcarbamoyl; Y is methyl, methoxy, ethyl or ethoxy; Z.sup.1 is phenyl or a phenyl substituted by one, two or three radicals selected from the group consisting of methyl, ethyl, methoxy, ethoxy and chlorine; Z.sup.2 is nitrophenyl or cyanophenyl, and wherein the pigments of the formulae (IIIa) and (IIIb) are different.

12. The inkjet ink as claimed in claim 11, wherein X.sup.1 is C.sub.1-C.sub.2-alkylcarbamoyl; Y is methoxy; Z.sup.1 is methylphenyl; and Z.sup.2 is nitrophenyl.

13. A toner cartridge set comprising a yellow, magenta, cyan and black toner cartridge, wherein the magenta cartridge contains a toner comprising a pigment mixture including at least one pigment of each of the formulae (IIIa) and (IIIb) ##STR00014## wherein, independently of one another, X.sup.1 is C.sub.1-C2-alkylcarbamoyl or di(C.sub.1-C.sub.2)-alkylcarbamoyl; Y is methyl, methoxy, ethyl or ethoxy; Z.sup.1 is phenyl or a phenyl substituted by one, two or three radicals selected from the group consisting of methyl, ethyl, methoxy, ethoxy and chlorine; Z.sup.2 is nitrophenyl or cyanophenyl, and wherein the pigments of the formulae (IIIa) and (IIIb) are different.

14. The toner cartridge set as claimed in claim 13, wherein X.sup.1 is C.sub.1-C.sub.2-alkylcarbamoyl; Y is methoxy; Z.sup.1 is methylphenyl; and Z.sup.2 is nitrophenyl.

15. An inkjet ink set comprising a yellow, magenta, cyan and black ink cartridge, wherein the magenta ink cartridge contains an inkjet ink comprising a pigment mixture including at least one pigment of each of the formulae (IIIa) and (IIIb) ##STR00015## wherein, independently of one another, X.sup.1 is C.sub.1-C.sub.2-alkylcarbamoyl or di(C.sub.1-C.sub.2)-alkylcarbamoyl; Y is methyl, methoxy, ethyl or ethoxy; is phenyl or a phenyl substituted by one, two or three radicals selected from the group consisting of methyl, ethyl, methoxy, ethoxy and chlorine; Z.sup.2 is nitrophenyl or cyanophenyl, and wherein the pigments of the formulae (IIIa) and (IIIb) are different.

16. The inkjet ink set as claimed in claim 15, wherein X.sup.1is C.sub.1-C.sub.2-alkylcarbamoyl; Y is methoxy; Z.sup.1 is methylphenyl; and Z.sup.2 is nitrophenyl.

Description

Synthesis Example 1

(1) a) Preparation of the diazonium salt solution:

(2) 2200 g of demineralized water are initially charged, 180 g of N-methyl-3-amino-4-epoxybenzamide (1.0 mol) are scattered in and the mixture is stirred homogeneously at room temperature. After 15 minutes, the mixture is cooled to 2 C. by adding 800 g of ice and by additional external cooling, and then 290 g of hydrochloric acid (31%) are added. The precipitated hydrochloride is diazotized by adding 179 g of sodium nitrite solution (40%) at 5 to 10 C. over the course of 15 to 20 minutes. The diazonium salt solution is stirred in an excess of nitrite for 1.5 h, then a clarifying aid is added and then the mixture is filtered and any nitrite excess is eliminated by addition of amidosulfonic acid. b) Preparation of a solution of the coupling component mixture:

(3) 2000 g of water are initially charged and 186 g (0.67 mol) of N-(2-methylphenyl)-3-hydroxynaphthalene-2-carboxamide and 103 g (0.33 mol) of N-(3-nitrophenyl)-3-hydroxynaphthalene-2-carboxamide are introduced while stirring, and the mixture is heated to 95 C. and dissolved under alkaline conditions by adding 330 g of sodium hydroxide solution (33%) at 90 to 95 C. within 2 minutes. Subsequently, the mixture is cooled to from 80 to 60 C. and kept at this temperature. The warm solution can optionally still be filtered with addition of a clarifying aid. c) Azo coupling:

(4) The clarified diazonium salt solution from a) is initially charged, adjusted to pH 4.3 to 4.5 by adding about 38 g of sodium acetate (in the form of a 4 N solution) and cooled to 10 C. Thereafter, the coupler solution from b) is metered in over the course of 1 to 1.5 h while stirring, while keeping the pH at 4.8 to 5 by simultaneous addition of a total of about 190 g of hydrochloric acid (31%). Subsequently, the mixture is stirred for about 2.5 to 3 h or until the disappearance of the diazo component at RT to 30 C. and pH 5 to 6. After the coupling reaction has ended, the mixture is heated to about 50 C. for another 1 h, then filtered and washed with water. After drying and grinding, 480 g of a bluish dark red pigment mixture containing the following pigments of the formulae (1) and (2) in a mass ratio of 65:35 are obtained.

(5) ##STR00009##

Synthesis Example 2

(6) a) The preparation of the diazonium salt solution is effected analogously to synthesis example 1 a). b) The preparation of the solution of the coupling component mixture is effected analogously to synthesis example 1 b), except using 139 g (0.5 mol) of N-(2-methylphenyl)-3-hydroxynaphthalene-2-carboxamide and 154 g (0.5 mol) of N-(3-nitrophenyl)-3-hydroxynaphthalene-2-carboxamide. c) The azo coupling is effected analogously to synthesis example 1 c). After drying and grinding, 484 g of a bluish dark red pigment mixture containing the pigments of the formulae (1) and (2) in a mass ratio of 48.4:51.6 are obtained.
Use examples:
A) Coloristic properties of the pigment compositions in a toner system: a) Test toner:

(7) For production of a polyester-based test toner, the pigment compositions are dispersed in a concentration of 3% to 5% in a commercial toner resin (Finetone T 382 ES polyester; from Reichhold). For this purpose, the polyester is melted in a laboratory kneader and the pigment composition is introduced in portions. The dispersion time after the introduction of the last pigment portion is 45 min. b) Test system and analysis:

(8) In order to obtain coloristic data in a toner medium that are very substantially independent of the type of machine used and not dependent on electrostatic chargeability, transfer rate, etc., the coloristic properties of the pigment composition used are assessed by dissolving the test toner produced above in a solvent resin (30% Finetone 382 ES in THF/ethyl acetate) and then applying it with a No. 5 manual coating bar with a wet film thickness of 50 m to white test cards with/without black bars, 100230 mm, 300 g/m.sup.2. The application contains 2.5% pigment composition in each case.

(9) The color intensity and color coordinates (Table 1) were measured according to DIN 5033-7 ISO 7724-2 by means of a spectrophotometer (D65-10 observer; d/8 measurement geometry with inclusion of luster). The spectral reflection is measured, and the color measurements are evaluated in the CIELAB system (DIN 6170, IS07724-3). The relative color intensity is ascertained via the weighted K/S sum (DIN EN ISO 787-26).

(10) The optical density (OD) was measured according to DIN 16536 by means of a Gretag Macbeth densitometer with 45/0 ring optics according to DIN 5033.

(11) TABLE-US-00001 TABLE 1 Color intensity Test toner with L* a* b* in % C H OD 5% synthesis 47.1 58.9 10.3 130 59.74 348.66 1.65 example 1 3.5% synthesis 51.0 56.8 16.1 100 58.81 344.51 1.33 example 1 5% PR269 51.6 54.6 13.5 96 56.29 346.49 1.25 (comparative) 5% PR184 52.0 55.9 12.5 96 57.08 347.41 1.19 (comparative)

(12) The pigment composition of the invention in this test system attains a much higher color intensity and a higher optical density (OD) than other naphthol azo pigments (e.g. PR 269, PR 184) that are typically used in toners. At the same time, the chroma value C is higher. c) Coloristic studies by means of a paint shaker (table 2):

(13) 1 g of pigment or pigment composition is dispersed with 50 g of 30% Finetone resin (30% Finetone T 382 ES in ethyl acetate) and 25 g of mixed oxide beads (0.8 mm Y-stabilized zirconia beads) on a paint shaker for 3 hours. The colored solution is applied to paper (Algro Finess 80 g/m.sup.2) and transparent film (Treofan GND 50) with a laboratory printing machine (labratester) (potentiometer 280, corresponding to 10 m/min). The sample and reference are applied here alongside one another. Three fields with different layer thicknesses are printed. The coloristic data are determined in the 3rd field (wet film thickness 34 m) (table 2).

(14) TABLE-US-00002 TABLE 2 Pigment Example composition a* b* C h.sub.ab OD 1 Synthesis example 1 51.56 13.48 53.29 345.35 0.98 (100%) 2 Synthesis example 1 50.16 13.94 52.06 344.46 0.93 (90%) P. R. 122 (10%) 3 Synthesis example 1 49.67 15.32 51.98 342.85 0.90 (80%) P. R. 122 (20%) 4 Synthesis example 1 49.05 15.3 51.38 342.68 0.88 (70%) P. R. 122 (30%) 5 Synthesis example 1 47.29 15.8 49.86 341.52 0.81 (50%) P. R. 122 (50%) 6 (comp.) P. R. 269 (50%) 43.61 14.04 45.82 342.15 0.70 P. R. 122 (50%) 7 (comp.) P. R. 269 (33%) 42.94 15.1 45.52 340.62 0.68 P. R. 122 (66%) 8 (comp.) P. R. 269 46.34 11.81 47.82 345.71 0.80 9 (comp.) P. R. 122 41.48 16.67 44.7 338.11 0.60

(15) Examples 6 to 9 (comparative) are pigments and pigment mixtures customarily used in the toner sector.

(16) All pigment compositions of the invention have higher chroma values C than the pigments or pigment mixtures customarily used.

(17) All pigment compositions of the invention have higher optical densities OD than the pigments or pigment mixtures customarily used. d) Comparison with known magenta-colored azo pigments:

(18) The same test method as in Ab) was used to make a coloristic comparison of inventive pigment compositions and various commercially available azo pigments with the magenta pigment C.I. Pigment Red 184 (table 3).

(19) TABLE-US-00003 TABLE 3 Color Example Pigment intensity dH dC dL da db transp. Reference P. R. 184 100 0 0 0 0 0 ref 10 Synth. 120 2.4 1.14 0.53 0.49 2.61 4tra ex. 1 11 Synth. 133 3.66 0.77 0.91 0.42 3.72 5 tra ex. 2 12 PR 269 93 0.38 0.17 0.31 0.26 0.33 2tra (comp.) 13 PR 185 96 10.47 0.55 1.4 2.23 10.24 4op (comp.) 14 PR 176 101 10.43 1.79 1.86 3.46 10 2op (comp.) 16 PR 146 84 8.38 0.63 1.13 0.91 8.35 3op (comp.) 18 PR 57:1 91 3.4 3.27 0.25 2.34 4.09 2 op (comp.) 19 PR 147 93 0.46 1.13 0.08 0.96 0.75 3 op (comp.)

(20) Only the pigment compositions of the invention have high color intensities, a distinctly bluer hue and a positive chroma value compared to the reference, and they also exhibit improved transparency compared to commercial pigments (comparative examples 12-19). e) Test in chemical toners:

(21) In the production of suspension polymerization toners, a polymerization for production of the toner particles in the m range is conducted in a biphasic system composed of water and monomer (styrene, acrylates). In order that the particles obtained are colored in the desired hue, the pigment must be finely dispersed in the monomer phase and must not be transferred from the monomer phase to the aqueous phase during the process either. In other words, the pigment must have a certain affinity for the monomer mixture used and must not be too hydrophilic, since it would then be transferred to the aqueous phase or remain at the interface between monomer and water.

(22) For examination of this property, the procedure is as follows: 2.5 g of pigment, 50 g of styrene are dispersed with 150 g of glass beads in a paint shaker for 60 min. After the beads have been removed, 9 g in each case of the pigment dispersion thus produced are added to aqueous solutions having pH 11.4, 6.9 and 1.5 in 3 different beakers. Subsequently, the 3 solutions are stirred by means of a magnetic stirrer for 30 min. After the stirrer has been switched off, the phase separation and the whereabouts of the pigment (in the monomer phase or the aqueous phase) are visually assessed. Subsequently, the solutions are heated to 80 C. and stirred once again for 30 min. After the stirrer has been switched off, the phase separation and the whereabouts of the pigment are visually assessed.

(23) Assessment: The quality of the phase separation is assessed visually for each of the 6 individual tests and rated with numbers from 1 to 3, 1 being the best rating. Then the mean from the 6 individual assessments is formed for each sample. The lower this value, the better the suitability of the pigment for a suspension polymerization process; values less than 2 show that the pigment has suitable hydrophobicity (table 4).

(24) TABLE-US-00004 TABLE 4 Rating 1 2 3 Observation Aqueous phase Aqueous phase Pigment in the clear and slightly colored, but aqueous phase uncolored transparent

(25) In this test, the pigment compositions of the invention according to synthesis examples 1 and 2 achieve a value (hydrophobicity index) of 1.7 and are thus of good suitability for use in suspension polymerization processes.

(26) In addition, it is important in the dispersing of the pigments that the resulting dispersion in the monomer solution has a low viscosity value (<100 mPas). The inventive pigment formulation from synthesis examples 1 and 2 achieves, for example, a value of 36 mPas or 45 mPas, measured in a 5% dispersion of the pigment in styrene by means of a plate-cone rotary viscometer (6 mm/2 cone) at 250 s.sup.1. This too shows that these pigment compositions are suitable for use in chemical toners such as suspension polymerization toners. f) Electrostatic Properties of the Toner:

(27) An important performance property of a toner is its electrostatic charging characteristics. These are affected to a greater or lesser degree by the pigments used. In order to assess the effect of the pigment on the charging characteristics of the toner, a test toner is produced and then the electrostatic chargeability of this test toner is measured by means of a Q/M meter.

(28) 5 parts of the inventive pigment composition from synthesis example 1 are incorporated homogeneously in powder form by means of a kneader into 95 parts of a toner binder (styrene acrylate: Almacryl B 1501) within 30 min. This is followed by grinding in a universal laboratory mill and then classification in a centrifugal sifter. The desired particle fraction (4-25 m) is activated with a carrier consisting of styrene-methacrylate copolymer-coated magnetite particles of size 50-200 mm (bulk density 2.62 g/cm.sup.3) (FBM 100 A, from Powder Tech). The measurement is effected with a conventional Q/M test bench. By using a sieve with a mesh size of 25 m, it is ensured that no carrier is entrained when the toner is blown out. The measurements are effected at about 50% relative air humidity and 22 C. Depending on the activation time, the following Q/M values are measured (table 5).

(29) TABLE-US-00005 TABLE 5 Triboelectrical charge in Charge C/g after activation Pigment control agent 5 min 10 min 30 min 2 h 24 h 5% synth. none 10 11 12 14 15 ex. 1 5% synth. with 2% 23 27 30 33 32 ex. 1 Bontron E 84

(30) The test results show that the pigment composition supports the negative charging of the toner resin (charge without pigment about 5 C/g), but is not too significantly dominant, and so the addition of a small amount of a charge control agent can adjust the toner charge according to the requirements. B) Use in inkjet inks: a) Coloristic properties in solvent inkjet inks:

(31) To test the coloristic properties of the pigment compositions of the invention, first of all, a pigment concentrate (3.5% pigment, 1.75% dispersing additive (Disperbye 2163), 9.5% VC/VAc copolymer, 85% solvent mixture (cyclohexanone/butoxyethyl acetate=5/95)) was produced. For this purpose, the constituents are dispersed with 2 mm glass beads in a paint shaker for 120 min.

(32) 1.6 g of the pigment concentrate thus produced are diluted with 24 g of a 25% binder solution and mixed homogeneously. The pigment concentrate thus produced is applied to a flexible PVC film (150 m) with a no. 5 manual coater (wet film thickness 50 m).

(33) In the analysis with the colorimeter, the pigment composition of the invention is used as reference (type) and the commercially available naphthol pigments PR 147 and PR 184 are analyzed against this type.

(34) Only in the case of 3.5 times the starting weight do the commercially available naphthol pigments attain similar color intensities to the pigment composition of the invention. The hue of the comparative pigments in each case is much yellower (dH=positive) and duller (dC=negative) than the pigment composition of the invention (table 6).

(35) TABLE-US-00006 TABLE 6 Color Pigment intensity Pigment conc. [%] [%] dH dC Synthesis example 1 3.5 100 0 0 PR 147 12* 105 2.12 1.37 (comparative) PR 184 12* 107 6.36 3.03 (comparative) *The pigment concentration had to be increased to 12% in order to attain comparable color intensities to synthesis example 1.