CS237685B1 - Process for preparing pigment mixtures - Google Patents

Abstract

A method for preparing pigment mixtures in which at least one pigment is prepared by azocoupling. The essence of the invention lies in the fact that the coupling takes place in the presence of a fine aqueous dispersion of a second pigment, the amount of which is such that the desired shade of the pigment mixture is achieved.

Description

The present invention relates to a novel process for preparing blended pigments exhibiting high and stable homogeneity, optimum texture, spreading and brilliance.

With the prior art methods, the desired shades are achieved by mixing solid powders in mixers of various types, often after their previous grinding under dry conditions. The individual pigments can also be mixed in the form of their finely ground dispersions, whether aqueous or in the media. of paints. Organic solvents such as toluene, nitrocellulose, alkyd, linseed oil, mineral oil, dibutyl phthalate and the like are commonly used. by mixing yellow and blue pigments, brown shades by mixing orange pigment and soot, etc. Methods of simultaneous preparation of two pigments in their chemical preparation have been published, for example by azocopulation of one diazonium salt with a mixture of two passive components, naphthols or ary people. On the contrary, it is possible to proceed on the contrary that a mixture of different active components is coupled to one passive component. Methods for preparing mixed lacquers using various metals in their preparation are also known. This preparation of mixed shades is accompanied by a number of technological difficulties, which often deteriorate the resulting application properties. In the blending treatment, perfect homogeneity is not guaranteed, the individual pigments used are at different agglomeration levels, resulting in different sedimentation rates in the coating compositions. In the production of blended pigments in the prior art using, for example, two different passive components, it is difficult to determine the reaction conditions to suit the optimum of both passive components, e.g., in acidity of the environment during coupling. Of course, this procedure cannot be used where both pigments are of completely different chemical configurations, eg where the second pigment is a derivative

237 68S

phthalocyanine, anthraquinone, carbon black, and the like.

These disadvantages are overcome by a process for the preparation of pigment mixtures in which at least one component is an unmetallized azopigmeht prepared by the azocopulation of the present invention, characterized in that the coupling process in which the unmetallized azo-. The pigment is formed in the presence of an aqueous dispersion of a second pigment, the amount of which is such as to achieve the desired shade of the pigment mixture. In the process according to the invention, one pigment is pre-milled in the presence of surfactants to a fine aqueous dispersion. 1 µm, as a coupling medium to prepare a second pigment. The preparation process can alternatively be modified in various ways. The aqueous dispersion of the first pigment may be added to the solution or dispersion of the passive coupling component, or vice versa, and the passive component may be prepared in an aqueous pigment dispersion. In some cases, the aqueous pigment dispersion can be added to the diazonium salt solution or vice versa. After the coupling, a mixed pigment of the desired shade is obtained, which is completely homogeneous compared to the preparation by the mixing processes and exhibits both a soft texture with easy dispersibility and increased spreading and braziness.

In order that the invention may be more fully understood, the following examples are provided.

Example 1.

19.8 g of 3-nitro-4-toluidine are stirred overnight in 35 ml of 9 mol / l hydrochloric acid with the addition of 0.8 g of carboraffin. The next day, 100 g of ice are added and diazotized by the sequential addition of 52 ml of 2.5 mol / l sodium nitrite solution. After diazotization, the solution was spiked. Meanwhile, the suspension

23.4 g of acetoacetanilide in 700 ml of water add a copper phthalocyanine dispersion (C.I.Pigm.Blue 15 µl) finely ground in water with the addition of 3 g of anioactive dispersant to particles less than 1 µm. 4 ml of 10 mol / l sodium hydroxide solution are added, the pH is adjusted to 6.0 by addition of acetic acid and the temperature is adjusted to 35 [deg.] C. At this temperature, a diazotized 3-nitro solution is added to the blue acetoacetanilide suspension. -4-toluidene. The pH is maintained by the gradual addition of sodium hydroxide solution in the range

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237 685 to 6o Addition of the diazonium salt flows for 30 to 60 minutes After the coupling is complete, the reaction mixture is heated to 6 ° C, the dye is filtered off, washed with warm water and dried. 48 g of green pigment are obtained. g of copper phthalocyanine (Cl POBol5il) with 36 g of pigment (Cl P®Y _O 1) considerably brighter with a spread rate of 351% to 40% higher when used in both oil paint and alkyd lacquer The texture of this new pigment is very soft, the spreading rate in the binder, as is the case with the pigment mixed from powders. It does not settle in the alkyd varnish even after standing for a long time, while in the varnish prepared by yellow and blue stirring, over time the sediment develops a blue pigment and homogeneity must be restored by thoroughly re-mixing »»

Example

15.6 g of 4-aminobenzamide are diazotized after dissolution in 70 ml of water and 50 ml of 5 mol / l hydrochloric acid solution with 40 ml of 2.5 mol / l sodium nitrite solution. After the addition of the carboraffin and stirring, the diaza solution is thawed. »Meanwhile, a dispersion of 9.4 g of 3-hydroxy-2- (2-methylbenzyl) carbamide and 0.5 g of copper phthalocyanine in 900 ml of water is prepared, ground with 5 g. a non-ionic dispersant to a particle size below 1 µm. 8 g of sodium bicarbonate are added to the dispersion, the pH is adjusted to 9-10.5 and the diazonium salt solution is added at 20-30 ° C. The pH is maintained between 9-10.5 by the addition of sodium hydroxide solution. »the pigment is filtered, washed and dried» »to obtain a homogeneous hue pigment, which cannot be prepared in an equally homogeneous state by hand-blending the respective powder pigments (Cl P®R®210 and Cl P®B®15il) <>

Example 3.

AND

The diaza solution is obtained by diazotizing 19.8 g of 3-nitro-4-toluidine as in Example 1. Meanwhile, 19.4 g of 2-naphthol are dissolved in 170 ml of water with 15 ml of 10 mol / l sodium hydroxide solution with the addition of 1 g of turkish red oil After dissolution, 1 g of diatomaceous earth is added and the solution is thickened into a dispersion of 40 g of Cl Pigment Red 210 pre-milled with 12 g of non-ionic dispersant in 200 ml of water to particles smaller than 1 µm. Drip into a red suspension of 2-naphthol at 20-25 ° C Alkalinity with stirring for 30 minutes

237 885 slowly decreases from pH 12 to pH 8 during the coupling process. · Finally, it is kept above pH 8 by the addition of sodium hydroxide solution®. The reaction mixture is heated to 65 ° C after coupling, the pigment is filtered off and dried. very soft grain® Pigment was judged to be considerably brighter and 40% more abundant after application in oil paint against the mixed pigment obtained by grinding Cl P®R®210 and 40 g ClP®R®3

Example 4®

A diaza solution was obtained by diazotization of 19.8 g of 3-nitro-4-toluidine as in Example 1. A solution of 19.4 g of 2-naphthol in water was prepared with the addition of sodium hydroxide as in Example 3. The naphtholate solution 3e was impregnated with stirring 10 g of sodium bicarbonate in 200 ml of water to which a dispersion of 4 g of finely ground carbon black in water was added with the addition of a dispersant®. Coupling into the black 2-naphthol suspension was carried out by admitting a diaza solution as in Example 3o. dries®

Example 5®

To a solution of diaza prepared from 13.6 g of 4-aminobenzamide as in Example 2 is added a dispersion prepared by grinding 40 g of copper phthalocyanine (Cl PB®15) in water with the addition of 15 g of a non-ionic dispersant. slowly solution 31.0 g of 3-hydroxy-2 (N- (2-methoxyphenyl) carbamide dissolved in 600 ml of water at 90 ° C with the addition of 22 ml of 10 mol / l sodium hydroxide solution) g of resin soap, after stirring 6 g of calcium chloride and the reaction mixture is boiled for 1 hour.The pigment is filtered, washed and dried® It has a blue-violet tint, soft texture and excellent stability in organic solvents®

Claims (1)

A process for the preparation of pigment mixtures wherein at least one component is an unmetallized azopigment prepared by azo copulation, characterized in that the coupling in which the unmetallized azopfement is produced is carried out in the presence of an aqueous pigment dispersion of a second amount sufficient to achieve the desired shade of pigment mixture.