JPH0633353B2 - Method of preparing organic pigment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method for preparing an organic pigment having excellent dispersibility and dispersion stability.

Specifically, the organic pigment is dissolved in an aprotic polar solvent in the presence of caustic alkali and water, and an acid containing a nonionic surfactant is added to the organic pigment for neutralization and reprecipitation, thereby performing purification and micronization. A method for preparing an organic pigment excellent in dispersibility and dispersion stability, which is carried out at the same time, is provided.

<Prior Art> There have been many proposals as a method for modifying an organic pigment using a surfactant, but all of them have been refined and refined by a method such as crushing or re-precipitation of a crude pigment in advance. After the step of performing, the contact operation with the surfactant is performed to improve the pigment characteristics. That is, in order to carry out the operations for finer, refining and pigment property modification in two stages,
Even the pigment particles once made finer already form an aggregate at the time of the contact operation of the surfactant, and in the end, the contact of the surfactant with the primary particles becomes impossible by this method, and the resulting pigment is obtained. The modification effect of is not sufficient. further,
The whole process is long, complicated, and requires a long time, so it is not an advantageous method from the viewpoint of economy and workability.

<Problems to be Solved by the Invention> The present invention provides an effective pigment modification by simultaneously performing the refinement and purification of the crude pigment and the contact treatment of the surfactant with the primary particles in one step operation. The present invention provides a method for preparing a pigment that is easy to manufacture and has a simple process.

<Means for Solving Problems> That is, according to the present invention, one kind or two or more kinds of organic pigments are dissolved in an aprotic polar solvent in the presence of caustic alkali and water to prepare a nonionic surfactant. Is a method for preparing an organic pigment characterized by neutralizing and reprecipitating with an acid containing carboxylic acid, and then adding heteropolyacid or tannic acid, which imparts pigment performance such as dispersibility and dispersion stability at the same time as micronization and purification Is what you can do.

The present invention will be described in more detail.

The organic pigment used in the present invention is premised on forming a salt with a caustic alkali and dissolving it in an aprotic polar solvent, and it is an unsubstituted quinacridone, 2,9-dimethylquinacridone, 3 having such properties. , 10 or 4,
One or two or more kinds are appropriately selected from quinacridone type, which is 11-dichlorquinacridone type, azo type and thioindigo type.

As the aprotic polar solvent used in the present invention, dimethylsulfoxide, dimethylimidazolidinone, N-
Methyl-2-pyrrolidone and the like are available, but dimethyl sulfoxide is preferable in terms of solubility, solvent recovery, and the like. It is difficult for these solvents to completely dissolve the pigment in the completely non-aqueous state, but by mixing a little water, the solubility is increased and the complete dissolution is facilitated. However, when the water content is 20% or more, the solubility is reduced again and the water is not completely dissolved. Usually, the most effective condition is about 10 to 15% water content. This is because caustic has a poor solubility in these solvents in a completely non-aqueous state, and salt formation with a pigment is hindered. The caustic alkali used in this dissolving operation is preferably potassium hydroxide or sodium hydroxide.

The solution in which the pigment is dissolved is then subjected to neutralization reprecipitation operation with an acid containing a nonionic surfactant. As the acid used for neutralization, it is possible to use inorganic acids such as sulfuric acid and hydrochloric acid, and various organic acids, but it is preferable to use sulfuric acid, hydrochloric acid and acetic acid in consideration of the performance of the obtained organic pigment.

The nonionic surfactant used with these acids has a beneficial effect in the present invention, and is also soluble in a neutralizing acid and insoluble or poorly soluble in the solvent system after neutralization. What you have is suitable. Nonionic surfactants satisfying such conditions include polyoxyethylene alkyl ethers having an HLB of 14 or more, such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether. , Or HLB17
The above polyoxyethylene alkylphenol ethers, for example, polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether can be mentioned. These 1 type (s) or 2 or more types can be used. These nonionic surfactants effectively act to improve the fineness, dispersibility, dispersion stability, fluidity and coloring power of the pigment. Further, the viscosity of the slurry at the time of neutralization and reprecipitation is reduced to facilitate stirring, which is effective in homogenizing the reaction system. The amount of these nonionic surfactants used is more preferably 0.5 to 30% by weight, preferably 2 to 15% by weight, based on the organic pigment used.

In this neutralization reprecipitation operation, the temperature has a large effect on the particle size, so it is necessary to carry out the neutralization reprecipitation operation while controlling at a temperature suitable for obtaining the target particle size.

To the precipitate slurry obtained by neutralization reprecipitation, an aqueous solution of heteropolyacid or tannic acid is added, or a precipitate slurry of pigment is gradually added to the aqueous solution of heteropolyacid or tannic acid to form a nonionic interface. The activator is deposited as a water-insoluble or sparingly water-soluble substance.

The heteropolyacid is selected from phosphotungstic acid, phosphomolybdic acid, silicotungstic acid and silicomolybdic acid. When tannic acid is used, the effect of modifying fluidity is particularly great. The reaction between the nonionic surfactant and the heteropoly acid or tannic acid is not always stoichiometric, and the addition amount of the heteropoly acid or tannic acid is preferably 1 to 5% by weight with respect to the nonionic surfactant used. Especially, 2 to 4 times by weight gives more preferable results.

The pigment slurry obtained by the above operation is then repeatedly washed with water and dried by ordinary means and dried to be recovered as an organic pigment excellent in fine dispersibility and dispersion stability.

<Effects of the Invention> As is clear from the above description, the method for preparing an organic pigment of the present invention is effective in improving pigment performance such as dispersibility, dispersion stability, coloring power, and transparency at the same time as refinement and purification. Since it can be carried out efficiently and the process is simple, it is an economically and workably excellent method which is extremely advantageous industrially.

<Examples> Hereinafter, the present invention will be described with reference to Examples.

In the examples, parts and% represent parts by weight and% by weight.

Example 1 A flask equipped with a stirrer and a thermometer was charged with 300 parts of dimethyl sulfoxide containing 10% of water, 30 parts of crude unsubstituted quinacridone was added, and the mixture was stirred at room temperature,
After forming a homogeneous slurry, 13.5 parts of potassium hydroxide and 18 parts of water are added. Continue stirring for 1 hour to dissolve the pigment. After cooling to 5 ° C., 1.5 parts of polyoxyethylene lauryl ether (HLB17.3) was added to 50% sulfuric acid 23.
A sulfuric acid solution dissolved in 6 parts is slowly dropped for 30 minutes for neutralization and reprecipitation. The obtained precipitate slurry is poured into 500 parts of water in which 3.0 parts of tannic acid is dissolved and stirred for 30 minutes. The obtained pigment wet cake is 1,
After redispersing in 000 parts of water and passing again, this operation was repeated 3 times, followed by drying and pulverizing to obtain a fine brilliant deep red-purple unsubstituted quinacridone pigment.

The unsubstituted quinacridone pigment powder obtained as described above was blended with a thermosetting aminoalkyd resin varnish and dispersed in a sand grind mill to prepare a paint having a pigment content of 10%. The dispersibility of the pigment at this time is good, and even after the film formation, the pigment particles do not aggregate, the good dispersion state is maintained, and the dispersion stability is extremely excellent. It was confirmed by the electron micrograph.

Moreover, it had excellent fluidity, coloring power, and transparency, and had a clear hue.

Example 2 1.5 parts of polyoxyethylene lauryl ether was added to the same amount of polyoxyethylene stearyl ether (HLB15.
The same operation as in Example 1 was carried out except for changing to 3) to obtain an unsubstituted quinacridone pigment.

For the obtained unsubstituted quinacridone pigment, a method of using a thermosetting amino alkyd resin varnish was used as in Example 1, and on the other hand, a thermosetting acrylic resin varnish was used instead of the thermosetting amino alkyd resin varnish. By the same method as in Example 1, paint tests were conducted on two kinds of paint resin systems.

As a result, the pigment exhibited excellent dispersibility, dispersion stability, fluidity and luster in any coating system, and the coloring power was sufficiently satisfactory.

Example 3 An unsubstituted quinacridone pigment was obtained by performing the same operation as in Example 1 except that the tannic acid was changed to phosphotungstic acid.

The same paint test as in Example 2 was conducted, and it was confirmed that this pigment was extremely excellent in dispersibility, dispersion stability, tinting strength and transparency.

Example 4 A flask similar to that of Example 1 was charged with 360 parts of dimethyl sulfoxide containing 10% of water, 30 parts of crude unsubstituted quinacridone was added, and the mixture was stirred at room temperature to form a homogeneous slurry, which was then hydroxylated. 13.5 parts potassium and 22 water
Add parts. Continue stirring for 1 hour to dissolve the pigment. Then, the temperature is raised to 50 ° C., and 0.9 part of polyoxyethylene noel phenol ether (HLB18.9) is added to 50% sulfuric acid 2%.
A solution of sulfuric acid in addition to 3.6 parts was slowly and continuously added dropwise over 30 minutes to neutralize and reprecipitate.

The reprecipitated pigment slurry is poured into 500 parts of water containing 2.0 parts of tannic acid and stirring is continued for 30 minutes.
Thereafter, washing with water, repeated washing in the same manner as in Example 1, drying and pulverization were carried out to obtain a clear and fine deep red non-substituted quinacridone pigment.

When the same paint test as in Example 1 was conducted, this pigment showed excellent dispersibility, dispersion stability and fluidity, gloss and tinting strength.

Example 5 Example 4 except that 30 parts of crude unsubstituted quinacridone was replaced with the same amount of crude 2.9 dimethylquinacridone and polyoxyethylene nonylphenol ether was replaced with 0.8 parts of polyoxyethylene oleyl ether (HLB15.4). The same operation was performed to obtain a fine quinacridone pigment having a strong blue tint.

As a result of a paint test conducted in the same manner as in Example 1, this pigment was found to have excellent dispersibility, dispersion stability, gloss and fluidity,
The hue was clear and the coloring power was sufficient.

Example 6 23 parts of crude unsubstituted quinacridone and CI Pigm
The same operation as in Example 4 was carried out except that 7 parts of ent Orange 36 was changed to obtain a fine dark reddish purple pigment.

The same paint test as in Example 1 was conducted to find that the pigment had dispersibility,
It was confirmed that the dispersion stability and fluidity were excellent.

Example 7 7 parts of CI Pigment Orange 36 was added to the same amount of CI Pigment Red.
Perform the same operation as in Example 6 except changing to 170,
A fine deep red-purple pigment was obtained.

According to the same paint test as in Example 1, this pigment showed dispersibility,
It was confirmed that the dispersion stability, fluidity, and coloring power were excellent.

Example 8 7 parts of CI Pigment Orange 36 was added to the same amount of CI Pigment Red.
The same operation as in Example 6 was carried out except that the amount was changed to 88 to obtain a fine deep reddish purple pigment.

As a result of a paint test by the same method as in Example 1, this pigment was excellent in dispersibility and dispersion stability, and had sufficient tinting strength.

Example 9 A red solid solution pigment was obtained in the same manner as in Example 6 except that 7 parts of CI Pigment Orange 36 was changed to the same amount of 2.9 dimethylquinacridone.

As a result of a paint test conducted in the same manner as in Example 1, the obtained pigment was excellent in dispersibility, dispersion stability, fluidity and tinting strength.

Comparative Example 1 The same operation as in Example 1 was carried out except that polyoxyethylene lauryl ether and tannic acid were removed to obtain a dark reddish-purple unsubstituted quinacridone pigment.

The same paint test as in Example 1 was conducted on this pigment,
The dispersion state of the pigment crystal particles in the obtained coating film section,
As shown in FIG. 2 as an electron micrograph, it can be seen that the pigment clearly forms many aggregates and the dispersion stability is not good. Further, this pigment had poor fluidity and poor coloring power as compared with the pigment obtained in Example 1.

Comparative Example 2 The same operation as in Example 1 was carried out except that polyoxyethylene lauryl ether was not used to obtain a dark reddish-purple unsubstituted quinacridone pigment.

Comparative Example 3 The same operation as in Example 1 was carried out except that tannic acid was removed to obtain a dark reddish purple unsubstituted quinacridone pigment.

Reference Example The pigment powders obtained in Example 1 and Comparative Examples 1 to 3 were blended with a thermosetting acrylic melamine varnish and dispersed by a sand grind mill to prepare a coating material having a pigment content of 10%. The following table shows the results of measuring the fluidity of the paint at this time with a B-type rotational viscometer.

[Brief description of drawings]

FIG. 1 is an electron micrograph (magnification: 20,000 times) showing a dispersion state of pigment crystal particles in a coating film section of the pigment obtained in one example of the present invention, and FIG. It is an electron micrograph (magnification: 20,000 times) which shows the dispersion state of the pigment crystal particle in the coating film slice of the obtained pigment.

Claims (7)

[Claims] 1. One or more organic pigments are dissolved in an aprotic polar solvent in the presence of caustic and water,
In addition to this, polyoxyethylene alkyl ethers having an HLB of 14 or more and / or HLB1 as a nonionic surfactant.
A method for preparing an organic pigment, which comprises adding an acid containing 7 or more polyoxyethylene alkylphenols for neutralization and reprecipitation, and then adding a heteropolyacid or tannic acid. 2. The method for preparing an organic pigment according to claim 1, wherein the organic pigment is a quinacridone type, an azo type or a thioindigo type. 3. A quinacridone pigment is an unsubstituted quinacridone,
2,9-dimethylquinacridone, 3,10 or 4,11
-The method for preparing an organic pigment according to claim (2), which is dichlorquinacridone. 4. The method for preparing an organic pigment according to any one of claims (1) to (3), wherein the caustic alkali is potassium hydroxide or sodium hydroxide. 5. The aprotic polar solvent is dimethyl sulfoxide, dimethylimidazolidinone, or N-methyl-2.
-A method for preparing an organic pigment according to any one of claims (1) to (4), which is pyrrolidone. 6. The method for preparing an organic pigment according to any one of claims (1) to (5), wherein the acid is sulfuric acid, hydrochloric acid or an organic acid. 7. The organic pigment according to claim 1, wherein the heteropolyacid is phosphotungstic acid, phosphomolybdic acid or silicotungstic acid, or silicomolybdic acid. Preparation method.