JPH0429707B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a simple method for producing a pigmented quinacridone solid solution pigment.

U.S. patent regarding solid solution formation of pigments by combining various quinacridone derivatives
3160510 and 3298847, and is already a known fact. This solid solution technology provides a powerful means for expanding the color gamut of quinacridone pigments and improving weather resistance and other properties, and is a technology that is expected to continue to develop further. Its production requires a large amount of sulfuric acid, it is relatively difficult to arbitrarily control the size of pigment particles, and when solid-type pigments with large particle sizes are required, solid solution formation is difficult to proceed sufficiently. It has the following drawbacks, and overall it lacks ease of operation.

In order to improve these shortcomings, the present inventors have conducted various studies on methods for producing solid solution pigments that are easy to operate and allow for arbitrary control of particle size. It was confirmed that many quinacridone derivatives are dissolved in solvents in the presence of caustic alkali, and the inventors discovered that the quinacridone derivatives can be applied to the production of pigments, leading to the present invention. That is, in the present invention, solutions of various quinacridone derivatives in polar organic solvents such as dimethyl sulfoxide are mixed in arbitrary ratios to obtain a homogeneous mixed solution, and then each crystal system is prepared by neutralizing and reprecipitating with an acid. By producing a crystal system in a solid solution form that is clearly different from the mixture system, and adjusting the temperature during neutralization and reprecipitation,
To provide a method for producing a solid solution pigment that can arbitrarily control particles in the range of 0.05 to 0.25 microns, is simple, has a short treatment process, does not require a large amount of waste acid treatment, and is advantageous in terms of equipment and cost. It is.

That is, the present invention involves dissolving and mixing various quinacridone derivatives in arbitrary ratios of two or more in a polar organic solvent such as dimethyl sulfoxide in the presence of caustic alkali, and then neutralizing and re-mixing with an acid such as sulfuric acid. It is characterized by forming a solid solution by precipitation, and various quinacridone derivatives are used for this purpose.
It is assumed that it forms a salt with a caustic alkali and completely dissolves in a polar organic solvent such as dimethyl sulfoxide. Examples of such types of quinacridone include 2,4-dimethylquinacridone, 4,11-dichloroquinacridone, and their 6,13-dihydroquinacridone, other than unsubstituted quinacridone. Derivatives having substituents that are free from oxidation, such as alkyl groups other than methyl and halogens other than chlorine, can be similarly used. Regarding the combination of two or more of these types, there is no particularly defined composition range for forming a solid solution, and it can be done in any ratio, and by appropriately adjusting the neutralization and reprecipitation conditions, pigment The size of the particles
It can be manufactured arbitrarily within the range of 0.05 to 0.25 microns. In manufacturing such solid solution pigments, it is assumed that the combination of crude pigments used as raw materials will completely dissolve in the solvent by forming caustic alkali and salt. Examples include dimethyl sulfoxide, dimethylimidazolidinone, N-methylpyrrolidone, etc.
Dimethyl sulfoxide is good in terms of solubility, solvent recovery, etc. These solvents are difficult to dissolve completely in a completely non-aqueous state, but by mixing a small amount of water, solubility increases and complete dissolution becomes easier. However, when the water content exceeds 20%, the solubility decreases again and complete dissolution is no longer achieved. A water content of about 10 to 15% is usually most effective. This is because caustic alkali has poor solubility in these solvents in a completely non-aqueous state, hindering salt formation with quinacridone or quinacridone derivatives. As the caustic alkali used in this dissolution operation, caustic soda and caustic potash are preferably used. This is because alkalis other than these are inferior in solubility.

The obtained mixed solution consisting of a combination of various quinacridone derivatives is converted into a solid solution pigment by setting neutralization and reprecipitation conditions according to the intended use of the pigment. On this occasion,
As the acids used for neutralization, sulfuric acid, hydrochloric acid, acetic acid, etc. can be used, but sulfuric acid is the best when considering the weather resistance of the pigment obtained.

The neutralization and reprecipitation conditions are as follows:
Since it greatly affects the particle size, it is necessary to carry out neutralization and reprecipitation while controlling the temperature to obtain the desired particle size.
~0.25 micron, 0.15-0.2 micron at 40℃, 20
Since the particle size varies from 0.1 to 0.15 microns at 0.degree. C. levels and from 0.05 to 0.1 microns at 0.degree. C. levels, the desired particle size may be selected within this range.

The precipitate slurry obtained by neutralization and reprecipitation is filtered and washed by normal means, and if necessary, surface treatment is applied to produce a product with excellent coloring strength, clarity, heat resistance,
A finely divided solid solution pigment with high light resistance is obtained.

Formation of a solid solution can be easily confirmed by X-ray diffraction analysis of the resulting product pigment. In the case of a simple mixture, the X-ray diffraction diagram will be a pattern equivalent to the superposition of the unique X-ray diffraction patterns of each, and the peak intensity will be proportional to the blending ratio, but it will not be possible to form a solid solution. In such cases, the difference between the two can be clearly distinguished by showing a diffraction pattern that has unique features of the newly formed crystal.

In order to clarify these facts, explanation will be given based on drawings. In Figure 1, 1 is γ-quinacridone, 2 is 2,9 dimethylquinacridone, and 3 is γ-
A mixture of type quinacridone and 2,9-dimethylquinacridone in a 6:4 (weight ratio), 4 is an embodiment of the present invention, unsubstituted quinacridone and 2,9-dimethylquinacridone.
2 shows characteristic patterns of X-ray diffraction diagrams of solid solutions with -dimethylquinacridone.

In addition, in Figure 2, 1 is γ-type quinacridone, 2 is 4,11-dichloroquinacridone, 3 is a mixture of γ-type quinacridone and 4,11-dichloroquinacridone at a ratio of 6:4 (weight ratio), and 4 is another embodiment of the present invention, unsubstituted quinacridone and 4,11-
3 shows characteristic patterns of X-ray diffraction diagrams of solid solutions with dichloroquinacridone. The X-ray diffraction angle 2θ in each drawing was measured using a CuKdNi filter.

From these facts, it is clear that all the solid solutions of the present invention exhibit novel patterns.

The solid solution pigment formation method according to the present invention has the following features compared to known methods, and is extremely advantageous from an industrial perspective.

These include: Since it dissolves uniformly in a polar organic solvent such as dimethyl sulfoxide, it is easy to remove foreign substances.

The crystal form of the crude pigment used as a raw material does not matter.

The melting operation can be completed in a short time without requiring high temperatures.

Particle size can be controlled arbitrarily by controlling the time of neutralization and reprecipitation.

Since there is no contamination of the solvent system with anything other than water, the solvent can be easily recovered and reused.

The entire process is extremely simple and short, so
Productivity is good regardless of the scale.

There are no particularly defined compositional ranges required to form a solid solution, and any combinations and ratios can be implemented.

etc.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 10.5 parts of crude unsubstituted quinacridone and crude 2,9-
Weigh out 4.5 parts of dimethyl quinacridone and 150 parts of dimethyl sulfoxide containing 10% water into a flask and add 7.5 parts of caustic potassium with stirring to form a homogeneous slurry.

When stirring is continued at room temperature, the system gradually turns blue-purple, changing from a slurry to a deep blue-purple solution. After stirring for about 1.5 hours, remove trace amounts of insoluble matter using a filter if necessary, and add 5 parts of sulfuric acid while cooling and keeping warm at 0°C.
Aqueous sulfuric acid diluted with 10 parts of H ₂ O was slowly added dropwise from the dropping funnel over a period of about 5 minutes. As the neutralization progresses, the system becomes a slurry again and rapidly thickens, so the stirring speed is increased as the viscosity increases. Once the dropwise addition is complete, continue stirring to maintain a sufficiently homogeneous slurry and age for 1 hour, then dilute with 150 parts of water to lower the viscosity of the slurry, and pass through a filter. The obtained cake-like material is re-dispersed and washed with 1 part of water in a dispersing mixer, and then filtered again. This operation was repeated three times before and after, and the mixture was dried in a hot air dryer at 60° C. for 12 hours to obtain the desired solid solution pigment with a recovery rate close to quantitative.

Confirmation that this substance has formed a solid solution is performed by X-ray diffraction. That is, while the γ-type crystal phase, a mixture of unsubstituted quinacridone and 2,9-dimethylquinacridone has their respective X-ray diffraction patterns superimposed, the product of this example has a 2θ angle of 5.95°,
Large intensity peaks at 13.6°, 26.3° and 27.4°,
A weakly intense peak was observed at 12.0°, clearly indicating that a different type of crystal form was formed, indicating solid solution formation (see Figure 1).

As a result of observing the particle state using an electron microscope photograph (20,000x magnification), it was confirmed that the particles were fine particles with an average distribution of around 0.05 microns, and the coloring power with excellent transparency was confirmed in the coating test. The results of the accelerated weathering test also confirmed that the solid solution product had a lower degree of deterioration and better light resistance than a mixed toned product of the same composition.

Example 2 The treatment was carried out under the same conditions as in Example 1 except that 2,9-dimethylquinacridone was replaced with 4,11-dichloroquinacridone, and a very yellowish red pigment powder was almost quantitatively produced. Obtained. The formation of a solid solution was confirmed using an X-ray diffraction chart as in Example 1, which showed strong peaks at 6.1°, 13.1°, and 26.5° and moderate peaks at 12.7 and 24° at 2θ. It was confirmed that, while a simple toned mixture shows a diffraction diagram of a superposition of unique patterns, a different type of crystal form clearly indicating solid solution formation was produced (see Fig. 2).

Observation results using an electron microscope (20,000 times magnification) showed that the particle size distribution was extremely narrow on the order of 0.05 microns, and the accelerated light fastness test results were also extremely good compared to the toned mixture.

[Brief explanation of drawings]

FIGS. 1 and 2 show an X-ray diffraction diagram of a conventionally known quinacridone and an X-ray diffraction diagram of a solid solution obtained in one embodiment of the present invention. In all measurements, the X-ray diffraction angle 2θ was measured using a CuKαNi filter.

Claims (1)

[Claims] 1. A solid solution solution characterized by dissolving a mixture of crude unsubstituted quinacridone and a quinacridone compound in an aprotic polar organic solvent in the presence of caustic alkali, and neutralizing and reprecipitating with an acid. Method for producing quinacridone pigments. 2. The manufacturing method according to claim 1, wherein 2,9-dimethylquinacridone, 4,11-dichloroquinacridone, or a 6,13-dihydroquinacridone derivative thereof is used as the quinacridone compound. 3. The manufacturing method according to claim 1 or 2, wherein the caustic alkali is caustic soda or caustic potash. 4 Dimethyl sulfoxide, dimethylimidazolidinone or N-
The manufacturing method according to any one of claims 1 to 3, using methylpyrrolidone. 5. The manufacturing method according to any one of claims 1 to 4, in which sulfuric acid, hydrochloric acid, or acetic acid is used as the acid.