JPS59122551A - Preparation of quinacridone pigment having gamma-crystal phase - Google Patents

Abstract

PURPOSE:To prepare a high-purity quinacridone pigment having gamma-crystal phase in the form of fine powder, economically, by dissolving crude quinacridone in a mixed solvent comprising cyclic N-alkylamide compound, etc. in the presence of an alkaline hydroxide, and neutralizing the solution with a mineral acid. CONSTITUTION:A quinacridone pigment having gamma-crystal phase is prepared by dissolving (A) crude quinacridone having arbitrary crystal phase in (B) a mixed solvent composed of (i) a cyclic N-alkylamide compound (e.g. N-methyl-2-pyrrolidone, N-methyl-epsilon-caprolactam, etc.) and (ii) an alcohol having a solubility parameter of 11-13 at a weight ratio of preferably (50-80):(50-20) in the presence of (C) an alkaline hydroxide such an NaOH, KOH, etc. (preferably 1-3mol per 1mol of the crude quinacridone), and neutralizing the solution with mineral acid or mineral acid diluted with the above N-alkylamide compound and/or alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing -, γ-crystalline phase quinacridone pigments. More specifically, crude quinacridone having any crystalline phase is dissolved in a mixed solvent of a cyclic N-alkylamide compound and an alcohol in the presence of an alkali hydroxide, and this is dissolved in a mineral acid or a cyclic N-alkylamide compound. and/or neutralization with a mineral acid diluted with an alcohol.This invention relates to a method for producing a fine particle γ-crystal phase quinacridone pigment from C.

Quinacridone has α-type and β-type due to differences in crystal structure.
It is known that there are atypical forms such as the γ-type and the γ-type. All of these are bright red or reddish-purple organic pigments with excellent heat resistance, weather resistance, and solvent resistance.
Widely used for inks and resin coloring.

The following methods are known as conventional methods for producing .gamma.-crystal phase quinacridone.

(1) A method in which milling with an inorganic salt is carried out in a solvent such as dimethylformamide to simultaneously perform grinding and adjustment of the crystal form (Japanese Patent Publication No. 13833/1983).

(2) A method of changing the crystal form to the γ-form by treatment in a specific solvent. For example, a method of boiling with dimethylformamide containing 5 to 10% water (Japanese Patent Publication No. 39-9271), a method of boiling in dimethyl sulfoxide (Japanese Patent Publication No. 1973-9271),
0-6098).

A method of boiling with potassium hydroxide in methanol (Japanese Patent Publication No. 39-20073) has been proposed.

(3) A method in which a concentrated sulfuric acid solution of quinacridone is dropped into a polar solvent such as alcohol to precipitate quinacridone (Japanese Patent Publication No. 16343/1986, 17149/1982)
Publication No.).

(4) Dissolving quinacridone as an alkali metal salt in a dimethyl sulfoxide solvent in the presence of an alkali and water,
A method of adding a mineral acid diluted with dimethylsulfoquinide or diluting it with sulfuric acidic alcohol (Japanese Unexamined Patent Publication Nos. 54-132625 and 54-130622).

However, each of the conventionally proposed methods described above has the following problems. That is, the method (1) requires long processing steps and is complicated, and the method (2) cannot make the particle size small enough to be used as a pigment. In method (3), there is a risk of partial sulfonation because it is dissolved in concentrated sulfuric acid. In the method (4), fine particles of quinacridone can be obtained. However, since a large amount of expensive solvent is used, it is necessary to recover it.

This is accompanied by an increase in manufacturing costs due to the expense for solvent recovery and poor recovery rate.

Taking these points into consideration, the present inventors have intensively investigated an economically advantageous method for producing γ-crystal phase quinacridone having a sufficiently small particle size and high purity from crude quinacridone. As a result, quinacridone completely dissolves in a mixed solvent of a cyclic N-alkylamide compound and an alcohol in the presence of an alkali, so insoluble dust and impurities can also be removed by passing this solution once. The quinacridone solution thus obtained is treated with mineral acid or the cyclic N
- It is possible to obtain γ-crystal phase quinacridone with a sufficiently small particle size and high purity by neutralizing it with an alkylamide compound and/or a mineral acid diluted with an alcohol; During the separation process, the salts produced can be removed at the same time, allowing the solvent system to be recycled.

It was discovered that the cost of solvent recovery can be significantly reduced9.
We have arrived at the present invention.

That is, in the present invention, crude quinacridone is dissolved in a mixed solvent of a cyclic N-alkylamide compound and an alcohol having a solubility parameter in the range of 11 to ]-3 in the presence of an alkali hydroxide, and this is dissolved in a mineral acid. Specifically, the present invention relates to a method for producing a γ-crystalline phase quinacrytone pigment, which is characterized in that the pigment is neutralized with a mineral acid diluted with the cyclic N-alkylamide compound and/or an alcohol.

Next, the present invention will be explained in detail.

The crude quinacridone used in the present invention can have any crystalline phase, and the size of the particles does not matter.

As the solvent, a mixed solvent system of a cyclic tri-J-alkylamide compound and alcohols is used. As the cyclic N-alkylamide compound, N-methyl-2-pyrrolidone, N-ethyl-2
-pyrrolidone, N-methyl-ε-caprolactam, and alcohols with a solubility parameter of 11
-13 things.

,! =<K, ethanol, propatool, and those that can dissolve alkali hydroxide to some extent, such as ethylene glycol monomethyl ether □, are suitable. N- in mixed solvent
The suitable ratio of the alkylamide compound to the alcohol is 50 to 80:50 to 2o. When the amount of alcohol exceeds this range, the solubility of quinacridone decreases and at the same time, β-
Types become mixed. However, if the alcohol content is low, the solubility of the alkali hydroxide will deteriorate, making it difficult to obtain the desired pigment. Note that when water is added to this mixed solvent, quinacridone other than the γ-crystalline phase is mixed in.

This is not preferable because the particle size also increases.

As the alkali hydroxide for forming the alkali metal salt of quinacridone, an alkali metal hydroxide such as aluminum hydroxide or potassium hydroxide is used. The appropriate amount to be used is 1 to 3 moles per mole of crude quinacridone. Further, when dissolving this alkali hydroxide in a solvent, it may be added directly to the mixed solvent, but it is preferable to dissolve it in alcohol for rapid dissolution.

In order to quickly dissolve quinacridone as its alkali metal salt in a solvent, it is better to add crude quinacridone to a solvent in which an alkali hydroxide has been dissolved, and further heat and stir. In this case, it is difficult to carry out the process under an inert gas atmosphere to prevent oxidation of the quinacridone.

A solution in which quinacridone is dissolved does not precipitate crystals even at room temperature and remains a homogeneous solution.

Pour this solution through a glass filter, etc., while hot or after cooling.
- It is possible to remove dust and insoluble impurities by filtration.

The solution of quinacridone thus obtained is neutralized by mineralization to precipitate quinacridone. Mineral acids used at this time include sulfuric acid and phosphoric acid.

Sulfuric acid is particularly preferred.

The mineral acid may be used alone or diluted with the cyclic N-alkylamide compound or/and alcohol. Also, neutralization can be done by adding quinacridone solution to the acid.

Conversely, it can also be carried out by adding an acid to the quinacridone solution. In particular, the ability to add acid later is a major advantage in terms of equipment. Further, by adjusting the temperature during acid neutralization, the size of the precipitated quinacridone particles can be changed. For example, if the neutralization temperature is around 10°C, the particles will be around 0.1μ, and if the neutralization temperature is around 30°C, the particles will be around 0.1μ.
Since the neutralization temperature is about 3 to 0.5 μ, it is preferable to maintain the neutralization temperature at 30° C. or lower.

Quinacridone can be obtained by separating the silage-like solution after acid neutralization by filtration, and at the same time, the salt produced by neutralization can also be separated. For this reason, the liquid is in a state where it contains almost no salt, acid, or alkali;
It becomes possible to reuse it. This has a great economical effect as it can reduce the cost of solvent recovery and the like.

Quinacridone is separated from the slurry after acid neutralization by a method such as f+ filtration, and by thoroughly washing it with water to remove salts etc., it is easy to obtain quinacridone with a small particle size and high purity in the γ-crystalline phase. can be obtained. The particle size thus obtained is small.

And the highly pure γ-crystalline quinacridone is superior to pigments.
By using the described method for producing pigments according to the present invention, it is possible to not only produce pigments with excellent performance, but also to have the following advantages compared to the conventional method for producing γ-crystalline phase quinacrytone pigments, which makes it suitable for industrial use. be advantageous to That is, (1) since a non-aqueous solvent system is used, quinacridone is precipitated by acid neutralization, and the salt produced is also precipitated at the same time. These are easily separated, and the solvent after separation becomes a state containing almost no salt, acid, or alkali, and can be reused as is. (2) Acid neutralization may be carried out by bathing quinacridone in acid or, conversely, by adding acid to the solution of quinacridone. - In particular, being able to use the latter method is a great advantage for the device. (3) The crude quinacridone serving as -1 may have the shape of
Just to adjust the temperature during acid neutralization.

The particle size of the quinacridone produced can be controlled, and pigments for a wide range of uses can be produced using the same equipment.

Next, Examples and Comparative Examples of the present invention will be described.

1000y of ethanol was placed in a 500mp flask, and 5.02ml of sodium hydroxide was first dissolved therein.

Add 200g of N-methyl-2-pyrrolidone to this.

An alkaline mixed solvent was used. Crude quinacridone 202 having a particle size of about 5 μm was added to this, and the mixture was heated and stirred at 80° C. for 2 hours under a )t12 gas flow. At this time, the liquid in the vessel was in a dark blue solution state. After cooling.

The mixture was filtered through an A-4 glass filter to remove a small amount of insoluble matter. 7. Transfer the [No] solution to the [t] flask.

It was further cooled to 10°C. On the other hand, Tsukuda t1￥Q 4, 5
P i (': N-Methyl-2-pyrrolidone 009 and ethanol 502 diluted solvent mixture was heated at 10°C in advance.
Keep it. Next, this acidic mixed solvent was added to the quinacridone solution at a pressure of 1·η.

The precipitate was collected using a G-5 glass filter, thoroughly washed with water using a centrifugal separator, and then dried at 60°C for 24 hours.

The obtained quinacridone was a red powder, and when X-ray diffraction was performed, it was found that at -20 it was 6.4°, 13', 7°, 26
．． Strong peak at 3°, 16.8°, 20.3°,
It showed a weak peak at 23.6°, which matched the analytical pattern of γ-crystal phase quinacridone. When the particle state of this red powder was examined using an ME microscope, it was found that the powder was composed of extremely fine particles with a particle diameter of approximately 0.1 μm. Furthermore, in a coating test using this quinacridone powder, it was confirmed that it exhibited excellent tinting strength and clear color tone.

Examples 2-5. Comparative Example 1.2 The mixed solvent system used to dissolve quinacridone in Example 1 was changed as shown in Table 1, and the same operations were performed. The results are shown in Example Nj in the same Table 1. As shown, it is a quinacridone with a very fine γ-crystalline phase, and it was confirmed in the coating film test that it exhibited excellent tinting power and clear color tone.

As shown in Comparative Example 1.2, the desired quinacridone could not be obtained when the ethanol ratio in the mixed composition of N-methyl-2-pyrrolidone and ethanol was 50% or more and less than 0%.

Table 1 Comparative Example 3 The same operation as in Example 1 was carried out except that 8 g of water was further added to the mixed solution 3001 in which quinacridone was dissolved. As a result, the solubility of quinacridone was significantly reduced, and the obtained quinacridone did not exhibit a pure γ-type crystal form, and the particle size of the quinacridone was close to 1 μ.

Examples 6 to 9 The same operations as in Example 1 were performed except that the neutralization method was changed as shown in Table 2. As a result, very fine γ-crystal phase quinacridone was obtained in all cases, and it was confirmed that the coating film test also showed excellent tinting power and clear color tone.

Table 2 Examples 10 to 12 The same operations as in Example 1 were performed except that the temperature during acid neutralization was changed as shown in Table 3. the result.

If the temperature is low (below 10℃), very fine γ-
Crystal phase quinacritone was obtained, and it was confirmed in the coating film test that it exhibited clear color tone with excellent transparency and tinting strength. Also, when the temperature is high (approximately 30℃), fine γ
- Quinacridone in a crystalline phase was obtained, and it was confirmed that it exhibited a clear color tone with excellent hiding properties in the coating film test.

Table 3 Example 13 After obtaining a quinacridone pigment in exactly the same manner as in Example 1, divide the l-1 solution into a ratio of 2:1, add 5.0 g of sodium hydroxide in small pieces to the larger portion, and heat for 1 hour. Stir to dissolve. This was transferred to a 50' Oml flask, 20y of crude quinacridone was added thereto, and heated and stirred at 80 to 90°C for 2 hours under N2 flow, followed by the same treatment as in the example. For acid neutralization, 4.5% of sulfuric acid was added to the remainder of the J-J solution. In this way, a quinacridone pigment was obtained and further (
This was repeated. The quinacridone obtained by reusing the mixed solution in this way is all quinacridone with a fine r-crystalline phase, and it was confirmed that it exhibited excellent coloring power and clear color tone in the coating film test. .

Patent applicant: Ube Industries Co., Ltd.

Claims (5)

[Claims] (1) Crude quinacridone is dissolved in a mixed solvent of a cyclic N-alkylamide compound and an alcohol having a solubility parameter in the range of 11 to 13 in the presence of alkali hydroxide, and this is dissolved in a mineral acid or A method for producing a γ-crystal phase quinacridone pigment, which comprises neutralizing with a mineral acid diluted with an N-alkylamide compound or/and an alcohol. (2) Cyclic N-alkylamide compound or N-methyl-2
-Pyrrolide/, IJ-ethyl-2-pyrrolidone, N-methyl-ε-caprolactam Claim (1)
A method for producing a γ-crystalline phase quinacridone pigment as described in Section 1. (3) The γ-crystal phase quinacridone pigment according to claim (1), wherein the alkali hydroxide is sodium hydroxide or potassium hydroxide, and the amount used is 1 to 3 mol per 1 mol of crude quinacridone. manufacturing method. (4) Claims in which the mineral acid is sulfuric acid (
A method for producing the γ-crystal phase quinacridone pigment described in section 1). (5) The weight ratio of the N-alkylamide compound and the alcohol having a solubility parameter in the range of 11 to 13 is 50
80: The method for producing a γ-crystal phase quinacridone pigment according to claim (1), wherein the mixed solvent is 50 to 20.