JPH064769B2 - Method for producing monoazo pigment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a monoazo pigment, and more specifically, an object thereof is to provide a yellowish red monoazo pigment useful as a coating material.

(Prior Art) Conventionally, 1- (2 ', 3'-oxynaphthoylamino)-
A monoazo pigment obtained by coupling a diazonium salt of 1-aminobenzene-4-carboxylic acid amide with 2-ethoxybenzene is known, and this monoazo pigment has three crystal forms of α, β and γ. It is also known.

Further, a method of converting the crystal form from the α modification to the γ modification is also known (see Japanese Patent Publication No. 54-32009).

(Problems to be Solved by the Invention) A known method for obtaining the γ-modified monoazo pigment is a method in which an aqueous suspension of the α-modified monoazo pigment is heat-treated at 90 to 200 ° C. Good results cannot be obtained unless the above temperature, for example, a temperature of 110 to 150 ° C. is used.

It is difficult to heat the aqueous suspension to 110 to 150 ° C. under normal pressure, and therefore, there is a problem that an expensive and complicated device is required.

Therefore, there is a demand for a method for obtaining a γ-modified monoazo pigment having good properties at normal pressure.

(Means for Solving Problems) The present inventor has completed the present invention as a result of research to solve the above-mentioned problems of the prior art.

That is, the present invention is represented by the following formula by coupling 1- (2 ', 3'-oxynaphthoylamino) -2-ethoxybenzene with a diazonium salt of 1-aminobenzene-4-carboxylic acid amide. In the method for producing a monoazo pigment, after completion of coupling, the reaction mixture is heat-treated at a temperature of 70 to 85 ° C. to convert the product from α modification to γ modification, and then filtered to obtain a filtered product. The cake as a suspension of alcoholic organic solvent 50 ~ 85 ℃
The method for producing a monoazo pigment is characterized in that crystal growth is performed by heat treatment at the temperature of.

Now, the present invention will be described in more detail. According to the detailed study by the present inventor, 1- (2 ', 3'-oxynaphthoylamino) -2-ethoxybenzene was converted into 1-aminobenzene-4-carboxylic acid. The conversion of the α-modification of the monoazo pigment obtained by coupling the diazonium salt of the amide to the γ-modification is very easy and is sufficiently performed even at a temperature of 100 ° C. or lower. Found that the grains were too fine to be used in practice and it was necessary to grow these fine crystals.

As described above, this crystal growth is 10
A temperature of 0 ° C or higher, preferably 110 to 150 ° C has been required.

In the present invention, the conversion into the γ-transformed particles and the crystal growth thereof are considered separately, and the crystal growth of the γ-transformation is performed in an organic solvent-rich state in an alcohol-based organic solvent to obtain a temperature of 100 ° C. or lower, that is, 50 The inventors have found that a temperature of 85 ° C. can be sufficiently achieved, and have solved the problem of requiring a temperature of 100 ° C. or higher in the prior art.

Therefore, according to the present invention, the conversion from α transformation to γ transformation also
In addition, the crystal growth of the γ-transformed particles can be easily carried out at a remarkably low temperature of 100 ° C., and a yellowish red monoazo pigment having very excellent physical properties as a coating material can be easily and economically provided. it can.

Diazotization of 1- (2 ', 3'-oxynaphthoylamino) -2-ethoxybenzene, 1-aminobenzene-4-carboxylic acid amide, 1-aminobenzene-4-carboxylic acid amide used in the present invention, The coupling reaction and the like are the same as in the conventionally known methods, and the monoazo pigment of the above formula can be obtained without any special conditions.

The monoazo pigment produced by the coupling is in the α modification, and the α modification is easily performed by subjecting the coupling reaction mixture or an aqueous suspension of the filter cake to a water treatment at a temperature of 70 to 85 ° C. for several hours to give a γ modification. Convert to pervert.

In the present invention, it is necessary to filter the γ-transformation into a press cake and suspend the press cake in an alcohol organic solvent. In this system, a temperature of 100 ° C. or lower, for example, 50 to 85 ° C. is sufficient. A simple crystal growth process is realized.

The alcohol-based organic solvent used is methanol,
Ethanol, propanol, butanol, ethylene glycol, ethylene glycol monomethyl, monoethyl ether and the like can be used.

The amount of these alcohol-based organic solvents used is preferably about 1,500 to 2,000 parts by weight per 100 parts by weight of the solid pigment, and in the present invention, an aqueous presscake of γ-transformation is added to the alcohol-based organic solvent. As a result of suspending,
The suspension system is a mixed system of water and alcohol, and the mixing ratio of water and alcohol is preferably alcohol-rich so that water / alcohol is 1 or less.

When the ratio of water / alcohol is 1 or more, crystallization is difficult, a high temperature of 100 ° C. or higher is required, and the crystal grains of the γ-transformation produced are not uniform, which is not preferable.

The treatment temperature is 50 to 85 ° C., preferably 60 to 85 ° C., and the stirring treatment for about 1 to 5 hours gives a γ-modified monoazo pigment having excellent properties.

(Operation / Effect) It is considered that according to the present invention as described above, the crystal growth of the monoazo pigment is possible at a temperature significantly lower than 100 ° C. for the following reason.

(1) In the prior art, when an aqueous suspension is simply used, various pH adjusters, impurities in raw materials, by-products at the time of coupling, etc. are present in this liquid, and therefore these impurities are contained. Hindered the crystal growth of the γ-transformed particles, and consequently required a high processing temperature.

(2) When an aromatic organic solvent is present in the suspension, surfactants are required, and these surfactants inhibit crystal growth as well as impurities.

(3) On the other hand, in the present invention, as a result of using the alcohol-based organic solvent having high compatibility with water, the suspension medium of the pigment is a homogeneous phase, and the existing impurities are dissolved in this homogeneous phase. In addition, since it is not necessary to use a surfactant, the crystal growth of the monoazo pigment is not hindered by impurities or surfactants, and the temperature is significantly lower than 100 ° C. at 50 to 85 ° C.
Even at a low temperature, crystal growth easily proceeds, and a monoazo pigment having a uniform particle size and excellent in various characteristics can be obtained.

Next, the present invention will be described more specifically with reference to examples.

Example 1 6.8 g of 1-aminobenzene-4-carboxylic acid amide are dissolved in 140 ml of water and 15.2 g of concentrated hydrochloric acid,
Add ice to make approximately 350 ml. To this, 3.55 g of sodium nitrite was added for diazotization, and 2 g of acetic acid and 8 g of sodium acetate were added to adjust the pH of the solution. On the other hand, 1-
15.35 g of (2 ', 3'-oxynaphthoylamino) -2-ethoxybenzene is dissolved in 400 ml of an aqueous solution containing 4.0 g of caustic soda. This solution is dropped into the above diazonium salt solution for about 1 hour to carry out a coupling reaction. After stirring for 1 hour, the temperature rise was started, and the mixture was stirred at 80 to 85 ° C for 1 hour to convert the produced monoazo pigment into the γ-modification.

This was washed with filtered water to obtain a filtered cake having a solid content of 25% by weight.

94 g of this filtered cake was added to 500 ml of methanol and heat-treated with stirring for 3 hours at 67.5 ° C., and the filtered cake was washed with water and dried to obtain 23.0 g of a clear yellowish red γ-modified monoazo pigment. .

Example 2 The same amount of ethanol was used instead of methanol in Example 1, and the crystal growth treatment was performed at 80 ° C. for 2 hours, and excellent results were obtained as in Example 1.

Example 3 The same amount of isopropyl alcohol was used instead of methanol in Example 1, and the crystal growth treatment was performed at 80 ° C. for 1 hour, and excellent results were obtained as in Example 1.

Claims (1)

[Claims] 1. 1- (2 ', 3'-oxynaphthoylamino) -2-ethoxybenzene, 1-aminobenzene-
In a method for producing a monoazo pigment represented by the following formula by coupling a diazonium salt of 4-carboxylic acid amide, the reaction mixture is adjusted to 70 to 8 after the coupling is completed.
The product is converted from α modification to γ modification by heat treatment at a temperature of 5 ° C., and then the filtration cake obtained by filtration is heated at a temperature of 50 to 85 ° C. as a suspension of an alcoholic organic solvent. A method for producing the above-mentioned monoazo pigment, which comprises performing a crystal growth by treating.