JP2006206759A - Method for producing diketopyrrolopyrrole pigment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a diketopyrrolopyrrole pigment by which the pigment having excellent quality can be produced with excellent productivity without requiring a pulverization medium and without requiring much time and labor such as pulverization. <P>SOLUTION: The method for producing the diketopyrrolopyrrole pigment comprises heating a diketopyrrolopyrrole crude pigment in an aprotic polar organic solvent. In the method, the aprotic polar organic solvent containing an alkali metal hydroxide in an amount of 0.1-1.5 pts. based on 100 pts. of the crude pigment expressed in terms of mass is used as the organic solvent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a diketopyrrolopyrrole pigment.

  The diketopyrrolopyrrole pigment is a heterocyclic pigment having a symmetric chromophore, and has excellent sharpness and various fastness properties including weather resistance. Examples of such diketopyrrolopyrrole pigments include C.I. I. Pigment Red 254, 255, 264, 270, 272, C.I. I. Pigment Orange 71 and 73 are known. A typical diketopyrrolopyrrole pigment includes C.I. I. Pigment Red 254.

  Conventionally, such a diketopyrrolopyrrole pigment has been produced by heating a crude pigment obtained by synthesis in an organic solvent. As the organic solvent at this time, for example, aprotic polar organic solvents such as dimethylformamide and dimethyl sulfoxide are known (Patent Document 1).

  Further, there is also known a method in which a crude pigment is added to a mixture of methanol and sulfuric acid and heated, and further heated in dimethylacetamide to form a diketopyrrolopyrrole pigment (Patent Document 2).

  Furthermore, a production method for obtaining an opaque diketopyrrolopyrrole pigment by wet grinding using a grinding medium at a temperature of 50 ° C. or lower in the presence of a base in alcohol is also known (Patent Document 3). ).

However, none of these production methods has achieved the inherent pigment performance, or it takes time-consuming operations such as dry or wet pulverization to form pigment-form particles tailored to the final application. It is difficult to say that it is a method for producing a diketopyrrolopyrrole pigment having both excellent productivity and excellent quality.
Japanese Patent Laid-Open No. 4-372632 (claims on page 2 and paragraph number 0010) WO 03 / 022847A2 (page 27 claim, page 13 lines 15-25) JP-A-1-306474 (claims on page 1 claims and page 2 lower right column bottom line to page 3 upper left column line 12)

  The present invention provides a method for producing a diketopyrrolopyrrole pigment, which does not require a pulverizing medium and does not require labor as in pulverization, and is capable of producing a pigment having excellent productivity and quality. The purpose is to provide.

  The present inventors have intensively studied a conditioning method for heating a crude pigment in an aprotic polar organic solvent so as to have suitability as a colorant. It has been found that the above problem can be solved by heating the crude pigment in the contained aprotic polar organic solvent, and the present invention has been completed.

  That is, the present invention relates to a method for producing a diketopyrrolopyrrole pigment in which a diketopyrrolopyrrole crude pigment is heated in an aprotic polar organic solvent. Provided is a method for producing a diketopyrrolopyrrole pigment characterized by using an aprotic polar organic solvent containing 0.1 to 1.5 parts of a metal hydroxide.

  The method for producing a diketopyrrolopyrrole pigment of the present invention comprises, in mass conversion, an aprotic polar organic solvent containing 0.1 to 1.5 parts of an alkali metal hydroxide with respect to 100 parts of a crude pigment, Since the pigment having high coloring power can be obtained simply by heating the crude pigment without pulverization, it is possible to produce a pigment having excellent productivity and quality.

  In the present invention, the diketopyrrolopyrrole crude pigment is heated in an aprotic polar organic solvent to obtain a pigment suitable for coloring the medium to be colored.

In the present invention, as the diketopyrrolopyrrole-based crude pigment, any of publicly known and commonly used pigments can be used. However, the diketopyrrolopyrrole crude pigment is larger than the pigment described later, and usually has a BET specific surface area of 0 to 8 m ² / g. Examples include pyrrole compounds. Such a diketopyrrolopyrrole crude pigment is produced by reacting, for example, 1 mol of a succinic diester and 2 mol of a benzonitrile in an organic solvent in the presence of a strong base such as a metal alcoholate. It can be produced by hydrolyzing the product with water or acid. A typical crude pigment is a crude pigment composed of a compound represented by the above chemical formula 1 (corresponding to CI Pigment Red 254).

  The crude pigment can be used in various forms such as dry forms such as dry powder and dry granules, and wet forms such as wet cakes and aqueous slurries. In the dry form of the crude pigment, the pH of the water in which it is immersed, and in the wet form of the crude pigment, the liquid medium containing it is neutral to weakly alkaline. It is preferable to use the alkali metal hydroxide to be described later in order to achieve the same basicity with the organic solvent as the target.

  Examples of the aprotic polar organic solvent used in the present invention include N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N-methylformamide, N, N′-dimethyl-1,3- Examples include imidazolidine, dimethyl sulfoxide, acetonitrile and the like. The aprotic polar organic solvent may be used alone or in combination of two or more. Suitable solvents are N, N-dimethylformamide and N-methylpyrrolidone because they are safer and have a suitable affinity with water, which allows crystals to grow more easily to the desired size. N-methylpyrrolidone is the most preferable at the point which can do.

  In the present invention, the amount of the aprotic polar organic solvent used is not particularly limited. For example, it is 100 to 5,000 parts in terms of mass with respect to 100 parts of the crude pigment. Since the mixture of the polar organic solvent and the following alkali metal hydroxide has a relatively low viscosity and the crude pigment can be easily heated uniformly without being pulverized, the amount is preferably 500 to 2,000 parts.

  Alkali metal hydroxides are used to increase the basicity of aprotic polar organic solvents. Examples of the alkali metal hydroxide used in the present invention include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like. This alkali metal hydroxide can be used in any form such as a simple substance or an aqueous solution. The deliquescent alkali metal hydroxide usually contains a small amount of water.

  That is, the alkali metal hydroxide is added so that the basicity of the object to be heated is higher than before adding the alkali metal hydroxide. The usage-amount of an alkali metal hydroxide can be adjusted as needed according to conditions, such as an end use, the mass of a crude pigment, and a solvent seed | species. In the present invention, when the object to be heated is a mixture containing only a crude pigment, an aprotic polar organic solvent, and an alkali metal hydroxide, alkali metal hydroxide is used with respect to 100 parts of the crude pigment in terms of mass. The product can be heated using an aprotic polar organic solvent containing 0.1 to 1.5 parts, preferably 0.2 to 1.0 parts.

  The object to be heated contains a crude pigment, an aprotic polar organic solvent, and a substance that reacts with an alkali metal hydroxide to reduce the basicity of the aprotic polar organic solvent. To increase the amount of alkali metal hydroxide to be added to the intended basicity. When the object to be heated does not contain a substance that reacts with the alkali metal hydroxide and reduces the basicity of the aprotic polar organic solvent in the crude pigment or aprotic polar solvent For this, the above-mentioned amount of alkali metal hydroxide is added to the aprotic polar organic solvent, and then the crude pigment is heated.

  The heating of the crude pigment in the aprotic polar organic solvent containing the alkali metal hydroxide can be carried out at 70 to 140 ° C., for example, with pressure or non-pressure being selected as necessary. . The heating time is, for example, 1 to 15 hours, preferably 3 to 7 hours. The heating of the mixture containing the crude pigment, the aprotic polar organic solvent, and the alkali metal hydroxide is preferably performed with stirring so that the mixture is heated more uniformly.

  This heating may be terminated, for example, by sampling over time and setting a point where desired characteristics are obtained as an end point. As an index for determining the end point, a BET specific surface area by a nitrogen adsorption method, an X-ray diffraction peak intensity at a specific Bragg angle, or the like can be used. In this method, sampling is performed every hour at a constant heating temperature, and the specific surface area and X-ray diffraction peak intensity of the pigment for each hour are plotted on a graph, and the next and subsequent heating operations are based on this graph. The end point is controlled by the heating time. Of course, for this heating, it is desirable to set an optimum heating temperature and time according to the actual situation each time according to the content of the alkali metal hydroxide contained in the aprotic polar organic solvent.

This heating is usually performed such that the particles are relatively smaller than the crude pigment before the heating. Thus, for example, a pigment having a BET specific surface area of 10 to 16 m ² / g can be obtained by heating as described above.

  The aprotic polar organic solvent containing the alkali metal hydroxide is preferably in an anhydrous state, but may contain a small amount of water. The water content is preferably as low as possible in the range of more than 0 to 50 parts with respect to 100 parts of aprotic polar organic solvent in terms of mass.

  As described above, when alkali metal hydroxide having deliquescence is used or a water-containing aprotic polar organic solvent is used, water may be mixed into the system. If you want to reuse only the organic solvent from the aprotic polar organic solvent containing a large amount of water, it is necessary to selectively recover it by distillation, so the aprotic polar organic solvent containing a large amount of water is Thus, it takes more time to recover the solvent than a similar organic solvent having a lower water content. Therefore, it is preferable to use an aprotic polar organic solvent with as little water content as possible in view of the convenience of such solvent recovery. The same applies to the case where water is added to an anhydrous aprotic polar organic solvent.

  The inventors of the present invention not only can eliminate troublesome operations such as wet pulverization by heating with an aprotic polar organic solvent containing an alkali metal hydroxide at a specified content. It was found that the desired suitability required as a pigment can be expressed at a lower temperature and in a shorter time. According to the production method of the present invention, compared to heating in a neutral or acidic aprotic polar organic solvent, the crude pigment can be made into a pigment having higher productivity and higher coloring power. Further, there is no mixing of the pulverizing medium in advance with the pulverized medium crushed by pulverization into the pigment, and it is difficult to cause inconvenience in the end use. The present invention is the first to disclose the importance of strict control of the amount of alkali metal hydroxide that has not previously been suggested in synthesis and conditioning and end uses.

  The pigment obtained by the production method of the present invention is excellent in coloring power and can be used in the form of, for example, colored plastic molded products, colored varnishes, oil-based or water-based paints, printing inks, and lacquers. The hiding power is one of the scales for evaluating the coloring power of paints and inks. The pigment obtained by the production method of the present invention is particularly suitable for the preparation of automobile paints because it can produce a red color with high saturation and high hiding power. These can be prepared by mixing the pigment obtained by the production method of the present invention, the following resins, fillers, various additives and, if necessary, a solvent.

  The pigment obtained by the production method of the present invention is suitable as a colorant for various resins as a medium to be colored. Examples of the resin used in this case include natural or synthetic resins such as polymerization resins and condensation resins, particularly urea resins / formaldehyde resins and melamine / formaldehyde resins, alkyd resins, phenol resins, polyester resins, polyamide resins, and polyvinyl chloride. , Polyurethane, acrylic / melamine, polystyrene, cellulose ether, nitrocellulose, polyacrylate, polyacrylonitrile, polyolefin and the like. These can be used alone or as a mixture.

  As the filler, for example, various metal foils, titanium oxide, silica and the like can be used. Examples of the various additives include surfactants and preservatives, and examples of the solvent include water and various organic solvents that do not change the crystal state of the pigment.

  As a method for judging whether or not the pigment obtained by the production method of the present invention expresses excellent hiding power and high saturation accurately, quickly and highly, in the form of the pigment, for example, as described above. There are X-ray diffraction measurement, specific surface area measurement and the like. These measurements are really useful as a method for accurately judging the crystallization situation and the size of the particles.

  Moreover, it can also judge in accordance with a well-known evaluation means in the application field to apply instead of the form of a pigment. As a method for evaluating the color characteristics such as hiding power, coloring power, saturation, etc., any known evaluation means can be used. For example, a dispersion / evaluation test method using a disperser such as a Hoovermarler or a paint conditioner. There is. When the final application is paint, the resin used frequently in the same application is used as the binder resin, and the pigment, binder resin, and solvent are dispersed for a predetermined time with a paint conditioner, etc. The superior effect can be confirmed by quantifying various aptitudes with a visual or measuring instrument.

  In automotive paint applications, for example, there is a balance between high coloring power and high saturation when the covering power of the coating film is maximum, and it is required as a color characteristic. The superiority or inferiority of the hiding power can be easily identified by evaluating the coating film of the paint prepared using a disperser. According to the knowledge of the present inventors, C.I. I. In the case of Pigment Red 254, the strength is 5,500 to 6,000 at a specific Bragg angle (2θ = 28.5 ± 0.3 °) by X-ray diffraction measurement of the obtained pigment crystal, In this case, it is known that the covering power of the coating film is maximized, and commercial value is generated only in this area.

  Hereinafter, the present invention will be described in detail with reference to examples. Hereinafter, parts and% are based on mass unless otherwise specified.

  In a 1 L wide neck separable flask, 1,4-diketopyrrolo [3,4-C] pyrrole produced by a known method (the same chemical structure as CI Pigment Red 254 represented by the above formula) 50 parts of the dry crude pigment (with a sodium hydroxide) is suspended and stirred in 3.0 parts of a 10% aqueous solution of sodium hydroxide, 600 parts of N-methylpyrrolidone and 150 parts of water. Stir for hours. Cool to 60 ° C., filter at the same temperature, wash the wet cake with N-methylpyrrolidone and water, dry, C.I. I. 48.0 parts of Pigment Red 254 were obtained.

The raw dry crude pigment used for heating was obtained by drying the wet cake used in Example 4 described later after washing with filtered water, and is defined in Appendix 2 of Japanese Industrial Standard JIS Z8830-1990. The BET specific surface area was 8 m ² / g or less as measured according to “Measurement method of gas adsorption amount by one-point method”, and the immersion water was almost neutral. When this red pigment was subjected to X-ray diffraction measurement, the intensity at 2θ = 28.4 ° was 5,500. It was 13.1 m < ² > / g when the BET specific surface area of this red pigment was measured like the above.

  A water-soluble acrylic resin for baking coating and the red pigment were dispersed with a Hoovermarler until coarse particles disappeared to prepare a primary color base enamel having a pigment content of 20%. A water-soluble acrylic resin, a water-soluble melamine resin, water and a solvent were added to the base enamel and mixed well to prepare a primary color enamel having a pigment content of 5%. This was developed on a PET film, and the hiding power of the colored coating film was visually determined. As a result, the color-colored coating film containing the red pigment of Example 1 had excellent hiding power. Further, since no pulverizing medium is used, there is no inconvenience due to contamination when the crushed material is mixed in paint or the like.

Comparative Example 1
The same amount of dry crude pigment as used in Example 1, 50.0 parts, sodium hydroxide 30% aqueous solution 53.7 parts and methanol 1632.9 parts were charged with 250 ml of 2 mm diameter zirconia beads in a 3 L stainless steel bottle. It was rotated at 25 ° C. for 48 hours with a ball mill. Thereafter, the beads are separated, the pigment suspension is filtered, washed with methanol and dried at 80 ° C. in a vacuum dryer. I. 47.9 parts of Pigment Red 254 were obtained.

In this manufacturing method, a pulverizing medium such as zirconia beads is required and a long time is required for pulverization, and the productivity is inferior to the manufacturing method of Example 1. Moreover, when X-ray diffraction measurement was performed on this red pigment in the same manner as in Example 1, the intensity at 2θ = 28.3 ° was 2,500, and the crystallinity was insufficient. As in Example 1, the BET specific surface area of this red pigment was measured and found to be less than 10 m ² / g. In addition, the color-painted coating film containing the red pigment of Comparative Example 1 obtained in the same manner as in Example 1 except that the red pigment was changed was significantly inferior in hiding power as compared with that of Example 1.

Comparative Example 2
The procedure of Example 1 was repeated except that an equivalent amount of sulfuric acid was added instead of 3.0 parts of a 10% aqueous sodium hydroxide solution. I. Pigment Red 254 was obtained.

  When this red pigment was subjected to X-ray diffraction measurement in the same manner as in Example 1, the intensity at 2θ = 28.3 ° was less than 2,000, and the crystallinity was insufficient. In addition, the color-painted coating film containing the red pigment of Comparative Example 2 obtained in the same manner as in Example 1 except that the red pigment was changed, was significantly inferior in hiding power as compared with that of Example 1.

  The procedure of Example 1 was repeated using only 50.0 parts of dry crude pigment similar to that used in Example 1, 0.4 parts of sodium hydroxide 98% solids, and 300.0 parts of N-methylpyrrolidone. When repeated, C.I. I. 47.6 parts of Pigment Red 254 were obtained.

When this red pigment was subjected to X-ray diffraction measurement in the same manner as in Example 1, the intensity at 2θ = 28.3 ° was 5,850, and the crystallinity was sufficient. As in Example 1, the BET specific surface area of this red pigment was measured and found to be 13.3 m ² / g.

  In the case of the method of Example 2, the stirring time to reach the X-ray diffraction intensity of Example 1 could be made shorter than that of Example 1. Thus, it was found that the productivity of the red pigment can be further improved as compared with Example 1 when a thicker alkali metal hydroxide is used. The color-developing colored coating film containing the red pigment of Example 2 had excellent hiding power as in Example 1. Furthermore, there was no inconvenience due to contamination when the crushed media were mixed in the paint.

  The same dry crude pigment as used in Example 1, 50.0 parts, sodium hydroxide 50% aqueous solution 1.5 parts, N, N-dimethylformamide 750.0 parts, and water 37.5 parts only. The procedure of Example 1 was repeated except that the heating temperature was lowered from 120 ° C. to 100 ° C. I. 48.4 parts of Pigment Red 254 were obtained.

The red pigment was subjected to X-ray diffraction measurement in the same manner as in Example 1. As a result, the intensity at 2θ = 28.3 ° was 5,600, and the crystallinity was sufficient. As in Example 1, the BET specific surface area of this red pigment was measured and found to be 13.0 m ² / g.

The color-developing colored coating film containing the red pigment of Example 3 had excellent hiding power similar to that of Example 1. Furthermore, there was no inconvenience due to contamination when the crushed media were mixed in the paint.

Comparative Example 3
The procedure of Example 3 was repeated using only 50.0 parts of dry crude pigment similar to that used in Example 1, 1500.0 parts of N, N-dimethylformamide, and 75.0 parts of water. However, C.I. I. 48.0 parts of CI Pigment Red 254 were obtained.

The red pigment was subjected to X-ray diffraction measurement in the same manner as in Example 1. As a result, the elongation of the crystal was smaller than that of Example 3, the intensity at 2θ = 28.3 ° was 4,800, and the crystallinity was not good. It was enough. As in Example 1, the BET specific surface area of this red pigment was measured and found to be less than 9 m ² / g.

  The color-developing colored coating film containing the red pigment of Comparative Example 3 was clearly inferior in hiding power as compared with that of Example 3. There was no inconvenience due to contamination when the crushed material of the pulverizing medium was mixed in the paint or the like.

  50.0 parts of a wet cake containing the same crude pigment as used in Example 1 (crude pigment solid content 29.5%, the balance being water), 11.0 parts of a 10% aqueous sodium hydroxide solution, water When the procedure of Example 1 was repeated using only 23.3 parts, C.I. I. 48.6 parts of Pigment Red 254 were obtained by heating and stirring for only 3 hours.

The water in the raw material wet cake used for heating was almost neutral. The red pigment was subjected to X-ray diffraction measurement in the same manner as in Example 1. As a result, the intensity at 2θ = 28.3 ° was 5,620, and the crystallinity was sufficient. As in Example 1, the BET specific surface area of this red pigment was measured and found to be 13.3 m ² / g.

The color-developing colored coating film containing the red pigment of Example 4 had excellent hiding power similar to that of Example 1. Furthermore, there was no inconvenience due to contamination when the crushed media were mixed in the paint.

Claims (2)

In the method for producing a diketopyrrolopyrrole pigment in which the diketopyrrolopyrrole crude pigment is heated in an aprotic polar organic solvent, an alkali metal hydroxide is used as the organic solvent with respect to 100 parts of the crude pigment in terms of mass. A method for producing a diketopyrrolopyrrole pigment, which comprises using an aprotic polar organic solvent containing 0.1 to 1.5 parts. An aprotic polar organic solvent containing 0.1 to 1.5 parts of alkali metal hydroxide with respect to 100 parts of crude pigment in terms of mass is alkali metal hydroxide with respect to 100 parts of crude pigment in terms of mass. The manufacturing method of Claim 1 using the aprotic polar organic solvent containing 0.2-1.0 part.