JP3271529B2 - Surface-treated pigment and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface-treated pigment and a method for producing the surface-treated pigment.

[0002]

2. Description of the Related Art Pigments are generally insoluble in solvents such as organic solvents and water. Therefore, when used in coloring image forming materials such as inks, paints, plastic colorants, liquid developers, etc., organic solvents may be used depending on the application. Often dispersed in water or water. In particular, recently, there is a strong demand for water-based treatment due to environmental problems and the effect on the human body, and the stability of aqueous dispersion is required.
Conventionally, in order to disperse a pigment in water, the surface of the pigment is modified with a surfactant, a dispersant, or a dispersing resin to obtain a water-based ink or a water-based paint. However, most organic pigments are lipophilic and maintain a dispersed state with an aqueous vehicle, so a dispersant or surfactant is selected for each pigment, and the dispersion conditions may need to be changed or pre-dispersion may be required. However, there is a problem that dispersion is not easy. In the case of an ink jet pigment type ink, the dispersed ink aggregates at the nozzle portion and is difficult to re-disperse. In a coating material, there are problems such as sedimentation of pigment particles due to aggregation.

For this reason, various attempts have been made to improve the dispersion stability, one of which is to improve the hydrophilicity of organic pigments. A method has been already proposed in which a hydrophilic group is chemically introduced into each molecule of an organic pigment to make it hydrophilic, thereby improving the compatibility with a hydrophilic vehicle and increasing the dispersion stability. However, in this case, if the number of introduced hydrophilic groups is large, the treated organic pigment becomes a water-soluble dye,
At the time of image formation, phenomena such as inferior water resistance and weather resistance on the transferred material occur, and there is a problem in performance of the ink. In addition, when the number of the introduced hydrophilic groups is small, the effect required for dispersion stability is significantly reduced. Thus, in the method of introducing a hydrophilic group into a molecule, it is difficult to control the introduced hydrophilic group, and it is extremely difficult to achieve both hydrophilicity and robustness.

On the other hand, a method of treating a pigment surface using fluorine gas has been devised (Kagaku, Vol. 46, No. 9, 199).
1). In this method, it is described that the carbon particle surface is hydrophilicized by ionizing the carbon particle surface with fluorine gas to obtain carbon having excellent dispersibility. However, ionization of the carbon particle surface has a problem in performance stability during storage in a powder state, and has a drawback that it is unstable with respect to pH and temperature changes in a dispersion system. Various processing methods other than the above-mentioned methods are being studied, and they can be roughly classified into gas phase processing and liquid phase processing. Ozone treatment and plasma treatment are typical examples of the gas phase treatment. In both treatment methods, uniform treatment is achieved by stirring the pigment to be treated in the system during the treatment. There are problems such as insufficient uniform treatment due to granulation and difficulty in treating the particle surface inside the aggregated particles.

On the other hand, in the liquid phase treatment, when the treatment is carried out in a reaction tank as in the case of the conventional organic reaction (Japanese Patent Application No.
89119) When the stirring section of the reaction system stirs the crescent blades, turbine blades, anchor blades, etc., the reaction in the tank proceeds uniformly, but the surface treatment can be performed up to the particle surface inside the agglomerated particles as in the gas phase treatment. Have difficulty. Even if the surface treatment effect on the surface of the aggregated particles is sufficient, when the treated pigment is used as a colorant, ink, paint, etc., when the aggregated particles are refined, sufficient dispersion stability is obtained on the surface of the crushed fine particles. There is a problem that the effect is difficult to obtain, and further improvement of the pigment particle surface treatment method has been required.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pigment which is excellent in initial dispersibility and long-term dispersibility in water or an organic solvent and which is less likely to cause aggregation of pigment particles.
Another object of the present invention is to provide a method for hydrophilizing the surface of a pigment for improving dispersibility.

[0007]

That is, according to the present invention, the following surface-treated organic pigment and a method for producing the same are provided. (1) Surface treatment characterized by introducing a sulfonic acid group with a sulfonating agent into the surface of the organic pigment particles while finely dispersing the aggregated particles of the organic pigment in a sulfonation reaction solvent with a pulverizer or a disperser. Pigment manufacturing method. (2) The method for producing a surface-treated pigment according to (1), wherein the fine dispersion by the pulverizer or the disperser is a shear stress or an impact force by a medium. (3) The method for producing a surface-treated pigment according to (1) or (2), wherein the sulfonating agent is a sulfonated pyridine salt or sulfamic acid. (4) The method for producing a surface-treated pigment according to any one of (1) to (3), wherein the sulfonation reaction solvent is a basic solvent that forms a complex with sulfur trioxide. (5) The surface-treated pigment according to (4), wherein the sulfonation reaction solvent is one or more of N, N-dimethylformamide, dioxane, pyridine, triethylamine, trimethylamine, nitromethane, acetonitrile, and trichlorofluoromethane. Production method. (6) The method for producing a surface-treated pigment according to any one of (1) to (3), wherein the sulfonation reaction solvent is sulfolane or N-methyl-2-pyrrolidone. (7) A surface-treated pigment produced by the method according to any one of (1) to (6).

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The surface-treated pigment of the present invention and the organic pigment used in the pigment surface treatment method are not particularly limited, and examples thereof include dye lakes, azos, benzimidazolones, phthalocyanines, quinacridones, and the like. Anthraquinone, dioxazine, indigo, thioindigo, perylene, perinone, diketopyrrolopyrrole, anthuanthrone, isoindolinone, nitro, nitroso, anthraquinone, flavanthrone, quinophthalone, Pyranthrone, indanthrone and the like. The particle size of the pigment particles used is the same as the particle size range of the pigments usually used for inks and paints, but is preferably 50 to 0.01 μm, particularly preferably 10 to 0.05 μm.

In the pigment surface treatment method of the present invention, if a solvent which is insoluble or hardly soluble in the pigment is selected without the dispersing solvent of the reaction system reacting with the sulfonating agent, the sulfonation can be carried out by a usual organic reaction. Reaction can be used. As the sulfonating agent, sulfuric acid, fuming sulfuric acid, sulfur trioxide, chlorosulfuric acid, fluorosulfuric acid, amidosulfuric acid and the like are used. In addition, when sulfur trioxide itself is too reactive to decompose or alter the pigment itself, or when it is difficult to control the reaction with a strong acid, sulfonation using a complex of sulfur trioxide and a tertiary amine is used. (New Experimental Chemistry, Vol. 14, 1773, Maruzen). When used as a simple substance such as sulfuric acid, fuming sulfuric acid, chlorosulfuric acid, or fluorosulfuric acid, the pigment dissolves easily, and for strong acids that react with each molecule, the type of solvent and amount It is necessary to pay attention to The type of the solvent in the reaction, the reaction temperature, the reaction time, the type of the sulfonating agent and the like cannot be specified because they differ depending on the type of the pigment and the reaction system, but examples of the solvent that can be used include sulfolane, N -Methyl-2-pyrrolidone, dimethylacetamide, quinoline, hexamethylphosphoric triamide, chloroform, dichloroethane, tetrachloroethane, tetrachloroethylene, dichloromethane, nitromethane, nitrobenzene, liquid sulfur dioxide, carbon disulfide, trichlorofluoromethane and the like.

Further, a sulfur trioxide complex is used as a sulfonating agent, and a reaction solvent forms a complex with sulfur trioxide, a basic solvent such as N, N-dimethylformamide, dioxane, pyridine, triethylamine, trimethylamine, or nitromethane. Acetonitrile can be used alone or in combination with one or more other solvents described above, as long as it is reactive to form a complex with a sulfonating agent. Specific reaction examples will be described with reference to Examples.

As the pulverizer or disperser used in the pigment surface treatment method of the present invention, various known pulverizers or dispersers can be used. However, as long as the agglomerated particles of the pigment can be finely dispersed, the following specific examples can be used. It will not be done. Specific examples include a three-roll mill and a two-roll mill that finely disperse pigment particles by shear stress, a ball mill that finely disperses by impact force due to collision of pigment particles with media such as glass beads, zirconia beads, and agate balls, Attritors, sand mills, co-ball mills, basket mills, vibration mills, paint conditioners, etc., dispersers, homogenizers, clear mixes, etc. A kneader, an extruder, a jet mill, or the like that finely disperses pigment particles or a pigment particle and a vehicle or a wall by a collision force or a shear stress, and an ultrasonic disperser that finely disperses by ultrasonic waves can be applied. In the pigment surface treatment method of the present invention, since a sulfonating agent is used, it is desirable that any pulverizer, disperser or, if necessary, the medium used is acid-resistant. Three roll mill,
Since the two-roll mill is generally of an open type, it is necessary to pay attention to changes in the reaction system due to the control of the reaction temperature or the volatilization of the solvent, the effects of ignition, and the effects on the human body. Also, when using a closed type pulverizer or disperser, attention must be paid to fire, especially explosion due to static electricity and pressure control, since the inside of the system is filled with the vapor of the solvent.

The surface-treated pigment obtained by the pigment surface treatment method of the present invention reacts with a reactive functional group or an aromatic ring on the surface of the organic pigment, and a sulfonic acid group is bonded to the surface of the pigment particle, whereby the pigment is converted into a vehicle. It is considered that the affinity with a solvent is improved to show excellent dispersion stability. Further, by binding a sulfonic acid group to the surface of the pigment particles, the treated organic pigment can be uniformly acidified. Therefore, conventionally, it was necessary to change the dispersant and the vehicle suitable for the basic pigment and the acidic pigment.However, by adjusting the surface properties of the organic pigment to some extent, the range of the pH value of the pigment surface was controlled, and the dispersant and the vehicle were controlled. The structure can be unified, and it is easy to formulate the ink at the time of ink production. In addition, by performing a surface treatment reaction while finely dispersing the aggregated particles of the organic pigment with a pulverizer or a disperser, the reaction effect was conventionally given only to the surface of the aggregated particles, but to the surface of the finely dispersed particles. The reaction effect can be given up to now, and the dispersibility in water and organic solvents has been improved.

The surface-treated organic pigment of the present invention includes printing inks, paints, cosmetics, writing inks, toners, liquid developers, electrophotographic materials, recording materials such as ink jets, and the like.
It can be used in a wide range of fields such as colorants such as plastics.

[0014]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. However, unless the scope of the present invention exceeds the gist thereof,
It is not limited to the embodiment. In addition, the obtained surface-treated pigment was evaluated by the following method. Dispersion stability: After the prepared ink was allowed to stand at 50 ° C. for 2 months, the state of the precipitate in the ink was examined, and evaluated by △ x.は indicates no precipitate, △ indicates slight precipitate, and × indicates a large amount of precipitate. The particle size distribution of the pigment particles was measured with a laser particle size analyzer (LPA-3000 / 3100, manufactured by Otsuka Electronics Co., Ltd.), and the average particle size of the dispersed pigment particles was determined.

Examples 1-4, Comparative Examples 1-2 Copper phthalocyanine blue (Lionol Blue FG-7351: manufactured by Toyo Ink Mfg. Co., Ltd.) was heated to a predetermined temperature in a solvent under the conditions shown in Table 1. . Next, a sulfonating agent is added, and the mixture is allowed to react while finely dispersing the pigment aggregated particles by a set pulverizer or a disperser for a set time and a set pulverizer or disperser. After washing twice, the mixture was poured into water to obtain a surface-treated copper phthalocyanine blue from the filtrate. Copper phthalocyanine blue reacted without performing fine dispersion of the pigment aggregated particles by a pulverizer or a disperser during the reaction was designated as Comparative Example 1, and untreated copper phthalocyanine blue was designated as Comparative Example 2.

Examples 5-8, Comparative Examples 3-4 Under the conditions shown in Table 1, diketopyrrolopyrrole (IRGA
ZIN DPP Red BO (manufactured by Ciba Geigy) in a solvent to a set temperature. Next, a sulfonating agent is added, and a reaction is performed while finely dispersing the pigment aggregated particles by a set pulverizer or a disperser for a set time and a set pulverizer or disperser. After washing several times, the mixture was poured into water to obtain a surface-treated diketopyrrolopyrrole from the filtrate. Diketopyrrolopyrrole, which was reacted without finely dispersing the pigment aggregated particles by a pulverizer or a disperser during the reaction, was taken as Comparative Example 3, and untreated diketopyrrolopyrrole was taken as Comparative Example 4.

Examples 9 to 12 and Comparative Examples 5 to 6 Under the conditions shown in Table 1, quinacridone red (Lionogen Red YF: manufactured by Toyo Ink Mfg. Co., Ltd.) is heated in a solvent to a set temperature. . Next, a sulfonating agent is added, and a reaction is performed while finely dispersing the pigment aggregated particles with a set pulverizer or a disperser for a set time and a set pulverizer or disperser. After washing, the mixture was poured into water to obtain quinacridone red from the filtrate. Quinacridone red which was reacted without finely dispersing the pigment aggregated particles by a pulverizer or a disperser during the reaction was designated as Comparative Example 5, and untreated quinacridone red was designated as Comparative Example 6.

Evaluation Example 1 With the following composition, a water-soluble amino resin was dissolved in water and propylene glycol, and the surface-treated copper phthalocyanine blue and glass beads obtained in Examples 1-4 and Comparative Examples 1-2 were added thereto. In addition, the mixture was mixed and dispersed with a paint conditioner for 3 hours to obtain an aqueous ink, and a dispersion stability test was performed.
Table 1 shows the results. Surface-treated copper phthalocyanine blue 10 parts by weight Water-soluble amino resin (Cymel 350 manufactured by Mitsui Cytec) 5 parts by weight Glass beads 1φ 30 parts by weight Water 55 parts by weight

Evaluation Example 2 A water-soluble melamine resin was dissolved in water and propylene glycol according to the following formulation, and the surface-treated diketopyrrolopyrrole and glass beads obtained in Examples 5 to 8 and Comparative Examples 3 to 4 were added thereto. Was added and mixed with a paint conditioner for 3 hours to obtain an aqueous ink, and a dispersion stability test was performed.
Table 1 shows the results. Surface-treated diketopyrrolopyrrole 12 parts by weight Water-soluble melamine resin (Melan 620 manufactured by Hitachi Chemical Co., Ltd.) 10 parts by weight Glass beads 1φ 30 parts by weight Water 48 parts by weight

Evaluation Example 3 An acrylic emulsion was dissolved in water and propylene glycol according to the following formulation.
The surface-treated quinacridone and glass beads obtained in Comparative Examples 5 to 6 were added, mixed and dispersed for 3 hours with a paint conditioner to obtain an aqueous ink, and a dispersion stability test was performed. Table 1 shows the results. Surface-treated quinacridone 8 parts by weight Water-soluble acrylic resin (Johncryl J-61 manufactured by Johnson Polymer) 15 parts by weight Dimethylaminoethanol 1 part by weight Glass beads 1φ 25 parts by weight Water 51 parts by weight

[0021]

[Table 1]

[0022]

The surface-treated pigment of the present invention has excellent dispersion stability when mixed with a vehicle or a solvent to form an ink or paint, and shows that the pigment aggregates and precipitates even after long-term storage. I can't.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C09B 67/20 C09B 67/14 C09B 67/48

Claims (7)

(57) [Claims] 1. A sulfonating group is introduced into a surface of an organic pigment particle by a sulfonating agent while finely dispersing aggregated particles of the organic pigment in a sulfonation reaction solvent with a pulverizer or a disperser. A method for producing a surface-treated pigment. 2. The method for producing a surface-treated pigment according to claim 1, wherein the fine dispersion by the pulverizer or the disperser is a shear stress or an impact force by a medium. 3. The method for producing a surface-treated pigment according to claim 1, wherein the sulfonating agent is a sulfonated pyridine salt or sulfamic acid. 4. The process for producing a surface-treated pigment according to claim 1, wherein the sulfonation reaction solvent is a basic solvent which forms a complex with sulfur trioxide. 5. The method for producing a surface-treated pigment according to claim 4, wherein the sulfonation reaction solvent is at least one of N, N-dimethylformamide, dioxane, pyridine, triethylamine, trimethylamine, nitromethane, acetonitrile and trichlorofluoromethane. . 6. The sulfonation reaction solvent is sulfolane or N
The method for producing a surface-treated pigment according to any one of claims 1 to 3, which is -methyl-2-pyrrolidone. 7. A surface-treated pigment produced by the method according to any one of claims 1 to 6.