JPH11302559A - Production of aqueous pigment dispersion, and aqueous colorant composition containing the aqueous pigment dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a finely dispersed aqueous pigment dispersion having good storage stability and capable of forming coating films having excellent water resistance, durability and fastness. SOLUTION: This method for producing an aqueous pigment dispersion having a volume-average pigment particle diameter in a range of 10-500 nm comprises neutralizing a part or all of carboxyl groups in a water-containing cake comprising a resin having an acid value based on the carboxyl groups in a range of 30-120 and the pigment treated with active energy rays and/or an active gas with a basic compound to disperse the neutralization product in an aqueous solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aqueous pigment dispersion useful for an aqueous colorant composition such as an aqueous paint, an aqueous ink, a printing agent, a color filter, a jet ink and a color toner.

[0002]

2. Description of the Related Art From the viewpoints of pollution prevention and occupational health, the industry in which colorants such as paints and inks are used has a strong tendency to become water-based.

[0003] In order to disperse a pigment used in an aqueous colorant in an aqueous medium, a method of dispersing a powdered pigment using a surfactant or a water-soluble resin is generally used. I have. However, a paint containing a pigment dispersed using a surfactant has a problem that the resulting coating film has extremely poor water resistance and can be used only for limited applications. In addition, it is generally more difficult to disperse the pigment in an aqueous medium containing a water-soluble resin than in the case of dispersing the pigment in an organic solvent medium, and the pigment is finely dispersed at a high level, and It is difficult to keep that state stable.

[0004] On the other hand, when the pigment is simply dispersed using a water-soluble resin, the bond between the pigment and the resin is due to only a weak bond called adsorption. Even so, there is a problem that the storage stability is not good because the pigment aggregates with time.

[0005] As a method for obtaining an easily dispersible pigment, an acid is added to an aqueous dispersion of a pigment dispersed in a resin having a carboxyl group neutralized with a base to make the resin hydrophobic. A so-called acid precipitation method is known in which a resin is fixed to a pigment.

For example, there is known a method in which rosin is fixed to a pigment by an acid precipitation method to obtain a powder pigment having good dispersibility. However, rosin cannot be used as a film-forming resin because of its low molecular weight, and also has extremely poor weather resistance. Therefore, the amount of rosin cannot be increased, and the amount of rosin is reduced to about 10% by weight or less. At present, there is no choice but to limit. Therefore, rosin is currently used in powdered pigments as a pigment treating agent, and when used in an aqueous pigment dispersion as in the present invention, a stable aqueous pigment dispersion cannot be obtained with rosin alone. In addition, there is a problem that the performance of the obtained coating film is low.

To solve this problem, Japanese Patent Laid-Open Publication No.
JP-A-122528 and JP-B-61-111979 disclose a method of obtaining a powder or solid pigment by performing acid precipitation using a limited resin such as an acrylic resin having a relatively high molecular weight.

However, in each of these methods, the pigment is solidified or powdered after the acid precipitation, so that the pigment agglomerates in the course of the process. However, there is a problem that a complicated process of kneading is required again. Moreover,
Although the powder or solid pigment obtained by these methods is easier to disperse than the untreated powder pigment, once the pigment has been powdered or solidified, the aqueous colorant has a high degree of coloring and coloring power. There is also a problem that a considerable amount of labor is required to finely disperse the particles to such an extent as to exert the effect.

On the other hand, US Pat. No. 4,166,811 discloses a pigment which uses a water-soluble resin having high hydrophilicity, is re-neutralized with a basic compound after acid precipitation, and is easily dispersed in an aqueous medium. Are disclosed.

However, the basic structure of this method is a method of pulverizing or solidifying after re-neutralizing with a basic compound. When re-dispersing in an aqueous medium, it is possible only with simple stirring. However, it is said that once powdered or solidified, the problem of re-aggregation of the pigment cannot be ignored, and exhibits the coloring property and coloring power of the coated object at a high level However, there is a problem that simple stirring alone is not sufficient. In addition, in order to facilitate redispersion in an aqueous medium after powdering or solidification, the resin that can be used in this method has a low molecular weight, and has a considerably high acid value, and is coated as a colorant. There is also a problem that the toughness and water resistance of the coating film are extremely low.

The film-forming resin used in the aqueous coating agent is
Since physical properties such as toughness of the coating and durability such as water resistance are important, a certain molecular weight or more is necessary, and a carboxyl group is required so as not to lower the water resistance of the obtained coating film. In many cases, the ratio of hydrophilic groups such as the above and various functional groups effective for dispersing the pigment is also reduced. Therefore, it has been extremely difficult to finely disperse the pigment at a high level using an aqueous film-forming resin designed to such a level.

That is, as far as the prior art is concerned, it has not been possible to obtain an aqueous pigment dispersion which can achieve both a fine dispersion of the pigment and a high level of durability such as water resistance of the article to be coated.

In order to solve the above problems, the present inventors disclosed in Japanese Patent Application Laid-Open No. 9-31360 a pigment finely dispersed with a resin having a carboxyl group neutralized using a basic compound. The aqueous dispersion of is strongly fixed to the pigment by making the resin hydrophobic by making the pH neutral or acidic using an acidic compound (hereinafter, this step is referred to as "acid precipitation"), and then If necessary, after filtration and washing with water, the carboxyl groups are neutralized again with a basic compound and redispersed in water, so that the gloss, color development and coloring power are sufficiently high. A method for obtaining an aqueous pigment dispersion that is dispersed and has excellent storage stability was proposed.

[Problems to be solved by the invention]

However, it has been found that pigments are extremely diverse, and it is difficult to finely disperse pigments depending on the kind, and the pigment particle diameter in the dispersion may not reach a target level depending on the use.

The problem to be solved by the present invention is that fine dispersion is still difficult even by the method described in JP-A-9-31360, and the pigment particle size in the dispersion may be reduced to a desired level depending on the application. Even when it does not reach, it is finely dispersed, has good storage stability, and has water resistance, durability,
An object of the present invention is to provide a method for producing an aqueous pigment dispersion capable of forming a coating film having excellent fastness.

[0016]

Even in the method described in JP-A-9-31360, pigments which are still difficult to finely disperse include, for example, surface-untreated copper phthalocyanine blue pigment and surface-untreated pigment. The present inventors concentrated on low-polarity pigments, such as diaminoanthraquinone pigments and surface-untreated monoazo yellow pigments. It has been found that the above problems can be solved by imparting a certain degree of polarity, and the present invention has been completed.

That is, in order to solve the above-mentioned problems, the present invention provides a resin (A) having an acid value based on a carboxyl group in the range of 30 to 120 and a pigment (B) treated with an active energy ray and / or an active gas. ) Is dispersed in an aqueous medium by neutralizing a part or all of the carboxyl groups using a basic compound (D1), thereby dispersing the hydrated cake (C) in an aqueous medium in a range of 10 to 500 nm. Provided is a method for producing an aqueous pigment dispersion having a particle diameter.

The "acid value" in the present invention is expressed in mg of potassium hydroxide necessary to neutralize 1 g of the solid content of the resin (A).

The manufacturing method of the present invention basically includes the following manufacturing steps. (1) A resin (A) having an acid value based on a carboxyl group in the range of 30 to 120 and a pigment (B) subjected to active energy ray treatment and / or active gas treatment are mixed or kneaded. (2) Disperse in an alkaline aqueous medium. (3) The resin (A) is made hydrophobic by making the pH neutral or acidic, and the resin (A) is strongly fixed to the pigment. (4) Filter and wash as necessary. (5) Neutralize the carboxyl group with a basic compound and re-disperse in an aqueous medium.

The resin (A) used in the production method of the present invention has an acid value based on a carboxyl group of 30 to 120.
If it is a resin in the range, it can be used without particular limitation.
Such resins include, for example, vinyl copolymers,
Polyester resin, polyurethane resin, epoxy resin,
Rosin-modified resin and the like can be mentioned. Among these, vinyl copolymers, polyester resins and polyurethane resins are preferred from the viewpoint of easy introduction of carboxyl groups and toughness of the coating.

The vinyl copolymer used in the production method of the present invention includes, for example, (meth) acrylate resin, (meth) acrylate-styrene copolymer resin, and styrene- (maleic anhydride) copolymer. Examples thereof include a polymer resin and a fluorine-containing vinyl copolymer resin.
Examples of the polyester resin used in the production method of the present invention include a saturated polyester resin, an unsaturated polyester resin, and an alkyd resin. It is essential that these resins contain a carboxyl group as a hydrophilic group for imparting appropriate water solubility or water dispersibility.

The vinyl copolymer having a carboxyl group can be easily produced by a method of copolymerizing a polymerizable monomer composition containing a polymerizable monomer having a carboxyl group. Examples of the polymerizable monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, fumaric acid, itaconic acid, (anhydrous) maleic acid, monoalkyl maleates such as monobutyl maleate, and itacons such as monobutyl itaconate. Monoalkyl acid and the like.

Examples of the polymerizable vinyl monomer other than the polymerizable vinyl monomer having a carboxyl group contained in the polymerizable monomer composition include aromatic vinyl monomers such as styrene, vinyltoluene and α-methylstyrene; methyl ( (Meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) Acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, butoxymethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, benzyl (meth) (Meth) acrylic esters such as acrylate, cetyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate and isobornyl (meth) acrylate; vinyl esters such as vinyl acetate, vinyl benzoate, vinyl versatate and vinyl propionate Polymerizable nitriles such as (meth) acrylonitrile;

Vinyl monomers having a fluorine atom such as vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene or chlorotrifluoroethylene; diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate,
Tertiary amino group-containing monomers such as N-vinylimidazole and N-vinylcarbazole; 2- (2'-hydroxy-5-methacryloyloxyethylphenyl) -2
H-benzotriazole, 2-hydroxy-4- (2-methacryloyloxyethoxy) benzophenone, 1,
Monomers having ultraviolet absorbing or antioxidant properties, such as 2,2,6,6-pentamethyl-4-piperidyl methacrylate; N-vinylpyrrolidone, glycidyl (meth) acrylate, 1,3-dioxolan-2-one-
N-alkoxymethyl (meth) such as 4-ylmethyl (meth) acrylate, 1,3-dioxolan-2-one-4-ylmethylvinylether, diacetone acrylamide, N-methylolacrylamide, N-butoxymethyl (meth) acrylamide Functional group-containing monomers such as acrylamides; monomers having a hydrolyzable alkoxysilane group such as γ-methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane; 2-
Phosphoric acid group-containing monomers such as phosphooxyethyl (meth) acrylate and 4-phosphooxybutyl (meth) acrylate; macromonomers having one polymerizable unsaturated group at the molecular terminal;

As the polymerization method of the polymerizable vinyl monomer composition, various known polymerization methods such as suspension polymerization, emulsion polymerization, bulk polymerization, and solution polymerization can be used, but solution polymerization is preferred because it is simple. As the polymerization initiator, known peroxides and azo compounds can be used.

The carboxyl group-containing polyester resin used in the present invention is prepared by mixing a carboxyl group-containing compound and a hydroxyl group-containing compound such that the carboxyl group remains.
It is produced by performing a dehydration condensation reaction by a known method such as a melting method and a solvent method.

The polyester resin includes a compound having a carboxyl group such as a monobasic acid, a dibasic acid, and a polybasic acid;
The alkyd resin is obtained by appropriately selecting a compound having a hydroxyl group such as a diol or a polyol and subjecting the compound to dehydration condensation, and further using an oil or a fat or a fatty acid as an alkyd resin.

The carboxyl groups of the polyester resin used in the production method of the present invention are mainly unreacted carboxyl groups derived from dibasic or polybasic acids constituting the polyester resin.

Examples of the dibasic acid or polybasic acid include adipic acid, (anhydride) succinic acid, sebacic acid, dimer acid, (anhydride) maleic acid, (phthalic anhydride), isophthalic acid, terephthalic acid, tetrahydro ( Phthalic acid, hexahydro (anhydride) phthalic acid, hexahydroterephthalic acid, 2,6-naphthalenedicarboxylic acid, (anhydride)
Trimellitic acid, (anhydrous) pyromellitic acid and the like.

Compounds having a carboxyl group that can be used other than dibasic acids or polybasic acids include lower alkyl esters of acids such as dimethyl terephthalate;
Monobasic acids such as benzoic acid, p-tert-butylbenzoic acid, rosin, hydrogenated rosin; fatty acids and fats and oils; macromonomers having one or two carboxyl groups at molecular terminals; 5-sodium sulfoisophthale Acids and dimethyl esters thereof.

As the compound having a hydroxyl group, for example,
Ethylene glycol, neopentyl glycol, propylene glycol, diethylene glycol, dipropylene glycol, 2-methyl-1,3-propanediol,
2,2-diethyl-1,3-propanediol, 1,4
-Butanediol, 1,3-propanediol, 1,6
-Hexanediol, 1,4-cyclohexanedimethanol, 1,5-pentanediol, an alkylene oxide adduct of bisphenol A, hydrogenated bisphenol A,
Alkylene oxide adduct of hydrogenated bisphenol A,
Polyethylene glycol, polypropylene glycol,
Diols such as polytetramethylene glycol; polyols such as glycerin, trimethylolpropane, trimethylolethane, diglycerin, pentaerythritol, and trishydroxyethyl isocyanurate;
Monoglycidyl compounds such as "Kajura E-10" (glycidyl ester of a synthetic fatty acid manufactured by Shell Chemical Industry Co., Ltd.), macromonomers having two hydroxyl groups at one molecular end, and the like.

When synthesizing a polyester resin,
Castor oil, hydroxyl-containing fatty acids or oils such as 12-hydroxystearic acid; dimethylolpropionic acid,
Compounds having a carboxyl group and a hydroxyl group, such as p-hydroxybenzoic acid and ε-caprolactone, can also be used.

Further, a part of the dibasic acid can be replaced with a diisocyanate compound.

As the polyester resin having a carboxyl group used in the production method of the present invention, a modified polyester resin obtained by grafting a polymerizable monomer having a carboxyl group to the polyester resin can also be used.

The polyurethane having a carboxyl group is
It can be easily produced by using a compound having a carboxyl group and a hydroxyl group such as dimethylolpropionic acid as the segment having a hydroxyl group.

The polyurethane resin having a carboxyl group used in the production method of the present invention comprises a polyol component containing a compound having a carboxyl group and a hydroxyl group such as dimethylolpropionic acid as a component for introducing a carboxyl group, and a polyisocyanate component. Can be easily produced by reacting

As the polyol component, in addition to the diol components listed in the polyester production method, a trifunctional or higher functional polyol compound can be used, if necessary.

The polyisocyanate component includes 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, 1,5-naphthalene diisocyanate,
Meta-xylylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated 4,
In addition to diisocyanate compounds such as 4'-diphenylmethane diisocyanate, hydrogenated meta-xylylene diisocyanate and crude 4,4'-diphenylmethane diisocyanate, polyisocyanate compounds such as polymethylene polyphenyl isocyanate can also be used.

The production of the polyurethane resin may be carried out according to a conventional method. For example, the addition reaction is preferably performed at room temperature or at a temperature of about 40 to 100 ° C. in an inert organic solvent solution that does not react with the isocyanate group. At that time, a known catalyst such as dibutyltin dilaurate may be used.

In the reaction system for producing the polyurethane resin, known chain extenders such as diamines, polyamines, N-alkyl dialkanolamines such as N-methyldiethanolamine, and dihydrazide compounds can be used.

As the resin (A) having a carboxyl group used in the production method of the present invention, a maleic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydro Resins having a carboxyl group obtained by a method in which a polybasic anhydride such as phthalic anhydride or trimellitic anhydride is subjected to an addition reaction can also be used.

The amount of the carboxyl group in the resin (A) having a carboxyl group used in the present invention is such that the acid value is 30 to 1
A range of 20 is preferable, and a range of 50 to 100 is more preferable. The acid value of the resin (A) used in the present invention is 1
If it exceeds 20, the hydrophilicity becomes too high, and the water resistance of the coated object tends to be remarkably reduced.
If it is lower than 0, it is not preferable because acid precipitation tends to reduce redispersibility in water after neutralization.

The resin (A) having a carboxyl group used in the production method of the present invention more preferably has a hydroxyl group in addition to the carboxyl group. The hydroxyl group bonded to the resin (A) can form a stronger film by reacting with a curing agent when used in baking paints, baking inks, printing agents and the like.

The vinyl copolymer having a carboxyl group and a hydroxyl group is prepared by a method of copolymerizing the polymerizable monomer used for producing the vinyl copolymer having a carboxyl group with the polymerizable monomer having a hydroxyl group. It can be easily manufactured.

Examples of the polymerizable monomer having a hydroxyl group include:
For example, 2-hydroxyethyl (meth) acrylate,
Alkyl (meth) acrylates having a hydroxyl group such as 2-hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate;
(Meth) acrylic monomers to which a lactone compound represented by M-2 "and" Placcel FA-2 "(manufactured by Daicel Chemical Industries, Ltd.) are added; polyethylene glycol mono (meth) acrylate monomers; polypropylene glycol mono (meth) A) acrylate monomers; and alkyl vinyl ethers having a hydroxyl group such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether.

The polyester resin having a carboxyl group and a hydroxyl group may be reacted in a dehydration condensation reaction of the polyester resin according to a known method so that the hydroxyl group remains. The remaining hydroxyl group is an unreacted group derived from a diol compound, a polyol compound or a carboxylic acid polyol compound.

The vinyl copolymer having a carboxyl group and the polyurethane resin used in the production method of the present invention are:
Those having a number average molecular weight in the range of 5,000 to 20,000 are preferred. When the number average molecular weight is smaller than 5,000, the coating film tends to become brittle when the obtained aqueous pigment dispersion is used as a coating agent, which is not preferable. When the number average molecular weight is larger than 20,000,
It is not preferable because it is difficult to obtain a fine aqueous pigment dispersion.

Since the polyester resin used in the production method of the present invention is mostly of a branched type, unlike the case of a linear vinyl copolymer or the like, even if the number average molecular weight is small, the weight of the polyester resin is low. Since it has a large average molecular weight, it has sufficient toughness as a coating film. Therefore, the polyester resin has a number average molecular weight of 1,000 to 20,000.
It is preferably in the range of 0, and in the weight average molecular weight,
Those in the range of 5,000 to 100,000 are preferred.

Active energy ray-treated and / or active gas-treated pigment (B) used in the production method of the present invention
The term “pigment” means a pigment obtained by treating powder such as an inorganic pigment, an extender pigment, carbon black, and an organic pigment with an active energy ray and / or an active gas.

Examples of the organic pigment include phthalocyanine blue, phthalocyanine green, Hansa Yellow,
Permanent red, anthraquinone, perinone, dioxazine, perylene, quinacridone, azo metal complex,
Methine-based metal complexes, thioindigo, isoindolinone,
Slen blue, diaminoanthraquinolyl and the like, and inorganic pigments, for example, zinc white, titanium oxide, antimony white, carbon black, iron black, red bengal, mapico yellow, lead red, cadmium yellow, zinc sulfide, lithopone,
Examples include barium sulfate, lead sulfate, barium carbonate, calcium carbonate, lead white, alumina white and the like.

The method of the active energy ray treatment and / or the active gas treatment of the pigment used in the production method of the present invention means that the pigment powder is irradiated with an active energy ray or brought into contact with an active gas to obtain a pigment. A method for modifying a surface. Examples of the active energy rays include ultraviolet rays, electron rays, α rays, β rays, γ rays, visible rays, and infrared rays. Among them, ultraviolet rays are generally used, and are desirable from the viewpoint of processing efficiency. Ozone gas is representative of the active gas, but it can also be activated by generating radicals by using an oxygen gas or an ammonia gas together with an active energy ray. For example, a method of modifying the surface of the pigment by irradiating the pigment powder with an active energy ray such as ultraviolet light, contacting it with an active gas such as ozone gas, or contacting oxygen gas plasma or ammonia gas plasma. This corresponds to this.

It is known that these methods improve the dispersibility of pigments used in paints and inks.
"Coloring Agents Association" Vol. 59 (No. 12), 732-74
0 (1986), "Journal of Coatings Technolog
y) "Vol. 60, No. 765, pp. 107-112 (198
8 years), JP-A-56-15563, and JP-A-5
In JP-A-7-177342, JP-A-58-205540 and JP-A-59-145038, plasma treatment of a pigment is used, and in JP-A-9-150049, ultraviolet treatment is used. The examples used in the article are introduced.

Next, the manufacturing method of the present invention will be described sequentially according to the steps.

In the step of mixing or kneading the resin (A) having a carboxyl group and the pigment (B) that has been subjected to the active energy ray treatment and / or the active gas treatment, the following 2 steps are performed.
The method is appropriate. (1) Active energy ray treatment in an organic solvent medium and / or
Alternatively, the active gas-treated pigment (B) is kneaded and then dispersed in an aqueous medium. (2) Mix or knead the pigment (B) that has been subjected to the active energy ray treatment and / or the active gas treatment in an aqueous medium.

A first method applicable to the step of mixing or kneading the resin (A) having a carboxyl group and the pigment (B) that has been subjected to the active energy ray treatment and / or the active gas treatment.
In the kneading in an organic solvent according to the above method, first, a pigment (B) treated with an active energy ray and / or an active gas and an organic solvent solution of the resin (A) having a carboxyl group are mixed with a ball mill, a sand mill, and the like. And finely dispersed using a known dispersing machine such as a colloid mill.

At this time, as the organic solvent to be used, all commonly used organic solvents can be used, but those having good solubility in the resin and having no problem in the synthesis of the resin, having a higher vapor pressure than water, and It is preferable to use a material that is easy to mix and further miscible with water. As such a solvent, for example,
Acetone, methyl ethyl ketone, methanol, ethanol, n-propanol, isopropanol, ethyl acetate, tetrahydrofuran and the like are particularly preferred. Low miscibility with water, but methyl isopropyl ketone, methyl-n
-Propyl ketone, isopropyl acetate, n-propyl acetate, methylene chloride, benzene and the like can also be used.

Active energy ray-treated and / or active gas-treated pigment (B) dispersed in an organic solvent medium
In order to disperse a dispersion comprising a resin (A) having a carboxyl group and an aqueous medium, the carboxyl group of the resin (A) is neutralized with a basic compound (D2), and the resin (A) is hydrophilically dispersed. And dispersing it in water. Alternatively, a resin (A) having a carboxyl group neutralized with a basic compound (D2) and a pigment (B) treated with an active energy ray and / or an active gas
May be dispersed in water.

The following method is suitable for dispersing in water. (A) A dispersion composed of a resin (A) having a carboxyl group and a pigment (B) treated with an active energy ray and / or an active gas is neutralized with a basic compound, and then water is added dropwise. (B) a resin (A) having a carboxyl group neutralized with a basic compound and treated with an active energy ray and / or
Alternatively, water is added dropwise to the dispersion comprising the pigment (B) that has been treated with active gas. (C) Water containing a basic compound is dropped into a dispersion composed of a resin (A) having a carboxyl group and a pigment (B) that has been treated with an active energy ray and / or an active gas. (D) neutralizing a dispersion comprising a resin (A) having a carboxyl group and a pigment (B) treated with an active energy ray and / or an active gas with a basic compound,
Add into aqueous medium. (E) a resin (A) having a carboxyl group neutralized with a basic compound and treated with an active energy ray and / or
Alternatively, a dispersion comprising the pigment (B) treated with an active gas is added to an aqueous medium. (F) A dispersion comprising a resin (A) having a carboxyl group and a pigment (B) treated with an active energy ray and / or an active gas is added to an aqueous medium containing a basic compound.

When dispersing in water, it may be carried out by ordinary stirring at a low shear, stirring at a high shear by a homogenizer or the like, or using ultrasonic waves. For the purpose of assisting dispersion in an aqueous medium, a surfactant, a protective colloid, or the like may be used in combination within a range that does not significantly lower the water resistance of the coating film.

As the basic compound (D2), for example,
Inorganic bases such as sodium hydroxide and potassium hydroxide; and organic amines such as ammonia, triethylamine, tributylamine, dimethylethanolamine, diisopropanolamine and morpholine.

A second method applicable to the step of mixing or kneading the resin (A) having a carboxyl group and the pigment (B) that has been treated with active energy rays and / or treated with active gas.
In the method of kneading the resin (A) and the pigment (B) that has been subjected to the active energy ray treatment and / or the active gas treatment in an aqueous medium, first, the carboxyl group of the resin (A) is converted to a basic compound as described above. The mixture is neutralized with the compound (D2) and mixed or kneaded with the pigment (B) that has been subjected to the active energy ray treatment and / or the active gas treatment in an aqueous medium. At this time,
The resin (A) dissolved or dispersed in water may contain an organic solvent, or may be a medium containing substantially only water by removing the solvent. As the pigment, any of a powder pigment, an aqueous slurry, and a press cake can be used. In the case where the pigment is dispersed in an aqueous medium, the pigment is used in order to simplify the production process and reduce secondary aggregation of the pigment particles.
It is preferred to use aqueous slurries or press cakes. The kneading method, the organic solvent, and the basic compound (D2)
The same method and the same material as in the case of dispersion in an organic solvent medium are possible.

Regardless of the type of kneading, either of an organic solvent type or an aqueous type, additives usually used in a pigment dispersion can be used within a range that does not lower the water resistance of the coating film.

When the pigment is kneaded or after kneading and before acid precipitation, substances other than the pigment, for example, a dye, an antioxidant, an ultraviolet absorber, a curing catalyst for a coating binder, a rust preventive. Agents, fragrances, drugs and the like can also be added.

The ratio of the resin (A) having a carboxyl group to the pigment is preferably in the range of 1 to 200 parts by weight, based on 100 parts by weight of the pigment, of the solid content of the resin (A).
A range of 00 parts by weight is particularly preferred. When the amount of the resin (A) used is less than 1 part by weight, the pigment tends to be difficult to disperse sufficiently finely, and when it is more than 200 parts by weight, the proportion of the pigment in the dispersion decreases, When the aqueous pigment dispersion is used as a coating agent or the like, there is a tendency that there is no room for formulation design, which is not preferable.

The acid precipitation performed for the purpose of strongly fixing the resin (A) to the pigment finely dispersed in the aqueous medium is performed by removing carboxyl groups neutralized by the basic compound (D2).
The resin (A) is made hydrophobic by adding an acidic compound (E) to make the pH neutral or acidic.

Examples of the acidic compound (E) to be used include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid; formic acid,
Organic acids such as acetic acid and propionic acid can be used, but hydrochloric acid which has a small amount of organic substances in the waste water and has a large acid precipitation effect is preferable. The pH at the time of acid precipitation is preferably in the range of 3 to 6, but some pigments can be decomposed by an acid. In the case of such a pigment, it is preferable to carry out acid precipitation at a pH of 4 to 7. It is preferable to remove the organic solvent present in the system before the acid precipitation by using a method such as distillation under reduced pressure.

After acid precipitation, if necessary, filtration and washing with water are performed to obtain a water-containing cake (C) of the dispersed pigment. As a filtration method, a known method such as suction filtration, pressure filtration, and centrifugation can be employed.

The water-containing cake (C) is not dried, and the carboxyl group is re-neutralized with the basic compound (D1) in a water-containing state, so that the pigment particles are not aggregated, and are not finely divided. While maintaining the state,
Redispersed in aqueous medium. As the basic compound (D1), volatile amine compounds such as ammonia, triethylamine and dimethylethanolamine are preferable in consideration of the water resistance of the coating film and the like.

The aqueous pigment dispersion thus obtained preferably has a volume average particle diameter in the range of 10 to 500 nm. When the volume average particle size is larger than 500 nm, it is difficult to obtain a coating film having excellent gloss, coloring properties, and coloring power, which is not preferable. In addition, a volume average particle size smaller than 10 nm is obtained. It is very difficult and unrealistic.

The aqueous pigment dispersion thus obtained is used by being blended with an aqueous paint, an aqueous ink, a printing agent and the like.

[0071]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the following examples, “parts” and “%” are all based on weight unless otherwise specified.

The molecular weight in the following examples is G
It was measured by PC (gel permission chromatography), and the volume average particle diameter was "UPA-1".
50 "(laser Doppler type particle size distribution meter manufactured by JGC Corporation).

<Synthesis Example 1> (Synthesis of Vinyl Copolymer) A three-liter four-necked flask equipped with a dropping device, a thermometer, a nitrogen gas inlet tube, a stirrer, and a reflux cooling tube was prepared.
Charge 1,000 parts of methyl ethyl ketone, and adjust the liquid temperature to 78.
C., and then heated to 700 ° C., n-butyl methacrylate 700
, 42 parts of n-butyl acrylate, 150 parts of 2-hydroxyethyl methacrylate, 108 parts of methacrylic acid and 80 parts of tert-butyl peroxy-2-ethylhexanoate were added dropwise over 4 hours. Further, the reaction was continued at the same temperature for 8 hours. After allowing the reaction mixture to cool to room temperature, methyl ethyl ketone was added and diluted so that the nonvolatile content became 50%, to obtain a resin solution A having an acid value of 70 and a number average molecular weight of 6,000.

<Synthesis Example 2> (Synthesis of Vinyl Copolymer) A three-liter four-necked flask equipped with a dropping device, a thermometer, a nitrogen gas inlet tube, a stirrer, and a reflux cooling tube was prepared.
Charge 1,000 parts of methyl ethyl ketone, and adjust the liquid temperature to 78.
After heating to ℃, a mixture consisting of 146 parts of styrene, 551 parts of n-butyl methacrylate, 150 parts of 2-hydroxyethyl methacrylate, 153 parts of methacrylic acid and 20 parts of tert-butyl peroxy-2-ethylhexanoate. The solution was added dropwise over 4 hours. Further, the reaction was continued at the same temperature for 8 hours. After allowing the reaction mixture to cool to room temperature, it was diluted by adding methyl ethyl ketone so that the nonvolatile content became 50%, and the acid value was 100 and the number average molecular weight was 1
6,000 resin solution B was obtained.

<Synthesis Example 3> (Synthesis of Polyester Resin) Into a two-liter four-necked flask equipped with a dehydrating tube, a thermometer, a nitrogen gas introducing tube, and a stirrer,
E-10 "(glycidyl ester of a synthetic fatty acid manufactured by Shell Chemical Industry Co., Ltd.) 100 parts, adipic acid 241 parts,
376 parts of hexahydrophthalic anhydride, 195 parts of neopentyl glycol, 165 parts of trimethylolpropane, and 0.5 part of dibutyltin dioxide were charged, and the temperature was raised to 190 ° C. over 5 hours while dehydrating. A dehydration condensation reaction was performed. The acid value was measured by sampling, and the reaction was terminated so that the target acid value was 60. After allowing the reaction mixture to cool, it was diluted by adding methyl ethyl ketone so that the nonvolatile content became 65%. The acid value was 61, the number average molecular weight was 2,200, and the weight average molecular weight was 30,000.
0, a resin solution C having a hydroxyl value per resin solid content of 60 was obtained.

<Synthesis Example 4> (Synthesis of Polyurethane Resin) 900 parts of methyl ethyl ketone and 129 dimethylolpropionic acid were placed in a three-liter four-necked flask equipped with a thermometer, a nitrogen gas inlet tube, a stirrer, and a reflux condenser.
Parts, 521 parts of “Placcel 212” (polylactone diol manufactured by Daicel Chemical Industries, Ltd.) and 350 parts of isophorone diisocyanate were reacted at 78 ° C. for 2 hours, and 0.1 part of dibutyltin dilaurate was added. Further, the reaction was carried out at the same temperature for 4 hours. After allowing the reaction mixture to cool to 30 ° C., a solution prepared by dissolving 5.8 parts of ethylenediamine in 106 parts of methyl ethyl ketone was charged.
After reacting for 1 hour, the acid value is 54, the number average molecular weight is 12,
000 was obtained.

<Processing Example 1> (Example of oxygen / UV treatment of pigment) A container having a diameter of 30 cm and a height of 8 cm in which a 0.3 mm-thick stainless steel film capable of being vibrated by a sound wave is provided on the bottom, A mechanism for applying mechanical vibration by a vibration motor having a balancer to the bottom, and a mechanism for applying vibration by sound waves using a speaker to the bottom of the container,
A gas introduction mechanism comprising an inlet for introducing various gases into the container and an outlet for allowing various gases to flow out of the container,
The powder was heated and dried at 80 ° C. under reduced pressure for 48 hours using an apparatus for stirring and treating powder having an ultraviolet irradiation device on the upper part of the container (the device used in Example 1 of JP-A-9-150049). Quinacridone pigment "Fastogen
50 g of "Super Magenta RG" (hereinafter abbreviated as "RG") is placed in a container, and the inside of the container is replaced with nitrogen gas. Then, while flowing oxygen gas at a flow rate of 10 ml per minute, the vibration motor is used. Mechanical vibration of 6000 revolutions per minute and frequency 15
A low-pressure mercury lamp is used as a light source while agitating the pigment by applying vibration with a sound wave of 0 Hz and an output of 10 W.
Stirring and surface treatment were performed for 60 minutes by irradiating ultraviolet rays having wavelengths of 4.9 nm and 253.7 nm to the pigment to be treated at an irradiation distance of 10 cm.

<Processing Example 2> (Example of oxygen / UV treatment of pigment) In processing example 1, monoazo yellow pigment "Shimlerfast Yellow Y4181" (hereinafter, referred to as "RG4") was used instead of RG.
Abbreviated as Y4181. ), And the surface treatment was performed in the same manner as in Processing Example 1 except that the frequency and output of the sound wave were changed to 230 Hz and 4.5 W.

<Treatment Example 3> (Pigment oxygen / UV treatment example) In treatment example 1, phthalocyanine pigment "Fastogen Blue FGF" (hereinafter abbreviated as FGF) was used in place of RG, and the Frequency and output frequency 2
Surface treatment was performed in the same manner as in Processing Example 1 except that the output was changed to 30 Hz and the output was 4.5 W.

<Processing Example 4> (Oxygen Plasma Treatment of Pigment) "Journal of Coatings Technology", Vol. 60, No. 76
According to the description of No. 5, pp. 107-112 (1988), an electrode was wound in a coil shape so as to enclose the outside of the eggplant-shaped flask portion of the evaporator, and a processing apparatus for generating low-temperature plasma was made by itself.

The diaminoanthraquinone pigment "Fastogen Super Red ATY-01" (hereinafter referred to as AT
Abbreviated as Y-01. ) 30 g was put into a 500 ml eggplant type flask, and the inside of the evaporator was depressurized while rotating at 30 rpm and flowing oxygen gas.
13.56 or less while controlling to orr or less.
A high frequency of MHz was applied at an applied power of 50 W for 2 hours to generate a plasma gas to perform a surface treatment of the pigment.

<Example 1> (Preparation Example of Aqueous Dispersion of Pigment) (1) Pigment Kneading Step The resin having a carboxyl group in the resin solution A obtained in Synthesis Example 1 was made 100% using dimethylethanolamine. Neutralized. To a 250 cc glass bottle, 8 parts of the neutralized resin in terms of solid content and 8 parts of RG treated in Processing Example 1 were added, and ion-exchanged water was added so that the total amount became 60 parts. After adding 130 g of 0.5 mm glass beads, kneading was performed for 4 hours using a paint shaker.
After completion of the kneading, the glass beads were removed by filtration to obtain a dispersion of a resin having a carboxyl group neutralized with a base and a pigment dispersed in water.

(2) Acid precipitation After dispersing a dispersion of a resin having a carboxyl group and a pigment neutralized with a base and a pigment in water, adding water and diluting it twice, stirring with a disper, 1N. Hydrochloric acid was added until the resin became insoluble and fixed to the pigment. PH at this time
Was 3-5.

(3) Filtration and washing The aqueous medium containing the pigment to which the resin is fixed is filtered by suction.
The residue was washed with water until the pH of the washing solution exceeded 6, to obtain a water-containing cake.

(4) Neutralization and Redispersion in Aqueous Medium After water is added to the water-containing cake until the water-containing cake flows, the pH of the dispersion is adjusted while stirring with a disper.
Until a pH of 8.5 to 9.5 was reached. Furthermore, after stirring was continued for 1 hour, water was added to adjust the nonvolatile content to 20% to obtain an aqueous pigment dispersion A-1.

<Comparative Example 1> In Example 1, processing example 1
An aqueous pigment dispersion a-1 was obtained in the same manner as in Example 1, except that untreated RG was used instead of RG treated with.

<Comparative Example 2> In Comparative Example 1, after removing the solvent under reduced pressure without performing acid precipitation, water was added.
The aqueous pigment dispersion a-2 was obtained by adjusting the nonvolatile content to 20%.

Example 2 In a 250 cc glass bottle, 16 parts of the resin solution B obtained in Synthesis Example 2 (8 parts
Parts), 8 parts of Y4181 treated in Processing Example 2, 40 parts of methyl ethyl ketone, and 130 parts of glass beads having an average diameter of 1.5 mm were charged and kneaded with a paint shaker for 4 hours. After adding 24 parts of methyl ethyl ketone to the kneaded material, the glass beads were removed by filtration. 88 parts of the kneaded product composed of the resin having a carboxyl group and the pigment thus obtained was put into an aqueous solution composed of 1.4 parts of dimethylethanolamine and 100 parts of water while stirring with a homomixer. Then, about 8 of methyl ethyl ketone
The fraction was removed by distillation under reduced pressure, and the process proceeded to an acid precipitation step.

After the acid precipitation step, an aqueous pigment dispersion B-1 was obtained in the same manner as in Example 1.

<Comparative Example 3> In Example 2, processing example 2
An aqueous pigment dispersion b-1 was obtained in the same manner as in Example 2, except that untreated Y4181 was used instead of Y4181 treated with.

<Comparative Example 4> In Comparative Example 3, after removing the solvent under reduced pressure without performing acid precipitation, water was added.
The aqueous pigment dispersion b-2 was obtained by adjusting the nonvolatile content to 20%.

<Example 3> In Example 1, synthesis example 1 was used.
In the same manner as in Example 1, except that the resin solution C obtained in Synthesis Example 3 was used in place of the resin solution A obtained in Step 3, and an untreated FGF was used instead of the FGF treated in Treatment Example 3, A pigment dispersion C-1 was obtained.

<Comparative Example 5> In Example 3, processing example 3
An aqueous pigment dispersion c-1 was obtained in the same manner as in Example 3, except that untreated FGF was used instead of the FGF treated with.

<Comparative Example 6> In Comparative Example 5, the solvent was removed under reduced pressure without performing acid precipitation, and then water was added.
The aqueous pigment dispersion c-2 was obtained by adjusting the nonvolatile content to 20%.

<Example 4> In Example 1, Synthesis Example 1
The resin solution A obtained in Synthesis Example 4 was used in place of the resin solution A obtained in Example 4, and 4 parts by weight in terms of solid content was used.
Aqueous pigment dispersion D- was prepared in the same manner as in Example 1 except that 8 parts of TY-01 and 10% aqueous ammonia were used instead of a 10% aqueous solution of dimethylethanolamine used for neutralization after acid precipitation. 1 was obtained.

<Comparative Example 7> In Example 4, processing example 4
Unprocessed ATY-0 instead of ATY-01 processed in
Except for using 1, an aqueous pigment dispersion d-1 was obtained in the same manner as in Example 4.

<Comparative Example 8> In Comparative Example 7, the solvent was removed under reduced pressure without performing acid precipitation, and then water was added.
By adjusting the nonvolatile content to 20%, an aqueous pigment dispersion d-2 was obtained.

<Examples 5 and 6> (Water-soluble baking acrylic resin paint) "Watersol S-751" (Acrylic resin for water-soluble baking paint manufactured by Dainippon Ink and Chemicals, Inc .;
Non-volatile content = 50%, “Symel 303” (melamine resin manufactured by Mitsui Cyanamid Co .; active ingredient content = 98)
%) And each of the aqueous pigment dispersions obtained in Examples 1 and 2 (non-volatile content = 20%), in terms of solid content, 28 parts of “Watersol S-751” 12 parts of “Cymer 303” 12 parts Pigment dispersing resin 10 The pigment was blended so as to have a ratio of 10 parts, and water was added to dilute the mixture to prepare a water-soluble baked acrylic resin paint having a nonvolatile content of 24%.

The coating material thus obtained was referred to as “BT-14”.
4 treated steel sheet "(Zinc phosphate treated steel sheet manufactured by Nippon Parker Rising Co., Ltd.) using a bar coater so that the film thickness becomes 20 ± 2 μm, and after setting for 10 minutes, 150
Baking was performed at 20 ° C. for 20 minutes to produce a test piece of the example. Each paint was coated on a corona discharge treated PET (polyethylene terephthalate) film with a film thickness of 10 ± 1.
After coating with a bar coater and setting for 10 minutes, baking was performed at 150 ° C. for 20 minutes to prepare a test piece of an example.

Comparative Examples 9 to 12 The procedure of Example 5 was repeated, except that the aqueous pigment dispersions obtained in Comparative Examples 1 to 4 were used instead of the aqueous pigment dispersion obtained in Example 1. In the same manner as in No. 5, water-soluble baked acrylic resin paints were respectively prepared.

In the same manner as in Example 5, the paint obtained in each comparative example was applied on the “BT-144 treated steel sheet” and the PET film subjected to the corona discharge treatment to prepare a test piece of the comparative example. .

<Example 7> (Water-soluble baked polyester resin paint) In Example 5, "Watersol S-751" was used.
Example 1 was replaced with "Watersol S-212" (a polyester resin for water-soluble baking paint manufactured by Dainippon Ink and Chemicals, Ltd .; nonvolatile content = 65%).
In the same manner as in the case of the water-soluble baked acrylic resin paint of Example 5, except that the aqueous pigment dispersion obtained in Example 3 was used in place of the water-based pigment dispersion obtained in the above, the water-soluble baked polyester resin paint was used. Was prepared.

In the same manner as in Example 5, on the “BT-144 treated steel sheet” and on the corona discharge treated PET film,
The paint obtained in Example 7 was applied to prepare a test piece of Example.

<Comparative Examples 13 and 14>
Comparative Examples 5 and 6 in place of the aqueous pigment dispersion obtained in Example 5
A water-soluble baked polyester resin paint was prepared in the same manner as in Example 7, except that the respective aqueous pigment dispersions obtained in the above were used.

In the same manner as in Example 7, on the “BT-144 treated steel sheet” and on the corona discharge treated PET film,
Each paint obtained in the comparative example was applied to prepare a test piece of the comparative example.

<Example 8> (Urethane-based aqueous ink) "Hydran AP-40" (a water-based urethane resin manufactured by Dainippon Ink and Chemicals, Inc., having a nonvolatile content of 22.5%)
%) And the aqueous pigment dispersion obtained in Example 4 were blended so as to obtain 40 parts of “Hydran AP-40”, 20 parts of a pigment dispersing resin, 40 parts of pigment, and 10 parts of ethanol by weight of solid content. Was added to prepare a water-based ink of Example having a nonvolatile content of 20%.

This ink was coated on a corona discharge treated PET film with No. 7 with a bar coater, 60
It dried at 1 degreeC for 1 minute, and produced the sample of the Example.

<Comparative Examples 15 and 16>
Comparative Examples 7 and 8 in place of the aqueous pigment dispersion obtained in Example 4
A water-based ink of a comparative example having a nonvolatile content of 20% was prepared in the same manner as in Example 8, except that the aqueous pigment dispersion obtained in the above was used.

In the same manner as in Example 8, Comparative Examples 15 and 16
Of No. on a corona discharge treated PET film.
7 was coated with a bar coater and dried at 60 ° C. for 1 minute to prepare a sample of a comparative example.

<Evaluation> (1) Volume Average Particle Diameter The volume average particle diameter of the aqueous pigment dispersion obtained in each of the Examples and Comparative Examples immediately after preparation and after standing at room temperature for 30 days was as follows:
The measurement was performed using "UPA-150" (laser Doppler type particle size distribution analyzer manufactured by JGC Corporation). The results are summarized in Table 1.

[0111]

[Table 1]

In the column of pigment in Table 1, RG is “fastogen super magenta RG” and Y4181
Is "Shimla Fast Yellow 8GTF", FG
F wrote "Fastogen Blue FGF" to ATY-
01 is "Fastogen Super Red ATY-
01 "respectively. (All manufactured by Dainippon Ink and Chemicals, Inc.)

From the results shown in Table 1, when these pigments were not subjected to acid precipitation, as shown in Comparative Examples 2, 4, 6 and 8,
It can be seen that the particle size is large and the stability is quite poor. On the other hand, when acid precipitation is performed, as in Comparative Examples 1, 3, 5, and 7, the particle diameter is relatively small, and the stability is also improved.
Further, it can be seen that the surface treatment of these pigments significantly reduces the particle diameter and improves the stability as in Examples 1 to 4.

(2) Evaluation of Baking Coating The coatings obtained in Examples 5 to 8 and Comparative Examples 9 to 16 were evaluated as follows. Table 2 shows the results of the water-soluble acrylic resin baking coating, and Table 3 shows the results of the water-soluble polyester resin baking coating.

Gloss: The thing coated on “BT-144 treated steel sheet” was measured at 60 ° specular gloss.

Color development: The thing coated on a PET film was visually judged. Evaluation criteria ◎: High color density and high concealability. ：: Color density and concealability are slightly inferior. Δ: The color density and the concealability were considerably poor. X: The color density and the concealability were considerably poor, and the sharpness was also low.

Water resistance: The coated BT-144 treated steel sheet was immersed in water at a temperature of 50 ° C., and after 48 hours, the degree of blister generation was visually determined. Evaluation criteria A: No abnormality. ：: Blister generation was slightly observed. Δ: Significant blister generation was observed. ×: Blisters were generated on the entire surface of the test piece.

[0118]

[Table 2]

[0119]

[Table 3]

From the results shown in Tables 2 and 3, the paint using the aqueous pigment dispersion obtained by the production method of the present invention showed gloss,
It can be understood that the coloring property and the water resistance are excellent.

(3) Evaluation of aqueous inks The aqueous inks obtained in Example 8 and Comparative Examples 15 and 16 were evaluated as follows, and the results are shown in Table 4.・ Gloss: 60 ° mirror gloss ・ Coloring property: Same evaluation as for baking paint

[0122]

[Table 4]

From the results shown in Table 4, it can be understood that the aqueous ink using the aqueous pigment dispersion obtained by the production method of the present invention is excellent in gloss and coloring.

[0124]

The aqueous pigment dispersion obtained according to the production method of the present invention uses a pigment which has been treated with an active energy ray and / or an active gas, and is finely dispersed by acid precipitation. And has excellent storage stability,
Further, when used in water-based paints, water-based inks, etc., they are excellent in glossiness, coloring properties and coloring power, and are also excellent in water resistance, and are extremely practical.

Continued on the front page (72) Inventor Nagayuki Takao 3-8-19 Matsugaoka, Ryugasaki, Ibaraki

Claims (10)

[Claims] An acid value based on a carboxyl group is 30 to 1
The water-containing cake (C) comprising the resin (A) and the active energy ray-treated and / or active gas-treated pigment (B) in the range of 20 is converted into a part of the carboxyl group by using a basic compound (D1). 10 to 500 n characterized by being dispersed in an aqueous medium by neutralizing everything
A method for producing an aqueous pigment dispersion having a volume average particle diameter in the range of m. 2. An acid value based on a carboxyl group of 30 to 1
A step (1a) of kneading the resin (A) in the range of 20 and the pigment (B) treated with the active energy ray and / or the active gas in an organic solvent medium;
2) a step (2) of neutralizing a part or all of the carboxyl groups and dispersing in an aqueous medium, and precipitating the resin (A) by neutralizing or acidifying the pH with an acidic compound (E) 2. A hydrated cake obtained by a production method comprising the step (3) of causing the mixture to adhere to a pigment.
A method for producing the aqueous pigment dispersion according to the above. 3. An acid value based on a carboxyl group of 30 to 1
A part of or all of the carboxyl groups of the resin (A) in the range of 20 is neutralized with the basic compound (D2), and the pigment (B) treated with the active energy ray and / or the active gas is converted into an aqueous medium. In which the resin (A) is precipitated by neutralizing or acidifying the pH with an acidic compound (E) and fixing to the pigment (3). The method for producing an aqueous pigment dispersion according to claim 1, wherein the obtained water-containing cake is used. 4. A pigment obtained by irradiating an active energy ray-treated and / or active gas-treated pigment (B) with an active energy ray in the presence of a gas which reacts with the surface of the pigment during irradiation with the active energy ray The method for producing an aqueous pigment dispersion according to claim 1, 2, or 3. 5. The method for producing an aqueous pigment dispersion according to claim 1, wherein the resin (A) is a vinyl copolymer. 6. A compound having a number average molecular weight of 5,000 to 20,000.
The method for producing an aqueous pigment dispersion according to claim 4, wherein a vinyl copolymer in the range of 0 is used. 7. The method for producing an aqueous pigment dispersion according to claim 1, wherein the resin (A) is a polyester resin or a polyurethane resin. 8. The method for producing an aqueous pigment dispersion according to claim 1, wherein the resin (A) is a resin having a hydroxyl group. 9. The method for producing an aqueous pigment dispersion according to claim 3, wherein the pigment (B) that has been subjected to the active energy ray treatment and / or the active gas treatment is an aqueous slurry or press cake thereof. 10. An aqueous colorant composition containing the aqueous pigment dispersion produced by the production method according to claim 1.