JPH051301B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aqueous pigment dispersion that uses a novel dispersant and has excellent dispersibility and dispersion stability. Conventionally, in water-based paints such as emulsion paints and water-soluble resin paints containing pigments, there has been a decrease in the coloring effect of the painted surface due to the difficulty of dispersing the pigments during manufacture and agglomeration/sedimentation of the pigments during storage.
It is well known that undesirable phenomena such as floating (floating mottling) and reduction in gloss occur. For this reason, generally, an aqueous pigment dispersion is prepared by dispersing the pigment in advance with a dispersant, and this is mixed and dispersed in the aqueous paint to be colored to color the aqueous paint. In conventional aqueous pigment dispersions, low molecular weight compounds such as surfactants are used as dispersants, but these dispersants have negative effects, such as secondary adverse effects such as deterioration of coating performance or coating condition. This is unavoidable, and in recent years, oligomers or polymers having a medium molecular weight have been used as dispersants to suppress the deterioration of coating film performance. However, when oligomers or polymers are used as dispersants, the amount used is larger than that of low-molecular surfactants, and the use of the resulting aqueous pigment dispersion is dependent on the type of binder used in water-based paints. Therefore, there are drawbacks such as limitations. This goes against the rationalization of paint manufacturing, and there is therefore a strong demand for the development of a water-based pigment dispersion that is common to various water-based paints. Therefore, the present inventors have developed an ideal dispersion that allows pigments to be easily dispersed in small amounts, is compatible with various water-based resins, and is polymeric in itself and does not cause a decline in the coating performance of water-based paints. The present invention was completed as a result of intensive research aimed at developing a particularly difficult aqueous system. Thus, according to the present invention, in an aqueous pigment dispersion comprising a pigment, a dispersant, and an aqueous medium, the dispersant is (A) an oil/fat fatty acid modified (meth)acrylic monomer (hereinafter referred to as "fatty acid modified"). (referred to as "meth)acrylic monomer") 3 to 98 parts by weight (B) Monomer having a nitrogen-containing heterocycle 2 to 97 parts by weight (C) α,β-ethylenically unsaturated carboxylic acid
0 to 20 parts by weight, and (D) 0 to 91 parts by weight of α,β-ethylenically unsaturated monomers other than the above (A) to (C). Provided is an aqueous pigment dispersion characterized by being a water-soluble product of a polymer obtained by copolymerizing. The polymer used as a dispersant for the aqueous pigment dispersion of the present invention is a non-crystalline and lipophilic long side chain containing a monomer having a hydrophilic nitrogen-containing heterocycle and an α,β-ethylenic monomer. Because it has a structure in which it is bonded in a separate form to the main chain containing unsaturated carboxylic acid, it has very high pigment dispersion ability. Furthermore, since the polymer contains both basic components derived from nitrogen-containing heterocycles and acidic components derived from carboxylic acids, it has the advantage that it is possible to disperse a wide range of pigments such as acidic pigments and basic pigments. ing. In addition, this dispersant has excellent pigment dispersion ability and has a relatively low acid value, that is, a small absolute amount of carboxyl groups, so it has excellent properties such as corrosion resistance and can produce a good colored coating film. be able to. Hereinafter, the dispersant used in the aqueous pigment dispersion of the present invention will be explained in more detail. Fatty acid modified (meth)acrylic monomer (A) Fatty acid modified (meth)acrylic monomer used in the present invention
The acrylic monomer (A) is a (meth)acrylic monomer as described below, a drying oil fatty acid, a semi-drying oil fatty acid,
It is a monomer produced by introducing fatty acids such as non-drying oil fatty acids by the method described below. Typical fatty acids that can be used in the present invention include, for example, safflower oil fatty acid, linseed oil fatty acid, soybean oil fatty acid, sesame oil fatty acid, poppy oil fatty acid, eno oil fatty acid, hempseed oil fatty acid, grape kernel oil fatty acid, and corn oil fatty acid. , tall oil fatty acids,
Drying and semi-drying oil fatty acids such as sunflower oil fatty acids, cottonseed oil fatty acids, walnut oil fatty acids, rubberseed oil fatty acids, tung oil fatty acids, oiticica oil fatty acids, dehydrated castor oil fatty acids, hygienic fatty acids; and coconut oil fatty acids, olive oil fatty acids, Examples include non-drying oil fatty acids such as castor oil fatty acids, hydrogenated castor oil fatty acids, and palm oil fatty acids; each of these fatty acids can be used alone or in a mixture of two or more. The amount of the fatty acid used can vary widely depending on the drying properties and coating performance desired for the aqueous pigment dispersion provided by the present invention, but in general,
It is advantageous to use amounts ranging from 5 to 65% by weight, preferably from 10 to 60% by weight, based on the weight of the polymer obtained. In addition, in the present invention, it is preferable because it can impart crosslinking drying properties at room temperature to a dispersant that yields drying oil fatty acids and semi-drying oil fatty acids having an iodine value of about 100 or more among the above-mentioned fatty acids. The (meth)acrylic monomer into which such a fatty acid is introduced is an ester of acrylic acid or methacrylic acid containing a functional group capable of reacting with the carboxyl group of the fatty acid, such as an epoxy group or a hydroxyl group, in the ester residue portion. I can give an example. Therefore, one type of (meth)acrylic monomer into which the fatty acid described above is introduced to obtain the fatty acid-modified (meth)acrylic monomer (A) is "acrylic ester having an epoxy group or methacrylic acid ester". ester” (hereinafter referred to as “epoxy-containing (meth)
(sometimes abbreviated as "acrylic acid ester"), and as this type of ester, those containing a glycidyl group in the ester residue of acrylic acid or methacrylic acid, particularly glycidyl acrylate and glycidyl methacrylate, are suitable. .
The fatty acid-modified acrylic monomer (A) using such an epoxy-containing acrylic ester is prepared in accordance with a conventional method, in the presence or absence of a suitable inert solvent, usually in the absence of a solvent. This can be done by reacting a saturated fatty acid with an epoxy-containing acrylic ester. The reaction generally takes about 60
It can be carried out at a temperature of from about 220°C to about 170°C, preferably from about 120 to about 170°C, and the reaction time is generally about
0.5 to about 40 hours, preferably about 3 to about 10 hours. The epoxy-containing acrylic ester is usually
It is advantageous to use a proportion of 0.7 to 1.5 mol, preferably 0.8 to 1.2 mol, per mol of unsaturated fatty acid. In addition, as the inert solvent used as necessary, water-immiscible organic solvents that can be refluxed at a temperature of 220°C or lower are preferred, such as aromatic hydrocarbons such as benzene, toluene, and xylene; heptane, Examples include aliphatic hydrocarbons such as hexane and octane. Furthermore, in the above reaction, a polymerization inhibitor such as hydroquinone, methoxyphenol, tert-butylcatechol, benzoquinone, etc. is added to the reaction system as necessary to produce a hydroxyl group-containing acrylic ester and/or a fatty acid-modified acrylic resin. It is advantageous to suppress the polymerization of the ester. In the above reaction, esterification accompanied by cleavage of the oxirane ring occurs between the oxirane group (epoxy group) of the epoxy-containing acrylic ester and the carboxyl group of the fatty acid, and an acrylic ester modified with the fatty acid is obtained. Another type of fatty acid-modified acrylic monomer
The (meth)acrylic monomer that is reacted with the above fatty acid to produce (A) is "acrylic ester or methacrylic ester containing a hydroxyl group"
(hereinafter sometimes abbreviated as "hydroxyl group-containing acrylic ester"), and this type of ester includes one hydroxyl group in the ester residue of acrylic acid or methacrylic acid, and Those containing 2 to 24, preferably 2 to 8 carbon atoms in the radical moiety are included, and among them, the following formula () or () In each of the above formulas, R ₁ represents a hydrogen atom or a methyl group, n is an integer of 2 to 8, p and q are each an integer of 0 to 8, provided that the sum of p and q is 1 to 8. Hydroxyl group-containing acrylic esters of the type shown below are suitable. Particularly suitable hydroxyl group-containing acrylic esters in the present invention include hydroxyalkyl acrylates and hydroxyalkyl methacrylates represented by the above formula (), particularly 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate and 2-hydroxypropyl acrylate.
-Hydroxypropyl methacrylate. The latter type of fatty acid-modified acrylic monomer (A)
The preparation can usually be carried out by reacting the fatty acid with the hydroxyl group-containing acrylic ester in an appropriate inert solvent in the presence of an esterification catalyst. The reaction generally takes about 100 to about 180
C, preferably about 120 to about 160 C, and the reaction time is generally about 0.5 to about 9 hours.
Usually about 1 to about 6 hours. The hydroxyl group-containing acrylic ester can usually be used at a ratio of 0.5 to 1.9 mol per mol of the fatty acid, preferably 1.0 mol per mol of the fatty acid.
It is advantageous to use a proportion of ~1.5 mol. Examples of the esterification catalyst used in the above reaction include sulfuric acid, aluminum sulfate, potassium hydrogen sulfate, p-toluenesulfonic acid, hydrochloric acid, methyl sulfate, and phosphoric acid. It is used in a proportion of about 0.001 to about 20% by weight, preferably about 0.05 to about 1.0% by weight of the total amount of the fatty acid and hydroxyl group-containing acrylic ester. In addition, as the inert solvent used as necessary, water-immiscible organic solvents that can be refluxed at a temperature of 180°C or lower are preferred, such as aromatic hydrocarbons such as benzene, toluene, and xylene; heptane, Examples include aliphatic hydrocarbons such as hexane and octane. Furthermore, in the above reaction, a polymerization inhibitor such as hydroquinone, methoxyphenol, tert-butylcatechol, benzoquinone, etc. is added to the reaction system as necessary to produce a hydroxyl group-containing acrylic ester and/or a fatty acid-modified acrylic resin. It is advantageous to suppress the polymerization of the ester. In the above reaction, esterification occurs between the hydroxyl group of the hydroxyl group-containing acrylic ester and the carboxyl group of the fatty acid, and an acrylic ester modified with a fatty acid is obtained. As yet another method for preparing the fatty acid-modified acrylic monomer (A), in addition to the method described above, glycidyl esters of unsaturated fatty acids (for example, "Blemmer DFA" manufactured by NOF Corporation), acrylic acid or methacrylic It is also possible to esterify the acid as described above. Vinyl monomer (B) having a nitrogen-containing heterocycle: Next, the vinyl monomer (B) having a nitrogen-containing heterocycle used in the present invention has 1 to 3 rings, preferably 1 or 2 rings. Monomers in which a monocyclic or polycyclic heterocycle containing a nitrogen atom is bonded to a vinyl group are included, and in particular, the monomers shown below can be mentioned. () Vinylpyrrolidones; For example, 1-vinyl-2-pyrrolidone, 1-vinyl-3-pyrrolidone, etc. () Vinylpyridines; For example, 2-vinylpyridine, 4-vinylpyridine, 5-methyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine, etc. () Vinylimidazoles; For example, 1-vinylimidazole, 1-vinyl-2-methylimidazole, etc. () Vinylcarbazoles; For example, N-vinylcarbazole. () Vinylquinolines; For example, 2-vinylquinoline. () Vinylpiperidines; For example, 3-vinylpiperidine, N-methyl-
3-vinylpiperidine, etc. Among the above-mentioned vinyl monomers having a nitrogen-containing heterocycle, vinyl pyrrolidones, vinyl imidazoles and vinyl carbazoles are preferable, and among them, those in which the ring nitrogen atom is tertiary are preferable. α,β-Ethylenically unsaturated carboxylic acid (C): Next, the α,β-ethylenically unsaturated carboxylic acid (C) used in the present invention consists of the carbon atom to which the carboxyl group is bonded and the carbon atom adjacent to it. An unsaturated aliphatic mono- or polycarboxylic acid having an addition-polymerizable double bond between
Those containing ~8, especially 3 to 5 carboxyl groups and 1 or 2 carboxyl groups are suitable, and have the following general formula () In the formula, R ₂ represents a hydrogen atom or a lower alkyl group, R ₃ represents a hydrogen atom, a lower alkyl group, or a carboxyl group, and R ₄ represents a hydrogen atom, a lower alkyl group, or a carboxy lower alkyl group. things are included. In the above formula (), the lower alkyl group is preferably one having 4 or less carbon atoms, particularly a methyl group. Examples of such α,β-ethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, and fumaric acid, each of which may be used alone or in combination. The above can be used in combination. Other α, β-ethylenically unsaturated monomers (D): Furthermore, there are no particular restrictions on the α, β-ethylenically unsaturated monomers (D) other than the above (A) to (C). can be selected from a wide range depending on the desired performance of the dispersant of the present invention. Representative examples of such unsaturated monomers are as follows. (a) Esters of acrylic acid or methacrylic acid, such as methyl acrylate, ethyl acrylate,
Propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate,
C1 _~ of acrylic acid or methacrylic acid such as octyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate, etc. ₁₈
Alkyl ester; glycidyl acrylate,
Glycidyl methacrylate; _C2-18 alkoxyalkyl ester of acrylic acid or methacrylic acid, such as methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, ethoxybutyl methacrylate;
_C2-8 alkenyl esters of acrylic acid or methacrylic acid such as allyl acrylate, allyl methacrylate; hydroxyethyl acrylate,
_C2-8 hydroxyalkyl esters of acrylic acid or methacrylic acid such as hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate; acrylic acid or methacrylic acid such as diethylaminoethyl acrylate, diethylaminoethyl methacrylate, methylaminoethyl acrylate, methylaminoethyl methacrylate Mono- or di-C _1-8 alkylaminoalkyl esters of acids; C _3-18 alkenyloxyalkyl esters of acrylic acid or methacrylic acid, such as allyloxyethyl acrylate, allyloxymethacrylate. (b) Vinyl aromatic compounds: e.g. styrene, α
-Methylstyrene, vinyltoluene, p-chlorostyrene. (c) Polyolefin compounds: for example, butadiene, isoprene, chloroprene. (d) Amides of acrylic or methacrylic acid: for example acrylamide, N-methylolacrylamide, N-butoxymethylacrylamide. (e) Others: Acrylonitrile, methacrylonitrile, methyl isopropenyl ketone, vinyl acetate, Beoba monomer (Siel Chemicals), vinyl propionate, vinyl pivalate, etc. Among these monomers, excluding the last-mentioned beoba monomer, the Q value in the Qe theory (the theory of addition reaction rate constant of monomers to radicals proposed by T. Alfrey and C. Price) is 0.1 or more. Especially preferred are esters of acrylic acid or methacrylic acid and vinyl aromatic compounds. These unsaturated monomers are appropriately selected depending on the desired physical properties, and may be used alone or in combination of two or more. According to the present invention, the above fatty acid-modified acrylic monomer (A), a vinyl monomer having a nitrogen-containing heterocycle
(B), the α,β-ethylenically unsaturated carboxylic acid (C) and the unsaturated monomer (D) are copolymerized with each other. The copolymerization is carried out according to methods known per se for producing acrylic copolymers, such as solution polymerization,
This can be carried out using an emulsion polymerization method, a suspension polymerization method, or the like. The blending ratio of the above four components in copolymerization can be changed depending on the desired performance as a dispersant, but it is appropriate to mix them in the following ratios. Fatty acid-modified acrylic monomer (A): 3 to 98 parts by weight, preferably 10 parts by weight from the viewpoint of coating film drying properties and coating film performance.
~85 parts by weight, vinyl monomer (B) having nitrogen-containing heterocycle: 2-97
Parts by weight, preferably 3 to 90 from the viewpoint of pigment dispersion
Part by weight, α,β-ethylenically unsaturated carboxylic acid (C): 0~
20 parts by weight, preferably 2 to 18 parts by weight in terms of water solubility and coating film performance, unsaturated monomer (D) other than the above (A) to (C): 0 to 91 parts by weight, preferably coating film 5 to 83 parts by weight in terms of performance. The above copolymerization reaction is preferably carried out according to a solution polymerization method, in which the above four components are mixed in a suitable inert solvent in the presence of a polymerization catalyst, usually at about 0 to about 180°C, preferably. at a reaction temperature of about 40 to about 170°C for about 1 to about 20 hours, preferably about 6 to about 20 hours.
This can be carried out by continuing the reaction for about 10 hours. As the solvent used, it is desirable to use a solvent that can dissolve the produced copolymer and is miscible with water so that gelation does not occur during the copolymerization reaction. Particularly preferred is one that can be used as is without being removed when obtaining an aqueous pigment dispersion. Examples of such solvents include cellosolve solvents of the formula HO-CH ₂ CH ₂ -OR ₅ [wherein R ₅ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms], such as ethylene glycol, butyl cellosolve, and ethyl cellosolve. etc; expression

[Formula] [However, R ₅ has the same meaning as above] Propylene glycol solvent such as propylene glycol monomethyl ether; Formula HO-
Carbitol solvents of CH ₂ CH ₂ −OCH ₂ CH ₂ −OR ₅ [wherein R ₅ has the same meaning as above] such as diethylene glycol, methyl carbitol, butyl carbitol; formula R ₆ O−CH ₂ CH ₂
-OR ₇ [However, R ₆ and R ₇ each represent an alkyl group having 1 to 3 carbon atoms] Glyme solvent such as ethylene glycol dimethyl ether; formula R ₆ O-CH ₂ CH ₂ OCH ₂ -CH ₂ OR ₇ [However,
R ₆ and R ₇ have the same meanings as above] diglyme solvent such as diethylene glycol dimethyl ether; formula R ₈ O-CH ₂ CH ₂ OCO-CH ₃
[However, R ₈ is a hydrogen atom, CH ₃ or C ₂ H ₅
cellosolve acetate solvents with the formula R ₉ OH [wherein R ₉
represents an alkyl group having 1 to 4 carbon atoms], such as ethanol, propanol, etc.; and diacetone alcohol, dioxane, tetrahydrofuran, aton, dimethylformamide, 3-methoxy-3-methyl-butanol, etc. Can be used. However, it is also possible to use inert solvents that are immiscible with water, and such water-immiscible solvents include those with a boiling point below 250°C so that they can be easily removed by distillation under normal or reduced pressure after the completion of the polymerization reaction. is preferred. Such solvents include, for example, the formula

[Formula] [However, R ₁₀ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms] or the formula

Aromatic hydrocarbons represented by the formula [where R ₁₁ and R ₁₂ each represent an alkyl group having 1 to 4 carbon atoms], such as toluene,
Xylene, etc.; Formula R ₁₃ −COO−R ₁₄ [However, R ₁₃
represents an alkyl group having 1 to 6 carbon atoms,
R ₁₄ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a cyclohexyl group], such as acetic acid, ethyl formate, butyl acetate, cyclohexyl acetate, etc.; formula
R ₁₅ R ₁₆ C=0 [However, R ₁₅ and R ₁₆ each represent an alkyl group having 1 to 8 carbon atoms] and

Ketones represented by [formula], such as methyl ethyl ketone, cyclohexanone, etc.;
Ethers represented by R ₁₅ -O-R ₁₆ [wherein R ₁₅ and R ₁₆ have the same meanings as above], such as ethyl ether, hexyl ether, etc.;
Alcohols represented by R ₁₇ OH [wherein R ₁₇ represents an alkyl group having 5 to 11 carbon atoms],
Examples include hexanol. These solvents are based on the total weight of the four copolymer components.
It can be used in a range of 15-90% by weight. Examples of polymerization catalysts include azo compounds, peroxide compounds, sulfides, sulfin compounds, sulfinic acids, diazo compounds, nitroso compounds, redox compounds, and radical initiators that can be used in normal radical polymerization such as ionizing radiation. is used. In the present invention, a substantially satisfactory aqueous pigment dispersion can be obtained even if the molecular weight of the copolymer to be produced changes, but if the molecular weight is too low, there is a risk of deterioration of the physical properties of the water-based paint to be colored. be.
In addition, if the molecular weight is too high, the viscosity will increase, and if the viscosity is lowered, the concentration of the copolymer will decrease and the dispersibility of the pigment will decrease.
The number average molecular weight of the copolymer produced is approximately 500 to approximately
150,000, preferably within the range of about 1,000 to about 100,000. The copolymer resin thus produced can be made water-soluble as it is or after distilling off the solvent. This water solubility can be achieved by a conventional method, for example, by neutralizing the carboxyl groups present in the copolymer resin with a conventionally known neutralizing agent. Examples of neutralizing agents that can be used include ammonia, amines, alkali metal hydroxides, alkali metal carbonates or bicarbonates, and the like.
As the amine, primary, secondary or tertiary alkylamines; primary, secondary or tertiary alkanolamines; and cycloalkylamines can be used. Also, examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide;
As the alkali metal carbonate and bicarbonate, potassium carbonate, sodium carbonate, sodium bicarbonate, etc. can be used. Among these neutralizing agents, potassium hydroxide and sodium hydroxide are particularly preferred. The neutralization treatment can be easily carried out by a conventional method by adding the neutralizing agent or an aqueous solution thereof to the copolymer resin or its solution obtained as described above. The amount of neutralizing agent used is generally 0.01 to 2.0 equivalents, preferably 0.3 to 2.0 equivalents based on the carboxyl group in the resin.
It is 1.0 equivalent. The water-solubilized polymer thus obtained is used as a dispersant in an aqueous pigment dispersion consisting of a pigment, a dispersant, and an aqueous medium. The amount of the dispersant made of the water-solubilizing polymer used is generally about 1 to 500 parts by weight per 100 parts by weight of the pigment.
Preferably, it can be about 1 to 300 parts by weight.
When the upper limit of this range is exceeded, the balance between coloring power and viscosity of the aqueous pigment dispersion tends to become imbalanced, while when it is outside the lower limit, the dispersion stability of the pigment tends to decrease. The aqueous medium used in the aqueous pigment dispersion of the present invention is essentially water, but if necessary,
For example, if the degree of hydrophilicity of the dispersant is low and sufficient pigment dispersion performance cannot be obtained, a hydrophilic organic solvent can be used in combination. As the hydrophilic organic solvent, those used in the production of the polymer can be used alone or in combination. Furthermore, the pigments used in the aqueous pigment dispersion of the present invention can be inorganic and organic pigments commonly used in this type of pigment dispersion. (zinc white, titanium dioxide, red iron oxide, chromium oxide, cobalt blue, iron black, etc.); (2) hydroxide type (alumina white,
(yellow iron oxide, etc.); (3) sulfides, selenide-based (zinc sulfide, vermilion, cadmium yellow, cadmium red, etc.); (4) ferrocyanide-based (dark blue, etc.); (5) chromate-based (yellow (lead, zinc chromate, molybdenum lead, etc.); (6) Sulfate type (precipitated barium sulfate, etc.);
(7) Carbonate-based (precipitated calcium carbonate, etc.); (8) Silicate-based (hydrated silicates, clay, ultramarine, etc.); (9) Phosphate-based (manganese violet, etc.); (10) Carbon Examples of organic pigments include (1) nitroso pigments (naphthol green B, etc.); (2) metal powders (aluminum powder, bronze powder, zinc powder, etc.); ) Nitro pigments (Naphthol Yellow S, etc.); (3) Azo pigments (Resol Red,
Lake Red C, Fast Yellow, Naphthol Red, Red, etc.); (4) Dyeing Lake Pigment system (Alkali Blue Lake, Rhodamine Lake, etc.); (5) Phthalocyanine pigment system (Phthalocyanine Blue, Fast Sky Blue, etc.); (6) Condensed polycyclic pigment systems (perylene red, quinacridone red, dioxazine violet, isoindolinone yellow, etc.) are included. The content of the pigment in the aqueous pigment dispersion of the present invention is not particularly technically limited, but is generally about 2 to 90% by weight based on the weight of the dispersion. The aqueous pigment dispersion of the present invention can be prepared by mixing together the above-mentioned components in a suitable dispersion device, and the dispersion devices that can be used include those commonly used in the paint industry. Examples include ball mills, roll mills, homomixers, sand grinders, sheakers, and attritors. If necessary, conventionally known surfactants and protective colloids can be added to the aqueous pigment dispersion of the present invention. The aqueous pigment dispersion of the present invention thus obtained is
The pigment is very uniformly and finely dispersed, and there is almost no aggregation or sedimentation of the pigment particles even when stored for a long time. This is presumed to be because the lipophilic part of the dispersant is adsorbed on the surface of the pigment, and the hydrophilic part dissolves in the aqueous medium, so that the pigment is stably dispersed in the aqueous medium. Therefore, the aqueous pigment dispersion of the present invention has alkyd resins used in water-based paints and inks,
It has good miscibility with conventionally known water-soluble resins, water-dispersible resins, emulsions, etc. such as acrylic resins, epoxy resins, urethane resins, maleated polybutadiene resins, etc., and there are no restrictions due to these resins, and it can be used with any of the following. It can also be widely used for coloring water-based paints made of resin. As specific examples of the above-mentioned water-based resins, for example, alkyd resins are synthesized from the same raw materials as conventional solvent-based alkyd resins, and include polybasic acids, polyhydric alcohols,
It is obtained by subjecting oil components to a condensation reaction using a conventional method. Acrylic resins include α,β-ethylenically unsaturated acids (e.g., acrylic acid, methacrylic acid, maleic acid, etc.), (meth)acrylic esters,
(e.g. ethyl acrylate, propyl acrylate,
butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, etc.) and vinyl aromatic compounds (for example, styrene, vinyltoluene, etc.). As an epoxy resin,
Epoxy esters are synthesized by the reaction between the epoxy groups of epoxy resins and unsaturated fatty acids, and α,β-unsaturated acids are added to these unsaturated groups. Examples include epoxy ester resins obtained by esterifying polybasic acids. In addition, as the urethane resin, polyisocyanate compounds (for example, toluene diisocyanate, diphenylmethane diisocyanate, 1,6
-Hexane diisocyanate, isophorone diisocyanate, etc.) to introduce a urethane group into the resin skeleton, and a carboxyl group using dimethylolpropionic acid or the like. When using the above-mentioned aqueous resin as water-soluble, it is synthesized so that the resin has an acid value of about 35 to 200, and this is neutralized with an alkaline substance such as sodium hydroxide or amine to make it water-soluble. Served for paint. On the other hand, when these resins are used in a self-dispersion type, the acid value of the resin is made into a low acid value resin of about 5 to 35, and this resin is neutralized and used as a water-dispersed paint. In addition, emulsions include emulsifier-dispersed emulsions obtained by dispersing alkyd resins, acrylic resins, epoxy resins, and urethane resins using anionic or nonionic low-molecular-weight surfactants; Emulsion polymerization emulsion obtained by emulsion polymerization of monomers such as acrylic acid ester, acrylonitrile, styrene, butadiene, vinyl acetate, vinyl chloride; maleated polybutadiene, maleated alkyd resin, maleated fatty acid modified vinyl resin, drying oil or Examples include soap-free emulsions obtained by emulsion polymerization and graft reaction of the above monomers using a water-soluble resin such as a semi-drying oil fatty acid modified acrylic resin as an emulsion stabilizer. The aqueous pigment dispersion of the present invention is particularly effective when blended into aqueous paints made of low acid value water-dispersible resins and emulsions that have poor pigment dispersibility. Among these, the effect is particularly remarkable for low acid value water-dispersible resins and emulsions that have oxidative curability. The blending ratio of the aqueous pigment dispersion of the present invention to the aqueous paint can be varied within a wide range depending on the type of pigment in the dispersion and the degree of coloring required for the final paint, but in general, The pigment dispersion can be blended in an amount of 2 to 1000 parts by weight per 100 parts by weight of the resin content of the aqueous paint. Next, the present invention will be further explained by examples.
In the examples, parts and % indicate parts by weight and % by weight. Example 1 (1-a) The following components: Safflower oil fatty acid 236 parts Glycidyl methacrylate 119 parts Hydroquinone 0.4 parts Tetraethylammonium bromide 0.2 parts were placed in a reaction vessel. The reaction is 140 while stirring.
The addition reaction product was obtained at a temperature of ~150°C.
The addition reaction between epoxy groups and carboxyl groups was monitored while measuring the amount of remaining carboxyl groups. The reaction took approximately 4 hours to complete. (1-b) 350 parts of n-butyl cellosolve was placed in a reaction vessel and heated to 120°C. Next, a mixture in the proportions shown below was added dropwise to this solution over about 2 hours. The reaction was carried out under nitrogen injection. Fat dispersion-modified monomer obtained in (1-a) above 113 parts N-vinylpyrrolidone 126 parts Acrylic acid 11 parts Azobisdimethylvaleronitrile 17.5 parts While keeping the reaction temperature at 120°C and stirring the reaction solution, the above The mixture was added dropwise. One hour after the completion of the dropwise addition, 2.5 parts of azobisisobutyronitrile was added to the reaction solution, and after another 2 hours, 2.5 parts of azobisisobutyronitrile was added to the reaction solution, and the reaction was then carried out while maintaining the temperature at 120°C for 2 hours. Summer. After the reaction was completed, unreacted monomers and n-butyl cellosolve were distilled under reduced pressure to obtain a copolymer solution with a heating residue of 70.1%, a resin acid value of 35.3, and a Gardner viscosity (40% n-butyl cellosolve solution) K. Furthermore, this copolymer was neutralized with triethylamine (1.0 equivalent neutralization), and water was added to obtain a dispersant () consisting of an aqueous solution with a heating residue of 40%. Next, a mixture of 8.3 parts of this dispersant and 200 parts of titanium white pigment (Titanium White R-5N manufactured by Sakai Chemical Co., Ltd.) was added to Red
Dispersion was carried out for 0.5 hours using a Devil disperser to obtain an aqueous pigment dispersion (A) of the present invention. Pigments were similarly dispersed according to the formulations shown in Table 1 below to obtain aqueous pigment dispersions (B) to (D) of the present invention.
Incidentally, pigments other than titanium white were dispersed for 1 hour. The properties of the obtained aqueous pigment dispersion are summarized in Table 1 below. Next, 10 parts of aqueous pigment dispersion (A) and water-dispersed alkyd resin (linseed oil fatty acid/pentaerythritol/benzoic acid/isophthalic acid/maleic anhydride =
Yucho made from 903/705/1140/610/45 (parts)
40% solids solution obtained by neutralizing 1.0 equivalent of alkyd resin with triethylamine and acid value 16)
Water-based paint (1) by thoroughly mixing a formulation consisting of 23.4 parts
was prepared. In the same way, the pigment dispersion liquid and the water-based resin shown in Table 2 below were sufficiently mixed to form a water-based paint (2).
~(6) was obtained. The coating film performance of the obtained water-based paint is summarized in Table 2 below. Example 2 (2-a) The following components: Safflower oil fatty acid 70.9 parts Hydroquinone 0.03 parts n-heptane 4.56 parts were placed in a reaction vessel, and the temperature was raised to 160°C while stirring. Next, a mixture of the following components: 41.2 parts of hydroxyethyl methacrylate, 0.03 parts of hydroquinone, 0.95 parts of dodecylbenzenesulfonic acid, and 3.7 parts of toluene was added dropwise into a reaction vessel at 160° C. over a period of 2 hours. When the generated condensation water is removed from the reaction system and the reaction product has an acid value of 5.5 and a Gardner viscosity of _A2 , the reaction vessel is reduced in pressure, toluene and n-heptane are removed under reduced pressure, and the acid value is 5.0 and the Gardner viscosity is A2. A fatty acid-modified acrylic monomer of _A1 was obtained. (2-b) 300 parts of n-butyl cellosolve was placed in a reaction vessel and heated to 120°C. Next, a mixture in the proportions shown below was added dropwise to this solution over about 2 hours. The reaction was carried out under nitrogen injection. Fatty acid modified monomer obtained in (2-a) above 75 parts n-butyl methacrylate 39 parts N-vinylpyrrolidone 125 parts acrylic acid 11 parts azobisdimethylvaleronitrile 18 parts The reaction temperature was maintained at 120°C and the reaction solution was The above mixture was added dropwise while stirring. One hour after the completion of the dropwise addition, 2.5 parts of azobisisobutyronitrile was added to the reaction solution, and after another 2 hours, 2.5 parts of azobisisobutyronitrile was added to the reaction solution, and the reaction was then continued while maintaining the temperature at 120°C for 2 hours. Summer. After the reaction, the unreacted monomer and n-butyl cellosolve were distilled under reduced pressure, and the heating residue was 70.0%, resin acid value 36.5, Gardner viscosity (40% n-butyl cellosolve solution) J
A copolymer solution was obtained. Furthermore, this copolymer was neutralized with triethylamine (1.0 equivalent neutralization),
Water was added to obtain a dispersant (2) consisting of an aqueous solution with a heating residue of 40%. Next, using the obtained dispersant (),
The pigment shown in Example 1 was dispersed in the same manner as in Example 1 to obtain an aqueous pigment dispersion E of the present invention. In addition, a water-based paint 7 was prepared by thoroughly mixing this pigment dispersion E with a water-based resin shown in Table 2 below. The properties of the pigment dispersion E and the coating performance of the water-based paint 7 are shown in Tables 1 and 2 below, respectively. Example 3 A monomer mixture of 85 parts of fatty acid-modified monomer obtained in (1-a), 150 parts of 2-vinylpyridine, and 15 parts of acrylic acid was subjected to a polymerization reaction according to the method described in Example 1. Heating residue 70.5%, resin acid value
A copolymer solution with a Gardner viscosity (40% n-butyl cellosolve solution) I of 45.6 was obtained. Neutralize this with triethylamine (1.0 equivalent neutralization),
A dispersant () consisting of an aqueous solution with a heating residue of 40% was obtained. Next, using the obtained dispersant (),
The pigment shown in Example 1 was dispersed in the same manner as in Example 1 to obtain an aqueous pigment dispersion F of the present invention. In addition, a water-based paint 8 was prepared by thoroughly mixing this pigment dispersion F and a water-based resin shown in Table 2 below. The properties of the pigment dispersion F and the coating performance of the water-based paint 8 are shown in Tables 1 and 2 below, respectively. Example 4 A polymerization reaction was carried out under the same conditions as in Example 3, except that the same amount of N-vinylcarbazole was used instead of 2-vinylpyridine in Example 3, and the heating residue was 71.0%, the resin acid value was 32.5, and the Gardner Viscosity (40
A copolymer solution of % n-butyl cellosolve solution) L was obtained. Next, this material was neutralized with triethylamine (1.0 equivalent neutralization) to obtain a dispersant consisting of an aqueous solution with a heating residue of 40%. Next, the pigments shown in Table 1 below were dispersed using the obtained dispersant in the same manner as in Example 1 to obtain an aqueous pigment dispersion G of the present invention. Further, a water-based paint 9 was prepared by sufficiently mixing this pigment dispersion G and the water-based resin shown in Table 2 below. The properties of the pigment dispersion G and the coating performance of the water-based paint 9 are shown in Tables 1 and 2 below, respectively. Example 5 A polymerization reaction was carried out under the same conditions as in Example 1 except that 1-vinylimidazole was used instead of N-vinylpyrrolidone in Example 1. 40%
n-Butyl cellosolve solution) A copolymer solution of N was obtained. Next, neutralize with triethylamine (1.0
(equivalent neutralization), a dispersant consisting of an aqueous solution with a heating residue of 40% was obtained. Next, the pigments shown in Table 1 below were dispersed using the obtained dispersant in the same manner as in Example 1 to obtain an aqueous pigment dispersion H of the present invention. In addition, a water-based paint 10 was prepared by thoroughly mixing this pigment dispersion H with a water-based resin shown in Table 2 below. The properties of the pigment dispersion H and the coating film performance of the water-based paint 10 are shown in Tables 1 and 2 below, respectively. Comparative Example 1 Commercially available pigment dispersant SMA1440H (ARCO
Titanium White R-
10 parts of a pigment dispersion (pigment content 70.0%) prepared by dispersing 5N (titanium oxide manufactured by Sakai Chemical Co., Ltd., trade name) in a solid weight ratio of titanium white/dispersant = 22/1 and the table below - A water-based paint for comparison was obtained by mixing 17.5 parts of Emulsion B of No. 2. The coating film performance of this product is shown in Table 2 below.

【table】

【table】

【table】

[Coating film performance test]

Add a water-based dryer (trade name: "Deiknate", manufactured by Dainippon Ink Co., Ltd., cobalt metal content: 3%) to water-based paints (1) to (10) at a ratio of 1 part to 100 parts of resin solid content, and paint on a mild steel plate. did. 20℃, relative humidity 75%
After drying for 3 days, it was used for testing. Goban adhesion: Make 100 1mm wide goban stitches,
A test was carried out by pasting cellophane adhesive tape on it and peeling it off vigorously. Water resistance: The condition of the coated surface was visually examined by immersing it in tap water at 20°C for 2 days.

Claims (1)

[Scope of Claims] 1. An aqueous pigment dispersion comprising a pigment, a dispersant, and an aqueous medium, wherein the dispersant is (A) an oil/fat fatty acid modified (meth)acrylic monomer.
3 to 98 parts by weight (B) Monomer having a nitrogen-containing heterocycle 2 to 97 parts by weight (C) α,β-ethylenically unsaturated carboxylic acid
0 to 20 parts by weight, and (D) 0 to 91 parts by weight of α,β-ethylenically unsaturated monomers other than the above (A) to (C). An aqueous pigment dispersion characterized by being a water-soluble product of a polymer obtained by copolymerizing.