JPH0441195B2 - - 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 have been problems such as decreased coloring effect on the painted surface, flattening (floating),
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 comprises (A) a (meth)acrylic monomer modified with a lactone or an oxyacid condensate. ~98 parts by weight (B) α,β-ethylenically unsaturated nitrogen-containing monomer
2 to 97 parts by weight (C) α,β-ethylenically unsaturated carboxylic acid
0 to 20 parts by weight and (D) α, β-ethylenically unsaturated monomer other than the above (A), (B), (C) 0 to 91 parts by weight of the weight body obtained by copolymerizing An aqueous pigment dispersion is provided, which is a water-soluble pigment dispersion. The polymer used as a dispersant for the aqueous pigment dispersion of the present invention has a non-crystalline relatively linear long side chain bonded in a separate form to a main chain containing a hydrophilic nitrogen-containing monomer. Due to its structure, it has very high pigment dispersion ability. Further, by using the aqueous pigment dispersion of the present invention, it is possible to obtain a colored coating film with excellent properties such as corrosion resistance and adhesion. Hereinafter, the dispersant used in the aqueous pigment dispersion of the present invention will be explained in more detail. (Meth)acrylic monomer modified with lactone or oxyacid condensate (A): (meth)acrylic monomer modified with lactone or oxyacid condensate (hereinafter referred to as "modified (meth) ) acrylic monomer)
(A) is a monomer obtained by reacting a (meth)acrylic monomer with a lactone or oxyacid condensate, and is typically represented by the following formula () In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂
is a -C _n H _2n - group (where m is an integer from 2 to 8) or

[Formula] represents a group (where R ₄ represents a hydrogen atom or a methyl group), and R ₃
is -C _o H _2o group (where n is an integer from 2 to 18)
, p represents 1 to 7, and those shown are included. The lactone used as a modifier in the modified (meth)acrylic monomer represented by the above formula () is a cyclic ester compound containing an ester functional group -CO-O- in the ring, and a typical lactone Examples include γ-lactone, δ-lactone, ε-lactone, γ-caprolactone, δ-caprolactone, methyl ε-caprolactone (including isomers).
Examples include. In addition, the oxyacid condensate is a condensate of aliphatic monocarboxylic acid (hydroxy fatty acid) having one hydroxyl group in the molecule, and examples of the hydroxy fatty acid include ring-opened products of the lactone compounds described above, ricinoleic acid, oxyacid Examples include stearic acid and lanopalmitic acid. The condensates of these oxyacids are produced by a conventional method using a mixture of the above-mentioned hydroxy fatty acids, a refluxing solvent (xylene, toluene, heptane, etc.) and an esterification catalyst (methyl sulfuric acid, dodecylbenzenesulfonic acid, etc.) for about 140 to This can be carried out by heating and condensing at 250°C. The lactone compound or oxyacid condensate described above is introduced into the (meth)acrylic monomer as described below. In this introduction, the above-mentioned lactone compound or oxyacid condensate may be used alone, or two or more types may be used in combination. However, the (meth)acrylic monomer into which the lactone compound described above is introduced in order to obtain a lactone-modified (meth)acrylic monomer has one hydroxyl group in the ester residue and the ester Hydroxyl group-containing (meth)acrylic acid esters containing 2 to 8 carbonate atoms in the residue moiety are preferably used, and specifically, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate,
Examples include hydroxypropyl acrylate and 2-hydroxypropyl methacrylate. A lactone-modified (meth)acrylic monomer is produced using such a hydroxyl group-containing (meth)acrylic ester.
(A) can be prepared by a method known per se, for example, the method disclosed in JP-A-57-195714, and usually the lactone and a (meth)acrylic acid ester containing a hydroxyl group are used. The reaction can be carried out by reacting in the presence of a catalyst at about 20 to 220°C, preferably about 50 to 180°C. The reaction time is generally about 0.5 to 40 hours, preferably 5 to 20 hours. As a catalyst, an organic tin compound, an alkyl titanate, a lead compound, an acid catalyst, etc. are used. The molecular weight of the lactone-modified (meth)acrylic monomer thus obtained is 200 to 1500, preferably 400.
A range of 1,000 to 1,000 is advantageous, and the molecular weight can be easily adjusted by appropriately changing the blending ratio of lactone and hydroxyl group-containing (meth)acrylic ester. In addition, the (meth)acrylic monomer into which the above-mentioned oxyacid condensate is introduced to obtain the oxyacid condensate-modified (meth)acrylic monomer contains a glycidyl group (meth) in the ester residue moiety. ) Acrylic esters, especially glycidyl acrylate and glycidyl methacrylate, are preferably used. The oxyacid condensate-modified (meth)acrylic monomer (A) can be prepared by reacting the above-described oxyacid condensate with a glycidyl group-containing ester of (meth)acrylic acid. The reaction is generally carried out at a temperature of about 60-220°C, preferably about 120-220°C.
It can be carried out at a temperature of 170°C, and the reaction time is generally about 0.5 to 40 hours, preferably about 3 to 10 hours.
It's time. The glycidyl group-containing ester of (meth)acrylic acid is usually 0.7 to 1 mole of the oxyacid condensate.
It is advantageous to use a proportion of 1.5 mol, preferably 0.8 to 1.2 mol. In addition, the oxyacid condensate is
Advantageously, it has a molecular weight in the range from about 100 to 2500, preferably from about 200 to 2000. α,β-ethylenically unsaturated nitrogen-containing monomer (B) : Next, as the α,β-ethylenically unsaturated nitrogen-containing monomer (B) used in the present invention, one monomer per molecule is or monomers containing multiple (usually up to 4) basic nitrogen atoms and one ethylenically unsaturated bond; typical examples include unsaturated monomers having a nitrogen-containing heterocycle; and nitrogen-containing derivatives of (meth)acrylic acid. These monomers will be explained in more detail below. [1] The unsaturated monomer having a nitrogen-containing heterocycle is a monomer in which a monocyclic or polycyclic heterocycle containing 1 to 3, preferably 1 or 2 ring nitrogen atoms is bonded to a vinyl group. 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. () Vinylquinolinic acid; For example, 2-vinylquinoline. () Vinylpiperidines; For example, 3-vinylpiperidine, N-methyl-
3-vinylpiperidine, etc. () Other; For example, the expression

[Formula] (where R ₁ has the above meaning)
(meth)acryloylmorpholine, formula

N-(meth)acryloylpyrrolidine represented by the formula: (wherein R ₁ has the above meaning), 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. [2] Nitrogen-containing derivatives of (meth)acrylic acid include those containing a substituted or unsubstituted amino group in the ester moiety of (meth)acrylic ester and amides of (meth)acrylic acid,
Especially the following formula () or () In each of the above formulas, R ₅ and R ₆ each independently represent a hydrogen atom or a lower alkyl group, R ₇ represents a hydrogen atom or a lower alkyl group, and R ₃ represents a hydrogen atom, a lower alkyl group, or a di(lower alkyl) amino It represents a lower alkyl group, a hydroxy lower alkyl group or a lower alkoxy lower alkyl group, q represents an integer of 2 to 8, and R ₁ has the above meaning. Aminoalkyl (meth)acrylates and (meth)acrylamides of the formula are suitable. The term "lower" herein means that the group to which this term is attached has no more than 6 carbon atoms, preferably no more than 4 carbon atoms. Therefore, as specific examples of such nitrogen-containing (meth)acrylic monomers, examples of the aminoalkyl (meth)acrylate of the above formula () include NN-dimethylaminoethyl (meth)acrylate, N,
N-diethylaminoethyl (meth)acrylate, N-t-butylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-dimethylaminobutyl (meth)acrylate, N-propylaminoethyl (meth)acrylate, N-butylaminoethyl (meth)acrylate, etc. are included, and examples of (meth)acrylamide in the above formula () include (meth)acrylamide, N-methyl (meth)
Acrylamide, N-ethyl (meth)acrylamide, N-butyl (meth)acrylamide, N,
N-dimethyl(meth)acrylamide, N,N-
Diethyl (meth)acrylamide, NN-dipropyl (meth)acrylamide, N-methylol (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N,N-dimethylaminopropylacrylamide, etc. Included. As these nitrogen-containing (meth)acrylic monomers, those in which the existing nitrogen atoms are tertiary are optimal, and those in which the nitrogen atoms are secondary are also preferably used. The α,β-ethylenically unsaturated nitrogen-containing monomers described above can be used alone or in combination of two or more. Ethylenically unsaturated carboxylic acid (C) : Next, the ethylenically unsaturated carboxylic acid (C) used in the present invention has an addition polymerizable property between the carbon atom to which the carboxyl group is bonded and the adjacent carbon atom. unsaturated aliphatic mono- or polycarboxylic acids of the type with double bonds, 3 to 8 carbon atoms;
In particular, those containing 3 to 5 carboxyl groups and 1 or 2 carboxyl groups are suitable, and are typically represented by the following general formula () In the formula, R ₉ represents a hydrogen atom or a lower alkyl group, R ₁₀ represents a hydrogen atom, a lower alkyl group, or a carboxy group, and R ₁₁ represents a hydrogen atom, a lower alkyl group, or a carboxy lower alkyl group. and the following general formula () In the formula, R ₁ represents the above meaning, and γ represents an integer of 2 to 6. Contains the following: In the above formula (), the lower alkyl group is preferably one having 4 or less carbon atoms, particularly a methyl group. Examples of such ethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, 2-carboxyethyl (meth)acrylate, 2-carboxypropyl (meth)acrylate. acrylates, etc., each of which may be used singly or in combination.
More than one species can be used in combination. Other α, β-ethylenically unsaturated monomers (D) : Furthermore, α, β-ethylenically unsaturated monomers (D) other than the above (A), (B), and (C) include: There are no particular restrictions,
A wide range of choices can be made 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,
C ₁ ~ 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.
C ₁₈ alkyl ester; glycidyl acrylate, glycidyl methacrylate; methoxybutyl acrylate, methoxybutyl methacrylate,
C ₂ - C ₁₈ alkoxyalkyl esters of acrylic acid or methacrylic acid such as methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, and ethoxybutyl methacrylate; C of acrylic acid or methacrylic acid such as allyl acrylate and allyl methacrylate ₂ ~
_C3 alkenyl ester: _C2-8 hydroxyalkyl ester of acrylic acid or methacrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate; acrylic acid or methacrylic acid such as allyloxyethyl acrylate, allyloxymethacrylate _C3-18 alkenyloxyalkynyl esters of acids. (b) Vinyl aromatic compounds: e.g. styrene, α
-Methylstyrene, vinyltoluene, p-chlorostyrene. (c) Polyolefin compounds: for example, butadiene, isoprene, chloroprene. (d) Others: acrylonitrile, methacrylonitrile, methyl isopropenyl ketone, vinyl acetate, beoba monomer (Siel Chemicals), vinyl propionate, vinyl pivalate, etc. 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 modified (meth)acrylic monomer (A), the α,β-ethylenically unsaturated nitrogen-containing monomer (B), the ethylenically unsaturated carboxylic acid (C) and the unsaturated The monomers (D) are copolymerized with each other. The copolymerization can be carried out according to methods known per se for producing acrylic copolymers, such as solution polymerization, emulsion polymerization, suspension polymerization, and 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. (1) Modified (meth)acrylic monomer (A): 3 to 98 parts by weight, preferably 10 to 85 parts by weight in terms of coating film performance, (2) α,β-ethylenically unsaturated nitrogen-containing monomer Body (B):
2 to 97 parts by weight, preferably 3 to 90 parts by weight from the viewpoint of pigment dispersion, (3) Ethylenically unsaturated carboxylic acid (C): 0 to 20 parts by weight, preferably from the viewpoint of water solubility and coating performance. 2~
(4) Unsaturated monomer (D) other than the above (A) to (C): 0 to 91 parts by weight, preferably 5 to 83 parts by weight from the viewpoint of coating film 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 solution 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 the formula HO-CH ₂ CH ₂ -OR ₁₂ [wherein R ₁₂ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms]. ] cellosolve solvents such as ethylene glycol, butyl cellosolve,
Ethyl cellosolve etc.; formula

[Formula] [However, R ₁₂ has the same meaning as above] Propylene glycol solvent such as propylene glycol monomethyl ether; Formula HO-CH ₂ CH ₂ -OCH ₂ CH ₂ -OR ₁₂
[However, R ₁₂ has the same meaning as above] Carbitol-based solvents such as diethylene glycol, methyl carbitol, butyl carbitol, etc.; Formula R ₁₃ O-CH ₂ CH ₂ -OR ₁₄ [However, R ₁₃ and
Each R ₁₄ represents an alkyl group having 1 to 3 carbon atoms] Glyme solvent such as ethylene glycol dimethyl ether; formula R ₁₃ O-CH ₂
CH ₂ OCH ₂ -CH ₂ OR ₁₄ [However, R ₁₃ and R ₁₄ have the same meanings as above] Diglyme solvent such as diethylene glycol dimethyl ether; Formula R ₁₅ O-CH ₂ CH ₂ OCO-CH ₃ [However, _R15
represents a hydrogen atom, CH ₃ or C ₂ H ₅ ]
Cellosolve acetate solvents such as ethylene glycol monoacetate and tamel cellosolve acetate; alcohol solvents of the formula R ₁₆ OH [wherein R ₁₆ represents an alkyl group having 1 to 4 carbon atoms] such as ethanol, propanol, etc.; , diacetone alcohol, dioxane, tetrahydrofuran, acetone, dimethylformamide, 3-methoxy-3-methyl-butanol, and the like 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 ₁₇ 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 ₁₈ and R ₁₉ each represent an alkyl group having 1 to 4 carbon atoms], such as toluene,
Xylene, etc.; Formula R ₂₀ −COO−R ₂₁ [However, R ₂₀
represents an alkyl group having 1 to 6 carbon atoms,
_R21 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.;
Formulas R ₂₂ , R ₂₃ C ₂ O [wherein R ₂₂ and R ₂₃ 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 the formula R ₂₂ -O-R ₂₃ [wherein R ₂₂ and R ₂₃ have the same meanings as above], such as ethyl ether, hexyl ether, etc.;
Alcohols represented by R ₂₄ OH [wherein R ₂₄ 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. agent 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 above water-soluble polymer to be used is:
The amount may generally be from about 1 to 500 parts by weight, preferably from about 1 to 300 parts by weight per 100 parts by weight of pigment. 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); (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 type (perylene red,
quinacridone red, dioxazine violet, isoindolinone yellow, etc.). 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 pole 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 can contain 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 acid esters (e.g., ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, etc.). , ethyl methacrylate, propyl methacrylate, butyl methacrylate, etc.) and vinyl aromatic compounds (for example, styrene, vinyltoluene, etc.). Epoxy resins can be produced by synthesizing epoxy esters by reacting the epoxy groups of epoxy resin with unsaturated fatty acids, and adding α,β-unsaturated acids to this unsaturated group, or by combining the hydroxyl groups of epoxy esters with phthalic acid. Examples include epoxy ester resins obtained by a method of esterifying polybasic acids such as or trimellitic acid. In addition, as the urethane resin, polyisocyanate compounds (for example, toluene diisocyanate,
This is a resin in which urethane groups are introduced into the resin skeleton using diphenylmethane diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, etc.) and carboxyl groups are introduced into the resin skeleton using dimethylolpropionic acid or the like. When using the above-mentioned aqueous resin as water-soluble, the resin is synthesized to have an acid value of approximately 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 ester, acrylonitrile, styrene, butadiene, vinyl acetate, vinyl chloride; maleated polybutadiene, maleated alkyd resin,
Examples include soap-free emulsions obtained by emulsion polymerization and craft reaction of the monomers described above using water-soluble resins such as maleated fatty acid-modified vinyl resins, drying oils or semi-drying oil fatty acid-modified acrylic resins as emulsion stabilizers. 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. 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 % are parts by weight and % by weight, respectively.
shows. Example 1 300 parts of n-butyl cellosolve was placed in a reaction container,
It was heated to 120°C. Then 2 of the proportions shown below
The different mixtures were added dropwise to this solution separately over a period of about 2 hours. The reaction was carried out under nitrogen injection. Plaxel FM-3 [ε-caprolactone modified vinyl monomer manufactured by Daicel Chemical Co., Ltd. (In the above formula, R ₁ = CH ₃ , R ₂ = CH ₂ CH ₂ , R ₃ = CH ₂
CH ₂ CH ₂ CH ₂ CH ₂ , p=3) A mixture of 126 parts N,N-dimethylacrylamide 91 parts acrylic acid 33 parts and azobisdimethylvaleronitrile 18 parts n-butyl cellosolve 50 parts. The reaction temperature was maintained at 120° C., and the above mixture was added dropwise while stirring the reaction solution. 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 70.5%, a resin acid value of 91.1, and a Gardner viscosity (40% n-butyl cellosolve solution) P. 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 2 350 parts of n-butyl cellosolve was placed in a reaction vessel,
It was 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. Plaxel FM-5 [ε-caprolactone modified vinyl monomer manufactured by Daicel Chemical Co., Ltd. (In the above formula, R ₁ = CH ₃ , R ₂ = CH ₂ CH ₂ , R ₃ = CH ₂
113 parts N _{- vinylpyrrolidone} 126 parts acrylic acid ₁₁ parts azobisisobutyronitrile ₉ parts While keeping the reaction temperature at 120°C and stirring the reaction solution, The above 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 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 70.3%, the resin acid value was 34.8, and the Gardner viscosity (40% n-butyl cellosolve solution) G
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) and 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 (3-a) 2155 parts of 12-hydroxystearic acid, 383 parts of toluene, and 4.3 parts of monomethylsulfonic acid were placed in a reaction vessel, and the reaction was carried out at 145°C for about 4 hours while removing the condensed water produced from the system. Ta. Glycidyl methacrylate when the resin acid value reaches 34.0
221 parts, 2 parts of hydroquinone and 10 parts of tetraethylammonium bromide were added, and the reaction temperature was 145.
The reaction was carried out at ℃ for about 6 hours to obtain a reaction product having a resin acid value of 5.8. (3-b) The monomer mixture obtained in (3-a) 132 parts N-vinylpyrrolidone 126 parts 2-carboxyethyl acrylate (manufactured by Alcolac, USA) 11 parts azobisdimethylvaleronitrile 17.5 parts A polymerization reaction was carried out according to the method described in 1. Heating residue 71.0%, resin acid value
26.5, Gardner viscosity (40% A copolymer solution of n-butyl cellosolve solution D was obtained. This was neutralized with triethylamine (1.0 equivalent neutralization), and a dispersant () consisting of an aqueous solution with a heating residue of 40% was obtained. Next, using the obtained dispersant (), the following table -
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 sufficiently mixing this pigment dispersion (F) and the water-based resin shown in Table 2 below. The properties of the pigment dispersion (F) and the film 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,N-dimethylaminoethyl methacrylate was used instead of N-vinylpyrrolidone in Example 3, and the heating residue was 71.3% and the resin acid value
A copolymer solution with a Gardner viscosity (40% n-butyl cellosolve solution) E of 39.5 was obtained. Next, this material was neutralized with triethylamine (1.0 equivalent neutralization), and a dispersant () consisting of an aqueous solution with a heating residue of 40%
I got it. 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 (G) of the present invention. In addition, a water-based paint (9) was prepared by thoroughly mixing this pigment dispersion (G) with 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,N-dimethylacrylamide in Example 1, and the heating residue was 70.3%, the resin acid value was 86.7, and the Gardner A copolymer solution with a viscosity (40% n-butyl cellosolve solution) of Q was obtained. Next, it was neutralized with triethylamine (1.0 equivalent neutralization) to obtain a dispersant () 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 (H) of the present invention. Further, this pigment dispersion (H) and the water-based resin shown in Table 2 below were sufficiently mixed to prepare a water-based paint (10). The properties of the pigment dispersion (H) and the coating 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) at 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】

[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. Corner stitch adhesion : Make 100 square stitches with a width of 1 mm.
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, in which the dispersant is (A) a (meth)acrylic monomer modified with a lactone or an oxyacid condensate 3-98 Part by weight (B) α,β-ethylenically unsaturated nitrogen-containing monomer
2-97 parts by weight (C) 0-20 parts by weight of ethylenically unsaturated carboxylic acid and (D) 0-20 parts by weight of α,β-ethylenically unsaturated monomers other than the above (A), (B), and (C) An aqueous pigment dispersion characterized by being a water-soluble product of a polymer obtained by copolymerizing 91 parts by weight.