JPH0576506B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cationic 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, the pigment is dispersed in advance with a dispersant to prepare an aqueous pigment dispersion, and this is mixed and dispersed in the aqueous paint to be colored to color the aqueous paint. Conventional aqueous pigment dispersions mainly use low-molecular weight compounds such as surfactants as dispersants, but these dispersants cause negative effects, such as secondary adverse effects such as deterioration of coating performance or coating condition. This is unavoidable, and recently oligomers or polymers having a medium molecular weight have been used as dispersants to suppress the deterioration of coating performance. However, when oligomers or polymers are used as dispersants, the amount used is larger than that of low-molecular surfactants, and the resulting aqueous pigment dispersion is limited to the types of binders used in water-based paints. It has disadvantages such as being limited by 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 inventors of the present invention have discovered that the pigment can be easily dispersed in a small amount, that it is compatible with cationic water-based resins in various water-based resins, etc., and that it itself is a polymer and causes a decline in the coating performance of water-based paints. As a result of intensive research aimed at developing an ideal dispersant that cannot be used in particularly difficult aqueous systems, the present invention was completed. 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 ( (meth)acrylic monomer (b) modified with a) and/or mono- or polyalkylene glycol or its derivative (hereinafter referred to as "modified (meth)acrylic monomer (A)") 3 to 98 parts by weight (B) Aminoalkyl (meth)acrylate or aminoalkyl (meth)acrylamide monomer (hereinafter referred to as "aminoalkyl (meth)acrylamide")
1 to 97 parts by weight (C) 0 to 96 parts by weight of α,β-ethylenically unsaturated nitrogen-containing monomers other than (B) above, and (D) above (A), ( It is characterized by being a water-soluble product obtained by neutralizing a polymer obtained by copolymerizing 0 to 91 parts by weight of α,β-ethylenically unsaturated monomers other than B) and (C) with an acid. A cationic aqueous pigment dispersion is provided. The polymer used as a dispersant for the cationic aqueous pigment dispersion of the present invention has a relatively linear long side chain separated from a main chain containing a hydrophilic nitrogen-containing (meth)acrylic monomer. Because it has a bonded structure, it has very high pigment dispersion ability. Furthermore, this polymer has very good pigment adsorption ability derived from nitrogen-containing monomer units, so it strongly adsorbs pigments and has excellent storage stability of paints, and because it is basic, it has excellent properties such as corrosion resistance. It is also possible to obtain a colored coating film of excellent quality. Hereinafter, the dispersant used in the cationic aqueous pigment dispersion of the present invention will be explained in more detail. Modified (meth)acrylic monomer (A): (meth)acrylic monomer (a) modified with lactone or oxyacid condensate: Modified with lactone or oxyacid condensate used in the present invention (Meth)acrylic monomer (hereinafter referred to as "modified (meth)acrylic monomer (a)") (a) is produced by reacting a (meth)acrylic monomer with a lactone or an oxyacid condensate. The obtained monomer is typically represented by the following formula ()

[Chemical formula] In the formula, R ₁ represents a hydrogen atom or a methyl group,
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
represents a -C _o -H _2o group (wherein n is an integer of 2 to 18), and p represents 1 to 7. The lactone used as a modifier in the modified (meth)acrylic monomer (a) represented by formula () is a cyclic ester compound containing an ester functional group -CO-O- in the ring, and a representative Examples of lactones include r-lactone, δ-lactone, and ε-lactone.
Examples include lactone, γ-caprolactone, δ-caprolactone, methyl ε-caprolactone (including isomers), and the like. In addition, the oxyacid condensate is a condensate of aliphatic monocarboxylic acids (hydroxy fatty acids) having one hydroxyl group in the molecule, and examples of the hydroxy fatty acids include ring-opened products of the above-mentioned lactone compounds, ricinoleic acid, Examples include oxystearic acid and lanopalmitic acid. The production of condensates of these oxyacids is carried out in accordance with conventional methods such as the above-mentioned hydroxy fatty acids,
A mixture consisting of a refluxing solvent (xylene, toluene, heptane, etc.) and an esterification catalyst (methyl sulfuric acid, dodecylbenzenesulfonic acid, etc.) is heated at approximately 140 to 250°C.
This can be carried out by heating and condensing. 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. Therefore, the (meth)acrylic monomer into which the above-mentioned lactone compound is introduced in order to obtain the lactone-modified (meth)acrylic monomer has one hydroxyl group in the ester residue moiety and Hydroxyl group-containing (meth)acrylic esters containing 2 to 8 carbon atoms in the ester residue moiety are preferably used, and specifically, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl methacrylate,
-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and the like. The preparation of the lactone-modified (meth)acrylic monomer (a) using such a hydroxyl group-containing (meth)acrylic acid ester can be carried out by a method known per se, for example, as disclosed in JP-A-57-195714. It can be carried out by a method such as, usually, by reacting the lactone with a hydroxyl group-containing (meth)acrylic ester in the presence of a catalyst at about 20 to 220 °C, preferably about 50 to 180 °C. can. 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. Such an oxyacid condensate-modified (meth)acrylic monomer 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 about 60-220°C, preferably about 120-170°C.
The reaction time is generally about 0.5 to 40 hours, preferably about 3 to 10 hours. 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. (meth)acrylic monomer modified with mono- or polyalkylene glycol or its monoether derivative (b) (meth)acrylic monomer modified with mono- or polyalkylene glycol or its monoether derivative used in the present invention (hereinafter referred to as "modified (meth)acrylic monomer (b)") (b)
is an ester compound of (meth)acrylic acid and mono- or polyalkylene glycol or its monoether derivative, and is typically represented by the following general formula:

[Chemical formula] In the formula, R ₁ represents the above meaning, R ₅ represents a hydrogen atom, a C ₁ to C ₂₀ alkyl group, an aryl group (e.g. phenyl group) or an aralkyl group (preferably a benzyl group), and m represents It is an integer of 2 to 12, and n is an integer of 1 to 20. Includes those shown. Specific examples of the modified (meth)acrylic monomer (b) include diethylene glycol (meth)acrylate, triethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, dipropylene glycol (meth)acrylate, and tripropylene. Glycol (meth)acrylate, polypropylene glycol (meth)
Acrylate, methoxyethylene (meth)acrylate, ethoxyethylene (meth)acrylate, butoxyethylene (meth)acrylate, hexyloxyethylene (meth)acrylate, ethoxypropylene (meth)acrylate, ethoxydiethylene (meth)acrylate, butoxydiethylene (meth)acrylate Examples include acrylate, dodecyloxydiethylene (meth)acrylate, phenoxydipropylene (meth)acrylate, and benzyloxydiethylene (meth)acrylate, each of which can be used alone or in combination of two or more. In addition, the molecular weight of these modified (meth)acrylic monomers (b) is generally 100
Advantageously, it is in the range ~5000, preferably 150-1500. Such modified (meth)acrylic monomers (a) and (b)
Each can be used alone or in combination. Aminoalkyl (meth)acrylic monomer (B): The aminoalkyl (meth)acrylic monomer (B) used in the present invention includes a substituted or unsubstituted ester moiety of a (meth)acrylic acid ester. Those containing an amino group and those containing a substituted or unsubstituted amino group in the amide moiety of (meth)acrylic acid are included, especially those containing the following formula () or ()

[ka]

embedded image In each of the above formulas, R ₆ , R ₇ and R ₈ each independently represent a hydrogen atom or a lower alkyl group, R ₁ has the above meaning, and n is an integer of 2 to 8. The one shown is 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. As specific examples of such aminoalkyl (meth)acrylic monomers, examples represented by the above formula () include N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, ) acrylate, N-t-butylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,
N-dimethylaminobutyl (meth)acrylate, N-propylaminoethyl (meth)acrylate, N-butylaminoethyl (meth)acrylate, and the like are included. Further, examples represented by the above formula () include N,N-dimethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, etc.
These can be used alone or in combination of two or more. Other α,β-ethylenically unsaturated nitrogen-containing monomers (C): Next, as α,β-ethylenically unsaturated nitrogen-containing monomers (C) other than the above (B) used in the present invention, includes monomers containing one or more (usually up to 4) basic nitrogen atoms and one ethylenically unsaturated bond in one molecule, and typical examples include nitrogen-containing hetero Examples include unsaturated monomers having a ring 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. (1) 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, 5-vinylquinoline. () Vinylpiperidines; For example, 3-vinylpiperidine, N-methyl-3-vinylpiperidine, etc. () Other; For example, 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,
These include vinyl imidazoles and vinyl carbazoles, and among them, those in which the ring nitrogen atom is tertiary are preferred. [2] Nitrogen-containing derivatives of (meth)acrylic acid include
Amides of (meth)acrylic acid are included, especially the following formula ()

[Chemical formula] R ₉ represents a hydrogen atom or lower alkyl,
R ₁₀ represents a hydrogen atom, a lower alkyl group, a hydroxy lower alkyl group, or a lower alkoxy lower alkyl group, and R ₁ and n have the above-mentioned meanings. A (meth)acrylamide represented by the following is suitable. Here, the term "lower" 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, examples of (meth)acrylamide of 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, N,N-dipropyl (meth)acrylamide, N-methylol (meth)acrylamide, N
-Ethoxymethyl (meth)acrylamide, N-
Butoxymethyl (meth)acrylamide, etc. are included. As these (meth)acrylamides, 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 singly or in combination of two or more. 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. (1) Esters of acrylic acid or methacrylic acid: for example, 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, acrylic ethoxybutyl, ethoxybutyl methacrylate; allyl acrylate; C _2-8 alkenyl esters of acrylic acid or methacrylic acid such as allyl methacrylate;
C _2-8 hydroxyalkyl ester; of acrylic acid or methacrylic acid such as allyloxyethyl acrylate, allyloxymethacrylate, etc.
_C3-18 alkenyloxyalkyl ester. (2) Vinyl aromatic compounds: e.g. styrene, α
-Methylstyrene, vinyltoluene, p-chlorostyrene. (3) Polyolefin compounds: for example, butadiene, isoprene, chloroprene. (4) Unsaturated carboxylic acids: for example, acrylic acid, methacrylic acid, maleic acid, itaconic acid, β-carboxyethyl acrylate, etc. (5) Others: Acrylonitrile, methacrylonitrile, methyl isopropenyl ketone, vinyl acetate, peopamonomer (Siel Chemicals), vinyl propionate, vinyl piperate, etc. The unsaturated monomers are appropriately selected depending on the physical properties desired for the aqueous pigment dispersion, and each may be used alone or in combination of two or more. According to the present invention, the above-mentioned modified (meth)acrylic monomer (A), aminoalkyl (meth)acrylic monomer (B), α,β-ethylenically unsaturated nitrogen-containing monomer
(C) and the unsaturated monomer (D) are copolymerized with each other. The copolymerization can be carried out according to methods known per se for producing (meth)acrylic copolymers, such as solution polymerization, emulsion polymerization, suspension polymerization, and the like. The blending ratio of the above four components when performing copolymerization can be changed depending on the desired performance as a dispersant, but it is generally appropriate to mix them in the following ratios. (1) Modified (meth)acrylic monomer (A): 3 to 98 parts by weight, preferably 5 to 90 parts by weight, more preferably 15 to 75 parts by weight in terms of coating film performance (2) Aminoalkyl ( meth)acrylic monomer
(B): 1 to 97 parts by weight, preferably 3 to 90 parts by weight from the viewpoint of pigment dispersion, more preferably 5 to 80 parts by weight
Part by weight (3) α, β-ethylenically unsaturated nitrogen-containing monomer (C):
0 to 96 parts by weight, preferably 5 to 90 parts by weight in terms of water solubility and coating performance, more preferably 10 to 75 parts by weight
Part by weight (4) Unsaturated monomers (D) other than the above (A), (B), and (C): 0 to
91 parts by weight, preferably 2 to 83 parts by weight from the viewpoint of coating film performance
parts by weight, more preferably 5 to 75 parts by weight.The above copolymerization reaction is advantageously 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. The reaction can be carried out by continuing the reaction at a reaction temperature of usually about 0 to about 180°C, preferably about 40 to about 170°C, for about 1 to about 20 hours, preferably about 6 to about 10 hours. As the solvent used, it is desirable to use a solvent that can dissolve the copolymer to be produced and is miscible with water. Particularly preferred are those that can be used as they are without being removed when obtaining a cationic aqueous pigment dispersion. Such solvents include, for example, those with the formula HO-
Cellosolve solvents of CH ₂ CH ₂ -OR ₁₁ [wherein R ₁₁ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms] such as ethylene glycol, butyl cellosolve, ethyl cellosolve, etc.; Formula

Propylene glycol solvents, such as propylene glycol monomethyl ether, [wherein R ₁₁ has the same meaning as above]; formula HO-
Carbitol solvents of CH ₂ CH ₂ −OCH ₂ CH ₂ −OR ₁₁ [wherein R ₁₁ has the same meaning as above] such as diethylene glycol, methyl carbitol, butyl carbitol; formula R ₁₂ O−
CH ₂ CH ₂ -OR ₁₃ [However, R ₁₂ and R ₁₃ each represent an alkyl group having 1 to 3 carbon atoms] Glyme solvent such as ethylene glycol dimethyl ether; formula R ₁₂ O-CH ₂ CH ₂ OCH ₂ −
Diglyme solvents of CH ₂ OR ₁₃ [wherein R ₁₃ and R ₁₃ have the same meanings as above], such as diethylene glycol dimethyl ether; formula R ₁₄ O-
Cellosolve acetate solvents of CH ₂ CH ₂ OCO-CH ₃ [wherein R ₁₄ represents a hydrogen atom, CH ₃ or C ₂ H ₅ ], such as ethylene glycol monoacetate, methyl cellosolve acetate, etc.; formula R ₁₅ OH [however, _R15 has 1 to 4 carbon atoms
alcoholic solvents such as ethanol, propanol, butanol and the like; 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 ₁₆ 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 ₁₇ and R ₁₈ each represent an alkyl group having 1 to 4 carbon atoms], such as toluene,
Xylene, etc.; Formula R ₁₉ -COO-R ₂₀ where R ₁₉ represents an alkyl group having 1 to 6 carbon atoms, and R ₂₀ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a cyclohexyl group] Acids or esters represented by the formula, such as acetic acid, ethyl formate, butyl acetate, cyclohexyl acetate, etc.;
R ₂₁ R ₂₂ C=O [wherein R ₂₁ and R ₂₂ 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 ₂₁ -O-R ₂₂ [wherein R ₂₁ and R ₂₂ have the same meanings as above], such as ethyl ether, hexyl ether, etc.;
Alcohols represented by R ₂₃ OH [wherein R ₂₃ represents an alkyl group having 5 to 11 carbon atoms],
Examples include hexanol. This means that the solvent is 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.
Moreover, 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. Therefore, in the above copolymerization reaction, the number average molecular weight of the copolymer produced is generally about 500 to 500.
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 amino groups present in the copolymer resin with a conventionally known neutralizing agent. Examples of neutralizing agents that can be used include organic acids such as formic acid, acetic acid, propionic acid, acetic acid, hydroxyacetic acid, and lactic acid; and inorganic acids such as boric acid, hydrochloric acid, phosphoric acid, and sulfuric acid. Particularly suitable are formic acid and acetic acid. 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 the neutralizing agent used is generally 0.01 to 2.0 equivalents, preferably 0.3 to 1.0 equivalents, based on the amino groups in the resin. The water-solubilized polymer thus obtained is used as a dispersant in a cationic aqueous pigment dispersion consisting of a pigment, a dispersant, and an aqueous medium. Dispersion of the pigment using the water-soluble polymer is usually carried out using a neutralized resin, but if necessary, a neutralization treatment may be performed after dispersing the pigment. 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 cationic 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, In that case,
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. Further, the pigments used in the cationic aqueous pigment dispersion of the present invention can be inorganic and organic pigments commonly used in this type of pigment dispersion. Materials (zinc white, titanium dioxide, red iron oxide, chromium oxide,
Cobalt blue, iron black, etc.); (2) Hydroxide-based (alumina white, yellow iron oxide, etc.); (3) Sulfide, selenide-based (zinc sulfide, vermilion, cadmium yellow, cadmium red, etc.); 4) Ferrocyanide type (prussian blue, etc.); (5) Chromate type (yellow salt, zinc chromate, molybdenum red, etc.); (6) Sulfate type (precipitated barium sulfate, etc.); (7) Carbonate type (precipitated calcium carbonate, etc.); (8) Silicates (hydrated silicates, clay,
(9) phosphate-based (manganese violet, etc.); (10) carbon-based (carbon black); (11) metal powder-based (aluminum powder, bronze powder, zinc powder, etc.). Organic pigments include (1) nitroso pigments (naphthol green B, etc.); (2) nitro pigments (naphthol yellow S, etc.); azo pigments (resol red, lake red, 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 system (perylene red, quinacridone red, etc.) dioxazine violet, isoindolinone yellow, etc.). There is no particular technical limit to the content of the pigment in the cationic aqueous pigment dispersion of the present invention, but
Generally from about 2 to 90% by weight, based on the weight of the dispersion. The cationic aqueous pigment dispersion of the present invention can be prepared by mixing the above components together in a suitable dispersion device, and examples of dispersion devices that can be used include those commonly used in the paint industry. Examples include ball mills, roll mills, homo mixers, sand grinders, sheakers, and attritors. If necessary, conventionally known surfactants and protective colloids may be added to the cationic aqueous pigment dispersion of the present invention to improve dispersion stability. In the cationic aqueous pigment dispersion of the present invention thus obtained, the pigment is very uniformly and finely dispersed, and the pigment particles hardly aggregate or settle 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 cationic aqueous pigment dispersion of the present invention can contain conventionally known water-soluble resins such as alkyd resins, acrylic resins, epoxy resins, urethane resins, and maleated polybutadiene resins used in water-based paints and inks. It has good miscibility with water-dispersible resins, emulsions, etc., is not limited by these resins, and can be widely used for coloring water-based paints made of any resin. It is particularly effective for cationic water-dispersible resins and polymeric emulsions which themselves have poor pigment dispersibility. The ratio of the cationic 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 water-based paint. Next, the present invention will be explained in more detail with reference to Examples. In the examples, parts and % indicate parts by weight and % by weight. Example 1 300 parts of n-butyl cellosolve was placed in a reaction container,
It was heated to 120°C. Next, mixtures in the proportions shown below were separately added dropwise to this solution over a period of about 2 hours. The reaction was carried out under nitrogen injection while stirring the solution. Plaxel FM-3 (manufactured by Daicel Chemical Co., Ltd., ε-caprolactone-modified vinyl monomer) 196 parts N-vinyl-2-pyrrolidone 93 parts and N,N-dimethylaminoethyl methacrylate
A mixture consisting of 4.4 parts of azobisdimethylvaleronitrile; A mixture of 19 parts of azobisdimethylvaleronitrile and 50 parts of n-butyl cellosolve; One hour after the completion of dropping the above mixture, 2.5 parts of azobisisobutyronitrile was added to the reaction solution, and after another 2 hours. , 2.5 parts of azobisisobutyronitrile were added to the reaction solution, and the reaction was then carried out while maintaining the temperature at 120°C for 2 hours. After the reaction is complete, unreacted monomers and n-butyl cellosolve are distilled under reduced pressure, and the heated residue is
70.4%, amine (milliequivalents/g polymer) = 0.841,
A copolymer solution of Gardner viscosity (40% n-butyl cellosolve solution) X was obtained. Further, this copolymer was neutralized with acetic acid (1.0 equivalent neutralization), and water was added to obtain a dispersant (1) 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. Similarly, pigments were dispersed in the proportions shown in Table 1 below to obtain aqueous pigment dispersions (B) and (C) of the present invention. Pigments other than titanium white were dispersed for 1 hour. The properties of the obtained cationic aqueous pigment dispersion are summarized in Table 1 below. Next, formulations consisting of a pigment dispersion liquid and an aqueous resin shown in Table 2 below were thoroughly mixed to obtain aqueous paints (1) to (4). The coating film performance of the obtained water-based paint is summarized in Table 2 below. Example 2 (2-a) The following components: 2155 parts of 12-hydroxystearic acid, 383 parts of toluene, and 4.3 parts of monomethylsulfonic acid were placed in a reaction vessel and heated at 145°C for about 4 hours to remove the condensation water produced from the system. I proceeded with the reaction. 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 increased.
The reaction was carried out at 145°C for about 6 hours to obtain a reaction product with a resin acid value of 5.8. 12-hydroxystearic acid condensate modified monomer obtained in (2-a) above (residue on heating: 86%) 233 parts N-vinyl-2-pyrrolidone 93 parts N,N-dimethylaminopropylacrylamide 48 parts Azobisdimethyl Valeronitrile 19 parts The reaction temperature was kept at 120°C, the above mixture was added dropwise while stirring the reaction solution, and polymerization was carried out in the same manner as in Example 1. A copolymer solution with a Gardner viscosity (40% n-butyl cellosolve solution) of Y (polymer) = 0.658 was obtained. Furthermore, this copolymer was neutralized with acetic acid (1.0 equivalent neutralization), and water was added to remove the heated residue.
A dispersant () consisting of a 40% aqueous solution 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 (D) of the present invention. Further, this pigment dispersion (D) and the water-based resin shown in Table 2 below were sufficiently mixed to prepare a water-based paint (5). The properties of the pigment dispersion (D) and the coating performance of the water-based paint (5) are shown in Tables 1 and 2 below, respectively. Example 3 Blemmer PE-350 (manufactured by NOF Corporation, reaction product of polyethylene glycol and methacrylic acid)
113 parts N,N-dimethylacrylamide 83 parts N-t-butylaminoethyl methacrylate
A mixture of 52 parts of azobisdimethylvaleronitrile, 19 parts of n-butyl cellosolve, and 50 parts of n-butyl cellosolve was subjected to a polymerization reaction according to the method described in Example 1. Heating residue 70.8%, amine (milliequivalent/
A copolymer solution with a Gardner viscosity (40% n-butyl cellosolve solution) B was obtained. Neutralize this with acetic acid (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 (2), pigments shown in Table 1 below were 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 (6) 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 (6) are shown in Tables 1 and 2 below, respectively. Example 4 NK-ester A-2PG (manufactured by Shin-Nakamura Chemical Co., Ltd.,

[Formula]) 114 parts N-vinyl-2-pyrrolidone 93 parts N,N-dimethylaminoethylmethacrylamide 44 parts n-butyl methacrylate 30 parts mixture and azobisdimethylvaleronitrile 19 parts n-butyl cellosolve 50 parts mixture. A polymerization reaction was carried out by the method described in Example 1. Heating residue 71.0%, amine (milliequivalents/g resin) = 0.996, Gardner viscosity (40% n
-Butyl cellosolve solution) A copolymer solution of C was obtained. This material was neutralized with acetic acid (1.0 equivalent neutralization), and 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 (F) of the present invention. Further, a water-based paint (7) 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 (7) are shown in Tables 1 and 2 below, respectively. Example 5 A mixture of NK ester A-2PG 57 parts Plaxel FM-5 98 parts N,N-dimethylaminoethyl methacrylate 67 parts acrylic acid 10 parts and azobisdimethylvaleronitrile 19 parts n-butyl cellosolve 50 parts was carried out. A polymerization reaction was carried out according to the method described in Example 1. Heating residue 70.5%, amine (milliweight/
A copolymer solution with a Gardner viscosity (40% n-butyl cellosolve solution) of 1.839 and a Gardner viscosity (40% n-butyl cellosolve solution) was obtained. Neutralize this with acetic acid (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 (), Table 1 below
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. Further, a water-based paint (8) was prepared by thoroughly mixing this pigment dispersion (G) with a water-based resin shown in Table 2 below. The properties of the pigment dispersion (G) and the film performance of the water-based paint (8) are shown in Tables 1 and 2 below, respectively. Comparative Example 1 A mixture of 1.96 parts of N-vinyl-2-pyrrolidone and 137 parts of methyl methacrylate and a mixture of 17 parts of azobisdimethylvaleronitrile and 50 parts of n-butyl cellosolve were subjected to a polymerization reaction according to the method described in Example 1. . Heating residue 70.2%, Gardner viscosity (40
% n-butyl cellosolve solution) D was obtained, and then a mixture of water and 200 parts of titanium white R-5N (pigment/dispersant = 60/1) was added to 4.7 parts of the polymer solution as in Example 1. Although it was dispersed in a similar manner, it thickened and became pudding-like, making it unusable. Further dilution with water was performed, but no effect as a dispersant was observed when the particle size was 20 μm or more. Comparative Example 2 n- instead of Plaxel FM-3 in Example 1
A polymerization reaction was carried out in the same manner as in Example 1 except that butyl methacrylate was used. Heating residue 70.5%, amine (milliequivalent/g resin)
= 0.850, Gardner viscosity (40% n-butyl cellosolve solution) F copolymer solution was obtained. Next, to 4.7 parts of the polymer solution, 3.6 parts of water, acetic acid (1.0 equivalent neutralization) and 200 parts of Titanium White R-5N (pigment/dispersant =
A mixture of 60/1) was dispersed in the same manner as in Example 1, but it thickened and became pudding-like and could not be used. Further dilution with water was performed, but no effect as a dispersant was observed when the particle size was 20 μm or more.

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[Coating film performance test]

Add a water-based dryer (trade name: "Deiknate", manufactured by Dainippon Ink Co., Ltd., cobalt metal content: 3%) to the water-based paints (1) to (8) 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. In an aqueous pigment dispersion consisting of a pigment, a dispersant, and an aqueous medium, the dispersant comprises (A) a (meth)acrylic monomer (a) modified with a lactone or an oxyacid condensate; and/or (meth)acrylic monomer (b) modified with mono- or polyalkylene glycol or its derivatives
3 to 98 parts by weight (B) Aminoalkyl (meth)acrylate or aminoalkyl (meth)acrylamide monomer
1 to 97 parts by weight (C) 0 to 96 parts by weight of α,β-ethylenically unsaturated nitrogen-containing monomer other than the above (B), and (D) Other than the above (A), (B), and (C) A cationic aqueous pigment dispersion characterized by being a water-soluble product obtained by neutralizing a polymer obtained by copolymerizing 0 to 91 parts by weight of an α,β-ethylenically unsaturated monomer with an acid. .