JPH0576509B2 - - 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 acidity 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 aggregation/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 liquid in which pigments are dispersed with a dispersant is prepared in advance, and this dispersion is mixed and dispersed in a colored aqueous paint to prepare an aqueous paint. Conventional aqueous pigment dispersions mainly use low molecular weight compounds such as surfactants as dispersants, but these dispersants cause 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 use of the resulting aqueous pigment dispersion is dependent on the type of binder used in water-based paints. However, there are disadvantages such as limitations. This goes against the rationalization of paint production, and there is therefore a strong demand for the development of an aqueous pigment dispersion that can be commonly used in various water-based paints. Therefore, the inventors of the present invention have discovered that the pigment can be easily dispersed in a small amount, is compatible with various water-based resins, especially cationic water-based resins, and is polymeric in itself and causes a decrease in the coating performance of water-based paints. As a result of intensive research with the aim of developing an ideal dispersant free of oxidation, 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 an oil or fat fatty acid or a synthetic saturated fatty acid ( 3 to 98 parts by weight (B) Aminoalkyl (meth)acrylate or aminoalkyl (meth)acrylamide monomer (hereinafter referred to as "fatty acid-modified (meth)acrylic monomer") “Aminoalkyl (meth)
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), ( Obtained by copolymerizing 0 to 91 parts by weight of α,β-ethylenically unsaturated monomers other than B) and (C) and converting the amino groups present in the resulting copolymer into quaternary ammonium. A cationic aqueous pigment dispersion characterized by being a water-soluble copolymer is provided. In the above polymer used as a dispersant for the cationic aqueous pigment dispersion of the present invention, a relatively lipophilic long side chain is bonded in a separated form to a main chain containing a hydrophilic nitrogen-containing monomer. Because of its structure, it has very high pigment dispersion ability. Furthermore, since the polymer has an extremely excellent ability to adsorb pigments derived from nitrogen-containing monomer units, it strongly adsorbs onto pigment particles and provides a coating material with excellent storage stability. Furthermore, since the polymer is basic, it has excellent properties such as corrosion resistance, and can provide a good colored coating film. Hereinafter, the dispersant used in the cationic aqueous pigment dispersion of the present invention will be explained in more detail. Fatty acid modified (meth)acrylic monomer (A) Fatty acid modified (meth) used in the present invention
The acrylic monomer (A) can be obtained by adding an oil fatty acid such as a drying oil fatty acid, a semi-drying oil fatty acid, a non-drying oil fatty acid, or a synthetic saturated fatty acid to a (meth)acrylic monomer as described below. It is a monomer produced by introducing Typical fat and oil 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. Drying and semi-drying oil fatty acids such as fatty acids, tall oil fatty acids, 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, castor oil fatty acids,
Examples include non-drying oil fatty acids such as hydrogenated castor oil fatty acids and palm oil fatty acids, and these fatty acids can be used alone or in a mixture of two or more. In addition, the synthetic saturated fatty acids used in the present invention can be obtained from natural fats and oils or fatty acids or petroleum raw materials by ozone oxidation method, paraffin liquid phase air oxidation method,
The number of carbon atoms artificially induced by methods such as the oxo method and the Koch method is 4 to 24, preferably 5.
~18 linear or branched saturated aliphatic carboxylic acids. Typical synthetic saturated fatty acids include neopentanoic acid, 2-ethylbutyric acid, heptanoic acid, 2-ethylhexanoic acid, isooctanoic acid, and nonane. acids, isononanoic acid, decanoic acid, isodecanoic acid, neodecanoic acid, isotridecanoic acid, isopalmitic acid, isostearic acid, and the like. 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, among the above-mentioned fatty acids, drying oil fatty acids and semi-drying oil fatty acids having an iodine value of about 100 or more are preferred because they can impart crosslinking drying properties to the resulting dispersant at room temperature. 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. can be exemplified. Therefore, one type of (meth)acrylic monomer into which the above-mentioned fatty acid is introduced to obtain the fatty acid-modified (meth)acrylic monomer (A) is
Examples of this type of ester include "acrylic acid ester or methacrylic acid ester having an epoxy group" (hereinafter, this may be abbreviated as "epoxy-containing (meth)acrylic acid ester"). Those containing a glycidyl group in the acid ester residue moiety, particularly glycidyl acrylate and glycidyl methacrylate, are preferred. Such epoxy-containing (meth)
The fatty acid-modified acrylic monomer (A) using an acrylic acid ester is prepared according to a conventional method in the presence or absence of a suitable inert solvent, usually in the absence of a solvent. This can be carried out by reacting with (meth)acrylic acid ester. The reaction can generally be carried out at a temperature of about 60 to about 220°C, preferably about 120 to about 170°C, and the reaction time is generally about 0.5 to about 40 hours.
Preferably it is about 3 to about 10 hours. It is usually advantageous to use the epoxy-containing (meth)acrylic ester in a proportion of 0.7 to 1.5 mol, preferably 0.8 to 1.2 mol, per mol of said 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 an epoxy-containing (meth)acrylic ester and/or a fatty acid to be produced. It is advantageous to suppress the polymerization of the modified (meth)acrylic ester. In the above reaction, esterification accompanied by cleavage of the oxirane ring occurs between the oxirane ring (epoxy group) of the epoxy-containing (meth)acrylic ester and the carboxyl group of the fatty acid, resulting in the (meth)acrylic ester modified with the fatty acid. is obtained. In addition, the (meth)acrylic monomers that are reacted with the above fatty acids to produce another type of fatty acid-modified (meth)acrylic monomer (A) include "acrylic esters or methacrylic esters containing hydroxyl groups. ” [Hereinafter, this will be referred to as “hydroxyl group-containing (meth)
(sometimes abbreviated as "acrylic acid ester")], and this type of ester includes ester residues of acrylic acid or methacrylic acid with 1
hydroxyl groups, and the ester residue has 2 to 3 hydroxyl groups.
Those containing 24 carbon atoms, preferably 2 to 8 carbon atoms are included, among them those of the following formula () or ()

[ka]

[Chemical formula] 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
-8, hydroxyl group-containing (meth)acrylic esters of the type shown below are suitable. Particularly suitable hydroxyl group-containing (meth) in the present invention
The acrylic esters are hydroxyalkyl acrylates and hydroxyalkyl methacrylates represented by the above formula (), especially 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate and 2-hydroxypropyl methacrylate. The latter type of fatty acid-modified (meth)acrylic monomer (A) is usually prepared by mixing the fatty acid with the hydroxyl group-containing (meth)acrylic ester in an appropriate inert solvent in the presence of an esterification catalyst. This can be done by reacting with. The reaction is generally carried out under heating at a temperature of 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 (meth)acrylic ester is
Usually, it can be used in a proportion of 0.5 to 1.9 mol per mol of said fatty acid, preferably 1.0 to 1.5 mol per mol of said fatty acid. 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. Approximately 0.001 of the total amount of the above fatty acid and hydroxyl group-containing (meth)acrylic ester
~about 20% by weight, preferably about 0.05 to about 1.0% by weight
used at a rate of 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 (meth)acrylic ester and/or a fatty acid to be produced. It is advantageous to suppress the polymerization of the modified (meth)acrylic ester. In the above reaction, esterification occurs between the hydroxyl group of the hydroxyl group-containing (meth)acrylic ester and the carboxyl group of the fatty acid, and a fatty acid-modified (meth)acrylic ester is obtained. As yet another method for preparing the fatty acid-modified (meth)acrylic monomer (A), in addition to the above-mentioned method, glycidyl esters of the fat and oil fatty acids (for example, "Blemmer DFA" manufactured by NOF Corporation) can be used. It is also possible to esterify acrylic acid or methacrylic acid as described above. Aminoalkyl (meth)acrylic monomer (B): The aminoalkyl (meth)acrylic monomer (B) used in the present invention contains a substituted amino group in the ester moiety of the (meth)acrylic acid ester. This includes those containing a substituted amino group in the amide moiety of (meth)acrylic acid, and especially those containing a substituted amino group in the amide moiety of (meth)acrylic acid, especially those of the following formula () or ()

[ka]

[Chemical formula] In each of the above formulas, R ₂ represents a lower alkyl group,
R ₃ and R ₄ each independently represent a hydrogen atom or a lower alkyl group, R ₁ and n have the above meanings, and those represented by these are suitable. The term "lower" used herein means that the group to which this term is attached has 6 or less carbon atoms, preferably 4 or less 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, etc. are included, and examples represented by the above formula () include N,N- Dimethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, etc. are included,
These can be used alone or in combination of two or more. Among the aminoalkyl (meth)acrylic monomers mentioned above, aminoalkyl (meth)acrylates of the formula () are preferred, and N,N-di-lower alkylaminoalkyl (meth)acrylates are especially optimal. be. 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. () 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. () Vinyl lactams: For example, vinyl caprolactam. () Others: For example, the expression

N-(meth)acryloylmorpholine represented by [Formula] (wherein R ₁ has the above meaning),
formula

N-(meta) represented by [Formula] (where R ₁ has the above meaning)
Acryloylpyrrolidine etc. Among the above-mentioned vinyl monomers having a nitrogen-containing heterocycle, preferred are vinylpyrrolidones, vinylimidazoles, and vinylcarbazoles, 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] In the formula, R ₃ represents a hydrogen atom or lower alkyl, R ₆ represents a hydrogen atom, a lower alkyl group, a hydroxy lower alkyl group, or a lower alkoxy lower alkyl group, and R ₁ has the above meaning, and The (meth)acrylamide shown is suitable. 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 and the like are included. Among 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 alone 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. (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; C _2-18 alkoxyalkyl ester of acrylic acid or methacrylic acid such as methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, ethoxybutyl methacrylate; Allyl C _2-8 alkenyl esters of acrylic acid or methacrylic acid such as acrylate, allyl methacrylate; C _2-8 hydroxyalkyl esters of acrylic acid or methacrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate; C _3-18 alkenyloxyalkyl esters of acrylic acid or methacrylic acid such as allyloxyethyl acrylate and allyloxymethacrylate;
C _3-9 carboxyalkyl esters of acrylic or methacrylic acid, such as 2-carboxyethyl acrylate. (b) Vinyl aromatic compounds: e.g. styrene, α
-Methylstyrene, vinyltoluene, p-chlorostyrene. (c) Polyolefin compounds: for example, butadiene, isoprene, chloroprene. (d) α,β-ethylenically unsaturated carboxylic acids: for example, acrylic acid, methacrylic acid, maleic acid,
such as itaconic acid. (e) Others: Acrylonitrile, methacrylonitrile, methyl isopropenyl ketone, vinyl acetate, Beoba monomer (Siel Chemicals), vinyl propionate, vinyl pivalate, 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 fatty acid-modified (meth)acrylic monomer (A), the aminoalkyl (meth)acrylic monomer (B), the 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) Fatty acid modified (meth)acrylic monomer (A): 3
~98 parts by weight, preferably from 5 to 90 parts by weight, more preferably from 15 to 90 parts by weight in terms of coating film drying properties and coating performance
75 parts by weight, (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
Parts 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
Parts by weight, (4) Above (A), (B), (C), unsaturated monomer of great wood (D): 0
~91 parts by weight, preferably 2~ from the viewpoint of coating film performance
83 parts by weight, more preferably 5 to 75 parts by weight, 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 and a polymerization catalyst is added. 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
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 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 ₇ [wherein R ₇ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms], such as ethylene glycol, butyl cellosolve, ethyl cellosolve, etc.; formula

A propylene glycol solvent of [formula] [wherein R ₇ has the same meaning as above], such as propylene glycol monomethyl ether; formula HO−CH ₂ CH ₂ −OCH ₂ CH ₂ −
OR ₇ [wherein R ₇ has the same meaning as above] carbitol-based solvents, such as diethylene glycol, methyl carbitol, butyl carbitol, etc.; formula R ₈ O−CH ₂ CH ₂ −OR ₉ [where R ₈ as well as
each R ₉ represents an alkyl group having 1 to 3 carbon atoms], such as ethylene glycol dimethyl ether; formula R ₈ O-
diglyme solvent of CH ₂ CH ₂ OCH ₂ −CH ₂ OR ₉ [However, R ₈ and R ₉ have the same meanings as above],
For example, diethylene glycol dimethyl ether; formula R ₁₀ O-CH ₂ CH ₂ OCO-CH ₃ [However,
R ₁₀ represents a hydrogen atom, CH ₃ or C ₂ H ₅ ] cellosolve acetate solvents, such as ethylene glycol monoacetate, methyl cellosolve acetate, etc.; formula R ₁₁ OH [where R ₁₁ has 1 to 4 carbon atoms] (representing an alkyl group) such as ethanol, propanol, butanol; and 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 ₁₂ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms] or the formula

Aromatic hydrocarbons represented by the formula [wherein R ₁₃ or R ₁₄ each represents an alkyl group having 1 to 4 carbon atoms], such as toluene, xylene, etc.; formula R ₁₅ -COO-R ₁₆ [ However, R ₁₅ represents an alkyl group having 1 to 6 carbon atoms, and R ₁₆
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.;
R ₁₇ R ₁₈ C=O [wherein R ₁₇ and R ₁₈ 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 ₁₇ -O-R ₁₈ [wherein R ₁₇ and R ₁₈ have the same meanings as above], such as ethyl ether, hexyl ether, etc.;
Alcohols represented by R ₁₉ OH [wherein R ₁₉ 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.
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. Additionally, the copolymers thus obtained generally contain at least 0.02 meq/g copolymer, preferably
It may have an amino group equivalent weight of 0.2 meq/g copolymer. The quaternary ammoniumization of the copolymer used as a dispersant in the present invention can be carried out, for example, by reacting the copolymer with the following 1,2-epoxy compound in the presence of an acid and/or water to form a copolymer. This can be carried out by converting the secondary or tertiary amino group in the compound into a quaternary ammonium. Examples of 1,2-epoxy compounds that can be used for quaternary ammonization of the copolymer include the following formula ()

[Chemical formula] In the formula, R ₁ has the above meaning, and R ₂₀ is a hydrogen atom, an alkyl group, a cycloalkyl group, -CH ₂ -O
−R ₂₁ ,

[Formula] or a substituted or unsubstituted phenyl group, where R ₂₁ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, or a substituted or unsubstituted phenyl group is suitable. There is. In the formula, the number of alkyl groups and cycloalkyl groups that can be represented by R ₂₀ and/or R ₂₁ is generally 1 to 18, preferably 1 to 18.
It can have 8 carbon atoms, and the alkenyl group can preferably have 2 to 6 carbon atoms. Furthermore, examples of substituents on the phenyl group include lower alkyl groups and lower alkoxy groups. Representative examples of such 1,2-epoxy compounds include:
ethylene oxide, propylene oxide,
1,2-butylene oxide, 1,2-pentylene oxide, 1,2-octylene oxide,
Styrene oxide, glycidol, glycidyl (meth)acrylate, glycidyl acetate, glycidyl lawalate, CARDURAR○ E (glycidyl ester of versatile acid, manufactured by Ciel Chemical Co., Ltd.), butyl glycidyl ether, octyl glycidyl ether, phenyl glycidyl ether, Enyl glycidyl ether, p-tert-butylphenyl glycidyl ether, allyl glycidyl ether, and the like. The amount of these 1,2-epoxy compounds used is 4
Although it can be changed depending on the type of amino group to be converted into primary ammonium, it is generally recommended to use 2 to 4 times the molar amount in the case of a secondary amino group, and 1 to 2 times the molar amount in the case of a tertiary amino group. It's convenient. On the other hand, examples of acids used in the quaternization reaction include formic acid, acetic acid, lactic acid, (meth)acrylic acid,
Examples include organic acids such as propionic acid, butyric acid, and hydroxyacetic acid; and inorganic acids such as boric acid, hydrochloric acid, phosphoric acid, and sulfuric acid. These acids are conveniently used in a proportion of about 1 to about 2 moles per amino group to be quaternized. Further, water is suitably used in a proportion of about 0.5 to about 20 moles per amino group to be converted into quaternary ammonium. One suitable method for converting the amino group derived from the aminoalkyl (meth)acrylic monomer (B) in the copolymer into a quaternary ammonium is to convert the copolymer into a mixture of the copolymer and the above acid. , 1,2-epoxy compound and water are added, and about 1
This is a method of reacting for about 7 hours. Note that when the amino group to be converted into a quaternary ammonium is a secondary amino group, the secondary amino group is first converted into a tertiary amino group by reaction with a 1,2-epoxy compound, and then the tertiary amino group is converted into a tertiary amino group by a reaction with a 1,2-epoxy compound. It is also possible to change it to a class ammonium group. The thus quaternary ammonium-formed copolymer should contain a sufficient amount of quaternary ammonium groups to make the copolymer water-soluble, and the amount depends on the type and molecular weight of the copolymer. Generally speaking, a suitable range is 0.01 to 6 meq/g copolymer, preferably 0.1 to 5 meq/g copolymer, and more preferably 0.1 to 3 meq/g copolymer, although it varies depending on the It is. The dispersant made of the copolymer made water-soluble as described above is generally about 1 to about 1% per 100 parts by weight of the pigment.
A range of 500 parts by weight, preferably from about 1 to about 300 parts by weight, can be used. When the amount of the dispersant used exceeds the upper limit of this range, the balance between coloring power and viscosity of the aqueous pigment separation solution tends to be imbalanced, while when it is outside the lower limit, the dispersion stability of the pigment decreases. It's easy to do. The aqueous medium that can be used in the cationic aqueous pigment dispersion of the present invention is essentially water, but if necessary, for example, the degree of hydrophilicity of the dispersant is low and sufficient pigment dispersion performance cannot be obtained. In such cases, a hydrophilic organic solvent can be used in combination. As the hydrophilic organic solvent, the same solvents as those used for producing the polymer can be used alone or in combination. Furthermore, the pigments used in the cationic aqueous pigment dispersion of the present invention can be inorganic and organic pigments commonly used in pigment dispersions of this type, for example, inorganic pigments include:
(1) Oxide-based (zinc white, titanium dioxide, red iron,
Chromium oxide, cobalt blue, iron black, etc.); (2) Hydroxide type (alumina white, yellow iron oxide, etc.); (3)
Sulfide, selenide type (zinc sulfide, vermilion, cadmium yellow, cadmium red, etc.); (4) Ferrocyanide type (dark blue, etc.); (5) chromate type (yellow lead, zinc chromate, molybdenum red, etc.) ); (6) Sulfate-based (precipitated barium sulfate, etc.); (7) Carbonate-based (precipitated calcium carbonate, etc.); (8) Silicate-based (hydrated silicate, clay, ultramarine, etc.); ( 9) Phosphate-based (manganese violet, etc.); (10) Carbon-based (carbon black, etc.); (11) Metal powder-based (aluminum powder, bronze powder, zinc powder, etc.); and organic pigments include , (1) Nitroso pigment type (naphthol green B
(2) Nitro pigment type (Naphthol Yellow S, etc.);
(3) Azo pigments (Resol Red, Lake Red, Fast Yellow, Naphthol Red, Red, etc.); (4) Dyeing lake pigments (Alkali Blue Lake, Rhodamine Lake, etc.); (5) Phthalocyanine pigments (Phthalocyanine Blue, Fast Sky Blue, etc.); (6) Condensed polycyclic pigments (perylene red,
quinacridone red, dioxazine violet, isoindolinone yellow, etc.). The content of the pigment in the cationic aqueous pigment dispersion of the present invention is not particularly technically limited, but is generally about 2 to
It is approximately 90% by weight. 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. 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-acidic 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 blending 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. The pigment dispersion can be blended in an amount of about 2 to about 1000 parts by weight per 100 parts by weight of the resin content of the above-mentioned aqueous 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. Stearyl methacrylate 113 parts N-vinyl-2-pyrrolidone 93 parts and N,N-dimethylaminoethyl methacrylate
A mixture consisting of 44 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
A copolymer solution with a Gardner viscosity of 70.3% and a Gardner viscosity (40% n-butyl cellosolve solution) B was obtained. Furthermore, 179 parts of the copolymer solution was placed in a reaction vessel, and approximately
The temperature was raised to 50°C, 6.6 parts of an 88% lactic acid aqueous solution was added, and then the temperature was further raised to 90°C and heated for about 30 minutes. Thereafter, the mixture was cooled to 50°C, 4.7 parts of 1,2-butylene oxide and 3.5 parts of water were added, and the mixture was heated to 110°C and reacted for about 3 hours to form a quaternary ammonium. The quaternary ammonium group content of the resulting copolymer was approximately 0.25 meq/g copolymer. After cooling the obtained water-solubilized copolymer to room temperature,
Water was added to obtain 40% dispersant (). 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 dispersed for 0.5 hours using a Red Devil dispersion machine to form an aqueous pigment dispersion of the present invention. I got (A). 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, the pigment dispersion liquid and the water-based resin shown in Table 2 below are thoroughly mixed to form water-based paints (1) to (4).
I got it. The coating film performance of the obtained water-based paint is summarized in Table 2 below. Example 2 (2-a) The following ingredients: 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. (2-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. Fatty acid modified monomer obtained in (2-a) above 113 parts N-vinylpyrrolidone 126 parts N,N-dimethylaminoethyl methacrylate
11 parts azobisdimethylvaleronitrile 17 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, with a heating residue of 70.6% and Gardner. Viscosity (40% n-butyl cellosolve solution)
A copolymer solution of J was obtained. Furthermore, 211 parts of this copolymer solution was placed in a reaction container and heated to approximately 50°C.
After adding 3.5 parts of 88% lactic acid aqueous solution, the temperature was raised to 70°C.
25 parts of 1,2-butylene oxide and 2 parts of water were added, the temperature was further raised to 110°C, and the mixture was reacted for about 3 hours to form a quaternary ammonium. The quaternary ammonium group content of the obtained copolymer was approximately 0.2 milliequivalent/
g copolymer. Water was added to this water-solubilized copolymer to obtain a 40% dispersant (). 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. In addition, a water-based paint (5) was prepared by thoroughly mixing this pigment dispersion (D) and the water-based resin shown in Table 2 below. 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 (1-a) The following components: 133 parts of isononanoic acid 119 parts of glycidyl methacrylate 0.3 parts of hydroquinone 0.2 parts of tetraethylammonium bromide 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) The following components: Synthetic fatty acid modified monomer obtained in (1-a) above
113 parts N,N-dimethylacrylamide 115 parts N,N-dimethylaminoethyl methacrylate
A mixture of 44 parts of azobisdimethylvaleronitrile, 17 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 70.3%, Gardner viscosity (40
% n-Butyl cellosolve solution) A copolymer solution of A was obtained. Furthermore, 180 parts of this copolymer solution was placed in a reaction vessel, the temperature was raised to approximately 50°C, 6.6 parts of an 88% lactic acid aqueous solution was added, the temperature was raised to 80°C, 4.7 parts of 1,2-butylene oxide and 3.5 parts of water was added, and the mixture was further reacted at 110°C for about 2.5 hours to form a quaternary ammonium. The quaternary ammonium group content of the obtained copolymer was about 0.3 meq/g copolymer. Water was added to this water-solubilized copolymer to obtain a 40% dispersant (). 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 Fatty acid modified monomer obtained in (2-a) 102 parts N-vinylpyrrolidone 92 parts Acrylic acid 11 parts A mixture of 44 parts N,N-dimethylaminopropylmethacrylamide and 17 parts azobisdimethylvaleronitrile A mixture of 50 parts of n-butyl cellosolve was subjected to a polymerization reaction according to the method described in Example 1. Heating residue 71.0%, Gardner viscosity (40
% n-Butyl cellosolve solution) A copolymer solution of H was obtained. Furthermore, 180 parts of this copolymer solution was placed in a reaction vessel, the temperature was raised to about 50°C, 7.7 parts of acetic acid was added, and the temperature was raised to 80°C, 9.4 parts of 1,2-butylene oxide and 7.0 parts of water. was added, the temperature was further raised to 110°C, and the mixture was reacted for about 3.5 hours to form a quaternary ammonium. The quaternary ammonium group content of the obtained copolymer was approximately 0.5 milliequivalent/g copolymer.
A 40% dispersion () was obtained by adding the water-soluble copolymer to the water-soluble copolymer. 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 Fatty acid modified monomer obtained in (2-a) 93 parts N-vinylpyrrolidone 83 parts N,N-dimethylaminoethyl methacrylate
A mixture of 44 parts n-butyl methacrylate 30 parts and azobisdimethylvaleronitrile 18 parts n-butyl cellosolve 50 parts was subjected to a polymerization reaction according to the method described in Example 1. Heating residue 70.4%, Gardner viscosity (40
% n-butyl cellosolve solution) A copolymer solution of G was obtained. Furthermore, 180 parts of this copolymer solution was placed in a reaction vessel, heated to about 50°C, 13.2 parts of an 88% lactic acid aqueous solution was added, and the temperature was raised to about 90°C, and 17.1 parts of butyl glycidyl ether and 7.0 parts of water were added. 120
The mixture was reacted at ℃ for about 3 hours to form a quaternary ammonium. The quaternary ammonium group content of the resulting copolymer was approximately 0.45 meq/g copolymer. Water was added to this water-solubilized copolymer to obtain a 40% dispersant (). 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 (8) was prepared by thoroughly mixing this pigment dispersion (G) and the 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.

【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 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. String adhesion: A test was carried out by making 100 1 mm wide grids, pasting cellophane adhesive tape on them, and peeling off the tape 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 consisting of a pigment, a dispersant, and an aqueous medium, in which the dispersant is (A) a (meth)acrylic monomer modified with an oil or fat fatty acid or a synthetic saturated fatty acid 3-98 Part by weight (B) Aminoalkyl (meth)acrylate or aminoalkyl (meth)acrylamide monomer
1 to 97 parts by weight and (C) α,β-ethylenically unsaturated nitrogen-containing monomer other than the above (B) 0 to 96 parts by weight (D) Other than the above (A), (B), and (C) It must be a water-soluble copolymer obtained by copolymerizing 0 to 91 parts by weight of an α,β-ethylenically unsaturated monomer and converting the amino groups present in the resulting copolymer into quaternary ammonium. A cationic aqueous pigment dispersion characterized by: