JPS61101577A - Aqueous pigment dispersion - Google Patents

Abstract

PURPOSE:To provide an aqueous pigment dispersion excellent in dispersibility and dispersion stability, by incorporating a water soluble copolymer contg. a fluoroalkyl group-contg. (meth)acrylic monomer, alpha,beta-ethylenically unsatd. nitrogen monomer, and ethylenically unsatd. carboxylic acid, as a dispersant. CONSTITUTION:An aqueous pigment dispersion comprising a pigment, an aqueous medium and, as a dispersant, a water-soluble polymer prepared by copolymerizing 1-97.5pts.wt. fluoroalkyl group-contg. (meth)acrylic monomer, 2-97pts.wt. (meth)acrylic monomer modified with a compd. selected from among a fatty acid, lactone, oxyacid condensate, and mono- or polyalkylene glycol and monoether derivative thereof, 0.5-20pts.wt. ethylenically unsatd. carboxylic acid, and 0-91pts.wt. other alpha,beta-ethylenically unsatd. monomer.

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 that contain pigments, the coloring effect on the painted surface decreases due to the dispersion of pigments during manufacturing and aggregation and sedimentation of pigments during storage.
It is well known that undesirable phenomena such as 7-latching (floating), 70-ting (floating and light mottling), and a decrease in gloss occur.

For this reason, generally, an aqueous pigment dispersion is prepared by dispersing the pigment in advance with a dispersant, and this dispersion 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 limited by the type of binder used in water-based paints. There are disadvantages such as receiving 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 with the aim of developing a new agent in an aqueous system, which is a difficult task.

Thus, according to the present invention, in an aqueous pigment dispersion comprising a pigment, a dispersant, and an aqueous medium, the dispersant contains (A) 1 to 97.5 parts by weight of a (meth)acrylic monomer containing a perfluoroalkyl group. (B) 0 (meth)acrylic monomers modified with a compound selected from fatty acids, lactones, oxyacid condensates, mono- or polyfulkylene glycols and monoether derivatives thereof
~96.5 parts by weight (C) (7,β-ethylenically unsaturated nitrogen monomer 2~
97 parts by weight (D) 0.5 to 20 parts by weight of ethylenically unsaturated carboxylic acid and (E) α other than the above (A), (B), (C) and (D).

An aqueous pigment dispersion is provided, which is a water-soluble product of a polymer obtained by copolymerizing 0 to 91 parts by weight of a β-ethylenically unsaturated monomer.

The polymer used as a dispersant for the aqueous pigment dispersion of the present invention is non-crystalline and has a long side chain consisting of a main chain containing a hydrophilic nitrogen-containing monomer and an ethylenically unsaturated carboxylic acid. It has a structure in which the polymers are bonded in a separated form, and since the polymer has a fluoroalkyl group in its side chain, it has a low interfacial tension, good wettability to pigments, and excellent pigment dispersion ability. Furthermore, since the polymer contains both basic components derived from nitrogen-containing monomers and acidic components derived from carboxylic acids, it has the advantage that it is possible to disperse a wide range of pigments such as acidic pigments and basic pigments. are doing. In addition, this dispersant has very good pigment dispersion ability, has a relatively low acid value, and has a small absolute amount of carboxyl groups.
By using the aqueous pigment dispersion of the present invention, it is possible to obtain a good colored coating film that is extremely excellent in properties such as corrosion resistance.

Hereinafter, the dispersant used in the aqueous pigment dispersion of the present invention will be explained in detail.

The fluoroalkyl group-containing (ivy) acrylic monomer (A) used in the present invention includes those containing a fluoroalkyl group in the ester residue portion of acrylic acid or methacrylic acid ester; The term "alkyl group" refers to a linear or branched furkyl group in which at least one hydrogen atom is substituted with a fluorine atom.

Therefore, the fluoroalkyl group-containing (meth)acrylic monomer (A) that can be used in the present invention has the following formula % formula % (1) In the formula, R represents a hydrogen atom or a methyl group, and R "represents a fluoroalkyl group having 2 to 35 carbon atoms, preferably 5 to 15 carbon atoms." Examples include fluoroalkyl esters of acrylic acid or methacrylic acid represented by the following formula R3 CH2= C-COOCm H2m - Cn F 2
n -X(I-1) In the formula, R3 has the above meaning, m is an integer of 1 to 10, n is an integer of 1 to 21, and X represents hydrogen or a fluorine atom. Those shown are suitable, and specifically, the following can be exemplified.

2-Perfluorobutylethyl methacrylate CH.

CH2=C-CO〇-CH2CH2-C,F.

2-Perfluorooctylethyl methacrylate CH.

CH,=c-coo-cH2cH2-c,F.

2-perfluoroiso/nyl ethyl methacrylate CH.

CH2=C-Coo-CH2CH2-(CF2).

2-perfluoro/nylethyl methacrylate CH.

CH2=C-C0O-CH2CH2-C,F.

2-Perfluorodecylethyl methacrylate CH.

CH2=C-Coo-CH2CH,-C,,・F 21
1.1.7-) Lihydroperfluorohebutyl acrylate CH2=CH-Coo-CH2-(CF2), H These can be used alone or in combination of 21g or more. Among the above-mentioned fluoroalkyl group-containing (meth)acrylic monomers, 2-perfluorooctylethyl methacrylate, 2-perfluoroiso/
Nylethyl methacrylate-14, 1.7-) 1j hydroperfluorobutyl acrylate is preferred.

・ Mail ゛! 0 Modified (meth)acrylic monomer (B) used in the present invention
is a radical polymer ((
These are meth)acrylic monomers, and these will be explained in more detail below.

(B-1-) Fatty acid modified (meth)acrylic monomer? The fatty acid-modified acrylic monomers that can be used in the present invention include (meth)acrylic monomers as described below, drying oil fatty acids, semi-drying oil fatty acids, non-drying oil fatty acids, synthetic saturated fatty acids, etc. These include monomers produced by introducing a fatty acid according to the method described below. Here, synthetic saturated fatty acids have 4 to 24 carbon atoms and are artificially induced from natural oils and fats, fatty acids, or petroleum raw materials by methods such as ozone oxidation, paraffin liquid phase air oxidation, oxo method, and Koch method. , preferably a linear or branched saturated aliphatic carboxylic acid having 5 to 18 atoms.

Typical fatty acids that can be used as modifiers include, for example, soybean oil fatty acid, linseed oil fatty acid, soybean oil fatty acid, sesame oil fatty acid, poppy oil fatty acid, dino oil fatty acid, hempseed oil fatty acid, grape kernel oil fatty acid, and corn oil fatty acid. fatty acid,
Drying and semi-drying oil fatty acids such as tall oil fatty acids, castor oil fatty acids, cottonseed oil fatty acids, walnut oil fatty acids, rubber seed oil fatty acids, tung oil fatty acids, olive oil fatty acids, dehydrated castor oil fatty acids, ＼＼, idiene fatty acids; and coconut oil fatty acids. oil fatty acids,
Non-drying oil fatty acids such as olive oil fatty acids, castor oil fatty acids, hydrogenated castor oil fatty acids, palm oil fatty acids; neopentanoic acid, 2-ditylbutyric acid, heptanoic acid, 2-ethylhexanoic acid, isooctanoic acid, nonanoic acid, isononanoic acid, Examples include synthetic saturated fatty acids such as decanoic acid, isodecanoic acid, neodecanoic acid, indoridecanoic acid, isopalmitic acid, and isostearic acid, and these can be used alone or in combination of two or more.

The amount of the fatty acid used can vary widely depending on the drying properties and film performance desired for the aqueous pigment dispersion provided by the present invention, but is generally based on the weight of the resulting polymer. 5-65% by weight, preferably 10-60%
It is advantageous to use amounts that fall within the range of % by weight.

Moreover, among the above-mentioned fatty acids, it is preferable because it can impart crosslinking drying properties at room temperature to a dispersant that yields a drying oil fatty acid and a semi-drying oil fatty acid having an iodine value of about 100 or more.

The (meth)acrylic monomer into which such a fatty acid is introduced is an ester of (meth)acrylic acid containing a functional group capable of reacting with the carboxyl group of the fatty acid, such as an epoxy group or a hydroxyl group, in the ester residue portion. I can give an example.

However, fatty acid-modified (meth)acrylic monomer (B-
The fatty acids described above are introduced to obtain 1) (meta)
One type of acrylic monomer is ``(meth)acrylic acid ester having an epoxy group'' (hereinafter sometimes referred to as ``epoxy-containing (meth)acrylic ester''), and this type of ester is C Preferred are (meth)acrylic esters containing a glycidyl group in the ester residue, particularly glycidyl (meth)7 acrylate. The fatty lS2-modified (meth)acrylic monomer (B-1) using such an epoxy-containing (meth)acrylic ester is usually prepared in accordance with a conventional method in the presence or absence of a suitable inert solvent. This can be carried out by reacting the aforementioned fatty acid with an epoxy-containing (meth)acrylic ester in the absence of a solvent. The reaction is generally carried out at a temperature of about 60 to about 220°C, preferably about 120 to about 1
It can be carried out at a temperature of 70°C, and the reaction time is generally about 0.5 to about 40 hours, preferably about 3 to about 10 hours.

The epoxy-containing (meth)acrylic ester is usually
0.7 to 1.5 mol per mol of said fatty acid, preferably 0.
It is advantageous to use a proportion of 8 to 1.2 mol.

In addition, as an inert solvent used as necessary, 2
Water-immiscible organic solvents that can be refluxed at temperatures below 20° C. are preferred, such as aromatic hydrocarbons such as benzene, toluene and xylene; and aliphatic hydrocarbons such as heptane, hexane and octane.

Furthermore, in the above reaction, a polymerization inhibitor, such as hydroquinone, methoxyphenol, jerk-butylcatechol, benzoquinone, etc., is added to the reaction system as necessary to treat the hydroxyl group-containing acrylic ester and/or the fatty acid modified (meth) produced. ) It is advantageous to suppress acrylic ester polymerization.

In the above reaction, esterification accompanied by ring opening of the oxirane group occurs between the oxirane group (epoxy group) of the epoxy-containing (meth)acrylic ester and the carboxyl group of the fatty acid. An ester is obtained.

In addition, the (meth)acrylic monomer that is reacted with the above fatty acid to produce another type of fatty acid-modified (meth)acrylic monomer (B-1) includes [hydroxyl group-containing (meth)acrylic monomer
meth)acrylic acid ester (hereinafter sometimes referred to as [hydroxyl group-containing (meth)acrylic ester]), this type of ester includes one ester residue in the (meth)acrylic ester. has a hydroxyl group and has 2 to 24, preferably 2 to 8 ester residues.
The following formula (
II) or (III) R.

CHz = CCOO@Cp l(211←OH(I
I) CHx =CCOOHC2H-0chi=(C3Hs
O'rr-H (Ill) In each of the above formulas, R1 has the above meaning, ρ is an integer from 2 to 8, and q and " are each an integer from 0 to 8, provided that ql!:r A hydroxyl group-containing (meth)acrylic ester represented by the following formula is preferable.

Particularly suitable hydroxyl group-containing (meth)acrylic esters in the present invention include hydroxyalkyl acrylate and hydroxyfurkyl methacrylate represented by the above formula (11), especially 2-hydroxyethyl acrylate, 2-
They are hydroxyethyl tutacrylate, 2-hydroxypropyl acrylate and 2-hydroxypropyl methacrylate.

The latter type of fatty acid-modified acrylic monomer (
B-1) is usually prepared by mixing the fatty acid with the hydroxyl group-containing (meth)acrylic ester in an appropriate inert solvent,
This can be carried out by reacting in the presence of an esterification catalyst. The reaction is generally carried out at a temperature of about 100 to about 180°C;
It is preferably carried out under heating at a temperature of about 120 to about 160°C, and the reaction time is generally about 0.5 to about 9 hours, usually about 1 hour.
~about 6 hours.

The hydroxyl group-containing (meth)acrylic ester can usually be used at a ratio of 0.5 to 1.9 mol per mol of the fatty acid, preferably 1.9 mol per mol of the fatty acid. ()～
Advantageously, a proportion of 1.5 mol is used.

Examples of the esterification catalyst used in the above reaction include sulfuric acid, aluminum sulfate, potassium hydrogen sulfate, p-)
Examples include luenesulfonic acid, salt e, methyl acid, phosphoric acid, etc., and these catalysts are usually used in a range of about 0.001 to about the total amount of the above fatty acid and hydroxyl group-containing acrylic ester to be reacted 2.0% by weight, preferably about O,O
It is used in a proportion of S to about 1.0% by weight.

In addition, as an inert solvent used as necessary, 1
Organic solvents that are refluxed at a temperature of 80° C. or lower and immiscible with water are preferred, such as aromatic hydrocarbons such as benzene, toluene, and xylene; and aliphatic hydrocarbons such as heptane, 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.

As yet another method for preparing the fatty acid-modified (meth)acrylic monomer (B-1), in addition to the method described above,
It is also possible to carry out an esterification reaction between a glycidyl ester of an unsaturated fatty acid (for example, 6 Bremmer DFA" manufactured by NOF Corporation) and acrylic acid or methacrylic acid as described above.

(B-2) Lactone or oxyacid condensate-modified (meth)acrylic monomer A (meth)acrylic monomer modified with a lactone or oxyacid condensate that can be used in the present invention (hereinafter referred to as "meth)acrylic monomer" is sometimes referred to as "lactone-modified (meth)acrylic monomer" and "oxyacid condensate-modified (meth)acrylic monomer") is a (meth)7acrylic monomer and lactone or oxyacid. It is a monomer obtained by reacting a condensate, and is typically represented by the following formula (IV) (tV) In the formula, R9 has the above meaning, and R3 is -CtH,L-
group (here, t is an integer of 2 to 8), R7 represents -CH, -CH-CH2- group (herein, R1 has the meaning as described above), and R1 represents -Cu H2U-
(where U is an integer from 2 to 18) and S represents 1 to 7.

The lactone used as a modifier in the modified (meth)acrylic monomer represented by formula (1v) above is a cyclic ester compound containing an ester functional group -CO-0- in the ring, and a typical 1 as a lactone, γ-lactone, δ-lactone C-lactone, γ-caprolactone, δ
-caprolactone, methyl ε-caprolactone (including isomers), and the like.

Further, 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 lactone compounds described above, lysyl/- Examples include oleic acid, oxystearic acid, and lamepalmitic acid. The condensates of these oxyacids are produced in accordance with a conventional method by mixing a mixture of the above-mentioned hydroxy fatty acids, refluxing solvents (xylene, toluene, heptane, etc.) and hyesterification catalysts (methyl sulfuric acid, dodecylbenzenesulfonic acid, etc.) at about 140% This can be carried out by thermal condensation 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 kinds may be used in combination.

Therefore, in order to obtain a lactone-modified (meth)acrylic monomer, the above-mentioned lactone compound is introduced (meth)
As the acrylic monomer, a hydroxyl group-containing (meth)acrylic ester represented by the above formula (1) is preferably used.

The preparation of a lactone-modified (meth)acrylic monomer using such a hydroxyl group-containing (meth)acrylic ester can be carried out by a method known per se, for example, in JP-A-57-195714.
It can be carried out by the method disclosed in the above publication, and usually involves reacting the lactone with the hydroxyl group-containing (meth)acrylic ester in the presence of a catalyst at about 20 to 220°C, preferably at about 50 to 180°C. What you do depends on what you do. 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 1 soo, preferably 400 to 1 soo.
A range of 100 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, as the (meth)acrylic monomer into which the oxyacid condensate described above is introduced to obtain the oxyacid condensate-modified (meth)acrylic monomer, the epoxy-containing (meth)acrylic monomer mentioned above is
Acrylic esters are preferably used.

The oxyacid condensate-modified (meth)acrylic monomer can be prepared by reacting the oxyacid condensate described above with the epoxy-containing (meth)acrylic ester described above. This reaction can be carried out in accordance with the method for preparing fatty acid and epoxy-containing (meth)acrylic esters in the preparation of fatty acid-modified (meth)acrylic monomers described above.

The epoxy-containing (meth)acrylic ester is usually advantageously used in a proportion of 0.7 to 1.5 mol, preferably 0.8 to 1.2 mol, per mol of the oxyacid condensate. In addition, the oxyacid condensate has a molecular weight of about 100 to 2,500
, preferably in the range of about 200 to 2,000.

(B-3> (meth)acrylic monomer modified with mono- or polyfulkylene glycol or its monoether derivative Modified with mono- or polyalkylene glycol or its monoether derivative that can be used in the present invention (
Examples of meth)acrylic monomers (hereinafter sometimes referred to as "fulkylene glycol-modified (meth)acrylic monomers") include (meth)acrylic acid and mono- or polyalkylene glycols, or their monomers. It is an esterified product with an ether derivative, and is typically represented by the following general formula % () where R1 has the above meaning, R1 is a hydrogen atom, C,
-C2゜alkyl group, aryl group (e.g. phenyl group)
or represents an aralkyl group (preferably a pencil group), V is an integer of 2 to 12, and ... is an integer of 1 to 20.

Such a fullylene-modified (meth)acrylic monomer (B-
A specific example of 3) is diethyleneglyfur (meth)
7 acrylate, triethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, cubrobylene glycol (meth) 7 acrylate, tripropylene glycol (meth) 7 acrylate, polypropylene glycol (meth) acrylate, methoxyethylene (meth) Acrylate, ethoxyethylene (meth)
acrylate, butoxyethylene (meth) 7-acrylate, hexyloxyethylene (meth) 7-acrylate, ethoxypropylene (meth) 7-acrylate, ethoxydiethylene (meth) acrylate, butoxydiethylene (meth) 7-acrylate, trisyloxine ethylene (meth) acrylate, Examples include 7-ethylene propylene (meth)acrylate and benzyloxynoethylene (meth)acrylate, each of which may be used alone or in combination with two
More than one species can be used in combination. Further, it is advantageous that the molecular weight of these alkylene-modified (meth)acrylates is generally in the range of 100 to 5,000, preferably 150 to 1,500.

a-Elene\C11Next, as the a,β-ethylenically unsaturated nitrogen-containing monomer (C) used in the present invention, one or more (
Typical examples include unsaturated monomers having a nitrogen-containing heterocycle and V
Examples include nitrogen-containing derivatives of (meth)acrylic acid. Hereinafter, these monomers will be specifically explained.

[1] As an unsaturated monomer having a nitrogen-containing heterocycle, 1
Monomers in which a monocyclic or polycyclic heterocycle containing up to 3, preferably 1 or 2 ring nitrogen atoms are bonded to a vinyl group are included, and the monomers shown below can be particularly mentioned.

(I) Vinylpyrrolidones; For example, 1-vinyl-2-pyrrolidone, 1-vinyl-3
- such as pyrrolidone.

(TI) Vinylpyridines; For example, 2-vinylpyridine, 4-vinylpyridine), 5
-/f-2-vinylpyridine, 5-ethyl-2-vinylpyridine, etc.

(III) Vinylimidazoles; for example, 1-vinylimidazole, 1-vinyl-2-methylimiguzole, etc.

(IV) Vinyl carbazoles; For example, N-vinylcarbazole.

(V) Vinylquinolines; For example, 2-vinylquinoline.

(Vi) Vinylpiperidines; For example, 3-vinylpiperidine, N-methyl-3-vinylpiperidine, etc.゛(Vii) Others; N-(meta)(
Here, R1 has the above-mentioned meaning).
Among the vinyl monomers having a nitrogen-containing heterocycle such as meth)acryloylpyrrolidine, preferred are vinylpyrrolidones, vinylimidazoles, and vinylcarbazoles, among which the ring nitrogen atom is tertiaryized. Preferably.

[2] Nitrogen-containing derivatives of (meth)acrylic acid include those containing a substituted or unsubstituted amino group in the ester moiety of (meth)acrylic acid ester and 7-mide of (meth)acrylic acid, and in particular, the following Formula (vl) or (Vll) \R6 In each of the above formulas, Rs and VRs each independently represent a hydrogen atom or a lower alkyl group, R7 represents a hydrogen atom or a lower alkyl group, and R8 represents a hydrogen atom or a lower alkyl group. ,
represents a di(lower alkyl)amino lower alkyl group, a hydroxy lower alkyl group or a lower flukoxy lower alkyl group, R1 has the above meaning, and ) acrylate and (
meth)acrylamide 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 a specific example of such a nitrogen-containing (meth)acrylic monomer, examples of the 7-alkyl (meth)acrylate of the above formula (Vl) include N,N-dimethylaminoethyl (meth)acrylate. , N,N-diethylami7ethyl (meth)acrylate, N-L-butylami/ethyl (meth)acrylate, N,N-dimethyl7minoprobyl (meth)acrylate, N,N-trimethyl7minobutyl (meth)acrylate, N -Propyl 7-minoethyl (
meth)acrylate, N-butylaminoethyl (meth)
Examples of the (meth)acrylamide of the above formula (Vll) include (di)acrylamide, N-methyl (meth)acryl 7mide, N-ethyl (meth)acryl 7mide, N-ethyl (meth)acryl 7mide, and the like. -Butyl (meth)acrylamide, N,N-dimethyl (meth)acryl 7mide, N
, N-diethyl (meth)acrylamide, N, N-
Dipropyl (meth)acrylamide, N-7 tyrol (
meth)acrylamide, N-double oxymethyl(meth)acrylamide, N-butoxymethyl(meth)acryl7
Mido, N, N-dimethyl 7minobrovir acryl 7mide, and the like are included. As these nitrogen-containing acrylic monomers, those in which the nitrogen atoms present are 1@tertiary are optimal, and those in which the nitrogen atoms are secondary are also preferably used. .

The a, β-ethylenically unsaturated nitrogen-containing monomers mentioned above can be used alone or in combination of two or more.

Next, the ethylenically unsaturated carboxylic acid (D) used in the present invention has an addition-polymerizable double bond between the carbon atom to which the carboxyl group is bonded and the carbon atom adjacent thereto. Suitable are unsaturated aliphatic monomers or polycarboxylic acids of the type having 3 to 8, especially 3 to 5 carbon atoms and having 1 or 2 carboxyl groups, typically: The following general formula (n11) In the formula, R9 represents a hydrogen atom or a lower alkyl group, and R
1° represents a hydrogen atom, a lower alkyl group, or a carboxyl group, and R11 represents a hydrogen atom, a lower furkyl group, or a carboxy lower alkyl group, and those represented by the following general formula (IV) R.

CH2= CCOO-Cy H-y-COOH(I
V) In the formula, y is an integer of 2 to 6, and R1 has the same meaning as above. In the above formula n1l), the lower furkyl group has 4 or less carbon atoms,
A methyl group is particularly preferred.

Examples of such ethylenically unsaturated carboxylic acids (D) include acrylic acid, methacrylic acid, crotonic acid, itafonic acid, maleic acid, maleic anhydride, fumaric acid, 2-carboxyethyl (meth)acrylate, 2-carboxyethyl Examples include (meth)7 acrylate, which can be used alone or in combination of two or more.

a-Elene ＼ 11 Furthermore, there are no particular restrictions on the a,β-ethylenically unsaturated monomer (E) other than the above (A) to (D), and the desired performance of the dispersant of the present invention can be used. You can choose from a wide range of options depending on your needs. Representative examples of such unsaturated monomers are as follows.

(a) Esters of acrylic acid or tutaacrylic acid: for example, methyl acrylate, ethyl acrylate, butyl acrylate, isopropyl acrylate, butyl acrylate,
Hexyl acrylate, octyl acrylate, lauryl acrylate, methyl ivy acrylate, ethyl methacrylate,
C,-,,'r-lkyl esters of acrylic acid or methacrylic acid such as propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, lauryl methacrylate; glycidyl acrylate, glycidyl methacrylate): C2~, alkenyl esters of acrylic acid or methacrylic acid such as 7lyl 7cuturate and allyl methacrylate; 02~.l hydroxyalkyl of acrylic acid or methacrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, etc. Esters: 03-1 alkenyloxyalkyl esters of acrylic acid or tu-taacrylic acid, such as allyloxyethyl 7-acrylate and allyloxymethacrylate-F.

(b) Vinyl aromatic compounds: for example, styrene, α
-Methylstyrene, vinyltoluene, p-chlorostyrene.

(c) Polyolefin compounds: for example, butanoene, isoprene, chloroprene.

(d) Others: 7 Acrylonitrile, methacrylaterile, methyl isopropenyl ketone; vinyl acetate, beoba monomer (Shell Chemical Products'), vinyl propionate, vinyl bivalate, 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 above-mentioned fluoroalkyl group-containing (meth)acrylic monomer (A), acrylic monomer (B), a, β-ethylenically unsaturated nitrogen-containing monomer (C
), ethylenically unsaturated carboxylic acid (D) and unsaturated monomer (E) 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, and turbidity polymerization.

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.

Fluoroalkyl group-containing (meth)acrylic monomer (A)
: 1 to 98 parts by weight, preferably 1 to 95 parts by weight from the viewpoint of coating film performance
Parts by weight, Modified (meth)acrylic monomer (BGO ~ 96.5 parts by weight, preferably 10 to 85 parts by weight in terms of coating film performance, a, β-ethylenically unsaturated nitrogen-containing monomer (C) ;2~9
7 parts 1 part, preferably 3 to 90 from the viewpoint of pigment dispersion
Parts by weight, Ethylenically unsaturated carboxylic acid (D): 0.5 to 20 parts by weight, preferably 2 to 18 parts by weight from the viewpoint of water solubility and coating film performance, Unsaturated other than the above (A) to (D) Monomer (EGO~91
C0 ~, 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 solvent in the presence of a polymerization catalyst, usually at about 0 to about 180°C, preferably about At a reaction temperature of 40 to about 170'C, about 1
This can be carried out by continuing the reaction for 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 produced copolymer and is miscible with water so that delification 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 darkening solvents include those with the formula HO-CH2
Cellosolve solvents of CH2-OR,2 [wherein R12 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms] such as ethylene glycol, butyl cellosolve, ethyl cellosolve, etc.: formula HOCH7-CH-CH.

A propylene glycol solvent such as propylene glycol monomethyl ether O-CH2CH2-OCH2CH2-OR. 2 (wherein R12 has the same meaning as above) carpitol-based solvents such as diethylene glycol, methylcarpitol, butylcarpitol, etc.; formula R..O-CH,
．． CH. -OR,, (where R + 3 and R l
4 each represents a furkyl group having 1 to 3 carbon atoms] Glyme-based solvents such as ethylene glycol dimethyl ether; Formula R. , O-CH2CH20CH. -C
Diglyme-based solvents such as diethylene glycol dimethyl ether, etc. of the formula R., O
-CH2CH20CO-CH (however, R l 5
represents a hydrogen atom or CH3 or C2H] cellosolve acetate solvent such as ethylene glycol monoacetate, methyl cellosolve acetate; formula R40) Examples of alcoholic solvents that can be used include alcoholic solvents such as methoxypropanol, diacetate alcohol, acetone, dimethylformamide, 3-methoxy-3-methyl-butanol, and the like.

However, inert solvents that are immiscible with water can also be used, and water-immiscible solvents that have 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 are suitable. Preferably. Such solvents include, for example, an alkyl group having 1 to 4 atoms or a furkyl group having 1 to 4 atoms.
Aromatic hydrocarbons represented by the formula R2o-C00-R2, . C However, R
2. represents a full 1-kyl group having 1 to 6 carbon atoms, and R
, 1 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a cyclohexyl group] such as acetic acid, ethyl formate, butyl acetate, cyclohexyl acetate, etc.; formula R22R2. C=O (however, R2□ and R23 are carbon atoms fi1-8, respectively)
Examples of alkyl groups include methyl ethyl ketone, cyclohexanone; formula R22-0-R2. [However, R
22 and R2ff have the same meanings as above], such as -thyl ether, hexyl ether, etc.;
represents an alkyl group having 5 to 11 carbon atoms], such as hex/-al.

These solvents contain 15 to 9 of the total weight of the four copolymer components.
It can be used in a range of 0% by weight.

Examples of polymerization catalysts include 7zo compounds, peroxide compounds, sulfides, sulfines, sulfinic acids, diazo compounds, nitrone compounds, redox compounds, and radicals that can be used in normal radical polymerization such as ionizing radiation. An initiator 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. Advantageously, the process is carried out until the temperature is within the range of from about 500 to about 150,000, preferably from about 1,000 to about 10, o o o.

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,
Examples include carbonates or bicarbonates of alkali metals.

As the amine, primary, secondary or tertiary alkylamines; primary, secondary or tertiary fluoramines; and cycloalkylamines can be used. In addition, examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide; examples of alkali metal carbonates and bicarbonates include potassium carbonate, sodium carbonate, and sodium bicarbonate. Among these neutralizing agents, potassium hydroxide and sodium hydroxide are particularly suitable.

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 0.1 to 2.0 equivalents, preferably 0.3 to 1.0 equivalents based on the carboxyl group in the resin.
It is equivalent. ' The water-solubilized polymer thus obtained is used as a dispersant in an aqueous pigment dispersion consisting of a pigment, a dispersant and an aqueous medium.

The amount of the dispersant made of the water-solubilizing polymer used is as follows:
00 parts by weight, generally from about 1 to 500 parts by weight, preferably from about 1 to 300 parts by weight. When the upper limit of this range is exceeded, the balance between coloring power and viscosity of the aqueous pigment dispersion tends to be 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:
Although it is essentially water, a hydrophilic organic solvent can be used in combination if necessary, for example, if the degree of hydrophilicity of the dispersant is low and sufficient pigment dispersion performance cannot be obtained. 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 dispersions of the present invention can be inorganic and organic pigments commonly used in pigment dispersions of this type, for example, as inorganic pigments,
(1) Oxide type (zinc white, titanium dioxide, red iron oxide, chromium oxide, cobalt blue, iron black, etc.); (2) Hydroxide type (alumina white, yellow iron oxide*); (3) Sulfide, selenium Compounds (Sulfide Oksho, Vermilion, Cadmium Yellow, Chikara V Milam Rerad, etc.): (4) 7 Dirosyanides (Kuzei, etc.): (5) Chromate-based (Hondo copper, non-chromate, molybdenum red, etc.) ): (6) Sulfate-based (precipitated barium sulfate, etc.): <7) Carbonate-based (precipitated calcium carbonate, etc.); (8) Sulfate-based (hydrated silicate, clay, ultramarine, etc.): (9 ) Phosphate type (manganese violet etc.); (
10') Carbon 1k (carbon black, etc.): (11)i
Examples of organic pigments include (1) 2) nitro pigments (naphthonyl green B, etc.); (2) nitro pigments (naphthonyl green B, etc.);
7 Tall Yellow S, etc.): (3) 7 Pigment system (Resol Red, Lake Red C, Fast Yellow, Naphthol Red, etc.); (4) Dyeing lake pigment system (Alkali Blue Lake, Rhodamine Lake, etc.): (5) (6) fused polycyclic pigment systems (perylene red, quinacridone red, dioxanone violet, isoindolinone yellow, etc.) and the like.

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, such as a ball commonly used in the paint industry. Milling grinders, shakers, attritors, etc. are included.
(It's cold.

If necessary, conventionally known surfactants and protective colloids can be added to the aqueous pigment dispersion of the present invention.

In the thus obtained aqueous pigment dispersion of the present invention, 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 aqueous pigment dispersion of the present invention can be applied to alkyd resins, acrylic resins, etc. used in water-based paints and inks,
Epoxy resin, urethane? ．． It has good miscibility with conventionally known water-soluble resins such as resins, maleated polybutadiene resins, water-dispersible resins, emulsions, etc., and is not limited by these resins, and can be used for coloring water-based paints made of any resin. can also be widely used.

As a specific example of the above-mentioned water-based resin, for example, alkyd resin is synthesized from the same raw materials as conventional solvent-type fulkyto resin, and is obtained by subjecting polybasic acid, polyhydric alcohol, and oil components to an n-condensation reaction using a conventional method. It is something that can be done. Acrylic resin is a
, 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, ethyl methacrylate, propyl methacrylate, butyl methacrylate, etc.) and vinyl aromatic compounds (such as styrene, vinyltoluene, etc.). As an epoxy resin, an epoxy ester is synthesized by a reaction between an epoxy group of an epoxy resin and an unsaturated fatty acid, and a is added to this unsaturated group.

Examples include epoxy ester resins obtained by a method of adding a β-unsaturated acid or a method of esterifying a hydroxyl group of an epoxy ester with a polybasic acid such as heptatalic acid or trimellitic acid.

In addition, the urethane resin is a resin formed by introducing a urethane group into the resin skeleton using a polyisocyanate compound (for example, toluene diisocyanate, nophenylmethane diisocyanate, 1,6-hexane diisocyanate, isophorone noisocyanate, etc.), and A carboxyl group is introduced using dimethylolpropionic acid or the like.

When using the water-based resin described above as water-soluble, the resin is synthesized to have an acid value of about 35 to 200, and this is neutralized with an alkaline substance such as sodium hydroxide or amine to make it water-soluble. Used 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 type resin of about 5 to 35, and this resin is neutralized and used as a water-dispersed paint.

In addition, emulsions include emulsifier-dispersed emulsions obtained by dispersing alkyd resins, acrylic resins, epoxy resins, and urethane resins using anionic or nonionic low-molecular-weight surfactants; Emulsion polymerization emulsion obtained by emulsion polymerization of monomers such as acrylic acid ester, acrylonitrile, styrene, butanoene, vinyl acetate, vinyl chloride, etc.; maleated polybutadiene, maleated furquito resin, maleated fatty acid modified vinyl fat, drying oil Alternatively, there may be mentioned a soap-free emulsion obtained by emulsion polymerization and graph F reaction of the monomers described above using a water-soluble resin such as semi-drying oil fatty acid modified acrylic +A (fat) as an emulsion stabilizer.

The aqueous pigment dispersion of the present invention is particularly effective when blended into water-based paints consisting of low acid value water-dispersible resins and emulsions, which have poor pigment dispersibility.

The distribution ratio of the aqueous pigment dispersion of the present invention to the aqueous paint can be varied within a wide range depending on the type of pigment in the dispersion and the degree of coloring required for the final paint, but in general, The pigment dispersion can be blended in an amount of 2 to 1000 parts by weight per 100 parts by weight of the resin content of the aqueous paint.

Next, the present invention will be further explained by examples.

In the examples, parts and % indicate parts by weight and % by weight, respectively.

Production Example 1: - 1 l 81 I-previous safflower oil fatty acid 236 parts glycidyl methacrylate tis part hydroquine 0.4 part tetraethylammonium bromide 0.2 part After putting the above components into a reaction container, the reaction solution was The addition reaction was carried out while stirring while maintaining the reaction temperature at 140 to 150°C. The addition reaction between epoxy groups and carboxyl groups was monitored while measuring the amount of remaining carboxyl groups. The fatty acid-modified acrylic monomer (a) was obtained in a reaction time of about 4 hours.

Production Example 2: - Ile b ゛1 Safflower oil fatty acid 70.9 parts Hydroquinone 0.03 parts N-heptane 4.56 parts The above ingredients were placed in a reaction vessel and the temperature was raised to 160°C while stirring. Next, the following ingredients: Hydroxyethyl methacrylate 41.2 parts Hydroquinone
0.03 parts dodecylbenzene, 0.03 parts sulfonic acid.
9581S toluene
3.7 parts of the mixture was added dropwise into a reaction vessel at 160° C. over a period of 2 hours. The produced condensation water was removed from the reaction system, and the acid value of the reaction product was 5.5 and the donor viscosity was A2.
, the pressure in the reaction vessel is reduced, toluene and 1-hebutane are removed under reduced pressure, and the acid value is 5.0 and the donor viscosity is A.
A fatty acid-modified acrylic monomer (b) of No. 1 was obtained.

Production Example 3: - 1 l 1 l 1 isononanoic acid 133 parts glycidyl methacrylate) 119 g hydroquinone
0.3 parts Tetraethylammonium bromide 0.2 parts The above components were subjected to an addition reaction under the same conditions as in Production Example 1 to obtain a fatty acid-modified acrylic monomer (c).

Production Example 4: 61.8 parts of isopalmitic acid, 0.03 parts of hydroquinone, and 4.56 parts of n-hebutane were placed in a reaction vessel and heated to 160°C while stirring. Next, the following ingredients: Hydroxyethyl methacrylate 41.2ff
B Hydroquinone 0.03 parts Y Decylbenzenesulfone 1'12 0.9
5fflS toluene 3
．． 7 parts were reacted under the same conditions as in Production Example 2 and removed under reduced pressure to obtain a fatty acid-modified acrylic monomer (d) having an acid value of 5.0 and a -donor viscosity of A.

12-hydroxystearic acid 2155% toluene
383 parts and 4.3 n of monomethylsulfone e were placed in a reaction vessel, and the reaction was allowed to proceed at 145° C. for about 4 hours while removing the produced condensation water from the system. When the resin acid value reached 34.0, 221 parts of glycidyl methacrylate, 2 parts of hydroquinone, and 10 parts of tetraethylammonium fluoride were added, and the mixture was reacted at a reaction temperature of 145°C for about 6 hours to form a tj (oxyacid condensation with a fatty acid value of 5.8). Modified acrylic monomer (e)
I got it.

Production example 6: 1-mu ゛ 3~U-・tll-
350 parts of 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.

2-Perfluoroisononylethyl methacrylate 13 parts Fatty acid modified acrylic monomer (a) 100
Parts N-vinylpyrrolidone 126 parts Acrylic acid 11 parts Azobisdimethylvaleronitrile 17.5 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 addition, 7 Zopis Add 2.5 parts of isobutyronitrile to the reaction solution, and add 2.5 parts of isobutyronitrile to the reaction solution.
After an hour, 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.

After the reaction, unreacted monomers and n-butyl cellosolve were distilled under reduced pressure, leaving a heating residue of 70.7% and a resin acid value of 35.4.
A dispersant copolymer solution (a) having a donor viscosity (40% n-butyl cellosolve solution) of J was obtained.

Similarly, a polymerization reaction and vacuum distillation were carried out using the formulations shown in Table 1 below under the same conditions as in Production Example 6 to obtain copolymer solutions (1) to (u) for dispersants. Copolymer solution for dispersant (
The properties of a) to (u> are summarized in the table below.

The copolymer obtained in Production Example 6 was neutralized with triethylamine (1.0 equivalent neutralization), and water was added to reduce the heating residue to 40%.
An aqueous dispersant (A) consisting of an aqueous solution of was obtained. Similarly, the copolymer solutions for dispersants (b) to (,) were water-solubilized to obtain aqueous dispersants (B) to (U).

Next, water was added to a mixture of 8.3 parts of this aqueous dispersant (A) and 200 parts of titanium white pigment (Titan White R-5N manufactured by Sakai Kagaku Co., Ltd.), and Red Deui was dispersed for 1 minute and then dispersed for 0.5 hours. Finally, an aqueous pigment dispersion (2) of the present invention was obtained.

Pigments were similarly dispersed according to the formulations shown in Tables 2 to 5 below to obtain aqueous pigment dispersions ① to ＠ 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-2 below.
5.

Example 1 10 g of the aqueous pigment dispersion ■ obtained in Production Example 7 and water-dispersed alkyd resin (linseed oil fatty acid/pentaerythritol/benzoic acid/isophthalic acid/maleic anhydride = 9
03/705/1140/'610/45 (parts) as raw material, solid content 40 parts solution obtained by neutralizing 1°0 equivalent of fulkyto resin with oil length 30 and acid value 16 with triethylamine Q) 23°4 A water-based paint was obtained by thoroughly mixing the formulation consisting of the following parts. The coating performance of the obtained water-based paint is shown in Table 6 below.

Examples 2-41 In the same manner as in Example 1, water-based paints were prepared by sufficiently mixing the aqueous pigment dispersions ① to 0 shown in Tables 6-9 below and a water-based resin composition. did. Determine the film performance of the obtained water-based paint. ・See Table 6 below.
9.

Comparative Example Commercially available pigment dispersant 5MAl 44+)H (ARCOCI
Titanium white R-5N (titanium oxide, trade name, manufactured by Sakai Chemical Co., Ltd.) was prepared using titanium white R-5N (titanium oxide, trade name, manufactured by Sakai Chemical Co., Ltd.) at a solid content weight ratio of titanium white/dispersant = 22/ A water-based paint for comparison was obtained by mixing 10 parts of a pigment dispersion (pigment content 70.0%) dispersed at a ratio of Membrane performance is shown in Table 9 below.

(*1) 2-perfluoroisononylethyl methacrylate (*2) 2-perfluorooctylethyl methacrylate (*3) 1,1.7) Rehydroperfluoroheptyl acrylate (*4) Manufactured by Daicel Chemical Co., Ltd., ε- Caprolactone-modified vinyl monomer 1 (formula,
O CHPCCH, COO-C, H4-0-4-C-C5E
1°-0-17H compound) (*5) Daicel Chemical Co., Ltd., ε-caprolactone modified vinyl monomer (formula, 0 CHFCCHi 00- C,H,-0+C-C,Hl
o-0+1l-H compound) (*6) Manufactured by Nippon Oil & Fats Co., Ltd., formula, CHr:CCH,COO
-+CH,CH,-0) -H (however, nFi7-9 integer) Compound (*7) Manufactured by Usuda Yushi Co., Ltd., formula CE2=CCH,C00-
-fCH, CHCE, -05H (where n is 5 to 6
Compound (*8) manufactured by Shin Nakamura Chemical Co., Ltd., formula CH, =CHC00-(
*9) Manufactured by Alcolac, USA (*10) Measured with 411%-butyl cellosolve solution (*11) Titanium white R-5#: Titanium oxide carbon MA manufactured by Sakai Chemical Co., Ltd.: Carbon black copper phthalocyanine green 6YK manufactured by Mitsubishi Chemical Corporation: Toyo Yellow GKZR-8 manufactured by Ink Manufacturing Co., Ltd. (*12) Measured according to ASTM D1201-64 (*13) 30 parts of a neutralized product of the water-dispersed alkyd resin used in Example 1 with an acid value of 60 An emulsion obtained by polymerizing 70 parts of n-butyl acrylate (solid content 40%) (*14) using sodium salt of dodecylbenzene as an emulsion stabilizer, and styrene/methyl methacrylate/n-
An emulsion obtained by polymerizing a monomer mixture consisting of butyl methacrylate = 35/15/50 (
Solid content: 50%) [Coating film performance trial] The water-based paints shown in Examples 1 to 41 were coated with a water-based dryer (
A product of Dainippon Ink Co., Ltd. under the trade name "Dakenade" (cobalt metal content: 30%) was added at a ratio of 1 part to 100 parts of resin solid content, and coated on a mild steel plate.

After drying for 3 days at 20° C. and relative humidity of 75° C., it was used for testing.

Goban adhesion: A test was carried out by making 100 gobans of one width, pasting cellophane adhesive tape thereon, 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] In an aqueous pigment dispersion consisting of a pigment, a dispersant, and an aqueous medium, the dispersant comprises (A) 1 to 97.5 parts by weight of a (meth)acrylic monomer containing a fluoroalkyl group (B) 0 to 96.5 parts by weight of (meth)acrylic monomer modified with a compound selected from fatty acids, lactones, oxyacid condensates, mono- or polyalkylene glycols and monoether derivatives thereof (C) α,β-ethylene 2 to 97 parts by weight of an ethylenically unsaturated nitrogen monomer (D) 0.5 to 20 parts by weight of an ethylenically unsaturated carboxylic acid and (E) other than the above (A), (B), (C) and (D) α
, a water-soluble pigment dispersion, which is a water-soluble product of a polymer obtained by copolymerizing 0 to 91 parts by weight of a β-ethylenically unsaturated monomer.