Pigment dispersant

Abstract

To provide an additive for hydraulic compositions that can impart appropriate flowability and air entrainment properties to the hydraulic compositions for extended periods of time even if the formulations are different.SOLUTION: A pigment dispersant contains a polycondensation product of a monomer mixture containing a compound represented by formulas (A) to (C) in the figure, where the polycondensation product has a novolac structure and an HLB value of 10.0 to 19.5.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a pigment dispersant and a pigment dispersion liquid containing a phenolic polycondensate. More specifically, the present invention relates to a pigment dispersant and a pigment dispersion liquid that can achieve good dispersibility not only in hydrophilic pigments and hydrophobic pigments but also in a mixed system of hydrophilic pigments and hydrophobic pigments, and can provide a dispersion liquid with excellent color separation suppression and color tone stability.

Background Art

[0002] In recent years, due to efforts to address environmental issues and safety reasons, the water-based conversion of inks and paints has been progressing. However, inorganic pigments and organic pigments used in these paints and the like all have low affinity for water and are not easily dispersed in water. Against this background, dispersants for improving pigment dispersibility have been proposed in pigment dispersion compositions such as inks and paints (see Patent Documents 1 to 4).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, pigment dispersants are designed to balance the parts of the pigment that adsorb to the pigment with the parts of the solvent that have high affinity for the dispersion medium, according to the surface condition of the pigment to be dispersed. For this reason, many pigment dispersants useful for specific types of pigments have been proposed, such as those for hydrophilic pigments like titanium dioxide, or hydrophobic pigments like carbon black. On the other hand, designing a dispersant that is useful for both hydrophilic and hydrophobic pigments, which have different surface conditions, is difficult, and we have not yet been able to provide a pigment dispersant that can provide sufficient dispersibility and dispersion stability for either type of pigment.

[0005] Furthermore, paints and other products often use a mixture of multiple pigments. For example, in the manufacture of colored paints, in order to efficiently obtain a paint of the target color, a white paint mainly composed of white pigment is manufactured, and then a slurry of colored pigments is added to it to achieve the target color. The use of a mixture of multiple pigments not only easily causes pigment aggregation and sedimentation, but also presents problems such as color unevenness and color separation.

[0006] This invention has been made in view of the above problems, and aims to provide a pigment dispersant that provides excellent dispersibility and dispersion stability for both hydrophilic and hydrophobic pigments, and that does not aggregate even when these pigments are mixed, and has excellent color matching properties. [Means for solving the problem]

[0007] As a result of diligent research, the inventors considered using a phenolic polycondensate as a pigment dispersant. By focusing on the HLB value of the condensate having a novolac structure, they discovered that it is possible to provide a pigment dispersant that can impart good dispersibility to both hydrophilic and hydrophobic pigments, as well as to mixed systems of these pigments, thus completing the present invention.

[0008] In other words, the present invention covers the following [1] to [8]. [1] It contains a polycondensate of a monomer mixture containing compound A represented by the following formula (A), compound B represented by formula (B), and one or more aldehyde compounds C represented by formula (C). A pigment dispersant in which the polycondensate has a novolak structure and has an HLB value of 10.0 to 19.5.

Chemical formula

Chemical formula

[0009] The pigment dispersant of the present invention can form a dispersion with suppressed aggregation and precipitation when used with both hydrophilic and hydrophobic pigments, thereby exhibiting excellent dispersion performance. In particular, when the pigment dispersant of the present invention is added to a mixture of hydrophilic and hydrophobic pigments, these pigments do not aggregate, and the occurrence of color separation (separation into upper and lower layers) and color unevenness (partial concentration distribution) is suppressed, forming a dispersion with excellent color matching stability. [Modes for carrying out the invention]

[0010] Paints are generally composed of pigments, resins, solvents (such as water), and additives including pigment dispersants. As mentioned earlier, to obtain a paint of a desired color, a white paint is usually first produced, and then another pigment slurry is added to adjust the color until the desired color paint is obtained. Pigment dispersants used for hydrophilic pigments and those used for hydrophobic pigments are almost always different, and when mixing these pigments to create a color, the compatibility of the two types of pigment dispersants is not always good. Furthermore, paints may contain other additives besides pigment dispersants, such as defoamers. The compatibility of these other additives with the pigment dispersants must also be considered, and it is easy to imagine that the more types of additives there are, the more difficult it becomes to achieve good pigment dispersibility, suppression of color separation and color shifting, and color matching stability. With the above-mentioned difficulties in paint manufacturing in mind, the inventors investigated the construction of a pigment dispersant that can handle hydrophilic pigments, hydrophobic pigments, and even hydrophilic / hydrophobic pigment mixtures with a single agent. While conducting various studies on pigment dispersants, including orientation to each pigment, and repulsion due to charge and steric hindrance, they discovered that when a polycondensate of phenolic compounds, particularly a polycondensate having a novolac structure, has a specific HLB value range, it can become a pigment dispersant that solves the above problems and also suppresses foaming during manufacturing, thus completing the present invention.

[0011] As stated above, the pigments to which the pigment dispersant according to the present invention can be applied are not particularly limited. For example, it can be applied to any hydrophilic pigment such as calcium carbonate, talc, silica, titanium dioxide, alumina, and iron oxide, as well as azo pigments, phthalocyanine pigments, carbon black, graphite, and hydrophobic resins. Furthermore, it can also provide good dispersibility in mixed systems of hydrophilic and hydrophobic pigments. The polycondensate of the present invention and the additive for hydraulic compositions containing it will be described in detail below.

[0012] <Pigment dispersant> The pigment dispersant of the present invention includes alkylene oxide adducts or derivatives thereof of phenolic compounds such as phenol and bisphenol A (compound A represented by formula (A)), phosphate esters or sulfate ester derivatives of alkylene oxide adducts of phenolic compounds (compound B represented by formula (B)), and aldehydes (one or more aldehyde compounds C represented by formula (C)), and optionally includes polycondensates of monomer mixtures containing other monomer compounds D such as lignin, or other monomer components such as alkylene oxide adducts or derivatives thereof of hydroxyethylphenol, that is, copolymers obtained by polycondensing these monomer mixtures. In this specification, the polycondensate, that is, the "polycondensate containing a copolymer obtained by polycondensing a monomer mixture," means (1) An embodiment comprising a copolymer (copolymer 1) in which all of the monomer mixtures A to C are polycondensed, (2) An embodiment comprising a copolymer (copolymer 2) obtained by polycondensation of all of the monomer mixture, compounds A to C and other monomer components (at least one other monomer compound D, etc.), (3) The monomer mixture includes a copolymer (polymer 3) obtained by polycondensation of two of compounds A to C. (4) An embodiment in which the monomer mixture includes a copolymer (polymer 4) obtained by polycondensation of one or two of compound A to compound C and other monomer components. (5) An embodiment comprising two or more copolymers from (1) to (4) above. (6) an embodiment comprising one or more copolymers from (1) to (4) above, in addition to at least one of the unreacted compounds A to C and other monomer components, It encompasses all of these, and generally includes unreacted components and by-reactants generated during each polymerization step, the preparation steps of each component (compound A to compound C, and other monomer components), such as the alkylene oxide addition step. The following provides a detailed description of compounds A through C, as well as other monomeric components, contained in the monomer mixture.

[0013] Compound A represented by formula (A) Compound A is a phenolic compound such as phenol or bisphenol A, or an alkylene oxide adduct or derivative thereof of a substituted compound thereof, and has a structure represented by the following formula (A). [ka] In the above formula, n represents 1 or 2, and R 1 When n represents 1, it represents a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms; when n represents 2, it represents -CH2-, -C(CH3)2-, or -SO2-. A 1 O represents an alkylene oxy group with 2 to 4 carbon atoms, m represents the average number of added moles of alkylene oxide, ranging from 1 to 200, and R 2represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an acyl group having 2 to 24 carbon atoms.

[0014] Compound A is a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to a phenolic compound such as phenol or bisphenol A, or a substituted thereof, and derivatives of the alkylene oxide adduct (alkyl ester or fatty acid ester) are also included in Compound A. Examples of alkylene oxides having 2 to 4 carbon atoms include ethylene oxide, propylene oxide, and butylene oxide. These alkylene oxides can be added individually or in combination. When using two or more alkylene oxides, either block addition or random addition is acceptable.

[0015] That is, A above 1 Examples of alkylene oxy groups with 2 to 4 carbon atoms in O include ethylene oxy groups, propylene oxy groups, and butylene oxy groups. 1 O may consist only of an ethyleneoxy group, a propyleneoxy group, or a butyleneoxy group, or it may contain two or more of these groups. If it contains two or more groups, the addition method may be random addition or block addition. Furthermore, m represents the average number of added alkylene oxy groups, which is a number from 1 to 200, preferably from 1 to 150, for example, a number from 5 to 100.

[0016] The above R when n is 1 1 Examples of hydrocarbon groups having 1 to 24 carbon atoms include alkyl groups having 1 to 24 carbon atoms, alkenyl groups having 2 to 24 carbon atoms, unsaturated aliphatic hydrocarbon groups having 4 to 24 carbon atoms with two or more unsaturated bonds, aryl groups having 6 to 20 carbon atoms, and aralkyl groups having 3 to 24 carbon atoms. Examples of alkyl groups having 1 to 24 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl (lauryl), tetradecyl (myristyl), hexadecyl (palmityl), octadecyl (stearyl), eicosyl, docosyl (behenyl), and tetracosyl groups, which may have branched structures (e.g., isopropyl, isobutyl, sec-butyl, tert-butyl, neopentyl, etc.) and / or cyclic structures (e.g., cyclopropyl, cyclopentyl, cyclohexyl, 1-adamantyl, etc.). Examples of alkenyl groups having 2 to 24 carbon atoms include the alkyl groups having 2 to 24 carbon atoms listed above, which have one carbon-carbon double bond. Specifically, these include ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, dodecenyl, tetradecenyl, pentadecenyl, hexadecenyl, octadecenyl, eicocenyl, dococenyl, and tetracocenyl groups, which may have branched and / or cyclic structures. Furthermore, unsaturated aliphatic hydrocarbon groups having two or more unsaturated bonds between 4 and 24 carbon atoms include decadienyl group, undecadienyl group, dodecadienyl group, tridecadienyl group, tetradecadienyl group, pentadecadienyl group, hexadecadienyl group, heptadecadienyl group, octadecadienyl group, nonadecadienyl group, eicosadienyl group, henicosadienyl group, docosadienyl group, tricosadienyl group, Examples include tetracosadienyl group, decatrienyl group, undecatrienyl group, dodecatrienyl group, tridecatrienyl group, tetradecatrienyl group, pentadecatrienyl group, hexadecatrienyl group, heptadecatrienyl group, octadecatrienyl group, nonadecatrienyl group, eicosatrienyl group, henicosatrienyl group, docosatrienyl group, tricosatrienyl group, and tetracosatrienyl group. Furthermore, examples of aryl groups having 6 to 20 carbon atoms include, but are not limited to, phenyl, naphthyl, anthryl, and phenanthryl groups. An aralkyl group is an alkyl group substituted with an aryl group, and specific examples of such aryl and alkyl groups are the same as those mentioned above. Specific examples of aralkyl groups having 7 to 20 carbon atoms include, but are not limited to, phenylmethyl (benzyl) group, α-methylbenzyl group, 2-phenylethyl group, 1-methyl-1-phenylethyl (cumyl) group, 3-phenylpropyl group, and 2-phenyl-2-propyl group. If n is 2, then the above R 1 represents -CH2-, -C(CH3)2-, or -SO2-. Note that in both cases where n is 1 and where n is 2, R in equation (A) 1 The bonding position is not particularly limited, but it is preferable that it is bonded in the para position relative to the oxygen atom bonded to the aromatic ring, as this facilitates the exertion of the effects of the present invention.

[0017] The above R 2 The alkyl group having 1 to 10 carbon atoms in the above R may have a branched structure and / or a cyclic structure, specifically the above R 1 Among the groups listed as specific examples of alkyl groups having 1 to 24 carbon atoms, alkyl groups having 1 to 10 carbon atoms can be cited. Specifically, examples include methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, neopentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, n-octyl group, n-decyl group, 1-adamantyl group, etc. Furthermore, examples of acyl groups having 2 to 24 carbon atoms include saturated or unsaturated acyl groups (R'(CO)- group, where R' is a hydrocarbon group having 1 to 23 carbon atoms). For example, saturated acyl groups having 2 to 24 carbon atoms include carboxylic acids such as acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid (caproic acid), heptanoic acid, octanoic acid (caprylic acid), nonanoic acid, decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), pentadecanoic acid (pentadecylic acid), hexadecanoic acid (palmitic acid), heptadecanoic acid (margaric acid), octadecanoic acid (stearic acid), nonadecanoic acid, eicosanoic acid (arachidic acid), docosanoic acid (behenic acid), and tetracosanoic acid (lignoceric acid). Fatty acid-derived acyl groups include monounsaturated acyl groups derived from monounsaturated fatty acids such as myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, and nervonic acid; diunsaturated acyl groups derived from diunsaturated fatty acids such as linoleic acid, eicosadienoic acid, and docosadienoic acid; and triunsaturated acyl groups derived from triunsaturated fatty acids such as linolenic acid, pinolenic acid, eleostearic acid, meadic acid, dihomo-γ-linolenic acid, and eicosatrienoic acid.

[0018] Compound A, represented by the above formula (A), can be used individually or in combination of two or more types.

[0019] In one embodiment of the polycondensate according to the present invention, in compound A, when n=1, the above A 1 It is preferable that the compound contains at least an ethyleneoxy group as O. For example, in a compound represented by formula (A), (A 1 It is preferable that the proportion of ethyleneoxy groups in O) is 20 mol% to 100 mol%, 50 mol% to 100 mol%, or 80 mol% to 100 mol%. When n=1 (A 1By setting the proportion of ethyleneoxy groups in O) within the above range, and further increasing that proportion, it is expected that when the pigment dispersant containing the resulting polycondensate is blended into a dispersion containing a hydrophobic pigment, the increase in the viscosity of the dispersion over time will be suppressed.

[0020] Furthermore, in one embodiment of the polycondensate according to the present invention, when n=2 in compound A, When a pigment dispersant containing a polycondensate is incorporated into a dispersion containing a hydrophilic pigment, it is expected to be even more effective in reducing the viscosity of the dispersion. Furthermore, when the pigment dispersant of this embodiment is incorporated into a dispersion containing a hydrophobic pigment, it is expected to exhibit an effect of reducing the initial viscosity of the dispersion.

[0021] Compound B represented by formula (B) Compound B is a phosphate ester derivative or sulfate ester derivative of an alkylene oxide adduct of a phenolic compound such as phenol or bisphenol A, and has a structure represented by the following formula (B). [ka] In the above formula, q represents 1 or 2, and R 3 When q represents 1, it represents a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms; when q represents 2, it represents -CH2-, -C(CH3)2-, or -SO2-. A 2 O represents an alkylene oxy group with 2 to 4 carbon atoms, p represents the average number of added moles of alkylene oxide, ranging from 1 to 200, and X 1 This represents a phosphate ester group or a sulfate ester group.

[0022] The above compound B is a phosphate ester derivative or sulfate ester derivative of a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to a substituted compound of phenol or bisphenol A. Examples of alkylene oxides having 2 to 4 carbon atoms include ethylene oxide, propylene oxide, and butylene oxide. These alkylene oxides can be added individually or in combination. When using two or more alkylene oxides, either block addition or random addition is acceptable.

[0023] That is, A above 2 Examples of alkylene oxy groups with 2 to 4 carbon atoms in O include ethylene oxy groups, propylene oxy groups, and butylene oxy groups. 2 O may consist only of an ethyleneoxy group, a propyleneoxy group, or a butyleneoxy group, or it may contain two or more of these groups. If it contains two or more groups, the addition method may be random addition or block addition. Furthermore, p represents the average number of moles of alkylene oxide added, which is between 1 and 200, preferably between 1 and 100, for example, between 1 and 10.

[0024] In one embodiment of the polycondensate of the present invention, n=1 in compound A and the average number of added moles p of alkylene in compound B is less than 4. By incorporating a pigment dispersant containing the polycondensate obtained from these compounds into a dispersion containing a hydrophobic pigment, an improvement in the wettability (affinity) of the hydrophobic pigment to the dispersion medium can be expected.

[0025] The above R when q is 1 3 Examples of hydrocarbon groups having 1 to 24 carbon atoms include alkyl groups having 1 to 24 carbon atoms, alkenyl groups having 2 to 24 carbon atoms, unsaturated aliphatic hydrocarbon groups having 4 to 24 carbon atoms with two or more unsaturated bonds, aryl groups having 6 to 20 carbon atoms, and aralkyl groups having 3 to 24 carbon atoms. Also, if q is 2, then the above R 3 represents -CH2-, -C(CH3)2-, or -SO2-. Examples of these include R 1 The same things can be cited. Note that in both the case where q is 1 and the case where q is 2, R in equation (B) 3 The bonding position is not particularly limited, but it is preferable that it is bonded in the para position relative to the oxygen atom bonded to the aromatic ring, as this facilitates the exertion of the effects of the present invention.

[0026] Also X 1 When represents a phosphate ester group, they are phosphate monoesters and / or salts thereof, phosphate diesters and / or salts thereof, or phosphate triesters, or mixtures thereof, and X 1 When represents a sulfate ester group, they are sulfate monoesters and / or salts thereof, or sulfate diesters, or mixtures thereof. Examples of the above-mentioned phosphate ester salts or sulfate ester salts include alkali metal salts such as sodium and potassium; group 2 metal salts such as calcium or magnesium; ammonium salts; and organic ammonium salts such as alkylammonium or alkanolammonium. Compound B may be synthesized by known methods using a (poly)oxyalkylene alkylphenol with a phosphorylating agent or sulfating agent. Examples of phosphorylating agents include phosphoric anhydride, phosphoric acid, polyphosphate, and phosphorus oxychloride, while examples of sulfating agents include chlorosulfonic acid, sulfamic acid, and direct sulfation using sulfur.

[0027] As an example of compound B represented by the above formula (B), when q is 1, compound B can be given as the compound represented by the following formula. Note that in the formula, R 3 , A 2 O and n represent the same elements as defined in formula (B) above, and Ph represents a phenylene group. M represents a hydrogen atom; an alkali metal atom such as sodium or potassium; an alkaline earth metal atom such as calcium or magnesium; an ammonium group; or an organic ammonium group such as an alkylammonium group or an alkanolammonium group. Furthermore, Z represents a polyoxyalkylene alkyl ether residue represented by the formula: R''-O-(A'O)w- (wherein R'' represents an alkyl group having 1 to 24 carbon atoms, A'O represents an alkylene oxy group having 2 to 3 carbon atoms, i.e., an ethylene oxy group or a propylene oxy group, and w represents the average number of added moles of the alkylene oxy group A'O, which is 1 to 100). If there are multiple Zs, they may be the same group or different groups. • Phosphate monoesters and their salts R 3 -Ph-O-[A 2 O] p -P(=O)(-OM)2 • Phosphate diesters and their salts [R 3 -Ph-O-[A 2 O] p -]2P(=O)(-OM) [R 3 -Ph-O-[A 2 O] p -](Z-)P(=O)(-OM) • Triester phosphate [R 3 -Ph-O-[A 2 O] p -]3P(=O) [R 3 -Ph-O-[A 2 O] p -]2(Z-)P(=O) [R 3 -Ph-O-[A 2 O] p -](Z-)2P(=O) • Monoester sulfates and their salts R 3 -Ph-O-[A 2 O] p -S(=O)2(-OM) • Diester sulfate [R 3 -Ph-O-[A 2 O] p -]2S(=O)2 [R 3 -Ph-O-[A 2 O] p-](Z-)S(=O)2

[0028] Compound B, represented by the above formula (B), can be used individually or in combination of two or more types.

[0029] Compound C represented by formula (C) Compound C is an aldehyde and has the structure represented by the following formula (C). [ka] In the formula, R 4 represents a hydrogen atom, a carboxyl group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a phenyl group, a naphthyl group, or a heterocyclic group, and r represents a number from 1 to 100. These alkyl groups, alkenyl groups, phenyl groups, naphthyl groups, and heterocyclic groups may be substituted with any substituents such as alkyl groups having 1 to 10 carbon atoms; aryl groups such as phenyl and naphthyl groups; halogen atoms such as chlorine and bromine atoms; sulfonic acid functional groups such as sulfo groups and sulfonic acid bases; acyl groups such as acetyl groups; hydroxyl groups; amino groups; and carboxyl groups. The above R 4 The alkyl group having 1 to 10 carbon atoms and the alkenyl group having 2 to 10 carbon atoms in the above compound A (formula (A)) may have a branched structure or a cyclic structure, and a specific example thereof is R in compound A (formula (A)) above. 1 Among the groups listed as specific examples of alkyl groups having 1 to 24 carbon atoms and alkenyl groups having 2 to 24 carbon atoms, we can mention alkyl groups having 1 to 10 carbon atoms and alkenyl groups having 2 to 10 carbon atoms. Furthermore, examples of heterocyclic groups include furyl groups, thienyl groups, pyridyl groups, piperidyl groups, and morpholino groups. Furthermore, r preferably represents a number between 2 and 100.

[0030] Compound C (aldehydes) includes, for example, formaldehyde, paraformaldehyde, trioxane, glyoxylic acid, acetaldehyde, trichloroacetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, hexylaldehyde, heptanal, octylaldehyde, nonylaldehyde, isononylaldehyde, decylaldehyde, dodecanal, acrolein, crotonaldehyde, pentenal, Examples include hexenal, heptenal, octenal, cinnamaldehyde, benzaldehyde, benzaldehyde sulfonic acid, benzaldehyde disulfonic acid, anisaldehyde, salicylaldehyde, benzylaldehyde [(C6H5)2C(OH)-CHO], naphthaldehyde, furfural, etc., but among these, the group consisting of formaldehyde, paraformaldehyde, benzaldehyde, or any mixture of two or more of these may be selected. Compound C can be used as a pure crystalline or powdered substance, or as a hydrate thereof, or in the form of an aqueous solution such as formalin, in which case the weighing or mixing of the components can be simplified.

[0031] Compound C, represented by the above formula (C), can be used individually or in combination of two or more types.

[0032] Monomer mixture In the monomer mixture containing the above compounds A to C used in the polycondensate in the present invention, the mixing ratio is not particularly limited, but for example, the mixture may contain compounds A and B in a molar ratio of compound A:compound B = 0.5 to 1.3:0.3 to 3.5, and compound C may be contained in a molar ratio of (compound A + compound B):compound C = 10:1 to 1:10 relative to the total molar amount of compounds A and B. More preferably, the ratio of compound A to compound B can be 0.5 to 1.3:0.5 to 1.5 (molar ratio), or more preferably, compound A to compound B can be 0.5 to 1.3:1 (molar ratio), and (compound A + compound B): compound C = 10:4 to 18 (molar ratio). In the polycondensate, by setting the proportions of compounds A to C within the above numerical range, the HLB value of the polycondensate described later can be set to a suitable range.

[0033] Polycondensates The polycondensate used in the present invention comprises a copolymer obtained by polycondensing a monomer mixture containing the above-mentioned compounds A to C, and a monomer mixture further containing, optionally, other monomer components described later, in addition to compounds A to C. The methods for producing compounds A to C and other monomer components described later, as well as the polymerization method for obtaining the copolymer, are not particularly limited. Furthermore, there are no particular limitations on the order or method of adding compounds A, B, and C, as well as other monomeric components, during polycondensation. For example, the entire amount of compounds A to C (and other monomeric components) may be added all at once before the polycondensation reaction; a portion of compounds A to C (and other monomeric components) may be added before the polycondensation reaction, and the remainder may be added dropwise; or a portion of compounds A to C (and other monomeric components) may be added before the polycondensation reaction, and the remainder may be added after a certain reaction time has elapsed.

[0034] Polycondensates can be obtained, for example, by polycondensing compound A, compound B, and compound C (and optionally other monomeric components) in the presence of a dehydrating catalyst, either in a solvent-free or solvent-based manner, at a reaction temperature of 80°C to 150°C, under atmospheric pressure to pressurized pressure, for example, 0.001 to 1 MPa. Examples of the above-mentioned dehydration catalysts include hydrochloric acid, perchloric acid, nitric acid, formic acid, methanesulfonic acid, octylsulfonic acid, dodecylsulfonic acid, vinylsulfonic acid, allylsulfonic acid, phenolsulfonic acid, acetic acid, sulfuric acid, diethyl sulfate, dimethyl sulfate, phosphoric acid, oxalic acid, boric acid, benzoic acid, phthalic acid, salicylic acid, pyruvic acid, maleic acid, malonic acid, nitrobenzoic acid, nitrosalicylic acid, p-toluenesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, trifluoromethanesulfonic acid, fluoroacetic acid, thioglycolic acid, mercaptopropionic acid, activated clay, etc. These dehydration catalysts can be used individually or in combination of two or more types. Furthermore, when carrying out the polycondensation reaction under a solvent, the solvent can be water, glycol ether compounds such as propylene glycol monomethyl ether (PGME), aromatic compounds such as toluene and xylene, or cyclic aliphatic compounds such as methylcyclohexane. In addition, it is also possible to use a solvent that is suitable as a dehydration catalyst (acid catalyst), such as acetic acid. The reaction can be carried out at temperatures of, for example, 95°C to 130°C, and the polycondensation reaction can be completed by allowing the reaction to proceed for about 3 to 25 hours. The polycondensation reaction is preferably carried out under acidic conditions, and it is desirable that the pH of the reaction system be 4 or less.

[0035] Other monomeric components In the polycondensate of the present invention, the monomer mixture may contain, in addition to compound A, compound B, and compound C, other monomer components that can polycondense with these compounds, to the extent that they do not impair the effects of the present invention. Other monomeric components include monomeric compounds D such as lignin, rosin, benzoic acid, phenol, bisphenol A, phenolsulfonic acid, and hydroxyethylphenol.

[0036] In addition, other monomeric components besides the above monomeric compound D include adducts of cresol, catechol, resorcinol, nonylphenol, methoxyphenol, naphthol, methylnaphthol, butylnaphthol, aniline, methylaniline, hydroxyaniline, methoxyaniline and / or salicylic acid with 1 to 300 mol of alkylene oxide; phenoxyacetic acid, methoxyphenol, resorcinol, cresol, nonylphenol, aniline, methylaniline, N-phenyldiethanolamine, N,N-di(carboxyethyl)aniline, N,N-di(carboxymethyl)aniline, anthranilic acid, etc. It is possible.

[0037] Furthermore, other monomeric components include, for example, alkylene oxide adducts of hydroxyethylphenol or derivatives thereof (compound E) having a structure represented by the following formula (E). [ka] In the formula, A 3 O and A 4 O independently represents an alkylene oxy group having 2 to 4 carbon atoms, t and u are the average number of added moles of alkylene oxide, each independently representing a number from 0 to 200 and t + u ≥ 1, X 2 and X 3 Each of these independently represents a hydrogen atom, a phosphate ester group, or a sulfate ester group.

[0038] Compound E is a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to hydroxyethylphenol, specifically to at least one or both of the hydroxyethyl group and / or phenolic hydroxyl group. Derivatives of this alkylene oxide adduct (phosphate esters, sulfate esters) are also included in compound E. The hydroxyethylphenol may be o-hydroxyethylphenol, m-hydroxyethylphenol, or p-hydroxyethylphenol. Compound A is preferably a compound (and its ester derivative) obtained by adding an alkylene oxide having 2 to 4 carbon atoms to o-hydroxyethylphenol.

[0039] Examples of alkylene oxides having 2 to 4 carbon atoms include ethylene oxide, propylene oxide, and butylene oxide. These alkylene oxides can be added individually or in combination. When using two or more alkylene oxides, either block addition or random addition is acceptable. That is, A above 3 O and A 4 Examples of alkylene oxy groups with 2 to 4 carbon atoms in O include ethylene oxy groups, propylene oxy groups, and butylene oxy groups. 3 O and A 4 O may consist only of an ethyleneoxy group, a propyleneoxy group, or a butyleneoxy group, or it may contain two or more of these groups. If it contains two or more groups, the addition method may be random addition or block addition. Furthermore, t and u are the average number of moles of alkylene oxide added, each independently representing a number from 0 to 200, preferably from 0 to 60, and t + u ≥ 1. 3 O, A 4 By increasing the number of added moles of oxygen, an improvement in water-reducing properties can be expected.

[0040] Also X 2 , X 3 When X represents a phosphate ester group, they are phosphate monoesters and / or salts thereof, phosphate diesters and / or salts thereof, or phosphate triesters, or mixtures thereof. 2 , X 3 When represents a sulfate ester group, they are sulfate monoesters and / or salts thereof, or sulfate diesters, or mixtures thereof. Examples of phosphate ester salts or sulfate ester salts include alkali metal salts such as sodium and potassium; group 2 metal salts such as calcium or magnesium; ammonium salts; and organic ammonium salts such as alkylammonium or alkanolammonium.

[0041] After the polycondensation reaction is complete, various conventionally known methods can be used to reduce the content of unreacted aldehyde components (compound C) in the reaction system. For example, a method of making the pH of the reaction system alkaline and heating it to 60-140°C, a method of removing the aldehyde components by volatilizing the reaction system under reduced pressure (-0.1 to -0.001 MPa), or even a small amount of sodium bisulfite. Methods include adding hydrogen peroxide, ethylene urea, and / or polyethyleneimine. The dehydration catalyst used in the reaction can be neutralized after the reaction is complete and removed by filtration as a salt; however, even if the catalyst is not removed, the performance of the catalyst as an additive for the hydraulic composition of the present invention, as described later, will not be impaired. Methods for catalyst removal other than filtration include phase separation, dialysis, ultrafiltration, and the use of ion exchangers. Furthermore, neutralizing the reaction product and diluting it with water improves the workability, such as measurement, when using it as an additive for hydraulic compositions, as described later. Examples of basic compounds used for neutralization include alkaline hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth hydroxides such as calcium hydroxide, and organic amines such as ammonia, monoethanolamine, diethanolamine, and triethanolamine. One or more of these may be used in combination.

[0042] The copolymer ultimately obtained can have a number-average molecular weight Mn (calculated by gel permeation chromatography (hereinafter referred to as "GPC method"), in terms of polyethylene glycol) in the range of 1,000 to 30,000, more preferably in the range of 1,000 to 20,000, and particularly in the range of 1,500 to 15,000. By setting the value of the number average molecular weight Mn within the above numerical range, the HLB value of the polycondensate described below can be set within a suitable range. As described above, the "polycondensate" in the present invention may consist only of a copolymer obtained by polycondensing a monomer mixture containing compounds A to C (and optionally other monomer components), but generally includes components including unreacted components and by-products generated in each polymerization step, alkylene oxide addition step, etc.

[0043] The copolymer contained in the polycondensate of the present invention can have, for example, a structural unit A represented by the following formula (1) and a structural unit B represented by formula (2). [Chemical formula] In the above formula (1), R 1 , A 1 , m and R 2 are synonymous with the groups listed in the above formula (A) (when n = 1), and in formula (2), R 3 , A 2 , p and X 1 are synonymous with the groups listed in the above formula (B) (when q = 1).

[0044] [HLB value] The HLB (Hydrophile Lipophile Balance) value is a numerical value representing the balance between the hydrophobicity and hydrophilicity of a surfactant (the degree of affinity for water or oil). In the present invention, in the polycondensate contained in the pigment dispersant, the ratio of hydrophobic groups / hydrophilic groups in these monomers (the presence / type of substituents on the phenyl group, the number of added moles of alkyleneoxy groups, etc.) is considered to affect the suitable HLB value described below. Furthermore, the type and ratio of substituents in the monomer (steric hindrance due to the bulkiness of the substituents), the ratio of adsorbing groups and neutral salt structures in these monomers (selection of phosphate ester salts or sulfate ester salts), etc. are also considered to affect the HLB value.

[0045] In this invention, the HLB value refers to the value calculated based on the Griffin method [HLB = 20 × {sum of formula weights of hydrophilic parts / molecular weight}]. Specifically, NMR measurements are performed on the polycondensate, and the HLB of the polycondensate is calculated from the number of protons in the hydrophobic and hydrophilic regions of the obtained spectrum. [HLB calculation formula] HLB value = {Number of protons in the hydrophilic region / (Number of protons in the hydrophilic region + Number of protons in the hydrophobic region)} × 20 Sum of the integral values ​​for hydrophobic regions with proton numbers of 0.5-1.6 ppm and 6.1-7.5 ppm. Hydrophilic proton number: Integral value for 2.8~4.3 ppm

[0046] The present invention relates to a pigment dispersant containing the polycondensate having a novolac structure and an HLB value of 10 to 19.5. By using polycondensates with an HLB value of 10 to 19.5 as a component of the pigment dispersant, good color separation prevention and color toning stability can be obtained when incorporated into a mixed system (mixed dispersion) of hydrophilic and hydrophobic pigments. In particular, using polycondensates with an HLB value of 15.5 to 19.5 can provide even better color separation prevention and color toning stability. Furthermore, by using a polycondensate with an HLB value of 10-16 as a component of the pigment dispersant and incorporating it into a dispersion containing a hydrophilic pigment, a foam suppression effect during manufacturing can be obtained.

[0047] The amount of pigment dispersant added in the present invention varies depending on the type and combination of pigments used, but it is usually added in an amount of approximately 0.01 to 5.0% by mass on a solid content basis relative to the total mass of pigments.

[0048] <Pigment dispersion, paint composition> The present invention relates to a pigment dispersion containing the pigment dispersant, pigment, and water, and to a paint composition containing the pigment dispersant, pigment, resin, and water. Examples of the above-mentioned pigments include the hydrophilic and hydrophobic pigments mentioned earlier. Other classifications include inorganic coloring pigments, organic coloring pigments, extender pigments, metallic pigments, and corrosion-resistant pigments.

[0049] The above-mentioned resin is not particularly limited as long as it is a resin with film-forming properties that is commonly used in paint compositions. For example, thermosetting resins such as acrylic resins, epoxy resins, polyester resins, and polyurethane resins; and thermoplastic resins such as acrylic resins, polyester resins, polyolefin resins, and polyamide resins may be appropriately selected depending on the object to be coated and the purpose.

[0050] Furthermore, the above-mentioned paint composition can be appropriately blended with known and publicly available additives for paint compositions depending on various applications and performance requirements. Specifically, these may include surfactants (nonionic surfactants, anionic surfactants, cationic surfactants, etc.), thickeners (cellulose-based water-soluble polymers such as methylcellulose, ethylcellulose, hydroxyethyl sesrose, carboxymethylcellulose, etc., polyacrylamide-based water-soluble polymers, biopolymer-based thickeners such as deutan gum, welan gum, xan gum, etc., nonionic thickeners such as polyethylene glycol, polyalkylene oxide, etc.), and defoamers (nonionic defoamers, silicone-based defoamers, higher alcohols). Examples include wetting agents, dispersants, and color separation inhibitors.

[0051] The above-mentioned pigment dispersion can be prepared by mixing, for example, a pigment dispersant, the desired pigment, and water as a solvent using a disperser such as a bead mill, ball mill, or disperser. When using both hydrophilic and hydrophobic pigments, a dispersion containing the hydrophilic pigment and a dispersion containing the hydrophobic pigment can be prepared separately and then mixed. Furthermore, the above-mentioned paint composition can be manufactured by conventionally known methods. For example, a general method for manufacturing paint can be broadly divided into two steps: 1) a dispersion step (mill-base step) in which pigments are dispersed in a solvent (water in the case of water-based paints) to prepare a pigment dispersion, and 2) a blending step (let-down step) in which resins and other additives (such as curing agents) are added to the pigment dispersion. In this way, primary colors are produced for each pigment, and if necessary, a color matching step is taken to adjust them to the desired hue. [Examples]

[0052] The present invention will be described below with reference to examples. However, the present invention is not limited in any way by these examples and comparative examples.

[0053] The physical properties of the samples were measured under the following conditions using the following equipment. (1) GPC (Gel Permeation Chromatography) <Gel Permeation Chromatography (GPC) Measurement Conditions> Columns: OHpak SB-802.5HQ, OHpak SB-803HQ, OHpak SB-804HQ (manufactured by Showa Denko Corporation) Eluent: Mixture of 50 mM sodium nitrate aqueous solution and acetonitrile (volume ratio 80 / 20) Detector: Differential refractometer Calibration curve: Polyethylene glycol (2) NMR (Nuclear Magnetic Resonance Spectroscopy) <Measurement of the number of moles of phosphate groups introduced> JEOL Ltd. JNM-ECZ400S (400MHz). Nuclide: 31P, Solvent: Heavy water, Sample concentration: 15 wt%, Number of cumulative counts: 512. From the spectra obtained by NMR measurement, the molar ratio of phosphate groups in the phosphate group and the polycondensate is calculated by comparing the integrated values. <Calculation of HLB value of polycondensates> JEOL Ltd. JNM-ECZ400S (400MHz). Nuclide: 1H, Solvent: Heavy water (D2O), Sample concentration: 10%, Number of cumulative counts: 64. The HLB of the polycondensate is calculated from the number of protons in the hydrophobic and hydrophilic regions of the spectrum obtained from the NMR measurement using the following formula. [HLB calculation formula] HLB value = {Number of protons in the hydrophilic region / (Number of protons in the hydrophilic region + Number of protons in the hydrophobic region)} × 20 Sum of the integral values ​​for hydrophobic regions with proton numbers of 0.5-1.6 ppm and 6.1-7.5 ppm. Hydrophilic proton number: Integral value for 2.8~4.3 ppm <Measurement of RSP value of carbon black dispersion> TD-NMR Spectrometer Spin Track, manufactured by Resonance Systems (Germany). Measurement conditions: CPMG pulse sequencing method. Immediately after preparing the measurement sample (carbon black, pigment dispersant, and water-containing dispersion) or blank solution (pigment dispersant, and water-containing dispersion), the relaxation time T2 of each is measured by pulsed NMR, and the RSP value of the sample is calculated using the following formula. The RSP value is an indicator of wettability, and a higher value indicates easier wettability. [RSP value calculation formula] RSP value = {T2 (blank) / T2 (sample)} - 1

[0054] ≪Method for producing polycondensates≫ [Manufacturing Example 1: Preparation of Compound (A)] In a stainless steel high-pressure reactor equipped with a thermometer, stirrer, pressure gauge, and nitrogen inlet tube, 80 parts of diethylene glycol monophenyl ether (HighSolve DPH, manufactured by Toho Chemical Industry Co., Ltd.) and 0.2 parts of 96% potassium hydroxide were charged. The reaction vessel was purged with nitrogen, and the mixture was heated to 150°C under a nitrogen atmosphere. Then, while maintaining the temperature at 150°C under safe pressure, 360 parts of ethylene oxide were introduced into the reactor over 10 hours, and the temperature was maintained for another 2 hours to complete the alkylene oxide addition reaction, yielding polyethylene glycol monophenyl ether (number of moles of EO added = 17). Following this procedure, various polyalkylene glycol monophenyl ether derivatives shown in Table 1 were prepared by changing the starting material to bisphenol A or p-tert-butylphenol, varying the number of moles of ethylene oxide added, or by adding propylene oxide in addition to ethylene oxide.

[0055] [Production Example 2: Preparation of Compound (B) (Phosphate Ester Derivative)] Three moles of phenol EO adduct were charged into a glass reaction vessel equipped with a stirrer, thermometer, and nitrogen inlet tube. One mole of anhydrous phosphoric acid was added over four hours at 50°C while nitrogen bubbling was performed, and the reaction was carried out. Subsequently, the reaction was aged at 100°C for three hours to complete the phosphate esterification reaction, yielding phenol EO adduct phosphate ester. Furthermore, in the same manner as with the EO adduct phosphate esters of phenols, various phosphate esters shown in Table 1 were obtained: EO adduct phosphate ester of p-tert-butylphenol, PO adduct phosphate ester of p-tert-butylphenol, EO adduct phosphate ester of bisphenol A, PO adduct phosphate ester of bisphenol A, and EO adduct phosphate ester of hydroxybiphenyl.

[0056] [Manufacturing Example 3: Preparation of Polycondensates (No. 1 to No. 8, ratio 1 to ratio 2)] Compounds A and B were charged into a glass reaction vessel equipped with a stirrer, thermometer, and reflux condenser in the molar ratios shown in Table 1. The mixture was heated to 70°C, and then 0.5 wt% of 98% sulfuric acid was added relative to the total mass of compounds A and B. Next, compound C (aldehydes) was added to the reaction vessel in the molar ratios shown in Table 1, and the mixture was then heated to 105°C. At 105°C, the pH of the reactants was 2.3 (1% aqueous solution, 20°C). After reaching 105°C, the reaction was allowed to proceed for 2 to 24 hours. After the reaction was completed, 48% caustic soda was added to the reaction vessel to neutralize the mixture so that the pH of the 1% aqueous solution of the reactants was in the range of 4.5 to 8.0. Subsequently, an appropriate amount of water was added so that the solid content of the reactants was 35%, and aqueous solutions of polycondensates No. 1 to No. 8, with ratios of 1 to 2, were obtained. The number-average molecular weight (Mn) of these polycondensates was determined by GPC measurement, and NMR measurements were performed on these polycondensates to determine the HLB values ​​using the procedure described above. The results obtained are shown in Table 1.

[0057] [Table 1]

[0058] [Performance evaluation of pigment dispersants] Titanium dioxide was selected as the hydrophilic pigment and carbon black as the hydrophobic pigment. The performance of pigment dispersants (No. 1 to No. 8, polycondensates with ratios of 1 to 2) in titanium dioxide dispersions, carbon black dispersions, and titanium dioxide / carbon black mixed systems was evaluated using the following procedure. In the following explanation, the example numbers of the polycondensates will also be treated as the example numbers of the dispersions used in the performance evaluation. The product names of the pigments used in the following performance evaluations are as follows: Titanium dioxide: Ti-Pure R-902 (manufactured by Chemours) Carbon Black: Acetylene Black (50% compressed) Fujifilm Wako Pure Chemical Corporation

[0059] (1) Titanium dioxide dispersion system (hydrophilic pigment dispersion system) (1) [Table 2] Using a homodisperser (Primix Co., Ltd., LB Homodisperser Type 1.5), titanium dioxide dispersion (1) was prepared at 2,000 rpm for 15 minutes, according to the formulation example in Table 2 above. The viscosity (mPa·s) of the prepared titanium dioxide dispersion (1) was measured immediately after preparation and over time (1 hour, 1 day, 3 days, and 7 days after dispersion preparation) using a ViscoMETER TVB-10M (Toki Sangyo Co., Ltd., rotor No. 2), at 30 rpm and a storage temperature of 20°C. The results obtained are shown in Table 5.

[0060] (2) Titanium dioxide dispersion system (hydrophilic pigment dispersion system) (2) A portion of the prepared titanium dioxide dispersion (1) was taken, and water was added to prepare a titanium dioxide dispersion (2) with a titanium dioxide concentration of 3% by mass. The relaxation time of the dispersion was measured using pulsed NMR (CPMG pulsed sequencing method).

[0061] Furthermore, 50 mL of titanium dioxide dispersion (2) was placed in a stoppered graduated cylinder, and the cylinder was shaken 30 times up and down with a shaking amplitude of 30 cm. The foaming of the dispersion was visually observed. The height of the foam was determined relative to the volume of liquid before shaking (50 mL), and the foaming was judged according to the following criteria. <Foaming Criteria> ◎: Foam height is less than 5ml after 60 seconds 〇: Foam height after 60 seconds is 5-50ml -:Not measured The results obtained are shown in Table 5.

[0062] (3) Carbon black dispersion system (hydrophobic pigment dispersion system) [Table 3] According to the formulation example in Table 3, each component was placed in a glass container and set up in a vibrating agitator (bead filling rate 75 vol%; agitator: manufactured by Seiwa Giken Co., Ltd., rocking shaker model: RS05W; zirconia balls: ASONE, CZY0200 φ1.90~2.10 mm), 1 A carbon black dispersion was prepared by processing for 5 minutes. A blank solution was prepared using only water and the dispersant shown in Table 3, following the same procedure. The relaxation time T2 of the carbon black dispersion and blank solution (both immediately after preparation) was measured by pulsed NMR, and the RSP value was determined from the obtained values ​​using the procedure described above. Furthermore, the viscosity (mPa·s) of the carbon black dispersion was measured over time (1 hour, 1 day, and 3 days after dispersion preparation) using a ViscoMETER TVB-10M (Toki Sangyo Co., Ltd., rotor No. 2), at 30 rpm, and at a storage temperature of 20°C. The viscosity increase rate was also calculated from the viscosity after 1 day and 3 days. The results obtained are shown in Table 5.

[0063] (4) Titanium dioxide / carbon black mixture (hydrophilic pigment / hydrophobic pigment mixed dispersion) [Table 4] Using a homodisperser (Primix Co., Ltd., LB Homodisperser Type 1.5), titanium dioxide dispersion a was prepared at 2,000 rpm for 15 minutes, according to the formulation example in Table 4 above. Next, following the formulation example in Table 4, each component was placed in a glass container and placed in a vibrating agitator (bead filling rate 75 vol%; agitator: manufactured by Seiwa Giken Co., Ltd., rocking shaker model: RS05W; zirconia balls: ASONE, CZY0200 φ1.90~2.10 mm) and processed for 15 minutes to prepare carbon black dispersion b. Dispersion a and dispersion b were collected in vials in a ratio of dispersion a / dispersion b = 50 vol% / 50 vol% and mixed with a hand vibrator for 60 seconds to obtain a mixed dispersion. One day after the preparation of the mixed dispersion, the state of the mixture was visually observed. If the mixture separated into upper and lower colored sections, the ratio of the length of the colored section (length from the top of the mixture to the colored section) to the total height of the mixture was calculated, and the color separation properties were evaluated according to the following criteria. <Criteria for determining color separation> ◎: The length of the color separation is within 5% of the total height of the mixture. ○: The length of the color separation is within 20% of the total height of the mixed liquid. ×: The length of the color separation is 20% or more of the total height of the mixture.

[0064] Furthermore, the color-matching stability of the mixed dispersion was evaluated using the rubbing test described below. Immediately after preparing the mixed dispersion, the dispersion was applied to opacity test paper (50 μm thick), and the semi-dry coating was rubbed with a fingertip. The color difference between the rubbed area and other areas was visually observed, and the color stability was evaluated according to the following criteria. <Toning stability judgment criteria> ◎: No difference in color is observed between the rubbed area and the unrubbed area. ○: There is a slight difference in color between the rubbed and unrubbed areas. ×: There is a noticeable difference in color between the rubbed area and the unrubbed area. The results obtained are shown in Table 5.

[0065] [Table 5]

[0066] As shown in Table 5, in the titanium dioxide dispersion system (hydrophilic pigment dispersion system) (1), dispersions No. 1 to No. 8 had lower viscosity immediately after preparation and in the initial period (after 1 hour) compared to dispersions with a ratio of 1 to 2, and showed less change in viscosity over time. This trend was particularly pronounced in dispersions No. 6 to No. 8. This was particularly noticeable in the dispersion. On the other hand, the viscosity of dispersions with ratios of 1 to 2 increased significantly after one day, and viscosity measurement became difficult from the third day onward. Furthermore, in the titanium dioxide dispersion system (hydrophilic pigment dispersion system) (2), the relaxation time of the dispersions obtained by pulsed NMR measurement increased for dispersions No. 1 to No. 8 compared to the dispersions with ratios of 1 to 2. Additionally, foaming was suppressed. Furthermore, in the titanium dioxide dispersion systems (hydrophilic pigment dispersion systems) (1) and (2), dispersions No. 1 to No. 8 did not show any aggregation or precipitation of the hydrophilic pigment titanium dioxide, as observed visually from immediately after preparation to the time of evaluation.

[0067] The pulsed NMR used to evaluate the dispersion in this example measures the relaxation time, which is the time required to move from the excited state to the ground state, allowing for non-destructive evaluation of molecular mobility. As demonstrated in this example, it can also be used to evaluate the dispersibility of fine particle dispersions. In pulsed NMR measurements, the mobility of water is measured as the relaxation time T2. In a particle dispersion system, water can be broadly classified into two types: water that is adsorbed on the particle surface and whose movement is constrained, and water that is not adsorbed and moves freely within the system. The response to changes in the magnetic field differs between this constrained water and the free water. Constrained water undergoes energy conversion more easily, resulting in a shorter relaxation time, while the relaxation time of free water is longer. Therefore, generally, the more water that is adsorbed on the particles and whose mobility is reduced, the lower (shorter) the measured relaxation time T2 will be, suggesting that the particles are more dispersed in the dispersion, provided that chemical differences at the particle interface do not need to be considered. However, in the dispersions containing titanium dioxide, which is the hydrophilic pigment targeted by the present invention, dispersions No. 1 to No. 8 have lower viscosity and higher dispersibility compared to dispersions with a ratio of 1 to 2, yet their relaxation time is longer. This is thought to be because the hydrophilicity-adjusted dispersant of the present invention makes the surface of the titanium dioxide hydrophobic, thereby suppressing particle aggregation via water and leading to a lower viscosity dispersion.

[0068] In the carbon black dispersion system (hydrophobic pigment dispersion system), dispersions No. 1 to No. 8 showed lower initial viscosity (after 1 hour) and less viscosity change over time compared to dispersions with ratios of 1 to 2. This trend was particularly pronounced in dispersions No. 1 to No. 3. On the other hand, the viscosity of dispersions with ratios of 1 to 2 increased significantly after 1 day, making viscosity measurement difficult. Furthermore, dispersions No. 1 and No. 3-5 had higher RSP values ​​compared to the other dispersions. The RSP value is an indicator of wettability, and a high RSP value indicates that these dispersions have superior dispersibility. Furthermore, in the carbon black dispersion systems (hydrophobic pigment dispersion systems) No. 1 to No. 8, no aggregation or precipitation of the hydrophobic pigment carbon black was observed visually from immediately after preparation to the time of evaluation.

[0069] In the titanium dioxide / carbon black mixed system (hydrophilic / hydrophobic pigment mixed dispersion system), dispersions No. 1 to No. 8 received a rating of ○ or higher for both color separation and color matching stability. In particular, dispersions No. 1 to No. 3 showed good results, with short color separation lengths (less color separation) in the color separation evaluation and no difference in color between rubbed and unrubbed areas in the color matching stability evaluation. On the other hand, dispersions with a ratio of 1 to 2 showed longer color separation areas (more color separation) in the color separation evaluation, and a significant color difference between rubbed and unrubbed areas in the color matching stability evaluation. Furthermore, in the titanium dioxide / carbon black mixed system (hydrophilic / hydrophobic pigment mixed dispersion system) dispersions No. 1 to No. 8, no aggregation or precipitation of the hydrophilic pigment titanium dioxide or the hydrophobic pigment carbon black was observed visually from immediately after preparation to the time of evaluation.

[0070] As described above, the pigment dispersant of the present invention can be used with respect to both hydrophilic and hydrophobic pigments. Examples have confirmed that by incorporating this compound, a dispersion can be formed in which aggregation and precipitation are suppressed, resulting in good dispersion performance. Furthermore, when added to a mixture of hydrophilic and hydrophobic pigments, these pigments do not aggregate, and color separation (separation into upper and lower layers) and color floating (partial concentration distribution) are suppressed, resulting in a dispersion with excellent color toning stability.

Claims

1. It contains a polycondensate of monomer mixtures comprising compound A represented by the following formula (A), compound B represented by formula (B), and one or more aldehyde compounds C represented by formula (C), A pigment dispersant wherein the polycondensate has a novolac structure and an HLB value of 10.0 to 19.5, 【Chemistry 1】 (In the formula, n represents 1 or 2, When n represents 1, R １ This represents a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms. A １ O represents an alkylene oxy group with 2 to 4 carbon atoms. m represents the average number of moles of alkylene oxide added, and is a number between 1 and 200. R ２ This represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an acyl group having 2 to 24 carbon atoms. When n represents 2, R １ is, -CH ２ -, -C(CH ３ ) ２ -, or -SO ２ - represents, A １ O represents an alkyleneoxy group having 2 to 4 carbon atoms, m represents the average number of moles of alkylene oxide added, and is a number between 1 and 200. R ２ (This represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an acyl group having 2 to 24 carbon atoms.) 【Chemistry 2】 (In the formula, q represents 1 or 2, If q represents 1, R ３ represents a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms. A ２ O represents an alkylene oxy group with 2 to 4 carbon atoms. p represents the average number of moles of alkylene oxide added, and is a number between 1 and 200. X １ This represents a phosphate ester group or a sulfate ester group. If q represents 2, R ３ is, -CH ２ -, -C(CH ３ ) ２ -, or -SO ２ - represents, A ２ O represents an alkylene oxy group with 2 to 4 carbon atoms. p represents the average number of moles of alkylene oxide added, and is a number between 1 and 200. X １ (This represents a phosphate ester group or a sulfate ester group.) 【Transformation 3】 (In the formula, R ４ This represents a hydrogen atom, a carboxyl group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a phenyl group, a naphthyl group, or a heterocyclic group. (r represents a number between 1 and 100.) In formula (A), n is 1, and in formula (B), p is less than 4, or In the above formula (A), n is 2, Pigment dispersant.

2. In the compound represented by the above formula (A), (A １ O) The proportion of ethyleneoxy groups in the group is 20 mol% to 100 mol%, The pigment dispersant according to claim 1.

3. The monomer mixture is The above compound A and compound B are contained in a molar ratio of compound A:compound B = 0.5 to 1.3:1, and The total molar amount of compound A and compound B is relative to compound C, which is contained in a molar ratio of (compound A + compound B):compound C = 10:4 to 18. A pigment dispersant according to claim 1 or claim 2.

4. A pigment dispersion comprising a pigment dispersant, a pigment, and water according to any one of claims 1 to 3.

5. A paint composition comprising a pigment dispersant, a pigment, a resin, and water according to any one of claims 1 to 3.

6. A method for dispersing a pigment, comprising the step of mixing a pigment dispersant and a pigment according to any one of claims 1 to 3 in a disperser.

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