KR20100114423A - Copolymer, methods for producing the same, and aqueous pigment compositions comprising the same - Google Patents

Abstract

The present invention provides a copolymer, a preparation method thereof, and an aqueous pigment dispersion comprising the same.

Description

Copolymer, Methods for Making the Same, and Aqueous Pigment Dispersions Containing the Same

The present invention provides a copolymer, a preparation method thereof, and an aqueous pigment dispersion comprising the same.

Pigment dispersions are compositions in which pigments and dispersants are dispersed in an aqueous medium or a non-aqueous medium. Pigment dispersions are used in the manufacture of products such as coating materials, inks, paints, toners and the like.

Generally, pigments are hydrophobic particles and have a low degree of wetness in water. Thus, dispersion of pigments in non-aqueous media is not a problem, but it is difficult to stably disperse pigments at high concentrations in aqueous media. To address this difficulty, the pigments can be treated by chemical or physical methods to enhance the dispersibility in the aqueous medium by binding hydrophilic functional groups to the surface of the pigments. In this way, the hydrophilic functional groups can allow a dispersant to be immobilized on the pigment surface, which can improve the dispersion stability and rheology of the pigment.

As a method for introducing hydrophilic functional groups to the pigment surface, there is a method of oxidizing the pigment. Oxidation treatment may be liquid phase oxidation or gas phase oxidation. Liquid phase oxidation is a method of oxidizing a pigment with an aqueous solution of an oxidizing agent such as hydrogen peroxide, nitric acid, sulfuric acid, chlorate, persulfate, percarbonate, and diazonium. In liquid phase oxidation, the degree of oxidation of the pigment can be controlled by adjusting the type, concentration, oxidation temperature and time of the oxidant used, and the ratio of the oxidant and the pigment.

For example, Japanese Laid-Open Patent Publication No. 1996-3498 discloses a method of oxidizing pigment carbon black with an aqueous solution of hypohalogenate. Japanese Patent Application Laid-Open No. 1996-319444 discloses a process of finely dispersing carbon black having an oil absorption of 100 ml / 100 mg or less in an aqueous medium; And a process of oxidizing carbon black using a hypohalogenate. In addition, Japanese Patent Laid-Open No. 2001-323052 discloses a method of introducing a sulfonic acid group into pigment particles and treating with a monovalent metal. U.S. Pat.No. 5,477,397 also discloses a method of treating carbon black with a diazonium salt.

In addition to the method of oxidizing the surface of the pigment, a dispersant having both a functional group having excellent affinity with the pigment and a functional group having excellent affinity with the aqueous medium is known. Such dispersants have sulfonic acid groups, carboxylic acid groups or amino groups and can act as effective dispersants.

However, pigment formulations made with these dispersants do not meet all the requirements required for pigment formulations in terms of their performance properties. They are not selectively adsorbed for certain pigment species, but desorb at the pigment surface. Such desorption at the pigment particle surface of the dispersant may cause the pigment particles to aggregate or agglomerate together or have a poor color, ultimately degrading the quality of the final application, such as coatings, inks, paints and the like.

It is an object of the present invention to provide a copolymer which can be used as a dispersant for a wide variety of pigments, including inorganic pigments and organic pigments, which are not selectively adsorbed only to specific pigment species, and to provide aqueous pigment dispersions comprising the same. .

In order to solve the above problems, the present invention provides a copolymer in which the structural unit represented by the formula (A) and the structural unit represented by the formula (B) are copolymerized, and provide an aqueous pigment dispersion containing the copolymer. do.

Hereinafter, the present invention will be described in detail.

The present invention provides a copolymer in which the structural units represented by the formula (A) and the structural units represented by the formula (B) are linearly arranged.

Formula (A)

Formula (B)

In the above, Ar is a substituted or unsubstituted C ₆ -C ₂₅ aryl group;

R ₁ and R ₂ are each independently hydrogen or a C ₁ -C ₆ alkyl group;

R ₃ is —SO ₂ NHCOR ₈ , —CONH ₂ , wherein —COOH, —SO ₃ H, —PO ₃ H ₂ , R ₈ is a saturated or unsaturated C ₁ -C ₆ alkyl group or phenyl Or salts thereof;

R ₄ , R ₅ , R ₆ and R ₇ are each independently hydrogen, halogen or a substituted or unsubstituted C ₁ -C ₆ alkyl group;

Wherein X represents a simple bond or a C ₁ -C ₆ alkylene oxide or a C ₁ -C ₆ alkylene group; And

The number of structural units of formula (A) and of structural units of formula (B) may be 2-20 and 10-1000, respectively.

In the above, Ar may be, for example, naphthyl, anthracenyl, benzo [a] pyrenyl or coronenyl. In the above, Ar is for example naphthyl.

In the above, R ₁ and R ₂ are for example independently of each other hydrogen or methyl.

In the above, R ₃ is for example -COOH, -SO ₃ H, -CONH ₂ or salts thereof. Preferred salts are sodium salts, potassium salts, or alkyl ammonium salts. ^{E.g., -COONa, -COOK, -COO - N} (R 9) 4 +, -SO 3 Na, -HPO 3 Na, -SO 3 - N (R 9) 4 +, and PO ₃ Na _2, wherein R ₉ is a saturated or unsaturated C ₁ -C ₆ alkyl group or phenyl.

In the above R ₄ , R ₅ , R ₆ and R ₇ are for example hydrogen.

In the above, X represents a simple bond, for example.

In the above, the ratio of the number of structural units of formula (B) to the number of structural units of formula (A) may be, for example, 10 to 50.

The functional groups used in the definition of the copolymer according to the invention can be defined as follows.

"Aryl" means a monocyclic, bicyclic, tricyclic, pentacyclic or heptacyclic aromatic hydrocarbon moiety having from 6 to 25, preferably from 6 to 24 ring atoms, wherein at least one halogen substituent May be optionally substituted by.

"Alkyl" means a straight or branched chain saturated monovalent hydrocarbon moiety of 1 to 6 carbon atoms. Alkyl groups may be optionally substituted by one or more halogen substituents. Examples of alkyl groups include methyl, ethyl, propyl, 2-propyl, n-butyl, iso-butyl, tert-butyl, pentyl, hexyl, fluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl, dichloromethyl, Trichloromethyl, iodomethyl, bromomethyl and the like.

"Alkylene" means that the alkyl group has a divalent structure.

"Halogen" means fluorine, chlorine, bromine or iodine. For example, halogen means fluorine, chlorine or bromine.

The copolymer of the present invention may have a number average molecular weight (Mn) in the range of 1,000 to 50,000 g / mol. When the number average molecular weight is less than 1,000, the adhesion to the pigment particles is insufficient to disperse the pigment. When the number average molecular weight exceeds 50,000, agglomeration may occur between the pigment particles to disperse the pigment. In addition, it is difficult to increase the pigment concentration in the aqueous pigment dispersion. In particular, when used in ink pigments, the copolymer itself has a high molecular weight, which is not preferable because the flying of the droplets becomes unstable. For example, the number average molecular weight of the copolymer may be in the range of 5,000 to 20,000 g / mol.

The copolymer of the present invention can be used as a dispersant in an aqueous dispersion comprising a pigment or a dye, and the aqueous dispersion comprising the copolymer of the present invention can be used as a component of an ink or paint (paint or coating composition). .

The copolymers of the present invention comprise certain aryl groups of relatively simple structure that interact with pigments and specific functional groups that interact with aqueous media. Therefore, the copolymer of the present invention can be used as a dispersant for both inorganic pigments and organic pigments having completely different configurations. In addition, the copolymer of the present invention can lower the viscosity of the pigment, and can improve pigment dispersibility by suppressing reagglomeration even after pigment dispersion. In particular, the copolymers of the present invention can be used for organic pigments, in particular carbon black, quinacridone, phthalocyanine and inorganic pigment bismuth vanadate pigments.

The copolymer of the present invention may be a random copolymer in which the structural units represented by the formula (A) and the structural units represented by the formula (B) are irregularly arranged. In addition, the copolymer of the present invention may be a block copolymer of the structural unit represented by the formula (A) and the structural unit represented by the formula (B). For example, the copolymer of the present invention may be a random copolymer.

The copolymers of the present invention are characterized in that each structural unit is copolymerized with a method of copolymerization such as atom transfer radical polymerization, reversible addition-fragmentation chain transfer (RAFT) or nitroxide mediated polymerization. It can be prepared by (nitroxide mediated polymerization, NMP).

In one embodiment, the copolymer of the present invention is selected from the group consisting of structural units of formula (A) such as 2-naphthyl acrylate and structural units of formula (B) such as methacrylic acid, acrylic acid or acrylamide It can be prepared by copolymerizing monomers. The number of structural units represented by formula (A) and the structural units represented by formula (B) may be 2-20 and 10-1000, respectively, but is not limited thereto. Although copolymerization temperature can be 40-95 degreeC, it is not limited to these.

When preparing the copolymer of the present invention, the initiator that can be used may be a water-soluble initiator or a fat-soluble initiator commonly used in copolymerization. The initiator may be used in 0.1-5 parts by weight based on 100 parts by weight of the copolymer structural unit (A) or (B), but is not limited thereto. The water-soluble initiator may be, but is not limited to, azo initiators including potassium persulfate, sodium persulfate, ammonium persulfate, or 4,4'-azo-bis (4-cyanovaleric acid). The fat soluble initiator may be, but is not limited to, benzoyl peroxide, azobisisobutyronitrile, azobismethylbutyronitrile, azobiscyclohexanecarbonitrile.

When manufacturing the copolymer of this invention, a copolymerization solvent can be used. As a solvent, the solvent which does not reduce the surface tension of the water-based pigment dispersion of this invention is preferable. A water-soluble solvent can be used as a solvent, For example, it may be diethylene glycol monomethyl ether or diethylene glycol monoethyl ether. Although a water-insoluble solvent can be used, it is preferable to further remove the water-insoluble solvent after synthesizing the copolymer.

When preparing the copolymer of the present invention by copolymerization, a chain transfer agent may further be used for the production of a copolymer having a desired appropriate molecular weight. Examples of chain transfer agents include alkyl mercaptans including lauryl mercaptan; Thiocarboxylic acids, including mercapto acetic acid, 2-mercapto propionic acid, or 3-mercapto propionic acid; Or thio carboxylic acid esters including butyl thioglycolate or 2-ethylhexyl thioglycolate.

The present invention relates to an aqueous pigment dispersion comprising at least one pigment, an aqueous medium, and a dispersant, wherein the dispersant is a copolymer in which the structural unit represented by the formula (A) and the structural unit represented by the formula (B) are linearly arranged. It is characterized by a chain.

Formula (A)

Formula (B)

In the above, Ar is a substituted or unsubstituted C ₆ -C ₂₅ aryl group;

R ₁ and R ₂ are each independently hydrogen or a C ₁ -C ₆ alkyl group;

R ₃ is —SO ₂ NHCOR ₈ , —CONH ₂ , wherein —COOH, —SO ₃ H, —PO ₃ H ₂ , R ₈ is a saturated or unsaturated C ₁ -C ₆ alkyl group or phenyl Or salts thereof;

R ₄ , R ₅ , R ₆ and R ₇ are each independently hydrogen, halogen or a substituted or unsubstituted C ₁ -C ₆ alkyl group;

Wherein X represents a simple bond or a C ₁ -C ₆ alkylene oxide or a C ₁ -C ₆ alkylene group; And

The number of structural units of formula (A) and the number of structural units of formula (B) can be 2-20 and 10-1000, respectively, and the ratio of the number of structural units of formula (B) to the number of structural units of formula (A) is 10 to 50 may be.

In the above, Ar may be, for example, naphthyl, anthracenyl, benzo [a] pyrenyl or coronyl. Ar is for example naphthyl.

In the above, R ₁ and R ₂ are for example independently of each other hydrogen or methyl.

In the above, R ₃ is for example -COOH, -SO ₃ H, -CONH ₂ or salts thereof. Preferred salts are sodium salts, potassium salts, or alkyl ammonium salts. ^{E.g., -COONa, -COOK, -COO - N} (R 9) 4 +, -SO 3 Na, -HPO 3 Na, -SO 3 - N (R 9) 4 +, and PO ₃ Na _2, wherein R ₉ is a saturated or unsaturated C ₁ -C ₆ alkyl group or phenyl.

In the above, R ₄ , R ₅ , R ₆ and R ₇ are for example hydrogen.

X is for example a simple bond.

In the aqueous pigment dispersion of the present invention, both pigments may be used as the pigments, organic pigments or inorganic pigments, and the pigments may be in the form of powder, granules or aqueous press cakes.

Organic pigments include monoazo pigments, disazo pigments, azo lake pigments, phthalocyanine, triphenylmethane, thioindigo, thiazineindigo, quinacridone, dioxazine, isoindolinone, isoindolin, quinaphthalone, quinoph It may be one or more selected from the group consisting of talon, perylene, anantrone, perinone, diketopyrrolopyrrole, benzimidazoloneazo, naphthol and carbon black, but is not limited thereto. Carbon blacks may include acidic or alkaline carbon blacks, including furnace blacks or gas blacks. The inorganic pigment may be one or more selected from the group consisting of titanium dioxide, zinc sulfide, iron oxide, chromium oxide, nickel or chromium antimony titanium dioxide, cobalt oxide and bismuth vanadate, but are not limited thereto.

The pigment may be, for example, a carbon black, quinacridone, phthalocyanine or bismuth vanadate pigment.

The pigment may be commercially available or may be prepared by a known method. Examples include Monarch 280, Monarch 120, Regal 350R, Regal 99R from Cabot Corporation; Special black 550, Special black 4, Special black 6, FW1, FW2, FW2V, FW18, XBF 285, S-160, S-170, Printex 90, Printex 95, Printex 80, Printex 75 (Degussa); And Raven 7000, Raven 5000UltraII, Raven 2600Ultra, Raven 3000, Raven 1255, Raven CD-5008, Raven C-975Ultra, Raven 1040, Raven 1500 (Columbia Chemical), and the like. In addition, pigments such as BASF, Clariant, CIBA, Aztech, Sun Chemical, DIC, Swiss, etc. may be used, for example CIPigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 16, 22, 56, 60, 64, CIPigment Red 9, 17, 97, 122, 123, 149, 166, 168, 177, 180, 192, 202, 209, 215, 137, 138, 150 , 153, 154, 155, 166, 168, 180.

In the present invention, the 'aqueous medium' may be water alone or a mixture of water and an aqueous organic solvent. Aqueous organic solvents include alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol or alkyl ethers thereof, glycerin, N-methylpyrrolidone, 1,3 -Dimethylimidazolinone, thiodiglycol, 2-pyrrolidone, dimethyl sulfoxide, sulfolane, diethanolamine, triethanolamine, ethanol or isopropyl alcohol, but are not limited to these.

The aqueous pigment dispersion of the present invention is based on the total weight of the aqueous pigment dispersion (a) 5 to 80% by weight, for example 10 to 50% by weight, (b) copolymers 2 to 25 of the invention. Weight percent, such as 3 to 15 weight percent, (c) 5 to 80 weight percent of aqueous media, for example 10 to 60 weight percent.

The aqueous pigment dispersions of the present invention may further comprise one or more conventional additives selected from the group consisting of antisettling agents, wetting agents, preservatives, viscosity stabilizers, and auxiliaries affecting the rheology. For example, the aqueous pigment dispersion of the present invention may be based on the total weight of the aqueous pigment dispersion (a) from 5 to 80% by weight, for example from 10 to 50% by weight, (b) from the air of the invention. 2 to 25% by weight, for example 3 to 15% by weight, (c) 5 to 80% by weight of aqueous media, for example 10 to 60% by weight, and (d) greater than 0 to 5% by weight of additives. Can be.

The viscosity of the aqueous pigment dispersion of the present invention may be 1.5-4.0 cps, for example in the range 3.0-4.0 cps.

The aqueous pigment dispersions of the present invention can be prepared using conventional methods for preparing pigment dispersions. The pigment may be prepared by dispersing the pigment in the presence of an aqueous medium and a dispersant, or the dispersant, pigment and additives may be mixed and the aqueous medium may be used to adjust the concentration of the aqueous pigment dispersion. For example, an aqueous medium, a dispersant, and an additive may be mixed first, followed by the addition of a pigment. In order to disperse the mixture thus prepared, an agitator, rotor / stator mill, dissolver, ball mill, ball mill (eg sand mill or bead mill) equipped with agitator, high speed Mixers, roll mixing mills, and micro fluidizers can be used.

The aqueous pigment dispersion of the present invention can be in liquid to paste form, and is excellent in high cohesive stability and storage stability, color strength, gloss, homogeneity, brightness, wear resistance, and rheological stability. The aqueous pigment dispersions of the present invention can be usefully used as paints, dispersion varnishes, printing inks such as textile printing inks, wood preservation systems, viscous solution dyes, varnishes. In addition, the aqueous pigment dispersion of the present invention can be usefully used as a colorant in electrophotographic toner, electrophotographic developer such as one component or two component powder toner, magnetic toner, liquid toner, polymerized toner. The aqueous pigment dispersions of the present invention can also be usefully used as colorants in inkjet inks based on both aqueous and non-aqueous systems, operating according to high temperature melting methods, or inks based on microemulsions.

The copolymers of the present invention can be used as dispersants for both organic and inorganic pigments. The aqueous pigment dispersion containing the copolymer of the present invention had a low viscosity and improved pigment dispersibility.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited by the following examples.

Example  1: copolymer preparation

A flask equipped with a thermometer, a stirrer, a nitrogen inlet, and a reflux condenser was placed in an oil bath to maintain a constant temperature at 80 ° C. 95.0 g of diethylene glycol monomethyl ether, 18.0 g of 2-naphthyl acrylate and 2.0 g of methacrylic acid were added to the flask. It was refluxed at 80 ° C. for 10 minutes. A mixture of 5.0 g of diethylene glycol monomethyl ether and 0.2 g of potassium persulfate catalyst was added over 5 minutes. Then, the mixture was reacted at 80 ° C. for 12 hours and cooled to collect a copolymer. The produced copolymer was a random copolymer, a viscous liquid pale yellow polymer (Mn (number average molecular weight): 10,070; Mw (weight average molecular weight): 34,240).

Example  2: copolymer preparation

In Example 1, 90.0 g of 2-naphthyl acrylate and 8.0 g of methacrylic acid were added to the flask. Secondly, a mixture of 2.0 g of methacrylic acid and 0.2 g of potassium persulfate catalyst was added. In the same manner as in Example 1, a copolymer was prepared. The produced copolymer was a random copolymer which was a viscous liquid pale yellow polymer (Mn: 24,578; Mw: 76,160; yield: 98.7%).

Example  3: copolymer preparation

In Example 1, 95.0 g of diethylene glycol monomethyl ether, 18.0 g of 2-naphthyl acrylate, 2.0 g of acrylic acid, and 1.0 g of mercapto acetic acid were added to the flask. Secondly, 5.0 g of diethylene glycol monomethyl ether and 0.2 g of azobisisobutyronitrile catalyst amount were added. In the same manner as in Example 1, a copolymer was prepared. The produced copolymer was a random copolymer, a viscous liquid pale yellow polymer (Mn: 6,140; Mw: 45,430; yield: 18.7%).

Example  4: copolymer preparation

In Example 1, 95.0 g of diethylene glycol monomethyl ether, 18.0 g of 2-naphthyl acrylate, 2.0 g of acrylamide, and 1.0 g of mercapto acetic acid were added to the flask. Secondly, 5.0 g of diethylene glycol monomethyl ether and 0.2 g of azobisisobutyronitrile catalyst amount were added. In the same manner as in Example 1, a copolymer was prepared. The prepared copolymer was a random copolymer, a viscous liquid pale yellow polymer (Mn: 7,340; Mw: 57,200; yield: 19.1%).

Example  5: water based pigment Dispersion  Produce

Five kinds of pigments were used in the preparation of the aqueous pigment dispersion. Organic pigments include carbon black Printex 75 (Degussa) and Raven 3500 (Columbian Chemical), quinac reddone red pigment Chromofine Magenta 6887 (Dainichiseika Color & Chemicals), and phthalocyanine blue pigment Endurophthal Blue BT-617D (Clariant) Irgacolor Yellow (Ciba), a bismuth-vanadate yellow pigment, was used as the inorganic pigment.

15 wt% of the pigment, the copolymer prepared in Example 1 (5 wt% if the pigment is carbon black, 7.5 wt% otherwise) and 77.5 wt% of the aqueous medium (pH 7-7.5) Mixed. The mixture was stirred for 1 hour in an in-line mixer and again dispersed for 1 hour in a microfluidizer to prepare an aqueous pigment dispersion.

Experimental Example Aqueous Pigment Dispersion  Property evaluation

The average particle diameter, viscosity and surface tension of the aqueous pigment dispersion prepared in Example 5 were measured. In addition, 24 hours after the preparation of the pigment dispersion, when observed with an Olympus microscope (magnification: 100 times), whether it was uniform, exhibited Brownian motion, and whether or not the aggregation of pigment particles was observed visually, Dispersibility was evaluated. The results are shown in Table 1.

TABLE 1 Aqueous pigment dispersion comprising the copolymer of Example 1

Type of pigment Pigment 1 Pigment 2 Pigment 3 Pigment 4 Pigment 5 Average particle diameter
(nm) 110 102 165 148 156 Surface tension
(dyne / cm) 52 54 49 48 49 Viscosity (cps) 3.3 3.1 3.0 3.9 4.0 Pigment dispersibility Great Great Great Great Great

Pigment 1: Printex 75

Pigment 2: Raven 3500

Pigment 3: Chromofine Magenta 6887

Pigment 4: Endurophthal Blue BT-617D

Pigment 5: Irgacolor Yellow

Using the copolymer prepared in Examples 2 to 4 and the same method as in Example 5, an aqueous pigment dispersion was prepared, and the physical properties thereof were evaluated. The results are shown in Tables 2 to 4.

TABLE 2 Aqueous pigment dispersions comprising the copolymer of Example 2

Type of pigment Pigment 1 Pigment 2 Pigment 3 Pigment 4 Pigment 5 Average particle diameter
(nm) 107 100 167 169 154 Surface tension
(dyne / cm) 57 55 49 48 49 Viscosity (cps) 3.0 3.1 3.3 3.5 3.8 Pigment dispersibility Great Great Good Great Great

TABLE 3 Aqueous pigment dispersions comprising the copolymer of Example 3

Type of pigment Pigment 1 Pigment 2 Pigment 3 Pigment 4 Pigment 5 Average particle diameter
(nm) 103 105 156 167 135 Surface tension
(dyne / cm) 59 57 49 50 49 Viscosity (cps) 3.3 3.5 3.4 3.7 3.7 Pigment dispersibility Great Great Good Great Great

TABLE 4 Aqueous pigment dispersions comprising the copolymer of Example 4

Type of pigment Pigment 1 Pigment 2 Pigment 3 Pigment 4 Pigment 5 Average particle diameter
(nm) 117 109 187 178 180 Surface tension
(dyne / cm) 55 56 51 51 50 Viscosity (cps) 3.2 3.4 3.2 3.7 3.6 Pigment dispersibility Good Great Good Great Great

As a comparative example, an aqueous pigment dispersion was prepared using the same aqueous dispersing agents Disperbyk 194 (BYK Chemie) and EFKA-4550 (Ciba), and the same method as in Example 5, and the physical properties thereof were evaluated. The results are shown in Tables 5 to 6.

Table 5: Aqueous Pigment Dispersions Containing Disperbyk 194

Type of pigment Pigment 1 Pigment 2 Pigment 3 Pigment 4 Pigment 5 Average particle diameter
(nm) 180 260 280 308 502 Surface tension
(dyne / cm) 51 56 50 51 50 Viscosity (cps) 5.1 7.8 5.4 8.2 8.5 Pigment dispersibility Good Bad Good Bad Bad

TABLE 6 Aqueous pigment dispersions comprising EFKA-4550

Type of pigment Pigment 1 Pigment 2 Pigment 3 Pigment 4 Pigment 5 Average particle diameter
(nm) 170 150 674 1215 652 Surface tension
(dyne / cm) 54 54 51 53 51 Viscosity (cps) 4.9 4.9 8.8 9.2 9.7 Pigment dispersibility Good Good Bad Bad Bad

As shown in Tables 1 to 4, the aqueous pigment dispersion containing the copolymer of the present invention was excellent in pigment dispersibility for all five kinds of pigments, and the average particle diameter and viscosity were also low. On the other hand, as shown in Tables 5 and 6, the aqueous pigment dispersions comprising the dispersants Disperbyk 194 and EFKA-4550 showed good pigment dispersibility only for certain pigments, and the viscosity was higher than that of the aqueous pigment dispersions of the present invention. High.

Claims (11)

A copolymer in which the structural units represented by the following formula (A) and the structural units represented by the following formula (B) are linearly arranged: Formula (A)

Formula (B)

In the above, Ar is a substituted or unsubstituted C ₆ -C ₂₅ aryl group; R ₁ and R ₂ are each independently hydrogen or a C ₁ -C ₆ alkyl group; R ₃ is —SO ₂ NHCOR ₈ , —CONH ₂ , wherein —COOH, —SO ₃ H, —PO ₃ H ₂ , R ₈ is a saturated or unsaturated C ₁ -C ₆ alkyl group or phenyl Or salts thereof; R ₄ , R ₅ , R ₆ and R ₇ are each independently hydrogen, halogen or a substituted or unsubstituted C ₁ -C ₆ alkyl group; Wherein X represents a simple bond or a C ₁ -C ₆ alkylene oxide or a C ₁ -C ₆ alkylene group; The number of structural units of the formula (A) and the structural units of the formula (B) is 2-20 and 10-1000, respectively. The method of claim 1, wherein Ar is naphthyl, anthracenyl, benzo [a] pyrenyl, or coronyl, or a derivative thereof; R ₁ and R ₂ are independently of each other hydrogen or methyl; R ₃ is —COOH, —SO ₃ H, —CONH ₂ or a salt thereof; And the ratio of the number of structural units of formula (B) to the number of structural units of formula (A) is from 10 to 50. The copolymer according to claim 1, wherein the copolymer has a number average molecular weight (Mn) of 1,000 to 50,000 g / mol. The copolymer of claim 1, wherein the copolymer is a random copolymer or a block copolymer. An aqueous pigment dispersion comprising at least one pigment, an aqueous medium and a dispersant, wherein the dispersant is the copolymer of any one of claims 1-4. 6. The aqueous system of claim 5, wherein the aqueous pigment dispersion comprises from 5 to 80 weight percent of the pigment, from 2 to 25 weight percent of the copolymer and from 5 to 80 weight percent of the aqueous medium, based on the total weight of the aqueous pigment dispersion. Pigment dispersions. The method of claim 5, wherein the pigment is monoazo pigment, disazo pigment, azo lake pigment, phthalocyanine, triphenylmethane, thioindigo, thiazine indigo, quinacridone, dioxazine, isoindolinone, isoindolin, Quinaphthalone, Quinophthalone, Perylene, Anthrone, Perinone, Diketopyrrolopyrrole, Benzimidazoloneazo, Naphthol, Carbon Black, Titanium Dioxide, Zinc Sulfide, Iron Oxide, Chromium Oxide, Nickel or Chromium Antimony Dioxide Water-based pigment dispersions selected from the group consisting of titanium, cobalt oxide and bismuth vanadate. The method of claim 5, wherein the aqueous medium is water or ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol or alkyl ethers thereof; Glycerin, N-methylpyrrolidone, 1,3-dimethylimidazolinone, thiodiglycol, 2-pyrrolidone, dimethyl sulfoxide, sulfolane, diethanolamine, triethanolamine, ethanol, and isopropyl alcohol An aqueous pigment dispersion, which is a mixture of at least one aqueous organic solvent selected from the group consisting of and water. The aqueous pigment dispersion of claim 5 wherein the viscosity of the aqueous pigment dispersion is 1.5-4 cps. 6. The aqueous pigment dispersion of claim 5 wherein the aqueous pigment dispersion further comprises one or more additives selected from the group consisting of antisettling agents, wetting agents, preservatives and viscosity stabilizers. The waterborne pigment dispersion according to claim 10, wherein the aqueous pigment dispersion is based on the total weight of the aqueous pigment dispersion, from 5 to 80% by weight of the pigment, from 2 to 25% by weight of the copolymer, from 5 to 80% by weight of the aqueous medium, and from greater than 0 to the additive. 5 wt% of the aqueous pigment dispersion.