JP7633864B2 - Coloring composition and coating film - Google Patents

Description

The present invention relates to a coloring composition containing a black colorant, a dispersant, and an aqueous dispersion medium.

In recent years, in order to prevent air pollution, there has been a demand to reduce emissions of volatile organic compounds (VOCs) from factories and business establishments. For this reason, the switch to water-based paints has been considered for the paints used to paint the metal plates that make up the bodies of automobiles and other vehicles. In addition to high levels of film performance such as durability, acid resistance, resistance to scratches caused by car washes, and chipping resistance, automotive paints are also required to have better finished appearances, such as greater transparency and color development than ever before.

The colorants used in paints generally have a hydrophobic surface. Furthermore, the dispersants used in solvent-based colored paints have low solubility in water and poor dispersion stability in aqueous dispersion media. In particular, carbon particles such as carbon black used as black colorants have a small primary particle diameter and an extremely large specific surface area, resulting in very strong cohesive forces. For this reason, it is difficult to disperse carbon particles uniformly in aqueous dispersion media, and even if they are dispersed, they tend to aggregate.

Therefore, a technique for improving the dispersibility of carbon black in paints using carbon black as a black colorant has been proposed. For example, Patent Document 1 describes a highly jet-black carbon black dispersion (when the colorant is black, the coloring property is particularly pronounced as jet-black) in which carbon black with a DBP oil supply of 150 ml/100 g or less, an average primary particle size of 15 nm or less, a specific surface area of 500 ^m2 /g or less, and a pH in the acidic to neutral range is dispersed as fine particles in an aqueous medium by a dispersant. In Patent Document 1, the dispersibility of carbon black is improved by controlling the physical properties of carbon black (see Patent Document 1 (Claim 1, paragraphs 0019, 0021, 0024)).

Patent Document 2 describes an aqueous coating composition that contains (A) (a) a polymerizable unsaturated monomer having a specific cationic functional group, (b) a polymerizable unsaturated monomer having a polyoxyalkylene chain, and (c) a copolymer of other polymerizable unsaturated monomers, (B) a pigment, and (C) an acid group- and hydroxyl group-containing acrylic resin (see Patent Document 1 (Claim 1, paragraph 0014)).

JP 2008-285632 A JP 2014-5399 A

In water-based paints that use carbon particles as a black coloring material, paints that improve the dispersibility of the carbon particles have been proposed, but there is still room for improvement in preventing the aggregation of the carbon particles. The present invention was made in consideration of the above circumstances, and aims to provide a water-based coloring composition that contains a black coloring material (especially carbon particles) and that can improve the jet blackness of the coating film when applied.

The coloring composition of the present invention, which has been able to solve the above problems, contains a black colorant, a dispersant, and an aqueous dispersion medium, and is characterized in that the dispersant contains a block copolymer having an A block containing a structural unit represented by formula (1) and a B block containing a structural unit represented by formula (3) and a structural unit having a basic group.

［式（１）において、ｎ１は２～３０の整数を表す。Ｒ¹¹は水素原子または炭素数が１～３のアルキル基を表す。Ｒ¹²は炭素数が１～３のアルキレン基を表す。Ｒ¹³は水素原子またはメチル基を表す。なお、複数存在するＲ¹²は、それぞれ同一でも異なっていてもよい。］

[In formula (1), n1 represents an integer of 2 to 30. R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R ¹² represents an alkylene group having 1 to 3 carbon atoms. R ¹³ represents a hydrogen atom or a methyl group. Note that a plurality of R ¹² 's may be the same or different.]

［式（３）において、Ｒ³¹は脂環式炭化水素基を表す。Ｚ^３はＯまたはＮＨを表す。Ｒ³²は水素原子またはメチル基を表す。］

[In formula (3), R ³¹ represents an alicyclic hydrocarbon group. Z ³ represents O or NH. R ³² represents a hydrogen atom or a methyl group.]

The block copolymer contained as a dispersant in the coloring composition of the present invention has a structural unit represented by formula (1) contained in the A block that has high affinity with the aqueous dispersion medium, and a structural unit represented by formula (3) and a structural unit having a basic group contained in the B block that adsorb to the black colorant. Therefore, the coloring composition of the present invention has high dispersibility of the black colorant and can form a coating film with excellent jet blackness.

The coloring composition of the present invention is an aqueous coloring composition that contains a black colorant (particularly carbon particles), and can produce a coating film with excellent jet black color.

<Coloring Composition>
The colored composition of the present invention contains a dispersant (a block copolymer), a black colorant, and an aqueous dispersion medium.

(Coloring material)
The black colorant used in the present invention is not particularly limited, and can be a pigment or dye used as a black colorant in conventional paints, and is preferably a black pigment from the viewpoint of light resistance and heat resistance. Examples of black pigments include carbon black such as furnace black, channel black, acetylene black, thermal black, lamp black, and bone black; carbon nanotubes; carbon nanofibers; fullerene; natural graphite; graphite; perylene pigments; lactam pigments; titanium black; metal oxides such as copper, iron, manganese, cobalt, chromium, nickel, zinc, calcium, and silver; composite oxides; metal sulfides; metal sulfates; and metal carbonates, and are preferably at least one type of carbon particles selected from the group consisting of carbon black and carbon nanotubes.

The primary particle size of the carbon particles is not particularly limited, but is preferably 5 nm to 100 nm.
The specific surface area of the carbon particles is preferably 300 m ² /g to 1300 ^{m 2} /g, and more preferably 400 m ² /g to 800 m ² /g. The specific surface area is measured according to JIS K 6217-3 (2001).

The DBP (dibutyl phthalate) oil absorption of the carbon particles is preferably 50 ml/100 g to 150 ml/100 g, and more preferably 80 ml/100 g to 120 ml/100 g. The DBP oil absorption is measured according to JIS K 6217-4 (2017).

The carbon particles may have their surfaces subjected to an oxidation treatment. By subjecting the carbon particles to an oxidation treatment, carboxyl groups or phenolic hydroxyl groups can be added to the surfaces of the carbon particles. The oxidation treatment can be performed by treating the surfaces of the carbon particles with ozone, nitric acid, or the like. Carbon particles with carboxyl groups or phenolic hydroxyl groups added to their surfaces have an acidic pH.

When 1 g of carbon particles is dispersed in 100 ml of water (25°C), the pH of the dispersion is preferably 3 to 9, and more preferably 5 to 9.

Colorants other than black may be included to adjust the hue, etc., as long as they do not impair the preferred physical properties of the present invention.

The other coloring materials are not particularly limited, and pigments and dyes used as coloring materials in conventional paints can be used, with pigments being preferred from the viewpoint of light resistance and heat resistance. As the pigment, either organic or inorganic pigments may be used, but organic pigments containing an organic compound as the main component are preferred.

Examples of organic pigments include blue, red, yellow, green, purple, and orange pigments. Examples of the structure of organic pigments include azo pigments such as phthalocyanine pigments, monoazo pigments, diazo pigments, and condensed diazo pigments, and polycyclic pigments such as diketopyrrolopyrrole pigments, isoindolinone pigments, isoindoline pigments, quinacridone pigments, indigo pigments, thioindigo pigments, quinophthalone pigments, dioxazine pigments, anthraquinone pigments, perylene pigments, and perinone pigments.

The coloring composition may contain only one type of other coloring material, or multiple types.

Blue pigments, according to compounds classified as pigments in the Color Index (C.I.), include C.I. Pigment Blue 1, 1:2, 9, 14, 15, 15:1, 15:2, 15:3, 15:4, 15:5, 15:6, 16, 17, 17:1, 19, 22, 25, 27, 28, 29, 33, 35, 36, 56, 56:1, 60, 61, 61:1, 62, 63, 66, 67, 68, 71, 72, 73, 74, 75, 76, 78, 79, 80, etc. Phthalocyanine pigments include C.I. C.I. Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17, 17:1, and 75 are preferred, and as copper phthalocyanine pigments and monohalogenated copper phthalocyanine pigments, C.I. Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17, and 17:1 are preferred. As an anthraquinone pigment, C.I. Pigment Blue 60 is preferred. As a dioxazine pigment, C.I. Pigment Blue 80 is preferred.

Red pigments include C.I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 14, 15, 16, 17, 21, 22, 23, 31, 32, 37, 38, 41, 47, 48:1, 48:2, 48:3, 48:4, 49, 49:1, 49:2, 50:1, 52:2, 53, 53:1, 53:2, 53:3, 57, 57:1, 57:2, 58:4, 60 , 63, 63:1, 63:2, 64, 64:1, 68, 69, 81, 81:1, 81:2, 81:3, 81:4, 83, 88, 90:1, 101, 101:1 , 104, 108, 108:1, 109, 112, 113, 114, 122, 123, 144, 146, 147, 149, 151, 166, 168, 169, 170, 172, 173, 174, 175, 176, 177, 178, 179, 181, 184, 185, 187, 188, 190, 193, 194, 20 0, 202, 206, 207, 208, 209, 210, 214, 215, 216, 221, 224, 230, 231, 232, 233, 235, 236, 2 37, 238, 239, 242, 243, 245, 247, 249, 250, 251, 253, 254, 255, 256, 257, 258, 259, 260, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274, 275, 276, 291, etc.

Yellow pigments include C.I. Pigment Yellow 1, 1; 1, 2, 3, 4, 5, 6, 9, 10, 12, 13, 14, 16, 17, 24, 31, 32, 34, 35, 35: 1, 36, 36: 1, 37, 37: 1, 40, 41, 42, 43, 48, 53, 55, 60, 61, 62, 62: 1, 63, 65, 73 , 74, 75, 77, 81, 83, 87, 93, 94, 95, 97, 98, 100, 101, 104, 105, 108, 109, 110, 111, 116, 117, 119, 120, 126, 127, 127:1, 128, 129, 133, 134, 136 , 138, 139, 142, 147, 148, 150, 151, 153, 154, 155, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 172, 180, 181, 182, 183, 184, 185, 188, 189, 190, 191, 191:1, 192, 193, 194, 195, 196, 197, 198, 199, 200, 202, 203, 204, 205, 206, 207, 208, 213, 215, etc.

Examples of green pigments include C.I. Pigment Green 1, 2, 4, 7, 8, 10, 13, 14, 15, 17, 18, 19, 26, 36, 45, 48, 50, 51, 54, 55, 58, 59, 62, 63, aluminum phthalocyanine, polyhalogenated aluminum phthalocyanine, aluminum phthalocyanine hydroxide, diphenoxyphosphinyloxyaluminum phthalocyanine, diphenylphosphinyloxyaluminum phthalocyanine, polyhalogenated diphenoxyphosphinyloxyaluminum phthalocyanine, polyhalogenated diphenylphosphinyloxyaluminum phthalocyanine, etc.

Examples of purple pigments include C.I. Pigment Violet 1, 1:1, 2, 2:2, 3, 3:1, 3:3, 5, 5:1, 14, 15, 16, 19, 23, 25, 27, 29, 31, 32, 37, 39, 42, 44, 47, 49, and 50.

Examples of orange pigments include C.I. Pigment Orange 1, 2, 5, 13, 16, 17, 19, 20, 21, 22, 23, 24, 34, 36, 38, 39, 43, 46, 48, 49, 61, 62, 64, 65, 67, 68, 69, 70, 71, 72, 73, 74, 75, 78, and 79.

Inorganic pigments include barium sulfate, lead sulfate, titanium oxide (rutile type, anatase type, etc.), yellow lead, red iron oxide, and chromium oxide.

The number-average particle diameter of the pigment may be appropriately selected depending on the application, and is not particularly limited. From the viewpoint of high brightness, it is preferable that the coloring composition contains a pigment having a number-average particle diameter of 10 nm to 150 nm.

The pigment may contain a dye derivative as a dispersing aid. The dye derivative preferably contains an acidic dye derivative having an acidic group in order to form an ionic bond with a basic group (e.g., an amino group) in the block copolymer contained in the dispersant and adsorb it. This dye derivative has an acidic group introduced into the dye skeleton. The dye skeleton is preferably the same or similar to the pigment constituting the coloring composition, or the same or similar to the compound that is the raw material for the pigment. Specific examples of the dye skeleton include an azo dye skeleton, a phthalocyanine dye skeleton, an anthraquinone dye skeleton, a triazine dye skeleton, an acridine dye skeleton, and a perylene dye skeleton. The acidic group introduced into the dye skeleton is preferably a carboxy group, a phosphoric acid group, or a sulfonic acid group. For convenience of synthesis and due to the strength of acidity, a sulfonic acid group is preferable. The acidic group may be directly bonded to the dye skeleton, or may be bonded to the dye skeleton via a hydrocarbon group such as an alkyl group or an aryl group; an ester, an ether, a sulfonamide, or a urethane bond.

There are no particular limitations on the amount of dye derivative used, but it is preferable that the amount be, for example, 4 to 17 parts by weight per 100 parts by weight of pigment.

From the viewpoint of brightness, the upper limit of the content of the coloring material in the coloring composition is usually 80 mass%, preferably 70 mass%, and more preferably 60 mass%, based on the total solid content of the coloring composition. The lower limit of the content of the coloring material in the coloring composition is usually 3 mass%, preferably 20 mass%, and more preferably 30 mass%, based on the total solid content of the coloring composition. Here, the solid content refers to components other than the dispersion medium described below.

The content of the dispersant relative to the colorant in the coloring composition is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the colorant, and is preferably 200 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less.

(Dispersant)
The dispersant used in the present invention contains a block copolymer having an A block containing a structural unit represented by formula (1) and a B block containing a structural unit represented by formula (3) and a structural unit having a basic group. The dispersant contains the block copolymer as a main component (50% by mass or more), preferably contains the block copolymer in an amount of 75% by mass or more, and more preferably is composed only of the block copolymer. The block copolymer is considered to exert an effect of increasing the dispersibility of the black colorant, for example, by the alicyclic hydrocarbon group in its structure (B block) being firmly bonded to the hydrophobic surface of the colorant, and the B block being adsorbed to the black colorant (e.g., carbon particles).

The dispersant can be made into a dispersant solution before preparing the coloring composition to facilitate dispersion of the black coloring material (e.g., carbon particles). The solvent used in the dispersant solution is preferably a solvent that can dissolve the dispersant, does not react with these components, and has moderate volatility. Examples of the solvent include the dispersion medium used in the coloring composition described below. The content of the solvent in the dispersant solution is not particularly limited and can be adjusted as appropriate. The upper limit of the content of the solvent in the dispersant solution is usually 99% by mass. In addition, the lower limit of the content of the dispersion medium in the dispersant solution is usually 10% by mass, and preferably 30% by mass, taking into account the viscosity suitable for producing the coloring composition described below.

(Block Copolymer)
In the present invention, "A block" can be rephrased as "A segment", and "B block" can be rephrased as "B segment". In the present invention, "vinyl monomer" refers to a monomer having a radically polymerizable carbon-carbon double bond in the molecule. "Structural unit derived from vinyl monomer" refers to a structural unit in which the radically polymerizable carbon-carbon double bond of a vinyl monomer is polymerized to become a carbon-carbon single bond. "(Meth)acrylic" refers to "at least one of acrylic and methacrylic". "(Meth)acrylate" refers to "at least one of acrylate and methacrylate". "(Meth)acryloyl" refers to "at least one of acryloyl and methacryloyl".

(Block A)
The A block is a block containing a structural unit represented by formula (1). The A block may have only one type of structural unit represented by formula (1), or may have two or more types of structural units.

［式（１）において、ｎ１は２～３０の整数を表す。Ｒ¹¹は水素原子または炭素数が１～３のアルキル基を表す。Ｒ¹²は炭素数が１～３のアルキレン基を表す。Ｒ¹³は水素原子またはメチル基を表す。なお、複数存在するＲ¹²は、それぞれ同一でも異なっていてもよい。］

[In formula (1), n1 represents an integer of 2 to 30. R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R ¹² represents an alkylene group having 1 to 3 carbon atoms. R ¹³ represents a hydrogen atom or a methyl group. Note that a plurality of R ¹² 's may be the same or different.]

In formula (1), n1 is 2 or more, preferably 5 or more, and 30 or less, preferably 20 or less, more preferably 15 or less.

The alkyl group having 1 to 3 carbon atoms represented by R ¹¹ may be either linear or branched, but is preferably linear. Specific examples of the alkyl group having 1 to 3 carbon atoms represented by R ¹¹ include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

The alkylene group having 1 to 3 carbon atoms represented by R ¹² may be either linear or branched, but is preferably linear. Specific examples of the alkylene group having 1 to 3 carbon atoms represented by R ¹² include a methylene group, an ethylene group, a trimethylene group, and a propane-1,2-diyl group. R ¹² is preferably an ethylene group or a trimethylene group.

Examples of monomers constituting the structural unit represented by formula (1) include (meth)acrylates having a polyalkylene glycol structure. The polyalkylene glycol portion may be, for example, a mixture of ethylene oxide and propylene oxide. Examples of the (meth)acrylates having a polyalkylene glycol structure include (meth)acrylates having a polyethylene glycol structure such as polyethylene glycol (degree of polymerization = 2-30) methyl ether (meth)acrylate, polyethylene glycol (degree of polymerization = 2-30) ethyl ether (meth)acrylate, and polyethylene glycol (degree of polymerization = 2-30) propyl ether (meth)acrylate; and (meth)acrylates having a polypropylene glycol structural unit such as polypropylene glycol (degree of polymerization = 2-30) methyl ether (meth)acrylate, polypropylene glycol (degree of polymerization = 2-30) ethyl ether (meth)acrylate, and polypropylene glycol (degree of polymerization = 2-30) propyl ether (meth)acrylate.

The content of the structural unit represented by formula (1) is preferably 20% by mass or more, more preferably 35% by mass or more, and even more preferably 50% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less, in 100% by mass of the A block. If the content is 20% by mass or more, the affinity with the aqueous dispersion medium is further improved, and if it is 95% by mass or less, the affinity with the coating film-forming resin is better.

It is preferable that the A block further contains a structural unit represented by formula (2). The A block may contain only one type of structural unit represented by formula (2), or may contain two or more types. When the A block contains a structural unit represented by formula (2), the affinity with the coating film-forming resin is further improved.

［式（２）において、Ｒ²¹は、置換基を有していてもよい鎖状の炭化水素基を表す。Ｒ²²は水素原子またはメチル基を表す。］

[In formula (2), R ²¹ represents a chain hydrocarbon group which may have a substituent. R ²² represents a hydrogen atom or a methyl group.]

Examples of the chain-like hydrocarbon group represented by R ²¹ include linear alkyl groups and branched alkyl groups. The linear alkyl group preferably has 1 to 20 carbon atoms, more preferably has 1 to 10 carbon atoms, and even more preferably has 1 to 5 carbon atoms. Examples of the linear alkyl group include methyl, ethyl, n-propyl, n-butyl, n-hexyl, n-octyl, n-nonyl, n-decyl, and n-lauryl groups. The branched alkyl group preferably has 3 to 20 carbon atoms, more preferably has 3 to 10 carbon atoms, and even more preferably has 3 to 5 carbon atoms. Examples of the branched alkyl group include isopropyl, isobutyl, sec-butyl, tert-butyl, 2-ethylhexyl, neopentyl, and isooctyl groups.

Examples of the substituent that the chain hydrocarbon group represented by R ²¹ may have include a halogen group, an alkoxy group, a benzoyl group (--COC ₆ H ₅ ), and a hydroxy group.

Vinyl monomers that form the structural unit represented by formula (2) include (meth)acrylates having a chain alkyl group (straight-chain alkyl group or branched-chain alkyl group) and (meth)acrylates having an aromatic group. Among these, (meth)acrylates having a chain alkyl group (straight-chain alkyl group or branched-chain alkyl group) are preferred.

Examples of the (meth)acrylate having a linear alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, decyl (meth)acrylate, n-lauryl (meth)acrylate, and n-stearyl (meth)acrylate.

Examples of the (meth)acrylate having a branched alkyl group include isopropyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, and isodecyl (meth)acrylate.

Examples of aromatic groups include aryl groups, and may also have a chain portion such as an alkylaryl group, an aralkyl group, or an aryloxyalkyl group. Specific examples of (meth)acrylates having an aromatic group include benzyl (meth)acrylate, phenyl (meth)acrylate, and phenoxyethyl (meth)acrylate.

When the structural unit represented by formula (2) is contained, the content is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and is preferably 80% by mass or less, more preferably 65% by mass or less, even more preferably 50% by mass or less, in 100% by mass of the A block. If the content is 5% by mass or more, the affinity with the resin for forming the coating film is improved, and if it is 80% by mass or less, the affinity with the aqueous dispersion medium is improved.

The A block may be composed of only the structural unit represented by formula (1), or may be composed of only the structural unit represented by formula (1) and the structural unit represented by formula (2), or may contain other structural units. The total content of the structural unit represented by formula (1) and the structural unit represented by formula (2) in the A block is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

Specific examples of vinyl monomers that can form other structural units of the A block include (meth)acrylates having a hydroxy group, (meth)acrylates having a lactone-modified hydroxy group, (meth)acrylates having an alkoxy group, (meth)acrylates having an acidic group, (meth)acrylic acid, and (meth)acrylates having a cyclic ether group.

Examples of (meth)acrylates having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate. Among these, (meth)acrylates having a hydroxyalkyl group having 1 to 5 carbon atoms are more preferred.

Examples of (meth)acrylates having a lactone-modified hydroxy group include those obtained by adding lactone to the (meth)acrylates having a hydroxy group, and those having caprolactone added are preferred. The amount of caprolactone added is preferably 1 mol to 20 mol, and more preferably 1 mol to 10 mol. Preferred examples of (meth)acrylates having a lactone-modified hydroxy group include 1 mol caprolactone adduct of 2-hydroxyethyl (meth)acrylate, 2 mol caprolactone adduct of 2-hydroxyethyl (meth)acrylate, 3 mol caprolactone adduct of 2-hydroxyethyl (meth)acrylate, 4 mol caprolactone adduct of 2-hydroxyethyl (meth)acrylate, 5 mol caprolactone adduct of 2-hydroxyethyl (meth)acrylate, and 10 mol caprolactone adduct of 2-hydroxyethyl (meth)acrylate.

Examples of (meth)acrylates having an alkoxy group include methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate.

Examples of the acidic group include a carboxy group (--COOH), a sulfonic acid group (--SO ₃ H), a phosphoric acid group (--OPO ₃ H ₂ ), a phosphonic acid group (--PO ₃ H ₂ ), and a phosphinic acid group (--PO ₂ H ₂ ). Examples of the (meth)acrylate having an acidic group include a (meth)acrylate having a carboxy group, a (meth)acrylate having a phosphoric acid group, and a (meth)acrylate having a sulfonic acid group.

Examples of (meth)acrylates having a carboxy group include monomers obtained by reacting (meth)acrylates having a hydroxy group, such as carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, and 2-(meth)acryloyloxyethyl phthalate, with acid anhydrides, such as maleic anhydride, succinic anhydride, and phthalic anhydride. Examples of (meth)acrylates having a phosphoric acid group include 2-(phosphonooxy)ethyl (meth)acrylate. Examples of (meth)acrylates having a sulfonic acid group include ethyl sulfonate (meth)acrylate.

Examples of (meth)acrylates having a cyclic ether group include glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, 2-[(2-tetrahydropyranyl)oxy]ethyl (meth)acrylate, and 1,3-dioxane-(meth)acrylate.

It is preferable that the A block does not substantially contain a structural unit represented by formula (3) described below, a structural unit having a basic group, and a structural unit having a basic group that forms a salt. That is, the content of the structural unit represented by (3), the structural unit having a basic group, and the structural unit having a basic group that forms a salt is preferably 3% by mass or less, more preferably 1% by mass or less, and even more preferably 0.1% by mass or less, in 100% by mass of the A block, and it is particularly preferable that the A block does not contain a structural unit represented by (3), a structural unit having a basic group, and a structural unit having a basic group that forms a salt.

When two or more types of structural units are contained in the A block, the various structural units contained in the A block may be contained in the A block in any form, such as random copolymerization or block copolymerization, and from the viewpoint of uniformity, it is preferable that they are contained in the A block in the form of random copolymerization. For example, the A block may be formed by a copolymer of a structural unit consisting of an a1 block and a structural unit consisting of an a2 block.

(Block B)
The B block is a block containing a structural unit represented by formula (3) and a structural unit having a basic group.

(Structural unit represented by formula (3))
The structural unit represented by formula (3) in the B block may be of only one type, or of two or more types.

［式（３）において、Ｒ³¹は脂環式炭化水素基を表す。Ｚ^３はＯまたはＮＨを表す。Ｒ³²は水素原子またはメチル基を表す。］

[In formula (3), R ³¹ represents an alicyclic hydrocarbon group. Z ³ represents O or NH. R ³² represents a hydrogen atom or a methyl group.]

Examples of the alicyclic hydrocarbon group represented by R ³¹ include a cyclic alkyl group having a monocyclic structure and an alkyl group having a polycyclic structure. The number of carbon atoms in the alicyclic hydrocarbon group is preferably 4 to 18, more preferably 6 to 12, and even more preferably 6 to 10.

Examples of cyclic alkyl groups with a single ring structure include cyclohexyl, methylcyclohexyl, cyclododecyl, 3,3,5-trimethylcyclohexyl, and 4-tert-butylcyclohexyl groups. Examples of alkyl groups with a polycyclic structure include bornyl, isobornyl, 1-adamantyl, 2-adamantyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, norbornyl, dicyclopentanyl, and dicyclopentenyl groups.

Specific examples of vinyl monomers that form the structural unit represented by formula (3) include (meth)acrylates having a cyclic alkyl group with a monocyclic structure, and (meth)acrylates having a cyclic alkyl group with a polycyclic structure.

(Meth)acrylates having a cyclic alkyl group with a monocyclic structure include compounds in which a cyclic alkyl group is directly bonded to a (meth)acryloyloxy group. Specific examples include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, and 4-tert-butylcyclohexyl (meth)acrylate.

(Meth)acrylates having a cyclic alkyl group with a polycyclic structure include compounds in which a cyclic alkyl group with a bridged ring structure is directly bonded to a (meth)acryloyloxy group. Specific examples include bornyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, etc.

The content of the structural unit represented by formula (3) is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and is preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, in 100% by mass of the B block. If the content is 15% by mass or more, the dispersion performance of the colorant is further improved, and if it is 80% by mass or less, an increase in the viscosity of the coloring composition can be suppressed.

(Structural Unit Having a Basic Group)
The structural unit having a basic group may be a structural unit derived from a vinyl monomer having a basic group. The basic group is preferably an amino group in terms of availability of raw materials and ease of synthesis. In this specification, the amino group includes, in addition to a general amino group structure (-NH ₂ ), substituted amino groups represented by -NHR ⁴¹ and -NR ⁴¹ R ⁴² (R ⁴¹ and R ⁴² each independently represent a chain or cyclic hydrocarbon group. R ⁴¹ and R ⁴² may be bonded to each other to form a cyclic structure) in which H is substituted by a hydrocarbon group, and nitrogen-containing heterocyclic groups (pyridyl group, imidazole group, etc.).

The structural unit having a basic group is preferably a structural unit represented by formula (4) or a structural unit represented by formula (5). The structural unit represented by formula (4) or the structural unit represented by formula (5) in the B block may be of only one type or of two or more types.

［式（４）において、Ｒ⁴¹およびＲ⁴²は、それぞれ独立して、置換基を有していてもよい鎖状もしくは環状の炭化水素基を表す。Ｒ⁴¹およびＲ⁴²が互いに結合して環状構造を形成していてもよい。Ｒ⁴³は２価の炭化水素基を表す。Ｚ⁴はＯまたはＮＨを表す。Ｒ⁴⁴は水素原子またはメチル基を表す。］

[In formula (4), R ⁴¹ and R ⁴² each independently represent a chain or cyclic hydrocarbon group which may have a substituent. ^{R 41} and R ⁴² may be bonded to each other to form a cyclic structure. R ⁴³ represents a divalent hydrocarbon group. Z ⁴ represents O or NH. R ⁴⁴ represents a hydrogen atom or a methyl group.]

Examples of the chain-like hydrocarbon group represented by R ⁴¹ and R ⁴² include linear alkyl groups and branched alkyl groups. The linear alkyl group preferably has 1 to 20 carbon atoms, more preferably has 1 to 10 carbon atoms, and even more preferably has 1 to 5 carbon atoms. Examples of the linear alkyl group include methyl, ethyl, n-propyl, n-butyl, n-hexyl, n-octyl, n-nonyl, n-decyl, and n-lauryl. The branched alkyl group preferably has 3 to 20 carbon atoms, more preferably has 3 to 10 carbon atoms, and even more preferably has 3 to 5 carbon atoms. Examples of the branched alkyl group include isopropyl, isobutyl, sec-butyl, tert-butyl, 2-ethylhexyl, neopentyl, and isooctyl.

Examples of the substituent that the chain hydrocarbon group represented by R ⁴¹ and R ⁴² may have include a halogen group, an alkoxy group, a benzoyl group (--COC ₆ H ₅ ), and a hydroxy group.

Examples of the cyclic hydrocarbon group represented by R ⁴¹ and R ⁴² include a cyclic alkyl group, an aromatic group, and the like, and the cyclic alkyl group and the aromatic group may have a chain portion. The number of carbon atoms of the cyclic alkyl group is preferably 4 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, and even more preferably 6 to 10 carbon atoms. Examples of the cyclic alkyl group include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. The number of carbon atoms of the aromatic group is preferably 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, and even more preferably 6 to 8 carbon atoms. Examples of the aromatic group include a phenyl group, a tolyl group, a xylyl group, and a mesityl group. Examples of the cyclic alkyl group having a chain portion and the chain portion of the aromatic group having a chain portion include an alkylene group having 1 to 12 carbon atoms, preferably an alkylene group having 1 to 6 carbon atoms, and more preferably an alkylene group having 1 to 3 carbon atoms.

Examples of the substituent that the cyclic hydrocarbon group represented by R ⁴¹ and R ⁴² may have include a halogen group, an alkoxy group, a chain alkyl group, and a hydroxy group.

Examples of the cyclic structure formed by R ⁴¹ or R ⁴² bonding to each other include a 5- to 7-membered nitrogen-containing heterocycle or a condensed ring formed by condensing two of these. The nitrogen-containing heterocycle is preferably one that does not have aromaticity, and more preferably a saturated ring. Specific examples include structures represented by the following formulae (4-1), (4-2), and (4-3).

［式（４－１）、（４－２）、（４－３）において、Ｒ⁴⁵は、炭素数１～６のアルキル基を示す。ｌは０～５の整数を表す。ｍは０～４の整数を表す。ｎは０～４の整数を表す。＊は結合手を表す。ｌが２～５、ｍが２～４、ｎが２～４の場合、複数存在するＲ⁴⁵は、それぞれ同一でも異なっていてもよい。］

[In formulas (4-1), (4-2), and (4-3), R ⁴⁵ represents an alkyl group having 1 to 6 carbon atoms. l represents an integer of 0 to 5. m represents an integer of 0 to 4. n represents an integer of 0 to 4. * represents a bond. When l is 2 to 5, m is 2 to 4, and n is 2 to 4, multiple R ^45s may be the same or different.]

Examples of the divalent hydrocarbon group represented by R ⁴³ include an alkylene group having 1 to 10 carbon atoms, an alkenylene group having 1 to 10 carbon atoms, and an arenediyl group having 6 to 10 carbon atoms. Among these, an alkylene group having 1 to 10 carbon atoms is preferred. The alkylene group may be either linear or branched, but linear is preferred. The number of carbon atoms in the alkylene group is more preferably 1 to 4. Examples of the alkylene group include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, and a heptamethylene group.

Specific examples of vinyl monomers that form the structural unit represented by formula (4) include dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, dimethylaminobutyl (meth)acrylate, diethylaminoethyl (meth)acrylate, diethylaminopropyl (meth)acrylate, diethylaminobutyl (meth)acrylate, ethylaminoethyl (meth)acrylate, ethylaminopropyl (meth)acrylate, ethylaminobutyl (meth)acrylate, propylaminoethyl (meth)acrylate, propylaminopropyl (meth)acrylate, propylaminobutyl (meth)acrylate, and dimethylaminopropyl (meth)acrylamide.

［式（５）において、Ｒ⁸¹、Ｒ⁸²およびＲ⁸³は、同一または異なって、水素原子または置換基を有していてもよい炭素数１～１０のアルキル基を示す。Ｒ⁸⁴は、含窒素ヘテロ環基を示す。ｍ８は０～４の整数を示す。］

[In formula (5), R ⁸¹ , R ⁸² and R ⁸³ are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. R ⁸⁴ represents a nitrogen-containing heterocyclic group. m8 represents an integer of 0 to 4.]

The number of carbon atoms of the alkyl group in R ⁸¹ to R ⁸³ is preferably 1 to 6, more preferably 1 to 4. As the alkyl group, a methyl group or an ethyl group is more preferable, and a methyl group is particularly preferable. The substituent in R ⁸¹ to R ⁸³ is not particularly limited, and examples thereof include a carboxy group, a sulfonic acid group, and esters or salts thereof; an amino group; and a hydroxy group. R ⁸¹ to R ⁸³ are preferably a hydrogen atom.

Examples of the nitrogen-containing heterocyclic group represented by R ⁸⁴ include a 4-pyridyl group, a 1-imidazole group, a 2-pyridyl group, and a 9-carbazole group, with the 4-pyridyl group being preferred.

m8 is preferably an integer from 0 to 2, more preferably an integer from 0 to 1, and even more preferably 0.

Examples of vinyl monomers that form the structural unit represented by formula (5) include 4-vinylpyridine, 4-allylpyridine, 4-(3-butenyl)pyridine, 1-vinyl-1H-imidazole, 1-allyl-1H-imidazole, 2-vinylpyridyl, and 9-vinylcarbazole. Among these, 4-vinylpyridine is preferred.

The content of structural units having a basic group is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and is preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, in 100% by mass of the B block. If the content is 20% by mass or more, the dispersion performance for the colorant is further improved, and if it is 80% by mass or less, an increase in the viscosity of the color composition can be suppressed.

In the B block, the mass ratio of the structural unit represented by formula (3) to the structural unit having a basic group (structural unit represented by formula (3)/structural unit having a basic group) is preferably 0.15 or more, more preferably 0.2 or more, even more preferably 0.4 or more, and is preferably 4.0 or less, more preferably 3.0 or less, even more preferably 2.5 or less.

The total content of the structural unit represented by formula (3) and the structural unit having a basic group is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, in 100% by mass of the B block. The B block may be composed only of the structural unit represented by formula (3) and the structural unit having a basic group.

In the structural unit having a basic group, a part of the basic group may form a salt. Examples of the salt of the basic group include inorganic salts such as halide salts (F, Cl, Br, I, etc.) and sulfate salts of the basic group; and sulfonates, sulfates, phosphates, or carboxylates of organic compounds. In addition, the salt of the basic group is preferably an amino group salt in view of availability of raw materials and ease of synthesis. In this specification, the salt of the amino group also includes salts (e.g., halides) of quaternary ammonium groups (-NH ₄ ⁺ , -NR ₄ ⁺ , etc.).

Specific examples of vinyl monomers that can form other structural units of the B block include the same monomers as those exemplified as specific examples of monomers that can form other structural units of the A block.

In the B block, the content of the structural unit represented by (1) is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, and it is particularly preferable that the B block does not contain the structural unit represented by (1).

When two or more types of structural units are contained in the B block, the various structural units contained in the B block may be contained in the B block in any form, such as random copolymerization or block copolymerization, and from the viewpoint of uniformity, it is preferable that they are contained in the B block in the form of random copolymerization. For example, the B block may be formed by a copolymer of a structural unit consisting of a b1 block and a structural unit consisting of a b2 block.

(Block Copolymer)
The structure of the block copolymer is preferably a linear block copolymer. The linear block copolymer may have any structure (arrangement), but from the viewpoint of the physical properties of the linear block copolymer or the physical properties of the composition, when the A block is represented as A and the B block is represented as B, it is preferable that the block has at least one structure selected from the group consisting of (A-B) _m type, (A-B) _m -A type, and (B-A) _m -B type (m is an integer of 1 or more, for example, an integer of 1 to 3). Among these, from the viewpoint of the handling property during processing and the physical properties of the composition, it is preferable that the block is an A-B type diblock copolymer. By forming an A-B type diblock copolymer, the structural unit represented by formula (1) in the A block and the structural unit represented by formula (3) in the B block are localized, and it is considered that they can efficiently act favorably with the pigment and the dispersion medium (solvent). The block copolymer may have a block other than the A block and the B block.

The content of the A block is preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 60% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less, based on 100% by mass of the entire block copolymer. The content of the B block is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, based on 100% by mass of the entire block copolymer. By adjusting the contents of the A block and the B block within the above ranges, the dispersion performance when used as a dispersant is further improved.

The mass ratio of the A block to the B block in the block copolymer (A block/B block) is preferably 50/50 or more, more preferably 55/45 or more, even more preferably 60/40 or more, and is preferably 95/5 or less, more preferably 90/10 or less, even more preferably 80/20 or less. If the mass ratio of the A block to the B block is within the above range, the dispersion performance when used as a dispersant is further improved.

The content of the structural unit represented by formula (1) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, and particularly preferably 60% by mass or less, based on 100% by mass of the entire block copolymer.

The content of the structural unit represented by formula (3) is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on 100% by mass of the entire block copolymer, and is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less.

The content of structural units having a basic group is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, and is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, based on 100% by mass of the entire block copolymer.

The molecular weight of the block copolymer is measured by gel permeation chromatography (hereinafter referred to as "GPC"). The weight average molecular weight (Mw) of the block copolymer is preferably 3,000 or more, more preferably 5,000 or more, even more preferably 7,000 or more, and particularly preferably 10,000 or more, and is preferably 40,000 or less, more preferably 35,000 or less, and even more preferably 30,000 or less. If the weight average molecular weight is within the above range, the dispersion performance when used as a dispersant will be better.

The molecular weight distribution (PDI) of the block copolymer is preferably 2.5 or less, more preferably 2.0 or less, and even more preferably 1.7 or less. In the present invention, the molecular weight distribution (PDI) is calculated by (weight average molecular weight (Mw) of the block copolymer) / (number average molecular weight (Mn) of the block copolymer). The smaller the PDI, the narrower the molecular weight distribution width, and the copolymer has a uniform molecular weight. When the PDI value is 1.0, the molecular weight distribution width is the narrowest. In other words, the lower limit of the PDI is 1.0. When the molecular weight distribution (PDI) of the block copolymer exceeds 2.5, it includes both low and high molecular weights.

The amine value of the block copolymer is preferably 10 mgKOH/g or more, more preferably 20 mgKOH/g or more, and even more preferably 30 mgKOH/g or more, and is preferably 200 mgKOH/g or less, more preferably 150 mgKOH/g or less, and even more preferably 120 mgKOH/g or less. If the amine value is 10 mgKOH/g or more, the dispersion performance for the colorant is further improved, and if it is 200 mgKOH/g or less, an increase in the viscosity of the coloring composition can be suppressed.

(Method for Producing Block Copolymer)
Examples of methods for producing a block copolymer include a method in which an A block is first produced by a polymerization reaction of a vinyl monomer, and then a monomer for a B block is polymerized onto the A block; a method in which a B block is first produced, and then a monomer for an A block is polymerized onto the B block; and a method in which the A block and the B block are produced separately, and then the A block and the B block are coupled together.

The polymerization method is not particularly limited, but living radical polymerization is preferred. That is, the block copolymer is preferably one polymerized by living radical polymerization. The living radical polymerization method is preferable in that it maintains the simplicity and versatility of conventional radical polymerization methods, while being less susceptible to termination reactions and chain transfer, and growth is not hindered by side reactions that deactivate the growing end, making it easy to precisely control the molecular weight distribution and produce polymers with a uniform composition.

Living radical polymerization methods include those using transition metal catalysts (ATRP method), those using sulfur-based reversible chain transfer agents (RAFT method), and those using organic tellurium compounds (TERP method), depending on the method used to stabilize the polymer growth terminal. Among these methods, the TERP method is preferred from the viewpoints of the variety of monomers that can be used, molecular weight control in the polymer region, uniform composition, and coloring.

The TERP method is a method in which an organic tellurium compound is used as a chain transfer agent to polymerize a radically polymerizable compound (vinyl monomer), and is described, for example, in WO 2004/14848, WO 2004/14962, WO 2004/072126, and WO 2004/096870.

Specific polymerization methods of the TERP method include the following (a) to (d).
(a) A method of polymerizing a vinyl monomer using an organotellurium compound represented by formula (6):
(b) A method of polymerizing a vinyl monomer using a mixture of an organotellurium compound represented by formula (6) and an azo-based polymerization initiator.
(c) A method of polymerizing a vinyl monomer using a mixture of an organotellurium compound represented by formula (6) and an organoditelluride compound represented by formula (7).
(d) A method of polymerizing a vinyl monomer using a mixture of an organotellurium compound represented by formula (6), an azo-based polymerization initiator, and an organic ditelluride compound represented by formula (7).

［一般式（６）において、Ｒ⁶¹は、炭素数１～８のアルキル基、アリール基または芳香族ヘテロ環基を示す。Ｒ⁶²およびＲ⁶³は、それぞれ独立に、水素原子または炭素数１～８のアルキル基を示す。Ｒ⁶⁴は、炭素数１～８のアルキル基、アリール基、置換アリール基、芳香族ヘテロ環基、アルコキシ基、アシル基、アミド基、オキシカルボニル基、シアノ基、アリル基またはプロパルギル基を示す。
一般式（７）において、Ｒ⁶¹は、炭素数１～８のアルキル基、アリール基または芳香族ヘテロ環基を示す。］

[In formula (6), R ⁶¹ represents an alkyl group having 1 to 8 carbon atoms, an aryl group, or an aromatic heterocyclic group. R ⁶² and R ⁶³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ⁶⁴ represents an alkyl group having 1 to 8 carbon atoms, an aryl group, a substituted aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amido group, an oxycarbonyl group, a cyano group, an allyl group, or a propargyl group.
In formula (7), R ⁶¹ represents an alkyl group having 1 to 8 carbon atoms, an aryl group, or an aromatic heterocyclic group.

Specific examples of the organic tellurium compound represented by the general formula (6) include ethyl-2-methyl-2-n-butyltellanyl-propionate, ethyl-2-n-butyltellanyl-propionate, (2-hydroxyethyl)-2-methyl-methyltellanyl-propionate, and the organic tellurium compounds described in WO 2004/14848, WO 2004/14962, WO 2004/072126, and WO 2004/096870. Specific examples of the organic ditelluride compound represented by the general formula (7) include dimethyl ditelluride, dibutyl ditelluride, and the like. The azo polymerization initiator can be any azo polymerization initiator used in normal radical polymerization without any particular restrictions, such as 2,2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (ADVN), 1,1'-azobis(1-cyclohexanecarbonitrile) (ACHN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70), etc.

In the polymerization process, a vinyl monomer and an organic tellurium compound of general formula (6) are mixed in a vessel purged with an inert gas, and for the purpose of promoting the reaction and controlling the molecular weight and molecular weight distribution depending on the type of vinyl monomer, an azo polymerization initiator and/or an organic ditelluride compound of general formula (7) are further mixed. Examples of the inert gas include nitrogen, argon, and helium. Argon and nitrogen are preferable. The amount of the vinyl monomer used in (a), (b), (c), and (d) may be appropriately adjusted depending on the physical properties of the desired copolymer.

The polymerization reaction can be carried out without a solvent, but may be carried out by stirring the mixture using an aprotic or protic solvent generally used in radical polymerization. Examples of aprotic solvents that can be used include anisole, benzene, toluene, propylene glycol monomethyl ether acetate, ethyl acetate, and tetrahydrofuran (THF). Examples of protic solvents include water, methanol, and 1-methoxy-2-propanol. Solvents may be used alone or in combination of two or more. The amount of solvent used may be adjusted appropriately, and is preferably 0.01 ml to 50 ml per 1 g of vinyl monomer. The reaction temperature and reaction time may be adjusted appropriately depending on the molecular weight or molecular weight distribution of the resulting copolymer, but the mixture is usually stirred at 0°C to 150°C for 1 minute to 100 hours. After the polymerization reaction is completed, the solvent used and the remaining vinyl monomer are removed from the resulting reaction mixture by a conventional separation and purification means, and the desired copolymer can be separated.

The growing end of the copolymer obtained by the polymerization reaction is in the form of -TeR ⁶¹ (wherein R ⁶¹ is the same as above) derived from the tellurium compound, and is deactivated by operation in air after the polymerization reaction is completed, but tellurium atoms may remain. Since a copolymer with tellurium atoms remaining at the end is colored or has poor thermal stability, it is preferable to remove the tellurium atoms. Methods for removing tellurium atoms include a radical reduction method; a method of adsorption with activated carbon or the like; a method of adsorbing metal with an ion exchange resin or the like, and these methods can also be used in combination. The other end of the copolymer obtained by the polymerization reaction (the end opposite to the growing end) is in the form of -CR ⁶² R ⁶³ R ⁶⁴ (wherein R ⁶² , R ⁶³ and R ⁶⁴ are the same as R ⁶² , R ⁶³ and R ⁶⁴ in formula (6)) derived from the tellurium compound.

(Aqueous Dispersion Medium)
Examples of the aqueous dispersion medium include water or an aqueous solvent (a solvent miscible with water). Specifically, examples of the aqueous dispersion medium include alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, 1-methoxy-2-propanol, and 1-butoxy-2-propanol; polyhydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, and glycerin; ethers such as tetrahydrofuran, dioxane, ethylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, triethylene glycol, monomethyl ether, and monoethyl ether; ketones such as acetone, methyl ethyl ketone, and isobutyl ketone; and amides such as dimethylformaldehyde and dimethylacetamide. Among these, alcohols and glycols are preferred. The aqueous solvent may be used alone or in combination of two or more.

The content of the aqueous dispersion medium in the coloring composition is not particularly limited and can be adjusted as appropriate. The upper limit of the content of the aqueous dispersion medium in the coloring composition is usually 99% by mass. The lower limit of the content of the aqueous dispersion medium in the coloring composition is usually 60% by mass, and preferably 80% by mass, taking into account the viscosity suitable for application of the coloring composition.

Depending on the application, the coloring composition may further contain additives such as a resin for forming a coating film, a surfactant, a leveling agent, a filler, an ultraviolet absorber, an antioxidant, a preservative, an anti-mold agent, a viscosity adjuster, a pH adjuster, an antifoaming agent, and a crosslinking agent. In addition, when conductive carbon particles are used in the coloring composition, it can be used for an electrode. In this case, the coloring composition may further contain additives such as a resin for forming an electrode, an electrode active material, a surfactant, a film-forming assistant, a leveling agent, a preservative, an anti-mold agent, a viscosity adjuster, a pH adjuster, an antifoaming agent, and a crosslinking agent.

(Film-forming resin)
The film-forming resin is a component that becomes the main body of the film when a coating film is formed using the coloring composition. The film-forming resin is not particularly limited, and any resin that has been used in conventional paints can be used. Examples of the film-forming resin include thermosetting resins, thermoplastic resins, and polymerizable compounds (polymerizable resins, monomers having one polymerizable unsaturated bond in the molecule, monomers having two or more polymerizable unsaturated bonds in the molecule, oligomers, etc.). The film-forming resin can be used alone or in a mixture of two or more kinds. When the film-forming resin is blended in the coloring composition, the content of the film-forming resin is preferably 60% by mass to 95% by mass of the total solid content of the coloring composition.

(thermosetting resin, thermoplastic resin)
Examples of thermosetting resins and thermoplastic resins include butyral resins, styrene-maleic acid copolymers, chlorinated polyethylene resins, chlorinated polypropylene resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, vinyl acetate resins, urethane resins, phenolic resins, polyester resins, acrylic resins, alkyd resins, styrene resins, styrene-acrylic resins, polyamide resins, rubber-based resins, cyclized rubbers, epoxy resins, celluloses, polybutadiene, polyimide resins, benzoguanamine resins, melamine resins, urea resins, silicone resins, and fluororesins.

(Polymerizable compound)
As the polymerizable resin as the polymerizable compound, a resin in which a crosslinkable group such as a (meth)acrylic compound or cinnamic acid is introduced into a linear polymer having a reactive substituent such as a hydroxy group, a carboxy group, an amino group, etc. via an isocyanate group, an aldehyde group, an epoxy group, etc. is used. Polymers in which a linear polymer containing an acid anhydride such as a styrene-maleic anhydride copolymer or an α-olefin-maleic anhydride copolymer is half-esterified with a (meth)acrylic compound having a hydroxy group such as a hydroxyalkyl (meth)acrylate are also used.

(Surfactant)
The surfactant may, for example, be a nonionic surfactant, an anionic surfactant, a cationic surfactant, or an amphoteric surfactant.
Examples of the nonionic surfactant include a fluorine-based surfactant, a silicone-based surfactant, and a polyoxyethylene-based surfactant.
Examples of anionic surfactants include alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, polyoxyethylene alkyl ether sulfonates, alkyl sulfates, alkyl sulfate ester salts, higher alcohol sulfate ester salts, aliphatic alcohol sulfate ester salts, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl phosphate ester salts, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, and special polymer surfactants.
Examples of the cationic surfactant include quaternary ammonium salts, imidazoline derivatives, and alkylamine salts.
Examples of the amphoteric surfactant include betaine-type compounds, imidazolium salts, imidazolines, and amino acids.

(Leveling Agent)
Examples of the leveling agent include silicone-based agents and fluorine-based agents. Examples of the silicone-based agents include dimethyl silicone oil, methylphenyl silicone oil, alkyl-modified silicone, alkoxy-modified silicone, oxyalkyl-modified silicone, glycol-modified silicone, polyether-modified silicone, polyether-modified silicone, and fatty acid ester-modified silicone. Examples of the fluorine-based agents include fluorocarbon compounds and fluorine silicone. These agents can be used alone or in combination of two or more.

(Filling material)
Examples of fillers include silicon dioxide, alumina, zinc oxide, potassium titanate fiber, aluminum flakes, stainless steel powder, tin powder, gold powder, metal-plated glass powder, titanic mica, calcium carbonate, barium sulfate, barium carbonate, kaolin, baryta, clay, other metal oxides, and composite metal oxides. These can be used alone or in combination of two or more kinds to prevent a decrease in viscosity or poor gloss.

(Resin for forming electrodes) Resins for forming electrodes are used to bond particles of active materials or conductive carbon materials together, or to bond conductive carbon particles to a current collector. Examples of the resin for forming electrodes include acrylic resins, polyurethane resins, polyester resins, phenolic resins, epoxy resins, phenoxy resins, urea resins, melamine resins, alkyd resins, formaldehyde resins, silicone resins, fluororesins, cellulose resins such as carboxymethyl cellulose, synthetic rubbers such as styrene butadiene rubber and fluororubber, conductive resins such as polyaniline and polyacetylene, and polymeric compounds containing fluorine atoms such as polyvinylidene fluoride, polyvinyl fluoride, and tetrafluoroethylene. Modified products, mixtures, or copolymers of these resins can also be used. These resins can also be used alone or in combination.

<Method of producing colored composition>
The coloring composition can be prepared by mixing a coloring material, a dispersant (block copolymer), an aqueous dispersion medium, and, if necessary, a resin for forming a coating film and other compounding agents. For mixing, a mixer/disperser such as a paint shaker, a bead mill, a ball mill, a dissolver, or a kneader can be used. The coloring composition is preferably filtered after mixing. Examples of the coloring composition include a coating composition for automobiles.

The coloring composition can be applied (coated) to a substrate such as a stainless steel plate or an aluminum plate by, for example, roll coating, spin coating, flow coating, slot die coating, spray coating, dip coating, electrostatic coating, electrostatic coating, brush coating, powder coating, or the like. If necessary, the coating is then heated to evaporate the solvent, and the coating is dried and cured. At this time, heating or irradiation with ultraviolet rays may be performed. The coating obtained by applying the coloring composition may be further coated with one or more layers of a top clear coating to form a top clear coating. A top clear coating is a liquid coating that forms a colorless or colored transparent coating film, consisting mainly of a resin component and a solvent, and further containing other coating additives, etc., as necessary.

The present invention will be described in more detail below based on specific examples. The present invention is not limited to the following examples, and can be modified as appropriate within the scope of the present invention. The polymerization rate, weight average molecular weight (Mw), molecular weight distribution (PDI), amine value, and coating film properties of the block copolymer were evaluated according to the following methods.

The meanings of the abbreviations are as follows:
BTEE: Ethyl 2-methyl-2-n-butyltellanyl-propionate AIBN: 2,2'-azobis(isobutyronitrile)
BA: Butyl acrylate M9EGA: Polyethylene glycol (degree of polymerization = 9) methyl ether acrylate (NOF Corporation, Blenmar (registered trademark) AME-400)
M11EGA: polyethylene glycol (degree of polymerization = 11) methyl ether acrylate (manufactured by Green Co., Ltd., KOMERATE-A040TT)
CHA: cyclohexyl acrylate IBXA: isobornyl acrylate DCPA: dicyclopentanyl acrylate DMAEMA: dimethylaminoethyl methacrylate 4VPy: 4-vinylpyridine PMA: propylene glycol monomethyl ether acetate MP: 1-methoxy-2-propanol

(Polymerization rate)
^1H -NMR was measured (solvent: _CDCl3 , internal standard: TMS) using a nuclear magnetic resonance (NMR) measurement device (Bruker Biospin, model: AVANCE500 (frequency 500 MHz)). The integral ratio of the peak derived from the monomer to the peak derived from the polymer was obtained for the obtained NMR spectrum, and the polymerization rate of the monomer was calculated.

(Weight average molecular weight (Mw) and molecular weight distribution (PDI))
The molecular weight was determined by gel permeation chromatography (GPC) using a high performance liquid chromatograph (Tosoh, model HLC-8320). A column of SHODEX KF-603 (φ6 mm×150 mm) (SHODEX) was used, and a lithium bromide (10 mmol/L)-acetic acid (10 mmol/L)-methylpyrrolidone solution was used as the mobile phase, and a differential refractometer was used as the detector. The measurement conditions were a column temperature of 40° C., a sample concentration of 20 mg/mL, a sample injection amount of 10 μm, and a flow rate of 0.2 mL/min. A calibration curve was created using polystyrene (molecular weights 70,500, 37,900, 19,920, 10,200, 4,290, 2,630, and 1,150) as a standard substance, and the weight average molecular weight (Mw) and number average molecular weight (Mn) were measured. From the measured values, the molecular weight distribution (PDI=Mw/Mn) was calculated.

(Amine value)
The amine value represents the mass of potassium hydroxide (KOH) equivalent to the basic component per 1 g of solid content. The measurement sample was dissolved in tetrahydrofuran, and the obtained solution was neutralized with a hydrochloric acid (0.1 mol/L)-propanol solution using a potentiometric titrator (product name: GT-06, manufactured by Mitsubishi Chemical Corporation). The amine value (B) was calculated by the following formula, with the inflection point of the titration pH curve being the titration end point.
B=56.11×Vs×0.1×f/w
B: Amine value (mg KOH / g)
Vs: Amount (mL) of hydrochloric acid (0.1 mol/L)-propanol solution required for titration
f: Potency of hydrochloric acid (0.1 mol/L)-propanol solution w: Mass (g) of the measurement sample (solid content equivalent)

(Black evaluation)
The black paint was applied to a stainless steel plate using a bar coater (#20) and dried at 60° C. for 10 minutes to form a coating film, and a test specimen was prepared.
The L value of the coating film-formed surface of the obtained test piece was measured by removing regular reflected light using an L value measuring device (Model CM-2600d, manufactured by Konica Minolta Japan, Inc.) Evaluation was performed on the black paint immediately after preparation and on the black paint after being left at 35°C for 3 weeks after preparation.

(Microscopic Observation)
The black paint was applied to a stainless steel plate using a bar coater (#20) and dried at 60° C. for 10 minutes to form a coating film, and a test specimen was prepared.
The coating surfaces of the obtained test pieces were observed under a microscope, and those where no aggregation was observed were rated as "O", those where slight aggregation was observed were rated as "Δ", and those where aggregation was observed were rated as "X".

<Synthesis of block copolymer>
(Block Copolymer No. 1)
In a flask equipped with an argon gas inlet tube and a stirrer, 9.0 g of BA, 18.0 g of M9EGA, 0.05 g of AIBN, and 6.8 g of PMA were charged, and after replacing with nitrogen, 0.45 g of BTEE was added and reacted at 60° C. for 48 hours to polymerize the A block. The polymerization rate was 100%.

A mixture of 5.0 g of CHA, 7.1 g of DMAEMA, 0.05 g of AIBN, and 3.0 g of PMA, which had been previously purged with argon, was added to the reaction solution, and the mixture was reacted at 60°C for 55 hours to polymerize the B block. The polymerization rate was 93%.

After the reaction was completed, the reaction solution was poured into stirred n-heptane. The precipitated polymer was filtered by suction and dried to obtain block copolymer No. 1. The resulting block copolymer No. 1 had an Mw of 24,880, a PDI of 1.48, and an amine value of 68 mgKOH/g.

(Block Copolymers No. 2 to 6)
Block copolymers No. 2 to 6 were produced in the same manner as in the production of block copolymer No. 1. Table 1 shows the monomers, organotellurium compounds, azo-based polymerization initiators, solvents, reaction conditions, and polymerization rates used. Table 2 also shows the composition, Mw, PDI, and amine value of each block copolymer. The content of each structural unit in the copolymer was calculated from the charge ratio and polymerization rate of the monomers used in the polymerization reaction.

(Black paint No. 1 to 6)
Black paints were prepared using the block copolymers No. 1 to 6 obtained above as dispersants. Specifically, each component was added to a 50 mL mayonnaise bottle so as to obtain the composition shown in Table 3, and 66 g of zirconia beads (φ0.3 mm) was added, and the mixture was stirred for 5 hours using a dispersing machine (SKANDEX DISPERSER BA-S20, manufactured by O-Well). After stirring, the beads were filtered off to obtain a pigment dispersion. Black paints No. 1 to 6 were prepared by mixing the obtained pigment dispersion with a clear paint. It was visually confirmed that the dispersibility of carbon black was good for the obtained black paints No. 1 to 6.

黒色顔料１：商品名「ＥＭＰＥＲＯＲ（登録商標）２０００」、キャボットコーポレーション社製、カーボンブラック、ｐＨ６～９
消泡剤：商品名「ＢＹＫ－０２４」、ビックケミー社製、シリコーン系界面活性剤
アクリル樹脂：商品名「ウォーターゾール（登録商標）ＡＣＤ－２００１」、ＤＩＣ社製、不揮発分；４０質量％、溶媒；水、プロピレングリコール－ｎ－ブチルエーテル
メラミン樹脂：商品名「サイメル（登録商標）３０３ＬＦ」、ａｌｌｎｅｘ社製、メチル化メラミン樹脂、不揮発分；１００質量％

Black pigment 1: Trade name "EMPEROR (registered trademark) 2000", manufactured by Cabot Corporation, carbon black, pH 6 to 9
Defoaming agent: trade name "BYK-024", manufactured by BYK-Chemie, silicone-based surfactant Acrylic resin: trade name "WATERSOL (registered trademark) ACD-2001", manufactured by DIC Corporation, non-volatile content; 40 mass%, solvent; water, propylene glycol-n-butyl ether Melamine resin: trade name "CYMEL (registered trademark) 303LF", manufactured by Allnex, methylated melamine resin, non-volatile content; 100 mass%

(Black paint No. 7-9)
Pigment dispersions were prepared using the block copolymers No. 2 to 4 obtained above as dispersants. Specifically, each component was added to a 50 mL mayonnaise bottle so as to obtain the composition shown in Table 4, and 66 g of zirconia beads (φ0.3 mm) was further added, followed by stirring for 5 hours using a dispersing machine (SKANDEX DISPERSER BA-S20, manufactured by O-Well). After stirring was completed, the beads were filtered off to prepare black paints No. 7 to 9. It was visually confirmed that the dispersibility of carbon nanotubes was good for the obtained black paints No. 7 to 9.

黒色顔料２：商品名「Ｎａｎｏｃｙｌ７０００」、ＮＡＮＯＣＯＹＬ社製、多層カーボンナノチューブ
消泡剤：商品名「ＢＹＫ－０２４」、ビックケミー社製、シリコーン系界面活性剤

Black pigment 2: Product name "Nanocyl 7000", manufactured by NANOCOYL, multi-walled carbon nanotubes Defoaming agent: Product name "BYK-024", manufactured by BYK-Chemie, silicone surfactant

Block copolymers No. 1 to 5 have an A block containing a structural unit represented by formula (1) and a B block containing a structural unit represented by formula (3) and a structural unit having a basic group. Black paints No. 1 to 5 containing these block copolymers No. 1 to 5 had low L values for the coating films produced both immediately after preparation and after storage for 3 weeks.
Furthermore, black paints No. 7 to 9 prepared using block copolymers No. 2 to 4 also had excellent dispersion performance for carbon nanotubes (carbon particles). Since block copolymer No. 1 has a similar structure to block copolymer No. 2, it is believed that block copolymer No. 1 also has high dispersion performance for carbon nanotubes (carbon particles).

Block copolymer No. 6 does not have a B block containing the structural unit represented by formula (3). The black paint using this block copolymer No. 6 had a high L value for the coating film both immediately after preparation and after storage for three weeks.

The coloring composition of the present invention is useful for automotive paints, etc., because the coating film formed has a high jet black color.

Claims (14)

Contains a black colorant, a dispersant, and an aqueous dispersion medium,
The coloring composition, characterized in that the dispersant contains a block copolymer having an A block containing a structural unit represented by formula (1) and a B block containing a structural unit represented by formula (3) and a structural unit having a basic group.

[In formula (1), n1 represents an integer of 2 to 30. R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R ¹² represents an alkylene group having 1 to 3 carbon atoms. R ¹³ represents a hydrogen atom or a methyl group. Note that a plurality of R ¹² 's may be the same or different.]

[In formula (3), R ³¹ represents an alicyclic hydrocarbon group. Z ³ represents O or NH. R ³² represents a hydrogen atom or a methyl group.] The coloring composition according to claim 1, wherein the content of the structural unit represented by the formula (1) is 20% by mass to 95% by mass in 100% by mass of the A block. The coloring composition according to claim 1 or 2, wherein the content of the structural unit represented by formula (3) is 15% by mass to 80% by mass in 100% by mass of the B block. The coloring composition according to any one of claims 1 to 3, wherein in the B block, the mass ratio of the structural unit represented by formula (3) to the structural unit having a basic group (structural unit represented by formula (3)/structural unit having a basic group) is 0.15 to 4.0. The colored composition according to any one of claims 1 to 4, wherein the A block further contains a structural unit represented by formula (2).

[In formula (2), R ²¹ represents a chain hydrocarbon group which may have a substituent. R ²² represents a hydrogen atom or a methyl group.] The coloring composition according to any one of claims 1 to 5, wherein the amine value of the block copolymer is 10 mg KOH/g to 200 mg KOH/g. The colored composition according to any one of claims 1 to 6, wherein the structural unit having a basic group is a structural unit represented by formula (4):

[In formula (4), R ⁴¹ and R ⁴² each independently represent a chain or cyclic hydrocarbon group which may have a substituent. ^{R 41} and R ⁴² may be bonded to each other to form a cyclic structure. R ⁴³ represents a divalent hydrocarbon group. Z ⁴ represents O or NH. R ⁴⁴ represents a hydrogen atom or a methyl group.] The coloring composition according to any one of claims 1 to 7, wherein the mass ratio of the A block to the B block in the block copolymer (A block/B block) is 50/50 to 95/5. The coloring composition according to any one of claims 1 to 8, wherein the molecular weight distribution (PDI) of the block copolymer is 2.5 or less. The coloring composition according to any one of claims 1 to 9, wherein the weight average molecular weight (Mw) of the block copolymer is 3,000 to 40,000. The coloring composition according to any one of claims 1 to 10, wherein the block copolymer is polymerized by living radical polymerization. The coloring composition according to claim 11, further comprising a coating film-forming resin. The coloring composition according to claim 12, which is an automotive coating composition. A coating film formed from the coloring composition according to any one of claims 1 to 13.