Block copolymer, dispersant, and coloring composition

Abstract

To provide a block copolymer that can be used as a dispersant for an aqueous coating, the block copolymer allowing improved dispersion of a coloring material.SOLUTION: A block copolymer has an A block containing a constitutional unit represented by formula (1) and a B block containing a constitutional unit represented by formula (3).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a block copolymer, and particularly to a block copolymer that can be used as a dispersant for a colorant in a coloring composition.

Background Art

[0002] In recent years, from the viewpoint of preventing air pollution, it has been required to reduce the emissions of volatile organic compounds (VOCs) from factories and business establishments. Therefore, regarding the paints used for coating metal plates constituting vehicle bodies such as automobiles, a switch to water-based paints is being considered. In addition, in automotive paints, not only film properties such as high durability, acid resistance, car wash scratch resistance, and chipping resistance are required, but also the finish appearance of the film such as transparency and color development is required more than ever.

[0003] The colorants used in paints generally have a hydrophobic surface. In addition, the dispersants used in solvent-based colored paints have low solubility in water and are inferior in dispersion stability in an aqueous dispersion medium. In particular, carbon particles such as carbon black used as black colorants have a small primary particle diameter and a very large specific surface area, so the cohesive force is very strong. Therefore, it is difficult to uniformly disperse carbon particles in an aqueous dispersion medium, and there is also a problem that they aggregate even if dispersed.

[0004] Therefore, in paints using carbon black as a black colorant, techniques for improving the dispersibility of carbon black have been proposed. For example, in Patent Document 1, the DBP oil absorption amount is 150 ml / 100 g or less, the average primary particle diameter is 15 nm or less, and the specific surface area is 500 m 2A highly jet-black carbon black dispersion in which carbon black contained in an amount of / g or less and in a region having an acidic to neutral pH is finely dispersed in an aqueous medium by a dispersant (sometimes referred to as jet blackness particularly when the coloring material is a black coloring material among coloring properties) is described. In this 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)).

[0005] Further, Patent Document 2 describes an aqueous coating composition containing (A) a copolymer of (a) a polymerizable unsaturated monomer having a specific cationic functional group, (b) a polymerizable unsaturated monomer having a polyoxyalkylene chain, and (c) other polymerizable unsaturated monomers, (B) a pigment, and (C) an acrylic resin containing an acid group and a hydroxyl group (see Patent Document 1 (Claim 1, Paragraph 0014)).

[0006] On the other hand, regarding jet blackness, since carbon black is a reddish-black color, a method of enhancing jet blackness by adding a blue coloring material (blueing agent) such as a phthalocyanine-based pigment is known.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] In an aqueous paint using carbon particles as a black coloring material, a paint with improved dispersibility of carbon particles has been proposed, but there is still room for improvement in preventing aggregation of carbon particles. Also, improvement in the dispersibility of a blue coloring material (particularly a phthalocyanine-based pigment) using the same dispersant is also required.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a block copolymer that can be used as a dispersant for aqueous paints and has high dispersibility for coloring materials (particularly carbon particles and blue coloring materials). Another object is to provide a block copolymer that can improve the jet blackness of a coating film when used as a dispersant for a coloring composition containing carbon particles, and can improve the transparency and chroma of a coating film when used as a dispersant for a coloring composition containing a blue coloring material.

Means for Solving the Problems

[0010] The block copolymer of the present invention that has solved the above problems is characterized by having an A block containing a structural unit represented by formula (1) and a B block containing a structural unit represented by formula (3).

[0011]

Chemical formula

[0012]

Chemical formula

[0013] In the block copolymer of the present invention, the structural unit represented by the formula (1) contained in the A block has a high affinity for the aqueous dispersion medium, and the structural unit represented by the formula (3) contained in the B block adsorbs to the colorant. Therefore, the block copolymer can improve the dispersibility of the colorant by being used as a dispersant for the colorant in an aqueous coloring composition containing an aqueous dispersion medium and a colorant.

Advantages of the Invention

[0014] The block copolymer of the present invention can be used as a dispersant for aqueous paints, and is particularly excellent in the dispersion performance of carbon particles and blue pigments. By using the block copolymer of the present invention as a dispersant for a coloring composition containing carbon particles (black colorant), the jet blackness of the coating film can be improved. Further, by using the block copolymer of the present invention as a dispersant for a coloring composition containing a blue colorant, the transparency and chroma of the coating film can be improved.

[0015] Furthermore, since the block copolymer of the present invention is excellent in the dispersibility of both carbon particles and blue colorants, it can be suitably used for an aqueous coloring composition containing carbon particles (black colorant) and a blue colorant (bluing agent), and an aqueous coloring composition having excellent jet blackness can also be obtained.

Embodiments for Carrying Out the Invention

[0016] <Block Copolymer> The block copolymer of the present invention is characterized by having an A block containing a structural unit represented by the formula (1) and a B block containing a structural unit represented by the formula (3).

[0017] The block copolymer contains an A block containing a structural unit represented by the formula (1) having a high affinity for the aqueous dispersion medium. Further, the B block contains a structural unit represented by the formula (3) having a portion that adsorbs to the colorant. By using the block copolymer as a dispersant for an aqueous coloring composition containing a colorant, the dispersibility of the colorant can be improved.

[0018] Hereinafter, an example of a preferred embodiment in which the present invention is implemented will be described. However, the following embodiments are merely illustrative. The present invention is not limited to the following embodiments at all.

[0019] 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, the "vinyl monomer" refers to a monomer having a carbon-carbon double bond capable of radical polymerization in the molecule. The "structural unit derived from a vinyl monomer" refers to a structural unit in which the carbon-carbon double bond capable of radical polymerization of the vinyl monomer has polymerized to form a carbon-carbon single bond. "(Meth)acryl" 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".

[0020] (A block) The A block is a block containing a structural unit represented by formula (1). The structural unit represented by formula (1) in the A block may be only one kind or may have two or more kinds.

[0021] [Chemical formula] [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. In addition, a plurality of R 12 may be the same or different from each other.]

[0022] n1 in formula (1) is 2 or more, preferably 5 or more, 30 or less, preferably 20 or less, more preferably 15 or less, and still more preferably 10 or less.

[0023] R 11 The alkyl group having 1 to 3 carbon atoms represented by is either linear or branched, but a linear one is preferred. The above R 11 Specific examples of the alkyl group having 1 to 3 carbon atoms represented by include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

[0024] R 12 The alkylene group having 1 to 3 carbon atoms represented by is either linear or branched, but a linear one is preferred. The above R 12 Specific examples of the alkylene group having 1 to 3 carbon atoms represented by 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.

[0025] Examples of the monomer constituting the structural unit represented by formula (1) include (meth)acrylates having a polyalkylene glycol structure. The polyalkylene glycol moiety may be, for example, a mixture of ethylene oxide and propylene oxide. Examples of the (meth)acrylate having a polyalkylene glycol structure include (meth)acrylates having a polyethylene glycol structure such as polyethylene glycol (degree of polymerization = 2 to 30) methyl ether (meth)acrylate, polyethylene glycol (degree of polymerization = 2 to 30) ethyl ether (meth)acrylate, and polyethylene glycol (degree of polymerization = 2 to 30) propyl ether (meth)acrylate; (meth)acrylates having a polypropylene glycol structure such as polypropylene glycol (degree of polymerization = 2 to 30) methyl ether (meth)acrylate, polypropylene glycol (degree of polymerization = 2 to 30) ethyl ether (meth)acrylate, and polypropylene glycol (degree of polymerization = 2 to 30) propyl ether (meth)acrylate.

[0026] The content rate of the structural unit represented by formula (1) is preferably 20% by mass or more, more preferably 35% by mass or more, still more preferably 50% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 80% by mass or less, in 100% by mass of the A block. If the content rate 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 resin for forming a coating film becomes better.

[0027] The A block preferably further contains a structural unit represented by formula (2). The structural unit represented by formula (2) in the A block may be only one kind or may have two or more kinds. By the A block having the structural unit represented by formula (2), the affinity with the resin for forming a coating film is further improved.

[0028]

Chemical formula

[0029] Examples of the linear hydrocarbon group represented by R 21 include a linear alkyl group, a branched alkyl group, etc. The number of carbon atoms of the linear alkyl group is preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, still more preferably 1 to 5 carbon atoms. Examples of the linear alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-hexyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-lauryl group, etc. The number of carbon atoms of the branched alkyl group is preferably 3 to 20 carbon atoms, more preferably 3 to 10 carbon atoms, still more preferably 3 to 5 carbon atoms. Examples of the branched alkyl group include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a 2-ethylhexyl group, a neopentyl group, an isooctyl group, etc.

[0030] Examples of the cyclic hydrocarbon group represented by R 21Examples of the substituent of the chain hydrocarbon group represented by include a halogen group, an alkoxy group, a benzoyl group (-COC6H5), a hydroxy group, and the like.

[0031] R 21 Examples of the cyclic hydrocarbon group represented by include a cyclic alkyl group and an aromatic group. 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, more preferably 6 to 12, and even more preferably 6 to 10. 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, more preferably 6 to 12, and even more preferably 6 to 8. Examples of the aromatic group include a phenyl group, a tolyl group, a xylyl group, and a mesityl group. Examples of the chain portion of the cyclic alkyl group having a chain portion and 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.

[0032] R 21 Examples of the substituent of the cyclic hydrocarbon group represented by include a halogen group, an alkoxy group, a chain alkyl group, a hydroxy group, and the like.

[0033] Examples of the vinyl monomer that forms the structural unit represented by formula (2) include (meth)acrylate having a chain alkyl group (linear alkyl group or branched alkyl group), (meth)acrylate having a cyclic alkyl group, (meth)acrylate having a polycyclic structure, and (meth)acrylate having an aromatic group. Among these, (meth)acrylate having a chain alkyl group (linear alkyl group or branched alkyl group) and (meth)acrylate having a cyclic alkyl group are preferred.

[0034] 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, n-stearyl (meth)acrylate, and the like.

[0035] 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, isodecyl (meth)acrylate, and the like.

[0036] Examples of the cyclic alkyl group include a cyclic alkyl group having a monocyclic structure (for example, a cycloalkyl group). Specific examples of the (meth)acrylate having a cyclic alkyl group with a monocyclic structure include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, and the like.

[0037] Examples of the polycyclic structure include a cyclic alkyl group having a bridged ring structure (for example, an adamantyl group, a norbornyl group, an isobornyl group). Specific examples of the (meth)acrylate having a polycyclic structure include isobornyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, dicyclopentanyl oxyethyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, and the like.

[0038] Examples of the aromatic group include aryl groups, etc., and may also have a chain portion such as an alkylaryl group, an aralkyl group, an aryloxyalkyl group, etc. Specific examples of the (meth)acrylate having an aromatic group include benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc.

[0039] When containing the structural unit represented by formula (2), its content is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, in 100% by mass of the A block, and preferably 80% by mass or less, more preferably 65% by mass or less, still more preferably 50% by mass or less. If the content is 5% by mass or more, the affinity with the resin for film formation is further improved, and if it is 80% by mass or less, the affinity with the aqueous dispersion medium becomes better.

[0040] The A block may be only the structural unit represented by formula (1), or 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, still more preferably 90% by mass or more.

[0041] Specific examples of the vinyl monomer capable of forming other structural units of the A block include (meth)acrylate having a hydroxy group, (meth)acrylate having a lactone-modified hydroxy group, (meth)acrylate having an alkoxy group, (meth)acrylate having an acidic group, (meth)acrylic acid, etc.

[0042] Examples of the (meth)acrylate 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, 12-hydroxylauryl (meth)acrylate, and the like. Among these, the (meth)acrylate having a hydroxyalkyl group with 1 to 5 carbon atoms is more preferable.

[0043] Examples of the (meth)acrylate having a lactone-modified hydroxy group include those obtained by adding lactone to the (meth)acrylate having a hydroxy group, and those obtained by adding caprolactone are preferable. The addition amount of caprolactone is preferably 1 mol to 20 mol, and more preferably 1 mol to 10 mol. Examples of the (meth)acrylate having a lactone-modified hydroxy group include 2-hydroxyethyl (meth)acrylate with 1 mol of caprolactone added, 2-hydroxyethyl (meth)acrylate with 2 mol of caprolactone added, 2-hydroxyethyl (meth)acrylate with 3 mol of caprolactone added, 2-hydroxyethyl (meth)acrylate with 4 mol of caprolactone added, 2-hydroxyethyl (meth)acrylate with 5 mol of caprolactone added, 2-hydroxyethyl (meth)acrylate with 10 mol of caprolactone added, and the like.

[0044] Examples of the (meth)acrylate having an alkoxy group include methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and the like.

[0045] Examples of the acidic group include a carboxy group (-COOH), a sulfonic acid group (-SO3H), a phosphoric acid group (-OPO3H2), a phosphonic acid group (-PO3H2), and a phosphinic acid group (-PO2H2). Examples of the (meth)acrylate having the 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.

[0046] Examples of the (meth)acrylate having a carboxy group include monomers obtained by reacting an acid anhydride such as maleic anhydride, succinic anhydride, or phthalic anhydride with a (meth)acrylate having a hydroxy group such as carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, or 2-(meth)acryloyloxyethyl phthalate. Examples of the (meth)acrylate having a phosphoric acid group include 2-(phosphonooxy)ethyl (meth)acrylate. Examples of the (meth)acrylate having a sulfonic acid group include ethyl sulfonate (meth)acrylate.

[0047] The content of the structural unit represented by the above formula (3) in the A block is preferably 3% by mass or less, more preferably 1% by mass or less, still more preferably 0.1% by mass or less, and particularly preferably does not contain the structural unit represented by formula (3).

[0048] 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 any form such as random copolymerization or block copolymerization in the A block, and are preferably contained in the form of random copolymerization from the viewpoint of uniformity. For example, the A block may be formed of a copolymer of a structural unit composed of an a1 block and a structural unit composed of an a2 block.

[0049] (B block) The B block is a block containing a structural unit represented by the formula (3). The structural unit represented by the formula (3) in the B block may be only one kind or may have two or more kinds.

[0050]

Chemical formula

[0051] In the formula (3), examples of the divalent linking group X include a -CO- group (carbonyl group) and a -COO-R 32 - group (ester group), and preferably a -CO- group. The bonding direction of the ester group is not particularly limited, but as the bonding mode, a C-CO-O-R 32 - morpholino group is preferred.

[0052] The above-mentioned R 32 is a single bond or an alkylene group having 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 3), and more preferably a single bond. Specific examples of the alkylene group having 1 to 10 carbon atoms include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, etc.

[0053] Examples of the (meth)acrylic monomer capable of forming the structural unit represented by the formula (3) include 4-(meth)acryloylmorpholine, morpholin-4-yl (meth)acrylate, N-((meth)acrylamidomethyl)morpholine, 2-(4-morpholinyl)ethyl (meth)acrylate, etc. Among these, 4-(meth)acryloylmorpholine is preferred, and 4-acryloylmorpholine is more preferred.

[0054] The content ratio of the structural unit represented by the formula (3) is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, particularly preferably 50% by mass or more, in 100% by mass of the B block, and preferably 100% by mass or less, more preferably 95% by mass or less, still more preferably 90% by mass or less. If the content ratio is 20% by mass or more, aggregation of the coloring material can be suppressed, and an excellent coating film can be formed.

[0055] The B block may consist only of the structural unit represented by the formula (3), or may contain other structural units.

[0056] Specific examples of the vinyl monomer capable of forming other structural units of the B block include, in addition to those exemplified as specific examples of the monomer capable of forming other structural units of the A block, vinyl monomers having a basic group, vinyl monomers having a cyclic N-alkenyl lactam structure, and the like.

[0057] As the basic group, an amino group is preferable in view of easy availability of raw materials and ease of synthesis. The amino group in this specification includes, in addition to the structure of a general amino group (-NH2), -NHR in which H is substituted by a hydrocarbon group, 41 , -NR 41 R 42 (R 41 , R 42 each independently represents a linear or cyclic hydrocarbon group. Also, R 41 and R 42 may be bonded to each other to form a cyclic structure.) and a nitrogen-containing heterocyclic group (such as a pyridyl group and an imidazole group).

[0058] Specific examples of the vinyl monomer having a basic group 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, dimethylaminopropyl (meth) acrylamide, 1 - vinylimidazole, 2 - vinylpyridine, 4 - vinylpyridine, and the like.

[0059] When the B block has a structural unit derived from a vinyl monomer having a basic group, its content is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, still more preferably 65% by mass or less in 100% by mass of the B block.

[0060] Examples of the vinyl monomer having a cyclic N - alkenyl lactam structure include the structural unit represented by the formula (4).

[0061]

Chemical formula

[0062] Examples of vinyl monomers having a cyclic N-alkenyl lactam structure include vinyl monomers having a 5-membered lactam structure such as N-vinylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-5-ethylpyrrolidone, N-vinyl-5-propylpyrrolidone, N-vinyl-5-butylpyrrolidone, 1-(2-propenyl)-2-pyrrolidone, etc.; vinyl monomers having a 6-membered lactam structure such as N-vinylpiperidone; vinyl monomers having a 7-membered lactam structure such as N-vinylcaprolactam, etc. Vinyl monomers having a cyclic N-alkenyl lactam structure can be used alone or in combination of two or more. Among these, vinyl monomers having a 5-membered lactam structure are preferred, and N-vinylpyrrolidone is more preferred.

[0063] When the B block has a structural unit derived from a vinyl monomer having a cyclic N-alkenyl lactam structure, its content is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, still more preferably 65% by mass or less in 100% by mass of the B block.

[0064] The content of the structural unit represented by the above (1) in the B block is preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 6% by mass or less, and it is particularly preferable that the B block does not contain the structural unit represented by formula (1).

[0065] When two or more structural units are contained in the B block, the various structural units contained in the B block may be contained in any form such as random copolymerization or block copolymerization in the B block, and it is preferably contained in the form of random copolymerization from the viewpoint of uniformity. For example, the B block may be formed of a copolymer of a structural unit composed of a b1 block and a structural unit composed of a b2 block.

[0066] (Block copolymer) The structure of the block copolymer is preferably a linear block copolymer. Also, the linear block copolymer may have any structure (arrangement), but from the perspective 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, (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), and it is preferably a copolymer having at least one structure selected from the group consisting of. Among these, from the perspective of handleability during processing and the physical properties of the composition, an A-B type diblock copolymer is preferable. By constituting an A-B type diblock copolymer, the structural unit represented by formula (1) is localized in the A block, and the structural unit represented by formula (3) is localized in the B block, and it is considered that they can preferably act on the pigment and the dispersion medium (solvent) efficiently. The block copolymer may have other blocks other than the A block and the B block.

[0067] The content of the A block is preferably 50% by mass or more, more preferably 55% by mass or more, still more preferably 60% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 80% by mass or less in 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, still more preferably 15% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less in 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.

[0068] The mass ratio of block A to block B in the block copolymer (A block / B block) is preferably 50 / 50 or more, more preferably 55 / 45 or more, still more preferably 60 / 40 or more, and preferably 95 / 5 or less, more preferably 90 / 10 or less, still more preferably 80 / 20 or less. If the mass ratio of block A to block B is within the above range, the dispersion performance when used as a dispersant will be further improved.

[0069] The content of the structural unit represented by formula (1) is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, particularly preferably 40% by mass or more, and preferably 90% by mass or less, more preferably 85% by mass or less, still more preferably 80% by mass or less in 100% by mass of the entire block copolymer.

[0070] The content of the structural unit represented by formula (3) is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less, particularly preferably 30% by mass or less in 100% by mass of the entire block copolymer.

[0071] 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, still more preferably 7,000 or more, particularly preferably 10,000 or more, and preferably 40,000 or less, more preferably 35,000 or less, still 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.

[0072] 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 1.6 or less. In the present invention, the molecular weight distribution (PDI) is determined 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, and the more uniform the molecular weight of the copolymer. When the value is 1.0, the molecular weight distribution is the narrowest. That is, the lower limit value of PDI is 1.0. When the molecular weight distribution (PDI) of the block copolymer exceeds 2.5, it will contain components with a small molecular weight or a large molecular weight.

[0073] When the B block does not contain a structural unit derived from a vinyl monomer having a basic group, the amine value of the block copolymer is preferably 10 mgKOH / g or less, more preferably 1 mgKOH / g or less, and even more preferably 0.1 mgKOH / g or less. It is preferable that the block copolymer substantially has no amine value (amine value is 0 mgKOH / g).

[0074] When the B block contains a structural unit derived from a vinyl monomer having a basic group, 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 preferably 200 mgKOH / g or less, more preferably 150 mgKOH / g or less, and even more preferably 100 mgKOH / g or less.

[0075] (Method for producing block copolymer) Examples of the method for producing the block copolymer include a method of first producing the A block by a polymerization reaction of vinyl monomers and then polymerizing the monomers of the B block on the A block; a method of first producing the B block and then polymerizing the monomers of the A block on the B block; a method of separately producing the A block and the B block and then coupling the A block and the B block.

[0076] The coincidence method is not particularly limited, but living radical polymerization is preferred. That is, as the block copolymer, those polymerized by living radical polymerization are preferred. The living radical polymerization method maintains the simplicity and versatility of the conventional radical polymerization method, while side reactions such as termination reactions and chain transfer are less likely to occur, and the growth end grows without being hindered by side reactions that deactivate it. Therefore, it is preferred in terms of precise control of the molecular weight distribution and easy production of polymers with a uniform composition.

[0077] Living radical polymerization methods include methods using transition metal catalysts (ATRP method) depending on the difference in the method of stabilizing the polymerization growth end; methods using sulfur-based reversible chain transfer agents (RAFT method); methods using organic tellurium compounds (TERP method), etc. Among these methods, from the viewpoints of the variety of monomers that can be used, molecular weight control in the polymer region, uniform composition, or coloring, it is preferable to use the TERP method.

[0078] The TERP method is a method of polymerizing a radically polymerizable compound (vinyl monomer) using an organic tellurium compound as a chain transfer agent, for example, the methods described in International Publication No. 2004 / 14848, International Publication No. 2004 / 14962, International Publication No. 2004 / 072126, and International Publication No. 2004 / 096870.

[0079] Specific polymerization methods of the TERP method include the following (a) to (d). (a) A method of polymerizing a vinyl monomer using an organic tellurium compound represented by the formula (6). (b) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by the formula (6) and an azo-based polymerization initiator. (c) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by the formula (6) and an organic ditelluride compound represented by the formula (7). (d) A method of polymerizing a vinyl monomer using a mixture of an organic tellurium compound represented by the formula (6), an azo-based polymerization initiator, and an organic ditelluride compound represented by the formula (7).

[0080] [Chemical formula] [In general formula (6), R 61 represents an alkyl group, aryl group or aromatic heterocyclic group having 1 to 8 carbon atoms. 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, aryl group, substituted aryl group, aromatic heterocyclic group, alkoxy group, acyl group, amide group, oxycarbonyl group, cyano group, allyl group or propargyl group having 1 to 8 carbon atoms. [In general formula (7), R 61 represents an alkyl group, aryl group or aromatic heterocyclic group having 1 to 8 carbon atoms.]

[0081] Specific examples of the organic tellurium compound represented by general formula (6) include ethyl-2-methyl-2-n-butyltellanyl-propionate, ethyl-2-n-butyltellanyl-propionate, (2-hydroxyethyl)-2-methyl-methyltellanyl-propionate, etc., and the organic tellurium compounds described in International Publication No. 2004 / 14848, International Publication No. 2004 / 14962, International Publication No. 2004 / 072126, and International Publication No. 2004 / 096870. Specific examples of the organic ditelluride compound represented by general formula (7) include dimethylditelluride, dibutylditelluride, etc. The azo-based polymerization initiator can be used without particular limitation as long as it is an azo-based polymerization initiator used in ordinary radical polymerization. For example, 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. can be mentioned.

[0082] The polymerization process is carried out in a container replaced with an inert gas. Vinyl monomer, an organic tellurium compound of general formula (6), and depending on the type of vinyl monomer, for the purposes of promoting reaction, controlling molecular weight and molecular weight distribution, etc., an azo-based polymerization initiator and / or an organic ditelluride compound of general formula (7) are further mixed. At this time, examples of the inert gas include nitrogen, argon, helium, etc. Preferably, argon and nitrogen are good. The usage amount of the vinyl monomer in the above (a), (b), (c) and (d) may be appropriately adjusted according to the physical properties of the target copolymer.

[0083] The polymerization reaction can be carried out without a solvent, but it may also be carried out by using an aprotic solvent or a protic solvent commonly used in radical polymerization and stirring the above mixture. Examples of the aprotic solvent that can be used include anisole, benzene, toluene, propylene glycol monomethyl ether acetate, ethyl acetate, tetrahydrofuran (THF), etc. Examples of the protic solvent include water, methanol, 1-methoxy-2-propanol, etc. The solvent may be used alone or in combination of two or more. The usage amount of the solvent may be appropriately adjusted. For example, 0.01 ml to 50 ml is preferable with respect to 1 g of the vinyl monomer. The reaction temperature and reaction time may be appropriately adjusted according to the molecular weight or molecular weight distribution of the obtained copolymer, but usually, it is stirred at 0 °C to 150 °C for 1 minute to 100 hours. After the completion of the polymerization reaction, from the obtained reaction mixture, the used solvent, residual vinyl monomer, etc. can be removed by ordinary separation and purification means, and the target copolymer can be separated.

[0084] The growth end of the copolymer obtained by the polymerization reaction is -TeR derived from the tellurium compound 61 (wherein, R 61It has the same form as described above), and it is deactivated by operations in air after the polymerization reaction, but tellurium atoms may remain. Since the copolymer with tellurium atoms remaining at the ends may be colored or have poor thermal stability, it is preferable to remove the tellurium atoms. Methods for removing tellurium atoms include radical reduction methods; methods of adsorbing with activated carbon or the like; methods of adsorbing metals with ion exchange resins or the like, and these methods can also be used in combination. In addition, the other end (the end opposite to the growing end) of the copolymer obtained by the polymerization reaction is -CR derived from the tellurium compound 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).).

[0085] <Dispersant> The dispersant of the present invention contains the block copolymer. The dispersant contains the block copolymer as a main component (50% by mass or more), preferably contains 75% by mass or more of the block copolymer, and more preferably is composed only of the block copolymer.

[0086] In addition, the dispersant has particularly high dispersibility with respect to carbon black, which is a black coloring material, and can suppress aggregation. Further, the dispersant exhibits excellent dispersibility with respect to carbon particles such as carbon nanotubes and graphene, similar to carbon black. Therefore, the dispersant of the present invention can also be suitably used as a dispersant for carbon particles and can also be used in conductive compositions.

[0087] The dispersant can facilitate the dispersion of the coloring material by being kept as a dispersant solution before preparing the coloring composition. As the solvent used in the dispersant solution, a solvent that can dissolve the dispersant, does not react with these components, and has appropriate volatility is preferred. Examples of the solvent include the dispersion medium used in the coloring composition described later. 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. Also, considering the viscosity suitable for the production of the coloring composition described later, the lower limit of the content of the dispersion medium in the dispersant solution is usually 10% by mass, and preferably 30% by mass.

[0088] <Coloring composition> The coloring composition of the present invention contains a dispersant (block copolymer), a coloring material, and an aqueous dispersion medium.

[0089] (Coloring material) The coloring material is not particularly limited, and pigments and dyes conventionally used as coloring materials for paints can be used, but pigments are preferred from the viewpoints of light resistance and heat resistance. Examples of the pigments include pigments of various colors such as red pigments, yellow pigments, orange pigments, blue pigments, green pigments, purple pigments, and black pigments. The structures of the pigments include azo pigments such as monoazo pigments, diazo pigments, and condensed diazo pigments, diketopyrrolopyrrole pigments, phthalocyanine pigments, isoindolinone pigments, isoindoline pigments, quinacridone pigments, indigo pigments, thioindigo pigments, quinophthalone pigments, dioxazine pigments, anthraquinone pigments, perylene pigments, perinone pigments, etc. organic pigments; carbon black, graphite, titanium black, and inorganic pigments such as metal oxides, composite oxides, metal sulfides, metal sulfates, and metal carbonates of copper, iron, manganese, cobalt, chromium, nickel, zinc, calcium, silver, etc. The pigment contained in the coloring composition may be only one type or a plurality of types.

[0090] Since the block copolymer exhibits excellent dispersion performance particularly with respect to black pigments and blue pigments, it is preferable that at least one of the colorants is selected from the group consisting of black pigments and blue pigments.

[0091] Examples of the black pigment include carbon blacks such as furnace black, channel black, acetylene black, thermal black, lamp black, bone black; carbon nanotubes; carbon nanofibers; fullerenes; natural graphite; graphite; perylene-based pigments; lactam-based pigments; titanium black; metal oxides such as copper, iron, manganese, cobalt, chromium, nickel, zinc, calcium, silver; composite oxides; metal sulfides; metal sulfates; metal carbonates, etc. Preferably, it is at least one kind of carbon particles selected from the group consisting of carbon black and carbon nanotubes.

[0092] The primary particle diameter 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, more preferably 400 m 2 / g to 800 m 2 / g. The specific surface area is measured according to JIS K 6217-3 (2001).

[0093] The DBP (dibutyl phthalate) oil absorption amount of the carbon particles is preferably 50 ml / 100 g to 150 ml / 100 g, more preferably 80 ml / 100 g to 120 ml / 100 g. The DBP oil absorption amount is measured according to JIS K 6217-4 (2017).

[0094] The carbon particles may be surface-treated with oxidation. By performing the oxidation treatment, carboxyl groups and phenolic hydroxyl groups can be imparted to the surface of the carbon particles. The oxidation treatment can be carried out by treating the surface of the carbon particles with ozone, nitric acid, etc. The pH of the carbon particles having carboxyl groups and phenolic hydroxyl groups imparted to the surface becomes acidic.

[0095] The carbon particles preferably have a dispersion liquid pH of 3 to 9, more preferably 5 to 9, when 1 g of the carbon particles is dispersed in 100 ml of water (25°C).

[0096] Examples of the blue pigment include organic pigments mainly composed of organic compounds such as phthalocyanine-based pigments, anthraquinone-based pigments, and dioxazine-based pigments, and one or more of these can be mixed and used. Among these, phthalocyanine-based pigments are preferred, and metal phthalocyanine pigments and monohalogenated metal phthalocyanine pigments (halogenated metal phthalocyanine pigments having one halogen atom in the molecule) are more preferred. Note that polyhalogenated metal phthalocyanine pigments (halogenated metal phthalocyanine pigments having two or more halogen atoms in the molecule) are green pigments, so the phthalocyanine-based pigments used as blue pigments do not contain polyhalogenated metal phthalocyanine pigments.

[0097] As the phthalocyanine-based pigment, the compound represented by the general formula (8) is particularly preferred. Copper phthalocyanine pigments and monohalogenated copper phthalocyanine pigments have a transmission region in the short wavelength region, so a coloring layer with higher luminance can be formed.

[0098] [In Chemical Formula (8), R each independently represents a hydrogen atom or a halogen atom. However, the number of halogen atoms in R 8 is 0 or 1.] 8

[0099] R 8 is preferably all hydrogen atoms because it transmits light well in the short wavelength region and the effects of the present invention are easily obtained.

[0100] ​According to the compounds classified as pigments in the Color Index (C.I.) as cyan pigments, specifically, 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. can be mentioned. As phthalocyanine pigments, C.I. Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17, 17:1, 75 are preferred. 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, 17:1 are preferred. As anthraquinone pigments, C.I. Pigment Blue 60 is preferred. As dioxazine pigments, C.I. Pigment Blue 80 is preferred.

[0101] The number average particle diameter of the pigment may be appropriately selected according to its use and is not particularly limited. From the viewpoint of high brightness, the coloring composition preferably contains a pigment having a number average particle diameter of 10 nm to 150 nm.

[0102] The pigment may contain a dye derivative as a dispersion aid. This dye derivative is one in which a functional group is introduced into the dye skeleton. As the dye skeleton, a skeleton identical or similar to the coloring material constituting the coloring composition or a skeleton identical or similar to the compound serving as the raw material of the pigment is preferred. Specific examples of the dye skeleton include an azo-based dye skeleton, a phthalocyanine-based dye skeleton, an anthraquinone-based dye skeleton, a triazine-based dye skeleton, an acridine-based dye skeleton, a perylene-based dye skeleton, etc.

[0103] The amount of the dye derivative used is not particularly limited, but for example, it is preferably 4 parts by mass to 17 parts by mass with respect to 100 parts by mass of the pigment.

[0104] From the perspective of brightness, the upper limit of the content of the colorant in the coloring composition is usually 80% by mass, preferably 70% by mass, and more preferably 60% by mass in the total solid content of the coloring composition. Also, the lower limit of the content of the colorant in the coloring composition is usually 3% by mass, preferably 20% by mass, and more preferably 30% by mass in the total solid content of the coloring composition. Here, the solid content refers to components other than the dispersion medium described later.

[0105] The content of the dispersant with respect to the colorant in the coloring composition is preferably 5 to 200 parts by mass, more preferably 10 to 100 parts by mass, and even more preferably 10 to 80 parts by mass per 100 parts by mass of the colorant.

[0106] (Aqueous dispersion medium) Examples of the aqueous dispersion medium include water or an aqueous solvent (a solvent miscible with water). Specifically, 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; amides such as dimethylformaldehyde and dimethylacetamide, etc. Among these, alcohols and glycols are preferred. The aqueous solvent may be used alone or in combination of two or more.

[0107] The content of the aqueous dispersion medium in the coloring composition is not particularly limited and can be adjusted appropriately. 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, preferably 80% by mass, in consideration of the viscosity suitable for application of the coloring composition.

[0108] Depending on the application, the coloring composition may further contain additives such as a coating film-forming resin, 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 anti-foaming agent, and a crosslinking agent. Furthermore, 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 an electrode-forming resin, an electrode active material, a surfactant, a film-forming aid, a leveling agent, a preservative, an anti-mold agent, a viscosity adjuster, a pH adjuster, an anti-foaming agent, and a crosslinking agent.

[0109] (Resin for coating film formation) 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. There are no particular limitations on the film-forming resin, and those that are conventionally used in 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 resins can be used alone or in combination of two or more. When the film-forming resin is blended into the coloring composition, the content of the film-forming resin is preferably 60% to 95% by mass of the total solid content of the coloring composition.

[0110] (thermosetting resin, thermoplastic resin) Examples of the thermosetting resin and the thermoplastic resin include butyral resin, styrene-maleic acid copolymer, chlorinated polyethylene resin, chlorinated polypropylene resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, vinyl acetate resin, urethane resin, phenol resin, polyester resin, acrylic resin, alkyd resin, styrene resin, styrene acrylic resin, polyamide resin, rubber-based resin, cyclized rubber, epoxy resin, celluloses, polybutadiene, polyimide resin, benzoguanamine resin, melamine resin, urea resin, silicone resin, fluororesin, and the like.

[0111] (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, or an amino group via an isocyanate group, an aldehyde group, an epoxy group, or the like is used. A polymer obtained by half-esterifying a linear polymer containing an acid anhydride such as a styrene-maleic anhydride copolymer or an α-olefin-maleic anhydride copolymer with a (meth)acrylic compound having a hydroxy group such as hydroxyalkyl (meth)acrylate is also used.

[0112] (Surfactant) Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. Examples of the nonionic surfactant include fluorine-based surfactants, silicone-based surfactants, polyoxyethylene-based surfactants, and the like. Examples of anionic surfactants include alkyl sulfonates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, polyoxyethylene alkyl ether sulfonates, alkyl sulfates, alkyl sulfate esters, higher alcohol sulfate esters, aliphatic alcohol sulfate esters, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl phosphate esters, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, special polymer surfactants, and the like. Examples of cationic surfactants include quaternary ammonium salts, imidazoline derivatives, alkylamine salts, and the like. Examples of amphoteric surfactants include betaine-type compounds, imidazolium salts, imidazolines, amino acids, and the like.

[0113] (Leveling agent) Examples of leveling agents include, for example, silicone-based, fluorine-based, and the like. Examples of silicone-based 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, fatty acid ester-modified silicone, and the like. Examples of fluorine-based include carbon fluoride-based compounds, fluorosilicone, and the like. These can be used alone or in combination of two or more.

[0114] (Filler) Examples of fillers include, for example, silicon dioxide, alumina, zinc white, potassium titanate fiber, aluminum flake, stainless steel powder, tin powder, gold powder, metal-plated glass powder, titanium mica, calcium carbonate, barium sulfate, barium carbonate, kaolin, barite, clay, and other metal oxides, composite metal oxides, etc. In order to prevent a decrease in viscosity and poor gloss, they can be used alone or in combination of two or more.

[0115] (Resin for electrode formation) The resin for electrode formation is used to bind particles such as active materials and conductive carbon materials to each other, or to bind conductive carbon particles and current collectors. Examples of the resin for electrode formation include acrylic resins, polyurethane resins, polyester resins, phenol 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, and conductive resins such as polyaniline and polyacetylene. Further, modified products, mixtures, or copolymers of these resins can also be used. These resins can be used alone or in combination of two or more.

[0116] <Method for producing colored composition> The colored composition can be prepared by mixing a coloring agent, a dispersant (block copolymer), an aqueous dispersion medium, and, if necessary, a resin for film formation and other compounding agents. For mixing, for example, mixing and dispersing machines such as paint shakers, bead mills, ball mills, dissolvers, and kneaders can be used. The colored composition is preferably filtered after mixing. Examples of the colored composition include automotive paint compositions.

[0117] Coating (painting) of the colored composition onto a substrate such as a stainless steel plate or an aluminum plate can be performed by methods such as roll coating, spin coating, flow coating, slot die coating, spray coating, dip coating, electrodeposition coating, electrostatic coating, brush painting, and powder coating. Thereafter, if necessary, it is heated to evaporate the solvent, and the coating film is dried and cured. At this time, heating or irradiation with ultraviolet rays or the like may be performed. On the coating film obtained by applying the colored composition, one or more layers of top clear paint may be further applied to form a top clear coating film. The top clear paint is a liquid paint that forms a colorless or colored transparent coating film mainly composed of a resin component and a solvent, and further containing other paint additives as necessary.

Examples

[0118] 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 practiced with appropriate modifications 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.

[0119] 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, Blenmer (registered trademark) AME-400) M11EGA: Polyethylene glycol (degree of polymerization = 11) methyl ether acrylate (Green Co., KOMERATE-A040TT) VP: N-vinyl-2-pyrrolidone ACMO: 4-acryloylmorpholine DEAA: Diethylacrylamide NIPAM: Isopropylacrylamide DMAEMA: Dimethylaminoethyl methacrylate 4VPy: 4-vinylpyridine PMA: Propylene glycol monomethyl ether acetate MeOH: Methanol

[0120] (Polymerization rate) Using a nuclear magnetic resonance (NMR) measurement device (Bruker Biospin, model: AVANCE500 (frequency 500 MHz)), 1 H-NMR was measured (solvent: CDCl3, internal standard: TMS). For the obtained NMR spectrum, the integral ratio of the peak derived from the monomer to the peak derived from the polymer was determined, and the polymerization rate of the monomer was calculated.

[0121] (Weight average molecular weight (Mw) and molecular weight distribution (PDI)) The molecular weights were determined by gel permeation chromatography (GPC) using a high-performance liquid chromatograph (Tosoh, Model HLC-8320). A SHODEX KF-603 (φ6 mm × 150 mm) column (SHODEX) was used. The mobile phase was a lithium bromide (10 mmol / L)-acetic acid (10 mmol / L)-methylpyrrolidone solution, and the detector was a differential refractometer. The measurement conditions were a column temperature of 40°C, a sample concentration of 20 mg / mL, a sample injection volume of 10 μm, and a flow rate of 0.2 mL / min. A calibration curve was prepared using polystyrene standards (molecular weights: 70,500, 37,900, 19,920, 10,200, 4,290, 2,630, and 1,150), and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) were measured. The molecular weight distribution (PDI=Mw / Mn) was calculated from the measured values.

[0122] (amine value) The amine value represents the mass of potassium hydroxide (KOH) equivalent to the basic component per 1 g of solids. The measurement sample was dissolved in tetrahydrofuran, and the resulting 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 inflection point of the titration pH curve was used as the titration endpoint, and the amine value (B) was calculated using the following formula. B=56.11×Vs×0.1×f / w B: Amine value (mgKOH / 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 of the measurement sample (g) (solid content equivalent)

[0123] (Black rating) 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 surface of the obtained test piece was measured with specular reflection removed using an L value measuring device (Model CM-2600d, manufactured by Konica Minolta Japan, Inc.) Evaluation was carried out on the black paint immediately after preparation and on the black paint after being left at 35°C for 3 weeks after preparation.

[0124] (Blue rating) A blue paint (primary color) was applied to a 100 μm transparent film using a 52 μm bar, pre-dried at 60°C, and then dried at 140°C for 10 minutes to form a coating film, which was then used to prepare a test specimen. The haze of the coating surface of the resulting test specimen was measured using a haze meter (manufactured by Nippon Denshoku Co., Ltd., model NDH-5000). In addition, blue paint (aluminum coating paint) was applied to a 100 μm transparent film using a 52 μm bar, pre-dried at 60 ° C, and then dried at 140 ° C for 10 minutes to form a coating film, and a test piece was prepared. The surface of the obtained test piece on which the coating film was formed was measured using a spectrophotometer (manufactured by Konica Minolta Japan, model CM-2600d), and the chroma was calculated as C = (a 2 +b 2 ) 1 / 2 Calculated from.

[0125] <Synthesis of block copolymer> (Block copolymer No. 1) A flask equipped with an argon gas inlet tube and a stirrer was charged with 9.0 g of BA, 18.0 g of M9EGA, 0.05 g of AIBN, and 6.7 g of PMA. After replacing the atmosphere with nitrogen, 0.45 g of BTEE was added and the reaction was carried out at 60°C for 25 hours to polymerize the A block. The conversion rate was 95%.

[0126] A mixed solution of 10.2 g of ACMO, 0.05 g of AIBN, and 9.2 g of MeOH, which had been previously purged with argon, was added to the reaction solution, and the mixture was reacted at 60° C. for 36 hours to polymerize the B block. The polymerization rate was 100%.

[0127] After the reaction was completed, the reaction solution was poured into the stirring n-heptane. The precipitated polymer was obtained by suction filtration and drying to obtain block copolymer No. 1. The obtained block copolymer No. 1 had an Mw of 26,312 and a PDI of 1.25.

[0128] (Block copolymers No. 2 to 8) In the same manner as the production method of block copolymer No. 1, block copolymers No. 2 to 8 were prepared. Table 1 shows the monomers, organic tellurium compounds, azo polymerization initiators, solvents, reaction conditions, and polymerization rates used. Table 2 shows the composition, Mw, PDI, and amine value of each block copolymer. The content rate of each structural unit in the copolymer was calculated from the charging ratio of the monomers used in the polymerization reaction and the polymerization rate.

[0129]

Table 1

[0130]

Table 2

[0131] (Black paints No. 1 to 8) As a dispersant, black paints were prepared using block copolymers No. 1 to 8 obtained above. Specifically, each component was put into a 50 mL mayonnaise bottle so as to have the formulation shown in Table 3, and further 66 g of zirconia beads (φ0.3 mm) were added, and using a disperser (manufactured by Ohwel Co., Ltd., SKANDEX DISPERSER BA-S20), it was stirred for 5 hours. After the stirring was completed, the beads were filtered off to obtain a pigment dispersion. By mixing the obtained pigment dispersion and a clear paint, black paints No. 1 to 8 were prepared. It was visually confirmed that the carbon black had good dispersibility in the obtained black paints No. 1 to 8.

[0132]

Table 3

[0133] (Blue paint No.1 - 8) As a dispersant, block copolymers No.1 - 8 obtained above were used to prepare blue paints (primary color, aluminum split paint). Specifically, each component was put into a 50 mL mayonnaise bottle so as to have the formulation shown in Table 4, and further 66 g of zirconia beads (φ0.3 mm) were added. Using a disperser (manufactured by Aurwell, SKANDEX DISPERSER BA-S20), it was stirred for 5 hours. After the stirring was completed, the beads were filtered off to obtain a pigment dispersion. By mixing the obtained pigment dispersion with a clear paint or the pigment dispersion with aluminum primary color, blue paints No.1 - 8 (primary color, aluminum split paint) were prepared. Regarding the obtained blue paints No.1 - 8 (primary color, aluminum split paint), it was visually confirmed that the dispersibility of the blue pigment was good.

[0134]

Table 4

[0135] 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). For the black paints using these block copolymers No. 2 to 5, the L value of the prepared paint film was low both immediately after preparation and after 3 weeks of storage. Also, the haze value of the paint film formed from the blue paints (primary colors) using these block copolymers No. 1 to 5 was low. Furthermore, the chroma of the paint film formed from the blue paint (aluminum split paint) was high. Therefore, these block copolymers No. 1 to 5 have high dispersion performance for both black colorants and blue colorants.

[0136] Block copolymers No. 6 to 8 are cases where they do not have a B block containing a structural unit represented by formula (3). For the black paints using these block copolymers No. 6 to 8, the L value of the prepared paint film was high both immediately after preparation and after 3 weeks of storage. Also, for the blue paints using these block copolymers No. 6 to 8 (primary colors), the haze value of the prepared paint film was high. Furthermore, the chroma of the paint film formed from the blue paint (aluminum split paint) using block copolymers No. 6 to 8 was low.

Industrial Applicability

[0137] The block copolymer of the present invention can be used as a dispersant for a coloring composition containing a colorant and an aqueous dispersion medium, and is particularly useful as a dispersant for carbon particles. Since the coloring composition of the present invention has high jet blackness of the formed paint film, it is useful for automotive paints and the like.

Claims

Claim 1: A dispersant containing a block copolymer, wherein the block copolymer has an A block containing a structural unit represented by formula (1) and a B block containing a structural unit represented by formula (3), the B block further contains a structural unit derived from a vinyl monomer having a basic group or a structural unit having a cyclic N-alkenyl lactam structure represented by formula (4), and is characterized by a dispersant. 【Chemical 1】 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 may be the same or different from each other.] 【Chemical 2】 [In formula (3), R 31 represents a hydrogen atom or a methyl group. X represents a -CO- group or a -COO-R32- group. R 32 represents a single bond or an alkylene group having 1 to 10 carbon atoms.] 【Chemical Formula 3】 [In formula (4), R 41 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. m4 represents an integer of 0 to 4. n4 represents an integer of 1 to 3.] Claim 2 The dispersant according to claim 1, wherein the content of the structural unit represented by formula (1) is 20% by mass to 95% by mass in 100% by mass of the A block. Claim 3 The dispersant according to claim 1 or 2, wherein the content of the structural unit represented by formula (3) is 20% by mass to 95% by mass in 100% by mass of the B block. Claim 4 The dispersant according to any one of claims 1 to 3, wherein the mass ratio (A block / B block) of the A block and the B block in the block copolymer is 50 / 50 to 95 / 5. Claim 5 The dispersant according to any one of claims 1 to 4, wherein the A block further contains a structural unit represented by formula (2). 【Chemical Formula 4】 [In formula (2), R 21 represents a linear or cyclic hydrocarbon group which may have a substituent. R 22 represents a hydrogen atom or a methyl group. ] Claim 6 The dispersant according to any one of claims 1 to 5, wherein the molecular weight distribution (PDI) of the block copolymer is 2.5 or less. Claim 7 The dispersant according to any one of claims 1 to 6, wherein the weight average molecular weight (Mw) of the block copolymer is 3,000 to 40,000. Claim 8: The dispersant according to any one of claims 1 to 7, wherein the content of the structural unit derived from the vinyl monomer having a basic group is 5% by mass to 80% by mass in 100% by mass of the B block. Claim 9: The dispersant according to any one of claims 1 to 7, wherein the content of the structural unit represented by formula (4) is 5% by mass to 80% by mass in 100% by mass of the B block. Claim 10: A coloring composition comprising the dispersant according to any one of claims 1 to 9, a coloring material, and an aqueous dispersion medium. Claim 11 The coloring composition according to claim 10, wherein the coloring material is at least one selected from the group consisting of a black pigment and a blue pigment. Claim 12 The colored composition according to claim 11, further containing a resin for forming a coating film.

13. The colored composition according to claim 12, which is an automotive paint composition.

14. A coating film characterized by being formed from the colored composition according to any one of claims 10 to 13.

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