Emulsion-type anionic electrodeposition paint, coating method, and method for producing coated article

Abstract

To provide an emulsion-type anionic electrodeposition coating excellent in storage stability that can form a coating film excellent in thermal shock resistance, substrate adhesion, water resistance, corrosion resistance and the like.SOLUTION: Provided is an emulsion-type anionic electrodeposition coating that contains a composite resin (C) having an epoxy resin (A) part and a carboxyl group-containing acrylic polymer (B) part, water, and an organic solvent (D), and has an electrical conductivity of 300 to 1200 μS / cm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an emulsion-type anionic electrodeposition paint that can be used to form a coating film in anionic electrodeposition coating, a coating method therefor, and a method for producing a coated article. [Background technology]

[0002] Electrodeposition coating is a coating method in which a substrate (e.g., a metal) and a pair of electrodes are immersed in an electrodeposition coating, a voltage is applied, and charged film-forming components in the coating are electrophoresed and deposited on the substrate, forming a coating film. Electrodeposition coating can form a coating film of uniform thickness even on substrates with complex shapes, and also has excellent edge coverage. Compared to spray coating and dip coating, electrodeposition coating can form a more uniform coating film. Therefore, it is used in a variety of fields, such as automotive parts, building materials, and electronic materials and components, to improve the corrosion resistance, water resistance, durability, etc. of coated substrates. Furthermore, because electrodeposition coating can be applied using a small amount of organic solvent, it is an excellent coating method from the perspective of VOC (volatile organic compound) countermeasures. Depending on the charge of the coating film-forming components, electrodeposition coating is divided into anionic electrodeposition coating and cationic electrodeposition coating. Of these, anionic electrodeposition coating is a coating method in which anionic electrodeposition paint carrying an anionic charge is electrodeposited onto the substrate, which acts as the anode, and is widely used in electrodeposition coating of aluminum and other materials.

[0003] Patent Document 1 describes that an alkoxyalkyl(meth)acrylamide and a (meth)acrylic monomer having an alkoxysilyl group are polymerized in an organic solvent to obtain a resin solution, and the carboxyl groups in the resin solution are neutralized to make it water-soluble, and then a melamine resin is added to obtain an anionic electrodeposition paint (Claim 1, Paragraph 0020, Examples, etc.). However, because a water-soluble acrylic resin obtained by solution polymerization is used as the main component of the coating resin, there are problems in that the coating film formed is easily brittle and has insufficient substrate adhesion and thermal shock resistance.

[0004] Patent Document 2 describes the use of sodium polyoxyethylene phenyl ether sulfate as a surfactant, emulsion polymerization of an acrylic monomer in water, and then emulsion polymerization of an acrylic monomer for the core to obtain an anionic acrylic resin emulsion (Examples 6 and 7). However, sodium ions derived from the surfactant used during emulsion polymerization remain in the coating film, which causes problems such as insufficient water resistance and corrosion resistance of the coating film.

[0005] Patent Document 3 discloses an anionic electrodeposition paint containing an epoxy resin-modified polyester resin obtained by reacting a carboxyl group-containing polyester resin with an epoxy resin having at least one epoxy group per molecule. However, the resulting coating film does not satisfy the high corrosion resistance required for automobile parts and the like, and the coating film also has problems such as insufficient thermal shock resistance.

[0006] Patent Document 4 discloses an electrodeposition coating composition characterized by containing a dispersion of polyarylene sulfide microparticles coated with an ionic functional group-containing aqueous polymer compound and an ionic functional group-containing aqueous resin. However, since it is difficult to obtain long-term dispersion stability of polyarylene sulfide, which is a crystalline thermoplastic resin, in an aqueous medium, there are problems with the storage stability of the coating material and the coating appearance of the resulting coating film. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 10-7739 [Patent Document 2] Japanese Patent Application Publication No. 4-55479 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-112996 [Patent Document 4] Japanese Patent Application Laid-Open No. 2017-186391 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention solves the problems of the prior art described above, and aims to provide an emulsion-type anionic electrodeposition paint with excellent storage stability that can be used in electrodeposition coating to obtain an excellent coating film appearance and form a coating film on the substrate that is excellent in thermal shock resistance, substrate adhesion, water resistance, corrosion resistance, etc. [Means for solving the problem]

[0009] The emulsion-type anionic electrodeposition paint of the present invention (hereinafter sometimes simply referred to as electrodeposition paint) contains a composite resin (C) having an epoxy resin (A) part and a carboxyl group-containing acrylic polymer (B) part, water, and an organic solvent (D), and has an electrical conductivity of 300 to 1200 μS / cm. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an emulsion-type anionic electrodeposition paint which has high storage stability over a long period of time and which provides a coating film formed by anionic electrodeposition coating with excellent coating appearance, thermal shock resistance, substrate adhesion, water resistance, and corrosion resistance. DETAILED DESCRIPTION OF THE INVENTION

[0011] The emulsion-type anionic electrodeposition paint of the present invention and its production method will be described below. In the present invention, the monomer is an ethylenically unsaturated monomer. Furthermore, (meth)acrylic acid includes both acrylic acid and methacrylic acid, and (meth)acrylate includes both acrylate and methacrylate. In the present invention, (iso)alkyl ether includes both normal alkyl ether (n-alkyl ether) and isoalkyl ether (the alkyl may include specific alkyl groups such as propyl and butyl). The coating film of the present invention refers to a film formed by electrodeposition coating an emulsion-type anionic electrodeposition paint on a substrate such as a metal plate, followed by baking.

[0012] [Emulsion-type anionic electrodeposition paint] The emulsion-type anionic electrodeposition paint of the present invention is an emulsion-type anionic electrodeposition paint containing a composite resin (C), water, and an organic solvent (D), The composite resin (C) has an epoxy resin (A) portion and a carboxyl group-containing acrylic polymer (B) portion (hereinafter also simply referred to as polymer (B) portion).

[0013] <Epoxy resin (A)> The epoxy resin (A) portion refers to a structural portion derived from the epoxy resin (A) in the composite resin (C) formed by reacting a portion of the epoxy resin (A) to form a bond with the acrylic polymer (B). Bisphenol-type, novolac-type, naphthalene-type, biphenyl-type, alicyclic-type, and other epoxy resins can be suitably used as the epoxy resin (A). Among these, bisphenol-type epoxy resins are preferred in consideration of the thermal shock resistance, corrosion resistance, and substrate adhesion when formed into a coating film.

[0014] The epoxy equivalent of the epoxy resin (A) is preferably from 200 to 50,000, more preferably from 300 to 35,000, and particularly preferably from 350 to 25,000. When the epoxy equivalent is equal to or greater than the lower limit, the coating film has better thermal shock resistance and corrosion resistance, whereas when the epoxy equivalent is equal to or less than the upper limit, the coating film has better substrate adhesion and the emulsion-type anionic electrodeposition paint has better storage stability.

[0015] The weight average molecular weight of the epoxy resin (A) is preferably from 1,000 to 200,000, more preferably from 1,250 to 150,000, and particularly preferably from 1,500 to 100,000. When the weight average molecular weight is equal to or greater than the lower limit, the coating film has better thermal shock resistance and corrosion resistance, whereas when the weight average molecular weight is equal to or less than the upper limit, the coating film has better substrate adhesion and the emulsion-type anionic electrodeposition paint has better storage stability.

[0016] In the present invention, examples of commercially available epoxy resins (A) include jER1001, jER1002, jER1003, jER1004, JER1007, jER1009, jER1010, jER1256, jER4250, jER4275, jER4005P, jER4007P, and jER4010P manufactured by Mitsubishi Chemical Corporation.

[0017] <Carboxyl group-containing acrylic polymer (B)> The carboxyl group-containing acrylic polymer (B) portion is an acrylic polymer composed of an ethylenically unsaturated monomer, and is a portion that forms a bond with the epoxy resin (A) in the composite resin (C). The monomer contains at least a carboxyl group-containing monomer, and other ethylenically unsaturated monomers may also be used as needed.

[0018] The carboxyl group-containing monomer has at least an ethylenically unsaturated bond and a carboxyl group. The ethylenically unsaturated bond may be a vinyl group, an allyl group, or a (meth)acryloyl group. Specific examples include (meth)acrylic acid, maleic acid (anhydride), itaconic acid, and fumaric acid, and among these, (meth)acrylic acid is preferred. The carboxyl group-containing monomers can be used alone or in combination of two or more.

[0019] The other ethylenically unsaturated monomers are not particularly limited, but examples thereof include (meth)acrylic acid alkyl ester monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; Ethylenically unsaturated monomers having a hydroxyl group, such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, and hydroxyhexyl (meth)acrylate; Styrenic monomers such as styrene, vinyltoluene, 2-methylstyrene, tert-butylstyrene, and chlorostyrene; Examples thereof include N-hydroxyalkyl (meth)acrylamides such as N-hydroxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, and N-hydroxybutyl (meth)acrylamide; N-alkoxyalkyl (meth)acrylamides such as N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-(n-, iso)butoxymethyl (meth)acrylamide, N-methoxyethyl (meth)acrylamide, N-ethoxyethyl (meth)acrylamide, and N-(n-, iso)butoxyethyl (meth)acrylamide; and amide monomers such as (meth)acrylamide. As the other ethylenically unsaturated monomer, it is preferable to use an acrylic acid alkyl ester-based monomer or a styrene-based monomer. The other ethylenically unsaturated monomers may be used singly or in combination of two or more.

[0020] The polymer (B) portion can be obtained by polymerizing an ethylenically unsaturated monomer using an azobis-based polymerization initiator, a peroxide-based polymerization initiator, or the like, according to a conventional method. Examples of the azobis-based polymerization initiator include azobisisobutyronitrile, azobismethylbutyronitrile, azobis-(2,4-dimethylvaleronitrile), and 2,2'-azobis-(4-methoxy-2,4-dimethylvaleronitrile). Examples of peroxide-based polymerization initiators include tert-butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide, benzoyl peroxide (benzoyl peroxide), diisopropyl peroxydicarbonate, and tert-butyl peroxybenzoate.

[0021] The organic solvent used in the reaction step is not particularly limited, but solvents with relatively high hydrophilicity such as those shown below are preferred. Specific examples include alcohols such as ethanol, n-propanol, isopropanol, n-butyl alcohol, isobutyl alcohol, n-amyl alcohol, amyl alcohol, methyl amyl alcohol, octanol, and 2-ethylhexanol; Glycols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and 1,3-butylene glycol; Ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, ethylene glycol mono(iso)propyl ether, ethylene glycol di(iso)propyl ether, ethylene glycol mono(iso)butyl ether, ethylene glycol di(iso)butyl ether, ethylene glycol mono-tert-butyl ether, ethylene glycol monohexyl ether, 1,3-butylene glycol-3-monomethyl ether, 3-methoxybutanol, 3-methyl-3-methoxybutanol, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol mono(iso)propyl ether, diethylene glycol di(iso)propyl ether, diethylene glycol mono(iso)butyl ether, diethylene glycol di(iso)butyl ether various ether alcohols or ethers such as diethylene glycol monohexyl ether, diethylene glycol dihexyl ether, triethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono(iso)propyl ether, propylene glycol mono(iso)butyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di(iso)propyl ether, propylene glycol di(iso)butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono(iso)propyl ether, dipropylene glycol mono(iso)butyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol di(iso)propyl ether, and dipropylene glycol di(iso)butyl ether; Organic solvents such as acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, ethylene glycol monobutyl ether acetate, and 3-methyl-3-methoxybutyl acetate can be used appropriately, and may be added separately after the reaction, if necessary.

[0022] The polymer (B) portion more preferably contains a carboxyl group-containing acrylic polymer (B-1) portion and a carboxyl group-containing acrylic polymer (B-2) portion (hereinafter abbreviated as (B-1) portion and (B-2) portion, respectively). The composite resin (C) containing the (B-1) and (B-2) moieties is preferably formed by the esterification method described below. Specifically, the acrylic polymers that form the (B-1) and (B-2) moieties are first prepared, and then reacted with the epoxy resin (A).

[0023] The glass transition temperature (Tg) of the (B-1) portion is preferably 40 to 130°C, more preferably 45 to 125°C, and particularly preferably 50 to 120°C. When the glass transition temperature (Tg) is at least the lower limit, the corrosion resistance of the coating film and the storage stability of the emulsion-type anionic electrodeposition paint are superior. When the glass transition temperature (Tg) is at most the upper limit, the appearance of the coating film after electrodeposition coating and the thermal shock resistance of the coating film are superior.

[0024] The glass transition temperature (Tg) of the (B-2) portion is preferably from -20 to 30°C, more preferably from -20 to 25°C, and particularly preferably from -20 to 20°C. If the glass transition temperature (Tg) is equal to or higher than the lower limit, the water resistance and corrosion resistance of the coating film will be superior, and if it is equal to or lower than the upper limit, the appearance of the coating film after electrodeposition coating and the thermal shock resistance of the coating film will be superior.

[0025] The glass transition temperature (Tg) is a value calculated by Fox's formula shown in the following formula (1) using the Tg of the homopolymer of the monomer described in the Polymer Handbook or the like. For example, when using monomers M1, M2, M3, M4, ...MN, the mass percentages of each are W1, W2, W3, W4, ...WN (the total of W1, W2, W3, W4, ...WN is 100 mass%), and the glass transition temperatures (unit: K) of the homopolymers of each monomer are Tg1, Tg2, Tg3, Tg4, ...TgN, the Tg (K) of the copolymer obtained by copolymerization is calculated using the Fox formula, shown below in equation (1). 1 / Tg(K)=[(W1 / Tg1)+(W2 / Tg2)+(W3 / Tg3)+(W4 / Tg4)····(WN / TgN)] / 100···· Formula (1) If the Tg of the homopolymer of the monomer is not known, the Tg is measured by DSC (Differential Scanning Calorimetry). The temperature rise rate in DSC is 10°C / min.

[0026] The acid value of the acrylic polymer forming the portion (B-1) is preferably from 180 to 500 mgKOH / g, more preferably from 200 to 480 mgKOH / g, and particularly preferably from 200 to 450 mgKOH / g. When the acid value is equal to or greater than the lower limit, the coating film has better substrate adhesion and the emulsion-type anionic electrodeposition paint has better storage stability, while when the acid value is equal to or less than the upper limit, the coating film has better water resistance and corrosion resistance. The acid value used in the present invention is a theoretical value determined from the charged ratio of the carboxyl group-containing monomer to the total amount of monomers forming the polymer (B) portion.

[0027] The weight average molecular weight of the acrylic polymer forming the (B-1) portion is preferably from 5,000 to 100,000, more preferably from 6,000 to 90,000, and particularly preferably from 7,000 to 80,000. If the weight average molecular weight is equal to or greater than the lower limit, the coating film will have better thermal shock resistance and corrosion resistance, and if it is equal to or less than the upper limit, the coating film will have better appearance when applied by electrodeposition coating.

[0028] The acid value of the acrylic polymer forming the (B-2) portion is preferably from 10 to 170 mgKOH / g, more preferably from 10 to 150 mgKOH / g, and particularly preferably from 10 to 135 mgKOH / g. When the acid value is equal to or greater than the lower limit, the coating film has better substrate adhesion and the emulsion-type anionic electrodeposition paint has better storage stability, while when the acid value is equal to or less than the upper limit, the coating film has better water resistance and corrosion resistance.

[0029] The weight average molecular weight of the acrylic polymer forming the (B-2) portion is preferably from 7,000 to 200,000, more preferably from 8,000 to 170,000, and particularly preferably from 9,000 to 150,000. If the weight average molecular weight is equal to or greater than the lower limit, the corrosion resistance of the coating film is superior, and if it is equal to or less than the upper limit, the appearance of the coating film when applied by electrodeposition coating is superior.

[0030] The mass ratio of the (B-1) part to the (B-2) part in the polymer (B) part is preferably (B-1) parts / (B-2) parts=100 / 0 to 20 / 80, more preferably 100 / 0 to 25 / 75, and particularly preferably 85 / 15 to 25 / 75. When the mass ratio of the (B-1) part to the (B-2) part is within the above range, the composite resin (C) has excellent dispersion stability in the electrodeposition paint, and the appearance of the coating film after electrodeposition coating, the thermal shock resistance of the coating film, and the corrosion resistance are also superior. The polymer (B) portion may contain other acrylic polymer portions in addition to the (B-1) portion and the (B-2) portion.

[0031] <Composite resin (C)> The composite resin (C) is a resin having an epoxy resin (A) portion and a carboxyl group-containing acrylic polymer (B) portion, in which at least a portion of the epoxy resin (A) and at least a portion of the acrylic polymer (B) are bonded together.

[0032] The synthesis method of the composite resin (C) is not particularly limited, but examples of the production method include an esterification method, a grafting method, a direct method, etc. Esterification method: This method involves polymerizing an ethylenically unsaturated monomer containing a carboxyl group-containing monomer as an essential component to obtain a carboxyl group-containing acrylic polymer (B), and then esterifying some of the carboxyl groups in this polymer with some of the epoxy groups in the epoxy resin (A) in the presence of a basic compound to obtain a composite resin (C). Grafting method: This method involves polymerizing an ethylenically unsaturated monomer, the essential component of which is a carboxyl group-containing monomer, using a polymerization initiator in the presence of an epoxy resin (A), to obtain a composite resin (C) in which an acrylic polymer is grafted onto the epoxy resin. Direct method: In this method, a portion of the epoxy groups in the epoxy resin (A) is reacted with the carboxyl groups of a carboxyl group-containing monomer, and this compound is copolymerized with an ethylenically unsaturated monomer that contains the carboxyl group-containing monomer as an essential component to obtain a composite resin (C).

[0033] The composite resin (C) can also be obtained by combining the above methods, for example, a method in which an ethylenically unsaturated monomer is polymerized in the presence of the epoxy resin (A) to carry out graft polymerization, followed by adding a basic compound to carry out an esterification reaction, or a method in which an ethylenically unsaturated monomer is copolymerized in the presence of a reaction product of the epoxy resin (A) and a carboxyl group-containing monomer to carry out direct polymerization, followed by an esterification reaction, etc.

[0034] In the above grafting method, as the polymerization initiator used for polymerization, among the polymerization initiators exemplified for obtaining the polymer (B) portion, peroxides are preferred, and benzoyl peroxide is particularly preferred. The reaction conditions such as temperature and time during the grafting reaction are not special and can be any known conditions.

[0035] The esterification catalyst used in the esterification is preferably an organic amine compound, ammonia, or a basic compound such as an alkali metal hydroxide. Examples of the organic amine compound include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine (also known as dimethylaminoethanol), N,N-diethylethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, N-methyldiethanolamine, N-ethyldiethanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. The basic compounds can be used singly or in combination of two or more, and they can be added all at once or in several portions. The reaction conditions such as temperature and time during the esterification reaction are not particularly limited, and the reaction can be carried out under known conditions.

[0036] When the composite resin (C) is obtained, the ratio by mass of the epoxy resin (A) to the acrylic polymer (B) is preferably (A) / (B)=45 / 55 to 90 / 10, more preferably 50 / 50 to 85 / 15, and particularly preferably 55 / 45 to 85 / 15. The mass of the polymer (B) is the total amount of the constituent monomers. When an acrylic polymer forming the (B-1) portion and the (B-2) portion is used, (B) is the total mass of the acrylic polymer. If the proportion of (B) is 55 or less, the resulting composite resin (C) will have excellent dispersion stability in the electrodeposition paint, and the hydrophilicity will not be too high, resulting in the coating film having better water resistance, corrosion resistance, and thermal shock resistance. On the other hand, if the proportion of (B) is 10 or more, the resulting composite resin (C) will have sufficient hydrophilicity, excellent dispersion stability in the electrodeposition paint, and better coating appearance and substrate adhesion when electrodeposition coated.

[0037] The composite resin (C) of the present invention is dispersed in a mixed solvent of water and an organic solvent (D) and used as an emulsion-type paint. The composite resin (C) can be made into an emulsion by a method similar to that used for conventional emulsification of acrylic-modified epoxy resins. Specifically, the carboxyl groups present in the composite resin (C) can be neutralized with a basic compound or the like to impart hydrophilicity. More specifically, examples of the method include a method in which a basic compound is added to a solution of the composite resin (C) and then an aqueous medium is added to form an emulsion, and a method in which an aqueous medium containing a basic compound is added to a solution of the composite resin (C) to form an emulsion.

[0038] The basic compound used to neutralize the carboxyl groups present in the composite resin (C) is preferably an organic amine compound, ammonia, an alkali metal hydroxide, or the like. Examples of the organic amine compound include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine (also known as dimethylaminoethanol), N,N-diethylethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, N-methyldiethanolamine, N-ethyldiethanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine. Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. The basic compounds can be used singly or in combination of two or more.

[0039] <Organic solvent (D)> The emulsion-type anionic electrodeposition paint of the present invention contains water and an organic solvent (D) as solvents. The inclusion of the organic solvent (D) can, for example, improve film-forming properties during electrodeposition coating, thereby improving the coating appearance, substrate adhesion of the coating film, thermal shock resistance, corrosion resistance, etc. The organic solvent (D) is not particularly limited, but is preferably a highly hydrophilic solvent such as those exemplified as solvents used in synthesizing the acrylic polymer (B) portion. Among these, alkylene glycol monoalkyl ethers in which the alkyl group has 1 to 6 carbon atoms or alkyl alcohols in which the alkyl group has 1 to 10 carbon atoms are preferred from the viewpoints of the storage stability of the emulsion-type anionic electrodeposition paint, surface tension control effect, film-forming properties during electrodeposition coating, and solvent evaporation rate during baking. The organic solvent (D) can be used alone or in combination of two or more kinds.

[0040] The organic solvent (D) is contained in the emulsion type anionic electrodeposition coating material preferably in an amount of 3.0 to 20.0 mass %, more preferably 3.0 to 18.0 mass %, and particularly preferably 4.0 to 17.0 mass %. When the content of the organic solvent (D) is 3.0 mass % or more and 20.0 mass % or less, the film-forming properties during electrodeposition coating are improved, and a better coating appearance is obtained, resulting in better thermal shock resistance, corrosion resistance, etc. of the coating film. The emulsion type anionic electrodeposition paint preferably contains 50 to 98% by mass of water, more preferably 55 to 97% by mass, and particularly preferably 60 to 96% by mass.

[0041] The organic solvent (D) preferably contains an organic solvent (D-1) having a boiling point of 120 to 250° C., more preferably 150 to 250° C. If the boiling point of the organic solvent (D-1) is in the range of 120 to 250° C., the film-forming properties during electrodeposition coating and baking are improved, and a better coating appearance is obtained, resulting in better thermal shock resistance, substrate adhesion, corrosion resistance, etc. of the coating. The organic solvent (D) may be composed of the organic solvent (D-1) alone, or may be mixed with an organic solvent having a boiling point different from that of the organic solvent (D-1) as required.

[0042] The organic solvent (D-1) having a boiling point of 120 to 250°C is preferably contained in the emulsion type anionic electrodeposition paint in an amount of 1.5 to 17.0 mass%, more preferably 3.0 to 15.0 mass%, and particularly preferably 3.0 to 13.0 mass%. When the content of the organic solvent (D-1) is 1.5 mass % or more and 17.0 mass % or less, the film-forming properties during electrodeposition coating and baking are improved, and a better coating appearance is obtained, resulting in better thermal shock resistance, substrate adhesion, corrosion resistance, etc. of the coating.

[0043] A curing agent can be added to the emulsion-type anionic electrodeposition paint of the present invention, if necessary, to improve the curing properties of the coating film and its adhesion to the substrate. Examples of curing agents that can be used include phenolic resins, amino resins, blocked polyisocyanate compounds, β-hydroxyalkylamides, and tris(alkoxycarbonylamino)triazines. Of these, it is preferable to select from the group consisting of phenolic resins and amino resins. One or more curing agents may be added. The curing agent can react with carboxyl groups in the composite resin (C). If the composite resin (C) has hydroxyl groups, the curing agent can also react with those hydroxyl groups. Furthermore, if the other ethylenically unsaturated monomers constituting the acrylic polymer (B) portion contain amide monomers and the composite resin (C) has crosslinkable functional groups derived from these amide monomers, the curing agent can also react with these crosslinkable functional groups.

[0044] Examples of phenolic resins include resins synthesized by an addition-condensation reaction between a phenolic compound and an aldehyde such as formaldehyde. Examples of phenolic compounds include bisphenol A, phenol, o-cresol, p-cresol, m-cresol, p-tert-butylphenol, p-phenylphenol, p-nonylphenol, 2,3-xylenol, 2,5-xylenol, 3,5-xylenol, catechol, resorcinol, and hydroquinone. In this case, the phenolic compounds may be used alone or in combination of two or more.

[0045] Commercially available phenolic resins may be used, and examples of commercially available phenolic resins that can be preferably used include Phenodur PR285, PR411, PR516, PR517, R612, and VPR1785 manufactured by Allnex Co., Ltd., and Shounol CKS-380A and CKS-3898 manufactured by Aica SDK Phenol Co., Ltd.

[0046] Examples of amino resins include those obtained by addition reaction of formaldehyde with amino compounds such as urea, melamine, and benzoguanamine. In this case, the amino compounds can be used alone or in combination of two or more.

[0047] Commercially available amino resins may be used, and examples of commercially available amino resins that can be preferably used include Cymel 301, 303LF, 304, 323, 325, 328, 370, 659, and 1123 manufactured by Allnex, and Luwipal 014, 015, 018, 066, 070, 052, and B017 manufactured by BASF.

[0048] The above phenol resins and amino resins may also be suitably used in the form in which some or all of the methylol groups formed by addition of formaldehyde are etherified with alcohols having 1 to 12 carbon atoms.

[0049] Examples of polyisocyanate compounds used in the blocked polyisocyanate compound include polyisocyanate compounds such as toluene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate; cyclized polymers or biuret products of these polyisocyanate compounds; and combinations thereof. Examples of blocking agents include dimethylpyrazole, methyl ethyl ketone oxime, and ε-caprolactam.

[0050] The blocked polyisocyanate compound may be a commercially available product. Preferred commercially available products include Desmodur BL 1265 manufactured by COVESTRO, and VESTANAT B1358A, B1370, and B1186A manufactured by EVONIK.

[0051] The curing agent is preferably added in an amount of 0 to 30 parts by mass, more preferably 0.5 to 25 parts by mass, and particularly preferably 0.5 to 20 parts by mass, per 100 parts by mass of the composite resin (C). By keeping the curing agent amount within this range, the coating material's adhesion to substrates, corrosion resistance, thermal shock resistance, etc. are further improved without impairing the storage stability.

[0052] Furthermore, if necessary, a lubricant such as wax can be added to the emulsion-type anionic electrodeposition paint of the present invention for the purpose of preventing scratches on the coating film. Suitable waxes include animal and vegetable waxes such as carnauba wax, lanolin wax, palm oil, candelilla wax, and rice wax, petroleum waxes such as paraffin wax, microcrystalline wax, and petrolatum, and synthetic waxes such as polyolefin wax and polytetrafluoroethylene (PTFE) wax.

[0053] The electrodeposition coating of the present invention may contain curing catalysts, leveling agents, antifoaming agents, surfactants, preservatives, mildew inhibitors, rust inhibitors, pH adjusters, etc., depending on the purpose and application, in order to improve the coatability and physical properties of the coating film formed.

[0054] The electrodeposition coating of the present invention can also contain colorants such as pigments and dyes. Examples of pigments include chromatic pigments (e.g., quinacridone, phthalocyanine, and azo pigments) and achromatic pigments (e.g., titanium oxide, iron oxide, aluminum, and carbon black). These pigments can be used alone or in combination of two or more.

[0055] <Electrical conductivity> It is important that the electrical conductivity of the electrodeposition paint of the present invention is 300 to 1200 μS / cm at a paint temperature of 25° C., more preferably 350 to 1100 μS / cm, and particularly preferably 350 to 1000 μS / cm. If the electrical conductivity is 300 μS / cm or more, the resulting composite resin (C) will have excellent dispersion stability in the electrodeposition coating material, and the storage stability and smoothness of the coating film obtained by electrodeposition coating will be excellent. Furthermore, if the current is 1200 μS / cm or less, excessive current flow during electrodeposition coating is suppressed, and gas generation due to electrolysis of water is suppressed, thereby suppressing the occurrence of coating defects such as gas pinholes, dents, and popping, resulting in a better coating surface appearance. The electrical conductivity can be measured using a commercially available electrical conductivity meter in accordance with JIS K 0130 (general rules for measuring electrical conductivity). The electrical conductivity can be controlled by, for example, the amount of the basic compound used to neutralize the carboxyl group or the amount of the organic solvent (D) added, and can be increased by increasing the amount of the basic compound or decreasing the amount of the organic solvent (D).On the other hand, the electrical conductivity decreases by decreasing the amount of the basic compound or increasing the amount of the organic solvent (D).

[0056] The emulsion-type electrodeposition paint of the present invention is prepared by partially or completely neutralizing the carboxyl groups present in the synthesized composite resin (C), adding water with stirring to form an emulsion, and then adding an organic solvent (D) and, if necessary, a curing agent, etc., followed by stirring and mixing. The organic solvent (D) and curing agent, etc., can also be added before adding water. The nonvolatile content is preferably 1 to 20% by mass, more preferably 1 to 15% by mass.

[0057] Using the electrodeposition coating of the present invention, the resin component of the coating is deposited on the substrate by a general anionic electrodeposition coating method, and then the substrate is baked to form a coating film on the substrate. In anionic electrodeposition, for example, the substrate is completely or partially immersed in an electrodeposition bath filled with the electrodeposition paint to serve as the anode, and a counter electrode is immersed therein to apply a voltage between them to perform electrodeposition coating. The substrate, to which the electrodeposition paint and its resin component are attached, is then removed and the excess electrodeposition paint is washed off in a water bath, after which the substrate is baked to obtain an anionic electrodeposition coated article. There are no particular restrictions on the coating conditions for anionic electrodeposition coating, and they can be adjusted appropriately depending on the type and shape of the object to be coated, the properties of the electrodeposition paint, the size and shape of the electrodeposition bath, the use and purpose of the object to be coated, etc. Examples of conditions include a liquid temperature of the electrodeposition paint of 10 to 50°C, an applied voltage of 1 to 400 V, and an electrodeposition time of 10 seconds to 30 minutes. After painting, the applied resin component is heated to bake in. Heating may be performed all at once at 140 to 250°C, or a step of pre-drying at 60 to 130°C for 3 to 60 minutes and then baking at 140 to 250°C is also preferred. The thickness of the coating film formed is about 1 μm to 150 μm.

[0058] The electrodeposition paint of the present invention is used for the purpose of forming a coating film that covers a substrate. The substrate is a metal substrate that can be electrodeposited, and preferred examples include metal materials such as iron, aluminum or anodized aluminum, copper, nickel, stainless steel, magnesium, plated materials or plated articles, and die-cast metals. Electrodeposition-coated articles can be used, for example, for electronic parts, automobile parts, and building materials. [Example]

[0059] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. In the examples, "parts" means parts by mass, and "%" means % by mass, unless otherwise specified.

[0060] (Measurement conditions for weight average molecular weight) Measurements were performed using a high-speed GPC system, 8020 series (THF (tetrahydrofuran) solvent, column temperature 40°C, polystyrene standard) manufactured by Tosoh Corporation. Specifically, the measurements were performed using four columns, G1000HXL, G2000HXL, G3000HXL, and G4000HXL manufactured by Tosoh Corporation, connected in series at a flow rate of 1.0 ml / min.

[0061] (Conditions for measuring electrical conductivity) The electrical conductivity of the electrodeposition paint at 25°C was measured using a portable electrical conductivity / pH meter WM-32EP manufactured by DKK-TOA Corporation.

[0062] [Manufacturing Example 1] <Synthesis of acrylic polymer (B1)> A reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet tube was charged with 146 parts of n-butyl alcohol and heated to 100°C under a nitrogen atmosphere with stirring. A mixture of 60 parts of methacrylic acid, 10 parts of styrene, 30 parts of ethyl acrylate, 62 parts of ethylene glycol monobutyl ether, and 1.4 parts of benzoyl peroxide (initial amount) was continuously added dropwise from the dropping tank over 2 hours to polymerize. Benzoyl peroxide (0.14 parts) was added in an amount 1 / 10 of the initial amount 1 hour, 2 hours, and 3 hours after the completion of the dropwise addition, and the reaction was continued for 4 hours after the completion of the dropwise addition. Next, 90 parts of ethylene glycol monobutyl ether was added and cooled to obtain a solution of acrylic polymer (B1) (nonvolatile content 25%) with an acid value of 391 mgKOH / g, a weight-average molecular weight of 25,000, and a glass transition temperature of 67°C. The glass transition temperatures were calculated using the Fox equation. The glass transition temperatures of the homopolymers used in the calculation were 130°C for methacrylic acid, 100°C for styrene, -20°C for ethyl acrylate, and 105°C for methyl methacrylate.

[0063] [Manufacturing Examples 2 to 4, 101] <Synthesis of acrylic polymers (B2) to (B4) and (B101)> The synthesis method was the same as in Production Example 1, except that the raw materials and blending amounts in Production Example 1 were changed to the raw materials and blending amounts shown in Table 1, and solutions of acrylic polymers (B2) to (B4) and (B101) were obtained (non-volatile content concentration 25%).

[0064] [Manufacturing Example 5] <Synthesis of acrylic polymer (B5)> A reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet tube was charged with 87.5 parts of n-butyl alcohol and heated to 100°C under a nitrogen atmosphere with stirring. A mixture of 5 parts of methacrylic acid, 3 parts of styrene, 92 parts of ethyl acrylate, 15 parts of ethylene glycol monobutyl ether, and 0.6 parts of benzoyl peroxide (initial amount) was continuously added dropwise from the dropping tank over 2 hours to polymerize. Benzoyl peroxide (0.06 parts) was added in an amount 1 / 10 of the initial amount 1 hour, 2 hours, and 3 hours after the completion of the dropwise addition, and the reaction was continued for 4 hours after the completion of the dropwise addition. Next, 47.5 parts of ethylene glycol monobutyl ether was added and cooled to obtain a solution of acrylic polymer (B5) (nonvolatile content 40%) with an acid value of 33 mgKOH / g, a weight-average molecular weight of 42,000, and a glass transition temperature of -13°C.

[0065] [Manufacturing Examples 6, 7, and 102] <Synthesis of acrylic polymers (B6), (B7), and (B102)> The synthesis method was the same as in Production Example 5, except that the raw materials and blending amounts in Production Example 5 were changed to those shown in Table 1, and solutions of acrylic polymers (B6), (B7), and (B102) were obtained, respectively (non-volatile content concentration 40%).

[0066] [Table 1]

[0067] <Synthesis of emulsion-type anionic electrodeposition paint> [Example 1] A reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube was charged with 74.3 parts of epoxy resin (A1) (Mitsubishi Chemical Corporation, jER1009), 31 parts of acrylic polymer (B5) solution (acrylic polymer (B-2): containing 12.4 parts of nonvolatiles), 4 parts of n-butyl alcohol, and 27 parts of ethylene glycol monobutyl ether. The mixture was heated to 120 ° C under a nitrogen gas atmosphere and stirred to completely dissolve the epoxy resin. The mixture was then cooled to 70 ° C, and 3.5 parts of dimethylaminoethanol was added while maintaining the temperature at 70 ° C. The mixture was then reacted for 1 hour. Next, 49.5 parts of acrylic polymer (B1) solution (acrylic polymer (B-1): containing 12.4 parts of nonvolatiles) was added, and the mixture was further reacted for 3 hours to obtain a composite resin. After that, 809.5 parts of ion-exchanged water was gradually added dropwise over 1 hour, and then 1.3 parts of Phenodur PR411 (manufactured by Allnex, phenolic resin solution: non-volatile content 75%) was added as a curing agent to obtain an emulsion-type anionic electrodeposition paint with a non-volatile content of 10.0%. The epoxy resin (A1), acrylic polymer (B1), and acrylic polymer (B5) used in the reaction were in a mass ratio of 75:12.5:12.5.

[0068] [Examples 2 to 12, 14 to 18], [Comparative Examples 1 to 6] The emulsion-type anionic electrodeposition paints shown in Table 2 were obtained in the same manner as in Example 1, except that the raw materials and blending amounts in Example 1 were changed to those shown in Table 2.

[0069] [Example 13] A reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet was charged with 74.3 parts of epoxy resin (A1) (Mitsubishi Chemical Corporation, jER1009), 99 parts of acrylic polymer (B1) solution (acrylic polymer (B-1): containing 24.8 parts nonvolatile content), 4 parts of n-butyl alcohol, and 27 parts of ethylene glycol monobutyl ether. The mixture was heated to 120°C under a nitrogen gas atmosphere and stirred to completely dissolve the epoxy resin. The mixture was then cooled to 70°C, and 5.0 parts of dimethylaminoethanol was added while maintaining the temperature at 70°C. The mixture was then allowed to react for 3 hours to obtain a composite resin. 789.4 parts of ion-exchanged water was then added dropwise over 1 hour, followed by the addition of 1.3 parts of Phenodur PR411 (Allnex, phenolic resin solution: nonvolatile content 75%) as a curing agent, yielding an emulsion-type anionic electrodeposition paint with a nonvolatile content of 10.0%. The epoxy resin (A1) and the acrylic polymer (B1) used in the reaction were in a mass ratio of 75:25.

[0070] [Example 19] A reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet tube was charged with 74.3 parts of epoxy resin (A1) (Mitsubishi Chemical Corporation, jER1009), 31 parts of acrylic polymer (B5) solution (acrylic polymer (B-2): containing 12.4 parts of nonvolatile matter), 4 parts of n-butyl alcohol, and 27 parts of ethylene glycol monobutyl ether. The mixture was heated to 120°C under a nitrogen gas atmosphere and stirred to completely dissolve the epoxy resin. The mixture was then cooled to 70°C, and 3.5 parts of dimethylaminoethanol was added while maintaining the temperature at 70°C. The mixture was then allowed to react for 1 hour. The mixture was then heated to 100°C, and a mixture of 7.44 parts of methacrylic acid, 1.24 parts of styrene, 3.72 parts of ethyl acrylate, 18.8 parts of ethylene glycol monobutyl ether, and 0.4 parts of benzoyl peroxide was added dropwise from the dropping tank over 1 hour. One hour after the completion of the dropwise addition, 0.04 parts of benzoyl peroxide was added, and the reaction was continued for two hours after the completion of the dropwise addition. After that, 18.3 parts of n-butyl alcohol was added, and then 809.5 parts of ion-exchanged water was gradually added dropwise over one hour, after which 1.3 parts of Phenodur PR411 (Allnex, phenolic resin solution: non-volatile content 75%) was added as a curing agent, to obtain an emulsion-type anionic electrodeposition paint with a non-volatile content of 10.0%.

[0071] [Example 20] A reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet tube was charged with 74.3 parts of epoxy resin (A1) (Mitsubishi Chemical Corporation, jER1009), 31 parts of acrylic polymer (B5) solution (acrylic polymer (B-2): containing 12.4 parts of nonvolatiles), 4 parts of n-butyl alcohol, and 27 parts of ethylene glycol monobutyl ether. The mixture was heated to 120 ° C under a nitrogen gas atmosphere and stirred to completely dissolve the epoxy resin. The mixture was then cooled to 70 ° C, and 3.5 parts of dimethylaminoethanol was added while maintaining the temperature at 70 ° C. The mixture was then reacted for 1 hour. The mixture was then heated to 100 ° C, and 0.004 parts of hydroquinone, 0.06 parts of 25% aqueous sodium hydroxide, and 0.30 parts of methacrylic acid were added, followed by stirring at 100 ° C. for 3 hours. Next, a mixture of 7.14 parts methacrylic acid, 1.24 parts styrene, 3.72 parts ethyl acrylate, 18.8 parts ethylene glycol monobutyl ether, and 0.4 parts benzoyl peroxide was added dropwise from the dropping tank over one hour. One hour after the completion of the addition, 0.04 parts benzoyl peroxide was added, and the reaction was continued for two hours. After that, 18.3 parts of n-butyl alcohol was added, and 809.5 parts of ion-exchanged water was gradually added dropwise over one hour. Then, 1.3 parts of Phenodur PR411 (Allnex, phenolic resin solution: nonvolatile content 75%) was added as a curing agent, resulting in an emulsion-type anionic electrodeposition paint with a nonvolatile content of 10.0%.

[0072] [Table 2]

[0073] In Tables 2 and 3, the symbols are as follows: "BPA" stands for bisphenol A, and "BPF" stands for bisphenol F. Epoxy resin A1: jER1009 (Mitsubishi Chemical Corporation, BPA-type epoxy resin, epoxy equivalent: 2,400 to 3,300, weight-average molecular weight: approximately 20,000) Epoxy resin A2: jER1007 (Mitsubishi Chemical Corporation, BPA-type epoxy resin, epoxy equivalent: 1,750 to 2,200, weight-average molecular weight: approximately 11,000) Epoxy resin A3: jER4250 (Mitsubishi Chemical Corporation, BPA / BPF mixed phenoxy resin, epoxy equivalent: 7,500-8,900, weight average molecular weight: approximately 60,000) Phenolic resin: PHENODUR PR411 / 75B (manufactured by Allnex, resol-type phenolic resin, non-volatile content 75%) Amino resin: CYMEL303LF (Allnex, methylated melamine resin, non-volatile content 98% or more)

[0074] <Storage stability> The resulting emulsion-type anionic electrodeposition paint was left to stand in an incubator at 37°C for one month, and then its appearance was evaluated. ○ Good storage stability × Abnormalities such as gelation, sedimentation, and separation occur

[0075] [Anion electrodeposition coating] The resulting anionic electrodeposition paint was placed in a tank, a SUS304 steel plate was used as the cathode, and an aluminum material (10 cm x 10 cm x 0.30 mm thick) was immersed as the substrate. Anionic electrodeposition coating was performed at a liquid temperature of 25°C by adjusting the voltage and coating time so that the dried coating film would have a thickness of 15 μm, and excess paint was washed off in a water bath. After drying at 80°C for 20 minutes, it was baked at 200°C for 10 minutes to prepare an electrodeposition-coated panel for evaluation, and the physical properties of the coating film were tested.

[0076] <Paint appearance> The surfaces of the electrodeposition coated plates obtained above were visually evaluated according to the following criteria. A: No problems, good. B: The coating is slightly uneven, but this does not pose any problems for practical use. C: The coating film shows signs of pinholes, cracks, and a decrease in smoothness. Not suitable for practical use.

[0077] <Adhesion to substrate (cross-cut peel test)> Eleven perpendicular scratches were made at 1 mm intervals on the coating of the resulting electrodeposition-coated plate with a cutter knife so that they reached the substrate. Cellophane tape was then adhered to the scratches and peeled off, and the state of peeling of the coating was observed. A: No peeling at all B: Peeling occurred over an area of ​​less than 5%. No practical problems. C: Peeling occurred over an area of ​​more than 5%. Unsuitable for practical use.

[0078] <Thermal shock resistance> Using an Espec TSE-12-A thermal shock tester, electrodeposition-coated panels were cooled to -40°C for 15 minutes, then immediately heated to 180°C and held there for 15 minutes. This constituted one cycle, and 500 consecutive cycles of thermal shock testing were performed. The surface condition of the coated panels after the test was evaluated visually. A: No abnormalities in appearance, good condition. B: Slight foaming of the coating film is observed, but this does not pose a problem in practical use. C: Significant bubbling and cracking of the coating film was observed. Not suitable for practical use.

[0079] <Water resistance> The electrodeposition coated panels were immersed in water and subjected to boiling treatment at 100°C for 2 hours, and the surface condition of the coating film after treatment was evaluated visually. A: No change from untreated coating. B: Some whitening is observed, but this does not pose a problem in practical use. C: Significant whitening and blisters are observed. Not suitable for practical use.

[0080] <Corrosion resistance> The resulting electrodeposition-coated panels were subjected to a corrosion resistance test using the cyclic corrosion test method (JIS K 5600-7-9), and the surface condition of the coating film after the test was visually evaluated. Specifically, the electrodeposition-coated panels were scored diagonally and placed in a cycle tester, and then subjected to a salt spray test with a 5% sodium chloride solution at 35°C for 2 hours. Immediately, the panels were dried at 60°C and 20 to 30% RH for 4 hours, and then immediately wetted at 50°C and 95% RH or higher for 2 hours. This cycle (8 hours) constituted one cycle, and the corrosion resistance test was performed for 60 consecutive cycles (480 hours). A: No abnormalities in appearance, good condition. B: Some whitening is observed, but this does not pose a problem in practical use. C: Peeling of the coating, significant whitening, blisters, corrosion of the base material, etc. are observed. Not suitable for practical use.

[0081] Tables 3 and 4 show the compositions of the emulsion-type anionic electrodeposition paints obtained in Examples 1 to 20 and Comparative Examples 1 to 6, and the evaluation results of the physical properties of the coating films obtained from these emulsion-type anionic electrodeposition paints.

[0082] [Table 3]

[0083] [Table 4]

[0084] As shown in Table 3, the emulsion-type anionic electrocoating paints of Examples 1 to 20 had good physical properties in all respects, whereas the emulsion-type anionic electrocoating paints of Comparative Examples 1 to 6 had poor physical properties in one respect or another, and no paints were found to have good properties in all respects.

Claims

1. The emulsion-type anionic electrodeposition paint contains a composite resin (C) having an epoxy resin (A) portion and a carboxyl group-containing acrylic polymer (B) portion including a (B-1) portion having a glass transition temperature (Tg) of 40 to 130°C, water, and an organic solvent (D), and has an electrical conductivity of 300 to 1200 μS / cm.

2. The emulsion-type anionic electrodeposition paint according to claim 1, wherein the carboxyl group-containing acrylic polymer (B) comprises a (B-1) portion having a glass transition temperature (Tg) of 40 to 130°C and a (B-2) portion having a glass transition temperature (Tg) of -20 to 30°C.

3. 3. The emulsion type anionic electrodeposition paint according to claim 1 or 2, which contains 3.0 to 20.0 mass % of the organic solvent (D).

4. 4. The emulsion type anionic electrodeposition paint according to claim 1, wherein the organic solvent (D) comprises an organic solvent (D-1) having a boiling point of 120 to 250°C.

5. 5. The emulsion type anionic electrodeposition paint according to claim 1, wherein the epoxy resin (A) is formed from a bisphenol type epoxy resin.

6. A coating method for electrodeposition coating a metal substrate with the emulsion type anionic electrodeposition coating material according to any one of claims 1 to 5.

7. A method for producing a coated article, comprising electrodeposition coating a metal substrate with the emulsion-type anionic electrodeposition paint according to any one of claims 1 to 5, and heating the substrate at 140 to 250°C.

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