Epoxy resins and electrodeposition paints

Abstract

To provide an epoxy resin which is excellent in curability when a catalyst having low activity is used and when a temperature is low and storage stability, and is excellent in coating film finishing property and corrosion resistance when constituting a coating, an amine-modified epoxy resin obtained by reacting the epoxy resin and an amine compound, and a cation electro-deposition coating containing the amine-modified epoxy resin.SOLUTION: An epoxy-based resin is obtained by reacting at least a compound having one or more epoxy groups, and a multi-functionalizing agent containing a compound (A) having a pieces of primary amino groups, b pieces of secondary amino groups, c pieces of alcoholic hydroxyl groups, d pieces of phenolic hydroxyl groups, e pieces of carboxyl groups, f pieces of mercapto groups, g pieces of sulfonic acid groups, h pieces of carboxylic acid anhydride groups and i pieces of epoxy groups (a, b, c, d, e, f, g and h are each independently an integer of 0 or more, i is an integer of 0 or 3 or more, and 2a+b+c+d+e+f+g+2h+i≥3, in the case of b=1, a≠1, c≠2 or d+e+f+g+2h+i≥1, and in the case of d≥3, 2a+b+d+e+f+g+2h+i≥1).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to epoxy resins and electrodeposition paints. Specifically, it relates to: (i) an epoxy resin obtained by reacting specific components, (ii) an epoxy resin having specific properties, (iii) an electrodeposition paint containing the epoxy resin or a modified product thereof, (iv) an amine-modified epoxy resin obtained by reacting the epoxy resin with an amine compound, and (v) a cationic electrodeposition paint containing the amine-modified epoxy resin and a bismuth compound.

Background Art

[0002] Epoxy resins are excellent in properties such as mechanical strength, adhesiveness, and chemical resistance, and are widely used as coating film-forming resins for paints. Among paints, electrodeposition paints are widely used for coating metal products (for example, automotive parts, electrical equipment parts, and other industrial equipment, etc.) that require these performances because of their excellent coating workability and good corrosion resistance of the formed coating film.

[0003] An electrodeposition paint is provided in a form in which a coating film-forming resin that is a cationic resin (for example, an amine-modified epoxy resin, etc.) or an anionic resin (for example, a resin containing a carboxyl group, etc.), a curing agent (for example, a blocked polyisocyanate compound, etc.), and a curing catalyst are dissolved or dispersed in an aqueous medium. This paint composition is used in a coating bath, an electric current is passed with the object to be coated as the cathode or anode, and after a deposited coating film is formed on the object to be coated, the deposited coating film is heated to form a crosslinked and cured coating film.

[0004] In electrodeposition paints, organic tin compounds have generally been used as curing catalysts that promote crosslinking reactions. However, although organic tin compounds have very high catalytic performance, there are problems in terms of safety and the environment and their use may be restricted, and thus catalysts to replace organic tin compounds have been demanded. As alternatives, the use of bismuth compounds, zinc compounds, etc. has been studied, but there have been problems such as being expensive, having insufficient catalytic effects, and being unstable in the paint. Furthermore, even when using organotin compound catalysts, it was necessary to maximize the hardening performance.

[0005] Typically, coating film formation by cross-linking curing is achieved by heating to 160°C or higher. However, depending on the conditions of the drying oven and the shape of the object to be coated, some parts may be baked at a lower temperature than the target temperature. Furthermore, in order to reduce energy costs, there is a growing demand for low-temperature baking (80-160°C, preferably 80-130°C). To perform low-temperature curing, it has been common practice to use low-temperature curable blocked polyisocyanate compounds as curing agents. However, electrodeposition coatings with enhanced low-temperature reactivity often suffer from insufficient long-term storage stability (bath stability), resulting in inferior finish and corrosion resistance of the coating film.

[0006] Patent Document 1 describes polyfunctionalized epoxy resins. However, these epoxy resins are not intended for use in electrodeposition coatings. Furthermore, their curability, particularly when using low-activity catalysts, and the storage stability of the coatings have not been investigated. Patent documents 2 and 3 describe electrodeposition coatings using amine-modified epoxy resins, which are epoxy resins modified with caprolactone adducts or phenolic compounds. However, the curing characteristics, particularly low-temperature curing properties and storage stability of these electrodeposition coatings, have not been investigated. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Chinese Patent Application Publication No. 104628995 Specification [Patent Document 2] Japanese Patent Publication No. 2016-135848 [Patent Document 3] Japanese Patent Publication No. 2001-279168 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide an epoxy resin that exhibits excellent curability when using a low-activity catalyst or at low temperatures, as well as excellent storage stability, and that provides excellent coating finish and corrosion resistance when used in paints. Furthermore, the invention aims to provide an electrodeposition paint containing the epoxy resin or a modified version thereof, an amine-modified epoxy resin obtained by reacting the epoxy resin with an amine compound, and a cationic electrodeposition paint containing the amine-modified epoxy resin. [Means for solving the problem]

[0009] As a result of diligent research to solve the above problems, the inventors have found that the above problems can be solved by an epoxy resin obtained by reacting specific components, an epoxy resin having specific properties, an electrodeposition coating containing any of the above epoxy resins or a modified version thereof, an amine-modified epoxy resin obtained by reacting any of the above epoxy resins with an amine compound, and a cationic electrodeposition coating containing the amine-modified epoxy resin and a bismuth compound, and have completed the present invention.

[0010] Specifically, it is as follows: [Item 1] A compound having one or more epoxy groups, A polyfunctionalizing agent containing compound (A) having a primary amino group, b secondary amino groups, c alcoholic hydroxyl groups, d phenolic hydroxyl groups, e carboxyl groups, f mercapto groups, g sulfonic acid groups, h carboxylic acid anhydride groups, and i epoxy groups (where a, b, c, d, e, f, g, and h are each independent integers of 0 or more, and i is 0 or an integer of 3 or more, such that 2a+b+c+d+e+f+g+2h+i≧3. If b=1, then a≠1, c≠2, or d+e+f+g+2h+i≧1. If d≧3, then 2a+b+d+e+f+g+2h+i≧1. An epoxy resin obtained by at least reacting the following. [Item 2] A compound having one or more epoxy groups, A polyfunctionalizing agent containing compound (A) having a primary amino group, b secondary amino group, c alcoholic hydroxyl group, d phenolic hydroxyl group, e carboxyl group, f mercapto group, g sulfonic acid group, h carboxylic acid anhydride group, and i epoxy group (where a, b, c, d, e, f, g, and h are each independent integers of 0 or more, and i is 0 or an integer of 3 or more, such that 2a+b+c+d+e+f+g+2h+i≧3. If d≧3, then 2a+b+d+e+f+g+2h+i≧1. It is obtained by at least the following reaction, as shown in formula (1); (1): Average degree of polyfunctionalization (X1) = Number of terminals per molecule of epoxy resin - 2 An epoxy resin having an average polyfunctionalization degree (X1) per molecule of the epoxy resin indicated by 0.1 or higher. [Item 3] The following formula (2); (2): Average polyfunctionalization concentration (Y1) = Average polyfunctionalization degree of epoxy resin (X1) ÷ Weight-average molecular weight of epoxy resin Mw × 1000 The epoxy resin described in item 2, wherein the average polyfunctionalization concentration (Y1) shown is 0.10 or higher. [Item 4] The epoxy resin according to any one of items 1 to 3, wherein the polyfunctionalizing agent contains one or more selected from the group consisting of an amine compound having two or more amino groups, a carboxylic acid compound having three or more carboxyl groups or its anhydride, an alcohol compound having three or more alcoholic hydroxyl groups, and an epoxy compound having three or more epoxy groups. [Item 5] The epoxy resin according to any one of Items 1 to 4, wherein the polyfunctionalizing agent further comprises compound (B) having j primary amino groups, k secondary amino groups, m alcoholic hydroxyl groups, n phenolic hydroxyl groups, p carboxyl groups, q mercapto groups, r sulfonic acid groups, s carboxylic acid anhydride groups, and t isocyanate groups (where j, k, m, n, p, q, r, and s are each independent integers of 0 or more, and 2j+k+m+n+p+q+r+2s≦2), and the content ratio of compound (A) to compound (B) is in the range of 1 / 99 to 99 / 1. [Item 6] An aqueous resin dispersion in which an epoxy resin described in any of Items 1 to 5 is dispersed in an aqueous medium. [Item 7] An electrodeposition coating comprising an epoxy resin or a modified thereof as described in any of Items 1 to 5. [Item 8] An amine-modified epoxy resin obtained by reacting an epoxy resin described in any of Items 1 to 5 with an amine compound. [Item 9] A cationic electrodeposition coating comprising the amine-modified epoxy resin described in Item 8, a curing agent, and a bismuth compound. [Effects of the Invention]

[0011] The epoxy resins and amine-modified epoxy resins of the present invention exhibit excellent curability when using low-activity catalysts or at low temperatures, as well as storage stability, and provide excellent coating finish and corrosion resistance when used in paints. Furthermore, the electrodeposition coating of the present invention exhibits excellent curability, storage stability, coating film finish, and corrosion resistance, even when using a low-activity catalyst or at low temperatures. [Modes for carrying out the invention]

[0012] In this invention, "epoxy resin" refers to both a resin having epoxy groups and a resin obtained by the reaction of the epoxy groups of the epoxy resin with other functional group-containing compounds, and does not necessarily have to contain epoxy groups. That is, in this invention, "epoxy resin" means an epoxy resin having epoxy groups and / or a modified epoxy resin that does not have epoxy groups. Also, "epoxy" may be abbreviated as "EP". In the present invention, "polyfunctional" means that the number of functional groups is greater than 2. However, in the present invention, even if there are two or more functional groups generated and / or introduced by the reaction of the terminal epoxy group of the epoxy resin with the reactive functional group-containing compound, the number of functional groups in this terminal portion is counted as 1. Further, with regard to the secondary hydroxyl group inside the epoxy resin molecule, since its reactivity is low, it shall not be included in the number of the above functional groups. In the present invention, the "functional group" in polyfunctional substantially refers to a reactive functional group that can react with a curing agent such as a blocked polyisocyanate compound.

[0013] [Epoxy resin] <Epoxy resin according to the first aspect> The epoxy resin according to the first aspect of the present invention is a compound having one or more epoxy groups, and a polyfunctionalizing agent containing a compound (A) having a primary amino group a, a secondary amino group b, an alcoholic hydroxyl group c, a phenolic hydroxyl group d, a carboxyl group e, a mercapto group f, a sulfonic acid group g, a carboxylic anhydride group h, and an epoxy group i (a, b, c, d, e, f, g, and h are each independently an integer of 0 or more, i is 0 or an integer of 3 or more, and 2a + b + c + d + e + f + g + 2h + i ≧ 3. When b = 1, either a ≠ 1, c ≠ 2 or d + e + f + g + 2h + i ≧ 1. When d ≧ 3, 2a + b + d + e + f + g + 2h + i ≧ 1.), and <null>is an epoxy resin obtained by reacting at least. In the reaction, if necessary, a compound having one or more active hydrogens in one molecule other than the compound (A) and / or a polyisocyanate compound can be further reacted. The epoxy resin according to the first aspect of the present invention is excellent in its curability, particularly in the curability when using a low-activity catalyst and in the curability at low temperatures, and in storage stability. Further, when an electrodeposition paint is prepared using the epoxy resin, the finish and corrosion resistance of the coating film are excellent.

[0014] (Compound having one or more epoxy groups) A compound having one or more epoxy groups (epoxy compound) is a compound having at least one epoxy group, preferably two or more, in one molecule. In the present invention, the number of epoxy groups in one molecule of an epoxy compound is preferably 2 to 8, more preferably 2 to 6, even more preferably 2 to 4, and most preferably 2. When using an epoxy compound having three or more epoxy groups as a polyfunctionalizing agent, a compound having one or two epoxy groups is used. The weight-average molecular weight of the epoxy compound is not particularly limited, but it is preferable to have one that is at least 300, preferably 400 to 4,000, and more preferably 800 to 2,500. Similarly, the epoxy equivalent is not particularly limited, but it is suitable to have one that is at least 160, preferably 180 to 2,500, and more preferably 400 to 1,500. As the epoxy compound, one or more selected from the group consisting of, for example, epoxy compounds obtained by the reaction of a polyphenol compound with an epihalohydrin (such as epichlorohydrin), epoxy compounds containing a polyalkylene oxide chain in the molecule, and diglycidyl dimer acid esters can be used. In the present invention, epoxy compounds obtained by the reaction of polyphenol compounds with epihalohydrins are preferably used.

[0015] Any known polyphenol compound can be used without limitation to react with the epihalohydrin. For example, one or more substances selected from the group consisting of bis(4-hydroxyphenyl)-2,2-propane [bisphenol A], bis(4-hydroxyphenyl)methane [bisphenol F], bis(4-hydroxycyclohexyl)methane [hydrogenated bisphenol F], 2,2-bis(4-hydroxycyclohexyl)propane [hydrogenated bisphenol A], 4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-1,1-isobutane, bis(4-hydroxy-3-tert-butyl-phenyl)-2,2-propane, bis(2-hydroxynaphthyl)methane, tetra(4-hydroxyphenyl)-1,1,2,2-ethane, 4,4'-dihydroxydiphenylsulfone, α,α,α'-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene, phenol novolac, cresol novolac, etc. can be used.

[0016] As the epoxy compound, an epoxy compound containing a polyalkylene oxide chain in its molecule can be used. Typically, such an epoxy compound can be obtained by (α) reacting an epoxy compound having at least one, preferably two or more epoxy groups with an alkylene oxide or polyalkylene oxide to introduce a polyalkylene oxide chain, or by (β) reacting the above-mentioned polyphenol compound with a polyalkylene oxide having at least one, preferably two or more epoxy groups to introduce a polyalkylene oxide chain. Alternatively, an epoxy compound that already contains a polyalkylene oxide chain may be used (see, for example, Japanese Patent Application Publication No. 8-337750). The alkylene group in the polyalkylene oxide chain is preferably an alkylene group having 2 to 8 carbon atoms, more preferably an ethylene group, a propylene group, or a butylene group, and particularly preferably a propylene group. The content of the polyalkylene oxide chain described above is, from the viewpoint of improving stability, finish, and corrosion resistance during electrodeposition coating formation, typically within the range of 1.0 to 15% by mass, preferably 2.0 to 9.5% by mass, and more preferably 3.0 to 8.0% by mass, based on the solid content mass of the epoxy resin.

[0017] Diglycidyl dimer acid esters can be used as epoxy compounds. Such epoxy compounds are obtained by introducing a glycidyl group to a dimer acid obtained by dimerizing an unsaturated fatty acid, and preferably have linear, branched, and / or cyclic hydrocarbon groups having 10 to 150 carbon atoms. While any known unsaturated fatty acid can be used without limitation, higher unsaturated fatty acids with 11 to 22 carbon atoms are preferred from the viewpoint of the flexibility and hydrophobicity of the epoxy compound. As the above-mentioned higher unsaturated fatty acids, any known fatty acids can be used without limitation. Specifically, for example, one or more fatty acids selected from the group consisting of oleic acid, linoleic acid, linolenic acid, eicosenoic acid, docosenoic acid, branched octadecenoic acid, branched hexadecenoic acid, undecylenic acid, etc., can be used.

[0018] In the present invention, it is preferable to use one or more epoxy compounds obtained by reacting an epihalohydrin with one or more selected from bis(4-hydroxyphenyl)-2,2-propane [bisphenol A], bis(4-hydroxyphenyl)methane [bisphenol F], bis(4-hydroxycyclohexyl)methane [hydrogenated bisphenol F], 2,2-bis(4-hydroxycyclohexyl)propane [hydrogenated bisphenol A], 4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-1,1-isobutane, bis(4-hydroxy-3-tert-butyl-phenyl)-2,2-propane, bis(2-hydroxynaphthyl)methane, tetra(4-hydroxyphenyl)-1,1,2,2-ethane, 4,4'-dihydroxydiphenylsulfone, phenol novolac, and cresol novolac.

[0019] Particularly preferred is an epoxy compound obtained by the reaction of a polyphenol compound with an epihalohydrin (e.g., epichlorohydrin), wherein the following formula is derived from bisphenol A. [ka] Examples of commercially available products include those sold by Mitsubishi Chemical Corporation under the product names jER828EL, jER1002, jER1004, and jER1007. As mentioned above, secondary hydroxyl groups within the epoxy resin molecule in the above formula are not included as functional groups in the polyfunctional category. Furthermore, in a modified epoxy resin obtained by the reaction of, for example, the terminal epoxy group of the above formula with a reactive functional group-containing compound, the hydroxyl groups that appear as a result of the reaction of the epoxy group are also not included as functional groups in the polyfunctional category in this invention.

[0020] (Multifunctionalizing agent) The polyfunctionalizing agent contains compound (A) having a primary amino group, b secondary amino groups, c alcoholic hydroxyl groups, d phenolic hydroxyl groups, e carboxyl groups, f mercapto groups, g sulfonic acid groups, h carboxylic acid anhydride groups, and i epoxy groups (where a, b, c, d, e, f, g, and h are each independent integers of 0 or more, and i is 0 or an integer of 3 or more, such that 2a+b+c+d+e+f+g+2h+i≧3. If b=1, then a≠1, c≠2, or d+e+f+g+2h+i≧1. If d≧3, then 2a+b+d+e+f+g+2h+i≧1). Of these, it is preferable that the polyfunctionalizing agent contains one or more selected from the group consisting of an amine compound having two or more primary amino groups, a carboxylic acid compound having three or more carboxyl groups or its anhydride, an alcohol compound having three or more alcoholic hydroxyl groups, and an epoxy compound having three or more epoxy groups.

[0021] Furthermore, the polyfunctionalizing agent may further contain compound (B) having j primary amino groups, k secondary amino groups, m alcoholic hydroxyl groups, n phenolic hydroxyl groups, p carboxyl groups, q mercapto groups, r sulfonic acid groups, and s carboxylic acid anhydride groups (where j, k, m, n, p, q, r, and s are each independent integers of 0 or more, and 2j+k+m+n+p+q+r+2s≦2). The content ratio of compound (A) to compound (B) is not particularly limited, but is preferably in the range of 1 / 99 to 99 / 1 (mass ratio).

[0022] Examples of amine compounds having two or more primary amino groups include ethylenediamine, p-diaminobenzene, m-diaminobenzene, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, diethylenetriamine, dipropylenetriamine, 2,2'-diaminodiethylamine, 3,3'-diamino-N-methyldipropylamine, 3,3'-diaminodipropylamine, bis(hexamethylene)triamine, 2,2'-bis(methylamino)-N-methyldiethylamine, triaminobenzene, triaminonaphthalene, tetraaminobenzene, tetraaminonaphthalene, triethylenetetramine, 3,3',4,4'-tetraaminodiphenyl ether, and 3,3',4,4'- One or more substances selected from the group consisting of tetraaminodiphenylsulfone, 3,3',4,4'-tetraaminodiphenylketone, 3,3',4,4'-tetraaminobiphenyl, 3,3',4,4'-tetraaminodiphenylmethane, 3,3',4,4'-tetraaminodiphenylcyclohexane, 3,3',4,4'-tetraaminodiphenylfluorene, 3,3',4,4'-tetraaminodiphenylthioether, 2,2-isopropylidenebis(3,4-diaminobenzene), 2,2-bis(3,4-diaminophenyl)propane, 2,2-hexafluoroisopropylidenebis(3,4-diaminobenzene), tetraethylenepentamine, pentaethylenehexamine, polyamidoamine, etc.

[0023] As an alcohol compound having three or more alcoholic hydroxyl groups, one or more can be selected from the group consisting of glycerin, diglycerin, trimethylolethane, trimethylolpropane, trioxyisobutane, butanetriol, pentanetriol, hexanetriol, sorbitol, polyoxypropylenetriol, polyoxyethylenetriol, polyoxyethylenepropylenetriol, pentaerythritol, dipentaerythritol, etc.

[0024] Examples of carboxylic acid compounds having three or more carboxyl groups or their anhydrides include butanetricarboxylic acid, pentanetricarboxylic acid, trimellitic acid, trimesic acid, naphthalentricarboxylic acid, butanetetracarboxylic acid, pentanetetracarboxylic acid, pyromellitic acid, cyclohexanetetracarboxylic acid, cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, dicyclohexyl-3,3',4,4'-tetracarboxylic acid, 4,4'-oxydiphthalic acid, benzophenonetetracarboxylic acid, bipheno One or more substances selected from the group consisting of nyltetracarboxylic acid, diphenylsulfontetracarboxylic acid, 2,2-bis(3,4-dicarboxyphenyl)propane, 2,2-bis(3,4-dicarboxyphenoxyphenyl)propane, 4,4'-(hexafluoroisopropylidene)diphthalic acid, 1,2-bis(2,3-dicarboxyphenyl)ethane, bis(dicarboxyphenyl)ethane, bis(3,4-dicarboxyphenyl)methane, 4,4'-(p-phenylenedioxy)diphthalic acid, dimer acids, and their anhydrides.

[0025] Examples of epoxy compounds having three or more epoxy groups include: epoxy resins obtained by glycidly modifying trisphenols such as 1,1,1-tris(4-hydroxyphenyl)methane, 4,4-(1-(4-(1-(4-hydroxyphenyl)-1-methylethyl)phenyl)ethylidene)bisphenol, and α,α,α'-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene; epoxy resins obtained by glycidly modifying tetrakisphenols such as 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane; and glycidly modifying novolacs such as phenol novolac, cresol novolac, bisphenol A novolac, brominated phenol novolac, and brominated bisphenol A novolac. One or more epoxy resins selected from the group consisting of: lac-type epoxy resins, etc.; epoxy resins obtained by glycidly modifying polyhydric phenols of pentavalent or higher; aliphatic ether-type epoxy resins obtained by glycidly modifying polyhydric alcohols such as glycerin, diglycerin, polyglycerin, and sorbitol; ester-type epoxy resins obtained by glycidly modifying polycarboxylic acids such as trimellitic acid, pyromellitic acid, and benzophenonetetracarboxylic acid; glycidyl-type epoxy resins such as glycidyl derivatives of amine compounds such as 3,3',4,4'-tetraaminodiphenylmethane and amine-type epoxy resins such as triglycidyl isocyanurate; and alicyclic epoxy resins such as 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate. Of these, one or more epoxy resins obtained by glycidly modifying phenols of trivalent or higher are preferred.

[0026] Furthermore, the compound may have a total of three or more primary amino groups, secondary amino groups, alcoholic hydroxyl groups, phenolic hydroxyl groups, carboxyl groups, mercapto groups, sulfonic acid groups, and carboxylic acid anhydride groups in its molecule. For example, one or more compounds selected from the group consisting of diaminobenzoic acid, dihydroxybenzoic acid, diaminophenol, diethanolamine, triethanolamine, etc.

[0027] (Compounds containing one or more active hydrogen atoms in a single molecule) The polyfunctionalizing agent may contain one or more compounds having one or more active hydrogen atoms in a single molecule, other than compound (A) which has a primary amino group, b secondary amino groups, c alcoholic hydroxyl groups, d phenolic hydroxyl groups, e carboxyl groups, f mercapto groups, g sulfonic acid groups, and h carboxylic acid anhydride groups. Examples include one or more compounds selected from the group consisting of diol compounds, dicarboxylic acid compounds, polyhydric phenolic compounds, etc.

[0028] As the diol compound, one or more selected from the group consisting of alkylene glycols (ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, etc.) can be used. As dicarboxylic acid compounds, one or more selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, phthalic acid, dimer acid, and their acid anhydrides can be used. Examples of polyhydric phenolic compounds include bis(4-hydroxyphenyl)-2,2-propane [bisphenol A], bis(4-hydroxyphenyl)methane [bisphenol F], bis(4-hydroxycyclohexyl)methane [hydrogenated bisphenol F], 2,2-bis(4-hydroxycyclohexyl)propane [hydrogenated bisphenol A], 4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-1,1-isobutane, and bis(4-hydroxy-3-tert-butane). 2-phenyl)-2,2-propane, bis(2-hydroxynaphthyl)methane, tetra(4-hydroxyphenyl)-1,1,2,2-ethane, 4,4'-dihydroxydiphenylsulfone, biphenol, pyrogallol, phloroglucinol, hydroxyhydroquinone, 5-methylpyrogallol, gallic acid, 1,8,9-trihydroxyanthracene, 4,4',4”-trihydroxytriphenylmethane, 4,4',4”-ethyridinetris(2-methylphenol), 4,4'-(2-hydroxybenzylidene)bis(2,3,6-trimethyl Phenol), 2,3,4-trihydroxydiphenylmethane, 2,4,6-tris(4-hydroxyphenyl)-1,3,5-triazine, 1,3,5-tris(4-hydroxyphenyl)benzene, 1,1,1-tris(4-hydroxyphenyl)ethane, 1,1,3-tris(4-hydroxyphenyl)propane, 4,4'-[1-[4-[1-(4-hydroxy-3,5-dimethylphenyl)-1-methylethyl]phenyl]ethylidene]bis(2-methylphenol), 4,4'-[1-[4-[1-(4-hydroxyphenyl)-1- [methylethyl]phenyl]ethylidene]bisphenol, 2,6-bis(4-hydroxy-3,5-dimethylbenzyl)-4-methylphenol, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)propane, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1-[α-methyl-α-(4-hydroxyphenyl)ethyl]-3-[α,α-bis(4-hydroxyphenyl)ethyl]benzene, 1-[α-methyl-α-(4-hydroxyphenyl)ethyl]-4-[α,α-bis(4-hydroxyphenyl)ethyl]benzene, α,α-bis(4-hydroxyphenyl)-4-(4-hydroxy-α,α-dimethylbenzyl)-ethylbenzene, 2,2'-methylenebis[6-(2-hydroxy-5-methylbenzyl)-p-cresol, 4-[bis(4-hydroxy-3-methylphenyl)methyl]benzene-1,2-diol, 1,1,2,2-tetrakis(p-hydroxyphenyl)ethane, α,α,α',α”-tetrakis(4-hydroxyphenyl)-p-xylene, 1,4,9,10-tetrahydroxyanthrate One or more of the following can be used: sen, 2,4,6-tris[(4-hydroxyphenyl)methyl]-1,3-benzenediol, hexahydroxybenzene, 2,3,6,7,10,11-hexahydroxytriphenylene hydrate, phenolic compounds (phenol, cresol, bisphenolic compounds, etc.) and aldehydes (formaldehyde, acetaldehyde, benzaldehyde, hydroxybenzaldehyde, crotonaldehyde, glyoxal, etc.) obtained by condensation reaction in the presence of a catalyst, and phenolic resins.

[0029] As compounds having one active hydrogen atom per molecule, one or more can be selected from the group consisting of monophenol compounds (phenol, cresol, nonylphenol, nitrophenol, etc.), monoalcohol compounds (oxyl alcohol, 2-ethylhexanol, stearyl alcohol, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, propylene glycol monohexyl ether, etc.), and monocarboxylic acid compounds (saturated and unsaturated fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-ethylhexanoic acid (octyl acid), caproic acid, caprylic acid, stearic acid, oleic acid, linoleic acid, etc.). Furthermore, one or more substances selected from the group consisting of hydroxycarboxylic acids (glycolic acid, dimethylolpropionic acid, hydroxypropivalic acid, lactic acid, citric acid, etc.), mercaptoalkanols (mercaptoethanol, etc.), alkanolamines (ethanolamine, etc.) may be used.

[0030] (Amount of each ingredient) The amounts of compounds having one or more epoxy groups and polyfunctionalizing agents used in the production of epoxy resins according to the first aspect of the present invention can be appropriately adjusted according to the desired epoxy equivalent and other factors. For example, based on the total solid content mass of compounds having one or more epoxy groups and polyfunctionalizers, the amount of each component can be set within the following ranges. Compounds having one or more epoxy groups: 50-99.9% by mass, preferably 65-95% by mass, more preferably 65-92% by mass. Polyfunctionalizing agent: 0.1 to 50% by mass, preferably 0.2 to 30% by mass, more preferably 0.5 to 20% by mass.

[0031] If the polyfunctionalizing agent content is less than 0.1% by mass, the polyfunctionalization of the epoxy resin may be insufficient, and it may not be possible to obtain a polyfunctional and highly reactive epoxy resin. On the other hand, if the polyfunctionalizing agent content exceeds 50% by mass, the reactivity of the epoxy resin may become too high, potentially leading to gelation during synthesis or poor storage stability of the paint.

[0032] (Method for producing epoxy resin according to the first embodiment) The reaction conditions for at least one reaction between a compound having one or more epoxy groups and a polyfunctionalizing agent containing compound (A) having a primary amino group, b secondary amino groups, c alcoholic hydroxyl groups, d phenolic hydroxyl groups, e carboxyl groups, f mercapto groups, g sulfonic acid groups, h carboxylic acid anhydride groups, and i epoxy groups (where a, b, c, d, e, f, g, and h are each independently integers of 0 or more, and i is 0 or an integer of 3 or more, such that 2a+b+c+d+e+f+g+2h+i≧3. If b=1, then a≠1, c≠2, or d+e+f+g+2h+i≧1. If d≧3, then 2a+b+d+e+f+g+2h+i≧1.) are not particularly limited. For example, this can be carried out in a suitable solvent at a temperature of about 80 to 190°C, preferably about 90 to 170°C, for about 1 to 6 hours, preferably about 1 to 5 hours. In the present invention, epoxy resins can be made polyfunctionalized by using the polyfunctionalizing agent. Furthermore, epoxy resins can be chain-extended by, for example, a compound having two active hydrogen atoms in one molecule (such as a divalent phenolic compound).

[0033] The solvent used in the method for producing epoxy resins is not particularly limited, as long as it is a compound that functions as a solvent without reacting with the epoxy compound in the reaction system. For example, one or more solvents selected from the group consisting of hydrocarbons such as toluene, xylene, cyclohexane, and n-hexane; esters such as methyl acetate, ethyl acetate, and butyl acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone; amides such as dimethylformamide and dimethylacetamide; alcohols such as methanol, ethanol, n-propanol, and i-propanol; and ether alcohol compounds such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether can be used.

[0034] The weight-average molecular weight of the epoxy resin according to the first embodiment is preferably in the range of 500 to 50,000, more preferably in the range of 1,000 to 20,000, and more preferably in the range of 1,500 to 10,000, from the viewpoint of finish quality, corrosion resistance, etc. In this specification, unless otherwise specified, the weight-average molecular weight is the value obtained by converting the retention time (retention volume) measured using gel permulation chromatography (GPC) to the molecular weight of polystyrene using the retention time (retention volume) of standard polystyrene with a known molecular weight measured under the same conditions. Specifically, the measurement can be performed using "HLC8120GPC" (trade name, manufactured by Tosoh Corporation) as the gel permulation chromatograph, and four columns: "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL", and "TSKgel G-2000HXL" (trade names, all manufactured by Tosoh Corporation), under the conditions of tetrahydrofuran mobile phase, measurement temperature of 40°C, flow rate of 1 mL / min, and radioisotope detector.

[0035] <Epoxy resin relating to the second embodiment> The epoxy resin according to a second aspect of the present invention is obtained by reacting at least one epoxy group with a compound (A) having a primary amino group, b secondary amino groups, c alcoholic hydroxyl groups, d phenolic hydroxyl groups, e carboxyl groups, f mercapto groups, g sulfonic acid groups, h carboxylic acid anhydride groups, and i epoxy groups (where a, b, c, d, e, f, g, and h are each independently integers of 0 or more, and i is 0 or an integer of 3 or more, and 2a+b+c+d+e+f+g+2h+i≧3. If d≧3, then 2a+b+d+e+f+g+2h+i≧1), and the epoxy resin is obtained by reacting at least one compound having one or more epoxy groups with a polyfunctionalizing agent containing a compound (A) having a primary amino group, b secondary amino group, c alcoholic hydroxyl group, d phenolic hydroxyl group, e carboxyl group, f mercapto group, g sulfonic acid group, h carboxylic acid anhydride group, and i epoxy group (where a, b, c, d, e, f, g, and h are each independently integers of 0 or more, and i is 0 or an integer of 3 or more, and 2a+b+c+d+e+f+g+2h+i≧3.

[0036] A "compound having one or more epoxy groups" used to obtain the epoxy resin according to the second embodiment is a "compound having one or more epoxy groups" used to obtain the epoxy resin according to the first embodiment. Furthermore, the "multifunctionalizing agent" may be one or more selected from the "multifunctionalizing agents" used to obtain the epoxy resin according to the first embodiment. Furthermore, the proportions of each component can be the same as those of the epoxy resin according to the first embodiment.

[0037] In the epoxy resin according to the second aspect of the present invention, properties such as curability, particularly curability when using a low-activity catalyst and curability at low temperatures, storage stability, finish quality of the coating film when an electrodeposited coating is prepared using the epoxy resin, and corrosion resistance are closely related to the degree of polyfunctionalization of the epoxy resin. In particular, by adopting the average degree of polyfunctionalization per molecule of the epoxy resin (X1) as the degree of polyfunctionalization of the epoxy resin and setting its range to a specific range, the above properties can be made preferable. In this specification, "average degree of polyfunctionalization per molecule of the epoxy resin (X1)" may be referred to as "average degree of polyfunctionalization of the epoxy resin (X1)" or "average degree of polyfunctionalization (X1)".

[0038] Methods for polyfunctionalizing epoxy resins include (1) reacting an epoxy compound (containing one or more epoxy groups, preferably two or more) with a polyfunctionalizing agent having three or more reactive functional groups that react with the epoxy groups (polyfunctionalization by a polyfunctionalizing agent), and (2) reacting a secondary hydroxyl group inside the molecule of an epoxy compound with at least one terminal epoxy group of another epoxy compound to polyfunctionalize it (polyfunctionalization by cooking). Both methods can be suitably used. From the viewpoint of stably producing epoxy resins, it is preferable to use at least method (1) above. The polyfunctional agent referred to here is a compound (A) having a primary amino group, b secondary amino groups, c alcoholic hydroxyl groups, d phenolic hydroxyl groups, e carboxyl groups, f mercapto groups, g sulfonic acid groups, h carboxylic acid anhydride groups, and i epoxy groups (where a, b, c, d, e, f, g, and h are each independent integers of 0 or more, and i is 0 or an integer of 3 or more, and 2a+b+c+d+e+f+g+2h+i≧3. If b=1, then a≠1, c≠2, or d+e+f+g+2h+i≧1. If d≧3, then 2a+b+d+e+f+g+2h+i≧1).

[0039] The average degree of polyfunctionalization (X1) per molecule of epoxy resin is given by the following formula (1): (1): Average degree of polyfunctionalization (X1) = Number of terminals in one epoxy resin molecule - 2 This can be determined by [method]. For example, if one molecule is divided into three ends, X will be 1, and if it is a linear epoxy resin that is not polyfunctionalized at all, X will be 0. The larger the average degree of polyfunctionalization (X1) value, the more polyfunctionalized each molecule is. Furthermore, the polyfunctionalization of epoxy resin ends by reacting them with polyfunctional modifiers (for example, amine compounds such as ketimine of diethylenetriamine and diethanolamine, and carboxylic acid compounds such as dimethylolpropionic acid) is not defined as "polyfunctionalization" in this invention because it results in reduced reactivity due to steric hindrance. Similarly, secondary hydroxyl groups within epoxy resins are not defined as "polyfunctionalization" in this invention from the standpoint of reactivity. In this invention, "multifunctionalization" refers to a system in which the main skeleton of the epoxy resin is branched.

[0040] When epoxy resins are polyfunctionalized by the method described in (1) above (polyfunctionalization with a polyfunctionalizing agent), the average degree of polyfunctionalization (N) per molecule of epoxy resin due to the polyfunctionalizing agent is given by the following formula: Average degree of polyfunctionalization (N) due to polyfunctionalizing agents = Σ [(valence of each polyfunctionalizing agent - 2) × basic amount of each polyfunctionalizing agent] This can be determined by [method]. Here, the "basic amount" of each polyfunctionalizing agent can be determined by the following method. (Method for calculating the basic formula) Basic amount of each raw material (mol) = Amount of each raw material (mol) × Basic mixing ratio *Amount of each ingredient (mol) = Mass of each ingredient (g) / Molecular weight of each ingredient *Basic formulation ratio = 2 / (Number of epoxy groups (mol) - Number of functional groups that react with epoxy groups excluding end-capturing agents (mol) - Number of polyfunctional groups due to polyfunctionalizing agents) *Terminal encapsulants: Monofunctional amines, acids, etc. *Functional groups that react with epoxy groups: Difunctional or more phenolic hydroxyl groups and isocyanate groups, amino groups of amines with two or more active hydrogens, etc. *Number of polyfunctional functions due to polyfunctionalizing agent = (Valence of polyfunctionalizing agent - 2) × Amount of polyfunctionalizing agent (mol)

[0041] The method described in (2) above (polyfunctionalization by cooking) is a method of reacting the epoxy groups of an epoxy resin with the secondary hydroxyl groups of another epoxy resin. In this case, the average degree of polyfunctionalization (M) per molecule of epoxy resin due to cooking is given by the following formula: Average degree of polyfunctionalization due to cooking (M) = (2-m) / (1-m)-2 (m represents the excess epoxy in the basic formulation.) This can be determined by [method]. Here, the excess epoxy (EP excess) m in the basic formulation is calculated as follows: Excess EP amount m in the basic formulation = Number of EP groups in the basic formulation (mol) - Number of functional groups that react with EP groups in the basic formulation (mol) The excess amount of EP in the epoxy resin according to the first or second embodiment of the present invention is typically 0 to 5 mmol / g, preferably 0 to 2 mmol / g, and more preferably 0 to 1.5 mmol / g, based on the resin solids content.

[0042] The average degree of polyfunctionalization per molecule of epoxy resin (X1) is calculated using the following formula, based on the average degree of polyfunctionalization due to the polyfunctionalizing agent (N) and the average degree of polyfunctionalization due to the cooking process (M): Average degree of polyfunctionalization (X1)=(N+2)×(M+1)-M-2 It can be calculated using [this method]. The epoxy resin according to the second aspect of the present invention can have an average polyfunctionalization degree (X1) per molecule of the epoxy resin that is usually 0.1 or higher, preferably 0.3 or higher, more preferably in the range of 0.6 to 10.0, even more preferably in the range of 0.7 to 6.0, and particularly preferably in the range of 1.3 to 3.7.

[0043] (Average degree of polyfunctionalization and average polyfunctionalization concentration of epoxy resins) The epoxy resin of the second embodiment is an epoxy resin obtained by reacting at least one compound having one or more epoxy groups with a compound having a functional group that reacts with epoxy groups, and if it includes epoxy resins with multiple degrees of polyfunctionalization, the calculation of the average degree of polyfunctionalization (X1) below shall be the average of each epoxy resin. The epoxy resin of the second embodiment can be an epoxy resin in which the average degree of polyfunctionalization (X1) per molecule of the epoxy resin represented by the following formula (1) is 0.1 or more, and preferably the average polyfunctionalization concentration (Y1) represented by the following formula (2) is 0.1 or more. Formula (1): Average degree of polyfunctionalization (X1) = Number of terminals per molecule of epoxy resin - 2 (In formula (1), "number of terminals per molecule of epoxy resin" refers to the number of terminals in one molecule of epoxy resin that have epoxy groups and the number of terminals that have functional groups that react with epoxy groups.) Formula (2): Average polyfunctionalization concentration (Y1) = Average degree of polyfunctionalization of epoxy resin (X1) ÷ Weight-average molecular weight of epoxy resin Mw × 1000

[0044] In the epoxy resin according to the second aspect of the present invention, the properties such as curability, particularly curability when using a low-activity catalyst and curability at low temperatures, storage stability, finish quality of the coating film when an electrodeposited coating is prepared using the epoxy resin, and corrosion resistance are closely related to the average polyfunctionalization concentration of the epoxy resin, in addition to the degree of polyfunctionalization of the epoxy resin. In particular, by adopting the average degree of polyfunctionalization per molecule of the epoxy resin (X1) and, if necessary, the average polyfunctionalization concentration (Y1) as the degree of polyfunctionalization of the epoxy resin, and setting the ranges of each to specific ranges, the aforementioned properties can be made desirable.

[0045] The epoxy resin according to the second aspect of the present invention may have an average polyfunctionalization degree (X1) per molecule of the epoxy resin of 0.30 or more, preferably in the range of 0.30 to 15.00, more preferably in the range of 0.60 to 13.00, even more preferably in the range of 0.70 to 10.00, and particularly preferably in the range of 0.90 to 8.00.

[0046] In the epoxy resin according to a second aspect of the present invention, the average polyfunctionalization concentration (Y1) of the epoxy resin, which can be used as needed, is calculated from the average degree of polyfunctionalization per molecule of the epoxy resin (X1) and the weight-average molecular weight Mw of the epoxy resin using the following formula (2). Formula (2): Average polyfunctionalization concentration (Y1) = Average degree of polyfunctionalization of epoxy resin (X1) ÷ Weight-average molecular weight of epoxy resin Mw × 1000 Here, the weight-average molecular weight Mw of the epoxy resin is calculated as follows: The weight-average molecular weight (Mw) of epoxy resins is calculated as follows: Mw = Σ(amount of each raw material in the basic formulation (moles) × molecular weight of each raw material). The average number of functional groups per molecule of polyfunctionalizing agent components with three or more functions is calculated using the following formula. Average number of functional groups = Σ(percentage of each polyfunctionalizing agent component ÷ molecular weight of each polyfunctionalizing agent component × number of functional groups of each polyfunctionalizing agent component) / Σ(percentage of each polyfunctionalizing agent component ÷ molecular weight of each polyfunctionalizing agent component)

[0047] The epoxy resin of the second aspect of the present invention may have an average polyfunctionalization concentration (Y1) per gram of solid content of the epoxy resin of 0.10 (mmol / g) or more, preferably in the range of 0.10 to 5.00 (mmol / g), more preferably in the range of 0.40 to 3.00 (mmol / g), and even more preferably in the range of 0.40 to 2.00 (mmol / g). The average polyfunctionalization concentration (Y1) defines the degree of polyfunctionalization per unit mass; a higher Y1 value indicates more functional groups and higher resin reactivity. If the degree of polyfunctionalization and / or concentration of polyfunctionalization is high, gelation or thickening will occur during resin synthesis, resulting in a deterioration of the finish of the coating film. Conversely, if it is low, corrosion resistance and oil repellency will decrease.

[0048] <End functional groups of epoxy resins> The epoxy resin of the first or second embodiment described above may have terminal functional groups other than epoxy groups. For example, after synthesizing the epoxy resin described in the first or second embodiment, a modified epoxy resin having other reactive functional groups at its terminals may be obtained by reacting the epoxy group of the polyfunctional epoxy resin with a reactive functional group-containing compound. However, even if a single epoxy group at the end of the epoxy resin reacts with a reactive functional group-containing compound (e.g., diethanolamine) to produce multiple terminal functional groups (in the case of diethanolamine, the epoxy group and the secondary amino group of diethanolamine react to produce two hydroxyl groups derived from diethanolamine and one hydroxyl group derived from the epoxy group), the "number of functional groups as polyfunctional" in this invention remains one, as described above. The functional groups that react with epoxy groups are not particularly limited as long as they can react with epoxy groups, and examples include carboxyl groups, primary or secondary amino groups, and hydroxyl groups. Even in cases like the one described above (modified epoxy resin), the calculation of the average degree of polyfunctionalization (X1) and the average polyfunctionalization concentration (Y1) can be performed in the same manner.

[0049] [Amine-modified epoxy resin] The present invention further relates to amine-modified epoxy resins. Amine-modified epoxy resins can be obtained by reacting an epoxy resin of the first or second embodiment with an amine compound. It is preferable to use an epoxy resin of the first or second embodiment that has not been previously reacted with an amine compound. Furthermore, if necessary, an epoxy compound that has been pre-reacted with an amine compound may be used when obtaining either the epoxy resin of the first or second embodiment. In this case, the amount of amine compound used can be appropriately determined so that the amine value of the amine-modified epoxy resin reaches a desired value, and it is preferable that the amount of amine compound used be 99 mol% or less of the total amine compound.

[0050] <Amine compounds> The amine compound is not particularly limited as long as it is an amine compound that has reactivity with epoxy resins.For example, mono-alkylamines or di-alkylamines such as monomethylamine, dimethylamine, monoethylamine, diethylamine, dipropylamine, dibutylamine, dihexylamine, dioctylamine, monoisopropylamine, diisopropylamine, monobutylamine, monooctylamine, methylbutylamine, and dibutylamine; monoethanolamine, N-methylethanolamine, N-ethylethanolamine, diethanolamine, mono(2-hydroxypropyl)amine, di(2-hydroxypropyl)amine, N-butylethanolamine, dipropanolamine, monomethylaminoethanol, N-(2-hydroxypropyl)ethylenediamine, 3-methylamino-1,2-propanediol, 3-tert-butylamino-1,2-propanediol, N-methylglucamine, and N-octylglucamine; polymethylenediamine, polyetherdiamine, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, trimethylhexamethylenediamine, and triethylenetetramine. Alkylene polyamines such as dimethylaminopropylamine, diethylenetriamine, diethylaminopropylamine, and bis(4-aminobutyl)amine; aromatic or alicyclic polyamines such as mensendiamine, isophoronediamine, bis(4-amino-3-methylcyclohexyl)methane, metaxylylenediamine, metaphenylenediamine, naphthylenediamine, and dimethylaminomethylbenzene; heterocyclic polyamines such as piperazine, 1-methylpiperazine, 3-pyrrolidinol, 3-piperidinol, and 4-pyrrolidinol. One or more can be used selected from the group consisting of: ; epoxy-added polyamines obtained by adding 1 to 30 moles of an epoxy group-containing compound to 1 mole of the above polyamine; polyamide polyamines containing one or more primary or secondary amines in the molecule of the polyamide resin produced by condensation of the above polyamine with an aromatic acid anhydride, a cyclic aliphatic acid anhydride, aliphatic acid anhydride, halogenated acid anhydride and / or dimer acid; ketiminated amines obtained by reacting one or more primary or secondary amines in the above polyamine with a ketone compound; etc.

[0051] The ketone compound used to produce the above-mentioned ketimated amine is not particularly limited as long as it reacts with the primary or secondary amine of the polyamine to form a ketimated product and is further hydrolyzed in the aqueous paint composition. For example, one or more selected from the group consisting of methyl isopropyl ketone (MIPK), diisobutyl ketone (DIBK), methyl isobutyl ketone (MIBK), diethyl ketone (DEK), ethyl butyl ketone (EBK), ethyl propyl ketone (EPK), dipropyl ketone (DPK), methyl ethyl ketone (MEK), etc., can be used. In the present invention, when a ketimated amine is used, its ketimation rate is not particularly limited. For example, it is preferably 80% or more.

[0052] Amine-modified epoxy resins can be modified with a modifying agent as needed. Such modifying agents are not particularly limited as long as they are resins or compounds that react with epoxy resins, and one or more selected from the group consisting of polyols, polyether polyols, polyester polyols, polyamidoamines, polycarboxylic acids, fatty acids, polyisocyanate compounds, compounds obtained by reacting polyisocyanate compounds, lactone compounds such as ε-caprolactone, acrylic monomers, compounds obtained by polymerization of acrylic monomers, xyleneformaldehyde compounds, epoxy compounds, etc., can be used.

[0053] The proportion of the above-mentioned modifier used is not strictly limited and can be appropriately changed depending on the application of the paint composition, but from the viewpoint of improving finish and corrosion resistance, it is generally appropriate to use a range of 0 to 50% by mass, preferably 0.1 to 30% by mass, and more preferably 1 to 20% by mass, based on the solid content mass of the amine-modified epoxy resin.

[0054] <Method for producing amine-modified epoxy resin> The reaction between the epoxy resin according to the first or second embodiment and the amine compound can be carried out, for example, in a suitable solvent at a temperature of about 80 to about 190°C, preferably about 90 to about 170°C, for about 1 to 6 hours, preferably about 1 to 5 hours. The solvent used in the reaction is not particularly limited. For example, the same solvent used in the production of the epoxy resin according to the first embodiment can be used.

[0055] The weight-average molecular weight of the amine-modified epoxy resin is usually in the range of 1,000 to 50,000, more preferably in the range of 1,300 to 20,000, and more preferably in the range of 1,600 to 10,000, from the viewpoint of finish quality, corrosion resistance, etc. The amine value of the amine-modified epoxy resin is typically 5 mg KOH / g or higher, based on the resin solids content, preferably in the range of 10 to 200 mg KOH / g, and more preferably in the range of 20 to 150 mg KOH / g, from the viewpoint of improving water dispersibility and corrosion resistance.

[0056] The amine values ​​used herein are measured in accordance with JIS K 7237-1995. All values ​​are amine values ​​per resin solids (mgKOH / g). Furthermore, the weight-average molecular weight of the amine-modified epoxy resin is the same as that described for the epoxy resin according to the first embodiment.

[0057] [Aqueous resin dispersion] The aqueous resin dispersion of the present invention is obtained by dispersing one or more epoxy resins selected from either the epoxy resins of the first or second embodiment and their modified products in an aqueous medium. For example, an epoxy resin of the first or second embodiment can be obtained by dispersing it in an aqueous medium. Alternatively, an amine-modified epoxy resin can be obtained by (i) reacting either the epoxy resin of the first or second embodiment with an amine compound, and / or (ii) using an epoxy compound that has been previously reacted with an amine compound as the epoxy compound used to obtain either the epoxy resin of the first or second embodiment, and then neutralizing the amine-modified epoxy resin with an acid compound and dispersing it in an aqueous medium. In the present invention, "aqueous resin dispersion" refers to a state in which the resin component exists in a particulate state without being dissolved in the aqueous medium.

[0058] The content of one or more epoxy resins selected from either the first or second embodiment of epoxy resins and their modified products in the aqueous resin dispersion is preferably 50% by mass or more, based on the solid content. The aqueous resin dispersion is preferably prepared by mixing an epoxy resin and / or a modified version thereof according to the first or second embodiment with a curing agent (such as a blocked polyisocyanate compound) described later and dispersing it in an aqueous medium. In this case, an amine-modified epoxy resin is preferred as the epoxy resin and / or a modified version thereof, and a blocked polyisocyanate compound is preferred as the curing agent. Furthermore, the mixing ratio (mass ratio) of epoxy resin and / or modified thereof with the curing agent is preferably 1 / 99 to 99 / 1 in terms of solid content, more preferably 30 / 70 to 90 / 10, and even more preferably 40 / 60 to 85 / 15.

[0059] The aqueous medium used to disperse one or more epoxy resins selected from either the epoxy resins of the first or second embodiment and their modified products is a solvent mainly composed of water and / or a hydrophilic solvent (containing 50% by mass or more in the solvent). Other solvents may include, for example, ester solvents, ketone solvents, amide solvents, alcohol solvents, and ether alcohol solvents, or mixtures thereof. Here, as the hydrophilic solvent, specifically, one or more selected from the group consisting of ethylene glycol, ethylene glycol monoalkyl ethers (e.g., methyl ether, ethyl ether, butyl ether, etc.), diethylene glycol, diethylene glycol monoalkyl ethers (e.g., methyl ether, ethyl ether, butyl ether, etc.), glyme solvents (e.g., ethylene glycol dimethyl ether, etc.), diglyme solvents (e.g., diethylene glycol dimethyl ether, etc.), alcohol solvents (e.g., methanol, ethanol, propanol, n-butanol, etc.), propylene glycol, propylene glycol monoalkyl ethers (e.g., methyl ether, ethyl ether, butyl ether, etc.), dipropylene glycol, dipropylene glycol monoalkyl ethers (e.g., methyl ether, ethyl ether, butyl ether, etc.), etc. can be used.

[0060] Any known acid compound can be used without particular limitation when dispersing in an aqueous medium. Specifically, examples include inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid, and sulfamic acid; and organic acids including carboxylic acid compounds such as formic acid, acetic acid, propionic acid, and lactic acid. These acid compounds can be used individually or in combination of two or more, with organic acids being preferred, and carboxylic acid compounds being particularly preferred. As for the neutralization equivalent, 0.2 to 1.5 equivalents of the acid compound per 1 equivalent of the amino group is preferred, and 0.5 to 1.0 equivalent is more preferred.

[0061] The aqueous resin dispersion of the present invention may contain, as necessary, one or more epoxy resins selected from either the epoxy resins of the first or second embodiment and their modified products, and acid compounds, as well as additives such as neutralizing agents, emulsifiers, catalysts, and other resin components. The dispersion of the amine-modified epoxy resin in an aqueous medium may be carried out by adding the aqueous medium to the neutralized amine-modified epoxy resin while stirring, adding the neutralized amine-modified epoxy resin to the aqueous medium while stirring, or mixing the aqueous medium and the neutralized amine-modified epoxy resin before stirring. The dispersion temperature is preferably less than 100°C, more preferably 40 to 99°C, and even more preferably 50 to 95°C. The resin solids content concentration of the obtained dispersion is preferably 5 to 80% by mass, and more preferably 10 to 50% by mass.

[0062] [Electrodeposition paint] The electrodeposition coating of the present invention may be either a cationic electrodeposition coating or an anionic electrodeposition coating, as long as it contains the epoxy resin of the present invention or a modified thereof. Cationic electrodeposition coatings preferably contain the epoxy resin or a modified version thereof of the present invention as a film-forming resin component. Alternatively, they may contain an aqueous resin dispersion in which the epoxy resin or a modified version thereof of the present invention is dispersed in an aqueous medium. Examples of modified epoxy resins include amine-modified epoxy resins obtained by reacting an epoxy resin with an amine compound. The anionic electrodeposition coating preferably contains the epoxy resin of the present invention as a film-forming resin component. Alternatively, it may contain an aqueous resin dispersion in which the epoxy resin of the present invention is dispersed in an aqueous medium. The electrodeposition coating of the present invention is particularly preferably a cationic electrodeposition coating.

[0063] <Cationic electrodeposition coating> The cationic electrodeposition coating of the present invention contains an amine-modified epoxy resin obtained by reacting the epoxy resin of the present invention with an amine compound as a film-forming resin component. Furthermore, if an amine compound is used as the polyfunctionalizing agent for the epoxy resin of the present invention, it is not necessarily required to react the epoxy resin with the amine compound, since the amine compound has already been introduced by the polyfunctionalizing agent. Furthermore, the present invention may also include an aqueous resin dispersion in which the epoxy resin or an amine-modified epoxy resin obtained by reacting the epoxy resin with an amine compound is dispersed in an aqueous medium.

[0064] The cationic electrodeposition coating of the present invention contains a film-forming resin component comprising the epoxy resin of the present invention or an amine-modified epoxy resin obtained by reacting the epoxy resin with an amine compound, and a curing agent capable of curing the epoxy resin as essential components. Optionally, it may also contain a curing catalyst, pigment, solvent such as water, and additives (surfactants, surface modifiers, curing co-catalysts, neutralizing agents, etc.). As the coating film-forming resin component, an amine-modified epoxy resin obtained by reacting an epoxy resin according to the first or second embodiment with an amine compound is preferred. Examples of cationic electrodeposition coatings of the present invention include cationic electrodeposition coatings containing the amine-modified epoxy resin described in the [amine-modified epoxy resin] section above and a curing agent. Furthermore, examples of cationic electrodeposition coatings of the present invention include a single-layer cationic electrodeposition coating containing the amine-modified epoxy resin described above and a curing agent.

[0065] As a coating resin component other than the amine-modified epoxy resin mentioned above, one or more can be selected from the group consisting of acrylic resin, epoxy resin other than the epoxy resin of the first or second embodiment of the present invention or a modified product thereof (including amino group modified), urethane resin, and melamine resin. When a cationic electrodeposition coating contains acrylic resin, the acrylic resin content in the cationic electrodeposition coating is preferably less than 30% by mass, more preferably less than 15% by mass, and even more preferably less than 3% by mass, when the total amount of all epoxy resins (including modified products) and acrylic resin is taken as 100% by mass, from the viewpoint of corrosion resistance and other factors. Furthermore, from the viewpoint of resin compatibility and finish quality, it is preferable that the difference in solubility parameters (SP values) between at least one epoxy resin and an acrylic resin is less than 1.0 in absolute value, and more preferably less than 0.5. By using resins with similar SP values, it is possible to form a coating film without phase separation.

[0066] Here, the solubility parameter, also commonly called the SP value (solubility parameter), is a measure that indicates the degree of hydrophilicity or hydrophobicity of a resin. It is also an important measure for determining the compatibility between resins, and resins with similar solubility parameter values ​​(small absolute difference in solubility parameters) generally have good compatibility. The measured solubility parameters are values ​​obtained by turbidity titration and are calculated according to the following formula by KWSUH and JMCORBETT (see Journal of Applied Polymer Science, VOL.12, 2359-2370 (1968)). Measured solubility parameter (SP value) = (√Vml·δH + √Vmh·δD) / (√Vml + √Vmh) Vml, Vmh, δH, and δD are values ​​calculated by applying the following formula to the following equation: Vml, Vmh, δH, and δD are obtained by dissolving 0.5g of resin (solid content) in 10mL of tetrahydrofuran at a measurement temperature of 20°C, adding n-hexane, and defining the point at which a No. 4 type on a newspaper placed below the bottom can be seen and read from the top of the beaker as the turbidity point. The titration volume H (mL) at the turbidity point and the titration volume D (mL) at the turbidity point when deionized water is added to 0.5g of resin (solid content) in 10mL of tetrahydrofuran at a measurement temperature of 20°C are then applied to the following equation. Vml=81.1×130.3 / {(1-VH)×130.3+VH×81.1} Vmh=81.1×18 / {(1-VD)×18+VD×81.1} VH = H / (10 + H) VD = D / (10 + D) δH=9.52×10 / (10+H)+7.24×H / (10+H) δD=9.52×10 / (10+D)+23.43×D / (10+D) The molecular volume (mL / mol) of each solvent is tetrahydrofuran: 81.1, n-hexane: 130.3, and deionized water: 18. The SP values ​​of each solvent are tetrahydrofuran: 9.52, n-hexane: 7.24, and deionized water: 23.43.

[0067] The above-mentioned acrylic resin can be used without particular limitations, but a cationic acrylic resin is preferred. Cationic acrylic resins can be produced, for example, by radical copolymerization of cationic base-containing acrylic monomers and other monomers. Non-cationic acrylic resins can be produced using only the other monomers described later. The above-mentioned cationic base-containing acrylic monomers specifically include, for example, amino group-containing acrylic monomers and their quaternary chlorides such as N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, and N,N-di-t-butylaminoethyl (meth)acrylate; quaternary ammonium base-containing acrylic monomers such as (meth)acryloyloxyethyltrimethylammonium chloride, (meth)acryloyloxyethyldimethylbenzylammonium chloride, (meth)acryloyloxyethyltrimethylammonium methyl sulfate, and (meth)acryloyloxyethyldimethylethylammonium ethyl sulfate; and tertiary sulfonium base-containing acrylic monomers such as 4-(dimethylsulfonio)phenyl methacrylate. These can be used individually or in combination of two or more types.

[0068] The above-mentioned other monomers can preferably be any known monomer other than the above-mentioned cationic base-containing acrylic monomer. Examples include (meth)acrylic acid, styrene, vinyltoluene, aromatic vinyl monomers such as α-methylstyrene, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, addition products of 2-hydroxyethyl (meth)acrylate and caprolactone (e.g., Praxel FA-2 and FM-3, trade names of Daicel Corporation), polyalkylene glycol (meth)acrylate, (meth)acrylamide, etc. These can be used individually or in combination of two or more.

[0069] The above-mentioned acrylic resin can be obtained by radical copolymerization of these monomers using known methods. The hydroxyl value of the above-mentioned acrylic resin is typically in the range of 0 to 300 mg KOH / g, preferably in the range of 30 to 200 mg KOH / g. The weight-average molecular weight of the acrylic resin is typically in the range of 1,000 to 200,000, preferably in the range of 3,000 to 50,000. The amine value of acrylic resin is typically in the range of 0 to 300 mg KOH / g, preferably in the range of 10 to 150 mg KOH / g.

[0070] Furthermore, acrylic resins can be synthesized by radical copolymerization of reactive functional group-containing acrylic monomers with other monomers, and then a cationic base can be introduced into the acrylic resin by reacting the reactive functional group with a cationic base-containing compound. For example, an amino group can be imparted to an acrylic resin by adding an amine compound containing active hydrogen to the glycidyl group of a copolymer of polymerizable unsaturated monomers containing glycidyl (meth)acrylate. Examples of such amine compounds include primary mono- and polyamines, secondary mono- and polyamines or mixed primary and secondary polyamines, secondary mono- and polyamines having ketiminated primary amino groups, and hydroxy compounds having ketiminated primary amino groups.

[0071] The cationic electrodeposition coating of the present invention is a cationic electrodeposition coating containing the above-mentioned amine-modified epoxy resin (I), an amine-modified epoxy resin (II) obtained by reacting an epoxy resin having 2 or fewer functional groups (which can be optionally contained) with an amine compound, and a curing agent (particularly a blocked polyisocyanate compound). The curing agent content in the above-mentioned cationic electrodeposition coating is preferably 10 to 50% by mass, and more preferably 20 to 40% by mass, based on 100% by mass of the resin solids. The average polyfunctionalization degree (X2) of the amine-modified epoxy resin (I) represented by the following formula (3) can be 0.30 or higher, preferably in the range of 0.30 to 15.00, more preferably in the range of 0.60 to 13.00, even more preferably in the range of 0.70 to 10.00, and particularly preferably in the range of 0.90 to 8.00. A cationic electrodeposition coating can be used in which the average polyfunctionalization concentration (Y2) of the amine-modified epoxy resin contained in the cationic electrodeposition coating represented by the following formula (4) is 0.1 (mmol / g) or higher (preferably in the range of 0.1 to 5 (mmol / g), more preferably in the range of 0.4 to 3.0 (mmol / g), and even more preferably in the range of 0.4 to 2.0 (mmol / g)). If necessary, it may contain a curing catalyst, pigment, solvent such as water, and additives (surfactants, surface modifiers, curing co-catalysts, neutralizing agents, etc.). The average polyfunctionalization concentration (Y2) mentioned above is the average polyfunctionalization concentration (Y2) of all amine-modified epoxy resins contained in the cationic electrodeposition coating.

[0072] Formula (3): Average degree of polyfunctionalization (X²) = Number of terminals in one molecule of amine-modified epoxy resin (I) - 2 Formula (4): The average polyfunctionalization concentration (Y2) of the amine-modified epoxy resin contained in cationic electrodeposition paint = average polyfunctionalization degree (X2) of the amine-modified epoxy resin (I) ÷ weight-average molecular weight (Mw) of the amine-modified epoxy resin (I) × 1000 × (amount of amine-modified epoxy resin (I) ÷ total amount of amine-modified epoxy resin)

[0073] (Hardening agent) The curing agent included in the cationic electrodeposition coating of the present invention is preferably at least one selected from blocked polyisocyanate compounds and amino resins. -Blocked polyisocyanate compounds- Blocked polyisocyanate compounds are the addition reaction products of polyisocyanate compounds and blocking agents. Alternatively, if necessary, active hydrogen-containing compounds other than blocking agents can be used, reacted together with the blocking agent and the polyisocyanate compound. Known polyisocyanate compounds can be used. For example, aromatic, aliphatic, or alicyclic polyisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,2'-diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, crude MDI [polymethylene polyphenyl isocyanate], polymeric MDI, crude TDI, bis(isocyanate methyl)cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate, etc., or one or more selected from the group consisting of dimers, trimers, biuretes, allophanates, uretodiones, uretoimines, isocyanurates, oxadiazinetriones, etc. of these polyisocyanate compounds can be used. In particular, aromatic polyisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, MDI, etc. (preferably crude MDI, etc.) are more preferred for their corrosion-resistant properties.

[0074] The blocking agent blocks the isocyanate groups of the polyisocyanate compound by adding to them. The blocked polyisocyanate compound produced by this addition is stable at room temperature (20±15°C), but it is desirable that the blocking agent dissociates and regenerates free isocyanate groups when heated to the baking temperature of the coating film (for example, about 80 to about 200°C). Examples of blocking agents include oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenolic compounds such as phenol, para-t-butylphenol, and cresol; alcoholic compounds such as n-butanol, 2-ethylhexanol, phenylcarbinol, methylphenylcarbinol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, ethylene glycol, propylene glycol, propylene glycol monomethyl ether, and methoxymethanol; lactam compounds such as ε-caprolactam and γ-butyrolactam; active methylene compounds such as dimethyl malonate, diethyl malonate, diisopropyl malonate, ethyl acetoacetate, isopropyl acetoacetate, methyl acetoacetate, isopropyl acetoacetate, and acetylacetone; pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-bromo-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-benzyl-3,5-dimethylpyrazole, and methyl Pyrazole compounds such as -5-methylpyrazole-3-carboxylate, 3-methyl-5-phenylpyrazole, and 3,5-dimethylpyrazole-4-carboxyanilide; mercaptan compounds such as butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, and ethylthiophenol; acetanilide, acetanisidide, acetotoluid, acrylamide, methacrylamide, acetic acid amide, stearic acid amide, and benzalkonium amide. Acid amide compounds such as mid; imide compounds such as succinimide, phthalimide, and maleimide; amine compounds such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, and butylphenylamine; imidazole compounds such as imidazole and 2-ethylimidazole; urea compounds such as urea, thiourea, ethyleneurea, ethylenethiourea, and diphenylurea; carbamic acid ester compounds such as phenyl phenylcarbamate;One or more compounds selected from the group consisting of imine compounds such as ethyleneimine and propyleneimine; and sulfite compounds such as sodium bisulfite and potassium bisulfite may be used.

[0075] In particular, at least one selected from the group consisting of pyrazole compounds, active methylene compounds, oxime compounds, phenol compounds, lactam compounds, and alcohol compounds is preferred as the blocking agent.

[0076] -Amino resin- As the amino resin, known ones can be used. For example, one or more can be selected from the group consisting of various amino resins having alkylol groups obtained by reacting various amino group-containing compounds such as melamine, benzoguanamine, acetoganaamine, or urea with various aldehyde compounds (or aldehyde-supplying substances) such as formaldehyde or acetaldehyde (e.g., melamine resin, benzoguanamine resin, urea resin, etc.), and various alkoxyalkyl group-containing amino resins obtained by reacting the alkylol group-containing amino resin with various lower alcohols such as methanol, ethanol, n-butanol, or i-butanol (isobutanol).

[0077] (curing catalyst) The cationic electrodeposition coating of the present invention may contain a bismuth compound as a curing catalyst. Furthermore, in addition to the bismuth compound, one or more curing catalysts selected from the group consisting of, for example, inorganic compounds such as zinc compounds, tin compounds, titanium compounds, zirconium compounds, and yttrium compounds; organic compounds such as phosphazene compounds, amine compounds, and quaternary salt compounds; and composites thereof may be used in combination. Furthermore, organotin compounds such as dibutyltin dibenzoate, dioctyl tin oxide, and dibutyltin oxide can be used as catalysts to improve the hardening properties of the coating film. However, due to recent environmental regulations on organotin compounds, it is preferable not to use them. From an environmental perspective, it is even more preferable to use a curing catalyst selected from the group consisting of bismuth compounds, or bismuth compounds and inorganic compounds such as zinc compounds, titanium compounds, zirconium compounds, and yttrium compounds; organic compounds such as phosphazene compounds, amine compounds, and quaternary salt compounds; or composites thereof, or to substantially not use a curing catalyst at all. The cationic electrodeposition coating of the present invention preferably contains a bismuth compound as a curing catalyst from an environmental and safety standpoint.

[0078] As the bismuth compound, one or more can be selected from the group consisting of inorganic bismuth compounds such as metallic bismuth, bismuth chloride, bismuth oxychloride, bismuth bromide, bismuth oxide, bismuth hydroxide, bismuth nitrate, bismuth nitrite, bismuth silicate, bismuth aluminate, bismuth aluminate, bismuth borate, bismuth phosphate, bismuth carbonate, and bismuth oxycarbonate; and organic bismuth compounds such as bismuth formate, bismuth acetate, bismuth salicylate, bismuth citrate, bismuth benzoate, bismuth gallate, bismuth oxalate, bismuth lactate, bismuth oleate, bismuth methoxyacetate, bismuth dimethylolpropionate, bismuth dialkyldithiocarbamate, bismuth toluenesulfonate, and triphenylbismuth. The blending ratio of the bismuth compound in the cationic electrodeposition coating of the present invention is 0.1 to 10 parts by mass, preferably 0.5 to 6 parts by mass, based on 100 parts by mass of resin solids.

[0079] (Pigment) As pigments that can be used in the cationic electrodeposition coating of the present invention, for example, one or more selected from the group consisting of coloring pigments, rust-preventive pigments, extender pigments, etc. can be used. These pigments are preferably mixed into paints as a pigment dispersion paste. For example, a pigment dispersion paste prepared by blending a pigment dispersion resin, pigment, and various additives such as a neutralizing agent, and dispersing them in a dispersion mixer such as a ball mill, sand mill, or pebble mill, can be used in cationic electrodeposition paints.

[0080] As pigments, known pigments can be used without particular limitations. For example, one or more pigments selected from the group consisting of coloring pigments such as titanium dioxide, carbon black, and red iron oxide; extender pigments such as clay, mica, barita, calcium carbonate, and silica; and metal compounds that function as rust-preventive pigments such as zinc phosphate, iron phosphate, aluminum phosphate, calcium phosphate, zinc phosphite, zinc cyanide, zinc oxide, aluminum tripolyphosphate, zinc molybdate, aluminum molybdate, calcium molybdate, and aluminum phosphomolybdate, aluminum phosphomolybdate, and zinc phosphomolybdate can be used. In this invention, when silica is used, its amount used is less than 5% by mass.

[0081] The pigment dispersion resin that may be incorporated into the pigment dispersion paste is not particularly limited. For example, one or more resins selected from the group consisting of epoxy resins having hydroxyl groups and cationic groups, acrylic resins having hydroxyl groups and cationic groups, tertiary amine type epoxy resins, quaternary ammonium salt type epoxy resins, tertiary sulfonium salt type epoxy resins, tertiary amine type acrylic resins, quaternary ammonium salt type acrylic resins, tertiary sulfonium salt type acrylic resins, etc., can be used. The amount of pigment added is preferably in the range of 1 to 100 parts by mass, particularly 10 to 50 parts by mass, per 100 parts by mass of resin solids of the cationic electrodeposition coating.

[0082] Examples of cationic electrodeposition coatings of the present invention include a cationic electrodeposition coating that contains a compound having one or more epoxy groups, a compound (A) having a primary amino group, b secondary amino groups, c alcoholic hydroxyl groups, d phenolic hydroxyl groups, e carboxyl groups, f mercapto groups, g sulfonic acid groups, h carboxylic acid anhydride groups, and i epoxy groups (where a, b, c, d, e, f, g, and h are each independently integers of 0 or more, i is 0 or an integer of 3 or more, and 2a+b+c+d+e+f+g+2h+i≧3; if b=1, a≠1, +c≠2, or d+e+f+g+2h+i≧1; if d≧3, 2a+b+d+e+f+g+2h+i≧1), an amine-modified epoxy resin obtained by reacting these compounds, and a curing agent.

[0083] The compound having one or more epoxy groups that constitutes the cationic electrodeposition coating of the present invention is preferably a compound that has not been amine-modified. Furthermore, the epoxy resin that constitutes the cationic electrodeposition coating of the present invention is preferably obtained by reacting a compound having one or more epoxy groups with a polyfunctionalizing agent.

[0084] The cationic electrodeposition coating of the present invention is preferably a single-layer cationic electrodeposition coating. A single-layer cationic electrodeposition coating is a coating that, when applied by cationic electrodeposition and heat curing, forms a single coating film in which the components in the thickness direction of the coating film are substantially uniform. For example, the single-layer cationic electrodeposition coating of the present invention is a cationic electrodeposition coating that forms a coating film that does not show two-layer separation (or multi-layer separation) when the cross-section of the electrodeposited coating film is observed under a microscope. Even if there is some bias in the pigment components or resin components, if no interface between layers is visible in the cross-sectional observation, it is considered a single-layer coating film. Furthermore, for example, the single-layer cationic electrodeposition coating of the present invention is a cationic electrodeposition coating that does not form a multilayer film with a concentration gradient such that a corrosion-resistant resin (epoxy resin) is mainly distributed in the lower layer (metal substrate surface side; the same applies hereinafter) and a resin other than epoxy resin is mainly distributed in the upper layer by a single electrodeposition coating.

[0085] (Method of manufacturing cationic electrodeposition coating) The cationic electrodeposition coating of the present invention is not particularly limited as long as it is a manufacturing method capable of producing a cationic electrodeposition coating containing the epoxy resin of the present invention or a modified thereof, or a cationic electrodeposition coating containing the amine-modified epoxy resin and bismuth compound of the present invention. For example, a method for producing a cationic electrodeposition coating includes the steps of: reacting an epoxy resin obtained by reacting at least one epoxy group with a phenolic compound of trivalent or higher valentvit In the method for producing cationic electrodeposition coatings of the present invention, it is preferable that the compound having one or more epoxy groups is an amine-modified compound. Furthermore, it is preferable that the produced cationic electrodeposition coating is a single-layer cationic electrodeposition coating.

[0086] (Cationic electrodeposition coating method and coated articles) The cationic electrodeposition coating method using the cationic electrodeposition paint of the present invention includes the steps of immersing an object to be coated in an electrodeposition bath made of the cationic electrodeposition paint, and passing an electric current through the object to be coated with the object as the cathode. A coated article to which the cationic electrodeposition coating of the present invention has been applied can be obtained by immersing the object to be coated in an electrodeposition coating bath containing the cationic electrodeposition coating and performing electrodeposition coating. Examples of objects to be coated with cationic electrodeposition paint include automobile bodies, automobile parts, motorcycle parts, household appliances, and other equipment. There are no particular restrictions as long as the object contains metal. Examples of metal sheets to be coated include cold-rolled steel sheets, alloyed hot-dip galvanized steel sheets, electro-galvanized steel sheets, electro-galvanized zinc-iron double-layer plated steel sheets, organic composite plated steel sheets, Al material, Mg material, etc., as well as metal sheets that have been cleaned on the surface by alkaline degreasing or the like as needed, and then subjected to surface treatments such as phosphate chlorination, chromate treatment, and composite oxide treatment.

[0087] Cationic electrodeposition coating is carried out by using a cation electrodeposition coating, prepared by diluting it with deionized water or the like to a solid content concentration of approximately 5 to 40% by mass, preferably 10 to 25% by mass, and further adjusting the pH to within the range of 4.0 to 9.0, preferably 5.5 to 7.0, as a bath, usually adjusting the bath temperature to 15 to 35°C, and applying an electric current with the object to be coated as the cathode under conditions of a load voltage of 100 to 400V, preferably 150 to 350V. After cation electrodeposition coating, the object to be coated is usually thoroughly washed with ultrafiltration solution (UF filtrate), reverse osmosis permeate (RO water), industrial water, pure water, etc., to remove any excess cation electrodeposition coating.

[0088] The film thickness of the cationic electrodeposition coating is not particularly limited, but generally it can be in the range of 5 to 40 μm, preferably 10 to 30 μm, based on the dry coating. Furthermore, while baking the coating is generally done using drying equipment such as an electric hot air dryer or a gas hot air dryer, at a temperature higher than 160°C and lower than 200°C on the surface of the coated article, in the present invention, from the viewpoint of reducing energy costs, it is preferably less than 160°C, more preferably 80 to 130°C, and particularly preferably 100 to 130°C. The baking time is 10 to 180 minutes, preferably 20 to 50 minutes. A cured coating can be obtained by the above baking drying.

[0089] <Anionic Electrodeposition Paint> The anionic electrodeposition coating of the present invention contains a film-forming resin component comprising the epoxy resin and carboxyl group-containing resin of the present invention, and a curing agent as essential components. Optionally, it may also contain epoxy phosphate compounds, curing catalysts, pigments, solvents such as water, and additives (surfactants, surface modifiers, curing co-catalysts, neutralizing agents, etc.). As the carboxyl group-containing resin, one or more can be selected from the group consisting of, for example, acrylic resin, polyester resin, polyether resin, polycarbonate resin, urethane resin, etc. The weight-average molecular weight of the carboxyl group-containing resin (A) is suitable to be in the range of 5,000 to 100,000, the acid value is suitable to be in the range of 5 to 180 mgKOH / g, and the hydroxyl value is suitable to be in the range of 3 to 150 mgKOH / g. The curing agent is preferably at least one selected from, for example, a blocked polyisocyanate compound and an amino resin (such as melamine resin), and for example, those listed as curing agents for cationic electrodeposition coatings of the present invention can be used.

[0090] In anionic electrodeposition coatings, the mixing ratio of carboxyl group-containing resin to curing agent is preferably 50 to 90 parts by mass of carboxyl group-containing resin, based on a total of 100 parts by mass of solids of the carboxyl group-containing resin and curing agent. The anionic electrodeposition coating of the present invention can have a solid content concentration of about 5 to 40% by mass, preferably 10 to 25% by mass, and a pH that can be adjusted to within the range of 7.0 to 10.0, preferably 7.5 to 9.5.

[0091] (Anionic electrodeposition coating method) The anionic electrodeposition coating method includes the steps of immersing an object to be coated in an electrodeposition bath made of the anionic electrodeposition paint, and passing an electric current through the object to be coated as the anode. Examples of objects to be coated with anionic electrodeposition coatings include building materials, aluminum sashes, joinery, base materials for verandas, roofing materials, shutters, doors, shoji screens, shutter boxes, sunrooms, and their components.

[0092] Anionic electrodeposition coating is performed by, for example, using anionic electrodeposition paint as a bath, adjusting the bath temperature to typically 15-35°C, and applying an electric current with the object to be coated, such as aluminum or an aluminum alloy, as the anode under a load voltage of 100-400V. After anionic electrodeposition coating, thorough rinsing with water is optional. The film thickness of the anionic electrodeposited coating can be, for example, within the range of 1 to 40 μm based on the dry film thickness. The coating can be baked and dried using drying equipment such as an electric hot air dryer or a gas hot air dryer. The conditions for the above-mentioned baking and drying are a drying temperature of 140 to 220°C, preferably less than 160°C, and a baking time of 10 to 180 minutes. [Examples]

[0093] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "mass%" and "parts" means "parts by mass".

[0094] [Amino group-containing epoxy resin] <Example 1-1> In a reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 378 parts of bisphenol A, 1054 parts of bisphenol A type epoxy resin (epoxy compound), 21 parts of polyfunctionalizer 4 (Note 4), and 1.0 part of TBAB (tetrabutylammonium bromide; catalyst) were added, along with methyl isobutyl ketone (solvent) at a concentration equal to 10% of the total mass of the bisphenol A type epoxy resin, bisphenol A, and polyfunctionalizer. The mixture was reacted at 160°C until the epoxy equivalent was 727. The resulting reaction product was then diluted with methyl isobutyl ketone until the solid content was 80%. Next, 179 parts of diethanolamine and 89 parts of a ketimine (90% grade) of diethylenetriamine and methyl isobutyl ketone were added and the mixture was reacted at 120°C for 4 hours. Further, methyl isobutyl ketone was added to obtain a polyfunctional amine-modified epoxy resin solution (A1) having amino groups and a solid content of 75%. The resulting epoxy resin (A1) had an amine value of 77.6 mgKOH / g, an average degree of polyfunctionalization (X1) of 0.10, and an average polyfunctionalization concentration (Y1) of 0.06.

[0095] <Examples 1-2 to 1-12 and Comparative Example 1-1> Amine-modified epoxy resin solutions A2 to A13 were prepared in the same manner as in Example 1-1, except for the formulations shown in Table 1 below.

[0096] [Table 1] Note that the amine values ​​in the table above do not include amines from polyfunctionalizing agents.

[0097] The components used in the manufacture of the epoxy resin are as follows: <Epoxy compounds> • Bisphenol A type epoxy resin: Manufactured by Mitsubishi Chemical Corporation, product name jER828EL (2 functional groups, epoxy equivalent weight 187, weight-average molecular weight 375)

[0098] <Multifunctionalizing agent> • Polyfunctionalizing agent 1: Polyamidoamine (mixture; details are shown in Table 2 below) • Polyfunctionalizing agent 2: Ethylenediamine (molecular weight 60, number of functional groups 4) • Multifunctionalizing agent 3: Dimer acid (mixture; details are shown in Table 2 below) • Polyfunctionalizing agent 4: trimellitic acid (molecular weight 210, number of functional groups 3) • Polyfunctionalizing agent 5: Diethanolamine (molecular weight 105, number of functional groups 3) • Polyfunctionalizing agent 6: 3,5-diaminobenzoic acid (molecular weight 152, number of functional groups 3)

[0099] • Polyfunctionalizing agent 7: Compound with the following structural formula (molecular weight 592, number of functional groups 3) [ka]

[0100] • Polyfunctionalizing agent 8: Compound with the following structural formula (mixture; details are shown in Table 2 below) [ka] (n is a non-negative integer)

[0101] [Table 2] The polyfunctionalizers 1, 3, and 8 described above are mixtures of two-functional components and three- or more-functional components. Components with three or more functional properties are classified as polyfunctional components.

[0102] [Cationic electrodeposition paint] <Manufacturing of pigment dispersion resins> In a flask equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, 1010 parts of bisphenol A type epoxy resin (epoxy equivalent 190, weight-average molecular weight 350) were added to 390 parts of bisphenol A, 240 parts of Praxel 212 (manufactured by Daicel Chemical Industries, Ltd., trade name polycaprolactone diol, weight-average molecular weight approximately 1,250), and 0.2 parts of dimethylbenzylamine. The mixture was reacted at 130°C until the epoxy equivalent was approximately 1090. Next, 134 parts of dimethylethanolamine and 150 parts of a 90% aqueous lactic acid solution were added, and the mixture was reacted at 90°C until the epoxy groups disappeared. Then, propylene glycol monomethyl ether was added to adjust the solid content, and a pigment dispersion resin (R) containing a quaternary ammonium base with a solid content of 60% was obtained.

[0103] <Manufacturing of pigment dispersion paste> (Pigment dispersion paste (P1)) 8.3 parts (5 parts solids) of pigment dispersion resin (R) containing a quaternary ammonium base with a solid content of 60%, 14 parts titanium dioxide, 6.0 parts purified clay, 0.3 parts carbon black, 3.5 parts bismuth hydroxide, and 20.3 parts deionized water were added and dispersed in a ball mill for 20 hours to obtain a pigment dispersion paste (P1) with a solid content of 55%.

[0104] <Production of blocked polyisocyanate compounds (BNCO(B1))> 270 parts of Cosmonate M-200 (manufactured by Mitsui Chemicals, trade name Crude MDI, NCO group content 31.3%) and 127 parts of methyl isobutyl ketone were added to a reaction vessel and the temperature was raised to 70°C. 236 parts of ethylene glycol monobutyl ether were added dropwise over 1 hour, and the temperature was then raised to 100°C. Samples were taken over time while maintaining this temperature, and infrared absorption spectroscopy was used to confirm that the absorption of unreacted isocyanate groups had disappeared, yielding a blocked polyisocyanate compound (BNCO(B1)) with a resin solids content of 80%.

[0105] <Example 2-1> 100 parts (solids) of the amine-modified epoxy resin (A-1) obtained in Example 1-1 and 45 parts (solids) of the blocked polyisocyanate compound (BNCO) (B1) were mixed, and 13 parts of 10% acetic acid were added and the mixture was stirred uniformly. Then, deionized water was added dropwise over approximately 15 minutes while stirring vigorously to obtain an emulsion with a solids content of 34%. Next, 294 parts of the above emulsion (100 parts solids), 52.4 parts of pigment dispersion paste (P1), and deionized water were added to produce a cationic electrodeposition coating (X1) with a solids content of 20%. The average polyfunctionalization concentration (Y2) of the cationic electrodeposition coating (X1) is shown in Table 3 below. The obtained cationic electrodeposition paint was used for electrodeposition coating, and the resulting electrodeposited coating film was obtained by heat curing. The surface finish, corrosion resistance (salt spray), corrosion resistance (salt immersion), and oil repellency of the obtained electrodeposited coating film were evaluated. The results are shown in Table 3.

[0106] <Examples 2-2 to 2-18, Comparative Example 2-1> Cationic electrodeposition coatings X2 to X19 with a solid content of 20% were prepared in the same manner as in Example 2-1, except that the amine-modified epoxy resin was as shown in Table 3. For example, Example 2-13 is an example in which 30 parts A6 and 70 parts A13 were used as the amine-modified epoxy resin, and the average polyfunctionalization concentration (Y2) is calculated as the average of the two types of amine-modified epoxy resins mixed, in units of mmol / g. The obtained cationic electrodeposition paint was used for electrodeposition coating, and the resulting electrodeposited coating film was obtained by heat curing. Upon examining the cross-section of the electrodeposited coating, it was found that all of them were single-layer coatings (without an interface). The resulting electrodeposited coatings were evaluated for their surface finish, corrosion resistance (salt spray), corrosion resistance (salt immersion), and oil repellency. The results are shown in Table 3. In this invention, if even one of the four evaluations results in a failing grade "C", the product will be considered unsuccessful. Note that all resin content values ​​in the table represent solid content.

[0107] [Table 3]

[0108] <Rating> The finish, corrosion resistance (salt spray), corrosion resistance (salt immersion), and oil repellency were evaluated as follows. Any coating (paint) with even one "C" rating was deemed unacceptable.

[0109] (Finished skin) Cold-rolled steel sheets (0.8 mm × 150 mm × 70 mm) treated with zinc phosphate were electrodeposited at a bath temperature of 28°C and a load voltage that resulted in a cured coating thickness of 18 μm. The coating was then heated and cured at 170°C for 20 minutes to obtain test plates. Subsequently, the surface roughness value (Ra) of the coated test plate was measured using a SurfTest 301 (Mitutoyo Corporation, product name: surface roughness meter) with a cutoff of 0.8 mm, as defined in JIS B 601, and evaluated according to the following criteria. S is the best evaluation, and C is a failure. S: Surface roughness value (Ra) is less than 0.15. A: Surface roughness value (Ra) is 0.15 or higher and less than 0.25. B1: Surface roughness value (Ra) is 0.25 or higher and less than 0.35. B2: Surface roughness value (Ra) is 0.35 or higher and less than 0.45. C: Surface roughness value (Ra) is 0.45 or higher.

[0110] (Corrosion resistance (salt spray)) Cold-rolled steel sheets (0.8 mm × 150 mm × 70 mm) treated with zinc phosphate were electrodeposited with a coating applied at a bath temperature of 28°C and a load voltage that resulted in a cured coating thickness of 18 μm. The coating was then heated and cured at 170°C for 20 minutes to obtain a test plate. Subsequently, cross-cut scratches were made in the coating of the test plate using a utility knife so as to reach the substrate. A 35°C salt spray test was then performed on this plate for 840 hours in accordance with JIS Z-2371, and the rust and blister width on one side of the cut area were evaluated according to the following evaluation criteria. S is the best evaluation, and C is a failure. S: The maximum width of rust and blistering is 2.0 mm or less on one side of the cut section, indicating excellent corrosion resistance. A: The maximum width of rust and blistering exceeds 2.0 mm on one side of the cut section, but is 3.0 mm or less, indicating good corrosion resistance. B: The maximum width of rust and blistering exceeds 3.0 mm on one side of the cut section, but is 4.0 mm or less, and the corrosion resistance is standard. C: The maximum width of rust and blistering exceeds 4.0 mm on one side of the cut section, indicating poor corrosion resistance.

[0111] (Corrosion-resistant (saltwater immersion)) Cold-rolled steel sheets (0.8 mm × 150 mm × 70 mm) treated with zinc phosphate were electrodeposited with a coating applied at a bath temperature of 28°C and a load voltage that resulted in a cured coating thickness of 18 μm. The coating was then heated and cured at 170°C for 20 minutes to obtain a test plate. Subsequently, the test plate was immersed in a 5% by weight salt solution at 50°C for 600 hours. After that, the test plate was removed, the moisture on the coating surface was wiped off, and then cellophane adhesive tape was applied to the coating surface and peeled off instantly. The percentage of the coating that peeled off was evaluated using this peel test. S is the best evaluation, and C is a failure. S: Less than 5% of the coating peeled off the test coating area. A: The percentage of the coating that peeled off from the test coating area was 5% or more, but less than 10%. B: The percentage of the coating that peeled off from the test coating area was 10% or more, but less than 20%. C: The percentage of the coating that peeled off from the test coating area was 20% or more.

[0112] (Oil-resistant) A wet film was obtained by electrodepositing a zinc phosphate-treated cold-rolled steel sheet (0.8 mm × 150 mm × 70 mm) at a bath temperature of 28°C and a load voltage that resulted in a cured coating thickness of 18 μm. After washing this wet film with water and letting it sit for 30 minutes, 0.2 ml of rust-preventive machine oil (manufactured by Nippon Parkerizing Co., Ltd., product name NOX-RUST320) is evenly scattered and applied during the baking process. After cooling, the coating surface was visually inspected, and the number and size of the repellents were counted and evaluated according to the following evaluation criteria. S is the best evaluation, and C is a failure. S: There are absolutely no craters on the surface of the coating. A: Fewer than 10 craters appeared on the paint film surface. B: More than 10 craters appeared on the paint film surface (all less than 2 mm in diameter). C: More than 10 craters appear on the paint film surface (at least one crater is 2 mm or larger in diameter).

[0113] Although the present invention has been described in detail above with reference to embodiments and examples, the present invention is not limited to the embodiments and examples described above, and various modifications based on the technical concept of the present invention are possible.

Claims

1. An amine-modified epoxy resin obtained by reacting an epoxy resin with an amine compound, The epoxy resin mentioned above is Compounds having one or more epoxy groups, A polyfunctionalizing agent containing compound (A) having a primary amino group, b secondary amino groups, c alcoholic hydroxyl groups, d phenolic hydroxyl groups, e carboxyl groups, f mercapto groups, g sulfonic acid groups, h carboxylic acid anhydride groups, and i epoxy groups (where a, b, c, d, e, f, g, and h are each independent integers of 0 or more, and i is 0 or an integer of 3 or more, and 2a + b + c + d + e + f + g + 2h + i ≥ 3. If b = 1, then a ≠ 1, c ≠ 2, or d + e + f + g + 2h + i ≥ 1. If d ≥ 3, then 2a + b + d + e + f + g + 2h + i ≥ 3. An epoxy resin having a branched main skeleton, obtained by at least reacting the following: The polyfunctionalizing agent contains one or more compounds selected from the group consisting of an amine compound having two or more amino groups, a carboxylic acid compound having three or more carboxyl groups or its anhydride, an epoxy compound having three or more epoxy groups, diaminobenzoic acid, dihydroxybenzoic acid, diaminophenol, and triethanolamine. The amine-modified epoxy resin.

2. An amine-modified epoxy resin obtained by reacting an epoxy resin with an amine compound, The epoxy resin mentioned above is Compounds having one or more epoxy groups, A polyfunctionalizing agent containing compound (A) having a primary amino group, b secondary amino groups, c alcoholic hydroxyl groups, d phenolic hydroxyl groups, e carboxyl groups, f mercapto groups, g sulfonic acid groups, h carboxylic acid anhydride groups, and i epoxy groups (where a, b, c, d, e, f, g, and h are each independent integers of 0 or more, and i is 0 or an integer of 3 or more, such that 2a + b + c + d + e + f + g + 2h + i ≥ 3. If d ≥ 3, then 2a + b + d + e + f + g + 2h + i ≥ 3), It can be obtained by at least reacting the following formula (1); （１）： Average degree of polyfunctionalization (X1) = Number of terminals per molecule of epoxy resin - 2 The epoxy resin is characterized by having an average degree of polyfunctionalization (X1) per molecule of 0.1 or higher, and having a branched main skeleton. The polyfunctionalizing agent contains one or more compounds selected from the group consisting of an amine compound having two or more amino groups, a carboxylic acid compound having three or more carboxyl groups or its anhydride, an epoxy compound having three or more epoxy groups, diaminobenzoic acid, dihydroxybenzoic acid, diaminophenol, and triethanolamine. The amine-modified epoxy resin.

3. The epoxy resin is The following formula (2); （２）： Average polyfunctionalization concentration (Y1) = Average polyfunctionalization degree of epoxy resin (X1) ÷ Weight-average molecular weight of epoxy resin Mw × 1000 The amine-modified epoxy resin according to claim 2, wherein the average polyfunctionalization concentration (Y1) indicated by is 0.10 or higher.

4. The amine-modified epoxy resin according to any one of claims 1 to 3, wherein the polyfunctionalizing agent further comprises compound (B) having j primary amino groups, k secondary amino groups, m alcoholic hydroxyl groups, n phenolic hydroxyl groups, p carboxyl groups, q mercapto groups, r sulfonic acid groups, s carboxylic acid anhydride groups, and t isocyanate groups (where j, k, m, n, p, q, r, and s are each independently integers of 0 or more, and 2j + k + m + n + p + q + r + 2s ≤ 2), and the content ratio of compound (A) to compound (B) is in the range of 1 / 99 to 99 / 1.

5. An electrodeposition coating comprising an amine-modified epoxy resin according to any one of claims 1 to 4.

6. A cationic electrodeposition coating comprising an amine-modified epoxy resin according to any one of claims 1 to 4, a curing agent, and a bismuth compound.

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