Modified epoxy resins and cationic electrodeposition coatings

Abstract

To provide a modified epoxy resin which is excellent in curability and storage stability at low temperatures when a catalyst of low activity is used, and coating film finishing property and anticorrosion property (throwing power) when constituting a coating; an aqueous resin dispersion where the modified epoxy resin or its modified product is dispersed in an aqueous medium; and a cationic electro-deposition coating containing the modified epoxy resin.SOLUTION: A modified epoxy resin is obtained by reacting compounds containing a compound (α) having one or more epoxy groups, a compound (β) which is used as necessary, has functional groups reactive with an epoxy group, and has the total of functional valences of the functional groups of 3 or more, and a compound (γ) which has functional groups reactive with an epoxy group and has the total of functional valences of the functional groups of 1 or 2, wherein an average polyfunctional degree (X1) represented by the following formula (1) per one molecule of a modified epoxy resin is 0.10 or more. Expression (1): average functional degree (X1)=terminal number per one molecule of modified epoxy resin-2.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to modified epoxy resins and cationic electrodeposition coatings. More specifically, it relates to modified epoxy resins obtained by reacting specific components, aqueous resin dispersions in which modified epoxy resins or modified products thereof are dispersed in an aqueous medium, cationic electrodeposition coatings containing modified epoxy resins, and methods for producing these. [Background technology]

[0002] Epoxy resins have excellent properties such as mechanical strength, adhesion, and chemical resistance, and are widely used as coating resins in paints. Among paints, electrodeposition paints are widely used for painting metal products (for example, automobile parts, electrical equipment parts, and other industrial equipment) that require these properties, due to their excellent workability and the good corrosion resistance of the resulting paint film. Cationic electrodeposition coatings are provided in a form in which a film-forming resin, which is a cationic resin (e.g., an amino group-containing epoxy resin), a curing agent (e.g., a blocked polyisocyanate compound), and a curing catalyst are dissolved or dispersed in an aqueous medium. This coating composition is used as a coating bath, and an electric current is passed through the object to be coated with the object as the cathode to form a deposited coating film on the object. After that, the deposited coating film is heated to form a cross-linked and cured coating film.

[0003] In cationic electrodeposition coatings, organotin compounds have generally been used as curing catalysts to promote crosslinking reactions. However, although organotin compounds have very high catalytic performance, there have been concerns about safety and environmental impact, which may lead to restrictions on their use. As a result, there has been a demand for catalysts to replace organotin compounds. Bismuth compounds and zinc compounds have been considered as alternatives, but they have problems such as being expensive, having insufficient catalytic effect, or being unstable in the coating. Furthermore, even when using organotin compound catalysts, it was necessary to maximize the hardening performance. 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).

[0004] 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. Furthermore, it was necessary to improve the coating's adherence in order to enhance the corrosion resistance of the coated object with a complex shape.

[0005] 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]

[0006] [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 project] [Problems that the invention aims to solve]

[0007] The problem that this invention aims to solve is to provide a modified 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 (adhesion) when used in paints. Furthermore, the invention aims to provide an aqueous resin dispersion in which the modified epoxy resin or a modified product thereof is dispersed in an aqueous medium, and a cationic electrodeposition paint containing the modified epoxy resin. [Means for solving the problem]

[0008] As a result of diligent research to solve the aforementioned problems, the present inventors have found that the aforementioned problems can be solved by a modified epoxy resin obtained by reacting specific components, an aqueous resin dispersion in which the modified epoxy resin or a modified product thereof is dispersed in an aqueous medium, and a cationic electrodeposition coating containing the modified epoxy resin, and have completed the present invention. Specifically, it is as follows: Item 1: A compound (α) having one or more epoxy groups, A compound (β) having a functional group that reacts with an epoxy group, and the sum of the functional values ​​of the functional groups is 3 or higher, which may be used as needed. A compound (γ) having a functional group that reacts with an epoxy group, wherein the sum of the functional values ​​of the functional groups is monovalent or divalent, A modified epoxy resin obtained by reacting a compound containing, A modified epoxy resin having an average polyfunctionalization degree (X1) per molecule of the modified epoxy resin represented by the following formula (1) of 0.10 or higher. Formula (1): Average degree of polyfunctionalization (X1) = Number of end molecules per molecule of modified epoxy resin - 2 Item 2: The modified epoxy resin according to Item 1, wherein the compound (β) is contained in a proportion of 1% by mass or more and 70% by mass or less of the total solid content mass of the compound (α), the compound (β), and the compound (γ), the proportion of the compound (α) is 1% by mass or more and 50% by mass or less of the compound (β), and the proportion of the compound (γ) is 10% by mass or more and 90% by mass or less of the compound (γ). Item 3: The modified epoxy resin according to Item 1 or 2, wherein the functional group that reacts with the epoxy group of the compound (β) is at least one functional group selected from the group consisting of phenolic hydroxyl group, isocyanate group, carboxyl group, primary and / or secondary amino groups. Item 4: The modified epoxy resin according to any one of Items 1 to 3, wherein the average polyfunctionalization concentration (Y1) represented by the following formula (2) is 0.10 or more. Formula (2): Average polyfunctionalization concentration (Y1) = average polyfunctionality degree (X1) of the modified epoxy resin ÷ weight average molecular weight Mw of the modified epoxy resin × 1000 Item 5: The modified epoxy resin according to any one of Items 1 to 4, wherein the compound (γ) contains a compound (γ1) having no amino group. Item 6: The modified epoxy resin according to any one of Items 1 to 5, wherein the compound (γ) is a compound having no amino group. Item 7: The modified epoxy resin according to any one of Items 1 to 6, wherein at least a part of the terminal of the modified epoxy resin has an organic group represented by the following structural formula (1) or the following structural formula (2).

Chemical formula

Chemical formula

[0009] The present invention provides a modified epoxy resin that exhibits excellent curability when using a low-activity catalyst or at low temperatures, as well as excellent storage stability, and provides excellent coating finish and corrosion resistance (adhesion) when used in paints. The invention also provides an aqueous resin dispersion in which the modified epoxy resin or a modified product thereof is dispersed in an aqueous medium, and a cationic electrodeposition paint containing the modified epoxy resin. Furthermore, the present invention provides an aqueous resin dispersion and an electrodeposition coating that exhibit excellent curability, storage stability, coating finish, and corrosion resistance, even when using a low-activity catalyst or at low temperatures. [Modes for carrying out the invention]

[0010] In the present invention, "modified epoxy resin" refers to a resin obtained by reacting the epoxy groups of an epoxy resin and / or epoxy compound with a compound having a functional group that reacts with the epoxy groups, and does not necessarily have epoxy groups. In the present invention, "epoxy resin" refers to a resin containing epoxy groups and / or epoxy groups of an epoxy compound reacted with a compound having functional groups that react with epoxy groups, but does not necessarily contain epoxy groups. In this invention, "epoxy" may be abbreviated as "EP".

[0011] In this invention, "polyfunctional" means that the number of functional values ​​of a compound having functional groups, or the sum of those values, is greater than 2. However, in this invention, even if there are two or more functional groups generated and / or introduced by the reaction between the terminal epoxy groups of the epoxy resin and a reactive functional group-containing compound, these terminal groups are counted as one functional group. Furthermore, secondary hydroxyl groups inside the epoxy resin molecule are not included in the aforementioned functional value due to their low reactivity. In this invention, "functional group" in polyfunctionality refers to a reactive functional group that can react with a curing agent such as a blocked polyisocyanate compound. Furthermore, in this invention, having, for example, "one" functional group in a compound may be referred to as "monofunctional," "single-unit," or "monovalent."

[0012] [Modified epoxy resin] The modified epoxy resin of the present invention is obtained by reacting a compound comprising (α) having one or more epoxy groups, (β) having a functional group that reacts with the epoxy group and the sum of the functional values ​​of the functional groups is 3 or higher, and (γ) having a functional group that reacts with the epoxy group and the sum of the functional values ​​of the functional groups is 1 or 2, and is defined by the following formula (1): Average degree of polyfunctionalization (X1) = Number of end molecules per molecule of modified epoxy resin - 2 This modified epoxy resin has an average degree of polyfunctionalization (X1) per molecule of the modified epoxy resin shown as 0.10 or higher. The modified epoxy resin of the present invention is obtained by (i) reacting at least compound (α), compound (β), and compound (γ), and / or (ii) reacting at least compound (α) and compound (γ).

[0013] <Average degree of polyfunctionalization of modified epoxy resin (X1)> For example, if one molecule is divided into three ends, X will be 1, and if it is a linear modified 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 the ends of a modified epoxy resin by reacting it with a polyfunctional modifying agent (for example, a carboxylic acid compound 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 the modified epoxy resin are not defined as "polyfunctionalization" in this invention from the standpoint of reactivity. In this invention, "multifunctionalization" refers to a modification where the main skeleton of the modified epoxy resin is branched.

[0014] The modified epoxy resin of the present invention exhibits excellent curability, particularly when using low-activity catalysts or at low temperatures, as well as excellent storage stability. Furthermore, when paints, especially electrodeposition paints, are prepared using this modified epoxy resin, they exhibit excellent coating finish and corrosion resistance (adhesion). This property is closely related to the degree of polyfunctionalization of the modified epoxy resin. In particular, by adopting the average degree of polyfunctionalization per molecule of the modified epoxy resin (X1) and setting its range to a specific range, the aforementioned property can be made desirable.

[0015] Methods for obtaining polyfunctionalized modified epoxy resins include (1) a method of reacting an epoxy compound (containing one or more epoxy groups, preferably two or more) with a polyfunctionalizing agent (compound (β)) having functional groups that react with epoxy groups and the sum of the functional values ​​of the functional groups being 3 or higher (polyfunctionalization by a polyfunctionalizing agent), and (2) a method of polyfunctionalizing by reacting a secondary hydroxyl group inside the molecule of the epoxy compound with at least one terminal epoxy group of another epoxy compound (polyfunctionalization by cooking). Both methods can be suitably used. From the viewpoint of stably producing polyfunctionalized modified epoxy resins, it is preferable to use at least method (1) above.

[0016] When obtaining a polyfunctionalized modified epoxy resin by the method described in (1) above (polyfunctionalization with a polyfunctionalizing agent), the average degree of polyfunctionalization (N) per molecule of the modified epoxy resin with 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].

[0017] 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) *End-capturing agents: Monophenol compounds, monocarboxylic acids, etc., that have only one phenolic hydroxyl group. *Functional groups that react with epoxy groups: phenolic hydroxyl groups, isocyanate groups, carboxyl groups, primary and / or secondary amino groups, etc. *Number of polyfunctional functions due to polyfunctionalizing agent = (Valence of polyfunctionalizing agent - 2) × Amount of polyfunctionalizing agent (mol)

[0018] 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 modified epoxy resin by cooking is given by the following formula: Average degree of polyfunctionalization due to cooking (M) = (2-m) / (1-m)-2 This can be determined by [method]. *m: Excess epoxy amount in the basic formulation Here, the excess epoxy (EP) in the basic formulation is calculated as follows: Excess EP 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 modified epoxy resin 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.

[0019] Then, the average degree of polyfunctionalization per molecule of the modified epoxy resin (X1) is calculated from the average degree of polyfunctionalization due to the polyfunctionalizing agent (N) and the average degree of polyfunctionalization due to the cooking process (M) using the following formula: Average degree of polyfunctionalization (X1)=(N+2)×(M+1)-M-2 It can be calculated using [this method]. In the modified epoxy resin of the present invention, the average degree of polyfunctionalization (X1) per molecule of the modified epoxy resin can be typically 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.

[0020] <Average polyfunctionalization concentration (Y1) of modified epoxy resin> The modified epoxy resin of the present invention preferably has an average polyfunctionalization concentration (Y1) represented by the following formula (2) of 0.1 or higher. Formula (2): Average polyfunctionalization concentration (Y1) = Average polyfunctionalization degree of modified epoxy resin (X1) ÷ Weight-average molecular weight of modified epoxy resin Mw × 1000 Here, the weight-average molecular weight Mw of the modified epoxy resin is calculated as follows: The weight-average molecular weight (Mw) of a modified epoxy resin is calculated as follows: Mw = Σ(amount of each raw material in the basic formulation (moles) × molecular weight of each raw material).

[0021] The average number of functional groups per molecule of a polyfunctionalizing agent component with three or more functions, when the functional value of the functional group that reacts with the epoxy group is 1, can be calculated using the following formula. Average number of functional groups = Σ(percentage of each polyfunctionalizing agent component ÷ molecular weight of each polyfunctionalizing agent component × each polyfunctionalizing agent component) (Number of functional groups of the polyfunctionalizing agent component) / Σ(Percentage of each polyfunctionalizing agent component ÷ Molecular weight of each polyfunctionalizing agent component)

[0022] The curability of the modified epoxy resin of the present invention, particularly when using a low-activity catalyst or at low temperatures, as well as its storage stability, and properties such as the finish and corrosion resistance (adhesion) of the electrodeposited coating when using the modified epoxy resin, are closely related to the average polyfunctionalization concentration of the modified epoxy resin, in addition to the degree of polyfunctionalization of the modified epoxy resin. In particular, by adopting the average degree of polyfunctionalization per molecule of the modified epoxy resin (X1) and the average polyfunctionalization concentration (Y1) as the degree of polyfunctionalization of the modified epoxy resin, and setting the ranges of each to specific ranges, the aforementioned properties can be optimized.

[0023] In the modified epoxy resin of the present invention, the average polyfunctionalization concentration (Y1) per gram of solid content of the modified epoxy resin is usually 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.

[0024] <Compounds (α) having one or more epoxy groups> Compound (α) having one or more epoxy groups is one of the components of the modified epoxy resin of the present invention, and 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 compound (α) having one or more epoxy groups is preferably 2 to 8, more preferably 2 to 6, even more preferably 2 to 4, and most preferably 2. The weight-average molecular weight of compound (α) having one or more epoxy groups is not particularly limited, but it is preferable to have a weight-average molecular weight in the range of at least 300, preferably 400 to 4,000, and more preferably 800 to 2,500. Similarly, its epoxy equivalent is not particularly limited, but it is suitable to have an epoxy equivalent in the range of at least 160, preferably 180 to 2,500, and more preferably 400 to 1,500. As compound (α) having one or more epoxy groups, 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.

[0025] In the present invention, epoxy compounds obtained by the reaction of polyphenol compounds with epihalohydrins are preferably used. Any known polyphenol compound can be used without limitation to react with the epihalohydrin. For example, one or more compounds 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, phenol novolac, cresol novolac, etc. can be used.

[0026] As the compound (α) having one or more epoxy groups, an epoxy compound containing a polyalkylene oxide chain in its molecule can be used. Typically, such an epoxy compound can be obtained by (a) a method of introducing a polyalkylene oxide chain by reacting an epoxy compound having at least one, preferably two or more epoxy groups with an alkylene oxide or polyalkylene oxide, or by (b) a method of introducing a polyalkylene oxide chain by reacting the polyphenol compound with a polyalkylene oxide having at least one, preferably two or more epoxy groups. 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. From the viewpoint of improving stability, finish, and corrosion resistance during electrodeposition coating formation, the content of the polyalkylene oxide chain is 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 modified epoxy resin.

[0027] As the compound (α) having one or more epoxy groups, diglycidyl dimer acid esters can be used. Such epoxy compounds are obtained by introducing glycidyl groups into dimer acid, which is 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 having 11 to 22 carbon atoms are preferred from the viewpoint of the flexibility and hydrophobicity of the compound (α) having one or more epoxy groups. As the aforementioned 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.

[0028] 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 as compound (α) having one or more epoxy groups.

[0029] Particularly preferred are epoxy compounds obtained by the reaction of a polyphenol compound with an epihalohydrin (e.g., epichlorohydrin), which are epoxy compounds derived from bisphenol A and represented by the following formula. [ka]

[0030] 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 molecule of the modified epoxy resin 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.

[0031] <A compound (β) having a functional group that reacts with an epoxy group, and the sum of the functional values ​​of the functional groups is 3 or greater> Compound (β) having a functional group that reacts with an epoxy group, and the sum of the functional values ​​of the functional groups being 3 or higher, can be used as a component of the modified epoxy resin of the present invention as needed, and can be suitably used as a polyfunctionalizing agent to polyfunctionalize the modified epoxy resin. In the present invention, examples of "functional groups that react with epoxy groups" include primary amino groups (functional value 2), secondary amino groups (functional value 1), alcoholic hydroxyl groups (functional value 1), phenolic hydroxyl groups (functional value 1), isocyanate groups (functional value 1), carboxyl groups (functional value 1), mercapto groups (functional value 1), sulfonic acid groups (functional value 1), and carboxylic acid anhydride groups (functional value 2). The compound (β) may contain one or more compounds selected from the group consisting of a phenolic compound having a trivalent or greater phenolic hydroxyl group, an isocyanate compound having a trivalent or greater isocyanate group, an amine compound having a trivalent or greater amino group, a carboxylic acid compound having a trivalent or greater carboxyl group or its anhydride, and an alcoholic compound having a trivalent or greater alcoholic hydroxyl group.

[0032] Furthermore, the compound may have a primary amino group, a secondary amino group, an alcoholic hydroxyl group, a phenolic hydroxyl group, an isocyanate group, a carboxyl group, a mercapto group, a sulfonic acid group, and a carboxylic acid anhydride group in the molecule such that the sum of the functional values ​​of the functional groups is 3 or higher. For example, one or more selected from the group consisting of diaminobenzoic acid, dihydroxybenzoic acid, diaminophenol, etc.

[0033] (Phenol compounds having trivalent or greater phenolic hydroxyl groups) Phenolic compounds having a trivalent or greater phenolic hydroxyl group are one or more compounds that have three or more hydroxyl groups (phenolic hydroxyl groups) attached to an aromatic ring within their molecule. Examples of trivalent phenolic compounds include 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-trimethylphenol), and 2,3,4-trihydro Xydiphenylmethane, 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-methylphenyl) One or more substances selected from the group consisting of (4-hydroxyphenyl)-4-(4-hydroxy-α,α-dimethylbenzyl)-ethylbenzene, etc. may be used.

[0034] Examples of phenol compounds having a valency of 4 or more include, for example, 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-tetrahydroxyanthracene, 2,4,6-tris[(4-hydroxyphenyl)methyl]-1,3-benzenediol, hexahydroxybenzene, 2,3,6,7,10,11-hexahydroxytriphenylene hydrate, etc., and one or more selected from the group consisting of these can be used.

[0035] In addition, one or more selected from the group consisting of phenolic resins obtained by subjecting a phenolic compound (phenol, cresol, bisphenolic compound, etc.) component and aldehydes (formaldehyde, acetaldehyde, benzaldehyde, hydroxybenzaldehyde, crotonaldehyde, glyoxal, etc.) to a condensation reaction in the presence of a catalyst can be used. For example, the following structural formula (A)

Chemical formula

[0036] In the present invention, it is preferable to use one or more compounds represented by the above structural formula (A) as trivalent or higher phenolic compounds. 21 ~R 23 In this regard, organic groups having hydrogen or carbon are preferred. Examples of organic groups having carbon include monovalent alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, propyl, and butyl groups.

[0037] (Isocyanate compounds having isocyanate groups with a valency of 3 or higher) As isocyanate compounds having a trivalent or higher isocyanate group, one or more compounds having three or more isocyanate groups in their molecule are used. For example, aliphatic triisocyanates such as 2,6-diisocyanatohexanoate 2-isocyanatoethyl (lysine ester triisocyanate), 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, and 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyloctane. T; 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 2-(3-isocyanatopropyl)-2,6-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-I Socyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 6-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, bicycloheptane triisocyanate, 6-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3- Alicyclic triisocyanates such as socyanatopropyl)-bicyclo(2.2.1)heptane, aromatic aliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene, aromatic triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene; aromatic tetraisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate, shown in structural formula (B) below. [ka] (In equation (B), n is an integer greater than or equal to 1.) One or more compounds selected from the group consisting of crude compounds of various polyisocyanates such as crude MDI [polymethylene polyphenyl isocyanate] (polymeric MDI) and crude TDI [crude tolylene diisocyanate] can be used.

[0038] Also, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, methylene diisocyanate, dimer Aliphatic diisocyanates such as acid diisocyanates, methyl 2,6-diisocyanatohexanoate (common name: lysine diisocyanate); 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: isophorone diisocyanate) Anate, 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or mixtures thereof, methylenebis(4,1-cyclohexanediyl) diisocyanate (common name: hydrogenated MDI), norbornane diisocyanate, etc. Alicyclic diisocyanates; aromatic aliphatic diisocyanates such as methylenebis(4,1-phenylene) diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof;One or more compounds selected from the group consisting of trimers or isocyanurates of aromatic diisocyanates such as m-phenylenediisocyanate, p-phenylenediisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, 2,4-tlylenediisocyanate (common name: 2,4-TDI), or 2,6-tlylenediisocyanate (common name: 2,6-TDI) or mixtures thereof, 4,4'-toluidinediisocyanate, 4,4'-diphenyletherdiisocyanate, diphenylmethane-2,2'-diisocyanate, diphenylmethane-2,4'-diisocyanate, and diphenylmethane-4,4'-diisocyanate, which have three or more isocyanate groups in their molecule, can be used.

[0039] Furthermore, one or more compounds selected from the group consisting of dimers, trimers, biuretes, allophanates, uretodiones, uretoimines, isocyanurates, oxadiazinetriones, crude compounds, etc., that have isocyanate groups of three or more valent values. An isocyanate compound having a trivalent or higher isocyanate group may be a blocked polyisocyanate compound, which is a compound in which the isocyanate group is blocked with a blocking agent.

[0040] Examples of the blocking agents include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; aliphatic alcohols such as methanol, ethanol, propanol, butanol, amyl alcohol, and lauryl alcohol; ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylolurea, methylolmelamine, diacetone alcohol, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methyl hydrate. Alcohol-based compounds such as thacrylates; oxime-based compounds such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime; active methylene-based compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone; butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, and ethylthiophenol. Mercaptans such as acetanolide; acid amides such as acetanilide, acetanisidide, acetotoluid, acrylamide, methacrylamide, acetic acid amide, stearamide, and benzamide; imides such as succinimide, phthalimide, and maleimide; amines such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, and butylphenylamine; ureas such as urea, thiourea, ethyleneurea, ethylenethiourea, and diphenylurea;Examples of compounds include carbamic acid esters such as phenyl N-phenylcarbamate; imines such as ethyleneimine and propyleneimine; sulfites such as sodium bisulfite and potassium bisulfite; and azole compounds. The azole compounds include one or more selected from the group consisting of pyrazoles or pyrazole derivatives such as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole; imidazoles or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole, and 2-phenylimidazole; and imidazoline derivatives such as 2-methylimidazoline and 2-phenylimidazoline.

[0041] In the present invention, as a compound containing a trivalent or higher isocyanate group, preferably one or more selected from the group consisting of isocyanurates of aliphatic diisocyanates, isocyanurates of aromatic aliphatic diisocyanates, isocyanurates of aromatic diisocyanates, crude compounds of polyisocyanates, etc., can be used. Particularly preferably, one or more selected from the group consisting of isocyanurates of hexamethylene diisocyanates, crude MDI (polymeric MDI), and crude TDI can be used.

[0042] (Amine compounds having a trivalent or greater amino group) As amine compounds having a trivalent or higher amino group, one or more compounds having a primary or secondary amino group, and possessing a primary amino group (divalent) and / or a secondary amino group (monovalent) in the molecule, with a valency of trivalent or higher, are used. For example, 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, 3,3',4,4'-tetraaminodiphenyl sulfone, 3,3',4,4'-tetraaminodiphenyl ketone, 3, One or more substances selected from the group consisting of 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, etc.

[0043] (Carboxylic acid compounds having trivalent or greater carboxyl groups, or their anhydrides) As a carboxylic acid compound having a trivalent or higher carboxyl group, or its anhydride, one or more compounds having three or more carboxyl groups in the molecule, which may be anhydride groups, are used. For example, one or more selected from the group consisting of 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, biphenyltetracarboxylic acid, diphenylsulfonetetracarboxylic 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, and their anhydrides.

[0044] (Alcoholic compounds having trivalent or higher alcoholic hydroxyl groups) As an alcohol-based compound having three or more alcoholic hydroxyl groups, one or more compounds having three or more alcoholic hydroxyl groups in the molecule can be used. One or more compounds selected from the group consisting of glycerin, trimethylolethane, trimethylolpropane, trioxyisobutane, butanetriol, pentanetriol, hexanetriol, triethanolamine, polyoxypropylenetriol, polyoxyethylenetriol, polyoxyethylenepropylenetriol, pentaerythritol, etc. can be used.

[0045] Furthermore, the compound may have a total of three or more primary amino groups, secondary amino groups, alcoholic hydroxyl groups, phenolic hydroxyl groups, isocyanate 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, and diaminophenol may be used.

[0046] <Having a functional group that reacts with an epoxy group, and the sum of the functional values ​​of the said functional group is monovalent or divalent. Compound (γ)> It has a functional group that reacts with an epoxy group, and the sum of the functional valencies of the said functional group is monovalent or divalent. Compound (γ) can be suitably used as an end-capturing agent or chain extender for sealing or extending the ends of the modified epoxy resin of the present invention. In the present invention, the "functional group that reacts with the epoxy group" is the same functional group as the "functional group that reacts with the epoxy group" in compound (β). It has a functional group that reacts with an epoxy group, and the sum of the functional valencies of the said functional group is monovalent or divalent. The compound (γ) is contained as a component of the modified epoxy resin of the present invention and includes, for example, one or more compounds selected from the group consisting of monovalent or divalent phenolic compounds, alcoholic compounds, carboxylic acidic compounds, isocyanate compounds, etc. Furthermore, it is preferable that the compound (γ) contains a compound (γ1) that does not have an amino group, and it is even preferable that the compound (γ) does not have an amino group.

[0047] Divalent phenolic compounds are compounds that have two hydroxyl groups bonded to an aromatic ring within the molecule. Examples of divalent phenolic compounds include one or more 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, biphenol, etc.

[0048] In the present invention, when the compound (β) having a trivalent or higher functional group that reacts with an epoxy group includes the compound represented by structural formula (A), the compound having one or more active hydrogens in one molecule is represented by the following structural formula (C). [ka] (In equation (C), s represents an integer between 0 and 4, and t represents an integer between 0 and 4. R 31 , R 32 These are each independently monovalent groups. R is attached to the aromatic ring. 31 and / or R 32 If there are multiple instances, they may be identical or different from one another. 31 and / or R 32 It is preferable that the compound contains the compound represented by ).

[0049] As the dihydric alcohol compound, one or more compounds selected from the group consisting of alkylene glycols (ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, etc.) and glycerin can be used. As the divalent carboxylic acid compound, 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.

[0050] Examples of divalent isocyanate compounds include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and methylene diisocyanate. Aliphatic diisocyanates such as isocyanates, dimer diisocyanates, and methyl 2,6-diisocyanatohexanoate (common name: lysine diisocyanate); 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: lysine diisocyanate). Sophorone diisocyanate, 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or mixtures thereof, methylenebis(4,1-cyclohexanediyl) diisocyanate (common name: hydrogenated MDI), norbornane diisocyanate Alicyclic diisocyanates such as nates; aromatic aliphatic diisocyanates such as methylenebis(4,1-phenylene) diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof;Aromatic diisocyanates such as m-phenylenediisocyanate, p-phenylenediisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, 2,4-tolylenediisocyanate (common name: 2,4-TDI) or 2,6-tolylenediisocyanate (common name: 2,6-TDI) or mixtures thereof, 4,4'-toluidinediisocyanate, 4,4'-diphenyletherdiisocyanate, diphenylmethane-2,2'-diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, etc.; dimers, trimers, biuretes, allophanates, uretodiones, uretoimines, oxadiazinetriones, crude diisocyanate compounds of these diisocyanates; and one or more selected from the group consisting of these. The diisocyanate compound may also be a blocked polyisocyanate compound, which is a compound in which the isocyanate group in the diisocyanate or its derivative is blocked with a blocking agent. The blocking agent used is the same as the blocking agent used for isocyanate compounds having a trivalent or higher isocyanate group.

[0051] In the present invention, as the diisocyanate compound, preferably one or more selected from the group consisting of aliphatic diisocyanates, aromatic aliphatic diisocyanates, aromatic diisocyanates, etc., can be used. Particularly preferred are hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, and monomeric MDI (a compound represented by the following structural formula (B') where n=0). [ka] One or more types selected from the group consisting of these can be used.

[0052] It has a functional group that reacts with an epoxy group, and the sum of the functional valencies of the said functional group is monovalent or divalent. As compounds, one or more 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.) can be used. Furthermore, one or more substances selected from the group consisting of hydroxycarboxylic acids (glycolic acid, dimethylolpropionic acid, hydroxypropivalic acid, lactic acid, citric acid, etc.) and mercaptoalkanols (mercaptoethanol, etc.) can be used. Furthermore, a compound (γ1-1-1) having a monovalent functional group that reacts with the epoxy group described later can be suitably used.

[0053] It has a functional group that reacts with an epoxy group, and the sum of the functional valencies of the said functional group is monovalent or divalent. The compound (γ) preferably contains a compound (γ1) that does not have an amino group, and it is preferable that the modified epoxy resin of the present invention substantially does not have an amine value derived from compound (γ1). "Substantially does not have an amine value derived from compound (γ1)" means that in the modified epoxy resin containing compound (γ), the amine value derived from compound (γ1) is 10 mgKOH / g or less, preferably 5 mgKOH / g or less, and more preferably 0 mgKOH / g. Furthermore, it is preferable that the compound (γ1) contains a compound (γ1-1) having a functional group with a monovalent functional value that reacts with an epoxy group. It is even more preferable that the compound (γ) contains both a compound (γ1-1) having a functional group that reacts with an epoxy group and the sum of the functional values ​​of the functional groups is monovalent, and a compound (γ1-2) having a functional group that reacts with an epoxy group and the sum of the functional values ​​of the functional groups is divalent.

[0054] <Amount of each ingredient> The proportions of compound (α), compound (β) (optionally used), and compound (γ) used in the production of the modified epoxy resin of the present invention can be appropriately adjusted according to the desired epoxy equivalent, etc. For example, based on the total solid content mass of compound (α), compound (β), and compound (γ), the amount of each component can be set within the following ranges. Compound (α): For example, 0.5% by mass or more, preferably 1% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, for example, 80% by mass or less, preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 60% by mass or less. • Compound (β): 0% by mass or more, preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, for example, 50% by mass or less, preferably 40% by mass or less, and more preferably 35% by mass or less. • Compound (γ): For example, 5% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, for example, 95% by mass or less, preferably 90% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

[0055] If the content of compound (β), which is a polyfunctionalizing agent, exceeds 50% by mass, the reactivity of the modified epoxy resin may become too high, potentially leading to gelation during synthesis or poor storage stability of the paint.

[0056] <Method for manufacturing modified epoxy resin> A first method for producing the modified epoxy resin of the present invention involves mixing compound (α), compound (β) used as needed, and compound (γ), and reacting them 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. In this invention, a modified epoxy resin can be polyfunctionalized by using a compound (β) which is a polyfunctionalizing agent. Furthermore, for example, a compound (γ) having two active hydrogens in one molecule (a compound having a functional group that reacts with an epoxy group, and the sum of the functional values ​​of the functional groups is divalent) can be used to extend the chain of the modified epoxy resin.

[0057] A second method for producing the modified epoxy resin of the present invention involves reacting at least compound (α) and compound (β) to produce epoxy resin (X), and then reacting at least compound (γ). The reaction temperature can be the same as that of the first method. Furthermore, in the modified epoxy resin obtained by the second manufacturing method, the average degree of polyfunctionalization (X1) can be typically 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. The average polyfunctionalization concentration (Y1) can be typically 0.10 (mmol / g) or higher, 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).

[0058] The solvent used in the method for producing modified epoxy resin 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.

[0059] <Weight-average molecular weight of modified epoxy resin> The weight-average molecular weight of the modified epoxy resin of the present invention 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 the finish of the coating film and corrosion resistance (adhesion) when used to form a paint. 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.

[0060] <Terminal functional groups of modified epoxy resins> It is preferable that the modified epoxy resin has some or all of its terminal functional groups other than epoxy groups. When compound (γ) contains compound (γ1-1), the ends of the modified epoxy resin are sealed by compound (γ1-1), and some or all of the terminal functional groups may be other than epoxy groups. In particular, it is preferable that at least a portion of the end portion of the modified epoxy resin of the present invention has an organic group represented by the following structural formula (1) or structural formula (2). [ka] [In formula (1), R1 and R2 each independently represent a hydrogen atom, a hydroxymethyl group, a C1-C12 alkyl group, or a C1-C13 alkyloxymethyl group. R3 represents a hydrogen atom or a methyl group, and multiple R3s may be the same or different from one another.] [ka] [In formula (2), R4 and R5 each independently represent a hydrogen atom, a hydroxymethyl group, a C1-C12 alkyl group, or a C1-C13 alkyloxymethyl group. R6 represents a hydrogen atom or a methyl group, and multiple R6s may be the same or different from one another. R7, R8, R9 and R 10 Each of these independently represents a hydrogen atom and an alkyl group having 1 to 12 carbon atoms.

[0061] The aforementioned modified epoxy resin at the end can be produced by reacting compound (α) with compound (γ1-1-1). Examples of the compound (γ1-1-1) include 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, 2,2-bis[4-(2-hydroxypropoxy)phenyl]propane, 2,2-bis[4-(2-hydroxybutoxy)phenyl]propane, reaction products of a heterocyclic compound (γ1-1-1-1) and a diol compound (γ1-1-1-2), and reaction products of a hydroxyalkyl chloride and a diol compound (γ1-1-1-2). These can be used individually or in combination of two or more. Among these, the denaturing agent obtained by reacting a heterocyclic compound (γ1-1-1-1) and a diol compound (γ1-1-1-2) is preferred.

[0062] Examples of the heterocyclic compound (γ1-1-1-1) include alkylene carbonates such as ethylene carbonate and propylene carbonate; and alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide. These can be used individually or in combination of two or more. Furthermore, the diol compound (γ1-1-1-2) can be a polyphenol compound such as bisphenol A, bisphenol F, or bisphenol E, and these can be used individually or in combination of two or more.

[0063] The reaction between the heterocyclic compound (γ1-1-1-1) and the diol compound (γ1-1-1-2) can usually be carried out in a suitable solvent at a temperature of about 60 to about 250°C, preferably about 70 to about 200°C, for about 1 to 25 hours, preferably about 1 to 12 hours. Examples of the solvent include 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 iso-propanol; ether alcohol compounds such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether; or mixtures thereof. By reacting compound (α) with compound (γ1-1-1), a modified epoxy resin can be produced in which at least a portion of the resin ends has an organic group represented by structural formula (1) or structural formula (2).

[0064] [Aqueous resin dispersion] The aqueous resin dispersion of the present invention is obtained by dispersing the modified epoxy resin in an aqueous medium. Methods for dispersion in an aqueous medium include mixing a mixed solution containing the modified epoxy resin and an emulsifier (including a highly polar resin) with the aqueous medium, and mixing a modified epoxy resin solution to which highly polar functional groups have been added with the aqueous medium. All of these methods can be suitably used. In the present invention, "aqueous resin dispersion" refers to a state in which the modified epoxy resin component exists in a particulate state without being dissolved in the aqueous medium. The content of modified epoxy resin in the aqueous resin dispersion is preferably 10 to 90% by mass or more, based on the solid content. It is preferable to mix the modified epoxy resin and the amine-added epoxy resin (described later) with a curing agent (such as a blocked polyisocyanate compound) and disperse the mixture in an aqueous medium. In this case, a blocked polyisocyanate compound is preferred as the curing agent. Furthermore, the mixing ratio (mass ratio) of the epoxy resin (including modified epoxy resin and amine-added epoxy resin) and the curing agent is preferably 1 / 99 to 99 / 1 in terms of the solid content ratio of the epoxy resin to the curing agent, more preferably 30 / 70 to 90 / 10, and even more preferably 40 / 60 to 85 / 15.

[0065] The aqueous medium used to disperse the modified epoxy resin 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.

[0066] The aqueous resin dispersion of the present invention may, in addition to the modified epoxy resin or epoxy resin and the curing agent, optionally contain additives such as neutralizing agents, emulsifiers, catalysts, and other resin components. The dispersion of the modified epoxy resin or epoxy resin in an aqueous medium may be carried out by adding the aqueous medium to a resin solution containing the modified epoxy resin or epoxy resin and other resin components as needed, while stirring; by adding the resin solution to the aqueous medium while stirring; or by mixing the aqueous medium and the resin solution and then 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.

[0067] [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 modified epoxy resin and / or a modified product thereof of the present invention.

[0068] <Cationic electrodeposition coating> The cationic electrodeposition coating of the present invention contains the modified epoxy resin of the present invention, an amine-added epoxy resin, and a curing agent as film-forming resin components. A preferred method for manufacturing cationic electrodeposition paint involves first mixing a modified epoxy resin, an amine-added epoxy resin, and a curing agent into a solution, then adding an aqueous medium to produce an aqueous resin dispersion, and finally mixing the aqueous resin dispersion with a pigment paste and other components, as described later, to produce the cationic electrodeposition paint.

[0069] The content of the modified epoxy resin, amine-added epoxy resin, and curing agent is preferably within the following ranges based on the resin solids content. Modified epoxy resin: 1-70% by mass, preferably 5-60% by mass, more preferably 10-50% by mass. • Amine-added epoxy resin: 1 to 95% by mass, preferably 10 to 85% by mass, more preferably 30 to 75% by mass. • Curing agent: 1-60% by mass, preferably 5-50% by mass, more preferably 10-45% by mass.

[0070] <Amine-added epoxy resin> The amine-added epoxy resin can be obtained by reacting at least the compound (α) with an amine compound. As the compound (α) used as a raw material for the amine-added epoxy resin, a compound having two epoxy groups is preferred. Examples of commercially available products include those sold by Mitsubishi Chemical Corporation under the trade names jER828EL, jER1002, jER1004, and jER1007. Furthermore, the molecular weight can be increased by reacting it with a divalent phenolic compound, such as the compound (γ) mentioned above.

[0071] The amine compound is not particularly limited as long as it is an amine compound that has reactivity with epoxy groups.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 polyamine; polyamide polyamines containing one or more primary or secondary amines in the molecule of the polyamide resin produced by condensation of the 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 polyamine with a ketone compound; etc.

[0072] The weight-average molecular weight of the amine-added 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 the finish of the coating film and corrosion resistance (adhesion) when used to form a paint. The amine value of the amine-added epoxy resin is usually 11 mg KOH / g or more, based on the resin solids content, more preferably in the range of 15 to 200 mg KOH / g, and more preferably in the range of 30 to 150 mg KOH / g, from the viewpoint of water dispersibility and improved corrosion resistance of the coating film when used to form a paint. The amine value in this specification is as defined in JIS K This is the amine value (mgKOH / g) per resin solid content, obtained by measurement according to 7237-1995.

[0073] The cationic electrodeposition coating of the present invention contains, as essential components, a film-forming resin component comprising at least the modified epoxy resin and amine-added epoxy resin of the present invention, and at least the modified epoxy resin and a curable curing agent. If necessary, it may also contain other resins (such as acrylic resin, urethane resin, or polyether resin), curing catalysts, pigments, solvents such as water, and additives (such as surfactants, surface modifiers, curing co-catalysts, and neutralizing agents).

[0074] The cationic electrodeposition coating of the present invention is based on the following formula (3) Formula (3): The average polyfunctionalization concentration (Y2) of the epoxy resin contained in cationic electrodeposition paint = average polyfunctionalization degree of the modified epoxy resin (X1) ÷ weight-average molecular weight of the modified epoxy resin Mw × 1000 × (amount of modified epoxy resin ÷ total amount of epoxy resins) The average polyfunctionalization concentration (Y2) of the epoxy resin contained in the cationic electrodeposition coating shown 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). The average polyfunctionalization concentration (Y2) mentioned above is the average polyfunctionalization concentration (Y2) of all epoxy resins (modified epoxy resins, amine-added epoxy resins, etc.) contained in the cationic electrodeposition coating. The term "epoxy resin" includes resins obtained by reacting epoxy compounds (such as compound (α)) with other compounds, and includes the modified epoxy resin and amine-added epoxy resin.

[0075] (Hardening agent) The curing agent included in the cationic electrodeposition coating of the present invention can be any known compound that reacts with an active hydrogen-containing group without limitation, but it is particularly preferable to use a blocked polyisocyanate compound.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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).

[0080] 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. 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.

[0081] (curing catalyst) The cationic electrodeposition coating of the present invention may contain a film-forming resin component comprising at least the modified epoxy resin and the amine-added epoxy resin of the present invention, and a curing catalyst that promotes the curing reaction between at least the modified epoxy resin and a curable curing agent. The curing catalyst is not particularly limited, but may contain, for example, a bismuth compound. 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 curing 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 organotin compounds.

[0082] 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.

[0083] 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 preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 6 parts by mass, based on 100 parts by mass of resin solids.

[0084] (Pigment) The cationic electrodeposition coating of the present invention may contain a pigment. As the pigment, one or more selected from the group consisting of, for example, 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.

[0085] 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.

[0086] 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.

[0087] (Single-layer cationic electrodeposition coating) 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.

[0088] (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 coated with the cationic electrodeposition coating of the present invention 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.

[0089] 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.

[0090] The 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. [Examples]

[0091] [Manufacturing of epoxy resins] <Manufacturing Example 1> In a reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 1140 parts of jER828EL (trade name, manufactured by Mitsubishi Chemical Corporation, epoxy resin, epoxy equivalent 190, number average molecular weight 380), 456 parts of bisphenol A, 1.1 parts of TBAB (tetrabutylammonium bromide; catalyst), and 200 parts of methyl isobutyl ketone (solvent) were added. The mixture was reacted at 160°C until the epoxy equivalent was approximately 800, and the resulting reaction product was diluted with methyl isobutyl ketone until the solid content was 80%. Next, 178 parts of diethylenetriamine dikethymine (90%) and 137 parts of diethanolamine were added and reacted at 120°C for 4 hours. Furthermore, methyl isobutyl ketone was added to obtain a non-polyfunctional, linear amine-added epoxy resin (A-0) solution with 75% solids and amino groups. The obtained amine-added epoxy resin (A-0) had a number-average molecular weight of approximately 1900, an amine value of 92 mgKOH / g, an average degree of polyfunctionalization (X1) of 0, and an average polyfunctionalization concentration (Y1) of 0.

[0092] <Manufacturing Example 2> 228 parts of bisphenol A and 0.6 parts of potassium hydroxide were charged into an autoclave, and the reaction vessel was purged with nitrogen. 44 parts of ethylene oxide were added, and the temperature was slowly raised to approximately 160°C. After the reaction was complete, the mixture was cooled and neutralized with concentrated sulfuric acid. Then, ethylene glycol monobutyl ether was added to produce a compound (Z) solution with a solid content of 80%, which is compound (γ1-1-1) as described in the specification.

[0093] <Example 1-1> In a reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 1914 parts of bisphenol A type epoxy resin (epoxy compound, molecular weight 375), 610 parts of bisphenol A, 3.8 parts of dimethylbenzylamine (catalyst), and 280.4 parts of methyl isobutyl ketone (solvent) were added and reacted at 150°C until the epoxy equivalent was 555. The resulting reaction product was diluted with methyl isobutyl ketone until the solid content was 80%. Next, 1522 parts of compound (Z) from Production Example 2 (on a solid content basis) were added and reacted at 120°C for 3 hours. Methyl isobutyl ketone was then added to obtain a polyfunctional epoxy resin (A-1) solution with a solid content of 75%. The obtained epoxy resin (A-1) had an amine value of 0 mgKOH / g, an average degree of polyfunctionalization (X1) of 0.15, and an average polyfunctionalization concentration (Y1) of 0.1.

[0094] <Examples 1-2> In a reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 2082 parts of bisphenol A type epoxy resin (epoxy compound, molecular weight 375), 292 parts of bisphenol A, 3.6 parts of dimethylbenzylamine (catalyst), and 263.7 parts of methyl isobutyl ketone (solvent) were added and reacted at 150°C until the epoxy equivalent was 397. The resulting reaction product was diluted with methyl isobutyl ketone until the solid content was 80%. Next, 1923 parts of compound (Z) were added on a solid content basis and reacted at 120°C for 3 hours. Methyl isobutyl ketone was then added to obtain a polyfunctional epoxy resin (A-2) solution with a solid content of 75%. The obtained epoxy resin (A-2) had an amine value of 0 mgKOH / g, an average polyfunctionalization degree (X1) of 1.50, and an average polyfunctionalization concentration (Y1) of 1.6.

[0095] <Examples 1-3> In a reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 1915 parts of bisphenol A type epoxy resin (epoxy compound, molecular weight 375), 275 parts of polyfunctionalizer 1 (Note 1), 228 parts of bisphenol A, 1.0 part of TBAB (tetrabutylammonium bromide; catalyst), and 268.6 parts of methyl isobutyl ketone (solvent) were added and the mixture was reacted at 150°C until the epoxy equivalent was 434. The resulting reaction product was diluted with methyl isobutyl ketone until the solid content was 80%. Next, 1793 parts of compound (Z) were added on a solid content basis and the mixture was reacted at 120°C for 3 hours. Methyl isobutyl ketone was then added to obtain a polyfunctional epoxy resin (A-3) solution with a solid content of 75%. The obtained epoxy resin (A-3) had an amine value of 0 mgKOH / g, an average polyfunctionalization degree (X1) of 0.8, and an average polyfunctionalization concentration (Y1) of 0.41.

[0096] <Examples 1-4> In a reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 1928 parts of bisphenol A type epoxy resin (epoxy compound, molecular weight 375), 533 parts of polyfunctionalizer 1 (Note 1), 1.0 part of TBAB (tetrabutylammonium bromide; catalyst), and 273.4 parts of methyl isobutyl ketone (solvent) were added and reacted at 150°C until the epoxy equivalent was 475. The resulting reaction product was diluted with methyl isobutyl ketone until the solid content was 80%. Next, 1683 parts of compound (Z) were added on a solid content basis and reacted at 120°C for 3 hours. Methyl isobutyl ketone was then added to obtain a polyfunctional epoxy resin (A-4) solution with a solid content of 75%. The resulting epoxy resin (A-4) had an amine value of 0 mgKOH / g, an average polyfunctionalization degree (X1) of 3.02, and an average polyfunctionalization concentration (Y1) of 0.8.

[0097] <Examples 1-5> In a reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 1054 parts of bisphenol A, 378 parts of bisphenol A type epoxy resin (epoxy compound, molecular weight 375), 21 parts of polyfunctionalizer 2 (Note 2), 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, 544 parts of compound (Z) were added (on a solid content basis), and the mixture was reacted at 120°C for 4 hours. Further addition of methyl isobutyl ketone was obtained to obtain a polyfunctional modified epoxy resin (A-5) solution with a solid content of 75%. The resulting epoxy resin (A-5) had an amine value of 0 mgKOH / g, an average degree of polyfunctionalization (X1) of 0.1, and an average polyfunctionalization concentration (Y1) of 0.05.

[0098] <Examples 1-6 to 1-12> Polyfunctional modified epoxy resin solutions (A-6) to (A-12) were prepared in the same manner as in Examples 1-5, except for the formulations shown in Table 1 below.

[0099] [Table 1]

[0100] (Note 1) Polyfunctionalizing agent 1: A mixture in which the compound has p=q=r=0 and R1=R2=R3=H in the following structural formula, and the content ratio of each n value relative to the total amount of compounds where n is 1 or greater is shown in Table 2 below. Average number of functional groups: 8.4, weight-average molecular weight: 878. [ka]

[0101] [Table 2]

[0102] (Note 2) Polyfunctionalizing agent 2: trimellitic acid (molecular weight 210, number of functional groups 3) (Note 3) Polyfunctionalizing agent 3: Dimer acid (mixture; details are shown in Table 3 below) (Note 4) Polyfunctionalizing agent 4: Compound with the following structural formula (mixture; details are shown in Table 3 below) [ka] (n is a non-negative integer)

[0103] [Table 3]

[0104] <Comparative Example 1-1> In a reaction vessel equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 1140 parts of bisphenol A type epoxy resin (epoxy compound, molecular weight 375), 456 parts of bisphenol A, 1.1 parts of TBAB (tetrabutylammonium bromide; catalyst), and 200 parts of methyl isobutyl ketone (solvent) were added. The mixture was reacted at 160°C until the epoxy equivalent was approximately 800, and the resulting reaction product was diluted with methyl isobutyl ketone until the solid content was 80%. Next, 255 parts of dimethylolpropionic acid were added and the mixture was reacted at 120°C for 4 hours. Methyl isobutyl ketone was then added to obtain a non-polyfunctional, linear modified epoxy resin (A-13) solution with a solid content of 75%. The obtained modified epoxy resin (A-13) had a number-average molecular weight of approximately 1900, an amine value of 0 mgKOH / g, an average degree of polyfunctionalization (X1) of 0, and an average polyfunctionalization concentration (Y1) of 0.

[0105] [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 (product name of Daicel Chemical Industries, Ltd., 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, yielding a non-polyfunctional pigment dispersion resin containing a quaternary ammonium base with a solid content of 60%.

[0106] <Manufacturing of pigment dispersion paste> 8.3 parts (5 parts solids) of pigment dispersion resin containing a quaternary ammonium base with a solid content of 60%, 14.5 parts of titanium dioxide, 6.0 parts of purified clay, 0.3 parts of carbon black, 3 parts of bismuth hydroxide, and 20.3 parts of deionized water were added and dispersed in a ball mill for 20 hours to obtain a pigment dispersion paste with a solid content of 55%.

[0107] <Production of Blocked Polyisocyanate Compounds> 270 parts of Cosmonate M-200 (trade name, manufactured by Mitsui Chemicals, 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. While maintaining this temperature, samples were taken over time, and infrared absorption spectroscopy was used to confirm that the absorption of unreacted isocyanate groups had disappeared, yielding a blocked polyisocyanate compound with a resin solids content of 80%.

[0108] <Example 2-1> Sixty parts (solids) of the amine-added epoxy resin obtained in Production Example 1, forty parts (solids) of the modified epoxy resin (A-1) obtained in Example 1-1, and forty-five parts (solids) of the blocked polyisocyanate compound were mixed. Thirteen parts of 10% acetic acid were then added and the mixture was uniformly stirred. Deionized water was then added dropwise over approximately 15 minutes with vigorous stirring to obtain an emulsion with a solids content of 34%. Next, 294 parts of the emulsion (100 parts solids), 52.4 parts of pigment dispersion paste, and deionized water were added to produce a cationic electrodeposition coating (X-1) with a solids content of 20%. The average polyfunctionalization concentration (Y2) of the cationic electrodeposition coating (X-1) is shown in Table 4. 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 4. In this invention, a product is considered unsuccessful if even one of the four evaluation criteria results in a "C" rating. Note that all resin content values ​​in the table represent solid content.

[0109] <Examples 2-2 to 2-12, and Comparative Example 2-1> Cationic electrodeposition coatings (X-2) to (X-13) with a solid content of 20% were manufactured in the same manner as in Example 2-1, except for the formulations shown in Table 4 below. The results of various evaluations are shown in Table 4.

[0110] [Table 4]

[0111] <Rating> (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 19 μm. The coatings were then heated and cured at 170°C for 20 minutes to obtain test plates. Subsequently, the surface roughness value (Ra) of the coated test plates was measured using a SurfTest 301 (product name of Mitutoyo Corporation, 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.

[0112] (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 19 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.

[0113] (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 19 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.

[0114] (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 19 μm. The wet film was washed with water and left for 30 minutes. Then, during the baking process, 0.2 ml of rust-preventive machine oil (manufactured by Nippon Parkerizing Co., Ltd., product name NOX-RUST320) was uniformly sprinkled and applied. After cooling, the surface of the coating 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 3 mm in diameter). C: More than 10 craters appear on the paint film surface (at least one of them is 3 mm or larger in diameter).

Claims

1. A compound (α) having one or more epoxy groups, A compound having a functional group that reacts with an epoxy group, wherein the sum of the functional values ​​of the functional groups is 3 or more, comprising one or more compounds (β) selected from the group consisting of a phenolic compound having a phenolic hydroxyl group of 3 or more, an isocyanate compound having an isocyanate group of 3 or more, a carboxylic acid compound having a carboxyl group of 3 or more, or its anhydride, and a compound having three or more alcoholic hydroxyl groups in its molecule, A compound (γ) having a functional group that reacts with an epoxy group, the sum of the functional values ​​of the functional groups being monovalent or divalent, and not having an amino group, A modified epoxy resin obtained by reacting a compound containing, The following formula (1): Average degree of polyfunctionalization (X1) = Number of terminals per molecule of modified epoxy resin - 2 ... (1) A cationic electrodeposition coating comprising an epoxy resin containing a modified epoxy resin and an amine-added epoxy resin, wherein the average degree of polyfunctionalization (X1) per molecule of the modified epoxy resin shown is 0.10 or higher, and a curing agent.

2. The cationic electrodeposition coating according to claim 1, wherein, based on the total solid content mass of compound (α), compound (β), and compound (γ), compound (α) is contained in a proportion of 1% to 70% by mass, compound (β) in a proportion of 1% to 50% by mass, and compound (γ) in a proportion of 10% to 90% by mass.

3. The modified epoxy resin is given by the following formula (2): Average polyfunctionalization concentration (Y1) = Average degree of polyfunctionalization of modified epoxy resin (X1) ÷ Weight-average molecular weight of modified epoxy resin Mw × 1000 ... (2) The cationic electrodeposition coating according to claim 1 or 2, wherein the average polyfunctionalization concentration (Y1) shown is 0.10 or higher.

4. At least a portion of the end of the modified epoxy resin is structured as shown in structural formula (1) or structural formula (2): 【Chemistry 1】 [In formula (1), R １ and R ２ Each of these independently represents a hydrogen atom, a hydroxymethyl group, a C1-C12 alkyl group, or a C1-C13 alkyloxymethyl group. ３ R represents a hydrogen atom or a methyl group, and there are multiple R ３ They may be the same or different from each other. 【Chemistry 2】 [In formula (2), R ４ and R ５ each independently represents a hydrogen atom, a hydroxymethyl group, an alkyl group having 1 to 12 carbon atoms, or an alkyloxymethyl group having 1 to 13 carbon atoms. R ６ represents a hydrogen atom or a methyl group, and a plurality of R ６ may be the same as or different from each other. R ７ , R ８ , R ９ and R １０ each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.] A cationic electrodeposition coating according to claim 1 or 2, having an organic group represented by [the specified group].

5. A compound (α) having one or more epoxy groups, A compound having a functional group that reacts with an epoxy group, wherein the sum of the functional values ​​of the functional groups is 3 or more, comprising one or more compounds (β) selected from the group consisting of a phenolic compound having a phenolic hydroxyl group of 3 or more, an isocyanate compound having an isocyanate group of 3 or more, a carboxylic acid compound having a carboxyl group of 3 or more, or its anhydride, and a compound having three or more alcoholic hydroxyl groups in its molecule, A compound (γ) having a functional group that reacts with an epoxy group, the sum of the functional values ​​of the functional groups being monovalent or divalent, and not having an amino group, A modified epoxy resin obtained by reacting a compound containing, The following formula (1): Average degree of polyfunctionalization (X1) = Number of terminals per molecule of modified epoxy resin - 2 ... (1) A cationic electrodeposition coating comprising an aqueous resin dispersion in which a modified epoxy resin is dispersed in an aqueous medium, the modified epoxy resin having an average polyfunctionalization degree (X1) per molecule of 0.10 or more.

6. The following formula (3): The average polyfunctionalization concentration (Y2) of the epoxy resin contained in cationic electrodeposition paint = average polyfunctionalization degree of the modified epoxy resin (X1) ÷ weight-average molecular weight of the modified epoxy resin Mw × 1000 × (amount of modified epoxy resin ÷ total amount of epoxy resin) ... (3) The cationic electrodeposition paint according to claim 1 or 2, wherein the average polyfunctionalization concentration (Y2) of the epoxy resin contained in the cationic electrodeposition paint indicated by is 0.10 or higher.

7. A method for forming a coating film by immersing an object to be coated in an electrodeposition coating bath containing the cationic electrodeposition coating described in claim 1 or 2, and performing electrodeposition coating.

8. A compound (α) having one or more epoxy groups, A compound having a functional group that reacts with an epoxy group, wherein the sum of the functional values ​​of the functional groups is 3 or more, and the sum of the functional values ​​of the functional groups is 3 or more, comprising one or more compounds (β) selected from the group consisting of a phenolic compound having a phenolic hydroxyl group of 3 or more, an isocyanate compound having an isocyanate group of 3 or more, a carboxylic acid compound having a carboxyl group of 3 or more, or its anhydride, and a compound having three or more alcoholic hydroxyl groups in its molecule, At least react the following to produce epoxy resin (X): Next, a method for producing a modified epoxy resin, comprising reacting at least one compound (γ) having a functional group that reacts with an epoxy group, the sum of the functional values ​​of the functional groups being monovalent or divalent, and not having an amino group, The following formula (1): Average degree of polyfunctionalization (X1) = Number of terminals per molecule of modified epoxy resin - 2 ... (1) A method for producing cationic electrodeposition coating, comprising mixing an epoxy resin containing a modified epoxy resin and an amine-added epoxy resin obtained by a method for producing a modified epoxy resin in which the average degree of polyfunctionalization (X1) per molecule of the modified epoxy resin shown is 0.10 or more, with a curing agent.

9. A compound (α) having one or more epoxy groups, A compound having a functional group that reacts with an epoxy group, wherein the sum of the functional values ​​of the functional groups is 3 or more, and the sum of the functional values ​​of the functional groups is 3 or more, comprising one or more compounds (β) selected from the group consisting of a phenolic compound having a phenolic hydroxyl group of 3 or more, an isocyanate compound having an isocyanate group of 3 or more, a carboxylic acid compound having a carboxyl group of 3 or more, or its anhydride, and a compound having three or more alcoholic hydroxyl groups in its molecule, At least react the following to produce epoxy resin (X): Next, a method for producing a modified epoxy resin, comprising reacting at least one compound (γ) having a functional group that reacts with an epoxy group, the sum of the functional values ​​of the functional groups being monovalent or divalent, and not having an amino group, The following formula (1): Average degree of polyfunctionalization (X1) = Number of terminals per molecule of modified epoxy resin - 2 ... (1) The average degree of polyfunctionalization (X1) per molecule of the modified epoxy resin shown is 0.10 or higher. The following formula (2): Average polyfunctionalization concentration (Y1) = Average degree of polyfunctionalization of modified epoxy resin (X1) ÷ Weight-average molecular weight of modified epoxy resin Mw × 1000 ... (2) The average polyfunctionalization concentration (Y1) of the modified epoxy resin shown is 0.10 or higher. A method for producing cationic electrodeposition coating, comprising mixing an epoxy resin containing a modified epoxy resin and an amine-added epoxy resin obtained by a method for producing a modified epoxy resin with a curing agent.

10. A method for forming a coating film, comprising immersing an object to be coated in an electrodeposition coating bath containing a cationic electrodeposition coating obtained by the manufacturing method described in claim 8 or 9, and performing electrodeposition coating.

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