Cationic electrodeposition coating composition and electronic component having coating film

Abstract

To provide a cationic electrodeposition coating composition that achieves excellent insulation and edge covering performance suitable for electronic components, and an electronic component having a coating film coated with the cationic electrodeposition coating composition.SOLUTION: The foregoing problem is solved by a cationic electrodeposition coating composition comprising a cationic epoxy resin (A), an organic acid zinc compound (B), and a phenolic compound (C).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a cationic electrodeposition coating composition and an electronic part having a coating film. [Background technology]

[0002] In electronic components, insulating properties have been imparted by coating to prevent electrical conduction, but in recent years, other functions have also been required for coatings such as paints. For example, electronic components used in automobiles are required to maintain their insulating properties and other performance characteristics for long periods of time even in high-temperature environments (high-temperature durability). Patent Document 1 discloses an electronic component that meets the requirement for high-temperature durability by including a specific amino-modified epoxy resin in the coating. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-154458 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for even higher performance electronic components, which requires highly reliable insulation. To achieve highly reliable insulation, it is important to apply a coating without defects to not only the flat surfaces of electronic components but also their edge portions (end faces and pin corners) to provide insulation, which requires a coating material with excellent edge covering properties. Therefore, an object of the present invention is to provide a cationic electrodeposition coating composition that is applicable to electronic components and has excellent insulation and edge covering properties, and an electronic component having a coating film coated with the cationic electrodeposition coating composition. [Means for solving the problem]

[0005] The present invention that achieves the above object may include the following. [1] A cationic electrodeposition coating composition comprising a cationic epoxy resin (A), an organic acid zinc compound (B), and a phenol compound (C). [2] The cationic electrodeposition coating composition according to [1], wherein the organic acid zinc compound (B) is contained in an amount of 10 ppm or more and 1000 ppm or less in terms of divalent zinc ions. [3] The cationic electrodeposition coating composition according to [1] or [2], wherein the phenol compound (C) is contained in an amount of 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the cationic epoxy resin (A). [4] The cationic electrodeposition coating composition according to any one of [1] to [3], wherein the phenol compound (C) comprises a Mannich reaction product of a phenol and / or a phenolic resin, formaldehyde, and an amine. [5] The Mannich reaction products of the phenols and / or phenolic resins, formaldehyde, and amines include those cationized with organic acids, the amines include at least one selected from N-methylethanolamine and diethanolamine; The cationic electrodeposition coating composition according to [4], wherein the organic acid includes a monovalent organic acid. [6] The cationic epoxy resin is an amino group-modified epoxy resin obtained by reacting an epoxy resin (A1) with an amine compound (A2), and the amino group-modified epoxy resin is cationized with an organic acid; The epoxy resin (A1) is A constituent unit derived from propylene oxide-added diepoxy resin (a1) represented by formula (1) Rank and A structural unit derived from a bisphenol compound (a2), A structural unit derived from a diepoxy resin (a3) ​​other than that represented by formula (1), A structural unit derived from a dicarboxylic acid (a4) in which two carboxyl groups are bonded via at least one carbon atom; The cationic electrodeposition coating composition according to any one of [1] to [5], wherein the resin has the formula: [ka] [In formula (1), R 1 represents an alkylene group having 3 to 10 carbon atoms which may have a substituent, a cyclohexylene group which may have a substituent, a phenylene group which may have a substituent, or -Ra-Rb-Rc-, where Ra and Rc are cyclohexylene groups or phenylene groups, Rb is a methylene group which may have one or two substituents, and m and n are each independently an integer of 1 to 20. [7] The cationic electrodeposition coating composition according to any one of [1] to [6], further comprising a blocked polyisocyanate curing agent (D). [8] An electronic part having a coating film coated with the cationic electrodeposition coating composition according to any one of [1] to [7]. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a cationic electrodeposition coating composition that is applicable to electronic components and has excellent edge covering and insulating properties, and electronic components having a coating film coated with the cationic electrodeposition coating composition. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present invention will be described in detail below with reference to specific embodiments. <Cationic electrodeposition coating composition> A cationic electrodeposition coating composition according to one embodiment of the present invention comprises a cationic epoxy resin (A), an organic acid zinc compound (B), and a phenol compound (C).

[0008] <Cationic epoxy resin (A)> The cationic epoxy resin (A) is not particularly limited as long as it is a cationized epoxy resin, but for example, an amino group-modified epoxy resin obtained by reacting an epoxy resin (A1) with an amine compound (A2) and then cationizing it with an organic acid can be used. Bisphenol-type and novolac-type epoxy resins are particularly suitable as the epoxy resin (A1), and among bisphenol-type epoxy resins, the modified epoxy resins shown below are even more suitable.

[0009] <Modified epoxy resin> The modified epoxy resin may, for example, be a compound that comprises a structural unit derived from a propionoxide-added diepoxy resin (a1) represented by formula (1), a structural unit derived from a bisphenol compound (a2), a structural unit derived from a diepoxy resin (a3) ​​different from formula (1), and a structural unit derived from a dicarboxylic acid (a4) in which two carboxyl groups are bonded via at least one carbon atom. It is preferable to have [ka] [In formula (1), R 1 represents an alkylene group having 3 to 10 carbon atoms which may have a substituent, a cyclohexylene group which may have a substituent, a phenylene group which may have a substituent, or -Ra-Rb-Rc-, where Ra and Rc are cyclohexylene groups or phenylene groups, Rb is a methylene group which may have one or two substituents, and m and n are each independently an integer of 1 to 20.

[0010] Here, R in the above formula (1) 1 The "substituents" that can be contained in are independent of each other, and examples thereof include an alkyl group, a phenyl group, a hydroxyl group, and an alkoxyl group. Furthermore, these substituents may be substituted with another functional group (e.g., an alkyl group, a phenyl group, etc.). Furthermore, the alkyl group may be linear, branched, or cyclic.

[0011] The propylene oxide-added diepoxy resin (a1) of the above formula (1) can be obtained by a known method. 1 It can be obtained by addition or addition polymerization of propylene oxide to a polyol compound having hydroxyl groups at both ends, and then reacting the resulting polyether compound (having hydroxyl groups at both ends) with epichlorohydrin to effect diepoxidation.

[0012] Above R 1 Examples of polyol compounds having hydroxyl groups at both ends include linear or cyclic alkylene glycols having hydroxyl groups bonded to carbon atoms at both ends, such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,4-cyclohexanediol; polyhydric phenols having two or more hydroxyl groups, such as catechol, resorcinol, hydroquinone, and pyrogallol; and polyphenol compounds or hydrogenated products thereof, such as 2,2-bis(4-hydroxycyclohexyl)propane (hydrogenated bisphenol A), hydrogenated bisphenol F, hydrogenated bisphenol E, hydrogenated bisphenol B, hydrogenated bisphenol AP, hydrogenated bisphenol BP, bisphenol A, bisphenol F, bisphenol E, bisphenol B, bisphenol AP, and bisphenol BP.

[0013] The propylene oxide-added diepoxy resin (a1) of formula (1) may be used alone or in combination of two or more in the production of a modified epoxy resin. When two or more propylene oxide-added diepoxy resins (a1) of formula (1) are used to produce a modified epoxy resin, they may be added separately or simultaneously.

[0014] Examples of the bisphenol compound (a2) include bisphenol A, bisphenol F, bisphenol E, bisphenol B, bisphenol S, bisphenol AP, and bisphenol BP. Among these, bisphenol A and bisphenol F are preferred. In the production of the modified epoxy resin, the bisphenol compound (a2) may be used alone or in combination of two or more. When two or more bisphenol compounds (a2) are used to modify the epoxy resin, When producing an epoxy resin, they may be added separately or simultaneously.

[0015] The diepoxy resin (a3) ​​is a compound having two epoxy groups in one molecule, different from the propylene oxide-added diepoxy resin (a1). The diepoxy resin (a3) ​​is not particularly limited, but preferably has an epoxy equivalent in the range of 170 to 500, more preferably 170 to 400. The diepoxy resin (a3) ​​is not particularly limited, but is preferably a compound represented by the above formula (2). In formula (2), R 3 and R 4 may be the same or different, and may be, for example, a single bond, an alkylene group, a phenylene group, or a cyclohexylene group. 1 and Y 1 are each independently a hydrogen atom or an alkyl group. 1 and Y 1 The alkyl group as the alkyl group is not particularly limited as long as it is linear or branched, but is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms.

[0016] [ka]

[0017] The diepoxy resin (a3) ​​can be obtained by diepoxidizing two hydroxyl groups in a polyol compound by reacting them with epihalohydrin (for example, epichlorohydrin).Examples of the polyol compound include linear or cyclic alkylene glycols having hydroxyl groups bonded to both terminal carbon atoms, such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,4-cyclohexanediol; polyhydric phenols having two or more hydroxyl groups, such as catechol, resorcinol, hydroquinone, and pyrogallol; and 2,2-bis(4-hydroxycyclohexyl)propanol. Pan (hydrogenated bisphenol A), hydrogenated bisphenol F, hydrogenated bisphenol E, hydrogenated bisphenol B, hydrogenated bisphenol AP, hydrogenated bisphenol BP, bisphenol A, bisphenol F, bisphenol E, bisphenol B, bisphenol AP, bisphenol BP, 4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-isobutane, bis(4-hydroxy-2-tert-butylphenyl)-2,2-propane, bis(4-hydroxy-3-tert-butylphenyl)-2,2-propane Polyphenol compounds or their hydrogenated derivatives, such as tetrakis(4-hydroxyphenyl)-1,1,2,2-ethane, 4,4'-dihydroxydiphenyl sulfone, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, bis(4-hydroxyphenyl)-2,2-dichloroethylene, and 2,2-bis(3-methyl-4-hydroxyphenyl)propane; phenols having two hydroxyl groups bonded to the same carbon atom, such as 1,1-dihydroxyethane, 1,1-dihydroxypropane, and 2,2-dihydroxypropane. alkylene glycols in which one hydroxyl group and one hydroxyalkyl group are bonded to the same carbon atom, such as 2-hydroxypropanol and 2-hydroxybutanol; alkylene glycols in which one or two hydroxyalkyl groups are bonded to the same carbon atom, such as 2,2-(dihydroxymethyl)ethane, 2,2-(dihydroxyethyl)propane, 2,2-dimethyl-1,3-propanediol, 2,2-dimethyl-1,4-butanediol, and 3,3-diethyl-1,6-hexanediol; 4-(1-hydroxyethyl)phenol. alkylene glycols in which one hydroxyl group and one phenol group are bonded to the same carbon atom, such as 4-(1-hydroxyethyl)cyclohexanol, 3-(1-hydroxyethyl)phenol, and 4-(1-hydroxypropyl)phenol; alkylene glycols in which one hydroxyl group and one cyclohexanol group are bonded to the same carbon atom, such as 4-(1-hydroxyethyl)cyclohexanol and 2-(1-hydroxyethyl)cyclohexanol; alkylene glycols in which one hydroxyl group and one phenol group are bonded to the same carbon atom, such as 4-hydroxyphenyl-2-propanol and 4-hydroxyphenyl-2-butanol. alkylene glycols in which one hydroxyalkyl group and one cyclohexanol group are bonded to the same carbon atom, such as 2-(4-hydroxycyclohexyl)-1-propanol and 2,2-dimethyl-2-(4-hydroxycyclohexyl)-1-ethanol; alkylene glycols in which one phenol group and one cyclohexanol group are bonded to the same carbon atom, such as 2-(4-hydroxyphenyl)-2-(4-hydroxycyclohexyl)propane and 1-(4-hydroxyphenyl)-1-(4-hydroxycyclohexyl)propane; and the like.

[0018] In producing the modified epoxy resin, the diepoxy resin (a3) ​​may be used alone or in combination of two or more. When producing the modified epoxy resin using two or more diepoxy resins (a3), they may be added separately or simultaneously.

[0019] The dicarboxylic acid (a4) is a compound in which two carboxyl groups are bonded via at least one carbon atom. A suitable dicarboxylic acid is a compound in which the two carboxyl groups are bonded via a linear alkylene group (R) having 1 to 20 carbon atoms, as shown in the following formula (6): 2 In the compound of formula (6), the alkylene group (R 2The alkylene group (R) in the compound of formula (6) may have one or more substituents selected from an alkyl group, an alkenyl group, an alkadienyl group, and a methylene group, or may have one or more substituents selected from two or more substituents selected from an alkyl group, an alkenyl group, an alkadienyl group, and a methylene group. 2 When the alkylene group (R) has 2 to 20 carbon atoms, it may form a ring via adjacent carbon atoms of the alkylene group. The ring may have one or more substituents selected from alkyl groups and alkenyl groups, and preferably has two substituents of alkyl groups and / or alkenyl groups. When the ring has two substituents, the two substituents may be the same or different. Examples of the ring include a cyclohexane ring, a cyclohexene ring, a benzene ring, and a bicyclo ring in which two carbon-carbon bonds in a decalin ring are double bonds (e.g., bicyclo[4.4.0]decane-1,7-diene, etc.). 2 The alkyl group, alkenyl group, or alkadienyl group that may be present on the ring may be linear or branched.

[0020] [ka]

[0021] More preferred dicarboxylic acids (a4) are compounds having a cyclic and / or unsaturated bond. Particularly preferred dicarboxylic acids (a4) are compounds of formula (6) in which the alkylene group (R 2 ) has 2 to 18 carbon atoms, and 2 ) is a group consisting of one methylene group, one or two alkyl groups having 5 to 9 carbon atoms, or two substituents of one or two kinds selected from alkyl groups, alkenyl groups and alkadienyl groups having 5 to 9 carbon atoms, Alternatively, an alkylene group (R 2) constitutes one of the above rings via adjacent carbon atoms, and the ring may have two substituents, each of which is independently an alkyl group, an alkenyl group, or an alkadienyl group, each having 5 to 9 carbon atoms.

[0022] Examples of the dicarboxylic acid (a4) include malonic acid, succinic acid, glutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylglutaric acid, adipic acid, 2,2-dimethyladipic acid, pimelic acid, suberic acid, azelaic acid, 2-ethylazelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, and 1,13-tridecanedicarboxylic acid. Examples of the dicarboxylic acid (a4) include carboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,15-pentadecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,17-heptadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, 1,19-nonadecanedicarboxylic acid, 1,20-icosanedicarboxylic acid, itaconic acid, phthalic acid, dimer acid, 1,2-cyclohexanedicarboxylic acid, and 1,2-cyclohexenedicarboxylic acid. The dicarboxylic acid (a4) may be used alone or in combination with two or more other dicarboxylic acids (a4) when producing a modified epoxy resin. When two or more dicarboxylic acids (a4) are used to produce a modified epoxy resin, they may be added separately or simultaneously.

[0023] Examples of dimer acids that can be used as raw materials for the modified epoxy resin include commercially available Haridimer 200, 250, or 270S (Harima Chemicals Group, Inc.); Tsunodyme 205, 216, 228, 395, or 346 (Chikuno Foods Industry Co., Ltd.); Unydyme 14, 14R, T-17, 18, T-18, 22, T-22, 27, 35, M-9, M-15, M-35, or 40, or Century D-75, D-77, D-78, or D-1156, or Sylvatal 7001 or 7002 (Arizona Chemical Company); Empol 1016, 1003, 1026, 1028, 1061, 1062, 1008, or 1012 (BASF); hydrogenated dimer acid (average Mn~570; Sigma-Aldrich).

[0024] <Amine compound (A2)> The amine compound (A2) is a raw material for introducing an amino group into the epoxy resin (A1). Therefore, the amine compound (A2) contains at least one active hydrogen capable of reacting with an epoxy group. The amine compound (A2) is not particularly limited as long as it can introduce an amino group, and examples thereof include alkylamines and alkanolamines. Examples of alkylamines include monomethylamine, dimethylamine, monoethylamine, diethylamine, monoisopropylamine, diisopropylamine, monobutylamine, dibutylamine, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, tetraethylenepentamine, pentaethylenehexamine, diethylaminopropylamine, and diethylenetriamine. Examples of alkanolamines include monoethanolamine, diethanolamine, mono(2-hydroxypropyl)amine, di(2-hydroxypropyl)amine, monomethylaminoethanol, and monoethylaminoethanol. Among these, alkanolamines are preferred. Ketimine-modified primary amines can also be used. These amine compounds may be used alone or in combination of two or more. When two or more amine compounds (A2) are used to produce the cationic epoxy resin (A), they may be added separately or simultaneously.

[0025] <Method for producing epoxy resin (A1)> Next, a method for producing the epoxy resin (A1) will be described in detail. The epoxy resin (A1) can be produced by, for example, mixing a mixture of raw materials, such as a propylene oxide-added diepoxy resin (a1), a bisphenol compound (a2), a diepoxy resin (a3) ​​and a dicarboxylic acid (a4), and then subjecting the mixture to a desired reaction. The reaction can be carried out by stirring at a constant temperature. In order to promote the reaction, it is preferable to further add a reaction catalyst to the mixture.

[0026] The reaction catalyst is not particularly limited as long as it promotes the reaction, and examples of the reaction catalyst that can be used include tertiary amines such as dimethylbenzylamine, triethylamine, and tributylamine, and quaternary ammonium salts such as tetraethylammonium bromide and tetrabutylammonium bromide. The reaction temperature is preferably controlled to be between 70°C and 200°C, taking into consideration the progress of the reaction.

[0027] The epoxy equivalent of the epoxy resin (A1) obtained by the above-mentioned production method is, for example, preferably from 1,000 to 5,000, more preferably from 1,250 to 4,000, and particularly preferably from 1,500 to 3,000. Using an epoxy resin (A1) within this range as a raw material for the cationic epoxy resin (A) makes it possible to produce a cationic electrodeposition coating composition that can achieve better liquid stability and efficiently form a desired film thickness. The epoxy equivalent can be measured according to the potentiometric titration method of JIS K7236. The measurement can be performed using a commercially available potentiometric titrator (e.g., AT-610 manufactured by Kyoto Electronics Manufacturing Co., Ltd.).

[0028] In the production of the epoxy resin (A1), the blending proportions of the propylene oxide-added diepoxy resin (a1), bisphenol compound (a2), diepoxy resin (a3), and dicarboxylic acid (a4) relative to the total mass of the raw materials (a1) to (a4) are as follows: The propylene oxide-added diepoxy resin (a1) is preferably 1 to 50 mass%, more preferably 5 to 45 mass%, and most preferably 10 to 40 mass%. The dicarboxylic acid (a4) is preferably 1 to 20 mass%, more preferably 5 to 20 mass%, and most preferably 10 to 20 mass%. The remaining blending proportions are accounted for by the bisphenol compound (a2) and diepoxy resin (a3), and the bisphenol compound (a2) and diepoxy resin (a3) ​​are preferably 1 mass% or more.

[0029] The above reaction may be carried out in a solvent by adding each raw material to the solvent as appropriate. The solvent is not particularly limited as long as it is one that is commonly used in the production of resins, and examples thereof include hydrocarbon solvents such as toluene, xylene, and hexane; ester solvents such as methyl acetate and ethyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; amide solvents such as dimethylformamide and dimethylacetamide; alcohol solvents such as methanol, ethanol, and isopropanol; and ether alcohol solvents such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether. These may be used alone or in combination.

[0030] <Method for producing cationic epoxy resin (A)> Next, the method for producing the cationic epoxy resin (A) will be described in detail. First, the epoxy resin (A1) is reacted with the amine compound (A2). The reaction temperature and time are preferably within the range of 70°C to 110°C for 1 to 5 hours. In producing the resin, the amount of the amine compound (A2) is preferably adjusted so that the amine value of the resin is within the range of 5 mgKOH / g to 30 mgKOH / g. Therefore, the amine value of the resulting resin is preferably within the range of 5 mgKOH / g to 30 mgKOH / g, more preferably within the range of 5 mgKOH / g to 20 mgKOH / g, and particularly preferably within the range of 10 mgKOH / g to 20 mgKOH / g. The amine value, i.e., the total amine value of the resin, is measured according to the potentiometric titration method of JIS K7237. It is possible.

[0031] If unreacted epoxy groups remain even after adjusting the amine value, The compound to be reacted with the unreacted epoxy groups may be any compound, but examples thereof include phenol compounds, carboxylic acids, xylene formaldehyde resins, and ε-caprolactone.

[0032] The reaction of the epoxy resin (A1) with the amine compound (A2) can use the same solvent as that used in producing the epoxy resin (A1), but is not limited thereto, and other solvents may also be used.

[0033] The cationic epoxy resin (A) can be obtained by cationizing the amino groups contained in the structure of an amino-modified epoxy resin obtained by reacting an epoxy resin (A1) with an amine compound (A2) with an organic acid. The organic acid is not particularly limited as long as it can cationize the amino groups in the amino-modified epoxy resin. Examples of the organic acid that can be used include organic carboxylic acids such as formic acid, acetic acid, and lactic acid; and organic sulfonic acids such as sulfamic acid and methanesulfonic acid. Among these, methanesulfonic acid is preferred because it can produce a more stable low-amine value resin emulsion. These acids can be used alone or in combination of two or more. When two or more acids are used, they can be added separately or simultaneously. Cationization can be performed on all or some of the amino groups. The amount of organic acid used for cationization is, for example, 0.1 to 1.0 equivalent, preferably 0.25 to 0.75 equivalent, relative to the number of moles of amino groups.

[0034] The content of the cationic epoxy resin (A) contained in the cationic electrodeposition coating composition is not particularly limited, but is preferably 50 g / L or more and 250 g / L or less, and more preferably 100 g / L or more and 200 g / L or less.

[0035] <Blocked polyisocyanate curing agent (D)> The blocked polyisocyanate curing agent (D) is an addition reaction product of a polyisocyanate compound and a blocking agent, preferably an addition reaction product of a polyisocyanate compound and a blocking agent in approximately stoichiometric amounts. Examples of polyisocyanate compounds include tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, polymeric MDI (crude MDI), bis(isocyanatomethyl)cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, and isophorone diisocyanate. These compounds can be used alone or in combination.

[0036] The blocking agent is added to the isocyanate group of the polyisocyanate compound to block the reaction with other compounds. The blocked polyisocyanate compound produced by blocking the isocyanate group with the blocking agent is stable at room temperature. It is desirable that the blocked polyisocyanate compound be one in which the blocking agent dissociates when the coating film formed by the cationic electrodeposition coating composition of the present invention is baked. The baking temperature is usually about 100 to 200°C.

[0037] Examples of blocking agents that satisfy these requirements include lactam compounds such as ε-caprolactam and γ-butyrolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenolic compounds such as phenol, para-t-butylphenol and cresol; alcohols such as n-butanol and 2-ethylhexanol; ether alcohol compounds such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; etc. These blocking agents may be used alone or in combination of two or more. In order to efficiently carry out the addition and dissociation reactions of the blocking agent and to efficiently obtain the intended addition reaction product, the hydroxyl groups in the modified epoxy resin may be reacted with the isocyanate groups in the polyisocyanate compound in advance, and some or all of the other isocyanate groups in the polyisocyanate compound may be blocked with a blocking agent.

[0038] In order to make the addition and decomposition reactions of the blocking agent more efficient, a curing catalyst may be added as needed. Commercially available curing catalysts can be used as needed. The content of the blocked polyisocyanate curing agent (D) contained in the cationic electrodeposition coating composition is not particularly limited, but is preferably 15 g / L or more and 75 g / L or less, and more preferably 30 g / L or more and 60 g / L or less.

[0039] <Method for producing resin emulsion> The cationic epoxy resin (A) may be dispersed in water to form a resin emulsion, which can be produced by diluting a resin cationized with an organic acid with water while stirring.

[0040] The amount of acid used for cationization is not particularly limited, but if the amount is too small, the amount of cationization that imparts water dispersibility will be reduced and an emulsion may not be formed, so it is preferable to adjust the amount of acid appropriately.

[0041] The resin emulsion may contain other raw materials, such as a blocked polyisocyanate curing agent (D), a liquid medium (preferably water), a pigment paste (containing a pigment and a resin for dispersing the pigment), an organic solvent, a surfactant, an antifoaming agent, an antibacterial agent, and other additives used in cationic electrodeposition paints.

[0042] <Organic Zinc Compound (B)> The cationic electrodeposition coating composition contains at least one organic acid zinc compound, specific examples of which include zinc formate, zinc acetate, zinc lactate, zinc gluconate, zinc tranexamate, zinc dipropionate, and zinc methanesulfonate. Among these, it is preferable to use at least one selected from the group consisting of zinc lactate, zinc acetate, and zinc methanesulfonate, and among these, it is most preferable to use zinc acetate.

[0043] The content of the organic acid zinc compound contained in the cationic electrodeposition coating composition is not particularly limited, but is preferably 10 ppm to 1000 ppm, more preferably 100 ppm to 500 ppm, and even more preferably 150 ppm to 350 ppm, calculated as divalent zinc ions. The divalent zinc ions contained in the composition can be quantified using an ICP emission spectrometer.

[0044] <Phenol Compounds (C)> The cationic electrodeposition coating composition contains a phenolic compound (C). Examples of the phenolic compound (C) include phenols and phenolic resins. Examples of phenols include phenol, alkyl-substituted phenols, polyhydric phenols, α-naphthol, bisphenol, and polyvinylphenol. Examples of alkyl-substituted phenols include cresol, xylenol, butylphenol, and amylphenol. Examples of polyhydric phenols include resorcinol and catechol. Examples of bisphenols include bisphenol A and bisphenol F. Examples of phenolic resins include reaction products of the above phenols with formaldehyde. Examples of the above phenols The form of the reaction product of a phenol and formaldehyde is not particularly limited, and examples include novolak and resol. The phenol compound (C) may be a Mannich reaction product of the above-mentioned phenols and / or phenolic resin, formaldehyde, and amines. The above-mentioned Mannich reaction products of phenols and / or phenolic resin, formaldehyde, and amines may be used as they are, or may be cationized with an organic acid. The phenol compound (C) may be used alone or in combination of two or more. Of the above, the phenol compound (C) is preferably a Mannich reaction product of a phenol and / or phenolic resin, formaldehyde, and amines, and more preferably a Mannich reaction product of a phenol and / or phenolic resin, formaldehyde, and amines cationized with an organic acid.

[0045] The formaldehyde may be formaldehyde itself, a compound that generates formaldehyde, or the like. Examples of compounds that generate formaldehyde include aldehyde derivatives, aliphatic aldehydes, aromatic aldehydes, and heterocyclic aldehydes. Examples of aldehyde derivatives include paraformaldehyde and hexamethylenetetramine. Examples of aliphatic aldehydes include acetaldehyde and propionaldehyde. Examples of aromatic aldehydes include benzaldehyde, and examples of heterocyclic aldehydes include furfural. These may be used alone or in combination of two or more. Among these, formaldehyde is preferred.

[0046] Examples of the amines that can be used include primary amines and secondary amines. Examples of primary amines include primary alkylamines, primary hydroxyalkylamines, and primary aromatic amines. Examples of primary alkylamines include methylamine, ethylamine, propylamine, isopropylamine, and butylamine. Examples of primary hydroxyalkylamines include ethanolamine, propanolamine, and isopropanolamine. Examples of primary aromatic amines include aniline. Examples of secondary amines include secondary alkylamines and secondary hydroxyalkylamines. Examples of secondary alkylamines include dimethylamine, diethylamine, ethylpropylamine, dipropylamine, diisopropylamine, and dibutylamine. Examples of secondary hydroxyalkylamines include N-methylethanolamine, N-ethylethanolamine, diethanolamine, dipropanolamine, and diisopropanolamine. These may be used alone or in combination of two or more. Among these, secondary hydroxyalkylamines are preferred, with N-methylethanolamine and diethanolamine being more preferred.

[0047] The Mannich reaction can be carried out using conventional methods. For example, phenols and / or phenolic resins, formaldehyde, and amines can be mixed, and optionally, alcohols, glycol ethers, ketones, or the like can be used as a solvent. The reaction can be carried out at 20°C to 100°C for several minutes to several hours. The amounts of the phenols and / or phenolic resins, formaldehyde, and amines used in the Mannich reaction are not particularly limited; equimolar amounts of formaldehyde and amines are consumed in the Mannich reaction. The progress of the Mannich reaction can be confirmed by quantifying the remaining formaldehyde. There are no particular limitations on the method for confirming formaldehyde, but the acetylacetone absorptiometry method described in the Japanese Agricultural Standard JAS6000 established by the Ministry of Agriculture, Forestry and Fisheries can be used, for example.

[0048] The organic acid used for cationizing the Mannich reaction product of the phenols and / or phenolic resins, formaldehyde, and amines may be, for example, a monovalent organic acid or a polyvalent organic acid. Examples of the monovalent organic acid include formic acid, acetic acid, propionic acid, lactic acid, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and benzenesulfonic acid. Examples of suitable organic acids include carboxylic acid, toluenesulfonic acid, and nitrobenzenesulfonic acid. Examples of suitable polyvalent organic acids include citric acid, lactic acid, malic acid, fumaric acid, and maleic acid. Among these, monovalent organic acids are preferred, and acetic acid and methanesulfonic acid are particularly preferred. The content of the phenol compound (C) contained in the cationic electrodeposition coating composition of the present invention is not particularly limited, but is preferably 10 g / L or more and 200 g / L or less, and more preferably 50 g / L or more and 100 g / L or less. The phenol compound (C) is preferably contained in an amount of 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the cationic epoxy resin (A).

[0049] <Method of manufacturing cationic electrodeposition coating composition> The cationic electrodeposition coating composition can be produced, for example, by stirring and mixing the above-mentioned resin emulsion, organic acid zinc compound (B), and water-soluble phenol compound (C), and, if necessary, the above-mentioned liquid medium, pigment paste, organic solvent, surfactant, antifoaming agent, etc. The concentration of the cationic electrodeposition coating composition can be adjusted by appropriately diluting it with deionized water.

[0050] The pH of the cationic electrodeposition coating composition is not particularly limited, but is preferably in the range of 2.0 to 8.0, and more preferably in the range of 3.0 to 6.0. By ensuring that the pH of the composition is within this range, even if a chemical conversion treatment is performed with a chemical conversion treatment solution before cationic electrodeposition coating using the cationic electrodeposition coating composition, adverse effects due to contamination of the chemical conversion treatment solution and metals etched by the chemical conversion treatment can be prevented. There are no particular restrictions on the pH adjusters that can be used to adjust the pH, and known acids and bases can be used. For example, acids such as formic acid, acetic acid, lactic acid, nitric acid, sulfamic acid, methanesulfonic acid, and benzenesulfonic acid, and bases such as aqueous ammonia, monoethanolamine, diethanolamine, and triethanolamine can be used as appropriate. Note that the pH in this specification refers to a value measured at 25°C using a commercially available pH meter.

[0051] The electrical conductivity of the cationic electrodeposition coating composition is not particularly limited, but is preferably 1000 μS / cm or more and less than 2000 μS / cm. If it is less than 1000 μS / cm, deposition of the coating film during electrodeposition coating may be delayed, resulting in insufficient film thickness. If it is 2000 μS / cm or more, the appearance of the coating may deteriorate and sufficient insulation may not be achieved. The electrical conductivity can be measured using a commercially available electrical conductivity meter (for example, the Toa DKK Multi Water Quality Meter MM-60R).

[0052] <Cation electrodeposition coating method> Cationic electrodeposition coating using a cationic electrodeposition coating composition can be carried out by applying a current of 10 to 400 V, preferably 50 to 250 V, to the substrate as the cathode. The temperature of the paint bath containing the cationic electrodeposition coating composition during cationic electrodeposition coating is usually in the range of 10 to 50°C, preferably 15 to 40°C, but is not limited to these temperatures. After cationic electrodeposition coating, a drying step is carried out to harden the formed coating film. The drying of the coating film is preferably carried out within a temperature range of about 100 to about 300°C, and more preferably about 150 to about 250°C, based on the surface temperature of the coated object. By drying and curing the coating film in this way, an article having a coating film coated with the cationic electrodeposition coating composition is obtained. Note that a water-washing step may be performed between the cationic electrodeposition coating step and the drying step, if necessary. The water-washing step may be performed using, for example, ultrafiltrate, reverse osmosis permeated water, industrial water, pure water, etc.

[0053] The thickness of the coating film formed by the above cathodic electrodeposition coating method is not particularly limited, but is preferably 5 μm. Preferably, the thickness is between 10 μm and 50 μm, and more preferably between 10 μm and 40 μm. By keeping the thickness within this range, excellent corrosion resistance can be obtained. The coating thickness can be measured with an electromagnetic induction type coating thickness meter if the base metal is a magnetic metal, or with an eddy current type coating thickness meter if the base metal is a non-magnetic metal.

[0054] <Electronic components> There are no particular limitations on the articles to which the cationic electrodeposition coating composition can be applied, but electronic components are preferred. The electronic components are not particularly limited as long as they can be electrodeposited, and examples include electronic components that constitute motors (cores, stators, rotors), lead wires, rectangular wires, copper wires, etc. The present invention can be applied to a wide range of applications, including reactor coils, resolvers, bus bars, bobbins, inductors, capacitors, transformers, sintered magnets, component housings, adhesives, optical materials (e.g., imaging lenses), resists, liquid resists, printing plates, insulating varnishes, insulating sheets, laminates, printed circuit boards, sealants (e.g., for semiconductor devices, LED packages, liquid crystal injection ports, organic electroluminescent devices, optical elements, electrical insulation, electronic components, and separators), passivation films (e.g., for semiconductors and solar cells), interlayer insulating films, and protective films. The metal materials constituting electronic components are not particularly limited, and include cold-rolled steel, zinc-plated steel (e.g., galvannealed steel, hot-dip galvanized steel, and electrogalvanized steel), aluminum steel, aluminum, copper (oxygen-free copper, brass), and magnesium. These metal materials may be subjected to a surface cleaning treatment such as alkaline degreasing, or may be subjected to a surface treatment such as zinc phosphate conversion treatment or zirconium conversion treatment after the surface cleaning treatment, as required. These electronic parts can be used in, for example, automobile parts and household appliances.

[0055] <Other uses> Furthermore, applications of the present invention to materials other than electronic components include eyeglasses, lining agents, inks, molding materials, putty, glass fiber impregnating agents, sealing agents, lens portions of lens sheets such as prism lens sheets (for example, those used in the backlights of liquid crystal display devices), Fresnel lens sheets (for example, those used in the screens of projection televisions and the like), and lenticular lens sheets, or backlights using such sheets, optical lenses (for example, microlenses), optical elements, optical connectors, optical waveguides, and casting agents for optical shaping.

[0056] <Example> The present invention will be explained in more detail below with reference to Production Examples, Examples, and Comparative Examples, but the present invention is not limited thereto. The metal plates and degreasing agents used in the examples were arbitrarily selected from commercially available materials, and do not limit the actual use of the cationic electrodeposition coating composition of the present invention. Unless otherwise specified, % and parts mean % by mass and parts by mass, respectively. The raw materials used in the formulation are listed in Tables 1 to 4 below.

[0057] <Production of Amino Group-Modified Epoxy Resin> <Production Example 1> A 2-liter separable flask equipped with a thermometer, reflux condenser, and stirrer was charged with 77.25 g of diepoxy resin (Epolite 3002NN), 96.79 g of bisphenol A, 549.5 g of bisphenol A diglycidyl ether (jER828EL), 63.24 g of dicarboxylic acid (Haridimer 270S), and 1.0 g of triethylamine, and the mixture was reacted at 160 ° C until the epoxy equivalent reached 1500. 194.86 g of butyl cellosolve was added to terminate the reaction. The temperature was then adjusted to 100 ° C, and 14.63 g of diethanolamine was added. The mixture was reacted for 5 hours to obtain an amino-modified epoxy resin.

[0058] <Production Example 2> 114.7g of bisphenol A, 286.94g of bisphenol A diglycidyl ether (jER828EL), and 1.0g of triethylamine were added to a 2L separable flask equipped with a thermometer, reflux condenser, and stirrer, and the mixture was allowed to react at 160°C until the epoxy equivalent reached 1500, and 194.86g of butyl cellosolve was added to terminate the reaction.The temperature was then adjusted to 100°C, and 52.93g of diethanolamine was added, followed by a reaction for 5 hours to obtain an amino group-modified epoxy resin.

[0059] <Production of Blocked Polyisocyanate Curing Agent (D)> <Production Example 3> In a reaction vessel, 115.6 g of methyl isobutyl ketone was added to 678.4 g of Cosmonate M-200 (trade name, crude MDI manufactured by Mitsui Chemicals, Inc.), and the temperature was raised to 70°C. 706.0 g of butyl cellosolve was then slowly added dropwise, and the temperature was raised to 90°C after the addition was completed. The mixture was allowed to react at 90°C for 12 hours to obtain a blocked polyisocyanate curing agent. Infrared absorption spectroscopy showed no absorption due to unreacted isocyanate groups, confirming that the isocyanate had been completely blocked.

[0060] <Production of cationic epoxy resin (A) emulsion> <Production Example 4> 649.54 g of the amino group-modified epoxy resin obtained in Production Example 1 and 216.51 g of the blocked polyisocyanate obtained in Production Example 3 were mixed, and then 6.69 g of methanesulfonic acid was added and stirred uniformly. Then, 1116.79 g of deionized water was added over a period of about 10 minutes with vigorous stirring to obtain a cationic epoxy resin (A) emulsion with a solids content of 33%.

[0061] <Production Example 5> 649.54 g of the amino group-modified epoxy resin obtained in Production Example 2 and 216.51 g of the blocked polyisocyanate obtained in Production Example 3 were mixed, and then 24.19 g of methanesulfonic acid was added and stirred uniformly. Then, 1099.30 g of deionized water was added over a period of about 10 minutes with vigorous stirring to obtain a cationic epoxy resin (A) emulsion with a solids content of 33%.

[0062] <Production of Water-Soluble Phenol Compound (C)> <Production Example 6> 228.3 g of bisphenol A and 500.0 g of ethanol were placed in a 2-liter separable flask equipped with a thermometer, reflux condenser, and stirrer, and the temperature was raised to 60°C. 162.3 g of formalin and 150.2 g of methylethanolamine were then added dropwise, and the mixture was allowed to react for 5 hours. 120.1 g of acetic acid was then added while maintaining the temperature at 60°C, and the mixture was allowed to react for 1 hour. 1572.8 g of water was then added, producing a water-soluble phenolic compound with a solids content of 20%.

[0063] <Production Examples 7 to 13> Water-soluble phenol compounds with a solid content of 20% (Production Examples 7 to 13) were produced using the raw materials shown in Table 1 in the same manner as in Production Example 6.

[0064] [Table 1]

[0065] <Preparation of cationic electrodeposition coating composition> Example 1 910.61 g of the resin emulsion produced in Production Example 4, 3.72 g of zinc lactate, 78.88 g of the water-soluble phenol compound produced in Production Example 6, and 1006.79 g of deionized water were added and stirred to produce a cationic electrodeposition coating composition with a solids content of 16%.

[0066] <Examples 2 to 23 and Comparative Examples 1 to 4> In the same manner as in Example 1, a cationic coating composition with a solid content of 16% was produced using the raw materials shown in Table 2.

[0067] [Table 2]

[0068] <Preparation of test plate> Test plates were prepared by first degreasing a metal plate (cold-rolled steel plate: CRS (150 mm (length) × 70 mm (width) × 0.8 mm (thickness) in the table), aluminum alloy plate: Al (A5051) in the table, oxygen-free copper plate: Cu (C1020) in the table, or galvanized steel plate: GA in the table) using Fine Cleaner E6400, a trade name of Nippon Parkerizing Co., Ltd., dipping at 60°C for 3 minutes) and then rinsing with water to clean it. The cleaned metal plate was then electrodeposited using the cationic electrodeposition coating compositions of Examples 1 to 23 and Comparative Examples 1 to 4 to a dry film thickness of 20 μm, yielding a test plate for each Example and Comparative Example.

[0069] <Various evaluations> The test plates (electrodeposition coated plates) obtained by the above method were subjected to various evaluations as follows. The results are shown in Table 3.

[0070] <Breakdown voltage> The breakdown voltage (breakdown voltage per unit film thickness) of each test panel was measured using a voltage resistance tester (TOS9201, manufactured by Kikusui Electronics Co., Ltd.). The measurement was performed under the conditions of an initial voltage of 0 V, a voltage increase rate of 50 V / sec, and a cutoff current of 1.0 mA. Evaluation was based on the following criteria, with a score of fair or better being considered a pass. ◎:120V / μm or more ○: 100V / μm or more and less than 120V / μm △: 80V / μm or more and less than 100V / μm ×: Less than 80V / μm

[0071] <Edge covering> The coating thickness of each test panel was measured using an electromagnetic induction type coating thickness meter if the base metal was a magnetic metal, or an eddy current type coating thickness meter if the base metal was a non-magnetic metal, and the coating thickness at the center of the surface of the test panel was determined. Next, the edge of each test panel was cut out and embedded in a cup containing epoxy resin, the resin was cured, and the cross-section of the coating was polished. The cross-section of the coating was then observed using a Keyence VHX-6000 digital microscope at a magnification of 300x. The film thickness at the edge was calculated by image analysis using data analysis software compatible with this device, and the value calculated was used as the film thickness at the edge. The ratio of the film thickness at the edge to the film thickness at the center in the surface direction of the test plate was calculated and defined as the edge coverage rate, which was evaluated according to the following criteria, with a score of △ or better being considered a pass. ◎: 90% or more ○: 70% or more and less than 90% △: 50% or more and less than 70% ×: Less than 50%

[0072] <Pinhole test> Referring to JIS3261-5:2019, the test plate was immersed in 0.2% saline solution, with the sample as the cathode and the saline solution as the anode, and a 12V DC power supply was applied for 1 minute. If there were no pinholes, nothing would happen, but if there were pinholes, bubbles would be generated by the electrolysis of water and would emerge from them. The number of bubbles was counted and evaluated according to the following criteria, with a score of △ or higher being considered a pass. ◎: No bubbles ○: 1 or 2 bubbles △: 3 to 5 bubbles ×: 6 or more bubbles

[0073] [Table 3]

Claims

1. A cationic electrodeposition coating composition comprising a cationic epoxy resin (A), an organic acid zinc compound (B), and a phenol compound (C).

2. 2. The cationic electrodeposition coating composition according to claim 1, wherein the organic acid zinc compound (B) is contained in an amount of 10 ppm or more and 1000 ppm or less in terms of divalent zinc ions.

3. 2. The cationic electrodeposition coating composition according to claim 1, wherein the phenol compound (C) is contained in an amount of 1 part by mass to 20 parts by mass based on 100 parts by mass of the cationic epoxy resin (A).

4. 2. The cationic electrodeposition coating composition according to claim 1, wherein the phenol compound (C) comprises a Mannich reaction product of a phenol and / or a phenolic resin, formaldehyde, and an amine.

5. The Mannich reaction products of the phenols and / or phenolic resins, formaldehyde, and amines include those cationized with an organic acid, the amines include at least one selected from N-methylethanolamine and diethanolamine; The cationic electrodeposition coating composition according to claim 4, wherein the organic acid comprises a monovalent organic acid.

6. The cationic epoxy resin is an amino group-modified epoxy resin obtained by reacting an epoxy resin (A1) with an amine compound (A2), and the resulting resin is cationized with an organic acid; The epoxy resin (A1) is A structural unit derived from a propylene oxide-added diepoxy resin (a1) represented by formula (1), A structural unit derived from a bisphenol compound (a2), a structural unit derived from a diepoxy resin (a3) ​​other than that represented by formula (1); a structural unit derived from a dicarboxylic acid (a4) in which two carboxyl groups are bonded via at least one carbon atom; 2. The cationic electrodeposition coating composition according to claim 1, wherein the resin has the formula: 【Chemical 1】 [In formula (1), R １ represents an alkylene group having 3 to 10 carbon atoms which may have a substituent, a cyclohexylene group which may have a substituent, a phenylene group which may have a substituent, or -Ra-Rb-Rc-, where Ra and Rc are cyclohexylene groups or phenylene groups, Rb is a methylene group which may have one or two substituents, and m and n are each independently an integer of 1 to 20.

7. 2. The cationic electrodeposition coating composition according to claim 1, further comprising a blocked polyisocyanate curing agent (D).

8. An electronic part having a coating film coated with the cationic electrodeposition coating composition according to any one of claims 1 to 7.

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