Blocked polyisocyanate composition, paint composition, and cationic electrodeposition paint composition

Abstract

The present invention provides a blocked polyisocyanate composition, a paint composition, and a cationic electrodeposition paint composition that exhibit storage stability and excellent low-temperature curing properties. [Solution] A blocked polyisocyanate composition containing a blocked polyisocyanate obtained from a polyisocyanate and a blocking agent, wherein the blocking agent comprises one or more compounds represented by the following formula (1). TIFF2026147329000009.tif6181

Description

Technical Field

[0001] The present invention relates to a blocked polyisocyanate composition excellent in low-temperature curability, a coating composition, and a cationic electrodeposition coating composition.

Background Art

[0002] Conventionally, cationic electrodeposition coatings have been widely used for automobile parts, electrical equipment parts and other industrial equipment that require these properties because of their excellent coating workability and good corrosion resistance of the formed coating films.

[0003] In general, a cationic electrodeposition coating composition is provided in the form of a mixture of two components: a component of a resin emulsion obtained by mixing a resin component composed of a cationic resin (for example, an amino group-containing epoxy resin, etc.) and a curing agent (also referred to as a crosslinking agent, for example, a blocked polyisocyanate compound, etc.) and dispersing the mixture in an aqueous medium, and a component of a pigment dispersion paste containing a pigment dispersed with a pigment dispersion resin. This coating composition is used in a coating bath, current is passed with the article to be coated as a cathode and the counter electrode as an anode to form a deposited coating film on the article to be coated, and then the deposited coating film is heated to form a crosslinked and cured coating film.

[0004] The heating temperature during the above coating film formation is usually higher than 160°C, but in order to reduce energy costs, it has been demanded to perform the heating at a low temperature (80 to 160°C, preferably 80 to 140°C). This is called low-temperature baking.

[0005] In order to perform the above low-temperature baking, it is common to use a low-temperature curable blocked polyisocyanate compound as a curing agent. For example, Patent Document 1 discloses a method for producing a cationic electrodeposition coating composition in which three components, a low-temperature curable blocked polyisocyanate compound, an amino group-containing epoxy resin, and a pigment dispersion paste, are separately dispersed in water and mixed. However, although the storage stability is good, further improvement in low-temperature curability may be required in some cases.

Prior Art Literature

[0006] [Patent Document 1] International Publication No. 2017 / 138445 [Overview of the project] [Problems that the invention aims to solve]

[0007] The problem that the present invention aims to solve is to provide a blocked polyisocyanate composition, a paint composition, and a cationic electrodeposition paint composition that have storage stability and excellent low-temperature curing properties. [Means for solving the problem]

[0008] The inventors, after diligently studying to solve the above problems, discovered that the problems could be solved by a blocked polyisocyanate composition obtained from a blocking agent having a specific chemical structure and a polyisocyanate, and thus completed the present invention. That is, the present invention provides the following blocked polyisocyanate composition, paint composition, and cationic electrodeposition paint composition. [1] A blocked polyisocyanate composition containing a blocked polyisocyanate obtained from a polyisocyanate and a blocking agent, The aforementioned blocking agent is given by formula (1): TIFF2026147329000001.tif6181

[0009] (In equation (1), A 1 is a carbon atom or a nitrogen atom, A 2 is a carbon atom or a nitrogen atom, A 3 is a carbon atom or a nitrogen atom, A 4 is a carbon atom or a nitrogen atom, A 5 is a carbon atom or a nitrogen atom, R1 , when A 1 is a carbon atom, is a hydrogen atom or a monovalent organic group, and when A 1 is a nitrogen atom, does not exist, R 2 , when A 2 is a carbon atom, is a hydrogen atom or a monovalent organic group, and when A 2 is a nitrogen atom, does not exist, R 3 , when A 3 is a carbon atom, is a hydrogen atom or a monovalent organic group, and when A 3 is a nitrogen atom, does not exist, R 4 , when A 4 is a carbon atom, is a hydrogen atom or a monovalent organic group, and when A 4 is a nitrogen atom, does not exist, R 5 , when A 5 is a carbon atom, is a hydrogen atom or a monovalent organic group, and when A 5 is a nitrogen atom, does not exist, R 6 is a hydrogen atom or a monovalent organic group, X is a nitrogen atom or a sulfur atom, Z is a hydrogen atom or does not exist, R 1 to R 6 two or more of which may be linked to form a cyclic structure, when X is a nitrogen atom, R 6 is a hydrogen atom or a monovalent organic group, when X is a nitrogen atom and Z does not exist, X and the ring form a double bond, and R 6 is R 1 to R 5 forms a ring with any one or more of when X is a sulfur atom, Z does not exist, the molecule has one or more N-H groups or S-H groups.) A blocked polyisocyanate composition comprising one or more compounds represented by [2] wherein the blocking agent is any of formulas (1-1) to (1-19): TIFF2026147329000002.tif189150

[0010] (In equations (1-1) to (1-19), R 10 ~R 30 It is a monovalent organic group, n11, n12, n15, n16, n17, n27, n28, n29, n30 are integers from 0 to 5. n13 and n14 are integers between 0 and 6. n18 and n25 are integers between 0 and 10. n20 is an integer between 0 and 4. n21 is an integer between 0 and 3. n22, n23, n24, and n26 are integers from 0 to 8. R 11 ~R 18 , R 20 ~R 30 If there are two or more of them, they may be the same or different from each other. R 10 and R 11 Two or more of the following, and R 19 and R 20 Two or more of these may be connected to form a ring structure. R 12 ~R 18 , R 21 ~R 30 If there are two or more of these elements, they may be connected to form a ring-shaped structure. A block polyisocyanate composition according to [1], comprising one or more compounds represented by [1]. [3] The blocked polyisocyanate composition according to [1] or [2], wherein the polyisocyanate is an aromatic polyisocyanate. [4] A paint composition comprising a blocked polyisocyanate composition described in any one of items [1] to [3] and an active hydrogen group-containing resin. [5] A cationic electrodeposition coating composition comprising a blocked polyisocyanate composition described in any one of items [1] to [3] and an amino group-containing epoxy resin. [Effects of the Invention]

[0011] The blocked polyisocyanate composition of the present invention, when used as a curing agent for paints, can impart excellent low-temperature curing properties to paint compositions while maintaining good storage stability. Furthermore, the blocked polyisocyanate composition of the present invention can provide paint compositions and cationic electrodeposition paint compositions with good finish and excellent corrosion resistance. [Modes for carrying out the invention]

[0012] <Blocked polyisocyanate composition> The present invention relates to a blocked polyisocyanate composition (A) containing a blocked polyisocyanate (a) obtained from a polyisocyanate and a blocking agent.

[0013] The details are described below.

[0014] Blocked polyisocyanate (a) Blocked polyisocyanates (a) are addition reaction products of a polyisocyanate and an isocyanate blocking agent in approximately stoichiometric amounts. Known polyisocyanates can be used in blocked polyisocyanates (a), including, for example, aromatic, aliphatic, or alicyclic polyisocyanates 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], bis(isocyanate methyl)cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate; cyclized polymers or billets of these polyisocyanate compounds; or combinations thereof.

[0015] In particular, aromatic polyisocyanates such as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, and crude MDI (preferably crude MDI) are more preferred for their corrosion resistance. In this invention, "aromatic polyisocyanate" refers to a polyisocyanate having an aromatic compound.

[0016] The blocking agent used in the blocked polyisocyanate (a) of the present invention is a compound represented by the following formula (1). TIFF2026147329000003.tif6181

[0017] In equation (1), A 1 is a carbon atom or a nitrogen atom, A 2 is a carbon atom or a nitrogen atom, A 3 is a carbon atom or a nitrogen atom, A 4 is a carbon atom or a nitrogen atom, A 5 is a carbon atom or a nitrogen atom, R 1 is, A 1 If it is a carbon atom, it is a hydrogen atom or a monovalent organic group, A 1 In the case of a nitrogen atom, it does not exist. R 2 is, A 2 If it is a carbon atom, it is a hydrogen atom or a monovalent organic group, A 2 In the case of a nitrogen atom, it does not exist. R 3 is, A 3 If it is a carbon atom, it is a hydrogen atom or a monovalent organic group, A 3 In the case of a nitrogen atom, it does not exist. R 4 is, A 4 If it is a carbon atom, it is a hydrogen atom or a monovalent organic group, A 4 In the case of a nitrogen atom, it does not exist. R5 is, A 5 If it is a carbon atom, it is a hydrogen atom or a monovalent organic group, A 5 In the case of a nitrogen atom, it does not exist. R 6 is a hydrogen atom or a monovalent organic group, X is a nitrogen atom or a sulfur atom, Z is either a hydrogen atom or does not exist. R 1 ~R 6 Two or more of these may be connected to form a ring structure, A 1 ~A 5 If one or more of them are nitrogen atoms, then X and Z do not exist and R 6 It may be directly bonded to the ring, If X is a nitrogen atom, R 6 is a hydrogen atom or a monovalent organic group, If X is a nitrogen atom and Z is absent, X and the ring form a double bond, and R 6 is R 1 ~R 5 It forms a ring with one or more of the following: If X is a sulfur atom, then Z does not exist. The molecule contains one or more NH groups or SH groups.

[0018] R in equation (1) 1 ~R 6 If the group is an organic group, examples of such organic groups include one or more alkyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, aryl groups, heterocyclic groups, halogen groups, cyano groups, hydroxyl groups, amino groups, and alkoxy groups. Of these, it is preferable that the organic group be one or more alkyl groups, halogen groups, cyano groups, hydroxyl groups, and amino groups. Furthermore, two or more of these groups may be linked to each other to form a ring.

[0019] In this specification, when groups (atomic groups) are not explicitly labeled as substituted or unsubstituted, the term includes both groups (atomic groups) with and without substituents. For example, "alkyl group" includes not only unsubstituted alkyl groups but also substituted alkyl groups.

[0020] The blocking agent used in the blocked polyisocyanate (a) of the present invention is preferably a compound in which Z in formula (1) is a hydrogen atom, and A in formula (1) 1 ~A 5 It is preferable that all of these are carbon atoms. Furthermore, from the viewpoint of low-temperature curability and storage stability, it is preferable that the compound be represented by the following formulas (1-1) to (1-19). TIFF2026147329000004.tif189150

[0021] In equations (1-1) to (1-19), R 10 ~R 30 It is a monovalent organic group, n11, n12, n15, n16, n17, n27, n28, n29, n30 are integers from 0 to 5. n13 and n14 are integers between 0 and 6. n18 and n25 are integers between 0 and 10. n20 is an integer between 0 and 4. n21 is an integer between 0 and 3. n22, n23, n24, and n26 are integers from 0 to 8. R 11 ~R 18 , R 20 ~R 30 If there are two or more of them, they may be the same or different from each other. R 10 and R 11 Two or more of the following, and R 19 and R 20 Two or more of these may be connected to form a ring structure. R 12 ~R 18 , R21 ~R 30 When there are 2 or more groups, two or more of them may be linked to form a cyclic structure. Among these, one or more of the compounds represented by formula (1-1), (1-3), (1-4) and (1-8) are preferred, and one or more of the compounds represented by formula (1-1) and (1-8) are particularly preferred.

[0022] In formulas (1-1) to (1-19), R 10 ~R 30 the monovalent organic group represented by may be the same group as the organic group for R 1 ~R 6 in formula (1) above.

[0023] Examples of said organic group include monovalent organic groups such as alkyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, aryl groups and heterocyclic groups, among which alkyl groups and alkenyl groups are particularly preferred. The monovalent organic group may also contain at least one selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom and a halogen atom, and may be mutually linked with another substituent in formula (1) to form a cyclic structure.

[0024] Examples of the compound represented by formula (1-1) include N-methylaniline, N-ethylaniline, N-propylaniline, N-butylaniline, N-isopropylaniline, N-tert-butylaniline, N-methyl-o-toluidine, N-methyl-m-toluidine, N-methyl-p-toluidine, 2-fluoro-N-methylaniline, 3-fluoro-N-methylaniline, 4-fluoro-N-methylaniline, and the like.

[0025] Examples of the compound represented by formula (1-2) include benzenethiol, o-toluenethiol, m-toluenethiol, p-toluenethiol, 2-aminobenzenethiol, 3-aminobenzenethiol, 4-aminobenzenethiol, 2-fluorobenzenethiol, 3-fluorobenzenethiol, 4-fluorobenzenethiol, and the like.

[0026] Examples of compounds represented by formula (1-3) include indoline, 2-methylindoline, 3-methylindoline, 4-methylindoline, 5-methylindoline, 6-methylindoline, and 7-methylindoline.

[0027] Examples of compounds represented by formulas (1-4) include indole, 2-methylindole, 3-methylindole, 4-methylindole, 5-methylindole, 6-methylindole, 7-methylindole, 2-hydroxyindole, 3-hydroxyindole, 4-hydroxyindole, 5-hydroxyindole, 6-hydroxyindole, 7-hydroxyindole, 2-aminoindole, 3-aminoindole, 4-aminoindole, 5-aminoindole, 6-aminoindole, 7-aminoindole, 2-cyanoindole, 3-cyanoindole, 4-cyanoindole, 5-cyanoindole, 6-cyanoindole, 7-cyanoindole, and the like.

[0028] Examples of compounds represented by formula (1-5) include indole-2-thiol.

[0029] Examples of compounds represented by formulas (1-6) include indazole, 5-methylindazole, 5-hydroxyindazole, 5-aminoindazole, 5-cyanoindazole, and 5-fluoroindazole.

[0030] Examples of compounds represented by formulas (1-7) include indazole, 5-methylindazole, 5-hydroxyindazole, 5-aminoindazole, 5-cyanoindazole, and 5-fluoroindazole.

[0031] Examples of compounds represented by formula (1-8) include 1,2,3,4-tetrahydroquinoline, 2-methyl-1,2,3,4-tetrahydroquinoline, 3-methyl-1,2,3,4-tetrahydroquinoline, 4-methyl-1,2,3,4-tetrahydroquinoline, 5-methyl-1,2,3,4-tetrahydroquinoline, 6-methyl-1,2,3,4-tetrahydroquinoline, 7-methyl-1,2,3,4-tetrahydroquinoline, and 8-methyl-1,2,3,4-tetrahydroquinoline.

[0032] Examples of compounds represented by formula (1-9) include 4-(methylamino)pyridine.

[0033] Examples of compounds represented by formula (1-10) include adenine.

[0034] Examples of compounds represented by formula (1-11) include 5,10-dihydrophenazine.

[0035] Examples of compounds represented by formula (1-12) include phenoxazines.

[0036] Examples of compounds represented by formula (1-13) include phenothiazines.

[0037] Examples of compounds represented by formula (1-14) include 9,10-dihydroacridine.

[0038] Examples of compounds represented by formula (1-15) include 1,2,3,4-tetrahydroquinoxaline.

[0039] Examples of compounds represented by formula (1-16) include 6-azaindol.

[0040] Examples of compounds represented by formula (1-17) include 5-azaindol.

[0041] Examples of compounds represented by formula (1-18) include 7-azaindol.

[0042] Examples of compounds represented by formula (1-19) include 4-azaindol.

[0043] <Paint composition> A second aspect of the present invention is a paint composition containing the above-described blocked polyisocyanate composition (A) and an active hydrogen group-containing resin (B).

[0044] Active hydrogen group-containing resin (B) As the active hydrogen group-containing resin (B) that can be used in the coating composition of the present invention, any known resin can be used without particular limitation, as long as it has a reactive functional group that can be crosslinked with the blocked polyisocyanate composition and can be crosslinked with the blocked polyisocyanate composition (A).

[0045] Reactive functional groups that can be crosslinked with blocked polyisocyanate compositions include reactive functional groups having active hydrogen, such as hydroxyl groups, amino groups, carboxyl groups, and active methylene groups, as well as epoxy groups and carboxylic acid anhydride groups.

[0046] Examples of the active hydrogen group-containing resin (B) include acrylic resin, polyester resin, epoxy resin, alkyd resin, polyether resin, polyurethane resin, and polyamide resin, which can be used individually or in combination of two or more. In particular, it is preferable that at least one is selected from acrylic resin (B1), polyester resin (B2), and epoxy resin (B3).

[0047] The active hydrogen group-containing resin (B) may be dissolved in the paint composition, or it may be dispersed (for example, in an emulsion state in an aqueous solvent). In the case of dispersion, it may be crosslinked resin particles.

[0048] The acrylic resin (B1) that can be used in the paint composition of the present invention can be produced by radical copolymerization of acrylic monomers.

[0049] Examples of the above acrylic monomers include hydroxyl group-containing acrylic monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and addition products of 2-hydroxyethyl (meth)acrylate and caprolactone (e.g., Praxel FA-2 and FM-3, trade names of Daicel Corporation); aromatic vinyl monomers such as styrene, vinyltoluene, and α-methylstyrene; methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n- Examples include butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, polyalkylene glycol (meth)acrylate, isobornyl (meth)acrylate, (meth)acrylic acid, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-di-t-butylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylamide. These can be used individually or in combination of two or more.

[0050] In this specification, (meth)acrylic means acrylic or methacrylic, and (meth)acrylate means acrylate or methacrylate. Acrylic resin (B1) can be obtained by radical copolymerization of the above monomers using a known method.

[0051] The hydroxyl value of the acrylic resin (B1) is usually in the range of 0.1 to 300 mg KOH / g, preferably in the range of 10 to 200 mg KOH / g, and the weight-average molecular weight is usually in the range of 1,000 to 100,000, preferably in the range of 2,000 to 30,000.

[0052] In this specification, the number-average molecular weight and weight-average molecular weight are values ​​obtained by converting the retention time (retention volume) measured using gel permeation 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 "HLC8120GPC" (trade name, manufactured by Tosoh Corporation) was used as the gel permeation chromatograph, and four columns, "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL", and "TSKgel G-2000HXL" (trade names, all manufactured by Tosoh Corporation), were used as the columns, and measurements could be performed under the conditions of tetrahydrofuran as the mobile phase, a measurement temperature of 40°C, a flow rate of 1 mL / min, and a radioisotope detector. For the measurement of the amino group-containing epoxy resin (b3) described later, "tetrahydrofuran (containing 1% by weight of triethanolamine)" was used as the mobile phase.

[0053] The polyester resin (B2) that can be used in the paint composition of the present invention can be produced by an esterification reaction and / or transesterification reaction of an acid component and an alcohol component.

[0054] The acid component can be any compound commonly used as an acid component in the production of polyester resins, without any particular limitations. Examples of the acid component include alicyclic polybasic acids, aliphatic polybasic acids, aromatic polybasic acids, aromatic monocarboxylic acids, aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, and lower alkyl esters of these acids.

[0055] Alicyclic polybasic acids are generally compounds having one or more alicyclic structures (mainly 4-6 membered rings) and two or more carboxyl groups in a single molecule, as well as acid anhydrides and esterified products of the same.

[0056] Aliphatic polybasic acids are generally aliphatic compounds having two or more carboxyl groups in one molecule, acid anhydrides of said compounds, and esterified products of said compounds.

[0057] Aromatic polybasic acids are generally aromatic compounds having two or more carboxyl groups in one molecule, acid anhydrides of said aromatic compounds, and esterified products of said aromatic compounds. Additionally, aromatic monocarboxylic acids, aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, etc., can be used as needed.

[0058] The above alcohol component can be any compound commonly used as an alcohol component in the production of polyester resins, without any particular limitations. However, it is preferable to use one that contains dihydric alcohols such as alicyclic diols, aliphatic diols, and aromatic diols, as well as polyhydric alcohols of trihydric or higher hydric value.

[0059] The above polyester resin (B2) can be produced by reacting the above acid component and alcohol component using a known method. Furthermore, the polyester resin (B2) described above can also be modified with fatty acids, oils and fats, polyisocyanate compounds, epoxy compounds, etc., during the preparation of the resin, or after the esterification reaction and / or transesterification reaction.

[0060] The number-average molecular weight of the polyester resin (B2) is typically 1,000 to 20,000, preferably 1,050 to 10,000, and more preferably within the range of 1,100 to 5,000, from the viewpoint of finish properties.

[0061] Furthermore, the hydroxyl value of the polyester resin (B2) is typically 20 to 300 mg KOH / g, preferably 30 to 250 mg KOH / g, and more preferably within the range of 40 to 180 mg KOH / g, from the viewpoint of the curability of the resulting coating film.

[0062] The epoxy resin (B3) that can be used in the paint composition of the present invention can be obtained by reacting an epoxy resin (B3-1) with a modifier (B3-2).

[0063] Suitable epoxy resins (B3-1) that can be used as raw materials for epoxy resin (B3) are compounds having at least one epoxy group, preferably two or more, in one molecule, with a number average molecular weight of at least 300, preferably 400 to 4,000, more preferably in the range of 800 to 2,500, and an epoxy equivalent of at least 160, preferably 180 to 2,500, more preferably in the range of 400 to 1,500. Such epoxy resins (B3-1) can, for example, be those obtained by the reaction of a polyphenol compound with an epihalohydrin (e.g., epichlorohydrin).

[0064] Examples of polyphenol compounds used to form the epoxy resin (B3-1) mentioned above include bis(4-hydroxyphenyl)-2,2-propane [bisphenol A], bis(4-hydroxyphenyl)methane [bisphenol F], bis(4-hydroxycyclohexyl)methane [hydrogenated bisphenol F], 2,2-bis(4-hydroxycyclohexyl)propane [hydrogenated bisphenol A], 4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-1,1-isobutane, 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.

[0065] Furthermore, among the epoxy resins (B3-1) obtained by the reaction of polyphenol compounds with epihalohydrins, the resin derived from bisphenol A with the following formula is particularly preferred.

[0066] [ka]

[0067] Here, values ​​shown for n = 0 to 8 are preferred.

[0068] Examples of commercially available epoxy resins (B3-1) include those sold by Mitsubishi Chemical Corporation under the product names jER828EL, jER1002, jER1004, and jER1007.

[0069] Examples of modifiers (B3-2) that can be used as raw materials for epoxy resin (B3) include polyhydric alcohols, monohydric alcohols, acidic compounds, phenols, amine compounds, lactones, isocyanate compounds, and xyleneformaldehyde compounds.

[0070] Examples of the above polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,3-propanesiol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, 2,2,4-trimethyl-1,3-pentanediol, triethylene glycol, 2-butyl-2-ethyl-1,3-propanediol, Examples include dihydric alcohols such as tricyclodecanedimethanol, triethylene glycol, neopentyl glycol, 1,4-cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol F, hydrogenated bisphenol A, and hydrogenated bisphenol F; polyetherdiols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; trihydric alcohols such as glycerin, trimethylolpropane, and tris(2-hydroxyethyl) isocyanurate; tetrahydric alcohols such as pentaerythritol; and polyester polyols and acrylic polyols.

[0071] Examples of the monohydric alcohols mentioned above include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, n-octanol, 2-ethylhexanol, dodecyl alcohol, stearyl alcohol, and benzyl alcohol.

[0072] Examples of the above-mentioned acidic compounds include acetic acid, propionic acid, butyric acid, valeric acid, acrylic acid, oleic acid, glycolic acid, lactic acid, benzoic acid, gallic acid, fatty acids, and dibasic acids.

[0073] Examples of the phenols mentioned above include phenol, cresol, ethylphenol, para-tert-butylphenol, nonylphenol, catechol, resorcinol, and 4-tert-butylcatechol.

[0074] The above-mentioned amine compounds are not particularly limited as long as they contain at least one active hydrogen atom that reacts with an epoxy group. Examples include mono- or di-alkylamines such as monomethylamine, dimethylamine, monoethylamine, diethylamine, monoisopropylamine, diisopropylamine, monobutylamine, and dibutylamine; alkanolamines such as monoethanolamine, diethanolamine, mono(2-hydroxypropyl)amine, di(2-hydroxypropyl)amine, monomethylaminoethanol, and monoethylaminoethanol; alkylene polyamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, tetraethylenepentamine, pentaethylenehexamine, diethylaminopropylamine, diethylenetriamine, and triethylenetetramine; alkyleneimines such as ethyleneimine and propyleneimine; and cyclic amines such as piperazine, morpholine, and pyrazine. In addition, these above-mentioned amines can be used in combination with amines obtained by ketiminating primary amines. These can be used individually or in combination of two or more.

[0075] The epoxy resin (B3) can be manufactured by reacting the epoxy resin (B3-1) and the modifier (B3-2) using a known method.

[0076] Furthermore, the number-average molecular weight of the epoxy resin (B3) is usually in the range of 1,000 to 50,000, 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 paint stability, finish quality, and corrosion resistance. The hydroxyl value of the epoxy resin (B3) is usually in the range of 10 to 300 mgKOH / g, preferably in the range of 20 to 250 mgKOH / g, and even more preferably in the range of 30 to 200 mgKOH / g, from the viewpoint of the curability of the resulting coating film.

[0077] In the paint composition of the present invention, the blending ratio of the blocked polyisocyanate composition (A) and the active hydrogen group-containing resin (B) is preferably such that, based on the total mass of the resin solids in the paint composition, component (A) is typically within the range of 10 to 60% by mass, preferably 15 to 55% by mass, and component (B) is typically within the range of 10 to 90% by mass, preferably 20 to 80% by mass. This is preferable in order to obtain a painted article with excellent finish and curing properties. If the blending ratio falls outside the above range, either the paint properties or the coating film performance may be impaired, which is undesirable.

[0078] The paint composition of the present invention is not particularly limited, but for example, in addition to components (A) and (B), it may optionally contain a pigment dispersion paste, a solvent such as water or an organic solvent, a neutralizing agent, a surfactant, a surface modifier, a thickener, an anti-settling agent, an ultraviolet absorber, a light stabilizer, an antifoaming agent, a dissociation catalyst, a plasticizer, and the like.

[0079] The above-mentioned pigment dispersion paste is prepared by pre-dispersing pigments such as coloring pigments, rust-preventive pigments, and extender pigments into fine particles. For example, a pigment dispersion paste can be prepared by blending a pigment dispersion resin, a neutralizing agent, a solvent, and the pigment, and then dispersing them in a dispersion mixer such as a ball mill, sand mill, or pebble mill.

[0080] The above pigments can be any known pigment without particular limitation, such as titanium dioxide, zinc oxide, zinc phosphate, aluminum phosphate, zinc molybdate, calcium molybdate, Prussian blue, ultramarine blue, cobalt blue, copper phthalocyanine blue, indanthron blue, synthetic yellow iron oxide, transparent red iron oxide (yellow), bismuth vanadate, titanium yellow, zinc yellow, monoazo yellow, isoindolinone yellow, metal complex azo yellow, quinophthalone yellow, benzimidazolon yellow, red iron oxide, monoazo red, quinacridone red, azo lake (Mn salt), quinacridone magenta, ancencelon orange, and dianthuric acid. Coloring pigments such as nonyl red, perylene maroon, quinacridone magenta, perylene red, diketopyrrolopyrrole chrome vermilion, chlorinated phthalocyanine green, brominated phthalocyanine green, pyrazolone orange, benzimidazolon orange, dioxazine violet, and perylene violet; extender pigments such as barita powder, barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, white carbon, diatomaceous earth, talc, magnesium carbonate, alumina white, gloss white, and mica powder; and rust-preventive pigments such as aluminum phosphomolybdate, aluminum tripolyphosphate, and zinc oxide (zinc oxide) can be added.

[0081] As the solvent mentioned above, any known solvent such as water or organic solvent can be used without limitation, but it is preferable that it contains water. Examples of organic solvents 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, methyl amyl ketone, and isobutyl methyl 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, diethylene glycol monoethyl ether, and propylene glycol monomethyl ether; or mixtures thereof.

[0082] Furthermore, bismuth compounds, zinc compounds, titanium compounds, amidine compounds, phosphazene compounds, quaternary salt compounds, proazaphosphatran compounds, and the like can be suitably used as dissociation catalysts for the isocyanate blocking agent.

[0083] When applying paint using the paint composition of the present invention, known painting methods such as brush painting, roller painting, dipping painting, barcoder painting, applicator painting, curtain painting, spray painting, rotary atomization painting, and electrodeposition painting can be used without particular limitation.

[0084] The film thickness of the coating is not particularly limited, but generally it can be in the range of 5 to 60 μm, preferably 10 to 40 μm, based on the dry film thickness.

[0085] Furthermore, the coating film is baked and dried by heating it using drying equipment such as an electric hot air dryer or a gas hot air dryer at a surface temperature of 80 to 160°C, preferably 80 to 140°C, for a period of 3 to 180 minutes, preferably 10 to 50 minutes. A cured coating film can be obtained by the above baking and drying process.

[0086] Examples of objects to be coated according to the present invention include automobile bodies, automobile parts, motorcycle parts, household appliances, and other equipment. There are no particular restrictions on the material, and it can be metal, plastic, inorganic material, wood, fiber material, etc. In the case of metal materials, for example, the surface may be cleaned by alkaline degreasing or other methods as needed, and then further surface treated by phosphate chlorination treatment, chromate treatment or other methods as needed. Objects coated with primer paint or the like may also be used. A coated article can be obtained by applying the coating composition of the present invention to the above-mentioned object to be coated.

[0087] <Cationic electrodeposition coating composition> A third aspect of the present invention, a cationic electrodeposition coating composition, contains the above-mentioned blocked polyisocyanate composition (A) and an amino group-containing epoxy resin (b3).

[0088] Amino group-containing epoxy resin (b3) As the amino group-containing epoxy resin (b3) that can be used in the cationic electrodeposition coating composition of the present invention, an epoxy resin using an amine compound as the modifier (B3-2) of the epoxy resin (B3) can be used.

[0089] The above-mentioned amine compounds are not particularly limited as long as they contain at least one active hydrogen atom that reacts with an epoxy group. Examples include mono- or di-alkylamines such as monomethylamine, dimethylamine, monoethylamine, diethylamine, monoisopropylamine, diisopropylamine, monobutylamine, and dibutylamine; alkanolamines such as monoethanolamine, diethanolamine, mono(2-hydroxypropyl)amine, di(2-hydroxypropyl)amine, monomethylaminoethanol, and monoethylaminoethanol; alkylene polyamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, tetraethylenepentamine, pentaethylenehexamine, diethylaminopropylamine, diethylenetriamine, and triethylenetetramine; alkyleneimines such as ethyleneimine and propyleneimine; and cyclic amines such as piperazine, morpholine, and pyrazine. In addition, these above-mentioned amines can be used in combination with amines obtained by ketiminating primary amines. These can be used individually or in combination of two or more.

[0090] The amine value of the above amino group-containing epoxy resin (b3) is preferably in the range of 30 to 80 mg KOH / g resin solids, and more preferably in the range of 40 to 70 mg KOH / g resin solids, from the viewpoint of improving water dispersibility and corrosion resistance.

[0091] Furthermore, the amino group-containing epoxy resin (b3) can be modified with a modifying agent as needed. Such modifying agents are not particularly limited as long as they are resins or compounds that are reactive with epoxy resins. For example, polyols, polyether polyols, polyester polyols, polyamidoamines, polycarboxylic acids, fatty acids, polyisocyanate compounds, compounds obtained by reacting polyisocyanate compounds, lactone compounds such as ε-caprolactone, acrylic monomers, compounds obtained by polymerization of acrylic monomers, xyleneformaldehyde compounds, and epoxy compounds can also be used as modifying agents. These modifying agents can be used individually or in combination of two or more.

[0092] The addition reaction of the above amine compound and modifier to the epoxy resin (B3) can usually be carried out in a suitable solvent at a temperature of about 50 to about 170°C, preferably about 60 to about 150°C, for about 1 to 6 hours, preferably about 1 to 5 hours.

[0093] About cationic electrodeposition coating compositions In the cationic electrodeposition coating composition of the present invention, the blending ratio of the blocked polyisocyanate composition (A) and the amino group-containing epoxy resin (b3) is preferably within the range of 5 to 95% by mass, preferably 20 to 50% by mass, for component (A) and 5 to 95% by mass, preferably 50 to 80% by mass, based on the total solid content mass of components (A) and (b3). This is preferable in order to obtain a coated article with good coating stability, excellent finish, and corrosion resistance. If the blending ratio falls outside this range, it may impair either the above-mentioned coating properties or the coating film performance, which is undesirable.

[0094] The method for producing the cationic electrodeposition coating composition of the present invention is not particularly limited, but for example, in addition to the above-mentioned blocked polyisocyanate composition (A) and amino group-containing epoxy resin (b3), various additives such as surfactants and surface modifiers may be added as needed to form a blended resin, which is then dispersed in water, and then epoxy resin crosslinked particles, pigment dispersion paste, water, organic solvent, neutralizing agent, etc. are thoroughly mixed in to obtain the composition. As the neutralizing agent, any known organic acid can be used without particular limitation, and formic acid, lactic acid, or mixtures thereof are particularly preferred.

[0095] The above-mentioned pigment dispersion paste is prepared by pre-dispersing pigments such as coloring pigments, rust-preventive pigments, and extender pigments into fine particles. For example, a pigment dispersion paste can be prepared by blending a pigment dispersion resin, a neutralizing agent, and a pigment, and then dispersing them in a dispersion mixer such as a ball mill, sand mill, or pebble mill.

[0096] As the above-mentioned pigment dispersion resin, any known resin can be used without particular limitation. For example, epoxy resins and acrylic resins having hydroxyl groups and cationic groups, surfactants, 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, and tertiary sulfonium salt type acrylic resins can be used.

[0097] The above-mentioned pigments can be any known pigments without particular limitations, and may include, for example, coloring pigments such as titanium dioxide, carbon black, and red iron oxide; extender pigments such as clay, mica, barita, calcium carbonate, and silica; and rust-preventive pigments such as aluminum phosphomolybdate, aluminum tripolyphosphate, and zinc oxide (zinc oxide).

[0098] As the solvent mentioned above, any known solvent such as water or organic solvent can be used without limitation, but it is preferable that it contains water. Examples of organic solvents 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, methyl amyl ketone, and isobutyl methyl 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, diethylene glycol monoethyl ether, and propylene glycol monomethyl ether; or mixtures thereof.

[0099] Furthermore, suitable dissociation catalysts for the isocyanate blocking agent include bismuth compounds, zinc compounds, titanium compounds, amidine compounds, phosphazene compounds, quaternary salt compounds, and proazaphosphatran compounds. From an environmental and safety standpoint, it is preferable to use bismuth compounds.

[0100] Paint film formation method Examples of objects to be coated with the cationic electrodeposition coating composition of the present invention include automobile bodies, motorcycle parts, household appliances, and other equipment, and there are no particular limitations as long as they are made of metal.

[0101] 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, and these metal sheets that have been cleaned by alkaline degreasing or other means as needed, followed by surface treatments such as phosphate chlorination or chromate treatment.

[0102] Cationic electrodeposition coating compositions can be applied to the surface of a desired substrate by cationic electrodeposition coating. The cationic electrodeposition method generally involves using a bath containing a cationic electrodeposition coating composition diluted 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. The bath temperature is usually adjusted to 15 to 35°C, and an electric current is applied with the substrate as the cathode under conditions of a load voltage of 100 to 400V, preferably 150 to 350V. After electrodeposition coating, the substrate is usually thoroughly washed with ultrafiltration solution (UF filtrate), reverse osmosis permeate (RO water), industrial water, pure water, etc., to remove any excess cationic electrodeposition coating.

[0103] The thickness of the electrodeposited 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. The coating is then baked and dried by heating the electrodeposited coating using drying equipment such as an electric hot air dryer or a gas hot air dryer at a temperature of 80 to 160°C, preferably 80 to 140°C, on the surface of the coated object for a period of 10 to 180 minutes, preferably 20 to 50 minutes. A cured coating can be obtained by the above baking and drying process. [Examples]

[0104] The present invention will be described in more detail below with reference to manufacturing examples, embodiments, and comparative examples, but the present invention is not limited thereto. In each example, "parts" refers to parts by mass, and "%" refers to mass percent.

[0105] Production of blocked polyisocyanate compositions Example A1 267 parts of Cosmonate M-200 (trade name, manufactured by Mitsui Chemicals, crude MDI, NCO group content 31.3%) and 120 parts of methyl isobutyl ketone were added to a reaction vessel and the temperature was raised to 60°C. 214 parts of N-methylaniline were added dropwise over 2 hours, and the temperature was then raised to 65°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 composition A-1 with a resin solids content of 80%.

[0106] Example A2 267 parts of Cosmonate M-200 (trade name, manufactured by Mitsui Chemicals, crude MDI, NCO group content 31.3%) and 131 parts of methyl isobutyl ketone were added to a reaction vessel and the temperature was raised to 60°C. 269 parts of tetrahydroquinoline were added dropwise over 2 hours, and the temperature was then raised to 65°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 composition A-2 with a resin solids content of 80%.

[0107] Comparative example A3 267 parts of Cosmonate M-200 (trade name, manufactured by Mitsui Chemicals, crude MDI, NCO group content 31.3%) and 117 parts of methyl isobutyl ketone were added to a reaction vessel and the temperature was raised to 60°C. 50 parts of propylene glycol and 150 parts of diethylene glycol monobutyl ether were added dropwise over 2 hours, 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 composition A-3 with a resin solids content of 80%.

[0108] Comparative example A4 267 parts of Cosmonate M-200 (trade name, manufactured by Mitsui Chemicals, crude MDI, NCO group content 31.3%) and 110 parts of methyl isobutyl ketone were added to a reaction vessel and the temperature was raised to 60°C. 174 parts of methyl ethyl ketoxime were added dropwise over 1 hour, and the temperature was then raised to 80°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 composition A-4 with a resin solids content of 80%.

[0109] Manufacturing of amino group-containing epoxy resin (b3) Manufacturing Example 1 In a flask equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser, 1200 parts of jER828EL (trade name, epoxy resin manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 190, number average molecular weight 350) were added to 500 parts of bisphenol A and 0.2 parts of dimethylbenzylamine, and the mixture was reacted at 130°C until the epoxy equivalent reached 850.

[0110] Next, 160 parts of diethanolamine and 65 parts of a ketimine compound of diethylenetriamine and methyl isobutyl ketone were added and reacted at 120°C for 4 hours. Then, 480 g of ethylene glycol monobutyl ether was added to obtain an amino group-containing epoxy resin EPA-1 solution with a solid content of 80%. The amino group-containing epoxy resin EPA-1 had an amine value of 58 mgKOH / g and a number-average molecular weight of 2100.

[0111] Manufacturing of pigment dispersion resins Manufacturing Example 2 In a flask equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, 1010 parts of jER828EL (trade name, epoxy resin manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 190, number average molecular weight 350) were added, along with 390 parts of bisphenol A, 240 parts of Praxel 212 (trade name, polycaprolactone diol, Daicel Chemical Industries, Ltd., weight average molecular weight approximately 1250), 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 pigment dispersion resin containing a quaternary ammonium base with a solid content of 60%.

[0112] Manufacturing of pigment dispersion paste Manufacturing Example 3 In Production Example 2, 8.3 parts (5 parts solids) of pigment dispersion resin containing a quaternary ammonium base with a solid content of 60%, 14.5 parts titanium dioxide, 7 parts purified clay, 0.3 parts carbon black, 2 parts bismuth hydroxide, and 20.3 parts deionized water were added and dispersed in a ball mill for 20 hours to obtain pigment dispersion paste P-1 with a solid content of 55%.

[0113] Manufacturing of cationic electrodeposition coating compositions Example B1 37.5 parts (30 parts solids) of the blocked polyisocyanate composition A-1 obtained in Example A1 and 87.5 parts (70 parts solids) of the amino group-containing epoxy resin EPA-1 solution obtained in Production Example 1 were mixed, and 13 parts of 10% acetic acid were added and the mixture was uniformly stirred. Then, deionized water was added dropwise over approximately 15 minutes while vigorously stirring to obtain an emulsion with a solid content of 34%. Next, 294 parts of the emulsion (100 parts solids), 52.4 parts of the pigment dispersion paste P-1 obtained in Production Example 3, and 350 parts of deionized water were added to produce cationic electrodeposition coating X-1 with a solids content of 20%.

[0114] Examples B2-B4, Comparative Examples B1-B2 Cationic electrodeposition coating compositions (X-2) to (X-6) were prepared in the same manner as in Example B1, except for the formulations shown in Table 1 below. Furthermore, the results of the evaluation tests (low-temperature hardening properties, storage stability) described later are shown in the table.

[0115] [Table 1]

[0116] All amounts in Table 1 above represent solid content values.

[0117] Preparation of test boards Cold-rolled steel sheets (150mm (length) x 70mm (width) x 0.8mm (thickness)) treated with chemical conversion treatment (product name, Palbond #3020, manufactured by Nippon Parkerizing Co., Ltd., zinc phosphate treatment agent) were used as the substrate for electrodeposition coating. Each of the cationic electrodeposition coatings obtained in the examples and comparative examples was electrodeposited to a dry film thickness of 15 μm, and the sheets were baked and dried at 140°C for 20 minutes to obtain test plates.

[0118] <Low-temperature curing properties (gel fraction)> The curing properties (gel fraction) at 140°C were evaluated from the obtained test plates. Grades A and B are considered passing grades, while C is considered a failing grade. A: Gel fraction is 80% or more. B: Gel fraction is 60% or more and less than 80%. C indicates that the gel fraction is less than 60%.

[0119] <Storage Stability (Post-Storage Finish)> The obtained cationic electrodeposition coating was placed in a sealed container and stored at 40°C for 30 days. Next, a cold-rolled steel sheet (150mm (length) x 70mm (width) x 0.8mm (thickness)) that had been treated with a chemical conversion agent (product name, Palbond #3020, manufactured by Nippon Parkerizing Co., Ltd., zinc phosphate treatment agent) was used as the substrate for electrodeposition coating with the stored cationic electrodeposition coating to a dry film thickness of 17 μm, and the sheet was baked and dried at 150°C for 20 minutes to obtain a test plate. Furthermore, the surface roughness value (Ra) of the obtained test plates was measured using SurfTest 301 (product name, manufactured by Mitutoyo Corporation, surface roughness meter) with a cutoff of 0.8 mm, and evaluated according to the following criteria. Evaluations were as follows: A to B were pass, and C was fail. A: Surface roughness value (Ra) is less than 0.25. B: Surface roughness value (Ra) is 0.25 or higher and less than 0.3. C: Indicates a surface roughness value (Ra) of 0.3 or higher.

Claims

1. A blocked polyisocyanate composition containing a blocked polyisocyanate obtained from a polyisocyanate and a blocking agent, The aforementioned blocking agent is defined by formula (1): (In equation (1), A １ is a carbon atom or a nitrogen atom, A ２ is a carbon atom or a nitrogen atom, A ３ is a carbon atom or a nitrogen atom, A ４ is a carbon atom or a nitrogen atom, A ５ is a carbon atom or a nitrogen atom, R １ is, A １ If it is a carbon atom, it is a hydrogen atom or a monovalent organic group, A １ In the case of a nitrogen atom, it does not exist. R ２ , when A ２ is a carbon atom, is a hydrogen atom or a monovalent organic group, and when A ２ is a nitrogen atom, R does not exist, R ３ is, A ３ If it is a carbon atom, it is a hydrogen atom or a monovalent organic group, A ３ In the case of a nitrogen atom, it does not exist. R ４ is, A ４ If it is a carbon atom, it is a hydrogen atom or a monovalent organic group, A ４ In the case of a nitrogen atom, it does not exist. R ５ is, A ５ If it is a carbon atom, it is a hydrogen atom or a monovalent organic group, A ５ In the case of a nitrogen atom, it does not exist. R ６ is a hydrogen atom or a monovalent organic group, X is a nitrogen atom or a sulfur atom, Z is either a hydrogen atom or does not exist. R １ ~R ６ Two or more of these may be connected to form a ring structure. If X is a nitrogen atom, R ６ is a hydrogen atom or a monovalent organic group, If X is a nitrogen atom and Z is absent, X and the ring form a double bond, and R ６ is R １ ~R ５ It forms a ring with one or more of the following: If X is a sulfur atom, then Z does not exist. (It has one or more N-H groups or S-H groups in its molecule.) A block polyisocyanate composition comprising one or more compounds represented by [the formula shown].

2. The aforementioned blocking agent is defined by formulas (1-1) to (1-19): (In equations (1-1) to (1-19), R １０ ~R ３０ It is a monovalent organic group, n11, n12, n15, n16, n17, n27, n28, n29, n30 are integers from 0 to 5. n13 and n14 are integers from 0 to 6. n18 and n25 are integers between 0 and 10. n20 is an integer between 0 and 4. n21 is an integer between 0 and 3. n22, n23, n24, and n26 are integers from 0 to 8. R １１ ~R １８ , R ２０ ~R ３０ If there are two or more of them, they may be the same or different from each other. R １０ and R １１ Two or more of the following, and R １９ and R ２０ Two or more of these may be connected to form a ring structure. R １２ ~R １８ , R ２１ ~R ３０ If there are two or more of these, they may be connected to form a ring-shaped structure. The block polyisocyanate composition according to claim 1, comprising one or more compounds represented by .

3. The blocked polyisocyanate composition according to claim 1 or 2, wherein the polyisocyanate is an aromatic polyisocyanate.

4. A paint composition comprising the blocked polyisocyanate composition according to claim 1 or 2 and an active hydrogen group-containing resin.

5. A cationic electrodeposition coating composition comprising the blocked polyisocyanate composition according to claim 1 or 2 and an amino group-containing epoxy resin.

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