Cationic electrodeposition coating composition, method for producing a cationic electrodeposition coating composition, and electrodeposition coating method

Abstract

To provide a cationic electro-deposition coating composition which can achieve an electro-deposition coating film that is excellent in stability of a coating composition without using a harmful organic solvent, and is excellent in heat resistance and impact resistance.SOLUTION: A cationic electro-deposition coating composition contains a coating film formation resin (A) and a curing agent (B), wherein the coating film formation resin (A) contains a resin (A1) which is a reactant of an aralkyl-modified phenol resin (a1), an epibis-type epoxy resin (a2) and an amine compound (a3), and the curing agent (B) contains a block isocyanate compound (B1) or an α,β-unsaturated carbonyl compound (B2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to a cationic electrodeposition coating composition, a method for producing a cationic electrodeposition coating composition, and an electrodeposition coating method. [Background technology]

[0002] Electrodeposition coating is a coating method in which a coating film is deposited on the surface of a substrate by immersing it in an electrodeposition coating composition and applying a voltage. This method allows for uniform coating even to the finest details of substrates with complex shapes with high coating efficiency, and can be performed automatically and continuously, making it widely used as a primer coating method for various substrates. Furthermore, electrodeposition coating offers excellent protective effects on the substrate, such as providing high corrosion resistance. Moreover, cationic electrodeposition coatings do not cause the metal substrate to leach out like anionic coatings, thus providing an even higher level of protection. In addition, since electrodeposition coating compositions are water-based, they have the advantage of reducing the environmental burden compared to solvent-based coating compositions.

[0003] In recent years, the electronics industry and other fields have seen a growing demand for high-performance materials with superior insulation, heat resistance, chemical resistance, and dimensional stability, driven by miniaturization, thinning, and increased functionality. In particular, even higher levels of insulation and heat resistance are required to guarantee product safety and reliability.

[0004] Materials that can achieve such high insulation and heat resistance requirements include polyamide-imide resins or polyimide resins. For example, Patent Document 1 describes an electrodeposition composition using a polyimide resin. Compared to general-purpose polymer compounds (resin compositions), these resins have a rigid and strong molecular structure, and therefore exhibit excellent electrical insulation, heat resistance, mechanical properties, solvent resistance, and chemical resistance. However, because these resins have a special molecular structure with high polarization, they can only be dispersed in specific organic solvents such as NMP (N-methyl-2-pyrrolidone), making film formation difficult and thus difficult to apply to paints. Furthermore, NMP and the like pose safety and environmental problems.

[0005] In addition, Patent Document 2 describes that in a resin composition for cationic electrodeposition paint, a cationic resin obtained by reacting a glycidyl etherified product of a phenolic novolak resin, an amine compound having a primary hydroxyl group, and a phenolic compound having a phenolic hydroxyl group is used.

[0006] Patent Document 3 describes that in a cationic electrodeposition paint composition, an amino group-containing epoxy resin obtained by reacting at least a compound having an epoxy group, a compound containing a trivalent or higher phenolic compound and / or a trifunctional or higher polyisocyanate compound, and an amine compound is used.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] Since the polyamideimide resin or polyimide resin described in Patent Document 1 has a highly polar special molecular structure, it can be dispersed only in a specific organic solvent such as NMP (N-methyl-2-pyrrolidone), and it has been difficult to form a film. In addition, NMP has problems in terms of safety and environment.

[0009] As described in Patent Document 2, when a phenolic resin is used, the obtained electrodeposition coating film is brittle, and the adhesion to the substrate and the impact resistance are not sufficiently satisfactory.

[0010] Furthermore, when using the amino group-containing epoxy resin described in Patent Document 3, the resulting electrodeposited coating film was not sufficiently satisfactory in terms of impact resistance.

[0011] This disclosure has been made in view of the above circumstances and aims to provide a cationic electrodeposition coating composition that can achieve an electrodeposition coating film with excellent stability, heat resistance and impact resistance without using harmful organic solvents. [Means for solving the problem]

[0012] This disclosure includes the following aspects: [1] It comprises a film-forming resin (A) and a hardening agent (B), The aforementioned coating-forming resin (A) includes a resin (A1) which is a reaction product of an aralkyl-modified phenol resin (a1), an epibis-type epoxy resin (a2), and an amine compound (a3). The curing agent (B) is a cationic electrodeposition coating composition comprising a blocked isocyanate compound (B1) or an α,β-unsaturated carbonyl compound (B2). [2] The amine value of the resin (A1) is 15 mg KOH / g or more and 70 mg KOH / g or less, the cationic electrodeposition coating composition according to [1]. [3] The cationic electrodeposition coating composition according to [1] or [2], wherein the number average molecular weight of the resin (A1) is 800 or more and 3,000 or less. [4] The cationic electrodeposition coating composition according to any one of [1] to [3], wherein the sum of the primary hydroxyl value and phenolic hydroxyl value of the resin (A1) is 100 mg KOH / g or more and 250 mg KOH / g or less. [5] The cationic electrodeposition coating composition according to any one of [1] to [4], wherein the number average molecular weight of the aralkyl-modified phenol resin (a1) is 500 or more and 2,000 or less, and the primary hydroxyl value of the aralkyl-modified phenol resin (a1) is 200 mg KOH / g or more and 400 mg KOH / g or less. [6] The aralkyl-modified phenolic resin (a1) comprises a biphenylaralkyl-modified novolac-type phenolic resin, as described in any one of [1] to [5]. [7] The cationic electrodeposition coating composition according to any one of [1] to [6], wherein the epoxy equivalent of the epibis-type epoxy resin (a2) is 180 g / eq or more and 490 g / eq or less. [8] The cationic electrodeposition coating composition according to any one of [1] to [7], wherein the epibis-type epoxy resin (a2) comprises a bisphenol A type epoxy resin. [9] The α,β-unsaturated carbonyl compound (B2) is a reaction product (B2-1) of an aralkyl-modified phenol resin (b2-1), an epihalohydrin compound (b2-2), and a monomer having an α,β-unsaturated carbonyl group (b2-3); or a bismaleimide resin (B2-2), as described in any one of [1] to [8].

[10] [1] to [9] involves immersing the object to be coated in a cationic electrodeposition coating composition described in any one of the above and applying a voltage to form a deposited coating film, and An electrodeposition coating method comprising drying and curing the deposited coating film to obtain an electrodeposited coating film. [Effects of the Invention]

[0013] This disclosure provides a cationic electrodeposition coating composition that can achieve an electrodeposition coating film with excellent stability, heat resistance, and impact resistance without using harmful organic solvents. [Modes for carrying out the invention]

[0014] The cationic electrodeposition coating composition of this disclosure comprises a film-forming resin (A) and a curing agent (B), The aforementioned coating-forming resin (A) includes a resin (A1) which is a reaction product of an aralkyl-modified phenol resin (a1), an epibis-type epoxy resin (a2), and an amine compound (a3). The curing agent (B) comprises a blocked isocyanate compound (B1) or an α,β-unsaturated carbonyl compound (B2).

[0015] Because the cationic electrodeposition coating composition of this disclosure has the above-described structure, it is possible to achieve an electrodeposited coating film with excellent stability of the coating composition, as well as excellent heat resistance and impact resistance, without using harmful organic solvents. This disclosure should not be interpreted as being limited to any particular theory, but the reason why the cationic electrodeposition coating composition of this disclosure can achieve the above-described effect is thought to be as follows.

[0016] In other words, the cationic electrodeposition coating composition of this disclosure uses an aralkyl-modified phenolic resin among phenolic resins, modifies a portion of the primary hydroxyl groups of the aralkyl-modified phenolic resin with an epibis-type epoxy resin, and further reacts it with an amine compound to obtain a resin (A1), which is used as the film-forming resin (A). In addition, a curing agent (B) is used that can form bonds with high bond energy between it and the film-forming resin (A). As a result, the resulting electrodeposited coating has high heat resistance, while the crosslinking density is moderately reduced. Consequently, it is considered possible to achieve an electrodeposited coating with excellent heat resistance, adhesion to the substrate, and impact resistance without using harmful organic solvents.

[0017] (A) Film-forming resin The coating-forming resin (A) refers to a resin that can form an electrodeposited coating film together with a curing agent (B). The coating-forming resin (A) includes a resin (A1) which is a reaction product of an aralkyl-modified phenolic resin (a1), an epibis-type epoxy resin (a2), and an amine compound (a3).

[0018] (a1) Aralkyl-modified phenolic resin Aralkyl-modified phenolic resin (a1) is a phenolic resin having a structure derived from an aralkyl group. Typically, it has a repeating structural unit in which a structure derived from an aralkyl group is introduced into the repeating structural unit of a novolac-type phenolic resin.

[0019] The aralkyl-modified phenol resin preferably has the following formula (I):

[0020] [Chemical Formula]

[0021] [In formula (I), Ar 1 represents a C 6-20 aromatic ring which may have a substituent; Ar 2 represents a C 6-20 aromatic ring which may have a substituent; n represents an integer from 1 to 20.] It is represented by

[0022] In formula (I), the C 1 aromatic ring represented by Ar 2 or Ar 6-20 may be a monocyclic or polycyclic ring. In the case of a polycyclic ring, it may be fused or non-fused. The C 1 aromatic ring represented by Ar 2 or Ar 6-20 Examples of the aromatic ring preferably include a benzene ring, a naphthalene ring, a biphenyl ring, 2,2-diphenylpropane, 1,1-diphenylmethane, etc. More preferably, a benzene ring, a naphthalene ring, and a biphenyl ring are included. The substituent of the C 1 aromatic ring represented by Ar 2 or Ar 6-20 is preferably a C 1-6 hydrocarbon group. Ar 1 is preferably a C 6-12 aromatic ring, and Ar 2 is preferably a C 6-12 aromatic ring.

[0023] In formula (I), n1 can preferably be 1 to 15, more preferably 1 to 5.

[0024] Examples of the aralkyl-modified phenol resin (a1) include Ar in formula (I) 2A biphenyl aralkyl-modified novolac-type phenolic resin in which the ring is a biphenyl ring is preferred. The content of biphenylaralkyl-modified novolac-type phenolic resin in the aralkyl-modified phenolic resin (a1) is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less.

[0025] Aalkyl-modified phenolic resin (a1) can be produced by reacting a phenolic hydroxyl group-containing compound with an aromatic crosslinking agent.

[0026] Examples of the phenolic hydroxyl group-containing compounds include phenol, hydroquinone, resorcinol, catechol, pyrogallol, phloroglucinol, 1-naphthol, 2-naphthol, 1,5-naphthalenediol, 1,6-naphthalenediol, 1,7-naphthalenediol, 2,6-naphthalenediol, 2,7-naphthalenediol, 2,2'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, and 4,4'-dihydroxybiphenyl. The phenolic hydroxyl group-containing compounds may be used individually or in combination of two or more.

[0027] Aromatic crosslinking agents include crosslinking agents having a benzene skeleton and crosslinking agents having a biphenyl skeleton. The crosslinking agent having a benzene skeleton may be an o-isomer, m-isomer, or p-isomer, and is preferably an m-isomer or p-isomer. Examples of crosslinking agents having a benzene skeleton include p-xylylene glycol, α,α'-dimethoxy-p-xylene, α,α'-diethoxy-p-xylene, α,α'-diisopropyl-p-xylene, α,α'-dibutoxy-p-xylene, m-xylylene glycol, α,α'-dimethoxy-m-xylene, α,α'-diethoxy-m-xylene, α,α'-diisopropoxy-m-xylene, and α,α'-dibutoxy-m-xylene. Examples of crosslinking agents having a biphenyl skeleton include 4,4'-dihydroxymethylbiphenyl, 2,4'-dihydroxymethylbiphenyl, 2,2'-dihydroxymethylbiphenyl, 4,4'-dimethoxymethylbiphenyl, 2,4'-dimethoxymethylbiphenyl, 2,2'-dimethoxymethylbiphenyl, 4,4'-diisopropoxymethylbiphenyl, 2,4'-diisopropoxymethylbiphenyl, 2,2'-diisopropoxymethylbiphenyl, 4,4'-dibutoxymethylbiphenyl, 2,4'-dibutoxymethylbiphenyl, and 2,2'-dibutoxymethylbiphenyl. The substitution position of the functional group such as the methylol group on the biphenyl may be any of the 4,4'-, 2,4'-, or 2,2'- positions, with the 4,4'- position being preferred. Hereinafter, compounds in which the substitution position of the functional group such as the methylol group on the biphenyl is at the n,n'- position will also be referred to as the n,n'-isomer.

[0028] The aromatic crosslinking agent preferably contains a crosslinking agent having a biphenyl skeleton, and more preferably contains a crosslinking agent having a 4,4'-isomer biphenyl skeleton. This can improve the adhesion and impact resistance of the resulting electrodeposited coating film to the substrate. In the aromatic crosslinking agent, the content of the crosslinking agent having a 4,4'-isomer biphenyl skeleton may be preferably 50% to 100% by mass, more preferably 80% to 100% by mass, out of 100 parts by mass of the total aromatic crosslinking agent. Aromatic crosslinking agents may be used individually or in combination of two or more.

[0029] In formula (I), the value of n1 can be adjusted by the molar ratio of the phenolic hydroxyl group-containing compound to the aromatic crosslinking agent.

[0030] The number-average molecular weight of the aralkyl-modified phenol resin (a1) is preferably 500 to 1,400, more preferably 550 to 1,200, and even more preferably 600 to 1,000. Having the number-average molecular weight of the aralkyl-modified phenol resin (a1) within this range can result in better adhesion and impact resistance of the resulting electrodeposited coating film to the substrate. In this disclosure, the number-average molecular weight refers to the polystyrene equivalent value measured by gel permeation chromatography.

[0031] The phenolic hydroxyl value of the aralkyl-modified phenol resin (a1) is preferably 200 mg KOH / g or more and 400 mg KOH / g or less, more preferably 220 mg KOH / g or more and 370 mg KOH / g or less, and even more preferably 250 mg KOH / g or more and 350 mg KOH / g or less. Having the primary hydroxyl value of the aralkyl-modified phenol resin (a1) within the above range can result in better adhesion and impact resistance of the resulting electrodeposited coating film to the substrate. In this disclosure, the hydroxyl value refers to the value on a solid content basis and means the hydroxyl value calculated for hydroxyl groups only. The hydroxyl value of the aralkyl-modified phenolic resin (a1) is the value measured according to the method in accordance with JIS K 0070.

[0032] The aralkyl-modified phenolic resin (a1) may be used alone or in combination of two or more types.

[0033] (a2) Epivis type epoxy resin The epibis-type epoxy resin (a2) is typically a condensate of a bisphenol compound and diglycidyl of the bisphenol compound. Examples of the bisphenol compound include bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol E, bisphenol C, and bisphenolacetophenone, with bisphenol A being preferred.

[0034] The epibis-type epoxy resin (a2) is preferably the following formula (II):

[0035] [ka]

[0036] [In formula (II), R 1 Each of them is independent of C1-4 Alkylene group, C 6-10 Represents one or more selected from aromatic hydrocarbon groups and hydrogen atoms; n2 represents an integer greater than or equal to 1, preferably between 1 and 22, more preferably between 1 and 5. It is represented as follows.

[0037] In the epibis-type epoxy resin (a2) described above, the proportion of the bisphenol skeleton is preferably 90% by mass or more and 100% by mass or less. By using such a highly rigid epoxy resin, the heat resistance of the resulting electrodeposited coating can be improved.

[0038] The epoxy equivalent of the epibis-type epoxy resin (a2) is preferably 180 g / eq to 490 g / eq, more preferably 180 g / eq to 300 g / eq, and more preferably 180 g / eq to 200 g / eq. Having the epoxy equivalent of the epibis-type epoxy resin (a2) within this range can result in better heat resistance and impact resistance of the resulting electrodeposited coating.

[0039] It is preferable that the epibis-type epoxy resin (a2) contains a bisphenol A type epoxy resin. Including a bisphenol A type epoxy resin can improve the heat resistance of the resulting electrodeposited coating. The content of the bisphenol A type epoxy resin in the epibis-type epoxy resin (a2) is preferably 50 parts by mass or more and 100 parts by mass or less, more preferably 70 parts by mass or more and 100 parts by mass or less, and even more preferably 80 parts by mass or more and 100 parts by mass or less, out of 100 parts by mass of the total epibis-type epoxy resin (a2). When the content of the bisphenol A type epoxy resin in the epibis-type epoxy resin (a2) is within the above range, the heat resistance and impact resistance of the resulting electrodeposited coating can improve.

[0040] As the epibis-type epoxy resin (a2), commercially available products may be used, or, as mentioned above, products synthesized by condensing bisphenol A with diglycidyl ether of bisphenol A may be used. Representative commercially available products include jER807, 815, 825, 827, 828, 834, 1001, 1004, 1007 and 1009 (all manufactured by Mitsubishi Chemical Corporation), DER330, DER310J, DER301, DER361 (all manufactured by Orin Corporation), YD-8125, YDF-170, YDF-170, YDF-175S, YDF-2001, YDF-2004, YDF-8170 (all manufactured by Nippon Steel Chemical & Material Co., Ltd.). As for the Epibis-type epoxy resin (a2), one type may be used alone, or two or more types may be used in combination.

[0041] The equivalent ratio (epoxy groups / phenolic hydroxyl groups) of epoxy groups in the epibis-type epoxy resin (a2) to the phenolic hydroxyl groups in the aralkyl-modified phenolic resin (a1) is preferably 0.05 to 0.7, more preferably 0.1 to 0.6, even more preferably 0.2 to 0.5, and even more preferably 0.3 to 0.5. Having this equivalent ratio within this range can result in better adhesion, impact resistance, and heat resistance of the resulting electrodeposited coating film to the substrate.

[0042] (a3) Amine compounds Amine compounds (a3) ​​refer to compounds that have at least one amino group in one molecule.

[0043] Examples of the amine compound (a3) ​​include butylamine, octylamine, diethylamine, dibutylamine, methylbutylamine, monoethanolamine, diethanolamine, and N-methylethanolamine. These may be used individually or in combination of two or more.

[0044] The amine compound (a3) ​​preferably includes amine compounds having a hydroxyl group, such as monoethanolamine, diethanolamine, and N-methylethanolamine. Using these materials has the advantage of improving the storage stability of the resulting paint composition.

[0045] The equivalent ratio (amino group / phenolic hydroxyl group) of the amino group contained in the amine compound (a3) ​​to the phenolic hydroxyl group contained in the aralkyl-modified phenol resin (a1) is preferably 0.03 to 0.35, more preferably 0.05 to 0.3, even more preferably 0.1 to 0.25, and even more preferably 0.15 to 0.25. Having the equivalent ratio within this range can improve the emulsification stability of the resulting resin, as well as the adhesion, impact resistance, and heat resistance of the resulting electrodeposited coating film to the substrate.

[0046] The equivalent ratio (amino group / epoxy group) of the amino group contained in the amine compound (a3) ​​to the epoxy group contained in the epibis-type epoxy resin (a2) is preferably 0.3 to 1.5, more preferably 0.4 to 1.2, and even more preferably 0.5 to 1.1. Having this equivalent ratio within this range can result in better impact resistance of the resulting electrodeposited coating.

[0047] The resin (A1) may be a compound obtained by further reaction between a precursor compound, which is a reaction between some of the hydroxyl groups of the aralkyl-modified phenol resin (a1) and the epoxy groups contained in the epibis-type epoxy resin (a2), and the amine compound (a3). Preferably, it is a compound of the following formula (III):

[0048] [ka] [In formula (III), Ar 1 Each of these is independently a C which may have substituents. 6-20 Represents an aromatic ring; Ar 2 Each of these is independently a C which may have substituents. 6-20Represents an aromatic ring; L is given by the following formula:

[0049] [ka] [In the formula, R 1 Each of them is independent of C 1-4 Alkylene group, C 6-10 Represents one or more selected from aromatic hydrocarbon groups and hydrogen atoms; n2 represents an integer greater than or equal to 1, preferably between 1 and 22, more preferably between 1 and 5. It represents a unit expressed as; R 2 Each of them is independent of C 1-4 Alkyl and C 1-4 Represents one type selected from the alkanol groups; m3 represents an integer greater than or equal to 1; n3 represents an integer greater than or equal to 1; In equation (III), the order of existence of the units enclosed in parentheses with m3 or n3 is arbitrary. It can be represented as follows.

[0050] The number-average molecular weight of resin (A1) is preferably 700 to 3,100, more preferably 800 to 3,000, and even more preferably 1,000 to 2,000. Having the number-average molecular weight within this range can result in better heat resistance of the resulting cured electrodeposited coating film, facilitate viscosity adjustment of resin (A1) for smooth synthesis, and make handling of the resulting emulsified dispersion of resin (A1) easier.

[0051] In this disclosure, the number-average molecular weight is the value obtained by converting to polystyrene equivalent using gel permeation chromatography (GPC).

[0052] The amine value of the resin (A1) is preferably 5 mg KOH / g or more and 70 mg KOH / g or less, more preferably 15 mg KOH / g or more and 70 mg KOH / g or less, and even more preferably 15 mg KOH / g or more and 60 mg KOH / g or less. Having the amine value of the resin (A1) within the above range can result in good stability of the resulting electrodeposited coating, and can also result in better adhesion, impact resistance, and heat resistance of the resulting electrodeposited coating film to the substrate. In this disclosure, the amine value refers to the value on a solid content basis and can be measured in accordance with JIS K 7237.

[0053] The sum of the primary hydroxyl value and phenolic hydroxyl value of the resin (A1) is preferably 100 mg KOH / g or more and 250 mg KOH / g or less, more preferably 130 mg KOH / g or more and 250 mg KOH / g or less. When the primary hydroxyl value of the resin (A1) is within the above range, the resulting electrodeposited coating film may have better heat resistance, better adhesion to the substrate, and better impact resistance. The primary hydroxyl value and phenolic hydroxyl value mentioned above refer to the hydroxyl values ​​derived from primary hydroxyl groups and phenolic hydroxyl groups, respectively, and are theoretical values ​​calculated based on the types and amounts of aralkyl-modified phenolic resin (a1), epibis-type epoxy resin (a2), and amine compound (a3) ​​used in the production of resin (A1).

[0054] Preferably, the amino groups of the resin (A1) are neutralized by a neutralizing acid. This allows the resin (A1) to be well dispersed or dissolved in water. It is also preferable that the curing agent (B) be dispersed together with the resin (A1).

[0055] Examples of the neutralizing acid include acid compounds such as inorganic acids and organic acids. Examples of the inorganic acid include hydrochloric acid, nitric acid, and phosphoric acid. Examples of the organic acid include carboxylic acid compounds such as formic acid, acetic acid, propionic acid, and lactic acid; and sulfonic acid compounds such as sulfamic acid. These may be used individually or in combination of two or more. Among these, organic acids are preferred from the viewpoint of the stability of the cationic electrodeposition coating composition, carboxylic acid compounds are more preferred, and lactic acid is particularly preferred from the viewpoint of the emulsification stability of the cationic electrodeposition coating composition.

[0056] The neutralization rate by the neutralizing acid (the equivalent amount of the acid relative to the equivalent amount of amino groups in the resin (A1)) is preferably 10 to 200%, more preferably 30 to 150%. Having the neutralization rate within this range ensures good dispersion or solubility of the resin (A1) and curing agent (B) in water.

[0057] The average particle size of the resin (A1) is preferably 20 nm to 1 μm, more preferably 30 nm to 500 nm, and even more preferably 40 nm to 300 nm. Having the average particle size of the resin (A1) within this range can result in good dispersion stability of the cationic electrodeposition coating composition. In this disclosure, the average particle diameter is the average particle diameter determined by dynamic light scattering, which can be measured using an electrophoretic light scattering spectrometer ELSZ series (manufactured by Otsuka Electronics Co., Ltd.) or the like.

[0058] Any suitable method can be used for the reaction of the aralkyl-modified phenol resin (a1), the epibis-type epoxy resin (a2), and the amine compound (a3). For example, one method involves reacting the aralkyl-modified phenol resin (a1) and the epibis-type epoxy resin (a2) in the presence of a suitable organic solvent by a known method to obtain a precursor compound, then adding an amine compound (a3) ​​in an amount approximately equivalent to the epoxy groups of the precursor compound to the precursor compound, and then heating as necessary.

[0059] Examples of organic solvents used when reacting the precursor compound with the amine compound (a3) ​​include ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ethers such as dibutyl ether and tetrahydrofuran; alcohols; cellosolves; glycol ethers, etc.

[0060] The heating temperature when reacting the precursor compound with the amine compound (a3) ​​is preferably 80 to 180°C, more preferably 110 to 150°C.

[0061] When reacting the precursor compound with the amine compound (a3), a catalyst may be present. Examples of such catalysts include quaternary ammonium salts, tertiary amines, imidazoles, and other amine catalysts.

[0062] The reaction between the precursor compound and the amine compound (a3) ​​can be carried out by any suitable method, for example, by heating the precursor compound and the amine compound (a3). The heating temperature is preferably 80 to 180°C, more preferably 110 to 150°C, and the heating time is, for example, 1 to 5 hours. As a result, the amino group of the amine compound undergoes ring-opening addition to the epoxy group of the precursor compound, yielding resin (A1).

[0063] The solid content of the resin (A1) contained in the coating resin (A) is preferably 80% to 100% by mass, more preferably 90% to 100% by mass, and even more preferably 95% to 100% by mass, out of 100% by mass of the solid content of the coating resin (A).

[0064] In this disclosure, the solid content of a component means the residue after heating the component at 150°C for 1 hour.

[0065] The coating-forming resin (A) of this disclosure may contain other resins (A2) in addition to resin (A1).

[0066] In the cationic electrodeposition coating composition of this disclosure, the solid content of the film-forming resin (A) is preferably 50% by mass or more and 90% by mass or less, and more preferably 60% by mass or more and 80% by mass or less, based on 100 parts by mass of the solid content of the cationic electrodeposition coating composition.

[0067] (B) Hardener The curing agent (B) can form an electrodeposited coating film together with the coating film-forming resin (A). The curing agent (B) comprises a blocked isocyanate compound (B1) or an α,β-unsaturated carbonyl compound (B2). The curing agent (B) may consist of a blocked isocyanate compound (B1) and an α,β-unsaturated carbonyl compound (B2) in combination, or it may not be used in combination, but it is preferable not to use them in combination.

[0068] (B1) Blocked isocyanate compounds A blocked isocyanate compound (B1) refers to a compound in which the isocyanate group of a polyisocyanate compound is blocked by a encapsulating agent.

[0069] The polyisocyanate compound preferably includes an aromatic diisocyanate compound. Including these has the advantage of improving the heat resistance of the resulting coating film. Examples of the aromatic diisocyanate compound include 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate. The aromatic polyisocyanate compound may be used alone or in combination of two or more.

[0070] The encapsulant is not particularly limited, but preferably used are monohydric alkyl (or aromatic) alcohols such as n-butanol, n-hexyl alcohol, 2-ethylhexanol, lauryl alcohol, phenolcarbinol, and methylphenylcarbinol; cellosolves such as ethylene glycol monohexyl ether and ethylene glycol mono-2-ethylhexyl ether; polyether-type terminal diols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycolphenol; polyester-type terminal polyols obtained from diols such as ethylene glycol, propylene glycol, and 1,4-butanediol, and dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, suberic acid, and sebacic acid; phenols such as para-t-butylphenol and cresol; oximes such as dimethyl ketoxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, methyl amyl ketoxime, and cyclohexanone oxime; and lactams represented by ε-caprolactam and γ-butyrolactam. The aforementioned sealing agent may be used alone or in combination of two or more types.

[0071] The blocking rate in the blocked isocyanate compound (B1) is preferably 100%. This can improve the storage stability of the cationic electrodeposition coating composition.

[0072] The blocked isocyanate compound (B1) preferably includes a compound obtained by blocking an aromatic diisocyanate with a encapsulant (hereinafter also referred to as "aromatic blocked isocyanate compound").

[0073] The blocked isocyanate compound (B1) and the resin (A1) can be cured by a reaction between the isocyanate group generated when the encapsulant blocking the blocked isocyanate group is removed and the hydroxyl group contained in the resin (A1).

[0074] When a blocked isocyanate compound (B1) is used as the curing agent (B), the curing agent (B) may contain other curing agents in addition to the blocked isocyanate compound (B1). Examples of other curing agents include at least one selected from the group consisting of organic curing agents such as melamine resin or phenolic resin; silane coupling agents; and metal curing agents.

[0075] The equivalent ratio (OH / NCO) of the total primary hydroxyl groups and phenolic hydroxyl groups contained in the resin (A1) to the isocyanate groups contained in the blocked isocyanate compound (B1) is preferably 0.8 or more and 1.6 or less, more preferably 0.9 or more and 1.5 or less.

[0076] (B2) α,β-unsaturated carbonyl compounds (B2) The α,β-unsaturated carbonyl compound (B2) refers to a compound having two or more α,β-unsaturated carbonyl groups in one molecule. Preferably, the α,β-unsaturated carbonyl compound (B2) includes a reaction product (B2-1) of an aralkyl-modified phenol resin (b2-1), an epihalohydrin compound (b2-2), and a monomer (b2-3) having an α,β-unsaturated carbonyl group; or a bismaleimide resin (B2-2). Hereinafter, the reaction product (B2-1) of the aralkyl-modified phenol resin (b2-1), the epihalohydrin compound (b2-2), and the monomer having an α,β-unsaturated carbonyl group (b2-3) will also simply be referred to as "compound (B2-1)".

[0077] (B2-1) Compounds containing α,β-unsaturated carbonyl groups The compound (B2-1) is a compound obtained by further reaction between a monomer having an α,β-unsaturated carbonyl group and a compound in which some of the hydroxyl groups contained in the aralkyl-modified phenol resin (b2-1) have reacted with an epihalohydrin to form a glycidyl compound.

[0078] The aralkyl-modified phenol resin (b2-1) is synonymous with the aralkyl-modified phenol resin (a1). Specifically, the aralkyl-modified phenol resin (b2-1) is a phenol resin having a structure derived from an aralkyl group, and typically has a structure in which a structure derived from an aralkyl group is introduced into the repeating structural unit of a novolac-type phenol resin.

[0079] The aralkyl-modified phenol resin (b2-1) is preferably a compound represented by formula (I), and more preferably the Ar in formula (I). 2 A biphenyl aralkyl-modified novolac-type phenolic resin, in which the group is derived from biphenyl, is more preferable. The content of biphenylaralkyl-modified novolac-type phenolic resin in the aralkyl-modified phenolic resin (b2-1) is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less.

[0080] The epihalohydrin compound (b2-2) refers to a compound in which, in a 1,2-alkylene oxide, the hydrogen atom bonded to the terminal carbon atom of the alkyl group attached to the oxirane ring is replaced by a halogen atom. The hydroxyl group of the aralkyl-modified phenol resin (b2-1) and the halogen atom of the epihalohydrin compound (b2-2) can undergo a dehalogenation reaction to obtain the reaction products of these compounds.

[0081] Examples of the epihalohydrin compound (b2-2) include epichlorohydrin, epibromohydrin, epiiodohydrin, and β-methylepichlorohydrin. Among these, epichlorohydrin is preferred as the epihalohydrin compound (b2-2). One epihalohydrin compound (b2-2) may be used, or two or more may be used in combination.

[0082] The equivalent ratio of the epihalohydrin compound (b2-2) to the primary hydroxyl group contained in the aralkyl-modified phenol resin (b2-1) (primary hydroxyl group / epihalohydrin compound (b2-2)) is preferably 0.8 to 20, more preferably 0.9 to 15, and even more preferably 1.0 to 10. By having the equivalent ratio within this range, the reaction between the aralkyl-modified phenol resin (b2-1) and the epihalohydrin compound (b2-2) can be controlled, resulting in good manufacturing efficiency and potentially better adhesion and impact resistance of the resulting electrodeposited coating film to the substrate.

[0083] The monomers (b2-3) having α,β-unsaturated carbonyl groups are compounds that have one or more carboxyl groups and one or more ethylenically unsaturated bonds in one molecule.

[0084] Examples of monomers (b2-3) having an α,β-unsaturated carbonyl group include unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; unsaturated dicarboxylic acids such as itaconic acid, maleic acid, maleic anhydride, fumaric acid, and citraconic acid; anhydrides of the unsaturated dicarboxylic acids; esters of the unsaturated monocarboxylic acids or unsaturated dicarboxylic acids; and caprolactone-modified products of the unsaturated monocarboxylic acids or unsaturated dicarboxylic acids. Among these, (meth)acrylic acid is preferred as the monomer (b2-3) having an α,β-unsaturated carbonyl group. Only one monomer (b2-3) may be used, or two or more may be used in combination. In this disclosure, (meth)acrylic acid refers to acrylic acid or methacrylic acid.

[0085] When reacting the aralkyl-modified phenol resin (b2-1) with the epihalohydrin compound (b2-2), it is preferable to include an alkali metal hydroxide. This can promote the dehalogenation reaction. Examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide. From the viewpoint of reaction control and suppression of side reactions, the amount of alkali metal hydroxide may be, for example, preferably 0.5 moles to 2.0 moles, more preferably 0.7 moles to 1.8 moles, and even more preferably 0.9 moles to 1.6 moles, per 1 mole of total phenolic hydroxyl groups contained in the aralkyl-modified phenol resin (b2-1).

[0086] The reaction between the aralkyl-modified phenol resin (b2-1) and the epihalohydrin compound (b2-2) is preferably carried out under normal pressure or reduced pressure. The reaction temperature is preferably 20 to 150°C, more preferably 30 to 120°C, and even more preferably 35 to 100°C, from the viewpoint of reaction control and suppression of side reactions. The reaction product may be washed or purified as needed.

[0087] The number-average molecular weight of the reaction product between the aralkyl-modified phenol resin (b2-1) and the epihalohydrin compound (b2-2) is preferably 400 to 2,500, more preferably 400 to 2,000. Having the number-average molecular weight of the reaction product within this range can result in better adhesion and impact resistance of the resulting electrodeposited coating film to the substrate.

[0088] The epoxy equivalent of the reaction product between the aralkyl-modified phenol resin (b2-1) and the epihalohydrin compound (b2-2) is preferably 200 g / eq to 300 g / eq, more preferably 250 g / eq to 300 g / eq. Having the epoxy equivalent of the reaction product within this range can result in better adhesion and impact resistance of the resulting electrodeposited coating to the substrate.

[0089] A commercially available product may be used as the reaction product of the aralkyl-modified phenol resin (b2-1) and the epihalohydrin compound (b2-2). Examples of such commercially available products include NC2000, NC3000-FH, NC3000-H, NC3000, NC3000L, NC3100, etc. (manufactured by Nippon Kayaku Co., Ltd.).

[0090] Compound (B2-1) can be produced by reacting the reaction product of the aralkyl-modified phenol resin (b2-1) and the epihalohydrin compound (b2-2) with a monomer (b2-3) having an α,β-unsaturated carbonyl group. The reaction may be carried out in the presence of an organic solvent. Examples of such organic solvents include ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ethers such as dibutyl ether and tetrahydrofuran; alcohols; cellosolves; glycol ethers, etc. The reaction temperature may be 80 to 150°C, or 90 to 120°C. The reaction time may be 30 minutes to 20 hours, preferably 1 to 10 hours.

[0091] The number-average molecular weight of compound (B2-1) is preferably 500 to 3,000, more preferably 500 to 2,500. Having the number-average molecular weight of compound (B2-1) within this range can result in better adhesion and impact resistance of the resulting electrodeposited coating to the substrate.

[0092] The equivalent amount of α,β-unsaturated carbonyl groups in compound (B2-1) is preferably 300 g / eq to 400 g / eq, more preferably 330 g / eq to 370 g / eq. Having the equivalent amount of α,β-unsaturated carbonyl groups in compound (B2-1) within this range can result in better adhesion and impact resistance of the resulting electrodeposited coating film to the substrate.

[0093] When compound (B2-1) is used as the curing agent (B), the equivalent ratio of α,β-unsaturated carbonyl groups in compound (B2-1) to the total of primary hydroxyl groups and phenolic hydroxyl groups in the coating resin (A) (α,β-unsaturated carbonyl groups / hydroxyl groups) is preferably 0.1 to 1.0, more preferably 0.2 to 0.6. Having this equivalent ratio within this range can result in better heat resistance, adhesion to the substrate, and impact resistance of the resulting electrodeposited coating.

[0094] (B2-2) Bismaleimide compound The bismaleimide compound (B2-2) is a compound having two or more maleimide groups in its molecule.

[0095] The bismaleimide compound (B2-2) is preferably of the following formula (IV):

[0096] [ka]

[0097] [In formula (IV), In the formula, R 3 ~R 6 These are, independently, hydrogen atoms and C 1-20 Represents an alkyl group, an amino group (-NH2), a nitro group (-NO2), or a nitroso group (-NO); L 2 This represents a divalent organic group. It is represented as follows.

[0098] In equation (IV), R 3 ~R 6 C represented by 1-20 Examples of alkyl groups include methyl, ethyl, and propyl groups. 1-5 Alkyl alkyl groups are preferred.

[0099] In equation (IV), L 2 As a divalent organic group represented by , C 1-20 Aliphatic saturated hydrocarbon group, C 6-20A C having an aromatic hydrocarbon group or an aromatic ring. 7-20 Examples include hydrocarbon groups, which may or may not have substituents. 1-20 As for aliphatic hydrocarbon groups, C 4-12 Alkylene group is preferred. 6-20 Examples of aromatic hydrocarbon groups include phenylene, torylene, xylylene, and naphthylene groups, with phenylene being preferred. 7-20 Examples of hydrocarbon groups include hydrocarbon groups having 1 to 4 aromatic rings and which may contain heteroatoms in the main chain. Examples of heteroatoms that may be contained in the main chain include oxygen atoms and sulfur atoms, and more specifically, embodiments in which each aromatic ring is bonded by -O-, -S-, -SS-, -SO2-, etc.

[0100] The substituents include C 1-5 Examples include alkyl groups, -NO2, -NH2, -F, -Cl, and -Br.

[0101] Examples of the bismaleimide compound (B2-2) include 4,4'-diphenylmethanebismaleimide, m-phenylenebismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, and 1,6'-bismaleimide-(2,2,4-trimethyl)hexane.

[0102] Commercially available products may be used as the bismaleimide compound (B2-2). Examples of commercially available products include: 4,4'-diphenylmethanebismaleimide (BMI-1000, BMI-1000H, BMI-1100, BMI-1100H, manufactured by Yamato Kasei Kogyo Co., Ltd.); m-phenylenebismaleimide (BMI-3000, BMI-3000H, manufactured by Yamato Kasei Kogyo Co., Ltd.); bisphenol A diphenyl etherbismaleimide (BMI-4000, manufactured by Yamato Kasei Kogyo Co., Ltd.); 4,4'-diphenylmethanebismaleimide (BMI, manufactured by K.I. Kasei Co., Ltd.); (bis-(3-ethyl-5-methyl-4-maleimidophenyl)methane (BMI-70, manufactured by K.I. Kasei Co., Ltd.); N,N'-m-phenylenebismaleimide (Sanfer Examples include BM (manufactured by Sanshin Chemical Industry Co., Ltd.), 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide (BMI-5100, manufactured by Yamato Chemical Industries Co., Ltd.), 2,2-bis[4-(4-maleimidophenoxy)phenylpropane] (BMI-70, manufactured by I-K Chemical Co., Ltd.), 4-methyl-1,3-phenylenebismaleimide (BMI-7000, BMI-7000H, manufactured by Yamato Chemical Industries Co., Ltd.), and 1,6'-bismaleimide-(2,2,4-trimethyl)hexane (BMI-TMH, manufactured by Yamato Chemical Industries Co., Ltd.), HR3070, HR3072, HR7000, HR-YSP (manufactured by Printec Co., Ltd.), BMI-1100H (manufactured by Yamato Chemical Industries Co., Ltd.), etc.

[0103] As the bismaleimide compound (B2-2), one type may be used alone, or two or more types may be used in combination.

[0104] When a bismaleimide compound (B2-2) is used as the curing agent (B), the mass ratio of (B2-2) to the film-forming resin (A) [(B2-2) / (A)] is preferably 0.2 to 1.0, and more preferably 0.2 to 0.9. Having this mass ratio within this range can result in better heat resistance, better adhesion to the substrate, and better impact resistance of the resulting electrodeposited coating.

[0105] (others) The cationic electrodeposition coating composition contains an aqueous medium. The aqueous medium is preferably water, a water-soluble organic solvent, or a mixture of water and a water-soluble organic solvent. Specific examples of the organic solvent include, for example, ethylene glycol, propylene glycol, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, diethylene glycol, dipropylene glycol, and diethylene glycol monobutyl ether. From the viewpoint of minimizing the use of VOCs, it is preferable to use as little organic solvent as possible.

[0106] The cationic electrodeposition coating composition may optionally contain pigments. Specific examples of pigments include coloring pigments such as titanium dioxide, yellow iron oxide, red iron oxide, carbon black, phthalocyanine blue, phthalocyanine green, azo red, quinacridone red, and benzimidazolon yellow; extender pigments such as calcium carbonate, barium sulfate, kaolin, clay, and talc; and anticorrosive pigments such as iron phosphate, aluminum phosphate, calcium phosphate, aluminum tripolyphosphate, aluminum molybdate, calcium molybdate, and aluminum phosphomolybdate.

[0107] These pigments are preferably dispersed in an aqueous medium at a high concentration using a pigment dispersion resin to form a paste (pigment dispersion paste), which is then added to the cationic electrodeposition coating composition. The pigment dispersion resin is not particularly limited, and for example, cationic polymers such as cationic or nonionic low molecular weight surfactants or modified epoxy resins having quaternary ammonium groups and / or tertiary sulfonium groups can be used. After mixing these components, the mixture is dispersed until the pigment has a predetermined uniform particle size to obtain a pigment dispersion paste. A conventional dispersion apparatus is used. For example, a ball mill or a sand grind mill is used. The particle size of the pigment contained in the pigment dispersion paste is preferably 15 μm or less.

[0108] When using cationic pigments, the pigment concentration in the cationic electrodeposition coating composition is preferably 2% by mass or more and 50% by mass or less of the total solid content of the cationic electrodeposition coating composition. This ensures that a good electrodeposition coating film is obtained and that the stability of the coating is maintained.

[0109] The cationic electrodeposition coating composition may contain additives as needed. Specific examples of additives include dispersants, plasticizers, viscosity modifiers, surface modifiers, defoamers, UV absorbers, pH adjusters, and catalysts.

[0110] When a blocked isocyanate compound (B1) is used as the curing agent (B), inorganic compounds such as organotin compounds, zinc compounds, bismuth compounds, titanium compounds, zirconium compounds, and yttrium compounds; or organic compounds such as phosphazene compounds, amine compounds, and quaternary salt compounds may be used as catalysts. Furthermore, when an α,β-unsaturated carbonyl compound (B2) is used as the curing agent (B), basic catalysts such as amidine compounds and guanidine compounds may be used as catalysts.

[0111] Preparation of cationic electrodeposition coating compositions The cationic electrodeposition coating composition can be produced by adding predetermined amounts of a film-forming resin (A), a curing agent (B), and other components (coloring pigments, additives, etc.) as needed, to an aqueous medium and dispersing them.

[0112] In one embodiment, a coating resin (A), a curing agent (B), and an organic solvent as needed are mixed, and then a neutralizing acid is mixed as needed. An aqueous dispersion is obtained by dropping the resulting mixture into an aqueous medium, or by adding an aqueous medium to the resulting mixture and dispersing or dissolving it. A cationic electrodeposition coating composition can be prepared by distilling off the organic solvent as needed.

[0113] In another embodiment, a film-forming resin (A) and an organic solvent as needed are mixed, and then a neutralizing acid is mixed as needed. An aqueous dispersion is obtained by dropping the resulting mixture into an aqueous medium, or by adding an aqueous medium to the resulting mixture and dispersing or dissolving it. If necessary, the organic solvent is removed by distillation. A cationic electrodeposition coating composition can be prepared by mixing the obtained aqueous dispersion with a curing agent (B), and then further mixing with deionized water.

[0114] Furthermore, other components used as needed in the production of cationic electrodeposition coating compositions can be added at any appropriate time.

[0115] The technical scope of this disclosure also includes a method for electrodepositing the cationic electrodeposition coating composition, and a laminate having an electrodeposited coating film formed from the cationic electrodeposition coating composition and a substrate.

[0116] Object to be coated The substrate to be coated with the cationic electrodeposition coating composition is not particularly limited as long as it is conductive. For example, metals (iron, steel, copper, aluminum, magnesium, tin, zinc, etc. and alloys containing these metals), iron plates, steel plates, aluminum plates, and those that have been surface-treated (for example, phosphate-based, chromic acid-based, or zirconium-based chemical conversion treatments), and molded products thereof can be used.

[0117] Electrodeposition coating method The electrodeposition coating method for the cationic electrodeposition coating composition is not particularly limited and can be carried out by conventionally known cationic electrodeposition coating methods. Specifically, the electrodeposition coating method includes immersing an object to be coated in the cationic electrodeposition coating composition, applying a voltage to form a deposited coating film, and drying and curing the deposited coating film to obtain an electrodeposited coating film. When an object to be coated is immersed in the cationic electrodeposition coating composition and a voltage is applied, the object can act as a cathode, and a coating film can be deposited on the surface of the object. By drying and curing the deposited coating film, an electrodeposited coating film can be manufactured. The deposited coating film may be washed with water before drying and curing, if necessary.

[0118] The bath temperature of the cationic electrodeposition coating composition is preferably 10°C to 40°C, and more preferably 10°C to 30°C. The applied voltage is preferably 50V to 450V, and more preferably 100V to 400V. The energizing time is preferably 1 second to 300 seconds, and more preferably 30 seconds to 180 seconds.

[0119] By heating an object having a deposited coating on its surface, the deposited coating can be dried and cured. The heating temperature may be, for example, 20 to 300°C, preferably 150 to 300°C, more preferably 200 to 300°C, and even more preferably 250 to 300°C. The heating time can be appropriately selected according to the temperature.

[0120] The heating time may preferably be 5 to 180 minutes, more preferably 10 to 180 minutes, and more preferably 10 to 120 minutes. The thickness of the resulting electrodeposited coating is preferably 5 to 50 μm.

[0121] If necessary, additional coatings may be formed on the electrodeposited coating. Examples of coatings that can be formed on the electrodeposited coating include intermediate coatings, topcoat base coatings, and clear coatings, which are formed in the automotive painting field. Only one of these coatings may be formed, or two or more coatings may be formed.

[0122] The cationic electrodeposition coating composition disclosed herein does not use harmful organic solvents and can realize an electrodeposition coating film with excellent heat resistance, adhesion to the substrate, and impact resistance. Therefore, it can be suitably used in electronic devices and the like, where high-performance materials with excellent insulation, heat resistance, chemical resistance, dimensional stability, etc., are required as miniaturization, thinning, and high functionality become more common. [Examples]

[0123] The present invention will be further described in detail by the following examples, but the present invention is not limited thereto.

[0124] (Manufacturing Example 1) Manufacturing of coating-forming resin (A1-1) In a reaction vessel equipped with a stirring device, a condenser, a nitrogen inlet tube, and a thermometer, 756.5 parts by mass of HE200C-10 as aralkyl-modified phenol-modified novolac resin (a1-1) and 277.5 parts by mass of DER331J as epibis-type epoxy resin (a2-1) were added and dissolved in 271.8 parts by mass of methyl isobutyl ketone (hereinafter referred to as "MIBK"). Dimethylbenzylamine 0.6 parts by mass was added, and the etherification reaction was continued at 105°C until the epoxy equivalent reached 1,194 g / eq, yielding a phenol resin modified with epoxy resin. After the reaction was complete, 55.4 parts by mass of methylethanolamine was added as the amine compound (a3-1), and the mixture was reacted at 120°C for 1 hour to obtain a coating resin (A1-1) (hydroxyl value: 190 mg KOH / g, amine value: 38 mg KOH / g, number average molecular weight: 1,220, average particle size: 85 nm, solid content concentration: 80% by mass).

[0125] The coating-forming resins (A1-2) to (A1-10) were obtained in the same manner as in Manufacturing Example 1, except that the materials used and their proportions were changed as shown in Table 1. The characteristic values ​​of each coating-forming resin are shown in Table 1.

[0126] [Table 1]

[0127] (Manufacturing Example 2) Manufacturing of hardener (B1-1) In a reaction vessel equipped with a stirring device, cooling tubes, nitrogen inlet tubes, and a thermometer, 1,250 parts by mass of diphenylmethane diisocyanate (MDI) and 313.1 parts by mass of MIBK were charged and heated to 80°C. Then, 2.5 parts by mass of dibutyltin dilaurate was added as a reaction catalyst. To this, 1,180 parts by mass of butyl cellosolve was added dropwise as blocking agent 1 over 2 hours at 80°C. After further heating at 100°C for 4 hours, the absorption based on the isocyanate group was confirmed to have disappeared by measuring the IR spectrum. After cooling, 295.0 parts by mass of MIBK was added to obtain curing agent (B1-1) (solid content concentration: 80% by mass).

[0128] (Manufacturing Example 3) Manufacturing of hardener (B1-2) In a reaction vessel equipped with a stirring device, cooling tubes, nitrogen inlet tubes, and a thermometer, 870 parts by mass of Cosmonate T100 and 217.5 parts by mass of MIBK were charged and heated to 80°C. Then, 2.5 parts by mass of dibutyltin dilaurate was added as a reaction catalyst. To this, 1,180 parts by mass of butyl cellosolve was added dropwise as blocking agent 1 over 2 hours at 80°C. After further heating at 100°C for 4 hours, the absorption based on the isocyanate group was confirmed to have disappeared by measuring the IR spectrum. After cooling, 292.5 parts by mass of MIBK was added to obtain curing agent (B1-2) (solid content concentration: 80% by mass).

[0129] (Manufacturing Example 4) Manufacturing of hardener (B1-3) In a reaction vessel equipped with a stirring device, cooling tubes, nitrogen inlet tubes, and a thermometer, 1,990 parts by mass of Coronate HX and 498.1 parts by mass of MIBK were charged and heated to 80°C. Then, 2.5 parts by mass of dibutyltin dilaurate was added as a reaction catalyst. To this, 870 parts by mass of MEK oxime was added dropwise as blocking agent 2 at 80°C for 2 hours. After further heating at 100°C for 4 hours, the absorption based on the isocyanate group was confirmed to have disappeared by measuring the IR spectrum. After cooling, 217.5 parts by mass of MIBK was added to obtain a curing agent (B1-3) (solid content concentration: 80% by mass).

[0130] (Manufacturing Example 5) Manufacturing of hardener (B2-11) In a reaction vessel equipped with a stirring device, condenser, nitrogen inlet tube, and thermometer, 275 parts by mass of NC3000 and 140 parts by mass of MIBK were charged. These were heated to 50°C and dissolved. Then, 75.6 parts by mass of acrylic acid and 3.5 parts by mass of dibutylhydroxytoluene were added as monomers having α,β-unsaturated carbonyl groups (b2-31). These were heated to 110°C, 1.7 parts by mass of dimethylbenzylamine were added, and the mixture was heated for a further 6 hours until the epoxy equivalent reached 8,000 g / eq or more, yielding a curing agent (B2-11) (solid content concentration: 70% by mass).

[0131] (Manufacturing Example 6) Manufacturing of hardener (B2-12) In a reaction vessel equipped with a stirring device, condenser, nitrogen inlet tube, and thermometer, 188 parts by mass of DER310J and 107.8 parts by mass of MIBK were charged and heated to 50°C until dissolved. Then, 75.6 parts by mass of acrylic acid and 3.5 parts by mass of dibutylhydroxytoluene were added as monomers (b2-31) having α,β-unsaturated carbonyl groups. These were heated to 110°C, 1.7 parts by mass of dimethylbenzylamine was added, and the mixture was heated for a further 6 hours until the epoxy equivalent was 8,000 g / eq or more, yielding a curing agent (B2-12) (solid content concentration: 70% by mass).

[0132] (Example 1) Preparation of electrodeposition coating composition 1 1,361.6 parts by mass of film-forming resin (A1-1) and 801.3 parts by mass of curing agent (B1-1) were stirred with a disperser, and 132.8 parts by mass of 50% lactic acid aqueous solution (neutralization rate: 100 mol%) was gradually added. Further, 6,355.8 parts by mass of deionized water were added while stirring to obtain an aqueous dispersion (solid content concentration: 20% by mass). 470 parts by mass of the MIBK and water mixture were removed by distillation at 50°C under reduced pressure, and the same amount of deionized water was added to obtain electrodeposition coating composition 1 (solid content concentration: 20% by mass). Furthermore, the equivalent ratio (isocyanate group / hydroxyl group) between the sum of the primary hydroxyl value and phenolic hydroxyl value contained in (A1-1) and the isocyanate group contained in (B1-1) is 1.4.

[0133] (Examples 2-12, Comparative Examples 1-4) Electrodeposition coating compositions 2 to 16 were obtained in the same manner as in Example 1, except that the types and amounts of the film-forming resin and curing agent used were changed as shown in Table 2. However, in Comparative Example 3, the solid content mass ratio [((A1-1) / (Y-1)] of (A1-1) to (Y-1) was set to 1.7. Furthermore, the paint composition is expressed in parts by mass of its natural state, including volatile components, etc.

[0134] (Example 13) Preparation of electrodeposition coating composition 17 1,361.6 parts by mass of film-forming resin (A1-1) and 731.7 parts by mass of curing agent (B2-11) were stirred with a disperser, and 132.8 parts by mass of 50% lactic acid aqueous solution (neutralization rate: 100 mol%) was gradually added. Further, 6,147.1 parts by mass of deionized water were added while stirring to obtain an aqueous dispersion (solid content concentration: 20% by mass). 450 parts by mass of the MIBK and water mixture were removed by distillation at 50°C under reduced pressure, and deionized water was added to the amount removed to obtain electrodeposition coating composition 17 (solid content concentration: 20% by mass). Furthermore, the equivalent ratio (unsaturated carbonyl group / hydroxyl group) between the sum of the primary hydroxyl value and phenolic hydroxyl value contained in (A1-1) and the α,β-unsaturated carbonyl group contained in (B2-1) is 0.4.

[0135] (Examples 14-23, Comparative Examples 5, 6) Electrodeposition coating compositions 18 to 29 were obtained in the same manner as in Example 13, except that the types and amounts of the film-forming resin and curing agent used were changed as shown in Table 3.

[0136] (Example 24) Preparation of electrodeposition coating composition 30 1,361.6 parts by mass of film-forming resin (A1-1) and 544.6 parts by mass of curing agent (B2-21) were stirred with a disperser, and 132.8 parts by mass of 50% lactic acid aqueous solution (neutralization rate: 100 mol%) was gradually added. Further, 6,130.1 parts by mass of deionized water were added while stirring to obtain an aqueous dispersion (solid content concentration: 20% by mass). 300 parts by mass of the MIBK and water mixture were removed by distillation at 50°C under reduced pressure, and the same amount of deionized water was added to obtain electrodeposition coating composition 30 (solid content concentration: 20% by mass). Furthermore, the content of (B2-2) relative to (A1-1) [(B2-2) / (A1-1):mass ratio] is 0.5.

[0137] (Examples 25-34, Comparative Examples 7, 8) Electrodeposition coating compositions 31 to 42 were obtained in the same manner as in Example 24, except that the types and amounts of the coating-forming resin and curing agent used were changed as shown in Table 4.

[0138] The details of each component shown in the table below, which was used in the examples and comparative examples, are as follows. Materials constituting the coating-forming resin (A): Aalkyl-modified phenolic resin (a1): (a1-1): HE200C-10 (biphenyl aralkyl type phenolic resin, manufactured by Airwater Co., Ltd.), hydroxyl value: 270 mg KOH / g, number average molecular weight: 720, solid content concentration: 100% by mass (a1-2): HE200-17 (biphenyl aralkyl type phenolic resin, manufactured by Airwater Co., Ltd.), hydroxyl value: 270 mg KOH / g, number average molecular weight: 760, solid content concentration: 100% by mass (a1-3): HE200-07 (Biphenyl aralkyl type phenolic resin, manufactured by Airwater Co., Ltd.), Hydroxyl value: 270 mg KOH / g, Number average molecular weight: 620, Solid content concentration: 100% by mass (a1-4): HE100-15 (biphenyl aralkyl type phenolic resin, manufactured by Airwater Co., Ltd.), hydroxyl value: 320 mg KOH / g, number average molecular weight: 910, solid content concentration: 100% by mass (x-1): KA-1160 (cresol-type phenolic resin, manufactured by DIC Corporation), hydroxyl value: 480 mg KOH / g, number average molecular weight: 870, solid content concentration: 100% by mass (x-2): TD-2131 (Novolac-type phenolic resin, manufactured by DIC Corporation), Hydroxyl value: 540 mg KOH / g, Number average molecular weight: 760, Solid content concentration: 100% by mass Epivis-type epoxy resin (a2): (a2-1): DER310J (Bisphenol A type epoxy resin, manufactured by Olin Co., Ltd.), epoxy equivalent: 188 g / eq, solids concentration: 100% by mass (a2-2): jER1001 (Bisphenol A type epoxy resin, manufactured by Mitsubishi Chemical Corporation), epoxy equivalent: 490 g / eq, solids concentration: 100% by mass Amine compound (a3): (a3-1): Methylethanolamine (manufactured by Tokyo Chemical Industry Co., Ltd.) (a3-2): Diethanolamine (manufactured by Tokyo Chemical Industry Co., Ltd.) Organic solvent: Methyl isobutyl ketone (MIBK: manufactured by Shoei Chemical Co., Ltd.) Reaction catalyst: Dimethylbenzylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) Materials constituting the hardening agent (B); Materials constituting the blocked isocyanate compound (B1): Diphenylmethane diisocyanate (MDI) (aromatic polyisocyanate, manufactured by Tosoh Corporation), NCO content: 33.6% by mass, solids content: 100% by mass Cosmonate T100 (toluene-2,4-diisocyanate, manufactured by Mitsui Chemicals Fine Co., Ltd.), NCO content: 48.3% by mass, solids content: 100% by mass Coronate HX (a nurate of hexamethylene diisocyanate (HDI), manufactured by Tosoh Corporation), NCO content: 21.1% by mass, solid content concentration: 100% by mass Blocking agent 1: Butyl cellosolve (manufactured by Shoei Chemical Co., Ltd.) Blocking agent 2: MEK oxime (methyl ethyl ketone oxime, manufactured by UBE) Reaction catalyst: Dibutyltin dilaurate (tin-based catalyst, manufactured by Kyodo Yakuhin Co., Ltd.) Materials constituting the α,β-unsaturated carbonyl compound (B2-1): NC3000 (biphenyl aralkyl-modified novolac-type epoxy resin, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 275 g / eq, molecular weight: 780) is a commercially available product obtained by reacting an aralkyl-modified phenol resin (b2-1) and an epihalohydrin compound (b2-2). Monomers having α,β-unsaturated carbonyl groups (b2-3): Acrylic acid (manufactured by Osaka Organic Chemical Industry Co., Ltd.), active ingredient concentration: 100% by mass Polymerization inhibitor: Dibutylhydroxytoluene (manufactured by Tokyo Chemical Industry Co., Ltd.) Reaction catalyst: Dimethylbenzylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) Materials constituting the bismaleimide compound (B2-2): (B2-21) BMI-1000 (4,4'-diphenylmethane bismaleimide, manufactured by Yamato Chemical Industries, Ltd.), solid content concentration: 100% by mass (B2-22) BMI-4000 (Bisphenol A diphenyl ether bismaleimide, manufactured by Yamato Chemical Industries, Ltd.), Solid content concentration: 100% by mass Other hardeners: (Y-1) Cymel 325 (methylated melamine resin, manufactured by Ornex Co., Ltd.), solid content concentration: 80% by mass)

[0139] Preparation of electrodeposited coating (test specimen) The cold-rolled steel sheet (JIS G 3141, SPCC-SD) to be coated was degreased by immersing it in Surf Cleaner EC90 (manufactured by Nippon Paint Surf Chemicals Co., Ltd.) at 50°C for 2 minutes. Next, the surface was prepared with Surf Fine GL1 (manufactured by Nippon Paint Surf Chemicals Co., Ltd.), and then treated with zinc phosphate by immersing it in Surf Dyne SD-5000 (manufactured by Nippon Paint Surf Chemicals Co., Ltd., zinc phosphate conversion treatment solution) at 40°C for 2 minutes. After that, it was rinsed with deionized water. After completely immersing the object to be coated in an electrodeposition bath at a liquid temperature of 30°C containing the electrodeposition coating composition obtained in the above examples and comparative examples, the application of voltage was immediately started, and the voltage was increased for 30 seconds until it reached 150V, and then held for 180 seconds to form a deposited coating film on the object to be coated. The obtained deposited coating film was heated at 250°C for 25 minutes to dry and cure, and an electrodeposited coated plate with an electrodeposited coating film thickness of 30 μm was obtained. The electrodeposited coated boards underwent evaluation tests, as described later, and the results are shown in Tables 2-4.

[0140] Evaluation items 1) Heat resistance The electrodeposited coated boards obtained in the above examples and comparative examples were subjected to a heat resistance test at 230°C for 100 hours using a Perfect Jet Oven (manufactured by espec). The film thickness of the coating after the test was measured, and the remaining coating percentage was calculated according to the following formula to evaluate the heat resistance of the coating. The evaluation criteria were as follows: A score of △ or higher was considered a pass. The film thickness of the coating was measured using an overcurrent film thickness gauge LH-370 (manufactured by kett). Coating film retention rate (%) = Coating film thickness after testing / Coating film thickness before testing × 100 ◎: The paint film retention rate is 90% or higher. ○: The remaining coating film is between 85% and 90%. △: The remaining coating film is between 80% and 85%. ×: The remaining coating film is less than 80%.

[0141] 2) Impact resistance (resistance to heavy drops) The electrodeposited coated boards obtained in the examples and comparative examples were evaluated for their resistance to dropping weights in accordance with JIS K 5600-5-3 (Weight resistance test). Specifically, a DuPont impact tester (1 / 2-inch impact type; manufactured by Ueshima Seisakusho Co., Ltd.) was used to drop a 500g weight from a certain height, and the height at which cracks occurred was measured to evaluate impact resistance (resistance to weight drops). The evaluation criteria were as follows: A score of △ or higher was considered a pass. ◎: Even when a weight is dropped from a height of 50 cm, no cracks, splits, or peeling will occur. ○: No cracks, splits, or peeling occur when the weight is dropped from a height of 40 cm, but cracks, splits, or peeling occur when dropped from a height of 50 cm. △: No cracks, splits, or peeling occur when the weight is dropped from a height of 30 cm, but cracks, splits, or peeling occur when dropped from a height of 40 cm. ×: Dropping the weight from a height of 30 cm will cause cracks, splits, peeling, etc.

[0142] [Table 2]

[0143] [Table 3]

[0144] [Table 4]

[0145] Examples 1 to 34 are embodiments of the present disclosure, and no harmful organic solvents were used. The resulting coatings exhibited excellent heat resistance and impact resistance. Due to their excellent impact resistance, they also exhibited excellent adhesion to the substrate. Comparative Examples 1, 2, 5, 6, 7, and 8 were examples in which aralkyl-modified phenolic resin (a1) was not used as a component of the coating resin (A), and the heat resistance and impact resistance were not sufficiently satisfactory. Comparative Example 3 is an example in which an amino resin was used as the curing agent (B), and the heat resistance and impact resistance were not sufficiently satisfactory. Comparative Example 4 was an example that did not contain the hardening agent (B), and therefore did not fully satisfy the requirements for heat resistance and impact resistance. [Industrial applicability]

[0146] The cationic electrodeposition coating composition disclosed herein does not use harmful organic solvents and can realize a coating film with excellent heat resistance, adhesion to the substrate, and impact resistance. Therefore, it can be suitably used in electronic devices and the like, where high-performance materials with excellent insulation, heat resistance, chemical resistance, and dimensional stability are required as miniaturization, thinning, and high functionality become more common.

Claims

1. It comprises a film-forming resin (A) and a hardening agent (B), The coating-forming resin (A) includes a resin (A1) which is a reaction product of an aralkyl-modified phenol resin (a1), an epibis-type epoxy resin (a2), and an amine compound (a3). The curing agent (B) comprises a blocked isocyanate compound (B1) or an α,β-unsaturated carbonyl compound (B2), A cationic electrodeposition coating composition wherein the equivalent ratio (amino group / phenolic hydroxyl group) of the amino group contained in the amine compound (a3) ​​to the phenolic hydroxyl group contained in the aralkyl-modified phenol resin (a1) is 0.03 or more and 0.35 or less.

2. The cationic electrodeposition coating composition according to claim 1, wherein the amine value of the resin (A1) is 15 mg KOH / g or more and 70 mg KOH / g or less.

3. The cationic electrodeposition coating composition according to claim 1, wherein the number average molecular weight of the resin (A1) is 800 or more and 3,000 or less.

4. The cationic electrodeposition coating composition according to claim 1, wherein the sum of the primary hydroxyl value and the phenolic hydroxyl value of the resin (A1) is 100 mg KOH / g or more and 250 mg KOH / g or less.

5. The cationic electrodeposition coating composition according to claim 1, wherein the number average molecular weight of the aralkyl-modified phenol resin (a1) is 500 or more and 2,000 or less, and the primary hydroxyl value of the aralkyl-modified phenol resin (a1) is 200 mg KOH / g or more and 400 mg KOH / g or less.

6. The cationic electrodeposition coating composition according to claim 1, wherein the aralkyl-modified phenol resin (a1) comprises a biphenylaralkyl-modified novolac-type phenol resin.

7. The cationic electrodeposition coating composition according to claim 1, wherein the epoxy equivalent of the epibis-type epoxy resin (a2) is 180 g / eq or more and 490 g / eq or less.

8. The cationic electrodeposition coating composition according to claim 1, wherein the epibis-type epoxy resin (a2) comprises a bisphenol A type epoxy resin.

9. The cationic electrodeposition coating composition according to claim 1, wherein the α,β-unsaturated carbonyl compound (B2) comprises a reaction product (B2-1) of an aralkyl-modified phenol resin (b2-1), an epihalohydrin compound (b2-2), and a monomer having an α,β-unsaturated carbonyl group (b2-3); or a bismaleimide resin (B2-2).

10. The process involves immersing an object to be coated in the cationic electrodeposition coating composition according to any one of claims 1 to 9, applying a voltage, and forming a deposited coating film, An electrodeposition coating method comprising drying and curing the deposited coating film to obtain an electrodeposited coating film.

Images