JP2013203966A - Cathodic electrodeposition coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathodic electrodeposition coating composition capable of obtaining a coating film excellent in weather resistance, adhesion, sensitivity to a base and corrosion resistance, and having 60 mirror glossiness of 30-70.SOLUTION: A cathodic electrodeposition coating composition includes: a base resin (A) which contains an amino group-containing epoxy resin (A1) and an amino group-containing acrylic resin (A2) at a ratio of solid mass of the resin (A1)/the resin (A2)=30/70 to 70/30; a blocked polyisocyanate curing agent (B); a specific pigment-dispersing paste (C); and a quaternary ammonium salt type epoxy resin (D), wherein the amount of blend of the quaternary ammonium salt type epoxy resin (D) is 0.1-10.0 pts.mass relative to the total solid content of 100 pts.mass of the base resin (A) and the blocked polyisocyanate curing agent (B).

Description

  The present invention relates to a cationic electrodeposition coating composition that is excellent in weather resistance, adhesion, base sensitivity, and corrosion resistance, and that provides a matte coating film having a 60 specular gloss of 30 to 70.

  Conventionally, cationic electrodeposition paints are widely used in automobile parts, electrical equipment parts, and other equipment because they can form a coating film excellent in weather resistance, corrosion resistance, and finish. Due to such characteristics of the cationic electrodeposition coating, its use as a product by one-time electrodeposition coating has increased, and a semi-glossy coating having weather resistance and corrosion resistance has been demanded for the cationic electrodeposition coating.

  In addition, the metal coating that has been subjected to chemical conversion treatment has a non-uniform coating appearance after electrodeposition coating and the smoothness of the coating surface is reduced due to the difference in electrical resistance in the chemical conversion treatment state of the metal coating. (So-called “reduction in substrate sensitivity”) may be a problem.

  Conventionally, as a cationic electrodeposition paint that can form a semi-gloss coating, it is obtained by adding block diisocyanate to an amine-modified epoxy cationic resin or a cationic acrylic resin having a solubility parameter at least 0.5 lower than that of an amine-modified epoxy cationic resin. A cationic electrodeposition coating composition containing a self-crosslinkable acrylic cationic resin and a blocked isocyanate curing agent is disclosed (Patent Document 1). However, the coating film obtained from the cationic electrodeposition coating composition described in Patent Document 1 has insufficient substrate sensitivity.

  Also, a pigment dispersion paste and a block in which an amine-modified epoxy resin and a cationic acrylic resin are blended at a solid weight ratio of 7/3 to 3/7, and pigment dispersed with a quaternary ammonium or sulfonium cation type epoxy pigment dispersing resin. A matte cationic electrodeposition coating composition obtained by dispersing a polyisocyanate crosslinking agent in an aqueous medium containing a neutralizing agent is disclosed (Patent Document 2). However, the coating film obtained from the cationic electrodeposition coating composition described in Patent Document 2 has insufficient base sensitivity, corrosion resistance, and adhesion.

  Furthermore, a method for forming a matte multilayer coating film using a cationic electrodeposition coating composition comprising a plurality of emulsions, each of which includes a plurality of emulsions selected from the plurality of emulsions, is disclosed. (Patent Document 3). However, the coating film obtained from the cationic electrodeposition coating composition described in Patent Document 3 has insufficient base sensitivity and 60-degree specular gloss.

  In addition, as an electrodeposition coating composition capable of forming such a semi-glossy coating film, the difference in solubility parameter between the cationic emulsion (A) and the cationic emulsion (B) is 0.5 to 1.5. In addition, an invention relating to a cationic electrodeposition coating composition having a low specular gloss and a good finish is disclosed by an emulsion having a difference in curing start temperature of 20 to 60 ° C. (Patent Document 4). However, the coating film obtained from the cationic electrodeposition coating composition described in Patent Document 4 has insufficient substrate sensitivity.

  From such a background, there is a need for a cationic electrodeposition coating composition that is excellent in weather resistance, adhesion, base sensitivity, and anticorrosion properties, and that can provide a matte coating film with a 60 specular gloss of 30 to 70. It was.

JP-A-8-333528 JP-A-9-87554 JP 2003-328192 A Japanese Patent Laid-Open No. 2006-2001

  The problem to be solved by the present invention is to provide a cationic electrodeposition coating composition that is excellent in weather resistance, adhesion, base sensitivity and anticorrosion properties, and can obtain a coating film having a 60-degree specular gloss of 30 to 70. That is.

As a result of intensive studies, the present inventors have conducted intensive studies in order to solve the above-mentioned problems. A2) = cationic electrodeposition containing a base resin (A) contained at a solid mass ratio of 30/70 to 70/30, a specific pigment dispersion paste (C), and a quaternary ammonium salt type epoxy resin (D) The inventors have found that this can be achieved by a coating composition, and have completed the present invention.

That is, the present invention
1. Base resin (A) containing amino group-containing epoxy resin (A1) and amino group-containing acrylic resin (A2) at a solid mass ratio of resin (A1) / resin (A2) = 30/70 to 70/30 A cationic electrodeposition coating composition comprising a blocked polyisocyanate curing agent (B), a pigment dispersion paste (C) having the following characteristics, and a quaternary ammonium salt type epoxy resin (D), wherein the quaternary ammonium salt type The cationic electrodeposition coating composition in which the amount of the epoxy resin (D) is 0.1 to 10.0 parts by mass with respect to 100 parts by mass in total of the solid content of the base resin (A) and the blocked polyisocyanate curing agent (B). Composition,
Pigment dispersion paste (C): an amine-added acid neutralized pigment dispersion resin (C1) obtained by reacting an epoxy resin (c1), an amine compound (c2) and a phenol compound (c3), and a pigment component 1. Pigment dispersion paste The cationic electrodeposition coating composition according to Item 1, wherein the pigment dispersion paste (C) is a pigment dispersion paste further comprising a hydroxyalkylimidazoline compound (C2) represented by the following formula (1):

Formula (1)
(In formula (1), R ¹ represents a hydrocarbon group having 6 to 32 carbon atoms, and R ² represents an alkylene group having 2 to 6 carbon atoms)
3. A coated article having a coating film obtained by electrodeposition-coating the cationic electrodeposition coating composition according to item 1 or 2 on a metal substrate and baking and drying the coating, wherein the coating film is 60 degrees according to JIS Z 8741 The present invention relates to a coated article characterized by having a specular glossiness in the range of 30 to 70.

  With the cationic electrodeposition coating composition of the present invention, it is possible to obtain a coating film having excellent weather resistance, adhesion, substrate sensitivity and anticorrosion properties, and a 60 ° specular gloss of 30 to 70.

  The present invention provides a substrate containing an amino group-containing epoxy resin (A1) and an amino group-containing acrylic resin (A2) at a solid mass ratio of resin (A1) / resin (A2) = 30/70 to 70/30. It is a cationic electrodeposition coating composition containing a resin (A), a blocked polyisocyanate curing agent (B), a specific pigment dispersion paste (C), and a quaternary ammonium salt type epoxy resin (D). Details will be described below.

[Substrate resin (A)]
The base resin (A) of the present invention comprises an amino group-containing epoxy resin (A1) and an amino group-containing acrylic resin (A2), resin (A1) / resin (A2) = 30/70 to 70/30, preferably 40 It is characterized by containing in the solid content mass ratio of / 60-60 / 40.

Amino group-containing epoxy resin (A1)
The amino group-containing epoxy resin (A1) is obtained by reacting an epoxy resin with an amine compound. The epoxy resin is particularly preferably an epoxy resin obtained by a reaction between a polyphenol compound and an epihalohydrin, for example, epichlorohydrin, from the viewpoint of the corrosion resistance of the coating film.

  A conventionally well-known thing can be used as a polyphenol compound which can be used for formation of this epoxy resin. Examples of such polyphenol compounds include bis (4-hydroxyphenyl) -2,2-propane (bisphenol A), 4,4-dihydroxybenzophenone, bis (4-hydroxyphenyl) methane (bisphenol F), bis (4 -Hydroxyphenyl) -1,1-ethane, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, bis (2-hydroxynaphthyl) ) Methane, tetra (4-hydroxyphenyl) -1,1,2,2-ethane, 4,4-dihydroxydiphenylsulfone (bisphenol S), phenol novolac, cresol novolac and the like. Moreover, bisphenol A obtained by reaction of a polyphenol compound and epichlorohydrin is suitable.

  The epoxy resin preferably has an epoxy equivalent of 150 to 2,300, more preferably 200 to 1,000, and a number average molecular weight of 320 to 3,000, particularly 350 to 1,500. What you have is suitable.

  Examples of such commercially available epoxy resins include those sold by Japan Epoxy Resins Co., Ltd. under the trade names jER828EL, jER1002, jER1004, and jER1007.

  The amine compound to be reacted with the epoxy resin is not particularly limited as long as it contains at least one active hydrogen that reacts with the epoxy group and can cationize the epoxy resin. It is preferable to use a secondary amine compound.

  Examples of the primary amine compound capable of introducing the primary amino group include monoethanolamine, propanolamine, hydroxyethylaminoethylenediamine, hydroxyethylaminopropylamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine. Examples include ketimine compounds.

  As the amine compound that can be used in combination with the primary amine, those conventionally used for cationization of epoxy resins can be used, but secondary amines are particularly preferred, and examples include diethylamine, diisopropylamine, diethanolamine, di (2-hydroxypropyl). ) Amine, monomethylaminoethanol, monoethylaminoethanol and the like. An amino group-containing epoxy resin (A1) can be obtained by reacting the epoxy resin with an amine compound by a known method.

  The amine value of the amino group-containing epoxy resin (A1) is preferably in the range of 30 to 70 mg KOH / g resin solid content, more preferably 40 to 60 mg KOH / g resin solid content or less. When the amine value exceeds 70 mg KOH / g resin solid content, the basicity of the resin increases, and thus the anticorrosion property decreases. On the other hand, when the amine value is less than 30 mg KOH / g resin solid content, the water dispersibility becomes poor and the coating stability is lowered.

Amino group-containing acrylic resin (A2)
The base resin (A) of the present invention is an amino group-containing acrylic resin comprising the amino group-containing epoxy resin (A1) having excellent anticorrosion properties and an acrylic resin having excellent weather resistance and an amino group of a water-dispersing group. (A2) is used in combination.

  The acrylic resin is obtained by radical copolymerization of a hydroxyl group-containing acrylic monomer, an amino group-containing acrylic monomer and other monomers as monomer components constituting the acrylic resin.

  Examples of hydroxyl group-containing acrylic monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and addition of 2-hydroxyethyl (meth) acrylate and caprolactone. (For example, Plaxel FA-2 and FM-3 as trade names manufactured by Daicel Corporation) and the like. These can be used alone or in combination of two or more.

  Examples of amino group-containing acrylic monomers include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and N, N-di. -T-butylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, etc. are mentioned.

  Examples of other monomers include aromatic vinyl monomers such as styrene, vinyl toluene, and α-methyl styrene, such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, Examples include n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. The acrylic resin can be obtained by subjecting the above monomers to radical copolymerization by a known method.

The hydroxyl value of the acrylic resin is usually in the range of 10 to 300 mgKOH / g, preferably 50 to 200 mgKOH / g, and the number average molecular weight is in the range of 2,000 to 100,000, preferably 3,000 to 50. A range of 1,000 is suitable.
Moreover, the amine compound containing active hydrogen can be added to the glycidyl group of the copolymer of the radically polymerizable unsaturated monomer containing glycidyl (meth) acrylate to impart water dispersibility to the acrylic resin. Examples of the amine compound include primary mono- and polyamines, secondary mono- and polyamines, or primary and secondary mixed polyamines, secondary mono- and polyamines having a ketiminated primary amino group, and ketiminated primary. Examples thereof include hydroxy compounds having an amino group. Specifically, diethylamine, diethanolamine, a ketimine product of diethyltriamine, and the like are preferably used.

Blocked polyisocyanate curing agent (B)
The blocked polyisocyanate curing agent (B) can be used regardless of its structure, and examples of the polyisocyanate compound used herein include aromatic, alicyclic or aliphatic polyisocyanate compounds. One kind or a mixture of two or more kinds can be used.

  Specific examples of the aromatic polyisocyanate include 1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate (TDI), crude TDI, 2,4′- And / or 4,4′-diphenylmethane diisocyanate (MDI), 4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4, Examples include 4'-diisocyanatodiphenylmethane, crude MDI, 1,5-naphthylene diisocyanate, 4,4 ', 4 "-triphenylmethane triisocyanate, m- and p-isocyanatophenylsulfonyl isocyanate.

  Aliphatic polyisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2 , 6-diisocyanatomethylcaproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate, etc. Moreover, p-xylylene diisocyanate (XDI), α, α, α ′, α′-tetramethylxylylene diisocyanate (TMXDI), and the like can also be used. Examples of the alicyclic polyisocyanate include isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI), and cyclohexylene diisocyanate. In order to achieve both corrosion resistance and weather resistance, the block polyisocyanate curing agent (B) is preferably an aliphatic polyisocyanate or an alicyclic polyisocyanate.

  The blocking agent is to block by adding to the isocyanate group of the polyisocyanate compound, and the blocked polyisocyanate compound produced by the addition of the blocking agent is stable at ordinary temperature and at a general electrodeposition coating baking temperature. It is desirable that the isocyanate group can be regenerated by dissociating the blocking agent when heated from about 100 ° C. to 200 ° C.

Examples of the blocking agent satisfying such requirements include lactam compounds such as ε-caprolactam and γ-butyrolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol compounds such as phenol, para-t-butylphenol and cresol. Aliphatic alcohols such as n-butanol and 2-ethylhexanol; aromatic alkyl alcohols such as phenyl carbinol and methyl phenyl carbinol; ether alcohol compounds such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether; propylene glycol; Dipropylene glycol, 1,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol 1,4-pentanediol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,5- Mention may be made of alcohol compounds containing secondary and tertiary hydroxyl groups such as hexanediol, 1,4-hexanediol, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, dimethylolvaleric acid and glyceric acid.
Particularly preferable block polyisocyanates among these include isophorone diisocyanate and hexamethylene diisocyanate triisocyanurate blocked with methyl ethyl ketoxime.

  In the resin component containing at least two types of base resin (A) of the amine-added epoxy resin (A1), amine-added acrylic resin (A2), and blocked isocyanate curing agent (B) described above, A resin emulsion can be obtained by adding a compatibilizer and further dispersing in water with deionized water.

  By adding the pigment dispersion paste (C) described below to this resin emulsion, the cationic electrodeposition coating composition of the present invention can be obtained.

[Pigment dispersion paste (C)]
The pigment dispersion paste (C) used for the production of the cationic electrodeposition coating composition of the present invention,
An amine-added acid neutralized pigment dispersion resin (C1) and a pigment dispersion paste containing a pigment component.

Amine-added acid neutralized pigment dispersion resin (C1)
The amine-added acid neutralized pigment dispersion resin (C1) is a pigment dispersion resin obtained by reacting an epoxy resin (c1) with an amine compound (c2) and a phenol compound (c3). By using the amine-added acid neutralized pigment dispersion resin (C1), a coating film having excellent anticorrosion properties can be obtained.

As the epoxy resin (c1), an epoxy resin that can be used for the base resin (A) can be used. From the viewpoint of anticorrosiveness of the coating film, the epoxy resin (c1) can be obtained by reacting a polyphenol compound with an epihalohydrin such as epichlorohydrin. Epoxy resins are preferred.
Specifically, bisphenol-type epoxy resin, phenol-type novolac epoxy resin, cresol-type novolac epoxy resin, bromo-modified phenol-type novolac epoxy resin, long-chain alkyl-modified phenol-type novolac epoxy resin, epoxy group represented by the following formula (2) An alicyclic epoxy resin having at least three functional groups in one molecule can be used.

Formula (2)
As a commercial item of the said bisphenol type | mold epoxy resin, what is marketed by the brand name called jER828EL, jER1002, jER1004, jER1007 from Japan Epoxy Resin Co., Ltd. is mentioned, for example.

  Moreover, as a commercial item of a phenol type novolak epoxy resin, DEN-438 and DEN-439 (above, Dow Chemical Japan Co., Ltd. make, brand name) are mentioned, for example. Examples of commercially available cresol type novolac epoxy resins include EPICRON N-695 (manufactured by Dainippon Ink Co., Ltd., trade name), CNE195LB (manufactured by Changchun Japan Co., Ltd.), EOCN-102S, EOCN-1020, EOCN104S (and above Nippon Kayaku Co., Ltd., trade name). BREN-S (trade name, manufactured by Nippon Kayaku Co., Ltd.) can be mentioned as a commercial product of a bromo-modified phenol type novolac epoxy resin. ESMB-260 (trade name, manufactured by Sumitomo Chemical Co., Ltd.) and the like are exemplified as the polyglycidyl etherified product of the long-chain alkyl-modified phenol type novolak resin. Moreover, as a commercial item of the said alicyclic epoxy resin, EHPE-3150 (The Daicel Chemical Industries Ltd. make, brand name, epoxy equivalent 180) is mentioned, for example.

  Examples of the amine compound (c2) include ketiminates such as monoethanolamine, propanolamine, hydroxyethylaminoethylenediamine, hydroxyethylaminopropylamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine. Moreover, diethylamine, diisopropylamine, diethylaminopropylamine, diethanolamine, di (2-hydroxypropyl) amine, monomethylaminoethanol, monoethylaminoethanol and the like can be mentioned.

Examples of the phenol compound (c3) include bisphenol A ([bis (4-hydroxyphenyl) -2,2-propane]), bisphenol F ([bis (4-hydroxyphenyl) -2,2-methane]) and these A polyaddition product of diglycidyl ether of bisphenol and bisphenol is preferable. Of these phenolic compounds, those having a number average molecular weight of at least 300, preferably in the range of about 320 to about 1,000 are suitable.
In addition, amine addition acid neutralization type pigment dispersion resin (C1) is epoxy resin (c1), amine compound (c2), and phenol compound (c3), for example, reaction temperature 50-300 degreeC, Preferably it is 70-200 degreeC. For 30 minutes to 10 hours, preferably 1 to 6 hours.

Specific examples of the pigment component include color pigments, extender pigments, and rust preventive pigments. Examples of the color pigment include titanium white, carbon black, red pepper, yellow iron oxide (ocher), copper phthalocyanine blue, copper phthalocyanine green, and the like. Examples of extender pigments include clay (kaolin), talc, calcium carbonate, barium sulfate, silica, diatomaceous earth, and magnesium carbonate. As the rust preventive pigment, organic tin compounds such as aluminum phosphomolybdate, aluminum tripolyphosphate, zinc oxide, bismuth oxide, bismuth hydroxide, dibutyltin oxide, and dioctyltin oxide can be appropriately used.
Moreover, the pigment dispersion paste (C) used for this invention can contain the hydroxyalkyl imidazoline compound (C2) represented by following formula (1) as needed.

Formula (1)
(In formula (1), R ¹ represents a hydrocarbon group having 6 to 32 carbon atoms, and R ² represents an alkylene group having 2 to 6 carbon atoms)
The compounding amount of the hydroxyalkyl imidazoline compound (C2) is 100 parts by mass or less, preferably 5 to 30 parts by mass of the hydroxyalkyl imidazoline compound (C2) per 100 parts by mass of the solid content of the pigment dispersion resin (C1). With the hydroxyalkyl imidazoline compound (C2), the substrate sensitivity can be improved.

  In addition, as said pigment component, the kind and usage-amount of a pigment are adjusted according to the target coating-film performance, a pigment component, an amine addition acid neutralization type pigment dispersion resin (C1), water, as needed Then, a surfactant and a hydroxyalkyl imidazoline compound (C2) are added, and the mixture is sufficiently stirred with a stirrer or dispersed using a ball mill, a sand mill, or the like to obtain a pigment dispersion paste (C).

  The compounding amount of the pigment component is usually 0.1 to 1200 parts by mass, preferably 20 to 800 parts by mass, per 100 parts by mass of the solid content of the amine-added acid neutralized pigment dispersion resin (C1). It is preferable for finishing and painting workability. The compounding amount of the amine-added acid neutralized pigment dispersion resin (C1) in the cationic electrodeposition coating composition is based on a total solid content of 100 parts by mass of the base resin (A) and the blocked polyisocyanate curing agent (B). Thus, 0.1 to 30 parts by mass, preferably 0.5 to 10 parts by mass is desirable for improving the base sensitivity and corrosion resistance.

Quaternary ammonium salt type epoxy resin (D)
The quaternary ammonium salt type epoxy resin (D) is a salt obtained by adding an acid to an amine compound to an epoxy resin, preferably a salt obtained by adding an acid to a tertiary amine compound to an epoxy resin (hereinafter referred to as “amine- An epoxy resin having a quaternary ammonium base can be obtained by reacting an acid addition salt). Examples of preferable amine compounds include dimethylethanolamine, triethylamine, trimethylamine, triisopropanolamine and the like.

The epoxy resin preferably has an epoxy equivalent of 150 to 2,300, more preferably 200 to 1,000, and a number average molecular weight of 320 to 3,000, particularly 350 to 1,500. What you have is suitable.
Examples of such commercially available epoxy resins include those sold by Japan Epoxy Resins Co., Ltd. under the trade names jER828EL, jER1002, jER1004, and jER1007.

  The reaction between the epoxy resin and the “amine-acid addition salt” is 1 to 50 parts by weight, preferably 5 to 40 parts by weight of the “amine-acid addition salt” with respect to 100 parts by weight of the epoxy resin, and is suitable for the organic solvent. A quaternary ammonium salt type epoxy resin (D) can be obtained at a reaction temperature of 60 to 100 ° C. by adding a catalyst.

  The obtained quaternary ammonium salt type epoxy resin (D) is dispersed in water and blended in an electrodeposition coating bath, but an acid is added as necessary to obtain good water dispersibility and electrodeposition characteristics. Examples of preferred acids that may be added include boric acid, lactic acid, acetic acid, formic acid, propionic acid, butyric acid, and phosphoric acid. Among these, lactic acid and acetic acid are preferable. The quaternary ammonium salt value of the quaternary ammonium salt type epoxy resin (D) is 10 to 90 mgKOH / g, and preferably 30 to 70 mgKOH / g for improving the substrate sensitivity and the anticorrosion property.

  Since the quaternary ammonium salt type epoxy resin (D) in the cationic electrodeposition coating composition of the present invention can provide a film deposition adjusting function at the time of electrodeposition coating, even if the surface of the object to be coated is uneven, A coating film excellent in sensitivity can be obtained. The blending amount of the quaternary ammonium salt type epoxy resin (D) in the cationic electrodeposition coating composition is based on the total solid content of 100 parts by mass of the base resin (A) and the blocked polyisocyanate curing agent (B). 0.1 to 10 parts by mass, preferably 0.2 to 5.0 parts by mass, and more preferably 0.3 to 3.0 parts by mass improves the base sensitivity and improves the 60 degree specular gloss. Desirable to adjust to ~ 70.

[Cationic electrodeposition coating composition]
An example of a method for obtaining the cationic electrodeposition coating composition of the present invention will be described below. A step of adding the base resin (A), the blocked polyisocyanate curing agent (B) and the neutralizing agent and dispersing in water to produce an emulsion. A step of producing a pigment dispersion paste (C) by dispersing a pigment component and, if necessary, a hydroxyalkylimidazoline compound (C2) in the presence of an amine-added acid neutralized pigment dispersion resin (C1).

The emulsion obtained by the above process, the pigment dispersion paste (C) and the quaternary ammonium salt type epoxy resin (D) are blended, and deionized water and acid are added to adjust the solid content and pH of the cationic electrodeposition coating composition. The cationic electrodeposition coating composition of the present invention can be obtained through the steps. The order of these steps can be adjusted as necessary.
In addition, as the neutralizing agent used for neutralizing the emulsion, organic carboxylic acids are used, and acetic acid, formic acid and lactic acid or a mixture thereof are suitable, and the stability of the coating formed by using these acids is improved. To do.

  The cationic electrodeposition coating composition of the present invention can be applied to a desired substrate surface by cationic electrodeposition coating. The electrodeposition coating is generally diluted with deionized water or the like so that the solid content concentration is about 5 to 40% by mass, preferably 15 to 25% by mass, and the pH is in the range of 5.5 to 9.0. The electrodeposition bath composed of the cationic electrodeposition coating composition of the present invention adjusted in the inside can be usually adjusted to a bath temperature of 15 to 35 ° C. under a load voltage of 100 to 400V.

  The film thickness of the cationic electrodeposition coating film is not particularly limited, but in general, it is preferably in the range of 10 to 40 μm, particularly 15 to 35 μm based on the cured coating film. The baking temperature of the coating film is generally about 120 to about 200 ° C., preferably about 140 to about 180 ° C. on the surface of the object, and the baking time is 5 to 60 minutes, preferably It can be 10-30 minutes.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited in any way by the following examples. Hereinafter, both “parts” and “%” are based on mass.

Production example of base resin (A) Production example 1 Production example of amino group-containing epoxy resin PP-400 (manufactured by Sanyo Chemical Co., Ltd., trade name, polypropylene glycol molecular weight 400) is added to 300 parts of ε-caprolactone. In addition, the temperature was raised to 130 ° C. Thereafter, 0.01 part of tetrabutoxy titanium was added and the temperature was raised to 170 ° C. Sampling was carried out over time while maintaining this temperature, the amount of unreacted ε-caprolactone was monitored by infrared absorption spectrum measurement, and the mixture was cooled when the reaction rate reached 98% or more to obtain modifier 1.
Next, jER828EL (trade name, epoxy resin, epoxy equivalent 190, number average molecular weight 350) 1000 parts, 400 parts of bisphenol A and 0.2 parts of dimethylbenzylamine and 0.2 parts of dimethylbenzylamine are added to another flask at 130 ° C. The reaction was continued until the epoxy equivalent was 750. Next, 200 parts of modifier 1, 140 parts of diethanolamine and 65 parts of diethylenetriamine ketiminate were added and reacted at 120 ° C. for 4 hours. The solid content was adjusted with ethylene glycol monobutyl ether, and the resin solid content was 70%. A polyol-modified amino group-containing epoxy resin solution was obtained. The resin solid content of the amino group-containing epoxy resin was an amine value of 56 mg KOH / g resin solid content and a number average molecular weight of 2,100.

Production Example 2 Production Example of Amino Group-Containing Acrylic Resin 246 parts of propylene glycol monomethyl ether was charged into a 2-liter four-necked flask and purged with nitrogen, and kept at 110 ° C. In this, the mixture shown below was dripped over 3 hours.
Styrene 240 parts n-butyl acrylate 160 parts methyl methacrylate 80 parts 2-hydroxyethyl methacrylate 240 parts glycidyl methacrylate 80 parts diethylamine 40 parts 2,2'-azobis (2-methylbutyronitrile) 40 parts 1 hour has elapsed since the completion of the dropping Thereafter, a solution obtained by dissolving 5 parts of 2,2′-azobis (2-methylbutyronitrile) in 56 parts of propylene glycol monomethyl ether was dropped into the solution over 1 hour. After completion of dropping, this was further maintained at 110 ° C. for 1 hour, and then adjusted with methyl isobutyl ketone to obtain an amino group-containing acrylic resin solution having a solid content of 70%. The resin solid content of the amino group-containing acrylic resin was a hydroxyl value of 120 mgKOH / g, an amine value of 35 mgKOH / g, and a number average molecular weight of 10,000.

Production of blocked polyisocyanate curing agent (B) Production Example 3 Curing Agent No. Production Example of One Solution In a reaction vessel, 168 parts of hexamethylene diisocyanate and 174 parts of methyl ethyl ketoxime were added and heated to 70 ° C. Sampling was carried out over time, and it was confirmed by absorption of unreacted isocyanate groups by infrared absorption spectrum measurement. The resin solid content was adjusted with ethylene glycol monobutyl ether. One solution was obtained.

Production Example 4 Curing Agent No. 2 Solution Production Example In a reaction vessel, 270 parts of Cosmonate M-200 (trade name, manufactured by Mitsui Chemicals, Crude MDI) and 127 parts of methyl isobutyl ketone were added and heated to 70 ° C. In this, 236 parts of ethylene glycol monobutyl ether was added dropwise over 1 hour, then heated to 100 ° C., sampled over time while maintaining this temperature, and unreacted isocyanate group was measured by infrared absorption spectrum measurement. It was confirmed that the absorption of the curing agent No. with a resin solid content of 90% was confirmed. Two solutions were obtained.

Production of pigment dispersion resin (C) Production Example 5 Pigment dispersion resin No. Example of 1 solution production (amine-added acid neutralized resin)
Into a flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser, 450 parts of nonylphenol and 960 parts of CNE195LB (Note 2) are charged, gradually heated with mixing and stirring, and reacted at 160 ° C. Thereafter, 430 parts of ε-caprolactone was charged, and the temperature was raised to 170 ° C. for reaction. Further, 105 parts of diethanolamine and 124 parts of N-methylethanolamine were reacted to confirm that the epoxy value was 0, and the solid content was adjusted by adding ethylene glycol monobutyl ether to obtain a pigment-dispersed resin having a solid content of 60%. No. One solution was obtained. This pigment dispersion resin No. The resin solid content of No. 1 had an amine value of 70 mgKOH / g and a number average molecular weight of 2,200.
(Note 2) CNE195LB: Changchun Japan Co., Ltd., trade name, cresol type novolac epoxy resin, glycidyl etherified product of novolac type phenol resin.

Production Example 6 Pigment Dispersion Resin No. Example of 2 solution production (amine addition acid neutralized resin)
In a flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser, 398 parts of ethylene glycol monobutyl ether, 900 parts of EHPE-3150 (manufactured by Daicel Chemical Industries, Ltd., trade name, alicyclic epoxy resin having an epoxy equivalent of 180) , 315 parts of diethanolamine, 371 parts of amine compound (Note 3) and 1651 parts of epoxyamine product (Note 4) were gradually heated with mixing and stirring, and reacted at 150 ° C., resulting in an epoxy equivalent of 0. The solid content was adjusted by adding ethylene glycol monobutyl ether, and pigment dispersion resin No. 60 having a solid content of 60% was prepared. Two solutions were obtained. Pigment dispersion resin no. The resin solid content of No. 2 was an amine value of 96.5 mgKOH / g and a number average molecular weight of 2,000.

  (Note 3) Amine compound: 285 parts of stearic acid, 104 parts of hydroxylethylaminoethylamine and 80 parts of toluene are charged into a reaction vessel equipped with a thermometer, stirrer, reflux condenser and water separator, and gradually mixed and stirred. An amine compound having an amine value of 150 and a freezing point of 76 ° C. obtained by removing 18 parts of the reaction water while removing the toluene and increasing the temperature as necessary, and then removing the remaining toluene under reduced pressure.

  (Note 4) Epoxyamine product: 105 parts of diethanolamine, 760 parts of bisphenol A diglycidyl ether having an epoxy equivalent of 190, 456 parts of bisphenol A and ethylene glycol in a flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser. An epoxyamine product having a solid content of 80% obtained by adding 330 parts of monobutyl ether and reacting at 150 ° C. until the remaining amount of epoxy groups becomes zero.

Production of quaternary ammonium salt type epoxy resin (D) Production Example 7 Quaternary ammonium salt type epoxy resin No. 4 1 Production Example jER828EL (trade name, epoxy resin, manufactured by Japan Epoxy Resin Co., Ltd.) 1010 parts, 390 parts of bisphenol A, 240 parts of polycaprolactone diol (number average molecular weight of about 1,200) and 0.2 part of dimethylbenzylamine In addition, the reaction was continued at 130 ° C. until the epoxy equivalent reached about 1,090.
Next, 134 parts of dimethylethanolamine and 135 parts of lactic acid were added and reacted at 120 ° C. for 4 hours. Then, ethylene glycol monobutyl ether was added to adjust the solid content, and a quaternary ammonium salt type epoxy having a resin solid content of 10%. Resin No. One solution was obtained. This quaternary ammonium salt type epoxy resin No. The resin solid content of No. 1 was a quaternary ammonium salt value of 44 mg KOH / g and a number average molecular weight of 3,000.

Production Example 8 Quaternary ammonium salt type epoxy resin no. Production Example 2 of jER828EL (trade name, epoxy resin, manufactured by Japan Epoxy Resins Co., Ltd.), 1,260 parts of bisphenol A, 240 parts of polycaprolactone diol (number average molecular weight of about 1,200) and dimethylbenzylamine 0.2 parts were added and reacted at 130 ° C. until the epoxy equivalent was about 1,090.
Next, 134 parts of dimethylethanolamine and 135 parts of lactic acid were added and reacted at 120 ° C. for 4 hours. Then, ethylene glycol monobutyl ether was added to adjust the solid content, and a quaternary ammonium salt type epoxy having a resin solid content of 10%. Resin No. Two solutions were obtained. This quaternary ammonium salt type epoxy resin No. The resin solid content of No. 2 was a quaternary ammonium salt value of 20 mg KOH / g and a number average molecular weight of 3,100.

Production Example 9 Quaternary ammonium salt type epoxy resin no. 3 Production Example jER828EL (trade name, epoxy resin, manufactured by Japan Epoxy Resin Co., Ltd.) 480 parts, bisphenol A 60 parts, polycaprolactone diol (number average molecular weight about 1,200) 240 parts and dimethylbenzylamine 0.2 parts In addition, the reaction was continued at 130 ° C. until the epoxy equivalent reached about 1,090.
Next, 134 parts of dimethylethanolamine and 135 parts of lactic acid were added and reacted at 120 ° C. for 4 hours. Then, ethylene glycol monobutyl ether was added to adjust the solid content, and a quaternary ammonium salt type epoxy having a resin solid content of 10%. Resin No. Three solutions were obtained. This quaternary ammonium salt type epoxy resin No. The resin solid content of No. 3 was a quaternary ammonium salt value of 84 mg KOH / g and a number average molecular weight of 2,900.

Production Example 10 Emulsion No. Production of 1 95.7 parts (67 parts solids) of the 70% amino group-containing epoxy resin obtained in Production Example 1 and 7.1% of the 70% amino group-containing acrylic resin obtained in Production Example 2 Part (solid content 5 parts), curing agent No. obtained in Production Example 3. 1 in 17.8 parts (solid content 16 parts), the curing agent No. 1 obtained in Production Example 4. 2 was mixed with 13.3 parts (solid content 12 parts), 11.5 parts of 10% formic acid, and stirred uniformly, and then dropped over about 15 minutes while vigorously stirring 167.1 parts of deionized water, Emulsion No. 33% solids 1 was obtained.

Production Examples 11 to 19 Emulsion No. 2-No. No. 10 Emulsion No. 10 having the composition shown in Table 1 was prepared in the same manner as in Production Example 10. 2-No. 10 was obtained.

[Production of pigment dispersion paste (C)]
Production Example 20 Pigment Dispersion Paste No. Production Example 1 Pigment Dispersion Resin No. 60 having a solid content of 60% obtained in Production Example 7 was prepared. 1 is 8.3 parts (solid content 5 parts), 10% acetic acid 3.8 parts, JR-600E (note 6) 34 parts, SIPARNAT FPS-5 (note 7) 1 part, bismuth hydroxide 1.5 parts, Blend 1 part aluminum dihydrogen tripolyphosphate, 2 parts dioctyltin oxide and 22.6 parts deionized water, disperse in a ball mill for 20 hours, add 37.9 parts deionized water, and add 50% solids pigment Dispersion paste No. 1 was obtained.
(Note 6) JR-600E: manufactured by Teika, trade name, rutile titanium dioxide (Note 7) SIPARNAT FPS-5: DSL. Product name, hydrous silicon dioxide, manufactured by Japan.

Production Examples 21 to 23 Pigment dispersion paste No. 2-No. Production Example 4 No. 4 pigment dispersion paste No. 4 in the same manner as in Production Example 20 except that the contents of Table 2 are used. 2-No. 4 was obtained.

(Note 5) Hartle M33: Harima Chemicals, trade name, 2-alkyl-1hydroxy-2imidazoline.

Example 1 Cationic Electrodeposition Paint No. No. 1 Production Preparation Example 10 emulsion No. 32 having a solid content of 32% was obtained. 3 to 312.5 parts (solid content 100 parts), the pigment dispersion paste No. 3 having a solid content of 50% obtained in Production Example 20 was prepared. No. 1 is 89 parts (44.5 parts), 10% solid content quaternary ammonium salt type epoxy resin No. 1 No. 1 was blended with 15 parts (1.5 parts solids), and 313.5 parts deionized water was added thereto to give a cationic electrodeposition paint no. 1 was obtained.

Examples 2 to 15 Cationic electrodeposition paint No. 2-No. 15 Production Examples In combination as shown in Table 3, cationic electrodeposition paint No. 2-No. 15 was created.

Comparative Examples 1-9 Cationic electrodeposition paint No. 16-No. 24 Production Examples In combination as shown in Table 4, cationic electrodeposition paint No. 16-No. 24 was created.

Preparation of test plate Using each of the cationic electrodeposition paints obtained in the above examples and comparative examples, the dry film thickness is 20 μm on a cold-rolled steel plate (0.8 mm × 70 mm × 150 mm) subjected to zinc phosphate treatment. Thus, electrodeposition coating was applied, and baking was performed at 170 ° C. for 20 minutes to prepare a test plate, which was tested according to the following test method. The results are shown in Tables 5-6.

(Note 8) 60 degree specular gloss:
According to the 60 degree specular gloss of JIS Z 8741 (1997), the reflectivity when the incident angle and the light receiving angle are 60 degrees is measured to determine the initial gloss level of the coating film. Expressed as a percentage when the glossiness of the reference surface is 100.

(Note 9) Weather resistance:
An accelerated weathering test using a sunshine carbon arc lamp method specified in JIS B7753 (2007) was conducted, and the 60-degree specular gloss (see note 12) of the coating film at 200 hours of irradiation was measured. The gloss retention (%) relative to the specular gloss value was measured.
◎: The gloss retention of the coating film at an irradiation time of 200 hours exceeds 70%. ○: The gloss retention of the coating film at an irradiation time of 200 hours exceeds 50% and is 70% or less. The gloss retention of the coating film at 30% is more than 30% and 50% or less. ×: The gloss retention of the coating film at an irradiation time of 200 hours is 30% or less.

(Note 10) Adhesion:
A cross-cut reaching the substrate with a cutter knife was put on the coating film of each test plate soaked at 40 ° C. for 240 hours, and an adhesive tape was attached to the cross-cut portion to instantly peel off.
◎: no peeling from the cut part ○: peeling from the cut part but less than 0.5 mm (one side)
Δ: peeling from the cut part is 0.5 mm or more and less than 2 mm (one side)
X: peeling from the cut part is 2 mm or more (one side).

(Note 11) Substrate sensitivity: The left half (0.8 mm × 35 mm × 150 mm) of a cold rolled steel sheet (0.8 mm × 70 mm × 150 mm) subjected to zinc phosphate treatment was sharpened with sandpaper (# 400). Using each of the cationic electrodeposition paints obtained in Examples and Comparative Examples, the electrodeposition coating was applied so that the dry film thickness was 20 μm, and the coating film was washed with water and then baked and dried at 170 ° C. for 20 minutes. The appearance of the left and right halves of the membrane was observed.
◎ is good because there is no difference in appearance between the left half coating film and the right half coating film.
○ is slightly different in appearance between the left half coating film and the right half coating film, but can be concealed by the intermediate coating film.
[Delta] is slightly different in appearance between the half coating film and the right half coating film, and cannot be concealed by the intermediate coating film, but can be concealed by recoating the top coating film on the intermediate coating film.
In x, there is a considerable difference in appearance between the half coating film and the right half coating film, and even if the intermediate coating film and the top coating film are applied repeatedly, they cannot be concealed.

(Note 12) Anticorrosion:
The electrodeposition coating film was cross-cut with a knife so as to reach the base of the test plate, and a salt spray resistance test was conducted for 840 hours according to JIS Z-2371. The evaluation was made according to the following criteria based on the rust and blister width from the knife scratch.
◎: The maximum width of rust and blisters is less than 2mm from the cut part (one side)
○: The maximum width of rust and blisters is 2 mm or more and less than 3 mm (one side) from the cut part.
△ indicates the maximum width of rust and blisters is 3mm or more and less than 4mm (one side) from the cut part.
X is rust, the maximum width of blisters is 4mm or more (one side) from the cut part,

It is possible to provide a coated article having a coating film having excellent weather resistance, adhesion, substrate sensitivity and anticorrosion properties, and a 60 specular gloss of 30 to 70.

Claims (3)

Base resin (A) containing amino group-containing epoxy resin (A1) and amino group-containing acrylic resin (A2) at a solid mass ratio of resin (A1) / resin (A2) = 30/70 to 70/30 A cationic electrodeposition coating composition comprising a blocked polyisocyanate curing agent (B), a pigment dispersion paste (C) having the following characteristics, and a quaternary ammonium salt type epoxy resin (D), wherein the quaternary ammonium salt type The cationic electrodeposition coating composition in which the amount of the epoxy resin (D) is 0.1 to 10.0 parts by mass with respect to 100 parts by mass in total of the solid content of the base resin (A) and the blocked polyisocyanate curing agent (B). Composition.
Pigment dispersion paste (C): an amine-added acid neutralized pigment dispersion resin (C1) obtained by reacting an epoxy resin (c1), an amine compound (c2) and a phenol compound (c3), and a pigment component Pigment dispersion paste The cationic electrodeposition coating composition according to claim 1, wherein the pigment dispersion paste (C) is a pigment dispersion paste further comprising a hydroxyalkyl imidazoline compound (C2) represented by the following formula (1).

Formula (1)
(In formula (1), R ¹ represents a hydrocarbon group having 6 to 32 carbon atoms, and R ² represents an alkylene group having 2 to 6 carbon atoms) A coated article having a coating film obtained by electrodeposition-coating the cationic electrodeposition coating composition according to claim 1 or 2 on a metal substrate and baking and drying the coating, wherein the coating film is 60 degrees according to JIS Z 8741 A coated article having a specular glossiness in the range of 30 to 70.