JP2002249702A - Electrodeposition paint composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrodeposition paint composition excellent in storage stability and weather resistance of the paint film. SOLUTION: This electrodeposition paint composition includes a) 10-70 wt.% of an acrylic resin having a carboxyl group and a hydroxyl group, b) 10-70 wt.% of a difluoro type fluororesin having carboxyl group manifesting an acid value of 10-100 mgKOH/g and hydroxyl group manifesting 50-200 mgKOH/g of hydroxyl value and c) 20-50 wt.% of at least one kind of an amino resin and a block isocyanate resin (with the proviso that sum of the a), b) and c) is 100 wt.%), and the acid value of the difluoro type fluororesin is 20-50% of the acid value of the acrylic resin. A matt electrodeposition paint composition including the prescribed composition and 0.5-5.0 wt.% of a metal chelate compound including a long chain β-keto ester having 6-30C alkyl ester group or further including a β-diketone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing
Matting and non-matting electrodeposition coating compositions.

[0002]

2. Description of the Related Art In order to improve the weather resistance of a coating film of an electrodeposition paint, a technique of blending a fluororesin as one of the paint components is known. For example, JP-A-11-256080, JP-A-62-59676, JP-A-62-156
No. 170, JP-A-62-179575, JP-A-1-32266, and the like. However, these prior arts are all trifluorinated resins. But,
Fluororesins generally have insufficient affinity with the acrylic resin used as the main component of the electrodeposition paint, and if such a trifluoride-type fluororesin is excessively blended, the storage stability of the paint decreases. In addition, there is a problem that the curability is impaired due to uneven dispersion of the fluororesin. Also, when a difluorinated fluororesin is used, both components may be separated due to the relationship with the acrylic resin used in combination. Therefore, in the conventional technology, the compounding amount of the fluororesin is
About 20% by weight of the total solids in the coating was the limit in terms of storage stability. However, when the content of the fluororesin was 20% by weight or less, the weather resistance of the obtained coating film was not sufficient.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrodeposition coating composition having good storage stability as a coating and having excellent weather resistance of a coating film.

[0004]

According to the present invention, there is provided a) an acrylic resin having a carboxyl group and a hydroxyl group.
-70% by weight (solid content basis, the same applies hereinafter), b) acid value is 1
Difluorinated fluororesin 1 having a carboxyl group in an amount of 0 to 100 mgKOH / g and a hydroxyl group in an amount of 50 to 200 mgKOH / g
0 to 70% by weight, and c) 20 to 50% by weight of at least one of the amino resin and the blocked isocyanate resin, provided that the total of a) + b) + c) is 100% by weight) and b) The present invention relates to an electrodeposition coating composition wherein the acid value of the difluorinated fluororesin is 20% to 50% of the acid value of the acrylic resin of a). The present invention also provides the above electrodeposition coating composition, wherein the hydroxyl value of the difluorinated fluororesin of b) is 70% to 150% of the hydroxyl value of the acrylic resin of a). About. The present invention also provides a metal chelate compound containing a long-chain β-ketoester having an alkyl ester group having 6 to 30 carbon atoms, or a metal chelate compound having an alkyl ester group having 6 to 30 carbon atoms. Chain β-ketoester and β-
0.5 to 5.0 metal chelate compounds containing diketones
It relates to an electrodeposition coating composition as described above, further comprising in an amount of% by weight.
The electrodeposition coating composition containing the metal chelate compound is a mat type.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The electrodeposition coating composition of the present invention has a carboxyl group and a hydroxyl value of 50 to 200 mgKOH / g in such an amount that the acid value becomes 10 to 100 mgKOH / g.
It is characterized in that it contains 10 to 70% by weight of a difluorinated fluororesin having an hydroxyl group. In the present invention, the term “difluorinated fluororesin” refers to a main chain carbon atom of 2 on average to the carbon chain forming the main chain of the fluororesin.
A type with two fluorine atoms per unit. In the present invention, the acid value refers to the value of potassium hydroxide required to neutralize the carboxyl group contained in 1 g of the fluororesin.
The g number. The hydroxyl value is defined as the fluorine resin 1
It means the number of mg of potassium hydroxide required to neutralize acetic acid required to acetylate g.

[0006] The fluororesin used in the present invention is preferably a resin containing a carboxyl group and a hydroxyl group in the molecule and being dissolved in water or stably dispersed in water by neutralization with a neutralizing agent. The above fluororesin has an acid value of 10 to 10.
0 mgKOH / g, preferably 10-80 mgKOH / g
g. If the acid value is smaller than this range, the water dispersibility of the coating tends to decrease, and if it is larger, the water resistance and the like of the coating film tend to deteriorate. The hydroxyl number is 50
~ 200mgKOH / g, preferably 100 ~ 180m
gKOH / g. Hydroxyl value is 50mgKOH
If it is less than / g, the curing reaction does not sufficiently occur, the hardness decreases, and the chemical resistance becomes poor. On the other hand, 200 mg KOH /
g, unreacted hydroxyl groups remain in the coating film,
Poor weather resistance.

The fluororesin used in the present invention has an acid value of 10
-100 mgKOH / g and hydroxyl groups having a hydroxyl number of 50-200 mgKOH / g. The optimum acid value and hydroxyl value are determined by the acid value and hydroxyl value of the acrylic resin used at the same time. The acid value is preferably 20% to 50% with respect to the acid value of the acrylic resin, and more preferably the hydroxyl value is in the range of 70% to 150% with respect to the hydroxyl value of the acrylic resin. It is preferable to select at. If the ratio is outside the above range, the compatibility between the fluororesin and the acrylic resin is reduced, and both resins are separated from each other in the paint, and the weather resistance of the coating film formed from the paint is reduced. The carboxyl group and the hydroxyl group may be directly bonded to the carbon of the main chain, or may be present in a substituent bonded to the carbon of the main chain.

The fluororesin used in the present invention is preferably a difluorinated type. Even with the same acid number and / or hydroxyl number, the difluorinated type has a much greater effect on the acrylic resin than the trifluorinated fluororesin containing an average of three fluorine atoms per two main chain carbons. Since it has a high affinity for, a coating material that is more uniform and has excellent storage stability and curability can be provided. The molecular weight of the fluororesin is preferably from 5,000 to
100,000, particularly preferably 10,000 to 50,000
It is. Such a fluororesin may be a homopolymer of fluoroethylene into which a substituent having a carboxyl group or a hydroxyl group is introduced instead of hydrogen, or fluoroethylene and another vinyl monomer having a carboxyl group or a hydroxyl group. It may be derived from a copolymer with a monomer. Such a fluororesin is used in an amount of 10 to 70% by weight, preferably 30 to 7% by weight, based on the total solid content in the electrodeposition coating composition.
It is blended in an amount of 0% by weight.

As the acrylic resin constituting the coating composition of the present invention, all acrylic resins used in conventional electrodeposition coatings can be used, but preferably the acid value is 20 to 150 mg.
KOH / g, hydroxyl value 40-200 mg KOH
/ G, particularly preferably an acid value of 40 to 100 mg KOH /
g, having a hydroxyl value of 50 to 150 mgKOH / g. The molecular weight of the acrylic resin is preferably 5
000-100,000, particularly preferably 10,000-7
0000. The acrylic resin is blended in an amount of 10 to 70% by weight, preferably 20 to 60% by weight based on the total solid content in the paint. When the content of the acrylic resin is less than 10% by weight, a paint excellent in transparency, gloss, surface hardness and adhesion to a substrate cannot be obtained. On the other hand, if it exceeds 70% by weight, the amount of the fluororesin or the curing agent becomes relatively small,
A coating film excellent in weather resistance, water resistance and surface hardness cannot be obtained.

The polymerizable monomer for introducing a carboxyl group into the acrylic resin includes acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, maleic monoester, itaconic acid, itaconic monoester, crotonic acid. , Citraconic acid or the like, and a vinyl polymerizable α, β-unsaturated fatty acid and a mixture thereof. The carboxyl group has an acid value of the acrylic resin of 20 to 150 mgKOH / g, preferably 40 to 150 mgKOH / g.
It is introduced so as to be １００100 mgKOH / g. Acid value is 2
If it is less than 0, the water dispersibility of the resin is poor, and it becomes difficult to produce a uniform coating. On the other hand, if the acid value exceeds 150 mgKOH / g, the water resistance of the coating film becomes poor, which is not preferable.

The reason for introducing a hydroxyl group into the acrylic resin is to enhance the reactivity with the curing agent. In order to introduce a hydroxyl group, a polymerizable monomer having a hydroxyl group, for example, β-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, allyl alcohol, hydroxybutyl (meth) acrylate, trade name Plaxel FM1
5 to 5 (Daicel Chemical Co., Ltd.) and a mixture thereof.

In the acrylic resin of the present invention, hydroxyl groups are introduced so as to have a hydroxyl value of 40 to 200 mgKOH / g, more preferably 50 to 150 mgKOH / g. If the hydroxyl value is less than 40 mgKOH / g, the curing reaction does not sufficiently occur, the hardness decreases, and the chemical resistance becomes poor. On the other hand, if it exceeds 200 mgKOH / g, unreacted hydroxyl groups remain in the coating film, resulting in poor water resistance and weather resistance.

The acrylic resin of the present invention may be copolymerized with a monomer having a chelate-forming group for the purpose of matting the coating film. Examples of the monomer having a chelate-forming group include acetoacetoxyethyl (meth) acrylate,
Examples thereof include acetoacetoxypropyl (meth) acrylate and acetoacetoxybutyl (meth) acrylate. Particularly preferred is acetoacetoxyethyl (meth)
Acrylate. The monomer having a chelate-forming group may be copolymerized at 2 to 20% by weight based on the total weight of the monomers to be copolymerized. On the other hand, if the copolymerization is more than 20% by weight, the chelate is too stabilized, so that a good matte coating film cannot be obtained.

Further, the acrylic resin of the present invention may be copolymerized with N-methylolacrylamide and / or N-butoxymethylacrylamide. These amide components are added in an amount of 2 to 10% by weight, preferably 3 to 5% by weight, based on the total weight of the monomers forming the acrylic resin. By copolymerizing these amide components,
Since a cross-linking reaction occurs between the acrylic resins, the cross-linking density increases, and the water resistance, chemical resistance, and the like are improved.

The acrylic component of the acrylic resin of the present invention includes methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, and normal butyl (meth) acrylate.
Acrylate, cyclohexyl (meth) acrylate, lauryl (meth) acrylate, glycidyl (meth) acrylate and the like are all suitably used. The acrylic resin of the present invention includes styrene, α-methylstyrene, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, (meth) acrylonitrile, vinyl fluoride, vinylidene fluoride, and 2-ethylhexyl (meth).
An acrylate or the like may be copolymerized.

The acrylic resin may be produced by any known method such as solution polymerization, emulsion polymerization, suspension polymerization and the like. In particular, alcohol solvents, cellosolve solvents,
It is preferable to employ a solution polymerization method in which a water-miscible solvent such as a carbitol-based solvent, a glyme-based solvent, or a cellosolve acetate-based solvent is used, and each monomer and an initiator are added to carry out polymerization. As the initiator used in preparing the acrylic resin, any of those used in ordinary synthesis are suitably used, and examples thereof include an azo compound, a disulfide compound, a sulfide compound, a sulfine compound, a diazo compound, and a nitroso compound. Compounds and peroxide compounds are exemplified.

The acrylic resin used in the paint of the present invention has a weight average molecular weight of 5,000 to 100,000, more preferably 10,000 to 70,000, and a scale of the molecular weight distribution expressed by the ratio of the weight average molecular weight to the number average molecular weight is 1 to 1. 6,
More preferably, it is 1-4. If the molecular weight of the acrylic resin is 5,000 or less, the gloss is difficult to disappear, and if it exceeds 100,000, the flowability of the electrodeposition coating film deteriorates.

In the paint of the present invention, the acrylic resin has a carboxyl group as an alkaline substance such as ammonia; trimethylamine, monoethylamine, diethylamine,
Triethylamine, tripropylamine, triisopropylamine, monobutylamine, dibutylamine, tributylamine, cyclohexylamine, dicyclohexylamine, diethylcyclohexylamine, methoxyisopropylamine, 2-amino-2-methylpropanol, 2-dimethylamino-2-methyl -1-propanol,
Aliphatic amines such as morpholine and N-ethylmorpholine; neutralized with alkanolamines such as ethanolamine, diethanolamine, triethanolamine, monomethylethanolamine, dimethylethanolamine and dibutylethanolamine, and used as a water-soluble resin I just need.

In the present invention, at least one of an amino resin and a blocked isocyanate resin is used as a curing agent in an amount of 20 to 50% by weight, preferably 30 to 40% by weight, based on the total solid content of the coating composition.
It is blended in the range of weight%. If the amount of the curing agent is less than 20% by weight, a sufficient curing reaction does not take place. On the other hand, if the amount exceeds 50% by weight, the coating film becomes too hard, and the adhesion and the flexibility deteriorate.

Preferably, the curing agent is an amino resin. Amino resin used as a curing agent is a condensate of an amino compound such as melamine, urea, benzoguanamine and glycoluril with an aldehyde compound such as formaldehyde and acetaldehyde by denaturing a lower alcohol such as methanol, ethanol, propanol and butanol. The obtained condensate. Those that are easily soluble when dissolved in water are not preferred because of their poor migration during electrodeposition. Therefore, a resin modified only with methanol or ethanol is not preferable because it is easily soluble in water, and a methyl / butyl mixed ether-modified melamine resin is usually suitably used.

The melamine resin includes a highly imino-type alkyl etherified melamine resin, a methylol type alkyl etherified melamine resin, an alkyl etherified melamine resin,
It is classified as a mixed alkyl etherified melamine resin, etc., and any of them can be used, and can be appropriately selected according to the baking temperature and the physical properties of the coating film. Since those having an imino group or a methylol group generally have low water resistance, alkyl etherified melamine resins and mixed alkyl etherified melamine resins are preferred from the viewpoint of water resistance of the coating film.

Examples of the alkyl etherified melamine resin include a butylated melamine resin etherified with an n-butyl group and an iso-butyl group, a methylated melamine resin etherified with a methyl group, and a methyl group and an n-butyl group. Group, methyl etherified by i-butyl group /
There are butyl mixed etherified melamine resins. Commercially available methylated melamine resins include, for example, those having a methoxy / isobutoxy group molar ratio of 60/4.
Cymel 238 having a molar ratio of methoxy group / butoxy group of 60/40, Cymel 231 having a molar ratio of methoxy group / butoxy group of 65/35, and Cymel 231 having a molar ratio of methoxy group / butoxy group of 65/35, and a molar ratio of methoxy group / butoxy group of 40/60. Cymel 236,
Examples thereof include Cymel 266 and 277 having a molar ratio of methoxy group / butoxy group of 70/30 (all of them are manufactured by Mitsui Cytec); Sumimar 50B (manufactured by Sumitomo Chemical Co., Ltd.).

Commercially available butylated melamine resins include, for example, Mycoat 506 (manufactured by Mitsui Cytec), U-Van 20SE, U-Van 20N
-60 (manufactured by Mitsui Toatsu Chemicals).
Commercially available methylated melamine resins include, for example, Cymel 303 (manufactured by Mitsui Cytec), Sumimar M30W, M40S, M50W (all manufactured by Sumitomo Chemical Co., Ltd.), Melan 622, 623 (all manufactured by Hitachi Chemical Co., Ltd.) And the like).

As the urea resin, for example, UFR6
Commercial products such as 5,300 (manufactured by Mitsui Cytec) can be mentioned.

Examples of the guanamine resin include commercially available products such as Cymel 1123, 1128, and Mycoat 105 (benzoguanamine resin; manufactured by Mitsui Cytec).

Examples of the glycoluril resin include commercially available products such as Cymel 1170, 1171 and 1172 (manufactured by Mitsui Cytec). In the present invention, the amino resin preferably has a molecular weight of 500 to 2,000.

The above isocyanate compound is usually used as a blocked isocyanate compound in which a reactive group is blocked with a suitable blocking agent in order to enhance the stability of the obtained coating composition. The blocking agent is not particularly limited and includes, for example, oxime-based blocking agents such as methyl ethyl ketoxime, acetoxime, cyclohexanone oxime, acetophenone oxime, and benzophenone oxime; phenol-based blocking agents such as m-cresol and xylenol; methanol, ethanol , Butanol, 2-ethylhexanol, cyclohexanol,
Alcohol blocking agents such as ethylene glycol monoethyl ether; lactam blocking agents such as ε-caprolactam; diketone blocking agents such as diethyl malonate and acetoacetic ester; mercaptan blocking agents such as thiophenol; Urea-based blocking agents such as urea; imidazole-based blocking agents; carbamic acid-based blocking agents, and the like. Among them, lactam blocking agents, oxime blocking agents, and diketone blocking agents are preferred.

The isocyanate compound used as the blocked isocyanate is not particularly limited as long as it has at least two isocyanate groups in one molecule. For example, hexamethylene diisocyanate (HMD)
I), trimethylhexamethylene diisocyanate (T
Aliphatic diisocyanates such as MDI); alicyclic diisocyanates such as isophorone diisocyanate (IPDI); aromatics of xylylene diisocyanate (XDI)
-Aliphatic diisocyanates; aromatic diisocyanates such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI); dimer acid diisocyanate (DDI), hydrogenated TDI
(HTDI), hydrogenated diisocyanates such as hydrogenated XDI (H6XDI) and hydrogenated MDI (H12MDI); dimers, trimers, tetramers and higher polyisocyanates thereof; Adducts of these with polyhydric alcohols such as ethylene glycol, trimethylolpropane, and pentol, water, and low molecular weight polyester resins can be given. In order to further improve the reactivity, a small amount of a tin compound such as dibutyltin dilaurate may be used in combination as needed.

The above-mentioned blocked isocyanate compound can be obtained by reacting the above-mentioned isocyanate compound and the above-mentioned blocking agent until free isocyanate groups disappear by a conventional method. Some of these are commercially available, for example, Desmodur series (manufactured by Sumitomo Bayer Urethane Co., Ltd.), Vernock D series (manufactured by Dainippon Ink and Chemicals, Inc.), Takenate B series (manufactured by Takeda Pharmaceutical Co., Ltd.),
Coronate 2500 series (manufactured by Nippon Polyurethane Industry Co., Ltd.) or the like can be used. Further, as the curing agent, a mixture of the amino resin and the blocked isocyanate may be used.

The matting electrodeposition coating can be obtained by adding a metal chelate compound to the coating composition of the present invention in addition to the above-mentioned coating components. The metal chelate compound of the present invention is a chelate compound of a metal atom with at least a long-chain β-ketoester or a compound containing a long-chain β-ketoester and β-diketone. Particularly preferred metal chelates of the present invention are metal chelates containing long-chain β-ketoesters and β-diketones, where aluminum is an example of a metal atom, of the formula (I):

[0031]

Embedded image[Wherein, R₁Is an alkyl group having 1 to 4 carbon atoms, R₂Is hydrogen
An atom or an alkyl group having 1 to 4 carbon atoms, R₃Is carbon number 6
30 to a long-chain alkyl group, X is (R₄O-CO-CH₂-
CO-CH₃) Or OR₅And R₄Has 1 to 1 carbon atoms
An alkyl group of 5, R ₅Is an alkyl group having 1 to 20 carbon atoms
A compound].

The number of moles of long chain β-ketoester bonded is 0.5.
Below, the long-term stability (gloss stability and high appearance) is poor. If the number of moles of β-diketone is 0.5 or more, the long-term stability is further improved. When the carbon number of the ester group of the β-ketoester is 1 to 5, long-term gloss stability cannot be ensured.

The long-chain β-ketoester has 6 carbon atoms.
A reaction product of the above alcohol and acetoacetic acid can be suitably used, and examples thereof include octyl acetoacetate, 2-ethylhexyl acetoacetate, lauryl acetoacetate, palmityl acetoacetate, stearyl acetoacetate, and oleyl acetoacetate. As β-diketone, acetylacetone, 2,4-hexanedione, 2,4-heptanedione,
3-butyl-2,4-pentanedione and the like can be used.

As the metal atom, zinc, zirconium,
Those having properties capable of forming a chelate compound such as aluminum and titanium can be used. Preferably, the metal is aluminum or zirconium, most preferably aluminum.

In the metal chelate compound of the present invention,
The number of coordinating molecules coordinating to metal atoms varies depending on the type of metal atom, but the average number of long chain β-ketoesters and β-diketones coordinating to each metal atom is as follows:
On aluminum: long chain β-ketoester is 0.5-0.5
2.5, preferably 1.0-2.0, β-diketone is 2.5
Below, preferably 0.5 to 2.5, more preferably 0.5 to 1.5, for zinc and zirconium: long chain β-
The ketoester is 0.5 to 1.5, preferably 0.7 to 1.5.
5, β-diketone is 1.5 or less, preferably 0.5
-1.5, more preferably 0.5-1.0, for titanium: 1-3.5, preferably 1.5-3.0, long-chain β-ketoester, 2.5 β-diketone. Or less, preferably 1.0 to 2.5, and more preferably 1.0 to 2.0. As long as the above coordination number is secured, molecules other than long-chain β-ketoesters and β-diketones, for example, β-ketoesters or alkoxy groups having an alkylester group having 5 or less carbon atoms are coordinated or bonded. You may.

In the matte electrodeposition coating composition, the metal chelate compound is 0.5 to 5.0% by weight, preferably 1.0 to 3.0%.
% By weight. If it is less than 0.5% by weight, a sufficient matting effect cannot be obtained. On the other hand, if it is more than 5.0% by weight, the luster may be too faint.

In the paint of the present invention, the solid content of the paint is 5 to 20% by weight, preferably about 8 to 10% by weight. Further, if necessary, a dye, a colorant and other commonly used additives may be blended.

[0038]

EXAMPLES (Synthesis of Acrylic Resin 1) 32 parts by weight of isopropyl alcohol as a solvent and butyl cellosolve 3
3 parts by weight were charged into a reaction vessel and heated to 90 to 100 ° C., and while slowly refluxing, 10 parts by weight of styrene, 23.5 parts by weight of methyl methacrylate, 15 parts by weight of isobutyl acrylate, 8 parts by weight of ethyl acrylate, A mixture of 27 parts by weight of hydroxyethyl acrylate, 10 parts by weight of methacrylic acid and 4 parts by weight of N-butoxymethylacrylamide and 2.0 parts by weight of azoisobutyronitrile as a polymerization initiator was added dropwise over 3 hours. After the completion of the dropwise addition, the reaction was further continued for 1 hour. Then, 0.5 parts by weight of azoisobutyronitrile and 1.0 part by weight of isopropyl alcohol as initiators were added dropwise over 1.5 hours, and the reaction was further continued for 2 hours. Was. The obtained acrylic varnish has a nonvolatile content of 60% and a hydroxyl value of 130 mg KO.
H / g, acid value was 65 mgKOH / g, and weight average molecular weight was 30,000.

(Synthesis of Acrylic Resin 2) When 67 parts by weight of isopropyl alcohol was heated to 80 ° C., 2 parts by weight of γ-methacryloxypropyltrimethoxysilane, 25 parts by weight of methyl methacrylate, 21 parts by weight of styrene, acrylic acid 22 parts by weight of n-butyl, 20 parts by weight of hydroxyethyl methacrylate, 7 parts by weight of acrylic acid and 1 part by weight of azobisisobutyronitrile were added dropwise over 3 hours. After completion of the dropwise addition, 10 parts by weight of n-butanol and 0.5 part by weight of azobisisobutyronitrile were added dropwise over 30 minutes, and the reaction was continued for another 4 hours. The obtained alkoxysilane-containing acrylic resin varnish has a nonvolatile content of 50%,
Acid value 54 mgKOH / g, hydroxyl value 86 mgKOH /
g, weight average molecular weight was 40,000.

(Metal chelate compound to be used) Aluminum is coordinated with aluminum at a ratio of 2 parts by weight of ethyl acetoacetate as a long-chain β-ketoester and 1.0 part by weight of acetylacetone as a β-diketone to form a chelate compound. Was prepared and blended into the matte electrodeposition coating composition of the example.

Example 1 15.0 parts by weight of the acrylic resin 1 varnish synthesized above and a fluororesin "KD300D" (manufactured by Kanto Denka Co., Ltd .; difluorinated type, hydroxyl value 120 mgKOH / g, acid value 2)
0 mg KOH / g, weight average molecular weight 40000) 16.
Triethylamine was added to 0 parts by weight so as to have a neutralization ratio of 35% (0.35 equivalents based on the carboxyl group), and mixed uniformly. A predetermined amount of a mixture of 8.0 parts by weight of Cymel 235 (manufactured by Mitsui Cytec; melamine resin) and 4.0 parts by weight of the metal chelate compound prepared above was added thereto, and the mixture was stirred for 10 minutes. did. While stirring, gradually add deionized water to the mixture to obtain a solid content of 30% by weight.
Was prepared and used as an electrodeposition paint stock solution. This stock solution was stored at room temperature to confirm the stability of the coating. Triethylamine and deionized water were added to this stock solution to obtain a neutralization ratio of 7%.
A material having 0% and a solid content of 10% by weight was subjected to electrodeposition. The electrodeposition paint was adjusted to 20 ° C., and anodized to a 6063S aluminum alloy plate (alumite film thickness: 9 μm).
m) and an electrolytic coloring treatment, followed by a sealing treatment (80 ° C.
Immersion in hot water for 3 minutes), and applying a DC voltage of 100 to 200 V for 3 minutes so as to obtain a dry film thickness of 8 to 10 μm, for electrodeposition coating. After the electrodeposition coating, the coated aluminum alloy plate was immersed in the above-mentioned washing bath adjusted to 20 ° C. for 3 minutes.
Baking and drying were performed at 80 ° C. for 30 minutes to obtain a cured coating film.

Example 2 "KD300E" (manufactured by Kanto Denka Co., Ltd .; 2
Except for using a fluorinated type, a hydroxyl value of 160 mgKOH / g, an acid value of 20 mgKOH / g, and a weight average molecular weight of 40,000, the same procedure as in Example 1 was carried out to confirm the storage stability of the stock coating solution, electrodeposition coating, washing with water and baking. Done.

Comparative Example 1 "KD300B" (manufactured by Kanto Denka; 2
Fluorine type, hydroxyl value 80mgKOH / g, acid value 4
(0 mg KOH / g, weight average molecular weight 40000) except that the storage stability of the undiluted coating solution, electrodeposition coating, washing with water and baking were carried out in the same manner as in Example 1.

Comparative Example 2 "KD300C" (manufactured by Kanto Denka; 2
Fluorine type, hydroxyl value 120mgKOH / g, acid value 10m
gKOH / g, weight average molecular weight 40000), and the storage stability of the coating solution was confirmed, electrodeposition coating, washing with water, and baking were carried out in the same manner as in Example 1.

Comparative Example 3 27.0 parts by weight of the acrylic resin 2 varnish synthesized above and a fluororesin “Lumiflon 926” (manufactured by Asahi Glass Co., Ltd .; 3
Fluoride type, hydroxyl value 60mgKOH / g, acid value 2
0mgKOH / g) 20.0 parts by weight, Cymel 235
Triethylamine was added to 12.0 parts by weight (manufactured by Mitsui Cytec Co., Ltd., melamine resin) so as to have a neutralization ratio of 60% (0.60 equivalents based on carboxyl groups), and the mixture was stirred for 10 minutes. Deionized water was gradually added thereto with stirring to prepare an aqueous dispersion having a solid content of 30% by weight, which was used as a stock solution for electrodeposition paint. This stock solution was stored at room temperature to confirm the stability of the coating. Deionized water was added to this stock solution to achieve a neutralization rate of 6%.
A material having 0% and a solid content of 10% by weight was subjected to electrodeposition. The electrodeposition paint was adjusted to 20 ° C., and anodized to a 6063S aluminum alloy plate (alumite film thickness: 9 μm).
m) and an electrolytic coloring treatment, followed by a sealing treatment (80 ° C.
Immersed in hot water for 3 minutes), and applied a DC voltage of 150 to 250 V for 3 minutes so as to obtain a dry film thickness of 8 to 10 μm, for electrodeposition coating. After the electrodeposition coating, the coated aluminum alloy plate was immersed in the above-mentioned washing bath adjusted to 20 ° C. for 3 minutes.
Baking and drying were performed at 80 ° C. for 30 minutes to obtain a cured coating film.

[Evaluation of Stability as a Paint] The storage stability of each of the stock solutions of the electrodeposition paints of Examples 1 and 2 and Comparative Examples 1 and 2 was determined by measuring the average particle size of the paint emulsion (light scattering method: manufactured by Hitachi, Ltd.). U-100 Hitachi Regio Beam Spectrophotometer "
Was measured). The results are shown in Table 1. “KD300B” and “KD30”, which are difluorinated fluororesins, whose acid value is significantly different from the acid value of the acrylic resin
The paints of Comparative Examples 1 and 2 using “0C” had a particle diameter of 400.
It was observed that the stability was poor over nm.

[0047]

[Table 1]

Using the dried coating films obtained in Examples 1 and 2 and Comparative Example 3, the coating films were evaluated for appearance, hardness, acid resistance, alkali resistance and weather resistance. The measuring method and evaluation criteria are as follows. [Evaluation of Appearance of Coating Film by Electrodeposition Coating] The coating film surface was visually observed and judged according to the following evaluation criteria according to the presence or absence of abnormalities such as uneven gloss and roughness. ：: No abnormality at all △: Slight abnormality observed ×: Remarkable abnormality observed

[Hardness] A scratch value test was performed with a pencil in accordance with JIS K5400, and the hardness was indicated by the highest pencil hardness at which the coating film was not scraped off.

[Acid resistance] According to JIS K8602,
After being exposed to a 5% sulfuric acid aqueous solution at 20 ° C. for 48 hours, the coating film surface is visually observed, and a rating number (JIS K8681: corrosion area ratio to test surface) is used.
Represented by

[Alkali resistance] According to JIS K8602, the coating film surface was visually observed after being exposed to a 1% aqueous sodium hydroxide solution at 20 ° C. for 48 hours.
It was represented by a rating number (JIS K8681: corrosion area ratio to test surface).

[Weather resistance] According to JIS K5400,
After exposing for 3000 hours using a sunshine weatherometer using a carbon arc lamp accelerated weathering tester, the gloss of the coating film was measured, and the rate of change (gloss retention) with respect to the gloss before the exposure test was determined. The surface of the film was visually observed, and judged according to the following criteria in accordance with the presence or absence of an abnormality such as blistering, whitening or peeling of the coating film. ：: The gloss retention is 80% or more, and no abnormality in appearance is observed. Δ: The gloss retention is 50 to less than 80%, and slight abnormality in appearance is observed. ×: The gloss retention is less than 50%. And a remarkable abnormality is observed in appearance. Table 2 shows the evaluation results of the coating films.

[0053]

[Table 2]

[0054]

The electrodeposition coating composition of the present invention is excellent in weather resistance of a coating film and can be applied to a wide range of applications requiring weather resistance. In addition, since it has excellent stability as a paint, there is no sedimentation of particles in an electrodeposition bath, and the finish of a coated film after baking is good.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 175/04 C09D 175/04 C25D 13/06 C25D 13/06 Z F-term (Reference) 4D075 AB09 CA02 CA32 CA38 CB02 CB04 CB06 DB01 EB16 EB20 EB22 EB32 EB36 EB39 EB52 EB55 EB56 EC08 EC54 4J038 CD091 CD092 CG031 CG032 CG061 CG062 CG071 CG072 CG081 CG082 CG141 GA02 NA121 CH122 GA03

Claims (4)

[Claims] 1. An acrylic resin having a carboxyl group and a hydroxyl group in an amount of 10 to 70% by weight (based on a solid content, the same applies hereinafter). B) An amount of the carboxyl group and the hydroxyl value in which the acid value becomes 10 to 100 mgKOH / g. 50-200mgK
10 to 70% by weight of a difluorinated fluororesin having a hydroxyl group in an amount of OH / g; and c) 20 to 50% by weight of at least one of an amino resin and a blocked isocyanate resin, provided that a) + b)
+ C) to 100% by weight) and b)
An electrodeposition coating composition wherein the acid value of the difluorinated fluororesin is 20% to 50% of the acid value of the acrylic resin of a). 2. The hydroxyl value of the difluorinated fluororesin of b) is 70% of the hydroxyl value of the acrylic resin of a).
The electrodeposition coating composition according to claim 1, wherein the content is from about 150% to about 150%. 3. The metal chelate compound containing a long-chain β-ketoester having an alkylester group having 6 to 30 carbon atoms in an amount of 0.5 to 5.0% by weight. Electrodeposition coating composition. 4. A metal chelate compound containing a long-chain β-ketoester and a β-diketone having an alkylester group having 6 to 30 carbon atoms in an amount of 0.5 to 5.0% by weight. Or the electrodeposition coating composition according to 2.