JP3280539B2 - Matte electrodeposition coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention can form a coating film which is excellent in appearance and matting degree, has no gloss unevenness, and has excellent chemical properties such as weather resistance, acid resistance and yellowing resistance. A possible matte electrodeposition coating composition.

[0002]

2. Description of the Related Art Conventionally, in a water-based paint obtained by neutralizing a resin having a carboxyl group with an organic amine or ammonia, a conductive object represented by a metal is used as an anode, and a voltage is applied between the anode and a cathode. Accordingly, a method of forming an electrodeposition coating film on the surface of a substrate to be coated is widely used. In recent years, a matte coating film that creates a calm atmosphere has been demanded instead of a metallic luster. Conventionally, as an electrodeposition coating composition to form a matte coating film,
(A) a composition containing fine powder of polyethylene or the like (for example, JP-A-60-135466) or (B) a composition containing crosslinked resin particles (for example, JP-A-63-6376)
No. 0) is known as a typical example. Recently, in order to improve weather resistance, (c) a composition containing a fluorine-containing copolymer as a binder (for example, see
No. 202382) is also known. However, (a)
However, the composition has problems that the matte effect is not long-lasting and that gloss unevenness is likely to occur. On the other hand, in the composition (b), if the difference in the refractive index between the binder and the crosslinked resin particles is not sufficiently controlled, there is a problem that the coating film becomes cloudy or a matting effect cannot be obtained. Further, since the composition (c) uses a microgel, it has the same problems as the composition (b). In addition, conventional electrodeposition coating compositions usually use a melamine resin or a blocked polyisocyanate as a cross-linking agent.For example, when a melamine resin is used, acid resistance is deteriorated. When used, there were problems such as easy yellowing.

[0003]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned problems of the conventional matte electrodeposition coating composition, that is, it has excellent appearance and matte degree, has no gloss unevenness, and has weather resistance. An object of the present invention is to provide a matte electrodeposition coating composition capable of forming a coating film having excellent chemical properties such as resistance, acid resistance and yellowing resistance.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and have found that an aqueous fluorinated copolymer having a specific functional group and an acrylic copolymer having a specific functional group have been developed. It has been found that the above object can be achieved by using a binder consisting of That is, the matte electrodeposition coating composition of the present invention comprises (A) 40 to 80% by weight of an aqueous fluorinated copolymer having a carboxyl group and a hydroxyl group, (B) an alkoxysilane group, and a general formula -CONHCH ₂ OR ( In the formula, R is an alkyl group having 1 to 4 carbon atoms) and a cycloalkyl group, and an acrylic copolymer 60 to 60 containing an ultraviolet light-stable monomer as a copolymerizable unsaturated monomer.
20% by weight of a binder. Hereinafter, the present invention will be described in detail.

The aqueous fluorinated copolymer having a carboxyl group and a hydroxyl group used as one component of the binder in the present invention (hereinafter referred to as "aqueous fluorinated copolymer") contains a carboxyl group and a hydroxyl group in the molecule. It is a resin that dissolves in water or is stably dispersed in water when neutralized with a neutralizing agent. The acid value of the aqueous fluorinated copolymer is preferably from 5 to 150, particularly preferably from 15 to 100.
When the acid value is smaller than the above range, the storage stability of the coating tends to decrease, and when it is larger, the water resistance of the coating film tends to deteriorate. The hydroxyl value of the aqueous fluorinated copolymer is preferably from 25 to 120, particularly preferably from 40 to 1.
00. When the hydroxyl value is smaller than the above range,
The crosslinkability with the acrylic copolymer component described later becomes insufficient, and the various physical strengths of the obtained coating film tend to decrease, and a matte coating film tends to be difficult to obtain. The water resistance of the film tends to deteriorate. The weight average molecular weight of the aqueous fluorine-containing copolymer is preferably from 2,000 to
150,000, particularly preferably 4,000 to 100,000
It is.

As such an aqueous fluorinated copolymer, a commercially available product, "Lumiflon 926" (trade name, manufactured by Asahi Glass Co., Ltd.) which is a copolymer mainly composed of fluoroolefin and cycloalkyl vinyl ether (acid value: about 20, (Hydroxyl value: about 60); trade name “Fluonate JZ-443” manufactured by Dainippon Ink and Chemicals, which is a copolymer containing fluoroolefin, vinyl ether and vinyl ester as main components.
(Acid value about 8, hydroxyl value about 85); fluoroolefin,
"Zeffle EV-12" (trade name, manufactured by Daikin Industries, Ltd.) which is a copolymer containing vinyl ether and vinyl ester as main components.
0 "(acid value about 48, hydroxyl value about 60)," Zeffle EV
-210 "(acid value about 80, hydroxyl value about 89); trade name" Cefralcoat XA-500-1 "(manufactured by Central Glass Co., Ltd.) which is a copolymer containing fluoroolefin, vinyl ether, allyl ether and vinyl ester as main components. Acid value of about 35, hydroxyl value of about 37), "Sefuralcoat XA-5
00-2 "(acid value about 33, hydroxyl value about 46)," Sefuralcoat XA-500-8 "(acid value about 45, hydroxyl value about 52)," Sefuralcoat XA-500-13 "(acid value about 48, A hydroxyl value of about 52) is known as a typical example. Further, JP-A-5-98207, JP-A-3-98207
181540, JP-A-2-70706, JP-A-2-70
55776, JP-A-62-243603, JP-A-6-243603
Various aqueous fluorinated copolymers described in JP-A-2-50306 and JP-A-58-136605 can also be used.

[0007] Such an aqueous fluorinated copolymer is used in the present invention.
By using it as a component of the binder in
An excellent matte coating film can be obtained. Binder in the present invention
An alkoxysilane group used as one component of the general formula-
CONHCH_TwoOR (where R is an alkyl having 1 to 4 carbon atoms)
And a cycloalkyl group
And a UV-stable model as a copolymerizable unsaturated monomer.
Acrylic copolymer using nomer (hereinafter referred to as “acryl copolymer”
For example) has an alkoxysilane group
Copolymerizable unsaturated monomer having the general formula -CONHCH_TwoO
R (where R is an alkyl group having 1 to 4 carbon atoms)
Α, β-monoethylenically unsaturated mono having the indicated group
(Preferably, a compound of the general formula CH_Two= C (R ¹) CONH
CH_TwoOR (where R is an alkyl group having 1 to 4 carbon atoms)
Yes, R¹Is a hydrogen atom or a methyl group)
α, β-monoethylenically unsaturated monomer], cycloal
Copolymerizable unsaturated monomer having a kill group and copolymerizable purple
External stability monomer is included as an essential component, and the rest is
Copolymerizable unsaturated mono, which is another copolymerizable unsaturated monomer
The polymer mixture is prepared by a known solution polymerization method, emulsion polymerization method, non-aqueous dispersion method.
It is obtained by a copolymerization reaction by a polymerization method or the like.
You.

The above-mentioned copolymer monomer having an alkoxysilane group includes divinyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltributoxysilane, γ-methacryloxypropyltrimethoxysilane, Typical examples thereof include γ-methacryloxypropyltriethoxysilane, trimethoxyallylsilane, triethoxyallylsilane, (meth) acryloylmethyltrimethoxysilane, (meth) acryloylethyltrimethoxysilane and the like. The above general formula -CO
Examples of the α, β-monoethylenically unsaturated monomer having a group represented by NHCH ₂ OR (where R is an alkyl group having 1 to 4 carbon atoms) include N-methoxymethyl (meth) acrylamide, N -Methoxymethyl (meth) acrylamide, Nn-propoxymethyl (meth) acrylamide, Ni-propoxymethyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, Ni-butoxymethyl (meth) Acrylamide,
Nt-butoxymethyl (meth) acrylamide is mentioned. Examples of the cycloalkyl group-containing monomer include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, and t-butylcyclohexyl (meth)
Acrylates, cyclododecyl (meth) acrylates and the like are mentioned as typical ones.

The above-mentioned copolymerizable ultraviolet light-stable monomer includes 4- (meth) acryloyloxy-2,2,2.
6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloylamino-2,2
6,6-tetramethylpiperidine, 4- (meth) acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4- (meth) acryloylamino-2,2,6,6- Tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-
2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1- Crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine,
1- (meth) acryloyl-4-cyano-4- (meth)
Acryloylamino-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloyloxy-2,2,2
6,6-tetraethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6,6-pentaethylpiperidine, 4- (meth) acryloyloxyethyloxy-1,2,2,6,6-pentane Methylpiperidine, 4-
(Meth) acryloyloxyethyloxy-2,2,
6,6-tetraethylpiperidine, 2-hydroxy-4
-(3- (meth) acryloxy-2-hydroxypropoxy) benzophenone, 2,2'-dihydroxy-4
-(3- (meth) acryloxy-2-hydroxypropoxy) benzophenone and 2-hydroxy-4-methacryloxyethylbenzophenone are typical examples.

Other copolymerizable unsaturated monomers constituting the remainder of the copolymerizable unsaturated monomer mixture include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypentyl ( (Meth) acrylate, neopentyl glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, glycerin mono (meth) acrylate and other copolymerizable unsaturated monomers having a hydroxyl group, (meth) acrylic acid,
Copolymerizable unsaturated monomers having a carboxyl group such as crotonic acid, itaconic acid, maleic acid, fumaric acid, methyl (meth) acrylate, ethyl (meth) acrylate,
Alkyl esters of (meth) acrylic acid such as propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, lauryl (meth) acrylate, glycidyl (meth) acrylate, styrene,
Representative examples thereof include vinyl toluene, (meth) acrylonitrile, and vinyl acetate.

The acrylic copolymer used as one component of the binder in the present invention is a copolymer obtained by copolymerizing these copolymerizable unsaturated monomer mixtures, and preferably has a weight average molecular weight of 2,2. 000 to 100,000, and more preferably 10,000 to 50,000. The amount of the copolymerizable unsaturated monomer having an alkoxysilane group in the acrylic copolymer is preferably from 0.1 to 30% by weight, particularly preferably from 1 to 15% by weight. If the amount of the copolymerizable unsaturated monomer having an alkoxysilane group is less than the above range, it becomes difficult to obtain a matte coating film which is the object of the present invention, and if it is too large, it becomes difficult to obtain a uniform coating film. There is a tendency.

The general formula -CO in the acrylic copolymer
The amount of the α, β-monoethylenically unsaturated monomer having a group represented by NHCH ₂ OR is preferably 5 to 50% by weight, particularly preferably 8 to 30% by weight. The α, β-
If the amount of the monoethylenically unsaturated monomer is less than the above range, the crosslinking reaction between the N-alkoxymethylamide group in the acrylic copolymer and the hydroxyl group in the aqueous fluorinated copolymer and the N- The self-crosslinking reaction between the alkoxymethylamide groups becomes insufficient, the various physical strengths of the obtained coating film tend to decrease, and the matte coating film tends to be difficult to obtain. It becomes easy to gel during the production of the copolymer. The amount of the copolymerizable cycloalkyl group-containing monomer in the acrylic copolymer is 25.
８０80% by weight, preferably 15-70% by weight. If the amount of the copolymerizable cycloalkyl group-containing monomer is less than the above range, the weather resistance of the coating film becomes insufficient, and if it is too large, a matte coating film tends to be difficult to obtain. The amount of copolymerizable UV-stable monomer in the acrylic copolymer is 0.1
10 to 10% by weight, preferably 0.3 to 5% by weight. If the amount of the copolymerizable UV-stable monomer is less than the above range, the weather resistance of the coating film will be insufficient, and if it is too large, the water resistance will be insufficient, and the coating film formed by electrodeposition coating will be heated and cured. They tend to be colored when they are made.

It is not essential that the acrylic copolymer has a hydroxyl group, but it is appropriate that the acrylic copolymer has a hydroxyl value of 10 to 100 in order to easily obtain a matte coating film. If the hydroxyl value is larger than the above range, the water resistance and the like of the coating film decrease, which is not preferable. The acid value of the acrylic copolymer is from 0 to 100, more preferably from 0 to 60. If the acid value is larger than the above range, the water resistance and the like of the coating film decrease, which is not preferable. The matte electrodeposition coating composition of the present invention contains 40 to 80% by weight, preferably 50 to 75% by weight of the above-described aqueous fluorinated copolymer.
And acrylic copolymer 60 to 20% by weight, preferably 50
-25% by weight as a binder. If the amount of the water-based fluorinated copolymer is less than the above range, the weather resistance of the coating film is reduced, and the coating film is too glossy and rough, and the storage stability of the coating material is reduced, If the amount is too large, a coating film having a low matting degree cannot be obtained, and neither is preferable. The matte electrodeposition coating composition of the present invention contains the above-mentioned binder, a neutralizing agent for making the binder water-soluble or water-dispersible, and an aqueous medium. It contains various additives such as organic or inorganic coloring pigments, extender pigments, thickeners, defoamers, anti-settling agents, anti-mold agents, curing catalysts and the like used in paints. Further, a matting agent such as a conventional crosslinked resin particle having an average particle diameter of 0.05 to 20 μm, a crosslinker such as a melamine resin or a blocked polyisocyanate which does not impair properties such as acid resistance and yellowing resistance are used in combination. It is also possible.

Typical examples of the neutralizing agent include organic amines such as monomethylamine, dimethylamine, trimethylamine, diethylamine, triethylamine, monoisopropylamine and diethylaminoethanol, and ammonia. The amount of neutralizer used is
The amount is such that the binder is stably dissolved or dispersed in the aqueous medium, and usually 30 to 100% of the total theoretical neutralization amount is appropriate. The aqueous medium is water or a mixture of water and a water-miscible organic solvent. Typical examples of the water-miscible organic solvent include ethyl cellosolve, propyl cellosolve, butyl cellosolve, ethylene glycol dimethyl ether, diacetone alcohol, ethyl alcohol, ethyl acetate, and methyl ethyl ketone. In addition,
If necessary, a small amount of a water-immiscible organic solvent such as xylene or toluene can be used in combination. The amount of the aqueous medium used is such that the solid concentration of the electrodeposition coating composition in the electrodeposition coating bath is about 2%.
A suitable amount is up to 20% by weight, preferably 5-15% by weight.

Next, a method for electrodeposition coating a conductive object using the electrodeposition coating composition of the present invention will be described. As the electrodeposition coating method, a conventionally known method can be employed as it is. That is, the electrodeposition coating composition of the present invention is maintained in an electrodeposition coating bath at a temperature of about 15 to 35 ° C. to form a bath liquid, and a conductive coating object is immersed in the bath liquid, and a coating voltage of about 50 to 400 V is applied. The electrodeposited coating film is formed on the surface of the conductive object under the conditions of preferably 70 to 300 V and a conduction time of 30 seconds to 10 minutes, preferably 1 to 5 minutes. Then, if necessary, after washing with water and air drying, 140 to 250 ° C, preferably 160 to 200 ° C
For about 10 to 60 minutes, preferably 20 to 40 minutes. Thus, an electrodeposition coating film having a desired matte effect is formed. Dry electrodeposition film thickness is about 2-50μ
m, preferably 5 to 30 μm. Note that, as the conductive coating object, for example, a metal material such as iron, steel, aluminum, and copper, or a metal plating or anodizing treatment performed on the surface of the coating object is a typical example. However, there is no particular limitation as long as it is conductive, and various coated objects can be applied. Next, the present invention will be described in more detail with reference to examples. In the examples, “parts” and “%” are based on weight.

[0016]

【Example】

<Preparation of Acrylic Copolymer Varnish B-1> 46 parts of isopropyl alcohol and 14 parts of butyl cellosolve were charged into a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a cooling tube, and heated to 85 ° C., followed by methacryloxy. 12 parts of propyltrimethoxysilane, 10 parts of N-methoxymethylacrylamide, 2-hydroxyethyl methacrylate
2.3 parts, methyl methacrylate 10.7 parts, cyclohexyl methacrylate 60 parts, 4-methacryloyloxy-
A mixture consisting of 5 parts of 1,2,2,6,6-pentamethylpiperidine and 0.7 part of azobisisobutyronitrile is
The solution was added dropwise over 3 hours while maintaining the reaction temperature at 85 ° C.
One hour after the completion of dropping, azobisisobutyronitrile is further added.
A mixture consisting of 1.0 part and 5 parts of butyl cellosolve was added dropwise over 2 hours, and the mixture was further reacted for 2 hours to produce an acrylic copolymer having an acid value of 0, a hydroxyl value of 10, and a weight average molecular weight of 25,000. A mixed solvent of isopropyl alcohol and butyl cellosolve at a weight ratio of 2: 1 was added to the reaction product so that the nonvolatile content became 50%, to prepare an acrylic copolymer varnish B-1.

<Preparation of Acrylic Copolymer Varnish B-2>
The reaction vessel was charged with 46 parts of isopropyl alcohol and 14 parts of butyl cellosolve, and heated to 85 ° C.
Methacryloxypropyltrimethoxysilane 10 parts, N
-Ethoxymethylacrylamide 30 parts, hydroxypropyl acrylate 7 parts, methyl methacrylate 17
Part, cyclohexyl acrylate 35 parts, 4-methacryloxy-2,2,6,6-tetramethylpiperidine 1
And a mixture consisting of 1.2 parts of azobisisobutyronitrile was added dropwise over 3 hours while maintaining the reaction temperature at 85 ° C. One hour after the completion of the dropwise addition, a mixture consisting of 1.0 part of azobisisobutyronitrile and 5 parts of butyl cellosolve was added dropwise over 2 hours, and the mixture was further reacted for 2 hours to obtain an acid value of 0, a hydroxyl value of 30, and a weight average molecular weight. 17,000 acrylic copolymers were prepared. The reaction product has a nonvolatile content of 5
An acrylic copolymer varnish B-2 was prepared by adding a mixed solvent of isopropyl alcohol and butyl cellosolve at a weight ratio of 2: 1 so as to be 0%.

<Preparation of Acrylic Copolymer Varnish B-3>
The reaction vessel was charged with 46 parts of isopropyl alcohol and 14 parts of butyl cellosolve, and heated to 85 ° C.
7 parts of methacryloxypropyltrimethoxysilane, N-
30 parts of n-propoxymethyl acrylamide, 4.1 parts of 2-hydroxyethyl acrylate, 3.3 parts of methyl methacrylate, 5.1 parts of acrylic acid, 50.0 parts of cyclohexyl methacrylate, 4-methacryloxy-1,2,2,2
A mixture consisting of 0.5 part of 6,6-pentamethylpiperidine and 0.7 part of azobisisobutyronitrile was reacted at a reaction temperature of 8
The solution was added dropwise over 3 hours while maintaining the temperature at 5 ° C. End of dripping 1
After an hour, a mixture consisting of 0.7 parts of azobisisobutyronitrile and 5 parts of butyl cellosolve is added dropwise over 2 hours, and the mixture is further reacted for 2 hours.
An acrylic copolymer having a weight average molecular weight of 22,000 was prepared. A mixed solvent of isopropyl alcohol and butyl cellosolve at a weight ratio of 2: 1 was added to the reaction product so that the nonvolatile content became 50%, to prepare an acrylic copolymer varnish B-3.

<Preparation of Acrylic Copolymer Varnish B-4>
The reaction vessel was charged with 46 parts of isopropyl alcohol and 14 parts of butyl cellosolve, and heated to 85 ° C.
2 parts of vinyltriethoxysilane, 30 parts of Nn-butoxymethylacrylamide, 33.6 of methyl methacrylate
Parts, 2-hydroxyethyl acrylate 8.3 parts, methacrylic acid 3.1 parts, cyclohexyl acrylate 20.0 parts
Part, 2-hydroxy-4-methacryloxyethyloxybenzophenone 3 parts and azobisisobutyronitrile
A mixture of 2.0 parts was added dropwise over 3 hours while maintaining the reaction temperature at 85 ° C. One hour after completion of the dropwise addition, 0.7 part of azobisisobutyronitrile and butyl cellosolve 5 were further added.
Was added dropwise over 2 hours and reacted for 2 hours to produce an acrylic copolymer having an acid value of 20, a hydroxyl value of 40, and a weight average molecular weight of 11,000. A mixed solvent of isopropyl alcohol and butyl cellosolve at a weight ratio of 2: 1 was added to the reaction product so that the nonvolatile content became 50%, to prepare an acrylic copolymer varnish B-4.

<Preparation of Acrylic Copolymer Varnish B-5>
The method of preparing the acrylic copolymer varnish B-1 was repeated except that 12 parts of methacryloxypropyltrimethoxysilane was changed to 0 parts, and 10.7 parts of methyl methacrylate was changed to 22.7 parts. Value 0, hydroxyl value 1
0, an acrylic copolymer having a weight average molecular weight of 24,000 was prepared, and an acrylic copolymer varnish B- having a nonvolatile content of 50% was prepared.
5 was prepared. <Preparation of Acrylic Copolymer Varnish B-6> In a method for preparing an acrylic copolymer varnish B-2, 30 parts of Nn-butoxymethylacrylamide was used as 0 part, 35 parts of cyclohexyl acrylate was used as 63 parts, and -Reaction was carried out in the same manner except that 1 part of methacryloxy-2,2,6,6-tetramethylpiperidine was changed to 3 parts,
An acrylic copolymer having a hydroxyl value of 30 and a weight average molecular weight of 15,000 was produced, and an acrylic copolymer varnish B-6 having a nonvolatile content of 50% was prepared.

<Preparation of Acrylic Copolymer Varnish B-7>
In the method for preparing the acrylic copolymer varnish B-3, the reaction was carried out in the same manner as above except that 50.0 parts of cyclohexyl methacrylate was replaced with 53.3 parts of methyl methacrylate, and the acid value was 40, the hydroxyl value was 20, and the weight-average molecular weight. 2
Acrylic copolymer of 0,500 was prepared and the non-volatile content was 50%
The acrylic copolymer varnish B-7 was prepared. <Preparation of Acrylic Copolymer Varnish B-8> In the method for preparing an acrylic copolymer varnish B-4, the method of preparing 2-hydroxy-4-methacryloxyethyloxybenzophenone 3
Parts were changed to 0 parts, and 33.6 parts of methyl methacrylate were changed to 36.6 parts. The same reaction was carried out to produce an acrylic copolymer having an acid value of 20, a hydroxyl value of 40, and a weight average molecular weight of 11,500. Then, an acrylic copolymer varnish B-8 having a nonvolatile content of 50% was prepared. [Examples 1 to 4 and Comparative Examples 1 to 7] The components shown in Table 1 (the values in the table are solid contents) were mixed, and then triethylamine was added at a ratio of 0.6 equivalent to the carboxyl group of each copolymer. , And diluted with pure water to prepare an electrodeposition paint having a solid content of 10%. The aqueous fluorinated copolymer varnish A-1 in Table 1 was manufactured by Daikin Industries, Ltd. under the trade name “Zeffle EV-2”.
10 "(acid value 80, hydroxyl value 89), and the aqueous fluorinated copolymer varnish A-2 was" Cefralcoat XA-500-2 "(trade name, manufactured by Central Glass Co., Ltd.) (acid value 33, hydroxyl value 46). The curing catalyst is “Nicure 2500X” (trade name, manufactured by King Corporation), and the melamine resin is “Nikarac MX-40” (trade name, manufactured by Sanwa Chemical Co., Ltd.). Using each electrodeposition paint, an aluminum plate treated with an anodized film was used as an anode and electrodeposited at 160 V DC for 150 seconds. Next, after rinsing with water, baking was performed at 180 ° C. for 30 minutes to form a cured coating film. Appearance, matte degree,
The gloss unevenness, weather resistance, acid resistance, yellowing resistance, adhesion and hardness were evaluated by the following methods. Table 2 shows the results. In Comparative Example 2, a practical cured coating film could not be formed.

Appearance: The surface of the coating film was visually observed to check for any abnormalities such as cissing, spots, and dents. ◎: No abnormality ：: Very slight abnormality △: Slight abnormality X: Severe abnormality Matte degree: Gloss due to 60 ° specular reflection was measured. Gloss unevenness: The coating film surface was visually observed to check for gloss unevenness. ：: No gloss unevenness ○: Very slight gloss unevenness △: Slight gloss unevenness ×: Equivalent gloss unevenness Weather resistance: 500 using a sunshine weatherometer
The gloss retention of the coating film after 0 hour was examined. ◎: 70% or more ○: 69 to 50% △: 49 to 30% ×: 29% or less

[0023] Acid resistance: The coated surface was visually observed after _{5% H 2 SO 4 (80} ℃) spot test 40 minutes, examined for spot traces. ：: No abnormality ：: Slight abnormality ：: Slight abnormality X: Severe abnormality Yellowing resistance: Color change of coating film appearance after baking at 200 ° C. for 30 minutes was visually observed. ：: No abnormalities ：: Very slight yellowing Δ: Slightly yellowing ×: Corresponding yellowing Adhesion: According to JIS K5400, a sticking test was performed at 1 mm intervals. ◎: 100/100 ○: 99/100 to 95/100 △: 94/100 to 90/100 ×: 89/100 to 0/100 Hardness: Pencil hardness test at 20 ° C. in accordance with JIS K5400 8.4 Implemented

[0024]

[Table 1]

[0025]

[Table 2] ────────────────────────────────── Comparative example ── ─────────────── 1 2 3 4 1 2 3 4 5 6 7 ──────────────────────外 観 Appearance ◎ ◎ ◎ ◎ ○ − △ ○ ◎ ◎ ◎ Matting degree 28 23 20 17 82 − 15 72 25 27 90 Matte unevenness ◎ ◎ ◎ ◎ △ − △ ○ ○ ◎ Glossy weather resistance ◎ ◎ ◎ ◎ ◎-○ ◎ ○ ○ ○ Acid resistance ◎ ◎ ◎ ◎ ◎-◎ ◎ ◎ ◎ △ Yellowing resistance ◎ ◎ ◎ ◎ ◎- − △ △ ◎ ◎ ◎ Hardness 3H 2H 3H 3H 3H − 3H HB 3H 3H 4H ──────────────────────────────── ──

As is evident from the data in Table 2, in each of the examples using the electrodeposition coating composition of the present invention, the matting degree, gloss unevenness, weather resistance, acid resistance, yellowing resistance, and adhesion were observed. Excellent coating films were obtained. On the other hand, in Comparative Example 1 using an acrylic copolymer containing no alkoxysilane group, no matte coating film was obtained. General formula-CONHC
In Comparative Example 2 using an acrylic copolymer containing no group represented by H ₂ OR, a practical cured coating film could not be formed. In Comparative Example 3 in which the amount of the aqueous fluorinated copolymer was small, the coating film appearance, weather resistance, and adhesion were reduced,
Conversely, in Comparative Example 4 in excess, no matte coating film was obtained. In Comparative Example 5 using an acrylic copolymer that did not use a copolymerizable cycloalkyl group-containing monomer, gloss unevenness and weather resistance were reduced. In Comparative Example 6 using an acrylic copolymer without a copolymerizable UV-stable monomer, the weather resistance was reduced. In Comparative Example 7, in which a melamine resin was used as a crosslinking agent without using an acrylic copolymer, a glossy coating film was obtained, and the acid resistance was poor.

[0027]

As described above, the electrodeposition coating composition of the present invention uses a binder composed of a specific aqueous fluorinated copolymer (A) and a specific acrylic copolymer (B). Therefore, the effect of improving the weather resistance by the component (A) and the component (B), the formation of a gel structure in the particle by the alkoxysilane group in the component (B), and the component (A) by the N-alkoxymethylamide group ), A self-crosslinking reaction between N-alkoxymethylamide groups and a self-crosslinking reaction between the N-alkoxymethylamide groups can provide a matte coating film without unevenness in gloss without separately adding a matting agent or a crosslinking agent. The film has excellent acid resistance and yellowing resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C09D 143/04 C09D 143/04 (72) Inventor Yuji Yamazaki 1920-1 Thinba, Otawara-shi, Tochigi Pref. (72) Inventor Masaharu Yamada Tochigi 1961-1 Usaba, Otawara-shi (72) Inventor, Mutsumi Takeishi 7-1414-41, Shimonagata, Nishinasuno-machi, Nasu-gun, Tochigi Prefecture (56) References JP-A-6-329962 (JP, A) JP-A-3-215544 (JP) JP-A-5-39445 (JP, A) JP-A-7-304954 (JP, A) JP-A-8-100138 (JP, A) JP-A-5-171100 (JP, A) (58) Surveyed field (Int.Cl. ⁷ , DB name) C09D 127/12 C09D 5/00 C09D 5/44 C09D 133/00-133/26 C09D 143/04

Claims (4)

(57) [Claims] (1) 40 to 80% by weight of an aqueous fluorinated copolymer having a carboxyl group and a hydroxyl group, (B) an alkoxysilane group, and a general formula -CONHCH ₂ O
Acrylic copolymer 60 having a group represented by R (where R is an alkyl group having 1 to 4 carbon atoms) and a cycloalkyl group, and containing an ultraviolet-stable monomer as a copolymerizable unsaturated monomer. A matte electrodeposition coating composition comprising a binder containing about 20% by weight. 2. The matte electrodeposition coating composition according to claim 1, wherein the component (A) is an aqueous fluorinated copolymer having an acid value of 5 to 150 and a hydroxyl value of 25 to 120. 3. The method according to claim 1, wherein the component (B) is 0.1 to 30% by weight of a copolymerizable unsaturated monomer having an alkoxysilane group, and a general formula CH ₂ ＣC (R ¹ ) CONHCH ₂ OR (where R is carbon Is an alkyl group having 1 to 4 alkyl groups, and R ¹ is a hydrogen atom or a methyl group), 5 to 50% by weight of an α, β-monoethylenically unsaturated monomer, a copolymerizable unsaturated monomer having a cycloalkyl group. Acrylic copolymer obtained from a copolymerizable unsaturated monomer mixture containing 5 to 80% by weight of a saturated monomer and 0.1 to 10% by weight of an ultraviolet light-stable monomer as essential components, with the balance being other copolymerizable unsaturated monomers. The matte electrodeposition coating composition according to claim 1, which is a union. 4. The UV-stable monomer has the general formula: Wherein R ₁ is a hydrogen atom or a cyano group, and R ₂ and R ₃ are each independently a hydrogen atom or a carbon atom
Two alkyl groups, X is an imino group or an oxygen atom, Y is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms or -C
_{(O) -C (R 2)} = C (R 3) H ( wherein, R _2, R ₃
Means the same as before). 4. The matte electrodeposition coating composition according to claim 1, which is a monomer represented by the following formula: