JP6904529B1 - A method for forming an aqueous resin composition containing an aluminum pigment, an aqueous electrodeposition resin solution, an aqueous electrodeposition coating film, a coating film, and an electrodeposition coating film. - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous resin composition containing an aluminum pigment, which has low VOC properties, is excellent in stability over time, is excellent in coating efficiency by electrodeposition coating, adhesion to an object to be coated, and concealment of a base. A water-based electrodeposition resin liquid composed of the water-based resin composition, a water-based electrodeposition coating material, having a metallic appearance (metallic feeling, gloss, color tone), and corrosion resistance (weather resistance, acid resistance, alkali resistance, solvent resistance, etc.) A coating film having excellent chemical resistance) and a method for forming the coating film are provided. SOLUTION: The (A) water-dispersible vinyl-based copolymer, (B) amino resin and (C) water-dispersible aluminum pigment are contained, and (A) the water-dispersible vinyl-based copolymer is used as a substituent. It is a (co) polymer having a carboxyl group, an acid value of 20 to 100 mgKOH, dispersibility in an aqueous solvent, and a carbon-carbon unsaturated bond (co) polymerized, and has a mass ratio (A). / (B) is 40/60 to 80/20, and the mass ratio (C) / {(A) + (B)} is 0.1 / 99.9 to 15/85. .. [Selection diagram] None

Description

The present invention relates to an aqueous resin composition containing an aluminum pigment, an aqueous electrodeposition resin solution comprising the aqueous resin composition, an aqueous electrodeposition coating material, and a metal material (such as aluminum, stainless steel, and various alloys) formed from the aqueous electrodeposition resin composition. The present invention relates to a coating film having excellent adhesion to an object to be coated made of a conductive material such as the above, and having a metallic and uniform appearance, and a coating method thereof.

Conventionally, an electrodeposition coating method has been studied in order to impart corrosion resistance and design to metal materials. The electrodeposition coating method has advantages such as excellent coating efficiency as compared with other coating methods, but its use is restricted in electrodeposition coating because pigments having a large specific density settle. In addition, a paint that easily imparts high brilliance and various design properties and that contains an aluminum pigment to obtain a metallic appearance is mainly formed by spray painting.
Although spray coating can obtain excellent designability, coating efficiency is poor and a large amount of VOC is generated. Therefore, in recent years, low VOC type coating materials have been desired.

As a method for solving the above problems, an electrodeposition coating material containing an aluminum pigment or the like has been studied for a long time (Patent Document 1).
However, since aluminum pigments having a large particle size of 1 μm to 100 μm ^{and a large specific gravity of 2.7 g / cm 3} tend to settle during electrodeposition coating, the appearance obtained by electrodeposition coating is the upper and lower parts of the object to be coated. In addition, the degree of coating (adhesion amount) of the aluminum pigment differs between the side surface and the top surface, and unevenness is likely to occur. In addition, there are many problems such as aluminum reacting with water in an aqueous system to generate hydrogen gas and deteriorating with time.
Subsequently, surface-treated aluminum pigments for suppressing the reaction between aluminum and water have been developed, and electrodeposition coating materials using them have been proposed (Patent Documents 2 and 3).
However, the same difference in the degree of coating (adhesion amount) as described above occurs, and it is not possible to obtain an appearance satisfying the metallic tone by concealing the base, or it is not possible to obtain a uniform metallic appearance.
Further, an anion electrodeposition coating material containing a leafing-shaped aluminum pigment that does not easily settle has been proposed (Patent Document 4), but the leaving-shaped aluminum pigment is suppressed from settling but easily floats on the liquid surface. There was a difference in the amount of aluminum pigment adhered between the upper part and the lower part of the object to be painted, the hiding property of the base was insufficient, and a sufficient metallic appearance could not be obtained.

As described above, there has never been an electrodeposition paint that uses an aluminum pigment and can obtain a sufficient metallic appearance.

Japanese Unexamined Patent Publication No. 48-051925 Japanese Unexamined Patent Publication No. 2006-137864 Japanese Unexamined Patent Publication No. 2015-187197 Japanese Unexamined Patent Publication No. 2007-138089

The present invention solves the above-mentioned problems in the prior art, has low VOC property, is excellent in stability over time, coating efficiency by electrodeposition coating, adhesion to an object to be coated, and hiding property of a base. An aqueous resin composition containing an aluminum pigment, an aqueous electrodeposition resin solution comprising the aqueous resin composition, an aqueous electrodeposition coating material, and a uniform film thickness and a uniform metallic tone formed from them. Aluminum with excellent appearance (metallic feeling, luster, color tone), adhesion, design, corrosion resistance (weather resistance and chemical resistance such as acid resistance, alkali resistance, solvent resistance), and stability over time. An object of the present invention is to provide a coating film containing a pigment and a method for forming the coating film.

As a result of diligent research, the present inventor has conducted electrodeposition coating by a constant current method using an aqueous resin composition containing a specific vinyl-based copolymer, an amino resin, and an aluminum pigment, and an aqueous resin composition obtained thereby. The present invention has been made by finding that the above problems can be overcome by forming an aluminum pigment-containing electrodeposited coating film having a metallic appearance.
The present invention is characterized by the following points.

1. 1. An aqueous resin composition containing (A) a water-dispersible vinyl-based copolymer, (B) an amino resin, and (C) a water-dispersible aluminum pigment.
The water-dispersible vinyl-based copolymer has a carboxyl group as a substituent, an acid value of 20 to 100 mgKOH, dispersibility in an aqueous solvent, and a carbon-carbon unsaturated bond (co). ) It is a polymerized (co) polymer,
The mass ratio (A) / (B) is 40/60 to 80/20.
An aqueous resin composition having a mass ratio (C) / {(A) + (B)} of 0.1 / 99.9 to 15/85.
2. The water-dispersible aluminum pigment comprises a surface-treated aluminum pigment.
The surface of the surface-treated aluminum pigment is characterized by containing one kind selected from the group consisting of an inorganic phosphorus-based compound, a molybdenum-based compound, a silicon-based compound, and an organic resin, or a combination of two or more kinds. The aqueous resin composition according to the above.
3. 3. An aqueous electrodeposition resin liquid comprising the aqueous resin composition according to 1 or 2 above. 4. An aqueous electrodeposition coating material comprising the aqueous electrodeposition resin solution according to 3 above.
5. An electrodeposition coating film formed from the water-based electrodeposition coating material according to 4 above, which has a metallic appearance.
6. A method for forming an electrodeposition coating film, which comprises electrodepositing the aqueous electrodeposition resin liquid according to 3 above or the aqueous electrodeposition coating material according to 4 above by a constant current method.

According to the present invention, it is extremely useful in industry because a low VOC coating process can be realized, and an aluminum pigment having excellent stability, coating efficiency by electrodeposition coating, adhesion to a metal material, and concealment of a base is excellent. A water-based resin composition containing the above, an water-based resin composition composed of the water-based resin composition, and an aluminum pigment formed from the water-based resin composition, which has a metallic appearance, and has adhesiveness, designability, and corrosion resistance. , A coating film having excellent stability over time, and a method for forming the coating film can be provided.

The present invention will be described in more detail.
The present invention relates to a low VOC water-based resin composition containing an aluminum pigment, a water-based resin liquid composed of the water-based resin composition, a water-based electrodeposition coating material composed of the water-based resin liquid, and a metallic tone formed from the water-based resin composition. The present invention relates to a coating film having the appearance of the above, which is uniform and has excellent stability over time, and a method for forming the coating film.

<Aqueous resin composition>
The aqueous resin composition of the present invention contains (A) a water-dispersible vinyl copolymer, (B) an amino resin, and (C) a water-dispersible aluminum pigment as active ingredients (solid content, non-solvent component). Is preferable.
Then, if necessary, (D) a neutralizing agent and (E) an aqueous solvent can be further contained.

In addition, a light stabilizer is added to further contain pigments, dyes, fillers, etc. so that the coating film has a design property, and to improve workability at the time of forming the coating film and to impart various functions to the coating film. , Various additives such as antioxidants, wetting agents, leveling agents, defoaming agents, and other resins such as urethane resin and epoxy resin can be further contained.

The mass ratio (A) / (B) of the (A) water-dispersible vinyl-based copolymer and the (B) amino resin in the aqueous resin composition of the present invention is preferably 40/60 to 80/20. More preferably, 50/50 to 75/25.
When the mass ratio (A) / (B) is less than the above range, the water dispersibility of the (A) water-dispersible vinyl copolymer and (B) amino resin, which are the resin components, in the aqueous resin composition. (Water solubility or emulsifying property) is lowered, liquid separation and sedimentation are likely to occur, the hardness of the coating film is likely to be insufficient, and the production cost is greatly increased.
If the mass ratio (A) / (B) is larger than the above range, it becomes difficult to obtain sufficient coating film performance (chemical resistance, coating film hardness).

Total mass ratio of (C) water-dispersible aluminum pigment, (A) water-dispersible vinyl copolymer and (B) amino resin in the aqueous resin composition of the present invention (C) / {(A) + (B)} is preferably 0.1 / 99.9 to 15/85, and more preferably 5/95 to 11/89.
If it is less than the above range, it is difficult to obtain a coating film having a sufficient metallic appearance (metallic feeling), and if it is larger than the above range, the coating film performance and alkali resistance deteriorate, and the manufacturing cost increases remarkably. ..

[(A) Water-dispersible vinyl copolymer]
The water-dispersible vinyl-based copolymer (A) is a vinyl-based copolymer that is soluble in an aqueous solvent or emulsible in an aqueous solvent so that it can be dispersed in an aqueous solvent.
The main skeleton of the (A) water-dispersible vinyl-based copolymer is mainly formed by (co) polymerization of polymerizable carbon-carbon unsaturated bond groups such as a polymerizable carbon-carbon double bond or a triple bond. ing.
Specific examples of the carbon-carbon unsaturated bond group include a vinyl group, an allyl group, a (meth) acrylic group, an αβ unsaturated carbonyl group and the like, which may be polymerized alone or in combination of two or more. It may be polymerized.

The water-dispersible vinyl-based copolymer (A) preferably has a carboxyl group as a substituent. Then, it may further have a carboxylic acid ester group and / or a hydroxyl group.
By having the above-mentioned substituent, the water-dispersible vinyl-based copolymer (A) can easily have excellent water dispersibility.
By having a hydroxyl group and / or a carboxyl group, the (A) water-dispersible vinyl-based copolymer can form a crosslink with the (B) amino resin, and the coating film has corrosion resistance (weather resistance, chemical resistance). (Sex), high hardness, etc. can be imparted.

The water-dispersible vinyl-based copolymer (A) preferably has an acid value of 20 to 100 mgKOH, and more preferably 30 to 80 mgKOH. If it is less than the above range, it tends to be difficult to obtain sufficient water dispersibility, and if it is higher than the above range, water resistance tends to decrease, it becomes difficult to obtain sufficient coating film performance, and surface-treated water dispersion. It tends to reduce the stability of the aluminum pigment. In the present invention, the acid value was measured according to JIS K5601-2-1.

The water-dispersible vinyl-based copolymer as described above has a monomer having a polymerizable carbon-carbon unsaturated bond group and a carboxyl group, and a polymerizable carbon-carbon unsaturated bond group, a carboxyl group and a hydroxyl group. A group consisting of a monomer, a monomer having a polymerizable carbon-carbon unsaturated bond group and a carboxylic acid ester group, and a monomer having a polymerizable carbon-carbon unsaturated bond group, a carboxylic acid ester group and a hydroxyl group. It can be obtained by (co) polymerizing one kind or a combination of two or more kinds selected from the above.
Further, as a copolymerization component, another monomer having a polymerizable carbon-carbon unsaturated bond group can also be used in combination.

Specific examples of the monomer having a polymerizable carbon-carbon unsaturated bond group and a carboxyl group include acrylic acid, α-chloroacrylic acid, methacrylic acid, itaconic acid, maleic anhydride, maleic acid, fumaric acid, and crotonic acid. Acids, citraconic acid, methacrylic acid and the like can be mentioned, and one or a combination of two or more selected from these groups can be used. Among the above, acrylic acid is preferable.

As the monomer having a polymerizable carbon-carbon unsaturated bond group and a carboxylic acid ester group, an alkyl group having up to about 20 carbon atoms, a (meth) acrylate having an alicyclic hydrocarbon group, or the like is preferably used. Examples include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, normal butyl acrylate, normal butyl methacrylate, normal hexyl acrylate, normal hexyl methacrylate, normal heptyl. Examples thereof include acrylate, normal heptyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, normal lauryl acrylate, normal lauryl methacrylate, stearyl acrylate, stearyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate and the like. One kind or two or more kinds selected from these groups can be used in combination.
Among the above, it is preferable to use a combination of methyl methacrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate.

Specific examples of the monomer having a polymerizable carbon-carbon unsaturated bond group, a carboxylic acid ester group and a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate and 2-hydroxypropyl. Examples thereof include methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, diethylene glycol monoacrylate, cyclohexanedimethanol monoacrylate, cyclohexanedimethanol monomethacrylate, and the like. One selected type or a combination of two or more types can be used.
Among the above, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl It is preferable to use one kind or a combination of two or more kinds selected from the group consisting of methacrylate. Among the above, 2-hydroxyethyl acrylate is preferable.

Specific examples of other monomers having a polymerizable carbon-carbon unsaturated bond group include a vinyl-based monomer having an aromatic group, a copolymerizable vinyl-based monomer having an N-alkoxyalkylamide group, and the like. Examples thereof include macromonomers, acrylonitriles, vinyl acetates, and allyl group-containing compounds which are polymers having a vinyl group at the end, and one or a combination of two or more selected from these groups can be used.

Specific examples of the vinyl-based monomer having an aromatic group include styrene, α-methylstyrene, α-chlorostyrene, vinyltoluene and the like, and one or a combination of two or more selected from these groups can be mentioned. Can be used. Among the above, styrene is preferable.

Specific examples of the copolymerizable vinyl-based monomer having an N-alkoxyalkylamide group include N-methoxymethylacrylamide, N-ethoxymethylacrylamide, N-normalbutoxymethylacrylamide, N-isobutoxymethylacrylamide, and N-. Examples thereof include methoxymethylmethacrylate, N-ethoxymethylmethacrylate, N-normalbutoxymethylmethacrylate, N-isobutoxymethylmethacrylate, etc., and one or a combination of two or more selected from these groups can be used. can.

When synthesizing a (co) polymer by (co) polymerizing the above (co) polymerization components, it is preferable to synthesize in various aqueous solvents, and various polymerization initiators are used as necessary. Can be done.

Specific examples of the aqueous solvent include water, alcohols, ethylene glycol ethers, and propylene glycol ethers, and one or a combination of two or more selected from these groups can be used, but the present invention is limited to these. Not done.
Among the above, isopropanol, ethylene glycol mononormal butyl ether and the like are preferably used.

It is preferable to use a radical initiator as the polymerization initiator.
Specific examples of the radical initiator include dihalogen compounds, azo compounds, organic peroxides, redox initiators, and the like, and one or a combination of two or more selected from these groups can be used. Not limited.
Among the above, azo compounds are preferably used, and among the azo compounds, 2,2'-azobisisobutyronitrile, 2,2'-azobisiso (2-methylbutyronitrile), and 2,2'-azobis (2). , 4-Dimethylvaleronitrile) is preferably used.

[(B) Amino resin]
As a specific example of the (B) amino resin, one kind or a combination of two or more kinds selected from the group consisting of a melamine resin, a benzoguanamine resin, and a urea resin can be used.
In particular, it is preferable to use a melamine resin, and among the melamine resins, it is more preferable to contain an alkoxylated melamine in which at least a part of the methylol group is alkoxylated with a lower alcohol.
As the lower alcohol, it is preferable to use one or a combination of two or more selected from the group consisting of methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol and isobutyl alcohol.
The amino resin (B) can be cured by heating, and a compound having a hydroxyl group or a carboxyl group may be used as a curing agent, or various curing accelerators may be used.

[(C) Water-dispersible aluminum pigment]
(C) The water-dispersible aluminum pigment is an aluminum pigment having excellent dispersibility in an aqueous solvent. Since the water-dispersible aluminum pigment is contained in the coating film, it is possible to exhibit a metallic appearance with a three-dimensional effect.
The water-dispersible aluminum pigment is an aluminum pigment that is excellent in being uniformly dispersed in an aqueous solvent as a powder.
(C) The water-dispersible aluminum pigment is a pigment obtained by treating the surface of aluminum powder with a surface treatment agent, and the formed surface treatment surface suppresses the reaction between metallic aluminum and water, which is excellent. Water dispersibility is obtained.
The water-dispersible aluminum pigment (C) is preferably used in the form of a paste having an aluminum powder content of 40 to 60% by mass.

Metallic aluminum reacts with water to generate aluminum hydroxide and hydrogen gas. When such a reaction proceeds, the aluminum pigment impairs the metallic appearance, and the aqueous resin composition containing the aluminum pigment foams, agglomerates of the aluminum pigment are derived, the viscosity changes, and the stability with time is changed. Decreases. Further, the coating film formed from the aqueous resin composition also impairs the metallic appearance and the stability with time is lowered.

(C) The shape of the particles of the water-dispersible aluminum pigment is preferably scaly because it is spread in the coating film and has an effect of concealing the base.
Further, since the leafing type conventionally used for electrodeposition applications is easily suspended and inferior in concealing property, the non-leafing type that can be uniformly dispersed and arranged in the coating film is more preferable.

The average particle size of the water-dispersible aluminum pigment (C) is preferably 7 to 50 μm, more preferably 7 to 20 μm, and more preferably 7 to 15 μm for general coating applications and 7 to 20 μm for aqueous resin composition applications. If it is smaller than the above range, the performance does not change much even though it is difficult to obtain, and if it is larger than the above range, (C) the water-dispersible aluminum pigment has a ^{large specific gravity of about 2.7 g / cm 3} , so its own weight. Is likely to cause sedimentation due to.
Specific examples of the compound constituting the surface of the (C) water-dispersible aluminum pigment include inorganic phosphorus compounds, molybdenum compounds, silicon compounds, organic resins and the like, and one or two selected from these groups A combination of seeds and above can be used. In particular, a hybrid of an organic silicon compound and an organic resin is preferable.

Commercially available surface treatment agents can be used, and examples thereof include inorganic phosphorus-based surface treatment agents, molybdenum-based surface treatment agents, silicon-based surface treatment agents, and organic resin-based surface treatment agents. One selected type or a combination of two or more types can be used.
It is preferable to use two or more types of surface treatment agents in combination rather than one type alone, and in particular, a combination of a silicon-based surface treatment agent and an organic resin-based surface treatment agent is preferable.

Phosphoric acid and the like are specific examples of the inorganic phosphorus-based surface treatment agent, ammonium molybdate, polymolybdate and the like are specific examples of the molybdate-based surface treatment agent, and alkoxysilane and the like are specific examples of the silicon-based surface treatment agent. Can be mentioned.

The organic resin-based surface treatment agent can contain various resins, and the contained resin may contain either or both of a thermoplastic resin and a thermosetting resin, but produces a solid three-dimensional crosslinked structure. It is preferable to contain a thermosetting resin that is insoluble and infusible.

Specific examples of the thermoplastic resin include acrylic acid ester copolymers, polyester resins, polyethylene resins, polystyrene resins and the like.
Specific examples of the thermosetting resin include acrylic acid ester copolymers, epoxy resins, polyurethane resins, and the like, and one or a combination of two or more selected from these groups can be used. Among the above, it is more preferable to contain an acrylic acid ester copolymer capable of forming a three-dimensional crosslinked structure.

Specific examples of the commercially available (C) water-dispersible aluminum pigment include an aqueous polypaste manufactured by Toyo Aluminum Co., Ltd., and depending on the treatment method, WXM series (treatment with an inorganic phosphoric acid compound-based treatment agent), WL series (treatment with molybdenum-based treatment agent), EMR series (treatment with organic silicon-based treatment agent), BP series (treatment with acrylic resin coating treatment agent), WRA series (hybrid with acrylic resin coating agent and organic silicon-based treatment agent) Treatment) and the like are on the market, and one kind or two or more kinds selected from these groups can be used in combination, but the present invention is not limited to these.

[(D) Neutralizer]
The aqueous resin composition of the present invention can contain (A) a neutralizing agent for neutralizing the carboxyl group of the water-dispersible vinyl-based copolymer.

The neutralizer (D) preferably contains organic amines.
Specific examples of organic amines include alkylamines, alkanolamines, alkylenepolyamines, alkyleneimines, cyclic amines, etc., and one or a combination of two or more selected from these groups may be used. However, it is not limited to these. Among the above, it is more preferable to contain alkanolamines.

Specific examples of alkylamines include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, monobutylamine, dibutylamine, tributylamine and the like. One or a combination of two or more selected from the group can be used, but is not limited thereto.

Specific examples of alkanolamines include monoethanolamine, diethanolamine, triethanolamine, mono (2-hydroxypropyl) amine, di (2-hydroxypropyl) amine, tri (2-hydroxypropyl) amine, dimethylaminoethanol, and the like. Examples thereof include diethylaminoethanol, and one or a combination of two or more selected from these groups can be used, but the present invention is not limited thereto.

Specific examples of the alkylene polyamines include ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine and the like, and one or a combination of two or more selected from these groups can be used, but the present invention is not limited thereto.

Specific examples of the alkyleneimines include ethyleneimine, propyleneimine, and the like, and one or a combination of two or more selected from these groups can be used, but the alkyleneimines are not limited thereto.

Specific examples of cyclic amines include piperazine, morpholine, pyrazine, pyridine and the like, and one or a combination of two or more selected from these groups can be used, but the cyclic amines are not limited thereto.

These organic amines are oriented toward the carboxyl group of the (A) water-dispersible vinyl-based copolymer and chloride to form an emulsifying property of the (A) water-dispersible vinyl-based copolymer in an aqueous solvent. Alternatively, the water solubility can be increased to enhance the dispersibility in an aqueous solvent.

The content of the (D) neutralizing agent in the aqueous resin composition is a molar ratio of the amino group of the organic amines and the carboxyl group of the (A) water-dispersible vinyl-based copolymer. The ratio is preferably 0.3 to 0.9, more preferably 0.4 to 0.7.
If it is higher than the above range, the stability of the water-dispersible aluminum pigment is lowered due to the increase in the alkaline component, and if it is lower than the above range, the water solubility or emulsifying property of the (A) water-dispersible vinyl copolymer is enhanced. The effect tends to be insufficient

[(E) Aqueous solvent]
The aqueous resin composition preferably contains (E) an aqueous solvent when the (A) water-dispersible vinyl copolymer is a solid or a high-viscosity liquid.
The (E) aqueous solvent is an aqueous solvent, and specific examples thereof include water, alcohols, ethylene glycol ethers, and propylene glycol ethers, and one or a combination of two or more selected from these groups. However, the present invention is not limited to these.

Specific examples of alcohols include methanol, ethanol, normal propanol, isopropanol, normal butanol, isobutanol, normal hexyl alcohol, 2-ethylhexyl alcohol, benzyl alcohol and the like, and one or two selected from these groups. The above can be used in combination, but the present invention is not limited to these.

Specific examples of ethylene glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mononormal propyl ether, ethylene glycol monoisopropyl ether, ethylene glycol mononormal butyl ether, ethylene glycol monoisobutyl ether, and ethylene glycol monotasha. Examples thereof include rebutyl ether, ethylene glycol mononormal hexyl ether, ethylene glycol mononormal octyl ether, ethylene glycol mono-2-ethylhexyl ether, and one or a combination of two or more selected from these groups can be used. , Not limited to these.

Specific examples of propylene glycol ethers include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mononormal propyl ether, propylene glycol monoisopropyl ether, propylene glycol mononormal butyl ether, propylene glycol monoisobutyl ether, and propylene glycol monotasha. Examples thereof include rebutyl ether, propylene glycol mononormal hexyl ether, propylene glycol mononormal octyl ether, propylene glycol mono2-ethylhexyl ether and the like, and one or a combination of two or more selected from these groups can be used. Not limited to these.

The content of the (E) aqueous solvent in the aqueous resin composition is preferably 1 to 10% by mass, more preferably 2 to 8% by mass.

<Aqueous electrodeposition resin liquid>
The aqueous electrodeposition resin liquid of the present invention is an electrodeposited resin liquid comprising the aqueous resin composition of the present invention, and an electrodeposition film can be formed by electrodeposition.
The composition of the aqueous electrodeposition resin liquid may be the same as that of the aqueous resin composition, and other components may be further contained if necessary.

<Aqueous electrodeposition paint>
The water-based electrodeposition coating material of the present invention is a coating material made of the water-based electrodeposition resin liquid of the present invention, and an electrodeposition coating film can be formed by electrodeposition coating.
The composition of the water-based electrodeposition coating material may be the same as that of the water-based electrodeposition resin liquid, and other components may be further contained if necessary.

<Electrodeposition coating>
The electrodeposition coating film of the present invention is a coating film formed by electrodeposition coating of the water-based resin composition, the water-based electrodeposition resin liquid, or the water-based electrodeposition coating material of the present invention on an object to be coated, and is metallic. Has the appearance of.
The electrodeposition coating is preferably electrodeposition coating by a constant current method.
The above-mentioned object to be coated is not particularly limited as long as it is a conductive material, but a metal material (particularly, aluminum, stainless steel and various alloys) is preferable.

<Method for forming electrodeposition coating film>
The electrodeposition coating film forming (electrodeposition coating) method of the present invention is a forming method of electrodeposition coating using the aqueous resin composition, the aqueous electrodeposition resin liquid or the aqueous electrodeposition coating material of the present invention.
The electrodeposition coating is preferably performed by a constant current method.
Further, the electrodeposition coating is preferably performed by anion electrodeposition coating in which the object to be coated is used as an anode and the electrode is used as a cathode.
Anionic electrodeposition coating is more advantageous than cationic electrodeposition coating in that the coating color is more stable and the baking temperature can be lowered.
The water-dispersible aluminum pigment (C) contained in the aqueous resin composition of the present invention has a ^{large specific gravity of about 2.7 g / cm 3} and easily settles during electrodeposition coating. It is preferable to increase the applied voltage so that a predetermined film thickness can be obtained in a short time.

In the stage of the film formation process in electrodeposition coating by the constant current method, a relatively low voltage is applied in the initial stage of film formation, and a relatively high voltage is applied as the film thickness increases and the film resistance increases. Is preferably applied. By changing the applied voltage according to the film thickness in this way, it is possible to perform electrodeposition coating with a constant current, suppress the occurrence of film thickness unevenness, and obtain a uniform metallic appearance.

On the other hand, in the case of electrodeposition coating by the constant voltage method, the current value decreases or slows down as the film resistance increases, and it is difficult to easily obtain a predetermined film thickness even in high voltage processing, or energization in the latter half. However, since a coating film containing no aluminum pigment is formed, lack of metallic appearance and unevenness are likely to occur.

As a specific condition of the forming method for electrodeposition coating by the constant current method, for example, the applied voltage is preferably 100 to 250 V, more preferably 150, for ^{a surface area of 100 cm 2 of the object to be electrodeposited.} The current density is preferably maintained at 1.0 to 6.0 mA / cm ² , more preferably 2.0 to 4.0 mA / cm ² , and the energization time is preferably 0. Electrodeposition coating may be performed in 10 minutes to 0.50 minutes, more preferably 0.20 to 0.30 minutes.
The electrodeposited object to be coated is washed with water and then heated at 150 to 250 ° C. for 15 to 60 minutes to remove the solvent, and the electrodeposition coating film is cured by cross-linking to obtain excellent corrosion resistance and hardness. The electrodeposited coating film to have is formed.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited thereto.

The (B) amino resin and (C) water-dispersible aluminum pigment used in the examples are as follows.
[(B) Amino resin]
-Amino resin 1: Melamine resin Cymel 232 manufactured by Ornex Japan Co., Ltd., 100% active ingredient.
[(C) Water-dispersible aluminum pigment]
-Water-dispersible aluminum pigment 1: WRA-5660 manufactured by Toyo Aluminum K.K. The active ingredient is 50%, and the surface contains a hybrid composition composed of an acrylic resin and a silicon-based compound. Scale-like, non-reefing type. Average particle size 10 μm.
-Water-dispersible aluminum pigment 2: EMR-D5620 manufactured by Toyo Aluminum K.K., 60% active ingredient, and the surface contains a silicon compound. Scale-like, non-leafing type Average particle size 17 μm.
-Water-dispersible aluminum pigment 3: BP-6360J manufactured by Toyo Aluminum K.K. The active ingredient is 50%, and the surface contains acrylic resin. Scale-like, non-reefing type. Average particle size 10 μm.

<(A) Production of water-dispersible vinyl copolymer>
[Synthesis Example 1]
The following raw materials were charged into a 3-liter four-necked flask equipped with a stirrer, a reflux condenser and a nitrogen introduction tube, and the temperature was raised to 90 ° C.
Isopropanol 12 parts by mass Ethylene glycol mononormal butyl ether 8 parts by mass Separately from the above, a mixed solution of the following raw materials was charged into a dropping funnel and dropped into the flask over 120 minutes. Here, 2,2'-azobisisobutyronitrile acts as a polymerization initiator.
Isopropanol 5 parts by mass Ethylene glycol mononormal butyl ether 13 parts by mass Acrylic acid 5 parts by mass 2-Hydroxyethyl acrylate 15 parts by mass Stylus 10 parts by mass 2-Ethylhexyl acrylate 10 parts by mass Ethyl acrylate 10 parts by mass Butyl acrylate 10 parts by mass Methyl methacrylate 40 parts by mass Part 2,2'-Azobisisobutyronitrile 1 part by mass After the above dropping was completed, the following mixture was further added 3 times every 30 minutes.
Isopropanol 0.4 parts by mass 2,2'-azobisisobutyronitrile 0.2 parts by mass Then, the reaction was continued at 90 ° C. for 90 minutes, and the water-dispersible vinyl copolymer solution 1 (solid content 72.2) was continued. Mass%, acid value of solid content 38.3 mgKOH.) Was obtained.

[Synthesis Example 2]
The following was placed in a 3-liter four-necked flask equipped with a stirrer, a reflux condenser and a nitrogen introduction tube, and the temperature was raised to 90 ° C.
Isopropanol 12.0 parts by mass Ethylene glycol mononormal butyl ether 8.0 parts by mass Separately from the above, the following mixed solution was charged into a dropping funnel and dropped into the flask over 120 minutes.
Isopropanol 5 parts by mass Ethylene glycol mononormal butyl ether 13 parts by mass Acrylic acid 7 parts by mass 2-Hydroxyethyl acrylate 15 parts by mass Stylus 10 parts by mass 2-Ethylhexyl acrylate 10 parts by mass Ethyl acrylate 10 parts by mass Butyl acrylate 10 parts by mass Methyl methacrylate 38 parts by mass Part 2,2'-Azobisisobutyronitrile 1 part by mass After completion of the dropping, the following mixture was further added 3 times every 30 minutes.
Isopropanol 0.4 parts by mass 2,2'-azobisisobutyronitrile 0.2 parts by mass Then, the reaction was continued at 90 ° C. for 90 minutes, and the water-dispersible vinyl copolymer solution 2 (solid content 72.2) was continued. Mass%, acid value of solid content 53.6 mgKOH.) Was obtained.

[Synthesis Example 3]
The following was placed in a 3-liter four-necked flask equipped with a stirrer, a reflux condenser and a nitrogen introduction tube, and the temperature was raised to 90 ° C.
Isopropanol 12 parts by mass Ethylene glycol mononormal butyl ether 8 parts by mass Separately from the above, the following mixed solution was charged into a dropping funnel and dropped into the flask over 120 minutes.
Isopropanol 5 parts by mass Ethylene glycol mononormal butyl ether 13 parts by mass Acrylic acid 2 parts by mass 2-Hydroxyethyl acrylate 15 parts by mass styrene 10 parts by mass 2-Ethylhexyl acrylate 10 parts by mass Ethyl acrylate 10 parts by mass Butyl acrylate 10 parts by mass Methyl methacrylate 43 parts by mass Part 2,2'-Azobisisobutyronitrile 1 part by mass After completion of the dropping, the following mixture was further added 3 times every 30 minutes.
Isopropanol 0.4 parts by mass 2,2'-azobisisobutyronitrile 0.2 parts by mass Further, the reaction was continued at 90 ° C. for 90 minutes, and the water-dispersible vinyl copolymer solution 3 (solid content 72.2% by mass) was continued. , The acid value of the solid content was 15.3 mgKOH.).

[Synthesis Example 4]
The following was placed in a 3-liter four-necked flask equipped with a stirrer, a reflux condenser and a nitrogen introduction tube, and the temperature was raised to 90 ° C.
Isopropanol 12 parts by mass Ethylene glycol mononormal butyl ether 8 parts by mass Separately from the above, the following mixed solution was charged into a dropping funnel and dropped into the flask over 120 minutes.
Isopropanol 5 parts by mass Ethylene glycol mononormal butyl ether 13 parts by mass Acrylic acid 14 parts by mass 2-Hydroxyethyl acrylate 15 parts by mass Stylus 10 parts by mass 2-Ethylhexyl acrylate 10 parts by mass Ethyl acrylate 10 parts by mass Butyl acrylate 10 parts by mass Methyl methacrylate 31 parts by mass Part 2,2'-Azobisisobutyronitrile 1 part by mass After completion of the dropping, the following mixture was further added 3 times every 30 minutes.
Isopropanol 0.4 parts by mass 2,2'-azobisisobutyronitrile 0.2 parts by mass Further, the reaction was continued at 90 ° C. for 90 minutes, and the water-dispersible vinyl copolymer solution 4 (solid content 72.2% by mass) was continued. , The acid value of the solid content was 107.2 mgKOH.).

[Example 1]
(Production of water-based resin composition (water-based electrodeposition resin liquid))
The water-dispersible vinyl copolymer solution 1 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 1.
Water-dispersible vinyl-based copolymer solution 1 90.0 parts by mass Amino resin 1 35.0 parts by mass Didimethylaminoethanol 1.2 parts by mass Deionized water 123.8 parts by mass Here, the water-dispersible vinyl in the stock solution 1 The concentration of the system copolymer 1 is 90 × 0.722 / (90 + 35 + 1.2 + 123.8) × 100 = 25.99% by mass.
The concentration of the amino resin 1 in the stock solution 1 is 35 / (90 + 35 + 1.2 + 123.8) × 100 = 14.00% by mass.
Further, the reaction was continued at 90 ° C. for 90 minutes to obtain an aqueous dispersible vinyl copolymer solution 1 (solid content 72.2% by mass, acid value 38.3 mgKOH of solid content).
Then, deionized water is charged into another container at the following ratio, the stock solution 1 obtained above is added while stirring, and then butyl cellosolve and dimethylaminoethanol are added to homogenize the mixture for electrodeposition coating. Diluted solution 1 (active ingredient 8%) was obtained.
Deionized water 789.4 parts by mass Stock solution 1 200.0 parts by mass Butyl cellosolve 10.0 parts by mass dimethylaminoethanol 0.6 parts by mass Here, the concentration of the water-dispersible vinyl copolymer 1 in the stock solution 1 is 200. × 0.2599 / (789.4 + 200 + 10 + 0.6) × 100 = 5.20% by mass.
The concentration of the amino resin 1 in the stock solution 1 is 200 × 0.14 / (789.4 + 200 + 10 + 0.6) × 100 = 2.80% by mass.
The obtained diluent 1 for electrodeposition coating material and the water-dispersible aluminum pigment 1 were mixed and stirred at the following ratios to obtain an aqueous resin composition (aqueous electrodeposition resin solution) 1.
Diluting Liquid for Electrodeposition Paint 1 100 parts by mass Water-dispersible aluminum pigment 1 1 part by mass Here, the water-dispersible vinyl copolymer 1 / amino resin 1 / water-dispersible aluminum pigment 1 in the aqueous resin composition. Since the mass ratio is 5.20 / 2.80 / 1 × 0.5, the following mass ratio is calculated.
Water-dispersible vinyl copolymer 1 / amino resin 1 = 5.20 / 2.80 = 65.0 / 35.0.
Water-dispersible aluminum pigment 1 / (water-dispersible vinyl copolymer 1 + amino resin 1) = 6.3 / 100.0
In addition, each mass% in the solid content of the aqueous resin composition is calculated as follows.
Water-dispersible vinyl copolymer 1: 5.20 / (5.20 + 2.80 + 0.5) × 100 = 61.2% by mass.
Amino resin 1: 2.80 / (5.20 + 2.80 + 0.5) × 100 = 32.9% by mass.
Water-dispersible aluminum pigment 1: 0.5 / (5.20 + 2.80 + 0.5) × 100 = 5.9% by mass.

(Formation of coating film)
Using the aqueous resin composition 1 and the following object to be coated and the cathode, a voltage was applied between the two poles by the constant current method under the following conditions to perform constant voltage anion electrodeposition coating. As the applied voltage, a low voltage was initially applied so that the current density in the following range could be maintained, and a high voltage was applied as the electrical resistance of the coating film increased.
Object to be coated: An A1100 plate having a thickness of 1 mm, which was pickled after being degreased with alkali, was bent into a U shape to have a shape having an upper surface portion, a side surface portion, and a lower surface portion.
Cathode: 18-8 stainless steel plate Bath temperature: 20 ° C
Current density: 3.0mA / cm ²
Energization time: 10 seconds Next, after taking out the electrodeposited object to be coated and thoroughly washing it with water, it is heated at a temperature of 170 ° C. for 20 minutes to dry and cure (baking and drying) the electrodeposited coating film. , An electrodeposition coating film having a metallic appearance was obtained.
Then, various evaluations were performed, and the above calculation results and various evaluation results are shown in Table 2.

[Example 2]
The water-dispersible vinyl copolymer solution 2 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 2.
Water-dispersible vinyl copolymer solution 2 90.0 parts by mass Amino resin 1 35.0 parts by mass Didimethylaminoethanol 1.7 parts by mass Deionized water 123.3 parts by mass Then, in another container at the following ratio. Deionized water was charged, and the undiluted solution 2 obtained above was added while stirring, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the mixture to obtain a diluted solution 2 for electrodeposition paint (active ingredient 8%). rice field.
Deionized water 789.1 parts by mass Stock solution 2 200.0 parts by mass Butyl cellosolve 10.0 parts by mass dimethylaminoethanol 0.9 parts by mass The obtained diluent 2 for electrodeposition coating and water-dispersible aluminum pigment 1 are mixed in the following proportions. The mixture was mixed and stirred to obtain an aqueous resin composition (aqueous electrodeposition resin solution) 2.
Diluting liquid for electrodeposition coating 2 100 parts by mass Water-dispersible aluminum pigment 1 1 part by mass The electrodeposition coating film is applied in the same manner as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin solution) 2 is used. It was formed and evaluated in the same manner.

[Example 3]
The water-dispersible vinyl copolymer solution 2 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 3.
Water-dispersible vinyl copolymer solution 2 83.1 parts by mass Amino resin 1 40.0 parts by mass Didimethylaminoethanol 1.5 parts by mass Deionized water 125.4 parts by mass And in another container at the following ratio Deionized water was charged, and the undiluted solution 3 obtained above was added while stirring, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the mixture to obtain a diluted solution 3 for electrodeposition paint (active ingredient 8%). rice field.
Deionized water 789.2 parts by mass Stock solution 3 200.0 parts by mass Butyl cellosolve 10.0 parts by mass dimethylaminoethanol 0.8 parts by mass The obtained diluent 3 for electrodeposition coating and water-dispersible aluminum pigment 1 are mixed in the following proportions. 3 was mixed and stirred to obtain an aqueous resin composition (aqueous electrodeposition resin solution) 3.
Diluting liquid for electrodeposition coating material 3 100 parts by mass Water-dispersible aluminum pigment 1 1 part by mass The electrodeposition coating film is applied in the same manner as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin solution) 3 is used. It was formed and evaluated in the same manner.

[Example 4]
The water-dispersible vinyl copolymer solution 1 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 4.
Water-dispersible vinyl copolymer solution 1 66.4 parts by mass Amino resin 1 58.6 parts by mass Didimethylaminoethanol 0.9 parts by mass Deionized water 124.1 parts by mass Then, in another container at the following ratio. Deionized water was charged, and the undiluted solution obtained above was added while stirring, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the mixture to obtain a diluted solution 4 (active ingredient 8%) for electrodeposition coating. ..
Deionized water 789.4 parts by mass Undiluted solution 4 200.0 parts by mass Butyl cellosolve 10.0 parts by mass Dimethylaminoethanol 0.6 parts by mass The obtained diluent 4 for electrodeposition coating and water-dispersible aluminum pigment 1 are mixed in the following proportions. Aqueous resin composition (aqueous electrodeposition resin solution) 4 was obtained by mixing and stirring with.
Diluting liquid for electrodeposition coating material 4 100 parts by mass Water-dispersible aluminum pigment 1 1 part by mass The electrodeposition coating film is applied in the same manner as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin solution) 2 is used. It was formed and evaluated in the same manner.

[Example 5]
The water-dispersible vinyl copolymer solution 1 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 5.
Water-dispersible vinyl copolymer solution 1 90.0 parts by mass Amino resin 1 35.0 parts by mass Didimethylaminoethanol 1.2 parts by mass Deionized water 123.8 parts by mass Then, in another container at the following ratio. Deionized water was charged, and the undiluted solution 5 obtained above was added while stirring, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the mixture to obtain a diluted solution 5 (active ingredient 8%) for electrodeposition coating. rice field.
Deionized water 789.4 parts by mass Undiluted solution 4 200.0 parts by mass Butyl cellosolve 10.0 parts by mass Dimethylaminoethanol 0.6 parts by mass The obtained diluent 5 for electrodeposition coating and water-dispersible aluminum pigment 2 are mixed in the following proportions. Aqueous resin composition (aqueous electrodeposition resin solution) 5 was obtained by mixing and stirring with.
Diluting liquid for electrodeposition paint 5 100 parts by mass Aluminum pigment 2 1 part by mass Then, an electrodeposition coating film was formed by the same method as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin liquid) 5 was used. , The same evaluation was performed.

[Example 6]
The water-dispersible vinyl copolymer solution 1 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 6.
Water-dispersible vinyl copolymer solution 1 90.0 parts by mass Amino resin 1 35.0 parts by mass Didimethylaminoethanol 1.2 parts by mass Deionized water 123.8 parts by mass Then, in another container at the following ratio. Deionized water was charged, and the undiluted solution 6 obtained above was added while stirring, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the mixture to obtain a diluted solution 6 (active ingredient 8%) for electrodeposition coating. rice field.
Deionized water 789.4 parts by mass Stock solution 5 200.0 parts by mass Butyl cellosolve 10.0 parts by mass Dimethylaminoethanol 0.6 parts by mass The obtained diluent 6 for electrodeposition coating and aluminum pigment 3 are mixed in the following ratios. The mixture was stirred to obtain an aqueous resin composition (aqueous electrodeposition resin solution) 6.
Diluting liquid for electrodeposition coating material 6 100 parts by mass Water-dispersible aluminum pigment 3 1 part by mass The electrodeposition coating film is applied in the same manner as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin liquid) 6 is used. It was formed and evaluated in the same manner.

[Example 7]
The water-dispersible vinyl copolymer solution 1 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 7.
Water-dispersible vinyl copolymer solution 1 90.0 parts by mass Amino resin 1 35.0 parts by mass Didimethylaminoethanol 1.2 parts by mass Deionized water 123.8 parts by mass Then, in another container at the following ratio. Deionized water was charged, and the undiluted solution 7 obtained above was added while stirring, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the mixture to obtain a diluted solution 7 (active ingredient 8%) for electrodeposition coating. rice field.
Deionized water 789.4 parts by mass Stock solution 6 200.0 parts by mass Butyl cellosolve 10.0 parts by mass Dimethylaminoethanol 0.6 parts by mass The obtained diluent 7 for electrodeposition coating and aluminum pigment 1 are mixed in the following ratios. The mixture was stirred to obtain an aqueous resin composition (aqueous electrodeposition resin solution) 7.
Diluting liquid for electrodeposition paint 7 100.0 parts by mass Aluminum pigment 1 1.8 parts by mass Then, the electrodeposition coating film was formed in the same manner as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin liquid) 7 was used. Was formed and evaluated in the same manner.

[Comparative Example 1]
The vinyl copolymer solution 3 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 8.
Water-dispersible vinyl copolymer solution 3 90.0 parts by mass Amino resin 1 35.0 parts by mass dimethylaminoethanol 0.5 parts by mass Deionized water 124.5 parts by mass And in another container at the following ratio Deionized water was charged, and the undiluted solution 8 obtained above was added while stirring, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the mixture to obtain a diluted solution 8 (active ingredient 8%) for electrodeposition coating. rice field.
Deionized water 789.7 parts by mass Undiluted solution 8 200.0 parts by mass Butyl cellosolve 10.0 parts by mass Dimethylaminoethanol 0.3 parts by mass The obtained diluent 8 for electrodeposition coating and water-dispersible aluminum pigment 1 are mixed in the following proportions. Aqueous resin composition (aqueous electrodeposition resin solution) 8 was obtained by mixing and stirring with.
Diluting liquid for electrodeposition coating 8 100 parts by mass Water-dispersible aluminum pigment 1 1 part by mass The electrodeposition coating film is applied in the same manner as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin liquid) 8 is used. It was formed and evaluated in the same manner.

[Comparative Example 2]
The vinyl copolymer solution 4 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 9.
Water-dispersible vinyl copolymer solution 4 90.0 parts by mass Amino resin 1 35.0 parts by mass Didimethylaminoethanol 3.4 parts by mass Deionized water 121.6 parts by mass Then, in another container at the following ratio. Deionized water was charged, and the undiluted solution 9 obtained above was added while stirring, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the mixture to obtain a diluted solution 9 (active ingredient 8%) for electrodeposition coating. rice field.
Deionized water 788.2 parts by mass Undiluted solution 9 200.0 parts by mass Butyl cellosolve 10.0 parts by mass Dimethylaminoethanol 1.8 parts by mass The obtained diluent 9 for electrodeposition coating and aluminum pigment 1 are mixed in the following ratios. The mixture was stirred to obtain an aqueous resin composition (aqueous electrodeposition resin solution) 9.
Diluting liquid for electrodeposition coating material 9 100 parts by mass Water-dispersible aluminum pigment 1 1 part by mass The electrodeposition coating film is applied in the same manner as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin solution) 9 is used. It was formed and evaluated in the same manner.

[Comparative Example 3]
The water-dispersible vinyl copolymer solution 1 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 10.
Water-dispersible vinyl copolymer solution 1 90.0 parts by mass Amino resin 1 35.0 parts by mass Didimethylaminoethanol 1.2 parts by mass 123.8 parts by mass Deionized water And another container at the following ratio Deionized water was added to the mixture, and the undiluted solution 10 obtained above was added while stirring, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the solution 10 (active ingredient 8%) for electrodeposition coating. Obtained.
Deionized water 789.4 parts by mass Undiluted solution 10 200.0 parts by mass Butyl cellosolve 10.0 parts by mass Dimethylaminoethanol 0.6 parts by mass The obtained diluent 10 for electrodeposition coating and aluminum pigment 1 are mixed in the following ratios. The mixture was stirred to obtain an aqueous resin composition (aqueous electrodeposition resin solution) 10.
Diluting liquid for electrodeposition coating 10 100 parts by mass Water-dispersible aluminum pigment 1 0.01 part by mass Electrodeposition coating by the same method as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin liquid) 10 was used. A film was formed and evaluated in the same manner.

[Comparative Example 4]
The water-dispersible vinyl copolymer solution 1 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 11.
Water-dispersible vinyl copolymer solution 1 90 parts by mass Amino resin 1 35 parts by mass Didimethylaminoethanol 1.2 parts by mass Deionized water 123.8 parts by mass Then, deionized water is placed in another container at the following ratio. The stock solution 11 obtained above was added while being charged and stirred, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the mixture to obtain a diluent 11 for electrodeposition coating (active ingredient 8%).
Deionized water 789.4 parts by mass Undiluted solution 11 200.0 parts by mass Butyl cellosolve 10.0 parts by mass Dimethylaminoethanol 0.6 parts by mass The obtained diluent 11 for electrodeposition coating and aluminum pigment 1 are mixed in the following ratios. The mixture was stirred to obtain an aqueous resin composition (aqueous electrodeposition resin solution) 11.
Diluting liquid for electrodeposition coating material 11 100 parts by mass Water-dispersible aluminum pigment 13 parts by mass The electrodeposition coating film is applied in the same manner as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin liquid) 11 is used. It was formed and evaluated in the same manner.

[Comparative Example 5]
The water-dispersible vinyl copolymer solution 1 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to carry out phase inversion emulsification to obtain a stock solution 12.
Water-dispersible vinyl copolymer solution 1 124.7 parts by mass Amino resin 1 10 parts by mass Didimethylaminoethanol 1.7 parts by mass Deionized water 114.6 parts by mass Then, deionize in another container at the following ratio. Water was charged, and the undiluted solution 12 obtained above was added while stirring, and then butyl cellosolve and dimethylaminoethanol were added to homogenize the mixture to obtain a diluted solution 12 (active ingredient 8%) for electrodeposition coating.
Deionized water 789.1 parts by mass Undiluted solution 12 200.0 parts by mass Butyl cellosolve 10.0 parts by mass Dimethylaminoethanol 0.9 parts by mass The obtained diluent 12 for electrodeposition coating and aluminum pigment 1 are mixed in the following ratios. The mixture was stirred to obtain an aqueous resin composition (aqueous electrodeposition resin solution) 12.
Diluting Liquid for Electrodeposition Paint 12 100 parts by mass Water-dispersible aluminum pigment 1 1 part by mass And electroelectricity is carried out in the same manner as in Example 1 except that the aqueous resin composition (aqueous electrodeposition resin vinyl-based copolymer liquid) 12 is used. A coating film was formed and evaluated in the same manner.

[Comparative Example 6]
The water-dispersible vinyl copolymer solution 1 and the amino resin 1 were mixed at the following ratios, and dimethylaminoethanol was further added and mixed. While continuing stirring, deionized water was added to obtain a stock solution 13.
However, since the undiluted solution 13 was non-uniform without water solubilization or phase inversion emulsification, the subsequent work and evaluation were stopped.
Water-dispersible vinyl-based copolymer solution 1 41.6 parts by mass Amino resin 1 70 parts by mass Dimethylaminoethanol 0.6 parts by mass Deionized water 137.8 parts by mass

[Comparative Example 7]
Same as Example 1 except that the aqueous resin composition (aqueous electrodeposition resin solution) 1 obtained in Example 1 was used and the constant voltage method (applied at 250 v for 10 seconds) was used instead of the constant current method. Electrodeposition coating was performed by the method to form a coating film, and evaluation was performed in the same manner.

<Evaluation method of electrodeposition coating film>
[Metallic feeling]
The metallic feeling (metallic appearance) of the electrodeposited coating film of the coated material was judged by visual comparison. The meanings of the symbols in the table are as follows.
⊚: Good metallic feeling and uniform.
◯: The metallic feeling is slightly insufficient or slightly uneven.
X: Insufficient metallic feeling or a lot of unevenness.

[Film thickness uniformity]
Using an eddy current type film thickness meter (ISOCOPE manufactured by Fisher), the film thickness of the electrodeposited coating film on the upper surface portion, the side surface portion, and the lower surface portion of the coated material was measured, and σ (dispersion) was calculated and determined. The meanings of the symbols in the table are as follows.
⊚: σ is less than 1.0 μm.
◯: σ is 1.0 μm or more and less than 2.0 μm.
X: σ is 2.0 μm or more.

[Gloss uniformity]
The gloss of the electrodeposited coating film on the side surface portion, the upper surface portion, and the lower surface portion of the coated material was measured using the 60 ° mirror surface reflectance, and σ (dispersion) was calculated and determined. The meanings of the symbols in the table are as follows.
⊚: σ is less than 5%.
◯: σ is 5% or more and less than 10%.
X: σ is 10% or more.

[Color tone uniformity]
The color tone of the electrodeposited coating film on the side surface, upper surface, and lower surface of the painted object was measured using a color difference meter CR-400 (manufactured by Konica Minolta), and the color difference ΔE of each of the upper surface and the lower surface with respect to the side surface was measured. Was calculated and judged by the average value. The meanings of the symbols in the table are as follows.
⊚: ΔE is less than 1.
◯: ΔE is 1 or more and less than 2.
X: ΔE is 2 or more.

[Adhesion]
According to JIS K 5600-5-6, 5 × 5 = 25 grid-shaped squares were engraved in the coating film, and the number of squares that did not peel or chip by the tape application and peeling operation was counted. The meanings of the symbols in the table are as follows.
⊚: 25 pieces.
〇: 24 or more, less than 25.
X: Less than 24 pieces.

[Acid resistance]
A ring having an inner diameter of 32 mm and a height of 30 mm was brought into contact with the surface of the coating film with petrolatum, and a 5% aqueous sulfuric acid solution was placed in the ring to a height of 1/2 of the ring, and the appearance state after 24 hours was evaluated. The meanings of the symbols in the table are as follows.
⊚: No corrosion or swelling, or slight swelling.
◯: Corrosion and swelling are observed.
X: Significant corrosion or swelling is observed.

[Alkali resistance]
A ring having an inner diameter of 32 mm and a height of 30 mm was brought into contact with the surface of the coating film with petrolatum, and a 0.5% sodium hydroxide aqueous solution was placed in the ring to a height of 1/2 of the ring, and the appearance state after 24 hours was evaluated. .. The meanings of the symbols in the table are as follows.
⊚: No corrosion or swelling, or slight swelling.
◯: Corrosion and swelling are observed.
X: Significant corrosion or swelling is observed.

[Solvent resistance]
A ring having an inner diameter of 32 mm and a height of 30 mm was brought into contact with the surface of the coating film with petrolatum, xylene was put into the ring to a height of 1/2 of the ring, and the appearance state after 24 hours was evaluated. The meanings of the symbols in the table are as follows.
⊚: No corrosion or swelling, or slight swelling.
◯: Corrosion and swelling are observed.
X: Significant corrosion or swelling is observed.

<Summary of results>
The aqueous resin composition (aqueous electrodeposition resin solution) of each example and the electrodeposition coating film electrodeposited by the constant current method using the aqueous resin composition have low VOC properties due to the use of an aqueous solvent, and have a surface surface. By using the treated water-dispersible aluminum pigment, it has excellent stability over time, excellent metallic feeling, film thickness uniformity,
It shows a balance of gloss uniformity, color tone uniformity, adhesion, acid resistance, alkali resistance, and solvent resistance, and solves the problem of the present invention.
On the other hand, Comparative Example 1 in which the acid value of the water-dispersible vinyl-based copolymer was too low showed inferior alkali resistance and solvent resistance, and Comparative Example 2 in which the acid value was too high showed inferior adhesion.
Comparative Example 3 in which the content of the water-dispersible aluminum pigment was too low showed a poor metallic feeling, and Comparative Example 4 in which the content of the water-dispersible aluminum pigment was too high showed a poor alkali resistance.
Mass ratio (A) Water-dispersible vinyl copolymer / (B) Amino resin is too high Comparative Example 5 is inferior in gloss uniformity, and Comparative Example 6 is too low. Since it was uneven, the subsequent evaluation was interrupted.
Comparative Example 7 in which electrodeposition coating was performed by the constant voltage method showed inferior results in metallic feeling, film thickness uniformity, gloss uniformity, and color tone uniformity.

An aqueous resin composition containing the aluminum pigment of the present invention, an aqueous electrodeposition resin liquid comprising the aqueous resin composition, an aqueous electrodeposition coating material, and an electroelectron containing an aluminum pigment having a metallic appearance formed by using the aqueous electrodeposition coating material. The coating film is preferably used in a field where designability and corrosion resistance are required and low VOC is required.

Claims (6)

(A) a water-dispersible vinyl copolymer, a (B) an amino resin and (C) a constant current method electrodeposition coating the aqueous resin composition containing a water-dispersible aluminum pigment,
The water-dispersible vinyl-based copolymer has a carboxyl group as a substituent, an acid value of 20 to 100 mgKOH, dispersibility in an aqueous solvent, and a carbon-carbon unsaturated bond (co). ) It is a polymerized (co) polymer,
The mass ratio (A) / (B) is 40/60 to 80/20.
Mass ratio (C) / {(A) + (B)} is characterized by a 0.1 / 99.9 to 15/85, a constant current method electrodeposition coating aqueous resin composition. The water-dispersible aluminum pigment comprises a surface-treated aluminum pigment.
The surface of the surface-treated aluminum pigment is characterized by containing one kind selected from the group consisting of an inorganic phosphorus-based compound, a molybdenum-based compound, a silicon-based compound, and an organic resin, or a combination of two or more kinds. constant current method electrodeposition coating the aqueous resin composition according to 1. Characterized by comprising the constant current method electrodeposition coating the aqueous resin composition according to claim 1 or 2, the aqueous electrocoating resin solution. A water-based electrodeposition coating material comprising the water-based electrodeposition resin liquid according to claim 3. An electrodeposition coating film formed from the water-based electrodeposition coating material according to claim 4, which has a metallic appearance. A method for forming an electrodeposition coating film, which comprises electrodepositionally coating the aqueous electrodeposition resin liquid according to claim 3 or the aqueous electrodeposition coating material according to claim 4 by a constant current method.