JPH08206585A - Formation of cured coating film - Google Patents

Abstract

PURPOSE: To provide a forming method of a cured coating film capable of forming the cured coating film at from room temp. to 100 deg.C and capable of forming a smooth coating film. CONSTITUTION: In the forming method of the cured coating film, the coating film is cured by bringing an uncured coating film into contact with aq. soln. containing a polyhydrazide compd. after forming the uncured coating film having unreacted carbonyl groups by applying a coating material using a carbonyl group-containing resin as a binder on the object to be coated. In this case, the forming method of the cured coating film in which an acid component such as phosphoric acid is added to an aq. soln. containing the polyhydrazide compd. is included.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for forming a coating film, which comprises coating and then curing the coating film by contacting it with an aqueous crosslinking solution.

[0002]

2. Description of the Related Art A coating film containing a thermoplastic resin as a binder has the property of becoming soft and tacky at high temperatures or becoming hard and brittle at low temperatures. Therefore, in order to maintain good physical properties from high temperature to low temperature, the coating film needs to be a cross-linked coating film. However, in order to cause a crosslinking reaction by heating, it is generally necessary to heat to a high temperature. In this case, if the heat capacity of the article to be coated is large, an enormous amount of heat is required, and in many cases, only about 1% of this amount of heat is used for the actual crosslinking reaction of the coating film. For this reason, it is preferable to use the room temperature crosslinking reaction from the viewpoint of effective use of energy, but generally, there is a problem that the crosslinking reaction at room temperature is slow and it is difficult to sufficiently proceed. Generally, if the method of accelerating the crosslinking reaction at room temperature is taken, the storage stability of the paint will be poor, and the usable life after the paint will be shortened.Because the leveling time of the applied coating will be short, the gloss will be low and the surface will be rough. It becomes a film. This drawback is noticeable especially when an organic solvent that dissolves a resin is not used like water-based paints and powder paints. For this improvement, a two-pack type paint is used, but in this case, if the use is not completed within a short time after the blending of the paint, the paint thickens and gels to make it unusable. In order to solve these problems, it is sufficient to first form a coating film that does not cause a crosslinking reaction and level it sufficiently, and then contact this coating film with a crosslinking liquid to cure it, but until now the No method has been found that can form a practical cured coating film in combination with a crosslinking liquid.

[0003]

Therefore, the present inventors have proposed a practical cured coating film which can use a coating material having a long pot life and has good coating surface smoothness, solvent resistance and coating film hardness. As a result of earnest research on a method capable of forming at room temperature or a low temperature forced drying temperature up to about 100 ° C., the present invention has been achieved. That is, the present invention, a coating material containing a carbonyl group-containing resin as a binder is applied to an object to be coated to form an uncured coating film having an unreacted carbonyl group, and the uncured coating film contains a polyhydrazide compound. The present invention provides a method for forming a cured coating film, which comprises contacting with an aqueous solution to cure the coating film.

According to the present invention, "1. A coating material containing a carbonyl group-containing resin as a binder is applied to an article to form an uncured coating film having an unreacted carbonyl group, and then the uncured coating film is coated with a poly- A method for forming a cured coating film, which comprises contacting an aqueous solution containing a hydrazide compound to cure the coating film 2. An uncured coating film on the coated object is placed in an aqueous solution containing a polyhydrazide compound. A method for forming a cured coating film according to item 1, which is characterized in that the coating film and the aqueous solution are brought into contact with each other by immersing the carbonyl group-containing resin in combination with the carbonyl group-containing vinyl monomer. A method for forming a cured coating film, which is a copolymer with a vinyl monomer, according to item 1 or 2. 4. Among all the monomer components constituting the carbonyl group-containing resin, the carbonyl group-containing vinyl monomer is 0. The method for forming a cured coating film according to item 3, which is 5 to 60% by weight 5. Out of all the monomer components constituting the carbonyl group-containing resin, the ionic monomer contained in other vinyl monomers is 30% by weight or less. The method for forming a cured coating film according to item 3. 6. In all the monomer components constituting the carbonyl group-containing resin, the other vinyl monomer is acrylic acid or methacrylic acid having 12 to 30 carbon atoms. 7. The method for forming a cured coating film containing 5 to 50% by weight of ester according to item 3. 7. The method for forming a cured coating film according to item 3, wherein the carbonyl group-containing vinyl monomer is diacetone acrylamide. The carbonyl group-containing resin contains an ionic group, and the paint is a water-based paint,
Item 8. A method for forming a cured coating film according to any one of items 1 to 7. 9. The method for forming a cured coating film according to item 8, wherein the article to be coated is electrically conductive, and the aqueous coating material is applied to the article to be coated by electrodeposition coating. 10. Item 10. The method for forming a cured coating film according to any one of items 1 to 9, wherein the polyhydrazide compound is carbodihydrazide. 11. An aqueous solution containing a polyhydrazide compound contains 1 to 60 parts by weight of a water-soluble organic solvent in 100 parts by weight of the aqueous solution, and the cured coating according to any one of items 1 to 10. Method of forming a film. 12. An aqueous solution containing a polyhydrazide compound is 3
The method for forming a cured coating film according to any one of items 1 to 11, which is an aqueous solution containing 0% by weight or less of an acid component. 13. 13. The method for forming a cured coating film according to item 12, wherein the acid component added to the aqueous solution containing the polyhydrazide compound is a phosphorus atom-containing acidic compound. 14. The method for forming a cured coating film according to any one of items 1 to 13, wherein the reaction between the carbonyl group in the coating film and the polyhydrazide is carried out at a low forced drying temperature of 15 ° C to 100 ° C. . Regarding

The paint used in the present invention uses a carbonyl group-containing resin as a binder, and any resin containing a carbonyl group in the molecule can be used. A typical example of the carbonyl group-containing resin is a copolymer of a carbonyl group-containing vinyl monomer and another vinyl monomer.

Typical examples of the carbonyl group-containing vinyl monomer include acrolein, diacetone acrylamide, diacetone methacrylamide, formyl styrene, vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, Vinyl butyl ketone, etc.), diacetone acrylate, diacetone methacrylate, acetonylyl acrylate, β-acryloyloxyethyl acetyl acetate, δ-acryloyloxybutyl acetyl acetate, (meth) acryloyloxyalkylpropenal [carbon atom of oxyalkyl group 1-6], acetoacetoxyethyl acrylate, acetoacetoxyethyl methacrylate; compounds having 10 or less carbon atoms having a hydroxyl group and a carbonyl group (examples For example, 4-hydroxy-2-
Butanone, 3-hydroxy-3-methyl-2-butanone, 4-hydroxy-4-methyl-2-pentanone, etc. and a polymerizable unsaturated carboxylic acid (for example, acrylic acid,
Methacrylic acid and the like); Condensation reaction product of hydroxyl group of compound having 10 or less carbon atoms having hydroxyl group and carbonyl group with amino group portion of acrylamide or methacrylamide; carbon atom having hydroxyl group and carbonyl group Adducts of 10 or less compounds with a polymerizable unsaturated monomer having an isocyanate group (for example, m-isopropenyl-α, α-dimethylbenzyl isocyanate, isocyanatoethyl methacrylate, methacryloyl acyl isocyanate, etc.); a hydroxyl group and a carbonyl group A compound having 10 or less carbon atoms and a diisocyanate compound (for example, tolylene diisocyanate, 4,4 ′)
-A diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-methylenebiscyclohexyl isocyanate and the like) mono-adduct [having one isocyanate group] with a hydroxyl group-containing polymerizable unsaturated monomer (for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, etc.) and the like. These can be used alone or in combination of two or more. Among these examples, preferred examples include acrolein, diacetone acrylamide,
Diacetone methacrylamide, vinyl methyl ketone,
Addition product of 4-hydroxy-2-butanone with a polymerizable unsaturated monomer having an isocyanate group (for example, m-isopropenyl-α, α-dimethylbenzyl isocyanate, isocyanatoethyl methacrylate, methacryloylacyl isocyanate), acetoacetoxy Examples thereof include ethyl methacrylate and acetoacetoxyethyl acrylate, and among them, diacetone acrylamide is particularly preferable.

As the other vinyl monomer forming a copolymer with the carbonyl group-containing vinyl monomer, any monomer having copolymerizability with the carbonyl group-containing vinyl monomer can be used without limitation. As typical examples, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate (n-, i-, t-), hexyl acrylate, 2-ethylhexyl acrylate, n-acrylate. Octyl, decyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate (n-, i-, t-), Hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, etc. Acrylic acid or methacrylic acid having 1 to 1 carbon atoms
30 alkyl ester or cycloalkyl ester; carbon number of acrylic acid or methacrylic acid such as trimethoxybutyl acrylate, trimethoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, ethoxybutyl methacrylate 2-18 alkoxyalkyl ester;
2-hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 2-
Hydroxyalkyl esters of acrylic acid or methacrylic acid such as hydroxyethylmethacrylate, hydroxypropylmethacrylate, and hydroxybutylmethacrylate having 2 to 8 carbon atoms; vinyl acetate, vinyl propionate, Veova monomer (Ciel Chemical Co., branched higher fatty acid vinyl ester). Such as vinyl esters of fatty acids having 1 to 20 carbon atoms; olefins such as ethylene, propylene, butylene, pentene; diene compounds such as butadiene, isoprene, chloroprene; acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, styrene sulfone Anionic monomers such as acid soda; dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminopropyl acrylamide, dimethylaminopropyl Methacrylamide, cationic monomers such as diethylaminoethyl methacrylate;
Examples thereof include styrene, vinyltoluene, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, N-vinylpyrrolidone, vinylpyridine and vinylpivalate.

[0008] Of all the monomer components constituting the copolymer, the amount of the carbonyl group-containing vinyl monomer is 0.5 to 60% by weight, more preferably 1 to 40% by weight, from the viewpoint of crosslinkability and coating performance. It is suitable to be in the range of preferably 3 to 30% by weight. If it is 0.5% by weight or less, the crosslinkability becomes insufficient, and if it is 60% by weight or more, the coating film tends to be brittle.

Among the above-mentioned other monomers, the amount of the ionic monomer such as anionic monomer and cationic monomer used is 30% by weight or less, preferably 20% by weight or less, from the viewpoint of the water resistance of the coating film. It is suitable. When the coating is water-based, the amount of the ionic monomer used is the amount necessary to make the water-based, and 0.5 to 30% by weight, preferably 1 to 20% by weight is suitable. If it is 0.5% by weight or less, it cannot be made water-soluble, and if it is 30% by weight or more, the water resistance of the coating film tends to be poor. Among the above-mentioned other monomers, acrylic acid or methacrylic acid has 12 carbon atoms.
~ 5 to 30 alkyl ester in the total monomer components
The water resistance of the coating film obtained by using 0% by weight can be improved. If it is 5% by weight or less, the effect of improving the water resistance becomes insufficient, and if it is 50% by weight or more, the coating film hardness tends to decrease. The above copolymer can be obtained by a known method such as emulsion polymerization, solution polymerization or bulk polymerization.

Examples of the carbonyl group-containing resin include various resins containing a carbonyl group, in addition to the above copolymers.
For example, epoxy resin, alkyd resin, polyester resin, urethane resin, etc. can be mentioned. These resins are, for example, compounds having 10 or less carbon atoms having a hydroxyl group and a carbonyl group (for example, 4-hydroxy-2-
Butanone, 3-hydroxy-3-methyl-2-butanone, 4-hydroxy-4-methyl-2-pentanone, etc. and a diisocyanate compound (for example, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene) Diisocyanate, isophorone diisocyanate, 4,
4'-methylenebiscyclohexyl isocyanate and the like) can be obtained by addition to various resins containing a hydroxyl group (for example, epoxy resin, alkyd resin, polyester resin, urethane resin, etc.).

In the present invention, the form of the paint used is
It may be any of water-based paint, organic solvent type paint and powder paint, but when it is water-based, it has an ionic group in a hydrophilic organic solvent in addition to the resin obtained by emulsion polymerization. It is also possible to use a resin obtained by synthesizing a resin and neutralizing it, for example, a resin which is obtained by copolymerizing a monomer component containing an ionic monomer in a hydrophilic organic solvent and then water-dispersed or water-solubilized. When the ionic monomer is anionic, ammonia, amines,
By neutralizing with a base such as an alkali metal, or when the ionic monomer is cationic, formic acid,
It can be water-dispersed or water-soluble in an aqueous medium by neutralizing or quaternary salting with an acid such as acetic acid, propionic acid or lactic acid. The molecular weight of the copolymer is not particularly limited, but generally, the number average molecular weight is 500 to 2000,0.
The range is 00.

The coating material used in the method of the present invention contains a carbonyl group-containing resin as a binder. In addition to the carbonyl group-containing resin, a resin having compatibility with the carbonyl group-containing resin may be added in an amount of 70% by weight in the binder. % Or less. Further, the coating used in the method of the present invention, if necessary, usually various additives that can be blended into the coating, for example, color pigments, extender pigments, rust preventive pigments,
It may be a mixture of an anti-sag agent, an antifoaming agent, a coating surface adjusting agent and the like.

In the method of the present invention, after the above coating material is applied to an object to be coated, the uncured coating film on the object to be coated is brought into contact with an aqueous solution containing a polyhydrazide compound to cure the coating film. The polyhydrazide compound has a hydrazino group (-N) directly bonded to a carbon atom of a carbonyl group.
It is a compound having two or more HNH ₂ ) in one molecule.
Typical examples of the polyhydrazide compound include compounds represented by the following general formula [1], [2] or [3]. General formula [1]

[0014]

Embedded image

(In the formula, R ¹ represents a divalent dicarboxylic acid residue having 1 to 12 carbon atoms or a direct bond, and n represents a number of 0 or 1.) General formula [2]

[0016]

Embedded image

(In the formula, m represents an integer of 1 to 5, preferably 1 to 3.) General formula [3]

[0018]

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(In the formula, R ² is a divalent linear or branched aliphatic hydrocarbon group having 2 to 7 carbon atoms or a divalent cyclic aliphatic group having 6 to 8 carbon atoms. Or represents an aromatic hydrocarbon group.)

Specific examples of the polyhydrazide compound include carbodihydrazide (carbonic acid dihydrazide), oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, Dihydrazide, itaconic acid dihydrazide,
Compounds represented by the general formula [1] such as phthalic acid dihydrazide, isophthalic acid dihydrazide, and terephthalic acid dihydrazide; compounds represented by the general formula [2] that are carbonic acid poly (tri, tetra, penta, etc.) hydrazides; In the formula [3], R ² is ethylene group, 1,2- or 1,3-propylene group, butylene group, hexylene group, o
A bissemicarbazide represented by the general formula [3] such as-, m- or p-phenylene group, tolylene group, cyclohexylene group or methylcyclohexylene group; dihydrazide or trihydrazide of trimellitic acid, dihydrazide of pyromellitic acid , Trihydrazide or tetrahydrazide; nitrilotriacetic acid trihydrazide, ethylenediaminetetraacetic acid tetrahydrazide; polyacrylic acid, polymethacrylic acid or polyhydrazides obtained by adding dihydrazine to their copolymers; low weight having a carboxylic acid lower alkyl ester group Examples thereof include polyhydrazide (see Japanese Examined Patent Publication No. 52-22878) obtained by reacting the combined product with hydrazine or hydrazine hydrate. Among these, carbodihydrazide and oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide,
In general formula [1] such as adipic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide and itaconic acid dihydrazide, dihydrazide of carboxylic acid in which R ¹ is a saturated or unsaturated dicarboxylic acid residue having 1 to 4 carbon atoms is an aqueous solvent. It is preferable in terms of solubility in medium, crosslinking reactivity and the like. The concentration of the polyhydrazide compound in the aqueous solution containing the polyhydrazide compound is not particularly limited, but is generally 1 to 40% by weight, preferably 5 to 20% by weight. .

The aqueous solution containing the polyhydrazide compound may be composed of the polyhydrazide compound and water, but if necessary, it may contain an organic solvent and an acid component. The organic solvent is added for the purpose of improving the solubility of the polyhydrazide compound in an aqueous solution and facilitating the permeation of the polyhydrazide compound into the coating film. Examples of the organic solvent include glycol-based solvents represented by the following general formula [4] and alcohol-based solvents represented by the following general formula [5]. General formula [4]

[0022]

[Chemical 4]

(In the formula, R ³ is a saturated hydrocarbon group having 1 to 8 carbon atoms, R ⁴ is a divalent saturated hydrocarbon group having 2 to 5 carbon atoms, R ⁵ is a hydrogen atom and 1 carbon atom. To 4 each represent an alkyl group or an acyl group, and k represents 1 to 4.) General formula [5]

[0024]

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(In the formula, R ⁶ represents a saturated hydrocarbon group having 1 to 8 carbon atoms.)

Specific examples of the organic solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monopropyl ether, diethylene glycol monoethyl ether, propylene glycol. Monomethyl ether, propylene glycol monoethyl ether, ethylene glycol dimethyl ether, 3-methyl-3-
Glycol-based solvents represented by the general formula [4] such as methoxybutanol, ethylene glycol monoethyl ether acetate and propylene glycol monomethyl ether acetate; methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, cyclohexanol, etc. Alcohol solvent represented by the general formula [5]; dioxane, tetrahydrofuran,
Mention may be made of N-methylpyrrolidone, ethylene glycol, dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether and benzyl alcohol. These may be used alone or in combination of two or more.

Among these organic solvents, in order to promote the penetration of the polyhydrazide compound into the coating film, it is preferable to use a solvent having an amphipathic property. 4] is further limited to the general formula R
⁷ OR ⁸ OH (in the formula, R ⁷ represents a saturated hydrocarbon group having 2 to 5 carbon atoms, and R ⁸ represents a divalent saturated hydrocarbon group having 2 to 5 carbon atoms). Organic solvents such as ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monopropyl ether, diethylene glycol monoethyl ether, propylene glycol monoethyl ether, 3-methyl-3-methoxybutanol Can be mentioned.

The blending amount of the above-mentioned organic solvent varies greatly depending on the type of solvent, but it is desirable that the coating film does not elute, the permeability is good, and there is no risk of fire. In the aqueous solution containing the polyhydrazide compound, it is appropriate that the amount is 60% by weight or less, preferably 3 to 50% by weight, more preferably 5 to 25% by weight. When it is 60% by weight or more, the coating film is easily dissolved in the aqueous solution.

The above-mentioned acid component which can be blended in the aqueous solution containing the polyhydrazide compound is used for acidifying the aqueous solution to accelerate the reaction between the carbonyl group in the coating film and the polyhydrazide compound, and the aqueous solution of the polyhydrazide compound. It is blended for the purpose of improving the solubility in it. If the coating resin has an anionic group and the coating film is acidic, it may not be necessary to add an acid component, but if the coating film is neutral or basic, It is preferable to add an acid component in order to shorten the reaction time between the carbonyl group in the coating film and the polyhydrazide compound and to prevent the coating film from swelling or dissolving due to contact with an aqueous solution.

Examples of the acid component include organic acids such as formic acid, acetic acid, propionic acid, acrylic acid, itaconic acid, maleic acid, fumaric acid, benzenesulfonic acid, phosphoric acid, phosphorous acid, hypophosphorous acid, orthophosphoric acid, and pyrophosphate. Phosphoric acid, tripolyphosphoric acid,
Phosphoric acid such as metaphosphoric acid, monomethyl phosphoric acid, monoethyl phosphoric acid, mono-n-butyl phosphoric acid, diethyl phosphoric acid, dimethyl phosphoric acid, phosphorous acid-containing acidic compounds such as esterified phosphoric acid such as phosphorous acid ethyl ester, hydrochloric acid, sulfuric acid, nitric acid, etc. Inorganic acids can be mentioned, and these can be used alone or in admixture of two or more. Of these acid components, a phosphorus atom-containing acidic compound such as phosphoric acid is particularly preferable because it is less likely to corrode the object to be coated, color the coating film, and deteriorate the adhesion of the coating film. The blending amount of this acid component varies depending on the acidity and basicity of the coating film, but generally it is 30% by weight or less, preferably 20% by weight in an aqueous solution containing a polyhydrazide compound.
The following range is suitable. If it is 30% by weight or more, the article to be coated is likely to be corroded.

[0031]

The steps of the method of the present invention will be described below. In the method of the present invention, the object to be coated with the coating material is not particularly limited, and metal, plastics, wood, paper, glass, ceramics, treated metal obtained by chemical conversion treatment of metal surface; Various things can be mentioned, such as a coated article formed by forming an undercoat coating film or an intermediate coating film. As a method for coating the coating material having the carbonyl group-containing resin as a binder on the article to be coated, dip coating, spray coating, roll coating, brush coating, etc. are used, and when the coating is aqueous, electrodeposition coating is used. Can also be used. When electrodeposition coating is carried out, anion electrodeposition coating is used when the coating resin is anionic, and cationic electrodeposition coating is used when the resin is cationic.

After coating, the coating film on the article to be coated is contacted with an aqueous solution containing a polyhydrazide compound, but the coating film may not dissolve, fall off, or excessively swell due to contact with this aqueous solution. If necessary, the coating film is dried (normal temperature drying or forced drying) after coating and before contact with the aqueous solution. By this drying, the solvent is removed from the water-based or organic solvent-based coating film, and the powder particles are fused to the powder coating film. Since the curing does not occur before contact with the aqueous solution, the coating film flows sufficiently,
Can be smoothed. Since a coating film applied by electrodeposition coating generally has a small solvent content, it is advantageous in many cases that this drying step can be omitted. Examples of the method of bringing the coating film on the article to be contacted into the aqueous solution containing the polyhydrazide compound include a method of immersing the coating solution in the aqueous solution, a method of spraying the aqueous solution, and a method of pouring the aqueous solution. Of these, the dipping method is preferable in terms of uniformity of contact with the aqueous solution, difficulty in applying pressure to the aqueous solution, and ease of process control. The contact between the aqueous solution and the coating is
It is preferable to carry out until the polyhydrazide compound in the aqueous solution can sufficiently penetrate into the coating film. This contact time varies depending on the type of coating film (acidity, basicity, etc.), aqueous solution type (concentration, polyhydrazide compound, solvent type, acidity, basicity), temperature, etc. 5-60
It's about a minute.

The polyhydrazide compound is immersed in the coating film by contacting the coating film on the article to be coated with an aqueous solution, and the reaction between the carbonyl group in the resin and the hydrazide group occurs according to the following formula.

[0034]

[Chemical 6]

After the above contacting step, a cured coating film can be obtained by washing with water if necessary and drying at room temperature or low temperature forced drying temperature of 15 ° C to 100 ° C. The heating can be performed as necessary for the purpose of further promoting the curing reaction to increase the degree of crosslinking. When this heating is performed, it is preferable that the temperature is 100 ° C. or lower from the viewpoint of effective use of energy, but it may exceed 100 ° C.
It is performed under heating conditions of about 200 ° C. for about 1 to 40 minutes.
In this way, the desired crosslinked cured coating film can be obtained.

Preferred embodiments of the method for forming a cured coating film of the present invention are shown below. (1) Formation of a cured coating film of the present invention, which comprises bringing the coating film and the aqueous solution into contact with each other by immersing the uncured coating film on the article to be coated in an aqueous solution containing a polyhydrazide compound. Method. (2) The method for forming a cured coating film of the present invention, wherein the carbonyl group-containing resin is a copolymer of a carbonyl group-containing vinyl monomer and another vinyl monomer. (3) Polymerizable unsaturated monomer having a carbonyl group-containing vinyl monomer having acrolein, diacetone acrylamide, diacetone methacrylamide, vinyl methyl ketone, acetoacetoxyethyl methacrylate, acetoacetoxyethyl acrylate isocyanate group and 4-hydroxy-2-butanone Alternatively, the method for forming a cured coating film of the present invention, which is at least one selected from an adduct with diacetone acrylamide. (4) The method for forming a cured coating film according to (2), wherein the carbonyl group-containing vinyl monomer is diacetone acrylamide. (5) The carbonyl group-containing resin is obtained by adding a mono-adduct (having one isocyanate group) of a compound having 10 or less carbon atoms having a hydroxyl group and a carbonyl group and a diisocyanate compound to an epoxy resin containing a hydroxyl group. The method for forming a cured coating film of the present invention, which is a resin comprising: (6) The method for forming a cured coating film according to the present invention, wherein the carbonyl group-containing resin contains an ionic group, and the coating material is an aqueous coating material. (7) The method for forming a cured coating film according to (6) above, wherein the article to be coated is electrically conductive, and the water-based paint is applied to the article to be coated by electrodeposition coating. (8) The polyhydrazide compound is carbodihydrazide,
A method for forming a cured coating film of the present invention, which is at least one selected from oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide and itaconic acid dihydrazide. (9) The method for forming a cured coating film of the present invention, wherein the polyhydrazide compound is carbodihydrazide. (10) The method for forming a cured coating film of the present invention, wherein the aqueous solution containing the polyhydrazide compound contains 1 to 60 parts by weight of a water-soluble organic solvent in 100 parts by weight of the aqueous solution. (11) An aqueous solution containing a polyhydrazide compound is used as a water-soluble organic solvent represented by the general formula R ⁷ OR ⁸ OH (in the formula, R ⁷ OR ⁸ OH
⁷ represents a hydrocarbon group having 2 to 5 carbon atoms, and R ⁸ represents a hydrocarbon group having 2 to 5 carbon atoms. ) The method for forming a cured coating film according to (10) above, which comprises an organic solvent represented by (12) The method for forming a cured coating film of the present invention, wherein the aqueous solution containing the polyhydrazide compound is an aqueous solution containing an acid component. (13) After applying an anionic water-based paint to an article to be coated by anion electrodeposition coating, contacting the uncured coating film on the article to an aqueous solution containing a polyhydrazide compound containing no acid component. The method for forming a cured coating film according to (6) above, which is characterized. (14) After applying a cationic aqueous coating composition to an object to be coated by cationic electrodeposition coating, the uncured coating film on the object to be coated is brought into contact with an acidic aqueous solution containing an acid component and a polyhydrazide compound. The method for forming a cured coating film according to (6) above.

[0037]

The present invention will be described below in detail with reference to examples.

Production of Resin Containing Carbonyl Group Production Example 1 Propylene glycol monomethyl ether 2 was placed in a flask.
70 parts by weight was added and heated to 110 ° C., nitrogen gas was introduced into the flask to replace air. Then, the following monomer mixture liquid was dropped into the flask over 1.5 hours. Acrylic acid 31.5 parts by weight Diacetone acrylamide 270 parts by weight Styrene 180 parts by weight Stearyl methacrylate 270 parts by weight n-Butyl methacrylate 343.5 parts by weight n-Butyl acrylate 30 parts by weight Isobutyl methacrylate 225 parts by weight Perbutyl O (NOF CORPORATION) 2.7 parts by weight after completion of dropping, the mixture was maintained at 110 ° C. for 1 hour, 2.7 parts by weight of perbutyl O was added dropwise over 2 hours, and the mixture was further aged at 110 ° C. for 2 hours. After the reaction, cool to 60 ° C,
After adding 675 parts by weight of isopropanol, 54 parts by weight of triethylamine was added for neutralization, and deionized water 1 was added.
After 400 parts by weight were added and dispersed, vacuum distillation was carried out to remove isopropanol, water, and a part of propylene glycol monomethyl ether to obtain emulsion A. Emulsion A has a solid content of 47.0% by weight, a pH of 8.9,
The particle size was 0.11 μm.

Production Example 2 In Production Example 1, the composition of the monomer mixture was changed as follows, and the amount of deionized water was changed from 1400 parts by weight to 135 parts by weight.
Emulsion B was obtained in the same manner as in Production Example 1 except that the amount was changed to 0 part by weight. Emulsion B has a solid content of 41.0
% By weight, pH was 9.1, and particle size was 0.08 μm. Blending of Monomer Mixture Acrylic acid 31.5 parts by weight Diacetone acrylamide 270 parts by weight Styrene 180 parts by weight n-butyl methacrylate 418.5 parts by weight n-butyl acrylate 450 parts by weight Perbutyl O (manufactured by NOF Corporation, polymerization initiator) ) 2.7 parts by weight

Production Example 3 Propylene glycol monomethyl ether 3 was added to a flask.
00 parts by weight was put thereinto and heated to 110 ° C., and nitrogen gas was introduced into the flask to replace air. Then, the following monomer mixture liquid was dropped into the flask over 1.5 hours. Acrylic acid 24 parts by weight Diacetone acrylamide 120 parts by weight Stearyl methacrylate 120 parts by weight Styrene 120 parts by weight n-Butyl methacrylate 96 parts by weight Isobutyl methacrylate 120 parts by weight Perbutyl O 18 parts by weight After completion of dropping, the mixture is kept at 110 ° C. for 2 hours, and then kept. 6 parts by weight of perbutyl O was added dropwise over 2 hours and then for another 2 hours 1
Aged at 10 ° C. After completion of the reaction, the mixture was cooled to 60 ° C, neutralized by adding 34 parts by weight of triethylamine, and further dissolved by adding deionized water to obtain a solid content of 26.3% by weight and pH.
Obtained an aqueous resin solution C of 9.8.

Production Example 4 Propylene glycol monomethyl ether 3 was added to a flask.
00 parts by weight was put thereinto and heated to 110 ° C., and nitrogen gas was introduced into the flask to replace air. Then, the following monomer mixture liquid was dropped into the flask over 1.5 hours. Acrylic acid 20 parts by weight Diacetone acrylamide 120 parts by weight Styrene 120 parts by weight n-Butyl methacrylate 120 parts by weight n-Butyl acrylate 120 parts by weight Isobutyl methacrylate 100 parts by weight Perbutyl O 18 parts by weight After dropping, the mixture is kept at 110 ° C. for 2 hours. Then, 6 parts by weight of perbutyl O was added dropwise over 2 hours, and then 1 hour for 2 hours.
Aged at 10 ° C. After completion of the reaction, the mixture was cooled to 60 ° C., 28 parts by weight of triethylamine was added for neutralization, and deionized water was further added to dissolve the mixture, to obtain a resin aqueous solution D having a solid content of 16.8 wt% and a pH of 10.4. Obtained.

Production Example 5 300 parts by weight of deionized water and Newcol 70 were added to a flask.
7SF (manufactured by Nippon Emulsifier Co., Ltd., anionic surfactant having a solid content of 30% by weight) (3.46 parts by weight) and ammonium peroxide (1 part by weight) were added, and the mixture was heated to 85 ° C. On the other hand, the following monomer mixture liquid was added to another container and stirred to obtain a pre-emulsion. Acrylic acid 5 parts by weight Diacetone acrylamide 194 parts by weight Styrene 265 parts by weight n-Butyl methacrylate 226 parts by weight n-Butyl acrylate 279 parts by weight Newcol 707SF 93.4 parts by weight Ammonium peroxide 2 parts by weight This pre-emulsion is used for 2 hours. It dripped at the said flask. After the dropping was completed, the temperature was kept at 85 ° C for 1 hour, and then 1 part by weight of ammonium peroxide and 1 part of deionized water were added.
A mixed solution with 0 part by weight was added dropwise over 1 hour. After completion of dropping, the mixture was aged for 2 hours. Since the viscosity increased during the reaction, deionized water was added to adjust the viscosity each time.
The solid content of the obtained emulsion E was 46.1% by weight, p
H was 2.50.

Production Example 6 Ethylene glycol monobutyl ether 18 was added to a flask.
9 parts by weight, propylene glycol monomethyl ether 1
89 parts by weight was put thereinto, the mixture was heated to 110 ° C., and nitrogen gas was introduced into the flask to replace air. Then, the following monomer mixture liquid was dropped into the flask over 1.5 hours. Dimethylaminoethyl methacrylate 85.5 parts by weight Diacetone acrylamide 189 parts by weight Styrene 126 parts by weight Stearyl methacrylate 155 parts by weight n-Butyl methacrylate 211.5 parts by weight n-Butyl acrylate 21 parts by weight Isobutyl methacrylate 158 parts by weight Azobisisobutyro 4.7 parts by weight of nitrile After completion of dropping, the mixture was kept at 110 ° C. for 2 hours, then 4.7 parts by weight of perbutyl O was added dropwise over 2 hours, and the mixture was aged at 110 ° C. for 2 hours. After the completion of the reaction, the mixture was cooled and neutralized by adding 26 parts by weight of acetic acid, and then 2446 parts by weight of deionized water was added and dissolved in water to obtain a cationic resin aqueous solution F having a solid content of 24.6% by weight and a pH of 4.32. Got

Production Example 7 104.4 parts by weight of tolylene diisocyanate was placed in a flask and heated to 40 ° C., and 58.1 parts by weight of hydroxybutanone was added dropwise thereto over 40 minutes. As a result, the temperature inside the flask rose to 60 ° C. 55 after the dropping
The mixture was kept at ℃ for 2 hours to obtain a solid adduct. 285 parts by weight of Epicoat 1001 (Bisphenol A type epoxy resin manufactured by Shell Chemical Co., Ltd.) and 65.1 parts by weight of propylene glycol monomethyl ether acetate were placed in another flask and heated to 60 ° C. to dissolve them, and then methyl ethanolamine 40. 7 parts by weight was added dropwise over 40 minutes. After the dropping was completed, the mixture was kept at 70 ° C. for 3 hours, and then 96 parts by weight of propylene glycol monomethyl ether acetate and 154.4 parts by weight of the solid adduct obtained as described above were added and reacted at 100 ° C. for 3 hours. After cooling, 24 parts by weight of acetic acid and 96 parts by weight of ethylene glycol monobutyl ether were added, and 980 parts by weight of deionized water was added and dissolved under stirring to obtain a cationic resin aqueous solution G having a solid content of 25.1% by weight.

Production Example 8 Ethylene glycol monobutyl ether 13 was placed in a flask.
2 parts by weight, propylene glycol monomethyl ether 1
32 parts by weight was put thereinto, the mixture was heated to 110 ° C., and nitrogen gas was introduced into the flask to replace air. Then, the following monomer mixture liquid was dropped into the flask over 1.5 hours. Diacetone acrylamide 135 parts by weight stearyl methacrylate 135 parts by weight styrene 90 parts by weight n-butyl methacrylate 172 parts by weight n-butyl acrylate 15 parts by weight isobutyl methacrylate 128 parts by weight perbutyl O 3.3 parts by weight After completion of dropping, 2 hours at 110 ° C. Then, 3.3 parts by weight of perbutyl O was added dropwise over 2 hours, followed by aging at 110 ° C. for 2 hours. After completion of the reaction, the mixture was cooled and 411 parts by weight of ethylbenzene was added to obtain a resin solution H.

Production Example 9 In Production Example 8, the composition of the monomer mixture was changed as follows, and the amount of ethylbenzene added after cooling was 464.
A resin solution I was prepared in the same manner as in Production Example 8 except that the parts by weight were used.
I got Acrylic acid 20 parts by weight Acetoacetoxyethyl methacrylate 132 parts by weight Stearyl methacrylate 132.6 parts by weight Methyl methacrylate 104.4 parts by weight n-Butyl methacrylate 148 parts by weight n-Butyl acrylate 15 parts by weight Isobutyl methacrylate 111 parts by weight Perbutyl O 3.3 Parts by weight

Production Example 10 Ethylene glycol monobutyl ether 18 was placed in a flask.
0 part by weight was added, and the mixture was heated to 110 ° C., nitrogen gas was introduced into the flask to replace air. Then, the following monomer mixture liquid was dropped into the flask over 2 hours. Dimethylaminoethyl methacrylate 27 parts by weight Diacetone acrylamide 90 parts by weight Styrene 78 parts by weight Methyl methacrylate 79 parts by weight Stearyl methacrylate 90 parts by weight n-Butyl acrylate 86 parts by weight Azobisisobutyronitrile 1.35 parts by weight Hold at 110 ° C. However, after the completion of dropping, 1.35 parts by weight of perbutyl O was dropped at 2 hours and 3 hours, respectively, and the mixture was kept at 110 ° C. for 2 hours and then cooled to obtain a resin solution. The resulting resin had a number average molecular weight of about 17,000 by gel permeation chromatography (GPC). Ethylene glycol monobutyl ether and benzyl alcohol were added to the obtained resin solution so that the total amount of ethylene glycol monobutyl ether was 70 parts by weight and the amount of benzyl alcohol was 10 parts by weight with respect to 100 parts by weight of the resin solid content, and acetic acid was further added to 0%. After adding 5 equivalents of neutralizing amount and stirring well,
Dilute with deionized water to a solid content of 19% and adjust to pH
A cationic resin aqueous solution J of 5.73 was obtained.

Production Example 11 A resin solution was obtained in the same manner as in Production Example 10 except that the monomer mixture liquid to be blended in the flask was prepared as follows. The resulting resin had a number average molecular weight by GPC of about 13,000. Dimethylaminoethyl methacrylate 27 parts by weight Diacetone acrylamide 60 parts by weight Styrene 120 parts by weight Methyl methacrylate 120 parts by weight Stearyl methacrylate 90 parts by weight n-Butyl acrylate 33 parts by weight Azobisisobutyronitrile 1.35 parts by weight Resin solution obtained Ethylene glycol monobutyl ether and benzyl alcohol were added so that the total amount of ethylene glycol monobutyl ether was 80 parts by weight and the amount of benzyl alcohol was 20 parts by weight with respect to 100 parts by weight of the resin solid content. After adding sufficient amount and stirring well, it is diluted with deionized water until the solid content becomes 18%, and the cationic resin aqueous solution K having a pH of 5.10.
I got

Production Example 12 In Production Example 10, the composition of the monomer mixture liquid to be incorporated in the flask was as follows, and the reaction temperature was 110 ° C.
To 120 ° C., a resin solution was obtained in the same manner as in Production Example 10. The resulting resin had a number average molecular weight by GPC of about 15,000. Acrylic acid 15 parts by weight Diacetone acrylamide 90 parts by weight Styrene 80 parts by weight Methyl methacrylate 80 parts by weight Stearyl methacrylate 90 parts by weight n-Butyl acrylate 95 parts by weight Perbutyl O 9 parts by weight Ethylene glycol monobutyl ether is added to the obtained resin solution and resin. The total amount of ethylene glycol monobutyl ether was 60 parts by weight based on 100 parts by weight of the solid content, and triethylamine was added in an amount to neutralize 0.6 equivalent, and the mixture was stirred well and the solid content was adjusted to 1 with deionized water.
It diluted to 6% and the aqueous solution L of anionic resin of pH 8.73 was obtained.

Example 1 Emulsion A obtained in Preparation Example 1 was diluted with deionized water to a solid content of 25% by weight, and emulsion A was further added.
Anion type electrodeposition coating composition A-1 was obtained by adding 50 parts by weight of ethylene glycol monobutyl ether to 100 parts by weight of the solid content. A cold-rolled steel sheet was immersed in this electrodeposition coating, and anion electrodeposition coating was performed at an applied voltage of 100 V for 3 minutes. After electrodeposition, pull up the coated plate, wash with water, and then at 80 ℃
And dried for 10 minutes to form a coated plate having a coating film having a dry film thickness of about 23 μm. The coated plate was immersed in an aqueous solution of a crosslinking agent having a liquid temperature of 25 ° C. shown in Table 1 below for 30 minutes, washed with water and dried at 80 ° C. for 10 minutes to obtain a cured coated plate.

Examples 2 to 6 and Comparative Example 1 A cured coated plate was obtained in the same manner as in Example 1 except that the composition of the aqueous solution of the crosslinking agent and the liquid temperature were as shown in Table 1 below.

Example 7 The emulsion A obtained in Production Example 1 was diluted with deionized water so that the solid content was 25% by weight, and the emulsion A was further added.
Anion-type electrodeposition coating composition A-2 was obtained by adding 53 parts by weight of ethylene glycol monobutyl ether and 27 parts by weight of benzyl alcohol to 100 parts by weight of the solid content. In Example 1, electrodeposition paint A-1
A cured coated plate was obtained in the same manner as in Example 1 except that the electrodeposition coating material A-2 was used instead.

Comparative Example 2 A cured coated plate was obtained in the same manner as in Example 7, except that the electrodeposited coated plate was not immersed in the aqueous crosslinking agent solution.

Examples 8 to 11 and Comparative Example 3 Emulsion B obtained in Production Example 2 was diluted with deionized water so that the solid content was 30% by weight, and Emulsion B was further added.
Anion-type electrodeposition coating composition B-1 was obtained by adding 50 parts by weight of ethylene glycol monobutyl ether to 100 parts by weight of the solid content. A cured coated plate was prepared in the same manner as in Example 1 except that the electrodeposition coating composition B-1 was used instead of the electrodeposition coating composition A-1 and the composition of the aqueous solution of the crosslinking agent was as shown in Table 1. Got

Examples 12 to 15 and Comparative Example 4 The aqueous resin solution C obtained in Production Example 3 was diluted with deionized water so that the solid content was 23% by weight, and the solid content of the aqueous resin solution C was 100 parts by weight. On the other hand, 24 parts by weight of ethylene glycol monobutyl ether and 10 parts by weight of benzyl alcohol were added to obtain anionic electrocoating composition C-1. In Example 1, the electrodeposition coating material C-1 was used instead of the electrodeposition coating material A-1, the composition of the aqueous solution of the crosslinking agent was as shown in Table 1, and the immersion in the aqueous solution of the crosslinking agent and the drying after washing with water were performed. A cured coated plate was obtained in the same manner as in Example 1 except that it was left at room temperature for 6 hours.

Example 16 and Comparative Example 5 Anion-type electrodeposition coating composition was prepared by adding 15 parts by weight of benzyl alcohol to 100 parts by weight of the solid content of the resin aqueous solution D to the resin aqueous solution D obtained in Example 4. D-1 was obtained.
In Example 1, the electrodeposition coating material D-1 was used in place of the electrodeposition coating material A-1, the composition of the aqueous solution of the crosslinking agent was as shown in Table 1, and immersion in the aqueous solution of the crosslinking agent and drying after washing with water were performed. A cured coated plate was obtained in the same manner as in Example 1 except that it was left at room temperature for 6 hours.

Example 17 and Comparative Example 6 The emulsion E obtained in Production Example 5 was diluted with deionized water so that the solid content was 29% by weight, and the emulsion E was further added.
Anionic electrocoating composition E-1 by adding 22 parts by weight of benzyl alcohol to 100 parts by weight of the solid content of
I got In Example 1, the electrodeposition coating material E-1 was used in place of the electrodeposition coating material A-1, the composition of the aqueous solution of the crosslinking agent was as shown in Table 1, and immersion in the aqueous solution of the crosslinking agent and drying after washing with water were performed. A cured coated plate was obtained in the same manner as in Example 1 except that it was left at room temperature for 6 hours.

Examples 18 to 20 and Comparative Example 7 60 parts by weight of the cationic resin aqueous solution F obtained in Production Example 6 was added.
30 parts by weight of deionized water, 2 parts by weight of benzyl alcohol and 3 parts by weight of ethylene glycol monobutyl ether were added to obtain a cationic electrodeposition coating composition F-1. A cold-rolled steel sheet was immersed in this electrodeposition coating, and cationic electrodeposition coating was performed at an applied voltage of 120 V for 3 minutes. After electrodeposition, the coated plate was pulled up, washed with water, and then dried at 80 ° C. for 30 minutes to form a coated plate having a coating film having a dry film thickness of about 35 μm. This coated board is shown in Table 1 below.
After being immersed in a cross-linking agent aqueous solution having a liquid temperature of 25 ° C. for 30 minutes, it was washed with water and dried at 80 ° C. for 30 minutes to obtain a cured coated plate.

Example 21 and Comparative Example 8 60 parts by weight of the cationic resin aqueous solution G obtained in Production Example 7 was added.
40 parts by weight of deionized water was added to add cationic electrodeposition paint G-
Got 1. A cold-rolled steel sheet was immersed in this electrodeposition coating, and cationic electrodeposition coating was performed at an applied voltage of 60 V for 3 minutes. After electrodeposition,
The coated plate was pulled up, washed with water, and then dried at 80 ° C. for 10 minutes to form a coated plate having a coating film having a dry film thickness of about 20 μm. The coated plate was immersed in an aqueous solution of a crosslinking agent having a liquid temperature shown in Table 1 below of 25 ° C for 10 minutes, washed with water and dried at 80 ° C for 10 minutes to obtain a cured coated plate. In Comparative Example 8, immersion in the aqueous solution of the crosslinking agent was not performed.

Examples 22 to 26 and Comparative Example 9 Coating composition A-3 was prepared by adding 10 parts by weight of deionized water to 50 parts by weight of emulsion A obtained in Production Example 1 and diluting it. This coating material A-3 was applied to a cold-rolled steel sheet with a bar coater, air-dried for 60 minutes, and then dried at 80 ° C. for 30 minutes to give a dry film thickness of about 40 μm.
A coated plate having a coating film of 1. was formed. This coated plate was immersed in an aqueous solution of a crosslinking agent shown in Table 1 below, washed with water and dried at 80 ° C. for 30 minutes to obtain a cured coated plate.

Examples 27 and 28 and Comparative Example 10 The emulsion E obtained in Production Example 5 was used as it was as the coating material E-2. This coating material E-2 was applied to a cold-rolled steel sheet with a bar coater, air-dried for 60 minutes and then dried at 80 ° C. for 30 minutes to form a coated plate having a coating film having a dry film thickness of about 55 μm. This coated plate was immersed in an aqueous solution of a crosslinking agent shown in Table 1 below, washed with water and dried at 80 ° C. for 30 minutes to obtain a cured coated plate.

Examples 29 to 31 and Comparative Example 11 The resin solution H obtained in Production Example 8 was used as it was as the coating material H-1. This coating material H-1 was applied to a cold-rolled steel sheet with a bar coater, air-dried for 60 minutes and then dried at 80 ° C. for 30 minutes to form a coated plate having a coating film having a dry film thickness of about 34 μm.
This coated plate was immersed in an aqueous solution of a crosslinking agent shown in Table 1 below, washed with water and dried at 80 ° C. for 30 minutes to obtain a cured coated plate.

Examples 32 to 34 and Comparative Example 12 10 parts by weight of ethylbenzene was added to 20 parts by weight of the resin solution I obtained in Production Example 9 to dilute it, and this was used as the paint I-1. This paint I-1 was applied to a cold-rolled steel sheet with a bar coater, air-dried for 60 minutes and then dried at 80 ° C. for 30 minutes to form a coated plate having a coating film having a dry film thickness of about 24 μm. This coated plate was immersed in an aqueous solution of a crosslinking agent shown in Table 1 below, washed with water and dried at 80 ° C. for 30 minutes to obtain a cured coated plate.

Example 35 Example 1 is repeated except that the coating plate is contacted with the crosslinking agent aqueous solution having a liquid temperature of 25 ° C. for 30 minutes by spraying instead of immersing the coated plate in the crosslinking agent aqueous solution. A cured coated plate was obtained in the same manner as above.

Example 36 The cationic resin aqueous solution J obtained in Production Example 10 was used as it was as a cationic electrodeposition coating material J-1. A cold-rolled steel sheet was dipped in this electrodeposition paint, and cationic electrodeposition coating was performed at room temperature at an applied voltage of about 100 V for about 3 minutes. After electrodeposition, the coated plate was pulled up, washed with water, and then dried at room temperature for 1 day to give a dry film thickness of 59.
A coated plate having a coating film of μm was formed. The coated plate was immersed in a cross-linking agent aqueous solution (a) having a composition shown in Table 6 below at a liquid temperature of 20.
After immersing at 20 ° C for 20 minutes, rinse with water for 10 minutes.
It was dried at 0 ° C for 30 minutes to obtain a cured coated plate.

Examples 37 to 41 and Comparative Examples 13 and 14 In Example 36, the kind of article to be dipped in the electrodeposition coating material,
Example 36 except that the dry film thickness, the type of the crosslinking agent aqueous solution, the liquid temperature, and the immersion time were as shown in Tables 6 and 7.
A cured coated plate was obtained in the same manner as above. In Comparative Examples 13 and 14, the coated plate was not immersed in the aqueous crosslinking agent solution.

Example 42 The cationic resin aqueous solution K obtained in Production Example 11 was used as it was as a cationic electrocoating K-1. A cold-rolled steel sheet was dipped in this electrodeposition coating, and cationic electrodeposition coating was performed at room temperature at an applied voltage of about 80 V for about 3 minutes. After electrodeposition, the coated plate was pulled up, washed with water, and then dried at room temperature for 1 day to give a dry film thickness of 32μ.
A coated plate having a coating film of m was formed. The coated plate was immersed in a cross-linking agent aqueous solution (a) having a composition shown in Table 6 below at a liquid temperature of 20.
After immersing at ℃ for 10 minutes, rinse with water for 10 minutes.
It was dried at 0 ° C for 30 minutes to obtain a cured coated plate.

Examples 43 to 47 and Comparative Examples 15 and 16 In Example 42, the kind of article to be dipped in the electrodeposition coating,
Example 42 except that the dry film thickness, the type of the crosslinking agent aqueous solution, the liquid temperature, and the immersion time were as shown in Tables 6 and 8.
A cured coated plate was obtained in the same manner as above. In Comparative Examples 15 and 16, the coated plate was not immersed in the aqueous crosslinking agent solution.

Example 48 The anionic resin aqueous solution L obtained in Production Example 12 was used as it was as an anionic electrocoating composition L-1. A cold-rolled steel sheet was immersed in this electrodeposition paint, and anion electrodeposition coating was performed at an applied voltage of about 100 V for about 4 minutes. After electrodeposition, the coated plate was pulled up, washed with water, and then dried at room temperature for 1 day to form a coated plate having a coating film with a dry film thickness of 72 μm. This coated plate was immersed in a crosslinking agent aqueous solution (a) having a composition shown in Table 6 below at a liquid temperature of 20 ° C. for an immersion time of 10 minutes, washed with water and then at 100 ° C. for 3 minutes.
It was dried for 0 minutes to obtain a cured coated plate.

Examples 49 to 53 and Comparative Examples 17 and 18 In Example 48, the kind of article to be dipped in the electrodeposition coating,
Example 48 except that the dry film thickness, the type of the crosslinking agent aqueous solution, the liquid temperature, and the immersion time are as shown in Tables 6 and 9.
A cured coated plate was obtained in the same manner as above. In Comparative Examples 17 and 18, the coated plate was not immersed in the aqueous crosslinking agent solution. Various tests were conducted on the cured coated plates obtained in Examples 1 to 53 and Comparative Examples 1 to 18 according to the following test methods. The test results are shown in Tables 1 to 5 and 7 to 9.

[0070]

[Table 1]

[0071]

[Table 2]

[0072]

[Table 3]

[0073]

[Table 4]

[0074]

[Table 5]

[0075]

[Table 6]

[0076]

[Table 7]

[0077]

[Table 8]

[0078]

[Table 9]

(Note) The coating method is described in Examples 1 to 17 and 35.
And 48-53, and Comparative Examples 1-6, 17 and 18 are anion electrodeposition and Examples 18-21 and 3
6 to 47, and Comparative Examples 7 and 8 and 13 to 16 were cationic electrodeposition, and Examples 22 to 34 and Comparative Examples 9 to 12 were used.
Is a bar coater painting. However, in Example 35 (* 1), the crosslinking agent aqueous solution was sprayed for 30 minutes. In Tables 7 to 9 in the column of the type of article to be coated, [untreated] represents [untreated cold-rolled steel sheet not subjected to chemical conversion treatment], and [treatment] is [zinc phosphate-treated cold-rolled steel sheet]. Represent Further, in Examples 36 to 53 and Comparative Examples 13 to 18, the solvent resistance test was conducted on the cured coated plates obtained by changing the drying conditions for obtaining the cured coated plates from 100 ° C-30 minutes to 80 ° C-10 minutes. As a result, in each Example and Comparative Example, the same results as the solvent resistance test results shown in Tables 7 to 9 were obtained.

Test Method Coloring of Coating Film: The coating film is visually observed to evaluate the degree of coloring. Those with no coloration are described as. Adhesion: Touch the coated surface with a finger and evaluate the degree of adhesion from the feeling. ⊚: No tackiness is felt at all: Slight tackiness is felt Δ: Significant tackiness is felt ×: Significant tackiness is felt Pencil hardness: JIS K5400 84.2 (19)
The pencil scratch test specified in 90) is performed and the breakage of the coating film is evaluated. Solvent resistance: 0.05 cc of acetone is placed on the coated surface, left at room temperature, and the traces on the coated surface where acetone has volatilized are visually observed. ⊚: No change was observed: Slight wrinkles were observed Δ: Significant wrinkles were observed ×: Dissolution of coating film was observed Erichsen value: JIS K5400 8.22 (1
990) According to the Erichsen value by the breaking distance method, a steel ball is extruded from the back surface of the Erichsen test piece using an Erichsen tester to measure the extrusion distance until cracks and peeling occur in the coating film. If there is no cracking or peeling even when extruded by 7 mm, it is displayed as 7 <. Impact resistance: JIS K5400 8.3.2 (19
90) According to the DuPont type impact resistance test, the weight of the falling weight is 50
The test was carried out by changing the drop height of the weight with the coated surface facing upward under the condition of 0 g and the tip diameter of the hammer of 1/2 inch. The maximum drop height that does not cause paint damage is displayed. When the coating film is not damaged even at 50 cm, it is displayed as 50 <. Water resistance: The state of the coated surface after immersing the cured coated plate in deionized water for 12 hours is evaluated. ◎: No abnormalities on the coated surface: Slight whitening on the coated surface △: Significant whitening on the coated surface ×: Significant whitening on the entire coated surface or breaks in the coating film

[0081]

In the method of the present invention, after the uncured coating film is formed, the coating film is contacted with an aqueous solution containing a curing agent to be cured, so that the coating material used can have a long pot life. In addition, after coating, the coating film can be leveled sufficiently, so that the coating surface has good smoothness, and the reaction between the carbonyl group in the coating film and the polyhydrazide compound is room temperature or low temperature forced drying up to about 100 ° C. It can be carried out at a temperature, and under this temperature condition, a practical cured coating film having good solvent resistance and coating film hardness can be formed. In the method of the present invention,
If the paint is applied by electro-deposition, it can be applied to articles with complicated shapes, has good adhesion efficiency, has few problems in occupational health, and can reduce the solvent content in the applied uncured coating film. Therefore, the step of drying the contact surface with the aqueous solution as the curing agent can be omitted, which is advantageous.

Claims (14)

[Claims] 1. A coating material containing a carbonyl group-containing resin as a binder is applied to an article to form an uncured coating film having an unreacted carbonyl group, and the uncured coating film contains a polyhydrazide compound. A method for forming a cured coating film, which comprises contacting an aqueous solution to cure the coating film. 2. By immersing the uncured coating film on the article to be coated in an aqueous solution containing a polyhydrazide compound,
The method for forming a cured coating film according to claim 1, wherein the coating film and the aqueous solution are brought into contact with each other. 3. The method for forming a cured coating film according to claim 1, wherein the carbonyl group-containing resin is a copolymer of a carbonyl group-containing vinyl monomer and another vinyl monomer. 4. The carbonyl group-containing vinyl monomer is 0.5 in all the monomer components constituting the carbonyl group-containing resin.
The method for forming a cured coating film according to claim 3, wherein the cured coating film is -60% by weight. 5. The method for forming a cured coating film according to claim 3, wherein the ionic monomer contained in the other vinyl monomer is 30% by weight or less in all the monomer components constituting the carbonyl group-containing resin. 6. The method according to claim 3, wherein the other vinyl monomer contains 5 to 50% by weight of an alkyl ester of acrylic acid or methacrylic acid having 12 to 30 carbon atoms in all monomer components constituting the carbonyl group-containing resin. A method for forming a cured coating as described. 7. The method for forming a cured coating film according to claim 3, wherein the carbonyl group-containing vinyl monomer is diacetone acrylamide. 8. The cured coating film according to claim 1, wherein the carbonyl group-containing resin contains an ionic group and the paint is a water-based paint. Forming method. 9. The method for forming a cured coating film according to claim 8, wherein the article to be coated is electrically conductive, and the water-based paint is applied to the article to be coated by electrodeposition coating. 10. The method for forming a cured coating film according to claim 1, wherein the polyhydrazide compound is carbodihydrazide. 11. An aqueous solution containing a polyhydrazide compound contains 1 to 60 parts by weight of a water-soluble organic solvent in 100 parts by weight of the aqueous solution, according to claim 1. A method for forming a cured coating as described. 12. The method for forming a cured coating film according to claim 1, wherein the aqueous solution containing the polyhydrazide compound is an aqueous solution containing 30% by weight or less of an acid component. 13. The method for forming a cured coating film according to claim 12, wherein the acid component added to the aqueous solution containing the polyhydrazide compound is a phosphorus atom-containing acidic compound. 14. The method according to claim 1, wherein the reaction between the carbonyl group in the coating film and the polyhydrazide is carried out at a low temperature forced drying temperature of 15 ° C. to 100 ° C.
The method for forming a cured coating film described in the item.