JPH0441191B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-based coating composition for electrodeposition coating that can be dried and cured at room temperature, and more particularly, it relates to a water-based coating composition for electrodeposition coating that can be dried and cured at room temperature, and more specifically, it mainly contains a water-solubilized or water-dispersed product of a specific fatty acid residue-containing resin, an amphiphilic organic solvent, and water. The present invention relates to a water-based paint composition for electrodeposition coating that dries at room temperature and contains the composition as a component. Electrodeposition coating has many advantages over other coating methods such as flow coating, brush coating, spray coating, and dip coating, and is used for coating various products including automobiles. There is. For example, compared to the other coating methods mentioned above, the electrodeposition coating method can coat difficult-to-coat areas with complex shapes with a uniform film thickness, and there is less loss of paint, making it more efficient to use. It has the advantages of being extremely high in corrosion resistance, and being less likely to run, sag, or sag on the painted surface. However, on the other hand, most conventional electrodeposition coatings use thermosetting water-based paints, which require baking at a high temperature of 100℃ or higher to harden the coating after electrodeposition. Therefore, it is difficult to apply to coated objects with a large heat capacity, or there are drawbacks such as large economic losses. Therefore, the present inventors have proposed that it would be possible to electrodeposit a water-based paint that dries and hardens at room temperature without baking the paint film, and to form a practical hardened paint film at room temperature. Considering that it is possible to eliminate the above-mentioned disadvantages while taking advantage of the above-mentioned advantages of the electrodeposition coating method, we have investigated a water-based paint composition that dries at room temperature and is suitable for electrodeposition coating. However, the properties that a water-based coating composition for use in electrodeposition coating should have include that the electrodeposition coating film formed from the coating composition dries and hardens at room temperature; It is required to meet the strict characteristics of For example, (1) the paint components have excellent stability in the electrodeposition bath without deteriorating due to hydrolysis, etc.;
(2) It must provide a coating film with excellent smoothness at room temperature; (3) It must have good throwing power. Therefore, the present inventors attempted electrodeposition coating using an alkyd resin-based or maleated polybutadiene-based emulsion type and aqueous solution type room-temperature-drying water-based paint that is generally used as a general-purpose paint. Of these, however,
With none of the emulsion-type water-based paints, a dense and smooth coating film could be obtained, and the throwing power was also insufficient. In addition, water-soluble alkyd resin paints have a limited film hardness and are forced to dry for a long time.
Moreover, since the alkyd resin is easily hydrolyzed in the electrodeposition bath and has poor bath stability, it has defects such as poor throwing power and roughness on the coated surface. On the other hand, water-soluble maleated polybutadiene paints are hardly hydrolyzed, but have poor drying properties at room temperature, so they are of little practical use. In this way, the above-mentioned water-based paints that dry at room temperature, which have been generally used as general-purpose paints, are different from the water-based paints that dry at room temperature and have excellent electrodeposition bath stability, coating film throwing power, coating film drying properties, and coating film smoothness. It does not have the performance required for an aqueous coating composition for electrodeposition, and it is difficult to use it for electrodeposition. However, surprisingly, the water-based coating composition containing components (A), (B), and (C) as main components described in detail below can be easily applied by electrodeposition.
It also has excellent bath stability, throwing power, and smoothness of the coating film, and even though drying properties are insufficient when applied with other coating methods, it can be applied by electrodeposition. Surprisingly, the inventors have discovered that the dry curing properties at room temperature are significantly superior, leading to the completion of the present invention. Therefore, according to the present invention, (A) in the presence of one or more selected from alkyd resins and epoxy resins modified with drying oil fatty acids and/or semi-drying oil fatty acids,
A water-soluble product of a fatty acid residue-containing resin obtained by polymerizing a polymerizable vinyl monomer component and having a glass transition temperature of -30 to 60°C, a content of the above fatty acid residue of 5 to 45% by weight, and an acid value of 15 to 200. or an aqueous dispersion, (B) water, and (C) an aqueous paint composition for electrodeposition coating that dries at room temperature, and whose main components are an amphipathic organic solvent that has an affinity with the above (A) and (B) components. is provided. In the present invention, since the polymer of the polymerizable vinyl monomer component is bonded to the fatty acid residue-containing resin of the component (A), it is hardly hydrolyzed in the electrodeposition bath, and the component (A) The aqueous coating composition of the present invention using the present invention has excellent electrodeposition bath stability, throwing power (ability to form a coating film of uniform thickness on all parts of the coated surface), and coating surface smoothness. There is. In addition, since the glass transition temperature of the fatty acid residue-containing resin of component (A) is adjusted to a specific range, the coating film after electrodeposition is oxidized based on the fatty acid residues of the drying oil or semi-drying oil. It is possible to obtain an initial hardness suitable for use simply by evaporation of volatile substances (water, organic solvents, etc.) from the coating film without polymerization, and the fatty acid residues undergo oxidative polymerization in the air. As a result, curing progresses further, and the flexibility, adhesion, fracture resistance, etc. of the coating film are further improved. By the way, when the content of fatty acid residues in component (A) increases, contact between the electrodeposition bath and air due to the opening of the electrodeposition bath increases, or when turnover becomes long, Although there is a possibility that the fatty acid residues undergo oxidative polymerization during bathing and deteriorate the coated surface condition, the electrodeposited coating film of the present invention has excellent initial hardness as described above, and moreover, as described below, Since the crosslinking reaction is carried out efficiently, the fatty acid residue content can be minimized in electrodeposition coating systems where such deterioration may occur, making it possible to eliminate such defects. Furthermore, the electrodeposition coating film formed from the aqueous coating composition of the present invention can be prepared by applying the aqueous coating composition to another coating method.
For example, it has significantly superior drying properties, flexibility, breaking strength, water resistance, etc., compared to coatings formed by spray painting, dipping coating, etc.
This technical effect is unexpected and
This is a surprising phenomenon. Although the basis for obtaining such technical effects is unknown, it is clear that almost no neutralizing agent is present in the coating film of the aqueous coating composition of the present invention deposited on the anode (object to be coated) by the electrodeposition coating method. The drying properties and water resistance of the coating film are improved because it does not contain any substances, and it is also free from oxygen gas generated at the anode and metal ions (e.g. iron, zinc, lead, calcium ions, etc.) released from the anode. The polymer chain (main chain)
The crosslinking reaction of the coating film is further promoted by the oxidative polymerization of the fatty acid residue of the drying oil or semi-drying oil that is bonded as a pendant side chain to It is surmised that performance such as durability is significantly improved compared to the other coating methods mentioned above. From this, it has become possible to efficiently carry out the crosslinking reaction based on the oxidative polymerization reaction of fatty acids, so the amount of fatty acids used can be reduced, contributing to improved stability of the electrodeposition bath. It is thought that this was created. Further, since the aqueous coating composition of the present invention contains a specific organic solvent, it has become possible to significantly improve the smoothness (gloss) of the coating film surface.
This is thought to be because the organic solvent is distributed into the coating film after electrodeposition and imparts flowability to the coating film. Hereinafter, the water-based coating composition according to the present invention will be explained in more detail. As described above, the aqueous coating composition comprises: (A) in the presence of one or more selected from alkyd resins and epoxy resins modified with drying oil fatty acids and/or semi-drying oil fatty acids;
A water-soluble product of a fatty acid residue-containing resin obtained by polymerizing a polymerizable vinyl monomer component and having a glass transition temperature of -30 to 60°C, a content of the above fatty acid residue of 5 to 45% by weight, and an acid value of 15 to 200. Or a water-based paint composition for electrodeposition coating that dries at room temperature and contains as a main component an aqueous dispersion (B) water, and (C) an amphiphilic organic solvent that has an affinity with the above (A) and (B) components. be. (A) Component: This is an alkyd resin modified with a drying oil fatty acid and/or a semi-drying oil fatty acid (hereinafter sometimes abbreviated as "modified alkyd resin") and an epoxy resin modified with the fatty acid (hereinafter referred to as "modified alkyd resin"). Polymerizable vinyl monomer components are polymerized in the presence of one or more selected from "modified epoxy resins" (sometimes abbreviated as "modified epoxy resins"). content of 5 to 45
It is a water-solubilized or water-dispersed product of a fatty acid residue-containing resin having an acid value of 15 to 200% by weight. First, modified alkyd resin is a polyhydric alcohol,
It is obtained by reacting a polybasic acid and a drying oil fatty acid (and/or a semi-drying oil fatty acid) in a conventional manner, and the content of fatty acid residues in the modified alkyd resin is 10 to 10. 70% by weight, especially 20 to 60% by weight, and the acid value is preferably 100 or less, especially 70 or less. Examples of the polyhydric alcohol used in the production of the modified alkyd resin include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, ethylene glycol, propylene glycol, neopentyl glycol, etc., and examples of the polybasic acid include ( (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, (anhydrous) trimellitic acid, glutaric acid, adipic acid, (anhydrous)
Maleic acid, itaconic acid, tetrahydro (anhydrous)
Examples include phthalic acid and fumaric acid. The drying oil fatty acid and the semi-drying oil fatty acid are components for imparting normal temperature drying properties to the obtained fatty acid residue-containing resin, and each molecule contains at least one carbon-carbon double bond that can be oxidatively polymerized. Higher unsaturated aliphatic carboxylic acids are preferably used and can generally contain from 6 to 30, preferably from 17 to 20 carbon atoms. Such fatty acids include drying oil fatty acids with an iodine value of 130 or higher and
80-130 semi-drying oil fatty acids are included, specifically tung oil fatty acids, dehydrated castor oil fatty acids, safflower oil fatty acids, linseed oil fatty acids, soybean oil fatty acids,
Sesame oil fatty acids, poppy oil fatty acids, eno oil fatty acids, hempseed oil fatty acids, grape nuclear fatty acids, corn oil fatty acids, tall oil fatty acids, sunflower oil fatty acids, cottonseed oil fatty acids, walnut oil fatty acids, rubber seed oil fatty acids, rice bran oil fatty acids, high diene fatty acids , etc., and these can be used alone or in combination of two or more. Among these, dehydrated castor oil fatty acids, safflower oil fatty acids, linseed oil fatty acids, soybean oil fatty acids, and tall oil fatty acids are particularly preferred. In addition, modified epoxy resin is obtained by esterifying polyepoxide and drying oil fatty acid and/or semi-drying oil fatty acid by a well-known method, and the content of fatty acid residues is usually 10% based on the modified epoxy resin. ~80% by weight, preferably 30-70% by weight
It is. Examples of polyepoxides used in the production of modified epoxy resins include bisphenol diepoxide, which is a reaction product of (methyl)epichlorohydrin and bisphenol A, ethylene glycol di(methyl)glycidyl ether, polypropylene glycol di(methyl)glycidyl ether, etc. Examples include aliphatic ether type diepoxides, di(methyl)glycidyl phthalate, di(methyl)glycidyl tetrahydrophthalate, etc., and among these, bisphenol type diepoxides are preferred. The fatty acid to be esterified into the polyepoxide is a drying oil fatty acid and/or a semi-drying oil fatty acid, and specifically, one or more fatty acids selected from the fatty acids explained in the production of the modified alkyd resin above. Can be used. Furthermore, in the present invention, modified alkyd resin,
Modified epoxy resins should be understood to include those produced as described above, in which maleic acid or its anhydride is added to fatty acid residues. Next, the polymerizable vinyl monomer components to be polymerized in the presence of these modified alkyd resins and/or modified epoxy resins include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate,
Alkyl acrylic acid or methacrylate (1 to 20 carbon atoms) such as lauryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, and lauryl methacrylate. ) Ester; Alkoxyalkyl ester of acrylic acid or methacrylic acid (2 to 30 carbon atoms) such as methoxyethyl acrylate, methoxyethyl methacrylate, methoxybutyl acrylate, methoxybutyl methacrylate, ethoxybutyl acrylate, and ethoxybutyl methacrylate. ; Hydroxyalkyl (carbon number 2 to 10) esters of acrylic acid or methacrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate; Acrylic acid or methacrylic acid such as allyl acrylate, allyl methacrylate, etc. Lower alkenyl esters of acids; mono- or di-lower alkylaminoalkyl esters of acrylic acid or methacrylic acid such as dimethylaminoethyl acrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, methylaminoethyl acrylate, methylaminoethyl methacrylate; allyloxyethyl acrylate , lower alkenyloxyalkyl esters of acrylic acid or methacrylic acid such as allyloxymethacrylate; dialkyl maleates such as dimethyl maleate and diethyl maleate; styrene, α-methylstyrene, vinyltoluene, P-
One or more selected from styrene derivatives such as chlorstyrene can be used, among which methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate ,
Methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate,
It is preferable to use butyl methacrylate, hexyl methacrylate, styrene, vinyltoluene, and the like. Furthermore, the acid value of the resin containing fatty acid residues was increased from 15 to 200.
As one means for adjusting the range, a polymerizable unsaturated carboxylic acid can be used in combination with the above polymerizable vinyl monomer component to copolymerize. The polymerizable unsaturated carboxylic acid is a mono- or polycarboxylic acid having an addition-polymerizable double bond between a carbon atom to which a carboxyl group is bonded and a carbon atom adjacent thereto, and having 3 to 8 carbon atoms. , especially 3 to 5, and 1 or 2 carboxyl groups.
The following general formula [In the formula, R ₁ represents a hydrogen atom or a lower alkyl group, R ₂ represents a hydrogen atom, a lower alkyl group, or a carboxyl group, and R ₃ represents a hydrogen atom, a lower alkyl group, -CH ₂ COOH, and Lower alkyl groups have 4 or less carbon atoms;
Particularly preferred is a methyl group. ] Compounds represented by, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid,
Maleic anhydride, fumaric acid, etc., and the following general formula [In the formula, R ₁ , R ₂ and R ₃ each have the same meaning as above. In addition, n is 2 to 6] Compounds such as β-carboxyethyl (meth)acrylate, γ-carboxypropyl (meth)acrylate, etc. are mentioned, and among these, acrylic acid and methacrylic acid are particularly preferred. Next, in polymerizing a polymerizable vinyl monomer component (including a polymerizable unsaturated carboxylic acid when used together) in the presence of a modified alkyd resin and/or a modified epoxy resin, the resin and the monomer component are polymerized. The proportions are based on their total weight ratio: the resin is 20-90% by weight, especially 30-70% by weight, the monomer component is 80-10% by weight, especially 70-30% by weight.
Weight percent is preferred. The polymerization reaction is achieved by blending the above-mentioned two components with a polymerization catalyst, an organic solvent, etc., and allowing the mixture to react at 50 to 160° C. while stirring.
Examples of polymerization catalysts include benzoyl peroxide, t-butyl perbenzoate, di-t-butyl peroxide, t-butyl peroxy-2-
Ethylhexanoate, cumene hydroperoxide, azobisisobutyronitrile, etc. can be used, and the organic solvent is one that dissolves each of the above components and their polymerization reaction products, and in particular, component (C) described below should be used. is suitable. Regarding the resin containing fatty acid residues obtained in this way, in order to improve the suitability for electrodeposition coating and various performances of the formed coating film, the content of fatty acid residues is 5 to 45% by weight, preferably 10 to 40% by weight. , more preferably
15~40% by weight, acid value 15~200, preferably 20~
It is important to adjust the glass transition temperature to -30 to 60°C, preferably 25 to 50°C, and even more preferably -23 to 40°C. Among these, the glass transition temperature can be easily adjusted mainly by adjusting the composition of the polymerizable vinyl monomer component and its constituent ratio. In addition, the acid value is, for example, the amount of polybasic acid used in the production of the modified alkyd resin, the amount of maleic acid added to the modified alkyd resin or modified epoxy resin, and the content of polymerizable unsaturated carboxylic acid in the polymerizable vinyl monomer component. The amount can be easily adjusted by any method selected. If the content of fatty acid residues is less than 5% by weight, sufficient oxidative polymerization drying (curing) of the electrodeposited coating cannot be expected and the strength will be insufficient, while if it exceeds 45% by weight, it will not be possible to dry (cure) the electrocoated film in an electrocoated coating bath. As oxidative polymerization progresses, bath stability decreases and a uniform coated surface cannot be obtained, and when the acid value is lower than 15, it becomes difficult to water-solubilize or water-disperse the fatty acid residue-containing resin, and electrophoresis On the other hand, if it is higher than 200, the water resistance, weather resistance, etc. of the coating film will deteriorate, so both are unfavorable and the object of the present invention cannot be achieved. In addition, the glass transition temperature of the resin containing fatty acid residues was measured using a torsional blade analyzer (manufactured by Rigaku Corporation, TBA-8120A1) based on the principle of free torsional vibration method under constant temperature rise. The temperature at which the mechanical damping index of the resin-impregnated fiber reaches its peak is measured. The fibers are impregnated with the resin by immersing the braid specified by the measuring device in a solution of the resin (ethyl acetate/butyl cellosolve = 1/1 solution with a solid content of 40% by weight), then pulling it up and vacuuming. It was prepared by drying to remove the solvent. The glass transition temperature of the resin containing fatty acid residues is −
If the temperature is lower than 30℃, the initial coating film hardening immediately after electrodeposition will not be sufficient, while if the temperature is higher than 60℃, the flexibility, adhesion, and impact resistance of the sufficiently oxidized and dried coating will decrease. So I don't like it. The structure of the fatty acid residue-containing resin obtained in this way is mainly that a polymerizable vinyl monomer is added to some of the unsaturated bond moieties contained in the fatty acid residues of the drying oil and/or semi-drying oil in the modified alkyd resin and modified epoxy resin. It is presumed that the components were graft polymerized, and if there are unsaturated bonds in the modified alkyd resin or modified epoxy resin other than unsaturated fatty acid residues, the polymerizable vinyl monomer component also exists in those parts. Naturally, graft polymerization is also possible. Therefore, when looking at modified alkyd resins in particular, the main skeleton of the resin itself contains many ester bonds, but because the polymerizable vinyl monomer component is graft-polymerized as described above, its hydrolysis resistance is extremely low. This has been improved, and there is almost no loss of bath properties of the electrodeposition bath. This also applies to modified epoxy resins. Water solubilization or water dispersion of the fatty acid residue-containing resin is carried out by neutralizing some or all of the carboxyl groups in the resin. Examples of neutralizing agents that can be used include ammonia, amines,
Examples include alkali metal hydroxides, alkali metal carbonates or bicarbonates. The amines that can be used include primary, secondary or tertiary alkyl amines; primary, secondary or tertiary lower alkanolamines; and cycloalkylamines. As the alkali metal hydroxide, potassium hydroxide, sodium hydroxide, etc. can be used; as the alkali metal carbonate or bicarbonate, sodium carbonate, sodium bicarbonate, etc. can be used. Among these neutralizing agents, triethylamine is particularly preferred. The amount of the neutralizing agent used can generally be 0.1 to 2.0 equivalents, preferably 0.5 to 1.2 equivalents, relative to the carboxyl groups in the resin. Note that fatty acids may deteriorate the stability of the electrodeposition bath, so it is preferable to keep the amount as small as possible; however, in electrodeposition coating systems where there is little contact between the electrodeposition bath and air and turnover is short, There is no problem even if it is contained in a large amount in the resin. (B) Water: Tap water, tap water, deionized water, etc. can be used. (C) Organic solvent: The aqueous coating composition of the present invention contains a solvent that improves the smoothness (gloss) of the coating film surface when the coating film formed by electrodeposition is dried and cured at room temperature. Therefore, it is necessary to mix an organic solvent. The organic solvent is distributed in the coating after electrodeposition and serves to impart flowability to the coating. As such an organic solvent, an amphiphilic organic solvent having an affinity with the components (A) and (B) mentioned above is used. Furthermore, in some cases, a non-hydrophilic organic solvent that has an affinity for component (A) but has no affinity for component (B) may be used in combination with the amphipathic solvent to improve the flow of the coating film. Malleability can be further improved. Among such organic solvents, examples of amphipathic solvents include those of the formula HO-
Cellosolve solvents represented by CH ₂ CH ₂ -OR ₄ [wherein R ₄ is an alkyl group having 1 to 10 carbon atoms], such as ethyl cellosolve, butyl cellosolve, etc.; formula HO-CH ₂ CH ₂ -O-CH ₂ CH ₂ −OR ₄ [However, R ₄ has the same meaning as above] Carbitol solvent such as methyl carbitol, butyl carbitol; formula HO−C ₃ H ₆ −
OR ₄ [However, R ₄ has the same meaning as above] Propylene glycol monoalkyl ether solvent such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc.; formula HO-C ₃ H ₆ -O-C _{3 H6} − _OR4
[However, R ₄ has the same meaning as above] Dipropylene glycol monoalkyl ether solvents such as dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, etc.; formula R ₅ O-CH ₂ CH ₂ -OR ₆ 〔however,
R ₅ and R ₆ are each an alkyl group having 1 to 6 carbon atoms], such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, etc.; formula R ₅ O-
Diglyme solvents represented by CH ₂ CH ₂ OCH ₂ CH ₂ −OR ₆ [wherein R ₅ and R ₆ have the same meanings as above], such as diethylene glycol dimethyl ether; formula R ₇ O-CH ₂ CH ₂ OCOCH ₃ [ However, R ₇ represents a hydrogen atom, CH ₃ or C ₂ H ₅ ] cellosolve acetate solvent such as ethylene glycol monoacetate, methyl cellosolve acetate, etc.; formula R ₈ OH [however, R ₈ represents a carbon atom number of 1 to 4] alcoholic solvents such as ethanol, propanol, n-butanol, sec-butanone, isobutanol and the like can be used. Furthermore, diacetone alcohol, dioxane, tetrahydrofuran, acetone, dimethylformamide, 3
-methoxybutyl acetate, 3-methoxy-3
-Methylbutanol and the like can also be used.
Among these, for example, cellosolve solvents [butyl cellosolve, ethyl cellosolve], carbitol solvents [butyl carbitol], alcohol solvents [n-propanol, n-butanol], 3-methoxybutyl acetate, 3-methoxy-3- Particularly preferred are amphiphilic organic solvents such as methylbutanol. On the other hand, as a non-hydrophilic solvent, for example, the formula

[Formula] [However, R ₉ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms] or the formula

[Formula] [However, R ₁₀ and R ₁₁ each represent an alkyl group having 1 to 4 carbon atoms] Aromatic hydrocarbons such as toluene, xylene, etc.; Formula R ₁₂ -COO-R ₁₃ [However, ,
R ₁₂ represents an alkyl group having 1 to 6 carbon atoms, and R ₁₃ represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a cyclohexyl group]
Acids or esters represented by the formula, such as ethyl formate, butyl acetate, cyclohexyl acetate, etc.
R ₁₄ R ₁₅ C=O [wherein R ₁₄ and R ₁₅ each represent an alkyl group having 1 to 8 carbon atoms] and

Ketones represented by [formula] such as methyl ethyl ketone, cyclohexanone, etc.;
R ₁₄ -O-R ₁₅ [However, R ₁₄ and R ₁₅ have the same meanings as above] Ethers such as ethyl ether, hexyl ether, etc.; R ₁₆
Examples include alcohols represented by OH (wherein R ₁₆ represents an alkyl group having 5 to 11 carbon atoms) such as hexanol. Among these, solvents selected from butyl acetate, cyclohexanone, hexanol, methyl ethyl ketone, octanol and benzyl alcohol are particularly preferred. The amount of these non-hydrophilic solvents to be blended is generally 70% by weight or less, preferably from 5 to 60% by weight, based on the total amount with the above-mentioned amphipathic solvent. The amount of these organic solvents (amphiphilic solvents alone or mixed with non-hydrophilic solvents) is generally 15 to 500 parts by weight per 100 parts by weight of fatty acid residue-containing resin.
Preferably 30 to 200 parts by weight, more preferably 50 parts by weight
~150 parts by weight is appropriate. The water-based coating composition of the present invention contains as main components the fatty acid residue-containing resin made water-soluble or water-dispersed, an organic solvent, and water, and can be used as is for electrodeposition coating. However, if necessary, coloring pigments, extender pigments, rust-preventing pigments, surfactants, etc. may be added as usual. Furthermore, it is possible to add commonly used metal salt desiccants such as cobalt naphthenate and lead naphthenate in order to improve the drying and curing properties of the coating film at room temperature. Since there is a risk of reducing the stability of bathing, it is preferable to select the amount added depending on the required degree of bath stability. Specifically, it is preferable to add the metal salt desiccant in an amount of 0.001 to 0.1 part by weight based on the amount of metal per 100 parts by weight of the fatty acid residue-containing resin. The aqueous coating composition of the present invention produced as described above can be widely used as a coating for electrodeposition coating. In electrodeposition coating, the electrodeposition coating bath is diluted so that the content of fatty acid residue-containing resin in the aqueous coating composition is generally 3 to 25% by weight, preferably 5 to 20% by weight. You can get it by twisting it. The object to be coated may be of any size and shape, as long as at least its surface is made of conductive metal. In particular, since the electrodeposited coating formed from the aqueous coating composition of the present invention does not need to be cured by heating,
It can be particularly advantageously applied to coated objects that have a large heat capacity and are difficult to cure by heating. Specifically, examples thereof include iron, aluminum, steel, and those whose surfaces have been subjected to chemical conversion treatment (for example, zinc phosphate treatment, iron phosphate treatment, etc.). The electrodeposition coating operation can be carried out in a manner known per se. For example, the temperature of the electrodeposition coating bath prepared as described above is set at 10 to 50°C, preferably 20 to 35°C.
The object to be coated is immersed in this as an anode, and the voltage between it and another cathode is 10 to 300 volts, preferably 30 to 250 volts, for 30 seconds to 20 minutes, preferably 1 to 10 volts. A coating film can be deposited on the surface of the object to be coated (anode) by applying electricity for a minute. Thereafter, the object to be coated is removed from the electrodeposition bath, the coated surface is washed with water if necessary, and the coated surface is left at room temperature to dry and harden the coated film. Of course, if necessary, the object to be coated may be cured by heating to an extent (approximately 250° C. or less) that the coating film components will not be thermally decomposed. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In addition, in the following, "part" and "%" are parts by weight and weight %, respectively. Example 1 (a) Production of resin containing drying oil fatty acid residue 1185 parts of dehydrated castor oil fatty acid,
532 parts of trimethylolethane, 765 parts of phthalic anhydride
1 part, 143 parts of trimellitic anhydride, and 1.3 parts of dibutyltin oxide, and heated to 180°C in the presence of nitrogen gas.
After heating for 13 hours, a modified alkyd resin having a solid content acid value of 59.2 was obtained. This product was cooled to 100°C, and 600 parts of n-butyl cellosolve was added to form a resin solution. Next, 666 parts of the above resin solution was added to the second flask.
Add 184 parts of n-butyl cellosolve and heat to 80°C, then add 350 parts of styrene and 100 parts of methyl methacrylate.
A mixture of 50 parts of methacrylic acid and 25 parts of azobisisobutyronitrile was added dropwise over about 2 hours. Add azobisisobutyronitrile every 30 minutes after completion of dripping.
Add 1.25 parts twice, hold at 80℃ for 2 hours, add n-butyl cellosolve, and reduce the resin solid content.
A resin solution was obtained with an n-butyl cellosolve solution viscosity of 62.5%, a resin solid acid value of 75.7, and a 60% solid content of _Z5 . (b) Production of water-based coating composition N-butyl cellosolve is added to the fatty acid residue-containing resin obtained in (a) above in an amount of 60 parts per 100 parts of resin solid content, and benzyl alcohol is added to the resin solid content. Added at a rate of 30 parts per 100 parts.
Then, the resin was neutralized using about 1 equivalent of triethylamine based on the total acid value of the resin. Next, the resin solid content is added to this neutralized resin solution.
Pigment Titanium Dioxide JR-600 (trade name, manufactured by Teikoku Kako Co., Ltd., rutile type titanium white) 29 per 100 parts
0.4 parts of Carbon Black MA-100 (trade name, Carbon Black, manufactured by Mitsubishi Kasei Corporation) and 400 parts of ion-exchanged water, and after dispersing with a paint conditioner, the total content of resin and pigment was determined. The mixture was diluted with ion-exchanged water to a concentration of 12% to obtain a water-based paint composition for electrodeposition coating. (c) Electrodeposition coating The above water-based paint composition for electrodeposition coating is placed in a hard polyvinyl chloride container that can be stirred with a magnetic stirrer, and the size of the electrode is 75 x 50 x 0.8 (mm).
A degreased and cleaned polished mild steel plate - SPCCJIS-G3141 was used as an anode and a cathode. A rectifier that converts DC voltage between both electrodes (Takasago Manufacturing Co., Ltd. TYPEG-25M)
GPO250-5) for 2 minutes. The distance between the electrodes was 15 cm, and both electrodes were each 10 cm deep in the bath composition.
immersed to a depth of After electrodeposition at 150 volts for 2 minutes, the mild steel plate on the anode side was removed from the bath and hung vertically to dry at room temperature. The stability of the electrodeposition coating composition in the electrodeposition bath and the performance test results of the resulting coating film are summarized in Table 1 below. Example 2 (a) Production of resin 1508 parts of Araldite 6071 (trade name, Ciba Geigy) and 1494 parts of safflower oil fatty acid were placed in the reaction vessel of 5.
part, soybean oil fatty acid 542 parts, dehydrated castor oil fatty acid 226 parts
of the resin was added and reacted for 2.5 hours at 230°C in the presence of an inert gas to give a resin solid content acid value of 20.6. Next, cool to 200℃, add 47 parts of fumaric acid,
The reaction was continued at 200°C for 2.5 hours until the resin acid value reached 20.6. After the reaction was completed, the mixture was cooled to 100°C, and 790 parts of n-butyl cellosolve was added to obtain a resin solution with a solid content of 81.4%. Next, add the above resin solution to reaction container 2.
737 parts, add 224 parts of n-butyl cellosolve, 100 parts
114 parts of styrene into this solution after heating to ℃
114 parts n-butyl methacrylate, methacrylic acid
A mixture of 71 parts of benzoyl peroxide and 12 parts of benzoyl peroxide was added dropwise over about 4 hours. After the completion of the dropwise addition, a mixture of 6 parts of benzoyl peroxide and 25 parts of n-butyl cellosolve was added in three portions every 30 minutes, and after the third addition was completed, the mixture was maintained at 100° C. for 2 hours. As a result, a resin solution was obtained with a resin solid content of 68.4%, a resin solid content acid value of 68.0, and an n-butyl cellosolve solution viscosity of 60% solid content of _Z4 . (b) Manufacture and electrodeposition of aqueous coating composition N-butyl cellosolve is added to the resin solution obtained in step a above at a concentration of 50 parts per 100 parts of the resin solid content, and benzyl alcohol is further added to the resin solution. After adding 30 parts per 100 parts, it was neutralized using about 1 equivalent of triethylamine based on the total acid value of the resin. Then, a pigment was dispersed in this neutralized resin solution in the same manner as in Example 1 (b) to obtain a coating composition for electrodeposition, and electrodeposition was applied in the same manner as in Example 1 (c). and was used for testing. The results are shown in Table 1 below. Comparative Example 1 The following ingredients Neopentyl glycol 52.5 parts Trimethylolpropane 68.25 parts Isophthalic acid 149.4 parts Trimellitic acid 13.44 parts Linseed oil fatty acid 70 parts Paratertiary butylbenzoic acid 26.7 parts A condensation reaction was carried out at 240°C for 7 hours. 30 parts of n-butyl cellosolve and 30 parts of benzyl alcohol were added to a drying oil fatty acid-modified alkyd resin with an acid value of 40, a Gardner viscosity of V to W, and a fatty acid content of 20%, and then the total acid value of the resin was About 1.0 equivalent of triethylamine was used for neutralization. Then, pigment per 100 parts of solid content of the alkyd resin.
30 parts of Titanium Dioxide JR-600, 0.4 parts of Carbon Black MA-100, and 1.0 part of Strontium Chromate were mixed together, and after being dispersed with a paint conditioner, the total content of resin and pigment was adjusted to 10%. This was diluted with ion-exchanged water to obtain an aqueous resin composition for electrodeposition coating. Electrodeposition coating was performed in the same manner as in Example 1, and the sample was subjected to a test as a comparative example. The results are summarized in Table 1 below. Comparative Example 2 The composition obtained up to the dispersion of the pigment in Example 1 was diluted with water and adjusted to a viscosity of 25 seconds for food cup No. 4, and a degreased and cleaned polished mild steel plate of 75 x 50 x 0.8 (mm) was prepared. A test board was prepared by spray painting SPCCJIS-G3141. A test plate with a film thickness of 20 μm in a dry state was used for the test. The results are shown in Table 1 below.

【table】

【table】

Claims (1)

[Claims] 1 (A) Polymerizing a polymerizable vinyl monomer component in the presence of one or more selected from alkyd resins and epoxy resins modified with drying oil fatty acids and/or semi-drying oil fatty acids. At least the glass transition temperature is -30~60℃, the content of the above fatty acid residue is 5~45% by weight, and the acid value is 15~200.
A water-solubilized or water-dispersed product of a fatty acid residue-containing resin, (B) water, and (C) an amphipathic organic solvent that has an affinity for the above (A) and (B) components, at room temperature. Water-based paint composition for dry electrodeposition coating.