JPS6313459B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to water-based coating compositions. Especially when the object to be coated is large and thick,
The present invention relates to a water-based coating composition that can be coated on objects for which the baking temperature cannot be raised by a simple forced drying method or normal temperature drying method. Conventionally, emulsion resin compositions or water-soluble resin compositions have been known as water-based coating compositions. By the way, the former type is usually dry at room temperature, but because it uses a large amount of dispersant and stabilizer, it is not often used in places where requirements such as corrosion resistance and alkali resistance are strict. Furthermore, the latter water-soluble resin composition is generally used in combination with a water-soluble aminoplast resin or the like, and then heated and dried at 150° C. or higher. In recent years, from the perspective of saving resources and energy, or when the object to be coated is extremely large and thick, it is therefore virtually impossible to dry it by heating at high temperatures. There has been an extremely high demand for an aqueous coating composition which can be baked and dried at a temperature of 100 mL, and which can form a coating film with excellent coating hardness, corrosion resistance, and the like. By the way, based on such requirements, water-based resins consisting of, for example, a water-soluble acrylic modified resin based on a drying oil-modified alkyd resin or an epoxy ester of a drying oil fatty acid, and an emulsion copolymer having a hydroxyl group or a carboxyl group have already been developed. Coating composition
-37892), an aqueous coating composition obtained by adding alcohol to a bisphenol-type epoxy resin, esterifying it with an unsaturated monocarboxylic acid, and copolymerizing a vinyl monomer (Japanese Patent Publication No. 48-32796); Alternatively, an aqueous coating composition obtained by copolymerizing a vinyl monomer with the double bond of epoxidized 1,2-polybutadiene having polymerizability (Japanese Patent Application Laid-open No. 7491/1983) can be baked at room temperature or low temperature. A dryable composition is presented. However, the coating composition as described above was heated to 100°C.
Unfortunately, the coating film obtained by baking and drying at the following temperature had insufficient surface hardness and corrosion resistance. On the other hand, conventional water-based coating compositions are
It is applied onto the object by shower painting, dipping, or electrodeposition, but in particular, the electrodeposition method, in which the paint is deposited on the object by electrochemical action, produces a smooth coating film. In order to obtain the desired coating performance,
In other words, baking at a relatively high temperature was required.
As described above, known aqueous coating compositions have the disadvantage that the appearance of the coating film (smoothness, film thickness distribution, etc.) deteriorates significantly if it is baked at a low temperature of 100°C or less after electrodeposition coating. . The present invention has been made to improve or eliminate the drawbacks of the prior art as described above. In other words, it has corrosion resistance even when baked at room temperature to about 100℃.
It is possible to form a coating film with excellent alkali resistance, solvent resistance, surface hardness, etc., and the appearance of the coating film is excellent even when applied by electrodeposition and baked at a low temperature of about 100℃ or less. The object of the present invention is to provide an aqueous coating composition capable of forming an excellent coating film in the following applications. That is, the present invention provides (a) an acid value of 25 to 50 and an iodine value of 50 to 150;
Moreover, a neutralized product of a resin containing unsaturated fatty acid monocarboxylic acid as one component...100 parts by weight (b) General formula (In the formula, R ₁ is H or CH ₃ ; R ₂ is

【formula】 【formula】

[Formula] There is Yeah

has a cyclic unsaturated _structure represented by [Formula _] ; Metal dryer (as metal component)
...Contains a proportion of 0.01 to 3 parts by weight, is dilutable with water, and can be used at room temperature or
This invention relates to an aqueous coating composition that can be baked at temperatures below 100°C. The resin having an acid value of 25 to 50, an iodine value of 50 to 150, and having an unsaturated aliphatic monocarboxylic acid as one component, which is related to the above (a) of the present invention, includes linseed oil, tung oil, It is a synthetic resin containing drying oil such as soybean oil, safflower oil, dehydrated castor oil, tall oil, or one or more of these fatty acids as one component.
Specifically, examples include alkyd resins (including maleated oil), epoxy ester resins, and resins containing unsaturated aliphatic monocarboxylic acids as one component. Particularly preferably, α,β-monoethylenically unsaturated carboxylic acid monomer and α,β-monoethylenically unsaturated carboxylic acid alkyl ester are combined in the presence of a drying oil-modified alkyd resin (including maleated oil). and at least one selected from alkenylbenzene
In the presence of a resin obtained by copolymerizing a seed monomer or a drying oil fatty acid ester of an epoxy resin, an α,β-monoethylenically unsaturated carboxylic acid monomer and an α,β-monoethylenically unsaturated carboxylic acid monomer are combined. It is a resin obtained by copolymerizing ethylenically unsaturated carboxylic acid alkyl ester and at least one monomer selected from alkenylbenzene. The alkyd resin is obtained by a known esterification reaction, for example, by reacting a drying oil or its fatty acid, a polyhydric alcohol, and a polycarboxylic acid or its anhydride at a temperature of 150 to 300°C while removing water sequentially. It is a resin with a weight average molecular weight in the range of about 500 to 50,000. The end point of the esterification reaction is determined by measuring the amount of water produced by the reaction or the acid value of the resin. The oil or fatty acid used in the production of the alkyd resin includes oils or fatty acids such as tall oil, dehydrated castor oil, linseed oil, safflower oil, soybean oil, tung oil, or fatty acids having 10 to 20 carbon atoms. Examples include straight chain unsaturated fatty acids having the following. Also,
Examples of the polyhydric alcohol used in producing the alkyd resin include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol,
1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2,2,4-trimethyl-1,
3-pentanediol, hydrogenated bisphenol A, 2,2-di(4-hydroxypropoxyphenyl)propane, glycerin, pentaerythritol, trimethylene glycol, 2-ethyl-
1,3-hexanediol, trimethylolpropane, 1,4-cyclohexanedimethanol,
1,4-bis(2-oxyethoxy)benzene,
Examples include 2,2,4,4-tetramethylcyclobutanediol-1,3, which may be used alone or as a mixture of two or more. Furthermore, the saturated or unsaturated polycarboxylic acids or their anhydrides used in the production of the alkyd resin include, for example, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride, and phthalic anhydride. , isophthalic acid, terephthalic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, hettic acid, 3,6-endomethylenetetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, Examples include methylnadic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, anthracene-maleic anhydride adduct, rosin-maleic anhydride adduct, and these may be used alone or as a mixture of two or more. In addition, maleated oil refers to the drying oil or semi-drying oil described above, which contains α, β such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, etc.
- A reaction product obtained by adding an ethylenically unsaturated dicarboxylic acid or its anhydride at a temperature of 140 to 260°C, and is a resin with a weight average molecular weight of about 1000 to 5000. In the present invention, the maleated oil may also be added to rosin, ester gum, coumaron resin,
Also included are resins modified with cyclopentadiene resin, petroleum resin, etc. In the present invention, in the maleation, α,
When a β-ethylenically unsaturated dicarboxylic acid anhydride is used, the acid anhydride group is ring-opened with water or alcohol. On the other hand, the esterified product of the drying oil fatty acid of the epoxy resin is an epoxy resin containing an epoxy group in the molecule, a drying oil or a semi-drying oil fatty acid (if necessary, α,β-ethylenically unsaturated dicarboxylic acid or its anhydride). (can be used in combination) and 100 to 250
Weight average molecular weight obtained by esterification, etherification or addition reaction at a temperature of °C, approximately 500 ~
It is a resin of about 30,000. The resin contains 1 carbon atom
It also includes those obtained by etherifying an epoxy resin with a saturated alcohol having ~20 atoms and then esterifying it with an α,β-ethylenically unsaturated carboxylic acid or fatty acid. The epoxy resin used in the present invention includes, for example, methyl epichlorohydrin or bisphenol A type diepoxy compounds obtained from epichlorohydrin and bisphenol A: halogenated bisphenols (for example, bisphenol tetrabromide A), resorcinol, bisphenol A, (Methyl)glycidyl ether compounds of various hydroxyl group-containing compounds such as phenol F, tetrahydroxyphenylethane, novolak, polyhydric alcohols (e.g. ethylene glycol, polypropylene glycol, glycerin, etc.): di(methyl)glycidyl phthalate;
Esterified diepoxy compounds such as di(methyl)glycidyl tetrahydrophthalate: Examples include epoxides of various unsaturated compounds such as polyolefins, unsaturated fatty acids, and unsaturated alicyclic compounds, and their weight average molecular weight is usually about 500 to 10,000. It is of a certain degree. Among these, use of bisphenol A type diepoxy compounds is particularly preferred. In the present invention, examples of the drying oil or semi-drying oil fatty acid to be reacted with the epoxy resin include linseed oil fatty acid, safflower oil fatty acid, soybean oil fatty acid, dehydrated castor oil fatty acid, and tall oil fatty acid. Further, examples of the α,β-ethylenically unsaturated dicarboxylic acid or its acid anhydride used as necessary include maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, and the like. The epoxy resin, the drying oil or semi-drying oil fatty acid, and the α,β-ethylenically unsaturated dicarboxylic acid or its anhydride used if necessary are usually 0.5 to 2.0 equivalents of carboxyl group per equivalent of epoxy group,
Preferably, the reaction is carried out at a ratio of 0.9 to 1.0 equivalent. When an α,β-ethylenically unsaturated dicarboxylic acid anhydride is used in the fatty acid addition reaction in the above, the acid anhydride group is ring-opened by water or alcohol. In the present invention, an α,β-monoethylenically unsaturated carboxylic acid monomer and an α,β-monoethylenically unsaturated carboxylic acid monomer are added to the drying oil-modified alkyd resin (including maleated oil) and the drying oil fatty acid ester of the epoxy resin. At least one monomer selected from ethylenically unsaturated carboxylic acid alkyl ester and alkenylbenzene is copolymerized. Examples of the α,β-monoethylenically unsaturated carboxylic acid monomer include α,β-monoethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, β-benzoyl acrylic acid, crotonic acid, and cinnamic acid. α,β-ethylenically unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, maleic anhydride, maleic acid monomethyl ester, or their anhydrides, or saturated linear chains thereof with 1 to 4 carbon atoms; Examples include monoesters with alcohols. Further, as the alkyl ester of the α,β-monoethylenically unsaturated carboxylic acid, for example, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, etc. ) acrylate, β-hydroxyethyl (meth)acrylate, β-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, monoester of (meth)acrylic acid of glycerin trimethylolpropane, glycidyl (meth)acrylate, etc. can be mentioned. Furthermore, examples of the alkenylbenzene include styrene, vinyltoluene, chlorostyrene, tert-butylstyrene, and the like. Other copolymerizable monomers as necessary, such as N-butoxymethyl (meth)acrylamide, N-tertiarybutyl (meth)acrylamide, dimethylaminoethyl (meth)acrylate, diacetone acrylamide , vinylpyrrolidone, N-methylolacrylamide, acrylamide, (meth)acrylonitrile, ethylene glycol mono(meth)acrylate, vinyl chloride, vinyl acetate, etc., or a combination of two or more thereof can be used. The resin related to (a) used in the present invention needs to have an acid value of 25 to 50 and an iodine value of 50 to 150. The acid value and iodine value were obtained by measuring according to methods 8.9 and 8.5 of JIS-K5400 (1979), respectively. In the above acid value range, if the acid value is less than 25, the water solubility and water dispersibility of the resin after neutralization will be extremely reduced, and the stability of the coating material will be poor due to sedimentation of the resin, which is not preferable. On the other hand, if the acid value exceeds 50, the water solubility of the neutralized resin becomes excessively high, resulting in poor water resistance, corrosion resistance, etc. of the coating film, which is not preferable. In addition, within the range of the iodine value, if the iodine value is less than 50, the crosslinking density of the final coating film will be low, and the water resistance and corrosion resistance of the coating film will be reduced; If it exceeds 150, the amount of fatty acids in the resin will inevitably increase, making it impossible to obtain a coating film with hardness that can withstand practical use under baking conditions of 100°C or lower, which is undesirable in either case. In the present invention, the resin particularly has a glass transition temperature (according to the logarithmic attenuation rate of JIS-K7213) of 0 to 30.
Preferably it is ℃. The glass transition temperature is 0
If the temperature is less than 100°C, it tends to be difficult to obtain sufficient coating hardness by baking at room temperature or below 100°C.
On the other hand, if the glass transition temperature exceeds 30°C, it becomes difficult to obtain sufficient leveling through the baking process.
There is a tendency that it is difficult to obtain a smooth coating film. In the present invention, basic compounds (neutralizing agents) for water-solubilizing or water-dispersing the resin include, for example, ammonia; alkanolamines such as monoethanolamine and triethanolamine; methylamine and dimethylamine. , trimethylamine, ethylamine, diethylamine, triethylamine, and other alkylamines; and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. In particular, it is preferable to use alkylamines having an alkyl group having 2 or less carbon atoms and ammonia in view of the corrosion resistance and water resistance of the final coating film, or the ease of bath management in the case of electrodeposition coating. The neutralizing agent is used alone or as a mixture in an amount such that the pH of the coating composition is in the range of 7.0 to 11.0. Next, a compound having a specific cyclic unsaturated structure and having the general formula (In the formula, R ₁ is H or CH ₃ : R ₂ is

【formula】 【formula】

[Formula] There is Yeah

[Formula]; X is -(CH ₂ -) _o O-, and n is an integer of 0 to 3). Component (b) acts as a catalyst for the oxidative polymerization reaction of the resin described in (a) above, and the compound itself also reacts to become a coating film-forming component, so it is good even under low temperature and short curing conditions. It is possible to form a coating film with excellent performance. Component (b) is used in an amount of 2 to 20 parts by weight per 100 parts by weight (solid content) of component (a). In the above usage range, if the amount of the compound used is less than 2 parts by weight, no effect of improving the low temperature drying properties of the coating film will be observed. On the other hand, if more than 20 parts by weight is used, the stability of the coating composition will be significantly impaired, so either case is not preferred. In addition, from the point of view of the effect of improving the drying properties of the coating film, the most preferable cyclic unsaturated structure (R ₂ ) is a dicyclopentenyl group. Furthermore, the metal dryer used as component (c) of the aqueous coating composition of the present invention includes, for example, organic acid salts of metals such as cobalt, manganese, lead, and zinc;
Sulfates, nitrates, chlorides, acetylacetonates, etc., specifically cobalt naphthenate, manganese naphthenate, lead naphthenate, zinc naphthenate, cobalt octenoate, manganese octenoate,
Oil-soluble compounds such as lead octenate, manganese stearate, lead stearate; cobalt formate, manganese formate, lead formate, cobalt acetate, manganese acetate, lead acetate, cobalt sulfate, manganese sulfate, cobalt nitrate, manganese nitrate, lead nitrate , cobalt chloride, manganese chloride, cobalt acetylacetonate, manganese acetylacetonate, and other water-soluble compounds. These are 1 type or 2
Can be used as a mixture of more than one species. In the present invention, the metal dryer is particularly suitable for cobalt, manganese, and lead naphthenes from the viewpoint of compatibility with the resin, or bath stability and workability when the coating composition is used for electrodeposition coating. Preference is given to using those selected from acid salts, octenoates and stearates. The metal dryer acts as a catalyst for oxidative polymerization of unsaturated bonds in the resin. That is, it promotes crosslinking of the resin to form a water-insoluble film, thereby improving the water resistance, corrosion resistance, etc. of the coating film. In the present invention, the metal dryer includes the above (a)
It is used in an amount of 0.01 to 3 parts by weight (as metal content) per 100 parts by weight of the component. If the amount of the metal dryer is less than 0.01 part by weight within the above usage range, there is a drawback that it is difficult to form a coating film with excellent water resistance, corrosion resistance, etc. On the contrary, 3.0
If the amount exceeds 1 part by weight, the stability of the coating composition will be significantly lowered, so it is not preferable to use more than 1 part by weight. The aqueous coating composition of the present invention can be obtained by dispersing the components (a), (b) and (c) in water. Furthermore, if necessary, pigments such as coloring pigments, extender pigments, and anticorrosive pigments, dyes, hydrophilic solvents, and various other additives can be added and mixed. In the present invention, the nonvolatile component of the coating composition can be about 5 to 50% by weight. The aqueous coating composition of the present invention thus obtained is
It is applied to the object to be coated by a coating method normally used for water-based coating compositions, such as spray coating, dipping coating, and electrodeposition coating. The applied item should then be kept at room temperature.
Heat at a temperature below 100℃ for about 5 minutes to 1 hour. As mentioned above, the aqueous coating composition of the present invention, that is, the neutralized product of the resin as the component (a), the (meth)acrylic acid ester having a cyclic unsaturated structure as the component (b), and
(c) By using a composition made of a metal dryer, it is possible to obtain excellent coating film performance such as sufficient appearance, hardenability, and corrosion resistance even when baking at a low temperature of room temperature to 100°C or less. Needless to say, it is of extremely high utility value industrially. Hereinafter, the details of the present invention will be explained with reference to Examples. Note that "parts" and "%" used herein indicate "parts by weight" and "% by weight." Example 1 196 parts of soybean oil fatty acid, phthalic anhydride by conventional method
111.2 parts of trimethylolpropane and 89.4 parts of trimethylolpropane were heated to 180 to 240°C in the presence of an inert gas to determine the resin acid value.
32 alkyd resins () were obtained. After adding 244.5 parts of ethylene glycol monobutyl ether to the resin and bringing the mixture to 90°C, 2 parts of benzoyl peroxide, 10 parts of methacrylic acid,
A mixture consisting of 30 parts of methyl methacrylate and 60 parts of styrene was gradually added dropwise, kept at the same temperature for 3 hours after the addition, and then rapidly cooled.
33 parts were added to obtain a modified alkyd resin solution A (resin acid value: 39, resin iodine value: 59, resin glass transition temperature: 15°C, non-volatile content: 62.6%). Separately, 1.2 parts of cobalt naphthenate (5% Co), 2.0 parts of lead naphthenate (15% Pb), and 3.2 parts of ethylene glycol monobutyl ether were thoroughly mixed to prepare metal dryer solution B. After mixing 240 parts of the modified alkyd resin solution, 10 parts of dicyclopentenyloxymethacrylate, and 6.4 parts of the metal dryer solution, 1250 parts of water was added little by little to obtain a water-based coating composition of the present invention. A mild steel plate (70 x 150 x 0.8 mm) was heated in the coating composition at a bath temperature of 29°C, an electrode ratio of 1/1, an inter-electrode distance of 15 cm, and a voltage.
Electrodeposition coating was performed under the conditions of 70V and 2 minutes of current application. After electrodeposition coating, various comparative tests were conducted on the coating film obtained by baking and drying at 90°C for 20 minutes.
The results are shown in Table 1. Example 2 After mixing 240 parts of resin solution A obtained in Example 1, 20 parts of dicyclopentenyloxymethacrylate, and 6.4 parts of metal dryer solution B, 1430 parts of water was added little by little to form the aqueous coating composition of the present invention. I got it. Electrodeposition coating was performed in the same manner as in Example 1. After electrodeposition coating, it was baked and dried at 90°C for 20 minutes, and then subjected to a comparative test. The results are shown in Table 1. Example 3 After mixing 240 parts of resin solution A obtained in Example 1, 5 parts of dicyclopentenyloxymethacrylate, and 6.4 parts of metal dryer solution B, 1250 parts of water was added little by little to form the aqueous coating composition of the present invention. I got it. Electrodeposition coating was performed in the same manner as in Example 1. After electrodeposition coating, it was baked and dried at 90°C for 20 minutes, and then subjected to a comparative test. The results are shown in Table 1. Example 4 After mixing 240 parts of resin solution A obtained in Example 1, 10 parts of dicyclopentenyloxymethacrylate, and 3.2 parts of metal dryer solution B, 1250 parts of water was added little by little to form the aqueous coating composition of the present invention. I got it. Electrodeposition coating was performed in the same manner as in Example 1. After electrodeposition coating, it was baked and dried at 90°C for 20 minutes, and then subjected to a comparative test. The results are shown in Table 1. Example 5 900 parts of an epoxy resin (epoxy equivalent: 450-500) which is a condensate of bisphenol A and epichlorohydrin, 830 parts of safflower oil fatty acid,
10 parts of fumaric acid was heated to 180°C in the presence of an inert gas to obtain an epoxy ester resin with a resin acid value of 30. After heating a mixture of the resin and 1040 parts of ethylene glycol monobutyl ether to 80°C,
A mixture consisting of 2 parts of α,α'-azobisisobutyronitrile, 10 parts of acrylic acid, 70 parts of n-butyl methacrylate, and 70 parts of vinyltoluene was gradually added dropwise, and the temperature was kept at the same temperature for 4 hours after the completion of the dropwise addition. After cooling rapidly, 88 parts of dimethylethanolamine was added to the modified epoxy ester resin solution C (resin acid value: 30,
Resin iodine value: 66, resin glass transition temperature: 21℃,
Non-volatile content: 62.7%) was obtained. 240 parts of the modified epoxy ester resin solution, 10 parts of dicyclopentenyloxyethyl acrylate
After mixing 6.4 parts of the metal dryer solution B,
1250 parts of water was added little by little to obtain a water-based coating composition of the present invention. Electrodeposition coating was performed in the same manner as in Example 1 using this composition. However, the painting voltage was 150V. After electrodeposition coating, it was baked at 80°C for 20 minutes and then subjected to a comparative test. The results are shown in Table 1. Example 6 The epoxy resin (epoxy equivalent: 450-500)
500 parts to 1000 parts of ethyl alcohol, xylol
After dissolving in 5,000 parts, a mixture of 100 parts of ethyl alcohol and 1 part of boron trifluoride (ethyl ether solution) was added, heated at reflux temperature for 1 hour, and then the solvent was distilled off under reduced pressure to bring the internal temperature down. The temperature was raised to 140°C and the solution was concentrated. 560 parts of linseed oil fatty acid was added to the concentrate, and the reaction was continued at 235+5° C. in the presence of an inert gas until the acid value became 10 or less. After adding 803 parts of ethylene glycol monoethyl ether to this resin and raising the temperature to 130°C,
A mixture consisting of 45 parts of butyl peroxide, 50 parts of maleic acid monomethyl ester, 100 parts of methyl methacrylate, and 150 parts of styrene was gradually added dropwise, kept at the same temperature for 3 hours after the addition was completed, then rapidly cooled, and 40 parts of diethanolamine was added. , modified epoxy ester resin solution (resin acid group: 23, resin iodine value: 80,
Resin glass transition temperature: 25℃, non-volatile content: 62.7%)
I got it. After mixing 240 parts of the modified epoxy ester resin solution, 10 parts of dicyclopentenyl acrylate, and 6.4 parts of the metal dryer solution B, 1250 parts of water was added little by little to obtain a water-based coating composition of the present invention. Electrodeposition coating was performed in the same manner as in Example 1 using this composition. However, the painting voltage was 200V. After electrodeposition coating, it was baked at 80°C for 20 minutes and then subjected to a comparative test. The results are shown in Table 1. Example 7 After mixing 240 parts of resin solution A obtained in Example 1, 10 parts of dicyclopentenyloxymethacrylate, and 6.4 parts of metal dryer solution B, 275 parts of water was added little by little to form the aqueous coating composition of the present invention. I got it. The same object to be coated as in Example 1 was immersed in the coating composition, and dip coating was performed at a bath temperature of 25°C. After dip coating, it was baked and dried at 100°C for 20 minutes, and then subjected to a comparative test. The results are shown in Table 1. Comparative Example 1 After mixing 240 parts of the resin solution A obtained in Example 1 and 6.4 parts of the metal dryer solution B, 1250 parts of water was added little by little to obtain a water-based coating composition of a comparative example. Electrodeposition coating was performed in the same manner as in Example 1. After electrodeposition coating, it was baked and dried at 90°C for 20 minutes, and then subjected to a comparative test. The results are shown in Table 1. Comparative Example 2 Alkyd resin obtained in Example 1 ()
(acid value: 32, resin iodine value: 81, resin glass transition temperature: -5°C) with ethylene glycol monobutyl ether added to adjust the non-volatile content to 62.5%.
After mixing 240 parts and 6.4 parts of metal dryer solution B, add water
1250 parts were added little by little to obtain a comparative aqueous coating composition. Electrodeposition coating was performed in the same manner as in Example 1. After electrodeposition coating, it was baked and dried at 90°C for 20 minutes, and then subjected to a comparative test. The results are shown in Table 1. Comparative Example 3 196 parts of soybean oil fatty acid, phthalic anhydride by conventional method
111.2 parts of trimethylolpropane and 89.4 parts of trimethylolpropane were heated to 180 to 240°C in the presence of an inert gas to determine the resin acid value.
32 alkyd resins were obtained. After the mixture of the resin and 351 parts of ethylene glycol monobutyl ether was heated to 90°C, a mixture consisting of 6 parts of benzoyl peroxide, 24 parts of methacrylic acid, 92 parts of methyl methacrylate, and 184 parts of styrene was gradually added dropwise, and the addition was completed. After maintaining the same temperature for another 3 hours, it was rapidly cooled, and then triethylamine was added.
Add 49 parts of modified alkyd resin solution (resin acid value:
41, Resin iodine value: 41, Resin glass transition temperature: 43
°C, non-volatile content: 62.7%). After mixing 240 parts of the modified alkyd resin solution and 6.4 parts of the metal dryer solution, 1250 parts of water was added little by little to obtain a comparative aqueous coating composition. Electrodeposition coating was performed in the same manner as in Example 1 using this composition. However, the painting voltage was 90V. After electrodeposition coating, it was baked at 90°C for 20 minutes and then subjected to a comparative test. The results are shown in Table 1. Comparative Example 4 196 parts of soybean oil fatty acid, phthalic anhydride by conventional method
103.8 parts of trimethylolpropane and 89.4 parts of trimethylolpropane were heated to 180 to 240°C in the presence of an inert gas to determine the resin acid value.
16 alkyd resins were obtained. After the mixture of the resin and 240 parts of ethylene glycol monobutyl ether was heated to 90°C, a mixture consisting of 2 parts of benzoyl peroxide, 1 part of methacrylic acid, 33 parts of methyl methacrylate, and 66 parts of styrene was gradually added dropwise, and the addition was completed. After maintaining the same temperature for another 3 hours, it was rapidly cooled, and then triethylamine 33
of the modified alkyd resin solution (resin acid value:
14, Resin iodine value: 60, Resin glass transition temperature: 14
°C, non-volatile content: 62.5%). After mixing 240 parts of the modified alkyd resin solution, 10 parts of dicyclopentenyloxymethacrylate, and 6.4 parts of the metal dryer solution, 1250 parts of water was added little by little to obtain a comparative water-based coating composition, but the resin was not water-dispersible and therefore could not be subjected to comparative tests.

【table】

[Table] From the above comparative test results, it is clear that the coating composition of the present invention has excellent coating appearance, hardness, impact resistance, salt spray resistance, alkali resistance, and xylene rubbing resistance even when baked at temperatures below 100°C. It can be seen that a coating film that can withstand practical use can be obtained in all properties such as. On the other hand, the coating films obtained from the compositions outside the technical scope of the present invention (Comparative Examples 1, 2, and 3) were particularly poor in salt spray resistance, alkali resistance, xylene rubbing resistance, or coating appearance. It was bad. or,
There were even some that could not be water-dispersed and therefore no coating composition could be obtained. (Comparative example 4)

Claims (1)

[Scope of Claims] 1 (a) An acid value of 25 to 50 and an iodine value of 50 to 150,
Neutralized resin containing unsaturated aliphatic monocarboxylic acid as one component...100 parts by weight (b) General formula (In the formula, R ₁ is H or CH ₃ ; R ₂ is [Formula] [Formula] [Formula] or [Formula]; X is -(CH ₂ -) _o - O-, and n is 0 A compound having a cyclic unsaturated structure represented by (an integer of ~3)
......2 to 20 parts by weight and (c) metal dryer (converted as metal component)
... Consisting of 0.01 to 3 parts by weight, water dilutable and at room temperature to 100%
Water-based coating composition that can be baked at temperatures below ℃. 2. Resin (a) is a mixture of α,β-monoethylenically unsaturated carboxylic acid monomer, α,β-monoethylenically unsaturated carboxylic acid alkyl ester, and alkenylbenzene in the presence of a drying oil fatty acid ester of epoxy resin. The aqueous coating composition according to claim 1, which is a neutralized product obtained by copolymerizing with at least one monomer selected from the following and then neutralizing with a basic compound. 3. Resin (a) is selected from α,β-monoethylenically unsaturated carboxylic acid monomers, α,β-monoethylenically unsaturated carboxylic acid alkyl esters, and alkenylbenzenes in the presence of a dry oil-modified alkyd resin. The aqueous coating composition according to claim 1, which is a neutralized product obtained by copolymerizing at least one monomer and then neutralizing with a basic compound. 4. The aqueous coating composition according to claim 1, wherein the resin (a) has a glass transition temperature of 0 to 30°C.