JPH0125489B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aqueous resin dispersion, and more specifically, as a coating composition for baking on metals.
In particular, the present invention relates to an aqueous resin dispersion that can form an excellent film as a paint for the inner surface of a can. Conventionally, it has been desired to shift paints for cans and anticorrosion paints to water-based paints from the viewpoints of resource conservation, energy conservation, and environmental pollution. As with the solvent-based type, epoxy resin-based ones have been mainly studied in water-based systems, and various methods have been proposed for dispersing epoxy resins in water. For example, as a method for dispersing an epoxy resin in water using a surfactant, two methods are known: a method using an anionic surfactant and a method using a nonionic surfactant. However, in the former case, the oxirane ring opens during the emulsification process and storage, resulting in decreased reactivity and poor performance of the formed coating, and sometimes problems with thickening and gelation during storage. On the other hand, in the latter case, from the viewpoint of dispersibility and storage stability, the system contains a fairly large amount of surfactant, so this surfactant may cause chemical and mechanical damage to the formed coating film. tends to have an adverse effect on character. As a solution to this problem, various self-emulsifying epoxy resins have been proposed in which epoxy resins are modified with acrylic resins and segments with emulsifying power are introduced into the molecules. For example, JP-A-53-1228 discloses a grafted polymer obtained by polymerizing a monomer mixture containing a carboxylic acid monomer using a free radical generator such as benzoyl peroxide in the presence of an epoxy resin. It has been shown that epoxy resins can be stably dispersed in aqueous media containing bases. JP-A-53-14963 and JP-A-Sho
Publication No. 55-9433 discloses that a partial reactant containing excess carboxyl groups obtained by reacting an acrylic resin with a relatively high molecular weight aromatic epoxy resin can be stably dispersed in an aqueous medium in the presence of ammonia or amine. It is shown. JP-A-55-3481 and JP-A-55-3482 disclose that epoxy resins containing substantially oxirane groups are obtained by esterifying a carboxyl group-functional polymer with an epoxy resin in the presence of an amine esterification catalyst. A self-emulsifying epoxy ester copolymer is disclosed that is self-emulsifying in water with a base. Unexamined Japanese Patent Publication 1987-
No. 105418 and Japanese Patent Application Laid-Open No. 198513 disclose a low-molecular compound having an epoxy group and an acryloyl group in one molecule obtained by partially reacting an aromatic epoxy resin and (meth)acrylic acid, and acrylic acid. Alternatively, an aqueous dispersion composition obtained by polymerizing a monomer mixture containing methacrylic acid and neutralizing it with a basic compound is disclosed. Since the self-emulsifying epoxy resin obtained by the above technique does not contain a surfactant in the coating material, a strong coating film can be obtained by itself. When a faster curing speed is required, water-soluble amino resins or phenolic resins are added to these paints. For example, an appropriate amount of water-soluble amino resin can improve the curing speed without reducing the physical properties of the formed coating film, and can sometimes increase the crosslinking density to obtain a desirable coating hardness. When used as a paint for internal surfaces, low molecular weight compounds originating from the amino resin are eluted into the contents of the can during heat sterilization, posing a hygiene problem. The present inventors have made extensive studies to overcome the above-mentioned problems, and as a result, have arrived at the present invention. That is, the present invention comprises an acrylic resin A containing 12 to 70% by weight of monobasic carboxylic acid monomer units as an essential component, and an aromatic epoxy resin having an average of 1.1 to 2.0 epoxy groups in one molecule. B
A composite resin composition with an excess of carboxyl groups obtained by mixing a partial combination D of and a phenol resin C represented by the following formula is prepared in the presence of ammonia or amine in an amount such that the final composition has a pH of 4 to 11. An aqueous resin dispersion made by dispersing in an aqueous medium. (In the formula, R ₁ is a hydrogen atom or has 1 or more carbon atoms.
12 alkyl groups, R ₂ and R ₃ each represent a hydrogen atom or a methylol group, and n represents an integer of 1 to 3. ). The aqueous resin dispersion in the present invention preferably contains 12 to 70% by weight of monobasic carboxylic acid monomer.
By chemically bonding an acrylic resin A obtained by copolymerizing a copolymerizable monomer mixture containing an aromatic epoxy resin B having an average of 1.1 to 2.0 epoxy groups per molecule and a phenol resin C. That's what you get. Acrylic resin A is prepared by mixing a monomer mixture consisting of a monobasic carboxylic acid monomer such as acrylic acid or methacrylic acid with other copolymerizable monomers in an organic solvent using a common solvent such as azobisisobutyronitrile or benzoyl peroxide. It can be obtained by copolymerizing using a radical polymerization initiator at a temperature of 80°C to 150°C. The copolymerizable monomers include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, and 2-acrylate. Acrylic esters such as ethylhexyl, n-octyl acrylate, decyl acrylate, dodecyl acrylate, methyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, n- methacrylate Methacrylic acid esters such as hexyl, n-octyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, and dodecyl methacrylate, styrene monomers such as styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene, and chlorstyrene. , hydroxy group-containing monomers such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, N-methylol (meth)acrylamide, N
It can be selected from one or more of N-substituted (meth)acrylic monomers such as -butoxymethyl (meth)acrylamide, epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, and acrylonitrile. The amount of monobasic carboxylic acid monomer used is 12 to 70% by weight based on the total amount of monomers, and if the amount is less than 12% by weight, the dispersion stability in an aqueous medium and the adhesion of the painted film to metal may be improved. When used for the interior of cans, solvent resistance, and flavor suitability, it is not preferable.On the other hand, if the amount used is more than 70% by weight, the viscosity of the reaction system when polymerizing acrylic resin A is Not only is it difficult to manufacture because it is extremely expensive,
The water resistance of the painted film and the boiling resistance when used on the inner surface of cans deteriorate. The weight average molecular weight of the acrylic resin A is preferably in the range of 3,000 to 80,000; if the weight average molecular weight is less than 3,000, the crosslinking density of the coating film will increase, which will impede processability; If the size is larger, gelation tends to occur more easily during reaction with the aromatic epoxy resin B. Aromatic epoxy resin B is obtained by condensing bisphenol A and epihalohydrin in the presence of an alkali catalyst, and has an average of 1.1 to 2.0 epoxy groups in one molecule, and a number average molecular weight of 300. or more, preferably 900 or more are used. Commercially available products include Epicote 828, Epicote 1001, Epicote 1004, manufactured by Ciel Chemical Co., Ltd.
Examples include Epicote 1007 and Epicote 1009. In addition, as an aromatic epoxy resin, a modified epoxy resin in which the epoxy group of the bisphenol A type epoxy resin is reacted with a vegetable oil fatty acid such as dehydrated castor oil, soybean oil fatty acid, or coconut oil fatty acid or a modifier such as bisphenol A is used. You can also use The main component of the phenolic resin C in the present invention is represented by the following formula. (In the formula, R ₁ is a hydrogen atom or has 1 or more carbon atoms.
12 alkyl groups, R ₂ and R ₃ each represent a hydrogen atom or a methylol group, and n represents an integer of 1 to 3. ) Phenol resin C is obtained by addition condensation of formaldehyde to alkylphenol in the presence of an alkali catalyst, but after producing a dimethylolated product of alkylphenol in high yield at a relatively low temperature of room temperature to about 60°C, A method of proceeding with condensation or other known synthetic means can be used.
As the alkylphenol, p-cresol,
o-cresol, p-ethylphenol, p-
Tert-butylphenol, p-octylphenol, p-nonylphenol, etc. can be used. The reaction conditions for producing such a phenolic resin can be freely selected within a range that satisfies the above requirements. Of course, there is nothing wrong with reacting under reaction conditions that allow a specific n number of phenolic resins C to be obtained in a high yield, further purifying by a conventional method, and using substantially as a single substance. It is also possible to prepare two or more types of alkylphenols with different types or with different n numbers, and use them by mixing them. In addition to phenolic resin C, known phenolic resins can be used in combination. As the phenolic resin used in combination, there are resol type phenolic resins and novolak type phenolic resins which have been used in conventional epoxy-phenolic paints. These phenolic resins can be used in an amount that does not impair the properties caused by the use of phenolic resin C, that is, in an amount that does not exceed about 50% by weight. In the present invention, the acrylic resin-aromatic epoxy resin partially bonded product D is in one molecule with the acrylic resin A obtained by copolymerizing a copolymerizable monomer mixture containing 12 to 70% by weight of a monobasic carboxylic acid monomer. It can be produced by partially reacting the aromatic epoxy resin B with an aromatic epoxy resin B having an average of 1.1 to 2.0 epoxy groups. To prepare an acrylic resin-aromatic epoxy resin partial reaction product, in a hydrophilic organic solvent such as ethylene glycol monobutyl ether, in the presence of ammonia or amine as described below, at 60°C to 170°C for 10 It is best to stir for about 2 minutes to 2 hours. Control of the reaction can be checked by measuring the percentage of oxirane, measuring the increase in viscosity or charting the molecular weight distribution by gel vermiaction chromatography (GPC). In addition, if the reaction is carried out in a relatively high boiling point solvent such as hexyl cellosolve, butyl cellosolve, methyl cellosolve acetate, or ethyl cellosolve acetate at 120°C or higher, acrylic resin A can be used without the coexistence of an esterification catalyst such as ammonia or amine. and aromatic epoxy resin B can be obtained. The reaction can also be controlled by measuring the % oxirane. The method for measuring oxirane% is as follows:
A known method is to add a predetermined amount of tetraethylammonium bromide solution to a sample solvent solution and titrate it with standardized perchloric acid using crystal violet as an indicator. When applying the titration method, the end point of the titration is often unclear, perhaps due to the inhibitory effect of excess carboxyl groups present.
Quantification by proton NMR is convenient and preferred. In proton NMR, the methylene of the oxirane group is 2.5~
Since it is at 2.9 ppm, track this peak area during the reaction and compare it with other reference peaks, such as the area of the proton peak of the benzene ring contained in aromatic epoxy resin, to determine the rate of reduction of the oxirane group. be able to. At this time, if a monomer having a benzene ring is used in the acrylic resin, the amount must be taken into account in the calculation. The reduction rate of oxirane groups in the reaction stage is 5% relative to the oxirane content of the aromatic epoxy resin as a raw material.
95%, more preferably 30 to 70%. If the reduction rate of oxirane groups is less than 5%, the acrylic resin-aromatic epoxy resin partial reaction product cannot be sufficiently self-emulsified in the aqueous medium and tends to separate during storage, while if it is greater than 95%, the The processability of the film tends to deteriorate. In particular, aqueous resins obtained with oxirane groups in the range of 30 to 70% are excellent in coating suitability. In the present invention, the acrylic resin-aromatic epoxy resin partial bond D is the aromatic epoxy resin B.
monobasic carboxylic acid monomer in the presence of 12~
It can be obtained by polymerizing a copolymerizable monomer mixture containing 70% by weight using a relatively large amount of an organic peroxide such as benzoyl peroxide. In this case, an aromatic epoxy resin grafted with an acrylic resin is obtained. The acrylic resin-aromatic epoxy resin partial bond D in the present invention also has a double bond and an epoxy group obtained by reacting the aromatic epoxy resin B and a monobasic carboxylic acid monomer in the presence of a base. Compounds with 12 monobasic carboxylic acid monomers
It can be obtained by polymerizing a copolymerizable monomer mixture containing ~70% by weight using a radical polymerization initiator. The solid content ratio of the acrylic resin A and the aromatic epoxy resin B is selected from the range of 1:1 to 1:6. In the present invention, the composite resin composition can be obtained by mixing the acrylic resin-aromatic epoxy resin partial bond D and the phenol resin C, preferably in a hydrophilic solvent. The amount of phenol resin C in the composite resin composition is 2 to 40% by weight based on the total amount of resin, and if it is less than 2% by weight, the effect on the curing speed of the coating film will not be sufficient; If it exceeds this amount, physical properties such as processability of the coating film tend to deteriorate. In the present invention, the aqueous resin composition may be prepared by adding ammonia or amine to the composite resin composition in an amount such that the final composition has a pH of 4 to 11 and dispersing it in an aqueous medium. When a high boiling point solvent is used, it is preferable to remove these solvents in advance under reduced pressure. Examples of the above amines include alkylamines such as trimethylamine, triethylamine, and butylamine; alcohol amines such as 2-dimethylaminoethanol, diethanolamine, triethanolamine, and aminomethylpropanol;
Morpholine etc. are used. Polyvalent amines such as ethylenediamine and diethylenetriamine can also be used. In the present invention, the aqueous medium means water alone or a mixture with a hydrophilic organic solvent in which at least 10% by weight is water, and examples of the hydrophilic organic solvent include methanol, ethanol, n-propanol, isopropanol, n-butanol, Alkyl alcohols such as sec-butanol, tert-butanol, isobutanol, ether alcohols such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, methyl carbitol, ethyl carbitol, ethers such as methyl cellosolve acetate, ethyl cellosolve acetate, etc. Esters, dioxane, dimethylformamide, diacetone alcohol, etc. are used. The aqueous resin dispersion of the present invention uses a phenolic resin with excellent reactivity, so it has excellent curability.
The resulting coating has excellent extraction properties. It also has extremely high adhesion to metals. The aqueous resin dispersion according to the present invention can be used as a paint by adding a surfactant, an antifoaming agent, etc. to improve coating properties, if necessary. Suitable substrates are metal plates such as untreated steel plates, treated steel plates, galvanized iron plates, and tin plates.As for the coating method, spray painting such as air spray, airless spray, and electrostatic spray is preferable. Dip coating, roll coater coating, electrodeposition coating, etc. are also possible. Also, the baking conditions are temperature 150
You can choose from ℃ to 230℃ and time from 2 to 30 minutes. The aqueous resin dispersion of the present invention can also be used in rust-preventing primers, printing inks, anti-corrosion paints, etc. by adding appropriate rust preventive agents, pigments, fillers, etc., depending on the purpose. The present invention will be explained below using examples. In addition,
In the examples, "parts" and "%" indicate "parts by weight" and "% by weight," respectively. Example 1 [Preparation of phenolic resin solution] 136 parts of p-tert-butylphenol, 162 parts of a 37% formaldehyde aqueous solution, and 160 parts of a 25% aqueous sodium hydroxide solution were placed in a flask, reacted at 50°C for 3 hours, and then treated with hydrochloric acid. Neutralize and separate water. After water separation, 250 parts of p-tert-butylphenol, 10
Add 3.7 parts of hydrochloric acid and 250 parts of water, stir for about 30 minutes, and when the heat generation has finished, add 160 parts of 25% sodium hydroxide.
part, add 120 parts of 37% formaldehyde aqueous solution to 50 parts.
℃ for 3 hours, neutralized with hydrochloric acid, separated the aqueous layer, repeated water washing and water separation three times, and dissolved in a mixed solvent of n-butanol/xylene/=1/1.
A 60% phenolic resin solution was obtained. As a result of analyzing the obtained resin by GPC, it was found that 91% was a dimethylolated trimer of p-tert-butylphenol, and the rest were dimethylolated monomers, dimethylolated dimers, and tetramers. It contained a small amount of dimethylolated product. [Preparation of acrylic resin solution] Styrene 300.0 parts Ethyl acrylate 210.0 Methacrylic acid 90.0 Ethylene glycol monobutyl ether 388.0 Benzoyl peroxide 12.0 1/4 of the mixture with the above composition was placed in a four-necked flask that had been replaced with nitrogen gas, and heated to 80 to 90°C. Heat it, keep it at that temperature and gradually drop the remaining amount over 2 hours, and after the dropwise addition is finished, stir it at that temperature for another 2 hours, then cool it, and the acid value is 93 (in terms of solid content, the same applies hereafter).
A carboxyl group-containing resin solution with a solid content of 59.7% and a viscosity of 4100 cps (25°C; all viscosities hereinafter refer to measurement results at 25°C) was obtained. [Preparation of epoxy resin solution] Epicote 1007 500 parts Ethylene glycol monobutyl ether 333.3 parts Pour the entire amount into a four-necked flask purged with nitrogen gas, gradually heat to raise the internal temperature to 100°C, stir for 1 hour, and dissolve completely. Cool to ℃, solids content 60%
An epoxy resin solution was obtained. [Preparation of aqueous dispersion] 50 parts of the above acrylic resin solution 100 parts of the above epoxy resin solution 2-dimethylaminoethanol 4.8 30 parts of the above phenolic resin solution Ion exchange water 355.2 In a four-necked flask, add and neutralize with stirring. After this, the temperature was raised to 80°C, reacted for 30 minutes, and then cooled. before and after reaction
The bond between acrylic resin and epoxy resin was confirmed by GPC measurement. After cooling, the solution was added and stirred to make a homogeneous solution, and then added gradually while stirring, resulting in a solid content of 20% and a viscosity of 425 cps.
A milky white dispersion was obtained. The resulting dispersion was heated to 50°C.
Although it was stored for 3 months, no abnormalities were observed. Example 2 [Preparation of phenol resin solution] 108 parts of p-cresol, 162 parts of a 37% formaldehyde aqueous solution, and 160 parts of a 25% aqueous sodium hydroxide solution were placed in a flask, reacted at 50°C for 2 hours, and then heated to 100°C. After heating and reacting at 100℃ for an additional hour, neutralization with hydrochloric acid, n-butanol/xylene/
A 60% phenol resin solution was obtained by extraction with a 1/1 mixed solvent. As a result of GPC analysis, 50℃, 2
At the time point, more than 90% of the reaction product was a dimethylol compound of p-cresol, and the final product was 9
% is dimethylolated p-cresol, 36% is dimethylolated dimer, 41% is dimethylolated trimer, 9% is dimethylolated tetramer, and 5% is dimethylolated pentamer or more. It was hot. The acrylic resin solution and epoxy resin solution were prepared in the same manner as in Example 1. [Preparation of aqueous dispersion] 50 parts of the above acrylic resin solution 100 parts of the above epoxy resin solution 4.8 parts of 2-dimethylaminoethanol After the addition, the temperature was raised to 80°C, reacted for 30 minutes, and then cooled. before and after reaction
The bond between acrylic resin and epoxy resin was confirmed by GPC measurement. After cooling, the solution was added and stirred to make a homogeneous solution, and then gradually added while stirring, the solid content was 20% and the viscosity was 390 cps.
A milky white dispersion was obtained. The resulting dispersion was heated to 50°C.
Although it was stored for 3 months, no abnormalities were observed. Comparative Example 1 An acrylic resin solution and an epoxy resin solution were prepared in the same manner as in Example 1. [Preparation of aqueous dispersion] 50 parts of the above acrylic resin solution 100 parts of the above epoxy resin solution 2-dimethylaminoethanol 4.8 ion-exchanged water 295.2 In a four-necked flask, charge , and bring the liquid temperature to 80
℃, reacted for 30 minutes, and cooled. before and after reaction
GPC measurements confirmed the reaction between epoxy resin and acrylic resin. Further, when the mixture was gradually added with stirring, a milky white dispersion with a solid content of 20% and a viscosity of 362 cps was obtained. No abnormalities were observed in the obtained dispersion when it was stored at 50°C for 3 months. Comparative Example 2 [Preparation of phenolic resin solution] 136 parts of p-tert-butylphenol, 162 parts of a 37% formaldehyde aqueous solution, and 80 parts of a 25% aqueous sodium hydroxide solution were placed in a flask, reacted at 100°C for 2.5 hours, and then diluted with hydrochloric acid. After mixing, extract with a mixed solvent of n-butanol/xylene/=1/1, and
% phenolic resin solution. As a result of GPC analysis, unreacted p-tert-butylphenol 8
%, dimethylolated product of p-tert-butylphenol 16%, dimethylolated product of dimers to tetramers 21%, 5
It was 55% dimethylol compound. The acrylic resin solution and epoxy resin solution were prepared in the same manner as in Example 1. In addition, the preparation of the aqueous dispersion is
The same procedure as in Example 1 was carried out except that the above phenolic resin solution was used as the phenolic resin solution. The resulting dispersion had a solids content of 20% and a viscosity of 412 cps. Comparative Example 3 An acrylic resin solution and an epoxy resin solution were prepared in the same manner as in Example 1. In addition, the preparation of the aqueous dispersion is
Cymel 325 instead of 30 parts of phenolic resin solution
(Water-soluble amino resin manufactured by Mitsui Toatsu Co., Ltd., solid content 80%)
The same procedure as in Example 1 was carried out except that 22.5 parts of . The resulting aqueous dispersion had a solids content of 20% and a viscosity of 386 cps.
It was hot. The aqueous dispersions obtained in Examples 1 to 2 and Comparative Examples 1 to 3 were applied on a tin plate to a thickness of 8 to 10μ, and dried by baking at 165°C and 200°C for 5 minutes each to create a test panel. did. The results of various resistance tests are shown in the table. In addition, the above aqueous dispersion was sprayed onto the inner surface of a 2-piece tin can with a content of 250 ml.
Cans with internal coatings were prepared by baking and drying at 165°C and 200°C for 5 minutes each, and their various resistances were tested. The results are shown in the table. From the table, Examples 1 and 2 and Comparative Example 2 containing phenolic resin or melamine resin,
Sample No. 3 exhibited superior performance to Comparative Example 1 in retort resistance, corrosion resistance, and saline storage tests. However, Examples 1 and 2 are similar to Comparative Examples 2 and 3.
Compared to other products, the amount of potassium permanganate consumed is extremely small and the extraction properties are excellent, as well as excellent flavor retention. The table and various test methods in the table are as follows. (1) Adhesion: Approximately 1.5mm using a knife on the coating surface
Make 11 vertical and horizontal cuts in the width of the goban. When a 24 mm wide cellophane adhesive tape is attached and strongly peeled off, the number of unpeeled areas in the goblin area is expressed in the numerator. (2) Retort resistance: After treatment in water at 125℃ for 30 minutes,
The coating film is judged visually and by peeling off the cellophane adhesive tape. (3) Workability: This occurs when using a special fold-type DuPont impact tester, placing a sample folded in half at the bottom, and dropping an iron weight weighing 1 kg with a flat contact surface from a height of 50 cm. The length of the crack in the paint film at the bent part was measured. 0 to 10 mm...marked ○ 10 to 20 mm...marked △ 20 mm or more...marked x. (4) Corrosion resistance: A test piece with an X cut made on the coating surface using a knife was placed in 1% saline solution at 125℃30.
The treatment is carried out for several minutes, and the degree of corrosion near the x mark is determined. Items with no abnormalities...〇 Items with slight corrosion...△ Items with significant corrosion...× (5) Potassium permanganate consumption: Fill a can with internal coating with 250ml of ion-exchanged water, and seal it. and 60
The samples were treated at -30 minutes at 100 degrees Celsius and at 100 degrees Celsius for 30 minutes, and measured according to the test method described in the Food Sanitation Act. (6) Salt solution storage test: 1% salt solution in a can with painted interior
After filling 250ml and sealing, pack them into cardboard boxes (15 cans in a box containing 30 cans) and apply vibration for 5 hours using a vibrator.
Saved for a month. The above test cans were opened and the amount of iron eluted into the saline solution was measured by atomic absorption spectrometry.
(Average of n: 15) (7) Flavor retention: ion exchange water 250% in inner coated can
ml, the can was sealed, sterilized at 100°C for 30 minutes, and then stored at 50°C for 6 months.The resulting solution in the can was then subjected to a flavor test. No change at all...〇 Slight change...△ Significant change...Indicated by ×. Example 3 [Adjustment of epoxy resin] Adjustment was made in the same manner as in Example 1. [Preparation of aqueous resin dispersion] The above epoxy resin solution 150 parts Butyl cellosolve 30 Methacrylic acid 30 Styrene 18 Ethyl acrylate 2 Benzoyl peroxide 3.5 Phenol resin solution of Example 2 30 2-Dimethylaminoethanol 4.8 Ion exchange water 560, 4 Pour into a two-necked flask and raise the temperature of the liquid to 115°C while stirring. Next, the above mixture was added dropwise over a period of 1 hour, and the reaction was continued for an additional 2 hours at 115°C. After cooling and stirring, the mixture was gradually added to obtain a stable aqueous dispersion. Using the obtained aqueous resin dispersion, tests similar to those shown in the table were conducted, and as a result, excellent properties were obtained in all items. Example 4 [Preparation of phenolic resin solution] 460 parts of a 11% aqueous sodium hydroxide solution was placed in a flask, and while stirring, 128 parts of a 92% aqueous paraformaldehyde solution was added little by little and dissolved, followed by p.
- 108 parts of cresol was charged and reacted at 50°C for 2 hours, then at 70°C for 6 hours, neutralized with hydrochloric acid, washed with water, and the slurry was extracted with n-butanol to obtain a 30% phenolic resin solution. As a result of GPC analysis, 2% is dimethylol of p-cresol, 90% is dimethylol of dimer, and 5% is dimethylol of p-cresol.
3% were dimethylolated trimers, and 3% were dimethylolated tetramers or more. [Preparation of aqueous dispersion] 50 parts of the acrylic resin solution of Example 1 100 parts of the epoxy resin solution of Example 1 4.8 parts of 2-dimethylaminoethanol 60 parts of the above phenolic resin solution 325.2 parts of ion-exchanged water Into a four-necked flask. After neutralizing by adding the mixture while stirring, the mixture was heated to 80°C, reacted for 30 minutes, and then cooled. before and after reaction
The bond between acrylic resin and epoxy resin was confirmed by GPC measurement. After cooling, the solution was added and stirred to make a homogeneous solution, and then added gradually while stirring, resulting in a solid content of 20% and a viscosity of 425 cps.
A milky white dispersion was obtained. The resulting dispersion was heated to 50°C.
Although it was stored for 3 months, no abnormalities were observed. Example 5 [Preparation of acrylic resin solution] Methyl cellosolve acetate 1000 parts Styrene 180.6 parts Ethyl acrylate 86 parts Methacrylic acid 163 parts Benzoyl peroxide 6.4 parts Reflux condenser, monomer tank, monomer flow rate regulator, thermometer, stirrer The attached four-necked flask was purged with nitrogen and charged. A monomer mixture and a polymerization catalyst were mixed in the monomer tank, and a quarter of the mixture was charged into the flask, which was then gradually heated and maintained at 105°C. The remaining mixed monomers were added over 2 hours, and after the dropwise addition was completed, stirring was continued for another 2 hours, and the mixture was cooled to room temperature.
The obtained solution had a solid content of 30.1%, a viscosity of UV (Gardner bubble viscometer, 25°C), and an acid value of 247 mgKOH/
g (in terms of solid content) of the acrylic resin solution. [Preparation of epoxy resin-acrylic resin partial reactant solution] 2100 parts of methyl cellosolve acetate 900 parts of Epicote 1009 1000 parts of the above acrylic resin solution A four-necked flask was equipped with a stirrer, a reflux condenser, a thermometer, and a solvent removal device. After purging with nitrogen, add and heat to 110°C and continue stirring. After the epoxy resin was completely dissolved, the mixture was heated to 135° C., and stirring was continued for 8 hours while maintaining this temperature to obtain an epoxy resin-acrylic resin partial reaction product. During this period, samples were taken out periodically to check their viscosity. At the end of the reaction, the solution had a solid content of 30.1% and a viscosity of UV. After this, part of the solvent was removed under reduced pressure, and the solid content was 60%.
And so. [Preparation of aqueous dispersion] 500 parts of the above epoxy resin-acrylic resin partial reactant 100 parts of the phenolic resin solution of Example 4 19.5 parts of 25% ammonia water 1180.5 parts of ion-exchanged water Charge the following into a four-necked flask and stir. Added some. After stirring for 30 minutes, the mixture was slowly added to obtain a yellowish milky white dispersion with a solid content of 20% and a viscosity of 480 cps. The obtained dispersion was stored at 50°C for 3 months, but no abnormality was observed. Example 6 [Preparation of epoxy acrylate resin solution] 646 parts of Epicote 1009, 349 parts of ethylene glycol monobutyl ether, 1 part of 10% sodium hydroxide solution, 0.02 parts of hydroquinone, 4 parts of methacrylic acid, stirred at 110°C for 2 hours, and cooled after confirming dissolution. did. was added at 100°C and added while heating. Reacted at 130℃ for 5 hours, acid value was 0.3
The process was terminated when the concentration decreased to mgKOH/g (in terms of solid content), and the mixture was cooled and taken out. The product had a number average molecular weight of 3800, an epoxy equivalent weight of 2750, and an average number of epoxy groups per molecule of 1.38. The solid content was 65% and the viscosity at 50°C was 80,000 cps. [Preparation of aqueous dispersion] Methyl ethyl ketone 40 parts Above epoxy acrylate resin solution
158.5 parts Styrene 15.4 parts Ethyl acrylate 18 parts Methacrylic acid 18 parts Ethylene glycol monobutyl ether 68.3 parts Azobisisobutyronitrile 0.5 parts Azobisisobutyronitrile 0.6 parts Phenolic resin solution of Example 4 57.3 parts Methyl ethyl ketone 10 parts Dimethylamino A flask was charged with 70 parts of a 10% aqueous solution of ethanol and 543.4 parts of ion-exchanged water, heated and refluxed, and the mixed solution of 10% was added little by little over 3 hours. After the addition was completed, the temperature was raised to 90°C, and the reaction was continued by adding water. It was sampled and cooled when the solid content reached 55% or more. After cooling, add toto and 15
After a few minutes, I added it little by little, and the solid content was 20.
%, an aqueous dispersion with a viscosity of 15 cps was obtained. Regarding the aqueous dispersions obtained in Examples 3 to 6,
A coating test was conducted in the same manner as in Example 1. The results of this test are shown in Table and Table.

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Claims (1)

[Scope of Claims] 1. Acrylic resin A containing 12 to 70% by weight of monobasic carboxylic acid monomer units as an essential component;
Partial combination D with aromatic epoxy resin B having an average of 1.1 to 2.0 epoxy groups in one molecule
A composite resin composition with an excess of carboxyl groups obtained by mixing phenol resin C represented by the following formula is dispersed in an aqueous medium in the presence of ammonia or amine in an amount such that the final composition has a pH of 4 to 11. Aqueous resin dispersion. (In the formula, R ₁ is a hydrogen atom or has 1 or more carbon atoms.
12 alkyl groups, R ₂ and R ₃ each represent a hydrogen atom or a methylol group, and n represents an integer of 1 to 3. ) 2 Acrylic resin-aromatic epoxy resin partial reaction in which acrylic resin-aromatic epoxy resin partial bond D is obtained by partially reacting acrylic resin A and aromatic epoxy resin B. The aqueous resin dispersion according to claim 1, which is a product. 3 Acrylic resin A and aromatic epoxy resin B
3. The aqueous resin dispersion according to claim 2, wherein the solid content ratio between the solid content and the solid content of the dispersion is from 2:1 to 1:6. 4. Claim 1, wherein the weight of the phenolic resin C is 2 to 40% by weight based on the total weight of the resin.
The aqueous resin dispersion according to items 1 to 3. 5. The aqueous resin dispersion according to claims 2 to 4, wherein the acrylic resin A has a weight average molecular weight of 3,000 to 80,000. 6 The number average molecular weight of aromatic epoxy resin is 900
The aqueous resin dispersion according to claims 1 to 5, which are the above.