JPH0125488B2 - - 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 coating for the inside 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. The reactivity decreases, resulting in poor performance of the coating film formed, and sometimes problems such as thickening and gelation occur during storage. Because they contain relatively large amounts of surfactants, these surfactants tend to have an adverse effect on the chemical and mechanical properties of the coatings formed. 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 is directed to an acrylic resin (A) containing 12 to 70% by weight of monobasic carboxylic acid monomer units as an essential component, an aromatic epoxy resin having an average of 1.1 to 2.0 epoxy groups in one molecule. A carboxyl group-excess composite resin composition containing a resin bond of resin (B) and phenolic resin (C) 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. In the aqueous resin dispersion, the acrylic resin (A) and the aromatic epoxy resin (B) are at least partially combined, and the phenolic resin (C) is combined with the acrylic resin (A) and/or the aromatic epoxy resin (B). The present invention relates to the above aqueous resin dispersion, which is precondensed with an epoxy resin (B). The aqueous resin dispersion in the present invention preferably contains 12 to 70% by weight of monobasic carboxylic acid monomer.
An acrylic resin (A) obtained by copolymerizing a copolymerizable monomer mixture containing a mixture of copolymerizable monomers, an aromatic epoxy resin (B) having an average of 1.1 to 2.0 epoxy groups in one molecule, and a phenol resin (C). It is obtained by chemically bonding. Acrylic resin (A) is produced by mixing a monomer mixture consisting of monobasic carboxylic acid monomers such as acrylic acid and methacrylic acid with other copolymerizable monomers in an organic solvent such as azobisisobutyronitrile or benzoyl peroxide. It can be obtained by copolymerization using a common 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
-N-substituted (meth)acrylic monomers such as butoxymethyl (meth)acrylic acid amide, epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, and one or more types of acrylonitrile can be selected. can. 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 used is less than 12%, the dispersion stability of the resin in an aqueous medium may be affected, and the metal resistance of the painted film may be affected. When used for the inside of cans, adhesion, solvent resistance, and flavor suitability are all deteriorated, which is undesirable.On the other hand, if the amount used is more than 70% by weight, it may cause reactions when polymerizing the acrylic resin (A). Since the viscosity of the system becomes extremely high, it not only becomes difficult to manufacture, but also deteriorates the water resistance of the painted film and the boiling resistance when used for can interior painting. The acrylic resin (A) preferably has a weight average molecular weight 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 it exceeds 40.000, especially 80.000, gelation tends to occur 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. Those having an 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, 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). Modified epoxy resins can also be used. The phenolic resin (C) is obtained by addition condensation of phenols and formaldehyde in the presence of a catalyst, and may be one in which the phenolic hydroxyl group or the alcoholic hydroxyl group is modified with a low molecular weight alcohol. The above catalysts include organic amines such as ammonia, ethylamine, butylamine, diethanolamine, etc., basic compounds such as sodium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, and hydrochloric acid, phosphoric acid, sulfuric acid, acetic acid, and oxalic acid. There are acidic compounds such as Phenols include p-cresol, o-cresol, p-
tert-butylphenol, p-ethylphenol,
Bifunctional phenols such as 2,3-xylenol and 2,5-xylenol, trifunctional phenols such as carbolic acid, m-cresol, m-ethylphenol, 3,5-xylenol, and m-methoxyphenol, and bisphenol (A ), tetrafunctional phenols such as bisphenol (B), etc. A particularly preferred phenolic resin is a phenolic resin (C) whose main component is a relatively low molecular weight phenolic resin 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. ) The above-mentioned relatively low molecular weight phenolic resin is obtained by addition condensation of formaldehyde to alkylphenol in the presence of an alkali catalyst. After generating with
A method of proceeding with condensation or other known synthetic means 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 no problem even if the phenolic resin (C) having a specific n number is reacted under reaction conditions that allow a high yield to be obtained, further purified by a conventional method, and used substantially as a single substance. Also, products with different types of alkylphenols or n
It is also possible to create two or more types with different numbers and use them in combination. The acrylic resin-aromatic epoxy resin partial bond (D) in the present invention is an 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 in one molecule. 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 permeation 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 can be produced even without the coexistence of an esterification catalyst such as ammonia or amine. (A) and aromatic epoxy resin (B)
A partial reaction product 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. The acrylic resin-aromatic epoxy resin partial bond (D) in the present invention is an aromatic epoxy resin (B).
monobasic carboxylic acid monomer in the presence of 12 to 70
% by weight of a copolymerizable monomer mixture 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 partially bonded product (D) in the present invention also has double epoxy groups and double A compound having both a bond and a monobasic carboxylic acid monomer in 12
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 precondensate of acrylic resin (A) or aromatic epoxy resin and phenol resin (C) is preferably prepared at 50°C or more in a hydrophilic solvent.
It can be obtained by reacting at 150°C for 10 minutes to 3 hours. In the present invention, the composite resin composition can be obtained using various methods. For example, (a) an aromatic epoxy resin-phenolic resin precondensate having an epoxy group and an acrylic resin (A) are reacted in the presence of ammonia or an amine. (b) The acrylic resin-aromatic epoxy resin partial bond (D) and the phenol resin (C) are subjected to a precondensation reaction at 50°C to 150°C for 10 minutes to 3 hours. (c) A copolymerizable monomer mixture containing 12 to 70% by weight of a monobasic carboxylic acid monomer in the presence of an aromatic epoxy resin-phenolic resin precondensate is mixed with an organic peroxide such as benzoyl peroxide. Use a large amount to polymerize. (d) After reacting an aromatic epoxy resin (B) with a monobasic carboxylic acid monomer in the presence of a base, and reacting a compound having both an epoxy group and a double bond with a phenol resin (C). A copolymerizable monomer mixture containing 12 to 70% by weight of a monobasic carboxylic acid monomer is polymerized using a radical polymerization initiator. The reactions (a) to (d) above are preferably carried out in a hydrophilic solvent. The amount of phenolic 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 contribution to the curing speed of the coating film will not be sufficient; % or more, 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 high boiling point solvents are 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. The aqueous resin dispersion of the present invention, which uses esters, dioxane, dimethylformamide, diacetone alcohol, etc., has excellent curability because it is used by precondensing the phenolic resin, and the resulting coating film has excellent extraction properties. Are better. In addition, it 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 and stir for about 30 minutes.
Once the exotherm has ended, add 25% sodium hydroxide.
Add 160 parts and 120 parts of 37% formaldehyde aqueous solution.
After reacting at 50℃ for 3 hours and neutralizing with hydrochloric acid to separate the aqueous layer, washing with water and separating the water were repeated 3 times, and the solution was dissolved in a mixed solvent of n-butanol/xylene/=1/1 to obtain 60% phenol. A 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 purged with nitrogen gas and heated to 80-90°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 was obtained with a solid content of 59.7% and a viscosity of 410.0 cps (25°C; all viscosities hereinafter refer to measurement results at 25°C). [Preparation of epoxy resin solution] Epicote 1007 500 parts Ethylene glycol monobutyl ether 333.3 Pour the entire amount into a four-necked flask purged with nitrogen gas and gradually heat to raise the internal temperature to 100°C, stir for 1 hour to completely dissolve, and then heat to 80°C. Cool to 60% solids
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 30 parts of the above phenol resin solution 2-dimethylaminoethanol 4.8 Ion-exchanged water 355.2 In a four-necked flask, charge , and at 100℃ for 2 hours with stirring. Made it react. GPC before and after reaction
It was confirmed through measurement that a portion of the epoxy resin and phenolic resin were bonded. The liquid temperature was lowered to 80°C, and the mixture was reacted for 30 minutes and cooled. The bond between the acrylic resin and epoxy resin was confirmed by GPC measurements before and after the reaction. Further, when the mixture was gradually added with stirring, a milky white dispersion with a solid content of 20% and a viscosity of 385 cps was obtained. The resulting dispersion was heated at 50°C.
It was stored for several months, but no abnormalities were observed. Example 2 [Preparation of phenol 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 to 60%
A phenolic resin solution was prepared. As a result of GPC analysis, 8% of unreacted p-tert-butylphenol,
Dimethylol of p-tertbutylphenol 16
%, dimethylolated products of dimers to tetramers, and dimethylolated products of pentamers or more were 55%. 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 phenol resin solution was used as the phenol example solution. The resulting dispersion had a solids content of 20% and a viscosity of 412 cps. Example 3 [Preparation of phenolic 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 for another hour at 100℃, neutralizing with hydrochloric acid, n-butanol/xylene =
Extraction was performed with a 1/1 mixed solvent to obtain a 60% phenolic resin solution. As a result of GPC analysis, more than 90% of the reaction product at 50°C for 2 hours 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. In addition, the preparation of the aqueous dispersion is
The same procedure as in Example 1 was carried out except that the phenolic resin solution was replaced with the above phenolic resin solution. The resulting dispersion had a solids content of 20% and a viscosity of 450 cps. The obtained dispersion was stored at 50°C for 3 months, but no abnormality was 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 Into 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 An acrylic resin solution and an epoxy resin solution were prepared in the same manner as in Example 1. Further, the phenol resin was prepared in the same manner as in Example 2. [Preparation of aqueous dispersion] 50 parts of the above acrylic resin solution 100 parts of the above epoxy resin solution 4.8 2-dimethylaminoethanol 4.8 30 parts of the above phenolic resin solution 355.2 ion-exchanged water In a four-necked flask, add the following with stirring. After the addition, the mixture was cooled. GPC measurements before and after the reaction confirmed that the acrylic resin and epoxy resin were partially bonded. After cooling, the solution was added and stirred to make a homogeneous solution, and then added gradually while stirring to obtain a milky white dispersion with a solid content of 20% and a viscosity of 405 cps. The obtained dispersion was stored at 50°C for 3 months, but no abnormality was observed. 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%)
Comparative Example 2 was carried out in the same manner as in Comparative Example 2, 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 prepare test panels. 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 and the table, Examples 1, 2, and 3 and Comparative Examples 2 and 3 containing phenolic resin or melamine resin exhibit superior performance to Comparative Example 1 in retort resistance, corrosion resistance, and saline storage tests. However, in Examples 1, 2, and 3, the amount of potassium permanganate consumed was extremely small compared to Comparative Examples 2 and 3, and the extraction characteristics were excellent, and the flavor retention was excellent. 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 a special fold-type Dupont impact tester is used, a sample folded in half is placed at the bottom, and a flat iron weight weighing 1 kg is dropped 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 with ○ 10 to 20 mm...marked with △ 20 mm or more...marked with 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 seam 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 in a cardboard box (15 cans in a box containing 30 cans). Vibrate with a vibrator for 5 hours, let the cans collide with each other, and store at 25℃ for 1 month. did. 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, 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 4 [Adjustment of epoxy resin] Adjustment was made in the same manner as in Example 1. [Preparation of aqueous resin dispersion] 150 parts of the above epoxy resin solution Butyl cellosolve 30 Methacrylic acid 30 Styrene 18 Ethyl acrylate 2 Benzoyl peroxide 3.5 Phenol resin solution of Example 3
30 2-dimethylaminoethanol
4.8 Pour 560 °C of ion-exchanged water into a four-necked flask and raise the temperature of the solution to 115°C while stirring. Next, the above mixture was added dropwise over 1 hour and reacted at 115°C for another 2 hours, and then added and reacted for 2 hours with stirring. After cooling, the mixture was added and further added gradually to obtain a stable aqueous dispersion. Ta. 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 5 [Preparation of phenolic resin solution] A flask was charged with 460 parts of a 11% sodium hydroxide aqueous solution, and while stirring, 128 parts of 92% paraformaldehyde was added little by little to dissolve, followed by 108 parts of p-cresol and heated at 50°C. The slurry was reacted for 2 hours at 70° C., then for 6 hours at 70° C., neutralized with hydrochloric acid, and washed with water. The slurry was extracted with n-butanol to obtain a 30% phenolic resin solution. As a result of GPC analysis, 2% was dimethylol of p-cresol.
90% were dimethylolated dimers, 5% were dimethylolated trimers, and 3% were dimethylolated tetramers or higher. [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 In a four-necked flask,... Prepare the liquid temperature to 80
℃ and allowed to react for 30 minutes. GPC before and after reaction
The measurements confirmed the reaction between epoxy resin and acrylic resin. Furthermore, after adding and reacting for 30 minutes at 80℃, the solid content was 20% and the viscosity was
A milky white dispersion of 850 cps was obtained. The obtained dispersion was stored at 50°C for 3 months, but no abnormality was observed. Example 6 [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 addition was complete, the mixture was stirred for an additional 2 hours and 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] Methyl cellosolve acetate 2100 parts Epicote 1009 900 parts The above acrylic resin solution 1000 parts 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 solution 100 parts of the phenolic resin solution of Example 5 19.5 parts of 25% ammonia water 1180.5 parts of ion-exchanged water Charge the following into a four-necked flask and stir. After heating at 100℃ for 3 hours, cooling
was added at 50°C. After stirring for 30 minutes, was slowly added to obtain a yellowish milky white dispersion with a solid content of 20% and a viscosity of 500 cps. The obtained dispersion was stored at 50°C for 3 months, but no abnormality was observed. Example 7 [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 part 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 reaction was terminated when the concentration decreased to mgKOH/g (in terms of solid content), and the mixture was taken out after cooling. 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 5 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. Added when the solid content reached 55% or more after sampling, continued reaction at 90°C for 2 hours, added while cooling, added at 60°C, and added little by little after 15 minutes. As a result, an aqueous dispersion with a solid content of 20% and a viscosity of 15 cps was obtained. Example 8 Acrylic resin solution of Example 1 50 parts Phenol resin solution of Example 5 60 parts Epoxy resin solution of Example 1 100 parts 2-dimethylaminoethanol 48 parts Ion-exchanged water 325.2 parts A four-necked flask was charged with: After reacting at 100°C for 2 hours with stirring, the mixture was cooled to 80°C, and reacted for 30 minutes. When further added gradually while stirring, the solid content was 20.
%, a milky white dispersion with a viscosity of 350 cps was obtained. This dispersion was stored at 80°C for 3 months, but no abnormalities were observed. Example 9 Epoxy resin solution of Example 1 100 parts Phenol resin solution of Example 5 60 parts Acrylic resin solution of Example 1 50 parts 2-dimethylaminoethanol 48 parts Ion exchange water 325.5 parts A four-necked flask was charged with the following: The mixture was reacted at 100° C. for 2 hours with stirring. GPC measurements before and after the reaction confirmed that the epoxy resin and phenolic resin were partially bonded. The temperature of the solution was lowered to 80°C, and was added to react for 30 minutes, followed by cooling. The bond between the acrylic resin and epoxy resin was confirmed by GPC measurements before and after the reaction. Furthermore, when it was gradually added while stirring, the solid content was 20%, and the viscosity was
A milky white dispersion of 400 cps was obtained. The obtained dispersion was stored at 50°C for 3 months, but no abnormality was observed. Regarding the aqueous dispersions obtained in Examples 4 to 9,
A coating test was conducted in the same manner as in Example 1. The results of this test are shown in Table and Table.

【table】

【table】

【table】

【table】

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, aromatic resin having an average of 1.1 to 2.0 epoxy groups in one molecule A carboxyl-rich composite resin composition containing a resin bond of an epoxy resin (B) and a phenol resin (C) is placed 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. In the aqueous resin dispersion formed by dispersing,
The acrylic resin (A) and the aromatic epoxy resin (B) are at least partially combined, and the phenolic resin (C) is precondensed with the acrylic resin (A) and/or the aromatic epoxy resin (B). The aqueous resin dispersion as described above. 2. The composite resin composition contains an acrylic resin-aromatic epoxy resin partial bond (D) and a phenol resin (C).
The aqueous resin dispersion according to claim 1, which is a composite resin composition with an excess of carboxyl groups, which is obtained by precondensing the above. 3. Acrylic resin-aromatic resin with excess carboxyl group, which is obtained by partially reacting acrylic resin (A) and aromatic epoxy resin (B) with acrylic resin-aromatic epoxy resin partial bond (D) The aqueous resin dispersion according to claim 2, which is a partially reacted epoxy resin. 4. A composite resin with an excess of carboxyl groups, in which the composite resin composition is obtained by partially reacting an aromatic epoxy resin (B) with a precondensate obtained by precondensing an acrylic resin (A) and a phenolic resin (C). The aqueous resin dispersion according to claim 1, which is a composition. 5 The composite resin composition is an aromatic epoxy resin (B)
Acrylic resin (A) is added to the precondensate having an epoxy group obtained by precondensing and phenol resin (C).
The aqueous resin dispersion according to claim 1, which is a composite resin composition with an excess of carboxyl groups, which is obtained by partially reacting the following. 6 Acrylic resin (A) and aromatic epoxy resin (B)
The aqueous resin dispersion according to any one of claims 2 to 5, having a solid content ratio of 2:1 to 1:6. 7. Claim 1, in which 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 6 to 6. 8. The aqueous resin dispersion according to claims 2 to 7, wherein the acrylic resin (A) has a weight average molecular weight of 3,000 to 80,000. 9 The number average molecular weight of aromatic epoxy resin is 900
The aqueous resin dispersion according to claims 1 to 8, which are the above.