JPH056566B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to an aqueous resin dispersion, and more particularly to an aqueous resin dispersion useful as a coating composition for metals, particularly as a coating for the inside of a can. (Conventional technology) Paints whose main component is aromatic epoxy resin are
It has excellent processability, content resistance, coating film properties, etc., and is used as a paint for cans, but the aromatic epoxy resin itself does not dissolve or disperse in aqueous media. On the other hand, water-based paints for cans are being considered from the viewpoint of resource saving, energy saving, or environmental pollution, and various proposals have also been made regarding paints containing aromatic epoxy resins as a main component. For example, a method is known in which aromatic epoxy resin is dispersed in water using a surfactant.
The action of surfactants tends to have an adverse effect on the storage stability and physical properties of the paint film. Various self-emulsifying aromatic epoxy resins have been proposed, which are aromatic epoxy resins modified with acrylic resins having carboxyl groups. For example, JP-A-53-14963 and JP-A-Sho.
Publication No. 55-9433 discloses that a partial reactant containing an excess of carboxyl groups obtained by reacting an acrylic resin and an aromatic epoxy resin can be stably dispersed in an aqueous medium in the presence of ammonia or an amine. There is. JP-A-57-105418 and JP-A-58-
Publication No. 198513 describes a monomer mixture containing a low-molecular compound having an epoxy group and an acryloyl group in one molecule, which is obtained by partially reacting an aromatic epoxy resin and (meth)acrylic acid, and acrylic acid or methacrylic acid. An aqueous dispersion composition obtained by polymerizing and neutralizing with a basic compound is disclosed. In addition, JP-A-53-1228 discloses a grafting method 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 aromatic epoxy resin. It has been shown that the prepared epoxy resins can be stably dispersed in aqueous media containing bases. Since the self-emulsifying aromatic epoxy resin obtained by the above technology does not contain surfactants in the paint, it can itself provide a strong coating film. Contains a highly water-soluble amino resin. By blending an amino resin, the curing speed of the paint can be improved to a certain extent without deteriorating the physical properties of the paint film, but when used in an amount that is practically satisfactory in terms of curing speed, the adhesion, Processability deteriorates, and especially as a paint for the inner surface of a can, low-molecular-weight compounds derived from the amino resin are eluted into the contents of the can during heat sterilization, resulting in hygienic problems. It is also known to incorporate a phenolic resin into a self-emulsifying aromatic epoxy resin, but it was thought that ordinary phenolic resins have a slow curing speed and cannot contribute to improving fast curing properties. (Problems to be Solved by the Invention) An object of the present invention is to improve the curing speed of a self-emulsifying aromatic epoxy resin coating. Furthermore, it is an object of the present invention to improve the adhesion and processability of the coating film. Furthermore, an object of the present invention is to overcome the hygienic problems associated with the combined use of water-soluble amino resins. [Structure of the Invention] (Means for Solving the Problems) That is, the present invention provides an acrylic resin (A) containing 12 to 70% by weight of monobasic carboxylic acid monomer units in one molecule as an essential component. and a carboxyl-excess acrylic resin-aromatic epoxy resin partial bond (D) having an aromatic epoxy resin (B) moiety, and a compound whose general formula is represented by the following formula (). A composite resin composition containing a phenolic resin initial condensate (C) containing 40% by weight or more has a pH of 4.
It is an aqueous resin dispersion prepared by dispersing it in an aqueous medium in the presence of ammonia or amine in an amount of ~11. (In the formula, R is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, X is a hydrogen atom or a methyl group, a and b are both 1 or 2, and a+
b=3 or a+b=4. ) The acrylic resin-aromatic epoxy resin partial bond (D) in the present invention has at least an acrylic resin (A) portion and an epoxy resin (B) in one molecule. In the first method for producing the acrylic resin-aromatic epoxy resin partially bonded product (D) in the present invention, 12 to 70% by weight of a monobasic carboxylic acid monomer is used.
An acrylic resin (A) formed by copolymerizing a copolymerizable monomer mixture containing Partial reaction occurs in the presence of an esterification catalyst or in the absence of a catalyst. The above acrylic resin (A) is prepared by mixing a monomer mixture consisting of monobasic carboxylic acid monomers such as acrylic acid and methacrylic acid with other copolymer monomers in an organic solvent such as azobisisobutyronitrile, benzoyl peroxide, etc. It can be obtained by copolymerization using a conventional 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, dodecyl methacrylate, styrene, vinyltoluene,
Styrenic monomers such as 2-methylstyrene, t-butylstyrene, and chlorostyrene, hydroxy group-containing monomers such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate, N-methylol (meth) Select from one or more of N-substituted (meth)acrylic monomers such as acrylamide and N-butoxymethyl (meth)acrylamide, epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, and acrylonitrile. I can do it. The amount of monobasic carboxylic acid monomer used is 12 to 70% by weight based on the total amount of monomers. If it is less than 12% by weight, the dispersion stability of the resin in an aqueous medium may be affected, and the adhesion of the painted film to the metal may be affected. This is not preferable because it deteriorates the properties, solvent resistance, flavor suitability, etc. Conversely, if it exceeds 70% by weight, the water resistance and boiling resistance of the coating film 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; Especially when it is larger than 80000, aromatic epoxy resin (B)
There is a tendency for gelation to occur when reacting with. The aromatic epoxy resin (B) in the present invention is preferably one obtained by condensing bisphenol A and epihalohydrin in the presence of an alkali catalyst,
Those having 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 and Epicote 1001 from Ciel Chemical Co., Ltd.
Epicote 1004, Epicote 1007, Epicote
1009 etc. 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 partial reaction product of acrylic resin (A) and aromatic epoxy resin (B) is obtained by combining the acrylic resin (A) and aromatic epoxy resin (B) in solid content ratio in a hydrophilic organic solvent. 2:1 to 1:6 in the presence of ammonia or amine at 60°C to 170°C.
It can be obtained by reacting for about 10 minutes to 2 hours. The reaction can be controlled by measuring the percentage of oxirane, measuring the viscosity, or measuring the molecular weight distribution by gel permeation chromatography (GPC). The final oxirane group content of the partial reactant is 5 to 5% as a reduction rate to the oxirane content of the aromatic epoxy resin.
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. The second method for producing the acrylic resin-aromatic epoxy resin partially bonded product (D) in the present invention involves combining an aromatic epoxy resin (B) and a monobasic carboxylic acid monomer such as (meth)acrylic acid. A monomer mixture containing a monobasic carboxylic acid monomer and the above-mentioned copolymerizable monomer is radically polymerized into a low molecular weight compound having a (meth)acryloyl group and an epoxy group in one molecule, which is obtained by partially reacting the two. The third method for producing the acrylic resin-aromatic epoxy resin partial bond (D) in the present invention includes 12 to 70% by weight of a monobasic carboxylic acid monomer in the presence of the aromatic epoxy resin (B). The copolymerizable monomer mixture is polymerized 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. In the composite resin composition of the present invention, a phenolic resin initial condensate (C) containing a compound represented by the following general formula () is mixed or preliminarily mixed into an acrylic resin-aromatic epoxy resin partial bond (D). It is a condensed product. (In the formula, R is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, X is a hydrogen atom or a methyl group, a and b are both 1 or 2, and a+
b=3 or a+b=4. ) The phenolic resin initial condensate (C) containing a compound whose general formula is represented by the formula () is a mixture of bisphenols such as bisphenol A or bisphenol F and formaldehyde into bisphenol A1
using 5 to 10 moles of formaldehyde and 1.5 to 4 moles of alkaline catalyst,
Relatively mild reaction conditions, i.e., reaction temperature of 30 to 70°C for 30 minutes to 4 hours, more preferably
It can be obtained by reacting at 45 to 55°C for 2 to 3 hours. In addition, the phenolic resin initial condensate (C) containing the compound represented by the general formula () includes hydrochloric acid, which is a trifunctional mononuclear phenol, m-ethylphenol,
It can be obtained using 3,5-xylenol and m-methoxyphenol as raw material phenols. Furthermore, the above trifunctional mononuclear phenol and p
-cresol, o-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-
Bifunctional phenols such as xylenol and m-methoxyphenol can also be used in combination. The preparation of the phenolic resin condensate (C) using these mononuclear phenols may be performed under the same reaction conditions as those using bisphenols. The alkaline catalyst used in the synthesis of the phenolic resin initial condensate (C) is preferably a strong base such as sodium hydroxide or potassium hydroxide, but sodium carbonate and the like can also be used alone or in combination. Formaldehyde can also be used as formalin and paraformaldehyde. The important point in this synthesis is to suppress the condensation reaction and allow only the addition reaction of formaldehyde to the phenols to occur.For this purpose, the reaction temperature is kept as low as possible, an alkali catalyst is used in excess of the number of moles of the phenols, and formaldehyde is also added to the phenols. Use more than the equivalent number of the class. For example, when 1 mol of bisphenol A is used as the phenol, it is suitable to use 2 mol of the alkali catalyst and 8 mol of formaldehyde. The end point of the reaction is determined by GPC measurement,
For reactions such as carbolic acid, where the hue changes from pale yellow to dark red depending on the degree of condensation,
It can also be determined by managing hue. Furthermore, if the reaction conditions can be controlled sufficiently, it can also be determined by the reaction time. To separate the phenolic resin initial condensate (C) containing the compound of general formula () from the reaction product, the reaction mixture is made acidic with hydrochloric acid, sulfuric acid, etc., and the precipitate is filtered and washed with water. be able to. In the case of reaction products with high solubility in organic solvents, such as bisphenols, the organic solvent and acid can be added at the same time and extracted into the solvent. The extracted reaction product is treated with acid, alkali, or
It can be purified by washing with water etc. General formula () in phenolic resin initial condensate (C)
The amount of the compound represented by can be confirmed by GPC measurement. Furthermore, the methylol concentration can be confirmed from nuclear magnetic resonance spectroscopy. General formula () in phenolic resin initial condensate (C)
The content of the compound represented by is 40% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more. As the amount of the compound represented by the general formula () increases, the faster curing properties, hot water resistance, processability, and adhesion improve. Further, the phenolic resin initial condensate (C) is used in an amount of 2 to 40% by weight based on the total amount of the resin including the acrylic resin (A) and the aromatic epoxy resin (B). 2
If it is less than 40% by weight, its contribution to the curing speed of the coating film will not be sufficient, and if it exceeds 40% by weight, the physical properties such as processability of the coating film will tend to deteriorate. The aqueous dispersion of the present invention 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. Examples of the above amines include alkylamines such as trimethylamine, triethylamine, and butylamine; alcohol amines such as 2-dimethylaminoethanol, diethanolamine, triethanolamine, and aminomethylpropanol;
Morpholine and the like 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 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
You can choose from a range of 150℃ to 230℃ and a time range of 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 with reference to Examples. In addition,
In the examples, "parts" and "%" indicate "parts by weight" and "% by weight," respectively. (Example) Example 1 [Preparation of acrylic resin solution] Styrene 300.0 parts Ethyl acrylate 210.0 Methacrylic acid 90.0 Buty cellosolve 288.0 Benzoyl peroxide 12.0 1/4 of the mixture of the above composition was placed in a four-neck flask purged with nitrogen gas. Heat the preparation to 80-90℃, and while keeping it at that temperature, gradually drop the remaining 3/4 over 2 hours. After the addition is complete, stir at that temperature for another 2 hours, cool, and give an acid value of 93 (solid). A carboxyl group-containing resin solution was obtained 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). [Preparation of epoxy resin solution] Epicote 1007 500 parts Butyl Cellosolve 333.3 After purging with nitrogen gas, charge the entire amount into a four-necked flask, gradually heat to raise the internal temperature to 100℃, stir for 1 hour, and after completely dissolving, heat to 80℃. Cool and solids
A 60% epoxy resin solution was obtained. [Preparation of phenolic resin (C1) solution] Bisphenol A 228g (1 mol), 37% formalin 649g (8 mol), 35% sodium hydroxide 302
After reacting at 50°C for 2 hours, 250 g of ethyl acetate and 250 g of n-butyl alcohol were added, followed by 401 g (2.2 mol) of 20% hydrochloric acid.
After stirring at 60℃ for 10 minutes, when left to stand still, 2
Divided into layers. The upper layer is an organic compound layer and the yield is
It was 430g. The organic layer was washed and neutralized using water and aqueous ammonia to obtain 330 g of a pale purple transparent phenolic resin (C1). The solid content was 30%. When this solution was analyzed by high performance liquid chromatography and nuclear magnetic resonance absorption spectroscopy, it was confirmed that it contained 75% of a tetramethylol compound of bisphenol A represented by the following chemical formula. 25 left
% was a mixture of polymethylolated bisphenol A dimers and trimers condensed at the methylol group. [Preparation of aqueous resin dispersion] 50 parts of the above acrylic resin solution, 100 parts of the above epoxy resin solution, 4.8 parts of 2-dimethylaminoethanol, 60 parts of the above phenol resin (C1) solution, 325.2 parts of ion-exchanged water, and reacted at 80°C for 70 minutes with stirring. was added while cooling, and the temperature of the reaction solution reached 60°C. After stirring at 60℃ for 10 minutes,
The mixture was added dropwise over time to obtain a milky white resin dispersion with a solid content of 20% and a viscosity of 50 cps. Example 2 Epoxy resin solution used in Example 1,
Acrylic resin solution and phenolic resin (C1)
An aqueous resin dispersion was prepared using the solution. However, the amount of the phenolic resin solution used was 30 parts, the amount of ion exchange water used was 315 parts, and the other components were the same as in Example 1. Solid content 20%, viscosity 75cps
A milky white resin dispersion was obtained. Example 3 Epoxy resin solution used in Example 1,
Acrylic resin solution and phenolic resin (C1)
An aqueous resin dispersion was prepared using the solution. However, the amount of the phenol resin solution used was 10 parts, the amount of ion exchange water used was 300.2 parts, and the other components were the same as in Example 1. Solid content 20%, viscosity
A milky white resin dispersion of 80 cps was obtained. Example 4 [Preparation of phenolic resin (C2) solution] Bisphenol A 228g (1 mol), 37% formalin 649g (8 mol), 35% sodium hydroxide 229g
When synthesized and purified in the same manner as the preparation of the phenolic resin in Example 1 using g (2 mol),
345 g of a solution with a solids content of 30% was obtained. The content of tetramethylolated bisphenol A in this phenolic resin (C2) solution was 63%. The remaining 37% was a mixture of polymethylolated bisphenol A dimers or more. [Preparation of aqueous resin dispersion] Aqueous resin was prepared in the same manner as in Example 1, except that the above phenol (C2) solution was used in place of the epoxy resin solution, acrylic resin solution, and phenol resin (C1) solution used in Example 1. A dispersion was obtained. Example 5 Epoxy resin solution used in Example 4,
Acrylic resin solution and phenolic resin (C2)
An aqueous resin dispersion was prepared using the solution. However, the amount of phenol resin (C2) used was 30 parts, the amount of ion exchange water used was 325.2 parts, and the other components were the same as in Example 4. Solid content 20%, viscosity
A milky white resin dispersion of 89 cps was obtained. Example 6 Epoxy resin solution used in Example 4,
Acrylic resin solution and phenolic resin (C2)
An aqueous resin dispersion was prepared using the solution. However, the amount of phenol resin (C2) used was 10 parts, the amount of ion exchange water used was 300.2 parts, and the other components were the same as in Example 4. Solid content 20%, viscosity
A milky white resin dispersion of 100 cps was obtained. Example 7 [Preparation of phenolic resin (C3) solution] 94 g (1 mol) of carbolic acid, 405 g of 37% formalin
(5 mol) and 211 g (1.32 mol) of 25% sodium hydroxide were mixed and reacted at 50°C for 2 hours and then at 70°C for 2 hours to obtain a red transparent solution. Add 100 g of ethyl acetate and 100 g of n-butyl alcohol to this solution, followed by 200 g of 20% hydrochloric acid.
(1.1 mol) was added, stirred at 60°C for 10 minutes, and then allowed to stand. Within a few minutes, the mixture separated into two layers: the upper layer was a golden-yellow organic layer, and the lower layer was a light brown aqueous layer. Water the organic layer to 150%
When washed twice with g, the lower layer became an organic layer. At this time, the pH of the water layer was 4.2. The yield of the organic layer was 303 g, solid content 26.3%. A portion of the solvent was removed to give a solid content of 30%. This organic layer consists of a mixture of dinuclear polymethylolates of carbolic acid.
%, and the polynuclear polymethylol compound was 45% phenolic resin (C3). [Preparation of aqueous resin dispersion] Aqueous resin dispersion was prepared in the same manner as in Example 1, except that the above phenolic resin (C3) solution was used in place of the epoxy resin solution, acrylic resin solution, and phenolic resin (C1) solution used in Example 1. A resin dispersion was obtained. Example 8 Epoxy resin solution used in Example 7,
Acrylic resin solution and phenolic resin (C3)
An aqueous resin dispersion was prepared using the solution. However, the amount of phenolic resin (C3) solution used is 30 parts,
The amount of ion-exchanged water used was 315.2 parts, and the other components were the same as in Example 7. A milky white resin dispersion with a solid content of 20% and a viscosity of 66 cps was obtained. Example 9 Epoxy resin solution used in Example 7,
Acrylic resin solution and phenolic resin (C3)
An aqueous resin dispersion was prepared using the solution. However, the amount of phenolic resin (C3) solution used is 10 parts,
The amount of ion-exchanged water used was 300.2 parts, and the other components were the same as in Example 7. A milky white resin dispersion with a solid content of 20% and a viscosity of 70 cps was obtained. Example 10 [Preparation of epoxy acrylate resin solution] Epicote 1009 646 parts Butyl cellosolve 349 10% sodium hydroxide 1 hydroquinone 0.02 methacrylic acid 4 parts were charged, stirred at 110°C for 2 hours, and dissolved.
After confirmation, it was cooled. was added at 100°C and while heating. The reaction was carried out at 130° C. for 5 hours, and the end point was reached when the acid value decreased to 0.3 mg KOH/g, and the reaction mixture was taken out after cooling. The number average molecular weight of the product is 3800, and the epoxy equivalent is
2750, the average number of epoxy groups per molecule is 1.38,
The viscosity at 50°C with a solid content of 65% was 80,000 cps. [Preparation of aqueous resin dispersion] Methyl ethyl getone 40 parts Above epoxy acrylate resin solution 171 Styrene 16.7 Ethyl acrylate 19.5 Methacrylic acid 19.5 Butyl cellosolve 33.4 Azobisisobutyronitrile 2.4 Azobisisobutyronitrile 0.6 Phenol resin (C1) solution 111 Methyl ethyl ketone 10 2-dimethylaminoethanol 10% aqueous solution
7.0 Ion-exchanged water 505.8 was charged into a flask, heated and refluxed, and the mixed solution of 505.8 was added little by little over a period of 3 hours. After the addition was completed, the temperature was raised to 90°C, and the reaction was continued by adding . When the sampled solution reached 55%, it was added, and the reaction was continued at 90°C for 2 hours, then added while cooling, and when the temperature reached 60°C, was added, and then was gradually added. . An aqueous dispersion with a solid content of 20% and a viscosity of 15 cps was obtained. Comparative Example 1 An aqueous resin dispersion was obtained in the same manner as in Example 1 except that only the acrylic resin solution and epoxy resin solution prepared in Example 1 were used as resin components. however,
295.2 parts of ion-exchanged water was used. Solid content 20%,
A milky white resin dispersion with a viscosity of 125 cps was obtained. Comparative Example 2 [Preparation of phenolic resin (C4) solution] Bisphenol A 228g (1 mol), 37% formalin 324g (4 mol), 35% sodium hydroxide 114
After reacting at 70°C for 4 hours, 200 g of ethyl acetate and 200 g of n-butyl alcohol were added, followed by 151 g (0.83 mol) of 20% hydrochloric acid.
After stirring at 60°C for 10 minutes, the mixture was allowed to stand and was separated into two layers within a few minutes. The solid content is 30% by the same operation as in Example 1.
300 g of a light brown, transparent solution was obtained. This phenolic resin (C4) solution contained 4.8% of tetramethylolated bisphenol A, and the rest was a condensed polynuclear mixture. [Preparation of aqueous resin dispersion] Example 1 except that the above phenolic resin (C4) solution was used in place of the phenolic resin (C1) solution.
In the same manner as above, a milky white dispersion with a solid content of 20% and a viscosity of 45 cps was obtained. Comparative Example 3 [Preparation of phenolic resin (C5) solution] 94 g (1 mol) of carbolic acid, 324.3 g of 37% formalin
(4 mol) and 211 g (1.32 mol) of 25% sodium hydroxide were mixed, and after reacting at 50°C for 2 hours,
After reacting at 70°C for 4 hours, a dark red transparent solution was obtained. Add 100g of ethyl acetate and n-
Add 100g of butyl alcohol, followed by 20% hydrochloric acid.
200 g (1.1 mol) was added. Thereafter, the same operation as in Example 1 was performed to finally obtain a brown transparent organic layer. The yield of the organic layer was 311 g, solid content 35.6%. n
- Butyl alcohol was added to make the solids content 30%.
The organic layer is 9.6% mononuclear and 26.7% dinuclear of carbolic acid.
A phenolic resin (C5) solution, which is a mixture of polymethylol compounds containing 63.7% polynuclear bodies, was obtained. [Preparation of aqueous resin dispersion] Example 1 except that the above phenolic resin (C5) solution was used in place of the phenolic resin (C1) solution.
In the same manner as above, a milky white dispersion with a solid content of 20% and a viscosity of 45 cps was obtained. Comparative Example 4 Same as Example 1 except that 22.5 parts of Cymel 325 (water-soluble amino resin manufactured by Mitsui Toatsu Co., Ltd., solid content 80%) was used instead of the phenolic resin (C1). A resin dispersion was obtained. The resulting resin dispersion had a solid content of 20% and a viscosity of 105 cps. Painting test The aqueous resin dispersions obtained in Examples 1 to 10 and Comparative Examples 1 to 4 were replaced with hexyl cellosolve.
4.6% water, 72.4% water, and 23% solids resin dispersion. Then add 25% ammonia water little by little.
All resin dispersions were prepared to have a solids content of 21 to 22.5% and a viscosity of 800 to 1200 cps. All of the prepared resin dispersions showed no change in viscosity or sedimentation after being stored at 50°C for 3 months, and were confirmed to be extremely stable. Next, the prepared resin dispersion was applied on a tin plate to a thickness of 8 to 10μ, and heated at 165°C and 200°C.
Each test panel was baked and dried for 5 minutes. The aqueous dispersion was sprayed onto the inner surface of a two-piece tin can with a content capacity of 250 ml, and baked and dried at 165° C. and 200° C. for 5 minutes each to prepare an inner-coated can, and its various resistances were tested. The test method is 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 was judged visually and by peeling off with cellophane adhesive tape. (3) Workability: This occurs when using a special folding type DuPont impact tester, placing a sample folded in half at the bottom, and dropping a 1 kg iron weight 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. (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°C.
The treatment was carried out for 30 minutes, and the degree of corrosion near the x mark was determined. (5) Potassium permanganate consumption: Fill the inner-coated can with 250 ml of ion-exchanged water and seal it.
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 each 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, the cans were sealed, sterilized at 100°C for 30 minutes, and then stored at 50°C for 6 months. The resulting liquid was then subjected to a flavor test. Test Results (1) Adhesion: All samples of Examples and Comparative Examples baked at 165°C and 200°C were 100/100. (2) Retort resistance: The judgment results are shown in Table 1. No abnormalities (○): Slight whitening or peeling of the paint film (△): Significant whitening or peeling of the paint film (×) Indicated. (3) Workability: All samples of Examples and Comparative Examples baked at 165°C and 200°C had crack lengths of 10 mm or less and passed the test. (4) Corrosion resistance: The evaluation results are shown in Table 1 as follows: No abnormality (○): Slight corrosion (△): Significant corrosion (x). (5) Potassium permanganate consumption: Shown in Table 1 as a numerical value (ppm). (6) Salt solution storage test: Table 1 shows the values (ppm). (7) Flavor preservability: Some changes were observed in the inner-coated can of Comparative Example 4, but no changes were observed in the inner-coated cans of other Examples and Comparative Examples. [Effects of the Invention] The aqueous resin dispersion resistance obtained in the present invention cures in a short time as a paint for metals, and the resulting coating film has excellent corrosion resistance. Also, as a paint for cans, it has excellent coating film adhesion, processability, and retort resistance. In addition, since the coating film does not contain unreacted low molecular weight substances, when used as a paint for the inner surface of cans,
Unreacted low molecular weight substances do not migrate into food contents, and flavor retention is excellent.

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Claims (1)

[Claims] 1. An acrylic resin (A) portion containing 12 to 70% by weight of monobasic carboxylic acid monomer units as an essential component and an aromatic epoxy resin (B) portion in one molecule. Acrylic resin with excess carboxyl groups-
40% by weight of aromatic epoxy resin partially bound product (D) and a compound whose general formula is represented by the following formula ()
An aqueous resin dispersion obtained by dispersing a composite resin composition containing the above-containing phenolic resin initial condensate (C) in an aqueous medium in the presence of ammonia or amine in an amount such that the pH becomes 4 to 11. (In the formula, R is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, X is a hydrogen atom or a methyl group, a and b are both 1 or 2, and a+
b=3 or a+b=4. 2. The aqueous resin dispersion according to claim 1, which contains a phenolic resin initial condensate (C) containing 60% by weight or more of a compound represented by formula (). 3. The aqueous resin dispersion according to claim 1, which contains a phenolic resin initial condensate (C) containing 70% by weight or more of a compound represented by formula (). 4. The aqueous resin dispersion according to claim 1, wherein the weight of the phenolic resin initial condensate (C) is 2 to 40% by weight based on the total weight of the resin. 5 Acrylic resin-aromatic resin with excess carboxyl groups, which is obtained by partially reacting acrylic resin (A) with aromatic epoxy resin (B), in which the acrylic resin-aromatic epoxy resin partial bond (D) The aqueous resin dispersion according to claim 1, which is a partially reacted epoxy resin. 6. The aqueous resin dispersion according to claim 5, wherein the acrylic resin (A) has a weight average molecular weight of 3,000 to 80,000. 7 The number average molecular weight of aromatic epoxy resin is 900
6,000 to 6,000. 8 Acrylic resin (A) and aromatic epoxy resin (B)
The aqueous resin dispersion according to claim 5, having a solid content ratio of 2:1 to 1:6. 9 The acrylic resin-aromatic epoxy resin partial bond (D) is combined with the aromatic epoxy resin (B) (meth)
Partially bonded product obtained by radical polymerizing a monomer mixture containing a monobasic carboxylic acid monomer to a low molecular weight compound having a (meth)acryloyl group and an epoxy group in one molecule obtained by partially reacting with acrylic acid ( D) The aqueous resin dispersion according to claim 1, which is D).