JPS6249291B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-dispersible resin composition that has excellent hot water resistance and flexibility, and is capable of providing a coating film with few water-oil components that inhibit flavor properties, which are particularly required for food applications. In recent years, aqueous polymer dispersions obtained by emulsion polymerization, such as acrylic, acrylic-styrene, vinyl acetate, and ethylene-vinyl acetate, have come to be widely used in industrial applications such as paints and adhesives. I came. However, coating films formed from these conventional aqueous polymer dispersions have insufficient adhesion to metals, wood, cured cement, plastics, etc., and in particular, their adhesion after immersion in hot water is significantly reduced. It has serious defects such as being unable to be used in food applications because it contains a large amount of water-extractable components, which are factors that cause irritation and inhibit flavor properties. In order to improve these defects, efforts have been made to reduce the amount of water-sensitive substances such as surfactants and protective colloids contained in the aqueous polymer dispersion, and to create crosslinked structures by introducing functional groups into the polymer skeleton. Attempts have been made to form a system, but sufficient results have not been achieved.
In addition, attempts have been made to improve the water resistance of the coating film by using thermosetting resins, such as epoxy resins, etc.
(1) The polymer component and epoxy resin separate during storage,
It cannot exist stably as an aqueous dispersion. (2) The resulting coating film becomes cloudy. (3) It had drawbacks such as insufficient hot water resistance of the coating film. In light of the above circumstances, research is being conducted on composite water dispersions that have a water-dispersible function by introducing carboxyl groups into acrylic polymer chains, and at the same time provide the hot water resistance of the coating film possessed by epoxy resins. At this time, by interposing a chemical bond between the acrylic polymer and the epoxy resin, the compatibility of both resins is improved, thereby improving the storage stability of the aqueous dispersion and eliminating the cloudiness of the resulting paint film. Is possible. JP-A No. 53-1228 discloses a grafting reaction to an acrylic main chain by abstracting hydrogen from an aliphatic skeleton carbon atom of an epoxy resin, but the relationship between a grafted epoxy resin and a free epoxy resin is It is very difficult to control the ratio (hereinafter referred to as the grafting rate), and the grafting rate is also low, resulting in a disadvantage that the aqueous dispersion lacks stability. Furthermore, compositions obtained by adding an epoxy resin to a pre-polymerized acrylic polymer containing carboxyl groups and reacting them have been disclosed; , Japanese Patent Application Laid-Open No. 55-75460), acrylic polymer is a polyfunctional polymer containing a large amount of carboxyl groups, while epoxy resin is a bifunctional compound.
It is very difficult to proceed with the reaction without causing gelation. According to this method, the grafting rate of the ester-type/grafted epoxy resin to the acrylic polymer and the free epoxy resin cannot be increased very high, and the aqueous dispersion has the disadvantage of poor storage stability. There is. Moreover, since a large amount of acrylic polymer remains without epoxy resin grafting, the heat resistance after coating film formation is poor, the coating film becomes cloudy, and at the same time, a large amount of water is extracted, especially as a coating forming agent that comes into contact with food. However, a fully satisfactory result cannot be obtained. A typical application that comes in contact with food is the coating applied to the inner surface of beverage cans, which does not change the flavor of the contents. The required performance must be met, such as no deterioration of the coating during the sterilization process at 120℃ or higher, the ability to withstand deformation during the can forming process, and no elution from the coating into the contents. No. Under these circumstances, the present inventor has developed a composite resin consisting of a combination of an acrylic polymer and an epoxy resin, which has storage stability, which is an essential requirement for an aqueous dispersion, when interposing a chemical bond between the acrylic polymer and the epoxy resin. The amount of chemical bonding between the two is adjusted to the optimum range to meet the hot water resistance, flexibility, and amount of water extracted, which are required for the inner surface coating of cans such as beverage cans, which are required after coating is formed. death,
At the same time, by suppressing the amount of free acrylic polymer below a certain level, we have surprisingly achieved both the storage stability, which is an essential requirement for an aqueous dispersion, and the storage stability required after coating film formation, especially for beverage cans. This invention satisfies all the properties required for the inner coating of canned goods, such as hot water resistance, flexibility, and almost no water extraction. That is, the present invention provides (a) a copolymer (A) component whose structural formula is composed of the following structural units (X), (Y) and (Z);

【formula】 【formula】

[Formula] [However, R ₁ is -H or -CH ₃ , R ₂ is

[expression] or

[Formula] (Here, R ₅ is −CnH _2o+1 (n=1, 2)), R ₃ is (Here, m = integer from 0 to 100, R ₆ is

[Formula] shall be represented. )] (b) The structural formula is

[Formula] [However, R ₇ is The epoxy resin (B) component and (f) structural formula represented by the following structural units (X) and (Z)
Copolymer (C) component consisting of

【formula】

[Formula] In a mixture consisting of the following, the weight ratio is (C) component / (A) component + (B) component + (C) component A) component contains x moles of the structural unit (X), y moles of the structural unit (Y), and z moles of the structural unit (Z), and the relational expression between x, y, and z is 20<x/x+y+z× 100<70 (2) 30<z/x+y+z×100<80 (3) 1≦y<5 (4) and 50% of the carboxyl groups in component (A) and component (B) % or less of the water-dispersible resin composition is a salt neutralized with an amine. In the present invention, the copolymer (A) component has a chemical structural formula of

Constituent unit (X) represented by [formula], chemical The structural formula is

Constituent unit represented by [formula] (Y) and the chemical structure is

It consists of a structural unit (Z) represented by the formula and can be obtained by copolymerizing monomers forming each structural unit. The array of its constituent units is
The shape is not limited to regular, irregular, block, or graft. The chemical structure is

In the structural unit (X) represented by [Formula], R ¹ is -H or -CH ₃ ,
R ₂ is

[expression] or

[Formula] (where R ₅ refers to -CnH _2o+1 (n=1, 2)). Examples of specific monomers include alkyl esters of acrylic acid, alkyl esters of methacrylic acid, specifically methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, bull methacrylate, isobutyl methacrylate, hexyl methacrylate, 2-
Hydrokyl alkyl esters of acrylic acid or methacrylic acid such as ethylhexyl methacrylate and octyl methacrylate, specifically 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and monomers having vinyl unsaturated groups, specifically styrene, vinyl Examples include styrenic monomers such as toluene and divinylbenzene. The monomer forming the structural unit (X) is selected from at least one of the above,
Preferably, two or more and up to three types of monomers are used in combination. For example, a combination of styrene and ethyl acrylate is preferred. The chemical structure is

In the structural unit (Y) represented by [Formula], R ₃ is (Here, m represents an integer from 0 to 100.) The monomer forming the structural unit (Y) is acrylic acid or methacrylic acid, and its general formula will be described later.

It is an esterification reaction product with a bisphenol type epoxy resin represented by the formula. At this time, it is necessary that only one epoxy group in one molecule of the epoxy resin having two epoxy groups reacts, and the remaining epoxy group remains unreacted. R ₃ in the structural unit represented by component (A) is

[Formula] It is a reactive residue. Here the general formula is

The bisphenol type epoxy resin represented by the formula is obtained by the condensation of bisphenol A and epihalohydrin, and depending on the repeating unit m,
The difference in molecular weight is expressed. Typical examples of bisphenol A type epoxy resins include AER-330, 331, 337, 661, 664, 667 manufactured by Asahi Kasei Co., Ltd.
669, Epicoat 828 manufactured by Yuka Ciel Epoxy Co., Ltd.
1001, 1004, 1007, 1009, 1010 and molecular weight 1
More than 10,000 phenoxy resins can be mentioned. It can be used within the range where the repeating unit m is an integer from 0 to 100; if it exceeds 100, the viscosity becomes high and is not practical. The preferred range of m is 0 to 40. The most preferred example of epoxy resin is an epoxy resin with an epoxy equivalent of 2000 in terms of processability and water extractability of the coating film.
~5000 bisphenol A type epoxy resins can be mentioned. As mentioned above, the monomer constituting component (Y) is synthesized by an addition reaction between acrylic acid or methacrylic acid and a bisphenol-type epoxy resin.
Synthesize a copolymer consisting of component and (Z) component,
After that, a bisphenol type epoxy resin may be added. The chemical structure is

The monomer forming the structural unit (Z) represented by the formula is acrylic acid or methacrylic acid, preferably methacrylic acid. The copolymer (A) component contains x moles of the structural unit (X),
Contains y moles of the structural unit (Y) and z moles of the structural unit (Z). For x, y, and z, a range that satisfies the following equations is used: 20<x/x+y+z×100<70 30<z/x+y+z×100<80 1≦y<5. The structural unit (X) forms the main chain of the acrylic polymer, and if it is less than 20 mol%, polymerization is difficult, and if it is more than 70 mol%, the hot water resistance of the resulting coating film will inevitably deteriorate. The structural unit (Y) is the most important because it controls the compatibility of the acrylic polymer and the epoxy resin, which is the key point of the present invention, and it is essential that it is contained in 1 mole or more in one molecule of the polymer of the component (A). This is the condition. If the structural unit (Y) is less than 1 mole in component (A), compatibility between the acrylic polymer and the epoxy resin cannot be achieved, the storage stability of the aqueous dispersion will be deteriorated, and the drying time during baking will be shortened. significantly longer. Moreover, if it is 5 moles or more, polymerization is difficult. The structural unit (Z) has two functions: first, it forms an amine salt to water-disperse the composition, and second, it reacts with the epoxy group during coating film formation to crosslink it. If the amount is less than 30 mol %, not only a sufficient water dispersion function cannot be exhibited, but also a sufficient crosslinking reaction cannot be carried out, resulting in poor hot water resistance of the coating film. Moreover, if it is more than 80 mol%, the hot water resistance will be lowered due to carboxyl groups remaining in the coating film. Furthermore, the preferable ratio of the number of structural units is in the range shown by the following formula: 35<x/x+y+z×100<55 45<z/x+y+z×100<65 1≦y<3. The weight average molecular weight of the copolymer of component (A) is 5000~
A range of 50000 is preferred. If it is less than 5000, the resulting coating film will not have sufficient flexibility. Moreover, if it is more than 50,000, the water dispersion particles cannot be properly fused during baking and drying, causing pinholes in the coating film. More preferred is a range of 10,000 to 30,000. The copolymer of component (A) can be produced by a method known per se, such as bulk polymerization, emulsion polymerization, or solution polymerization. Preferably, alcohols such as methanol, ethanol, and butanol; glycol derivatives such as ethylene glycol monomethyl ether and ethylene glycol monobutyl ether; ketones such as methyl ethyl ketone and methyl isobutyl ketone; and esters such as methyl acetate and ethyl acetate. or 40-160℃ in a mixed solvent,
It is preferably obtained by carrying out a polymerization reaction at a temperature of 40 to 90°C in the presence of an azo compound, peroxide, or other polymerization initiator. In the present invention, the structural formula of component (B) is

The epoxy resin represented by the formula is as described in the explanation of the structural unit (Y) of the component (A). A preferred example of the epoxy resin as component (B) is a bisphenol A type epoxy resin, and most preferably has an epoxy equivalent of 2,000 to 5,000 in terms of processability of the coating film and low water extraction. In the present invention, the epoxy resin of component (B),
The raw epoxy resins forming the structural unit (Y) of component (A) do not necessarily have to be the same. Preferably, the same resin is used. In the present invention, the copolymer (C) component has a chemical structural formula of

Constituent unit (X) represented by [formula], chemical The structural formula is

It consists of a structural unit (Z) represented by the formula and can be obtained by copolymerizing monomers forming each structural unit. As with component (A), the arrangement of the constituent units is not particularly limited. The types of monomers that can form the structural units (X) and (Y) are exactly the same as (X) and (Z) that constitute component (A). In the copolymer (C) component, the ratio of the structural units (X) and (Z) is not particularly limited,
Preferably, (X) is in a range of 20 to 70 mol%, and (Z) is in a range of 30 to 80 mol%. The copolymer (C) component can be produced by the same method as the copolymer (A) component. It is also possible to produce component (C) at the same time as producing the copolymer of component (A). In the present invention, component (A), which is a constituent element thereof,
Component (B) and component (C) each have the following functions. That is, component (A) includes an epoxy resin that does not have a water dispersion function, and has a function of imparting water dispersibility. At this time, the structural unit (Y) in component (A) has an affinity with the epoxy resin and plays the role of stably incorporating the epoxy resin into the water dispersion particles. Component (B) takes advantage of its excellent mechanical and thermal properties to provide a coating film with hot water resistance, flexibility, and low water extractability, which is the objective of the present invention. Component (C), like component (A), has the function of imparting water dispersibility, but conversely, when the amount exceeds a certain level, it impairs hot water resistance and increases the amount of water extracted, causing food Since it has a serious drawback of impairing flavor properties in applications, it is preferable that the amount be within a certain range as much as possible. Therefore, as an essential requirement of the present invention, the amount of component (C) by weight must satisfy the relationship of (C) component/(A) component + (B) component + (C) component x 100<5. shall be. If it is 5 or more, hot water resistance will be impaired and the amount of water extracted will also increase. It also has the disadvantage that it takes a long time to bake during coating formation. Preferably it is 3 or less. The amounts of component (A) and component (B) can be arbitrarily selected depending on the purpose, but coating films with excellent hot water resistance,
In order to satisfy the performance required for coating films for cans, the weight must be 35 < (A) component / (A) component + (B) component + (C) component x 100 < 80 20 < (B) component The range of /(A) component+(B) component+(C) component×100<65 is preferable. If component (A) is less than 35% by weight, water dispersibility will be lacking, and if it is more than 80% by weight, hot water resistance will be impaired. If component (B) is less than 20% by weight, hot water resistance will be impaired, and if it is more than 65% by weight, water dispersibility will be poor. In the present invention, the method of mixing component (A), component (B), and component (C) is not particularly limited.
Two of the three components may be mixed first and one component may be added later, or the three components may be mixed at the same time. In addition, as a method to obtain a mixture of component (A), component (B), and component (C) at once, a mixture of the monomers forming the structural unit (Y) in component (A) and component (B) is prepared in advance. Then, add monomers forming the structural units of (X) and (Z) in component (A),
It is also possible to proceed with the copolymerization reaction in the presence of component (B). At this time, component (C) can also be formed at the same time. In a mixture consisting of component (A), component (B), and component (C), an example of a method for separating each component and analyzing the amount of each component is a fractionation method using a combination of solvents. To give a specific example, when a mixed solvent of ethanol and tetrahydrofuran is used in a weight ratio of 6:1, component (B) has low solubility and component (A) dissolves at a constant rate. vice versa
Component (C) is completely dissolved. Furthermore, if a mixed solvent of chloroform and tetrahydrofuran is used in a weight ratio of 6:1, components (A) and (B) will be completely dissolved.
Component (C) does not dissolve. In the present invention, particularly excellent hot water resistance,
When trying to obtain a coating film with low flexibility and water extractable components, the structural unit (Y) of the copolymer (A) component
and the total weight of the epoxy resin (B) component is 70% relative to the total weight of the (A) component, (B) component and (C) component.
Preferably it is ~90% by weight. If it is less than 70% by weight, the heat resistance will be low, resulting in a decrease in hot water resistance, and if it is more than 85% by weight, the viscosity of the mixture will be high and the stability during water dispersion will be likely to deteriorate. In the present invention, water dispersion is made possible by carboxyl anions obtained by neutralizing the carboxyl groups in components (A) and (B). The compound used for neutralization is an amine, such as ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethanolamine,
Diethanolamine, dimethylmethanolamine, dimethylethanolamine, etc. can be mentioned. When neutralizing in the present invention, it is essential that the amount of the above amine be 0.5 equivalent or less with respect to the total amount of carboxyl groups in components (A) and (B). When using 0.5 equivalent or more, component (A) and (B)
Anionic polymerization of the epoxy groups in the components tends to proceed, resulting in extremely poor storage stability of the aqueous dispersion. The preferred amount of amine used is 0.3 equivalents or less. As for the method of neutralization with amine, (A) component, (B)
A predetermined amount of the amine may be added alone or after diluting the amine with water to the mixture of the component and the component (C). When using the composition of the present invention, it is first diluted with water to obtain a desired viscosity to obtain an aqueous dispersion. At this time, an organic solvent may be added if necessary in order to improve the coating properties or prevent the occurrence of "repelling" or "unevenness". In the present invention, the copolymer component
When containing (A) and (C), it is preferable to use a water-soluble organic solvent, and if there is an organic solvent used during synthesis, there is no need to add it again here. Examples of organic solvents used in the synthesis and aqueous dispersion of copolymer components (A) and (C) include methanol,
ethanol, propyl alcohol, butanol,
Alcohols such as hexanol, octanol, and decanol; glycol derivatives such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; and ethers such as dioxane. Ketones such as , acetone, methyl ethyl ketone, diacetone alcohol, and cyclohexanone are used. It is more preferable to use a mixture of two or more of these organic solvents than to use them alone. A preferred example is ethylene glycol monobutyl ether/
Mention may be made of the butanol/octanol combination and the butyl cellosolve/butanol/cyclohexanone combination. The total amount of water and organic solvent contained in the aqueous dispersion is preferably in the range of 10 to 1000 parts by weight based on 100 parts by weight of the resin solid content. The ratio of water to organic solvent is preferably 3:1 to 20:1 by weight. The obtained aqueous dispersion can be applied to an object by spray coating, roller coating, dipping coating, electrodeposition coating, or the like. The applied wet coating film can be baked at 100 to 200°C for 1 to 30 minutes, preferably at 160 to 200°C for 1 to 5 minutes, to form a uniform, transparent and good coating. By baking, the carboxyl groups in the components (A) and (C) react with the epoxy groups in the components (A) and (B) to form a crosslinked structure.
The reaction at this time is greatly accelerated by the addition of a catalyst. Basic compounds are effective as catalysts, such as alkali metal hydroxides such as KOH and NaOH, phosphorus compounds such as triphenylphosphine and triphenylphosphonium ethyliodine salt, and trimethylamine, benzyldimethylamine, diethylaminoethanol, etc. The following amine compounds can be mentioned. Preferred is diethylaminoethanol. The coating film obtained from the composition of the present invention can crosslink by itself to form a good coating film, but if necessary, a compound capable of reacting with the functional group of the composition of the present invention may be added to further improve the coating film. It is also possible to increase the degree of crosslinking. That is, since carboxyl groups, epoxy groups, and hydroxyl groups are present as functional groups in the composition of the present invention, the composition has functional groups such as hydroxyl groups, amino groups, carboxyl groups, acid anhydride groups, isocyanate groups, and methylol groups. Compounds, especially polyfunctional compounds, may be added. Specific examples include polyamines such as diethylenetriamine and diphenyldiaminomethane, acid anhydrides such as phthalic acid and trimellitic acid,
Examples include blocked isocyanates such as blocked tolylene diisocyanate and hexamethylene diisocyanate, methylol group-containing resins such as urea resins, melamine resins and phenol resins, dicyandiamide, and benzoguanamine. Preferred examples include melamine resins and phenolic resins, which can greatly improve the chemical resistance of the coating film. Pigments, additives, etc. commonly used in water-dispersible paints can be used in the composition of the present invention. Examples of pigments include titanium oxide, red iron oxide, talc, calcium carbonate, magnesium carbonate, aluminum powder, iron oxide, lead white, lead chromate, and carbon black. Examples of additives include carboxymethyl cellulose, polyvinylpyrrolidone, vinyl chloride-acetic acid emulsion, and the like. The objects to be coated with the composition of the present invention are mainly metals such as iron and its alloys, aluminum and its alloys, but are not necessarily limited thereto. As a special purpose, it can be used as a protective coating on the inner surface of cans, including beverage cans. Next, the present invention will be explained in more detail with reference to Examples. Parts in the examples refer to parts by weight unless otherwise specified. Example 1 1 Preparation of copolymer (A) component Bisphenol A type epoxy resin AER-331 (manufactured by Asahi Kasei Corporation) having an epoxy equivalent of 189 was distilled to obtain an epoxy resin having an epoxy equivalent of 170. Add 8.6 parts of methacrylic acid to 170 parts of this resin at 140°C.
A viscous resin was obtained by reacting for a period of time. The acid value of this resin was 0.5. When this resin was subjected to GPC and its weight fraction was examined, it was found that epoxy monoacrylate was 20.5% by weight and unreacted epoxy resin was 79.5% by weight. Therefore, this resin was fractionated using the difference in adsorption by styrene gel particles, and a 100% product of epoxy monoacrylate (hereinafter referred to as epoxy monoacrylate A) was obtained. This compound has a molecular weight of 426, one terminal group is an acryloyl group, the other terminal group is an epoxy group, and the structural unit (Y) in the copolymer (A) component in the composition of the present invention is It is a monomer that forms. 50 parts of methyl isobutyl ketone and 50 parts of n-butanol are charged into a reactor equipped with a reflux device prepared in advance and kept at 80°C. A monomer mixture having the following composition is added dropwise to this. Styrene 35 parts (0.34 mol) Methyl methacrylate 15 parts (0.15 mol) Epoxy monoacrylate A
25 parts (0.056 mol) Methacrylic acid 25 parts (0.29 mol) 4 parts azobisisobutyronitrile (hereinafter referred to as AIBN) After the dropwise addition, 1 part of AIBN was added and the reaction was continued by keeping at 90°C for about 24 hours. Ta. After the reaction was completed, the solvent was completely removed using a pressure reduction device to obtain solid resin A-1. The weight average molecular weight of A-1 was 5,500. The monomer yield was 99.5%. 2 Preparation of copolymer (C) component Next, in the same manner as above, styrene 35 parts methyl methacrylate 15 parts methacrylic acid 25 parts AIBN 3.5 parts The monomers of the composition were polymerized. After polymerization, the solvent is completely removed by vacuum treatment and solid resin C-
I got 1. The monomer yield was 99.8%. 3 Analysis of Resin A-1 First, a 6:1 solution (referred to as mixed solvent A) of gloloform/THF was prepared. When 50 parts of this solution was mixed and stirred with 10 parts of resin A-1 and left to stand overnight, some undissolved portion remained in the upper layer. Pass this undissolved part through your mouth, dry it, and then IR.
The presence or absence of epoxy groups and bisphenol A skeleton was investigated by NMR. As a result, the existence of either could not be confirmed. When the weight was measured, it was 0.1 part. Next, the dissolved portion was taken out, dried in the same manner, and weighed, and found to be 9.9 parts.
The absorption of the epoxy group of the resin in the dissolved region was detected by IR, and the skeleton of bisphenol A was detected by NMR. When the epoxy equivalent was similarly measured, it was found to be 1950, which revealed that the epoxy group of epoxy monoacrylate A remained intact. Therefore, the obtained resin is a copolymer composed of styrene/methyl methacrylate/epoxy monoacrylate/methacrylic acid = 6.07/2.68/1.0/5.17 in a molar ratio of 99% by weight, and the remaining 1% by weight % was found to be a copolymer containing no epoxy monoacrylate. 4. Mixing of three components The following resin mixture was prepared using AER-667 (manufactured by Asahi Kasei Corporation, epoxy equivalent: 2000) as epoxy resin B-1. A-1 35 parts B-1 62 parts C-1 3 parts Ethylene glycol monobutyl ether 35 parts n-octanol 15 parts Total 150 parts 5 Preparation of aqueous dispersion Heat 150 parts of the resin mixture to 50°C and stir. While the neutralizing agent dimethylaminoethanol
4.3 parts and 300 parts of water were added dropwise to obtain aqueous dispersion-1. The obtained aqueous dispersion-1 was left in a dryer at 40°C for one month, but no change was observed. 6 Creation of baked paint film and evaluation of physical properties Spray the aqueous dispersion-1 onto an aluminum plate to a dry film thickness of 10 microns, and immediately
3 in a hot air circulation type dryer controlled at 180℃
After baking for a minute, a transparent coating was obtained. Using this coating film, a hot water immersion test, a sterilization test, a flexibility test, and a water extraction test were conducted. In the hot water immersion test, a painted board was immersed in a 100°C solution of pure water, 5% NaCl solution, and 5% citric acid solution for 1 hour, and then pulled out to examine the deterioration and adhesion of the coating film. . In the sterilization test, the painted board was exposed to steam at 125°C for 1 hour, and the deterioration and adhesion of the paint film were examined. Flexibility was determined by bending the material 180 degrees with the painted side facing out and examining whether or not there were any cracks. The water extraction test was conducted in accordance with the method specified by Ministry of Health and Welfare Notification No. 370, and the amount of potassium permanganate consumed in the extract was investigated. Results (1) Warm water immersion test Appearance Patch adhesion Pure water No abnormality 100/100 5% NaCl aqueous solution 〃 100/100 5% citric acid aqueous solution No abnormality 100/100 (2) Sterilization test Appearance No abnormality Patch adhesion Test 100/100 (3) Flexibility No cracks (4) Water extraction test KMnO ₄ consumption 2.4 ppm Examples 2 to 4 A-1, C-1 and B-1 synthesized in Example 1
Aqueous dispersions-2, 3, and 4 were obtained according to the formulations shown in Table-1.

【table】

[Table] Using the obtained aqueous dispersion, a coating film was prepared in the same manner as in the example, and the physical properties were evaluated. The results are shown in Table-2. Further, when the aqueous dispersion was left at 25°C for 6 months, no change was observed in either case.

[Table] Comparative Example 1 A-1, C-1 and B-1 synthesized in Example 1
Using this method, aqueous dispersion 5 was obtained according to the following formulation. A-1 30 parts B-1 60 parts C-1 10 parts Ethylene glycol monobutyl ether 35 parts n-octanol 15 parts Dimethylaminoethanol 3.3 parts Water 300 parts Using the obtained aqueous dispersion, the same method as in Example A coating film was prepared and its physical properties were evaluated. The results are shown below. (1) Warm water immersion test Appearance Adherence to pure water No abnormalities 100/100 5% NaCl aqueous solution Whitening 80/100 5% citric acid aqueous solution Whitening 50/100 (2) Sterilization test Slight whitening 100/100 (3) Flexibility No cracks (4) Water extraction test KMnO ₄ consumption 5.1 ppm Comparative example 2 Aqueous dispersion-6 was obtained by changing the amount of dimethylaminoethanol used in Example 1 to 8.6 parts. . When the aqueous dispersion-6 was left in a dryer at 40°C, it gelled in about one week. Example 5 270 parts of bisphenol A type epoxy resin AER-669 (manufactured by Asahi Kasei Corporation) having an epoxy equivalent of 2700, 2.1 parts of methacrylic acid and NaOH as a catalyst were mixed at a temperature of 130°C in 200 parts of ethylene glycol monobutyl ether. The reaction was continued for about 5 hours. A monomer solution was prepared by mixing 472.1 parts of this resin solution with 40 parts of styrene, 50 parts of methacrylic acid, 20 parts of ethyl acrylate, and 5 parts of lauryl peroxide. One-third of this monomer solution is charged into a reactor equipped with a reflux device and kept at 85°C for about 5 hours. Add the remaining 1/3 dropwise over about 10 hours. After the dropwise addition was completed, the reaction was carried out for about 10 hours to obtain a viscous resin solution. The solvent was removed from this resin solution under reduced pressure to obtain 385 parts of solid resin. To this, add a solvent of chloroform and tetrahydrofuran in a weight ratio of 6:1.
After adding 2000 parts and stirring and mixing well at room temperature,
I left it for a day and night. 1000 parts of the dissolved portion was taken out and the solvent was removed again under reduced pressure to obtain a solid resin.
When the molecular weight distribution of this solid resin was examined by GPC, it was confirmed that there was a first molecular weight distribution based on AER-669 and a second molecular weight distribution on the higher molecular side. Therefore, a low molecular weight sample X-1 with a first molecular weight distribution and a high molecular weight sample X-2 with a second molecular weight distribution were fractionated by GPC and subjected to NMR and pyrolysis gas chromatography. As a result, it was confirmed that X-1 was a bifunctional bisphenol A type epoxy resin, and X-2 contained residues of styrene, methacrylic acid, ethyl acrylate, and bisphenol A type epoxy resin. Add C synthesized in Example 1 to 98 parts of this solid resin.
- Add 2 parts of component 1, 10 parts of cyclohexynone, and 10 parts of ethylene glycol monobutyl ether and dissolve them uniformly, then dimethylaminoethanol.
3.5 parts and 395 parts of water were added to obtain an aqueous dispersion solution 7. The properties of aqueous dispersion solution 7 were as follows. PH 6.8 Viscosity (B-type viscometer 25℃/cps) 380 Average diameter of dispersed particles (μm) 0.4 Condition after standing at 40℃/1 month No change Spread water dispersion solution 7 on a tin plate and the dry film thickness becomes 10μ The coating was applied in a similar manner and baked at 190°C for 1 minute. This process was repeated to obtain a coating film with a thickness of 30μ. This coating film was peeled off from the tin plate using the mercury amalgam method and used as a sample for evaluation. In the test, tensile strength, elongation, and water absorption were measured in accordance with JIS-K-6911. Tensile strength (Kg/cm ² ) 45.8 Elongation rate (%) 9.5 Water absorption rate (wt%)* 0.8 *Weight increase after 1 week immersion at 25°C Next, using this aqueous dispersion 7, the same procedure as in Example 1 was carried out. The physical properties of the coating film were evaluated. The results are shown below. (1) Hot water immersion test Appearance Goban adhesion Pure water No abnormalities 100/100 5% NaCl aqueous solution 〃 〃 5% citric acid aqueous solution 〃 〃 (2) Sterilization test 〃 〃 (3) Flexibility No cracks (4) Water extraction Test KMnO ₄ consumption 0.8ppm

Claims (1)

[Claims] 1 (a) A copolymer (A) component whose structural formula consists of the following structural units (X), (Y) and (Z) and [Formula] [Formula] [Formula] [However, R ₁ is -H or -CH ₃ , R ₂ is [Formula] or [Formula] (where R ₅ is -C _o H ₂₊₁ (n=1, 2), R ₃ is (Here, m = an integer from 0 to 100, and R ₆ represents [formula].)] (b) The structural formula is [However, R ₇ The epoxy resin (B) component and (c) structural formula represented by the following structural units (X) and (Z)
A copolymer consisting of component (C) [formula] [formula] In a mixture consisting of component (C) and [formula], the weight ratio is component (C) / component (A) + component (B) + component (C) x 100 < 5 (1) The copolymer (A) component contains x moles of the structural unit (X), y moles of the structural unit (Y) and z moles of the structural unit (Z), and x, y and z The relational expression between is 20<x/x+y+z×100<70 (2) 30<z/x+y+z×100<80 (3) 1≦y<5 (4) and (A) A water-dispersible resin composition characterized in that not more than 50% of the carboxyl groups in the component and (B) are salts neutralized with amines. 2 The total weight of the structural unit (Y) of the copolymer (A) component and the epoxy resin (B) component is 70 to 90% of the total weight of the (A) component, (B) component, and (C) component. % of the composition according to claim 1. 3 The ratio of copolymer (A) component and epoxy resin (B) component used is expressed by the following formula 35 < (A) component / (A) component + (B) component + (C) component x 100 < 80 (5 ) 20<component (B)/component (A)+component (B)+component (C)×100<65(6).