JPH02286736A - Water-base resin composition - Google Patents

Abstract

PURPOSE:To obtain a water-base resin composition which excels in film-forming properties and can give a coating film excellent in flexibility, corrosion resistance and water resistance by reacting a specified acrylic resin with an aromatic epoxy resin and a long-chain aliphatic epoxy resin in the presence of a basic compound. CONSTITUTION:An acrylic resin having a carboxyl in the molecular side chain is reacted with an aromatic epoxy resin (especially desirably a bisphenol A diglycidyl ether epoxy resin of an epoxy equivalent weight of 800-4500), a long- chain aliphatic epoxy resin (especially desirably epoxidized polybutadiene of a number-average MW of 600-3000 and an oxirane oxygen content of 3-10%) in the presence of a basic compound (e.g. trimethylamine). A water-base resin composition which excels in film-forming properties and can give a coating film excellent in all of adhesiveness, processability, corrosion resistance and water resistance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an aqueous resin composition that does not use an emulsifier or a protective colloid.

[Conventional technology]

Epoxy resins have excellent toughness, adhesive properties, and chemical resistance, and are widely used in various fields such as paints, adhesives, and binders.

Attempts have been made to make epoxy resins water-based, and epoxy emulsions made by emulsifying and dispersing them using large amounts of emulsifiers and protective colloids are known. In addition, as a product that does not use emulsifiers or protective colloids,
No. 9, JP-A No. 64-29468 discloses an anionic aqueous resin dispersion obtained by reacting an aromatic epoxy resin with an acrylic resin having a carboxyl group in the molecular side chain in the presence of a basic compound. Are listed.

[Problem to be solved by the invention]

However, the conventional so-called epoxy emulsion, which is emulsified and dispersed using a large amount of emulsifier, has poor stability.
Although the coating film obtained by curing this with a curing agent has excellent film-forming properties, it goes without saying that it has many problems in terms of water resistance and corrosion resistance.

On the other hand, Japanese Patent Publication No. 63-41949, Japanese Patent Application Publication No. 6429
Anionic water-based resins such as those described in Japanese Patent No. 468 have a high minimum film-forming temperature and have problems in film-forming properties. That is, even if the coating is cured without being formed at room temperature, there are problems with the homogeneity and smoothness of the coating, micro pinholes, etc. are formed, and water resistance, corrosion resistance, adhesion and processability cannot be fully exhibited.

[Means to solve the problem]

Therefore, the present inventor conducted intensive studies to produce a water-based resin that has excellent film-thickening properties and can provide a coating film that is excellent in adhesion, processability, corrosion resistance, and water resistance, and has finally completed the present invention. .

[Means for Solving the Problems] Therefore, the present inventor conducted extensive studies in order to produce a water-based resin composition that has excellent film-thickening properties and can provide a coating film that is excellent in flexibility, corrosion resistance, and water resistance. The present invention has now been completed.

That is, in the present invention, an acrylic resin (A) having a carboxyl group in a molecular side chain, an aromatic epoxy resin (B), and a long-chain aliphatic epoxy resin (C) are combined in the presence of a basic compound (D). The present invention provides an aqueous resin composition containing the reacted resin (I).

The resin (1) according to the present invention is a basic compound ( The reaction may be carried out in the presence of D).

The acrylic resin (A) having a carboxyl group in its molecular side chain used in the production of the resin (1) according to the present invention is, for example, mixed with ethylenically unsaturated carboxylic acid and other copolymerizable unsaturated monomers in an organic solvent. It can be obtained by copolymerizing by a conventional method using a conventional radical polymerization initiator such as azobisisobutyronitrile or benzoyl peroxide.

The ethylenically unsaturated carboxylic acid used in the production of the acrylic resin (A) is a compound having an ethylenically unsaturated double bond and at least one carboxyl group, for example,
Examples include (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, monomethyl maleate, monoethyl fumarate, and mono-n-butyl itaconate. Other copolymerizable unsaturated monomers include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate,
(meth)acrylic esters such as pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, and octadecyl (meth)acrylate, styrene, α-methylstyrene, Ethylenically unsaturated aromatic monomers such as vinyltoluene, chlorostyrene, 2,4-dibromustyrene, etc., unsaturated nitriles such as (meth)acrylonitrile, and vinyl esters such as vinyl acetate, vinyl propionate, etc. , vinylidene halides such as vinylidene chloride, vinylidene bromide, 2-hydroxyethyl acrylate,
2-hydroxypropyl acrylate, 2-methacrylate
- hydroxyalkyl esters of ethylenically unsaturated carboxylic acids such as hydroxyethyl, glycidyl esters of ethylenically unsaturated carboxylic acids such as glycidyl (meth)acrylate, and (meth)acrylamide, N-methylol (meth)acrylamide, N Examples include monomers capable of radical polymerization such as -butoxymethylacrylamide and diacetone acrylamide.

The amount of ethylenically unsaturated carboxylic acid used is at least 12% by weight of the total monomers constituting the acrylic resin (A), and if the acid value of the resin (I) according to the present invention is 40 or more,
The amount used is preferably 0 or less. If the acid value is less than 40, the dispersion stability of the resin in an aqueous medium tends to deteriorate, and if the acid value exceeds 120, the water resistance of the coating film tends to deteriorate.

Acrylic resin (A) has a number average molecular weight of 1000 to 15
0,000 is preferred. If the molecular weight is small, emulsification and dispersibility will be hindered, and if the molecular weight is large, the viscosity of the resin (1) will become extremely high, making it impractical.

The aromatic epoxy resin (B) used in the production of the resin (1) according to the present invention is an aromatic resin having at least two epoxy groups in the molecule, such as bisphenol diglycidyl ether type, tetrabromo Examples include epoxy resins such as bisphenol diglycidyl ether type and novolak polyglycidyl ether type.

Among these epoxy resins, bisphenol diglycidyl ether type epoxy resins are preferable, and among them, bisphenol diglycidyl ether type epoxy resins having an epoxy equivalent of 450 or more are more preferable, and particularly, bisphenol diglycidyl ether type epoxy resins having an epoxy equivalent of 8
Bisphenol A diglycidyl ether type epoxy resin having a molecular weight of 00 to 4500 is preferred.

Further, if necessary, an epoxy compound having less than two epoxy groups in the molecule may be used in combination.

What is usually called an epoxy resin is a mixture of an epoxy resin having two or more epoxy groups in the molecule and an epoxy resin having less than two epoxy groups, and these can of course also be used.

Further, the long-chain aliphatic epoxy resin (C) according to the present invention refers to a carbon-carbon single bond that does not have an aromatic ring in the long chain (however,
An oxygen atom may be present in the middle. ) and at least two epoxy groups, such as epoxidized polybutadiene obtained by epoxidizing polybutadiene with peracid, and epoxy resin obtained by adding epichlorohydrin to polybutadiene having a hydroxyl or carboxyl group at the end. Examples thereof include glycidyl ethers of aliphatic polyethers such as oxidized polybutadiene, epoxidized oils, epoxidized fatty acids, dimer acid glycidyl esters, and polypropylene glycol glycidyl ethers.

The long chain aliphatic epoxy resin (C) has a number average molecular weight of 60
0 to 3,000 and an oxirane oxygen content of 3 to 10% is preferable, especially those with a number average molecular weight of 600 to 3,000.
Epoxidized polybutadiene with an oxirane oxygen content of 3 to 10% is preferred.

Such epoxidized polybutadiene includes, for example, polybutadiene E-700-8, E-1000-3,
5゜E-1000-8, E-2000-6,5 (and above,
(manufactured by Nippon Oil Co., Ltd.).

Poly bd R-45EPT (manufactured by Idemitsu Petrochemical Co., Ltd.) and the like.

Further, if necessary, a carbon-carbon single bond having no aromatic ring in the long chain (however, an oxygen atom may be interposed in the middle).

) and less than 2 epoxy groups (
Hereinafter, it will be referred to as a long-chain aliphatic epoxy compound. ) may be used together.

The reaction ratio of the acrylic resin (A), the aromatic epoxy resin (B), and the long-chain aliphatic epoxy resin (C) during the production of the resin (I) according to the present invention, that is, the oxirane group and the carboxyl group. The functional group ratio with the group is not particularly limited, but the value of oxirane group/carboxyl group is 1/
It is preferably 2 to 1/20. The ratio of the aromatic epoxy resin (B) to the long-chain aliphatic epoxy resin (C) is not particularly limited, but the weight ratio is 9515 to
Among 5/95, 90/10 to 50150 are preferable.

In addition, when using a high molecular weight acrylic resin (A) in the production of resin (1), aromatic epoxy resin (B)
It is sufficient to select a relatively low-molecular-weight one as the long-chain aliphatic epoxy resin (C), or when using a high-molecular-weight aromatic epoxy resin (B), an acrylic resin (A)
It is preferable to determine the reaction ratio of the resins (A) to (C) in consideration of the balance between the two, such as selecting a relatively low molecular weight one for the long-chain aliphatic epoxy resin (C).

The resin (I) according to the present invention is a basic compound ( The reaction may be carried out in the presence of D), and the conditions are not particularly limited, but usually the acrylic resin (A) and aromatic epoxy are reacted in the presence of a basic compound (D) in an organic solvent. Resin (B) and long chain aliphatic epoxy resin (C
) at 50 to 200°C for 15 minutes to 10 hours, preferably at 80 to 150°C for 20 minutes to 4 hours. More preferably, in order to reduce the formation of low-molecular compounds in the resin (1) and to generate a microgel body with a three-dimensional network structure, the first step is to heat the resin (1) at 50 to 100°C.
The non-gelled resin reactant is allowed to react for 0 minutes to 4 hours to a sufficient extent that it has self-emulsifying properties, that is, typically 20-80%, preferably 30-70% of the epoxy groups are reacted, and then Dispersion in water by neutralizing with a basic compound in an amount such that the pH of the dispersion becomes 5 or more in the second step, and further reacting the remaining epoxy groups and carboxyl groups in the dispersion in the third step. Therefore, it is preferable to prepare an aqueous dispersion of a microgel resin having a three-dimensional network structure.

The basic compound (C) may be any compound having basic properties, such as alkali metal hydroxides, alkaline earth metal hydroxides, alkaline earth metal oxides, and alkali metal carbonates. , alkaline earth metal carbonates, ammonia, hydrazine, and organic amines. Among them, ammonia and organic amines are preferred, and organic tertiary amines are particularly preferred.

Examples of organic amines include alkylamines such as trimethylamine, triethylamine, and butylamine, alkanolamines such as dimethylethanolamine, jetanolamine, triethanolamine, and aminomethylpropanol, and morpholine. Further, polyvalent amines such as ethylenediamine and diethylenetriamine can also be used if necessary. The amount of the basic compound (D) used is 30 to 1 in equivalent ratio to the carboxyl group of the acrylic resin.
An amount of 50% by weight is preferred.

Furthermore, as the basic compound used in the second step of producing resin (1), any of the above-mentioned basic compounds (C) can be used.

The organic solvent used in the production of resin (1) is not particularly limited, and any known and commonly used organic solvent can be used. For example, methanol, ethanol, n-propanol, isopropanol, n-butanol, 5ec-butanol, tert-butanol, isobutanol, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, ethyl calpitol, butyl calpitol, methyl Examples include cellosolve acetate, ethyl cellosolve acetate, other hydrophilic organic solvents such as dioxane, dimethylformamide, and dia-7ton alcohol, and lipophilic organic solvents such as ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, and xylene.

These may be used alone or in combination of two or more, and if necessary, water and the organic solvent may be used in combination.

If necessary, the organic solvent used during the production of resin (1) can be removed by distillation.

If necessary, the above-mentioned basic compound (C) can be added to the aqueous resin composition of the present invention to adjust the pH.

By using the aqueous resin composition of the present invention in combination with a curing agent (II), it is possible to provide an aqueous resin composition having thermosetting properties more suitable for coatings. The curing agent used here (
II) is not particularly limited, and any known and commonly used curing agent can be used. Examples include urea formaldehyde resin, melamine-formaldehyde resin, benzoguanamine-formaldehyde resin, phenol-formaldehyde resin, blocked polyisocyanate, and the like. The amount of curing agent (II) used is 10% of the solid content of resin (I).
It is preferably 30 parts by weight or less, especially 20 parts by weight or less relative to 0 parts by weight.

The aqueous resin composition containing the curing agent (II) has a hardening agent of 100
By heating and drying at ~300°C for 30 seconds to 30 minutes, a coating film with better adhesion and water resistance can be obtained than when no curing agent is included.

A curing agent, a pigment, a filler, a fluidity regulator, an antifoaming agent, a tackifying agent, a flame retardant, an antioxidant, and other additives may be added to the aqueous resin composition of the present invention as necessary. good.

The aqueous resin composition of the present invention can be used in various fields such as paints, adhesives, fiber treatment agents, and binders. It is particularly excellent as a paint for metals, and can be applied by commonly known coating methods such as spray coating, roll coating, and dipping coating.

The present invention will be explained below with reference to Examples. Unless otherwise specified, "parts" and "%" are based on weight.

Example 1 Condenser, thermometer, dropping funnel, nitrogen gas introduction pipe,
After purging the flask equipped with a stirrer with nitrogen, 100 parts of n-butanol was charged, the temperature was raised to the reflux temperature, and 65 parts of methacrylic acid, 5 parts of styrene, 30 parts of ethyl acrylate, and 3.0 parts of benzoyl peroxide were added. , a mixed solution of 47.5 parts of n-butanol was added dropwise over 2 hours,
After that, it was kept at the reflux temperature for 3 hours and the number average molecular weight was 4.
An acrylic resin with an acid value of 100 and an acid value of 424 was obtained.

After purging the flask equipped with a condenser, thermometer, nitrogen gas inlet tube, and stirrer with nitrogen, 118 g of n-butanol was added.
1 part, raise the temperature to the reflux temperature, and apply Epikote 1.
010 (Bisphenol A diglycidyl ether type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 3800) After adding and dissolving 112 parts, 105°
In C, 36 parts of Nisseki Polybutadiene E-1000-3,5 (epoxidized polybutadiene manufactured by Nippon Oil Co., Ltd., number average molecular weight 1000, oxirane oxygen content 3.5%), 130 parts of the above acrylic resin, dimethyl ethanol 25.5 parts of amine was added and maintained at 105°C for 2 hours. 9
After cooling to 0°C, 467 parts of ion-exchanged water was added, stirred and mixed to disperse it in water, and after further addition of ion-exchanged water, n-butanol was removed by vacuum distillation to obtain an aqueous resin composition (I-a). ) was obtained.

This product has an acid value of 80, non-volatile content of 26%, and a viscosity of 188 cp.
s, pH 6.7.

Example 2 64 parts n-butanol, 16 parts toluene, 1 Epicote
010 (Bisphenol A diglycidyl ether type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 3800) 80 parts, Nisseki Polybutadiene E-1000
-3,5 (manufactured by Nippon Oil Co., Ltd., epoxidized polybutadiene molecular weight 1000, oxirane oxygen content 3.5%) 6
An aqueous resin composition (I
-b) was obtained. This stuff has an acid value of 95, non-volatile content of 23%,
Viscosity 33 cps.

The pH was 6.5.

Comparative Example 1 128 parts of n-butanol, Epicoat 1010 (bisphenol A diglycidyl ether type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 3800)
An aqueous resin composition (160 parts), 100 parts of the acrylic resin obtained in Example 1, 14 parts of dimethylethanolamine, and 467 parts of ion-exchanged water were used in the same manner as in Example 1.
-c) was obtained. This stuff has an acid value of 70, non-volatile content of 20%,
The viscosity was 23 cps and the pH was 6.5.

Application Example 1-2 and Comparative Application Example 1 Beckamine APH (Dainippon Ink & Chemicals Co., Ltd.) water-soluble melamine was added to 100 parts of the solid content of the aqueous resin composition obtained in Example 1-2 and Comparative Example 1. 3 parts of formaldehyde resin (in terms of solid content) were added, and the minimum film-forming temperature (which is a measure of film-forming property) was measured based on JIS K6828.

Also, in the same manner as above, an aqueous resin composition containing Beckamin APR was applied to an untreated steel plate, and after air drying at room temperature,
A sample (film thickness: 20 μM) was prepared by baking at 0° C. for 10 minutes, and the physical properties of the coating film (water resistance, corrosion resistance, adhesion, and flexibility) were measured based on JIS K5400. The results are shown in Table 1.

(However, flexibility is a measure of workability.) / [7/' / As shown in Figure 7, the toxicity to the human body and the risk of fire, which are disadvantages when using conventional organic solvents, are extremely small. .

For example, the water-based resin composition of the present invention containing a curing agent has extremely excellent film-thickening properties, processability, adhesion, corrosion resistance, and water resistance, which are not found in conventional water-based epoxy resins or water-based epoxy modified resin paints. Since it has the characteristic of providing a coating film, it can be used in various fields such as adhesives, fiber treatment agents, paints, and binders.

The aqueous resin composition of the present invention has an extremely low minimum film forming temperature,
By air drying at room temperature, a homogeneous and smooth coating was formed without any flaking. Furthermore, as is clear from Table 1, the coated film after baking was excellent in all of water resistance, corrosion resistance, adhesion, and flexibility.

〔Effect of the invention〕

Claims (1)

[Claims] 1. An acrylic resin (A) having a carboxyl group in its molecular side chain, an aromatic epoxy resin (B), and a long-chain aliphatic epoxy resin (C) are combined into a basic compound (D). ) An aqueous resin composition containing a resin (I) reacted in the presence of 2. The composition according to claim 1, wherein the long-chain aliphatic epoxy resin (C) is epoxidized polybutadiene. 3. The long chain aliphatic epoxy resin (C) has a number average molecular weight of 600 to 3000 and an oxirane oxygen content of 3 to 1
A composition according to claim 1, which is 0% by weight epoxidized polybutadiene. 4. The composition according to claim 1, which contains a curing agent (II). 5. The composition according to claim 4, wherein the curing agent (II) is at least one selected from melamine-formaldehyde resins and phenol-formaldehyde resins.