JPH10168384A - Resin for aqueous coating material and aqueous coating material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin for an aqueous coating material capable of providing a coating film excellent in adhesion to a metal, waterproof properties, etc., and further capable of providing an aqueous coating material excellent in water- solubility and preservation stability by copolymerizing a polyol compound, a vinyl-based monomer containing carboxylic acid group and other copolymerizable vinyl-based monomers. SOLUTION: This resin for an aqueous coating material comprises a copolymer obtained by copolymerizing (A) 5-50wt.% polyol compound having two or more hydroxyl groups, (B) 3-20wt.% vinyl-based monomer containing carboxylic acid group and (C) 30-92wt.% other copolymerizable vinyl-based monomers. The component A is exemplified by a compound having a structure of the formula [X is H, a <=20 alkylene, etc.; (m) is >=3; (a) and (b) are each >=1], e.g. a polycaprolactone polyol, as a main chain. The component B is exemplified by a monomer containing carboxylic acid of the formula (R<2> )CH= C(R<1> )COOH [R<1> is H, methyl, etc.; R<2> is H or a group of the formula COOR<3> (R<3> is H or a 1-10C hydrocarbon substituent)].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a coating film having good adhesion to a substrate of a coating film, particularly to a metal, and having a good balance between coating film hardness and impact resistance and having excellent water resistance. The present invention relates to a water-based paint resin that can be formed and can obtain a water-based paint excellent in storage stability, and a water-based paint using the same.

[0002]

2. Description of the Related Art Food cans, including beverage cans used in canned coffee, canned juice, canned beer, and the like, include:
In order to impart corrosion resistance to the contents, in the case of a can containing retort food, a coating is applied to withstand sterilization treatment.

Conventionally, organic solvent type paints such as epoxy resin / amino resin paint, acrylic resin / amino resin paint and polyester resin / amino resin paint have been used as the paint for cans. A method of heat curing in a baking furnace is used for curing the coating film. But,
Coating films formed from these solvent-type paints are said to cause a large amount of organic solvent to volatilize during the thermosetting treatment, which causes air pollution and is problematic from the viewpoint of resource saving. There is a demand for the appearance of a resin for water-based paint having a low content of.

There are two types of resins for water-based paints, water-dispersible resins and water-soluble resins. Water-dispersible resins are produced by an emulsion polymerization method of a vinyl monomer using an aqueous medium containing an emulsifier. In the coating film formed from this water-dispersible resin, because the surfactant used as an emulsifier remains, the water resistance of the coating film is inferior, and due to its structural viscosity, coating with a roll coater is performed. It has the problem of being difficult.

On the other hand, an acrylic resin is generally used as a water-soluble resin, but in order to make the water-soluble resin water-soluble, it is necessary to introduce a carboxyl group into the molecule. However, a coating film formed from a water-soluble resin into which a large amount of a carboxyl group has been introduced in order to increase the water solubility of the resin has a problem that water resistance and alkali resistance are insufficient.

In order to solve this problem, a method of using an aminoplast which gives a crosslinked structure to a coating film together with a water-soluble acrylic resin has been adopted. Does not have sufficient adhesion to the metal as the coating substrate. Therefore, as a method of improving adhesion, a method of further using a polyol resin in combination with the water-soluble paint has been adopted. However, water-based paints composed of water-soluble acrylic resins, aminoplasts and polyol resins have disadvantages such as phase separation of the polyol resin during storage and cloudiness of the formed coating film.
Not enough has yet been obtained.

Further, Japanese Patent Application Laid-Open No. 63-230779,
JP-A-63-248874 discloses that as a polyol compound, ethylene glycol or 1,
Polyester polyols and polyether polyols to which 1 to 20 moles of 2-propylene glycol have been added are shown to be suitable as components of the aqueous coating composition. However, although all compounds are excellent in solubility and stability in an aqueous medium, a coating film obtained from this composition has insufficient water resistance due to its structure, and is particularly resistant to a steam sterilization step. Poor water resistance (hereinafter referred to as retort resistance).

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to form a coating film having excellent adhesion to metal, balance between hardness and impact resistance, excellent water resistance, and excellent water solubility and storage stability. An object of the present invention is to provide a water-based paint resin that can constitute a paint.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies on resins for water-based paints in order to achieve the above object, and as a result, have reached the present invention.

That is, the present invention provides a polyol compound (A) having two or more hydroxyl groups in a molecule of 5 to 50% by weight,
3-20% by weight of a vinyl monomer having a carboxylic acid group (B) and another copolymerizable vinyl monomer (C)
Aqueous paint resin comprising a copolymer obtained by copolymerizing 30 to 92% by weight, and an aqueous paint obtained by blending 10 to 150 parts by weight of a water-soluble amino resin with respect to 100 parts by weight of the resin for aqueous paint. It is.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The water-based coating resin of the present invention comprises a polyol compound (A) having two or more hydroxyl groups in a molecule, a vinyl monomer (B) having a carboxylic acid group and other copolymers. It comprises a copolymer obtained by copolymerizing a possible vinyl monomer (C).

The polyol compound (A) having two or more hydroxyl groups in the molecule, which is a component of the copolymer in the resin for aqueous coating composition of the present invention (hereinafter referred to as the polyol compound (A))
That. ) Is used in the range of 5 to 50% by weight in the copolymer component. This is because if the amount is less than 5% by weight, the adhesion of the obtained coating film will be insufficient, while if it exceeds 50% by weight, the viscosity of the obtained polymer will increase and the coating workability will decrease. Preferably it is in the range of 10 to 40% by weight.

The polyol compound (A) used in the present invention preferably has a hydroxyl value in the range of 10 to 600 mgKOH / g. This means that the hydroxyl group is 10mg
If it is less than KOH / g, the crosslinking point with the amino resin as a crosslinking agent tends to be small and water resistance tends to decrease, while if the hydroxyl value exceeds 600 mgKOH / g, the number of crosslinking points with the amino resin increases, and This is because the workability of the resulting coating film becomes poor. More preferably 30 to 500 mg KO
H / g.

The polyol compound (A) used in the present invention includes, for example, polyester polyols and polyether polyols having a structure represented by the following general formula (I) or (II) in the main chain. .

[0015]

Embedded image

(Wherein, X represents a hydrogen atom or an alkylene group, alkenylene group, arylene group or cycloalkylene group which may contain an ester bond or an ether bond having 20 or less carbon atoms, m represents an integer of 3 or more, a and b represent an integer of 1 or more.)

[0017]

Embedded image

(Wherein, Y represents a hydrogen atom or an alkylene group, alkenylene group, arylene group, or cycloalkylene group which may contain an ester bond or an ether bond having 20 or less carbon atoms, and n represents an integer of 3 or more; c and d represent an integer of 1 or more.

Specific examples of the polyol compound having the structure represented by the general formula (I) in the main chain include a compound having a molecular weight of 5
And polycaprolactone polyols and polybutyrolactone polyols which may contain 000 or less ester bonds or ether bonds. The polycaprolactone polyol or polybutyrolactone polyol can be easily obtained by subjecting 1 mol of water to 1 mol of ε-caprolactone or 1 mol of γ-butyrolactone according to a conventional method. As a typical example of the polyol compound having the structure of the general formula (I) in the main chain, PLACCEL manufactured by Daicel Chemical Industries, Ltd.
(Placcel) 200 series and PLACCEL
(Placcel) 300 series and the like.

Specific examples of the polyol compound having the structure represented by the above general formula (II) in the main chain include, for example,
Examples thereof include polytetramethylene polyol having a molecular weight of 5000 or less and which may contain an ester bond or an ether bond. The polytetramethylene polyol can be easily obtained by, for example, ring-opening addition of 1 mol of tetrahydrofuran to 1 mol of water according to a conventional method. As a typical example of a polyol compound having a structure represented by the above general formula (II) in the main chain, BASF Japan
Poly THF, a product of Co., Ltd., and PTMG, a product of Hodogaya Chemical Co., Ltd., and the like. These polyol compounds (A) can be used alone or in combination of two or more as necessary.

The vinyl monomer (B) having a carboxylic acid group, which is a component of the copolymer in the resin for aqueous coating composition of the present invention, is used in an amount of 3 to 20% by weight in the copolymer component. You. This is because if the amount is less than 3% by weight, the solubility of the obtained copolymer in water decreases, and if it exceeds 20% by weight, the water resistance of the coating film decreases. Preferably 5 to 1
It is in the range of 5% by weight.

Examples of the vinyl monomer having a carboxylic acid group (B) used in the present invention include a carboxyl group-containing monomer having a structure represented by the following general formula (III) or the following general formula (IV): Can be mentioned.

[0023]

(R ² ) CH ＝ C (R ¹ ) COOH (III) wherein R ¹ represents a hydrogen atom or a methyl group or a carboxymethyl group, and R ² represents a hydrogen atom or —COOR
³ represents an oxygen atom-containing hydrocarbon substituent represented by ³ (R ³ represents a hydrogen atom or a hydrocarbon substituent having 1 to 10 carbon atoms). ]

[0024]

Embedded image CH ₂ = C (R ⁴⁾ in ^{COO-R 5 -COOH (IV)} [ wherein, R ⁴ represents a hydrogen atom or a methyl group, R ⁵
Is -R ^6- (wherein, R ⁶ represents a linear or branched alkylene group having 1 to 3 carbon atoms), and the following formula (V)

[0025]

Embedded image

(Wherein R ⁷ represents a linear or branched alkylene group having 1 to 10 carbon atoms, and R ⁸ represents a C 2 to C 2 alkylene group)
Represents a linear or branched alkylene group or alkenylene group, or an arylene group or cycloalkylene group which may be substituted with a carboxyl group or a halogen atom. ) Or the following formula (VI)

[0027]

Embedded image

(In the formula, R ⁹ represents a linear or branched alkylene group having 1 to 10 carbon atoms, m represents an integer of 4 to 6, and R ¹⁰ represents a linear alkylene group having 2 to 10 carbon atoms. Or a branched alkylene group or alkenylene group, or a carboxyl group or an arylene group or a cycloalkylene group optionally substituted with a halogen atom, wherein n is 1 to
Represents an integer of 6. ) Represents a hydrocarbon substituent having the structure represented by or a hydrocarbon substituent substituted with a hetero atom. ]

Specific examples of the carboxyl group-containing monomer having the structure represented by the general formula (III) include methacrylic acid, acrylic acid, crotonic acid, vinylbenzoic acid, fumaric acid, itaconic acid, maleic acid and citraconic acid. Monobasic or dibasic acid monomers such as monomethyl maleate;
Monoethyl maleate, Monobutyl maleate, Monooctyl maleate, Monomethyl itaconate, Monoethyl itaconate, Monobutyl itaconate, Monooctyl itaconate, Monomethyl fumarate, Monoethyl fumarate, Monobutyl fumarate, Monooctyl fumarate, Monoethyl citracone And the like. Monoesters of a dibasic acid or acid anhydride monomer typified by methacrylic acid, acrylic acid, and maleic acid monoester are preferable.

Specific examples of the carboxyl group-containing monomer having the structure represented by the general formula (IV) include β-carboxyethyl (meth) acrylate, β-carboxypropyl (meth) acrylate, and β- (meth) acrylic. Roxyethyl acid succinate, β- (meth) acryloxyethyl acid maleate, β- (meth) acryloxyethyl acid phthalate, β- (meth) acryloxyethyl acid hexahydrophthalate, β- (meth)
The terminal hydroxyl group of the ring-opened adduct of ε-caprolactone or γ-butyrolactone to acryloxyethyl acid methylhexahydrophthalate, γ- (meth) acryloxypropyl acid succinate, or 2-hydroxyethyl (meth) acrylate is converted to succinic anhydride. To a succinic acid monoester having a carboxyl group introduced at the end by esterification with 2-hydroxyethyl (meth) acrylate
-Caprolactone or a ring-opening adduct of γ-butyrolactone (for example, Plaxel F monomer manufactured by Daicel Chemical Industries, Ltd., Tone M monomer manufactured by UCC) to convert terminal hydroxyl groups to phthalic anhydride or hexahydrophthalic anhydride. Long chain carboxyl group-containing monomers such as half-ester reaction products of caprolactone-modified hydroxyl group-containing (meth) acrylic acid esters such as phthalic acid monoesters and hexahydrophthalic anhydride monoesters esterified with acids and acid anhydrides Among them, succinic acid monoester and phthalic acid monoester obtained by adding succinic acid or phthalic acid to a monomer having a primary hydroxyl group such as 2-hydroxyethyl (meth) acrylate are preferable. These vinyl monomers (B)
Can be used alone or in combination of two or more as necessary.

The other copolymerizable vinyl monomer (C), which is a component of the copolymer in the water-based coating resin of the present invention, is used in an amount of 30 to 92% by weight in the copolymer component. Is done. If the content is less than 30% by weight, the hardness of the coating film obtained from the copolymer is insufficient, so that the coating film is liable to be scratched or missing, and if it exceeds 92% by weight, the flexibility of the coating film is increased. Is because the processing resistance of the coating film becomes insufficient due to the decrease in Preferably it is in the range of 45 to 85% by weight.

As the vinyl monomer (C) used in the present invention, an alkyl (meth) acrylate having an alkyl group having 1 to 18 carbon atoms, for example, methyl (meth) acrylate, ethyl (meth) acrylate , Propyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, (meth) acrylic acid Octyl, stearyl (meth) acrylate and the like.

If necessary, aromatic vinyl compounds such as styrene and α-methylstyrene, vinyl esters such as vinyl acetate and vinyl propionate, nitrile group-containing monomers such as (meth) acrylonitrile, 2-hydroxyethyl Hydroxyalkyl (meth) acrylates such as (meth) acrylate; glycidyl group-containing monomers such as glycidyl (meth) acrylate; methacrylamides; or methylol-modified products of these amides; benzyl (meth) acrylate; Cyclopentenyl (meth) acrylate (for example, FA-product of Hitachi Chemical Co., Ltd.)
511A), tricyclodecanyl (meth) acrylate (for example, FA-513A manufactured by Hitachi Chemical Co., Ltd.)
And other commonly used monomers can also be used in combination.

The polymerization initiator used for copolymerizing the above components (A) to (C) is not particularly limited, and any known polymerization initiator can be used. For example, a radical polymerization initiator which is a peroxide such as lauryl peroxide, benzoyl peroxide, t-butyl peroctoate or an azo compound such as 2,2'-azobisisobutyronitrile is used. These polymerization initiators are used alone or in combination of two or more.

If necessary, a known chain transfer agent may be used. Examples of the chain transfer agent include n-dodecyl mercaptan, n-octyl mercaptan, 2-ethylhexyl thioglycolate, thiophenol, and α-methylstyrene dimer.

The polymerization method for obtaining the copolymer from the above components (A) to (C) is not particularly limited. For example, component (A) may be replaced with component (B) and component (C). ), A polymerization initiator, a chain transfer agent, and the like are added, and the mixture may be dropped and polymerized in a reaction vessel containing a hydrophilic organic solvent heated to a predetermined temperature, or the component ( A) and a hydrophilic organic solvent may be mixed and placed in a reaction vessel, and a mixture of the components (B) and (C), a polymerization initiator, a chain transfer agent, and the like may be dropped and polymerized.

Further, if necessary, after polymerization in a non-hydrophilic solvent such as toluene or xylene alone or in a mixed solvent with the above-mentioned hydrophilic solvent, the non-hydrophilic solvent is volatilized in vacuo or distilled off under reduced pressure to obtain a hydrophilic solvent. It may be replaced.

The hydrophilic organic solvent that can be used in the present invention includes, for example, methanol, ethanol,
Isopropanol, n-butanol, i-butanol,
alcohol-based organic solvents having an alkyl group of 4 or less such as t-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-propyl ether, ethylene glycol mono i-propyl ether, ethylene glycol mono n -Butyl ether, ethylene glycol mono i-
Butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tripropylene Monoalkyl glycol ether organic solvents having 4 or less carbon atoms in the alkyl group of the ether bond such as glycol monomethyl ether and tripropylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether Dialkyl glycol ether organic solvents having an alkyl group at the ether bond of 4 or less, such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, and dipropylene glycol diethyl ether; ethylene glycol monomethyl ether acetate; ethylene glycol monoethyl ether Examples thereof include monoalkyl glycol ether acetate organic solvents such as acetate, ketone organic solvents such as acetone and methyl ethyl ketone, and dioxane. The amount of the hydrophilic organic solvent to be used is not particularly limited.
It is in the range of 25 to 400 parts by weight with respect to 00 parts by weight.

The polymerization temperature is not generally determined by the type of polymerization initiator used, but is preferably in the range of 40 to 180.

The acid value of the copolymer obtained as described above is preferably in the range of 20 to 150 mgKOH / g. This is because the acid value of the copolymer is 20 mg KO
If it is less than H / g, the solubility in water tends to decrease, and it tends to separate easily in an aqueous solvent.
If the amount exceeds / g, the water resistance of the obtained coating film tends to decrease. More preferably 30 to 100 mgK
OH / g.

The above copolymer is neutralized with a basic compound and diluted with water to obtain a water-based coating resin. The neutralization of the copolymer with a basic compound is carried out with another resin such as an aqueous resin. It may be performed when an aqueous resin is prepared by adding an amino resin.

The basic compounds usable in the present invention include, for example, alkylamines such as triethylamine, trimethylamine and butylamine, 2-dimethylaminoethanol, triethanolamine, diethylethanolamine, dimethylethanolamine, aminomethylpropanol And morpholine. The amount of the basic compound used is preferably in the range of 50 to 150% of the acid value of the copolymer.

The resin for aqueous coating obtained by the present invention can be dissolved in an aqueous medium to obtain an aqueous coating. However, a water-based amino resin can be further added to obtain a cross-linkable aqueous coating. As the aqueous amino resin that can be used here,
Examples thereof include an alkyl etherified melamine resin, an alkyl etherified benzoguanamine resin, an alkyl etherified glycoluril resin, and an alkyl etherified resin of diguanamine in which two triazine rings are bonded to a phenylene nucleus. Amino resins are preferred. These amino resins are preferably used in a proportion of 10 to 150 parts by weight with respect to 100 parts by weight of the resin for aqueous paint.

The coating film formed from the aqueous coating composition containing the resin for aqueous coating composition of the present invention and the above-mentioned aqueous amino resin is further improved in stain resistance, hardness, solvent resistance, retort resistance and the like.

For obtaining the water-based paint of the present invention, a conventionally known polyether, polyester or the like may be used in combination as a flexibility imparting agent for the coating film.

In order to further increase the crosslinking rate of the water-based paint and the crosslinking density of the coating film, an acid catalyst such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, or Amino blocked products of these sulfonic acids can be used in combination. Further, conventionally known leveling agents, defoamers, lubricants, pigments, and the like can be used in combination.

As a method of applying the water-based paint, known methods such as a roll coating method, a spray coating method, and a brush coating method can be used.

The water-based paint obtained using the water-based paint resin of the present invention is particularly suitable as a paint for cans.

[0049]

The present invention will be described in more detail with reference to the following examples. In Examples and Comparative Examples, “parts” indicates “parts by weight”, and “%” indicates “% by weight”.

Reference Example (1) Synthesis of Copolymer (P-1) A four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube and reflux condenser was charged with 40.0 parts of butyl cellosolve and a hydroxyl value. 112 mg KOH / g of polycaprolactone polyol (PLACCEL21, manufactured by Daicel Chemical Industries, Ltd.)
0) Add 6.0 parts, dissolve and raise the temperature to 130 ° C., then 18.0 parts of ethyl acrylate, 6.0 parts of methacrylic acid, 0.6 parts of monomethyl maleate, n-acrylic acid A mixture consisting of 10.2 parts of butyl, 18.0 parts of styrene, 1.2 parts of 2-hydroxyethyl acrylate and 3.0 parts of t-butyl peroctoate was added dropwise over 5 hours. One hour after the completion of the dropwise addition, 0.2 parts of 2,2'-azobisisobutyronitrile was added, and the mixture was maintained for another 2 hours. Then, the reaction was terminated to obtain a copolymer (P-1).
The viscosity of the obtained copolymer (P-1) solution was Z1 (measured at 25 ° C. with a Gardner-Holdt foam viscometer), and the solid content was 6%.
0.1%, and the acid value of the solid content of the copolymer (P-1) was 7%.
It was 0 mgKOH / g.

(2) Copolymers (P-2) to (P-14)
The same polymerization and operation as in the synthesis of the copolymer (P-1) were carried out except that the raw material composition of the copolymer was as shown in Table 1, and the copolymers (P-2) to (P- 14) was obtained. Table 1 shows the measurement results of the physical properties of the obtained copolymer.

[0052]

[Table 1]

The abbreviations in Table 1 represent the following compounds. PLACCEL210: manufactured by Daicel Chemical Industries, Ltd., polycaprolactone polyol (having a hydroxyl value of 112 mg KO)
H / g, molecular weight 1000) PLACCEL230AL: Daicel Chemical Industries, Ltd.
Polycaprolactone polyol (hydroxyl value 37mg
PLACCEL303: manufactured by Daicel Chemical Industries, Ltd., polycaprolactone polyol (hydroxyl value 540 mg KO)
H / g, molecular weight 300) Poly THF1000: BASF Japan
Polytetramethylene polyol (having a hydroxyl value of 1)
13 mgKOH / g, molecular weight 1000) Poly THF2000: BASF Japan
Polytetramethylene polyol (having a hydroxyl value of 5)
6 mgKOH / g, molecular weight 2000) BA-10 glycol: manufactured by Japan Emulsifier Co., Ltd., ethylene oxide addition type polyol of bisphenol A (hydroxyl value 170 mgKOH / g, molecular weight 660) BPX-55: manufactured by Asahi Denka Kogyo KK, bisphenol A
Propylene oxide addition type polyol (hydroxyl value 1
43 mgKOH / g, molecular weight 790) Acrylic ester SA: manufactured by Mitsubishi Rayon Co., Ltd., β-methacryloxyethyl acid succinate

Example 1 The above copolymer (P-1) 1
In 00 parts, a methyl etherified benzoguanamine resin (manufactured by Mitsui Cytec Co., Ltd., Mycoat # 106, solid content 7)
53.3 parts by weight of 5% by weight, water-soluble amino resin), 6.7 of 2-dimethylaminoethanol (hereinafter abbreviated as DMAE).
Parts, 3 parts of butyl cellosolve and 47 parts of deionized water, and after stirring well, 40 parts of thinner (composition: deionized water / butyro cellosolve = 70/30) is added so that the solid content of the paint becomes 40%. And adjusted to paint. The appearance of the paint was transparent. This paint was applied on a 0.3 mm-thick aluminum plate with a dry coat to a thickness of 8 to 10 μm using a bar coater, and dried at 200 ° C. in a dry oven at 10 ° C.
Bake for a minute. Table 2 shows the evaluation results of the paint composition and the properties of the obtained paint.

[Examples 2 to 7 and Comparative Examples 1 to 9] In the same manner as in Example 1, coating materials having the compositions shown in Tables 2 and 3 were produced, and the same evaluation as in Example 1 was performed. . Tables 2 and 3 show the obtained evaluation results.

[0056]

[Table 2]

[0057]

[Table 3]

The coating properties shown in Tables 2 and 3 were evaluated by the following methods.

(1) Appearance of Paint The appearance of the paint was visually judged according to the following criteria. ○: good transparency △: slightly cloudy ×: cloudy separation

(2) Paint stability The paint was left in an atmosphere of 60 ° C. for one month, and the appearance was visually judged according to the following criteria. …: Good △: Some cloudiness is observed ×: Separation is observed

(3) Hardness of coating film Measured according to JIS standard using Mitsubishi Pencil Uni.

(4) Adhesion According to the JIS standard, the state of the coated plate after peeling off the cellophane tape was observed and judged according to the following criteria. ◎… Good ○… Slight peeling of coating film
△: considerable peeling of the coating film observed ×: peeled over the entire surface

(5) Impact resistance Using a Dupont impact tester, the evaluation was carried out under the conditions of a 1/2 inch hammer rod, a load of 300 g and a height of 30 cm. Was determined. ◎… Good ○… Slightly cracked coating film
Δ: considerable cracks in the coating film ×: cracks in the entire surface

(6) Retort resistance The coated plate was immersed in hot water at 130 ° C. for 30 minutes using a pressure cooker tester, and the whitening state of the coating film was visually observed and judged according to the following criteria. …: Good ○: very slight whitening is observed △: considerable whitening is observed ×: whitening is observed over the entire surface

[0065]

As is clear from the results of the above examples, the water-based paint containing the water-based paint resin of the present invention has good adhesion to metal, and has good coating film hardness and impact resistance. A well-balanced, water-resistant coating film can be formed and storage stability is excellent, which is very useful industrially.

Claims (6)

[Claims] 1. A polyol compound having two or more hydroxyl groups in a molecule (A), 5 to 50% by weight, a vinyl monomer having a carboxylic acid group (B), 3 to 20% by weight and other copolymerizable compounds. Vinyl monomer (C) 30 to 92% by weight
Water-based paint resin comprising a copolymer obtained by copolymerizing 2. The polyol compound (A) having a hydroxyl value of 10
The water-based paint resin according to claim 1, wherein the resin is a polyol compound having a concentration of from about 600 mgKOH / g. 3. The polyol compound (A) is selected from compounds having a structure represented by the following general formula (I) or (II) in the main chain. The resin for an aqueous coating according to the above. Embedded image (Wherein X is a hydrogen atom or an alkylene group which may contain an ester bond or an ether bond having 20 or less carbon atoms,
Represents an alkenylene group, an arylene group, or a cycloalkylene group, m represents an integer of 3 or more, and a and b represent an integer of 1 or more. ) (Wherein, Y represents a hydrogen atom or an alkylene group which may contain an ester bond or an ether bond having 20 or less carbon atoms,
Represents an alkenylene group, an arylene group, or a cycloalkylene group, n represents an integer of 3 or more, and c and d represent an integer of 1 or more. ) 4. The polyol compound (A) has a molecular weight of 500.
The resin for water-based paint according to claim 1, wherein the resin is at least one selected from polycaprolactone polyol, polybutyrolactone polyol, and polytetramethylene polyol which may contain 0 or less ester bond or ether bond. 5. . 5. The vinyl monomer (B) is represented by the following general formula (II)
The water-based paint resin according to claim 1, wherein the resin is selected from I) and a compound represented by the following general formula (IV). (R ² ) CH ＝ C (R ¹ ) COOH (III) wherein R ¹ represents a hydrogen atom or a methyl group or a carboxymethyl group, and R ² represents a hydrogen atom or —COOR
³ represents an oxygen atom-containing hydrocarbon substituent represented by ³ (R ³ represents a hydrogen atom or a hydrocarbon substituent having 1 to 10 carbon atoms). ] Embedded image CH ₂ = C (R ⁴⁾ in ^{COO-R 5 -COOH (IV)} [ wherein, R ⁴ represents a hydrogen atom or a methyl group, R ⁵
Is -R ^6- (R ⁶ represents a linear or branched alkylene group having 1 to 3 carbon atoms), and a compound represented by the following formula (V): (Wherein, R ⁷ represents a linear or branched alkylene group having 1 to 10 carbon atoms, and R ⁸ represents a linear or branched alkylene group or alkenylene group having 2 to 10 carbon atoms, or a carboxyl group. Or an arylene group or a cycloalkylene group which may be substituted with a halogen atom.) Or the following formula (VI): (Wherein, R ⁹ represents a linear or branched alkylene group having 1 to 10 carbon atoms; m represents an integer of 4 to 6;
¹⁰ represents a linear or branched alkylene group or alkenylene group having 2 to ¹⁰ carbon atoms, or an arylene group or cycloalkylene group optionally substituted with a carboxyl group or a halogen atom, and n is an integer of 1 to 6 Represents ) Represents a hydrocarbon substituent having the structure represented by or a hydrocarbon substituent substituted with a hetero atom. ) 6. An aqueous coating composition comprising 10 to 150 parts by weight of a water-soluble amino resin per 100 parts by weight of the resin for aqueous coating composition according to claim 1.