JPH0570559A - Curable resin composition - Google Patents

Abstract

PURPOSE:To provide a new thermally curable resin compsn. which exhibits a good adhesion to a substrate such as metal, scarcely any coloration, and a decreased change with time. CONSTITUTION:A curable resin compsn. which is useful as a coating compsn. excellent in coloration resistance and adhesiveness is prepd. by compounding 5-80wt.% (solid base) partially esterified epoxy resin obtd. by reacting an epoxy resin having an epoxy equivalent of 150-10,000 and at least 1.0 glycidyl group on average in the molecule, a compd. having an alcoholic hydroxyl group in the molecule, and an aliph. linear polycarboxilic anhydride with 95-20wt.% (solid base) resin and/or compd. having a thermally cross-linkable group.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermosetting resin composition. More specifically, the present invention relates to a resin composition for coatings, which exhibits good adhesion to a substrate such as a metal and gives a cured film having good water resistance.

[0002]

2. Description of the Related Art In recent years, water-based paints have been desired from the viewpoint of resource saving and environmental protection. Water-based acrylic resin, water-based polyester resin, as film forming resin for metal coating
It is widely known to use an aqueous epoxy resin or melamine as a curing agent. Water-based acrylic and water-based polyester resins that are commonly used are those that have a carboxyl group introduced into the resin skeleton and are neutralized with a tertiary amine to achieve water solubility and water resistance of the cured coating film. is there. In addition, an epoxy resin is usually used together in order to impart sufficient base material adhesion to the film. Although many examples of using an epoxy resin as a resin for water-based coatings are known, in particular, a glycidyl group is modified with a secondary amine or phosphoric acid, and then neutralized with an appropriate counter ion to be water-solubilized to obtain a modification. Epoxy resins are known to be effective in improving adhesion.

[0003]

When a modified epoxy resin as described above is incorporated into a paint as an adhesion-imparting component, a cured film having good adhesion can be obtained, but the storage stability of the paint and the modified resin There was a problem with the coloring of the solution. For example, when the glycidyl group in the epoxy resin is modified with a secondary amine, a water-soluble epoxy resin can be obtained by quaternary salting with an appropriate anion, but the resulting modified epoxy resin solution is colored brown. It is known that this coloring not only occurs but also progresses further by the heating effect treatment, and when it is applied to a clear paint or a light color paint, a problem may occur in the color tone. Further, when such a modified epoxy is used, the storage stability of the paint may be poor. That is, there are cases where the viscosity is increased during the ordinary pot life test, and the adhesion of the cured film is not expressed.

As a result of intensive studies to solve the above problems, the inventors of the present invention have shown novel adhesion with good substrate adhesion, almost no coloration, and a new heating with a reduced change over time. The present invention has led to the completion of the present invention by finding out a curable resin composition.

[0005]

The present invention provides the following compositions in order to solve the above problems. That is, (a) epoxy equivalent is 150 to
An epoxy resin having an average of 1.0 or more glycidyl groups in the molecule at 10,000, (b) a compound having an alcoholic hydroxyl group in the molecule, (c) an aliphatic linear polyanhydride,
5 to 80% by weight of the partially esterified epoxy resin (A), which is a reaction product of the above, and a resin and / or compound (B) containing a functional group curable by heating, in the solid content of 2%.
The curable resin composition containing 0 to 95% by weight, and the partially esterified epoxy resin (A) are used in an amount of 0.
A resin and / or compound having an alcoholic hydroxyl group in the molecule of 05 to 1 mol, and an amount of 0.05 to 1 mol of an acid anhydride group with respect to 1 mol of the glycidyl group in the epoxy resin (a). The curable resin composition described above is characterized by being partially esterified with an aliphatic linear polyanhydride.

The epoxy resin (a) used in the present invention has no limitation other than the epoxy equivalent described later, and examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin and novolac type. A so-called glycidyl ether-based epoxy resin such as an epoxy resin can be used, but is not limited thereto. Among these epoxy resins, an epoxy resin having an epoxy equivalent of 150 to 10,000 can be used, but an epoxy resin having an appropriate epoxy equivalent should be appropriately selected depending on the viscosity required for the coating material. As the epoxy resin, a commercially available epoxy resin can be used as it is, or can be used alone or as a mixture of two or more kinds.

The compound (b) having an alcoholic hydroxyl group in the molecule used in the present invention includes alcohols exemplified by methanol, ethanol, propyl alcohol, butanol, amyl alcohol, cyclohexanol and the like. It is possible to use cellosolves exemplified by ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, etc., but not limited thereto. These compounds having an alcoholic hydroxyl group can be used alone or as a mixture of two or more kinds. Hereinafter, the above-mentioned "compound having an alcoholic hydroxyl group in the molecule" is referred to as "alcohols".

As the aliphatic linear polyanhydride (c) used in the present invention, polyadipic anhydride, polyazelaic anhydride, polysebacic anhydride and the like can be used as an example. It is not limited to these. These can be used alone or as a mixture of two or more kinds, and if necessary, other aromatic acid anhydrides, cycloaliphatic acid anhydrides and the like can be used in combination.

The partially esterified epoxy resin (A) which characterizes the present invention can be obtained as a reaction product of these, and in general, a tertiary amine catalyst or the like is used in these reactions to accelerate the reaction. I can do things. The compounding amount of the acid anhydride and the alcohols to be reacted with the epoxy resin is from 0.05 to 1 mol of glycidyl group.
It is preferable to react 1 mol of the acid anhydride and the acid mol with the equimolar alcohols. If the amount is less than 0.05 mol, sufficient adhesion to the substrate cannot be obtained. On the other hand, if the amount is more than 1 mol, a free half-esterified product is produced, and thus the water resistance of the obtained film may be lowered.

This reaction is usually carried out in a suitable solvent, but if there is no particular problem, it is convenient to carry out the reaction in the alcohol used in the reaction. Usually, the temperature at which the reaction proceeds is preferably set in the range of 50 to 150 ° C. If the reaction temperature is lower than this range, the reaction proceeds slowly, which is not practical. On the other hand, if the reaction temperature is higher than this range, the epoxy resin tends to have a high molecular weight and gelation may occur, which is not preferable. The partial esterification reaction of the epoxy resin ends when the acid value becomes almost zero.

The partially esterified epoxy resin thus obtained is a solid ester component of other film-forming resin components,
It can be contained in an amount of 5 to 80% by weight. If the blending amount is less than 5% by weight, it is not preferable because sufficient adhesion cannot be imparted to the cured film, and the blending amount is 80% by weight.
If it is more than the above, the curing of the film becomes insufficient and the cured product characteristics,
For example, surface hardness, water resistance, solvent resistance, etc. may be insufficient, which is not preferable.

The above-mentioned resin and / or compound (B) containing a functional group that can be cured by heating are not particularly limited, but examples thereof include water-soluble acrylic resin, water-soluble polyester resin, aminoplasts, water-soluble alkyd resin and the like. Can be used. These are appropriately selected and used according to the desired properties of the cured product. The curable resin composition of the present invention includes, in addition to the film-forming resin component described above, various solvents for improving coatability, an antioxidant, an ultraviolet absorber, a curing agent, a lubricity imparting agent, a pigment.・ Various additives such as colorants such as dyes can be added. The method for coating the curable resin composition of the present invention is not particularly limited, and roll coating, spray coating, dip coating, brush coating and the like can be applied. The curable resin composition of the present invention can be cured under a temperature range of about 150 to 250 ° C. for about 10 seconds to 10 minutes.

[0013]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. In addition,
In the examples, all "parts" represent parts by weight.

Example 1 Bisphenol A diglycidyl ether type epoxy resin (Epicoat 1007 manufactured by Yuka Shell Epoxy Co., Ltd.) 790 having an epoxy equivalent of 1950 was placed in a reaction vessel equipped with a stirrer.
Part, polyazelaic anhydride (PAZ manufactured by Shin Nippon Rika Co., Ltd.
-90) 75 parts and 800 parts of ethylene glycol monobutyl ether are put and the temperature is raised to about 120 ° C. to dissolve the epoxy resin and the acid anhydride. When completely dissolved, 1.73 parts of dimethylbenzylamine is added as a catalyst and the reaction is continued at this temperature for about 6 hours to make the acid value 2 or less. To the resulting modified epoxy resin solution, 883 parts of solid content of water-soluble acrylic (triethylamine neutralized product of John Cryl 587 manufactured by Johnson Polymer Co., Ltd.) and 400 parts of solid content of water-soluble melamine resin (Cymel 303 manufactured by Mitsui Cyanamid Co., Ltd.) were added. Then, purified water was added so that the nonvolatile content was 50% by weight to obtain a resin solution.

A cured film physical property test of the obtained resin solution was conducted, and the results are shown in Table 1. For the adhesion test, a cellophane tape peeling test was performed, and the number of squares remaining without peeling was displayed among 100 squares of 1 × 1 mm. In the water resistance test, the state of the film was visually observed by immersing it in boiling water for 30 minutes. A roll coater is used for coating, and the dry coating thickness is 1
Apply to tin-plated steel sheet to 0 μm, and 200 ℃
Baking was performed for 5 minutes.

Example 2 A reaction vessel equipped with a stirrer was charged with 690 parts of a bisphenol A diglycidyl ether type epoxy resin (Epicoat 1004 manufactured by Yuka Shell Epoxy Co., Ltd.) having an epoxy equivalent of 950.
42 parts of polyazelaic acid anhydride and 500 parts of ethylene glycol monobutyl ether are added and the temperature is raised to about 100 ° C. to dissolve the epoxy resin and the acid anhydride. When completely dissolved, 1.50 parts of dimethylbenzylamine is added as a catalyst, the temperature is maintained and the reaction is continued for about 6 hours to adjust the acid value to 2 or less. The obtained modified epoxy resin solution had a solid content of 300 of a water-soluble acrylic resin (triethylamine neutralized product of John Cryl 587 manufactured by Johnson Polymer Co., Ltd.).
Parts, water-soluble melamine resin (Cymel 303 manufactured by Mitsui Cyanamid Co., Ltd.) and a solid content of 300 parts were added, and purified water was added so that the nonvolatile content was 50% by weight to obtain a resin solution.

The cured resin physical properties of the resin solution thus obtained were tested, and the results are shown in Table 1. For the adhesion test, a cellophane tape peeling test was performed, and the number of squares remaining without peeling was displayed among 100 squares of 1 × 1 mm. In the water resistance test, the state of the film was visually observed by immersing it in boiling water for 30 minutes. A roll coater is used for coating, and the dry coating thickness is 1
Apply to tin-plated steel sheet to 0 μm, and 200 ℃
Baking was performed for 5 minutes.

Example 3 In a reaction vessel equipped with a stirrer, 566 parts of a bisphenol A diglycidyl ether type epoxy resin having an epoxy equivalent of 470 (Epicoat 1001 manufactured by Yuka Shell Epoxy Co., Ltd.),
19 parts of polyazelaic anhydride and 300 parts of n-butyl alcohol are added and the temperature is raised to about 100 ° C. to dissolve the epoxy resin and the acid anhydride. When completely dissolved, 1.20 parts of dimethylbenzylamine is added as a catalyst, the reaction is continued for about 6 hours while maintaining this temperature, and the acid value is adjusted to 2 or less.
122 parts of solid content of water-soluble acrylic resin (triethylamine neutralized product of John Cryl 587 manufactured by Johnson Polymer Co., Ltd.) and 230 parts of solid content of water-soluble melamine resin (Cymel 303 manufactured by Mitsui Cyanamid Co., Ltd.) were added to the resulting modified epoxy resin solution. Then, purified water was added so that the nonvolatile content became 50% by weight to obtain a resin solution.

A cured film physical property test of the obtained resin solution was conducted, and the results are shown in Table 1. For the adhesion test, a cellophane tape peeling test was performed, and the number of squares remaining without peeling was displayed among 100 squares of 1 × 1 mm. In the water resistance test, the state of the film was visually observed by immersing it in boiling water for 30 minutes. A roll coater is used for coating, and the dry coating thickness is 1
Apply to tin-plated steel sheet to 0 μm, and 200 ℃
Baking was performed for 5 minutes.

Comparative Example 1 566 parts of a bisphenol A diglycidyl ether type epoxy resin (Epicoat 1001 manufactured by Yuka Shell Epoxy Co., Ltd.) having an epoxy equivalent of 470 was placed in a reaction vessel equipped with a stirrer.
Add 19 parts of polyazelaic anhydride and raise the temperature to about 90 ° C. to melt mix the epoxy resin and the acid anhydride. Once homogeneous, dimethylbenzylamine 1.20 as catalyst
When the temperature was maintained and the reaction was continued for about 3 hours, the viscosity increased and stirring became impossible.

Comparative Example 2 A reaction vessel equipped with a stirrer was charged with a solid content of 122 parts of a water-soluble acrylic resin (triethylamine neutralized product of John Cryl 587 manufactured by Johnson Polymer Co., Ltd.) and a water-soluble melamine resin (Cymel 303 manufactured by Mitsui Cyanamid Co., Ltd.). Solid content 23
0 parts was added, and purified water was added so that the nonvolatile content became 50% by weight to obtain a resin solution.

A cured film physical property test of the obtained resin solution was conducted, and the results are shown in Table 1. For the adhesion test, a cellophane tape peeling test was performed, and the number of squares remaining without peeling was displayed among 100 squares of 1 × 1 mm. In the water resistance test, the state of the film was visually observed by immersing it in boiling water for 30 minutes. A roll coater is used for coating, and the dry coating thickness is 1
Apply to tin-plated steel sheet to 0 μm, and 200 ℃
Baking was performed for 5 minutes.

Comparative Example 3 In a reaction vessel equipped with a stirrer, 566 parts of a bisphenol A diglycidyl ether type epoxy resin (Epicoat 1001 manufactured by Yuka Shell Epoxy Co., Ltd.) having an epoxy equivalent of 470,
Add 500 parts of ethylene glycol monobutyl ether and raise the temperature to about 80 ° C. to dissolve the epoxy resin. When completely dissolved, 50 parts of diethanolamine was added, the reaction was continued at this temperature for about 6 hours, and after cooling, 28 parts of acetic acid was added. A water-soluble acrylic resin (John Cryl 5 manufactured by Johnson Polymer Co., Ltd.) was added to the resulting modified epoxy resin solution.
87 of triethylamine neutralized product), 630 parts of solid content, 400 parts of solid content of water-soluble melamine resin (Cymel 303 manufactured by Mitsui Cyanamid Co., Ltd.) were added, and purified water was added so that the nonvolatile content became 50% by weight. A resin solution was obtained.

The cured resin physical properties of the resin solution thus obtained were tested, and the results are shown in Table 1. For the adhesion test, a cellophane tape peeling test was performed, and the number of squares remaining without peeling was displayed among 100 squares of 1 × 1 mm. In the water resistance test, the state of the film was visually observed by immersing it in boiling water for 30 minutes. A roll coater is used for coating, and the dry coating thickness is 1
Apply to tin-plated steel sheet to 0 μm, and 200 ℃
Baking was performed for 5 minutes.

[0025]

[Table 1]

[0026]

INDUSTRIAL APPLICABILITY The present invention relates to a curable resin composition containing an acid anhydride and an epoxy resin modified with a compound having an alcoholic hydroxyl group in the molecule. It can be suitably used as a coating resin composition having excellent adhesion.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Tadashi Nakamura 2-3-13 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd. (72) Masako Yamamoto 2-3-13 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. The epoxy equivalent (a) is 150 to 1000.
A reaction product of an epoxy resin having an average of 1.0 or more glycidyl groups in the molecule at 0, (b) a compound having an alcoholic hydroxyl group in the molecule, and (c) an aliphatic linear polyanhydride. Partially esterified epoxy resin (A) in solid content 5
20 to 95% by weight of a resin and / or compound (B) containing a functional group curable by heating,
A curable resin composition, characterized in that the curable resin composition is contained by weight%. 2. The partially esterified epoxy resin (A) comprises
Resin and / or compound having 0.05 to 1 mol of an alcoholic hydroxyl group in the molecule with respect to 1 mol of the glycidyl group in the epoxy resin, and 1 mol of the glycidyl group in the epoxy resin (a) 2. The curable resin composition according to claim 1, wherein the curable resin composition is partially esterified with an amount of an aliphatic linear polyanhydride having an acid anhydride group of 0.05 to 1 mol. ..