JPH09176289A - One-pack type epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a one-pack type epoxy resin compsn. excellent in shelf stability at the low-to-medium temp. range and capable of forming a cured product excellent in properties through short-time curing by using a specific compd. as a curing agent. SOLUTION: This one-pack type epoxy resin compsn. contains as a curing agent a salt prepd. from 1mol imidazoline compd. and 1mol aliph. dicarboxylic acid. The salt prepd. from the imidazoline compd. and the aliph dicarboxylic acid, when used alone as the curing agent, is used in an equivalent amt. of 0.15 to 0.80mol per epoxy groups in the epoxy resin compsn. 2-Phenylimidazoline is esp. suitable as the imidazoline compd. Adipic acid is esp. suitable as the aliph. dicarboxylic acid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-pack type epoxy resin composition which has excellent storage stability in the medium and low temperature range and can provide excellent cured product characteristics by curing in a short time. The present invention provides an epoxy resin composition which is excellent in coating applications such as film-fixing resistors, insulating films for electronic parts such as hybrid ICs, and exterior films for metal plates, metal containers, metal tubes and the like.

[0002]

2. Description of the Related Art Epoxy resin cured products having excellent curability with respect to epoxy resin and excellent electrical, mechanical and thermal properties can be obtained by curing in a short time.
Various imidazoline compounds are widely used as curing agents for epoxy resins. For example, 2-phenylimidazoline, which is used as a curing agent for solid epoxy resins, is often used as an epoxy resin curing agent for powder coatings, because a uniform and highly flexible coating film can be obtained by baking for a short time. Has been.

However, when 2-phenylimidazoline is used as an epoxy resin curing agent for powder coatings,
Since 2-phenylimidazoline has a low melting point of 90 to 95 ° C., when a solid epoxy resin is melted and blended with an additive or the like, it easily reacts with the epoxy resin to cause gelation, or an epoxy resin composition is formed. There was a defect such as blocking with the epoxy resin during storage.

Therefore, in order to overcome the drawbacks of poor manufacturing stability and storage stability when 2-phenylimidazoline is used as a curing agent, 2-phenylimidazoline is added with a salt of an aromatic polycarboxylic acid such as trimellitic acid. Although a combined use method has been proposed, although the production stability and storage stability are certainly improved, the compatibility with solid epoxy resin is poor because the melting point of trimellitate salt of 2-phenylimidazoline is high. Moreover, it is difficult to cure unless the temperature is raised to a high temperature of 200 ° C. or higher, and the time required for curing is considerably longer than that in the case of 2-phenylimidazoline alone, and the obtained cured coating film also has flexibility and impact resistance. It was inferior.

On the other hand, in JP-A-58-47064, acid anhydrides, dicyandiamide, dihydrazides such as adipic acid dihydrazide, imidazoline compounds such as 2-phenylimidazoline and imidazole compounds such as 2-methylimidazole are used as curing agents. Epoxy resin powder coating composition using one or a mixture of two or more selected as a curing agent, Japanese Patent Publication No. 1-12310 discloses a dibasic acid such as malonic acid, succinic acid or adipic acid and hydroxyalkyl. Disclosed is a coating composition in which a bisimidazoline compound obtained by reacting with ethylenediamine to amidate and then subjecting it to a ring closure reaction is compounded as a curing agent.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a one-pack type epoxy resin composition which has excellent storage stability in the medium and low temperature range and excellent cured product characteristics by short-time curing. is there.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies as to a curing agent and a curing accelerator for an epoxy resin having improved curing reactivity and excellent storage stability, and as a result, a specific imidazoline compound has been obtained. It was found that a desired one-pack type epoxy resin composition can be obtained by using a salt of carboxylic acid and aliphatic dicarboxylic acid, and completed the present invention.

That is, in the one-pack type epoxy resin composition of the present invention, a salt consisting of 1 mol of an imidazoline compound and 1 mol of an aliphatic dicarboxylic acid is used as a curing agent.
It was possible to provide an epoxy resin composition having a low reactivity with an epoxy resin in a medium to low temperature range of 150 ° C. or lower and an excellent reactivity with an epoxy resin in a high temperature range of 150 ° C. or higher. This epoxy resin composition, compared with a powder coating composition using an imidazoline compound alone as a curing agent,
It is excellent in that it does not cause changes such as changes during preparation of the composition or blocking that occurs when the composition is stored, and the gloss and properties of the cured coating film after curing and baking are also excellent. The same level as in the case of single use of is obtained.

In the present invention, the salt composed of an imidazoline compound and an aliphatic dicarboxylic acid used as a curing agent is shown in Chemical formula 1.

[0010]

Embedded image

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The imidazoline compound used in the practice of the present invention is preferably one having poor solubility in an epoxy resin at room temperature in order to retain its potential in an epoxy resin composition, and its typical 2-methylimidazoline, 2-ethyl-4-
Methyl imidazoline, 2-propyl imidazoline, 2-
Amyl imidazoline, 2-heptyl imidazoline, 2-
Decyl imidazoline, 2-undecyl imidazoline, 2
-Dodecyl imidazoline, 2-tridecyl imidazoline, 2-tetradecyl imidazoline, 2-heptadecyl imidazoline, 2-undecyl-4-methyl imidazoline, 2-heptadecyl-4-methyl imidazoline, etc. 2
Position alkyl imidazoline compounds and 2-phenyl imidazoline compounds, and among them, 2-phenyl imidazoline is particularly preferable, and as the aliphatic dicarboxylic acid to be reacted therewith, malonic acid, oxalic acid, glutaric acid, adipic acid, Pimelic acid and the like, these aliphatic dicarboxylic acids can be used alone or as a mixture of two or more kinds, in view of the reaction with the imidazoline compound, the solubility in the reaction solvent and the solubility to the reaction product is high, Adipic acid, which is also industrially easily available, is particularly preferable.

The salt consisting of an imidazoline compound and an aliphatic dicarboxylic acid used in the practice of the present invention comprises an imidazole compound of 0.
The reaction product obtained by mixing at a mixing ratio of 8 mol to 1.5 mol and reacting by heating and uniformly mixing and dissolving this mixture in the absence of solvent or in the presence of water or various organic solvents After cooling to room temperature, by crushing the product as it is when reacted in the absence of solvent, and by filtering the reaction product when reacted in water or solvent, the desired imidazoline compound And a salt of an aliphatic dicarboxylic acid can be obtained. When the amount of the imidazoline compound becomes larger than the compounding ratio of 1.5 mol upon mixing, the storage stability of the obtained resin composition decreases, and conversely, when the amount of the imidazoline compound becomes less than 0.8 mol, the obtained resin composition. This is not preferable because the curability of the product decreases.

In the practice of the present invention, when a salt of an imidazoline compound and an aliphatic dicarboxylic acid is used as a curing agent for an epoxy resin, it may be used alone or, if necessary, dicyandiamide or an organic amine having active hydrogen. Compounds, organic acid anhydrides, amine salts, quaternary ammonium salts, urea, melamine, guanamines, polycarboxylic acids, phenol resins, polyhydric phenols, cyanamide,
It may be used in combination with another curing agent such as a hydrazine derivative, an organic acid hydrazide or an imidazole compound.

The epoxy resin which is solid at room temperature used in the practice of the present invention can be used as long as it has one or more epoxy groups per molecule on average, and its representative one is bisphenol A. Type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, brominated bisphenol A type epoxy resin, hydridint-in-ring epoxy resin, novolac type epoxy resin and urethane modified epoxy resin.

In the practice of the present invention, when a salt comprising an imidazoline compound and an aliphatic dicarboxylic acid is used alone as a curing agent for an epoxy resin, the compounding ratio is 0. 1 with respect to 1 equivalent of the epoxy group in the epoxy resin composition. 15 ~
The range is 0.80 mol, and preferably the range is 0.2 to 0.4 mol. When other curing agents are used in combination, it is preferable to reduce the addition amount from the above blending ratio.

In the practice of the present invention, as a typical organic amine compound having active hydrogen, which is used in combination with a salt comprising an imidazoline compound and an aliphatic dicarboxylic acid,
Examples include metaphenylenediamine, diaminodiphenylmethane and diaminodiphenylmethane.

As a typical acid anhydride,
Phthalic anhydride, tetrahydrophthalic anhydride, chlorendic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic acid anhydride, 5- (2,5-
Examples thereof include dioxotetrahydrofuryl) -3-methyl-3-cyclohexane-1,2-dicarboxylic acid anhydride, methylcyclohexene dicarboxylic acid anhydride and alkylstyrene maleic anhydride copolymer. Further, if necessary, a color pigment, a plasticizer, a solvent, a reactive diluent, etc. may be added to the epoxy resin composition.

[0018]

The present invention will be described in more detail with reference to the following reference examples, examples and comparative examples, but the present invention is not limited to these examples. The raw materials and evaluation methods used in Examples and Comparative Examples are as follows,
All used parts of raw materials are parts by weight. 2-Phenylimidazoline: Shikoku Kasei Co., Ltd. 2-Methylimidazoline: Shikoku Kasei Co., Ltd. Adipic acid: Wako Pure Chemicals Reagent 2-Phenylimidazoline / trimellitic acid salt: Commercial product Bisphenol A type epoxy resin [trade name: Epicoat 1004, Epoxy equivalent: 875-975] manufactured by Yuka Shell Epoxy Co., Ltd.

The properties of the resins in these examples and comparative examples were measured by the following methods. Gel time: Stroke cure method [according to JIS C-2105 (hot plate method)] Manufacturing stability: 10 g of the epoxy resin composition is heated at a temperature of 120 ° C. for 15 minutes, and the gel time is measured and compared with that before treatment. Storage stability: JIS K-6838 (Epoxy resin composition is stored at a temperature of 40 ° C., the gel time of the composition at 180 ° C. is measured and compared with the initial value.) Blocking state: 30 at a temperature of 40 ° C. State after storage for a day Coating property: After coating on a stainless plate so that the thickness of the coating is about 200 μm and baking at a temperature of 180 ° C. for 10 minutes, measurement is performed according to JIS K-5400.

Reference Example 1 2-Phenylimidazoline
Synthesis of adipic acid salt [molar ratio 1: 1] 146 g of powdery adipic acid in a separable flask
(1.0 mol) and ethanol (1400 ml) are added, and this is stirred and heated to a temperature of 50 ° C. in an oil bath to uniformly dissolve. To this solution was added 146 g (1.0 mol) of powdered 2-phenylimidazoline with stirring,
After stirring for 1 hour, the mixture is cooled to room temperature. The slurry liquid in the flask was filtered to separate the generated crystals, and the crystals were washed with 500 ml of ethanol and then dried at a temperature of 100 ° C. to give white crystalline 2-phenylimidazoline-adipine. 256 g of acid salt [molar ratio 1: 1] (melting point: 148 to 150 ° C., yield: 8
8%).

[Reference Example 2] Synthesis of 2-methylimidazoline adipate [molar ratio 1: 1] 86 g (1.0 mol) of powdery 2-methylimidazoline and 400 m of isopropanol were placed in a separable flask.
1 is added, and this is uniformly dissolved with stirring. 146 g (1.0 mol) of powdery adipic acid was added to this solution with stirring, and the mixture was stirred for 3 hours. The slurry liquid in the flask was filtered to separate the formed crystals,
After washing with 0 ml of ethanol and drying at a temperature of 100 ° C., 213 g of white crystalline 2-phenylimidazoline adipate [molar ratio 1: 1] (melting point: 109-111 ° C., yield: 92) %) Was obtained.

[Reference Example 3] Synthesis of 2-methylimidazoline adipate [molar ratio 2: 1] In a separable flask, 172 g (2.0 mol) of powdery 2-methylimidazoline and 50 parts of isopropanol were added.
Add 0 ml, and dissolve it uniformly while stirring.
146 g (1.0 mol) of adipic acid powder in the solution
Is added with stirring and stirred for a further 3 hours. The formed liquid crystal is separated by filtering the slurry liquid in the flask. This was washed with 500 ml of ethanol and then dried at a temperature of 100 ° C. to give 296 g of white crystalline 2-phenylimidazoline adipate [molar ratio 2: 1] (melting point: 102-119 ° C., Yield: 9
2%).

[Example 1 and Comparative Examples 1 and 2] 2-phenylimidazoline adipate [1: 1] obtained in Reference Example 1 as a curing agent and commercially available 2-phenylimidazoline and 2-phenylimidazoline. A trimellitate salt was used, and each was mixed with Epicoat 1004 at a compounding ratio as shown in Table 1 and then pulverized with a pulverizer to obtain a one-pack type epoxy resin composition. The gel time of the resin composition thus obtained, the production stability at 120 ° C. and the storage stability in an environment of 40 ° C., and the characteristic results of the cured coating film obtained after curing the resin composition are , As shown in Table 1.

[0024]

[Table 1]

[Examples 2 to 3 and Comparative Example 3] 2-phenylimidazoline adipate [1: 1] and 2-methylimidazoline adipate [1] obtained in Reference Examples 1 to 3 as curing agents. : 1] and 2-phenylimidazoline adipate [2: 1] are mixed in Epicoat 1004 at the compounding ratios shown in Table 2 and then crushed using a crusher to prepare a one-pack type. An epoxy resin composition was obtained. The gel time, the production stability at 120 ° C. and the storage stability under an environment of 40 ° C. of the resin composition thus obtained were as shown in Table 2.

[0026]

[Table 2]

[0027]

The one-pack type epoxy resin composition of the present invention is
Since it has excellent storage stability and excellent characteristics of the coating film after curing, it is useful as a powder coating material, an electrical insulating material, a liquid coating material and the like.

Claims (2)

[Claims] 1. A one-pack type epoxy resin composition containing a salt of 1 mol of an imidazoline compound and 1 mol of an aliphatic dicarboxylic acid as a curing agent. 2. A one-pack type epoxy resin composition comprising a salt consisting of 1 mol of 2-phenylimidazoline and 1 mol of adipic acid as a curing agent.