JPH11293187A - Epoxy resin-based coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin-based coating composition containing no hardening accelerator, excellent in hardenability in a low temperature region [150 deg.C], providing a colorless transparent coating membrane after hardening and excellent in close adhesion to metal. SOLUTION: This epoxy resin-based coating composition comprises an epoxy resin having >=2 epoxy groups in a molecule in average, 1,3,5-tris(2-carboxyethyl) isocyanurate as a hardening agent, and an organic solvent having 8.0-13.0 solubility parameter. The ratio of the compounded epoxy resin and the hardening agent is regulated so as to be 0.5-4.0 expressed in terms of the equivalent ratio of the epoxy group/the carboxy group, and the amount of the compounded organic solvent is regulated so as to be 10-500 wt.% based on the total amount of the epoxy resin and the hardening agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin system capable of obtaining a coating film having a high curing speed at low temperatures, a colorless and transparent appearance of the cured coating film, and an excellent adhesion to metal. The present invention relates to a coating composition.

[0002]

2. Description of the Related Art Epoxy resin compositions are used in various fields because a cured product having excellent electrical, mechanical and thermal properties can be easily obtained by combining various epoxy resins with a curing agent. Have been. Usually, the epoxy resin composition uses an epoxy resin prepolymer having two or more epoxy groups in a molecule, a curing agent, and various curing accelerators as catalysts for the purpose of accelerating curing.

However, when a conventionally known epoxy resin-based coating composition is cured at a high temperature (for example, 180 ° C.) in a short time, a tertiary amine, It was necessary to improve the curability by adding an imidazole derivative or the like.

When such an epoxy resin-based coating composition is cured in a high-temperature region, a large amount of heat is generated during the curing due to the use of a curing accelerator, and as a result, the cured coating film is colored, and is thus colorless and transparent. It could not be used in areas requiring a coating. In addition, this type of epoxy resin composition,
The storage stability at room temperature was extremely poor, and had to be stored in a refrigerator.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the curing speed is increased to about 150 ° C. without using a curing accelerator such as a tertiary amine or an imidazole derivative in an epoxy resin-based coating composition. The present invention provides an epoxy resin-based coating composition in which a sufficient curing reaction occurs even when the temperature is lowered to a level, and the cured epoxy resin coating film is colorless and transparent, and a cured product having excellent adhesion to metal can be obtained. As an issue.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted a number of tests to solve this problem, and as a result, have obtained a cured epoxy resin having an average of two or more epoxy groups in one molecule. Using 1,3,5-tris (2-carboxyethyl) isocyanurate as an agent and an organic solvent having a solubility parameter in the range of 8.0 to 13.0, the compounding ratio of the epoxy resin and the curing agent was determined by using an epoxy group. / Equivalent ratio of carboxyl group is in the range of 0.5 to 4.0, and the compounding ratio of the organic solvent is 10 to 5 with respect to the sum of the epoxy resin and the curing agent.
It has been found that the desired coating composition can be obtained by adjusting the content to 00% by weight, preferably 20 to 100% by weight, and the present invention has been completed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin used in the practice of the present invention is not particularly limited, but may be any resin having an average of two or more epoxy groups per molecule. Representative epoxy resins include polyphenols such as bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AD epoxy resin, epoxy resin having hydantoin type, triglycidyl isocyanurate, catechol, resorcinol and the like, or glycerin. Polyglycidyl ether obtained by reacting polychlorohydrin with polyhydric alcohol such as polyethylene glycol or polyethylene glycol, or glycidyl ether ester obtained by reacting p-hydroxycarboxylic acid with epichlorohydrin, polycarboxylic acid such as phthalic acid, terephthalic acid, and epichlorohydrin And epoxidized phenol novolak resin, epoxidized polyolefin, water-soluble epoxy resin, Tan-modified epoxy resins and the like, but not limited thereto.

As the organic solvent used in the present invention, a known organic solvent can be used as long as the solubility parameter ranges from 8.0 to 13.0. For example, N, N-dimethylformamide (DMF), N-methyl-2-pyrrolidone, methyl ethyl ketone (MEK) and the like can be mentioned.
It is not limited to these.

In order to prepare the epoxy resin-based coating composition of the present invention, an epoxy resin as a main agent and 1,1 as a curing agent are used.
Desirably, 3,5 tris (2-carboxyethyl) isocyanurate is preliminarily compounded, and finally an organic solvent is added.

The epoxy resin-based coating composition according to the present invention may contain, if necessary, a diluent, a flexibility-imparting agent, a silane-based coupling agent, an antifoaming agent, a leveling agent, a filler, a pigment, a dye, and the like. Various additives can be added.

[0011]

The present invention will be described in detail below with reference to examples and comparative examples. The evaluation methods in these tests were based on the following test standards and conditions. Gel time: JIS C-2105 [Hot plate method (150
° C)] Pot life: JIS K-6838 [Time to reach twice the initial viscosity] Appearance of cured product: Visual Erichsen value: JIS K-5400 [Measurement temperature 25]
° C], unit: mm Flex resistance: JIS K-5400 [measuring temperature 25 ° C] DuPont impact value: JIS K-5400 [measuring temperature 2
5 ° C., load 500 g, height 40 cm] Pencil scratching value: JIS K-5400 [measurement temperature 25
° C] Cross-cut test: JIS K-5400 [measuring temperature 25 ° C]

Examples 1 to 8 Triglycidyl isocyanurate (manufactured by Nissan Chemical Industries, Ltd.) was used as an epoxy resin.
Trade name: TEPIC-S, epoxy equivalent 99) 100 parts by weight, as a curing agent, 1,3,3 of the compounding amount shown in Table 1
5-Tris (2-carboxyethyl) isocyanurate [carboxyl group equivalent 115, abbreviated as TCEIC] was weighed in a mortar, and then ground to 10 μm or less using the mortar. The pulverized mixture was transferred to a 300 ml glass beaker. Finally, 200 parts by weight of N, N-dimethylformamide as an organic solvent was added, and the container was sealed with a paraffin film. The mixture was irradiated with ultrasonic waves for 1 minute to obtain a homogeneously dissolved preparation.

Comparative Example 1 As a epoxy resin, 100 parts by weight of triglycidyl isocyanurate (same as in the example) was weighed in a mortar, and pulverized to 10 μm or less using the mortar. The pulverized triglycidyl isocyanurate was transferred to a 300 ml glass beaker, and 200 parts by weight of N, N-dimethylformamide was added as an organic solvent, and the container was sealed with a paraffin film. It was confirmed that a uniform solution was obtained by irradiating ultrasonic waves for 15 minutes by using, and finally, 5.0 parts by weight of 2-ethyl-4-methylimidazole [manufactured by Shikoku Chemicals Co., Ltd., abbreviated as 2E4MZ] was used as a curing agent. And again seal the container with paraffin film,
Ultrasonic irradiation was performed for 15 minutes using an ultrasonic cleaner to obtain a homogeneously dissolved preparation.

The results obtained by examining the curability (gel time) of the epoxy resin at 150 ° C. and the storage stability (pot life) at 25 ° C. of the preparations obtained in Examples and Comparative Examples are shown in Table 1. It was as follows.

[0015]

[Table 1]

The epoxy resin-based coating compositions obtained in Examples 1 to 4 and Comparative Example 1 were uniformly applied to a steel plate with a brush.
After heating and curing in an oven at 50 ° C. for 4 hours, the resin was cut into a predetermined size, and the cured resin was examined for coating film performance. These results are as shown in Table 2, and those shown in Examples are clearly superior to Comparative Examples in physical properties such as cured product appearance, Erichsen value, flex resistance and impact resistance. Was recognized.

[0017]

[Table 2]

[0018]

The epoxy resin-based coating composition according to the present invention has excellent curability in a low temperature range, and the cured coating film is colorless and transparent and has excellent adhesion to metal. The effect of the present invention in the fields of electric insulating materials and the like is extremely large.

Claims (1)

[Claims] 1. An epoxy resin having an average of two or more epoxy groups in one molecule, and 1,3,5-
Tris (2-carboxyethyl) isocyanurate,
And an organic solvent having a solubility parameter in the range of 8.0 to 13.0 as an essential component, and the compounding ratio of the epoxy resin and the curing agent is 0.5 to 4.0 in the equivalent ratio of epoxy group / carboxyl group. And the compounding ratio of the organic solvent is 10 to 500% by weight based on the sum of the epoxy resin and the curing agent.
An epoxy resin-based coating composition, characterized by having the following range.