JPS6045212B2 - epoxy resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an epoxy resin composition, and particularly to an epoxy resin composition that is fast-curing, has storage stability, and is capable of producing a transparent cured product with excellent moisture resistance.

Conventionally, various curing agents for epoxy resin molding materials have been put to practical use, and representative examples thereof include acid anhydrides and aromatic amines.

However, these curing agents have the disadvantage that they are relatively expensive and the properties of the molding material (storage stability, moisture resistance and transparency of the cured product, etc.) are unsatisfactory. As a result of studying these points, the inventors of the present invention found that epoxy resin-acid anhydride type products have excellent transparency of cured products.
T test (test of leaving in water vapor at 120°C and 2 atmospheres)
It was acknowledged that there is a drawback that the cured product becomes cloudy when subjected to a so-called moisture resistance test. Therefore, as a result of searching for an epoxy resin composition that does not cause such a phenomenon, a system using a phenol novolac resin as a curing agent was found to be
They discovered that it was excellent in CT tests, and further studied moisture resistance, storage stability, etc., and completed the present invention. That is, the object of the present invention is to
The object of the present invention is to provide a resin composition which is mainly composed of a phenol novolac resin curing agent and can produce a transparent cured product having particularly excellent moisture resistance.

To summarize the present invention, the epoxy resin composition of the present invention comprises two or more epoxy resins, phenol novolak resin, triethylammonium tetraphenylborate, and imidazole compounds in one molecule, and the phenol novolak resin, It is characterized by blending triethylammonium, tetraphenylborate, and imidazole-based compounds as a mixture that has been heated and melted in advance.

The present inventors selected and added triethylammonium tetraphenylfolate (hereinafter abbreviated as TEA-K), which is excellent as a latent curing accelerator, to the main component of an epoxy resin-phenol novolak resin curing agent system. A cured product of the composition was prepared and its transparency was examined.

This cured product is a composition using other known latent curing accelerators such as tetraphenylphosphonium tetraphenylborate (TPP-K) or tetraphenylarsonium tetraphenylborate (TPA-K). Although its transparency is superior to that of cured products, it is somewhat inferior to cured products of compositions using acid anhydrides such as hexahydrophthalic anhydride as a curing agent, and is slightly cloudy. The reason for this is thought to be the poor compatibility between 'IEA-K and the epoxy resin-phenol novolak resin curing agent system. Therefore, as a result of further research to improve the compatibility between the two, the present invention was completed. According to the present invention, a transparent mixture obtained by heating and melting a phenol novolac resin, TEA-K, and an imidazole compound in advance is blended with an epoxy resin, and this is cured to obtain a cured product with good transparency. I can do it.

Moreover, the cured product obtained in this way has excellent moisture resistance, and remains white even after 100 hours according to the PCT test (test of transparency after being left in water vapor at 120'Cl2 atmospheres for a long time). Does not give rise to Shu. In the present invention, since TEA-K1, which improves the pot life, and imidazole compounds, which improve heat resistance, are used, the composition of the present invention has good storage stability. 1
It is suitable for transfer molding at 80°C.

The epoxy resin in the present invention is not particularly limited, and a wide range of known epoxy compounds can be used. Examples of such resins include polyesters such as bisphenol A1, halogenated bisphenol A1, catechol, resorcinol, etc. Polyglycidyl ether or polyglycidyl ester obtained by reacting a polyhydric phenol or a polyhydric alcohol such as glycerin with Epica rehydrin in the presence of a basic catalyst, and a polyglycidyl ester obtained by condensing a novolak type phenolic resin with Epica rehydrin. epoxy novolak, epoxidized olefin epoxidized by peroxidation method, epoxidized polybutadiene, cyclopentadiene oxide, epoxidized vegetable oil, etc., and furthermore, vinyl cyclohexene dioxide, dipentene dioxide, 2,2-bis(3,4 - epoxy resins such as cyclohexane oxide derivatives such as epoxycyclobenzyl) ether or dicyclobentadiene oxide.

In addition, the phenol novolak resin in the present invention includes:
Products obtained by reacting and dehydrating one or more mixtures of phenol, cresol, xylenol, resorcinol, chlorophenol, phenylphenol, bisphenol, etc. with formaldehyde or paraformaldehyde using an acid, base, or neutral salt as a catalyst. is valid.

The blending ratio of these curing agents to the epoxy resin is suitably 0.5 to 1.5 equivalents per equivalent of the epoxy resin, but most preferably 0.8 to 1.3 equivalents. Moreover, no matter which side the compounding ratio is shifted from, a sufficient cured product cannot be obtained. Examples of imidazole compounds in the present invention include 1-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 4-butyl-5-ethylimidazole, 2-cyclohexyl-4-
Methylimidazole, 2-butoxy-4-allylimidazole, 2-carboethoxybutyl-4-methylimidazole, 2-octyl-4-hexylimidazole, 2
1-ethyl-4-phenylimidazole, 2-phenylimidazole, 2-heptadecylimidazole, 1-benzy-2-methylimidazole, 1-cyanoethyl-2
- Methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole and the tertiary nitrogen in these imidazole rings were formed with trimellitic acid. There are derivatives of imidazole compounds, derivatives of imidazole compounds modified with dicyandiamide, and the like.

Among these, especially 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole,
When 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, etc. are added and melted into a mixture of phenolic novolac resin and TEA-K, the ternary mixture easily becomes transparent. That is, this three-component mixture becomes transparent by heating at 100 to 130 DEG C. to melt and mix 5 to 1 particles, and this transparent mixture is cooled to room temperature, pulverized, and blended into an epoxy resin as a powder. In the composition of the present invention, higher fatty acids such as stearic acid, natural wax, synthetic wax, etc. can be added as needed.

Inorganic fillers such as surface coupling agents, dyes and transparent glass powders can also be added. Next, the present invention will be explained in detail with reference to examples, but the present invention is not limited by these in any way.

Examples 1-5 Each component was prepared in the following composition ratio.

(a) Cresol novolak type epoxy resin (epoxy equivalent: 225: EOCNlO2 manufactured by Nippon Kayaku Co., Ltd.) 8 parts (b
) Bisphenol A type epoxy resin (epoxy equivalent: 18
0: Ciel E828) 2 weighing parts (c)
Phenol novolak resin curing agent (molecular weight 800)
5 parts by weight (d) Triethylammonium tetraphenylborate (TEA-K) 4 parts by weight (e) Imidazole compound 0.5 to 1 part by weight (f) Stearic acid 2 parts by weight (g) Epoxysilane (Shin-Etsu Chemical KBM4O3)
2 parts by weight The above imidazole compounds include 2-ethylimidazole, 2-undecylimidazole, 2-
Heptadecyl imidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole were used (see table).

The above imidazole compound was heated and melt-mixed with the phenol novolac resin curing agent (c) and TEA-K (d) at a temperature of 100 to 130° C. for 10 minutes using a heating extractor.

These were kneaded together with the other components of the above composition in an 8-inch mixing roll machine at 50 to 80°C for 10 to 1 powder,
An epoxy resin molding material was obtained. For these molding materials, under molding conditions of 150℃ and 40kg/Cm, diameter 50T
1rm1 thickness 2? A test piece was transfer molded using a disk mold, and the time required to take out the test piece from the mold, the so-called molding time (minutes), was determined. The shorter the molding time, the better the curability. Further, the specimens prepared under the above molding conditions were cured at 150° C. for 5 hours, and then their transparency was examined.
As a guideline, transparency is the transmittance of light with a wavelength of 500n1μ (
%). Moisture resistance was evaluated by the transparency after leaving the sample in water vapor at 120'Cl2 atmospheres for 10C@. Furthermore, the storage stability of these molding materials makes them 40'
The sample was left in a constant temperature bath of C, and the spiral flow (fluidity) decreased by 10% of the initial value. The longer this time, the better the storage stability. The results thus obtained are shown in the table below. Comparative Examples 1 and 2 Using the same components as in Examples 2 and 3, (c), (d)
and (e) without pre-mixing and melting.
The mixture was then kneaded using a mixing roll machine under the same conditions as in Example 1 to obtain an epoxy resin molding material, and the same experiment as in Example was conducted.

The results are shown in the table below. Next, the results of comparative tests conducted on molding materials for conventional molds are shown as Comparative Examples 3 and 4.

Comparative examples 3 and 4 The composition was as follows.

Comparative Example 3 (a) Cresol novolac type epoxy resin (epoxy equivalent: 235: Ciba Geigy ECN1299) 10 parts by weight (b) Phenol novolac resin curing agent (molecular weight 800)
5 parts by weight θ (c) 2-undecylimidazole 3 parts by weight (d) Stearic acid
2 parts by weight (e) Epoxysilane (KBM manufactured by Shin-Etsu Chemical Co., Ltd.
4O3) 2 parts by weight Comparative Example 4 (
a) Cresol novolac type epoxy resin (epoxy equivalent 235: ECNl299 manufactured by Ciba Geigy) 10 parts by weight (b) Tetrahydrophthalic anhydride 55 parts by weight (c) Benzalkonium chloride (M2lOO manufactured by NOF Corporation)
3 parts by weight (d) stearic acid
2 parts by weight Each of the above components was roll-kneaded in the same manner as in the Examples to prepare an epoxy resin molding material, and the same tests as in the Examples were conducted.

The results are shown in the table below. As is clear from the above results, the phenol novolak resin curing agent, T
The epoxy resin molding material obtained by heating and melt-mixing the three components of EA-K and imidazole-based compounds in advance and adding them to the epoxy resin has a molecular weight of 150 to 180.
It has a fast curing property that allows it to be molded within 3 minutes at 40°C, and has excellent storage stability with very little loss of fluidity even when left at a high temperature of 40°C.

Moreover, these cured products have good transparency and are excellent in being able to withstand a severe moisture resistance test in which they are left in water vapor at 120° C. and 2 atm. As described above, the composition of the present invention is an epoxy resin composition that is fast-curing, has storage stability, and is capable of producing a transparent cured product with excellent moisture resistance.
In particular, it has high utility value as a transfer molding material, and its application fields are extremely wide.

Claims (1)

[Scope of Claims] 1. An epoxy resin having two or more epoxy groups in one molecule, a phenol novolak resin, triethylammonium tetraphenylborate, and an imidazole compound, and the phenol novolak resin, triethylammonium tetraphenyl An epoxy resin composition characterized in that a borate and an imidazole compound are blended as a mixture that has been heated and melted in advance. 2. Claim 1, wherein the imidazole compound is 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1-cyanoethyl-2-methylimidazole, or 1-cyanoethyl-2-undecylimidazole. Compositions as described.