Process for preparation of alicyclic diepoxy compound, curable epoxy resin compositions, epoxy resin compositions for the encapsulation of electronic components, stabilizers for electrical insulating oils, and casting epoxy resin compositions for electrical insulation

Abstract

According to the present invention (1), an alicyclic diepoxy compound represented by the following general formula (I): can be produced in high purity and high yields at low cost, by epoxidizing the corresponding alicyclic diolefin compound with an organic percarboxylic acid. As the alicyclic diepoxy compound lacks an ester group in the molecule, it will show high reactivity for a cationic catalyst. Besides, when it is used as a curable epoxy resin composition of the present invention (2), it will show an effect of lowering its curing temperature or reducing its curing time. The curable epoxy resin composition has high reactivity for various curing agents, low viscosity, and excellent workability. Moreover, the curable resin composition is also superior in that it has less effect to working surroundings, and a cured product thereof shows useful physical properties for the uses in coatings, ink, adhesives, sealants, encapsulants, and the like. Furthermore, as a resin composition of the present invention (3) shows a low coefficient of water absorption, it is of extremely high quality as an epoxy resin composition for the encapsulation of electronic parts. In addition, a stabilizer for an electrical insulating oil of the present invention (4) (i.e., the alicyclic diepoxy compound or an electrical insulating oil containing such a compound) is low in acid value, and the stabilizer improves the properties of the insulating oil. In addition, a cured product obtained by curing a casting epoxy resin composition for electrical insulation of the present invention (5) has excellent properties such as high bending strength, high Tg, and low permittivity.

Description

TECHNICAL FIELD [0001] The present invention relates to a process for preparation of an alicyclic diepoxy compound in which an unsaturated group-containing compound having a bicyclohexyl-3,3′-diene skeleton is reacted with an organic percarboxylic acid. In addition, the present invention relates to a curable resin composition having such the diepoxy compound as an essential ingredient and to a cured product thereof. The resin composition is useful in various fields including applications such as coatings, ink, adhesives, sealants, and encapsulating materials. Moreover, the present invention relates to an epoxy resin composition for encapsulating electronic parts such as a semiconductor, the epoxy resin composition containing the above alicyclic diepoxy compound as an essential ingredient and showing high moisture-resistance and high fluidity. Moreover, the present invention relates to a stabilizer for an electrical insulating oil and an electrical insulating oil. More particularly, ...

AI Technical Summary

Benefits of technology

[0033] An object of the present invention (1) is to provide a process for preparation of a less viscous and easily manageable alicyclic diepoxy compound without an ester group in the molecule, which has improved safeness, is economical, and gives environmental consideration.

[0034] In addition, an object of the present invention (2) is to provide a curable resin composition having the alicyclic diepoxy compound, an initiator for thermal cationic or photocationic polymerization, or an acid anhydride as essential ingredients and to provide a cured product obtained by hardening the composition, which has higher performance in reactivity to curing as well as in transparency, heat resistance, processibility, safeness in working, and so on, than that of an epoxy compound (resin) conventionally utilized.

[0035] Moreover, an object of the present invention (3) is to provide an epoxy resin composition for the encapsulation of electronic parts having high fluidity, good loading properties, and excellent moisture resistance in which the above problems of a resin for encapsulating electronic parts are overcome by blending the alicyclic diepoxy compound represented by the general formula (I) described below. In such an epoxy resin composition, when parts having an electronic circuit such as a semiconductor device are encapsulated, no lead wire is deformed or cut.

Problems solved by technology

If they are used under high temperatures and high moistures or under such a condition that a strong acid occurs, cured products thereof may suffer from decrease in physical properties.

Therefore, as the risk that the peroxydate is explosively decomposed is involved, there is a problem in safeness.

In addition, molybdenum chloride (V) used as a catalyst is expensive and strongly poisonous.

However, the cured product composed of the above aromatic epoxy resin for general purpose that is a glycidyl ether-based epoxy resin has the structure of an aromatic nucleus, so it has inferior weatherability outdoors.

Therefore, the glycidyl ether-based epoxy resin is mostly used by being dissolved in a solvent typified by toluene, xylene, methyl ethyl ketone, ethyl acetate, or the like, which causes a problem with workability and environmental safeness.

Since the epoxy compound with an alicyclic skeleton has sufficient performance but slightly lower reactivity when used in the above applications, the cured product thereof may suffer from decrease in physical properties and reactivity.

Furthermore, the foregoing monoepoxidized 4-vinylcyclohexene and limonene diepoxide evaporate at room temperature, which causes a problem with working surroundings.

However, none of those curable resin compositions each including the alicyclic diepoxy compound has displayed satisfactory performance yet.

Therefore, cracks occur in the portion of the resin and cracks and exfoliation occur around a chip, which reduces reliability, resulting in a problem of unusability as a product.

Although higher loading of a filler is effective means, it has limitations and may cause increase in viscosity and decrease in fluidity of the resin for encapsulation.

The increased viscosity of the resin for encapsulation results in the deformation and cutting of a lead wire and the decreased fluidity results in lower loading, which may reduce reliability.

However, as described above, 1,2,8,9-diepoxylimonene has a methyl group in carbon constituting an epoxy group and thus the epoxy group has low reactivity compared to one having no methyl group.

However, the epoxidation rate of the epoxy compound is somewhat low.

In addition, JP 2001-181481 A discloses an epoxy resin composition for the encapsulation of semiconductors utilizing a biphenyl-based epoxy resin, which has superior water-absorbing properties but still has a problem with fluidity and torque in curing, that is, moldability.

Moreover, in general, since a capacitor has the sealed structure in which an insulating oil is enclosed, it is deformed by gas generated from decomposition or made unusable owing to the reduction in breakdown voltage and capacitance.

Thus, a conventional cast article of an epoxy resin composition has limitations on electric properties and mechanical properties and potentially leads to breakdown.

Moreover, since dielectric loss (ε.tanδ.E2) is enlarged along with an ultra high-voltage, the thermal damage of an insulator may be caused by the generated heat.

Those compositions are not suitable for casting and impregnation because the compositions are of solid.

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