JPH061828A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in workability and crack resistance. CONSTITUTION:The title composition comprises a normally liquid mixture of a bisphenol A epoxy resin having a mol.wt. distribution curve with two peaks, one at a mol.wt. of 500 or lower and the other at 900 or higher and below 3,000, and a diol having a mol.wt. of 1,000 or lower, a liquid acid anhydride as a hardener, a curing accelerator, an inorganic filler, and an organic additive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition, and more particularly to an epoxy resin composition used for mold insulation of electric equipment.

[0002]

2. Description of the Related Art Conventionally, in order to insulate a high voltage applying portion of an electric device, a method of arranging a resin layer around it has been widely used. Epoxy resin, which has excellent insulating properties and mechanical properties, is most often used as the resin. Known methods for forming the resin layer include a die casting method and an impregnation method. In order to improve the workability of the resin composition to be used, it is common to use a liquid epoxy resin having a low viscosity or a curing agent, and in order to improve the crack resistance, increase the inorganic filler. Alternatively, a technique such as using a solid epoxy resin having a large molecular weight is known.

[0003]

However, the above method was not sufficient to satisfy both workability and crack resistance at the same time. A method of adding another organic material such as a rubber-based material to improve the crack resistance is also known, but this method is accompanied by a decrease in electrical characteristics, and thus its application range is limited. Further, in recent years, with the demand for smaller and lighter electric devices, a resin having more excellent workability and crack resistance is required.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an epoxy resin composition excellent in workability and crack resistance.

[0005]

To solve the above problems, the present invention provides a molecular weight of 500 or less and a molecular weight of 900 or more 30.
A mixture of a bisphenol A type epoxy resin having a molecular weight peak at two positions of less than 00 and a diol having a molecular weight of 1000 or less, a curing agent composed of a liquid acid anhydride, a curing accelerator, an inorganic filler, and The organic additive comprised an epoxy resin formulation.

To ensure cure of the formulations of the present invention, it is necessary to first mix the epoxy resins of different molecular weights and the diols and to react these mixtures at at least 60 ° C or above.

As the inorganic filler, silica, alumina or the like can be used. The organic additive means a colorant, a defoaming agent and the like.

[0008]

According to the compounding agent having the above-mentioned constitution, by using the epoxy resin having the molecular weight peaks at two places of the molecular weight of 500 or less and the molecular weight of 900 or more and less than 3000, the epoxy resin having the molecular weight peak at one place is used. The fluidity and crack resistance of the resin are improved as compared with the case. In addition, since the diol having a molecular weight of 1000 or less is contained, the diol partially reacts with the epoxy resin, and the low molecular weight epoxy resin forms a polymer to improve the crack resistance, and the high molecular weight epoxy resin is Dissolution is accelerated.
As a result, a uniform solution can be easily obtained, workability is improved, and crack resistance is improved.

[0009]

EXAMPLES The present invention will be specifically described with reference to Examples and Comparative Examples. Example 1 A mixture of 90 g of Epicoat 828 (molecular weight about 400), which is an epoxy resin, 10 g of Epicoat 1001 (molecular weight of about 1000), and 10 g of polypropylene glycol (average molecular weight of about 400) at 100 ° C. in a stainless container. Heated for 1 hour. Next, after cooling this mixed liquid to 70 ° C. or lower, ME-TH was used as a curing agent.
80 g of PA (methyl tetrahydrophthalic anhydride), 0.5 g of DMP-30 (tertiary amine) as a curing accelerator, and 286 g of silica as an inorganic filler were added and sufficiently mixed, followed by vacuum defoaming to obtain a resin. A formulation was prepared.

In order to evaluate the crack resistance of the obtained resin compound, a hexagonal bolt (M1
6 × 45) was placed and the resin formulation was vacuum cast and heated at 80 ° C. for 12 hours and 140 ° C. for 8 hours to produce 5 bolt mold samples. The obtained bolt mold sample was heated at 120 ° C. for 3 hours, and then placed in a low temperature bath at 0 ° C. and rapidly cooled. After 3 hours, the sample was taken out from the low temperature tank and the number of cracks was counted. The sample in which no crack was generated was heated again at 120 ° C. for 3 hours and then rapidly cooled in a low temperature bath maintained at −10 ° C. for 3 hours.
The number of cracks was counted. The test was repeated until cracks occurred in all samples, and the average crack index was obtained. Here, the crack index was set as follows for the heat cycle conditions.

Heat Cycle Conditions Crack Index 120 ° C. → 0 ° C. 1 120 ° C. → −10 ° C. (First Time) 2 120 ° C. → −10 ° C. (Second Time) 3 120 ° C. → −10 ° C. (Third Time) 4 120 ° C. → -20 ° C (1st time) 5 120 ° C → -20 ° C (2nd time) 6 120 ° C → -20 ° C (3rd time) 7 120 ° C → -30 ° C (1st time) 8 120 ° C → -30 ° C (2nd time) ) 9 120 ° C. → −30 ° C. (3rd time) 10 120 ° C. → −40 ° C. (first time) 11 120 ° C. → −40 ° C. (second time) 12 120 ° C. → −40 ° C. (third time) 13 (Example 2) ~ 7) In the same manner as in Example 1, a molecular weight of 500
The following epoxy resin, an epoxy resin having a molecular weight of 900 or more and less than 3000, and a diol having a molecular weight of 1000 or less were mixed at various blending ratios and heated to prepare an epoxy resin mixture to prepare a resin blend. Six types of bolt mold samples were manufactured using these resin compounds, and were set as Examples 2 to 7.

Table 1 shows the compositions of the resin formulations of Examples 1 to 7, the viscosity thereof, and the results of the heat cycle test of the bolt mold samples.

[0013]

[Table 1]

Comparative Examples 1 to 8 Various resin blends and bolt mold samples using these blends were manufactured in the same manner as in Examples 1 to 7. A heat cycle test was performed using the obtained sample, and an average crack index was obtained to evaluate crack resistance. Table 2 shows the composition of the resin compound, its viscosity, and the result of the heat cycle test of the bolt mold sample.

[0015]

[Table 2]

As is apparent from Tables 1 and 2, the formulations of Examples 1 to 3 contain the diol and silica, so that Comparative Examples 1 to 3 contain the same formulation of epoxy resin. The viscosity at 60 ° C. is lower than that of the compound (1). Further, in the formulations of Examples 4 to 7, the epoxy resin having a molecular weight of 500 or less and the diol and silica having a molecular weight peak at two positions of the molecular weight of 900 or more and less than 3000 are contained, so that the epoxy resin having a molecular weight of 500 or less is obtained. And the diol, or the epoxy resin having a molecular weight of 500 or less, the viscosity is higher than the formulations of Comparative Examples 4 to 8. In addition, the average crack index in all of the formulations of Examples is larger than the average crack index in the formulations of Comparative Examples.

[0017]

As described above, according to the compounding agent of the present invention, by using an epoxy resin having a molecular weight peak of two at a molecular weight of 500 or less and at a molecular weight of 900 or more and less than 3000, a molecular weight peak at one location is obtained. The fluidity and crack resistance of the resin are improved as compared with the case of using an epoxy resin having a. In addition, since the diol having a molecular weight of 1000 or less is contained, the fluidity and thus the workability are improved and the crack resistance is improved.

Claims (1)

[Claims] 1. A molecular weight of 500 or less and a molecular weight of 900 or more 3
A mixture of a bisphenol A type epoxy resin having a molecular weight peak at two sites of less than 000 and a diol having a molecular weight of 1000 or less, a curing agent composed of a liquid acid anhydride, a curing accelerator, an inorganic filler, and An epoxy resin formulation containing an organic additive.