JPS58157804A - Casting resin composition - Google Patents

Abstract

PURPOSE:To prepare the titled composition having excellent impregnation property into coil, etc., and high filler content, and giving a cured product having high strength, by compounding a casting resin with a large amount of spherical inorganic filler powder. CONSTITUTION:A casting resin (e.g. bisphenol-type liquid epoxy resin) is compounded with spherical inorganic filler powder (e.g. glass beads). The amount of the inorganic filler is >=50vol% of the whole fillers.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a casting resin composition that has excellent impregnation properties into coils and the like.

In general, (1) cost reduction, improvement in shrinkage and thermal expansion coefficients, (3) reduction in heat generation during curing, and (4)
BACKGROUND ART For the purpose of improving thermal conductivity, inorganic fillers are blended into casting resins, such as epoxy resins.

The above-mentioned effects become more pronounced as the amount of inorganic filler added increases, but in recent years, compositions containing a large amount of filler have become problematic in recent years.

That is, in recent years, ultrafine wire coils and ignition coils using interlayer paper have been impregnated with the above-mentioned highly filled epoxy resin composition and cast. This had the drawback that the properties of the cast product deteriorated, making it impossible to obtain a cast product with good properties.

The inventors of the present invention have conducted extensive research to solve these problems, and have found that by blending a large amount of powdered inorganic filler with spherical particle shapes, a castable material with excellent impregnation properties and high strength of the cured product has been developed. In a composition containing an inorganic filler from which a resin composition is obtained, a powder filler having a spherical particle shape is blended in an amount of at least 50% by volume of the total filler. The present invention relates to a resin composition.

The casting resin used in the present invention includes bisphenol type and other known liquid epoxy resins and unsaturated polyester resins. These casting resins are used in combination with a curing agent consisting of an amine type, an acid anhydride type, or a peroxide, but a curing accelerator can also be used together with these curing agents.

In this case, in order to blend as much filler as possible without reducing workability, filler should be blended in the curing agent system in advance, and this should be added to the casting resin composition containing filler. It is preferable to mix it.

Examples of the powdered inorganic filler having a spherical particle shape used in the present invention include glass peas.

As shown in Table 1, even if the particle size of the glass beads increases, the creep rupture strength of the cured product hardly changes. A wide range of particle sizes can be used.

On the other hand, in the case of crushed silica powder whose particle shape is not spherical, as the particle size increases, the strength of a cured product obtained from a composition filled with the crushed silica powder sharply decreases.

Table 1 (Tensile creep rupture strength of cured product obtained from an epoxy resin composition containing 38% by volume of the filler shown in the table, 65°C)
, 500 Ky'cd) Also, in the case of spherical powders such as glass beads, -c
The thickening effect caused by adding s is small, and therefore a large amount can be blended without significantly reducing workability.

In the present invention, such a spherical powder filler is blended in an amount of at least 50% by volume of the total filler, but the blending amount is limited in this way for the following reason.

In other words, when the amount of the spherical filler added is less than the SO volume % of the entire filler, no effect such as improvement in impregnating properties is observed compared to conventional ones, and the resulting composition is not the object of the present invention. This is because it does not match.

In addition, in the present invention, when a spherical powder filler is blended, the sedimentation of the filler when the composition is impregnated and hardened is large, and this tendency becomes greater as the particle size becomes larger, but this can be prevented. To achieve this, a filler with a small particle size is used, or hydrophobic fine powder silica (structural formula (CH2-110s7)
It is desirable to add a small amount of @)m).

In the above explanation, we have discussed the effect of blending spherical powder fillers in compositions mainly composed of epoxy resins, but the same effect can also be achieved with unsaturated polyester resins, etc., which are blended with large amounts of fillers. Of course, we can expect it.

Next, examples of the present invention will be described.

Examples 1-2 25% by volume and 35% glass beads with an average particle size of 30μ
An epoxy resin composition was prepared by blending the mixture into a bisphenol-type liquid epoxy resin (containing an acid anhydride curing agent) having an epoxy equivalent of 199 in volume %C.

For comparison, epoxy resin compositions were prepared by blending fragmented silica having an average particle size of 7.6 μm obtained by a wet method in the same manner as shown in Table 2.

Table 2 shows the results of an impregnation test conducted on these resin compositions.

In the impregnation test, glass beads with an average particle size of 65 μm were placed in a test tube in advance, and each of the above compositions was vacuum injected into the tubes and cured at a predetermined temperature, so that the resin composition penetrated into the glass beads layer. This was done by measuring the length of the impregnated layer.

The following is a blank space in Table 2. Examples 3 to 5 The compositions prepared by blending glass beads, silica, and other additives in the proportions shown in Table 3 with bisphenol-type epoxy V resin having an epoxy equivalent of 190 are described above. The impregnability was tested using the method described below. Furthermore, the thermal expansion coefficients of cured products obtained from these compositions were measured by a known method. 3rd result
Shown in the table.

Table 3 with blank space below (The numbers in the upper column of the table indicate volume %.) As is clear from the above examples, the composition of the present invention contains a large amount of inorganic filler, and the cured product It has the advantages of a low coefficient of thermal expansion and high mechanical strength. It also has excellent impregnating properties, making it suitable as a composition for impregnating and casting coils and the like.

Representative Patent Attorney Su Yamasa -

Claims (1)

[Scope of Claims] In a highly filled composition formed by blending a large amount of inorganic filler with a casting resin, it is claimed that a powder filler having a spherical particle shape is blended in an amount of at least 50% by volume of the total filler. Characteristic resin composition for casting.