JP2000169678A - Epoxy resin composition and mold coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mold coil capable of attaining viscosity reduction of an epoxy resin composition before curing and improving casting workability and having excellent insulation reliability after curing by using a silica filler having a regulated frequency of particle diameter in a specific range as a filler of an epoxy resin composition. SOLUTION: In this epoxy resin composition comprising an epoxy resin, a curing agent and a silica filler, the silica filler has <=50 μm maximum particle diameter, >=10% cumulative frequency having <=0.82 particle diameter, >=85% cumulative frequency having 0.82-18.50 μm particle diameter and the ratio of frequencies of [1] 0.82-2.31 μm particle diameter, [2] 2.31-6.54 μm particle diameter and [3] 6.54-18.50 μm particle diameter of [1]:[2]:[3] of 1.00:1.10 to 0.90:1.00 to 1.00-0.80.

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 a mold coil, and more particularly to an epoxy resin composition having low viscosity before curing and excellent in castability, and having excellent insulation reliability after curing and the epoxy resin. The present invention relates to a molded coil using a resin composition.

[0002]

2. Description of the Related Art Conventionally, epoxy resin compositions applied to molded coils and the like are used for the purpose of improving electrical properties, mechanical properties, crack resistance, etc., and further reducing costs.
Various fillers are blended in large amounts. However, the viscosity of the epoxy resin composition is increased by adding a large amount of filler, which significantly reduces the casting workability at the time of producing a molded coil, and furthermore, the epoxy resin composition does not easily penetrate into windings and the like. However, there have been problems such as a decrease in insulation reliability.

[0003] Therefore, a low-viscosity epoxy resin composition is demanded in order to improve casting workability and insulation reliability when producing a molded coil. Factors affecting the viscosity of the epoxy resin composition include the average particle size, particle size distribution, and particle shape of the filler.

As a conventional method for lowering the viscosity with a filler, for example, Japanese Patent No. 2638223 discloses an epoxy resin composition comprising an epoxy resin, a filler, and a curing agent.
(A) filler having an average particle size of 12 to 18 μm and a cumulative particle size distribution of 20 μm or less and a cumulative weight of 80% or more and 6 μm or less and a cumulative weight of 10% or less; (B) an average particle size of 3 to 5 μm and a particle size distribution of 6 μm or less (A) / (B) = 75/25 to 25/75 (weight ratio) by mixing a filler having a cumulative weight of 80% or more and a cumulative weight of 2 μm or less and 20% or less. I have.

Further, Japanese Patent No. 2646663 discloses that (A) spherical inorganic powder having an average particle diameter of 12 to 20 μm, a content of 2 μm or less of 7 to 15% by weight, and a content of 12 μm or less of 35 to 50% by weight or 24 μm
(B) a crushed inorganic powder having an average particle size of 8 to 25 μm,
Filler with a content of 5 μm or less of 5 to 15% by weight, 30 to 60% by weight of 12 μm or less, and 50 to 85% by weight of 24 μm or less (A) / (B) = 9
It is disclosed that mixing is performed in the range of / 1 to 5/5 (weight ratio) to achieve crack resistance and low viscosity.

As described above, conventionally, viscosity reduction has been achieved by applying a mixture of two or more inorganic fillers having different particle diameters or particle shapes (combined use) to an epoxy resin composition. However, these methods require the work of managing and mixing two or more particle size distributions. In addition, from the viewpoint of casting property to a thin wire portion such as a molded coil, the appearance of an epoxy resin composition having a lower viscosity is desired.

On the other hand, in Japanese Patent No. 2680029, a coupling agent which is chemically bonded or molecularly entangled with an organic matrix resin and an inorganic filler is used in combination to have a low viscosity before curing, and a crack resistance and heat resistance after curing. Are disclosed. However, although the use of the above-mentioned coupling agent improves viscosity characteristics and crack resistance, there is a problem that heat resistance is newly lowered.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art by providing an epoxy resin composition having a low viscosity before curing and having excellent casting workability, and having excellent insulation reliability after curing. It is intended to provide a molded coil using the epoxy resin composition.

[0009]

According to the present invention, in an epoxy resin composition, the maximum particle size of silica filler is 50 μm or less, and the cumulative frequency of 0.82 μm or less is 10% or less.
The above problem could be solved by setting the cumulative frequency of 0.82 to 18.50 μm to 85% or more and defining the frequency of the particle size in a specific range.

That is, the present invention relates to an epoxy resin composition containing an epoxy resin, a curing agent and a silica filler,
The silica filler has a maximum particle size of 50 μm or less, and a particle size of 0.8.
Cumulative frequency of 2μm or less is 10% or less, particle size 0.82 to 18.50μm
Is 85% or more, and [1] particle size is 0.82 to 2.
31 μm, [2] particle size 2.31 to 6.54 μm, [3] particle size 6.54 to 18.50
μm frequency ratio is [1]: [2]: [3] = 1.00: 1.10-0.90:
1.00 to 0.80. Here, epoxy resin [A] bisphenol A type epoxy resin and [B] bisphenol F type epoxy resin are [A]: [B] = 90 parts by weight: 10 parts by weight to 60 parts by weight: 40 parts by weight Is preferred. Further, the epoxy resin composition may be two-packed into [a] an epoxy resin composition containing an epoxy resin and a silica filler and [b] a resin composition containing at least a curing agent and a silica filler.

[0011] The present invention also relates to a method of casting a coil obtained by casting an epoxy resin composition on a winding having an electric insulator coated on a conductor and then curing the epoxy resin composition by heating. Was achieved.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The particle size composition of the silica filler shown in the present invention was defined from the result of measuring the particle size distribution with a laser diffraction particle size distribution analyzer MICROTRAC FRA type (manufactured by Nikkiso Co., Ltd.). That is, the measurement use range is set to 0.12 to 704 μm and the particle size distribution is measured, and the cumulative frequency of the particle size of 0.82 μm or less is 0.12 to 0.14 μm, 0.14 to 0.17 μm, 0.17 to 0.20 μm,
0.20-0.24μm, 0.24-0.29μm, 0.29-0.34μm, 0.34
~ 0.41μm, 0.41 ~ 0.49μm, 0.49 ~ 0.58μm, 0.58 ~ 0.6
The cumulative frequency of each frequency at 9 μm and 0.69 to 0.82 μm is 10
% Or less, the cumulative frequency of 0.82 to 18.50 μm is 85% or more, [1] The frequency of 0.82 to 2.31 μm is 0.82 to 0.97,
97-1.16 μm, 1.16-1.38 μm, 1.38-1.64 μm, 1.64-
The cumulative frequency of each frequency at 1.94 μm and 1.94 to 2.31 μm, and the frequency of [2] particle size 2.31 to 6.54 μm is 2.31 to 2.75
μm, 2.75-3.27 μm, 3.27-3.89 μm, 3.89-4.62 μm,
It is the cumulative frequency of each frequency in 4.62 to 5.50 μm and 5.50 to 6.54 μm, and the frequency of [3] particle size 6.54 to 18.50 μm is 6.5
4 to 7.78 μm, 7.78 to 9.25 μm, 9.25 to 11.00 μm, 11.00 to
This is the cumulative frequency of each frequency at 13.08 μm, 13.08 to 15.56 μm, and 15.56 to 18.50 μm.

Although it is not clear why the use of a silica filler having such a particle size distribution achieves a reduction in viscosity before curing, it is possible to achieve a close packing that is effective in lowering the viscosity. I guess. Examples of the silica filler include crystalline silica and fused silica from the viewpoints of production cost, particle size distribution, and the like.

From the viewpoints of viscosity, mechanical strength and heat resistance, the epoxy resins shown in the present invention include, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F An epoxy resin such as a type epoxy resin, a bisphenol A / F type epoxy resin obtained by the reaction of bisphenol A and bisphenol F with epichlorohydrin, an alicyclic epoxy resin, and a novolak epoxy resin is used. Epoxy resin is the same as the above epoxy resin alone or 2
A mixture of more than one species can be used.

Particularly, from the viewpoints of viscosity, heat resistance, cost and the like, the epoxy resin includes [A] bisphenol A type epoxy resin (epoxy equivalent of about 180 to 200) and [B] bisphenol F type epoxy resin (epoxy equivalent of 160 to 200). 180)
[A]: [B] = 90 parts by weight: 10 parts by weight to 60 parts by weight: preferably 40 parts by weight. If the bisphenol A type epoxy resin component is large, the viscosity and glass transition temperature (hereinafter, referred to as Tg) are high. On the other hand, the viscosity and Tg tend to decrease when the amount of bisphenol F type epoxy resin component is large.

The curing agent according to the present invention includes an acid anhydride or an amine compound.

As the acid anhydride, for example, phthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, etc., and as the amine compound, for example, aliphatic polyamine and its modified product, aromatic polyamine and its modified product And the like. Among them, acid anhydride has low viscosity and high Tg
Is preferred because The mixing ratio of the epoxy resin and the curing agent is not particularly limited, but usually, in consideration of the balance of various properties of the cured product, the equivalent ratio of the acid anhydride is about 1: 1 (cured with respect to 100 parts by weight of the epoxy resin). 80-120 parts by weight)
For amine compounds, 10-6 parts per 100 parts by weight of epoxy resin
0 parts by weight is selected.

The curing accelerator is appropriately used in accordance with the use of the epoxy resin composition of the present invention, improvement or improvement of properties, and examples thereof include 2-methylimidazole and 2-ethyl-4-.
Imidazoles such as methylimidazole, 1-cyanoethyl-2-methylimidazole, 1- (2-cyanoethyl) -2-ethyl-4-methylimidazole, and tertiary amines such as benzyldimethylamine and N-benzyldimethylamine is there. These curing accelerators may be used alone or in combination of two or more. The amount of the curing accelerator is appropriately selected from the gelation time and pot life (pot life) of the epoxy resin composition.
0.1 to 10 parts by weight is added to 80 to 120 parts by weight of the curing agent.

The coupling agent is appropriately used in accordance with the use, improvement or improvement of the properties of the epoxy resin composition of the present invention, and (1) a reactive functional group chemically bonded to an inorganic filler, an organic matrix resin, It is more effective to use a coupling agent having a reactive functional group to be bonded and (2) a coupling agent having a non-reactive organic group chemically bonded to an inorganic filler and entangled with an organic matrix resin.

As the coupling agent represented by the above (1), for example, vinylethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane Etc. Of these, γ-glycidoxypropyltrimethoxysilane is preferred. Also,
As the coupling agent represented by (2), monoalkoxy titanates, coordinate type titanates, chelate type titanates, and trialkoxy titanates can be used. Of these titanate coupling agents, monoalkoxy titanates are preferred. Of the above coupling agents, if the amount of the coupling agent represented by (1) is too large, the crack resistance tends to decrease, and the amount of the coupling agent represented by (2) is too large. And heat resistance tends to decrease. For this reason, it is preferable that both are added in the range of 0.05 to 2.0% by weight, more preferably 0.1 to 1.5% by weight, based on the inorganic filler. The epoxy resin composition containing the epoxy resin of the present invention, a curing agent and a silica filler is (a) an epoxy resin composition containing an epoxy resin and a silica filler.
[b] By separately preparing the resin composition containing at least a curing agent and a silica filler, it is possible to increase the amount of a curing accelerator appropriately used in the epoxy resin composition,
The epoxy resin composition according to the present invention can achieve rapid curability. In this case, the epoxy resin composition [a] and the resin composition [b] may be measured and mixed in an appropriate amount using a two-liquid mixing / discharging apparatus immediately before the casting operation, and then cast.

The above-described epoxy resin composition is cast into a winding in which an electric insulator is coated on a conductor, and then cured by heating, whereby a molded coil having excellent insulation reliability can be manufactured.

Hereinafter, the present invention will be described with reference to examples.

[0023]

Examples 1 to 6, Comparative Examples 1 to 5 Silica as Silica Filler
The maximum particle size of A, Silica B, Silica C, Silica 1, Silica 2, Silica 3, Silica 4, Silica 5 (crystalline silica manufactured by Tatsumori Co., Ltd.) 1
Shown in

[0024]

[Table 1]

These measurements were performed using a laser diffraction particle size distribution analyzer MICROTRAC FRA type (manufactured by Nikkiso Co., Ltd.)
The measurement range of the particle size was set to 0.12 to 704 μm, and about 1 g of silica filler was ultrasonically dispersed in about 100 ml of a 0.2 wt% aqueous solution of sodium hexametaphosphate for about 1 minute to obtain a measurement sample.

Using the silica filler described above, bisphenol F type epoxy resin (trade name: EP-4901, manufactured by Asahi Denka Co., Ltd.) and bisphenol A / F type epoxy resin (trade name: PY-, manufactured by Ciba Geigy Co., Ltd.) 302-2),
Alicyclic epoxy resin (manufactured by Ciba Geigy Corporation, trade name CY
-179), methylhexahydrophthalic anhydride (manufactured by Hitachi Chemical Co., Ltd., trade name HN-5500), methylnadic anhydride (manufactured by Hitachi Chemical Co., Ltd., trade name)
MHAC-P), diethylenetriamine (manufactured by Sumitomo Chemical Co., Ltd.), and 1- (2-cyanoethyl) -2- as a curing accelerator
Ethyl-4-methylimidazole (trade name: 2E4MZ-CN, manufactured by Shikoku Chemicals Co., Ltd.) and benzyldimethylamine (trade name: BDMA, manufactured by Kao Corporation) were weighed in predetermined amounts shown in Table 2.

[0027]

[Table 2]

Thereafter, each material was vacuum defoamed (10%) using a universal mixing stirrer (Dalton Co., Ltd.) adjusted to about 90 ° C.
Pa) while stirring and mixing for about 30 minutes to produce the epoxy resin compositions of Examples 1 to 6. Table 2 also shows the viscosity, casting time, and glass transition temperature (abbreviated to Tg) of the cured product of the prepared epoxy resin composition.

The viscosity was measured using a sample bottle (35φ, 110m
In l), about 80 ml of the epoxy resin composition was weighed and immersed in a silicone oil bath adjusted to 90 ° C. using a BL-type rotational viscometer (manufactured by Tokyo Keiki Co., Ltd.). Next, about 400 g of the epoxy resin composition heated to 90 ° C. was measured for a casting time of 50 g.
After placing in a 0 ml separatory funnel (cock hole diameter: 1 mm, foot diameter: 7 mm), open the cock and inject it into a 200 ml graduated cylinder, measure the time to reach 150 ml, and cast this time. Time.

Further, the Tg was measured by heating the epoxy resin composition at 90 ° C. for 17 hours, and further heating at 170 ° C. for 15 hours. Was performed at a heating rate of 2.0 ° C./min.

The cumulative frequency of silica filler particles having a particle size of 0.82 μm or less is 10% or less and the cumulative frequency of silica particles having a particle size of 0.82 to 18.50 μm is 85%.
% Or more, the frequency ratio in the particle size range of 2.31 to 6.54 μm is 1.10 to 0.90, and the frequency ratio in the particle size range of 6.54 to 18.50 μm is 1.00 to 0.80.
The viscosity of the epoxy resin composition was as low as 2.0 Pa · s or less. The casting time was 5 minutes for all of the epoxy resin compositions of Examples 1 to 6, and the Tg was 130 ° C. or more for Examples 1 to 6.

On the other hand, the epoxy resin compositions of Comparative Examples 1 to 5 were prepared from the respective materials shown in Table 3 in the same manner as in Example 1. Table 3 also shows the viscosity, casting time, and Tg of the cured product of the prepared epoxy resin composition.

[0033]

[Table 3]

The cumulative frequency of the silica filler having a particle size of 0.82 μm or less exceeds 10% (Comparative Examples 1 and 3) or the particle size is 0.82
When the cumulative frequency of ~ 18.50 μm is less than 85% (Comparative Examples 2 and 3), the frequency ratio in the particle size range of 2.31 to 6.54 μm is
Even when the frequency ratio in the range of 1.10 to 0.90 and the particle size range of 6.54 to 18.50 μm was 1.00 to 0.80, the viscosity increased to about 3.0 Pa · s. In addition, even if the cumulative frequency of particle size 0.82μm or less is 10% or less and the cumulative frequency of particle size 0.82 to 18.50μm is 85% or more, the ratio of frequency in the particle size range 2.31 to 6.54μm exceeds 1.10. (Comparative Example 4) or less than 0.9 (Comparative Example
In the case of 5), the viscosity increased to about 3.0 Pa · s.

On the other hand, the casting time was 9 to 10 minutes for the epoxy resin compositions of Comparative Examples 1 to 5, and the Tg was 130 ° C. or higher for Comparative Examples 1 to 5.

As described above, the epoxy resin composition of this example has a low viscosity, and the casting time can be reduced to about 1/2 compared with the comparative example, so that the casting workability can be improved.

[0037]

Examples 7-11, Comparative Examples 6-8 In the same manner as in Example 1, silica fillers such as silica D, silica E, silica F and silica
The particle size distribution of 6, silica 7, and silica 8 (crystalline silica, manufactured by Tatsumori Corporation) was measured. Table 4 shows the maximum particle size, the cumulative frequency and the ratio of the frequency for each particle size.

[0038]

[Table 4]

Using these silica fillers, an epoxy resin, a curing agent, and a curing accelerator are measured in predetermined amounts shown in Table 5, and
An epoxy resin composition was prepared in the same manner as in Example 1. Table 5 also shows the viscosity, casting time, and Tg of the cured product of the prepared epoxy resin composition.

[0040]

[Table 5]

The cumulative frequency of silica filler particles having a particle size of 0.82 μm or less is 10% or less, and the cumulative frequency of silica filler particles having a particle size of 0.82 to 18.50 μm is 85%.
As described above, by further setting the frequency ratio in the particle size range of 2.31 to 6.54 μm to 1.10 to 0.90 and the frequency ratio in the particle size range of 6.54 to 18.50 μm to 1.00 to 0.80, Examples 7 to 11
The viscosity of the epoxy resin composition was as low as 2.0 Pa · s or less.

Next, the casting time was 5 minutes for all of the epoxy resin compositions of Examples 7 to 11, and the Tg was that of Examples 7 to 11.
11 indicated 130 ° C. or higher. On the other hand, when the ratio of the frequency of the silica filler in the particle size range of 6.54 to 18.50 μm is more than 1.00 (Comparative Example 6) or less than 0.8 (Comparative Examples 7 and 8), the cumulative particle size is 0.82 μm or less. Frequency less than 10%, particle size
The cumulative frequency of 0.82 to 18.50μm is 85% or more, and the particle size range
Even when the ratio of frequencies at 2.31 to 6.54 μm was in the range of 1.10 to 0.90, the viscosity increased to about 3.0 Pa · s. Therefore, the casting time was 9 times for the epoxy resin compositions of Comparative Examples 6 to 8.
Showed ~ 10 minutes. Moreover, Tg was 130 degreeC or more in Comparative Examples 6-8.

As described above, the epoxy resin composition of the present example has a low viscosity, and the casting time can be reduced to about 1/2 compared with the comparative example. Therefore, the effect of improving the casting workability was obtained.

[0044]

Examples 12 to 15 Bisphenol A which is an epoxy resin using the same silica A, curing agent and curing accelerator as in Example 1
Epoxy resin (AER-260, manufactured by Asahi Ciba Co., Ltd.)
The mixing ratio of the epoxy resin and the bisphenol F type epoxy resin was changed as shown in Table 6, and the mixture was stirred and mixed in the same manner as in Example 1 to prepare an epoxy resin composition. The viscosity of this epoxy resin composition and the Tg of the cured product obtained by heating in the same manner as in Example 1 were measured. The results are also shown in Table 6.

[0045]

[Table 6]

In any of the examples, the viscosity was 2.0 Pa · s
The Tg was about 150 ° C. According to the present embodiment, the epoxy resin of the epoxy resin composition has a compounding ratio of bisphenol A type epoxy resin: bisphenol F type epoxy resin of 90 parts by weight: 10 parts by weight to 60 parts by weight: 40 parts by weight, Low viscosity and high Tg were obtained.

[0047]

Example 16 Next, the epoxy resin composition shown in the present invention was
Description of an example in which [a] an epoxy resin composition composed of an epoxy resin, a coupling agent and a silica filler and [b] a resin composition composed of a curing agent, a coupling agent, a curing accelerator and a silica filler are two-packed I do.

[A] The same epoxy resin composition as in Example 3, 100 parts by weight of bisphenol A / F type epoxy resin, silica
A330 parts by weight and 3.0 parts by weight of a silane-based coupling agent (Shin-Etsu Chemical Co., Ltd., trade name: KBM-403) were weighed as the basic components, and then mixed and stirred in the same manner as in Example 1. did. [B] The resin composition contained 95 parts by weight of methyl hexahydrophthalic anhydride, 330 parts by weight of silica A, and 0.25 parts by weight of 1- (2-cyanoethyl) -2-ethyl-4-methylimidazole as in Example 3. Further, each material was weighed based on 1.0 part by weight of a titanate-based coupling agent (trade name: S-181, manufactured by Nippon Soda Co., Ltd.), and the mixture was stirred and mixed in the same manner as in Example 1 to prepare a mixture.

Thereafter, the epoxy resin composition [a]
[b] The resin composition of Example 16 was mixed by using an automatic metering and discharging device (trade name: Tristan TVE-EL, manufactured by Nakari Liquid Control Co., Ltd.) in a mixing section. Was obtained. The gelation time, viscosity and Tg of the cured product obtained by heating in the same manner as in Example 1 were measured for the epoxy resin composition of Example 16 and the one liquid shown in Example 3. Table 7 shows the results.

[0050]

[Table 7]

The gelation time was measured using a gelation time measuring device (manufactured by Toshiba Corporation, Model SFO-4M), and about 8 ml of the epoxy resin composition was weighed into a test tube (18φ, 18 ml).
The test was carried out by immersion in a silicone oil bath adjusted to ° C. As a result, the gel time of the epoxy resin composition of Example 16 was
While it is 170 minutes at 90 ° C. and 88 minutes at 100 ° C., the one-part epoxy resin composition of Example 3 is 380 minutes at 90 ° C. and 200 minutes at 100 ° C.
Minutes.

The viscosity and Tg of the cured two-part epoxy resin composition of Example 16 were almost the same as those of Example 3 of one liquid. In the one-part epoxy resin composition of Example 3, the curing reaction starts when the epoxy resin and the curing agent are mixed, and the reaction is accelerated by further adding a curing accelerator. Therefore, there is a time restriction from the mixing of the materials until the casting operation is performed.

On the other hand, in Example 16, since the epoxy resin composition [a] and the resin composition [b] were preliminarily liquidized, the curing reaction does not occur unless both are mixed. Therefore, the storage of the epoxy resin composition can be made substantially indefinite by the two-packing, and the gelation time can be shortened to 1/2 by increasing the amount of the curing accelerator, thereby achieving rapid curing. .

[0054]

Example 17 and Comparative Example 9 An example in which a molded coil was produced using the epoxy resin composition according to the present invention will be described. FIG. 1 is a perspective view, partly in section, showing the configuration of a molded coil according to the seventeenth embodiment. In this molded coil, the inner and outer peripheries are molded with prepreg insulators 2a and 3a, respectively, to form an inner perimeter insulating layer 2 and an outer perimeter insulating layer 3, and the same epoxy resin composition 4 as in Example 4 is wound inside the coil. It is produced by impregnating and injecting into the inside of the wire 1 and then heating and curing.

As shown in FIG. 2, the method of manufacturing a molded coil in this embodiment is such that a prepreg insulator
2a is wound so as to be in intimate contact with the flange 7 for preventing leakage of the epoxy resin composition, and the winding 1 is wound thereon.

As shown in FIG. 3, the conductor 1a and the interlayer insulator 5 are wound alternately on the winding 1. In FIG. 2, after the winding 1 is wound, a prepreg insulator 3a is further wound on the upper surface thereof such that one end thereof is in close contact with the flange 7, and then at 170 ° C.
For 4 hours to dry winding 1 and prepreg insulators 2a, 3a
Is cured.

As shown in FIG. 3, in the same manner as in the fourth embodiment, a space surrounded by the inner circumferential insulating layer 2 and the outer circumferential insulating layer 3 and a space surrounded by the conductor 1a and the interlayer insulator 5 with the flange 7 down. The epoxy resin composition was impregnated and injected in about 10 minutes, and after heating and curing at 90 ° C. for 17 hours, the flange 7 and the core 8 were removed.
After heating and curing at 15 ° C. for 15 hours, it was cooled to room temperature over about 12 hours to produce a molded coil. Similarly, the molded coil of Comparative Example 9 was prepared by impregnating and injecting the same epoxy resin composition as in Comparative Example 3 into the winding in about 15 minutes, and manufactured in the same manner as in Example 17.

Since the molded coil of Example 17 uses a low-viscosity epoxy resin composition, there are no voids (bubbles) in the winding portion as shown in FIG. As a result of applying a voltage and conducting a withstand voltage test,
No corona was generated.

On the other hand, since the molded coil of Comparative Example 9 uses an epoxy resin composition having a high viscosity, FIG.
As shown in (1), voids (bubbles) were formed in the winding portion. As a result of conducting a withstand voltage test in the same manner as in Example 17, corona was generated.

According to the present example, since the epoxy resin composition had a low viscosity before curing, the casting operation time during coil production could be reduced from about 15 minutes to about 10 minutes as compared with Comparative Example 9, and the curing time was reduced. Later, no void was formed in the winding portion of the molded coil, and the occurrence of corona could be suppressed, so that the insulation reliability could be improved.

[0061]

Example 18 and Comparative Example 10 In the same manner as in Example 17, a winding having the flange 7, the inner peripheral insulating layer 2 and the outer peripheral insulating layer 3 was produced. Next, the same epoxy resin composition as in Example 12 was impregnated and injected into the winding in about 10 minutes, and after being heat-cured at 90 ° C. for 17 hours, the flange 7 and the core 8 were removed.
-After 15 hours of heat curing, the mold coil of the present invention was produced by cooling to room temperature over about 12 hours. Similarly, comparative example
The molded coil of No. 10 was manufactured in the same manner as in Example 18 by impregnating and injecting the same epoxy resin composition as in Comparative Example 8 into the winding in about 15 minutes.

After applying 300 kVA to these molded coils, the presence or absence of cracks was confirmed.
As a result, since the molded coil of Example 18 used the epoxy resin composition having a high Tg, the coil temperature was increased to about 135 ° C. by energization, but there was no crack. On the other hand, since the molded coil of Comparative Example 10 uses a low Tg epoxy resin composition, the coil temperature is reduced to about 135 by energization.
The temperature rose to ℃ and cracks occurred.

According to this example, since the epoxy resin composition had a high Tg after curing, it was possible to suppress the occurrence of cracks due to a rise in coil temperature during energization, thereby improving insulation reliability.

[0064]

[Embodiment 19] Fig. 5 is a perspective view, partially in section, showing the structure of a molded coil of this embodiment. In this molded coil, the inner and outer peripheries are molded with prepreg insulators 2a and 3a, respectively, to form an inner perimeter insulating layer 2 and an outer perimeter insulating layer 3, and a high viscosity putty resin composition 9 is applied to one end of the coil. After filling and curing, an epoxy resin composition 4 similar to that in Example 16 was impregnated and injected into the inside of the winding 1 and then heated and cured.

As shown in FIG. 6, the method of manufacturing a molded coil in this embodiment is such that a prepreg insulator
2a is wound, and the winding 1 is wound thereon. As shown in FIG. 7, a conductor 1a and an interlayer insulator 5 are wound alternately on the winding 1.

In FIG. 6, after the winding 1 is wound, a prepreg insulator 3a is further wound on the upper surface thereof, and as shown in FIG. 7, one end of the coil is filled with a high-viscosity putty resin composition 9. The wire 1 was dried by heating at 170 ° C. for 4 hours, and the prepreg insulators 2a and 3a and the putty-like resin composition 9 were cured. Thereafter, the coil was removed from the core 8 and placed with the end filled with the putty-like resin composition 9 down as shown in FIG.
A resin composition comprising the same [a] bisphenol A / F type epoxy resin, silica A and a silane coupling agent as in 6,
[b] Methylhexahydrophthalic anhydride, silica A, 1- (2
-Cyanoethyl) -2-ethyl-4-methylimidazole and an epoxy resin composition 4 obtained by mixing the resin composition comprising a titanate-based coupling agent with an automatic metering and discharging device.
Is the space surrounded by the inner insulating layer 2 and the outer insulating layer 3 and the winding 1
It was impregnated and injected into the space in about 5 minutes. Then, after heating and curing at 100 ° C. for 5 hours and 170 ° C. for 7 hours, it was cooled to room temperature over about 7 hours to obtain a molded coil.

According to this example, since the epoxy resin composition had a low viscosity before being cured, the casting operation time for producing the coil could be reduced from about 10 minutes to about 5 minutes as compared with the conventional method, and
Since no void is formed in the winding part of the molded coil,
Corona generation can be suppressed, and insulation reliability is improved. Furthermore,
By applying the two-component epoxy resin composition, it is possible to achieve a rapid curing property of about 1/2 of the gel time, thereby shortening the heat curing time of the mold coil from 32 hours to 12 hours. As a result, the manufacturing time of the molded coil was reduced by more than half.

[0068]

According to the present invention, the epoxy resin composition has a maximum particle size of 50 μm or less, a cumulative frequency of 0.82 μm or less is 10% or less, and a cumulative frequency of 0.82 to 18.50 μm is 85% or less.
% Or more, and [1] particle size 0.82 to 2.31 μm, [2] particle size
2.31 ~ 6.54μm, [3] particle size 6.54 ~ 18.50μm frequency ratio
[1]: [2]: [3] = 1.00: 1.10 to 0.90: By applying silica filler with 1.00 to 0.80, it becomes possible to lower the viscosity before curing and improve casting workability. Can be. The epoxy resin of the epoxy resin composition is a mixture of [A] bisphenol A type epoxy resin and [B] bisphenol F type epoxy resin, and [A]: [B] = 90 parts by weight: 10 parts by weight to 60 parts by weight Parts: in the range of 40 parts by weight, an epoxy resin composition having low viscosity before curing and having excellent heat resistance after curing can be obtained.

Further, the epoxy resin composition may be used as an epoxy resin composition containing [a] an epoxy resin and a silica filler.
[b] By two-packing with a resin composition containing at least a curing agent and a silica filler, it is possible to increase the amount of a curing accelerator appropriately used in the epoxy resin composition, and to achieve rapid curing, so that a mold is obtained. The time required to manufacture the coil can be reduced.

A molded coil having excellent insulation reliability can be obtained by casting a coil having an electric insulator coated on a conductor using the above-described epoxy resin composition, followed by heat curing.

[Brief description of the drawings]

FIG. 1 is a perspective view, partly in section, showing a configuration of a molded coil of Examples 17 and 18.

FIG. 2 is a side view of a coil manufactured by a winding machine in Examples 17 and 18 and Comparative Examples 9 and 10.

FIG. 3 is a cross-sectional view of a molded coil after impregnating and injecting the epoxy resin composition of the present invention.

FIG. 4 is a side view, partly in section, showing a configuration of a molded coil of Comparative Examples 9 and 10.

FIG. 5 is a perspective view, partially in section, showing a configuration of a molded coil of Example 19;

FIG. 6 is a side view of a coil manufactured by a winding machine in Example 19.

FIG. 7 is a cross-sectional view after filling a high-viscosity putty resin composition into one end of a coil in Example 19.

[Explanation of symbols]

1 ... winding, 1a ... conductor, 2 ... inner circumference insulation, 2a ... prepreg insulation, 3 ... outer circumference insulation, 3a ... prepreg insulation, 4 ... epoxy resin composition, 5 ... interlayer insulation, 6 ... winding Wire machine, 7… Flange, 8… Core, 9… Putty resin composition, 10… Void

Continued on the front page (72) Inventor Izumi Gumi 46-1, Tomioka, Nakajo-cho, Kitakanbara-gun, Niigata Prefecture Industrial Machinery Division, Hitachi, Ltd. F-term (reference) in the Industrial Equipment Division of Hitachi, Ltd.

Claims (6)

[Claims] 1. An epoxy resin composition comprising an epoxy resin, a curing agent and a silica filler, wherein said silica filler has a maximum particle size of 50 μm or less, and a cumulative frequency of a particle size of 0.82 μm or less.
The cumulative frequency of 10% or less, the particle size of 0.82 to 18.50 μm is 85% or more, and [1] the particle size of 0.82 to 2.31 μm, and [2] the particle size of 2.31
~ 6.54μm, [3] particle size 6.54 ~ 18.50μm frequency ratio
[1]: [2]: [3] = 1.00: 1.10 to 0.90: 1.00 to 0.80. 2. The epoxy resin is [A] bisphenol A.
2. The epoxy according to claim 1, wherein the epoxy resin and the [B] bisphenol F epoxy resin are [A]: [B] = 90 parts by weight: 10 parts by weight to 60 parts by weight: 40 parts by weight. Resin composition. 3. The epoxy resin composition comprising an epoxy resin, a curing agent and a silica filler, wherein the epoxy resin composition comprises [a] an epoxy resin composition containing an epoxy resin and a silica filler, and [b] at least a curing agent and a silica filler. 2. The epoxy resin composition according to claim 1, wherein the epoxy resin composition is formed into two liquids with a resin composition containing: 4. A molded coil which is obtained by casting an epoxy resin composition on a winding having an electric insulator coated on a conductor and then heat-curing the molded coil, wherein the epoxy resin composition contains an epoxy resin, a curing agent and a silica filler, The silica filler has a maximum particle size of 5
0 μm or less, the cumulative frequency of 0.82 μm or less is 10% or less, the cumulative frequency of 0.82 to 18.50 μm is 85% or more, and [1] 0.82 to 2.31 μm and [2] 2.31 to 6.54
μm, [3] particle size 6.54-18.50μm frequency ratio [1]:
[2]: [3] = 1.00: 1.10 to 0.90: 1.00 to 0.80. 5. A molded coil which is obtained by casting an epoxy resin composition on a winding having an electric insulator coated on a conductor and then heat-curing, wherein the epoxy resin composition contains an epoxy resin, a curing agent and a silica filler, In the epoxy resin, [A] bisphenol A type epoxy resin and [B] bisphenol F type epoxy resin are [A]: [B] = 90 parts by weight: 10 parts by weight to 60 parts by weight: 40 parts by weight. 5. The molded coil according to claim 4, wherein: 6. An epoxy resin composition comprising an epoxy resin, a curing agent and a silica filler, comprising: [a] an epoxy resin composition comprising an epoxy resin and a silica filler; and [b] at least a curing agent and a silica filler. And a resin composition containing
5. The molded coil according to claim 4, wherein the molded coil is liquefied.