JP3404304B2 - Epoxy resin composition and molded coil - Google Patents

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 molded coil, and more particularly to an epoxy resin composition having a low viscosity before curing, excellent workability in casting, and 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 Epoxy resin compositions conventionally applied to mold coils and the like have been used for the purpose of improving electrical properties, mechanical properties, crack resistance, etc., and further reducing costs.
A large amount of various fillers are mixed. However, when the epoxy resin composition contains a large amount of filler, the viscosity increases and casting workability is significantly reduced during the production of the mold coil. Furthermore, the epoxy resin composition does not easily penetrate into windings and the like. However, there is a problem that insulation reliability is reduced.

Therefore, a low-viscosity epoxy resin composition is required in order to improve casting workability and insulation reliability when producing a mold coil. Factors that affect 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 reducing the viscosity with a filler, for example, Japanese Patent No. 2623823 discloses an epoxy resin composition comprising an epoxy resin, a filler and a curing agent.
(A) A filler having an average particle size of 12 to 18 μm and a 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, and (B) an average particle size of 3 to 5 μm and a particle size distribution of 6 μm or less. A filler having a cumulative weight of 80% or more and a cumulative weight of 2 μm or less and 20% or less in the range of (A) / (B) = 75/25 to 25/75 (weight ratio) is disclosed. There is.

Further, Japanese Patent No. 2634663 discloses (A) spherical inorganic powder having an average particle diameter of 12 to 20 μm and a content of 7 to 15% by weight of 2 μm or less, 35 to 50% by weight of 12 μm or less, and 24 μm.
The following is a filler of 60 to 75% by weight, 45 μm or more is 6% by weight or less, and (B) crushed inorganic powder, having an average particle size of 8 to 25 μm, 2
(A) / (B) = 9 fillers with a content of less than μm of 5 to 15% by weight, 12 μm or less of 30 to 60% by weight, and 24 μm or less of 50 to 85% by weight.
It is disclosed that the mixture is mixed in the range of 1/5 to 5/5 (weight ratio) to achieve crack resistance and low viscosity.

As described above, conventionally, a mixture of two or more kinds of inorganic fillers having different particle diameters or particle shapes (combined use) is applied to the epoxy resin composition to reduce the viscosity. However, these methods require the work of controlling and mixing two or more kinds of particle size distributions. Further, from the viewpoint of castability for a thin wire portion such as a mold coil, the appearance of a lower viscosity epoxy resin composition is desired.

[0007] On the other hand, in Japanese Patent No. 2680029, a combination of an organic matrix resin and a coupling agent which chemically bonds with an inorganic filler or molecularly entangles each other to provide a low viscosity before curing and crack resistance and heat resistance after curing. It is disclosed to satisfy both. However, although the above-mentioned coupling agent is used in combination, the viscosity property and crack resistance are improved, but there is a problem that the heat resistance is newly lowered.

[0008]

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

[0009]

Means for Solving the Problems In the epoxy resin composition according to the present invention, the maximum particle size of the silica filler is 50 μm or less, and the cumulative frequency of particle size 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 provides 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 μm.
Cumulative frequency of 2 μm or less is 10% or less, particle size 0.82 to 18.50 μm
Has a cumulative frequency of 85% or more, and [1] particle size 0.82 to 2.
31μm, [2] grain size 2.31 ~ 6.54μm, [3] grain size 6.54 ~ 18.50
The frequency ratio of μm is [1]: [2]: [3] = 1.00: 1.10-0.90:
It is characterized by consisting of 1.00 to 0.80. Here, [A]: [B] = 90 parts by weight: 10 parts by weight to 60 parts by weight: 40 parts by weight of the epoxy resin is [A] bisphenol A type epoxy resin and [B] bisphenol F type epoxy resin. Is preferred. Further, the epoxy resin composition may be liquefied 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.

Further, according to the present invention, in a mold coil in which an epoxy resin composition is cast on a winding in which a conductor is coated with an electric insulator and then heat-cured, the epoxy resin composition is cast and then heat-cured. Was achieved by

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The particle size constitution of the silica filler shown in the present invention is defined from the result of measuring the particle size distribution by a laser diffraction particle size distribution measuring device MICROTRAC FRA type (manufactured by Nikkiso Co., Ltd.). That is, the measurement use range is set to 0.12 to 704 μm to measure the particle size distribution, and the cumulative frequency of particle size 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 to 0.24 μm, 0.24 to 0.29 μm, 0.29 to 0.34 μm, 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
%, The cumulative frequency of particle size 0.82 to 18.50 μm is 85% or more, and [1] frequency of particle size 0.82 to 2.31 μm is 0.82 to 0.97, 0.
97 to 1.16 μm, 1.16 to 1.38 μm, 1.38 to 1.64 μm, 1.64 to
Cumulative frequency of each frequency at 1.94 μm and 1.94 to 2.31 μm, and [2] Frequency of 2.31 to 6.54 μm is 2.31 to 2.75.
μm, 2.75 to 3.27 μm, 3.27 to 3.89 μm, 3.89 to 4.62 μm,
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.
4-7.78 μm, 7.78-9.25 μm, 9.25-11.00 μm, 11.00-
The cumulative frequency of each frequency at 13.08 μm, 13.08 to 15.56 μm and 15.56 to 18.50 μm.

It is not clear why the application of the silica filler having such a particle size distribution lowers the viscosity before curing, but the closest packing effective for lowering the viscosity is achieved. I guess. Examples of the silica filler include crystalline silica and fused silica from the viewpoint of production cost and particle size distribution.

The epoxy resin according to the present invention is, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F from the viewpoint of viscosity, mechanical strength and heat resistance. Type epoxy resins, bisphenol A and bisphenol A / F type epoxy resins obtained by reaction of bisphenol F with epichlorohydrin, alicyclic epoxy resins, novolac epoxy resins and other epoxy resins are used. The epoxy resin may be the above epoxy resin alone or 2
A mixture of two or more species can be used.

Particularly, the epoxy resin is composed of [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 about 160) from the viewpoint of viscosity, heat resistance and cost. About 180)
[A]: [B] = 90 parts by weight: 10 parts by weight to 60 parts by weight: preferably 40 parts by weight, and when the amount of the bisphenol A type epoxy resin component is large, the viscosity and the glass transition temperature (hereinafter referred to as Tg) are However, when the amount of the bisphenol F type epoxy resin component is large, the viscosity and Tg tend to decrease.

Examples of the curing agent shown in the present invention include acid anhydrides and amine compounds.

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. Etc. Among them, acid anhydrides have low viscosity and high Tg.
Is preferred, which is preferable. 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, an acid anhydride has an equivalent ratio of about 1: 1 (cured with respect to 100 parts by weight of the epoxy resin. 80-120 parts by weight of the agent),
For amine compounds, 10 to 6 per 100 parts by weight of epoxy resin
0 parts by weight is selected.

The curing accelerator is appropriately used depending on the use, improvement or improvement of properties of the epoxy resin composition of the present invention, 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, tertiary amines such as benzyldimethylamine and N-benzyldimethylamine is there. You may use these hardening accelerators individually or in mixture of 2 or more types. The amount of the curing accelerator compounded 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 depending on the use, improvement or improvement of characteristics 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 and a chemical compound. 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 the inorganic filler and entangled with the organic matrix resin.

Examples of the coupling agent represented by the above (1) include vinylethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane. Etc. Of these, γ-glycidoxypropyltrimethoxysilane is preferable. Also,
As the coupling agent represented by (2), monoalkoxy titanates, coordinate type titanates, chelate type titanates and trialkoxy titanates can be used. Among these titanate coupling agents, monoalkoxy titanates are preferable. 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 the heat resistance tends to decrease. For this reason, it is preferable that both are blended in an amount 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, the curing agent and the silica filler of the present invention is [a] an epoxy resin composition containing the epoxy resin and the silica filler.
[b] By separately preparing a resin composition containing at least a curing agent and a silica filler, it becomes possible to increase the amount of a curing accelerator used in the epoxy resin composition,
The epoxy resin composition according to the present invention can be rapidly cured. In this case, just before the casting operation, an appropriate amount of the [a] epoxy resin composition and the [b] resin composition may be weighed and mixed by a two-liquid mixing / discharging device or the like, and then cast.

A mold coil having excellent insulation reliability can be manufactured by casting the above-mentioned epoxy resin composition on a winding in which a conductor is coated with an electric insulator and then heating and curing it.

The present invention will be described below based on examples.

[0023]

[Examples 1 to 6 and Comparative Examples 1 to 5] Silica as a silica filler
A, Silica B, Silica C, Silica 1, Silica 2, Silica 3, Silica 4, Silica 5 (Tatsumori Co., Ltd., crystalline silica) maximum particle size, cumulative frequency in each particle size and frequency ratio 1
Shown in.

[0024]

[Table 1]

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

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

[0027]

[Table 2]

Then, vacuum degassing (10%) was performed using a universal mixing stirrer (manufactured by Dalton Co.) in which each material was adjusted to about 90 ° C.
Pa) while stirring for about 30 minutes to prepare the epoxy resin compositions of Examples 1-6. The viscosity, casting time, and glass transition temperature (abbreviated as Tg) of the cured product of the produced epoxy resin composition are also shown in Table 2.

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

Further, the Tg was measured by heating the above epoxy resin composition at 90 ° C. for 17 hours and then at 170 ° C. for 15 hours to obtain a cured product, which was a thermophysical tester TM-1500 type (Vacuum Riko Co., Ltd.). Manufactured by K.K.) at a heating rate of 2.0 ° C./min.

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

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

[0033]

[Table 3]

The cumulative frequency of silica filler particles having a particle size of 0.82 μm or less exceeds 10% (Comparative Examples 1 and 3) or a particle size of 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 2.31 to 6.54 μm is
The viscosity increased to about 3.0 Pa · s 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. Even if the cumulative frequency of particle sizes of 0.82 μm or less is 10% or less and the cumulative frequency of particle sizes of 0.82 to 18.50 μm is 85% or more, the frequency ratio in the particle size range 2.31 to 6.54 μm 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 shortened to about 1/2 of that of the comparative example, so that the casting workability can be improved.

[0037]

[Examples 7 to 11 and Comparative Examples 6 to 8] Silica D, silica E, silica F, and silica, which are silica fillers, were prepared in the same manner as in Example 1.
The particle size distribution of 6, silica 7 and silica 8 (Crystalline silica manufactured by Tatsumori Co., Ltd.) was measured. Table 4 shows the maximum particle size, the cumulative frequency in each particle size, and the frequency ratio.

[0038]

[Table 4]

Using these silica fillers, the epoxy resin, curing agent and curing accelerator were weighed in the prescribed amounts shown in Table 5,
An epoxy resin composition was produced in the same manner as in Example 1. The viscosity, casting time and Tg of the cured product of the produced epoxy resin composition are also shown in Table 5.

[0040]

[Table 5]

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

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

As described above, since the epoxy resin composition of this example has a low viscosity and the casting time can be shortened to about 1/2 of that of the comparative example, the effect of improving the casting workability was obtained.

[0044]

Examples 12 to 15 Using the same silica A, curing agent and curing accelerator as in Example 1, bisphenol A which is an epoxy resin
Type epoxy resin (Asahi Chiba Co., Ltd., trade name AER-260)
The compounding ratio of bisphenol F type epoxy resin and bisphenol F 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 a 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. or less. According to this example, 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, A low viscosity and a high Tg were obtained.

[0047]

Example 16 Next, an epoxy resin composition shown in the present invention was prepared.
An explanation is given of an example in which [a] an epoxy resin composition comprising an epoxy resin, a coupling agent and a silica filler, and [b] a resin composition comprising a curing agent, a coupling agent, a curing accelerator and a silica filler are liquefied. To do.

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

Thereafter, the [a] epoxy resin composition and
[b] The resin composition was prepared in the same manner as in Example 16 by mixing each metered resin composition in the mixing section using an automatic metering / discharging device (Naka Liquid Control Co., Ltd., trade name Tristan TVE-EL). The epoxy resin composition of was obtained. The gelling time, viscosity, and Tg of the cured product obtained by heating in the same manner as in Example 1 were measured in the case of the epoxy resin composition of Example 16 and the one-component solution shown in Example 3. The results are shown in Table 7.

[0050]

[Table 7]

The gelation time was measured by using a gelation time measuring device (manufactured by Toshiba Corporation, model SFO-4M) and weighing about 8 ml of the epoxy resin composition in a test tube (18φ, 18 ml).
The test was performed by immersing in a silicone oil bath adjusted to ° C. As a result, the gelling time of the epoxy resin composition of Example 16 was
Whereas 90 ° C. for 170 minutes and 100 ° C. for 88 minutes, the one-part epoxy resin composition of Example 3 was 90 ° C. for 380 minutes and 100 ° C. for 200 minutes.
It was a minute.

Further, the viscosity of the two-liquefied epoxy resin composition of this Example 16 and the Tg of the cured product were almost the same values as those of the one-liquid Example 3. The one-component epoxy resin composition of Example 3 starts the curing reaction when the epoxy resin and the curing agent are mixed, and the reaction is accelerated by adding the curing accelerator. Therefore, there is a time constraint from the mixing of the materials to the casting work.

On the other hand, in Example 16, since the epoxy resin composition [a] and the resin composition [b] were liquefied in advance, the curing reaction would not occur unless both were mixed. Therefore, the storage of the epoxy resin composition can be made virtually indefinite by liquefying it, and the gelation time can be shortened to 1/2 by increasing the amount of the curing accelerator, and rapid curing can be achieved. .

[0054]

Example 17, Comparative Example 9 An example of producing a molded coil using the epoxy resin composition of the present invention will be described. FIG. 1 is a perspective view, partly in section, showing the structure of the molded coil of the seventeenth embodiment. In this molded coil, the inner and outer circumferences were respectively molded with prepreg insulators 2a and 3a to form an inner circumference insulating layer 2 and an outer circumference insulating layer 3, and an epoxy resin composition 4 similar to that used in Example 4 was wound inside the coil. It is produced by impregnating and injecting the inside of the wire 1 and then heating and curing.

As shown in FIG. 2, the method of manufacturing the molded coil in this embodiment is such that the prepreg insulator is attached to the core 8 of the winding machine 6.
2a is wound so as to be in close contact with the leakage preventing flange 7 of the epoxy resin composition, and the winding 1 is wound thereon.

As shown in FIG. 3, the winding 1 is formed by alternately winding a conductor 1a and an interlayer insulator 5. In FIG. 2, after winding the winding 1, a prepreg insulator 3a is further wound on the upper surface of the winding so that one end of the winding is closely attached to the flange 7, and then 170 ° C.
Heat for 4 hours to dry winding 1 and prepreg insulation 2a, 3a
Cure.

As shown in FIG. 3, in the space surrounded by the inner peripheral insulating layer 2 and the outer peripheral insulating layer 3 with the flange 7 facing downward and in the space surrounded by the conductor 1a and the interlayer insulating material 5, the same as in the fourth embodiment. Impregnating and injecting a different epoxy resin composition in about 10 minutes, heating and curing at 90 ° C for 17 hours, and then removing the flange 7 and the core 8 and further 170
After heat-curing at 15 ° C. for 15 hours, it was cooled to room temperature over about 12 hours to prepare a mold coil. Similarly, the mold coil of Comparative Example 9 was produced in the same manner as in Example 17, by impregnating the winding with the same epoxy resin composition as in Comparative Example 3 in about 15 minutes.

Since the mold coil of this Example 17 uses a low-viscosity epoxy resin composition, there are no voids (air bubbles) in the winding portion as shown in FIG. 3, and the mold coil has about 10 kV. As a result of applying a voltage and performing a withstand voltage test,
There was no occurrence of corona.

On the other hand, since the molded coil of Comparative Example 9 uses the epoxy resin composition having a high viscosity,
Voids (air bubbles) were formed in the winding portion as shown in (4), and as a result of the withstand voltage test performed in the same manner as in Example 17, corona was generated.

According to this example, since the epoxy resin composition had a low viscosity before curing, the casting time during coil preparation could be shortened from about 15 minutes to about 10 minutes as compared with Comparative Example 9, and the curing After that, voids were not formed in the winding part of the mold coil and the generation of corona could be suppressed, so that the insulation reliability could be improved.

[0061]

Example 18, Comparative Example 10 In the same manner as in Example 17, a winding provided with 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 wire in about 10 minutes, and after heating and curing at 90 ° C. for 17 hours, the flange 7 and the core 8 were removed, and further 170 ° C.
After heating and curing for 15 hours, it was cooled to room temperature over about 12 hours to produce the molded coil of the present invention. Similarly, a 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 the produced mold coils, it was confirmed whether or not there was a crack.
As a result, since the mold coil of this Example 18 uses the epoxy resin composition having a high Tg, the coil temperature rose to about 135 ° C. by energization, but there was no crack. On the other hand, since the mold coil of Comparative Example 10 uses the low Tg epoxy resin composition, the coil temperature is about 135 due to the 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 the temperature rise of the coil during energization, so that the insulation reliability could be improved.

[0064]

[Embodiment 19] FIG. 5 is a perspective view, partly in section, showing the structure of the molded coil of the present embodiment. In this molded coil, the inner and outer circumferences are respectively molded with prepreg insulators 2a and 3a to form an inner circumference insulating layer 2 and an outer circumference insulating layer 3, and a high-viscosity putty-like resin composition 9 is further formed on one end of the coil. After the filling and curing, the epoxy resin composition 4 similar to that in Example 16 was impregnated and injected into the inside of the winding 1, and then cured by heating.

As shown in FIG. 6, the method of manufacturing the molded coil in this embodiment uses a prepreg insulator on the core 8 of the winding machine 6.
2a is wound and winding 1 is wound on it. As shown in FIG. 7, the winding 1 is formed by alternately winding a conductor 1a and an interlayer insulator 5.

In FIG. 6, after winding the winding 1, the prepreg insulator 3a is further wound on the upper surface thereof, and one end of the coil is filled with the high-viscosity putty resin composition 9 as shown in FIG. Then, the winding 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 portion filled with the putty-like resin composition 9 downward as shown in FIG.
A resin composition comprising [a] bisphenol A / F type epoxy resin, silica A and a silane coupling agent similar to 6
[b] Methylhexahydrophthalic anhydride, silica A, 1- (2
-Cyanoethyl) -2-ethyl-4-methylimidazole and an epoxy resin composition 4 obtained by mixing a resin composition comprising a titanate coupling agent with an automatic metering and discharging device.
The space surrounded by the inner insulation layer 2 and the outer insulation layer 3 and the winding 1
The inner space was impregnated and injected 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 mold coil.

According to this example, since the epoxy resin composition has a low viscosity before curing, the casting work time during coil production can be shortened 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 mold coil,
Corona generation can be suppressed and insulation reliability is improved. Furthermore,
By applying a two-liquefied epoxy resin composition, the gelling time can be set to about 1/2 and the rapid curing property can be achieved, which can reduce the heat curing time of the mold coil from 32 hours to 12 hours. As a result, the time required to manufacture the mold coil could be reduced by more than half.

[0068]

According to the present invention, in the epoxy resin composition, the maximum particle size is 50 μm or less, the cumulative frequency of 0.82 μm or less is 10% or less, and the 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
The frequency ratio of 2.31 ~ 6.54 μm, [3] particle size 6.54 ~ 18.50 μm
[1]: [2]: [3] = 1.00: 1.10 to 0.90: 1.00 to 0.80 By applying a silica filler, it is possible to lower the viscosity before curing and improve casting workability. You can 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: By setting the content in the range of 40 parts by weight, an epoxy resin composition having low viscosity before curing and excellent heat resistance after curing can be obtained.

Furthermore, the epoxy resin composition is an epoxy resin composition containing [a] an epoxy resin and a silica filler.
[b] By liquefying into a resin composition containing at least a curing agent and a silica filler, it is possible to increase the amount of a curing accelerator that is appropriately used in an epoxy resin composition, and a rapid curing property is achieved. The manufacturing time of the coil can be shortened.

A molded coil having excellent insulation reliability can be obtained by casting an electric insulating material on a winding coated with a conductor using the epoxy resin composition described above and then heating and curing.

[Brief description of drawings]

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

FIG. 2 is a side view of coils 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 impregnation and injection of the epoxy resin composition of the present invention.

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

FIG. 5 is a perspective view, partly in section, showing the configuration of a mold 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 one end portion of a coil in Example 19 with a high-viscosity putty-like resin composition.

[Explanation of symbols]

1 ... Winding wire, 1a ... Conductor, 2 ... Inner circumference insulator, 2a ... Prepreg insulator, 3 ... Outer circumference insulator, 3a ... Prepreg insulator, 4 ... Epoxy resin composition, 5 ... Interlayer insulator, 6 ... Winding Wire machine, 7 ... Flange, 8 ... Core, 9 ... Putty resin composition, 10 ... Void

Continuation of front page (72) Tomohiro Kaizu 46-1, Tomioka, Nakajo-cho, Kitakanbara-gun, Niigata Prefecture Hitachi Industrial Co., Ltd. (56) Reference JP-A-5-331296 (JP, A) JP-A-2 -263857 (JP, A) JP-A-9-296073 (JP, A) JP-A-9-124837 (JP, A) JP-A-4-345640 (JP, A) JP-A-3-197529 (JP, A) ) JP-A-6-200125 (JP, A) Patent 2623823 (JP, B2) Patent 2634663 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 63/00-63/10 H01B 3/40 H01F 27/32

Claims (6)

(57) [Claims] 1. An epoxy resin composition containing an epoxy resin, a curing agent and a silica filler, wherein the silica filler has a maximum particle size of 50 μm or less, and a cumulative frequency of 0.82 μm or less.
Accumulation frequency of 10% or less, particle size 0.82-18.50μm is 85% or more, and [1] particle size 0.82-2.31μm, [2] particle size 2.31
~ 6.54μm, [3] particle size 6.54 ~ 18.50μm frequency ratio
[1]: [2]: [3] = 1.00: 1.10-0.90: 1.00-0.80, which is an epoxy resin composition. 2. The epoxy resin is [A] bisphenol A.
2. The epoxy according to claim 1, wherein the type epoxy resin and the [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. Resin composition. 3. An epoxy resin composition containing the epoxy resin, a curing agent and a silica filler, [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, which is obtained by liquefying into a resin composition containing 4. A molded coil, which is obtained by casting an epoxy resin composition on a winding having a conductor coated with an electric insulator and then heat curing the epoxy resin composition, 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
0μm or less, the cumulative frequency of particle size 0.82μm or less is 10% or less, the cumulative frequency of particle size 0.82 to 18.50μm is 85% or more, and [1] particle size 0.82 to 2.31μm, [2] particle Diameter 2.31 ~ 6.54
The ratio of the frequency of μm, [3] particle size 6.54 to 18.50 μm is [1]:
[2]: [3] = 1.00: 1.10 to 0.90: 1.00 to 0.80, which is a molded coil. 5. A molded coil, which is obtained by casting an epoxy resin composition onto a winding having a conductor coated with an electrical insulator and then heat curing the epoxy resin composition, 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. The molded coil according to claim 4, which is characterized in that. 6. An epoxy resin composition containing the epoxy resin, a curing agent and a silica filler, [a] an epoxy resin composition containing an epoxy resin and a silica filler, and [b] at least a curing agent and a silica filler. And a resin composition containing 2
The molded coil according to claim 4, wherein the molded coil is liquefied.