JP2001288334A - Molded coil and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a molded coil scarcely causing a cracking and excellent in insulation reliability by applying an epoxy resin composition improved in modulus of elasticity at a high temperature thereto and to provide a method for producing the molded coil. SOLUTION: This molded coil and the method for producing the coil are characterized in that the epoxy resin composition comprises an epoxy resin, a specific organosilicon compound, a curing agent of an acid anhydride and an inorganic filler as essential components in the molded coil obtained by carrying out mold curing of a coil prepared by coating a conductor with an electrical insulating material by the epoxy resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel molded coil and a method of manufacturing the same.

[0002]

2. Description of the Related Art A molded coil is produced by casting an epoxy resin composition onto a winding having an electric insulator coated on a conductor and then curing the same. The mold coil is assembled together with an iron core or the like and used in a mold transformer. When the mold transformer operates, copper loss or iron loss occurs, so that the mold coil generates heat and becomes high temperature. Therefore, if the mechanical properties of the epoxy resin composition deteriorate at high temperatures, cracks (cracks) will occur in the molded coil when stresses such as vibration during equipment operation and electromagnetic force during a short circuit occur, causing trouble. Become. Therefore, in order to prevent cracks and the like at high temperatures in the molded coil, it is important to improve the mechanical properties of the epoxy resin composition particularly at high temperatures.

Various methods have been disclosed to improve the mechanical properties of the epoxy resin composition at high temperatures. JP-A-7-331069 and JP-A-7-331070 disclose a method of dispersing a metal oxide sol in a polyamideimide resin, and JP-A-8-100107 discloses a method in which a metal alkoxide is added to an epoxy resin to perform condensation polymerization. Japanese Patent Application Laid-Open No. 9-216938 discloses a method in which a metal alkoxide is swollen in a phenol resin and then subjected to polycondensation.
Further, Japanese Patent Application Laid-Open No. 9-291131 reports a method of adding a metal alkoxide to a polyurethane resin and condensing it by a sol-gel method. However, these methods have a problem that the curing reaction involves water generation due to polycondensation, and swelling occurs at the interface of the composite material. Further, in these techniques, no consideration is given to prevention of peeling or cracks occurring at the interface of the composite material due to a temperature change.

Japanese Patent Application Laid-Open No. Hei 8-199045 discloses that in order to reduce the generation of thermal stress, an alkoxysilane and water are added to an epoxy resin dissolved in an organic solvent to hydrolyze the alkoxy group of the alkoxysilane. After removing the solvent,
A method of curing a resin and dehydrating a hydroxyl group by heating is disclosed. However, this method also has problems in the generation of water during heat curing and the adhesion at the interface of the composite material at high temperatures.

[0005] As described above, the prior art is a method of forming a composite by curing a mixture of a thermosetting resin, an organosilicon compound and water together with a base material such as a metal or a ceramic. And alcohol is generated. Due to the water and alcohol, the metal base material is corroded, swells at the interface between the base material and the resin, and cracks and peels occur in the molded product. Furthermore, no consideration is given to prevention of swelling or cracks occurring at the interface between the base material and the resin due to a temperature change.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a molded coil having a high elastic modulus at a high temperature and excellent insulation reliability in which cracks and the like are less likely to occur, and a method of manufacturing the same.

[0007]

SUMMARY OF THE INVENTION The present invention provides an epoxy resin composition in which an epoxy resin, a specific organosilicon compound, an acid anhydride curing agent, and an inorganic filler are mixed to provide a thermal stress at high temperatures. Thus, there is provided a molded coil having excellent insulation reliability and a method of manufacturing the same, since cracks due to cracks and the like are less likely to occur.

That is, the present invention provides a molded coil obtained by molding a coil having an electric insulator coated on a conductor with an epoxy resin composition and then curing the epoxy resin composition, wherein the epoxy resin composition comprises an epoxy resin; Represented by the following general formula (1) or (2)

[0009]

Embedded image

[0010]

Embedded image

Wherein R is an organic group containing a functional group that causes an addition reaction with the acid anhydride curing agent of the epoxy resin, n is from 0 to 3, and X is H, CH ₃ , C ₂ H
₅ ), and a cured product of an epoxy resin composition obtained by mixing the acid anhydride curing agent and an inorganic filler.

The epoxy resin composition used for the molded coil is constantly subjected to stresses such as electromagnetic force and the like due to use under various conditions from room temperature to high temperature.
It is important to secure an elastic modulus so that deformation of the epoxy resin composition does not occur due to a load of an external force at a high temperature. Here, in order to improve the mechanical properties at high temperatures and to reduce the change in physical properties due to the temperature change, a method of adding a filler of several μm to 10 nm to the epoxy resin composition is usually adopted. However, in this method, since the change in the physical properties of the resin composition itself is not suppressed, the physical properties of the epoxy resin composition to which the filler is added as a composite material are similar to those of the epoxy resin composition without the filler alone. Make a change. Therefore, it is considered important to add a substance having a small change in physical properties with respect to the temperature change at the molecular level in order to suppress the mechanical properties of the epoxy resin composition at high temperatures and the change in physical properties with respect to the temperature change. According to the present invention, a Si material having a small change in physical properties with respect to a temperature change and having stable mechanical properties is provided.
The O ₂ skeleton is preferably formed uniformly at a molecular level of 5 nm or less, and is bonded to the epoxy resin by providing a functional group that is covalently bonded to the epoxy resin at the end of the SiO ₂ skeleton to form an epoxy resin composition. This technology improves mechanical properties at high temperatures.

Further, the present invention relates to a method for manufacturing a molded coil in which a mixed solution of an epoxy resin composition is injected into a winding in which an electric insulator is coated on a conductor and molded with a cured product of the epoxy resin composition. Equation (3) or (4)

[0014]

Embedded image

[0015]

Embedded image

(Where R is an organic group containing a functional group that causes an addition reaction with an acid anhydride curing agent of an epoxy resin, and R ¹ and R ² are a methyl group or an ethyl group) And a step of producing a mixed solution of an organosilicon compound by heat-treating a mixed solution containing water and a hydrolysis catalyst; and a step of producing an epoxy mixed solution by heat-treating by adding an epoxy resin to the mixed solution. And a step of adding an acid anhydride curing agent, a curing accelerator, and an inorganic filler to the epoxy mixed solution, heating and mixing, and then injecting the mixed solution and heating and curing the mixed solution. .

The aforementioned organosilicon compound (where R is an organic group containing a functional group that causes an addition reaction with an acid anhydride curing agent of the epoxy resin, and R ¹ and R ² are a methyl group or an ethyl group. The amount of water to be added to the mixed solution of (3) is preferably 3 to 0.02 times the molar amount of the organosilicon compound. Since the cured product can maintain a high elastic modulus even at a high temperature, deformation of the epoxy resin composition due to a load applied from the outside can be suppressed. In addition, since the heat treatment is performed before the addition of the acid anhydride curing agent as described above, generation of by-products such as water and alcohol during the heat curing after the addition of the acid anhydride curing agent is slight. Therefore, even when a molded coil is manufactured using the epoxy resin composition together with the conductor and the insulating film, swelling and cracking are less likely to occur at the interface between the conductor or the insulating film and the epoxy resin composition.

Further, when the epoxy resin composition is cured, the chemical shift of ²⁹ Si-NMR is from -53 ppm to -7 ppm.
The integrated value of the peak at 2 ppm is 1 to 50 times the integrated value of the peak at -40 ppm to -52 ppm. This indicates that the organosilicon compound formed a bond of Si-O-Si to increase the molecular weight. However, since the organic silicon compound had good compatibility with the epoxy resin, it was transparent without solid particles.

The above-mentioned organosilicon compound (where R is an organic group containing a functional group that causes an addition reaction with an acid anhydride curing agent of an epoxy resin, and R ¹ and R ² are a methyl group or an ethyl group. ) And water is preferably subjected to a heat treatment at 60 ° C to 160 ° C for 1 to 10 hours, and a step of adding an acid anhydride curing agent for the epoxy resin to the heat-treated mixture. It is in.

Here, in the present invention, in the curing process of the resin, it is important to suppress the generation of by-products in order to prevent swelling and cracks at the interface between the epoxy resin composition and different materials such as conductors. . The reason for using epoxy resin as the resin is to eliminate the generation of by-products during curing. The heat treatment of a mixed solution of an epoxy resin and an organosilicon compound and water is performed in advance, and then the addition of an acid anhydride curing agent to the mixed solution involves heating and curing the epoxy resin composition. Consideration is given to suppressing the generation of water and alcohol which are generated as by-products before. In order to obtain an epoxy resin composition in which the generation of by-products such as water and alcohol during the curing reaction is minimized, the inventors of the present invention require a mixture of an epoxy resin, an organosilicon compound and water, It has been found that it is effective to perform a heat treatment in advance. Here, the organosilicon compound has a functional group that causes an addition reaction with an acid anhydride curing agent of the epoxy resin. According to this feature, before adding the acid anhydride curing agent, the mixture containing the epoxy resin, the organosilicon compound and water is subjected to a heat treatment, so that the cured product of the epoxy resin composition of the present invention can be used at high temperatures. Since the change in elastic modulus is small, thermal stress is hardly generated, and cracks are hardly generated. Further, since a high elastic modulus can be maintained even at a high temperature, deformation of the epoxy resin composition due to a load applied from the outside can be suppressed. In addition, since the generation of by-products such as water and alcohol during curing is very small, even if a molded coil is manufactured using an epoxy resin composition and a conductor, insulating film, etc., the conductor and the epoxy resin composition Swelling at the interface with the object and cracks and the like in the molded coil are less likely to occur.

The epoxy resin shown in the present invention is a resin which is solidified by three-dimensional crosslinking by heating.
There is no particular limitation, and known ones can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol A / F type epoxy resin, novolak type epoxy resin, alicyclic type epoxy resin and the like can be mentioned. Epoxy resins can be used alone or in combination of two or more.

The acid anhydride curing agent shown in the present invention is a known compound which is generally used. Further, from the viewpoints of castability and physical properties of the cured product, for example, phthalic anhydride, hexahydrophthalic anhydride, And methylhexahydrophthalic anhydride.

In the present invention, an inorganic filler is added to further improve the mechanical properties and reduce the coefficient of linear expansion. Examples of the inorganic filler include crystalline silica and fused silica from the viewpoints of various physical properties before and after curing of the epoxy resin composition, material costs, production costs, and the like. The curing accelerator is appropriately used in accordance with the use of the epoxy resin composition of the present invention, improvement or improvement of the properties, and the like.
-Methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-
There are imidazoles such as (2-cyanoethyl) -2-ethyl-4-methylimidazole and epoxy adductimidazole compounds, and tertiary amines such as benzyldimethylamine and N-benzyldimethylamine. These curing accelerators may be used alone or in combination of two or more.

Further, other known coupling agents, release agents, coloring agents, plasticizers, diluents, flexibilizers, various rubber-like substances, photosensitizers, etc. are appropriately added according to the purpose and use. Can be used.

In the present invention, examples of the organosilicon compound represented by the general formula 3 include the following organosilicon compounds having an epoxy group represented by the following formulas 5 and 6.

[0026]

Embedded image

[0027]

Embedded image

Furthermore, in the present invention, as an example of the organosilicon compound represented by (general formula 4), there is an organosilicon compound represented by the following (formula 7).

[0029]

Embedded image

By performing the heat treatment in the state of the mixture of the epoxy resin, the organosilicon compound and water as described above,
The higher the dispersibility between the epoxy group and be easily generated by an organosilicon compound of about oligomer, ²⁹ Si-
It was found from the chemical shift of NMR.

[0031]

Embedded image

Or

[0033]

Embedded image

(Where R is an organic group containing a functional group that causes an addition reaction with an acid anhydride curing agent of an epoxy resin, and R ¹ and R ² are a methyl group or an ethyl group) Has a chemical shift of -4 of ²⁹ Si-NMR.
Absorption appears between 1 ppm and -44 ppm.

[0035]

Embedded image

The chemical shift of ²⁹ Si-NMR of Si having one Si--O--Si bond as shown in FIG.
Absorption appears between m and -52 ppm.

[0037]

Embedded image

The chemical shift of ²⁹ Si-NMR of Si having two Si—O—Si bonds as shown in FIG.
Absorption appears between m and -63 ppm.

[0039]

Embedded image

The chemical shift of ²⁹ Si-NMR of Si having three Si—O—Si bonds as shown in FIG.
Absorption appears between m and -72 ppm.

The epoxy resin composition of the present invention, which was previously heat-treated in the state of a mixture of an epoxy resin, an organosilicon compound and water, and then heat-cured by adding an acid anhydride curing agent, was subjected to ²⁹ Si-NMR chemistry. When you measure the shift,
Absorption appears between -40 ppm and -75 ppm. Of these,
The integrated value of absorption from 53 ppm to -75 ppm is -40 ppm to-
Since the value was larger than the integrated value of the absorption at 52 ppm, it was found that the organosilicon compound in the resin formed a bond of Si—O—Si to form a molecule having a size of an oligomer. As described above, even if the molecular weight of the organosilicon compound is increased, the epoxy resin composition has good compatibility with the epoxy resin, and thus the epoxy resin composition before curing is transparent without generating solid particles.

The epoxy resin composition which does not contain an acid anhydride curing agent which has been subjected to a heat treatment in advance in the state of a mixture of an epoxy resin, an organosilicon compound and water as in the present invention is not mixed with the epoxy resin. When water is added to the organosilicon compound of the general formula (3) or (general formula 4) and heat-treated, an epoxy resin monomer is not formed,
Since the organosilicon compound solidifies or becomes a high-viscosity solution of 10,000 poise or more, even if it is mixed with the epoxy resin after the above-mentioned heat treatment, it cannot be uniformly mixed at the molecular level.

The above-described epoxy resin composition is cast into a winding in which an electrical insulator is coated on a conductor, and then cured by heating. As a result, a cured product having an improved elastic modulus at a high temperature can be obtained. A molded coil in which cracks are less likely to be produced.

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Example 1 and Comparative Example 1) The procedure for preparing the epoxy resin composition used in this example and the physical properties of the cured product will be described. As shown in Table 1, the composition of the epoxy resin composition for this example was as follows: the organosilicon compound was 3-glycidoxypropyltrimethoxysilane (manufactured by Chisso Corporation, trade name: SILAACE S510), and the epoxy resin was bisphenol A type epoxy. Resin (AER-260, manufactured by Asahi Ciba Co., Ltd.), and acid anhydride curing agent is methylhymic anhydride (MHAC-, manufactured by Hitachi Chemical Co., Ltd.)
P), the curing accelerator is epoxy adduct imidazole (manufactured by Yuka Shell Co., Ltd., trade name P-200), and the inorganic filler is crystalline silica (Tatsumori Corporation, trade name C-BASE-).
It was prepared by the following procedure using 1) and the like.

FIG. 1 is a flowchart of the preparation of the epoxy resin composition of this example.

(1) Organosilicon compound, water and tin dibutyl dilaurate as a catalyst for hydrolysis (Wako Pure Chemical Industries, Ltd.)
Weighed, mixed and left at room temperature for at least one day to prepare an organosilicon mixed solution. (2) The epoxy resin is weighed and mixed with the organosilicon mixed solution of (1). (3) After the mixing of (2), heat treatment is performed at 150 ° C. for 4 hours to prepare an epoxy mixed solution. (4) After cooling the epoxy mixed solution of (3) to room temperature, an acid anhydride curing agent, a curing accelerator, crystalline silica and the like are weighed and mixed at about 90 ° C.

The mixed solution obtained in the above (4) is the epoxy resin composition used in this embodiment.

On the other hand, the epoxy resin composition for Comparative Example 1 was prepared by weighing the epoxy resin, the acid anhydride curing agent, the curing accelerator, the crystalline silica, etc. shown in Table 1 and mixing them at about 90 ° C. Produced.

[0049]

[Table 1]

The above-mentioned epoxy resin compositions for the present example and comparative example 1 were injected into a mold, and then heated at 100 ° C. for 5 hours + 17 hours.
The composition was cured by heating at 0 ° C. for 7 hours to prepare a cured product.
The storage elastic modulus and glass transition temperature (hereinafter Tg) of these cured products
Are shown in Table 1. The storage elastic modulus was measured using a dynamic viscoelasticity device PVE Rheospectler (manufactured by Rheology Co., Ltd.) under the conditions of a heating rate: 2 ° C./min., A frequency: 10 Hz, a distance between chucks: 20 mm, and a displacement amplitude: 5 μm. I went in.
The Tg was measured using a thermophysical tester TM-1500 (manufactured by Vacuum Riko Co., Ltd.) under the condition of a heating rate of 2 ° C./min.

First, as the physical properties of the cured product of the epoxy resin composition, the storage elastic modulus at 50 ° C. for this example is 15 GPa, which is almost the same as that for Comparative Example 1 (14 GPa), but 220 ° C.
Has a storage elastic modulus of 1.5 GPa for Comparative Example 1 (0.4 GPa
About three times higher than a). Next, the Tg of the epoxy resin composition for this example is 155 ° C., which is almost the same as that for Comparative Example 1 (151 ° C.). In this example, the integrated value of the peak from -53 ppm to -72 ppm of the chemical shift of ²⁹ Si-NMR is 1 to the integrated value of the peak from -40 ppm to -52 ppm.
0.5 times, and the organosilicon compound was an oligomer-level molecule.

FIG. 2 is a partially sectional perspective view showing the structure of the molded coil of this embodiment. An example in which the above-described epoxy resin composition is applied to manufacture the molded coil of the present example will be described. 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 epoxy resin composition 4 of the present embodiment is wound inside the coil 1 It is manufactured by impregnating and injecting into the inside of the substrate and then heating and curing.

FIG. 3 is a side view of a coil manufactured by a winding machine. As shown in FIG. 3, the method of manufacturing a molded coil in this embodiment is as follows. A prepreg insulator 2a is wound around a core 8 of a winding machine 6 so as to be in intimate contact with a flange 7 for preventing leakage of an epoxy resin composition. The winding 1 is wound thereon.

FIG. 4 is a cross-sectional view of the molded coil after the impregnation and injection of the epoxy resin composition. As shown in FIG. 4, the winding 1 has a conductor 1a and an interlayer insulator 5 wound alternately.
In FIG. 3, after winding of the winding 1, a prepreg insulator 3a is further wound on the upper surface of the winding 1 so that one end thereof is in close contact with the flange 7, and then heated at 170 ° C. for 4 hours. Drying and curing of the prepreg insulators 2a and 3a are performed. As shown in FIG. 4, the epoxy resin for the first embodiment is provided in a space surrounded by the inner circumferential insulating layer 2 and the outer circumferential insulating layer 3 with the flange 7 down and a space surrounded by the conductor 1a and the interlayer insulator 5. After impregnating and injecting the composition and heating and hardening at 100 ° C. for 5 hours, the flange 7 and the core 8 were removed.
After heating and curing for a time, the mold coil was prepared by cooling to room temperature over about 12 hours. Similarly, the molded coil of Comparative Example 1 was manufactured by impregnating and injecting the epoxy resin composition for Comparative Example 1 into the winding in the same manner as in this example.

A short-circuit test (test for simulating the current generated at the time of a short-circuit accident) of the molded coil of this embodiment and Comparative Example 1 was performed to confirm the presence or absence of cracks. As a result, since the molded coil of this example uses an epoxy resin composition having improved mechanical properties (storage elastic modulus) at high temperatures, the temperature of the molded coil rises to about 150 ° C. by energization, and the electromagnetic force also increases. It occurred but no crack occurred. On the other hand, the epoxy resin composition for Comparative Example 1 does not consider mechanical properties at high temperature at all.
Cracks occurred when the temperature of the molded coil was raised to about 150 ° C. by energization and at the same time an electromagnetic force was generated.

According to the present embodiment, the epoxy resin composition has an improved elastic modulus at a high temperature after curing as compared with the epoxy resin composition for Comparative Example 1, so that stress such as electromagnetic force is applied to the mold coil. Even if it did, no cracking occurred, and insulation reliability could be improved.

(Example 2 and Comparative Example 2) As shown in Table 2, the epoxy resin composition for this example was such that the organosilicon compound was 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (Chisso Corporation). (Trade name: SILA ACE S530), epoxy resin is bisphenol A / F type epoxy resin (trade name: PY-30, manufactured by Ciba-Geigy Corporation)
2-2), the acid anhydride curing agent is methylhymic anhydride,
When the curing accelerator is 1- (2-cyanoethyl) -2-ethyl-4
-Methylimidazole (Shikoku Chemicals Co., Ltd., trade name 2
E4MZ-CN) and an inorganic filler using crystalline silica or the like was used in the same manufacturing procedure as in Example 1. Similarly, the epoxy resin composition for Comparative Example 2 was weighed and mixed at about 90 ° C. with the epoxy resin, acid anhydride curing agent, curing accelerator, crystalline silica, and the like shown in Table 2. For the epoxy resin composition for Example 2 and the epoxy resin composition for Comparative Example 2, cured products were prepared in the same manner as in Example 1, and the properties of the cured products were measured.

First, as the physical properties of a cured product of the epoxy resin composition, the storage elastic modulus at 50 ° C. for this example is 14 GPa, which is almost equal to that for comparative example 2 (13 GPa).
° C storage elastic modulus of 1.2 GPa and that for Comparative Example 2 (0.4 G
3 times higher than Pa). Next, the Tg of the epoxy resin composition for this example is 151 ° C., which is almost the same as that for Comparative Example 1 (150 ° C.). In the present example, the integrated value of the peak from -53 ppm to -72 ppm of the chemical shift of ²⁹ Si-NMR is-
10. For the integrated value of the peak from 40 ppm to -52 ppm.
The number was 5 times, and the organosilicon compound was an oligomer-level molecule.

[0059]

[Table 2]

Next, the molded coil of the present example was manufactured in the same manner as in Example 1 by applying the above-described epoxy resin composition for the present example. Further, the molded coil of Comparative Example 2 was manufactured by impregnating and injecting the epoxy resin composition for Comparative Example 2 into the winding in the same manner as in this example.

A short-circuit test (test for simulating a current generated at the time of a short-circuit accident) of the molded coils of this embodiment and Comparative Example 2 was performed to confirm the presence or absence of cracks. As a result, since the molded coil of this example uses an epoxy resin composition having improved mechanical properties (storage elastic modulus) at high temperatures, the temperature of the molded coil rises to about 150 ° C. by energization, and the electromagnetic force also increases. It occurred but no crack occurred. In contrast, the epoxy resin composition for Comparative Example 2 did not consider mechanical properties at high temperatures at all, and
Cracks occurred when the temperature of the molded coil was raised to about 150 ° C. by energization and at the same time an electromagnetic force was generated.

According to the present embodiment, the epoxy resin composition has an improved elastic modulus at a high temperature after curing as compared with the epoxy resin composition for Comparative Example 2, so that stress such as electromagnetic force is applied to the mold coil. Even if it did, no cracking occurred, and insulation reliability could be improved.

(Example 3 and Comparative Example 3) As shown in Table 3, the epoxy resin composition for this example was composed of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and an epoxy silicon resin. A mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin (manufactured by Asahi Denka Co., Ltd., trade name EP-4901), acid anhydride curing agent is methylhydrophthalic anhydride, curing accelerator is epoxy adduct imidazole, inorganic filler is The same procedure as in Example 1 was performed using crystalline silica or the like. Similarly, the epoxy resin composition for Comparative Example 3 was prepared by weighing the epoxy resin, acid anhydride curing agent, curing accelerator, crystalline silica, and the like shown in Table 2 and mixing them at about 90 ° C. Example 3
For the epoxy resin composition for Comparative Example 3 and the epoxy resin composition for Comparative Example 3, cured products were prepared in the same manner as in Example 1, and the physical properties of the cured products were measured.

[0064]

[Table 3]

First, as the physical properties of the cured product of the epoxy resin composition, the storage elastic modulus at 50 ° C. for this example was 15 GPa, which was almost the same as that for Comparative Example 3 (14 GPa).
° C storage elastic modulus of 1.3 GPa for Comparative Example 3 (0.4 G
About 3 times higher than Pa). Next, the Tg of the epoxy resin composition for this example is 153 ° C., which is almost the same as that for Comparative Example 3 (150 ° C.). Also, for this example, the integrated value of the peak from -53 ppm to -72 ppm of the ²⁹ Si-NMR chemical shift is:
11. For integrated value of peak from -40 ppm to -52 ppm.
It was 0 times, and the organosilicon compound was an oligomer-level molecule.

Next, the molded coil of this example was manufactured in the same manner as in Example 1 by applying the epoxy resin composition for this example described above. Further, the molded coil of Comparative Example 3 was manufactured by impregnating and injecting the epoxy resin composition for Comparative Example 3 into the winding in the same manner as in this example.

A short-circuit test (a test for simulating a current generated at the time of a short-circuit accident) of the molded coils of this embodiment and Comparative Example 3 was performed to confirm the presence or absence of cracks. As a result, since the molded coil of this example uses the epoxy resin composition for this example that has improved mechanical properties (storage modulus) at high temperatures, the temperature of the molded coil rises to about 150 ° C. by energization. At the same time, electromagnetic force was generated, but no crack was generated. On the other hand, since the epoxy resin composition for Comparative Example 3 did not consider the mechanical properties at high temperatures at all, the temperature of the mold coil rose to about 150 ° C. by energization, and at the same time, when the electromagnetic force was generated, cracks occurred. There has occurred.

According to this example, the epoxy resin composition has an improved elastic modulus at a high temperature after curing as compared with the epoxy resin composition for Comparative Example 3, so that a stress such as an electromagnetic force is applied to the mold coil. Even if it did, no cracking occurred, and insulation reliability could be improved.

[0069]

According to the present invention, the use of an epoxy resin composition having an improved elastic modulus at a high temperature has a remarkable effect that a molded coil excellent in insulation reliability can be obtained because cracks are hardly generated. Have.

[Brief description of the drawings]

FIG. 1 is a view showing a production flowchart of an epoxy resin composition of Examples 1 to 3.

FIG. 2 is a perspective view, partially in section, showing a configuration of a molded coil of Examples 1 to 3 and Comparative Examples 1 to 3.

FIG. 3 is a side view of a coil manufactured by a winding machine in Examples 1 to 3 and Comparative Examples 1 to 3.

FIG. 4 is a cross-sectional view of a molded coil after the impregnation and injection of the epoxy resin compositions of Examples 1 to 3 and Comparative Examples 1 to 3.

[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

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01F 27/02 H01F 27/32 A 5E070 27/32 41/04 A 41/04 15/02 L (72) Inventor Yuichi Sado 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Katsuo Sugawara 7-1-1, Omika-cho, Hitachi City, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. In the laboratory (72) Inventor Seichi Nakai 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term in the Hitachi Research Laboratory, Hitachi Ltd. F-term (reference) GB05 LB20 4J036 AA01 AA02 AD01 AF01 AJ21 DB15 FA01 FA05 JA05 JA07 5E044 AA03 AA07 AB01 AB07 AC01 AD02 AD05 AD06 5E062 FF02 5E070 AA01 AB10 DA12

Claims (4)

[Claims] 1. A molded coil in which a winding in which an electric insulator is coated on a conductor is molded with an epoxy resin composition, wherein the epoxy resin composition is represented by the following general formula (1) or (2): Embedded image Embedded image Wherein R is an organic group containing a functional group that causes an addition reaction with the acid anhydride curing agent of the epoxy resin,
n is 0 to 3 and X is H, CH ₃ , C ₂ H ₅ )
A mold coil, which is a cured product of an epoxy resin composition obtained by mixing the acid anhydride curing agent and the inorganic filler. 2. The method according to claim 1, wherein the cured product is 220
A molded coil having a storage elastic modulus at 1 ° C. of 1 GPa or more. 3. A transformer comprising the molded coil according to claim 1. 4. A method of manufacturing a molded coil in which a mixed solution of an epoxy resin composition is injected into a winding having an electric insulator coated on a conductor and molded with a cured product of the epoxy resin composition, the following general formula (3): Or as shown in (4): Embedded image (Where R is an organic group containing a functional group that causes an addition reaction with an acid anhydride curing agent of the epoxy resin, and R ¹ and R ² are a methyl group or an ethyl group) and water Producing a mixed solution containing an epoxy resin and a hydrolysis catalyst; adding an epoxy resin to the mixed solution; mixing the mixed solution and heat-treating the mixed solution; and curing the epoxy mixed solution with an acid anhydride. Adding a curing agent, a curing accelerator, and an inorganic filler, heating and mixing the mixture, then injecting the mixed solution and then heating and curing the mixture to produce a molded coil.