JPH07230931A - Manufacture of high tension transformer - Google Patents

Abstract

PURPOSE:To develope a manufacturing method wherein a high tension transformer is obtained having an excellent impregnating property to a high tension coil, heat conductivity and crack-proof property. CONSTITUTION:After the filler of average particle diameter of 100mum or more has been filled in the case or the mold in which a high voltage transformer part is housed, an epoxy resin composition, containing the filler of average particle diameter of 50mum or less in quantity less than 300 pts.wt. based on the epoxy resin of 100 pts.wt., is vacuum injected and it is hardened in this high voltage transformer manufacturing method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a high voltage transformer suitable for electric equipment.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a high voltage transformer, a high voltage coil, a circuit component, and other high voltage transformer parts are set in a case, and an acid anhydride and a curing accelerator are added to a uniform mixture of an epoxy resin and an inorganic filler. Alternatively, a potting method is known in which an epoxy resin composition mixed with an amine compound is injected and cured under normal pressure or vacuum. However, in this method, there is a limit to the amount of the inorganic filler to be mixed in terms of viscosity at the time of mixing and injection workability, for example,
The weight ratio of the epoxy resin composition to the filler of 1.0 is limited to 0.4. For this reason, the product price increases, but if a filler is further added, the impregnating property with respect to the high-voltage coil deteriorates.

Further, since volume contraction occurs when the epoxy resin composition is cured, cracks are generated in the cured product, and peeling and cracks are likely to occur in the built-in coil, parts and case, and thermal conductivity is high. However, there is a problem in that the temperature of the electric device becomes high and the temperature at which it is used is limited. Furthermore, since the injection work is performed after the epoxy resin composition and the inorganic filler are mixed and defoamed under vacuum, it is necessary to use one having a long curing time of the epoxy resin composition, and the curing time after injection is also long. There is a limit to the rationalization of work processes and energy saving.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art and provides a method capable of efficiently producing a high-voltage transformer excellent in impregnation into a high-voltage coil, thermal conductivity and crack resistance. To do.

[0005]

According to the present invention, after a filler having an average particle diameter of 100 μm or more is filled in a case or a mold in which a high-voltage transformer component is housed, a filler having an average particle diameter of 50 μm or less is filled. The present invention relates to a method for producing a high-voltage transformer, which comprises injecting an epoxy resin composition contained in an amount of 300 parts by weight or less with respect to 100 parts by weight of an epoxy resin in a vacuum to cure the epoxy resin composition.

In the present invention, first, the average particle size is 1 in a case or a mold in which high-voltage transformer parts are housed.
A filler having a size of 00 μm or more (hereinafter referred to as filler (A)) is filled. A preferable average particle diameter is 200 to 20.
It is 00 μm. The average particle size is JIS-Z.
2602-1976. If the average particle diameter is less than 100 μm, the particles are fine and the voids between the particles are small, so that the unimpregnated portion remains when the epoxy resin composition is injected, and the impregnation property into the high-voltage coil is poor. In addition, since the filler (A) is unevenly filled between the parts, the linear expansion coefficient of the entire transformer becomes non-uniform, resulting in peeling and cracking around the coil and parts during heat cycle, and thermal conductivity. descend.

The type of filler (A) used in the present invention is not particularly limited, and for example, silica sand, silica, alumina, clay, mica, glass beads and the like are used. This commercial product includes Pearl Sand No. 4, Pearl Sand No. 6,
Mikawa silica V-3 (trade name of Tochu Co., Ltd.), Morundum-A (Showa Denko KK), GB-AG, GB-AC, GB
-B (manufactured by Toshiba Ballotini) and the like. These may be used alone or in combination of two or more.

Next, in the present invention, the epoxy resin composition is vacuum-injected.
A filler having an average particle diameter of 50 μm or less (hereinafter referred to as filler (B)) is mixed. The preferable average particle size of this filler is 5 to 20 μm. The average particle diameter is measured using a sedgraph (manufactured by MICROMERI-TICS). When the average particle diameter exceeds 50 μm, the filler (B) precipitates quickly during storage of the epoxy resin composition, and the desired epoxy resin composition cannot be obtained. Further, when the epoxy resin composition is injected onto the filler (A), unimpregnated parts remain, the thermal conductivity is lowered, and the insulating property is impaired. Furthermore, since the filler (B) is unevenly filled between the parts, the linear expansion coefficient of the entire transformer becomes non-uniform, and peeling and cracks occur around the coil and parts during the heat cycle. The amount of the epoxy resin composition with respect to the filler (A) is such that the entire filler (A) is sufficiently impregnated with the epoxy resin composition.

The filler (B) is an epoxy resin 1
It is used in an amount of 300 parts by weight or less based on 00 parts by weight. When the epoxy resin contains a reactive diluent, the filler (B) is 300 parts by weight or less based on 100 parts by weight of the total amount of the epoxy resin and the reactive diluent. When the amount of the filler (B) exceeds 300 parts by weight, impregnating property into the coil is impaired, dielectric breakdown is caused by generation of corona, and this is a fatal defect for a high voltage transformer. The filler (B) may not be used.

As the filler (B), for example, crystalline silica, fused silica, hydrated alumina, alumina oxide, talc, calcium carbonate, mica, glass beads, magnesium hydroxide, clay and the like are used. As this commercial item, CRT-AA, CRT-D, RD-8 (manufactured by Tatsumori Co., Ltd.), C-303H, C-315H, C-308 (manufactured by Sumitomo Chemical Co., Ltd.), SL-700 (manufactured by Takehara Chemical Co., Ltd.). ) And the like. The filler (B) can be used alone or in combination of two or more kinds.

The epoxy resin used in the present invention has at least one epoxy group in one molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, polyvalent Polyglycidyl ether of alcohol or the like can be used. These resins are not particularly limited, but those that are liquid at room temperature are preferable, and as commercially available products, Epicoat 828 (manufactured by Shell Chemical Co., trade name), GY-260 (manufactured by Ciba Geigy Co., trade name), D
ER-331 (trade name of Dow Chemical Co., Ltd.) and the like can be mentioned. These can be used in combination. The epoxy resin may contain a reactive diluent such as polypropylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether and butanediol diglycidyl ether.

The epoxy resin composition used in the method of the present invention contains a curing agent together with the epoxy resin. An acid anhydride, a curing accelerator, or an amino compound is used as the curing agent. The acid anhydride is not particularly limited, but is preferably a liquid at room temperature, for example, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylendomethylenephthalic anhydride, dodecenylphthalic anhydride and the like are used. To be As a commercial product, HN-
2200 (manufactured by Hitachi Chemical Co., Ltd., trade name), QH-200 (manufactured by Nippon Zeon Co., Ltd., trade name) and the like. These may be used alone or in combination of two or more. The amount of the acid anhydride blended is 5 with respect to 100 parts by weight of the epoxy resin.
It is preferably from 0 to 150 parts by weight.

Examples of the acid anhydride curing accelerator include 2-ethyl-4-methylimidazole, 1-cyanoethyl-4-methylimidazole, and 1-benzyl-2-.
Imidazole such as ethylimidazole and its derivatives,
Tertiary amines such as trisdimethylaminophenol and benzyldimethylamine are used. Commercially available products are 2E4MZ (Shikoku Kasei Co., Ltd., trade name), BDMA
(Manufactured by Kao Corporation, product name) and the like. The mixing amount of these curing accelerators is 0.1 per 100 parts by weight of the acid anhydride.
˜5.0 parts by weight is preferred.

Examples of the amine compound include aromatic polyamines and modified products thereof, and aliphatic polyamines and modified products thereof. For example, an adduct of diaminodiphenylmethane and an epoxy resin is used. As a commercial product,
EH-520 (manufactured by Asahi Denka Co., Ltd., trade name), EH-551
(Manufactured by Adeka, trade name), Ancamine 2007 (manufactured by Anchor Chemical Co.) and the like. These can be used alone or in combination of two or more. The blending amount of these amino compounds is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the epoxy resin.

In the epoxy resin composition, if necessary, red phosphorus, hexabromobenzene, dibromophenyl glycidyl ether, dibromocresyl glycidyl ether,
Flame retardants such as antimony trioxide, red iron oxide, ferric oxide,
Coloring agents such as carbon and titanium white, silane coupling agents, antifoaming agents such as silicone agents, diluents such as monoglycidyl ether and diglycidyl ether, and the like can be added.

In order to carry out the present invention, as described above, in a case or a mold in which high-voltage transformer parts are housed,
First, the filler (A) is filled. Next, the epoxy resin composition containing the epoxy resin and the curing agent or the epoxy resin composition containing the epoxy resin, the curing agent and the filler (B) is preheated and defoamed under vacuum, and then injected into the above case under vacuum. Then, the pressure may be returned to normal pressure and then heated to cure. When a mold is used, it is removed from the mold after curing.

The high-voltage transformer obtained by the manufacturing method of the present invention includes, for example, a transformer in which a high-voltage coil, electronic parts, high-voltage transformer parts such as electric parts are housed in a plastic or metal case, a flyback transformer, a neon transformer. , An ignition coil, a caseless type transformer of these, or the like.

[0018]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, "part" in an example means a "weight part" unless there is particular notice. The average particle diameter of the fillers (A) and (B) was measured and various performances were evaluated by the following methods.

(1) Average particle size of filler (A) The particle size distribution is measured according to JIS-Z2602-1976 "Testing method for particle size distribution of foundry sand", and particles when the cumulative weight% is 50% by weight. The diameter was defined as the average particle diameter. (2) Average particle diameter of filler (B) Using a sedigraph 5000EP (manufactured by Shimadzu Corporation),
Filler (B) was added at a concentration of about 8% by weight to an aqueous solution of 0.1% by weight of sodium hexametaphosphate with a starting particle diameter of 50 μm, ultrasonic cleaning was performed for 20 minutes as a preliminary dispersion, and the particle size distribution was measured to determine the cumulative weight. The particle size when the percentage became 50% by weight was taken as the average particle size.

(3) Actual machine impregnation rate Modified polyphenylene oxide bobbin (12 slits)
A model coil in which a urethane wire having a diameter of 0.04 mm is wound for 500 turns or more is placed in a case made of polybutylene terephthalate, and the high voltage transformer manufactured in each of the examples and comparative examples is cut and polished from the center part using the case. The impregnation rate of the epoxy resin composition between the windings of the coil was observed under a microscope of 100 times. The impregnation rate was calculated for each slit by the following formula, and finally the average value was calculated.

[Equation 1] [However, T is the number of turns of the enamel wire of the coil, and V is the number of voids between the windings. The obtained average impregnation rate was evaluated according to the following criteria. ◯: Average impregnation rate 99% or more Δ: Average impregnation rate 95% or more and less than 99% X: Average impregnation rate less than 95%

(4) Impregnating Property into Filler (A) The cut surface used in the evaluation of the impregnating property in the above-mentioned (3) was 100.
Observation with a double microscope was performed to observe the impregnation state of the epoxy resin composition with respect to the filler (A), and then, evaluation was made based on a standard. ◯: The epoxy resin composition is impregnated between the particles of the filler (A). X: An unimpregnated part is recognized. (5) Thermal conductivity Filler (A) in a polyethylene beaker with a diameter of 50 mm
Fill while shaking. Next, the epoxy resin composition was injected and left under a reduced pressure of 10 mmHg for 10 minutes.
Cured at 0 ° C for 3 hours to prepare a disc-shaped test piece with a diameter of 50 mm and a thickness of 10 mm, and measure the thermal conductivity (cal / cm · sec · ° C) with a thermal conductivity measuring instrument (Dynatech). I asked.

(6) Crack resistance A test piece was prepared by casting in the same manner as in (3), and the JIS-
The test was performed according to the crack resistance test of C2105 "Test method for solvent-free liquid resin for electrical insulation". The number of crack test pieces was set to 5, a predetermined cooling / heating cycle was performed, and the presence or absence of cracks was confirmed for each cycle, and the number of cycles in which cracks first occurred was described. (7) Linear expansion coefficient A 5 mm x 5 mm x 2 mm test piece was cut out using a thermal conductivity measurement test piece, and the linear expansion coefficient (° C ^-1 ) was measured using a TMA thermophysical tester (manufactured by Rigaku Denki Co., Ltd.). I asked.

The materials used in the following Examples and Comparative Examples are
It is as follows. Filler (A) -Pearl sand No. 4 (silver made by Tochu Corporation, average particle size 417 μm) -GB-AC (glass beads made by Toshiba Ballotini, average particle size 200 μm) -EC-40 (crystalline silica made by Seto Kiln Co., average) Particle size 4
0 μm) Filler (B) CW-308 (hydrated alumina manufactured by Sumitomo Chemical Co., Ltd., average particle size 8 μm) CRT-AA (crystalline silica manufactured by Tatsumori, average particle size 7 μm)
m) -EC-15 (Crystalline silica manufactured by Seto Ceramics Co., average particle size 1
5 μm) EC-H (Crystalline silica manufactured by Seto Kiln Co., average particle size 15
0 μm)

Epoxy resin: DER-331 (manufactured by Dow Chemical Co.) Reactive diluent: polypropylene glycol diglycidyl ether manufactured by Asahi Denka Co., Ltd., trade name ED-506 Acid anhydride: HN-2200 Curing accelerator: 2E4MZ-CN

Examples 1 and 2 Modified polyphenylene oxide bobbins (12 slits)
A model coil in which a urethane wire having a diameter of 0.04 mm was wound for 500 turns or more was placed in a polybutylene terephthalate case, and the filler (A) shown in Table 1 was filled until reaching 3 mm above the upper end of the model coil. next,
After preheating the epoxy resin composition (containing no filler (B)) shown in Table 1 at 120 ° C. for 3.0 hours,
After defoaming under a vacuum of 0.5 Torr for 15 minutes, it was injected into the above case under a vacuum of 2 Torr and returned to normal pressure. Then 1
It was cured by heating at 00 ° C. for 3 hours and further at 140 ° C. for 3 hours. The properties of the obtained high-voltage transformer were examined. As shown in Table 1, in all cases, the impregnating property in the actual machine and the impregnating property into the filler (A) were good, the thermal conductivity was high, and the linear expansion coefficient was high. Was small and the crack resistance was also good. In Table 1, the unit of formulation is parts by weight.

Examples 3 to 6 A high-voltage transformer was prepared and obtained in the same manner as in Example 1 except that the filler (A) shown in Table 1 and the epoxy resin composition having the composition shown in Table 1 were used. The properties of the obtained high-voltage transformer were examined. As shown in Table 1, in all cases, the impregnating property in the actual machine and the impregnating property into the filler (A) were good, the thermal conductivity was high, and the linear expansion coefficient was It was small and had good crack resistance.

Comparative Example 1 A high-voltage transformer was manufactured in the same manner as in Example 3 except that the filler (A) was not used, and the characteristics of the high-voltage transformer were examined. The coefficient was low, the coefficient of linear expansion was small, and the crack resistance was poor.

Comparative Example 2 A high-voltage transformer was manufactured in the same manner as in Example 3 except that the filler (A) was not used in Example 3 and the amount of hydrated alumina was 350 parts by weight as the filler (B). As a result of examining each characteristic, as shown in Table 1, the impregnation property in the actual machine and the crack resistance were inferior.

Comparative Example 3 A high-voltage transformer was produced in the same manner as in Example 3 except that crystalline silica having an average particle diameter of 150 μm was used as the filler (B) in Example 3 instead of hydrated alumina.
When each property was examined, as shown in Table 1, the impregnation property in the actual machine, the impregnation property into the filler (A) and the crack resistance were inferior, and the linear expansion coefficient also varied.

Comparative Example 4 The average particle size of 40 as the filler (A) in Example 5
A high-voltage transformer was produced in the same manner as in Example 5 except that crystalline silica having a particle size of μm was used, and the characteristics of the transformer were investigated.
As shown in, the impregnation property in the actual machine, the impregnation property into the filler (A) and the crack resistance were poor, and the coefficient of linear expansion also varied.

[0031]

[Table 1]

[0032]

According to the present invention, it is possible to efficiently manufacture a high-voltage transformer which is excellent in impregnation into a high-voltage coil and a filler, thermal conductivity, and crack resistance.

Claims (1)

[Claims] 1. A case or mold in which a high-voltage transformer part is housed is filled with a filler having an average particle size of 100 μm or more, and then a filler having an average particle size of 50 μm or less is added to 100 parts by weight of an epoxy resin. A method for producing a high-voltage transformer, which comprises vacuum-injecting an epoxy resin composition contained in an amount of 300 parts by weight or less and curing the epoxy resin composition.