JP3018730B2 - Manufacturing method of electrical equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing electrical equipment, and more particularly to a method for manufacturing electrical equipment having excellent curability, crack resistance, thermal conductivity, and workability, and also excellent moisture resistance and voltage resistance. Related to manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as a method of insulating an electric device,
A potting method is known in which a component such as a coil and a circuit component is set in a plastic case or a metal case, and a uniform mixture of a resin and an inorganic filler is injected under normal pressure or vacuum and cured. However, in this method, there is a limit to the amount of the inorganic filler to be mixed from the viewpoint of workability, so that there is a disadvantage that the product price increases. In addition, when the resin composition cures, volume contraction occurs, so that cracks occur in the cured product, and peeling and cracks easily occur in components such as built-in coils. Further, there is a problem that the temperature of the device becomes high due to poor thermal conductivity, and the temperature used is limited. Furthermore, in order to perform the injection work after mixing the resin composition and the inorganic filler and defoaming under vacuum, it is necessary to use a resin composition having a long curing time, and thus the curing time after the injection becomes long, There are limits to the rationalization of work processes and energy saving. Recently, as a method for solving the above-mentioned drawbacks, a method of filling a resin composition in advance and then injecting and curing a resin composition has been studied.
According to this method, cracking, thermal conductivity, work rationalization and the like can be improved, but there is a problem that the moisture resistance and the voltage resistance are inferior.

[0003]

SUMMARY OF THE INVENTION The present invention eliminates the above-mentioned disadvantages of the prior art, and is excellent in curability, crack resistance, thermal conductivity and workability, and furthermore excellent in moisture resistance and voltage resistance. Is provided.

[0004]

According to the present invention, a case containing coils, parts and the like is filled with a filler having an average particle diameter of 300 μm or more, and then (A) castor oil, (B) diisocyanate and (C) Inject a urethane resin composition containing a silane coupling agent having an epoxy group, an amino group or a mercapto group at a degree of vacuum of 100 Torr or less,
The present invention relates to a method of manufacturing an electric device to be cured.

[0005] The average particle size of the filler used in the present invention is 300 µm or more, preferably 600 to 1200 µm. The particle size is measured according to JIS Z 2602-1977. When the average particle size is less than 300 μm,
Since the particles are fine and the gap between the particles is small, an unimpregnated portion remains when the urethane resin composition is injected, so that the thermal conductivity is reduced and the insulating property is impaired. In addition, the filler is unevenly filled between the parts, the linear expansion rate of the entire equipment becomes uneven, peeling cracks occur around the coils and parts during the heat cycle, and solder cracks occur at the solder joints of the board . As the filler, for example, silica sand, silica, alumina, hydrated alumina, clay, mica, glass beads and the like are used, and there is no particular limitation on the type. Commercial products include Pearl Sand No. 4, Mikawa Silica Sand V-3 (manufactured by Tochu), GB
-B (manufactured by Toshiba Barotini), AGSCO SILI
CA SAND # 8-12 (manufactured by AGSCO) or the like can be used. These fillers can be used in combination. Further, these fillers are preferably dried at 70 to 600 ° C. for the purpose of dehumidification and dehydration. The usage ratio of the filler and the urethane resin composition is 10
It is preferable to use 70 to 80 parts by weight of the filler and 30 to 20 parts by weight of the urethane resin composition as 0 parts by weight.

The castor oil used in the present invention is a triglyceride containing ricinoleic acid (1,2-hydroxyoleic acid) as a main component and having about 2.7 hydroxyl groups in the molecule. In addition, for example, hexanediol, ethylene glycol, diethylene glycol, propylene glycol, octanediol, 2-ethyl-
It is also possible to use a low-molecular polyol such as 1,3-hexanediol, glycerin, pentaerythritol, and trimethylolpropane as a diluent or a modifier.

The diisocyanate used in the present invention is
Used as a curing agent for the polyol, for example, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, diphenyl sulfone diisocyanate, triphenyl methane diisocyanate, hexane methylene diisocyanate, diphenyl propane diisocyanate, phenylene diisocyanate, cyclohexylene diisocyanate, 3, 3-diisocyanate dipropyl ether, diphenyl ether-4,4-diisocyanate, carbodiimide-modified diphenylmethane-4,4 '
-Diisocyanate, polymeric diphenylmethane-
Diisocyanates such as 4,4'-diisocyanate or the above isocyanates are converted to phenols, oximes,
Examples include those blocked with imides, mercaptans, alcohols, ε-caprolactam, ethyleneimine, α-pyrrolidone, diethyl malonate, hydrogen sulfite, sodium, boric acid, and the like. These can be used alone or 2
A combination of more than one type is used. The castor oil and the diisocyanate are preferably used in such an amount that a hydroxyl group and an isocyanate group are equivalent.

The silane coupling agent having an epoxy group, an amino group or a mercapto group used in the present invention includes, for example, KBM-303, KBM-403, KBM
M-503, KBM-603, KBM-803 (trade name, manufactured by Shin-Etsu Silicone Co., Ltd.), A-187, A-1100, A
-189 (trade name, manufactured by Nippon Yunika) or the like is used. These may be used in combination. The amount is preferably 0.5 to 5% by weight based on castor oil and diisocyanate. If the amount is less than 0.5% by weight, the wettability of the interface between the filler and the urethane resin composition is poor, and the moisture resistance of the electric device is reduced. If it exceeds 5% by weight, the silane coupling agent remains as an unreacted component in the urethane resin composition, resulting in insufficient curing.

In the urethane resin composition, a plasticizer having no hydroxyl group, for example, phthalic acid esters such as dioctyl phthalate, triphenyl phosphate, tricresyl phosphate and cresyl diphenyl phosphate, and phosphate esters can be used in combination. . If necessary, flame retardants such as red phosphorus, hexabromobenzene, dibromophenyl glycidyl ether, dibromocresyl glycidyl ether, and antimony trioxide;
Coloring agents such as iron, carbon and titanium white, and various additives such as silicone-based antifoaming agents can be blended.

In the present invention, an electric device is obtained by injecting a urethane resin composition at a degree of vacuum of 100 Torr or less into a case in which a coil, a part, or the like, which is filled with a filler in advance, is cured and cured. The degree of vacuum is 100 Torr
If it exceeds r, the impregnation of the filler with the urethane resin composition is reduced, the thermal conductivity is reduced, and the insulation is impaired. Examples of the electric device to which the present invention is applied include a high-voltage transformer and a power supply transformer.

[0011]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The characteristics were evaluated by the following methods. (1) Model impregnation rate: The filler (A) was weighed after filling with shaking the filler in a polyethylene beaker having a diameter of 50 mm to determine the weight (W ₀ g) of the filler (A). Next, the resin composition was injected, left under a reduced pressure of 10 Torr for 10 minutes, and cured at 80 ° C. at normal pressure for 3 hours. Next, the cured product was taken out from the polyethylene beaker, the weight (W ₁ g) of the filler separated from the cured product without impregnating the lower resin composition was determined, and the model impregnation rate was calculated from the following equation.

[Number 1] model impregnation rate (%) = _{[(W 0 -W 1) / W} 0 ] × 100 model impregnation ratio is for determining the ratio of the resin composition was impregnated into the filler, the non-impregnated portion The smaller the filler, the higher the model impregnation rate, indicating that the impregnation is excellent.

(2) Impregnating property into model equipment: A filler dried at 600 ° C. for 2 hours is added to a model equipment in which a primary coil, a secondary coil and parts are housed in a metal case.
Filling was carried out while lowering the temperature to ℃ and shaking. Next, after injecting the urethane resin composition under a reduced pressure of 10 Torr, 1
It was left at 0 Torr for 3 minutes, returned to normal pressure, and cured at 70 ° C. for 6 hours. Next, the obtained model equipment was cut, and the impregnation state of the gap between the coil and the parts and the impregnation state of the filler with the urethane resin composition were observed and evaluated as follows. ：: Impregnated in the gap between the coil and the component, and the filler is impregnated with the urethane resin composition. Δ: Some unimpregnated portion of the urethane resin composition remains in the filler. X: The unimpregnated portion of the urethane resin composition remains considerably in the filler.

(3) Crack resistance: A 1/2 inch iron spring washer was set on a metal dish having a diameter of 60 mm, and a urethane resin composition was injected to the upper end of the washer and cured to obtain a test piece. Thereafter, the metal petri dish was removed, a heat cycle test was performed according to the heat cycle conditions of JIS C 2105, and the state of crack generation was observed.

(4) Thermal conductivity: A polyethylene beaker having a diameter of 50 mm was filled with a filler while being vibrated.
Next, the resin composition was injected, and the pressure was reduced to 10 under a reduced pressure of 10 Torr.
For 3 minutes at room temperature and at 80 ° C for 3 hours.
A disk-shaped test piece having a thickness of 0 mm and a thickness of 10 mm was prepared, and the thermal conductivity (cal /
cm · sec · ° C.).

(5) Humidity resistance: Model equipment treated in the same manner as in (2) is left in boiling water at 100 ° C. for 2 hours, and then left in cold water for 2 hours. Then, the presence or absence of cracks and peeling of the cured resin was observed.

(6) Dielectric breakdown strength: A filler adjusted to a thickness of 3 mm was filled with a filler dried at 600 ° C. for 2 hours while lowering the temperature to 70 ° C. and vibrating. Next, after injecting the urethane resin composition under a reduced pressure of 10 Torr,
It was left at Torr for 3 minutes, returned to normal pressure, and cured at 70 ° C. for 6 hours. Next, the obtained 3 mm thick resin cured plate is
A plate electrode was set, and a short-time breakdown voltage was measured in insulating oil.

Examples 1 to 12 Using the fillers shown in Table 1, and further using the urethane resin compositions prepared according to the formulations (units by weight) shown in Table 2,
The characteristics were examined according to the test methods described above, and the results are shown in Table 2.

[0018]

[Table 1] From Table 2, it can be seen that the model impregnation,
It shows excellent impregnation into actual transformers, crack resistance, thermal conductivity, cold water boiling characteristics, and dielectric breakdown strength.

Comparative Examples 1 to 3 In Example 1, the content of the epoxy silane coupling agent was not added, and 0.5 parts by weight (0.33% by weight) and 10.0 parts by weight (6.3% by weight) were used. ), And the characteristics were examined in the same manner as in Example 1. The results are shown in Table 2. In Comparative Examples 1 and 2 in which the content of the silane coupling agent is less than 0.5% by weight, the withstand voltage characteristics (dielectric breakdown strength) decrease, and in Comparative Example 3 in which the silane coupling agent content exceeds 5% by weight, the moisture resistance characteristics significantly decrease. did.

Comparative Examples 4 and 5 In Comparative Example 4 in which a polyol component other than castor oil was used, and in Comparative Example 5 in which an isocyanate component other than diisocyanate was used, both the withstand voltage characteristics and the moisture resistance characteristics were lowered. .

Comparative Example 6 In Comparative Example 6, in which a filler having an average particle diameter of less than 300 μm was used, the impregnating properties of the model and the transformer of the actual machine were significantly reduced.

Comparative Example 7 In Comparative Example 7 in which no filler was used, crack resistance and
Thermal conductivity was significantly poor.

[0023]

[Table 2]

[0024]

According to the electric device obtained by the production method of the present invention, since the filler in the case is uniformly and sufficiently impregnated with the urethane resin composition, the cured product has no air bubbles and can be used for parts, coils and the like. It adheres well and shows excellent impregnation and adhesion as in the conventional potting method. In the conventional potting method, filler 1.
The use ratio of the resin composition to 0 was limited to 0.4 by weight, but according to the present invention, the amount of the filler can be made larger than this, so that the total cost can be reduced, and The curing shrinkage at the time is small, and the thermal conductivity and heat cycle property of the crack resistant cured product are improved.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01F 41/12

Claims (1)

(57) [Claims] 1. After filling a filler having an average particle diameter of 300 μm or more into a case containing a coil, parts, and the like,
(A) castor oil, (B) diisocyanate and (C)
Urethane resin composition containing silane coupling agent having epoxy group, amino group or mercapto group is 100T
A method for manufacturing an electric device, wherein the method is performed by injecting and curing at a degree of vacuum of orr or less.