JPS6351528B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a moisture-proof insulated capacitor. A moisture-proof insulated capacitor in which a paper capacitor, ceramic capacitor, plastic film capacitor, or other capacitor is placed inside a case such as a plastic case or metal case, and the case is cast and impregnated with epoxy resin, urethane resin, etc., and then cured. is publicly known. However, although these resins have excellent general mechanical and electrical properties, they tend to crack under conditions of use where they are subject to rapid cooling and heating cycles, and for example, porcelain capacitors, etc. are destroyed. Another disadvantage is that the impact strength is low and the cured product is easily destroyed. Furthermore, these resins have a large shrinkage upon curing and are highly compressed against internal elements, which may damage ceramic capacitors, plastic film capacitors, etc., for example. The inventor of the present invention has conducted various studies to substantially solve the drawbacks of moisture-proof insulated capacitors that use known casting impregnating resins. It was discovered that the object could be achieved by pouring and curing the material underneath, and after further research, the present invention was completed. That is, in the present invention, the hardness according to JIS K 6301 after curing is A-80 (23°C) so that the capacitor is buried in the case in which the capacitor is disposed.
After injecting the following low hardness urethane resin liquid and semi-curing, injecting a high hardness urethane resin liquid with a hardness of D-50 (23℃) or higher according to ASTM D-2240 after curing, and then combining both resins. The present invention relates to a method for manufacturing a moisture-proof insulated capacitor, which is characterized by complete curing. In addition, in this specification, "semi-cured" means
This refers to the period from a viscous state of 30,000 cps (23°C) or higher to a state where the hardness is 50% of the final hardness. The urethane resin used in the present invention has a compound viscosity of
20000cps or less, preferably 10000cps or less (23℃),
Volume resistivity after curing 1×10 ¹³ Ω-cm or more (23
℃) and water absorption of 0.5% or less (at 23℃). The present invention will be described in detail below according to embodiments shown in the drawings. In the embodiment shown in FIG.
A capacitor 3 such as a paper capacitor, a plastic capacitor, a tantalum capacitor, a magnetic capacitor, a mica capacitor, etc. is disposed, and a soft or low hardness urethane resin layer 7 is provided in the case 1 so that the capacitor 3 is buried, Furthermore, a hard or high hardness urethane resin layer 9 is formed on the low hardness urethane resin layer 7. For the metal case, materials such as aluminum and iron are used, and for the plastic case, materials such as polycarbonate, vinyl chloride resin, polyethylene terephthalate, polybutylene terephthalate, polypropylene, and ABS resin are used. Examples of low-hardness urethane resins include castor oil-based, polybutadiene-based, polyester-based, and polyether-based urethane resins that meet JIS K6301 after hardening.
It is desirable to use a material having a hardness of A-80 (23°C) or less, more preferably A-60 (23°C) or less. High hardness urethane resins include urethane resins such as polybutadiene and castor oil, and after curing,
Use a material with a hardness of D-50 (23°C) or higher according to ASTM D-2240. Both low-hardness and high-hardness urethane resins are produced by adding flame retardants, diluents, colorants, antifoaming agents, etc. as necessary to a specified polyol such as polyester polyol, and then adding an isocyanate compound. Cast as an added formulation. As flame retardants, organic phosphorus compounds, organic halogen compounds, aluminum hydroxide, magnesium hydroxide, antimony trioxide, red phosphorus, etc. are used, and these are used alone or in combination of two or more types. . Examples of organic phosphorus compounds include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, octyl diphenyl phosphate, polyphosphate, aromatic Phosphate esters such as polyphosphate; tris(chloroethyl)phosphate, tris(dichloropropyl)phosphate, tris(chloropropyl)phosphate, bis(2,3-dibromopropyl)2,3-dichloropropylphosphate, tris(2, halogen-containing phosphate esters such as 3-dibromopropyl) phosphate and bis(chloropropyl) monooctyl phosphate; additive type and phosphonate type polyols such as special phosphate esters such as epoxy phosphate and dialkyl hydroxymethyl phosphate; There are reactive types such as phosphorus-containing polyether polyols. Examples of organic halides include hexabromobenzene, tetrabromobisphenol A, tetrabromoxylene, decabromodiphenyl oxide, tribromophenol, tetrabromoethane, ammonium bromide, dibromoneopentyl glycol, and the like. In the embodiment shown in FIG.
A capacitor 3 to which lead terminals 5 and 5 are attached via terminals 1 and 11 is disposed inside a case 1.
A low hardness urethane resin layer 7 and a high hardness urethane resin layer 9 are sequentially formed inside. The moisture-proof insulated capacitor of the present invention is manufactured as follows. First, a capacitor is placed in a predetermined case, and then a low hardness urethane resin liquid is cast in an amount sufficient to embed the capacitor and semi-hardened. Next, a high-hardness urethane resin liquid is cast onto the semi-hardened low-hardness urethane resin layer, and both resins are cured at room temperature or under heating, so that the composition changes continuously from low-hardness resin to high-hardness resin. While changing to
A reactor-integrated capacitor is obtained. In the capacitor thus obtained, both resin layers are tightly integrated without showing a clear boundary surface, so that remarkable effects such as stress relaxation on the capacitor element and improvement of moisture-proof insulation are achieved. When injecting high-hardness urethane resin liquid without semi-curing the low-hardness urethane resin liquid, both resin liquids may mix arbitrarily and cause curing failure, or the low-hardness urethane resin may float to the surface layer and cause the surface to dry. The disadvantage is that it reduces the hardness of the parts. On the other hand, if the high hardness urethane resin liquid is injected after the low hardness urethane resin liquid has cured too much, the adhesion between both resin layers will be insufficient.
Air, carbon dioxide, etc., and moisture may enter the boundary between the two layers, resulting in decreased durability under usage conditions such as high humidity and cooling/heating cycles. In the moisture-proof insulated capacitor produced by the method of the present invention, in which a low-hardness urethane resin layer and a high-hardness urethane resin layer are integrated without forming an interface,
The following remarkable effects are achieved: (a) Since the hardness of the low-hardness urethane resin layer is low and its curing mechanism is addition polymerization, there is little shrinkage during curing, and therefore no capacitance change or destruction occurs due to tightening of the capacitor body. (b) Since the cured resin, especially the high-hardness urethane resin, has excellent moisture resistance and water resistance, the obtained moisture-proof insulated capacitor can be used even in a high-humidity atmosphere. (c) Since both resins have excellent electrical properties after curing, they do not impede the properties of the capacitor. (d) Since the resin after curing, especially low-hardness urethane resin, is a highly elastic material, the resin itself will not crack even under severe conditions with rapid cooling and heating cycles, and therefore the capacitor will not be damaged. It will never happen. (e) Since the resin can be cured even at room temperature, a heat source can be omitted and the capacitor will not be adversely affected. (F) Since the high hardness urethane resin layer with high mechanical strength protects the low hardness urethane resin layer with low strength, the case and terminal parts will not be affected by the mechanical load that would occur if the low hardness urethane resin layer was used alone. Separation from the resin and the resulting decrease in moisture resistance and thermal cycle strength are prevented. (g) The use of high hardness urethane resin prevents damage such as scratches and abrasions. Since the moisture-proof insulated capacitor of the present invention can achieve the above-mentioned effects, it can be used in fields where known moisture-proof insulated capacitors have had major problems in use, such as in heating and cooling cycles in high-humidity environments such as in washing machines, electric fans, ventilation fans, etc. It is also possible to use it in fields involving It goes without saying that the present invention is applicable to moisture-proofing treatment of capacitors of types other than those shown in FIGS. 1 and 2. Furthermore, the present invention can be applied to other components where internal stress is to be avoided, such as components with ferrite diodes, flyback transformers, transformers, noise prevention components, hybrid ICs, etc. Examples 1 to 3 As shown in Fig. 1, a plastic film capacitor 3 was housed in a polycarbonate case 1, and low-hardness and high-hardness urethane resin liquids having the blended viscosity and curing characteristics shown in Table 1 were sequentially poured into the plastic film capacitor 3. Mold and harden. In addition, when casting a high hardness urethane resin liquid, the curing of the low hardness urethane resin liquid progresses and the viscosity increases to 200000 cps (23
℃). Table 2 shows the moisture resistance, durability under cooling and heating cycles, etc. of the obtained moisture-proof insulated capacitor. All values shown in Tables 1 and 2 are at 23℃.
This is the measured value at . Comparative Examples 1-5 Examples 1-3 except that urethane resin and epoxy resin having the curing properties shown in Table 1 were used.
A resin-treated capacitor is obtained in the same manner as above. Table 2 shows the moisture resistance and durability under cooling and heating cycles of the resin-treated capacitors. From the results shown in Table 2, the resins used in Comparative Examples 1 to 5 exhibited satisfactory effects in at least one of the following: appearance, shrinkage, moisture resistance during curing, and durability under cold and hot cycles. It is clear that there is no.

【table】

【table】

[Table] Experimental Example 1 In the same manner as No. 1 of Invention 1, polybutadiene-based urethane resin (A) and castor oil-based urethane resin (B) were sequentially cast and cured. However, casting of the castor oil-based urethane resin was carried out at various stages in which the curing state of the polybutadiene-based urethane resin was different, as shown in Table 3 below. The results are shown in Table 3.

【table】

[Table] Examples 4 to 9 and Comparative Examples 6 to 7 High hardness urethane resin (castor oil based urethane resin) and low hardness urethane resin (polybutadiene based urethane resin) whose hardness after curing is the value shown in Table 4
Resin-treated capacitors are obtained in the same manner as in Examples 1 to 3, except that they are used in combination. The performance, etc. of each resin-treated capacitor obtained was evaluated under the same conditions as in Examples 1 to 3. The results are shown in Table 4.

[Table] From the results shown in Table 4, it is clear that the moisture-proof insulated capacitor according to the present invention has excellent properties in which the hardness after curing is within a specific range and both resin layers are closely integrated. Ru

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing an outline of an embodiment of the present invention, respectively. 1... Case, 3... Capacitor, 5, 5...
Lead terminal, 7...Low hardness urethane resin layer, 9...
...High hardness urethane resin layer, 11, 11... Connection portion.

Claims (1)

[Claims] 1 Inject a low-hardness urethane resin liquid whose hardness according to JIS K 6301 after hardening is A-80 (23℃) or less so as to bury the capacitor in the case in which the capacitor is placed, and after semi-curing, after curing
A method for manufacturing a moisture-proof insulated capacitor, which comprises injecting a high-hardness urethane resin liquid having a hardness of D-50 (23° C.) or higher according to ASTM D-2240, and completely curing both resins.