JPH01280305A - Dry-type metallized plastic film capacitor - Google Patents

Abstract

PURPOSE:To realize resin armor at a lower temperature as compared with a conventional method which uses epoxy resin, etc., as armor resin, to enable easy armor sealing, and to realize quality stability without reducing electric efficiency and electric characteristics of a capacitor by using thermosetting unsaturated polyester resin as armor resin. CONSTITUTION:A capacitor is made by a capacitor element 1 whereto a metallized plastic film is wound or laminated and provided with a metallicon electrode 2 on the both ends, a drawn terminal 3 connected to the metallicon electrode 2, and a thermosetting unsaturated polyester resin armor section 4 which covers a part of the drawn terminal 3 and the capacitor element 1. For instance, the capacitor element 1 is dried at 85 deg.C in a vacuum tank of 0.01mmHg for about 30 hours and then insulating varnish is filled and immersed to eliminate wax attaching to the surface. The capacitor element 1 is inserted into a molding die, thermosetting unsaturated polyester resin is charged, and resin armor 4 is formed at a molding temperature of 110 deg.C by using a transfer molding machine of closing pressure of 50 tons.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a dry metal film coated with a resin and using a metallized plastic film (hereinafter referred to as MF) as a dielectric material, which is used for household electrical equipment, lighting lights, small industrial electrical equipment, etc. This invention relates to a plastic film capacitor (hereinafter referred to as a dry MF capacitor).

Conventional technology (1) Conventional dry MF capacitors are made by winding MF and flattening it with a press, or by stacking MF to form a capacitor element, and then housing the capacitor element in a case made of epoxy resin or polyurethane. The mainstream is injected with a highly fluid resin such as resin, heated and hardened, and sealed.

As mentioned above, cases are occasionally made of metal, but most cases are made of thermoplastic resin and are injection molded. In addition, there is a simple structure in which the outside of the capacitor element is wrapped and covered with a thick polyester film, and both ends of the capacitor element are filled with the epoxy resin or the like and sealed.

(2) There is a dip type dry type MF capacitor in which the capacitor element of (1) is immersed in a thermosetting resin such as an epoxy resin, and the heat curing operation is repeated two or three times to coat the surface with the resin.

(3) Recently, dry-type MF capacitors have appeared that apply the insert direct molding method, which has long been used for capacitors for electronic circuits, to capacitors for small electrical equipment, and are used for a limited number of special applications. ing. In this method, a capacitor element similar to the above (11) is inserted into a mold, and the exterior is made of polypropylene resin (hereinafter referred to as P
It is injection molded and sealed with a thermoplastic resin such as P resin. (Japanese Unexamined Patent Publication No. 59-213121 is an example of this.) Problems to be Solved by the Invention The dry type MF capacitor of the prior art (No. 11) has many problems. A dry MF capacitor using a plastic case will be explained below as an example.

For wound capacitor elements, a rectangular case is usually used, and the capacitor element is pressed and flattened using a hot press or the like in order to increase the efficiency of accommodating the capacitor element and to reduce its size. When a capacitor element, which was originally wound in a round shape, is forcibly flattened by heating and pressurizing, the dielectric material is mechanically damaged, causing electrical characteristics to deteriorate, such as a decrease in withstand voltage and large fluctuations in capacitance. descend. On the other hand, the manufacturing process has become many and complex, and the equipment has become large-scale because it takes a long time to heat-cure the filling resin for sealing, and each process has been cut into pieces, making it difficult to mechanize and requiring a large amount of manpower. However, there were problems such as high product costs.

Furthermore, the dip-type dry MF capacitor of the prior art (2) has a lead wire attachment structure, such as for mounting on a board, and is limited to small capacitors with a small capacity, and is used for built-in motors and electrical equipment such as home appliances. This is inappropriate because it does not have a structure that allows for fixed installation.

Next, regarding the dry type MF capacitor having an insert direct mold exterior made of thermoplastic resin according to the prior art (3), there are problems with the basic characteristics of the capacitor, and the structure has not made much progress so far.

That is, the biggest problem is that during exterior molding, the dielectric material forming the capacitor element deteriorates in the mold due to high temperature and pressure, and the electrical characteristics of the capacitor rapidly deteriorate. In capacitors with this structure, the capacitor element and lead terminals are integrally formed and inserted into a mold, and the space between the mold, capacitor element, and lead terminals is filled with high-temperature molten resin under high pressure, and then cooled. Let it harden.

For this reason, the thermoplastic resin used as the exterior material has a molding temperature of over 200°C even when using PP resin, which has the lowest molding temperature.
PF), the melting temperature of MPPF itself is 1
Since the temperature is around 65° C., the MPPF will suffer fatal thermal damage during this sealing molding. Therefore, in direct mold sealing with thermoplastic resin, MPPF, which is the mainstay of dry MF capacitors, cannot be used as a dielectric material, and metallized polyethylene terephthalate film (hereinafter referred to as MPETF), which has a high heat resistance, cannot be used as a dielectric material.
is used. Further, especially when the dielectric is MPETF, it is difficult to add a dielectric safety mechanism, making it impossible to guarantee the most important safety for dry MF capacitors.

Furthermore, when sealing the terminal part with thermoplastic resin, the coefficient of thermal expansion is large, and thermoplastic resin does not have adhesive properties with metal under normal conditions. A gap is created.

Repeated temperature changes such as energization and deactivation of the dry MF capacitor cause the terminal sealing part to breathe, and over a long period of time it absorbs moisture, causing insulation deterioration of the dry MF capacitor. Incidentally, the thermal expansion coefficient of metal is as small as 1 to 1.5 x 10-S7°C, while when the thermoplastic resin is PP resin, the thermal expansion coefficient is 4 to 6 x 10-'/''C; With such a combination, it is no longer possible to maintain long-term airtightness.

Therefore, as a countermeasure to this problem,
In this publication, the terminal part is curved in an uneven shape to prevent the terminal from loosening due to external tensile force, and in Japanese Utility Model Application Publication No. 58-173227, a silane couple agent is applied to the terminal surface to prevent the metal surface from loosening. Efforts have been made to increase the adhesion between the resin and the resin, but none of these measures are definitive.

Next, what is common to the prior art (1), (2), and (3) is the safety of the exterior against heat and combustion.
This is a problem with all resin sheaths except metal. Among these, thermoplastic resins have a decisive flaw in that they always melt due to heat.

If a dry MF capacitor is thermally destroyed due to an unexpected accident during use, or if it is exposed to high temperatures from the outside, the exterior may be damaged, and in the worst case, there is a risk that the capacitor may burst into flames. In the worst case scenario, even if the exterior resin is flame retardant, if it melts and breaks due to heat,
There was a problem that the internal capacitor element was exposed and could catch fire.

Means for Solving the Problems The present invention seeks to provide a dry MF capacitor that solves the above problems.

Against this background, the inventors focused on the existence of thermosetting resins that do not have any fear of melting even if the resin itself encounters high heat.

Normally, thermosetting resins are extremely promising for use in capacitor exteriors because their physical properties can be easily reinforced with glass fibers or inorganic substances, and strong flame retardance can be easily achieved without using organic flame retardants that adversely affect capacitor properties. This is because it has both characteristics.

However, thermosetting resins have traditionally been used in mica capacitor exterior molds, tantalum capacitors, and super heat-resistant metalized polyphenylene sulfide films (hereinafter referred to as MPP).
It was only used to seal capacitors for electronic circuits that require high heat resistance, such as the exterior mold of MPPSF capacitors using SF.

Generally available commercially available thermosetting resins, such as phenolic resins, epoxy resins, urethane resins, melamine resins, and diallyl phthalate resins, have molding temperatures uniformly as high as 140 to 200'C; Since the capacitor element is in contact with heat for a long time of 1 to 5 minutes during molding, it is extremely susceptible to thermal damage. Therefore, there was originally no room for it to be used in the direct mold exterior of a dry MF capacitor mainly composed of MPPF.

However, as a result of further investigation into the rationality of using the thermosetting resin for the exterior of a dry MF capacitor, the inventor discovered that ``thermosetting unsaturated polyester resin'' is relatively new among thermosetting resins and has unique characteristics. ” was discovered. This thermosetting unsaturated polyester resin has ultra-low temperature moldability (90
-130℃), short-time curing (60-150 seconds), super heat resistance after curing (200℃ or more), does not melt, can be provided with super flame retardancy (UL94-5V), thermal expansion coefficient close to that of metal. It is extremely easy to airtightly seal with the terminal (the coefficient of thermal expansion is 1 for iron).
×10-'/”C1 copper nano-non-ferrous gold 1~1.5X1
0-'/℃, aluminum and its alloys 1.5-2
．． 5 x 10-'/'Ill:, and thermosetting unsaturated polyester resin is 1.0-3.0
- arbitrarily adjustable), and the resin is less likely to crack during molding, which are extremely advantageous conditions for sealing and molding dry-type MF capacitor elements.

That is, the present invention provides a capacitor element in which MF is wound or laminated and metallicon electrodes are provided on both end faces, a lead terminal connected to the metallicon electrode of the capacitor element, and a part of the lead terminal and the capacitor element covered. This is a dry-type MP capacitor constructed from a thermosetting unsaturated polyester resin exterior part.

Note that the thermosetting unsaturated polyester resin has a thermal expansion coefficient of 1 to 3, and a heat molding temperature of 1 to 3.
It has been found that a resin having a molding shrinkage rate of 0 to 0.3% at a temperature of 00 to 140°C is suitable as an exterior resin for a dry type MF capacitor.

Function As mentioned above, in the direct mold sealing of dry-type MPPF capacitors using MPPF as the dielectric material and the newly developed "thermosetting unsaturated polyester resin" as the exterior resin of dry-type MF capacitors, the molding temperature of the resin exterior is can be molded at ultra-low temperatures of 90 to 135°C, and by appropriately setting the molding temperature in the low temperature range, even if the dielectric is MPPF, it can be sealed without affecting the electrical characteristics of dry MPPF capacitors at all. We were able to perform permanent molding.

Next, in order to airtightly seal the terminal part, it is necessary to make special efforts in the shape and structure of the terminal by matching the thermal expansion coefficients of the metal of the terminal material and the thermosetting unsaturated polyester resin of the exterior sealing material. There is no need to apply a silane coupler or other adhesive to the terminal surface, making it possible to reliably achieve the airtight seal necessary to maintain the performance of dry MP capacitors. This made it possible to newly apply the sealing technology obtained by matching or approaching the thermal expansion coefficients of a plurality of different materials to dry MF capacitors.

Examples [Example 1] A pair of MPPFs having a thickness of 51 m and a width of 40 m were wound to form a column-shaped capacitor element 1 with a diameter of 31 mm and a length of 43 mm, and metallicon electrodes 2 were formed on both end faces of the capacitor element 1. FIG. 2 shows a capacitor element in which a lead terminal 3 is attached to the metallicon electrode 2.

The capacitor element 1 is dried in a vacuum tank at a temperature of 85° C. and 0.01 mHg for about 30 hours, filled with and impregnated with an insulating face, Nichiro 180M, thoroughly removed wax adhering to the surface, and cooled to room temperature. The element 1 was inserted into a molding die, thermosetting unsaturated polyester resin was injected into the molding die, and resin exterior molding was performed at a molding temperature of 110°C using a transfer molding machine with a mold clamping pressure of 50 tons.
As a result, the dry MPPF capacitor shown in FIG. 1 is constructed. The capacitance of the dry MPPF capacitor is 18 μF and the rated voltage is 220 V AC.

The thermosetting unsaturated polyester resin used for the exterior is Showa Kobunshi Co., Ltd.'s product name "Revolac" RNC833.
It has improved physical properties for the exterior sealing of dry MPPF capacitors, with a minimum molding temperature of 100°C and a molding shrinkage rate of 0.0.
05%, and the thermal expansion coefficient of the molded product is 1.5×10-'/''C.

In Figures 3 to 5, A is a dry MPPF capacitor of the present invention manufactured as described above, B is a case-botting type dry MPPF capacitor manufactured using the conventional technology, and A and B are dielectric specifications and ratings. The capacity and rated voltage are the same.

Figure 3 shows the results of a continuous durability test according to the JIS C490B test method. Figure 4 shows the capacitance change rate vs. time characteristic. Figure 4 shows the tan δ vs. time characteristic at rated voltage 220 VAC 160 Hz and ambient temperature 75°C. Figure 5 shows the results. -25℃ 120 minutes
Rapid cooling and rapid heating operations at +85℃ for 120 minutes were repeated 100 times, causing severe damage to the terminal sealing part and exterior resin part.
After that, it was heated to 200℃ in an environment of 60℃, 95% high temperature, and high humidity.
FIG. 3 is an insulation resistance-time characteristic diagram between terminals subjected to a 0-hour moisture resistance test.

As a result of the above test, as is clear from the results shown in FIGS. 3 and 4, the dry-type MPPF capacitor A of the present invention did not exhibit comparable electrical characteristics to the conventional dry-type MPPF capacitor B.

That is, this shows that the characteristics of the dry MPPF capacitor did not change even when the MPPF dielectric was exposed to high temperatures and pressures in the mold.

Figure 5 also shows that the terminal sealing part and the exterior resin part are expanded, contracted, and damaged by repeated cooling and heating, and furthermore, in the subsequent moisture resistance test, the dry MPPF capacitor A of the present invention was compared to the conventional dry MPPF capacitor. It did not show any inferiority compared to B. This indicates that there was no deterioration in the characteristics of the capacitor due to abnormal moisture absorption from the terminal sealing portion and the exterior resin portion.

[Example 2] A column-shaped capacitor element with a diameter of 30 mm and a length of 43 mm was manufactured by winding a pair of MPPFs with a thickness of 10 μm and a width of 40 m in the same manner as in Example 1.
After drying in a vacuum of 0.01 inHg at 90°C for about 30 hours, a low viscosity impregnating epoxy resin (viscosity 18
0 to 200 cps) is impregnated and heat cured, and after heat curing is completed, the capacitor element is cooled to room temperature, the capacitor element is inserted into a mold, a thermosetting unsaturated polyester resin is injected into the mold, and the mold is clamped. Using a transfer molding machine with a pressure of 50 mm, the outer shell was molded at a molding temperature of 110° C. to form a dry MPPF capacitor. The capacitance of the dry MPPF capacitor is 4 μF with a rated voltage of 440 μF.

Exterior molding was done using Showa Kobunshi Co., Ltd.'s unsaturated polyester resin product name "Revolac" RLS70, RNC833.
, K515 series, molding temperature and dry MPP
The relationship between the characteristics deterioration of the F capacitor was confirmed through experiments.

The results are shown in FIGS. 6 and 7. Further, Fig. 8 shows actual measured values of the molding temperature and thermosetting time when Rigorasoc RNC833 was used as the exterior resin of the dry MPPF capacitor of the present invention.

Figure 6 is a capacitance change rate-cumulative overcurrent characteristic diagram in which the cumulative overcurrent (A/m) value during 100 charging and discharging cycles is plotted for each molding temperature of the exterior resin, showing the current resistance of a dry MPPF capacitor. It is.

As is clear from FIG. 6, when the molding temperature is 120° C., extremely stable current resistance can be obtained, but when the molding temperature is 140° C. or higher, the dielectric of the dry MPPF capacitor suffers significant thermal damage. In this molding temperature range, dry MP
The intermediate region of 130° C., where the PF capacitor cannot maintain its function, is a usable region, but the influence of thermal deterioration appears.

FIG. 7 shows the results of a continuous durability test based on JIS C4908, and shows a capacitance change rate-time characteristic diagram for each molding temperature.

As is clear from this result, the characteristics tend to be similar to those shown in FIG. 6, and when the molding temperature exceeds 140° C., the dry MPPF capacitor loses its function.

Figure 8 shows the molding temperature of the exterior resin Rigorasoku RNC833.
A thermal curing time characteristic diagram showing the limits of the cured area and uncured area.

From this result, the lower limit of the moldable temperature range is approximately 100℃.
It turned out to be.

At lower temperatures, the resin will harden over time, but
The desired physical strength cannot be expected. Experiments have also revealed that other resin grades, RLS70 and 515 series, exhibit similar heat curing time characteristics.

Combining the above results, it can be concluded that when the molding temperature is in a high temperature range exceeding 140°C, the electrical characteristics of dry MPPF capacitors rapidly deteriorate, and in a low temperature range below 100°C, the resin cannot be sufficiently cured, and the specified resin Physical properties cannot be obtained. Therefore, thermosetting unsaturated polyester resins, especially dry M
Even if it is a low-temperature molding grade developed as an exterior resin for PPF capacitors, it is very difficult to use it in the dry MPPF capacitor according to the present invention unless the above-mentioned molding temperature conditions are reliably observed.

In the above embodiment, a dry MPPF using MPPF as a dielectric material is used.
Although we have explained about capacitors, dry-type MF capacitors using MF other than MPPF for the dielectric are also explained.
The same tendency as in the case of the PPF capacitor was shown, and the dry MF capacitor of the present invention showed superior electrical characteristics compared to the conventional dry MF capacitor.

Also, although the above explanation was about a wound type MF capacitor,
A multilayer dry type MF capacitor in which MF is laminated also exhibits electrical characteristics similar to those of a wound type dry type MF capacitor.

Effects of the Invention As described above, the dry MF capacitor of the present invention uses a thermosetting unsaturated polyester resin for low-temperature molding as the exterior resin.・Conventional dry type M with resin exterior under high pressure
Compared to F capacitors, it can be coated with resin at a lower temperature.
In addition to being easy to package, the capacitor's electrical performance and characteristics do not deteriorate, and its quality is stable.

(b) No component parts other than the capacitor element and two terminals are required, reducing the number of parts and materials.

(c) Since all the assembly processes are concentrated in the mold, manufacturing time can be shortened by shortening the process and man-hours, in other words, productivity can be streamlined, and costs can be reduced.

It has the following effects and is of great industrial and practical value.

[Brief explanation of the drawing]

FIG. 1 is a front cross-sectional view of one embodiment of a dry metalized polypropylene film capacitor of the present invention, FIG. 2 is a perspective view of a capacitor element of the capacitor shown in FIG. 1, and FIGS. Figure 3 is a comparison of the electrical characteristics diagrams of a dry-type metalized polypropylene film capacitor and a conventional dry-type metalized polypropylene film capacitor, and is based on JIS C4908.
Figure 4 shows the capacitance change rate vs. time characteristic diagram in the continuous durability test based on Figure 3.
tan δ- at 20■, 60Hz, ambient temperature 75℃
The time characteristic diagram, Figure 5, shows that after repeating the rapid cooling and heating operations 100 times at -25°C for 120 minutes and +85°C for 120 minutes,
Figure 6 shows the insulation resistance vs. time characteristics in a humidity test at 0°C and 95% humidity. Figure 6 shows the capacitance change rate vs. cumulative overcurrent characteristics for each molding temperature of the resin exterior in a current withstand test of a dry metallized polypropylene film capacitor. Figure 7 shows JIS C49 dry metalized polypropylene film capacitors.
Figure 8 shows the capacitance change rate vs. time characteristic diagram for each molding temperature of the resin casing in the continuous durability test based on 08. A molding temperature-thermal curing time characteristic diagram is shown. 1: Capacitor element 2: Metallicon electrode 3: Output terminal 4: Thermosetting unsaturated polyester resin exterior A: Dry metallized polypropylene film capacitor of the present invention B: Conventional dry metallized polypropylene film capacitor

Claims (1)

[Claims] (1) A capacitor element made by winding or laminating metallized plastic film and having metallicon electrodes on both end faces,
A dry metallized plastic comprising a lead-out terminal connected to a metallicon electrode of the capacitor element, and a thermosetting unsaturated polyester resin exterior covering a part of the lead-out terminal and the capacitor element. Film capacitor.