JPH0118569B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF INDUSTRIAL APPLICATION This invention relates to metallized film capacitors. Conventional structure and its problems Traditionally, metallized film capacitors
As shown in Fig. 1, a double-sided metallized PET film 1, which has metal electrode layers 1a formed on both sides of a polyethylene terephthalate film (hereinafter referred to as PET film), which has particularly excellent electrical properties, productivity, and economic efficiency, is used as a film. A metallized film capacitor in which polypropylene films 2 (hereinafter referred to as PP films) are integrally wound or laminated and electrodes 4 are formed on the end faces of the obtained capacitor element 3 is well known. In the dielectric constant-temperature characteristic of the PET film 1, the dielectric constant increases as the temperature rises, whereas in the dielectric constant-temperature characteristic of the PP film 2, the dielectric constant decreases as the temperature increases. In addition, the rate of increase in dielectric constant due to temperature rise of PET film 1 and that of PP film 2 are also shown.
It is almost equal to the rate of decrease in dielectric constant as temperature rises. Therefore, the film capacitor using the above-mentioned PET film 1 and PP film 2 as a composite dielectric has the excellent advantage that the dielectric constant-temperature characteristic is stable, that is, the capacitance-temperature characteristic is flat. Furthermore, since the PP film 2 has high voltage resistance and a small dielectric loss tangent, that is, generates little heat during use, a capacitor using this PP film 2 has a high breakdown voltage. On the other hand, the PET film 1 has a high dielectric constant and is particularly economical. Therefore, a film capacitor using PET film 1 and PP film 2 as a composite dielectric has many advantages such as stable capacitance-temperature characteristics, high withstand voltage, and excellent economic efficiency. had. However, there is a strong demand for smaller and lighter capacitors, and impregnated capacitors are considered to meet this demand. However, since PP film 2 was used as the laminated film, there was a problem of poor impregnability. This is because the compatibility between the impregnating agent and the PP film 2 is poor due to chemical factors such as the surface condition and wetting properties of the PP film 2. Therefore, double-sided metallized PET film 1
The capacitor element 3 obtained by winding or laminating the PP film 2 as a film was not uniformly impregnated with the impregnating agent, and it was not possible to prevent the film from deteriorating due to corona discharge and the vapor-deposited metal electrode from scattering. . That is, it has been impossible to further improve the withstand voltage of the film in the capacitor element 3 and to reduce the change in capacitance to make the metal film capacitor smaller and lighter. Purpose of the Invention This invention uniformly impregnates a capacitor element with an impregnating agent, thereby preventing film deterioration and metal electrode scattering due to corona discharge, improving the withstand voltage of the film, and reducing capacitance changes. The purpose is to make capacitors smaller and lighter. Structure of the Invention The metallized film capacitor of the present invention has a double-sided metallized film in which metal electrode layers are formed on both sides of a plastic film whose dielectric constant decreases as the temperature rises and has poor wettability. A metallized film capacitor element is constructed by overlappingly winding or laminating a laminated film using another plastic film whose dielectric constant increases and whose rate of increase corresponds to the dielectric constant of the plastic film and has wettability. , this element is impregnated with an impregnating agent, and electrodes are further formed on the end faces of the element. In this way, in this invention, by forming metal electrode layers on both sides of a plastic film that has poor wettability, chemical factors such as the surface condition and wettability of the film are improved, and furthermore, as a laminated film, it has excellent wettability. By using another film, it is possible to uniformly impregnate the impregnating agent into the metallized film capacitor element. DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 2 to 8. That is, in Figure 2, 5
is double-sided metallization with metal electrode layers 5a deposited on both sides.
PP film, 6 was used as a laminated film
A PET film is formed by overlapping a PET film 6 on the double-sided metallized PP film 5 to form a wound capacitor element 7, an electrode 4 is formed on the end face of this element 7 by metallicon, and an impregnating agent is added inside the element 7. 8. Regarding the metallized film capacitor thus obtained and the conventional capacitor shown in FIG.
The impregnating property of the impregnating agent was investigated. First, Table 1 shows the results of examining the impregnation properties of various films. In the test, various PET films or PP films with different surface conditions, or films with a width of 300 mm made by metallizing both sides of these films, were each wound 40 times around a core (diameter 28 mm) at a constant winding force of 750 g. As shown in Figure 3, the film was placed vertically in a container containing an impregnating agent up to a height of 25 mm, and after 10 hours, the height h of the impregnating agent was measured, and the impregnating property of each film was measured. did. In FIG. 3, 9 is a winding core, 10 is a sample film, 11 is an impregnating agent, and 12 is a container.
The surface conditions shown in Table 1 were determined according to JIS B 0601 (Film Surface Roughness), and the larger the value of the center line average roughness Ra, the rougher the film surface.

[Table] As is clear from Table 1, the thickness of sample No. 1
The impregnability of the PET film of 7 μm and Ra=0.09 was extremely good. Thickness of sample No. 2: 6μm, Ra=
The impregnability of the PP film with Ra = 0.09 is very poor, and the impregnability of Sample No. 3, the PP film with Ra = 0.25, is improved due to its rough surface, but it is not as good as that of the PET film. Sample No. 4, a PET film with metallization on both sides, and Sample No. 5, a PP film with metallization on both sides, have the same surface covered with metal, so their impregnability is almost the same. It was equally good. Next, using a testing device as shown in Fig. 4, a double-sided metallized PP film obtained by metallizing both sides of the 6 μm thick PP film of sample No. 5, and a 7 μm thick PP film of sample No. 1,
The metallized film capacitor of this example shown in Fig. 2 using a PET film with Ra = 0.09, the double-sided metallized PET film made by metallizing both sides of the 7 μm thick PET film of sample No. 4, and sample No. 4. 2 thickness
Using a 6μm, Ra=0.09 PP film, we investigated its impregnability with the conventional metallized film capacitor shown in Figure 1. In FIG. 4, 13 is a glass container, 14 is a metallized film capacitor of the embodiment, 15 is a conventional metallized film capacitor,
16 is an impregnating agent, and 17 is a vacuum chamber. In the test, impregnation was performed for 10 hours at a vacuum level of 0.5 mmHg, and the impregnation state and impregnation rate of the capacitor were investigated. FIGS. 5A and 5B show the state of impregnation of the impregnant into the film layer of the disassembled film surfaces of the metallized film capacitor of this embodiment and the conventional metallized film capacitor after impregnation, respectively. Fifth
In figures A and B, 6 is the thickness of sample No. 1, 7 μm.
PET film with m, Ra = 0.09, 5 is a double-sided metallized PP film made by metalizing both sides of the 6 μm thick PP film of sample No. 5, 2 is a 6 μm thick PP film of sample No. 2, Ra
=0.09 PP film, 1 is sample No. 4 thickness 7μm
Double-sided metallization of PET film with metallization on both sides
PET film 8 is impregnated with impregnating agent. From this result, the metallized film capacitor 14 of the example uses the double-sided metalized PP film 5 and the PET film 6, but as is clear from the table above, both the double-sided metalized PP film 5 and the PET film 6 have impregnability. The film was so good that the entire surface of the film was uniformly impregnated as shown in FIG. 5A. Next, the conventional metallized film capacitor 15 uses a double-sided metalized PET film 1 and a PP film 2, but as is clear from the above-mentioned Table 1, the impregnability of the double-sided metalized PET film 1 is good. Yes, but
Since the impregnating properties of the PP film 2 are poor, only the ends of the film surface are impregnated, as shown in FIG. 5B. Next, using a double-sided metallized PP film 5, which is a 6 μm thick PP film with metallization on both sides, and a 7 μm thick PET film 6, the metallized film capacitor of this example shown in FIG. value
10μF, and 7μm thick PET
A conventional metallized film capacitor shown in Fig. 1 was made using a double-sided metallized PET film 1 in which both sides of the film were metallized and a PP film 2 with a thickness of 6 μm so that the capacitance value before impregnation would be 10 μF, the same as above. After the preparation, impregnation with an impregnating agent was carried out for 10 hours at a vacuum degree of 0.5 mmHg using the testing apparatus shown in FIG. 4 described above. Table 2 shows the capacitance changes between the metallized film capacitor of this example and the conventional metallized film capacitor before and after impregnation.

[Table] *The capacitance after impregnation is an average value.
From the results in Table 2, it can be seen that while the capacitance of the conventional metallized film capacitor remains almost the same before and after being impregnated with the impregnating agent, the capacitance of the capacitor of this example has increased significantly. In other words, although conventional metallized film capacitors use double-sided metalized PET film 1 with good impregnability,
Since PP film 2 with poor impregnation properties is also used,
Poor impregnability as a capacitor element. On the other hand, the metallized film capacitor of the example uses a double-sided metallized PP film 5 with good impregnability and a PET film 6 with good impregnability, so it has good impregnability as a capacitor element. be. Furthermore, Figure 6 shows the high temperature (70°C) of the metallized film capacitor of this example and the conventional metallized film capacitor after impregnation, which were prepared in the same manner as described above.
The voltage-breakdown time characteristics (hereinafter referred to as VT characteristics) are shown in FIG. From FIG. 6, it can be seen that the metallized film capacitor of this example has the effect of improving the V-T characteristic by about 12% compared to the conventional metallized film capacitor. Figure 7 is JIS C
4908 indicates the rate of change in capacity after a continuous durability test of 1000 hours at an applied voltage of 350 VAC. As is clear from FIG. 7, the metallized film capacitor of this embodiment is more effective in reducing capacitance changes than the conventional metallized film capacitor. 6th
The improvement in the V-T characteristics and capacitance change rate of the metallized film capacitor of this example shown in Fig. 7 and Fig. 7 is due to the uniform impregnation between the film layers throughout the film, which is caused by corona discharge. This is because deterioration of the film and scattering of the vapor-deposited metal electrode layer were suppressed. Effects of the Invention According to the present invention, the impregnation property of the impregnating agent into the capacitor element is improved, and as a result, the withstand voltage of the film used in the capacitor element is increased, the capacitance is increased, and the capacitance change is further reduced. This has the effect of making the capacitor smaller and lighter.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the main structure of a conventional metallized film capacitor, Fig. 2 is a sectional view showing the main structure of an embodiment of the present invention, and Fig. 3 is a method for measuring the impregnability of film materials. FIG. 4 is an explanatory diagram of a test device for testing the impregnating properties of metallized film capacitors, and FIGS. 5 A and B show impregnating agents for the metallized film capacitor of the example and the conventional metallized film capacitor, respectively. FIG. 6 is a graph of voltage-breakdown time characteristics under high temperature, and FIG. 7 is a graph of capacity change rate in continuous durability test. 4...Electrode, 5...Double-sided metallized PP film (double-sided metalized film), 5a...Metal electrode layer, 6
...PET film (laminated film), 7... Capacitor element, 8... Impregnating agent.

Claims (1)

[Claims] 1. A double-sided metallized film, in which metal electrode layers are formed on both sides of a plastic film whose dielectric constant decreases and has poor wettability as the temperature rises, and a double-sided metallized film that is superimposed on this film and is integrally wound or laminated to increase the temperature. A laminated film consisting of another plastic film having wettability, the dielectric constant of which increases as the plastic film increases, and whose rate of increase corresponds to the rate of decrease of the dielectric constant of the plastic film, and this laminated film and the double-sided metallized film. A metallized film capacitor comprising an impregnating agent impregnated into a wound or laminated metallized film capacitor element, and an electrode formed on an end surface of the capacitor element.