JPS6114716A - Method of producing capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method of manufacturing a capacitor.

Conventional Structure and Problems Therein FIG. 2 shows a cross-sectional view of a conventional capacitor consisting of a metallized film and a laminated film. In Figure 2,
1 is a first dielectric film with vapor-deposited metal films 2 and 3 formed on both sides; 4 is a second dielectric film which is alternately stacked with the first dielectric film 1; and 5 and 6 are metallicons, respectively. .

In the above capacitor, the first dielectric film 1 is made of polyethylene terephthalate, polypropylene, polysulfone, etc., and the vapor-deposited metal 1j! 2
．． Aluminum, zinc, etc. are used as the material for 3.
Further, as the material for the second dielectric film 4, the same material as the first dielectric film 1 can be used, and in this case, since metal vapor deposition is not performed, there is no need to consider vapor deposition properties.

In such conventional capacitors, a gap X occurs between the vapor-deposited metal film 2°3 and the second dielectric film 4, which causes corona to occur when an electric field is applied between the electrodes. There is. Therefore, the corona generation voltage becomes low and the design potential gradient in practical use becomes low, causing the capacitor to become larger.

Purpose of the Invention The purpose of the invention is to provide a method for manufacturing a capacitor that can reduce the size and weight of the capacitor by minimizing the gap between the capacitor electrode (deposited metal film) and the second dielectric film to improve the potential gradient of the dielectric. The goal is to provide the following.

Structure of the Invention This invention provides polypropylene with a melt index of 10 g/10 minutes or less (where x, x' are -H, -OH, -COOH, which are the same or different, and n 30 parts by weight or less of polybutadiene having an unsaturated bond represented by (average value is 18 to 60) is mixed into 100 parts by weight of the polypropylene, and after mixing, a non-stretched film is prepared, and further stretched to form a film, After forming a capacitor using the film as a second dielectric film 4' as shown in FIG. They are brought into close contact as shown in Figure (B).

[9! 2.

It has the effect of improving the adhesion with 3 and minimizing the gap between them.

In this way, the second dielectric film 4' is made of polypropylene mixed with polybutadiene, and the first and second dielectric films 1.4' are superimposed and then heat-treated to form the vapor-deposited metal. The adhesion between the membrane 2.3 and the second dielectric film 4' is increased, the gap between them is minimized, the corona generation voltage can be increased, and the potential gradient of the dielectric can therefore be increased. As a result, the capacitor can be made smaller and lighter.

Description of Examples Isotactic polypropylene with a density of 0.9 and a melt index of 3 and polybutadiene with an average molecular weight M=3000 (terminal group is -H) were mixed into the polypropylene 100.
After mixing 10 parts by weight at about 220 to 250°C, it is formed into a film, rapidly cooled, and further stretched to obtain a film with a thickness of about 5 microns. It is the second
The first dielectric film (double-sided vapor deposited film) is a polyethylene terephthalate film (7.5 micron thick) with aluminum vapor-deposited electrodes on both sides to form a capacitor. After forming a capacitor element, both ends are treated with metallicon, and then heat treated at about 110 to 120° C. for about 8 hours. After the capacitor element is inserted into a resin case, resin is injected into the gap between the capacitor element and the case to form a capacitor. The capacitance of the obtained capacitor was 10 μF. A step-up withstand voltage test was conducted for 1 hour at 50V intervals from 200V at a temperature of 75°C for the capacitors according to the present invention and the conventional polypropylene film used as the second dielectric film (laminated film). . As a result, the conventional one broke at one place at 400V and four places at 450V, and the example broke at one place at 450V and four places at 500V, and these results were confirmed.

As a result of various experiments, it was found that polypropylene with a melt index of 10 g/10 minutes or less is suitable for obtaining the optimum film, and as an additive, polybutadiene with an -OH terminal group and - COO
Similar excellent results were confirmed for the hydrogenated product.

Furthermore, it was also confirmed that their average molecular weights are not limited to 3000. Furthermore, regarding the mixing ratio of the additive to the resin, the propylene resin 100%
It was also confirmed that the desired effect can be obtained if the amount is 30 parts by weight or less. In addition, the mixing ratio of additives is 31M
If the amount exceeds a certain amount, the heat resistance and crystallinity of polypropylene were adversely affected, and the dielectric strength voltage tended to decrease.

Effects of the Invention According to this invention, the corona starting voltage of the manufactured capacitor is high, and the amount of corona generated is small in the same electric field, making it possible to design a dielectric material with a high potential gradient, and achieving a reduction in size and weight of the capacitor. can.

[Brief explanation of the drawing]

FIGS. 1A and 1B are cross-sectional views for explaining the steps of the capacitor manufacturing method of the present invention, and FIG. 2 is a cross-sectional view of a conventional capacitor.

Claims (1)

[Claims] A first dielectric film with metal films formed on both sides and polypropylene with a melt index of 10 g/10 minutes or less ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, X, X' 30 parts by weight or less of polybutadiene represented by -H, -OH, and -COOH, which are the same or different, and the average value of n is 18 to 60, is mixed into 100 parts by weight of the polypropylene. 1. A method for manufacturing a capacitor, the method comprising: alternately stacking and heat-treating second dielectric films.