JP2950575B2 - Electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to an electrolytic capacitor having an electrolyte held between electrodes by a separator.

[Prior art]

Electrolytic capacitors use a so-called valve metal in which an insulating oxide film is formed on the surface of a metal such as aluminum, tantalum, or niobium at least as an anode electrode. The anode metal has a desired thickness by an operation such as anodizing treatment. An insulating oxide film is formed, and this film is used as a dielectric layer. There are various shapes of the anode electrode, and the main one has an element structure in which a long foil is wound together with a long separator and a cathode. There is also a laminated capacitor element in which a foil electrode and a separator are overlapped. In these capacitor elements, a liquid or solid electrolyte is held by a separator, and this electrolyte directly contacts the dielectric oxide film layer to function as a true cathode. Further, although outside the scope of the present invention, an element using a block-shaped porous valve metal body as an anode without using a separator in an element is known. As the liquid electrolyte, those obtained by dissolving an organic acid, an inorganic acid, or a salt thereof in various organic solvents such as ethylene glycol and γ-butyrolactone or water are used. As the solid electrolyte, a semiconductor inorganic compound such as manganese dioxide and lead dioxide, and a conductive organic compound such as tetracyanoquinodimethane, polyacetylene, and polypyrrole are used. As described above, the separator has a function of holding the electrolyte between the electrodes and preventing a short circuit between the anode and the cathode. If the material of the separator is a liquid electrolyte,
Paper is often used, and as its raw material, a material using relatively long fiber pulp called kraft, a material using manila hemp fiber, and the like are frequently used. In the case of a solid electrolyte using manganese dioxide which requires a thermal denaturation step, a thin glass fiber cloth other than paper may be used.

[Problems to be solved by the invention]

The function required for the separator is to maintain a necessary and sufficient amount of the electrolyte between the anode and the cathode, and since the electrolyte is interposed between the electrodes, sufficient conductivity is maintained so that the loss characteristics and the like are not deteriorated. Is required. However, if the thickness and density of the separator are reduced more than necessary in order to improve the electrical conductivity, an accident such as a short circuit between the electrodes may occur. In addition, it is difficult to make the separator thinner than a certain level, and the practical limit is about 20 μm for paper and several tens of μm for glass fiber. Inconvenience such as occurrence of Furthermore, in the case of electrolytic capacitors using liquid electrolyte, the temperature range during manufacture or in the operating temperature range does not increase significantly. Since the process of thermal denaturation at a temperature of 250 ° C. or more is repeated at the time of the formation, a separator having heat resistance may be required in some cases. The present invention has been made to solve the above-described problems, and by adopting a novel separator,
The purpose is to obtain an electrolytic capacitor having excellent characteristics.

[Means for Solving the Problems]

The electrolytic capacitor of the present invention is formed by winding or laminating an anode electrode having a dielectric oxide film layer formed on the surface thereof, a separator between the anode electrode and the cathode electrode, and including the polyamideimide fiber in the separator. It is characterized by using a thing. Polyamideimide resin is Having a very high thermal stability and excellent mechanical properties such as tensile strength and elastic modulus, and has been conventionally used as a resin processed product for various uses. The separator used in the present invention may be a sheet made of polyamide imide fiber or a mixture of existing pulp and manila hemp fiber. Polyamideimide fibers having a fiber diameter of 10 μm or less have been put to practical use. By using such particularly thin fibers, a thin separator having a thickness of 20 μm or less can be obtained.

[Action]

As described above, the polyamideimide fiber has extremely high tensile strength, heat resistance, and chemical resistance. Therefore, a separator using all or a mixture of these fibers has high tensile strength, high heat resistance, and high heat resistance. Has chemical properties. For this reason, the tension applied to the separator during the manufacture of the wound element can be increased, and the capacitor element can be firmly wound. Further, since a separator thinner than the conventional one can be used to obtain the same tensile strength, the capacitance value per unit volume is increased and the loss is reduced. Furthermore, since it is excellent in heat resistance and chemical resistance, it is not affected by high-temperature treatment or generated gas as in the case of forming a manganese dioxide electrolyte.

【Example】

Hereinafter, the present invention will be described in more detail with reference to examples. FIG. 1 shows the element structure of the electrolytic capacitor of the present invention. The figure shows a capacitor element 1 with a wound structure
FIG. 2 is a partially exploded front view showing a separator 3 slightly wider than the anode 2 using a valve metal foil made of aluminum, tantalum, or the like cut into a belt shape, and the same width as the anode. The cathode 4 made of metal foil is overlapped as shown in the figure and wound from one end to form a cylindrical capacitor element 1. In this case, two separators 3 were used, and the anode 2 was also used on the back side of the winding.
And the cathode 4 do not come into contact with each other. Anode 2
Lead wires 5 and 6 for obtaining electrical connection with the outside are connected to the cathode 4 and the cathode 4, respectively, and are led out from one of the winding end faces. In this capacitor element 1, a liquid or solid electrolyte is permeated into the separator 3 by a predetermined process to be maintained. The capacitor element 1 having been subjected to the electrolyte infiltration treatment may be housed in a metal case or sealed with a resin to perform an exterior treatment, if necessary. As an example of the present invention, first, an electrolytic capacitor using a liquid electrolyte was prepared and its characteristics were examined. (Example 1 of the present invention) The electrolytic capacitor used in this example of the present invention uses a wound type capacitor element, and has a rated voltage of 63 V and a rated capacitance of 1
000 μF. The capacitor element has a thickness of 9
Using a high-purity aluminum foil having a thickness of 0 μm, an electrochemical etching treatment was performed to increase the surface area of the aluminum foil, and then a voltage of 90 V was applied to the surface by anodic oxidation to form a dielectric layer of aluminum oxide. The anode foil was cut into a strip having a width of 24 mm and a length of 450 mm, and an anode lead was connected by crimping. An aluminum foil having a thickness of 50 μm was used as the cathode foil, and was also cut into a band shape. To these electrode foils, leads for connecting the electrodes are connected, and a band-shaped separator made of polyamideimide fiber having a thickness of 40 μm is interposed between the two electrode foils.
It was wound with a winding tension of 2 kg to obtain a capacitor element. Next, the capacitor element was impregnated with an electrolytic solution containing ammonium adipate as a main solute, stored in a cylindrical ammonium case, and the opening was sealed with elastic rubber to obtain an electrolytic capacitor. (Comparative Example 1) The same anode foil and cathode foil as those of Example 1 of the present invention were used. As the separator, electrolytic paper of Manila hemp blended paper having a thickness of 40 sealed was used, and these were overlapped and wound with a winding tension of 1 kg to form a capacitor element. This capacitor element was impregnated with the same electrolytic solution as in Example 1 of the present invention, and was packaged in the same manner to obtain an electrolytic capacitor. When the characteristics of these electrolytic capacitors were measured, the results shown in Table 1 below were obtained. The loss is a value at 120 Hz, and the leakage current is a value of one minute after the rated voltage cathode. Next, an example using a solid electrolyte as an electrolyte will be described. (Example 2 of the present invention) For the formation of the capacitor element, the same material as in Example 1 of the present invention was used for the anode side electrode and the separator. Also, the winding tension was set to the same value as that of Example 1 of the present invention. This capacitor element is immersed in an aqueous solution of manganese nitrate, and then
C. for 10 minutes to convert manganese nitrate to manganese dioxide. This step was repeated three times. (Comparative Example 2) The same anode-side electrode as that of Example 1 of the present invention was used, and a separator having a thickness of 100 µm made of glass fiber was used and wound with a winding tension of 1 kg to obtain a capacitor element. In this capacitor element, a solid electrolyte layer made of manganese dioxide was formed in the same manner as in Inventive Example 2. When the initial electrical characteristics of the electrolytic capacitor using the solid electrolyte thus prepared were measured, the results shown in Table 2 were obtained. As can be seen from these results, first, in the case of the electrolytic capacitor using the liquid electrolyte, the electrolytic capacitor using the separator of the present invention can be wound with high winding tension. Further, since the fiber diameter is small, the gap between the fibers becomes uniform, and the air permeability of the separator is improved. By improving the air permeability and reducing the distance between the electrodes, a capacitor having a small loss can be obtained. Further, in Example 2 of the present invention, the separator can be made thin, and as a result, the diameter of the capacitor element becomes small. Conversely, if the diameter of the capacitor element is made the same as the conventional one, the amount of winding of the electrode can be increased, and the capacitance increases accordingly.

【The invention's effect】

As described above, the electrolytic capacitor using the separator containing the polyamide-imide fiber of the present invention can form a capacitor element with a high tension because the mechanical strength of the polyamide-imide fiber is high. Is obtained. Further, since it is excellent in heat resistance and can be formed thinner than glass fiber cloth, stable characteristics can be maintained and the size of the capacitor can be reduced.

[Brief description of the drawings]

FIG. 1 is a partially exploded front view showing the element structure of the electrolytic capacitor of the present invention. 1 ... capacitor element, 2 ... anode, 3 ... separator, 4 ...
Cathode, 5,6 ... Leader.

Claims (2)

(57) [Claims] 1. A capacitor element formed by winding or laminating a separator made of polyamideimide fiber between an anode electrode having a dielectric oxide film layer formed on its surface and a cathode electrode, thereby forming a capacitor element. An electrolytic capacitor in which an electrolyte is held in a separator part. 2. A capacitor element is formed by winding or laminating a separator containing polyamide-imide fibers between an anode electrode having a dielectric oxide film layer formed on its surface and a cathode electrode, thereby forming a capacitor element. An electrolytic capacitor in which an electrolyte is held in the separator of the element.