JPH01235225A - Separator for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain an electrolytic capacitor having little short-circuit failures due to inside burr and fine powder of aluminum, by using mixed paper of single unit body or composite body of vegetable fiber or synthetic resin fiber or glass fiber and floss silk fiber. CONSTITUTION:Raw material of floss silk is cocoon. The diameter of its fiber is small and 1/2-1/100 of Manila hemp, and the bending of fiber is complicated. The floss silk fiber having property like this is made into vegetable fiber such as Manila hemp, and mixed paper is manufactured. In this case, the floss silk fibers closely entangle in the gap between thick fibers of Manila hemp or kraft, and very thin gaps are formed. As a result, it is remarkably decreased that burr of electrode foil or burr of leading-out wire or fine powder of aluminum penetrates a separator. The breakdown strength of the separator being an electrolytic paper is also improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a separator in an electrolytic capacitor in which an anode M[i made of aluminum foil or the like and a cathode foil are laminated or wound together with a separator interposed therebetween. .

[Prior Art] Generally, an aluminum electrolytic capacitor is manufactured by laminating an anode foil and a cathode foil made of aluminum foil with a separator in between, or by impregnating a wound capacitor element with an electrolytic solution and assembling it together with a sealing body in an exterior case. It has an intricate structure.

In such laminated or wound type electrolytic capacitors, a separator is used to retain a sufficient amount of electrolyte and to prevent short circuits between the electrodes. Most of the materials for manufacturing separators are vegetable fibers or synthetic resin fibers.

Most separators made of vegetable fibers are kraft paper or Manila hemp paper. In addition, small amounts of items made from Indian solar hemp and cotton are also used.

Although kraft paper is cheap and strong, it has the disadvantage that the fibers are flat, so the current path after being impregnated with electrolyte becomes long and the electrical resistance increases. Manila hemp paper has a fiber shape that is slightly more circular than kraft paper, and the current path is shorter, so it has the advantage of reducing resistance, but it is expensive. Papers made from a mixture of kraft and manila hemp are also used.

Examples of the material for the separator made of synthetic resin Ia fibers include polypropylene, vinylon, rayon, polyethylene, and polyester. These synthetic resin fibers can be obtained in a shape close to a perfect circle, so they can have a low resistance value after being impregnated with an electrolyte, but the disadvantage is that it is difficult to obtain a material with good properties as paper. It is often used as kraft or mixed paper with Manila hemp.

Glass fibers are also used, but glass fibers are rarely used alone, and are used as a mixed paper with vegetable fibers and synthetic resin fibers.

[Problems to be Solved by the Invention] As described above, an aluminum electrolytic capacitor is produced by impregnating an electrolyte into a capacitor element in which an anode foil and a cathode foil made of aluminum foil are wound with a separator interposed therebetween, and an outer case together with a sealing body. However, in addition to using a high-conductivity electrolyte, increasing the surface thickness of the foil, increasing the number of lead wires from the foil, and increasing the thickness of the separator, By making the electrolytic capacitor thinner, the equal series resistance value of the electrolytic capacitor can be lowered.

The thickness of the separator is preferable because the thinner the separator, the lower the equal series resistance value of the electrolytic capacitor. However, as a separator, its thickness is 30
If a thin material such as μm is used, the burr on the electrode foil that is generated when the electrode foil is slit, or the burr that is generated when the electrode foil and the leader wire are caulked, will pass through the space between the fibers of the separator, and the other electrode will pass through the space between the fibers of the separator. It is not likely to cause electrical short-term failures due to contact with the foil.

[Means for Solving Problem X1] However, in order to solve the above problems, the present invention provides a separator made of mixed paper containing cotton fibers.

The raw material for cotton cotton is cocoon, and the fibers have a thinner thickness of 172 to 17,100 than Manila hemp, and the fibers have complicated bends. When cotton fibers with such properties are mixed with vegetable fibers such as Manila hemp or kraft to create a mixed paper, the cotton fibers are tightly entangled in the gaps between the thick fibers of Manila hemp or kraft, and the thin gaps created by the scraping occur. form. Therefore, the penetration of the above-mentioned electrode foil flakes, lead wire flakes, or aluminum fine powder through the separator is greatly reduced. Furthermore, the withstand voltage of the separator, which is electrolytic paper, is also improved.

The separator according to the present invention is made of cotton fibers mixed with other vegetable fibers, synthetic resin fibers, glass fibers, or mixed fibers of stiff straw.

[Example] Example 1 Thickness 3 consisting of 70% Manila hemp fiber and 30% cotton fiber
A mixed paper of 0 μm was prepared. An electrolytic capacitor with a rating of 25 V and 470 μF was prepared using this mixed paper and a γ-butyrolactone-based electrolyte.

Comparative Example 1 Paper with a thickness of 30 μm was made from 100% Manila hemp fiber,
An electrolytic capacitor similar to that in Example 1 was created.

Example 2 Thickness 3 consisting of 70% kraft fiber and 30% cotton fiber
A mixed paper of 0 μm was prepared. By using this mixed paper and using an ethylene glycol electrolyte,
■・A 10 μF electrolytic capacitor was created.

Comparative Example 2 Paper with a thickness of 30 μm was made from 100% kraft fiber,
An electrolytic capacitor similar to that in Example 2 was created.

Example 3 A mixed paper having a thickness of 30 μm was prepared consisting of 30% Manila hemp fibers, 40% kraft fibers, and 30% cotton fibers. Using this mixed paper and an ethylene glycol electrolyte, an electrolytic capacitor with a rating of 200 V and 22 μF was created.

Comparative Example 3 An electrolytic capacitor similar to that in Example 3 was prepared by preparing a 30 μm thick mixed paper consisting of 40% Manila hemp fibers and 60% kraft fibers.

Example 4 30μ thickness consisting of 20% polypropylene fibers, 30% glass fibers, 20% Manila hemp fibers and 30% cotton fibers
A mixed paper of m was prepared. Using this mixed paper, we also used γ-
Using butyrolactone electrolyte, rated at 50V/1
A 00μF electrolytic capacitor was created.

Comparative Example 4 A mixed paper with a thickness of 30 μm consisting of 30% polypropylene, 40% glass fiber and 30% Manila hemp fiber was prepared,
An electrolytic capacitor similar to that in Example 4 was created.

Next, a rated voltage was applied to each of 100 electrolytic capacitors of Examples 1 to 4 and Comparative Examples 1 to 4, and short circuit failures were measured, and the failure rates were as shown in Table 1.

Table 1: Short-circuit defects in electrolytic capacitors [Effects] As can be seen from Table 1, the cotton fiber mixed paper according to the present invention can provide electrolytic capacitors with fewer short-circuit defects due to internal Paris and aluminum fine powder. .

Patent applicant: Elna Co., Ltd.

Claims (1)

[Claims] (1) A separator for electrolytic capacitors made of paper mixed with plant fibers, synthetic resin fibers, or glass fibers alone or in combination with cotton fibers.