JP2706954B2 - Separator for electrolytic capacitor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a separator in an electrolytic capacitor in which an anode foil and a cathode foil made of aluminum foil or the like are laminated or wound via a separator.

[Prior art] Generally, an aluminum electrolytic capacitor is formed by laminating an anode foil and a cathode foil made of aluminum foil via a separator, or impregnating a wound capacitor element with an electrolyte,
It has a structure that is incorporated in the outer case together with the sealing body.

In such a laminated or wound electrolytic capacitor, the separator is used to hold a sufficient amount of the electrolytic solution and to prevent a short circuit between both electrodes. The material for producing the separator is a vegetable fiber or a synthetic resin fiber.

Most of the separators made of vegetable fibers are kraft paper or manila linen paper. In addition, small quantities of materials made from Indian hemp and cotton are also used. Kraft paper is an inexpensive and strong paper, but because the fibers are flat, the current path after impregnating the electrolyte becomes longer,
There is a drawback that the electric resistance value increases. Manila hemp paper has the advantage that the resistance value is smaller than that of kraft paper because the shape of the fibers is slightly closer to a circle and the current path is shorter. Also, mixed paper of kraft and Manila hemp is used.

Examples of the material of the separator made of synthetic fibers include polypropylene, vinylon, rayon, polyethylene, and polyester. Such synthetic fibers have a fiber shape close to a perfect circle, so that a low resistance value after impregnation with an electrolyte can be obtained.However, it is difficult to obtain a paper having good properties as paper. Yes, it is often used as a mixed paper with craft or manila hemp.

[Problems to be Solved by the Invention] In an electrolytic capacitor using the separator as described above, the resistance value is still high, the amount of retained electrolyte is small, and when viewed as an electrolytic capacitor, the electric capacitance at room temperature and low temperature is low. When used in a switching power supply or the like because of its high resistance, a problem has arisen. When an electrolytic capacitor is used as a power supply smoothing capacitor or coupling capacitor for audio equipment, its resistance to frequency is high, and it cannot absorb internal and external vibrations, causing deterioration of audio signals and distortion of sound quality. It was difficult to prevent.

[Means for Solving the Problems] In order to solve the problems described above, the present invention provides a separator containing fibers composed of animal proteins.

The fiber comprising animal protein as a material constituting the separator of the present invention relates to an artificial protein fiber made from milk (milk) casein. For example, a concentrated aqueous solution of the above protein together with an acrylonitrile monomer and a suitable inorganic salt is used. And a polymerization mixture obtained by polymerizing acrylonitrile by adding a radical polymerization catalyst thereto becomes a fiber raw material, which is obtained as a fiber by wet spinning. The polymerization mixture used as the fiber raw material is composed of three components: a protein, a graft polymer of acrylonitrile on the protein, and a homopolymer of acrylonitrile. Preferably, the protein and acrylonitrile are copolymerized in a ratio of about 3: 7. Such milk casein fiber is called promix and is already commercially available. Also, instead of acrylonitrile, a promix can be obtained by copolymerizing a protein with a vinyl monomer such as acrylate, acrylamide, vinyl acetate or vinylpyridine.

The artificial protein fiber made from animal protein has a thickness of one fiber which is sufficiently thinner than that of Manila hemp, and is obtained as a paper by cutting, beating, paper making operations and the like. Since the papermaking with the protein fiber is dense, the holding amount of the electrolytic solution is improved, and the electric resistance value when the electrolytic solution is impregnated can be reduced. Also, in order to increase the mechanical strength, when mixed with vegetable fibers such as manila hemp and kraft to create a mixed paper, protein fibers are closely entangled in the gaps between the thick fibers of manila hemp and kraft, resulting in extremely narrow gaps. So that
The withstand voltage of the separator as the electrolytic paper is improved. In addition, it was found that the electric resistance value when the electrolytic solution was impregnated was much smaller than that of the case of Manila hemp or Kraft alone. In addition, according to the separator containing milk casein fiber, the separator has a small repulsive force because it is soft against a small bending force due to vibration, and therefore, can prevent deterioration of the audio signal and distortion of sound quality. It is.

The separator according to the present invention is made of milk casein fiber alone, other vegetable fiber, synthetic fiber resin, glass fiber, or a mixture of these fibers.

Next, papermaking consisting only of the milk casein fiber and mixed papermaking consisting of the milk casein fiber and Manila hemp were respectively prepared, and γ-butyrolactone, ethylene glycol, acetonitrile, and N- as the solvent of the electrolytic solution for driving the electrolytic capacitor were used. It was immersed in each solution of N 'dimethylformamide, ethylene glycol monomethyl ether and diethylene glycol monomethyl ether for a long time, but no change such as discoloration or deterioration was observed in both papers. However, alteration was observed in the sodium hydroxide solution.

[Example] Example 1 A separator having a thickness of 60 µm and a density of 0.5 g / cm ³ was prepared as a separator composed of 70% of milk casein fiber and 30% of manila hemp. The air density of this separator is 20.5 sec / 100 cc, and the air density when impregnated with a γ-butyrolactone-based electrolytic solution is
The ESR at 0 ° C. and 1 kHz was 0.67Ω.

Reference example Manila hemp alone separator 60mm thick, density 0.
5 g / cm ³ was prepared. The air tightness of this separator is 1
It was 0.5 sec / 100 cc, and the ESR at 20 ° C. and 1 kHz when impregnated with a γ-butyrolactone-based electrolyte was 0.75Ω.

Next, an aluminum electrolytic capacitor having a rating of 63 V and a capacity of 470 μF was prepared using the separator described above, and the frequency characteristics of the equivalent series resistance (ESR) at 20 ° C. were measured. Table 1 shows the results.

10% when 1kHz vibration is applied to these electrolytic capacitors
When the third harmonic distortion factor when a signal of kHz was input was examined, that of the first embodiment was 4 to 5 dB compared to that of the reference example.
It was found to decrease.

Also, when these electrolytic capacitors were replaced in the coupling circuit of the CD player and auditioned, the distortion of the high-frequency sound quality of the example 1 was greatly reduced compared to the reference example, and The amount of information was greatly increased, resulting in a well-balanced, high-quality sound.

[Effects] As described above, according to the separator of the present invention at least partially containing milk casein fiber, an electrolytic capacitor having a low equivalent series resistance value and a good sound quality can be provided.

Further, the separator according to the present invention, in addition to aluminum electrolytic capacitors, electric double-layer capacitors, solid electrolytic capacitors, other special capacitors, and primary batteries, secondary batteries, other special batteries, such as energy storage elements. It can be applied as a separator.

Claims (1)

(57) [Claims] 1. A separator for an electrolytic capacitor containing at least a part of milk casein fiber.