JP2965335B2 - Electrolytic capacitor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor having a unique separator, and more particularly, to a chemically and thermally stable material capable of realizing a long life of the capacitor. The present invention relates to an electrolytic capacitor provided with a separator capable of lowering the impedance of a capacitor by improving the tensile strength by a predetermined process and reducing the density.

2. Description of the Related Art Electrolytic capacitors are small, large-capacity, inexpensive, and have excellent characteristics such as smoothing of rectified output, and are one of important components of various electric and electronic devices. In general, electrolytic capacitors are classified into an electrolytic solution type and a solid type. A conductive oxide or organic substance such as polypyrrole is interposed as a solid electrolyte.

Regardless of the type of electrolyte or solid electrolytic capacitor, a separator made of a generally porous material is sandwiched between the anode foil and the current collector cathode foil to immerse the electrolyte or solid electrolyte. Means are often used to ensure retention and to separate the anode and cathode foils in the product.

Cellulose-based fibers such as manila paper and kraft paper are widely used as separators for electrolytic capacitors.However, in the case of conventional electrolytic capacitors using separators, the chemical reaction between the electrolytic solution and the separator will occur if the capacitor is used for a long time. And the like, and there is a disadvantage that stable characteristics cannot be sufficiently maintained. That is, in a conventional electrolytic capacitor using a separator, for example, when used under severe conditions for a long period of time, the capacitance (Cop.), Dielectric loss tangent (tan δ), and impedance (Imp.) The decline is remarkably recognized, and it has been desired to avoid or alleviate these degradations.

The reason why the stable characteristics cannot be sufficiently maintained may be that some inconvenient chemical reaction occurs at the time of the characteristic deterioration, resulting in deterioration of the separator, but a possible chemical reaction at this time is cellulose. An esterification reaction between a hydroxyl group of the system fiber and a carboxylic acid, which is a component of the electrolytic solution of the electrolytic capacitor, can be mentioned. It is considered that this esterification reaction causes consumption of ions effective for maintaining the characteristics, and particularly deteriorates the characteristics of the capacitor.

[Problems to be solved by the invention] The present invention is to improve the separator of the electrolytic capacitor,
A separator made of a chemically and thermally stable material that can extend the life of the capacitor, improves tensile strength by a predetermined process, enables low density, and provides a low impedance capacitor It is another object of the present invention to provide an electrolytic capacitor including the same.

[Means for Solving the Problems] According to the present invention, in an electrolytic capacitor having a separator interposed between an anode foil and a cathode foil, the separator has a glass fiber, a glass transition temperature of 130 ° C. or higher, and a melting point. Alternatively, there is provided an electrolytic capacitor characterized by being a separator for an electrolytic capacitor comprising a nonwoven fabric mixed with a heat-resistant organic polymer fiber having a fusion property at a temperature equal to or higher than the glass transition temperature.

It is preferable that the heat-resistant organic polymer fiber be an aromatic polyamide (aramid) or polyphenylene sulfide (PPS).

The thickness of the glass fiber yarn is preferably 1 to 10 μm, and fiber yarns having different thicknesses can be used by appropriately mixing. The thickness of the heat-resistant organic polymer fiber yarn is preferably
It is 0.5-5 μm, and fiber yarns having different thicknesses can be appropriately mixed and used. When mixing glass fiber yarn and heat-resistant organic polymer fiber yarn, these ratios are
4: 6 to 8:12 is preferable.

The heat-resistant organic polymer fibers constituting the mixed nonwoven fabric are treated at a temperature equal to or higher than the melting point or the glass transition temperature, and between the glass fibers and the heat-resistant organic polymer fibers and between the heat-resistant organic polymer fibers. It is preferable that they are fused or adhered at the intersection.

Density of混抄nonwoven is 0.05 to 50 g / cm ^3, a thickness of 10
It is preferable that the thickness be 200 μm.

[Operation] As described above, cellulosic fibers such as manila paper and kraft paper are widely used as separators for electrolytic capacitors. Japanese Patent Application Laid-Open No.
-12262, JP-A-52-366, JP-A-63-207114, JP-A-61-27328, JP-A-61-38926 and JP-A-62
There is a technique described in 162830.

However, such a conventional electrolytic capacitor using a separator has a drawback that if the capacitor is used for a long period of time, a chemical reaction between the electrolytic solution and the separator occurs, and stable characteristics cannot be sufficiently maintained. The hydroxyl group of the cellulosic fiber may contribute to the chemical reaction, but the present invention has been completed as a result of a study from the viewpoint of suppressing the chemical reactivity of the conventional separator.

From the viewpoint of suppressing the chemical reaction, there is also a means of using a glass fiber having completely different properties from the cellulosic fiber alone for the separator of the electrolytic capacitor, but since the glass fiber alone has almost no entanglement between the fibers, Heat treatment (heating and pressurizing treatment) of a paper made by mixing PPS or aramid fiber with glass fiber causes the fibers to be fused (or bonded) to improve the strength of the nonwoven fabric.

The glass, aramid, and polyphenylene sulfide used in the present invention are chemically and thermally stable, and can extend the life of an electrolytic capacitor. In addition, since the tensile strength of the nonwoven fabric can be increased by fusing at the inter-fiber intersecting portion, the density of the separator can be reduced, and thereby the impedance of the capacitor can be reduced.

[Effects of the Invention] According to the present invention, a separator of an electrolytic capacitor is improved to be made of a chemically and thermally stable material that can extend the life of the capacitor, and the tensile strength is improved by a predetermined treatment. Thus, an electrolytic capacitor provided with a separator capable of lowering the density and realizing a lower impedance of the capacitor is provided.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited only to the following examples.

Production of Electrolytic Capacitors The electrolytic solution and separator shown in Table 1 were used, and these were combined in a conventional manner to a size of 10φ × 20, rated voltage of 10
V, an electrolytic capacitor having a rated capacity of 1000 μF was produced.
The symbols in the table indicate the following electrolytes and separators.

Electrolyte A: γ-butyrolactone / tetraethylammonate maleate electrolyte B: γ-butyrolactone / tetramethylammonium phthalate electrolyte C: Ethylene glycol / ammonium adipate electrolyte Separator MER: Manila / Espart ( Weight ratio 60:40) Mixed paper G1: Glass fiber / PPS fiber mixed nonwoven fabric G2: Glass fiber / aramid fiber mixed nonwoven fabric G3: Glass fiber / PPS fiber mixed nonwoven fabric G1 is 9 μm and 6 μm glass fiber yarn (1: 1
(Weight ratio) and 3 μm PPS fiber yarn (glass: PPS
G2 is composed of 9 μm and 3 μm glass fiber yarns (4: 6 weight ratio) and 2 μm aramid fiber yarns (glass: aramid = 7: 3 weight ratio), and G3 is 6 μm glass. Consists of fiber yarn and 2 μm PPS fiber yarn (glass: PPS
= 4: 6 weight ratio).

In the table, the unit of density is g / cm ³ , and the unit of thickness is μm
It is.

Table 2 shows the measured values of the capacitance, dielectric loss tangent, and impedance as initial characteristics and characteristics after 5,000 hours of use at 105 ° C. In the table, Cap. Is the capacitance at 120 Hz (μ
F), ΔCap is a capacitance change rate (%), and tan
δ is the tangent of the loss angle at 120 Hz, IMP. is 100 KHz
(Ω).

From the results, the electrolytic capacitor according to the present invention achieves a longer service life of the capacitor,
It can be seen that low density and low impedance of the capacitor are realized.

Continuation of the front page (72) Inventor Akihiro Shimada 1-167, Higashi-Ome, Ome-shi, Tokyo 1 Inside Nippon Chemi-Con Corporation (72) Inventor Takato Ito 1-167, Higashi-Ome, Ome-shi, Tokyo 1 Nippon Chemi-Con Corporation (56) References JP-A-62-162830 (JP, A) JP-A-2-155217 (JP, A) JP-A-2-213113 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) H01G 9/02

Claims (4)

(57) [Claims] 1. An electrolytic capacitor having a separator interposed between an anode foil and a cathode foil, wherein the separator has a glass fiber having a glass transition temperature of 130 ° C. or higher and a melting point or a temperature higher than the glass transition temperature. An electrolytic capacitor characterized by being a separator for an electrolytic capacitor made of a nonwoven fabric mixed with a heat-resistant organic polymer fiber having adhesiveness. 2. The heat-resistant organic polymer fiber is made of aromatic polyamide (aramid) or polyphenylene sulfide (PP).
2. The electrolytic capacitor according to claim 1, which is S). 3. The heat-resistant organic polymer fibers constituting the mixed nonwoven fabric are treated at a temperature not lower than the melting point or the glass transition temperature, so that the heat-resistant organic polymer fibers are interposed between the glass fibers and the heat-resistant organic polymer fibers. The electrolytic capacitor according to claim 1, wherein the electrolytic capacitor is fused or adhered at the inter-fiber intersecting portion. 4. The electrolytic capacitor according to claim 1, wherein the mixed nonwoven fabric has a density of 0.05 to 50 g / cm ³ and a thickness of 10 to 200 μm.