Separator for electrolytic capacitor and electrolytic capacitor

Abstract

To provide a separator for an electrolytic capacitor and an electrolytic capacitor that can provide high sound quality and suppress defects caused by static electricity.SOLUTION: An electrolytic capacitor 1 includes a capacitor element 2, an exterior case 3, and a sealing body 4. The capacitor element 2 includes an anode, a cathode, and a separator for an electrolytic capacitor. The separator for an electrolytic capacitor is disposed between the anode and the cathode. The separator for an electrolytic capacitor contains ceramic powder and animal fiber powder.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a separator for use in an electrolytic capacitor and to an electrolytic capacitor. [Background technology]

[0002] As an electrolytic capacitor used in audio equipment, an acoustic electrolytic capacitor that can obtain high-quality sound is known (see Patent Document 1). The electrolytic capacitor described in Patent Document 1 uses electrolytic paper coated with glass powder as a separator, which can obtain high-quality sound. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-96761 A Summary of the Invention [Problem to be solved by the invention]

[0004] The electrolytic capacitor has an outer case and a capacitor element housed in the outer case. The capacitor element is produced by winding an anode and a cathode with a separator interposed therebetween. Research by the present inventors has revealed that the capacitor element used in the electrolytic capacitor described in Patent Document 1 may have foreign matter attached thereto due to static electricity generated on the separator during winding. If foreign matter adheres to the separator, this may cause quality defects in the electrolytic capacitor.

[0005] An object of the present invention is to provide a separator for an electrolytic capacitor that provides high sound quality and prevents defects caused by static electricity, and an electrolytic capacitor. [Means for solving the problem]

[0006] As a result of research conducted by the present inventors, it has been found that the quality defects of electrolytic capacitors for audio applications can be suppressed by adopting the following configuration.

[0007] The separator for an electrolytic capacitor disclosed in this specification is a separator for an electrolytic capacitor disposed between an anode and a cathode, and contains ceramic powder and animal fiber powder in electrolytic paper for an electrolytic capacitor.

[0008] It was found that the above-mentioned structure makes it difficult for static electricity to be generated on the separator when the capacitor element is wound up. Because static electricity is unlikely to be generated, foreign matter is unlikely to adhere to the separator. As a result, it was found that as an electrolytic capacitor for audio equipment, it can achieve high sound quality and suppress the occurrence of defects caused by static electricity. In addition, the electrolytic capacitor using a separator to which foreign matter does not easily adhere provides the following effects. When an overvoltage is applied to the electrolytic capacitor, it is less likely to break down. Also, the occurrence of short circuits inside the electrolytic capacitor is suppressed.

[0009] In the above-mentioned configuration, the ceramic powder is preferably glass powder, and the animal fiber powder is preferably silk powder.

[0010] In the above configuration, the content of the ceramic powder is preferably 0.01% by weight to 30.0% by weight, and the content of the animal fiber powder is preferably 0.05% by weight to 6.0% by weight, based on the electrolytic paper for capacitors. When the content is at this level, static electricity is less likely to be generated in the separator than when the electrolytic paper is coated with one type of powder (e.g., conventional glass powder). This results in high sound quality and suppresses the occurrence of defects caused by static electricity.

[0011] In the above configuration, the ceramic powder and the animal fiber powder may be present on a surface portion of the separator for an electrolytic capacitor. For example, the ceramic powder and the animal fiber powder can be present on the surface of the separator for an electrolytic capacitor by a simple process of applying a liquid containing ceramic powder and animal fiber powder to electrolytic paper and drying it. Also, the ceramic powder and the animal fiber powder can be present on the surface of the separator for an electrolytic capacitor by a simple process of immersing electrolytic paper in a liquid containing ceramic powder and animal fiber powder and drying it. With such a simple process, it is possible to provide a separator for an electrolytic capacitor that can achieve the above-mentioned effects.

[0012] The electrolytic capacitor disclosed in this specification includes a capacitor element in which an anode and a cathode are wound with the above-mentioned electrolytic capacitor separator interposed therebetween, an exterior case in which the capacitor element is housed, and a sealing body that seals the opening of the exterior case.

[0013] The electrolytic capacitor uses a separator that is resistant to foreign matter, which allows for high quality sound and prevents defects caused by static electricity. In addition, an electrolytic capacitor using a separator to which foreign matter does not easily adhere can provide the following effects. When an overvoltage is applied to the electrolytic capacitor, it is less likely to break down. Also, the occurrence of short circuits inside the electrolytic capacitor is suppressed. Effect of the Invention

[0014] By using the above separator for electrolytic capacitors in electrolytic capacitors, it is possible to achieve high quality sound and prevent defects caused by static electricity. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a schematic diagram of an example of an electrolytic capacitor according to the present embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the capacitor element shown in FIG. [Diagram 3] FIG. 2 is a schematic diagram of an example of an electron microscope image of a surface portion of a separator. [Figure 4]FIG. 1 shows the experimental relationship between electrostatic potential and silk content. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0017] As shown in FIG. 1, electrolytic capacitor 1 includes a capacitor element 2, an exterior case 3 in which capacitor element 2 is housed, and a sealing member 4 that seals the opening of exterior case 3.

[0018] The outer case 3 is a cylindrical case with a bottom. The outer case 3 is, for example, a metal case. The sealing body 4 is, for example, made of an elastic material such as rubber.

[0019] As shown in Fig. 2, capacitor element 2 has anode 11, cathode 12, and separator 13. Anode 11 and cathode 12 are wound into a cylindrical shape or the like with separator 13 interposed therebetween. An electrolyte solution, or an electrolyte solution and a conductive polymer, are held in separator 13. Anode 11 and cathode 12 are hatched in Fig. 2.

[0020] Lead tabs (not shown) are connected to the anode 11 and the cathode 12, respectively. The anode 11 is connected to a lead terminal 21 via a lead tab. The cathode 12 is connected to a lead terminal 22 via a lead tab. The lead terminals 21 and 22 are led out to the outside through holes 31 and 32, respectively, formed in the sealing body 4, as shown in FIG. 1.

[0021] The anode 11 (see FIG. 2) is, for example, a valve metal having a dielectric oxide film formed on its surface. The valve metal may be, for example, at least one selected from the group consisting of aluminum, tantalum, niobium, and titanium. The oxide film is formed, for example, by roughening the surface of a foil of the valve metal by etching, and then performing anodization (chemical conversion) treatment.

[0022] The cathode 12 is formed, for example, using a valve metal. For example, a valve metal foil whose surface is roughened by etching, or a foil whose surface is roughened and then subjected to chemical conversion treatment is used as the cathode 12. A plain foil that is not subjected to etching may be used as the cathode 12. Furthermore, a coating foil in which a metal thin film containing at least one metal selected from the group consisting of titanium, nickel, titanium carbide, nickel carbide, titanium nitride, nickel nitride, titanium carbonitride, and nickel carbonitride is formed on the surface of the roughened foil or plain foil may be used. A coating foil in which a carbon thin film is formed on the surface of the roughened foil or plain foil may also be used.

[0023] The separator 13 is an electrolytic paper for electrolytic capacitors containing ceramic powder and animal fiber powder. The separator 13 may be, for example, a general electrolytic paper mainly made of cellulose fiber, Manila fiber, Kraft fiber, hemp fiber, cotton fiber, rayon fiber, or Esparto fiber, in which ceramic powder and animal fiber powder are present on the surface and / or inside thereof, or a general electrolytic paper made of a mixture of two or more kinds of fibers, such as cellulose fiber, Manila fiber, Kraft fiber, hemp fiber, cotton fiber, rayon fiber, and Esparto fiber, in which ceramic powder and animal fiber powder are present on the surface and / or inside thereof. The main material of the electrolytic paper is not limited to cellulose fiber, Manila fiber, Kraft fiber, hemp fiber, cotton fiber, rayon fiber, and Esparto fiber, and various materials can be used. The thickness of the separator 13 is not particularly limited, and may be, for example, a general thickness (about 25 to 50 μm) for electrolytic paper for electrolytic capacitors.

[0024] The ceramic powder and the animal fiber powder may be present on the surface portion of the separator 13, may be present inside the separator 13, or may be present both on the surface portion and inside the separator 13. The surface portion of the separator 13 refers to a range from the surface of the separator 13 to a depth of about several μm (e.g., 10 μm) in the thickness direction. The inside of the separator 13 refers to the portion other than the surface portion of the separator 13.

[0025] FIG. 3 is a schematic diagram showing an example of an electron microscope image of the separator 13 observed by an electron microscope. FIG. 3 shows an example in which the fibers 41, which are the main components of the electrolytic paper, the ceramic powder 42, and the animal fiber powder 43 can be confirmed from the electron microscope image. The ceramic powder 42 and the animal fiber powder 43 may be present on the fibers 41, as shown in FIG. 3, or may be present in the entangled fibers 41. The fibers 41, the ceramic powder 42, and the animal fiber powder 43 can be confirmed, for example, by an image observed or photographed by a microscope at a magnification of 100 to 1,000 times. A scanning electron microscope (SEM), a microscope, or the like can be used to observe the separator 13.

[0026] Ceramic powder is ceramic in powder form. Examples of ceramic powder include at least one powder selected from Al2O3, BeO, MgO, BaTiO3, SrTiO3, ZrO2, Si3N4, cBN (cubic boron nitride), SiC, and glass. Among these, glass powder is preferably used. When glass powder is used, an electrolytic capacitor that reliably obtains high sound quality can be provided. Glass is a material that contains silicon dioxide (SiO2) as one of its main components, and may be, for example, aluminosilicate glass (Al2O3-SiO2) or calcium aluminosilicate glass (CaO-Al2O3-SiO2). The glass may be so-called soda-lime glass, the main components of which are silicic acid (SiO2), soda ash (Na2O) and lime (CaO), or so-called lead glass, the main components of which are silicic acid (SiO2), potassium oxide (K2O) and lead oxide (PbO), or borosilicate glass, the main components of which are silicic acid (SiO2), soda ash (Na2O), alumina (Al2O3) and boron oxide (B2O3). Commercially available glass flakes (Glass Flake (registered trademark) manufactured by Nippon Sheet Glass Co., Ltd., etc.) may be used as the glass powder.

[0027] The shape and size of the particles constituting the ceramic powder are not particularly limited. The particles constituting the ceramic powder may be, for example, flat and flaky or approximately spherical. For example, when glass powder is used, the particles constituting the glass powder may be scaly flakes having an average thickness of 0.4 to 5.0 μm and an average particle size of 1 to 900 μm. The average thickness here refers to the average value of the thickness of one flake (particle), and the average particle size refers to the diameter when the area of ​​the broad surface of one flake (particle) is considered to be the area of ​​a circle.

[0028] The animal fiber powder is, for example, animal fiber that has been pulverized by crushing, etc. Examples of animal fibers include silk, wool, cashmere, alpaca, mohair, camel, etc. Among these, silk is easy to obtain and can be easily powdered.

[0029] The shape and size of the particles constituting the animal fiber powder are not particularly limited. The particles constituting the animal fiber powder are often elongated and slender in the fiber direction, for example, because they are formed by crushing long animal fibers. For example, when silk powder is used, it is produced by crushing silk. The particles constituting the silk powder may be elongated and slender with a maximum length in the fiber direction of 1 to 500 μm. The animal fiber powder may contain particle diameters with the same maximum length in the fiber direction, or may contain particles with various maximum lengths in the fiber direction.

[0030] The content of the ceramic powder and animal fiber powder is not particularly limited. For example, when using glass powder as the ceramic powder, the content of the glass powder may be 0.01% by weight or more and 30.0% by weight or less with respect to 100% by weight of the electrolytic paper for electrolytic capacitors. This can reliably achieve high sound quality, which is preferable for an acoustic electrolytic capacitor.

[0031] For example, when silk powder is used as the animal fiber powder, the content of silk powder may be 0.05% by weight or more and 6.0% by weight or less with respect to 100% by weight of the electrolytic paper for electrolytic capacitors. This is believed to suppress the generation of static electricity when winding up the separator 13 compared to the conventional case where only glass powder is used.

[0032] The total content of the ceramic powder and the animal fiber powder is not particularly limited, and is preferably, for example, 0.06% by weight or more and 36.0% by weight or less with respect to 100% by weight of the electrolytic paper for electrolytic capacitors.

[0033] The above-mentioned separator 13 is produced, for example, by the following method.

[0034] Prepare general-purpose electrolytic paper that does not contain ceramic powder or animal fiber powder. Prepare a solution in which ceramic powder and animal fiber powder are dispersed or dissolved in a solvent (e.g., pure water) and adhesive (e.g., polyvinyl alcohol), and apply this solution to the general-purpose electrolytic paper and dry it. Alternatively, general-purpose electrolytic paper may be immersed in a solution in which ceramic powder and animal fiber powder are dispersed or dissolved in a solvent (e.g., pure water) and adhesive (e.g., polyvinyl alcohol), and then removed and dried. As a further alternative, separator 13 may be produced without using the general-purpose electrolytic paper, by mixing the fibers that form the main part of the electrolytic paper with ceramic powder and animal fiber powder at the stage of producing the electrolytic paper. As a result of the above, the ceramic powder and the animal fiber powder are present on the surface and / or inside of the separator.

[0035] Next, an example of a method for producing the electrolytic capacitor 1 will be described. Lead tabs for external extraction electrodes are connected to anode 11 and cathode 12 cut to a predetermined width (see FIG. 2). Anode 11 and cathode 12 to which the lead tabs are connected are wound with separator 13 interposed therebetween to produce capacitor element 2. After winding, chemical conversion treatment may be performed. Alternatively, a conductive polymer layer may be formed by immersing the anode 11 and cathode 12 wound with separator 13 interposed therebetween in a liquid containing a conductive polymer and then drying.

[0036] After impregnating capacitor element 2 with an electrolyte, capacitor element 2 is housed in exterior case 3 (see FIG. 1), and sealing body 4 is fitted into the opening of exterior case 3 to seal the opening. The opening of exterior case 3 is curled. The order of impregnation of the electrolyte and accommodation of capacitor element 2 is not limited to the above. For example, an electrolytic solution may be injected into exterior case 3, and then capacitor element 5 may be housed in exterior case 3. Alternatively, sealing body 4 may be attached to capacitor element 5, and capacitor element 5 may be housed in exterior case 3, after which an electrolytic solution may be injected into exterior case 3 and the opening of exterior case 3 may be sealed with sealing body 4.

[0037] It has been found that when the above-mentioned separator 13 is used, static electricity is less likely to be generated in the separator 13 when the capacitor element 2 is wound in the manufacturing process of the electrolytic capacitor 1. The reason for this is not clear, but it is speculated that when ceramic powder and animal fiber powder are contained, static electricity is less likely to be generated because the chargeability of the animal fiber powder disperses electricity. Since static electricity is less likely to be generated in the separator 13 when the capacitor element 2 is wound, foreign matter is less likely to adhere to the separator 13. By using such a separator 13, it is possible to provide an electrolytic capacitor 1 that has high sound quality and can suppress the occurrence of defects caused by static electricity. Such an electrolytic capacitor 1 is preferable as an electrolytic capacitor for audio.

[0038] Furthermore, the electrolytic capacitor obtained by using the separator 13 has the following effects. When an overvoltage is applied to the electrolytic capacitor 1, the electrolytic capacitor 1 is less likely to break down. Also, the occurrence of a short circuit inside the electrolytic capacitor 1 is suppressed.

[0039] Furthermore, when separator 13 contains glass powder as the ceramic powder and silk powder as the animal fiber powder, high quality sound can be achieved and defects caused by static electricity can be reliably prevented.

[0040] Although there are no particular limitations on the total content of ceramic powder and animal fiber powder in separator 13, it is estimated that when the total content of ceramic powder and animal fiber powder in separator 13 is 0.06% by weight or more and 36.0% by weight or less, static electricity is less likely to occur in separator 13 than when separator 13 contains one type of powder (ceramic powder or animal fiber powder).This allows for high sound quality and suppresses the occurrence of defects caused by static electricity. EXAMPLES

[0041] The present invention will be described in more detail below with reference to examples. However, the following examples do not limit the present invention, and all modifications and variations within the scope of the present invention are included in the technical scope of the present invention.

[0042] General electrolytic paper mainly made of Manila hemp fiber and esparto fiber was prepared, and separators consisting of only the general electrolytic paper (No. 1), separators consisting of the general electrolytic paper coated with one type of powder (glass powder or silk powder) (No. 2, No. 3), and separators consisting of the general electrolytic paper coated with two types of powder (glass powder and silk powder) (No. 4 to No. 7) were prepared. The separator fabrication conditions are shown in Tables 1 and 2 below. For No. 2 to 7, separators were fabricated by applying a coating liquid consisting of glass powder and / or silk powder dispersed in a solvent (pure water) containing polyvinyl alcohol to the general electrolytic paper alone, and then drying it.

[0043] The glass powder and silk powders A to C shown in Tables 1 and 2 are described in detail below. Glass powder: calcium aluminosilicate glass Silk powder A: Silk powder with a maximum length of 8±1μm in the fiber direction Silk powder B: Silk powder with a maximum length of 20 to 25 μm in the fiber direction Silk powder C: A mixture of silk powder with a maximum fiber length of 8±1 μm and silk powder with a maximum fiber length of 20 to 25 μm.

[0044] [Table 1]

[0045] [Table 2]

[0046] <Measurement of electrostatic potential> The separator was sandwiched between two polypropylene sheets and rubbed for 10 seconds, after which the separator was moved to different locations and the electrostatic potential was measured at a total of five locations. The electrostatic potential was measured using a static potential meter "STATIRON (registered trademark) DZ4" manufactured by Shishido Electrostatic Corporation, with the distance between the detection part of the potential meter and the location where the electrostatic potential was measured being 30 mm. Tables 1 and 2 show the electrostatic potentials at the five locations (1 to 5) where the electrostatic potential was measured and their average value (Ave.).

[0047] As can be seen from Table 1, the separators (No. 2 and No. 3) in which one type of powder (glass powder or silk powder) was coated on general electrolytic paper had a higher electrostatic potential than the separator made of general electrolytic paper alone (No. 1). This shows that when a separator coated with one type of powder (glass powder or silk powder) is used, static electricity is more likely to be generated when winding up the capacitor element than when a separator made of general electrolytic paper alone is used.

[0048] On the other hand, from Tables 1 and 2, the separators coated with two types of powder (glass powder and silk powder) (No. 4 to No. 7) had lower electrostatic potential than the separator made of general electrolytic paper alone (No. 1) and the separators coated with one type of powder (glass powder or silk powder) (No. 2, No. 3). This shows that when a separator coated with two types of powder (glass powder and silk powder) is used, static electricity is less likely to be generated during winding compared to when a separator made of general electrolytic paper alone is used and when a separator coated with one type of powder (glass powder or silk powder) is used.

[0049] Figure 4 plots No. 2, which uses one type of powder (glass powder) from Table 1, and No. 4 and No. 5, which use glass powder and silk powder A from Table 2. Note that while the unit of electrostatic potential in Tables 1 and 2 is "kV," the unit of electrostatic potential in Figure 4 is "V."

[0050] In Figure 4, X is the line that passes through No. 2, which uses one type of powder (glass powder), and Y is the line that passes through No. 4 and No. 5, which use two types of powder (glass powder and silk powder A). No. 5, which contains 1.0% silk powder by weight, has a slightly higher electrostatic potential than No. 4, which contains 0.1% silk powder by weight. In general, silk is more easily charged than general electrolytic paper, so it is expected that the electrostatic potential will increase as the silk powder content increases. Based on this, we assumed that the electrostatic potential changes exponentially, and obtained the electrostatic potential transition Z when the silk powder content is 1.0% or more by weight. From Z, it is expected that when the silk powder content is 6.0% or less by weight, the electrostatic potential will be smaller than when one type of powder (glass powder) is used (X).

[0051] Note that Z in Fig. 4 is the transition of electrostatic potential when silk powder A is used, but from No. 4, No. 6, and No. 7 in Table 2, when the contents of silk powders A to C are the same, the electrostatic potential is smaller when silk powder B or silk powder C is used than when silk powder A is used. From this, it is presumed that when silk powder B or silk powder C is used, the silk powder content at which the electrostatic potential is smaller than when one type of powder (glass powder) is used (X) is more than 6.0 wt%.

[0052] In the above experiments, silk powders A to C were used, but the particle size of the silk powder is not limited to the particle size of silk powders A to C.

[0053] In addition, in the above experiment, the content of the glass powder was 0.05% by weight, but the content of the glass powder is not limited to this content, and the content of the silk powder is also not limited to 0.1% by weight and 1.0% by weight in the above experiment. [Explanation of symbols]

[0054] 1. Electrolytic capacitor 2. Capacitor elements 3 Outer case 4 Sealing body 11 Anode 12 Cathode 13 Separator 21, 22 Lead terminal

Claims

1. A separator for an electrolytic capacitor disposed between an anode and a cathode, A separator for an electrolytic capacitor, comprising electrolytic paper for an electrolytic capacitor, the electrolytic paper containing ceramic powder and animal fiber powder.

2. the ceramic powder is a glass powder, The animal fiber powder is silk powder.

2. The separator for an electrolytic capacitor according to claim 1 .

3. The content of the ceramic powder is 0.01% by weight or more and 30.0% by weight or less with respect to the electrolytic paper for electrolytic capacitors, 3. The separator for an electrolytic capacitor according to claim 1, wherein the content of the animal fiber powder is 0.05% by weight or more and 6.0% by weight or less based on the weight of the electrolytic paper for an electrolytic capacitor.

4. 3. The separator for an electrolytic capacitor according to claim 1, wherein the ceramic powder and the animal fiber powder are present on a surface portion of the electrolytic paper for an electrolytic capacitor.

5. a capacitor element in which an anode and a cathode are wound with the separator for an electrolytic capacitor according to claim 1 or 2 interposed therebetween; an exterior case in which the capacitor element is housed; a sealing body that seals the opening of the exterior case; An electrolytic capacitor comprising:

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