JP2013207250A - Separator for aluminum electrolytic capacitor, and aluminum electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum electrolytic capacitor which is remarkably improved in capacitor's capacitance-reduction rate, life, short resistance, heat resistance and impedance property, especially equivalent series resistance by use of a separator having excellent heat resistance, good lyophilic property with both of two electrolytes of γ-butyrolactone and ethylene glycol and therefore a high liquid-holding rate, and both high compactness and low density, which are antithetical to each other.SOLUTION: The aluminum electrolytic capacitor has a separator interposed between positive and negative electrode foils. The separator includes a solvent spinning cellulose fiber having an aspect ratio of 300-800, and a polyester fiber, such as polyester, polyethylene terephthalate, polyethylenenaphthalate, or polyarylate fiber, having a fiber diameter of 18 μm or smaller; the fibers are blended by 20-50 wt.%. The solvent spinning cellulose fiber having an aspect ratio of 300-800 are beaten to CSF 200 ml or less.

Description

  The present invention relates to a separator for an aluminum electrolytic capacitor and an aluminum electrolytic capacitor.

  An aluminum electrolytic capacitor is formed by interposing a separator between an anode foil and a cathode foil and winding it to form a capacitor element, and using ethylene glycol (hereinafter abbreviated as EG) or γ-butyrolactone (hereinafter abbreviated as GBL). It is manufactured by immersing it in an electrolytic solution in which an organic acid salt such as boric acid, ammonium adipate, or carboxylic acid amidine salt is dissolved and sealing it.

  The separator used for the conventional aluminum electrolytic capacitor was made from natural fibers such as wood kraft pulp, manila hemp pulp, and esparto pulp. In order to improve the density of the separator, it is necessary to beat these fibers. However, it is known that the equivalent series resistance (hereinafter abbreviated as ESR) is deteriorated by beating natural fibers. For this reason, a method of using beaten solvent-spun cellulose fibers has been proposed in order to improve the denseness and improve the ESR (Patent Document 1).

  In addition, it has a paper strength composed of solvent-spun cellulose fibers, polyvinyl alcohol fibers (hereinafter abbreviated as PVA fibers), and polyvinyl alcohol binder fibers (hereinafter abbreviated as PVA binder fibers) without any difficulty in handling. On the other hand, a separator having low density and low impedance characteristics has also been proposed (Patent Document 2).

Moreover, what carried out the calendar process as a structure containing an aramid fiber and a solvent spinning cellulose fiber as a separator for solid electrolytic capacitors excellent in reflow heat resistance, low ESR and high withstand voltage has been proposed (Patent Document 3). ).
Furthermore, Patent Document 4 proposes a capacitor separator which is made of a wet nonwoven fabric containing a polymer having a melting point or a thermal decomposition temperature of 250 ° C. or more and is excellent in heat resistance, electrolytic solution retention and internal short circuit prevention. ing.

Japanese Patent No. 3466206 Japanese Patent No. 3324803 Japanese Patent No. 4109697 JP 2007-059789 A JP 2003-168629 A JP 2003-133181 A

  In order to improve the electrolyte retention rate of the separator, a method of increasing the porosity of the separator or increasing the specific surface area of the separator is known. This is because if the separator has a high electrolytic solution retention rate, a large amount of electrolytic solution can be retained in the aluminum electrolytic capacitor, leading to a longer life of the capacitor.

  However, even when a separator with a high electrolyte retention rate is used, if the lyophilicity between the separator and the electrolyte is low, the electrolyte is localized in the aluminum electrolytic capacitor during long-term use, and the electrolyte above the capacitor It moves down. As a result, the capacity reduction rate of the aluminum electrolytic capacitor is increased, and the life of the aluminum electrolytic capacitor is shortened.

  Further, in order to improve the strength of the separator, a method is known in which chemical fibers are fixed with binder fibers such as PVA, or cellulose fibers are beaten and fibrillated, or fibrillated chemical fibers are used.

  However, when a PVA binder fiber is used for strength enhancement, even if the strength is enhanced, a part of the fiber dissolves to form a film, so that ESR deteriorates. In the configuration of Patent Document 2, even if the impedance characteristics are improved at a low density, there remains a problem that a part of the PVA binder fiber dissolves to form a film and deteriorates ESR.

  In addition, when natural cellulose fiber is used, it is necessary to beat in order to improve the denseness, but when natural cellulose fiber is beaten, the density increases and ESR is secondarily deteriorated. Even when natural cellulose fibers were beaten, it was not possible to achieve both low density and denseness.

  In order to improve the deterioration of ESR at the time of beating in natural cellulose fiber, in Patent Document 1, a separator using solvent-spun cellulose fiber is used. However, solvent-spun rayon has a high EG electrolyte solution retention ratio and is a lyophilic solution. However, since it does not have good lyophilicity with respect to GBL, there is a problem that the electrolytic solution holding power is low and the capacity reduction rate of the aluminum electrolytic capacitor is increased.

  In the separator using the solvent-spun rayon described in Patent Literature 3, the strength of the separator is improved without impairing ESR by impregnating with a paper strength enhancer. Similarly, solvent-spun rayon has a high EG electrolyte solution retention ratio and exhibits lyophilicity, but does not exhibit good lyophilicity with respect to GBL. There was a problem that the capacity reduction rate was increased.

  Patent Document 4 describes fibrillated aramid fibers and fibrillated solvent-spun cellulose fibers. Para-aramid fibers described in Examples are dissolved in sulfuric acid and then coagulated. In order to manufacture, it is unavoidable to contain a large amount of sulfate ions. For this reason, sulfate ions have adversely affected the characteristics of aluminum electrolytic capacitors.

  Moreover, since the fibrid in Patent Document 4 forms a film between fibers by heat fusion, there is a problem that ESR is deteriorated. In addition, in order to ensure the strength that can withstand use, the configuration of Patent Document 4 must be subjected to a calendering process, a heat treatment, or a heat calendering process, and these processes increase the density. As a result, the problem that ESR rises remains.

  The separators described in Patent Document 5 and Patent Document 6 use para-type wholly aromatic polyamide and wholly aromatic polyester fiber which are easily fibrillated. Moreover, the structure of the separator for capacitors which contained natural cellulose fiber, solvent-spun cellulose fiber, etc. in an appropriate amount is disclosed. However, it is difficult to use these as separators for aluminum electrolytic capacitors. The fibrillated liquid crystalline wholly aromatic polyamide fiber or liquid crystalline wholly aromatic polyester fiber is easy to get entangled when the generated fibrils form the fiber web. There remains a problem that it is difficult to obtain a good separator.

  If the texture becomes uneven, the fibers are localized to form through holes, so that the short-circuit defect rate in the capacitor manufacturing process increases. Moreover, also in the structure of patent document 5 and patent document 6, in order to ensure the intensity | strength which can be endured use similarly to patent document 4, the calender process, the heat processing, or the heat calender process is performed. Since the density is increased by these treatments, there remains a problem that as a result, the ESR increases.

  Moreover, about the fiber used by the structure of patent document 4, 5 and 6, when the liquid retention of GBL and EG was evaluated as shown in Table 1, the fibrillated wholly aromatic polyamide fiber was made of GBL and EG. In all cases, the lyophilicity was low. Moreover, although the fibrillated wholly aromatic polyester fiber has lyophilicity with GBL, the EG was low in lyophilicity.

Table 1 is a table | surface which shows the evaluation result of GBL and EG liquid retention of each fiber.

  In the configurations of Patent Documents 4, 5 and 6, the lyophilic cellulose fiber content of EG is 15% or less, so the lyophilicity of the separator with respect to EG remains low. That is, because of its low density, even if an electrolyte is present in the gap, the ability to retain it is low, and the configurations of Patent Documents 3 and 4 having a cellulose fiber content of 15% or less are used in aluminum electrolytic capacitors. In either GBL or EG, the electrolyte solution is localized and the capacity reduction rate is increased.

  In particular, in a wound aluminum electrolytic capacitor, the electrolyte solution is localized, so that the electrolyte solution on the top of the capacitor moves downward during long-term use, increasing the capacity reduction rate of the aluminum electrolytic capacitor and increasing the service life. Will be shorter.

  In Patent Documents 5 and 6, the electrolyte retention rate of the separator is defined, but the method for measuring the electrolyte retention rate of the separator is a measurement value immediately after impregnating the electrolyte and draining the excess electrolyte. For this reason, the effect of extending the life of aluminum electrolytic capacitors has not been correctly evaluated. Even if the liquid retention rate close to the maximum value immediately after liquid removal is increased, the life of the aluminum electrolytic capacitor is not evaluated.

  It is possible to accurately evaluate the life of an aluminum electrolytic capacitor by leaving the aluminum electrolytic capacitor in a high temperature atmosphere without applying a voltage and measuring the change in capacitance after a certain period of time. The capacity reduction rate in this embodiment is measured after 2000 hours have passed without applying a voltage in an atmosphere of 85 ° C. Neither patent document discloses a configuration in which the lyophilicity of both the GBL and EG electrolytes is improved and the capacity reduction rate is reduced. Since it is not possible to improve localization and reduce the capacity reduction rate, it is not possible to extend the life of aluminum electrolytic capacitors.

  The present invention has been made in view of such problems, and provides a separator for an aluminum electrolytic capacitor that exhibits good electrolytic solution retention, has a high porosity, and is excellent in heat resistance. An object of the present invention is to provide an aluminum electrolytic capacitor that is excellent, has a reduced capacity reduction rate, has a long life, and has an improved ESR.

For example, the following configuration is provided as one means for achieving the object.
That is, a separator for an aluminum electrolytic capacitor interposed between an anode foil and a cathode foil of an aluminum electrolytic capacitor, which is characterized by comprising at least a solvent-spun cellulose and a chemical fiber.
For example, the chemical fiber has a fiber diameter of 18 μm or less. For example, the chemical fiber is a straight fiber that is not fibrillated.

Further, for example, the chemical fiber is at least one selected from polyester fibers such as polyester, polyethylene terephthalate, polyethylene naphthalate, polyarylate fiber, and the like.
For example, the solvent-spun cellulose fiber is characterized by beating to CSF 200 ml or less.
Or it is set as the aluminum electrolytic capacitor characterized by using one of the separators for aluminum electrolytic capacitors described above.

  According to the present invention, a separator for an aluminum electrolytic capacitor that exhibits good electrolytic solution retention, a large number of voids, and excellent heat resistance, excellent short circuit resistance, reduced capacity reduction rate, long life, and An aluminum electrolytic capacitor with greatly improved ESR can be provided.

  Hereinafter, an aluminum electrolytic capacitor separator and an aluminum electrolytic capacitor using the separator according to an embodiment of the present invention will be described in detail. However, the present invention is not limited to the configurations of the embodiments and various examples.

The manufacturing process of the separator of this embodiment and the manufacturing process of the aluminum electrolytic capacitor using the separator will be described.
[Production process of aluminum electrolytic capacitors]

(1) Production of separator There is no restriction on the paper machine for producing the separator. For example, each of the paper machine, for example, a circular paper machine, a long paper machine, a short paper machine, an inclined short paper machine, a former, Alternatively, a plurality of combinations are possible.

As specific constituent fibers of the separator, for example, the following fibers can be used.
Beating solvent-spun cellulose fibers having an aspect ratio of 300 to 800 to CSF 200 ml or less, and blending 20 to 50% of polyester fibers such as polyester, polyethylene terephthalate, polyethylene naphthalate, polyarylate fibers having a fiber diameter of 18 μm or less. Paper strength enhancers such as semi-synthetic polymers and synthetic polymers that do not form a film upon drying, such as carboxymethyl cellulose and polyacrylamide, are used.

  With this configuration, both the density and low density of the separator are compatible, so that the lyophilicity with GBL and EG is improved, the electrolyte can be retained for a long period of time, and the capacity reduction rate of the aluminum electrolytic capacitor is small. , Long life, short resistance, and ESR characteristics can be improved.

  The solvent-spun cellulose fibers used in this embodiment are those having an aspect ratio of 300 to 800. When the aspect ratio is less than 300, when the CSF is beaten to 200 ml or less, it cannot have strength enough to withstand use. In addition, fine fibrils are less likely to be generated by beating, and the separator cannot be given denseness. If the aspect ratio is greater than 800, the fibers tend to be entangled by beating and the thickness of the separator becomes non-uniform. In addition, if there are many entangled fibers, the fibers in the separator are likely to be localized, resulting in an increase in the number of through holes in the separator, and a short circuit failure is likely to occur in the capacitor manufacturing process.

The solvent-spun cellulose fiber used is beaten to a CSF of 200 ml or less. When the CSF is larger than 200 ml, the generated fine fibrils are reduced and the denseness of the separator is lowered. Moreover, since generation | occurrence | production of a fine fibril decreases, the physical entanglement between fibers reduces and the tensile strength of a separator falls.
Further, the blending ratio of the solvent-spun cellulose fiber is 50% or more. When it is less than 50%, the strength of the separator, the retention rate of the EG electrolyte solution, and the density of the separator are lowered, and the short-circuit defect rate and the capacity reduction rate of the electrolytic capacitor using EG as the electrolyte solution are reduced. When the blending ratio is larger than 80%, the lyophilicity with GBL is lowered, and the capacity decreasing rate is reduced in an electrolytic capacitor using GBL as an electrolytic solution.

  Polyester, polyethylene terephthalate, polyethylene naphthalate, and polyarylate fibers are used as the polyester fiber, but it is a chemical fiber with a heat resistance of 200 ° C. or higher, high lyophilicity with γ-butyrolactone, and aluminum. It is not limited to these as long as it does not contain a substance that adversely affects the electrolytic capacitor.

  If the fiber diameter of the chemical fiber is 18 μm or less, the influence on ESR is slight. However, if the fiber diameter is larger than 18 μm, large fibers prevent the passage of ions, so that ESR deteriorates. As the fiber diameter is smaller, the ESR is improved because the passage of ions is not hindered. However, if the fiber diameter is too small, the denseness is improved, leading to an increase in density, and eventually accompanied by a worsening of the ESR. For this reason, the fiber diameter is preferably 18 μm or less. The fiber diameter of the chemical fiber is preferably not less than fibrils generated by beating the solvent cellulose fiber, specifically 0.1 μm or more.

The thickness of the separator is preferably 10 to 70 μm and the density is preferably 0.10 to 0.40 g / cm ³ . When the thickness is reduced and the density is reduced, the entanglement between the fibers is reduced, so that the strength of the separator is inevitably lowered even if the strength can withstand use. Semi-synthetic that does not form a film when dried, such as carboxymethylcellulose and polyacrylamide, in structures with a basis weight of less than 12 g / m ^{2 in} order to improve handling at the time of element winding and compensate for strength without deteriorating ESR Use paper strength enhancers such as polymers and synthetic polymers.

(2) Element winding A separator manufactured between a tabbed anode aluminum foil and a cathode aluminum foil is interposed and wound with an element winding machine to create a capacitor element.

(3) Impregnation with liquid electrolyte Next, the capacitor element is immersed in, for example, GBL or EG liquid to form an electrolyte layer on the separator.

(4) Sealing in the case After impregnation with the electrolyte, it is put in the case, the opening is sealed with a sealing member, and aging is performed to produce an aluminum electrolytic capacitor having a withstand voltage of 50 WV and a capacity of 220 μF, for example.

Next, various specific examples, comparative examples, and conventional examples of the aluminum electrolytic capacitor according to the present invention will be described.
[Example 1]
Paper making is performed with a circular multi-layer combination machine using 50% by weight of a raw material obtained by beating beating solvent-spun cellulose fiber having an aspect ratio of 500 to 70 ml of CSF and 50% by weight of polyethylene naphthalate fiber having a fiber diameter of 10 μm. Thereafter, a diluted solution of polyacrylamide resin was impregnated and applied with a direct roll coater and dried with a cylinder dryer to obtain a circular double paper having a thickness of 40.1 μm and a density of 0.201 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Example 2]
Paper making is performed with a circular multi-layer combination machine using a mixed raw material of 70% by weight of a raw material obtained by beating beating solvent-spun cellulose fiber having an aspect ratio of 800 to 45 ml of CSF and 30% by weight of polyarylate fiber having a fiber diameter of 10 μm. Thereafter, a diluted solution of carboxymethyl cellulose resin was impregnated and applied with a direct roll coater and dried with a cylinder dryer to obtain a circular triplex paper having a thickness of 41.0 μm and a density of 0.290 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

Example 3
Paper is made with a circular multi-layer combination machine using 60% by weight of a raw material obtained by beating beating solvent-spun cellulose fibers having an aspect ratio of 400 to 30 ml of CSF and 40% by weight of a polyester fiber having a fiber diameter of 14 μm. A circular triplex paper having a size of 3 μm and a density of 0.249 g / cm ³ was obtained. Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

Example 4
Paper making is carried out by a circular multi-layer combination machine using a mixed raw material of 50% by weight of a raw material obtained by beating beating solvent-spun cellulose fibers having an aspect ratio of 300 to 40 ml of CSF and 50% by weight of polyethylene naphthalate fibers having a fiber diameter of 10 μm. Thereafter, a dilute solution of polyethyleneimine resin was impregnated and applied with a direct roll coater, and dried with a cylinder dryer to obtain a circular double paper having a thickness of 60.8 μm and a density of 0.190 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

Example 5
Paper making is carried out with a circular multi-layer combination machine using a mixed raw material of 70% by weight of a raw material obtained by beating a solvent-spun cellulose fiber having an aspect ratio of 400 to 50 ml of CSF and 30% by weight of polyethylene naphthalate having a fiber diameter of 10 μm. Thereafter, a diluted solution of polyacrylamide resin was impregnated and applied with a direct roll coater, and dried with a cylinder dryer to obtain a circular triplex paper having a thickness of 58.6 μm and a density of 0.159 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

Example 6
Paper is made with a circular multi-layer combination machine using 70% by weight of a raw material obtained by beating beating solvent-spun cellulose fibers having an aspect ratio of 300 to 30 ml of CSF and 30% by weight of polyarylate fibers having a fiber diameter of 12 μm. A circular triplex paper having a diameter of 0.2 μm and a density of 0.268 g / cm ³ was obtained. Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

Example 7
Paper making is carried out with a circular multi-layer combination machine using a mixed raw material of 70% by weight of a raw material obtained by beating a solvent-spun cellulose fiber having an aspect ratio of 400 to 50 ml of CSF and 30% by weight of polyethylene naphthalate having a fiber diameter of 10 μm. Thereafter, a diluted solution of polyacrylamide resin was impregnated and applied with a direct roll coater and dried with a cylinder dryer to obtain a circular triplex paper having a thickness of 50.1 μm and a density of 0.233 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

Example 8
Paper making is performed with a circular multi-layer combination machine using a mixed raw material of 70% by weight of a raw material obtained by beating a solvent-spun cellulose fiber having an aspect ratio of 300 to 10 ml of CSF and 30% by weight of a polyethylene terephthalate fiber having a fiber diameter of 12 μm. Thereafter, a diluted solution of polyacrylamide resin was impregnated and applied with a direct roll coater, and dried with a cylinder dryer to obtain circular double paper having a thickness of 70.8 μm and a density of 0.105 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

Example 9
Paper making is carried out with a circular multi-layer combination machine using 70% by weight of a raw material obtained by beating solvent-spun cellulose fibers having an aspect ratio of 300 to 120 ml of CSF and 30% by weight of a polyarylate fiber having a fiber diameter of 0.1 μm. Thereafter, a diluted solution of carboxymethyl cellulose resin was impregnated and applied with a direct roll coater and dried with a cylinder dryer to obtain a circular double paper having a thickness of 33.0 μm and a density of 0.229 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

Example 10
Paper making is carried out with a long net paper machine using 80% by weight of a raw material obtained by beating beating solvent-spun cellulose fibers having an aspect ratio of 700 to 5 ml of CSF and 20% by weight of polyethylene naphthalate having a fiber diameter of 5 μm. Thereafter, a dilute solution of polyacrylamide resin was impregnated and applied with a direct roll coater, and dried with a cylinder dryer to obtain a single sheet of long net with a thickness of 15.2 μm and a density of 0.412 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Comparative Example 1]
Using a mixed raw material of 90% by weight of a raw material obtained by beating solvent-spun cellulose fiber up to 450 ml of CSF and 10% by weight of PVA binder fiber, paper was made with a circular net paper machine, and the thickness was 40.5 μm and the density was 0.227 g / cm. I got ³ circle nets. Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Comparative Example 2]
Using a mixed raw material of 58% by weight of raw material obtained by beating solvent-spun cellulose fiber up to 300 ml of CSF, 32% by weight of PVA fiber, and 10% by weight of PVA binder fiber, paper was made with a circular net paper machine, and the thickness was 40.7 μm. A circular mesh single paper having a density of 0.202 g / cm ³ was obtained. Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.
In addition, about the comparative example 1 and the comparative example 2, since the polyester-type fiber is not used, description of the fiber structure is abbreviate | omitted in Table 2.

[Comparative Example 3]
Paper making is carried out by a circular multilayer combination machine using a mixed raw material of 70% by weight of a raw material obtained by beating beating solvent-spun cellulose fibers having an aspect ratio of 800 to CSF of 45 ml and 30% by weight of polyarylate fibers having a fiber diameter of 20 μm. Thereafter, a diluted solution of carboxymethyl cellulose resin was impregnated and applied with a direct roll coater and dried with a cylinder dryer to obtain a circular triple paper having a thickness of 42.1 μm and a density of 0.298 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Comparative Example 4]
Paper is made with a circular multi-layer combination machine using 60% by weight of a raw material obtained by beating beaten solvent-spun cellulose fibers having an aspect ratio of 900 to 30 ml of CSF and 40% by weight of polyester fibers having a fiber diameter of 14 μm. A circular triplex paper having a thickness of 7 μm and a density of 0.252 g / cm ³ was obtained. Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Comparative Example 5]
Paper was made with a circular multi-layer combination machine using 60% by weight of a raw material obtained by beating beating solvent-spun cellulose fibers having an aspect ratio of 200 to CSF of 30 ml and 40% by weight of a polyester fiber having a fiber diameter of 14 μm. A circular triplex paper having a size of 8 μm and a density of 0.254 g / cm ³ was obtained. Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Comparative Example 6]
Using a mixed raw material of 5% by weight of a raw material obtained by beating solvent-spun cellulose fiber to CSF 10 ml, 20% by weight of polyethylene terephthalate fiber, 25% by weight of core-sheath polyester fiber, and 50% by weight of fibrillated wholly aromatic polyamide fiber, Paper is made with a circular paper machine. Next, heat treatment was performed at 200 ° C. to obtain a circular net single paper having a thickness of 58.7 μm and a density of 0.264 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.
In addition, since there are many constituent fiber types, the description of the fiber configuration is omitted in Table 2.

[Comparative Example 7]
Paper is made with a circular multi-layer combination machine using a mixed raw material of 70% by weight of a bead of solvent-spun cellulose fiber having an aspect ratio of 300 and CSF 220 ml and 30% by weight of a polyarylate fiber having a fiber diameter of 12 μm. A circular triplex paper having a thickness of 0.8 μm and a density of 0.262 g / cm ³ was obtained. Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Comparative Example 8]
Using a mixed raw material of 10% by weight of a raw material obtained by beating solvent-spun cellulose fiber to 10 ml of CSF, 5% by weight of fibrillated aramid fiber, 50% by weight of polyacrylonitrile-based carbon fiber, and 35% by weight of acrylic fiber, Make paper with a machine. Next, calendar treatment was performed to obtain a circular mesh single paper having a thickness of 49.9 μm and a density of 0.262 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.
In addition, since there are many constituent fiber types, the description of the fiber configuration is omitted in Table 2.

[Comparative Example 9]
Paper making is performed with a circular multi-layer combination machine using 40% by weight of a raw material obtained by beating beating solvent-spun cellulose fibers having an aspect ratio of 400 to 50 ml of CSF and 60% by weight of polyethylene naphthalate having a fiber diameter of 10 μm. Thereafter, a diluted solution of polyacrylamide resin was impregnated and applied with a direct roll coater, and dried with a cylinder dryer to obtain a circular triplex paper having a thickness of 52.0 μm and a density of 0.239 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Comparative Example 10]
Paper making is performed with a circular multi-layer combination machine using a mixed raw material of 90% by weight of a raw material obtained by beating a solvent-spun cellulose fiber having an aspect ratio of 400 to 50 ml of CSF and 10% by weight of polyethylene naphthalate having a fiber diameter of 10 μm. Thereafter, a diluted solution of polyacrylamide resin was impregnated and applied with a direct roll coater and dried with a cylinder dryer to obtain a circular triplex paper having a thickness of 48.9 μm and a density of 0.240 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Comparative Example 11]
Paper making is carried out with a circular multi-layer combination machine using a mixed raw material of 40% by weight of a raw material obtained by beating beating solvent-spun cellulose fibers having an aspect ratio of 300 to 10 ml of CSF and 60% by weight of polyethylene terephthalate fibers having a fiber diameter of 12 μm. Thereafter, a diluted solution of polyacrylamide resin was impregnated and applied with a direct roll coater and dried with a cylinder dryer to obtain circular double paper having a thickness of 70.3 μm and a density of 0.109 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Comparative Example 12]
Paper is made with a circular multilayer combination machine using 90% by weight of a raw material obtained by beating beating solvent-spun cellulose fibers having an aspect ratio of 300 to 120 ml of CSF and 10% by weight of polyarylate fibers having a fiber diameter of 0.1 μm. Thereafter, a diluted solution of carboxymethyl cellulose resin was impregnated and applied with a direct roll coater and dried with a cylinder dryer to obtain a circular mesh double paper having a thickness of 32.7 μm and a density of 0.238 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Comparative Example 13]
Using a raw material obtained by beating a solvent-spun cellulose fiber having an aspect ratio of 700 to a CSF of 5 ml, paper is made with a long net paper machine. Thereafter, a dilute solution of polyacrylamide resin was impregnated and applied with a direct roll coater and dried with a cylinder dryer to obtain a single web of long net having a thickness of 15.8 μm and a density of 0.428 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Conventional example 1]
Paper was made with a circular multi-layer combination machine using 65% by weight of a raw material obtained by beating solvent-spun cellulose fibers up to 100 ml of CSF and 35% by weight of hemp pulp, and a circular mesh with a thickness of 40.2 μm and a density of 0.351 g / cm ^3. I got heavy paper. Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.

[Conventional example 2]
Using a mixed raw material of 40% by weight of Manila hemp pulp, 35% by weight of hemp pulp, and 25% by weight of esparto pulp, paper is made by a circular multi-layer combination machine. Thereafter, a diluted solution of polyacrylamide resin was impregnated and applied with a direct roll coater and dried with a cylinder dryer to obtain a circular triplex paper having a thickness of 61.2 μm and a density of 0.278 g / cm ³ . Next, using this separator, a 50 WV, 220 μF aluminum electrolytic capacitor was obtained.
In addition, since the polyester fiber is not contained in the prior art example 1 and the prior art example 2, but the other fiber is contained, description of the fiber seed | species structure in Table 2 is abbreviate | omitted.

About each Example and each comparative example manufactured by the above, and each separator and aluminum electrolytic capacitor of each conventional example, thickness (micrometer), density (g / cm < ³ >), tensile strength (N / 15mm), (gamma)- Butyrolactone retention rate (%), ethylene glycol retention rate (%), aging short defect rate (%), and ESR (Ω / 1 kHz) were measured.

〔Evaluation method〕
The thickness and density of the separator were measured by the method specified in JIS C 2300 (Test method for cellulose paper for electricity).

Tensile strength of separator Five or more test pieces having a width of 15 mm and a length of 250 mm were taken in the longitudinal direction of the separator and measured by the tensile strength measuring method defined in JIS C2300, and the average value was determined as the tensile strength of the separator. did.

Liquid retention rate of the separator A test piece having a size of 50 × 50 mm is taken and immersed in γ-butyrolactone or ethylene glycol for 60 minutes. This is hung vertically and the weight after 60 minutes is measured. From the weight before and after the immersion, the liquid retention rate of the electrolytic solution is calculated.
Liquid retention ratio (%) = [(weight after immersion−weight before immersion) / weight before immersion] × 100

Aging short circuit failure rate is gradually increased to 62.5V, and aging is performed. Those that cannot be boosted from the initial stage and those whose voltage drops during boosting are regarded as aging short defects, and the ratio of defective elements to the total number of elements is aging short. The defective rate.

ESR (Equivalent Series Resistance)
The ESR of the aluminum electrolytic capacitor was measured using an LCR meter at a frequency of 20 ° C. and 1 kHz.

Capacity reduction rate The aluminum electrolytic capacitor was left unloaded without applying voltage in an atmosphere of 85 ° C., and after 2000 hours, the treatment was performed at 20 ° C. according to JIS C5104 4.1, and the capacitance was measured. The rate of decrease with respect to the initial capacity value was defined as the capacity decrease rate (hereinafter abbreviated as ΔC).

Table 2 shows the results of measuring the characteristics of the aluminum electrolytic capacitors of the example, the comparative example, and the conventional example measured by the method described above.

  As shown in Table 2, the aluminum electrolytic capacitor obtained with the configuration according to the present embodiment has a small ΔC, a low aging short-circuit defect rate, and a large ESR with respect to both GBL and EG electrolytes. You can see that it has improved. Further, when the capacitor element is manufactured, the tensile strength that can be used is 7.8 N / 15 mm or more, and all the examples show values of 7.8 N / 15 mm or more.

For example, Example 1 is a circular multi-layer combination machine using 50% by weight of a raw material obtained by beating solvent-spun cellulose fibers having an aspect ratio of 500 to 70 ml of CSF and 50% by weight of polyethylene naphthalate fibers having a fiber diameter of 10 μm. By using a circular double paper having a thickness of 40.1 μm and a density of 0.201 g / cm ³ , the GBL retention rate was 455.4% and the EG retention rate was 308. .7%, both of which are large numbers. ΔC is 2.79% for GBL and 3.52% for EG, both of which are small numerical values. The tensile strength was 16.1 N / 15 mm, and the handling during element winding was also good.

On the other hand, Comparative Example 1 was obtained by making paper with a circular net paper machine using 90% by weight of raw material obtained by beating solvent-spun cellulose fiber up to 450 ml of CSF and 10% by weight of PVA binder fiber. A circular single sheet having a thickness of 40.5 μm and a density of 0.227 g / cm ³ was used. Since solvent-spun cellulose fibers are lyophilic with EG, the liquid retention rate of EG is 284.2%, but the liquid retention rate in GBL is 176.2%. Less than half.

  The liquid retention rate in the EG of Comparative Example 1 is 284.2%, which is about 90% of the liquid retention rate of Example 1. ΔC is 13.67% for GBL and 5.90% for EG, both of which are larger than Example 1 and worsening. For this reason, it turns out that the comparative example 1 has difficulty in the lifetime of a capacitor | condenser. In Comparative Example 1, the solvent-spun cellulose fiber has a high CSF of 450 ml, and since fibrillation has not progressed, strength improvement cannot be expected, and 10% by weight of PVA binder is blended, but the tensile strength is only 7.1 N / 15 mm. No paper break occurred during element winding.

Further, due to the film forming action of the PVA binder, the ESR in GBL is as high as 0.907Ω, which is 28.5% worse than in Example 1. The ESR of EG is 0.525Ω at 1 kHz, which is 25.3% worse than that of Example 1.
In Comparative Example 2, as in Comparative Example 1, the liquid retention rate of GBL is as low as 174.4%, which is about 40% of the liquid retention rate of Example 1. ΔC is 13.86% in GBL, which is a numerical value larger than that of Example 1 and worsening.

  The liquid retention rate of EG is 252.2%, which is about 80% of the liquid retention rate of Example 1. ΔC is 6.3% in EG, which is larger than Example 1 and is worse. For this reason, it turns out that the comparative example 2 has difficulty in the lifetime of a capacitor | condenser. Since a PVA fiber having a solvent-spun cellulose fiber content lower than that of Comparative Example 1 and having no hydrogen bond was used, the tensile strength was weaker than that of Comparative Example 1 and did not have a strength that could withstand use.

  The ESR of GBL is as high as 0.868Ω, which is 22.9% worse than that of Example 1. The ESR in EG is 0.633Ω at 1 kHz, which is 50.9% worse than that in Example 1.

Since Conventional Example 1 is composed of EG and highly lyophilic fibers, the liquid retention rate in EG is as high as 328.3% and ΔC is 3.26%. Although it is a numerical value close to Example 1, the liquid retention rate in GBL is 202.8%, which is about 40% of the liquid retention rate of Example 1. ΔC is 7.01%, which is a larger value than that of Example 1, and is worsening. The ESR in GBL is 0.817Ω, which is 15.7% worse than that in Example 1.
ESR in EG was 0.599Ω, 42.7% worse than that of Example 1.

  Moreover, the liquid retention rate of GBL of Example 2 was 309.7%, and the liquid retention rate of EG was 351.6%, both showing large numerical values. ΔC is 3.77% for GBL and 2.96% for EG, both showing small numerical values. The tensile strength was 19.0 N / 15 mm, and the handling during element winding was also good.

  On the other hand, in Comparative Example 3, since the fiber diameter of the polyarylate fiber is as thick as 20 μm, the ESR in GBL is 0.814Ω, which is 28.4% worse than that of Example 2. The ESR of the EG was 0.463Ω, which is 26.2% worse than that of Example 2.

  In Example 3, the liquid retention ratio of GBL was 330.0%, and the liquid retention ratio of EG was 323.0%, both showing large numerical values. ΔC is 3.13% for GBL and 3.22% for EG, both showing small numerical values. The tensile strength was 8.8 N / 15 mm, and the handling during element winding was also good.

  On the other hand, Comparative Example 4 has an aspect ratio as high as 900 compared to Example 3, so the tensile strength is as high as 10.5 N / 15 mm, but there are many fibers entangled by beating. Since the separator texture was deteriorated, the aging failure rate was 2.2%, which was 7.3 times that of Example 3.

  In Comparative Example 5, the aspect ratio is as low as 200 as compared with Example 3, so the tensile strength is as low as 3.9 N / 15 mm. Since it does not have a strength that can withstand use, many paper breaks occur during winding of the element, and in the configuration of Comparative Example 5, the yield in capacitor manufacturing is reduced. The aging short defect rate is also 2.0%, which is 6.7 times that of Example 3.

  In Conventional Example 2, since the fibers are all composed of natural cellulose, the liquid retention in EG is 378.8%, and ΔC is as small as 2.73%, which is a better value than Example 3. The liquid retention rate in GBL was 234.9%, and ΔC was 6.78%, which is larger than Example 3 and worsening.

  The ESR in GBL is 0.801Ω, which is 3.5% different from that in Example 3. The deterioration is small, but the ESR in EG is 0.616Ω, which is 32.3% worse than that in Example 3.

  In Example 4, the liquid retention rate of GBL was 499.1%, and the liquid retention rate of EG was 367.1%, both showing large numerical values. ΔC is 2.52% for GBL and 2.89% for EG, both showing small numerical values. The tensile strength was 9.7 N / 15 mm, and the handling during element winding was also good.

  In Example 5, the liquid retention ratio of GBL was 498.1%, and the liquid retention ratio of EG was 379.2%, both showing large numerical values. ΔC is 2.73% for GBL and 2.81% for EG, both of which are small values. The tensile strength was 8.2 N / 15 mm, and the handling during element winding was also good.

  On the other hand, in Comparative Example 6, the liquid retention ratio of GBL was 227.1%, the liquid retention ratio of EG was 210.5%, and the liquid retention ratio of GBL was half of the liquid retention ratio of Examples 4 and 5. Hereinafter, the liquid retention rate of EG is about 60% of the liquid retention rate of Examples 4 and 5, which is worse. ΔC was 10.43% in GBL and 9.72% in EG, both showing numerical values larger than Example 5 and worsening. For this reason, it turns out that the comparative example 6 has difficulty in the lifetime of a capacitor | condenser.

  The ESR of the GBL is 1.379Ω, which is 147.5% worse than that of Example 4 and 224.4% worse than that of Example 5. The ESR of the EG was 1.006Ω at 1 kHz, which was 191.3% of the value of Example 4, and 257.3% of Example 5.

  In Example 6, the liquid retention rate of GBL was 377.6%, and the liquid retention rate of EG was 355.7%, both showing large numerical values. ΔC is 3.02% for GBL and 2.94% for EG, both showing small numerical values. The tensile strength was 19.8 N / 15 mm, and the handling during element winding was also good.

  On the other hand, in Comparative Example 7, since the CSF is as high as 220 ml, fine fibrils generated from the solvent-spun cellulose fibers are reduced, and physical entanglement between the fibers is reduced. For this reason, the tensile strength is 11.6 N / 15 mm, which is lower than that of Example 6. Moreover, since there are few fine fibrils, the density of a separator falls and the aging short-circuit defect rate is 1.2%, which is 6.0 times that of Example 6.

  Moreover, in Example 7, the liquid retention rate of GBL was 411.2%, and the liquid retention rate of EG was 364.2%, both showing large numerical values. ΔC is 3.28% for GBL and 2.8% for EG, both showing small numerical values. The tensile strength was 25.9 N / 15 mm, and the handling during element winding was also good.

  On the other hand, in Comparative Example 8, the liquid retention ratio in GBL is 191.0%, and the liquid retention ratio in EG is 185.4%, which is about 50% of the liquid retention ratio in Example 7, respectively. ΔC was 10.83% in GBL and 12.92% in EG, both showing numerical values larger than Example 7 and worsening. For this reason, it turns out that the comparative example 8 has difficulty in the lifetime of a capacitor | condenser. The ESR in GBL is 1.081Ω, which is 73.8% of Example 7, and the ESR in EG is 0.685Ω, which is 86.2% worse than in Example 7.

  In Comparative Example 9, since the blending ratio of polyethylene naphthalate is as high as 60% by weight, the liquid retention ratio in EG is 288.4%, which is about 80% compared with the liquid retention ratio in Example 7. ing. ΔC is 5.76% in EG, which is larger than that of Example 7 and is worse. For this reason, it turns out that the comparative example 9 has difficulty in the lifetime of a capacitor | condenser.

  Further, since the blending ratio of polyethylene naphthalate is increased as compared with Example 7, the solvent-spun cellulose fiber is reduced and the density of the separator is lowered. For this reason, the aging short defect rate is 1.4%, which is 14.0 times that of Example 7.

  In Comparative Example 10, since the blending ratio of polyethylene naphthalate is as low as 10% by weight, the liquid retention rate in GBL is 221.8%, which is about 50% of Example 7. ΔC is 9.93% in GBL, which is larger than that of Example 7 and is worsening. For this reason, it turns out that the comparative example 10 has difficulty in the lifetime of a capacitor | condenser.

  In Example 8, the GBL liquid retention rate was 388.0%, and the EG liquid retention rate was 350.4%, both showing large numerical values. ΔC is 3.01% for GBL and 2.90% for EG, both showing small numerical values. The tensile strength was 8.3 N / 15 mm, and the handling during element winding was also good.

  On the other hand, in Comparative Example 11, since the blending ratio of polyethylene terephthalate is as high as 60% by weight, the liquid retention rate in EG is 267.4%, which is about 70% of Example 8. ΔC is 6.08% as EG, which is larger than that of Example 8 and is worse. For this reason, it turns out that the comparative example 11 has difficulty in the lifetime of a capacitor | condenser. In addition, since the blending ratio of polyethylene terephthalate is increased as compared with Example 8, the solvent-spun cellulose fiber is reduced and the density of the separator is lowered. For this reason, the aging short defect rate is 1.5%, which is 7.5 times that of Example 8.

  In Example 9, the liquid retention ratio of GBL was 321.5%, and the liquid retention ratio of EG was 311.3%, both showing large numerical values. ΔC is 3.61% for GBL and 3.43% for EG, both showing small numerical values. The tensile strength was 13.3 N / 15 mm, and the handling during element winding was good.

  On the other hand, in Comparative Example 12, since the blending ratio of polyarylate is as low as 10% by weight, the liquid retention ratio in GBL is 207.9%, which is about 60% of the liquid retention ratio in Example 9. ing. ΔC is 10.29% in GBL, which is a larger numerical value than in Example 9, and is worse. For this reason, it turns out that the comparative example 12 has difficulty in the lifetime of a capacitor | condenser.

  In Example 10, the liquid retention rate of GBL was 403.5%, and the liquid retention rate of EG was 374.9%, both showing large numerical values. ΔC is 2.98% for GBL and 2.74% for EG, both of which are small values. The tensile strength was 17.8 N / 15 mm, and the handling during element winding was also good.

  On the other hand, in Comparative Example 13, since polyethylene naphthalate is not blended, the liquid retention rate in GBL is 229.8%, which is about 60% of the liquid retention rate in Example 10. ΔC is 9.65% in GBL, which is a larger numerical value than Example 10 and is worse. For this reason, it turns out that the comparative example 13 has difficulty in the lifetime of a capacitor | condenser.

  As can be seen from the data described above, each example shows a high electrolyte solution retention rate for both the GBL and EG electrolytes. For this reason, it is difficult for the capacity reduction due to the localization of the electrolytic solution to occur, the ΔC of the aluminum electrolytic capacitor is reduced, and the life can be extended. Further, the ESR is improved as compared with the comparative example and the conventional example, and the ESR of the aluminum electrolytic capacitor can be reduced.

  As described above, according to the present embodiment, for example, in an aluminum electrolytic capacitor in which a separator is interposed between an anode foil and a cathode foil, the solvent-spun cellulose fiber having an aspect ratio of 300 to 800 and the fiber diameter are By blending 20 to 50% by weight of a polyester fiber (polyester, polyethylene terephthalate, polyethylene naphthalate, polyarylate fiber, etc.) that is 18 μm or less and beating the solvent-spun cellulose fiber to CSF 200 ml or less, either GBL or EG In both cases, since the lyophilicity is increased, the liquid retention rate is increased.

  As a result, the ΔC of the capacitor is reduced, the service life is long, the contradictory nature of the separator is the balance between the denseness and low density of the separator, the heat resistance can withstand reflow, and the short circuit resistance is improved. By significantly improving impedance characteristics, particularly ESR, it is possible to provide an aluminum electrolytic capacitor that maintains good ESR.

  Moreover, the aluminum electrolytic capacitor of this embodiment is an aluminum electrolytic capacitor in which a separator is interposed between an anode foil and a cathode foil, and beating solvent-spun cellulose fibers having an aspect ratio of 300 to 800 to CSF 200 ml or less. It is possible to have a strength that can be used without using a binder or binder fiber.

That is, since the binder becomes a film, the ion flow path is not obstructed, and as a result, ESR can be improved. Since the decrease in tensile strength becomes significant when the basis weight is less than 12 g / m ² , a semi-synthetic polymer that does not form a film when dried, such as carboxymethyl cellulose or polyacrylamide, for the purpose of improving handling during winding of the element, Use paper strength enhancers such as synthetic polymers.

  Since the calendar process is not performed in these configurations, there is no ESR deterioration due to the density increase. Furthermore, by beating solvent-spun cellulose up to 200 ml of CSF, the fine fibrils that are generated make the separator dense, and it is possible to improve short-circuiting during device winding and aging.

  Furthermore, ESR is deteriorated by using a separator containing polyester fibers, such as polyester, polyethylene terephthalate, polyethylene naphthalate, polyarylate fibers, etc., having a fiber diameter of 18 μm or less and not fibrillated. Without causing the fibers to disperse uniformly, the texture is improved.

The separator made dense by the fibrillated solvent-spun cellulose fiber is reduced in density by the above-mentioned straight fiber, and the electrolyte solution is held by the polyester fiber in the case of GBL and the solvent-spun cellulose fiber in the case of EG. The capacity reduction rate due to the localization of the liquid is reduced, and the life of the aluminum electrolytic capacitor can be extended.
It is important that these polyester fibers reduce impurities such as chloride ions and sulfate ions to a level that does not corrode or alter the aluminum foil.

  Also, by blending polyester fibers such as polyester, polyethylene terephthalate, polyethylene naphthalate, polyarylate fibers, etc., having a melting point of around 270-350 ° C. and excellent in heat resistance, the heat resistance of solvent-spun cellulose fibers can be improved if it is a simple substance. In addition, the heat resistance of the separator can be improved and the operating temperature range of the aluminum electrolytic capacitor can be expanded.

  As described above, in the present invention, solvent-spun cellulose fibers having an aspect ratio of 300 to 800 and polyester fibers such as polyester, polyethylene terephthalate, polyethylene naphthalate, and polyarylate fibers having a fiber diameter of 18 μm or less are used. By using a separator that is blended by weight% and exhibits good lyophilicity for both GBL and EG electrolytes and has a high liquid retention rate, the capacity reduction rate of capacitors, life, short-circuit resistance, heat resistance, And ESR can be greatly improved.

Claims (6)

An aluminum electrolytic capacitor separator interposed between an anode foil and a cathode foil of an aluminum electrolytic capacitor,
A separator for an aluminum electrolytic capacitor, comprising at least solvent-spun cellulose and chemical fiber.   The separator for an aluminum electrolytic capacitor according to claim 1, wherein the chemical fiber has a fiber diameter of 18 μm or less.   The separator for an aluminum electrolytic capacitor according to claim 1 or 2, wherein the chemical fiber is a straight fiber that is not fibrillated.   4. The aluminum electrolytic capacitor according to claim 1, wherein the chemical fiber is at least one selected from polyester fibers such as polyester, polyethylene terephthalate, polyethylene naphthalate, and polyarylate fibers. 5. Separator.   The separator for an aluminum electrolytic capacitor according to any one of claims 1 to 4, wherein the solvent-spun cellulose fiber is beaten to 200 ml or less of CSF.   An aluminum electrolytic capacitor using the separator according to any one of claims 1 to 5.