KR20180056383A - Separator for aluminum electrolytic capacitor and aluminum electrolytic capacitor - Google Patents

Abstract

The present invention relates to a separator for a solid electrolytic condenser or a hybrid electrolytic condenser which has at least one layer of non-woven fabric layer and is interposed between a pair of electrodes. The non-woven fabric layer contains 20 or more mass% of synthetic fibers, has 130% or more of a compression complementary rate, and contains 0.1-8.0% of microfibers of which the length ranges from 0.05 mm or more to less than 0.2 mm. Desirably, the synthetic fibers are at least one selected among nylon, aramid, acryl, and polyester fibers. Moreover, preferably, the non-fabric layer contains 0.1-8.0% of microfibers of which the length ranges from 0.05 mm or more to less than 0.2 mm. An electrolytic capacitor using such separator improves a separator complementary force, increases a conductive polymer maintaining amount for a separator, and reduces an ESR.

Description

TECHNICAL FIELD [0001] The present invention relates to separators for aluminum electrolytic capacitors, and separators for aluminum electrolytic capacitors and separators for aluminum electrolytic capacitors.

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

In recent years, with the digitization of electronic apparatuses and automobile electric apparatuses, these apparatuses are becoming more sophisticated and high-performance, and further miniaturization of these apparatuses is also required, and electronic circuit boards used in apparatuses are also required to be miniaturized.

An aluminum electrolytic capacitor (hereinafter referred to as "solid electrolytic capacitor") using a conductive polymer as a cathode material is superior in ESR (equivalent series resistance) characteristics to an aluminum electrolytic capacitor using an electrolytic solution as a cathode material, It is possible to miniaturize the system.

Recently, a conductive polymer hybrid aluminum electrolytic capacitor (hereinafter referred to as "hybrid electrolytic capacitor") using a conductive polymer and an electrolytic solution together as a negative electrode material has been provided by each company of a capacitor manufacturer. It is also used for automobiles, which is an essential requirement that there is no defect.

As a separator used in a solid electrolytic capacitor, there is also a cellulose separator. Usually, a separator made of cellulose is used by carrying out carbonization treatment. This is because carbonization treatment of the cellulosic separator improves the resistance of the separator to the oxidizing agent and increases the porosity of the separator by carbonization, so that impregnation of the polymerization liquid of the conductive polymer can also be improved.

However, thermal degradation of the cellulose fibers occurs due to the heat applied in the carbonization process of the separator, and the mechanical strength of the separator is deteriorated by this heat deterioration. Further, since the cellulose fibers are slowly decomposed under acidic conditions, if the polymer solution of the conductive polymer containing an oxidizing agent or the dispersion liquid showing acidity is impregnated in the capacitor element, the mechanical strength of the separator is remarkably deteriorated. As the mechanical strength of the separator is lowered, there is a possibility that the short failure of the condenser is increased.

In order to avoid such a problem of the cellulose separator, for example, as described in Patent Documents 1 to 3, a separator containing synthetic fibers is used.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-165593 Patent Document 2: JP-A-2004-235293 Patent Document 3: JP-A-2013-197297

Patent Document 1 proposes a separator containing a semi-aromatic polyamide resin as synthetic fibers. It is described that this separator has good impregnation property with the conductive polymeric liquid polymerization solution. It is also described that ESR can be reduced by using the separator.

Patent Document 2 discloses a separator which comprises a non-fibrillated organic fiber, a fibrillated polymer having a melting point or a thermal decomposition temperature of 250 ° C or higher and an absorption rate of 5 mm / min or more as synthetic fibers. By using this separator, the formation of the conductive polymer in the solid capacitor becomes uniform, and the resistance of the solid electrolytic capacitor is reduced.

Patent Document 3 discloses a separator in which the ratio of the orientation properties of the synthetic fibers is 2.0 or less and describes that the liquid absorbency of the polymer liquid and the dispersion liquid of the conductive polymer from the transverse direction of the separator is improved. It is described that the ESR of the solid electrolytic capacitor can be reduced by using this separator.

In the separators described in Patent Documents 1 to 3, the formation and maintenance of the conductive polymer are important for the lowering of the ESR of the solid electrolytic capacitor, and the absorption and the absorption rate of the separator are used as parameters thereof.

However, capacitors using a separator having a high absorption rate or a high liquid-absorbing capacity as described in Patent Documents 1 to 3 have recently been required to have further low ESR. For this reason, there is a possibility that the polymer liquid or dispersion liquid of the conductive polymer leaks from the separator after impregnation with the polymer liquid or dispersion of the conductive polymer.

The inventors of the present invention have made intensive investigations on such problems, and as a result, they found that it is necessary to increase the amount of the conductive polymer in the capacitor element to reduce the ESR of the capacitor, which has recently been required. For this purpose, it has been found that it is important that the separator has a high ability of holding the polymer solution or dispersion for forming the conductive polymer.

In this respect, the inventors of the present invention have found that the parameter most affecting the formation and maintenance of the conductive polymer in the solid electrolytic capacitor is the liquid-repellency of the separator.

The conductive polymer layer can be obtained by impregnating a device obtained by winding a pair of electrode foils with a separator interposed therebetween and by polymerizing and drying the polymer electrolyte solution or by impregnating and drying a dispersion of the conductive polymer . It was found that the amount of holding the conductive polymer in the capacitor element depends on the amount that the separator can linger, and the amount of the separator capable of losing the liquid affects the ESR characteristics.

On the other hand, in order to increase the holding amount of the conductive polymer, for example, a method of increasing the impregnation time in the manufacturing process of the capacitor, increasing the degree of vacuum at the time of impregnation, or increasing the number of impregnation can be considered. There is a possibility that the productivity of the capacitor is lowered and the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to improve the ESR of an aluminum electrolytic capacitor using such a separator by increasing the retaining amount of the conductive polymer to the separator by improving the separator repelling force.

The present invention has been made for the purpose of solving the above-mentioned problems, and has the following constitution as one means for achieving a related object.

That is, the present invention is a separator for a solid electrolytic capacitor or a hybrid electrolytic capacitor having at least one nonwoven fabric layer and interposed between a pair of electrodes, wherein the nonwoven fabric layer contains 20% by mass or more of synthetic fibers, And a compressive laminating ratio of 130% or more, and a content of fine fibers having a fiber length of 0.05 mm or more and less than 0.2 mm is in a range of 0.1 to 8.0%.

For example, the synthetic fibers are at least one kind of fibers selected from nylon fibers, aramid fibers, acrylic fibers, and polyester fibers.

Further, the present invention is characterized in that it is a solid electrolytic capacitor using a solid electrolytic capacitor or a separator for a hybrid electrolytic capacitor, or a hybrid electrolytic capacitor. For example, the solid electrolytic capacitor or the hybrid electrolytic capacitor of the present invention is characterized by using a conductive polymer as a cathode.

According to the present invention, it is possible to improve the deflecting force of the separator, to lower the ESR of the aluminum electrolytic capacitor using the separator of the present invention, and to suppress the occurrence of the short failure of the aluminum electrolytic capacitor using the separator of the present invention .

Hereinafter, one embodiment of the present invention will be described in detail. In the embodiment of the present invention, attention is paid to the separator replenishing force, and a sec- ond liquid permeability is secured.

When a separator is wound between a pair of electrodes to form a capacitor element, the separator is compressed by both electrode foils. This is because, in the case of a separator having a high impregnation property, although it is effective for shortening the impregnation time and the like, there is a case where the holding amount of the conductive polymer can not be increased in such a compressed state. Thus, in the present embodiment, a predetermined compression ratio is ensured by assuming a state in which the condenser element is formed, not impregnating property such as absorbency or absorption.

That is, the separator of the present embodiment is a separator for an aluminum electrolytic capacitor interposed between a pair of electrodes, and the compressive porosity of the separator is 130% or more. The compressive compressive load is preferably 160% or more, and more preferably 190% or more. There is no upper limit to the compressive solubility of the separator. However, judging from the thickness and density of the separator applicable to practical capacitors, the upper limit is considered to be about 300%.

In the separator of the present embodiment, the ESR is reduced by setting the compressive compressive load to 130% or more. This is because the ESR can not be sufficiently reduced with a lubrication force having a compressive compressive load of less than 130%.

The term "compressive lubrication" as used herein refers to the retention ratio calculated from the difference between the mass of the dry state and the mass after the compression after the separator is dipped in ethanol and compressed, and is used as an index for measuring the performance of the separator.

Specifically, the mass of the separator in a dry state of a certain area was measured, and then the separator was immersed in ethanol and taken out. The separator was weighted to 7 kN / m ² , and the mass was measured. The compressive compressive load was calculated from the difference between the mass and the mass after compression. If the compressive lubrication ratio is maintained, it is possible to irradiate the liquefied force after applying the load to the liquefied separator, and can be used as an index for appropriately measuring the separator liquefaction force after the device winding. Further, in order to immerse the entire surface of the separator test piece with ethanol, the immersion time was set to 30 seconds.

In the present embodiment, the impregnation property of the separator, not the impregnation property, is noted. When the impregnation property of the separator is favorable, impregnation of the polymer solution or dispersion of the conductive polymer becomes favorable, However, as described above, it has recently been required to further lower the ESR, and it has been found that not only the evaluation of the impregnability but also the resistivity is important in order to meet this requirement. If the separator has a compressive laminating ratio of 130% or more after being weighted at ⁷ kN / m ² stronger than the load applied to the separator after the device turns, it can be said to be a separator having high refractory force.

Therefore, when the refractory force is increased, the conductive polymer can be formed to the corner between the surface of the capacitor electrode foil and the electrode foil, and the ESR characteristic can be improved.

According to this embodiment, by using the separator having a high refractory force, the separator can sufficiently retain the polymer liquid or dispersion of the conductive polymer, and the amount of the conductive polymer to be retained is also increased. Further, by containing 20 mass% or more of synthetic fibers in the separator, the acid resistance and the oxidation resistance of the separator are improved, and the mechanical strength of the separator due to the polymerization liquid or dispersion of the conductive polymer can be suppressed.

When the content of the synthetic fibers is less than 20 mass%, that is, when the content of the natural fibers such as cellulose fibers exceeds 80 mass%, the acid resistance and the oxidation resistance of the separator are lowered and the mechanical strength of the separator is lowered, There is a possibility that the defect rate increases.

As the synthetic fiber used in the present embodiment, nylon fiber, aramid fiber, acrylic fiber and polyester fiber are preferable from the viewpoints of acid resistance and oxidation resistance of the separator.

These synthetic fibers may be used in one kind or plural kinds. Among these synthetic fibers, polyamide fibers such as nylon fibers are more preferable from the viewpoint of affinity with the polymer solution of the conductive polymer and the dispersion. These synthetic fibers may be fibrillated chemical fibers or nonfibrillated chemical fibers.

In addition, polyester fibers (hereinafter referred to as "unstretched polyester fibers") produced by suppressing the degree of drawing contribute to enhancement of physical properties such as mechanical strength of the separator. The content of the unstretched polyester fiber is not particularly limited as long as a desired compressive lubrication percentage can be satisfied, but if it is up to about 50% by mass, the compressive lubrication rate is hardly lowered.

The separator of the present embodiment may contain 20 mass% or more of synthetic fibers, and other materials constituting the separator may be synthetic fibers or synthetic fibers. In the case of synthetic fibers, other fibers than the above may be used, and in the case of synthetic fibers, natural fibers such as cellulose may also be used.

In addition, binder fibers such as polyvinyl alcohol fibers can be used in a range that does not affect the compressive lubrication ratio, taking into account the mechanical strength during molding of the separator, winding, and the like. The content of the binder fiber is not particularly limited as long as a desired compressive lubrication rate can be satisfied, but if it is up to about 15% by mass, the compressive lubrication rate is hardly lowered.

By setting the content ratio of the fine fibers of the separator within the range of 0.1 to 8.0%, the compressive storage ratio of the separator can be improved, and the liquid repellency can be increased. The details are unclear, but it is considered that by making the content ratio of the fine fibers 0.1 to 8.0%, the fine fibers are appropriately dispersed and serve as a buffer material for compression. That is, it is considered that the separator has a drag against compression, and it is possible to maintain the thickness, and the repulsive force is not lowered.

The fine fibers in this embodiment are fibers having a fiber length of 0.05 mm or more and less than 0.2 mm. As means for obtaining the fine fibers, for example, any means may be used for preparing the paper making raw material. Generally, a beater, a conical refiner, a disk refiner, a high pressure homogenizer or the like is used.

The fibers having a fiber length of less than 0.05 mm are discharged at the time of sheet forming. In the fibers of 0.2 mm or more, since the fibers are entangled with each other, they are not properly dispersed in the separator and do not serve as cushioning materials.

If the content of the fine fibers is less than 0.1%, the effect of the fine fiber as a buffer material is low, and the weight can not withstand, and the separator repelling force may be lowered. If the content of the fine fibers exceeds 8.0%, the separator becomes excessively dense, and the gap between the fibers becomes small. As a result, the separator repelling force may not be developed.

The thickness and density of the separator of the present embodiment can be selected without particular limitation, with the thickness and density satisfying the characteristics of the desired aluminum electrolytic capacitor. Generally, a separator having a thickness of 20 to 70 mu m and a density of about 0.20 to 0.60 g / cm < ³ > is used, but the present invention is not limited to this range.

In the embodiment of the present invention, the separator employs a wet nonwoven fabric formed by using a papermaking method. The papermaking method of the separator is not particularly limited as long as it can satisfy the compressive laminating ratio or the content ratio of the fine fibers. It is possible to use a papermaking form such as a long puddle puddle, a short puddle puddle paper, A plurality of separators may be used.

In the case of papermaking, additives such as a dispersing agent, a defoaming agent, and an emulsifying agent may be added to the separator for the condenser so long as it does not affect the separator for capacitors. After the formation of the emulsion layer, May be performed.

By employing the above configuration, the separator of this embodiment forms a homogeneous electron conduction path and contributes to an increase in the amount of the conductive polymer to be maintained. By using this separator in an aluminum electrolytic capacitor using a conductive polymer as a negative electrode material, an aluminum electrolytic capacitor of low ESR can be obtained.

In the aluminum electrolytic capacitor of this embodiment, a separator is used as the separator, the separator is sandwiched between a pair of electrodes, and a conductive polymer is used as a negative electrode material.

[Method for Measuring Characteristics of Separator and Aluminum Electrolytic Capacitor]

The specific characteristics of the separator and the aluminum electrolytic capacitor according to the present embodiment were measured by the following conditions and methods.

[Canadian Standard Freeness Chart (CSF)]

CSF is measured according to JIS P8121-2 'Pulp-Freeness Test - Part 2: Canadian Standard' freeness method '(ISO5267-2' Pulps-Determination of drainability-Part2: did.

〔thickness〕

"JIS C 2300-2" Cellulose paper for electrical applications - Part 2: Using the micrometer of "5.1.1 Measuring instrument and measuring method: a. When using an external micrometer" specified in the test method "5.1 Thickness" 5.1.3 When the thickness of the paper is folded and folded, the thickness of the separator is measured by folding and folding in ten sheets.

〔density〕

"JIS C 2300-2 " Cellulose paper for electrical purposes - Part 2: Test method " Density 7.0A"

[Content of fine fibers]

The content of microfine fibers can be measured by the method described in JIS P 8226-2 'Pulp - Determination of fiber length by optical automatic analysis method Part 2: Non-polarizing method' (ISO 16065-2 'Pulps-Determination of Fiber length by automated optical analysis- Part 2 : Unpolarized light method "). Here, the length-weighted average fiber length distribution is measured in the range of 0.05 to 7.6 mm using Kajaani Fiber Lab (Metso Automation Co., Ltd.), and the fiber length Of not less than 0.05 mm and less than 0.2 mm was calculated.

[Compressive Loss Ratio]

Measure the mass of the separator before immersion. Further, the separator was immersed in 20 ethanol for 30 seconds, weighted to ⁷ kN / m < ² >, mass was measured, and the compressive lowness was calculated by the following formula (1).

The measurement was carried out in an environment of room temperature 20 and relative humidity 65%.

Compressive Liquid Percentage (%) = [(W2-W1) / W1] 100 ... (Equation 1)

W1: Specimen mass before immersion (g)

W2: weight of specimen after weighting (g)

[Absorption rate]

The measurement of the absorption rate is carried out using the method described in Method B of Test Method '22 Absorption ", Part 2: Cellulosic paper for electrical use according to JIS C 2300-2, (mm / min). In the above-described Patent Document 2, the separator width is 20 mm, but the measurement is made at the width described in JIS.

[Transpiration in the horizontal direction]

The absorbency was used as an index of the impregnation property of the separator. It is considered that the impregnation property of the separator is increased when the liquid absorbency is increased. In addition, the measurement of the liquid absorbency was carried out by changing the water to ethanol using the method specified in Method B of "JIS C 2300-2 " Cellulose Paper for Electricity - Part 2: Test Method 22 Absorption ". In addition, the liquid-absorbing direction was taken in the transverse direction of the separator in consideration of the process of impregnating the capacitor.

[Process for producing a solid electrolytic capacitor]

A solid electrolytic capacitor having a rated voltage of 6.3 V, a diameter of 10.0 mm and a height of 10.0 mm and a solid electrolytic capacitor having a rated voltage of 50 V and a diameter of 10.0 mm and a height of 15.0 mm were produced using a separator of each of the examples, .

A concrete production method is as follows.

The separator was wound between the positive electrode foil and the negative electrode foil which had been subjected to the etching treatment and the oxide film formation treatment so as to be in contact with each other, thereby producing a capacitor element. The produced capacitor element was subjected to remineralization treatment and then dried.

In the case of a solid electrolytic capacitor having a rated voltage of 6.3 V, the conductive polymeric solution was impregnated into the capacitor element, followed by heating and polymerization, and the solvent was dried to form a conductive polymer. In the case of a solid electrolytic capacitor having a rated voltage of 50 V, a conductive polymer dispersion was impregnated in a capacitor element, followed by heating and drying to form a conductive polymer.

Next, a condenser element was put in a predetermined case, the opening was sealed, and aging was performed to obtain two types of solid electrolytic capacitors having different rated voltages.

[Manufacturing process of hybrid electrolytic capacitor]

A hybrid electrolytic capacitor having a rated voltage of 16 V, a diameter of 10.0 mm and a height of 12.5 mm and a hybrid electrolytic capacitor having a rated voltage of 80 V and a diameter of 10.0 mm and a height of 10.5 mm were produced using a separator of each of Examples, Comparative Examples and Conventional Example.

A concrete production method is as follows.

The separator was wound between the positive electrode foil and the negative electrode foil which had been subjected to the etching treatment and the oxide film formation treatment so as to be in contact with each other, thereby producing a capacitor element. The produced capacitor element was subjected to remineralization treatment and then dried.

In the case of a hybrid electrolytic capacitor having a rated voltage of 16 V, the conductive polymeric solution was impregnated into the capacitor element, followed by heating and polymerization, and the solvent was dried to form a conductive polymer. In the case of a hybrid electrolytic capacitor having a rated voltage of 80 V, a conductive polymer dispersion was impregnated in a capacitor element, followed by heating and drying to form a conductive polymer.

Subsequently, the capacitor element was impregnated with a driving electrolytic solution, the capacitor element was put into a predetermined case, the opening was sealed, and aging was performed to obtain two kinds of hybrid electrolytic capacitors having different rated voltages.

[Evaluation method of aluminum electrolytic capacitor]

The specific performance of the aluminum electrolytic capacitor of the present embodiment was evaluated by the following conditions and methods.

[ESR]

The ESR of the capacitor element thus fabricated was measured using an LCR meter under the conditions of a temperature of 20 캜 and a frequency of 100 kHz.

〔capacitance〕

Capacitance was obtained by the method of "4.7 Capacitance" specified in JIS C 5101-1 'Fixed capacitors for electronic equipment Part 1: General rules for each item' ".

[Shot defect rate]

The short defect ratio was determined by counting the number of short defects occurring during aging by using a wound capacitor element and dividing the number of short defective elements by the number of capacitor elements subjected to aging to obtain a short defect ratio with a percentage.

[Examples]

Hereinafter, specific examples of the separator according to the embodiment of the present invention will be described.

[Example 1]

20% by mass of a semi-aromatic nylon fiber and 80% by mass of fibrillated cellulose fibers (CSF 500 ml) were mixed. The obtained raw material was subjected to grinding to obtain a separator of Example 1. The separator had a thickness of 50 탆 and a density of 0.60 g / cm ³ , a compressive compressive strength of 162%, an absorption rate of 25 mm / min, a transverse liquid absorption of 26 mm / (10 min) and a content of fine fibers of 0.1% .

[Example 2]

20% by mass of acrylic fiber, 10% by mass of polyester fiber and 70% by mass of fibrillated aramid fiber (CSF 30 ml) were mixed. The obtained raw material was subjected to grinding to obtain a separator of Example 2. The separator is the thickness 40㎛, density 0.30g / cm ^3, the compression beam aekryul was 221%, the absorption speed of 16mm / min, the liquid-absorbing in the transverse direction also 6mm / (10 min), the content of the fine fiber is 7.7%.

[Example 3]

75% by mass of semi-aromatic nylon fibers, 20% by mass of fibrillated cellulose fibers (CSF 110 ml) and 5% by mass of polyvinyl alcohol fibers were mixed. The obtained raw material was subjected to grinding to obtain a separator of Example 3. The separator, the thickness 70㎛, density 0.20g / cm ^3, the compression beam aekryul was 289%, the absorption rate 9mm / minute, liquid-absorbing in the transverse direction even 12mm / (10 min), the content of the fine fiber is 3.6% .

[Example 4]

40% by mass aramid fibers, 45% by mass fibrillated cellulose fibers (CSF 210 ml) and 15% by mass polyvinyl alcohol fibers were mixed. The obtained raw material was subjected to grinding to obtain a separator of Example 4. The separator, the thickness 20㎛, a density 0.40g / cm ^3, the compression beam aekryul was 191%, the absorption speed of 4mm / min, the liquid-absorbing in the transverse direction even 20mm / (10 min), the content of the fine fiber is 0.8% .

[Example 5]

30% by mass of a semi-aromatic nylon fiber, 20% by mass of an acrylic fiber and 50% by mass of an unoriented polyester fiber. The obtained raw material was subjected to grinding to obtain a separator of Example 5. The separator had a thickness of 30 탆 and a density of 0.50 g / cm ³ , a compressive compressive strength of 132%, an absorbing speed of 33 mm / min, a lateral liquid immersion degree of 24 mm / (10 min) and a content of fine fibers of 0.0% .

[Example 6]

65% by mass of acrylic fiber and 35% by mass of fibrillated acrylic fiber (20 ml of CSF) were mixed. The obtained raw material was subjected to grinding to obtain a separator of Example 6. The separator had a thickness of 50 탆 and a density of 0.30 g / cm ³ , a compressive compressive strength of 136%, an absorption rate of 11 mm / min, a lateral liquid immersion of 9 mm / (10 min) and a content of fine fibers of 8.6% .

[Comparative Example 1]

A separator was produced by the same manufacturing method as in the method described in Example 1 of Patent Document 1, and used as a separator of Comparative Example 1. The separator of Comparative Example 1 contained 70% by mass of the semi-aromatic nylon fiber and 30% by mass of the polyvinyl alcohol fiber, and had a thickness of 40 탆 and a density of 0.27 g / cm ³ , a compressive lowness of 105% Min, the liquidus in the transverse direction was 14 mm / (10 min), and the content of fine fibers was 0.0%.

[Comparative Example 2]

A separator was produced by the same manufacturing method as in the method described in Example 1 of Patent Document 3, and used as a separator of Comparative Example 2. The separator of Comparative Example 2, polyester fiber of 35% by mass, non-stretched polyester containing polyester fiber 65% by mass, a thickness 50㎛, density 0.40g / cm ^3, the compression beam aekryul is 124%, the absorption speed of 14mm / Minute, the liquidusability in the transverse direction was 19 mm / (10 minutes), and the content of the fine fibers was 0.0%.

[Comparative Example 3]

15% by mass of semi-aromatic nylon fibers and 85% by mass of fibrillated cellulose fibers (CSF 400 ml) were mixed. The obtained raw material was subjected to grinding to obtain a separator of Comparative Example 3. The separator, the thickness 60㎛, a density 0.40g / cm ^3, the compression beam aekryul is 139%, the absorption speed of 28mm / min, the liquid-absorbing even 24mm / (10 min), the content of the fine fibers in the transverse direction was 1.0% .

[Comparative Example 4]

15% by mass of acrylic fiber, 25% by mass of polyester fiber and 60% by mass of fibrillated aramid fiber (CSF 200 ml) were mixed. The obtained raw material was subjected to grinding to obtain a separator of Comparative Example 4. The separator had a thickness of 50 탆 and a density of 0.30 g / cm ³ , a compressive compressive strength of 104%, an absorbing speed of 12 mm / min, a lateral liquid immersion of 16 mm / (10 min) and a content of fine fibers of 4.3% .

[Conventional example]

A separator was produced in the same manner as in the method described in Example 1 of Patent Document 2, and used as a conventional separator. The separator of this conventional example contains 30 mass% of fibrillated aramid fibers (12 ml of CSF), 45 mass% of polyester fibers and 25 mass% of unstretched polyester fibers, and has a thickness of 45 m and a density of 0.35 g / cm ³ , and the compression ratio was 88%, the absorption rate was 10 mm / min, the lateral absorption was 6 mm / (10 min), and the content of fine fibers was 16.2%.

Table 1 shows the evaluation results of the single separator of each of the examples, comparative examples and conventional examples of the present embodiment. Table 1 also includes the absorption rate and the liquid absorption in the transverse direction.

Separator characteristics Synthetic fiber
Content rate compression
Load factor Absorption rate Horizontal absorption Fine fiber
Content ratio thickness density mass% % mm / min mm / 10 min % ㎛ g / cm ³ Example 1 20 162 25 26 0.1 50 0.60 Example 2 100 221 16 6 7.7 40 0.30 Example 3 80 289 9 12 3.6 70 0.20 Example 4 55 191 4 20 0.8 20 0.40 Example 5 100 132 33 24 0.0 30 0.50 Example 6 100 136 11 9 8.6 50 0.30 Comparative Example 1 100 105 3 14 0.0 40 0.27 Comparative Example 2 100 124 14 19 0.0 50 0.40 Comparative Example 3 15 139 28 24 1.0 60 0.40 Comparative Example 4 100 104 12 16 4.3 50 0.30 Conventional example 100 88 10 6 16.2 45 0.35

Table 2 shows the performance evaluation results of the aluminum electrolytic capacitors produced by using the separators of each of the examples, comparative examples and conventional examples. As shown in Table 2, a solid electrolytic capacitor was manufactured by using a condenser of 6.3 V for a low voltage and a condenser of 50 V for a high voltage. Also, a capacitor having a rated voltage of 16 V for a low voltage and a capacitor having a rated voltage of 80 V for a high voltage were fabricated as a hybrid electrolytic capacitor.

Capacitor characteristics after aging Solid electrolytic capacitor Hydride electrolytic capacitor Rated Voltage 6.3V Rated voltage 50V Rated voltage 16V Rated voltage 80V ESR blackout
Volume short
Defect rate ESR blackout
Volume short
Defect rate ESR blackout
Volume short
Defect rate ESR blackout
Volume short
Defect rate mΩ μF % mΩ μF % mΩ μF % mΩ μF % Example 1 16 269 0 18 40 0 19 129 0 23 50 0 Example 2 10 260 0 12 38 0 14 125 0 17 48 0 Example 3 8 263 0 9 39 0 10 126 0 13 49 0 Example 4 13 267 0 14 39 0 16 128 0 19 49 0 Example 5 19 269 0 22 40 0 24 130 0 28 50 0 Example 6 18 263 0 21 39 0 23 126 0 27 48 0 Comparative Example 1 26 264 0 31 39 0 31 127 0 38 49 0 Comparative Example 2 24 269 0 28 40 0 30 129 0 35 50 0 Comparative Example 3 17 269 0.8 20 39 0.7 21 129 0.8 25 50 0.7 Comparative Example 4 27 266 0 32 39 0 32 128 0 39 49 0 Conventional example 34 250 0 38 37 0 35 120 0 42 46 0

[Solid electrolytic capacitor using the separator of Example 1]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 1 was 16 m?, The electrostatic capacity was 269 占,, and the short defect ratio was 0%. The ESR of the solid electrolytic capacitors with a rated voltage of 50 V was 18 mΩ, the electrostatic capacity was 40 μF, and the short failure rate was 0%.

[Hybrid electrolytic capacitor using the separator of Example 1]

The ESR of the hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Example 1 was 19 m, the electrostatic capacity was 129 mu F, and the short defect rate was 0%. The ESR of the hybrid electrolytic capacitor having a rated voltage of 80 V was 23 mΩ, the electrostatic capacity was 50 μF, and the short defect rate was 0%.

[Solid electrolytic capacitor using the separator of Example 2]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 2 was 10 m?, The electrostatic capacity was 260 占,, and the short defect ratio was 0%. The ESR of the solid electrolytic capacitors with a rated voltage of 50 V was 12 mΩ, the electrostatic capacity was 38 μF, and the short defect rate was 0%.

[Hybrid electrolytic capacitor using the separator of Example 2]

The ESR of the hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Example 2 was 14 m?, The electrostatic capacity was 125 占,, and the short defect rate was 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V had an ESR of 17 mΩ, a capacitance of 48 μF, and a short defect ratio of 0%.

[Solid electrolytic capacitor using the separator of Example 3]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 3 was 8 m?, The electrostatic capacity was 263 占,, and the short defect ratio was 0%. The ESR of the solid electrolytic capacitors with a rated voltage of 50 V was 9 mΩ, the capacitance was 39 μF, and the short defect rate was 0%.

[Hybrid electrolytic capacitor using the separator of Example 3]

The ESR of the hybrid electrolytic capacitor having a rated voltage of 16V using the separator of Example 3 was 10 m?, The electrostatic capacity was 126 占,, and the short defect rate was 0%. The ESR of the hybrid electrolytic capacitor with a rated voltage of 80 V was 13 mΩ, the electrostatic capacity was 49 μF, and the short defect rate was 0%.

[Solid electrolytic capacitor using the separator of Example 4]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 4 was 13 m ?, the electrostatic capacity was 267 占,, and the shot defective rate was 0%. The ESR of the solid electrolytic capacitors with a rated voltage of 50 V was 14 mΩ, the electrostatic capacity was 39 μF, and the short defect rate was 0%.

[Hybrid electrolytic capacitor using the separator of Example 4]

The ESR of the hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Example 4 was 16 m?, The capacitance was 128 占,, and the short defect rate was 0%. The ESR of the hybrid electrolytic capacitor with a rated voltage of 80 V was 19 mΩ, the capacitance was 49 μF, and the short defect rate was 0%.

[Solid electrolytic capacitor using the separator of Example 5]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 5 was 19 m?, The electrostatic capacity was 269 占,, and the short defect ratio was 0%. The ESR of the solid electrolytic capacitors with a rated voltage of 50 V was 22 mΩ, the electrostatic capacity was 40 μF, and the short defect rate was 0%.

[Hybrid electrolytic capacitor using the separator of Example 5]

The ESR of the hybrid electrolytic capacitor of rated voltage of 16V using the separator of Example 5 was 24 m?, The electrostatic capacity was 130 占,, and the shot defective rate was 0%. The ESR of the hybrid electrolytic capacitor having a rated voltage of 80 V was 28 mΩ, the electrostatic capacity was 50 μF, and the short defect rate was 0%.

[Solid electrolytic capacitor using the separator of Example 6]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 6 was 18 m ?, the electrostatic capacity was 263 占,, and the short defect ratio was 0%. The ESR of the solid electrolytic capacitors with a rated voltage of 50 V was 21 mΩ, the capacitance was 39 μF, and the short defect rate was 0%.

[Hybrid electrolytic capacitor using the separator of Example 6]

The ESR of the hybrid electrolytic capacitor having a rated voltage of 16V using the separator of Example 6 was 23 m?, The capacitance was 126 占,, and the short defect ratio was 0%. The ESR of the hybrid electrolytic capacitor with a rated voltage of 80 V was 27 mΩ, the electrostatic capacity was 48 μF, and the short failure rate was 0%.

[Solid electrolytic capacitor using the separator of Comparative Example 1]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Comparative Example 1 was 26 mΩ, the electrostatic capacity was 264 μF, and the short failure rate was 0%. The ESR of the solid electrolytic capacitors with a rated voltage of 50 V was 31 mΩ, the capacitance was 39 μF, and the short defect rate was 0%.

[Hybrid electrolytic capacitor using the separator of Comparative Example 1]

The ESR of the hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Comparative Example 1 was 31 m?, The electrostatic capacity was 127 占,, and the short defect ratio was 0%. The ESR of the hybrid electrolytic capacitor with a rated voltage of 80 V was 38 mΩ, the capacitance was 49 μF, and the short defect rate was 0%.

[Solid electrolytic capacitor using the separator of Comparative Example 2]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Comparative Example 2 was 24 m?, The electrostatic capacity was 269 占,, and the shot defective rate was 0%. The ESR of the solid electrolytic capacitors with a rated voltage of 50 V was 28 mΩ, the electrostatic capacity was 40 μF, and the short defect rate was 0%.

[Hybrid electrolytic capacitor using the separator of Comparative Example 2]

The ESR of the hybrid electrolytic capacitor having a rated voltage of 16V using the separator of Comparative Example 2 was 30 m?, The electrostatic capacity was 129 占,, and the short defect ratio was 0%. The ESR of the hybrid electrolytic capacitor with a rated voltage of 80 V was 35 mΩ, the electrostatic capacity was 50 μF, and the short defect rate was 0%.

[Solid electrolytic capacitor using the separator of Comparative Example 3]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Comparative Example 3 was 17 m ?, the electrostatic capacity was 269 占,, and the shot defective ratio was 0.8%. The ESR of the solid electrolytic capacitors with a rated voltage of 50 V was 20 mΩ, the capacitance was 39 μF, and the short defect rate was 0.7%.

[Hybrid electrolytic capacitor using the separator of Comparative Example 3]

The ESR of the hybrid electrolytic capacitor having a rated voltage of 16V using the separator of Comparative Example 3 was 21 m?, The electrostatic capacity was 129 占,, and the short defect rate was 0.8%. The ESR of the hybrid electrolytic capacitor with a rated voltage of 80 V was 25 mΩ, the capacitance was 50 μF, and the short defect rate was 0.7%.

[Solid electrolytic capacitor using the separator of Comparative Example 4]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Comparative Example 4 was 27 mΩ, the electrostatic capacity was 266 μF, and the short failure rate was 0%. The ESR of the solid electrolytic capacitors with a rated voltage of 50 V was 32 mΩ, the capacitance was 39 μF, and the short defect rate was 0%.

[Hybrid electrolytic capacitor using the separator of Comparative Example 4]

The ESR of the hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Comparative Example 4 was 32 m?, The electrostatic capacity was 128 占,, and the short defect rate was 0%. The ESR of the hybrid electrolytic capacitor with a rated voltage of 80 V was 39 mΩ, the capacitance was 49 μF, and the short defect rate was 0%.

[Solid electrolytic capacitor using a conventional separator]

The ESR of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of the conventional example was 34 m.OMEGA., The electrostatic capacity was 250 .mu.F, and the short failure rate was 0%. The ESR of the solid electrolytic capacitor with a rated voltage of 50 V was 38 mΩ, the electrostatic capacity was 37 μF, and the short defect rate was 0%.

[Hybrid electrolytic capacitor using a conventional separator]

The ESR of the hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of the conventional example was 35 mΩ, the capacitance was 120 μF, and the short defect rate was 0%. The ESR of the hybrid electrolytic capacitor with a rated voltage of 80 V was 42 mΩ, the electrostatic capacity was 46 μF, and the short defect rate was 0%.

As is apparent from the above, the solid electrolytic capacitors having rated voltages of 6.3 V using the separators of Examples 1 to 4 have a low ESR of 8 to 16 m?, A capacitance of 260 to 269 占,, and no short failure occurs. Solid electrolytic capacitors with a rated voltage of 50 V using a copper separator also have ESR values of 9 to 18 mΩ, capacitances of 38 to 40 μF, and no short failure.

Also in the evaluation of the hybrid electrolytic capacitor having a rated voltage of 16 V using the separators of Examples 1 to 4, the ESR is as low as 10 to 19 m ?, the electrostatic capacity is 125 to 129 占,, and no short failure occurs. Hybrid electrolytic capacitors with a rated voltage of 80V using a copper separator also have low ESR of 13 to 23 mΩ and electrostatic capacities of 48 to 50 μF, and no short failure occurs.

The compressive lowness of the separator of Examples 1 to 4 was 162 to 289%. In this regard, the separator of the present embodiment is excellent in liquid-repellency and can sufficiently retain the amount of the conductive polymer contained in the capacitor element. It is known that the solid electrolytic capacitor and the hybrid electrolytic capacitor contribute to the lowering of the ESR .

The separator of Example 5 is a separator having a compressive compressive strength of 132%. The solid electrolytic capacitors and the hybrid electrolytic capacitors using this separator had no difference in electrostatic capacitance but a slightly worsened ESR as compared with Examples 1 to 4. This is presumably because the content of the fine fibers is 0.0% and there is no effect as a buffer material against the pressure.

Thus, it is considered that the separator retention force of Example 5 was lowered and the amount of the conductive polymer contained in the capacitor element was insufficient, which slightly affected the ESR of the capacitor. From the comparison of Examples 1 to 4 and Example 5, it can be seen that the ESR of the capacitor can be further reduced if the content of the fine fibers in the separator is 0.1% or more.

The separator of Example 6 is a separator having a compressive packing ratio of 136%. The solid electrolytic capacitors and the hybrid electrolytic capacitors using this separator have a slightly worsened ESR although there is no difference in capacitance in comparison with Examples 1 to 4. This is presumably because the content ratio of the fine fibers is 8.6%, which is higher than that of Examples 1 to 4, whereby the compactness of the separator becomes excessively high and the gap between the fibers becomes small.

As a result, the separator retention force is lowered, so that the holding amount of the conductive polymer in the capacitor element is insufficient, and it is considered that this slightly affects the ESR of the capacitor. From the comparison of Examples 1 to 4 and Example 6, it can be seen that the ESR of the capacitor can be further reduced if the content of the fine fibers in the separator is 8.0% or less.

The separator of Comparative Example 1 is the same as the separator described in Example 1 of Patent Document 1, but has a compressive solubility of 105%. As a result, there is no difference in the electrostatic capacity, but the ESR is higher as compared with the evaluation result of the capacitor using the separator of each embodiment. This is presumably because the polyvinyl alcohol fiber contained in the polyvinyl alcohol fiber in an amount of 30% by mass occupied the gap between the fibers, that is, the portion where the conductive polymer was held in advance, thereby lowering the separator repelling force.

In this respect, it was found that the content of the binder fiber such as the polyvinyl alcohol fiber is related to the decrease in the compressive lowness, and affects the amount of the conductive polymer contained in the capacitor element. As a result, it can be seen that the content of the binder fiber such as the polyvinyl alcohol fiber is not adversely affected by the content of 15% by mass or less, as in Example 4.

The separator of Comparative Example 2 is the same as the separator described in Example 1 of Patent Document 3, but the content of the fine fibers is 0.0% and the compressive compressibility is 124%. Compared with the evaluation results of the capacitors using the separators of the respective embodiments, there is no difference in the electrostatic capacity but the ESR is high. It is considered that this is because the unstretched polyester fibers are as large as 65 mass% and the voids between the fibers, that is, the portion in which the conductive polymer is held, are preliminarily occupied by binding of the fibers. From this point, it can be seen that when the content of the unstretched polyester fibers is 50% by mass or less, adverse effects are not exerted on the compressive lowness.

The separator of Comparative Example 3 had the same thickness, density, and compressive lowness as the examples, but the content of the synthetic fibers was 15 mass%, which is smaller than those of the examples. The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of this comparative example 3 had a shot defective rate of 0.8% at the time of aging and was higher than that of each example. In addition, even in the case of a solid electrolytic capacitor having a rated voltage of 50 V, the shot defective ratio at the time of aging was 0.7%, which is higher than that in each example. Even in the hybrid electrolytic capacitor having a rated voltage of 16 V, the shot defective ratio during aging was 0.8%. The hybrid electrolytic capacitor having a rated voltage of 80 V, which is higher than those of the examples, had a shot defect rate of 0.7% high.

This is considered to be caused by the fact that the separator of Comparative Example 3 contained only 15 mass% of the synthetic fibers in the entire separator, and the mechanical strength of the separator was lowered due to the polymerization liquid or dispersion of the conductive polymer. From this point, it can be understood that the content ratio of the synthetic fibers is insufficient at 15 mass% and 20 mass% or more is necessary for reducing the shot defective ratio of the capacitor.

In the separator of Comparative Example 4, the thickness, the density, and the content of the fine fibers were the same level as in the Examples, but the compressive compressibility was 104%. With respect to the compressive lowness, the ESR of each capacitor using the separator of Comparative Example 4 is all high. In each of the examples and the reference examples, the ESR of the capacitor is not reduced when the compressive lowness is less than 130%.

Therefore, it can be understood from the comparison between the comparative examples 1, 2, and 4 and each example that the compression ratio of the separator should be 130% or more in order to reduce the ESR.

The separator of the conventional example is the same as the separator described in Example 1 of Patent Document 2, but the content ratio of the fine fibers is as high as 16.2% and the compressive solubility is as low as 88%. As a result, the electrostatic capacitance is slightly lower and the ESR is also higher in the evaluation of each capacitor. This is considered to be because the conventional separator has a very high content of fine fibers and an excessively high compactness of the separator and a small gap between the fibers. Therefore, it is considered that the liquid-repellency of the polymerization liquid or dispersion of the conductive polymer is lowered.

In each of the examples, reference examples, and conventional examples, the highest absorption rate is Example 5, but the lowest ESR of each rated voltage of the solid electrolytic capacitor and the hybrid electrolytic capacitor is Example 3.

Likewise, among Examples, Reference Examples, and Conventional Examples, Example 1 has the highest liquid absorption in the transverse direction, but Example 3 is the one in which the ESR of each rated voltage of the solid electrolytic capacitor and the hybrid electrolytic capacitor is lowest.

It can be seen that the electrolyte membrane of the third embodiment has the highest compressive lubrication ratio and is more liquefied than the separator with respect to the absorption rate and the liquid absorption which have the greatest influence on the ESR reduction of the condenser.

Further, it is possible to measure the separator lyotropic force under an environment in which a load is applied, and it can be used as an index for examining the characteristics of the condenser.

As described above, the separator according to the present embodiment is a separator having improved refractory force. By using the separator for the capacitor, the ESR can be reduced, and also the short failure can be suppressed. In addition, there is a possibility that the separator contributes to the improvement of the productivity of the capacitor and the reduction of the manufacturing cost.

Claims (6)

A separator for a solid electrolytic capacitor or a hybrid electrolytic capacitor having at least one nonwoven fabric layer and interposed between a pair of electrodes,
Characterized in that the nonwoven fabric layer contains 20% by mass or more of synthetic fibers and has a compressive laminating ratio of 130% or more and a content ratio of fine fibers having a fiber length of 0.05 mm or more and less than 0.2 mm in a range of 0.1 to 8.0% And a separator for a solid electrolytic capacitor or a hybrid electrolytic capacitor. The method according to claim 1,
Wherein the synthetic fiber is at least one fiber selected from nylon fiber, aramid fiber, acrylic fiber and polyester fiber. A solid electrolytic capacitor using the separator for a solid electrolytic capacitor according to claim 1 or 2. The method of claim 3,
A solid electrolytic capacitor characterized by using a conductive polymer as a cathode. A hybrid electrolytic capacitor using the separator for a hybrid electrolytic capacitor according to claim 1 or 2. The method of claim 5,
A hybrid electrolytic capacitor characterized by using a conductive polymer as a cathode.