JP2001267182A - Electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor for upgrading a short circuit defective ratio without giving an adverse influence to an equivalent series resistance by improving a tensile strength at a low density by reducing a cationic amount to be extracted irrespective of a type of an electrolyte and improving productivity and lifetime characteristics. SOLUTION: The electrolytic capacitor is formed by interposing electrolytic paper between an anode foil and a cathode foil. Thus, the paper after papermaking is impregnated and coated with a paper strength reinforcing agent in which a total amount of cations of Na, K, Ca and Mg is reduced to 500 ppm or less or preferably 100 ppm or less. In this case, individual contents of Na, K, and Ca and Mg of the agent are set to 25 ppm or less. As the agent, one or a plurality of types selected from a starch, vegitative gum, semi-synthetic polymer and a synthetic polymer are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor comprising an electrolytic paper interposed between an anode foil and a cathode foil. By increasing the tensile strength of the electrolytic paper, it is possible to reduce the short-circuit failure rate without adversely affecting impedance characteristics, particularly equivalent series resistance (hereinafter, abbreviated as ESR), to improve the life characteristics, and to improve productivity. The present invention relates to a possible electrolytic capacitor.

[0002]

2. Description of the Related Art Generally, an electrolytic capacitor, particularly an aluminum electrolytic capacitor, is formed by winding an electrolytic paper between an anode aluminum foil and a cathode aluminum foil to form a capacitor element. It is immersed in an electrolytic solution, impregnated with an electrolyte, and sealed. As the electrolyte, ethylene glycol (EG), dimethylformamide (DMF) or γ-butyrolactone (G
BL) or the like, and a solution obtained by dissolving an organic acid salt such as boric acid, ammonium adipate, or ammonium hydrogen maleate in these solvents, and penetrating from both ends of the capacitor element.

[0003] In these conventional aluminum electrolytic capacitors, since the electrolytic solution is impregnated in the electrolytic paper, the ESR of the capacitor is likely to be high. Therefore, in order to improve the ESR, the resistance of the electrolytic solution is reduced or the electrolytic paper is reduced. In addition to means for reducing the thickness or density, means for changing the raw material for electrolytic paper from ordinary wood kraft pulp to Manila hemp pulp, esparto pulp, and the like are used. However, while lowering the resistance of the electrolyte causes corrosion to the aluminum foil, thinning or lowering the density of the electrolytic paper inevitably lowers the tensile strength and increases the short-circuit failure rate. However, even if no short circuit occurs, there is a problem that the short-circuit failure rate after the product is put on the market and put on the market is high.

In order to reduce the short-circuit defect rate,
Means for increasing the thickness or increasing the density of the electrolytic paper can be considered. For this purpose, CSF (Canadian S.P.S.) according to JIS P 8121 indicating the degree of beating of pulp as a raw material of electrolytic paper is considered.
tandard Freeness) and other measures, such as reducing the value of the pulp, fibrillates and becomes finer,
The obtained electrolytic paper becomes dense, the tensile strength increases, and the short-circuit defect rate is improved. Also, it has been found that when the thickness of the electrolytic paper increases, the effect on the ESR deteriorates in a linear manner, and when the density of the electrolytic paper increases, the ESR deteriorates in a quadratic manner. That is, in order to improve the ESR, it is necessary to make the electrolytic paper thinner and lower its density, contrary to the improvement of the short-circuit defect rate.

[0005] Therefore, the improvement of the short-circuit defect rate and the ESR
In order to achieve the contradictory objective of improving the above, by changing the raw material of electrolytic paper from ordinary wood kraft pulp to softwood pulp, Manila hemp pulp, esparto pulp and other smaller pulp as described above, Attempts to produce thin, low-density and dense electrolytic paper (Japanese Patent Publication No. 61-45379, Japanese Patent Application No. 62-126622),
Attempts to add a paper strength agent to the raw material suspension or mix the heat-fusible fibers and melt them in the drying process to increase the bonding between the fibers, or mix the thermoplastic fibers and heat-treat the secondary processing Attempts have been made to increase the tensile strength by fusing at a low density and having significantly improved tensile strength in recent years, improving the short-circuit failure rate without adversely affecting the ESR of electrolytic capacitors. A method capable of improving the productivity has been developed (JP-A-8-27398).
4).

[0006]

SUMMARY OF THE INVENTION Electrolytic paper has a low density and improved tensile strength, thereby improving the short-circuit failure rate without adversely affecting the ESR of an electrolytic capacitor, thereby improving productivity. Possible conventional technology (Japanese Unexamined Patent Publication No.
273984), ethylene glycol (E
Na, K, C in the paper strength enhancer in an electrolytic solution containing G) as a main solvent or an electrolytic solution containing a large amount of water other than that.
There is a problem that cations (cations) such as a and Mg are extracted into the electrolytic solution, corroding or altering the aluminum foil to cause an increase in leakage current or a decrease in capacitance, thereby deteriorating the life characteristics. .

Further, in the past, the electrolyte used was mainly an electrolyte containing γ-butyrolactone (GBL) as a main solvent in which a paper strength enhancer was insoluble. )) Or an electrolyte containing a large amount of water besides the above. Therefore, since most of the used paper-strengthening agents are water-soluble, the cations in the paper-strengthening agent are poor in an electrolyte containing ethylene glycol (EG) as a main solvent or an electrolyte containing a large amount of water. As a result, the cations eluted into the electrolyte form hydrates on the surface of the aluminum foil, which causes a problem that the original characteristics cannot be exhibited.

Accordingly, the present invention provides a method for preparing Na,
By impregnating and applying a paper strength enhancer in which the cations of K, Ca, and Mg are reduced, the amount of cations extracted is reduced regardless of the type of the electrolyte, and the tensile strength is greatly improved at a low density. It is an object of the present invention to provide an electrolytic capacitor capable of improving the short-circuit failure rate without adversely affecting the ESR of the capacitor, improving the productivity, and improving the life characteristics.

[0009]

In order to achieve the above object, the present invention provides an electrolytic capacitor having an electrolytic paper interposed between an anode foil and a cathode foil.
500 ppm or less of cations of K, Ca, and Mg in total,
Provided is an electrolytic capacitor coated with a paper strength enhancer, preferably reduced to 100 ppm or less.

Further, Na, K, Ca, Mg of the paper strength enhancer
Is 25 ppm or less. The paper strength enhancer is one or more selected from starch, vegetable gum, semi-synthetic polymer, and synthetic polymer. The paper strength enhancer is impregnated and applied to the electrolytic paper at 0.05% by weight to 5.0% by weight.

The fibers constituting the electrolytic paper are Manila hemp pulp,
One or more selected from esparto pulp, sisal pulp, and solvent-spun rayon. The density of the electrolyte sheet is ^{0.20g / cm 3 ~0.85g / cm 3} , a thickness of the 20Myuemu～90myuemu. The tensile strength of the electrolytic paper is 1.1 kg / 15 mm or more.

According to the present invention, a total of 500 ppm of cations of Na, K, Ca and Mg is added to the electrolytic paper after papermaking.
By impregnating and applying the reduced paper strength agent below,
It has low density and significantly improved tensile strength. It can improve the short-circuit failure rate without adversely affecting the ESR of the electrolytic capacitor, improve the productivity, and improve the life characteristics. An electrolytic capacitor can be provided.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the electrolytic capacitor according to the present invention will be described. The basic means of the present invention is to provide an electrolytic capacitor having an electrolytic paper interposed between an anode foil and a cathode foil, wherein Na, K, C
a, Mg cations are impregnated and coated with a paper strength enhancer in which the total amount of cations is reduced to 500 ppm or less, preferably 100 ppm or less, and the content of each cation is 25 ppm.
The present invention is characterized by using a reduced paper strength enhancer.

Examples of the paper strength enhancer applied to the electrolytic paper include plant gums such as guar gum, locust bean gum, tragacanth gum, starches such as corn starch, potato starch, wheat starch, tapioca starch, dialdehyde starch,
Semi-synthetic polymers such as cationic starch, methylcellulose and carboxymethylcellulose, and synthetic polymers such as polyacrylamide resin, polyethyleneimine resin and urea resin are used. In particular, dialdehyde starch, polyacrylamide resin, and polyethyleneimine resin are preferably used due to factors such as availability, economy, strength-enhancing effect, and workability. In addition, when the paper strength enhancer to be used contains an anion (anion) such as chloride ion excessively,
It is necessary to reduce anions by reducing anions in the production stage or by using an ion exchange resin in an aqueous solution.

The paper-strengthening agents used are Na, K, Ca,
The total amount of Mg cations is 500 ppm or less, preferably 100 ppm or less, and the individual cations are reduced to 25 ppm or less. There is a method of removing cations with a resin or the like. The paper strength enhancer used is not limited to those described above as long as the cations of Na, K, Ca, and Mg are reduced, and an appropriate one can be used. Further, the paper strength enhancer may be any low-cation product that meets the above conditions, and the method of reducing the cation is ion-exchange resin, electrodialysis,
Any method such as an ultrafiltration method and a reverse osmosis method may be used.

Further, the paper strength enhancer is added to the electrolytic paper by 0.0
By impregnating and coating in the range of 5% by weight to 5.0% by weight, it is possible to improve the short-circuit defect rate without adversely affecting the desired impedance characteristics and to perform electrolysis using ethylene glycol (EG) as a main solvent. The life characteristics can be improved in a liquid or an electrolytic solution containing a large amount of water.

As the coated paper to be impregnated and coated with the paper strength enhancer, a circular mesh paper machine having a single circular mesh bat portion (circular mesh single paper) and a circular mesh having two or more multiple circular mesh bat portions are used. Multi-layer combination paper machine (Circular double paper, triple paper, multiple paper), or Fourdrinier combination paper machine with one or more circular mesh portions and one long mesh portion (Fourd mesh circular multiple paper), etc. The electrolytic paper in a dry paper state produced by a suitable paper machine is used.

After the paper making, the dried electrolytic paper is impregnated with a paper strength enhancer diluted according to the target strength. Coating methods include direct roll coater, dip coater,
After being immersed in a coating method such as a spray coater or kiss roll coater, the liquid is adjusted and the thickness is adjusted with a press roll, and then dried by hot air drying, cylinder drying, etc., to obtain a predetermined thickness and density. Make paper. This method may be secondary processing, but if it is an online method in which these facilities are installed after papermaking, mass production can be performed without impairing productivity. According to this method, for example, a fixing aid containing a large amount of impurities such as a sulfuric acid band or polyaluminum chloride is not required as in the case of internally adding an anionic paper strength enhancer to a raw material suspension, and an anion, a nonion, and a cation can be eliminated. Any paper strength agent can be used.

Depending on the method of impregnation coating, press weighting, drying, and these conditions, it is possible to adjust the thickness and density of the electrolytic paper after paper making. It is possible to manufacture the ultra-low density electrolytic paper that has been used. In addition, it prevents paper breakage in the process due to the increase in tensile strength and firmly fixes the fine fibers in the paper, thus increasing the surface strength of the electrolytic paper. The generation of paper dust due to falling off can be prevented, the frequency of line cleaning can be reduced, and the work in the process can be smoothed.

The density of the obtained electrolytic paper is 0.20 g / cm.
^{3 to} 0.85 g / cm ³ and a thickness of 20 μm to 90 μm. The tensile strength is set to 1.1 kg / 15 mm or more. An anode obtained by tabulating the electrolytic paper thus obtained,
After being wound and formed between an aluminum foil and a cathode aluminum foil, a liquid electrolyte is impregnated and sealed to produce an electrolytic capacitor.

Hereinafter, various examples, comparative examples, and conventional examples according to the present invention will be described. The electrolytic capacitor is interposed between the anode foil and the cathode foil with tabs so that the two electrodes do not come into contact with each other, wound up to form an electrolytic capacitor element, and then impregnated with a predetermined electrolyte to form a case. It was sealed and aged to obtain an aluminum dry capacitor of 50 WV, 220 μF. Comparative Example 1 corresponds to Examples 1 and 2.

Example 1 70% by weight of esparto pulp
Using a mixed raw material of pulp and Manila hemp pulp 30% by weight
After beating to 640 cc with F, the anion impurities are removed at the production stage by an on-machine type direct roll coater, and the total amount of cations is reduced to 25%.
A diluted solution of polyacrylamide resin reduced to less than ppm is immersed, adjusted to remove polyacrylamide by 3.0% by weight with respect to paper by a press roll, and dried by a cylinder dryer to a thickness of 50.1 μm. , Density 0.2
Circular mesh triple paper having 99 g / cm ³ and a tensile strength of 1.3 kg / 15 mm was obtained. Next, 50 WV, 220
A μF electrolytic capacitor was manufactured.

Example 2 70% by weight of esparto pulp
Using a mixed raw material of pulp and Manila hemp pulp 30% by weight
After being beaten to 640 cc with F to form a mesh triple paper, anionic impurities were removed at the manufacturing stage using an off-machine direct roll coater, and the total amount of cations purified with an ion exchange resin was reduced to 25 ppm or less. After being immersed in a dilute solution of polyacrylamide resin and adjusted to remove polyacrylamide to 3.0% by weight of paper with a press roll, the mixture was dried with a cylinder drier to a thickness of 5%.
0.0 μm, density 0.301 g / cm ³ , tensile strength 1.
A round mesh triple paper of 2 kg / 15 mm was obtained. Next, a 50 WV, 220 μF electrolytic capacitor was manufactured using this electrolytic paper.

Example 3 60% by weight of esparto pulp
Using raw materials of 40% by weight of Manila hemp pulp
After being beaten to 590 cc with F to form a triple-mesh paper, anionic impurities were removed at the manufacturing stage by an on-machine type direct roll coater, and further purified by an ion exchange resin to reduce the total amount of cations to 25 ppm or less. A diluted solution of polyethyleneimine resin is immersed in the solution, adjusted by a press roll to remove polyethyleneimine to 3.0% by weight of the paper, and dried by a cylinder drier to obtain a thickness of 40.
2 μm, density 0.369 g / cm ³ , tensile strength 2.1 k
g / 15 mm round mesh triple paper was obtained. Then use this electrolytic paper for 5
A 0 WV, 220 μF electrolytic capacitor was manufactured.

[Example 4] CS using a mixed raw material of 70% by weight of Manila hemp pulp and 30% by weight of esparto pulp
After being beaten to 660 cc with F to make a double-mesh double paper, the on-machine type direct roll coater was used to purify it with an ion exchange resin to remove anionic impurities and further reduce the total amount of cations to 100 ppm or less. A diluted solution of starch is immersed in the solution, and the pressure of the dialdehyde starch is adjusted to 3.0% by weight of the paper with a press roll.
m, density 0.352 g / cm ³ , tensile strength 2.6 kg /
A 15 mm circular mesh triple paper was obtained. Next, 50W with this electrolytic paper
V, 220 μF electrolytic capacitor was manufactured.

Example 5 Manila hemp pulp 100% by weight
After beaten to 420cc with CSF using CSF to make a single-mesh net paper, with an on-machine type direct roll coater,
Purification with ion exchange resin to remove anionic impurities,
Further, a dilute solution of polyethyleneimine in which the total amount of cations has been reduced to 25 ppm or less is immersed, and dewatering is adjusted with a press roll so that the polyethyleneimine becomes 3.0% by weight with respect to the paper. 29.
8 μm, density 0.612 g / cm ³ , tensile strength 5.6 k
g / 15 mm round mesh single paper was obtained. Then use this electrolytic paper for 5
A 0 WV, 220 μF electrolytic capacitor was manufactured.

Example 6 Organic Solvent Spun Rayon 100
CSF was used to beaten to 240 cc with CSF to obtain single-mesh net paper, then an on-machine direct roll coater was used to remove anionic impurities at the production stage and purified with an ion exchange resin to reduce the total amount of cations. A diluted solution of polyacrylamide resin reduced to 25 ppm or less is immersed, adjusted to remove polyacrylamide by 3.0% by weight with respect to paper by a press roll, and dried by a cylinder drier to obtain a thickness of 68.0 μm. , Density 0.235 g / cm ³ ,
Circular mesh single paper with a tensile strength of 1.4 kg / 15 mm was obtained. Next, a 50 WV, 220 μF electrolytic capacitor was manufactured using this electrolytic paper.

Example 7 Organic Solvent Spun Rayon 100
CSF was used to beaten to 240 cc with CSF to obtain single-mesh net paper, then an on-machine direct roll coater was used to remove anionic impurities at the production stage and purified with an ion exchange resin to reduce the total amount of cations. After diluting a diluted solution of polyacrylamide resin and dialdehyde starch reduced to 500 ppm or less, and adjusting the pressure with a press roll, the polyacrylamide resin and dialdehyde starch are adjusted to a total of 3.0% by weight of the paper. Dry with a drier, thickness 69.3μm, density 0.233g / c
A circular mesh single paper having m ³ and a tensile strength of 1.4 kg / 15 mm was obtained. Next, a 50 WV, 220 μF electrolytic capacitor was manufactured using this electrolytic paper.

Comparative Example 1 70% by weight of esparto pulp
Using a mixed raw material of pulp and Manila hemp pulp 30% by weight
Beat to 640cc with F, thickness 49.1μm, density
0.320 g / cm ³, Tensile strength 0.6kg / 15mm
Was obtained. Next, 50WV, 22
A 0 μF electrolytic capacitor was manufactured.

[Conventional example 1] Espart pulp 70% by weight
Using a mixed raw material of pulp and Manila hemp pulp 30% by weight
After beating to 640 cc with F, a dilute solution of polyacrylamide resin from which anionic impurities have been removed at the manufacturing stage is immersed in an on-machine type direct roll coater, and the polyacrylamide is converted to paper with a press roll. Liquid was adjusted so as to be 3.0% by weight, and then dried with a cylinder drier to obtain a thickness of 49.6 μm and a density of 0.30%.
Circular triple paper having 4 g / cm ³ and a tensile strength of 1.2 kg / 15 mm was obtained. Next, a 50 WV, 220 μF electrolytic capacitor was manufactured using this electrolytic paper.

[Conventional Example 2] Espart pulp 60% by weight
Using raw materials of 40% by weight of Manila hemp pulp
After beating to 590 cc with F, a dilute solution of polyethyleneimine resin from which anionic impurities have been removed at the manufacturing stage is immersed in an on-machine type direct roll coater, and the polyethyleneimine paper is pressed with a press roll. The liquid was adjusted so as to have a concentration of 3.0% by weight and dried with a cylinder drier to obtain a thickness of 40.1 μm and a density of 0.37%.
Circular mesh triple paper having 1 g / cm ³ and a tensile strength of 2.1 kg / 15 mm was obtained. Next, a 50 WV, 220 μF electrolytic capacitor was manufactured using this electrolytic paper.

[Conventional Example 3] CS using a mixed raw material of 70% by weight of Manila hemp pulp and 30% by weight of esparto pulp
After beating to 660 cc with F, a dilute solution of dialdehyde starch purified by ion-exchange resin to remove anionic impurities was immersed in an on-machine type direct roll coater, and then press rolled. After adjusting the dewatering so that the dialdehyde starch becomes 3.0% by weight with respect to the paper, it was dried with a cylinder dryer and had a thickness of 49.9 μm.
m, density 0.350 g / cm ³ , tensile strength 2.7 kg /
A 15 mm circular mesh triple paper was obtained. Next, 50W with this electrolytic paper
V, 220 μF electrolytic capacitor was manufactured.

[Conventional Example 4] Manila hemp pulp 100% by weight
After beaten to 420cc with CSF using CSF to make a single-mesh net paper, with an on-machine type direct roll coater,
A dilute solution of polyethyleneimine purified from an ion exchange resin to remove anionic impurities is immersed in the solution, adjusted to remove polyethyleneimine by 3.0% by weight with respect to paper by a press roll, and dried by a cylinder dryer. And thickness 3
0.7 μm, density 0.593 g / cm ³ , tensile strength 5.
5 kg / 15 mm single-mesh net paper was obtained. Next, a 50 WV, 220 μF electrolytic capacitor was manufactured using this electrolytic paper.

[Conventional example 5] Organic solvent spun rayon 100
After being beaten to 240 cc with CSF using the weight percent to form a single-mesh net, a dilute solution of polyacrylamide resin from which anionic impurities have been removed at the manufacturing stage is immersed in an on-machine direct roll coater, and pressed. After adjusting the dewatering so that the polyacrylamide becomes 3.0% by weight with respect to the paper with a roll, it was dried with a cylinder dryer to a thickness of 70.
6 μm, density 0.231 g / cm ³ , tensile strength 1.4 k
g / 15 mm round mesh single paper was obtained. Then use this electrolytic paper for 5
A 0 WV, 220 μF electrolytic capacitor was manufactured.

[Conventional example 6] Organic solvent spun rayon 100
CSF was beaten to 240 cc with CSF to obtain single-mesh net paper, and then a dilute starch solution of polyacrylamide resin and dialdehyde starch from which anionic impurities had been removed at the production stage using an on-machine direct roll coater. After immersion, the polyacrylamide resin and dialdehyde starch were adjusted to a total weight of 3.0% by weight with respect to the paper with a press roll, followed by drying with a cylinder drier.
9.8 μm, density 0.230 g / cm ³ , tensile strength 1.
5 kg / 15 mm single-mesh net paper was obtained. Next, a 50 WV, 220 μF electrolytic capacitor was manufactured using this electrolytic paper.

The evaluation method of the electrolytic paper is as follows. First, the thickness, density and tensile strength of the electrolytic paper were measured according to JIS C2301.
(Electrolytic capacitor paper). The airtightness of the electrolytic paper was measured with a B-type tester (Gurley densometer) in accordance with the section of “12.1 Airtightness” specified in JIS C2111 (electrical insulating paper test method). However, an adapter having a hole portion of 6 mmφ was used. Electrolytic paper having an air density of 1 second or less was measured on five sheets and converted to one sheet.

The amount of paper dust generated is determined by fixing two cutter blades at an interval of 5 cm at the center of a tester provided with unwinding and winding. 1
The electrolytic paper cut into a record roll with a width of 8 mm was set on the unwinding side, pulled out with a tension of 0.5 kg, moved to the winding side of 1000 m at a speed of 10 m / min while rubbing on the cutter blade, and dropped off during this. Measure the amount of paper dust. The average of four measurements was displayed. Cation analysis method is paper strength enhancer 2
0 g ± 0.1 g was extracted with 200 ml of 0.1 mol / l aqueous solution of hydrochloric acid at room temperature for 1 hour, and this extract was analyzed by atomic absorption spectrometry.

The evaluation method of the electrolytic capacitor is as follows. First, the short-circuit failure rate is determined by winding the electrolytic paper together with the anode foil and the cathode foil to form an electrolytic capacitor element.
Conduction due to a short circuit between the two electrodes was confirmed with a tester without impregnating the electrolyte. The short-circuit defect rate was inspected for approximately 1000 elements, and the ratio of the short-circuit element to the total number of elements was defined as the short-circuit defect rate.

ESR (Equivalent Series Resistance) of Electrolytic Capacitor
Was measured by an LCR meter at 20 ° C. and a frequency of 1000 HZ. The capacitance was measured by an LCR meter at 20 ° C. and a frequency of 1000 HZ. The leakage current was measured at 20 ° C. by measuring the current (leakage current) flowing through the electrolytic capacitor after applying the rated DC voltage for 1 minute. The aging test was performed by continuously applying a rated DC voltage for 4,000 hours in a constant temperature layer at 85 ° C.
SR, capacitance, and leakage current were measured. Tables 1 and 2 show Examples 1 to 7, Comparative Example 1 and Conventional Examples 1 to 6 relating to the above items.
2 shows the measurement results.

[0040]

[Table 1]

[0041]

[Table 2]

As shown in the results of Tables 1 and 2, electrolytic paper impregnated and coated with a paper strength enhancer whose cation was reduced by an ion exchange resin or the like in an aqueous solution or in an aqueous solution did not remove the cation. It has the same characteristics (tensile strength, short-circuit defect rate, ESR, paper dust generation) as electrolytic paper impregnated with the agent. For example, in Example 1, a mixed material of 70% by weight of esparto pulp and 30% by weight of manila hemp pulp was impregnated and coated with a diluted solution of polyacrylamide resin in which cations were reduced to 10 ppm by an on-machine method. 50.1μm, density 0.299g / c
It is a circular mesh triple paper with m ³ and a tensile strength of 1.3 kg / 15 mm. In Example 2, a mixed material of 70% by weight of esparto pulp and 30% by weight of manila hemp pulp was impregnated with a diluted solution of a polyacrylamide resin in which cations were reduced to 10 ppm by an off-machine method to obtain a thickness of 50. 0
μm, density 0.301 g / cm ³ , tensile strength 1.2 kg
/ 15 mm circular mesh triple paper. Conventional Example 1 is a circle having substantially the same thickness, the same density, and the same tensile strength manufactured by impregnating and applying a diluted solution of polyacrylamide resin in which only anionic impurities have been removed at the manufacturing stage by the same raw material and the same method as in Example 1. It is net triple paper.

The first and second embodiments have the same characteristics (tensile strength, short-circuit defect rate, ESR, and amount of paper dust) as those of the first embodiment. Almost the same results were obtained in Example 3, Conventional Example 2, Example 4, Conventional Example 3, Example 5, Conventional Example 4, Example 6, Conventional Example 5, and Example 7, and Conventional Example 6.

Further, the electrolytic paper impregnated and coated with a paper strength enhancer whose cations have been reduced by the ion exchange resin or the like in the production stage or in an aqueous solution is similar to the electrolytic paper impregnated and coated with a paper strength enhancer from which cations have not been removed. The conventional technology (Japanese Patent Laid-Open No. 8-27398) is applied by impregnating and applying a paper strength enhancer.
The same effect as 4) is obtained.

Comparative Example 1 is a triple-mesh paper made of the same raw materials as in Examples 1 and 2 and Conventional Example 1 but not coated with a paper strength enhancer. In Examples 1 and 2, it was found that the short-circuit defect rate was remarkably improved without affecting the ESR by improving the tensile strength as compared with Comparative Example 1.

Table 3 is a list summarizing the initial values and the measured values after 4000 hours of the 85 ° C. load test for the capacitance, ESR, and leakage current of each embodiment, conventional example, and comparative example.

[0047]

[Table 3]

As shown in Table 3, by reducing the amount of cations in the electrolytic paper, it was possible to maintain substantially the same characteristics as the initial characteristics even after the aging test. For example, Examples 1 and 2 use electrolytic paper impregnated with a paper strength enhancer in which cations in the paper strength enhancer have been reduced to 10 ppm or less. Conventional example 1 uses electrolytic paper impregnated with a paper strength enhancer containing only about 2000 ppm of a cation by reducing only anions. Comparative Example 1 uses electrolytic paper not impregnated with a paper strength enhancer.

In Examples 1 and 2, similar to Comparative Example 1, even after the successive change test, good characteristics were maintained without much difference from the initial characteristics. On the other hand, in Conventional Example 1, the leakage current increases and the capacitance decreases. The same results were obtained for the third embodiment, the second conventional example, the fifth embodiment, the fourth conventional example, and the sixth embodiment and the fifth conventional example.

Example 4 shows that the cation in the paper strength agent was 10
It uses electrolytic paper impregnated with a paper strength enhancer reduced to 0 ppm or less. Conventional example 3 uses electrolytic paper impregnated with a paper strength enhancer containing only about 3000 ppm of cations by reducing only anions. Examples 1 and 2
And Conventional Example 1 have similar results.

Further, Example 7 uses electrolytic paper impregnated with a paper strength enhancer in which the cations in the paper strength enhancer have been reduced to 500 ppm or less. Conventional example 6 uses electrolytic paper impregnated and coated with a paper strength enhancer containing only about 6000 ppm of cations by reducing only anions. Example 7
, The leakage current and the capacity are slightly deteriorated, but are significantly improved as compared with the conventional example 6.

As shown in the results of Tables 1, 2, and 3, cations of the paper strength enhancer, in particular, Na, K, Ca, and Mg were added in a total amount of 5%.
By reducing the content to 00 ppm or less, preferably 100 ppm or less, even if the paper strength enhancer is impregnated and applied to the electrolytic paper, there is no adverse effect on the ESR due to the improvement in tensile strength as in the conventional case, and the short-circuit defect rate is also improved. It is apparent that the life characteristics in an electrolytic solution containing ethylene glycol (EG) as a main solvent or an electrolytic solution containing a large amount of water other than that are improved.

[0053]

As described in detail above, the electrolytic capacitor according to the present invention is capable of forming Na, K, C
a, Mg cation reduced to a total amount of 500 ppm or less, characterized in that it is impregnated and coated with a paper strength enhancer. Specifically, vegetable gums and starches whose cations are reduced to a level that does not corrode or alter aluminum foil The following effects can be obtained by impregnating and coating an electrolytic paper with a dilute solution of a paper strength enhancer such as a synthetic polymer, a semi-synthetic polymer, and a synthetic polymer.

That is, the electrolytic capacitor obtained by the conventional means contains Na, K, Ca,
Although cations such as Mg are extracted and corrode or alter the aluminum foil, there is a problem that an increase in leakage current or a decrease in capacitance is caused. On the other hand, electrolytic paper after paper making as in the present invention. By impregnating and applying a paper strength enhancer in which the total amount of the cations was reduced to 500 ppm or less,
The short-circuit failure rate can be significantly improved without adversely affecting R. Further, in order not to increase the cations in the electrolytic paper even after the impregnation application of the paper strength enhancer, even in the case of the electrolytic solution containing ethylene glycol as the main solvent, the cations are not extraly extracted into the electrolytic solution, The life characteristics can be greatly improved.

Further, since the conventionally used electrolyte is an electrolyte containing GBL as a main solvent in which the paper strength enhancer is insoluble,
The cation in the paper strength agent is easily eluted by the electrolytic solution, and the eluted cation forms a hydrate on the surface of the aluminum foil to adversely affect the characteristics of the capacitor. Regardless of the type of liquid, the amount of cations extracted is reduced to improve the tensile strength at low density,
In addition, it is possible to provide an electrolytic capacitor which improves the productivity by improving the short-circuit defect rate without adversely affecting the ESR of the electrolytic capacitor, and has an improved life characteristic.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoki Fujimoto 648, Hirookakami, Haruno-cho, Agawa-gun, Kochi Japan Nippon Advanced Paper Industries Co., Ltd. Within Japan Advanced Paper Industry Co., Ltd.

Claims (11)

[Claims] 1. An electrolytic capacitor having an electrolytic paper interposed between an anode foil and a cathode foil, wherein N
An electrolytic capacitor characterized by being coated by impregnation with a paper strength enhancer in which the total amount of cations of a, K, Ca, and Mg is reduced to 500 ppm or less. 2. Na, K, Ca, M is added to the electrolytic paper after paper making.
The electrolytic capacitor according to claim 1, wherein a paper strength enhancer in which the total amount of cations is reduced to 100 ppm or less is impregnated. 3. The electrolytic capacitor according to claim 1, wherein the Na content of the paper strength enhancer is 25 ppm or less. 4. The electrolytic capacitor according to claim 1, wherein the K content of the paper strength enhancer is 25 ppm or less. 5. The electrolytic capacitor according to claim 1, wherein the Ca content of the paper strength enhancer is 25 ppm or less. 6. The electrolytic capacitor according to claim 1, wherein the Mg content of the paper strength enhancer is 25 ppm or less. 7. The paper strength enhancer according to claim 1, 2, 3, 4, 5 or 6, wherein the paper strength enhancer is one or more selected from starch, vegetable gum, semi-synthetic polymer, and synthetic polymer. Electrolytic capacitors. 8. The electrolytic paper according to claim 1, wherein the paper strength enhancer is impregnated with 0.05 to 5.0% by weight.
8. The electrolytic capacitor according to 4, 5, 6, or 7. 9. The fiber constituting the electrolytic paper is one or more selected from the group consisting of manila hemp pulp, esparto pulp, sisal pulp, and solvent-spun rayon.
9. The electrolytic capacitor according to 2, 3, 4, 5, 6, 7, or 8. 10. The density of the electrolytic paper is 0.20 g / cm ³ or more.
0.85 g / cm ³ and a thickness of 20 μm to 90 μm
The electrolytic capacitor according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9. 11. The tensile strength of electrolytic paper is 1.1 kg / 15.
1, 2, 3, 4, 5, 6, 7,
The electrolytic capacitor according to 8, 9, or 10.