JP6442162B2 - Electrolytic capacitor - Google Patents

Description

  The present invention relates to an electrolytic capacitor having a conductive solid layer and an electrolytic solution.

  A conventional electrolytic capacitor is disclosed in Patent Document 1. In this electrolytic capacitor, a capacitor element in which an anode foil on which a dielectric film is formed and a counter cathode foil are wound via a separator is housed in an outer case. The capacitor element has a conductive solid layer made of a conductive polymer inside and is impregnated with an electrolytic solution. The outer case containing the capacitor element is sealed with rubber packing. In addition, polyoxyalkylene such as polyethylene glycol is added to the electrolytic solution.

  In the conventional electrolytic capacitor, by adding polyoxyalkylene such as polyethylene glycol to the electrolytic solution, the withstand voltage can be improved and the ESR (equivalent series resistance) can be reduced. As a result, the deterioration of the characteristics of the electrolytic capacitor in a high temperature environment can be suppressed, and the life can be extended.

International publication 2011/099261 pamphlet

  However, according to the conventional electrolytic capacitor described above, when the electrolytic capacitor is mounted on the substrate, the outer case may expand due to heating during reflow or the sealing packing may protrude. As a result, there is a problem that an electrolytic capacitor is poorly attached and the yield at the time of mounting is lowered.

  In addition, the conventional electrolytic capacitor has a problem that the ESR and loss angle tangent increase greatly when used for a long time, and the life of the electrolytic capacitor is shortened.

  An object of the present invention is to provide an electrolytic capacitor capable of improving the yield at the time of mounting and extending the life.

In order to achieve the above object, the electrolytic capacitor of the present invention is an electrolytic capacitor in which an electrolytic solution is impregnated with a capacitor element in which a conductive solid layer is disposed between a dielectric film formed on an anode and a cathode. It is characterized by adding polyoxyalkylene having the structure of the following formula (Formula 1) to the liquid.

  According to this configuration, by adding the polyoxyalkylene having the structure represented by (Chemical Formula 1), expansion of the outer case due to heating during reflow is suppressed.

According to the present invention, in the electrolytic capacitor configured as described above, the polyoxyalkylene added to the electrolytic solution has a structure represented by the following formula (Formula 2).

  According to the present invention, in the electrolytic capacitor having the above-described configuration, the ratio of polyoxyethylene in the polyoxyalkylene added to the electrolytic solution is 30 wt% or more and 40 wt% or less.

  In the electrolytic capacitor having the above-described configuration, the polyoxyalkylene added to the electrolytic solution has a design molecular weight of 3000 or more and 4000 or less.

  According to the present invention, polyoxyalkylene having a structure represented by (Chemical Formula 1) is added to the electrolytic solution impregnated in the capacitor element having the conductive solid layer. Thereby, the expansion | swelling of the electrolytic capacitor at the time of reflow can be suppressed. Further, increase in ESR and loss angle tangent during long-term use of the electrolytic capacitor can be reduced. Therefore, it is possible to improve the yield when mounting the electrolytic capacitor and to extend the life.

Side surface sectional drawing which shows the electrolytic capacitor of embodiment of this invention The perspective view which shows the capacitor | condenser element of the electrolytic capacitor of embodiment of this invention Process drawing which shows the manufacturing process of the electrolytic capacitor of embodiment of this invention The graph which shows the change of the capacity | capacitance change rate by the high temperature load test of the electrolytic capacitor which concerns on Example 3 of this invention The graph which shows the change of the capacity | capacitance change rate by the high temperature load test of the electrolytic capacitor which concerns on Example 5 of this invention The graph which shows the change of the capacity | capacitance change rate by the high temperature load test of the electrolytic capacitor which concerns on Example 6 of this invention The graph which shows the change of the capacity | capacitance change rate by the high temperature load test of the electrolytic capacitor which concerns on Example 7 of this invention The graph which shows the change of ESR by the high temperature load test of the electrolytic capacitor which concerns on Example 3 of this invention The graph which shows the change of ESR by the high temperature load test of the electrolytic capacitor which concerns on Example 5 of this invention The graph which shows the change of ESR by the high temperature load test of the electrolytic capacitor which concerns on Example 6 of this invention The graph which shows the change of ESR by the high temperature load test of the electrolytic capacitor which concerns on Example 7 of this invention The graph which shows the change of ESR by the high temperature load test of the electrolytic capacitor which concerns on Example 3, 5, 6, 7 of this invention The graph which shows the change of the tangent of the loss angle by the high temperature load test of the electrolytic capacitor which concerns on Example 3 of this invention The graph which shows the change of the tangent of the loss angle by the high temperature load test of the electrolytic capacitor which concerns on Example 5 of this invention The graph which shows the change of the tangent of the loss angle by the high temperature load test of the electrolytic capacitor which concerns on Example 6 of this invention The graph which shows the change of the tangent of the loss angle by the high temperature load test of the electrolytic capacitor which concerns on Example 7 of this invention

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing an electrolytic capacitor according to an embodiment. The electrolytic capacitor 1 has a capacitor element 10 housed in an outer case 2 made of bottomed cylindrical aluminum having an opening 2a on one surface. The opening 2 a of the outer case 2 is sealed with a rubber packing 3.

  FIG. 2 is an exploded perspective view of the capacitor element 10. The capacitor element 10 is formed by winding an anode foil 11 and a counter cathode foil 12 through a separator 13 such as electrolytic paper. The terminal end of the anode foil 11 or the counter cathode foil 12 is fixed by a winding tape 14. The anode foil 11 is made of a valve metal such as aluminum, tantalum, niobium or titanium, and a dielectric film is formed on the surface. The counter cathode foil 12 is opposed to the anode foil 11 through the separator 13 and is formed of aluminum or the like.

  Lead wires 21 and 22 are attached to the anode foil 11 and the counter cathode foil 12 via lead tabs 21a and 22a, respectively. Lead terminals 21 and 22 form anode and cathode terminal portions.

  A conductive solid layer is provided on the surface of the dielectric film of the anode foil 11 and the surface of the counter cathode foil 12 in the capacitor element 10. The conductive solid layer is formed of manganese dioxide, 7,7,8,8-tetracyanoquinodimethane, a conductive polymer, or the like. As a conductive polymer that forms the conductive solid layer, polythiophene, polypyrrole, or a derivative thereof can be used. In particular, polyethylenedioxythiophene is more desirable because of its high electrical conductivity.

  Capacitor element 10 is impregnated with an electrolytic solution. The electrolytic solution is formed by dissolving an organic acid or an organic acid salt in a polar solvent. The polar solvent of the electrolytic solution has a boiling point higher than the operating temperature range of the electrolytic capacitor 1 and a lower melting point. For example, a polar solvent containing γ-butyrolactone as a main component can be used for a use temperature range of −30 ° C. to 150 ° C.

  Organic acid salts contained in the electrolyte include triethylamine borodisalicylate, trimethylamine borodisalicylate, trimethylamine borodiglycolate, ethyldimethylamine phthalate, mono 1,2,3,4-tetramethylimidazolinium phthalate, phthalate The acid mono 1,3-dimethyl-2-ethylimidazolinium or a mixture thereof can be used.

In addition, polyoxyalkylene having a structure represented by the following formula (Formula 1) is added to the electrolytic solution. This polyoxyalkylene comprises a block copolymer of polyoxypropylene (PPO), polyoxyethylene (PEO) and polyoxypropylene (PPO).

Specific examples of the block copolymer include polyoxyalkylene (HO-PPO-PEO-PPO-H type polyoxyalkylene) having a structure represented by the following formula (Formula 2).

  In the electrolytic capacitor 1 in which HO-PPO-PEO-PPO-H type polyoxyalkylene is added to the electrolytic solution, expansion during reflow is suppressed as compared with an electrolytic capacitor in which polyethylene glycol (PEG) is added to the electrolytic solution. Thereby, the attachment failure of the electrolytic capacitor 1 can be prevented, and the yield fall at the time of mounting can be suppressed.

  In addition, the electrolytic capacitor 1 in which HO-PPO-PEO-PPO-H type polyoxyalkylene is added to the electrolytic solution has an ESR and a loss angle when used for a long time as compared with an electrolytic capacitor in which polyethylene glycol (PEG) is added to the electrolytic solution. The increase in the tangent (tan δ) of the material can be suppressed and the life can be extended. Further, polyoxyalkylene (HO-PEO-PPO-) comprising a block copolymer of polyoxyethylene (PEO), polyoxypropylene (PPO) and polyoxyethylene (PEO) having a structure represented by the following formula (Chemical Formula 3): Compared with PEO-H type polyoxyalkylene), it is possible to suppress an increase in ESR and loss angle tangent (tan δ) when the electrolytic capacitor 1 is used for a long time.

  Further, the ratio of polyoxyethylene (PEO) contained in the polyoxyalkylene having the structure represented by (Chemical Formula 1) is preferably 10% by weight to 40% by weight, and more preferably 30% by weight to 40% by weight. By setting the ratio of polyoxyethylene (PEO) to 30% by weight or more and 40% by weight or less, it is possible to further suppress an increase in ESR during long-term use. The average molecular weight of the polyoxyalkylene having the structure represented by (Chemical Formula 1) is preferably 1000 or more and 4000 or less, and more preferably 3000 or more and 4000 or less. By setting the average molecular weight to 3000 or more and 4000 or less, it is possible to further suppress an increase in ESR during long-term use.

  FIG. 3 is a process diagram showing the manufacturing process of the electrolytic capacitor 1. The electrolytic capacitor 1 is formed by sequentially performing an element forming process, an assembly process, a cleaning process, an aging process, and an inspection process. Moreover, the element formation process which forms the capacitor | condenser element 10 performs an anodizing process, a terminal formation process, a winding process, an element formation process, an electroconductive solid layer formation process, and an electrolyte solution impregnation process in order.

  In the anodizing step, first, the surface of the anode foil 11 made of a valve metal is roughened by etching. The anode foil 11 subjected to the etching process is anodized in the chemical conversion solution, and a dielectric film made of an oxide film is formed on the surface.

  In the terminal forming step, the lead tabs 21a and 22a of the lead wires 21 and 22 are joined to one end of the anode foil 11 and the counter cathode foil 12 by caulking.

  In the winding process, the anode foil 11 and the counter cathode foil 12 are wound through the separator 13, and the terminal ends are fixed by the winding tape 14. Thereby, the element body of the capacitor element 10 is formed.

  In the element forming step, the capacitor element 10 is immersed in the forming solution and anodized. Thereby, the dielectric film missing in the winding process or the like is repaired.

  In the conductive solid layer forming step, first, the capacitor element 10 is immersed in a dispersion liquid in which conductive solid particles or aggregates thereof are dispersed in a dispersion medium, and the capacitor element 10 is impregnated with the dispersion liquid. Next, the capacitor element 10 is dried at a high temperature, and the dispersion medium is removed to form a conductive solid layer.

  It is desirable that the dispersion medium does not dissolve the conductive solid, and it is more desirable to use water in consideration of handling property, dispersibility of the conductive solid, and the like. For example, the capacitor element 10 can be impregnated with the dispersion liquid by immersing the capacitor element 10 in a dispersion liquid in which polyethylenedioxythiophene particles are dispersed in water under reduced pressure. At this time, you may contain a dopant agent in a dispersion medium. Further, the dispersion medium can be removed by drying the capacitor element 10 at 100 ° C. to 200 ° C., for example.

  The conductive solid layer may be formed by oxidative polymerization of a polymerizable monomer in the conductive solid layer forming step. That is, the capacitor element 10 is impregnated with a polymerizable monomer (for example, a monomer of ethylenedioxythiophene). Next, the capacitor element 10 is immersed in an oxidizing agent (for example, an ethanol solution of iron paratoluenesulfonate) to perform oxidative polymerization. Thereby, a conductive solid layer made of a conductive polymer (for example, polyethylene dioxythiophene) is formed.

  In the electrolytic solution impregnation step, the capacitor element 10 is immersed in the electrolytic solution, and the capacitor element 10 is impregnated with the electrolytic solution. As described above, an electrolyte of an organic acid or an organic acid salt is dissolved in a polar solvent such as γ-butyrolactone. The concentration of the electrolyte in the polar solvent is not particularly limited, and can be, for example, 5 to 50% by weight. In addition, the immersion time of the capacitor element 10 varies depending on the size, but may be, for example, 1 second to several hours, preferably 1 second to 5 minutes. Moreover, the immersion temperature of the capacitor element 10 is not particularly limited.

  In the assembly process, the packing 3 is attached to the opening 2 a of the outer case 2. Then, drawing processing is performed on the peripheral surface of the outer case 2 facing the packing 3, and curling processing is performed on the peripheral edge of the opening 2a. As a result, the outer case 2 containing the capacitor element 10 is sealed.

  In the cleaning process, dirt due to the electrolytic solution adhering to the outer surface of the outer case 2 is cleaned.

  In the aging process, for example, an aging process is performed at about 125 ° C. for about 1 hour while applying a rated voltage or a voltage higher than the rated voltage between the lead wires 21 and 22. Due to the aging treatment, defects in the dielectric film generated on the cut surface of the anode foil 11 and the connecting portion of the lead wire 21 are repaired.

  In the inspection process, the appearance and characteristics of the electrolytic capacitor 1 are inspected. Thereby, the electrolytic capacitor 1 is completed.

According to this embodiment, the polyoxyalkylene having the structure shown in (Chemical Formula 1) is added to the electrolytic solution impregnated in the capacitor element 10 having the conductive solid layer. Thereby, the expansion | swelling of the electrolytic capacitor 1 at the time of reflow can be suppressed. Further, the increase in ESR and tangent of loss angle when the electrolytic capacitor 1 is used for a long time can be reduced. Therefore, the yield at the time of mounting the electrolytic capacitor 1 can be improved and the life can be extended.

Further, since the polyoxyalkylene added to the electrolytic solution has the structure of the following formula (Formula 2), it is possible to easily suppress the increase in ESR and loss angle tangent (tan δ) when the electrolytic capacitor 1 is used for a long time. be able to.

  Moreover, the raise of ESR at the time of long-term use can be suppressed more by making the ratio of the polyoxyethylene in the polyoxyalkylene added to electrolyte solution into 30 to 40 weight%.

  Moreover, the raise of ESR at the time of long-term use can be suppressed more by making the design molecular weight of the polyoxyalkylene added to electrolyte solution into 3000 or more and 4000 or less.

  In the present embodiment, the electrolytic capacitor 1 is formed by winding the anode foil 11 and the counter cathode foil 12, and is an electrolytic capacitor in which a cathode layer is provided on the surface of a porous anode body via a dielectric. There may be.

  In the present embodiment, in addition to the electrolytic solution, the capacitor element 10 may be impregnated with a liquid agent that is incompatible with the polar solvent of the electrolytic solution and has a boiling point higher than that of the polar solvent. As such a liquid agent, a liquid agent mainly composed of glycerin fatty acid ester, azelaic acid bis (2-ethylhexyl), 2-octyldodecanol and the like can be used. As glycerin fatty acid ester, tetraglycerol pentaester, decaglycerol decaester, decaglycerol monoester, decaglycerol triester, hexaglycerol monoester, hexaglycerol diester, hexaglycerol triester, hexaglycerol pentaester, tetraglycerol monoester, tetra Glycerol triester or the like can be used.

  Examples and comparative examples formed for evaluating the characteristics of the electrolytic capacitor 1 of the present embodiment will be described below.

  Table 1 shows the structure of polyoxyethylene added to the electrolyte solutions of Examples 1 to 7 and Comparative Examples 1 to 7, the sample numbers (A to G) of polyoxyethylene added to the electrolyte solutions, and polyoxyalkylene. The ratio of polyoxyethylene (EO ratio), the design molecular weight of polyoxyalkylene, and the amount of additive added to the electrolyte are shown.

  The electrolytic capacitor 1 of Example 1 was a capacitor element 10 having a final dimension (outer dimension of the electrolytic capacitor 1 in a state of being housed in the outer case 2) of φ6.3 mm × H6.0 mm and a rating of 25 V-47 μF.

  Further, in the conductive solid layer forming step, the capacitor element 10 is reduced in pressure by 80 kPa at 25 ° C. for 1 minute in a dispersion liquid (concentration: 10% by mass) in which polyethylene dioxythiophene particles are dispersed in water and containing a dopant agent. Soaked under. The capacitor element 10 impregnated with the dispersion was taken out of the dispersion and dried in a drying furnace at 125 ° C. to form a conductive solid layer of polyethylene dioxythiophene.

  In the electrolytic solution impregnation step, an additive (sample NO: A) made of polyoxyalkylene is added to 200 mg of an electrolytic solution in which γ-butyrolactone and sulfolane and a solvent are dissolved and 30% borodisalicylic acid triethylamine is dissolved as an electrolyte. Soaked. Next, the capacitor element 10 was stored in the outer case 2.

  In the aging process, aging was performed at about 125 ° C. for about 1 hour while applying a voltage of 1.15 times the rated voltage to the electrolytic capacitor 1.

  Note that 10 parts by weight of the additive was added to 100 parts by weight of the electrolytic solution of the electrolytic capacitor 1. In addition, a block copolymer of polyoxypropylene (PPO), polyoxyethylene (PEO), and polyoxypropylene (PPO) having a structure represented by the above formula (Chemical Formula 2) contained in the additive (in Table 1) HO-PPO-PEO-PPO-H type). Further, the additive has an EO ratio of 30 to 40% and a designed molecular weight of 3000 to 4000.

  In the electrolytic capacitor 1 according to Example 2, 20 parts by weight of the same additive as in Example 1 was added to 100 parts by weight of the electrolytic solution. Others are the same as the first embodiment.

  In the electrolytic capacitor 1 according to Example 3, 30 parts by weight of the same additive as in Example 1 was added to 100 parts by weight of the electrolytic solution. Others are the same as the first embodiment.

  In the electrolytic capacitor 1 according to Example 4, 40 parts by weight of the same additive as in Example 1 was added to 100 parts by weight of the electrolytic solution. Others are the same as the first embodiment.

  In the electrolytic capacitor 1 according to Example 5, 30 parts by weight of an additive (sample NO: B) made of polyoxyalkylene of HO-PPO-PEO-PPO-H type was added to the electrolytic solution with respect to 100 parts by weight of the electrolytic solution. . The additive has an EO ratio of 10 to 20% and a designed molecular weight of 2000 to 3000. Others are the same as the first embodiment.

  In the electrolytic capacitor 1 according to Example 6, 30 parts by weight of an additive composed of polyoxyalkylene of HO-PPO-PEO-PPO-H type (sample NO: C) was added to 100 parts by weight of the electrolytic solution. . The additive has an EO ratio of 10 to 20% and a designed molecular weight of 2000 to 3000. Others are the same as the first embodiment.

  In the electrolytic capacitor 1 according to Example 7, 30 parts by weight of an additive (sample NO: D) made of polyoxyalkylene of HO-PPO-PEO-PPO-H type was added to 100 parts by weight of the electrolytic solution. . Further, the additive has an EO ratio of 20 to 30% and a designed molecular weight of 1000 to 2000. Others are the same as the first embodiment.

[Comparative Example 1]
In the electrolytic capacitor 1 according to Comparative Example 1, 10 parts by weight of an additive made of polyethylene glycol (PEG 200, sample NO: E) was added to 100 parts by weight of the electrolytic solution. Others are the same as the first embodiment.

[Comparative Example 2]
In the electrolytic capacitor 1 according to Comparative Example 2, 20 parts by weight of an additive made of polyethylene glycol (PEG 200, sample NO: E) was added to 100 parts by weight of the electrolytic solution. Others are the same as the first embodiment.

[Comparative Example 3]
In the electrolytic capacitor 1 according to Comparative Example 3, 30 parts by weight of an additive composed of polyethylene glycol (PEG 200, sample NO: E) was added to 100 parts by weight of the electrolytic solution. Others are the same as the first embodiment.

[Comparative Example 4]
In the electrolytic capacitor 1 according to Comparative Example 4, 40 parts by weight of an additive made of polyethylene glycol (PEG 200, sample NO: E) was added to 100 parts by weight of the electrolytic solution. Others are the same as the first embodiment.

[Comparative Example 5]
In the electrolytic capacitor 1 according to Comparative Example 5, no additive is added to the electrolytic solution. Others are the same as the first embodiment.

[Comparative Example 6]
In the electrolytic capacitor 1 according to Comparative Example 6, an additive (sample NO: F) made of polyoxyalkylene having a structure represented by the following formula (Chemical Formula 3) is added to the electrolytic solution to 100 parts by weight of the electrolytic solution of the electrolytic capacitor 1 Part by weight was added. This polyoxyalkylene is composed of a block copolymer of polyoxyethylene (PEO), polyoxypropylene (PPO), and polyoxyethylene (PEO) (referred to as HO-PEO-PPO-PEO-H type in Table 1). . The additive has an EO ratio of 10% or less and a designed molecular weight of 1000 to 2000. Others are the same as the first embodiment.

[Comparative Example 7]
In the electrolytic capacitor 1 according to Comparative Example 7, an additive (sample NO: G) made of polyoxyalkylene of HO-PEO-PPO-PEO-H type was added to the electrolytic solution as to 30 parts by weight of the electrolytic solution of the electrolytic capacitor 1. Part by weight was added. The additive has an EO ratio of 10% or less and a designed molecular weight of 1000 to 2000. Others are the same as the first embodiment.

<Evaluation of expansion of electrolytic capacitors>
The electrolytic capacitors 1 of Examples 1 to 4 and Comparative Examples 1 to 5 prepared as described above were subjected to a VPS (vapor phase soldering) test for 210 seconds at a peak temperature of 235 ° C. twice, and the electrolytic capacitors 1 before and after the test. The amount of expansion (mm) was measured from the difference in height dimension. Table 2 summarizes the ratio of the expansion amount of each electrolytic capacitor 1 to the expansion amount of Comparative Example 5.

  According to Table 2, Examples 1 to 4 in which an additive composed of HO-PPO-PEO-PPO-H type polyoxyalkylene was added to the electrolytic solution were electrolytic capacitors after the high temperature test as compared with Comparative Examples 1 to 4. The expansion of 1 is suppressed.

  Next, Table 3 shows the results of the high temperature load test of Examples 3 and 5 to 7 in which the amount of the additive in the electrolytic solution is 30 parts by weight. For comparison, Table 3 shows the results of a high-temperature load test of Comparative Examples 3, 6, and 7 in which the amount of the additive in the electrolytic solution is 30 parts by weight and Comparative Example 5 that does not include the additive. .

  The high temperature load test is performed by applying a rated voltage up to 6000 hours in a high temperature environment of 125 ° C., and the capacitance change rate (ΔC / C), ESR, and loss angle tangent (tan δ) are evaluated. Each evaluation measures and averages about 100 samples for each Example and Comparative Example. The measurement frequency of capacitance and tan δ is 120 Hz, and the measurement frequency of ESR is 100 kHz.

<Evaluation of capacitance change rate>
4 to 7 show the transition of the capacitance change rate during the high temperature load test of Examples 3 and 5 to 7, respectively, and the results of Comparative Examples 3 and 5 to 7 are shown in each figure. In these figures, the vertical axis represents the capacitance change rate (ΔC / C, unit:%), and the horizontal axis represents time (unit: Hr).

  As shown in Table 3 and FIGS. 4 to 7, in Examples 3 and 5 to 7, as compared with Comparative Example 5, a decrease in capacitance is suppressed even after a long time has elapsed. Therefore, in Examples 3 and 5 to 7, the decrease in the capacitance change rate (%) is suppressed even after the high temperature load test, and it can be seen that each example has a very long life under a high temperature environment.

<Evaluation of ESR>
8 to 11 show the transition of ESR during the high temperature load test of Examples 3 and 5 to 7, respectively, and the results of Comparative Examples 3 and 5 to 7 are shown in each figure. FIG. 12 shows the results of Examples 3 and 5 to 7 in parallel. In these figures, the vertical axis represents ESR (unit: mΩ), and the horizontal axis represents time (unit: Hr).

  As shown in Table 3 and FIGS. 8 to 11, in Examples 3 and 5 to 7, the increase in ESR after a long time has been suppressed as compared with Comparative Examples 3 and 5 to 7. Therefore, Examples 3 and 5 to 7 show that the increase in ESR is suppressed even after the high temperature load test, and it can be seen that each Example has a very long life under a high temperature environment.

  Moreover, as shown in Table 3 and FIG. 12, the ratio (EO ratio) of polyoxyethylene in the polyoxyalkylene added to the electrolytic solution is 30 wt% or more and 40 wt% or less, and the design molecular weight is 3000 or more and 4000 or less. In comparison with the electrolytic capacitor 1 according to Examples 5 to 7, the increase in ESR during long-term use is further suppressed in the electrolytic capacitor 1 according to Example 3.

  Therefore, the ratio of polyoxyalkylene added to the electrolyte (EO ratio) is set to 30% to 40% by weight and the design molecular weight is set to 3000 to 4000, thereby further suppressing the increase in ESR during long-term use. You can see that

<Evaluation of tangent of loss angle>
FIGS. 13 to 16 show the transition of loss tangent in the high temperature load test of Examples 3 and 5 to 7, respectively, and the results of Comparative Examples 3 and 5 to 7 are shown in each figure. In these figures, the vertical axis represents the tangent of loss angle (tan δ), and the horizontal axis represents time (unit: Hr).

  As shown in FIGS. 13 to 16, in Examples 3 and 5 to 7, the increase in loss tangent (tan δ) is suppressed after a long period of time compared to Comparative Examples 3 and 5 to 7. Therefore, in Examples 3 and 5 to 7, the increase in loss tangent (tan δ) is suppressed even after the high temperature load test, and it can be seen that each example has a very long life under a high temperature environment.

  The present invention can be used for an electrolytic capacitor having a conductive solid layer and an electrolytic solution.

DESCRIPTION OF SYMBOLS 1 Electrolytic capacitor 2 Exterior case 3 Packing 10 Capacitor element 11 Anode foil 12 Opposite cathode foil 13 Separator 14 Winding tape 21, 22 Lead wire 21a, 22a Lead tab

Claims (4)

In an electrolytic capacitor in which an electrolytic solution is impregnated with a capacitor element in which a conductive solid layer is disposed between a dielectric coating formed on an anode and a cathode, the block having a structure of the following formula (Formula 2) is included in the electrolytic solution. An electrolytic capacitor characterized in that polyoxyalkylene composed of a polymer is added.

2. The electrolytic capacitor according to claim 1, wherein an addition amount of the polyoxyalkylene is 10 parts by weight or more and 40 parts by weight or less with respect to 100 parts by weight of the electrolytic solution.   3. The electrolytic capacitor according to claim 1, wherein a ratio of polyoxyethylene in the polyoxyalkylene added to the electrolytic solution is 30 wt% or more and 40 wt% or less.   4. The electrolytic capacitor according to claim 1, wherein the polyoxyalkylene added to the electrolytic solution has a design molecular weight of 3000 or more and 4000 or less.

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