Capacitor

Abstract

To provide a capacitor capable of stably maintaining characteristics on a long-term basis.SOLUTION: A capacitor 1 comprises: a capacitor element 3 which retains a predetermined solution between an anode foil 5 and a cathode foil 7, wound via a separator 6; a body case 2 which is formed like a bottomed cylinder having one end closed by an end wall part 2a and having the other end provided with an opening 2b, and which houses the capacitor element 3; a liquid supply sheet 10 which is arranged between an inner surface of the body case 2 and an outer surface of the capacitor element 3; and an end-sealing body 4 for sealing the opening 2b. In the solution, an end-sealing body degradation inhibitor is dissolved in a lipophilic solvent. The liquid supply sheet 10 has an absorption part 10a which is brought into contact with the separator 6 so as to absorb the solution, and a supply part 10b which is brought into contact with the end-sealing body 4 so as to supply the solution.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a capacitor having a sealing body. [Background technology]

[0002] A conventional capacitor is disclosed in Patent Document 1. This capacitor includes a main case, a capacitor element, and a sealing body. The main case is made of metal and has a cylindrical shape with a bottom, one end of which is closed and the other end has an opening.

[0003] The capacitor element is made by winding an anode foil and a cathode foil, on which an oxide film is formed, with a separator between them, and storing them in a main case. An electrolyte is held between the anode foil and the cathode foil. Lead terminals are connected to the anode foil and the cathode foil, respectively. The opening of the main case storing the capacitor element is sealed with a sealer such as rubber, and the lead terminals penetrate the sealer and are pulled out to the outside of the main case.

[0004] In addition, when polymers such as rubber are exposed to heat or light energy in the presence of oxygen, such as in the air, it is said that this will trigger the generation of radicals, leading to a chain reaction of oxidation, which will cause a deterioration in physical properties. For this reason, antioxidants (anti-aging agents) are mixed into the sealant to suppress oxidation reactions.

[0005] Patent Documents 2 and 3 disclose capacitors having a solid electrolyte instead of an electrolytic solution. These capacitors have a main case, a capacitor element, and a sealing body similar to those of Patent Document 1. A conductive polymer, which is a solid electrolyte, is held between the anode foil and the cathode foil of the capacitor element. In a capacitor with the above configuration, the ESR can be reduced by the conductive polymer.

[0006] Moreover, the capacitor of Patent Document 3 holds a hydrophilic polymer between the anode foil and the cathode foil. The hydrophilic polymer holds moisture, and the moisture can repair defects in the oxide film formed on the anode foil. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2000-100670 A (pages 2-4, Figure 1) [Patent Document 2] JP 2016-76562 A (pages 7-16, Figure 2) [Patent Document 3] International Publication No. 2014 / 050913 (pages 9-23, Figure 2) Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, as devices incorporating capacitors become smaller and more powerful, there are more cases where capacitors are placed near motors, engines, high-speed processing semiconductor elements, and other devices that generate a lot of heat. As a result, capacitors are increasingly being used in high-temperature environments.

[0009] According to the capacitor disclosed in the above-mentioned Patent Document 1, the antioxidant mixed into the sealing body is consumed as it performs its antioxidant function, and is gradually lost. When the capacitor is used in a high-temperature environment, the sealing body rapidly deteriorates as the antioxidant disappears. This often causes the electrolyte to evaporate outside the main case, eventually resulting in a state known as "dry-up." This causes a problem in that the characteristics of the capacitor cannot be stably maintained for a long period of time.

[0010] Similarly, the capacitor disclosed in Patent Document 3 also suffers from deterioration of the sealing body when used in a high-temperature environment. As a result, the water held in the hydrophilic polymer between the anode foil and the cathode foil leaks out of the main case due to deterioration of the sealing body, making it impossible to repair the oxide film. This causes a problem in that the characteristics of the capacitor cannot be stably maintained for a long period of time.

[0011] Furthermore, if the functional liquid has a function of not only repairing the oxide film but also enhancing the characteristics of the capacitor, the leakage of the functional liquid makes it difficult to stably maintain the characteristics of the capacitor for a long period of time.

[0012] An object of the present invention is to provide a capacitor capable of maintaining stable characteristics for a long period of time. [Means for solving the problem]

[0013] In order to achieve the above object, the present invention provides a capacitor comprising a capacitor element holding a predetermined solution between an anode foil and a cathode foil wound with a separator interposed therebetween, a main body case formed into a bottomed cylindrical shape having one end closed by an end wall and an opening at the other end, for housing the capacitor element, and a sealing body for sealing the opening, wherein a liquid supply sheet that contacts the sealing body at multiple points or surfaces is provided on the sealing body side of the capacitor element, and a solution in which a sealing body deterioration inhibitor is dissolved in a lipophilic solvent is supplied to the sealing body via the liquid supply sheet.

[0014] The present invention is also characterized in that, in the capacitor having the above-mentioned configuration, the liquid supply sheet is arranged with the absorption portion facing the end wall portion, and is folded from the absorption portion and extends axially along the inner surface of the main body case.

[0015] Furthermore, the present invention is characterized in that in the capacitor having the above-mentioned structure, the liquid supply sheet is folded at both side portions from the absorbing portion to form the supply portions at both end portions.

[0016] Furthermore, the present invention is characterized in that, in the capacitor having the above-mentioned configuration, the axial width of the separator is larger than the axial widths of the anode foil and the cathode foil, and the separator protrudes toward the end wall portion further than the anode foil and the cathode foil.

[0017] Furthermore, according to the present invention, in the capacitor having the above configuration, the liquid supply sheet protrudes toward the sealing body further than the capacitor element.

[0018] Furthermore, in the capacitor of the present invention having the above-mentioned configuration, the supply portion is disposed facing the sealing member by bending the liquid supply sheet extending in the axial direction in the radial direction.

[0019] Furthermore, the present invention is characterized in that, in the capacitor having the above-described configuration, the solution supplied to the sealing body via the supply part penetrates into the sealing body, the outer surface of the sealing body is covered with a coating part in which the sealing body deterioration inhibitor is solidified by oxidation, and the solution is present inside the sealing body on the capacitor element side of the coating part.

[0020] Furthermore, the present invention is characterized in that in the capacitor having the above structure, the capacitor element holds a solid electrolyte.

[0021] Furthermore, the present invention is characterized in that in the capacitor having the above-mentioned structure, the solution comprises an electrolytic solution in which the sealing body deterioration inhibitor and an electrolyte are dissolved in the lipophilic solvent.

[0022] Furthermore, the present invention is characterized in that in the capacitor having the above configuration, the concentration of the sealing body deterioration inhibitor in the electrolyte is 1% by weight to 90% by weight.

[0023] Furthermore, the present invention is characterized in that in the capacitor having the above configuration, the concentration of the sealing body deterioration inhibitor in the electrolyte is 3% by weight to 80% by weight.

[0024] Furthermore, the present invention is characterized in that in the capacitor having the above structure, the lipophilic solvent is γ-butyrolactone.

[0025] Furthermore, the present invention is characterized in that in the capacitor having the above-mentioned configuration, the lipophilic solvent is any one of polyethylene glycol, glycerin, and polyglycerin to which a lipophilic group is bonded.

[0026] Furthermore, the present invention is characterized in that in the capacitor having the above configuration, the solution contains the lipophilic solvent, any one of sulfolane, ethylene glycol, diethylene glycol, and polyethylene glycol, and an amphipathic compound.

[0027] Furthermore, the present invention is characterized in that in the capacitor having the above structure, the sealant deterioration inhibitor is a fat-soluble vitamin.

[0028] Furthermore, the present invention is characterized in that in the capacitor having the above configuration, the fat-soluble vitamin is tocopherol or tocotrienol. Effect of the Invention

[0029] According to the present invention, the capacitor element holds a predetermined solution in which a sealant deterioration inhibitor is dissolved in a lipophilic solvent, and a liquid supply sheet is provided on the sealant side of the capacitor element, which contacts the sealant at multiple points or surfaces. This allows the sealant deterioration inhibitor to be supplied from the separator to the sealant through the liquid supply sheet, making it possible to suppress deterioration of the sealant due to oxidation for a long period of time. This prevents the solution held in the capacitor element from leaking out, and makes it possible to stably maintain the characteristics of the capacitor for a long period of time. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a perspective view of a capacitor according to a first and second embodiment of the present invention, as viewed from above; [Diagram 2] FIG. 1 is a perspective view of a capacitor according to a first and second embodiment of the present invention, as viewed from below; [Diagram 3] FIG. 1 is a front cross-sectional view showing a capacitor according to a first and second embodiments of the present invention; [Figure 4] FIG. 1 is a perspective view showing a capacitor element of a capacitor according to first and second embodiments of the present invention; [Diagram 5] Detailed view of part G in Figure 3 [Figure 6] Detailed view of part H in Figure 3 [Figure 7]FIG. 4 is a front cross-sectional view showing an element housing process of the capacitor according to the first and second embodiments of the present invention; [Figure 8] FIG. 1 is a plan view showing an element housing step of the capacitor according to the first and second embodiments of the present invention; [Figure 9] FIG. 4 is a front cross-sectional view showing a process of attaching a sealing body to the capacitor according to the first and second embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figures 1 and 2 show a perspective view of a capacitor 1 of a first embodiment as seen from above and below. Capacitor 1 is an electrolytic capacitor, and is mounted on a seat plate 15. Seat plate 15 is made of synthetic resin and holds capacitor 1. Seat plate 15 is provided with a pair of through holes 15a, 15b.

[0032] Capacitor 1 has lead terminals 8, 9, and the lead terminals 8, 9 inserted into through holes 15a, 15b of base plate 15 are bent outward. As a result, capacitor 1 is placed on the circuit board while the top surface of main body case 2 is held by an automated machine, and the lead terminals 8, 9 are soldered to the lands of the circuit board for mounting.

[0033] 3 shows a front cross-sectional view of capacitor 1. Capacitor 1 comprises a main case 2, a capacitor element 3, a sealing body 4, and a liquid supply sheet 10. Main case 2 is made of a metal such as aluminum, and is formed into a cylindrical shape with a circular cross section and a bottom, one end of which is closed by an end wall portion 2a and the other end of which has an opening 2b. The capacitor element 3 is housed in main case 2, and opening 2b is sealed by sealing body 4.

[0034] 4 shows a perspective view of capacitor element 3. Capacitor element 3 has anode foil 5, cathode foil 7, and separator 6. Anode foil 5 and cathode foil 7 are each formed into a long strip of metal foil. Separator 6 is also formed into a long strip of nonwoven fabric or the like.

[0035] Capacitor element 3 is formed by winding anode foil 5 and cathode foil 7 with separator 6 interposed therebetween into a cylindrical shape. Band-shaped anode foil 5, cathode foil 7, and separator 6 are elongated in the winding direction (longitudinal direction), and the width in the direction perpendicular to the winding direction (transverse direction) is shorter than the length in the winding direction. The ends of anode foil 5 or cathode foil 7 are fixed with tape 12. A lead terminal 8 is connected to anode foil 5, and a lead terminal 9 is connected to cathode foil 7.

[0036] The width of separator 6 in the axial direction (short side direction) is formed to be larger than the axial widths of anode foil 5 and cathode foil 7. As a result, separator 6 protrudes upward (toward end wall portion 2a) and downward (toward opening 2b) relative to anode foil 5 and cathode foil 7, preventing a short circuit between anode foil 5 and cathode foil 7.

[0037] The anode foil 5 is made of a valve metal such as aluminum, tantalum, niobium, titanium, etc. The cathode foil 7 faces the anode foil 5 via the separator 6 and is made of aluminum or the like. An oxide film (not shown) is formed on the surfaces of the anode foil 5 and the cathode foil 7.

[0038] In addition, an electrolyte is held between the anode foil 5 and the cathode foil 7 of the capacitor element 3. By immersing the capacitor element 3 in the electrolyte for a predetermined period of time, the electrolyte permeates the separator 6 and is held between the anode foil 5 and the cathode foil 7. The electrolyte essentially functions as a cathode. In addition, the electrolyte can repair defects in the oxide films of the anode foil 5 and the cathode foil 7.

[0039] The electrolytic solution is made of a solution in which an electrolyte and a sealant deterioration inhibitor are dissolved in a lipophilic solvent. In this embodiment, γ-butyrolactone is used as the lipophilic solvent. As the lipophilic solvent, polyethylene glycol, glycerin, or polyglycerin to which a lipophilic group is bonded may also be used. To improve the penetration of the sealant deterioration inhibitor into the sealant 4, it is preferable that the lipophilic solvent contains γ-butyrolactone.

[0040] In addition, the solvent of the electrolyte may be sulfolane, ethylene glycol, diethylene glycol, polyethylene glycol, etc., in combination with a lipophilic solvent. In this case, an amphipathic compound may be added as necessary. As the amphipathic compound, a polyethylene glycol derivative, a polyethylene glycol-polypropylene glycol copolymer, etc. may be used.

[0041] The electrolyte dissociates into ions when dissolved in a solvent and exhibits electrical conductivity, and an organic amine salt of a boric acid compound or a carboxylic acid compound is used.

[0042] The sealant deterioration inhibitor is a compound that dissolves in a lipophilic solvent and penetrates into the sealant 4. For simplicity, a sealant deterioration inhibitor can be a compound that is dissolved in a lipophilic solvent at a concentration of 10% and after immersing the sealant 4 in the solution for one week and wiping off the solution on the surface, the weight of the sealant 4 increases compared to that of the sealant 4 immersed only in the lipophilic solvent.

[0043] Specifically, the encapsulant deterioration inhibitor may be a terpenoid such as a fat-soluble vitamin having an isoprene skeleton in the molecule (including cases where the main chain of the isoprene skeleton has a single bond or double bond and a cyclic structure), a saturated fatty acid, an unsaturated fatty acid, a polyglycerin ester, or a derivative thereof. In order to facilitate dissolution of these encapsulant deterioration inhibitors in a lipophilic solvent, a nonionic surfactant or an amphiphilic polymer compound may be added.

[0044] Examples of fat-soluble vitamins include vitamin A (retinol, α-carotene, β-carotene, β-cryptoxanthin), vitamin D (vitamin D2, vitamin D3), vitamin E (α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol, α-tocotrienol, β-tocotrienol, γ-tocotrienol, δ-tocotrienol), vitamin K (vitamin K1, vitamin K2, menaquinone 7), and the like.

[0045] An example of the polyglycerol ester is a tetraglycerol triester having oleic acid as the fatty acid group.

[0046] 3, sealing body 4 is formed into a disk shape by molding an insulating elastic material and has a pair of through holes 4a, 4b. Lead terminals 8, 9 of capacitor element 3 are inserted into through holes 4a, 4b by press-fitting. Sealing body 4 can be made of butyl rubber, silicone rubber, fluororubber, or the like.

[0047] Butyl rubber is more preferable because it has high environmental resistance such as heat aging resistance, chemical resistance, and weather resistance, high electrical insulation properties, and low gas permeability. Silicone rubber and fluororubber are less airtight than butyl rubber, but the airtightness can be increased by covering the outer surface of the sealing body 4 with a covering portion 17 described later.

[0048] The liquid supply sheet 10 is formed, for example, in a strip shape by papering up cellulose fibers into a sheet, and is disposed between the inner surface of the main body case 2 and the outer surface of the capacitor element 3. The liquid supply sheet 10 is provided with an absorption section 10a and a supply section 10b. The absorption section 10a is disposed facing the end wall section 2a, and contacts the separator 6 of the capacitor element 3 to absorb the electrolyte solution containing a sealant deterioration inhibitor. The supply section 10b is in contact with the sealant 4, and supplies the electrolyte solution absorbed from the separator 6 to the sealant 4.

[0049] The liquid supply sheet 10 folds both side portions from the absorption portion 10a facing the end wall portion 2a and extends in the axial direction along the inner peripheral surface 2c of the main body case 2. The liquid supply sheet 10 extending in the axial direction protrudes toward the sealing body 4 beyond the capacitor element 3, and is folded in the radial direction to face the sealing body 4. As a result, supply portions 10b are formed at both end portions of the liquid supply sheet 10.

[0050] 5 and 6 are detailed views of part G and part H in Fig. 3. At least a part of the separator 6 protruding toward the end wall portion 2a side relative to the anode foil 5 and the cathode foil 7 contacts the absorbing portion 10a at multiple points or a surface. In addition, the liquid supply portion 10b formed by bending both ends of the liquid supply sheet 10 in the radial direction contacts the sealing body 4 at multiple points or a surface.

[0051] The electrolyte solution absorbed from the separator 6 via the absorbing unit 10a is continuously supplied to the sealing body 4 via the supply unit 10b. The sealant deterioration inhibitor contained in the electrolyte solution permeates into the sealing body 4 via intermolecular gaps inside the sealing body 4. Therefore, the sealant deterioration inhibitor can inhibit the oxidation-induced deterioration of the sealing body 4 over the long term, and can prevent the electrolyte solution from evaporating through cracks in the sealing body 4, etc.

[0052] The electrolyte that permeates into sealing body 4 reaches the outer surface of sealing body 4 (the surface opposite capacitor element 3). As a result, the outer surface of sealing body 4 is covered with the electrolyte in an oily film state.

[0053] The sealant deterioration inhibitor on the outer surface of the sealant 4 is oxidized and solidified when exposed to oxygen in the air and exposed to high temperatures. Therefore, in the capacitor 1 of this embodiment, the outer surface of the sealant 4 is covered with a coating 17 in which the sealant deterioration inhibitor is oxidized and solidified by high-temperature treatment. The outer surface of the sealant 4 may be covered with an oil film, but as will be described in detail later, being covered with the coating 17 more reliably prevents evaporation of the electrolyte due to deterioration of the sealant 4.

[0054] Furthermore, liquid supply sheet 10 is in a swollen state due to the inclusion of the electrolyte, which reduces the range of movement of capacitor element 3 within main body case 2, thereby improving the vibration resistance of capacitor element 3.

[0055] The absorption section 10a facing the end wall section 2a may be provided at one end of the liquid supply sheet 10, and the supply section 10b may be provided at the other end. As shown in this embodiment, it is more preferable to form the liquid supply sheet 10 into a U-shape, provide the absorption section 10a in the center, and provide supply sections 10b at both ends, because this ensures that the sealant deterioration inhibitor can be supplied to the sealant 4.

[0056] With the sealing body 4 placed in the opening 2b, the main case 2 is subjected to a drawing process in which the outer peripheral surface is pressed. As a result, a protrusion 13 that protrudes toward the inner peripheral surface of the main case 2 is formed. The outer peripheral surface of the sealing body 4 is compressed in the inward direction by the protrusion 13, so that it is tightly attached to the inner peripheral surface of the main case 2. Furthermore, the compression of the sealing body 4 causes the inner surfaces of the through holes 4a, 4b to be tightly attached to the lead terminals 8, 9. As a result, the opening 2b of the main case 2 is sealed by the sealing body 4, so that the electrolyte held in the capacitor element 3 does not leak out of the main case 2.

[0057] In addition, the open end of main case 2 is folded back to the outer surface of sealing body 4 (the surface opposite capacitor element 3) to form folded back portion 14. Folded portion 14 and protruding portion 13 prevent sealing body 4 from slipping out of main case 2.

[0058] Capacitor 1 is manufactured by sequentially performing an element formation process, an element housing process, a sealing body attachment process, a molding process, and a repair process. In the element formation process, anode foil 5 with lead terminal 8 and cathode foil 7 with lead terminal 9 are wound with separator 6 interposed therebetween, and then immersed in an electrolyte for a predetermined time to form capacitor element 3.

[0059] 7 and 8 are a front cross-sectional view and a plan view showing the element storage step. In the element storage step, the longitudinal center of a strip-shaped liquid supply sheet 10 is placed on the opening 2b of the main case 2. The width of the liquid supply sheet 10 in the lateral direction is formed to be the same as or slightly smaller than the inner diameter of the main case 2. Then, the capacitor element 3 is inserted into the main case 2 from above the liquid supply sheet 10, and the liquid supply sheet 10 is pressed into the main case 2.

[0060] As a result, the liquid supply sheet 10 is disposed in a U-shape between the inner surface of the main body case 2 and the outer surface of the capacitor element 3 housed in the main body case 2. The central portion in the longitudinal direction of the liquid supply sheet 10 forms an absorption portion 10a that faces the end wall portion 2a and contacts the separator 6 (see FIG. 5). In addition, both ends in the longitudinal direction of the liquid supply sheet 10 protrude toward the opening 2b side (the sealing body 4 side) beyond the capacitor element 3 housed in the main body case 2 (see FIG. 9).

[0061] 9 is a front cross-sectional view showing the sealing body attachment process. In the sealing body attachment process, sealing body 4 is inserted into main case 2 housing capacitor element 3 from the opening 2b side and attached. Lead terminals 8, 9 of capacitor element 3 are inserted into through holes 4a, 4b of sealing body 4 by press-fitting. At this time, both longitudinal ends of liquid supply sheet 10 are pressed by sealing body 4 and bent in the radial direction, forming supply parts 10b in contact with the inner surface of sealing body 4 (the surface on the capacitor element 3 side).

[0062] In the molding process, a protruding portion 13 that protrudes toward the inner surface of the main case 2 is formed by drawing, and a folded portion 14 is formed by folding back the open end.

[0063] In the repair process, the oxide films formed on the anode foil 5 and the cathode foil 7 are repaired. The repair process is performed, for example, by applying a voltage of 35 V between the lead terminals 8 and 9 for 30 minutes in a high-temperature environment of 125°C. Furthermore, the sealant deterioration inhibitor that reaches the outer surface of the sealant 4 is oxidized and solidified in the high-temperature environment, forming the coating 17. At this time, an electrolyte containing the sealant deterioration inhibitor is present in the sealant 4 on the capacitor element 3 side of the coating 17.

[0064] As a result, the outer surface of the sealing body 4 is covered with the coating 17, making it difficult for the entire sealing body 4 to come into contact with oxygen outside the main case 2. Even if a portion of the coating 17 deteriorates, the liquid electrolyte present inside the sealing body 4 is supplied to that portion, and the sealing body deterioration inhibitor solidifies to repair the coating 17. This makes it possible to prevent deterioration of the sealing body 4 due to oxidation for a longer period of time. This makes it possible to more reliably prevent the evaporation of the electrolyte through cracks in the sealing body 4, etc.

[0065] The formation of the coating 17 may be performed in the repair process or in a process different from the repair process. In a high temperature environment, the supply of the electrolyte to the sealing body 4 becomes faster, and the oxidation reaction of the sealing body deterioration inhibitor becomes faster. For this reason, the temperature during the formation of the coating 17 is preferably 105°C or higher, and more preferably 125°C or higher. Note that when the sealing body deterioration inhibitor is a saturated fatty acid or an ester compound of a saturated fatty acid, it takes time for the solidification reaction to occur, so it is preferable to form the coating 17 at 160°C or higher.

[0066] To sufficiently advance the formation of the coating portion 17, the time for placing in the high temperature environment is preferably 30 minutes or more, and more preferably 1 hour or more, but if the temperature is 160° C. or higher, a shorter time may be acceptable.

[0067] The concentration of the sealant deterioration inhibitor in the electrolyte is preferably 1% by weight to 90% by weight. If the content of the sealant deterioration inhibitor in the electrolyte is less than 1% by weight, the oxidation inhibition effect of the sealant 4 cannot be maintained for a long period of time. If the content of the sealant deterioration inhibitor in the electrolyte exceeds 90% by weight, the viscosity of the electrolyte increases. This increases the time for which the electrolyte is held in the capacitor element 3 and the time for which the electrolyte is supplied from the capacitor element 3 to the sealant 4, and the number of steps required for the capacitor 1 increases. It is more preferable to set the concentration of the sealant deterioration inhibitor in the electrolyte to 3% by weight to 80% by weight, since this provides a greater oxidation inhibition effect and reduces the number of steps.

[0068] Next, a durability test was conducted on the capacitor 1 in a high-temperature environment at 150°C to examine the change in capacitance over time. The electrolyte of the capacitor 1 of this embodiment uses γ-butyrolactone as a lipophilic solvent and α-tocopherol as a sealant deterioration inhibitor. The concentration of the sealant deterioration inhibitor in the electrolyte is 10% by weight. A durability test was also conducted on a comparative example in which the sealant deterioration inhibitor in the electrolyte was omitted from the embodiment. The sealant 4 of the capacitor 1 of this embodiment and the comparative example is formed from butyl rubber.

[0069] As a result of a durability test, the capacitance of the capacitor 1 of this embodiment after 8000 hours had changed by 20% or less compared to the initial capacitance, and therefore the capacitor 1 can exhibit stable characteristics over a long period of time even in a high-temperature environment.

[0070] In contrast, in the comparative example, after 4000 hours, unwanted paths (cracks) were formed in the sealing body 4, the electrolyte rapidly evaporated, and the capacitance dropped rapidly by 30% or more compared to the initial value. Therefore, the comparative example has quality assurance problems in high temperature environments.

[0071] According to this embodiment, the capacitor element 3 holds an electrolyte solution in which a sealing body deterioration inhibitor is dissolved in a lipophilic solvent, and the liquid supply sheet 10 has an absorption section 10a that contacts the separator 6 to absorb the electrolyte, and a supply section 10b that contacts the sealing body 4 to supply the electrolyte. This allows the sealing body deterioration inhibitor to be supplied from the separator 6 to the sealing body 4 via the liquid supply sheet 10, making it possible to suppress deterioration of the sealing body 4 due to oxidation over the long term. This prevents the electrolyte held in the capacitor element 3 from leaking out, and makes it possible to stably maintain the characteristics of the capacitor 1 over the long term.

[0072] In addition, the liquid supply sheet 10 is disposed with the absorbing section 10a facing the end wall section 2a, and is bent from the absorbing section 10a to extend in the axial direction along the inner peripheral surface 2c of the main case 2. Therefore, the absorbing section 10a in contact with the separator 6 and the supply section 10b in contact with the sealing body 4 can be easily realized.

[0073] In addition, both sides of the liquid supply sheet 10 are folded from the absorption section 10a to form the supply sections 10b at both ends. Therefore, the absorption section 10a and the supply section 10b can be easily formed by placing the liquid supply sheet 10 on the opening 2b of the main body case 2 and inserting the capacitor element therein.

[0074] Furthermore, since the separator 6 protrudes further toward the end wall portion 2a than the anode foil 5 and the cathode foil 7, the liquid supply sheet 10 can be reliably brought into contact with the separator 6 to form the absorbing portion 10a.

[0075] Furthermore, since liquid supply sheet 10 protrudes toward sealing body 4 beyond capacitor element 3, liquid supply sheet 10 can be reliably brought into contact with sealing body 4 to form supply portion 10b.

[0076] In addition, since supply part 10b is disposed facing sealing body 4 by bending axially extending liquid supply sheet 10 in the radial direction, the contact area of ​​supply part 10b with sealing body 4 can be increased. Therefore, the electrolyte can be reliably supplied to sealing body 4.

[0077] Furthermore, the outer surface of sealing body 4 is covered with covering 17, and the electrolyte is present inside sealing body 4 on the capacitor element 3 side of covering 17. This makes it possible to prevent deterioration of sealing body 4 due to oxidation for a longer period of time, and to stably maintain the characteristics of capacitor 1 for a longer period of time.

[0078] Furthermore, if the concentration of the sealant deterioration inhibitor in the electrolyte is 1% by weight to 90% by weight, an increase in the number of steps can be suppressed and deterioration of the sealant 4 can be suppressed for the long term.

[0079] Furthermore, if the concentration of the sealant deterioration inhibitor in the electrolyte is 3% by weight to 80% by weight, an increase in the number of steps can be further suppressed, and deterioration of the sealant 4 can be suppressed for a long period of time.

[0080] Furthermore, when the lipophilic solvent of the electrolyte is γ-butyrolactone, an electrolyte in which the sealing body deterioration inhibitor is dissolved can be easily realized.

[0081] Furthermore, when the lipophilic solvent of the electrolyte contains at least one of sulfolane, ethylene glycol, and diethylene glycol, and a nonionic surfactant, it is possible to easily realize an electrolyte in which the sealing body deterioration inhibitor is dissolved.

[0082] Furthermore, if the lipophilic solvent of the electrolyte is polyethylene glycol to which a lipophilic group is bonded, or a polyethylene glycol-polypropylene glycol copolymer, an electrolyte having a dissolved sealant deterioration inhibitor can be easily realized.

[0083] Furthermore, a sealant deterioration inhibitor that prevents deterioration of the sealant 4 due to oxidation can be easily realized by using fat-soluble vitamins such as tocopherol and tocotrienol.

[0084] <Second embodiment> Next, a second embodiment will be described. In this embodiment, the capacitor element 3 holds a solid electrolyte (not shown) instead of an electrolytic solution and a predetermined functional liquid. The other parts are the same as those of the first embodiment.

[0085] The solid electrolyte is composed of a conductive polymer or the like. The conductive polymer can reduce the ESR of the capacitor 1. As the conductive polymer, polythiophene, polypyrrole, or derivatives thereof can be used. Polyethylenedioxythiophene is more preferable because of its high electrical conductivity.

[0086] By immersing capacitor element 3 in a dispersion liquid of a conductive polymer for a predetermined time and then drying it, a solid electrolyte made of a conductive polymer can be held between anode foil 5 and cathode foil 7.

[0087] In addition, a functional liquid having a function of further lowering the ESR of capacitor 1 is held between anode foil 5 and cathode foil 7. By immersing capacitor element 3 in the functional liquid for a predetermined period of time, the functional liquid permeates separator 6 and is held between anode foil 5 and cathode foil 7.

[0088] The functional liquid is a solution in which a sealant deterioration inhibitor is dissolved in a lipophilic solvent. As the lipophilic solvent, a solvent containing at least one of sulfolane, ethylene glycol, and diethylene glycol, and a nonionic surfactant may be used. As the lipophilic solvent, a solvent in which a lipophilic group is bonded to polyethylene glycol, or an amphipathic polymer compound such as a polyethylene glycol-polypropylene glycol copolymer may be used. In order to improve the penetration of the sealant deterioration inhibitor into the sealant 4, it is preferable that the solvent contains γ-butyrolactone.

[0089] As in the above, the sealant deterioration inhibitor may be a fat-soluble vitamin, a saturated fatty acid, an unsaturated fatty acid, a polyglycerol ester, or a derivative thereof. In order to facilitate dissolution of the sealant deterioration inhibitor in a lipophilic solvent, a nonionic surfactant or an amphiphilic polymer compound may be added.

[0090] Examples of fat-soluble vitamins include vitamin A (retinol, α-carotene, β-carotene, β-cryptoxanthin), vitamin D (vitamin D2, vitamin D3), vitamin E (α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol, α-tocotrienol, β-tocotrienol, γ-tocotrienol, δ-tocotrienol), vitamin K (vitamin K1, vitamin K2, menaquinone 7), and the like.

[0091] The solid electrolyte is swollen by the functional liquid, and therefore the solid electrolyte adheres more closely to the anode foil 5 and the cathode foil 7 that sandwich the solid electrolyte, thereby reducing the ESR of the capacitor 1.

[0092] As in the first embodiment, the absorption section 10a of the liquid supply sheet 10 contacts the separator 6 of the capacitor element 3, and the supply section 10b contacts the sealing body 4. The functional liquid is continuously supplied to the sealing body 4 via the liquid supply sheet 10. The functional liquid permeates into the sealing body 4 through intermolecular gaps inside the sealing body 4. For this reason, the sealing body deterioration inhibitor contained in the functional liquid can inhibit deterioration of the sealing body 4 due to oxidation over the long term, and can prevent evaporation of the functional liquid through cracks in the sealing body 4, etc.

[0093] The outer surface of the sealing body 4 is covered with a coating 17 formed by oxidizing and solidifying the sealing body deterioration inhibitor, making it difficult for the entire sealing body 4 to come into contact with oxygen outside the main case 2. Even if a portion of the coating 17 deteriorates, the functional liquid present inside the sealing body 4 is supplied to that portion, causing the sealing body deterioration inhibitor to solidify and repairing the coating 17. This makes it possible to prevent deterioration of the sealing body 4 due to oxidation for a longer period of time. This therefore makes it possible to more reliably prevent evaporation of the functional liquid through cracks in the sealing body 4, etc.

[0094] Furthermore, liquid supply sheet 10 is in a swollen state due to the inclusion of the functional liquid, which reduces the range of movement of capacitor element 3 within main body case 2, thereby improving the vibration resistance of capacitor element 3.

[0095] According to this embodiment, the capacitor element 3 holds a functional liquid, which is a solution of a sealing body deterioration inhibitor dissolved in a lipophilic solvent, and the liquid supply sheet 10 has an absorption section 10a that contacts the separator 6 to absorb the functional liquid, and a supply section 10b that contacts the sealing body 4 to supply the functional liquid. This allows the sealing body deterioration inhibitor to be supplied from the separator 6 to the sealing body 4 via the liquid supply sheet 10, making it possible to suppress deterioration of the sealing body 4 due to oxidation over the long term. This prevents the functional liquid held in the capacitor element 3 from leaking out, making it possible to stably maintain the characteristics of the capacitor 1 over the long term.

[0096] Furthermore, the outer surface of sealing body 4 is covered with covering portion 17, and the functional liquid permeates and exists inside sealing body 4 on the capacitor element 3 side of covering portion 17. This makes it possible to prevent deterioration of sealing body 4 due to oxidation for a longer period of time, and to stably maintain the characteristics of capacitor 1 for a longer period of time.

[0097] In this embodiment, the functional liquid has the function of lowering the ESR of the capacitor 1, but may also have the function of enhancing other characteristics of the capacitor 1 (such as the function of repairing defects in the oxide films of the anode foil and cathode foil, and the function of increasing the withstand voltage of the capacitor 1).

[0098] Moreover, instead of the functional liquid, an electrolytic solution similar to that in the first embodiment may be held between the anode foil 5 and the cathode foil 7. By holding a solid electrolyte and an electrolytic solution between the anode foil 5 and the cathode foil 7, the ESR of the capacitor 1 can be further reduced.

[0099] Furthermore, in the first and second embodiments, the capacitor element 3 holds a solid electrolyte or an electrolytic solution, but the capacitor 1 may hold the functional liquid of the second embodiment without holding a solid electrolyte or an electrolytic solution. [Industrial Applicability]

[0100] The present invention can be used in capacitors such as electrolytic capacitors, and in automobiles, electronic devices, and the like in which capacitors are mounted in circuits. [Explanation of symbols]

[0101] 1 Capacitor 2 Main unit case 2a End wall 2b opening 2c Inner surface 3 Capacitor elements 4 Sealing body 4a, 4b through hole 5 Anode foil 6 Separator 7 Cathode foil 8, 9 Lead terminal 10 Liquid supply sheet 10a Absorption section 10b Supply section 12 Tape 13 Protrusion 14 Folding part 15 Seat board 16 Through hole 17 Covering part

Claims

1. a capacitor element having a predetermined solution held between an anode foil and a cathode foil wound with a separator interposed therebetween; a main body case formed into a bottomed cylindrical shape having one end closed by an end wall and an opening at the other end, for housing the capacitor element; and a sealing body for sealing the opening, wherein a liquid supply sheet that contacts the sealing body at multiple points or surfaces is provided on the sealing body side of the capacitor element, and a solution in which a sealing body deterioration inhibitor is dissolved in a lipophilic solvent is supplied to the sealing body via the liquid supply sheet.

2. the liquid supply sheet is provided with an absorbing portion that is disposed facing the end wall portion and that is in contact with the separator to absorb the solution; 2. The capacitor according to claim 1, wherein the liquid supply sheet is bent from the absorbing portion and extends in the axial direction along an inner circumferential surface of the main case.

3. 3. The capacitor according to claim 2, wherein both side portions of the liquid supply sheet are folded from the absorbing portion to form supply portions at both ends of the liquid supply sheet.

4. 4. The capacitor according to claim 3, wherein the separator has an axial width greater than the axial widths of the anode foil and the cathode foil, and the separator protrudes toward the end wall portion beyond the anode foil and the cathode foil.

5. 5. The capacitor according to claim 3, wherein the liquid supply sheet protrudes toward the sealing body further than the capacitor element.

6. 6. The capacitor according to claim 5, wherein the liquid supply portion is disposed facing the sealing member by bending the liquid supply sheet extending in the axial direction in the radial direction.

7. The capacitor according to any one of claims 3 to 6, characterized in that the solution supplied to the sealing body via the supply part permeates into the sealing body, the outer surface of the sealing body is covered with a coating part in which the sealing body deterioration inhibitor is solidified by oxidation, and the solution is present inside the sealing body on the capacitor element side of the coating part.

8. The capacitor according to any one of claims 1 to 7, wherein the capacitor element holds a solid electrolyte.

9. 9. The capacitor according to claim 1, wherein the solution is an electrolytic solution in which the sealing body deterioration inhibitor and an electrolyte are dissolved in the lipophilic solvent.

10. 10. The capacitor according to claim 9, wherein the concentration of the sealing body deterioration inhibitor in the electrolyte is 1% by weight to 90% by weight.

11. 10. The capacitor according to claim 9, wherein the concentration of the sealing body deterioration inhibitor in the electrolyte is 3% by weight to 80% by weight.

12. The capacitor according to any one of claims 8 to 11, characterized in that the lipophilic solvent is γ-butyrolactone.

13. 12. The capacitor according to claim 1, wherein the lipophilic solvent is one of polyethylene glycol, glycerin, and polyglycerin to which a lipophilic group is bonded.

14. The capacitor according to any one of claims 1 to 11, characterized in that the solution contains the lipophilic solvent, any one of sulfolane, ethylene glycol, diethylene glycol, and polyethylene glycol, and an amphiphilic compound.

15. The capacitor according to any one of claims 1 to 14, characterized in that the sealing body deterioration inhibitor is a fat-soluble vitamin.

16. 16. The capacitor of claim 15, wherein the fat-soluble vitamin is a tocopherol or a tocotrienol.

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