WO2014010569A1

WO2014010569A1 - Electrolytic capacitor

Info

Publication number: WO2014010569A1
Application number: PCT/JP2013/068688
Authority: WO
Inventors: 中山　純一; 翠東城; 好夫寺田; 憲司古田
Original assignee: 日東電工株式会社
Priority date: 2012-07-13
Filing date: 2013-07-08
Publication date: 2014-01-16
Also published as: JP2014022442A; TW201403644A

Abstract

An electrolytic capacitor is provided with: a capacitor element; an external case which houses the capacitor element, comprises a side wall and a bottom wall and has one open end; and a sealing material for sealing said open end. The electrolytic capacitor is provided with a thermally conductive sheet which is disposed between the capacitor element and the inside surface of the external case and/or the sealing material.

Description

Electrolytic capacitor

The present invention relates to an electrolytic capacitor.

Electrolytic capacitors may generate heat due to ripple current. When the heat is stored inside the electrolytic capacitor, the life of the electrolytic capacitor is shortened. Therefore, it is known that the heat generated by the electrolytic capacitor is radiated to the outside by the radiation fin.

However, using heat radiating fins has the disadvantage of increasing the size of the device. For this reason, an electrolytic capacitor with improved heat dissipation without increasing the size has been proposed (see, for example, Patent Document 1 below).

Patent Document 1 listed below discloses an electrolytic capacitor in which a capacitor element is housed in a bottomed cylindrical outer case, and a gap between the outer case and the capacitor element is filled with silicone oil.

JP 2002-110479 A

However, in the electrolytic capacitor described in Patent Document 1, since the liquid between the outer case and the capacitor element is filled with silicone oil that is a liquid, the capacitor element is likely to vibrate without being stabilized in the outer case. There is a problem that the electrode lead connected to the capacitor element is disconnected.

Also, the electrolytic capacitor described in Patent Document 1 is insufficient in terms of heat dissipation, and further improvement in heat dissipation is required.

An object of the present invention is to provide an electrolytic capacitor having excellent heat dissipation and stability.

The electrolytic capacitor of the present invention includes a capacitor element, an exterior case in which the capacitor element is accommodated, having a side wall and a bottom wall, with one end opened, and a sealing material for sealing the opening at the one end. An electrolytic capacitor is characterized in that a thermally conductive sheet is disposed between the capacitor element and the inner surface of the outer case and / or the sealing material.

In addition, it is preferable that the thermal conductive sheet has a thermal conductivity of 0.3 W / m · K or more.

Moreover, it is preferable that the heat conductive sheet has an adhesive strength of 0.1 N / 20 mm or more.

The thermally conductive sheet preferably contains a resin and thermally conductive particles, and the blending ratio of the thermally conductive particles is preferably 50 to 1200 parts by mass with respect to 100 parts by mass of the resin. is there.

The resin is preferably an acrylic polymer obtained by polymerizing a monomer component containing a (meth) acrylic acid alkyl ester monomer.

The heat conductive sheet preferably includes a base material and a heat conductive pressure-sensitive adhesive layer laminated on both surfaces of the base material.

The heat conductive sheet has one surface in the thickness direction attached to the capacitor element, and the other surface in the thickness direction attached to at least one of the side wall, the bottom wall, and the sealing material. It is preferable that

Further, it is preferable that the thermal conductive sheet is disposed between the capacitor element and the inner surface of the bottom wall.

In the electrolytic capacitor of the present invention, a heat conductive sheet is disposed between the capacitor element and the inner surface of the outer case and / or the sealing material. Therefore, the heat generated by the capacitor element can be efficiently conducted to the exterior case. As a result, heat dissipation is excellent.

Also, the gap between the outer case and the capacitor element is blocked by the heat conductive sheet. Therefore, it is possible to suppress the capacitor element from vibrating in the outer case. Therefore, the stability of the capacitor element is excellent.

FIG. 1 shows a cross-sectional view of a first embodiment of the electrolytic capacitor of the present invention. FIG. 2 shows a cross-sectional view of a second embodiment of the electrolytic capacitor of the present invention. FIG. 3 shows a cross-sectional view of a third embodiment of the electrolytic capacitor of the present invention. FIG. 4 shows a cross-sectional view of a fourth embodiment of the electrolytic capacitor of the present invention. FIG. 5 is an explanatory view of a thermal characteristic evaluation apparatus, in which FIG. 5 (a) shows a front view and FIG. 5 (b) shows a side view.

Embodiment of the Invention

As shown in FIG. 1, the electrolytic capacitor 1 of the first embodiment of the present invention includes an outer case 3, a capacitor element 2, and a sealing material 4.

The exterior case 3 has a side wall 10 and a bottom wall 11, and an upper end portion (one end portion) 13 is opened to form a bottomed cylindrical shape.

The side wall 10 is formed in a substantially cylindrical shape, the inner diameter thereof is slightly larger than the outer diameter of the capacitor element 2, and the vertical length thereof is larger than the vertical length of the capacitor element 2.

The upper end 13 of the side wall 10 is formed in an S-shaped cross section or an inverted S-shaped cross section. Specifically, the upper end portion 13 has a concave portion 16a that is recessed in a substantially arc shape in cross section in the radial direction of the side wall 10 and extends upward continuously from the concave portion 16a. And a convex portion 16b bulging in an arc shape. The lower end portion of the concave portion 16a is continuous with the substantially cylindrical side wall 10 below the concave portion 16a, and the free end portion 14 of the convex portion 16b is formed to face downward.

The bottom wall 11 is formed in a substantially circular shape in plan view. The diameter of the bottom wall 11 coincides with the outer diameter of the side wall 10, and the peripheral edge portion of the bottom wall 11 is formed continuously with the lower end portion of the side wall 10.

The inner diameter (diameter) A1 of the inner surface 26 of the bottom wall 11 is, for example, 1 mm or more, preferably 5 mm or more, more preferably 10 mm or more, and for example, 100 mm or less, preferably 80 mm or less, more preferably. Is also 50 mm or less.

The capacitor element 2 is formed in a substantially cylindrical shape by winding an anode foil, a cathode foil, and a separator (not shown) interposed therebetween around a metal core 8.

A winding fastener (not shown) is attached to the outer peripheral surface 9 of the capacitor element 2.

The diameter A2 of the capacitor element 2 is, for example, 1 mm or more, preferably 5 mm or more, more preferably 10 mm or more, and for example, 100 mm or less, preferably 80 mm or less, more preferably 50 mm or less.

And the capacitor | condenser element 2 is accommodated in the exterior case 3, and is mounted in the center part of the bottom part of the bottom wall 11 so that the axial direction and the side wall 10 of the core 8 may become parallel in cross section. . The upper surface 28 of the capacitor element 2 is disposed so as to be lower than the recess 16a.

The sealing material 4 is disposed on the upper end portion 13 of the outer case 3.

The sealing material 4 is formed in an approximately circular shape with a thick wall from an elastically deformable insulating material such as rubber. The diameter of the sealing material 4 is substantially the same as the inner diameter of the outer case 3.

The sealing material 4 seals the upper end portion 13 of the outer case 3. Specifically, the sealing material 4 is in contact with the inner side of the boundary portion between the concave portion 16a and the convex portion 16b at the peripheral portion of the lower surface, and is in contact with the free end portion 14 at the peripheral portion of the upper surface. Thereby, the sealing material 4 is fixed to the outer case 3 by being sandwiched between the boundary portion between the concave portion 16 a and the convex portion 16 b and the free end portion 14, and seals the upper end portion 13 of the outer case 3. Yes.

Two external terminals 21 are arranged on the upper surface 19 of the sealing material 4 with a gap therebetween. Two internal terminals 22 corresponding to the two external terminals 21 are arranged on the lower surface 17 of the sealing material 4 at an interval.

Each external terminal 21 is electrically connected to the corresponding internal terminal 22 by a wiring (not shown) penetrating in the thickness direction of the sealing material 4.

Further, each of the two internal terminals 22 is electrically connected to the capacitor element 2 through the electrode lead wire 23. That is, one internal terminal 22 is connected to the anode foil of the capacitor element 2 via the electrode lead wire 23, and the other internal terminal 22 is connected to the cathode foil of the capacitor element 2 via the electrode lead wire 23. Yes.

The distance A3 between the outer peripheral surface 9 of the capacitor element 2 and the inner surface 25 of the side wall 10 is, for example, 0.1 mm or more, preferably 0.5 mm or more, more preferably 1 mm or more, and for example, 20 mm or less. It is preferably 10 mm or less, more preferably 5 mm or less.

The heat conductive adhesive sheet 30 is formed in a substantially circular flat plate shape, and more specifically, has substantially the same shape in plan view as the inner side surface 26 of the bottom wall 11 of the outer case 3.

The heat conductive adhesive sheet 30 is disposed between the lower surface 27 of the capacitor element 2 and the inner side surface 26 of the bottom wall 11 of the outer case 3. That is, one surface in the thickness direction of the heat conductive adhesive sheet 30 is in contact with the lower surface 27 of the capacitor element 2, and the other surface in the thickness direction is in contact with the inner surface 26 of the bottom wall 11. Further, the peripheral end surface of the heat conductive adhesive sheet 30 is in contact with the inner side surface 25 of the side wall 10 of the exterior case 3.

The heat conductive adhesive sheet 30 includes a base material 31 and a heat conductive adhesive layer 32 laminated on both surfaces of the base material 31.

The substrate 31 is, for example, a polyester film (polyethylene terephthalate film or the like), for example, a fluorine-based polymer (for example, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene). Copolymer, chlorofluoroethylene-vinylidene fluoride copolymer, etc.), eg, olefin resin film made of olefin resin (polyethylene, polypropylene, etc.), eg, polyvinyl chloride film, polyimide film, Plastic base film (synthetic resin film) such as polyamide film (nylon film) and rayon film, eg fine paper, Japanese paper, kraft paper, glassine paper, synthetic paper Paper such as top-coated paper, for example, and they were double layered composites and the like. Preferably, a polyester film is used.

The thickness of the base material 31 is, for example, 2 μm or more, preferably 12 μm or more, and for example, 100 μm or less, preferably 50 μm or less.

The heat conductive adhesive layer 32 contains, for example, heat conductive particles and a resin, and is formed into a sheet shape that spreads in the surface direction (direction orthogonal to the thickness direction).

The resin includes, for example, an acrylic polymer, and more specifically, an acrylic polymer obtained by polymerizing a monomer component containing a (meth) acrylic acid alkyl ester monomer.

Examples of (meth) acrylic acid alkyl ester monomers include methacrylic acid alkyl ester monomers and / or acrylic acid alkyl ester monomers, such as methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. Isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, (meth) Isopentyl acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, (meth ) Isononyl acrylate, (meth) ac Decyl lurate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, (meth) acrylic C1-20 alkyl groups in which the alkyl moiety is linear or branched, such as hexadecyl acid, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate And (meth) acrylic acid alkyl ester.

Of these (meth) acrylic acid alkyl ester monomers, (meth) acrylic acid C2-12 alkyl ester is preferred, and (meth) acrylic acid C4- 9 alkyl esters.

The (meth) acrylic acid alkyl ester monomer is blended in the monomer component in a proportion of, for example, 60% by mass or more, preferably 80% by mass or more, for example, 100% by mass or less, preferably 99% by mass or less. .

In addition to the (meth) acrylic acid alkyl ester monomer, the monomer component can contain, as optional components, a polar group-containing monomer, a polyfunctional monomer, and a copolymerizable monomer copolymerizable with these monomers.

Examples of polar group-containing monomers include nitrogen-containing monomers, hydroxyl group-containing monomers, sulfo group-containing monomers, nitrogen / hydroxyl group-containing monomers, nitrogen / sulfo group-containing monomers, hydroxyl group / phosphate group-containing monomers, and carboxyl group-containing monomers. Etc.

Examples of the nitrogen-containing monomer include cyclic (meth) acrylamides such as N- (meth) acryloylmorpholine and N- (meth) acryloylpyrrolidine, such as (meth) acrylamide, N-substituted (meth) acrylamide (for example, N- N-alkyl (meth) acrylamides such as ethyl (meth) acrylamide and Nn-butyl (meth) acrylamide, for example, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N N, such as dipropyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide, N, N-di (n-butyl) (meth) acrylamide, N, N-di (t-butyl) (meth) acrylamide N-dialkyl (meth) acrylamide) Luamide such as N-vinyl-2-pyrrolidone (NVP), N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazine-2 -One, N-vinyl cyclic amides such as N-vinyl-3,5-morpholinedione, such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl ( Amino group-containing monomers such as (meth) acrylate, for example, N-cyclohexylmaleimide, maleimide skeleton-containing monomers such as N-phenylmaleimide, such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N- 2-ethylhexylitaconimide, N-laurylitaconimi And itaconimide monomers such as N- cyclohexyl itaconic imide.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, (meth ) 8-hydroxyoctyl acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and the like.

Examples of the sulfo group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid, and the like.

Examples of the monomer having both nitrogen and hydroxyl groups include N- (2-hydroxyethyl) (meth) acrylamide (HEAA / HEMA), N- (2-hydroxypropyl) (meth) acrylamide, and N- (1-hydroxypropyl). (Meth) acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, N- (4-hydroxy N-hydroxyalkyl (meth) acrylamides such as (butyl) (meth) acrylamide.

Examples of the nitrogen / sulfo group-containing monomer include 2- (meth) acrylamide-2-methylpropanesulfonic acid and (meth) acrylamidepropanesulfonic acid.

Examples of the hydroxyl group / phosphate group-containing monomer include 2-hydroxyethyl (meth) acryloyl phosphate.

Examples of the carboxyl group-containing monomer include (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Examples of the carboxyl group-containing monomer include carboxylic anhydrides such as maleic anhydride and itaconic anhydride.

Among these polar group-containing monomers, from the viewpoint of imparting high adhesiveness and holding power to the pressure-sensitive adhesive layer, preferably, a hydroxyl group-containing monomer, a nitrogen-containing monomer, and a nitrogen / hydroxyl combination monomer are mentioned, and more preferably , NVP, HEAA / HEMA.

The polar group-containing monomer is blended in the monomer component, for example, in a proportion of 2% by mass or more, preferably 5% by mass or more, and for example, 30% by mass or less, preferably 25% by mass or less. Blended. When the blending ratio of the polar group-containing monomer is within the above range, good adhesiveness and holding power can be imparted to the pressure-sensitive adhesive layer.

In addition, the carboxyl group-containing monomer is preferably blended in the monomer component at a ratio of, for example, 5% by mass or less, preferably 1% by mass or less, and more preferably 0% by mass (that is, not blended). . By setting it as said mixture ratio, the corrosion of the metal which comprises the exterior case 3 etc. can be prevented.

The polyfunctional monomer is a monomer having a plurality of ethylenically unsaturated hydrocarbon groups, for example, hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolpropane tri ( Bifunctional or higher, such as (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate It includes polyfunctional monomer is.

Preferably, a tetrafunctional or higher polyfunctional monomer such as dipentaerythritol hexa (meth) acrylate is used.

The polyfunctional monomer is blended in the monomer component in an amount of, for example, 2% by mass or less, preferably 1% by mass or less, and for example, 0.01% by mass or more, more preferably 0.02% by mass. It mix | blends in the above ratio. When the blending ratio of the polyfunctional monomer is within the above range, the adhesive strength of the heat conductive composition can be improved.

Examples of the copolymerizable monomer include epoxy group-containing monomers such as glycidyl (meth) acrylate and allyl glycidyl ether, such as 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, (meth) Alkoxy group-containing monomers such as methoxyethylene glycol acrylate and methoxypolypropylene glycol (meth) acrylate, cyano group-containing monomers such as acrylonitrile and methacrylonitrile, styrene monomers such as styrene and α-methylstyrene, Α-olefins such as ethylene, propylene, isoprene, butadiene and isobutylene, for example, isocyanate groups such as 2-isocyanatoethyl acrylate and 2-isocyanatoethyl methacrylate Monomers, for example, vinyl ester monomers such as vinyl acetate and vinyl propionate, for example, vinyl ether monomers such as alkyl vinyl ether, for example, heterocyclic-containing (meth) acrylic esters such as tetrahydrofurfuryl (meth) acrylate, for example, Halogen atom-containing monomers such as fluoroalkyl (meth) acrylate, for example, alkoxysilyl group-containing monomers such as 3- (meth) acryloxypropyltrimethoxysilane, vinyltrimethoxysilane, for example, (meth) acryl group-containing silicone Siloxane skeleton-containing monomers such as cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclohexane Alicyclic hydrocarbon group-containing (meth) acrylates such as til (meth) acrylate, cyclooctyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, such as phenyl (meth) acrylate, benzyl (meth) Examples thereof include aromatic hydrocarbon group-containing (meth) acrylates such as acrylate, phenoxyethyl (meth) acrylate, and (meth) acrylic acid phenoxydiethylene glycol.

Of these copolymerizable monomers, an alkoxy group-containing monomer is preferable, and 2-methoxyethyl (meth) acrylate is more preferable. By mix | blending an alkoxy group containing monomer, the adhesiveness with respect to the exterior case 3 and / or the capacitor | condenser element 2 of a heat conductive adhesive layer can be improved.

The copolymerizable monomer is blended in the monomer component in an amount of, for example, 30% by mass or less, preferably 20% by mass or less, and 0% by mass or more (0% by mass when not blended or blended). %), Preferably 5% by mass or more.

These monomers can be used alone (only one kind) or in combination of two or more kinds.

Resin can be used alone (only one kind) or in combination of two or more kinds.

The thermally conductive particles are formed from a thermally conductive material in the form of particles, and examples of such thermally conductive materials include hydrated metal compounds, metal oxides, and metal nitrides. Preferably, a hydrated metal compound is used.

The hydrated metal compound has a decomposition start temperature in the range of 150 to 500 ° C., and has a general formula M _x O _y · nH ₂ O (M is a metal atom, x and y are integers of 1 or more determined by the valence of the metal, n is a compound represented by the number of contained crystal water) or a double salt containing the above compound.

Examples of the hydrated metal compound include aluminum hydroxide [Al ₂ O ₃ .3H ₂ O; or Al (OH) ₃ ], boehmite [Al ₂ O ₃ .H ₂ O; or AlOOH], magnesium hydroxide [MgO H ₂ O; or Mg (OH) ₂ ], calcium hydroxide [CaO · H ₂ O; or Ca (OH) ₂ ], zinc hydroxide [Zn (OH) ₂ ], silicic acid [H ₄ SiO ₄ ; H ₂ SiO ₃ ; or H ₂ Si ₂ O ₅ ], iron hydroxide [Fe ₂ O ₃ .H ₂ O or 2FeO (OH)], copper hydroxide [Cu (OH) ₂ ], barium hydroxide [BaO. H ₂ O; or BaO · _9H 2 O], zirconium oxide hydrate [ZrO · _nH 2 O], tin oxide hydrate [SnO · _H 2 O], basic magnesium carbonate _[3MgCO 3 · Mg (OH) · _3H 2 O], hydrotalcite _{_{[6MgO · Al 2 O 3 ·}} H 2 O], dawsonite _{_{_{_{[Na 2 CO 3 · Al 2}}}} O 3 · nH 2 O], borax _{_{_{[Na 2 O · B 2 O}}} 5 · 5H ₂ O], zinc borate _{_{[2ZnO · 3B 2 O 5 ·}} 3.5H 2 O] and the like.

Examples of the metal oxide include aluminum oxide, magnesium oxide, titanium oxide, zinc oxide, tin oxide, copper oxide, nickel oxide, and antimonic acid doped tin oxide.

Examples of metal nitrides include aluminum nitride and gallium nitride.

In addition to the above-mentioned compounds, the thermally conductive material includes, for example, boron nitride, silicon nitride, silicon carbide, silicon dioxide, calcium carbonate, barium titanate, potassium titanate, copper, silver, gold, nickel, aluminum Platinum and carbon (including diamond).

As the heat conductive material, aluminum hydroxide is preferably used from the viewpoint of imparting high heat conductivity and flame retardancy to the pressure-sensitive adhesive layer.

The shape of the heat conductive particles is not particularly limited as long as it is particulate (powder), and may be, for example, a bulk shape, a needle shape, a plate shape, or a layer shape. The bulk shape includes, for example, a spherical shape, a rectangular parallelepiped shape, a crushed shape, or a deformed shape thereof.

The size of the heat conductive particles is not particularly limited. For example, the primary average particle diameter is, for example, 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more. It is 1000 μm or less, preferably 200 μm or less, and more preferably 80 μm or less. The primary average particle size of the thermally conductive particles is based on the particle size distribution measured by the particle size distribution measurement method in the laser scattering method, and more specifically, the volume-based average particle size, more specifically, the D50 value (cumulative 50% median). (Diameter).

These heat conductive particles are commercially available. For example, as the heat conductive particles made of aluminum hydroxide, the trade name “Hijilite H-100-ME” (manufactured by Showa Denko KK), the trade name “Heidilite H— 10 "(manufactured by Showa Denko KK), trade name" Hijilite H-32 "(manufactured by Showa Denko KK), trade name" Heidilite H-31 "(manufactured by Showa Denko KK), trade name" Heidilite H-42 " (Manufactured by Showa Denko KK), trade name “Hijilite H-43M” (manufactured by Showa Denko KK), trade name “B103ST” (manufactured by Nippon Light Metal Co., Ltd.), etc. For example, the product name “KISUMA 5A” (manufactured by Kyowa Chemical Industry Co., Ltd.) can be used. For example, as the thermally conductive particles made of boron nitride, the product name “HP-40” (manufactured by Mizushima Alloy Iron Co., Ltd.) PT6 0 ”(made by Momentive Co., Ltd.) and the like, for example, as the thermally conductive particles made of aluminum oxide, the product name“ AS-50 ”(made by Showa Denko KK) and the product name“ AS-10 ”(made by Showa Denko KK). For example, as the heat conductive particles made of antimonic acid doped tin oxide, the product name “SN-100S” (Ishihara Sangyo Co., Ltd.), the product name “SN-100P” (Ishihara Sangyo Co., Ltd.), the product The name “SN-100D (water-dispersed product)” (manufactured by Ishihara Sangyo Co., Ltd.) and the like are listed. For example, as the thermally conductive particles made of zinc oxide, the trade name “SnO-310” (manufactured by Sumitomo Osaka Cement Co., Ltd.), the trade name “SnO-350” (manufactured by Sumitomo Osaka Cement Co., Ltd.), 10 "(Sumitomo Osaka Cement Co.), and the like.

These heat conductive particles can be used alone or in combination.

The content ratio of the heat conductive particles is, for example, 50 parts by mass or more, preferably 100 parts by mass or more, more preferably 300 parts by mass or more, and, for example, 1200 parts by mass with respect to 100 parts by mass of the resin. It is 1 part by mass or less, preferably 1100 parts by mass or less, and more preferably 1000 parts by mass or less. When the blending ratio of the heat conductive particles is within the above range, the heat conductive pressure-sensitive adhesive layer 32 can be provided with excellent heat conductivity and excellent adhesion (stickiness).

In addition to the above, the heat conductive adhesive layer 32 can also contain a known additive (described later).

Next, a method for producing the heat conductive pressure-sensitive adhesive layer 32 will be described.

In order to produce the heat conductive adhesive layer 32, first, a heat conductive composition is prepared. The heat conductive composition is prepared, for example, by preparing a monomer composition containing the above-described monomer component and a polymerization initiator, or preparing a polymer composition in which the above-described resin is dissolved in a solvent such as an organic solvent. Then, heat conductive particles are blended.

To prepare the monomer composition, first, a polymerization initiator is blended with the above-described monomer component.

Examples of the polymerization initiator include a photopolymerization initiator and a thermal polymerization initiator.

Examples of the photopolymerization initiator include a benzoin ether photopolymerization initiator, an α-ketol photopolymerization initiator, an acetophenone photopolymerization initiator, an aromatic sulfonyl chloride photopolymerization initiator, and a photoactive oxime photopolymerization initiator. Agents, benzoin photopolymerization initiators, benzyl photopolymerization initiators, benzophenone photopolymerization initiators, thioxanthone photopolymerization initiators, and the like. Preferred are benzoin ether photopolymerization initiators and α-ketol photopolymerization initiators.

Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, and anisole. Examples include methyl ether.

Examples of α-ketol photopolymerization initiators include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropan-1-one, and 1-hydroxy. Examples include cyclohexyl phenyl ketone.

Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis (2-methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (5-methyl-2- Imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethyleneisobutylamidine) hydrochloride, 2, Azo polymerization initiators such as 2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate, Peroxide polymerization initiators such as zoyl peroxide, t-butyl permaleate, t-butyl hydroperoxide, hydrogen peroxide, and persulfates such as potassium persulfate and ammonium persulfate, such as persulfate Examples include redox polymerization initiators such as a combination with sodium bisulfite and a combination of peroxide and sodium ascorbate.

These polymerization initiators can be used alone (only one kind) or in combination of two or more kinds.

Among these polymerization initiators, a photopolymerization initiator is preferable because of the advantage that the polymerization time can be shortened.

When a photopolymerization initiator is blended as a polymerization initiator, the photopolymerization initiator is not particularly limited, but is, for example, 0.01 parts by mass or more, preferably 0 with respect to 100 parts by mass of the monomer component. .05 parts by mass or more, and for example, 5 parts by mass or less, preferably 3 parts by mass or less.

In addition, when a thermal polymerization initiator is blended as a polymerization initiator, the thermal polymerization initiator is not particularly limited and is blended in an available ratio.

Next, in order to prepare the monomer composition, a part of the monomer component is polymerized as necessary.

In order to polymerize a part of the monomer component, when a photopolymerization initiator is blended, the mixture of the monomer component and the photopolymerization initiator is irradiated with ultraviolet rays. In order to irradiate ultraviolet rays, the monomer composition has a viscosity (BH viscometer, No. 5 rotor, 10 rpm, measurement temperature 30 ° C.) with irradiation energy that excites the photopolymerization initiator, for example, 5 Pa · s. As described above, irradiation is preferably performed until the pressure reaches 10 Pa · s or more, for example, 30 Pa · s or less, preferably 20 Pa · s or less.

In addition, when a thermal polymerization initiator is blended, the mixture of the monomer component and the thermal polymerization initiator is polymerized at, for example, a temperature higher than the decomposition temperature of the thermal polymerization initiator, specifically about 20 to 100 ° C. Similarly to the case where the photopolymerization initiator is blended at the temperature, the viscosity of the monomer composition (BH viscometer, No. 5 rotor, 10 rpm, measurement temperature 30 ° C.) is, for example, 5 Pa · s or more, preferably Heating is performed until the pressure reaches 10 Pa · s or higher, for example, 30 Pa · s or lower, preferably 20 Pa · s or lower.

When preparing a monomer composition in which a part of the monomer component is polymerized, first, a monomer selected from a (meth) acrylic acid alkyl ester monomer, a polar group-containing monomer and a copolymerizable monomer, and polymerization start As described above, a part of the monomer can be polymerized and then a polyfunctional monomer can be blended.

Thereby, a monomer composition is prepared.

To prepare the polymer composition, first, a polymerization initiator and an organic solvent are blended with the above-described monomer component, and the monomer component is polymerized, or the above-described resin is blended with the organic solvent.

The polymerization initiator and the blending ratio thereof are the same as the polymerization initiator and the blending ratio described above for the monomer component.

The solvent is an organic solvent or water, and examples of the organic solvent include ketones such as acetone and methyl ethyl ketone (MEK), aromatic hydrocarbons such as toluene, xylene, and ethylbenzene, esters such as ethyl acetate, and the like. And amides such as N, N-dimethylformamide.

These solvents can be used alone or in combination of two or more.

The mixing ratio of the solvent is, for example, 1 part by mass or more, preferably 50 parts by mass or more, and for example, 500 parts by mass or less, preferably 200 parts by mass with respect to 100 parts by mass of the monomer component or resin. It is also below the department.

In order to polymerize the monomer component, ultraviolet rays are irradiated when a photopolymerization initiator is blended, and heating is performed when a thermal polymerization initiator is blended.

Thereby, a polymer composition is prepared.

In addition, the monomer composition and the polymer composition include a dispersant, a tackifier, a crosslinking agent, a silane coupling agent, a fluorosurfactant, a plasticizer, a filler, an anti-aging agent, a colorant, and the like as necessary. Additives can also be blended.

The blending ratio of the additive is, for example, 0.1 to 10 parts by mass for the dispersant and 1 to 50 parts by mass for the tackifier with respect to 100 parts by mass of the monomer component and the resin. The agent is, for example, 0.1 to 10 parts by mass.

Next, in order to prepare a heat conductive composition, heat conductive particles are blended into the monomer composition and polymer composition obtained and mixed.

The thermally conductive particles and additives can be blended in the monomer composition or polymer composition in a state of being dispersed or dissolved in a solvent such as an organic solvent.

Thereby, a heat conductive composition is prepared.

In order to produce the heat conductive adhesive layer 32, a heat conductive composition is apply | coated to the surface (thickness direction one surface) where the peeling process of the base film (release sheet) by which the peeling process was performed was performed.

The base film is the same as that described above for the base material 31, for example.

In addition, when the heat conductive composition contains the photoinitiator, the base film which permeate | transmits an ultraviolet-ray is used so that ultraviolet irradiation with respect to a heat conductive composition may not be prevented.

As a method for applying the heat conductive composition to the base film, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, Examples include curtain coats, lip coats, and die coaters.

The coating thickness of the heat conductive composition is, for example, 1 μm or more, preferably 10 μm or more, and for example, 1000 μm or less, preferably 500 μm or less.

If necessary, a cover film (for example, a release sheet) is disposed on the surface (one surface in the thickness direction) of the coating film of the heat conductive composition. In order to arrange the cover film on the surface (one surface in the thickness direction) of the coating film, the cover film is arranged so that the surface on which the cover film is peeled is in contact with the coating film.

Examples of the cover film include films similar to the above-described base film. Moreover, when the heat conductive composition contains the photoinitiator, the cover film which permeate | transmits an ultraviolet-ray is used so that irradiation of the ultraviolet-ray with respect to a heat conductive composition may not be prevented.

In order to produce the heat conductive adhesive layer 32, when the monomer composition is contained, the monomer component of the heat conductive composition is then polymerized.

In order to polymerize the monomer component in the thermally conductive composition, as described above, when a photopolymerization initiator is blended, the thermal conductive composition is irradiated with ultraviolet rays and blended with the thermal polymerization initiator. If so, the thermally conductive composition is heated.

In addition, when a heat conductive composition is prepared from the polymer composition, the heat conductive composition is applied and dried by heating to remove the solvent. Moreover, when the polymer composition contains a crosslinking agent, the resin can be thermoset by heating.

Thereby, the heat conductive adhesive layer 32 is formed. The heat conductive adhesive layer 32 is formed as an acrylic adhesive layer, for example, when it contains a (meth) acrylic acid alkyl ester monomer as a monomer component.

The content ratio of the resin in the heat conductive adhesive layer 32 is, for example, 1% by mass or more, preferably 10% by mass or more, and for example, 60% by mass or less, preferably 45% by mass or less, more preferably. Is 40% by mass or less. The content ratio of the heat conductive particles in the heat conductive pressure-sensitive adhesive layer 32 is, for example, 1% by mass or more, preferably 10% by mass or more, and more preferably 30% by mass or more. It is also not more than mass%, preferably not more than 80 mass%.

Next, by preparing two heat conductive pressure-sensitive adhesive layers 32 on which cover films are laminated and laminating them on both surfaces of the base material 31, the heat conductive pressure-sensitive adhesive sheet 30 can be obtained.

The thickness of the heat conductive pressure-sensitive adhesive sheet 30 (total of the heat conductive pressure-sensitive adhesive layer 32 and the base material 31) is, for example, 5 μm or more, preferably 30 μm or more, and for example, 5000 μm or less, preferably 1000 μm. It is also below.

The adhesive strength (measured by the method described in Examples described later) on the surface (thermal conductive adhesive layer 32) of the obtained heat conductive adhesive sheet 30 is, for example, 0.1 N / 20 mm or more, preferably 1N / 20mm or more, more preferably 5N / 20mm or more, for example, 40N / 20mm or less, preferably 30N / 20mm or less, and more preferably 20N / 20mm or less. By setting it as this range, the heat conductive adhesive sheet 30 adheres firmly to the capacitor element 2 and the inner side surfaces 25 and 26 of the outer case 3 and / or the sealing material 4, and the capacitor element 2 and the outer case 3. And can be securely fixed.

The thermal conductivity of the heat conductive adhesive sheet 30 (measured by the method described in Examples below) is 0.3 W / m · K or more, preferably 0.4 W / m · K or more. Preferably, it is 0.5 W / m · K or more, for example, 10 W / m · K or less. By setting it as this range, the heat conductive adhesive sheet 30 is excellent in heat conductivity, Therefore, the heat | fever which the capacitor | condenser element 2 emits can be efficiently conducted to the exterior case 3. FIG.

In the electrolytic capacitor 1, a heat conductive adhesive sheet 30 is disposed between the lower surface (bottom surface) 27 of the capacitor element 2 and the inner surface 26 of the bottom wall 11. Therefore, the heat generated by the capacitor element 2 can be efficiently conducted to the outer case 3. As a result, heat dissipation is excellent. Further, the gap between the outer case 3 and the capacitor element 2 is blocked by the heat conductive adhesive sheet 30. Therefore, it is possible to suppress the capacitor element 2 from vibrating in the outer case 3. As a result, the stability of the capacitor element 2 is excellent.

Moreover, in 1st Embodiment, although a heat conductive sheet is the heat conductive adhesive sheet 30 laminated | stacked on both surfaces of the base material 31 and the base material 31, and is equipped with the heat conductive adhesive layer 32, The heat conductive sheet is not necessarily required to have adhesiveness on one side or both sides in the thickness direction, and even in such a case, it is excellent in heat dissipation and stability with respect to the capacitor element 2.

However, when the thickness direction one surface of the heat conductive adhesive layer 32 is adhered to the capacitor element 2 and the thickness direction other surface is adhered to the inner surface of the bottom wall 11 as in the first embodiment. The capacitor element 2 and the outer case 3 can be more stably fixed.

In the first embodiment, the heat conductive adhesive sheet 30 is laminated on the lower surface 27 of the capacitor element 2, but for example, a plurality of layers may be laminated, although not shown. That is, a plurality of layers (for example, 2 to 5 layers) of the heat conductive adhesive sheet 30 may be laminated in a gap between the lower surface 27 of the capacitor element 2 and the inner surface 26 of the bottom wall 11.

In the first embodiment, the heat conductive adhesive sheet 30 is disposed on the entire inner surface 26 of the bottom wall 11 and the entire lower surface 27 of the capacitor element 2. The sheet 30 may be disposed only on a part of the inner surface 26 of the bottom wall 11 and / or the lower surface 27 of the capacitor element 2.

In the first embodiment, the heat conductive adhesive sheet 30 is disposed between the lower surface 27 of the capacitor element 2 and the inner surface 26 of the bottom wall 11. For example, FIG. 2 (second embodiment) ), The capacitor element 2 may be disposed between the outer peripheral surface 9 and the inner side surface 25 of the side wall 10 of the outer case 3. In this case, the heat conductive adhesive sheet 30 is formed in a substantially rectangular flat plate shape and is wound around the outer peripheral surface 9 of the capacitor element 2. The vertical length of the heat conductive adhesive sheet 30 is substantially the same as the vertical length of the capacitor element 2, and the upper end portion and the lower end portion of the heat conductive adhesive sheet 30 are the upper surface 28 and the lower surface of the capacitor element 2. 27 to be flush with each other.

In the second embodiment, the heat conductive adhesive sheet 30 is wound once around the outer peripheral surface 9 of the capacitor element 2, but may be wound around a plurality of turns, for example, although not shown. That is, a plurality of layers (for example, 2 to 5 layers) of the heat conductive adhesive sheet 30 may be laminated in a gap between the outer peripheral surface 9 of the capacitor element 2 and the inner surface 25 of the side wall 10.

In the second embodiment, the heat conductive adhesive sheet 30 is wound once around the outer peripheral surface 9 of the capacitor element 2. For example, although not shown, the heat conductive sheet is formed of the capacitor element 2. It may be arranged only on a part of the outer peripheral surface 9. For example, the heat conductive adhesive sheet 30 may be wound around the outer peripheral surface 9 of the capacitor element 2 by a half circumference.

In the second embodiment, the vertical length of the heat conductive adhesive sheet 30 is substantially the same as the vertical length of the capacitor element 2. For example, although not shown, the vertical direction of the heat conductive adhesive sheet 30 is The length may be longer or shorter than the vertical length of the capacitor element 2.

In the first embodiment, the heat conductive adhesive sheet 30 is disposed between the lower surface 27 of the capacitor element 2 and the inner surface 26 of the bottom wall 11, but is shown in FIG. 3 (third embodiment). As shown, the capacitor element 2 may be disposed between the upper surface 28 and the lower surface 17 of the sealing material 4. In this case, the shape of the heat conductive pressure-sensitive adhesive sheet 30 is substantially the same in plan view as the upper surface 28 of the capacitor element 2 or the inside of the recess 16a. The heat conductive adhesive sheet 30 is formed with a plurality (two) of through holes penetrating in the thickness direction for inserting the electrode lead wires 23.

The above embodiments can be combined. For example, as shown in FIG. 4 (fourth embodiment), the heat conductive adhesive sheet 30 is disposed between the outer peripheral surface 9 of the capacitor element 2 and the inner side surface 25 of the side wall 10, and the capacitor element. The two lower surfaces 27 may be disposed between the lower surface 27 and the inner surface 26 of the bottom wall 11 of the outer case 3.

Hereinafter, the present invention will be described based on examples and comparative examples, but the present invention is not limited thereto.

In addition, the numerical value of the Example shown below can be substituted with the numerical value (namely, upper limit or lower limit value) described in said embodiment.

Example 1
(Preparation of heat conductive composition)
A monomer component containing 70 parts by mass of 2-ethylhexyl acrylate, 30 parts by mass of n-butyl acrylate, 0.05 part by mass of 2-hydroxyethyl acrylate, and 3 parts by mass of acrylic acid was added to a thermal polymerization initiator (2′2 ′ -Azobisisobutyronitrile (AIBN), manufactured by Wako Pure Chemical Industries, Ltd.) 0.08 parts by mass and 150 parts by mass of toluene were mixed and dissolved, and then polymerized at 65 ° C. for 8 hours to obtain an acrylic polymer. A solution (polymer composition) was obtained. The viscosity of the acrylic polymer solution (BH viscometer, No. 5 rotor, 10 s ⁻¹ , measurement temperature 30 ° C.) was about 25 Pa · s.

To the resulting acrylic polymer solution, 100 parts by mass of thermally conductive particles (aluminum hydroxide, trade name “Hijilite H-32”, shape: crushed, primary average particle size 8 μm, Showa Denko KK), adhesive Giving agent (rosin resin: trade name “superester”, weight average molecular weight 1520, softening point (ring-ball method) 95 to 105 ° C., Arakawa Chemical Industries, Ltd.) 35 parts by mass, and crosslinking agent (isocyanate crosslinking agent: The product name “Coronate L”, trimethylolpropane adduct of tolylene diisocyanate, solid content 75% by mass, 2.0 parts by mass) were added to prepare a heat conductive composition.

(Preparation of heat conductive adhesive sheet)
Using a roll coater, prepare the release sheet (polyethylene terephthalate, trade name “Diafoil MRF38”, thickness 38 μm, manufactured by Mitsubishi Plastics) so that the thickness after curing is 45 μm with a roll coater. Applied. Then, the heat conductive adhesive layer 32 was formed by heating a heat conductive composition at 110 degreeC for 3 minute (s), and making it thermoset. Next, another release sheet (polyethylene terephthalate, trade name “Diafoil MRN38”, thickness 38 μm, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) was laminated on the surface of the heat conductive adhesive layer 32.

Thereafter, one release sheet is peeled off from the heat conductive pressure-sensitive adhesive layer 32, and the heat conductive pressure-sensitive adhesive layer 32 is made of a polyethylene terephthalate substrate 31 (trade name “Lumirror S-10”, thickness 12 μm, manufactured by Toray Industries, Inc.). By sticking to both surfaces, the total thickness (excluding the thickness of the release sheet) including the polyethylene terephthalate substrate 31 and the heat conductive adhesive layer 32 laminated on both surfaces. That is, the polyethylene terephthalate substrate 31 is removed. And a thermal conductive adhesive sheet 30 (length: 300 mm, width: 250 mm) of 102 μm was prepared. This heat conductive adhesive sheet 30 was cut into a circular shape with a diameter of 30 mm.

(Production of electrolytic capacitors)
An electrolytic capacitor 1 was prepared in which a cylindrical capacitor element 2 (diameter (A2) 28 mm, height 45 mm) was accommodated in a bottomed cylindrical outer case 3 (inner diameter (A1) 30 mm, height 50 mm). The distance A3 between the outer peripheral surface 9 of the capacitor element 2 and the inner side surface 25 of the side wall 10 of the bottomed cylindrical outer case 3 was 1 mm.

The capacitor element 2 is taken out from the outer case 3, and one heat conductive adhesive sheet 30 (the release sheet is peeled off) cut into a circular shape is arranged (adhered) on the lower surface 27 of the capacitor element 2 so as to be concentric. Then, the capacitor element 2 was housed again in the outer case 3 to produce the electrolytic capacitor 1 of Example 1 (see FIG. 1).

Example 2
(Preparation of heat conductive composition)
82 parts by mass of 2-ethylhexyl acrylate, 12 parts by mass of 2-methoxyethyl acrylate, 5 parts by mass of N-vinyl-2-pyrrolidone (NVP), and 1 part by mass of hydroxyethyl acrylamide (HEAA) were mixed and mixed. A mixture was obtained.

To the resulting mixture, 0.05 parts by mass of a photopolymerization initiator (trade name “Irgacure 651”, 2,2-dimethoxy-1,2-diphenylethane-1-one, manufactured by Ciba Japan), and 0.05 parts by mass of a photopolymerization initiator (trade name “Irgacure 184”, 1-hydroxycyclohexyl phenyl ketone, manufactured by Ciba Japan Co., Ltd.) was blended.

Thereafter, the mixture was irradiated with ultraviolet rays, and the viscosity (BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30 ° C.) was about 20 Pa. Polymerization was performed until s was obtained, and a partial polymer obtained by polymerizing a part of the monomer component was obtained.

To 100 parts by mass of the obtained partial polymer, 0.05 parts by mass of dipentaerythritol hexaacrylate (polyfunctional monomer, trade name “KAYARAD DPHA-40H”, manufactured by Nippon Kayaku Co., Ltd.) and a dispersant (trade name “ 1 part by mass of “Price Surf A212E” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was mixed and mixed to obtain a monomer composition.

The obtained monomer composition was mixed with 175 parts by mass of aluminum hydroxide (trade name “Hijilite H-32”, shape: crushed, primary average particle size: 8 μm, manufactured by Showa Denko KK), and aluminum hydroxide ( 175 parts by mass of a trade name “Hijilite H-10”, shape: crushed, primary average particle size: 55 μm) (manufactured by Showa Denko KK) was added to prepare a heat conductive composition.

(Preparation of heat conductive adhesive sheet)
Between the release-treated surfaces of two release sheets (polyethylene terephthalate film, trade name “Diafoil MRF38”, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) on one side of the prepared thermally conductive composition. The film was applied so that the thickness after drying and curing was 119 μm.

Subsequently, ultraviolet rays having an illuminance of about 5 mW / cm ² are irradiated from both sides to the heat conductive composition for 3 minutes (corresponding to an irradiation energy of 900 mJ / cm ² ), and the remaining monomer component is polymerized to thereby form a heat conductive adhesive layer. 32 was made between two release sheets.

Thereafter, one release sheet is peeled off from the heat conductive pressure-sensitive adhesive layer 32, and the heat conductive pressure-sensitive adhesive layer 32 is made of a polyethylene terephthalate substrate 31 (trade name “Lumirror S-10”, thickness 12 μm, manufactured by Toray Industries, Inc.). By sticking to both surfaces, the total thickness (excluding the thickness of the release sheet) including the polyethylene terephthalate substrate 31 and the heat conductive adhesive layer 32 laminated on both surfaces. That is, the polyethylene terephthalate substrate 31 is removed. And a thermal conductive pressure-sensitive adhesive sheet 30 (length 300 mm, width 250 mm) having a thickness of 250 μm. This heat conductive adhesive sheet 30 was cut into a circular shape with a diameter of 30 mm.

The capacitor element 2 is taken out from the outer case 3, and one heat conductive adhesive sheet 30 (the release sheet is peeled off) cut into a circular shape is arranged (adhered) on the lower surface 27 of the capacitor element 2 so as to be concentric. Then, the capacitor element 2 was housed again in the outer case 3 to produce the electrolytic capacitor 1 of Example 2 (see FIG. 1).

Example 3
(Preparation of heat conductive composition)
In the same manner as in Example 2, a monomer composition was obtained.

To the obtained monomer composition, aluminum hydroxide (trade name “Hijilite H-42”, manufactured by Showa Denko KK, shape: crushed, average particle diameter (volume basis) 1 μm) 170 parts by mass, and aluminum hydroxide (Product name “Hijilite H-10”, shape: crushed, primary average particle size 55 μm, Showa Denko KK) 170 parts by mass were blended and mixed to prepare a heat conductive composition.

(Preparation of heat conductive adhesive sheet)
The prepared thermally conductive composition is dried and cured on the release-treated surface of a release sheet (polyethylene terephthalate film, trade name “Diafoil MRF38”, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) that has been subjected to a release treatment on one side. It apply | coated so that latter thickness might be set to 1000 micrometers.

Next, another release sheet (trade name “Diafoil MRF38”) is placed on the surface of the coating film of the heat conductive composition so that the coating film of the heat conductive composition is sandwiched between the release sheet and the release sheet. did. Next, the heat conductive composition was irradiated with ultraviolet rays (illuminance of about 5 mW / cm ² ) from both sides for 3 minutes.

Thereby, the monomer component in the heat conductive composition was polymerized to prepare a heat conductive pressure-sensitive adhesive sheet 30 (length 300 mm, width 250 mm). This heat conductive adhesive sheet 30 was cut into a circular shape with a diameter of 30 mm.

The capacitor element 2 is taken out from the outer case 3, and one heat conductive adhesive sheet 30 (the release sheet is peeled off) cut into a circular shape is arranged (adhered) on the lower surface 27 of the capacitor element 2 so as to be concentric. Then, the capacitor element 2 was stored again in the outer case 3 to produce the electrolytic capacitor 1 of Example 3 (see FIG. 1).

Comparative Example 1
The electrolytic capacitor 1 prepared in Example 1 (the electrolytic capacitor 1 in which the heat conductive adhesive sheet 30 is not wound around the capacitor element 2) was used as the electrolytic capacitor 1 of Comparative Example 1.

Comparative Example 2
An electrolytic capacitor 1 (an electrolytic capacitor 1 in which the heat conductive adhesive sheet 30 is not wound around the capacitor element 2) is prepared, and silicone oil (trade name “TSF451”) is placed in the gap between the capacitor element 2 and the outer case 3. Momentive) was injected up to the upper surface 28 of the capacitor element 2. This was designated as electrolytic capacitor 1 of Comparative Example 2.

<Evaluation>
-Adhesive strength About the heat conductive adhesive sheet 30 produced in each Example, a release sheet was peeled off, a 25-micrometer-thick PET film was bonded together, this was cut into width 20mm and length 150mm, and the sample for evaluation did.

The remaining release sheet is peeled off from the surface of the sample for evaluation and attached to an aluminum plate (# 1050) in an atmosphere of 23 ° C. and 50% RH. The adhesive sheet 30 was pressed against the aluminum plate.

After curing at 23 ° C. for 30 minutes, using a universal tensile tester “TCM-1kNB” (Minebea), 90 ° peel adhesive strength (adhesive strength) at a peel angle of 90 degrees and a pulling speed (peeling speed) of 300 mm / min. Was measured according to JIS Z 0237.

The results are shown in Table 1.

-Thermal conductivity The thermal conductivity was measured using a thermal property evaluation apparatus shown in FIG.

Specifically, between a pair of aluminum blocks (A5052, thermal conductivity: 140 W / m · K) L (sometimes referred to as rods) L formed so as to be a cube having a side of 20 mm. The heat conductive pressure-sensitive adhesive sheet 30 (20 mm × 20 mm, from which both release sheets were peeled off) of each example was sandwiched, and the pair of blocks L were bonded together with the heat conductive pressure-sensitive adhesive sheet 30.

And it arrange | positioned between the heat generating body (heater block) H and the heat radiating body (cooling base board comprised so that a cooling water circulates inside) C so that a pair of block L might become up-down. Specifically, the heating element H is disposed on the upper block L, and the radiator C is disposed below the block L on the lower side.

At this time, the pair of blocks L bonded together by the heat conductive adhesive sheet 30 is located between a pair of pressure adjusting screws T penetrating the heating element H and the radiator C. A load cell R is disposed between the pressure adjusting screw T and the heating element H, and is configured to measure the pressure when the pressure adjusting screw T is tightened. The pressure S applied to the heat conductive adhesive sheet 30 was used. Specifically, in this test, the pressure adjusting screw T was tightened so that the pressure applied to the heat conductive adhesive sheet 30 was 25 N / cm ² (250 kPa).

Further, three probes P (diameter 1 mm) of a contact displacement meter were installed so as to penetrate the lower block L and the heat conductive adhesive sheet 30 from the radiator C side. At this time, the upper end portion of the probe P is in contact with the lower surface of the upper block L, and the distance between the upper and lower blocks L (the thickness of the heat conductive adhesive sheet 30) can be measured. .

The temperature sensor D was attached to the heating element H and the upper and lower blocks L. Specifically, the temperature sensor D was attached to one place of the heating element H, and the temperature sensors D were attached to the five places of each block L at intervals of 5 mm in the vertical direction.

First of all, the pressure adjusting screw T is tightened to apply pressure to the heat conductive adhesive sheet 30 to set the temperature of the heating element H to 80 ° C., and at the same time, 20 ° C. cooling water is applied to the radiator C. It was circulated.

After the temperature of the heating element H and the upper and lower blocks L is stabilized, the temperature of the upper and lower blocks L is measured by each temperature sensor D, and the thermal conductivity (W / m · K) and temperature gradient of the upper and lower blocks L are measured. As well as calculating the heat flux passing through the heat conductive adhesive sheet 30, the temperature at the interface between the upper and lower blocks L and the heat conductive adhesive sheet 30 was calculated. Then, using these, the thermal conductivity (W / m · K) at the above pressure was calculated using the following thermal conductivity equation (Fourier's law).

The results are shown in Table 1.

Q = -λgradT
Q: Heat flux per unit area λ: Thermal conductivity gradT: Temperature gradient ・ Heat dissipation test A current was applied so that the center temperature of the capacitor element 2 was 80 ° C. (+ 3 ° C., within −3 ° C.). The temperature (T1) 30 minutes after applying the current was measured by inserting a thermocouple. Further, a thermocouple was also installed on the outer surface of the bottom wall 11 of the outer case 3, and the temperature (T2) 30 minutes after the application of current was measured.

The heat dissipation was evaluated by measuring the temperature difference by (center temperature of capacitor element 2 (T1)) − (temperature of outer surface of bottom wall 11 (T2)). A case where the temperature difference was 25 ° C. or less was evaluated as “◯”, and a case where the temperature difference exceeded 25 ° C. was evaluated as “X”.

The results are shown in Table 1.

-Stability test The stability of the electrolytic capacitor 1 was evaluated by the following test.

Electrolytic capacitor 1 was shaken lightly to the left and right, and a case where no vibration sound was heard was evaluated as ◯, and a case where vibration sound was heard was evaluated as x.

The results are shown in Table 1.

Although the above invention has been provided as an exemplary embodiment of the present invention, this is merely an example and should not be construed as limiting. Variations of the present invention that are apparent to one of ordinary skill in the art are within the scope of the following claims.

Claims

An electrolytic capacitor comprising a capacitor element, an outer case in which the capacitor element is accommodated, having a side wall and a bottom wall, with one end opened, and a sealing material for sealing the opening at the one end,
An electrolytic capacitor, wherein a thermally conductive sheet is disposed between the capacitor element and an inner surface of the outer case and / or the sealing material.
The electrolytic capacitor according to claim 1, wherein the thermal conductive sheet has a thermal conductivity of 0.3 W / m · K or more.
2. The electrolytic capacitor according to claim 1, wherein the heat conductive sheet has an adhesive strength of 0.1 N / 20 mm or more.
The thermally conductive sheet contains a resin and thermally conductive particles,
The electrolytic capacitor according to claim 1, wherein the blending ratio of the heat conductive particles is 50 to 1200 parts by mass with respect to 100 parts by mass of the resin.
5. The electrolytic capacitor according to claim 4, wherein the resin is an acrylic polymer obtained by polymerizing a monomer component including a (meth) acrylic acid alkyl ester monomer.
2. The electrolytic capacitor according to claim 1, wherein the heat conductive sheet includes a base material and a heat conductive pressure-sensitive adhesive layer laminated on both surfaces of the base material.
The heat conductive sheet has one surface in the thickness direction attached to the capacitor element, and the other surface in the thickness direction is attached to at least one of the side wall, the bottom wall, and the sealing material. The electrolytic capacitor according to claim 1, wherein:
2. The electrolytic capacitor according to claim 1, wherein the thermally conductive sheet is disposed between the capacitor element and an inner surface of the bottom wall.