JP2000223374A - Electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce defective peeling of an electrically insulative resin layer in a lateral groove processing or a draw processing. SOLUTION: In an electrolytic capacitor 1 having an electrically insulative resin layer 4 on the least either of the inner surface and outer surface of a metal packaged case 3, an easily adhesive resist layer having an adhesive force stronger than that of the layer 4 to a metal layer forming the case 3 is provided between the layer 4 and the metal layer, whereby the defective peeling of the layer 4 in a lateral groove processing or a draw processing is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor having an electrically insulating resin layer on at least one of an inner surface and an outer surface of an outer case for housing a capacitor element.

[0002]

2. Description of the Related Art Conventionally, as an outer case constituting an electrolytic capacitor, a bottomed cylindrical container formed by drawing a metal, particularly an aluminum plate, has been used. The purpose of the outer case is to electrically insulate the inner or outer surface of the outer case. As Japanese Patent Laid-Open No. 60-
As proposed in Japanese Patent No. 245107 and Japanese Patent No. 2572094, an electric insulating resin (polyamide resin or acrylic resin) is applied to the inner surface or outer surface of the outer case, or an aluminum plate is formed in advance. An outer case is formed by bonding and forming an electrically insulating resin (polyamide resin or acrylic resin) layer on one surface, and drawing it to form an outer case.

[0003]

However, when a polyamide resin or an acrylic resin is used as the resin layer as described above, the groove is formed at a predetermined position on the side near the opening end of the outer case after the capacitor element is stored. When processing is performed, there is a problem that the polyamide resin layer or the acrylic resin layer is peeled off due to insufficient adhesive strength of the resin layer, resulting in a failure.

[0004] Further, even when the polyamide resin layer or the acrylic resin layer is formed on one surface of an aluminum plate in advance and formed into an outer case by drawing, there is a problem that these resin layers are peeled off in the same manner as described above. was there.

Accordingly, the present invention has been made in view of the above-mentioned problems. In the groove processing or the drawing of the outer case after the storage of the capacitor element, the electric insulating resin layer is peeled off and defective. It is an object of the present invention to provide an electrolytic capacitor that does not cause any problems.

[0006]

In order to solve the above-mentioned problems, an electrolytic capacitor according to the present invention comprises a capacitor element housed in a metal outer case having a bottomed cylindrical shape, and a capacitor element near an open end of the outer case. A groove is formed at a predetermined position on a side portion, an open end of the outer case is sealed with a sealing member, and a lead terminal derived from the capacitor element is passed through the sealing member and pulled out from the same end face, and the metal outer case is formed. An electrolytic capacitor having an electrically insulating resin layer adhered to the metal outer case on at least one of the inner surface and the outer surface of the electrolytic capacitor, wherein the resin for the metal is formed between the resin layer and the metal forming the outer case. It is characterized in that an easy-adhesion resin layer having an adhesive strength higher than that of the resin layer is provided. According to this feature, by interposing the easy-adhesion resin layer between the resin layer and the metal forming the exterior case, the adhesive force of the resin layer to the metal forming the exterior case is provided. In the groove processing or the drawing of the outer case after the storage of the capacitor element, the occurrence of defects due to the peeling of the electrically insulating resin layer can be reduced.

[0007] In the electrolytic capacitor of the present invention, it is preferable that the resin layer is a polyester resin or a nylon resin, and the easy-adhesion resin layer is an epoxy-modified polyester resin. In this case, the resin layer comes into contact with a high-temperature electrolytic solution on the inner surface of the outer case and is made into a cleaning liquid such as flux cleaning after mounting on the outer surface of the outer case. However, as an easy-adhesion resin layer, an epoxy-modified polyester resin which is relatively inferior to these chemical-resistant products but has high adhesive strength and plastic deformation properties is coated with a polyester resin or nylon resin having good chemical resistance. In addition, not only good adhesiveness to the outer case and good workability in the groove processing or drawing processing can be obtained, but also good chemical resistance can be obtained, and a balance in adhesiveness, workability, and chemical resistance can be obtained. A loose resin layer can be obtained.

In the electrolytic capacitor of the present invention, the epoxy-modified polyester resin has an epoxy equivalent of 5000 to 10
It is preferably 0000 g / eq. In this case, the epoxy equivalent is 5,000 to 100,000 g / eq.
By doing so, not only sufficient adhesive strength to the outer case can be obtained, but also the epoxy-modified polyester resin becomes hard due to excessive crosslinking, and the plastic deformability does not decrease.

In the electrolytic capacitor of the present invention, the thickness of the resin layer is in the range of 5 to 20 μm, and the thickness of the easily adhesive resin layer is in the range of 20 to 50% of the thickness of the resin layer. Is preferred. With this configuration, by setting the thickness of the resin layer to 5 to 20 μm, it is possible to not only prevent the strength of the resin layer from being increased and to facilitate peeling during the processing, but also to reduce the thickness of the easily adhesive resin layer. In the range of 20% to 50% of the thickness of the resin layer, the followability to the metal forming the outer case and the resin layer during the processing is also improved.

In the electrolytic capacitor according to the present invention, the resin layer is a film having a substantially uniform thickness, and these resin films are bonded and laminated on the metal plate forming the metal outer case by the easily adhesive resin layer. Preferably, the laminate is formed into a bottomed cylindrical outer case. With this configuration, since the resin layer is formed into a film having a substantially uniform thickness, an electrically insulating resin layer having a substantially uniform thickness can be easily formed on a metal plate before drawing. Not only can the film be used, but by using a film, degradation of chemical resistance due to pinholes and the like can be reduced as compared with the formation of a resin layer by coating.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a chip type capacitor as an example.

(Embodiment) FIG. 1 is a partially cutaway front view showing an electrolytic capacitor of this embodiment, and FIG. 2 is an enlarged sectional view showing the structure of an exterior case used for the electrolytic capacitor of this embodiment. FIG. 3 is a side sectional view showing the state of drawing of the exterior case used for the electrolytic capacitor of the embodiment.
(A), (b) is a diagram showing the state of groove processing and curl processing in the electrolytic capacitor of the present embodiment, FIG.
FIG. 3 is a diagram illustrating a state of formation of an insulating layer in the present embodiment.

As shown in FIG. 1, the electrolytic capacitor of this embodiment has an electrically insulating layer 4 having a predetermined thickness on its outer surface, and has a bottomed cylindrical shape made of aluminum as a metal. The exterior case 3, a capacitor element 6 housed inside the exterior case 3, and a sealing member 7 for closing the opening of the exterior case 3 and sealing the interior of the exterior case 3.
And the sealing member 7 derived from the capacitor element 6
And a lead terminal 8 which is exposed to the outside through the capacitor. These electrolytic capacitors 1 are, as shown in FIG. After the capacitor element 6 and the electrolyte (not shown) are stored in the outer casing 3, a groove is formed in a predetermined position on the side surface near the open end of the outer casing 3 as shown in FIG. 5
Is formed, and the open end of the exterior case 3 is closed by the sealing member 7, and the open end 11 of the exterior case 3 is closed by a car.
And the sealing member 7 is fixed.

The capacitor element 6 in the present embodiment
Is formed by winding a separator between an anode foil and a cathode foil made of a valve metal such as aluminum and wound with an electrolytic solution, or a solid manganese dioxide layer as an electrolyte formed of aluminum or the like. A solid electrolytic capacitor element or the like formed and wound between an anode foil and a cathode foil made of a valve action metal can be used.

As shown in FIG. 2, the insulating layer 4 formed on the outer surface of the exterior case 3 in this embodiment is an easily-adhesive resin layer that adheres to the aluminum surface on which the exterior case 3 is formed. 9 and a resin layer 10 adhered to the easily-adhesive resin layer 9 and formed outside thereof.

The resin layer 10 has an appropriate strength and plastic deformability to follow the deformation in the groove processing or the outer case when the outer case is drawn into a cylindrical shape with a bottom. As described above, these chemicals are used as the electrolyte when provided on the inner surface of the outer case 3 and as the flux cleaning liquid at the time of mounting or the like when provided on the outer surface of the outer case 3. It is preferable that the resin has chemical resistance (chemical stability) that does not deteriorate even when it comes into contact with a resin or a chemical. In this embodiment, a nylon resin and a saturated polyester resin are used as resins satisfying these characteristics. However, the present invention is not limited to this, and other resins may be used as long as the above characteristics are satisfied.

If the thickness of the resin layer 10 is too small, sufficient electrical insulation and strength cannot be obtained.
In the above-mentioned processing, not only breakage or the like is likely to occur, but also good chemical resistance cannot be obtained, and if the thickness is too large, the strength of the resin layer becomes too strong with respect to the adhesive force with the aluminum surface, and during processing, In addition, the ability to follow the deformation of aluminum at the time is reduced and peeling is likely to occur, and when these resin layers are formed by coating or the like, the time required for the formation becomes longer, and 20 μm
In this embodiment, it is preferably 7 μm for nylon resin and 12.5 μm for saturated polyester resin.
However, the present invention is not limited to this, and these thicknesses may be appropriately selected according to the type and characteristics of the resin used.

Since the easy-adhesion resin layer 9 is made of metal, particularly aluminum in the present embodiment, the outer case 3 has an adhesive force with aluminum. Higher than
It is preferable that the resin layer 10 is firmly adhered to the resin layer 10 and has appropriate plastic deformability capable of following the deformation during the above-mentioned processing. Epoxy-modified polyester resin modified by introducing an epoxy group as a group is used.By thus modifying the polyester resin with epoxy, it is possible to maintain the plastic deformability of the polyester resin almost and to convert the metal to aluminum by the epoxy group. Although it is preferable because the adhesive force can be significantly improved, the present invention is not limited to this, and other resins may be used as the easily adhesive resin layer 9 as long as the above-mentioned characteristics can be satisfied. Good, and furthermore, an appropriate amount of epoxy resin is mixed with the polyester resin as the easily adhesive resin layer 9. Mixed resin may be used.

As for the thickness of the easily-adhesive resin layer 9, if it is too thin with respect to the thickness of the resin layer, good adhesive strength cannot be obtained, and if it is too thick, the strength of the easily-adhesive resin layer 9 itself becomes high. Therefore, it is preferable that the thickness be in the range of 20 to 50% of the thickness of the resin layer 10 because the followability to the aluminum and the resin layer 10 is reduced. However, the present invention is not limited to this, and may be used. What is necessary is just to select suitably according to the kind of resin, and is set to 3 micrometers in this embodiment.

The epoxy-modified polyester resin used as the easy-adhesion resin layer 9 in the present embodiment is cured with a curing agent such as an acid anhydride or a tertiary amine. If this is too large, the amount of epoxy groups present in the resin will decrease and good adhesive strength cannot be obtained, and if too small, the amount of epoxy groups present in the resin will increase and cure. , The plastic deformability of the resin is reduced.
Is preferably the minimum amount of epoxy group that can provide good adhesive strength.

In this embodiment, when the polyester resin is used as the resin layer 10 as a method of forming the easily adhesive resin layer 9 and the resin layer 10, as shown in FIG. Dissolved in a solvent, and a predetermined amount of a curing agent is added thereto to form a paint.
After coating and pre-drying to form an easy-adhesion resin layer 9 to a thickness of 1 μm, a polyester film 16 having a thickness of about 12.5 μm is laminated on the coating surface by heating and pressing with a ramylol 18. By forming the resin layer 10 and curing the epoxy-modified polyester resin,
The insulating layer 4 is formed by firmly bonding the easily adhesive resin layer 9 to the aluminum plate 13 and the polyester film 16.

As described above, the use of the polyester film 16 as the resin layer 10 makes it possible to manufacture the resin layer 10 having a substantially constant thickness in a uniform state with almost no pinhole at a high speed and stably. It is preferable because it can be performed.

It is optional to add hydrophilic or hydrophobic silica, calcium carbonate powder, titanium oxide powder or the like to these paints for the purpose of improving the heat resistance and adjusting the viscosity and the like.

In this embodiment, as described above, the epoxy-modified polyester resin is dissolved in an appropriate solvent to form a coating. However, when the epoxy-modified polyester resin is a resin that is liquid at room temperature, the liquid It is only necessary to add a curing agent to the above resin, apply it, and cure it after lamination.

In the case where a nylon resin is used for the resin layer 10, in this embodiment, the epoxy-modified polyester resin is applied to an aluminum plate 13, dried and cured, and then the nylon resin dissolved in an appropriate solvent is used. A resin paint is applied on the epoxy-modified polyester resin layer so as to have a thickness of about 7 μm and dried.

In the step of forming the resin layer 4, in order to enlarge the surface of aluminum, which is a metal, and to improve the adhesion to the resin, the aluminum surface is subjected to a pretreatment such as a phosphoric acid-chromate solution or the like. May be used to perform chemical etching or electrolytic etching.

The aluminum plate 13 on which the resin layer 10 and the easily-adhesive resin layer 9 are formed as described above is so arranged that the insulating layer 4 made of each of these resin layers becomes the outer surface of the cylindrical exterior case 3. After drawing as shown in FIG.
Forming the exterior case 3 having the insulating layer 4 by the die 15 and the punch 12 having a predetermined shape is used as the exterior case shown in FIG. It is not necessary to form the insulating layer 4 for each case 3 and the process of forming the insulating layer 4 can be simplified. However, the present invention is not limited to this. The above-mentioned epoxy-modified polyester resin layer (easy-adhesive resin layer 9) is formed on the outer surface of the exterior case 3 formed by coating, and then a nylon resin paint is applied to form a nylon resin layer (resin layer 10). It may be formed.

As described above, the cylindrical outer case 3 having the insulating layer 4 formed therein receives the capacitor element 6 and the electrolyte (not shown), and then processes the groove and the cap shown in FIG. The open end thereof is hermetically sealed by a sealing member 7 to form an electrolytic capacitor 1.

The evaluation of the insulating layer 4 formed in this manner is based on the resin (acrylic resin, nylon resin, etc.) conventionally used for the metal (aluminum) adhesive force, plastic deformation property and chemical resistance. The results obtained in comparison with are shown below.

[Table 1]

As can be seen from these results, in the conventional insulating layer 4 made of nylon resin and acrylic resin, there is a case where the adhesive force to aluminum, which is a metal, is insufficient and peeling or cracking occurs in the groove processing or drawing processing. In contrast to this, the presence of an epoxy-modified polyester resin as the easily-adhesive resin layer 9 as in the present embodiment improves the adhesion to aluminum, which is a metal, and causes peeling and squeezing in the groove processing and drawing processing. Defects due to cracking could be reduced.

As the easy-adhesion resin layer 9, an epoxy resin alone having a strong adhesive force to aluminum, which is a metal, was also evaluated. These epoxy resins are excellent in adhesive force and chemical resistance, but the resin is hard and brittle. Has characteristics,
Because of poor plastic deformability, cracks were apt to occur in the groove processing and the drawing processing, and could not be used alone.

Further, as can be seen from the above results, the epoxy-modified polyester resin is inferior in chemical resistance to the conventional nylon resin, but the surface of the resin layer has excellent chemical resistance. Since the layer and the polyester resin layer were formed as the resin layer 10, the overall chemical resistance was good and there was no problem in practical use.

Although the present invention has been described with reference to the drawings, the present invention is not limited to these embodiments, and changes and additions may be made without departing from the scope of the present invention. Needless to say, it is included in the invention.

Further, in the above embodiment, the insulating layer 4 is formed only on the outer surface of the exterior case 3, but the present invention is not limited to this, and the insulating layer 4 is formed on the exterior case. It may be formed on the inner surface of the case 3 or on both the inner surface and the outer surface of the outer case 3 as shown in FIG.

In the above embodiment, an aluminum outer case, which is generally used as a metal outer case, is used. However, the present invention is not limited to this.
These metals may be other metals than aluminum.

[0036]

The present invention has the following effects.

(A) According to the first aspect of the present invention, the easy-adhesion resin layer is interposed between the resin layer and the metal forming the exterior case, so that the exterior case of the resin layer is formed. It is possible to improve the adhesive strength to the metal forming the metal element and reduce the occurrence of defects due to peeling of the electrically insulating resin layer in the groove processing or the drawing of the outer case after the storage of the capacitor element. it can.

(B) According to the second aspect of the present invention, the resin layer comes into contact with the electrolytic solution which becomes high in temperature on the inner surface of the outer case, and is made into a cleaning solution such as flux cleaning after mounting on the outer surface of the outer case. Therefore, chemical resistance is required, but as an easily adhesive resin layer, an epoxy-modified polyester resin which is relatively inferior to these chemical resistance but is rich in adhesive strength and plastic deformability, has good chemical resistance By coating with a polyester resin or a nylon resin, not only good adhesiveness to the outer case and good workability in the groove processing or drawing processing can be obtained, but also good chemical resistance can be obtained. In addition, a resin layer having a good balance in workability and chemical resistance can be obtained.

(C) According to the third aspect of the present invention, when the epoxy equivalent is 5,000 to 100,000 g / eq,
Not only can sufficient adhesive strength be obtained for the outer case, but also the epoxy-modified polyester resin becomes hard due to excessive crosslinking, and the plastic deformability does not decrease.

(D) According to the fourth aspect of the present invention, by setting the thickness of the resin layer to 5 to 20 μm, it is possible to prevent the strength of the resin layer from being increased and the resin layer from being easily peeled off during the processing. Alternatively, by setting the thickness of the easy-adhesion resin layer in the range of 20% to 50% of the thickness of the resin layer, the ability to follow the metal forming the exterior case and the resin layer during the processing is also improved.

(E) According to the fifth aspect of the present invention, since the resin layer is formed into a film having a substantially uniform thickness, the electrically insulating resin layer having a substantially uniform thickness is drawn. Not only can it be easily formed on the previous metal plate, but also by using a film, degradation of chemical resistance due to pinholes and the like can be reduced as compared with the formation of a resin layer by coating.

[0042]

[Brief description of the drawings]

FIG. 1 is a partially broken front view showing an electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing the structure of an exterior case used for the electrolytic capacitor according to the embodiment of the present invention.

FIG. 3 is a side sectional view showing a state of drawing of an exterior case used for the electrolytic capacitor in the embodiment of the present invention.

FIGS. 4A and 4B are side sectional views showing a groove processing state in the embodiment of the present invention.

FIG. 5 is a diagram showing a state of formation of an insulating layer in an example of the present invention.

FIG. 6 is a partially cutaway front view showing an electrolytic capacitor according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 electrolytic capacitor 3 outer case 4, 4 'insulating layer 5 lateral groove 6 capacitor element 7 sealing member 8 lead terminal 9 easy-adhesion resin layer 10 resin layer 11 opening end 12 punch 13 aluminum plate 15 die 16 polyester film 18 ramiro Le

Claims (5)

[Claims] 1. A capacitor element is housed in a bottomed cylindrical metal outer case, a groove is formed at a predetermined position on a side near an open end of the outer case, and the open end of the outer case is sealed by a sealing member. At the same time, the lead terminal led out from the capacitor element is passed through the sealing member and pulled out from the same end face, and at least one of the inner surface and the outer surface of the metal outer case is bonded to the metal outer case. In an electrolytic capacitor having a resin layer, an easy-adhesion resin layer having an adhesive force higher than the adhesive force of the resin layer to the metal is provided between the resin layer and the metal forming the exterior case. An electrolytic capacitor characterized by the following: 2. The electrolytic capacitor according to claim 1, wherein the resin layer is a polyester resin or a nylon resin, and the easily adhesive resin layer is an epoxy-modified polyester resin. 3. The electrolytic capacitor according to claim 2, wherein the epoxy-modified polyester resin has an epoxy equivalent of 5,000 to 100,000 g / eq. 4. The method according to claim 1, wherein the thickness of the resin layer is in a range of 5 to 20 μm, and the thickness of the easily adhesive resin layer is in a range of 20 to 50% of the thickness of the resin layer. The electrolytic capacitor as described. 5. The laminate according to claim 1, wherein the resin layer is a film having a substantially uniform thickness, and the resin film is adhered and laminated on the metal plate forming the metal outer case by the easily adhesive resin layer. The electrolytic capacitor according to any one of claims 1 to 4, wherein said capacitor is formed into a bottomed cylindrical outer case.