JP2002319523A - Resin-coated aluminum member for capacitor case, capacitor case using the same, and capacitor having the capacitor case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-coated aluminum member for a capacitor case in which excellent adhesion of the coating resin film and stable insulation capability are obtained. SOLUTION: In this resin-coated aluminum member for a capacitor case, a chemical conversion layer 2 is formed on an aluminum plate 1, and a resin coating-film 3 is formed thereon. The resin coating-film 3 is made of a thermosetting resin that is constituted by a polyester resin having a number-averaged molecular weight of 8000-28000, having a hydroyl group, and which is crosslinked by a polyol-modified blocked isocyanate compound having a number-averaged molecular weight of 1000-5000. The adhesion property of the resin coating-film is satisfactory, and stable insulation capability can be obtained by not requiring any heat treatment. This resin-coated aluminum member is of high quality, is excellent in productivity, and exhibits a remarkable effect when it is used for a case of an aluminum electrolytic capacitor or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-coated aluminum (hereinafter referred to as A) for a capacitor case in which the adhesion of a resin film (organic resin film) is good and stable insulation is obtained.
l), a capacitor case using the resin-coated aluminum material, and a capacitor using the capacitor case.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 2, a capacitor element 6 is formed by impregnating a bottomed cylindrical case 5 formed by deep drawing of an Al plate with a driving electrolyte.
After the rubber sealing member 7 is stored, a lateral groove 8 is formed on the side of the case 5 to prevent the sealing member 7 from dropping off and to make the sealing member 7 and the case 5 adhere to each other. The case 5 is formed by curling and making it bite into the upper part of the sealing body 7 to seal the inside of the case 5. Hereinafter, the lateral groove processing and the curling processing are collectively referred to as “caulking processing”.

As shown in FIG. 3, the capacitor element 6 is formed by winding an anode foil 9 and a cathode foil 10 with a separator 11 interposed therebetween. 13 are connected via tabs 14 and 15, and the lead wires 12 and 13 are led out of the case 5 through a hole provided in the sealing body 7 (see FIG. 2). There are many types of the case 5. For example, the dimensions of the cylindrical type are (A) type: φ16 × 22L, φ5 × 7.0.
L, (B) type: φ16 × 37L, φ5 × 10.9
L, (C) type: φ14.5 × 47L, φ5 × 14.
4L (the unit is mm, φ is diameter, L is length)
and so on.

As shown in FIG. 4, the transverse groove is formed by a disk-shaped caulking sesame 1 rotatably mounted on a rotating shaft 16.
7 is pressed against the outer periphery of the case 5. The curling process is performed by pressing the concave portion of the curling jig 19 attached to the rotating shaft 18 against the open end 4 of the case 5.
The horizontal groove processing and the curling processing are performed by fixing the rotating shafts 16 and 18 of the caulking sesame 17 and the curling jig 19 at predetermined positions and rotating the case 5.

[0005] Incidentally, in order to prevent the outer surface of the case from contacting other electronic parts and causing malfunction, the case is covered with a PVC cover and insulated. However, since covering the Al case with a PVC cover to insulate it impairs productivity, a laminated material in which an Al plate and a thermoplastic nylon resin are laminated instead of the Al plate (Japanese Patent Laid-Open Publication No. HEI 0-1990).
8-1857), and a method of eliminating the step of covering a PVC cover with a coating material obtained by coating an Al plate with a thermoplastic polyester resin (Japanese Patent Application Laid-Open No. 09-275043).

In recent years, with the miniaturization of electronic components, A
1) Electrolytic capacitors have also tended to be miniaturized. For example, chip-type Al electrolytic capacitors that have been miniaturized by eliminating lead wires for surface mounting (chip-on-board) are in practical use. For capacitors, it is extremely difficult to cover the heat-shrinkable tube, so instead of an Al plate, use a laminated material obtained by laminating a thermoplastic nylon resin film on an Al plate, or a coating material obtained by coating a thermosetting epoxy resin on an Al plate. There has been proposed a method of using the heat-shrinkable tube to omit the coating.

[0007]

However, in the case of the laminated material of the prior art, the adhesiveness between the resin film and the Al plate is reduced at the time of caulking, pinholes are generated in the resin film, and the resin film becomes fine during use. Breaking (pinhole breaking) lowers the insulating properties. To prevent this, heat treatment is performed after caulking, resulting in poor productivity. Further, when the laminate is left in a high-temperature and high-humidity atmosphere, there is a problem that the adhesion of the resin film is reduced. On the other hand, the coating material has a problem that when the drawing ratio is increased to about 1.5 to 2.2, the resin film is broken at the time of drawing and the insulating property is reduced. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a resin-coated aluminum material for a capacitor case in which the adhesion of a resin film is good and stable insulation is obtained, and the use of the same. A capacitor case and a capacitor provided with the capacitor case are provided.

[0008]

According to the present invention, in order to solve the above-mentioned problems, a first aspect of the present invention is directed to a resin coating in which a chemical conversion film is provided on an aluminum plate and a resin film is provided thereon. In the aluminum material, the resin film
A polyester resin having a hydroxyl group having a number average molecular weight of 8,000 to 28,000 is prepared by converting a number average molecular weight of 1,000 to 5,000.
A resin-coated aluminum material for a capacitor case, wherein a thermosetting resin film formed by crosslinking with a polyol-modified blocked isocyanate compound is used.

Further, the invention according to claim 2 is characterized in that the polyester resin having a hydroxyl group has a glass transition temperature (Tg) of 40 ° C. to 120 ° C. Material.
Here, the glass transition temperature is a temperature at which the resin transitions from a molten state to a glassy state. At this temperature, freezing or release of a molecular chain segment occurs, and the mechanical, dielectric, and magnetic properties rapidly change. The invention according to claim 3 is the resin-coated aluminum material for a capacitor case according to claim 1 or 2, wherein the thickness of the resin film is 25 μm or less.

According to a fourth aspect of the present invention, there is provided a capacitor case using the resin-coated aluminum material for a capacitor case according to any one of the first to third aspects. The invention according to claim 5 is a capacitor using the capacitor case according to claim 4.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a resin-coated Al material for a capacitor case according to the present invention has a chemical conversion film 2 provided on an Al plate 1 and a resin film 3 provided thereon.
The adhesiveness between the Al plate and the resin film is increased without requiring heat treatment or the like by specifying the type of the resin film 3 in the material.

In the present invention, the resin film is a thermosetting resin film formed by painting and baking a polyester resin having a hydroxyl group and a polyol-modified blocked isocyanate compound (crosslinking agent) which reacts with the hydroxyl group. .

The above-mentioned polyol-modified blocked isocyanate compound is obtained by blocking the terminal isocyanate of a polyfunctionalized and high-molecular-weight isocyanate compound modified with a polyol with a blocking agent. As the isocyanate, TDI (tolylene diisocyanate), MDI (diphenylmethane diisocyanate), HDI (hexamethylene diisocyanate), IDI
PDI (isophorone diisocyanate) and the like.

The blocking agent is selected from various blocking agents having different dissociation temperatures according to various baking conditions. The blocking agent includes acetylacetone and ethyl acetoacetate as active methylenes, phenols as phenols, P-nitrophenol, m-cresol,
Lactams include ε-caprolactam, and alcohols include methyl alcohol, ethyl alcohol, iso-propyl alcohol, and n-benzyl alcohol. The polyol-modified blocked isocyanate compound may be of various types depending on the combination of the isocyanate and the blocking agent. One type may be used alone, or two or more types may be used in combination.

In the present invention, the Al plate is made of pure Al (JI
SA1100) plate, Al alloy (JISA3004 etc.) plate and the like can be used. If the Al surface is roughened in advance, the adhesion between the chemical conversion film and the resin film is improved. For roughening, a method of rolling using a rolling roll having a rough surface, a shot blast method, an electrochemical etching method, or the like can be applied.

In the present invention, the chemical conversion coating is provided between the Al plate and the resin coating to enhance the adhesion between them.
1 and firmly adhere to the resin film.
Specifically, chromate phosphate, chromate chromate,
It is a reaction type chemical conversion film formed with a processing solution such as zirconium phosphate or titanium phosphate, and particularly, a chromate phosphate coating is preferred because it is low in cost and versatile.

In the present invention, the resin film is provided as follows. That is, a polyester resin having a hydroxyl group and a cross-linking agent are mixed, and this mixture is mixed with an aromatic hydrocarbon solvent,
Alcohol solvents, ether solvents, ester solvents,
A paint is formed using a ketone-based solvent or the like as a main solvent or a diluent, and this paint is applied on the chemical conversion film by a roll coater, a blade coater, a spray device, or the like. Coating properties such as viscosity are controlled by adjusting the amount of the solvent.

In the present invention, it is also possible to add a coloring agent to the paint to improve decorativeness, conceal the base, or make use of the base by color clear coating. Inorganic fine particles or an organic lubricant can be added to the resin film to improve drawability. The coating is Al
It is preferable from the viewpoint of productivity to carry out continuously in the coiling step of the plate. After coating, it is preferable to perform a baking treatment to increase the adhesion.

In the present invention, the reason why the number average molecular weight of the polyester resin having a hydroxyl group is specified to 8,000 to 28,000 is that when the number average molecular weight is less than 8000, the elongation of the resin film is reduced and the adhesion is reduced. That's why. Further, when the number average molecular weight exceeds 28,000, when the resin is diluted with a solvent to form a coating, the viscosity of the coating increases and the appearance of the coating surface may deteriorate.

In the present invention, the polyol-modified blocked isocyanate compound has a number average molecular weight of 1,000.
The reason that the number average molecular weight is set to 1000 is
When the number average molecular weight exceeds 5,000, the cross-linking density of the resin film decreases, and depending on the type of the degreasing solvent for cleaning, press oil cleaning after processing is performed if the number is less than 5,000. This is because the resin film may be dissolved or deteriorated in the process.

The polyester resin having a hydroxyl group is as follows:
Those having a glass transition temperature (Tg) of 40 ° C to 120 ° C are particularly preferred. When the glass transition temperature (Tg) is less than 40 ° C., depending on the type of the degreasing solvent for washing, the resin film may be dissolved or deteriorated in the press oil washing step after processing, and the productivity may be greatly reduced. Tg) is 1
If the temperature exceeds 20 ° C., the elongation of the resin film is reduced, and the adhesion may be reduced.

When the thickness of the resin film exceeds 25 μm, the resin film is partially peeled during drawing (so-called “galling”), and the resin film may be broken or peeled during caulking. Therefore, the thickness of the resin film is preferably 25 μm or less. On the other hand, if the thickness of the resin film is less than 2 μm, the resin film may peel or break during drawing, and therefore the thickness of the resin film is preferably 2 μm or more.

[0023]

Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described with reference to Table 1. The present invention examples 1 to 9 in Table 1 have a thickness of 0.3 m.
m aluminum alloy plate (JISA3004) is subjected to degreasing and water washing by a conventional method, then a phosphoric acid chromate conversion coating is provided by a spray method, and the number average molecular weight shown in Table 1 is changed variously within the range of the present invention. A hydroxyl-modified polyester resin is mixed with a polyol-modified blocked isocyanate compound whose number average molecular weight is variously changed within the scope of the present invention as a cross-linking agent, and the resulting mixture is dissolved in a solvent (paint). This was coated and then crosslinked and baked at 230 ° C. (PMT (maximum ultimate plate temperature)) to produce a resin-coated Al material. Next, the resin-coated Al
A blank (a disk having a diameter of 11 mm) was punched out of the material, and after degreased, a volatile lubricating oil G-6284M (trade name: manufactured by Nippon Kogyo Oil Co., Ltd.) was applied to both surfaces thereof. And drawing (drawing ratio [blank diameter / punch diameter] = 2.2) to form a cylindrical case (diameter 5).
mm, height 7 mm). Examples 1 to 9 of the present invention shown in Table 1 are Examples of the invention of Claim 1 and Examples 3 to 5 of the present invention.
Reference numeral 8 denotes an embodiment of the invention according to claim 2, and Examples 1 to 6 of the invention and Examples 8 and 9 of the invention represent embodiments of the invention of claim 3.

In Comparative Examples 1 to 3, cylindrical cases were prepared in the same manner as in the above-mentioned Examples of the present invention, except that the number average molecular weights of the polyester resin having a hydroxyl group and the crosslinking agent were outside the specified values of the present invention. In Comparative Example 4, a cylindrical case was produced in the same manner as in the above-described present invention example, except that a melamine resin was used as a crosslinking agent. In Comparative Example 5, a cylindrical case was produced in the same manner as in the above-mentioned Example of the present invention except that a conventional epoxy resin paint was used as the paint.

For each of the cylindrical cases produced in Examples 1 to 9 of the present invention and Comparative Examples 1 to 5, the adhesion of the resin film was examined by visual observation. In addition, the presence or absence of galling of the resin film was examined. Next, the cylindrical case was subjected to degreasing and boiling in this order, and the adhesion of the resin film after degreasing and after boiling was examined.

The following two commercially available degreasing agents were used. Degreasing agent P: Perchrene (trade name, cleaning agent composed of perchlorethylene and surfactant), Degreasing agent N: NK
Cleaner (trade name: Nippon Kogyo Oil Co., Ltd., cleaning agent comprising a hydrocarbon solvent and a surfactant). Boiling was performed by immersing in boiling pure water for 1 hour. The adhesion of the resin film
Very good (皮膜) if the resin film did not peel at all, good (○) if the resin film only slightly receded, slightly poor (△) if the resin film receded significantly, and peeled the resin film Alternatively, a broken sample was determined to be defective (x).

Furthermore, the cleaning solution resistance of the degreased cylindrical case was examined. The washing liquid resistance was evaluated by the degree of sticking when the cases were brought into close contact with each other. If the cases did not adhere at all, the wash resistance was extremely good (◎), if they were slightly adhered but could be easily separated, they were good (○). X). Table 1 shows the results. Table 1 shows the Tg of the polyester resin having a hydroxyl group,
The number average molecular weight and the resin film thickness of the polyester resin having a hydroxyl group and the crosslinking agent are also shown.

[0028]

[Table 1]

As is clear from Table 1, Examples 1 to 9 of the present invention.
In each case, the adhesiveness of the resin film and the washing liquid resistance were good, and were suitable as resin-coated Al materials for capacitor cases. However, in Examples 1 and 2 of the present invention, the glass transition temperature (Tg) of the resin film was low, so that the cleaning liquid resistance was slightly inferior when the degreasing agent P was used. In Example 6 of the present invention, the thickness of the resin film was small, and in Example 9 of the present invention, the Tg of the polyester resin having a hydroxyl group was high. In Example 7 of the present invention, since the resin film was thick, the adhesion of the resin film was somewhat reduced, and the resin film after drawing was slightly galled. However, slight defects in Examples 1, 2, 6, 7, and 9 of the present invention did not hinder practical application.

On the other hand, in Comparative Example 1, since the number average molecular weight of the hydroxyl group-containing polyester resin is small, and in Comparative Example 2, the number average molecular weight of the crosslinking agent is small. did. In Comparative Example 3, since the number average molecular weight of the cross-linking agent was large, the cross-linking density was lowered, and in particular, the resin film adhesion and the cleaning liquid resistance of the degreasing agent P were deteriorated. In Comparative Example 4, a melamine resin was used as a cross-linking agent, so that a very hard portion was microscopically formed in the resin film, and a large residual stress was generated at the interface between the resin film and the chemical conversion film after drawing, and the adhesion was high after degreasing and after boiling. Was inferior. In Comparative Example 5, since the resin film was an epoxy resin (conventional product), the adhesion of the resin film was poor.

[0031]

Second Embodiment A second embodiment of the present invention will be described with reference to Table 2. Using the case obtained by drawing the resin-coated Al material (Examples 1 to 9 in Table 1) manufactured in Example 1 above, the above-described capacitor shown in FIG. With respect to the capacitor, the pinhole breakage and peeling state of the coating film in the swaged portion were observed, and the quality was determined. When the number of pinhole breaks or the number of peelings of the coating film is 0, the adhesion is extremely good. When the number of breaks or the number of peelings is 1 to 5, the result is good (○). △), 11 or more were determined to be poor. There is no practical problem if it is almost good (良好) or more. Table 2 shows the results.

[0032]

[Table 2]

As is clear from Table 2, Examples 1 to 9 of the present invention
In each case, the adhesion of the coating film (resin coating) was good, and there was no practical problem. The capacitor prepared in Example 2 was incorporated in an electronic circuit and used in a high-temperature, high-humidity atmosphere. However, the coating did not peel off, and good performance was stably obtained.

[0034]

As described above, the resin-coated aluminum material of the present invention is provided with a chemical conversion film on an aluminum plate, on which a polyester resin having a hydroxyl group having a number average molecular weight of 8000 to 28,000 and a number average molecular weight are formed. Molecular weight 10
Since a thermosetting resin film composed of a polyol-modified blocked isocyanate compound having a molecular weight of from 5000 to 5000 is provided, the resin film has good adhesion and stable insulating properties can be obtained without requiring heat treatment. Therefore, the resin-coated aluminum material of the present invention is of high quality and excellent in productivity, and has a remarkable effect when used for an aluminum electrolytic capacitor case or the like. Further, the present invention can obtain a capacitor case without pinhole breakage or resin film breakage by using such a resin-coated aluminum material as a capacitor case, and further, a capacitor provided with this capacitor case, This has an effect that good characteristics can be stably obtained without causing pinhole breakage in the resin film or peeling of the resin film by caulking.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing an embodiment of a resin-coated Al material for a capacitor case of the present invention.

FIG. 2 is an explanatory longitudinal sectional view of a capacitor.

FIG. 3 is a development view of a capacitor element.

FIG. 4 is an explanatory view of a caulking method of a capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Al plate 2 Chemical conversion film 3 Resin film 4 Open end 5 Capacitor case 6 Capacitor element 7 Rubber sealing body 8 Side groove 9 Anode foil 10 Cathode foil 11 Separator 12 Lead wire of anode foil 13 Lead wire of cathode foil 14 Tab of anode foil 15 Tab of cathode foil 16 Rotation axis of caulking sesame 17 Caulking sesame 18 Rotation axis of curling jig 19 Curling jig

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C23C 22/33 C23C 22/33 22/83 22/83 28/00 28/00 Z (72) Inventor Sato Masatoshi 1-167 Higashi-Ome, Ome-shi, Tokyo F-term (reference) in Nippon Chemi-Con Corporation 4D075 BB73X CA13 CA23 CA47 DA06 DB07 DC19 EA07 EA19 EB35 EB52 EB53 4F100 AA04 AB10A AB31 AK01C AK41C AK51E BAE EBA EBAE BAH EJ05 EJ052 EJ48 EJ482 EJ68B EJ69 EJ691 EJ85 EJ851 GB16 GB41 JA05C JA07C JG04 JM02B 4K026 AA09 AA22 AA25 BA03 BA07 BA12 BB05 BB09 CA16 EB08 4K044 AA06 AB02 AB03 CA15 BC17 BA21 BB09

Claims (5)

[Claims] 1. A resin-coated aluminum material having a conversion coating provided on an aluminum plate and a resin coating provided thereon, wherein the resin coating has a number average molecular weight of 800
A resin-coated aluminum material for a capacitor case, comprising a thermosetting resin film obtained by crosslinking a polyester resin having a hydroxyl group of 0 to 28,000 with a polyol-modified blocked isocyanate compound having a number average molecular weight of 1,000 to 5,000. 2. The resin-coated aluminum material for a capacitor case according to claim 1, wherein the polyester resin having a hydroxyl group has a glass transition temperature (Tg) of 40 ° C. to 120 ° C. 3. The resin-coated aluminum material for a capacitor case according to claim 1, wherein the thickness of the resin film is 25 μm or less. 4. A capacitor case, wherein the resin-coated aluminum material for a capacitor case according to claim 1 is used. 5. A capacitor using the capacitor case according to claim 4.