JP2002075778A - Film for capacitors and film capacitors - Google Patents

Abstract

(57) [Summary] [Problem] A vapor deposition film for a capacitor and a film capacitor capable of preventing invasion of substances such as water vapor and air from the outermost layer of a film capacitor and reducing deterioration of the capacitor characteristics due to decomposition of the substance. provide. Kind Code: A1 A vapor-deposited film for a capacitor having a non-conductive metal layer on one or both sides of a base film, which is used as a film wound around the outermost layer of a film capacitor element. An adhesive layer is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metallized film for a film capacitor used by being wound around the outermost layer of a capacitor element, and a film capacitor using the metallized film for a film capacitor.

[0002]

2. Description of the Related Art Conventionally, various plastic films have been used as a film wound around the outermost layer of a film capacitor element. Generally, the same material film as a base film of a vapor deposition film forming a capacitor has been used. . In some cases, the base metal film of the vapor-deposited film forming the capacitor is wound around the outermost layer of the film capacitor element by blowing off the electrode metal on the outermost layer of the film capacitor element by an electrical process called burn-off.

[0003] Conventionally, the film capacitor has no tension applied to the film at the end of the winding of the film capacitor element forming the capacitor due to its manufacturing method.
Since a gap is generated between several layers in the outermost layer and the capacitor characteristics are easily deteriorated, a film wound around the outermost layer of the film capacitor element is disclosed in Japanese Patent Application Laid-Open No. Hei 7-161573.
And high heat shrink films proposed in Japanese Patent Application Laid-Open No. 8-298226 and JP-A-8-298226.

[0004] However, due to the above-mentioned problem of the film capacitor manufacturing method, water vapor or oxygen that penetrates through the film on the outermost layer during the process or during use of the film capacitor, when the voltage is applied to the capacitor, causes the outermost layer to have several layers. The corona electric field concentrates in the voids formed between the layers and decomposes due to the electric field, and the electrode metal becomes non-conductive, or water vapor or oxygen reacts with the electrode metal of the film capacitor to impair the conductivity, resulting in static electricity of the capacitor. Decrease capacity.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems by preventing invasion of substances such as water vapor and air from the outermost layer of a film capacitor and reducing deterioration of capacitor characteristics. To provide a capacitor film that can be used.

Another object of the present invention is to provide a film capacitor using the above-mentioned film for a capacitor, in which deterioration of the capacitor characteristics is reduced.

[0007]

A film for a capacitor according to the present invention, which achieves the above object, is a film having a nonconductive metal layer on one or both sides of a base film as a film wound around the outermost layer of a film capacitor element. The non-conductive metal layer can be suitably formed by vapor deposition.

The capacitor film of the present invention preferably has a water vapor transmission rate of not more than 5.0 g / m ² for 24 hours at 40 ° C. and 90% RH.
More preferably, the oxygen permeability is 5.0 cc / m ² or less for 24 hours at 20 ° C. and 95% RH. Further, in order to minimize voids in the outermost layer of the film capacitor element, it is preferable that one surface is coated with a heat bonding coating.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The film for a capacitor and the film capacitor of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a general structure of a film capacitor.

In FIG. 1, generally, a film capacitor is formed by laminating two vapor-deposited films 3 each serving as an electrode having a non-vapor-deposited portion called a margin on a core body 4, winding a predetermined length, and then forming an adhesive layer 2. The film 1 to be wound around the surface layer is wound 3 to 10 times to form a capacitor winding element.

A metal spray called metallikon 10 is applied to both ends of the capacitor-wound element, and a lead wire for lead-out of electrodes is attached thereon by soldering or the like, and then an exterior 5 is applied.

The film for a film capacitor of the present invention is a film used by being wound around the outermost layer of the above-mentioned film capacitor element, which prevents moisture and air from entering the surface layer of the film capacitor and decomposes the substance by a corona electric field. It is necessary to have a non-conductive metal layer on one or both sides of the film in order to make the electrode metal non-conductive when charging and discharging the film capacitor for a long time by the ions generated in the film, and to reduce the decrease in capacitance. is there.

FIG. 2 is a structural view illustrating a film capacitor of the present invention, and FIG. 3 is a cross-sectional structural view illustrating a film wound around the outermost layer of the present invention.

In FIG. 2, a vapor-deposited film 3 serving as an electrode having a non-vapor-deposited portion is wound around a core 4 by a predetermined length, and a film 1 'wound around the outermost layer of the present invention is wound thereon. , And a capacitor winding element. Metallicon 1 is placed at both ends of this capacitor winding element.
0, and a lead wire 7 for extracting an electrode is attached to the metallikon 10 by soldering or the like.

In FIG. 3, (a) shows the base film 9
Is provided with a non-conductive metal layer 8 on one side, and an adhesive layer 2 is provided on the opposite side.

In (b), a non-conductive metal layer 8 is provided on one side of a base film 9. Here, an example in which the non-conductive metal layer 8 is provided on one side is shown. However, the non-conductive metal layer 8 is not limited to one side, and the adhesive layer 2 is also formed on the non-conductive metal layer 8. It may be.

The substrate film of the capacitor film of the present invention is preferably a thermoplastic resin film such as a polyester film or a polypropylene film having a thickness of preferably 9 to 25 μm, but the material is not particularly limited. .

Examples of the material constituting the non-conductive metal layer of the present invention include metal oxides such as aluminum oxide, zinc oxide and copper oxide, but the material is not particularly limited. In the present invention, the non-conductive metal layer is suitably formed by vapor deposition.

The non-conductive metal layer prevents moisture and air from entering the surface layer of the film capacitor intended in the present invention, and can control the water vapor transmission rate and the oxygen transmission rate by its film thickness.

In the present invention, when a voltage is applied to the film capacitor, water vapor and the like interposed in the outermost layer of the film capacitor element is decomposed, thereby corroding the electrode metal of the film capacitor and reducing the capacitance of the capacitor. In order to reduce that, or because the conductivity of the electrode metal of the film capacitor is not impaired by reacting with water vapor or air, the water vapor transmission rate of the film for a capacitor of the present invention wound around the outermost layer of the film capacitor element is At a temperature of 40 ° C. and 90% RH for 24 hours, preferably 5.0 g / m ² or less, more preferably 1.0 g / m ^2.
Less and, the oxygen permeability is preferably at 20 ° C., 24 hours under RH 95% 5.0cc / m ² or less, and more preferably not more than 1.0 cc / m ^2. The water vapor transmission rate and the oxygen transmission rate can be changed by changing the film thickness of the non-conductive metal layer. These values are preferably as small as possible in order to prevent adverse effects due to invading moisture and the like. A film thickness of from 10 to 500 angstroms, preferably from 70 to 400 angstroms, is preferred.

A heat treatment is performed to stabilize the characteristics of the film capacitor. At the time of the heat treatment, one of the vapor-deposited films for the film capacitor is used to minimize voids in the outermost layer of the element due to heat shrinkage of the film. Is coated with a polymer having a crystalline melting point of −10 ° C. to 180 ° C., preferably 0.5 to 3 μm, as an adhesive, to provide an adhesive layer. Is preferred.

The material of the adhesive layer 2 is not limited to the above-mentioned polymer material, but any material can be used as long as it is a material which can be bonded by heating, which is generally used for the outermost layer of a capacitor element.

The film for a capacitor of the present invention is used by being wound around the outermost layer of a film capacitor.

[0025]

The present invention will be described in more detail with reference to the following examples. In addition, each value of the water vapor transmission rate and the oxygen transmission rate in the present invention is a value measured by the following method.

A. Water vapor transmission rate was measured in accordance with JIS K 7129.

B. Oxygen permeability Measured according to JIS K 7126.

(Example 1) A vapor-deposited film for a film capacitor was formed on a polyethylene terephthalate film having a film thickness of # 12 μm by a reactive vapor deposition method (Japanese Patent No. 2136729) using a vacuum vapor deposition machine of Japan Vacuum Engineering Co., Ltd. Is deposited to a thickness of about 500 angstroms to produce a vapor deposited film having a water vapor transmission rate of 3.2 g / m ² or less and an oxygen transmission rate of 2.8 cc / m ² or less,
Further, on the opposite side of the aluminum oxide layer, apply a
The film coated to a thickness of m was slit into a width of 101 mm to form a vapor deposition film for a capacitor to be wound around the outermost layer of the film capacitor element.

On the other hand, the vapor-deposited film for a film capacitor as an electrode is made of Toyo Metallizing Co., Ltd.
Using an aluminum-evaporated polypropylene film with a thickness of 5 μm, a product width of 100 mm, and a margin width of 2.0 mm, the element was wound so that the capacitance was 30 μF (frequency 1 kHz, measurement voltage 5 V), and heat-treated at 105 ° C. for 16 hours.
In a heated state, the above-prepared vapor-deposited film for a capacitor was wound around the element four times, and as a sheath, Sanyuresin Co., Ltd.
Was hardened with an amine-based curing agent to prepare a film capacitor having the structure shown in FIG.

In this way, the film capacitor is
Of which 50 capacitors are AC voltage 10
25 hours of charge / discharge test for 2 hours ON and 2 hours OFF at 80V
After repeating 0 times, each capacitor was disassembled and the number of non-conductive portions generated in the film 0.5 m forming the outermost layer electrode was measured with the naked eye, and the score was measured with the naked eye. Moisture load (10 at 40 ° C, 90%)
(80 V power application) for 1000 hours, and the decrease in capacitance of the capacitor was measured.

The remaining 10 capacitors were subjected to a durability test (applying 1200 VDC at 75 ° C.), and the capacitance reduction of each capacitor was measured.

Comparative Example 1 A vapor deposition film for a capacitor and a film capacitor were manufactured in the same manner as in Example 1 except that the vapor deposition film for a film capacitor in the outermost layer was not used, and the same measurement as in Example 1 was performed. Was performed.

The above results are shown in FIGS. 4, 5 and 6. FIG. 4 is a diagram showing the number of non-conductive portions on the outermost layer of the film capacitor electrode. FIG. 5 is a diagram showing the rate of change in the capacitance of the capacitor during the moisture resistance load test. FIG. FIG. In Example 1, the number of non-conductive portions in the outermost layer 0.5 m of the film capacitor was small from FIG. 4, the capacitance change due to the moisture resistance load was small from FIG. 5, and in the long-term capacitor durability test from FIG. Also obtains stable capacitor characteristics,
It can be estimated that the service life is improved.

On the other hand, in Comparative Example 1, the number of non-conductive portions in the outermost layer of the film 0.5 m was remarkably large, and the change in the capacitance of the capacitor due to the moisture resistance load test and the durability test was large. Conceivable.

[0035]

As described above, the film for a film capacitor of the present invention is a film film to be wound on the outermost layer, and has a non-conductive metal layer on one or both sides thereof. This prevents the intrusion of moisture or air from the electrode film and reduces the corrosion of the electrode metal by ions generated by the decomposition of substances existing in the gaps between the dielectric film layers when the film capacitor is charged and discharged.

In particular, the vapor-deposited film for a film capacitor preferably has a water vapor transmission rate of not more than 5.0 g / m ² at 40 ° C. and 90% RH for 24 hours. 5.0 c in 24 hours under% RH
c / m ² or less, and more preferably, one surface is coated with a coating for thermal bonding, so that stable capacitor characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a general structure of a film capacitor.

FIG. 2 is a structural view illustrating a film capacitor of the present invention.

FIG. 3 is a sectional structural view illustrating a film wound around the outermost layer of the present invention.

FIG. 4 is a diagram showing the number of non-conductive portions generated by a charge / discharge test of the outermost layer of a film capacitor electrode.

FIG. 5 is a diagram of a capacitance change rate of a capacitor during a moisture resistance load test.

FIG. 6 is a diagram showing a change in capacitance of a capacitor during a durability test.

[Explanation of symbols]

 1: Film to be wound on the outermost layer 1 ': Film to be wound on the outermost layer of the present invention 2: Adhesive layer 3: Deposited film forming electrode 4: Core body 5: Exterior 6: Electrode 7: Lead wire 8: Non-conductive metal layer 9: Base film 10: Metallicon

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C08L 101: 00 H01G 4/24 301K (72) Inventor Shinkichi Aihara 33-1, Nagafushi, Mishima-shi, Shizuoka F-term in Toyo Metallizing Co., Ltd. Mishima Plant (Reference) 4F006 AA35 AB73 AB74 BA05 BA06 CA08 DA01 5E082 AB04 BC19 EE07 EE11 EE23 EE37 FF05 FG06 FG35 HH22 HH25 HH30 HH43 HH47 HH48 HH51 PP05 PP06 PP10

Claims (4)

[Claims] 1. A film for a capacitor wound around the outermost layer of a capacitor, wherein the film for a capacitor has a non-conductive metal layer on one or both sides of a base film. 2. A water vapor transmission rate of not more than 5.0 g / m ² for 24 hours at 40 ° C. and 90% RH, and an oxygen transmission rate of 24 g at 20 ° C. and 95% RH. 5 in time.
2. The capacitor film according to claim 1, wherein the content is 0 cc / m ² or less. 3. The capacitor film according to claim 1, wherein a thermal adhesive layer is provided on one of the surfaces. 4. A film capacitor using the film for a capacitor according to claim 1 as an outermost layer of a capacitor-wound element.