JPH09267434A - Metallized film and capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent capacitor excellent in the impregnation property with insulating layer, reduced in the lowering of insulating capacity caused by long-term charge under a high temp. and high voltage condition and keeping tanδ, ΔC characteristics by using a metallized film. SOLUTION: This metallized film is obtained by vapor-depositing a metal on at least the single surface of a biaxially stretched polypropylene film. In this case, this biaxially stretched polypropylene film contains 0.02-0.1 pts.wt. of an epoxy compd. and the m.p. peaks thereof by a scanning type differential calorimeter are two or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor comprising a metal vapor deposition film and a metal vapor deposition film used for the same.

[0002]

2. Description of the Related Art A metallized film capacitor (hereinafter referred to as an MF capacitor) having a vapor-deposited metal layer made of Al, Zn or the like as an electrode has a self-recovery function, and the withstand voltage can be increased by winding the metallized film together. Therefore, it is widely used because it can be downsized. As a film used for this MF capacitor, a biaxially oriented polypropylene film is often used because of its good temperature characteristic of dielectric loss. Also for oil impregnated capacitors,
In particular, for oil-impregnated metallized film capacitor applications using a metallized film as a dielectric, a film whose surface is roughened to secure an oil layer between film layers is used, and as insulating oil, mineral oil, vegetable oil, Aromatic hydrocarbon oils are often used.

[0003]

When a metallized polypropylene film capacitor as described above is charged with electricity for a long period of time, the dielectric strength of the polypropylene film decreases with the passage of time, and the power factor decreases due to an increase in tan δ. I had a problem.

For example, Japanese Unexamined Patent Publication No. 3-70114 proposes a capacitor in which a roughened film is impregnated with an impregnating agent. However, the present inventors were not necessarily satisfied as the insulator strength as described later.
The present invention is intended to solve such problems,
That is, an object of the present invention is to obtain a practical MF capacitor that can improve the electric resistance and can be miniaturized and have a long life.

[0005]

The present invention refers to a film obtained by vapor-depositing a metal on at least one side of a biaxially oriented polypropylene film, wherein the biaxially oriented polypropylene film contains an organic compound having a chlorine-capturing ability. 02% ~
A metallized film containing 0.1% by weight and having two or more melting point peaks as measured by a scanning differential calorimeter.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The biaxially oriented polypropylene film in the present invention means MFR (Melt Flow R).
aate) is a film biaxially stretched using a polymer having a rate of 1 to 10 g / min (temperature: 230 ° C., load: 2.16 kgf), which is biaxially stretched by either a simultaneous or sequential method. If Other than the homopolymer, it may be a copolymer of propylene and another α-olefin polymer (for example, ethylene, butene, etc.), or a blend of polypropylene and another α-olefin polymer.

In the case of the present invention, a polymer is particularly preferable, and the isotacticity (hereinafter referred to as II) is 96.
% Or more is particularly preferable. In addition to epoxy, various known additives such as heat stabilizers, antioxidants, and crystal nucleating agents can be added to the polymer.

It is essential that the film of the present invention contains 0.02% to 0.1% by weight of an organic compound having a chlorine capturing ability, and preferably 0.04% to 0.0%.
8%. If the content is less than 0.02%, the effect of the addition is not obtained, and the dielectric strength is lowered during long-term voltage application, and sometimes dielectric breakdown occurs. If the content exceeds 0.1%, the film surface tends to become sticky when the content is high.

The organic compound having a chlorine-capturing ability refers to an organic compound which reacts with chlorine or chlorine ions, and typical examples of the organic compound include an epoxy compound and an unsaturated compound, among which an epoxy compound is particularly preferable.

The film of the present invention has a melting point peak of 2 when measured by a scanning differential calorimeter (hereinafter referred to as DSC).
It is necessary to have more points. A melting point peak of 2 points or more means having a peak of 2 points or more between 125 and 175 ° C. When the melting point peak is less than two points, it is not possible to obtain a surface roughened surface or a shape sufficient for permeating the insulating oil, which leads to early destruction of the capacitor.

In the film of the present invention, it is preferable that at least one surface has an average roughness Ra of 0.1 μm to 0.4 μm. If Ra is less than 0.1 μm, the slipperiness is poor, and wrinkle defects are generated during film production and during capacitor production, and there is a high possibility of dielectric breakdown due to local electric field concentration. When Ra exceeds 0.4 μm, the substantial thickness decreases, and there is a high possibility that the dielectric breakdown will be low. A more preferable range of Ra is 0.15 μm to 0.35
μm.

In the present invention, the film resistance of the metal film is preferably in the range of 1 Ω / □ to 40 Ω / □, more preferably 3 Ω / □ to 12 Ω / □. Membrane resistance is 1
If it is less than Ω / □, clearing of the vapor-deposited metal film at the time of dielectric breakdown of the polypropylene film becomes insufficient, which may lead to destruction of the capacitor. If it exceeds 40 Ω / □, there is a possibility that problems such as disappearance of the metal vapor deposition film may occur due to the influence of moisture in the air or in the insulating oil. The metal to be vapor-deposited is most preferably aluminum, zinc, copper or an alloy, but is not limited thereto. Specific examples of the alloy include aluminum / zinc, zinc / copper, etc., but are not limited thereto.

The withstand voltage of the capacitor using the metallized film of the present invention is further increased by using the impregnating agent. Examples of the impregnating agent include oil, solidified impregnating agent, gas and the like.

In the present invention, as an excellent oil immersion agent, there may be mentioned a mixture of an electrically insulating compound having two aromatic rings which is liquid at room temperature and a natural fatty acid glyceride which is a vegetable oil. The mixture was impregnated with an insulating oil obtained by mixing 30% to 70% by weight of a synthetic oil having two aromatic rings and 70% to 30% by weight of a natural fatty acid glyceride which is a vegetable oil. It must be a thing. When the synthetic oil having two aromatic rings exceeds 70% by weight, the film swells and cracks occur in the deposited film.
There is a high possibility that the increase in tan δ and the decrease in capacity will be large.
On the other hand, if the mixing ratio of natural fatty acid glyceride exceeds 70%, the viscosity of the insulating oil becomes high and unimpregnated parts may be formed, or tan δ may increase due to the influence of the insulating oil. Typical synthetic oils having two aromatic rings are diarylalkanes, alkylbiphenyls, and alkylnaphthalenes.

A preferred diarylalkane is represented by the following formula.

[0016]

Embedded image Here, n and m are integers of 0 to 3 and m R
₁ and n R < ₂ > are hydrogen atoms, the same or different C1-C6 alkyl groups, or cycloalkyl groups. R ₃ is a divalent hydrocarbon residue derived from a saturated hydrocarbon having 1 to 6 carbon atoms such as methane, ethane, propane and cyclohexane.

An example of the method for producing a metallized biaxially oriented polypropylene film for capacitors of the present invention will be described below. However, the present invention is not limited to the following manufacturing method.

A polypropylene resin containing an epoxy compound is supplied to an extruder, and the molten polymer is discharged from a die and wound around a cooling roll kept at 30 to 95 ° C. to be cooled and solidified for molding.

Then, it is preheated in an oven kept at 125 to 150 ° C. or in contact with a roll to be preheated, stretched 3 to 6 times in the longitudinal direction, and then cooled.

This film was introduced into a tenter maintained at 155 to 175 ° C., stretched 6 to 12 times in the width direction, and
Heat treatment is carried out at a temperature of 50 to 160 ° C. while relaxing about several percent to obtain a biaxially stretched film for capacitors.

Thereafter, the film surface is subjected to corona discharge treatment in air or various gases at 5 to 50 W / m ² / min.

In the case of a composite film, a method in which a plurality of extruders are used to laminate a plurality of films in a short tube or a die and co-extrude and stretch them, or after stretching in the longitudinal direction, extrusion lamination and width There is a method of stretching in the direction.

The above-mentioned width 630 whose surface is corona-discharge treated
Copper metal was used as a nucleus-forming metal on the corona discharge treated surface of a product having a size of mm × 11,000 m, and a metallized film obtained by vapor deposition of zinc was used.

[0024]

[Measurement Method of Physical Properties] Next, terms and measurement methods used in the present invention will be described.

(1) Melting point peak in DSC Using a DSK-II type scanning differential calorimeter manufactured by PERKIN ELMER, 1st r obtained under the following measurement conditions:
The melting point peak at un was defined as the melting point peak at DSC.

Sample amount: 5 mmg Range: 5 mcal / sec Temperature rising rate: 20 ° C./min Sensitivity Sensitivity: 10 mV

(2) Surface roughness Ra According to JIS-B-0601. However, the cutoff at that time was 0.25 mm. For the measurement, a three-dimensional roughness measuring machine ET-30HK manufactured by Kosaka Laboratory Ltd. was used.

(3) Withstanding Voltage A 3 μF capacitor element was prepared using a Zn metal vapor deposition film and immersed in an oil impregnating agent under vacuum. This impregnated capacitor element was used in an atmosphere of 90 ° C under a voltage of 1.6 kV for 2
The continuous charge test for 000 hours was set to 5 pieces / 1 level. Disassemble the capacitor after charging, take out the film sheet, place this film sample on the copper plate with the vapor deposition surface on top,
Apply a DC voltage with the copper plate as the anode and the deposition surface as the cathode, and
The same voltage is applied for 0 seconds. After that, the voltage is increased by 500 V, and the number of locations where dielectric breakdown occurs at each voltage is counted. 5 / m
^{2 The} generated voltage was used as the dielectric breakdown voltage value.

⊚: No damage to the capacitor in a 2000-hour charging test
And the breakdown voltage is 70% or more of the non-powered product ratio. ○: The breakdown of the capacitor is 0 in the power test for 2000 hours.
And the breakdown voltage is 40 to less than 70% of the non-powered product. △: One capacitor is destroyed in the 2000-hour power test or the breakdown voltage is 30 to 40% of the non-powered product.
%: X: Two or more capacitors destroyed in the 2000 hours voltage application test, or the breakdown voltage is 20% compared to non-voltage applied products.
It is as follows.

(4) tan δ The above-mentioned capacitor before being disassembled but before being disassembled is manufactured by SOKEN Co., Ltd.
Automatic Shaling Bridge DAC-PSC-20
Using W, t at a frequency of 60 Hz and a voltage of 200 V
It was defined as an δ value.

[0031]

【Example】

Example 1 PP raw powder (II 98.3 obtained by polymerization and post-treatment in solvent-free liquefied propylene with ultra-high activation catalyst)
%) As an antioxidant "Irganox" 1010
1000 ppm (manufactured by Ciba Geigy), BHT (manufactured by Yoshitomi Pharmaceutical Co., Ltd.) 4000 ppm, and 800 ppm of a cycloaliphatic epoxy resin CY179 (manufactured by Ciba Geigy) were blended, melted and kneaded by an extruder, and then pelletized to obtain a base material. The MFR of this pellet was 1.5 g / min.

80% by weight of an ethylene / propylene random copolymer having an ethylene content of 1.2% by weight, which was polymerized by a gas phase method using a Ziegler type catalyst, and "Philips".
System catalyst [Silica-alumina carrier with chromium oxide attached (SiO ₂ -Al ₂ O ₃ -CrO ₃ ). The carrier is 90% silica, 10% alumina is particularly effective. The amount of chromium is preferably 13% by weight. 20% by weight of high-density polyethylene polymerized by the solvent method
1000 p of "Irganox" 1010 to the mixture
pm, BHT 4000 ppm, and cycloaliphatic epoxy resin CY179 were mixed at 1000 ppm, melted and kneaded by an extruder, and then pelletized, and this raw material was used as a surface layer raw material.
The MFR of this pellet was 5.6 g / 10 min.

The above-mentioned base raw material was supplied to one extruder and the surface layer raw material was supplied to another extruder, coextruded from one die at a temperature of 270 ° C., and wound on a chill roll at 45 ° C. to form a sheet. The sheet was stretched 4.5 times in the length direction with a heating roll at a temperature of 145 ° C., and then stretched 10.5 times in the width direction with a tenter heated to a temperature of 173 ° C.
The film surface was heat-treated while relaxing at 5 ° C., and the film surface was corona-treated. The thickness obtained in this way is 16 μm
After winding the film, width 620mm x length 1100
The product was cut to 0 m. Surface roughness Ra of this film
Is 0.23 μm, and the number of melting point peaks by DSC is 2
Was individual.

Zinc metal was adjusted to a film resistance of 8 Ω / □ on this product and vapor-deposited on the corona-treated surface. This vapor-deposited product was cut into a width of 100 mm × 3500 m to obtain a vapor-deposited product. Two of the above reels were wound in layers to form seven capacitor elements having a capacity of 3 μF.

This capacitor element was impregnated with the impregnating agent SUS60 to obtain an impregnated capacitor. The five capacitors were placed in an oven maintained at an ambient temperature of 90 ° C for 1.6
An AC voltage of kV was applied, and a long-term voltage application test was performed for 2000 hours. The remaining two pieces were subjected to a destructive test of unpowered products.

As shown in Table 1, the test results show that there is no breakdown of the capacitor during voltage application, and the dielectric breakdown value after voltage application is 90% of that of the non-voltage applied product, and it has excellent withstand voltage characteristics. It was The tan δ and ΔC were also excellent properties.

Example 2 The procedure of Example 1 was repeated except that the tenter temperature was set to 168 ° C. and stretching was performed in the width direction. The results are shown in Table 1 as in Example 1.
It was just as good as.

Example 3 The same as Example 1 except that the resistance value of the deposited film was 5 Ω / □. As shown in Table 1, the results were excellent as in Example 1.

Example 4 The procedure of Example 1 was repeated except that the tenter temperature was set to 176 ° C. and stretching was performed in the width direction. The results are shown in Table 1 as in Example 1.
It was just as good as.

Comparative Example 1 Example 1 was repeated except that the chill roll temperature was set to 80 ° C. by using only the base material. The results are as shown in Table 1.
The surface of the film is smooth and wrinkles occur on the evaporation reel,
In a long-term voltage test, one capacitor was destroyed. In addition, the dielectric breakdown value after voltage application was as low as 35% of non-voltage applied products.

Comparative Example 2 Example 1 was repeated except that the content of the cycloaliphatic epoxy resin CY179 (manufactured by Ciba Geigy) was increased to 0.2%. As shown in Table 1, the capacitor characteristics were excellent, but the surface of the vapor deposition reel was dirty and the product appearance was poor.

Comparative Example 3 Example 1 was repeated except that the cycloaliphatic epoxy resin CY179 (manufactured by Ciba Geigy) was not added. As shown in Table 1, two capacitors were destroyed in the long-term voltage application test.

[0043]

[Table 1]

[0044]

As described above, the metallized film of the present invention has the following effects. It is a metallized film that has excellent impregnation properties with insulating oil, and has little deterioration in insulation performance due to long-term application of electricity at high temperature and high voltage.
It is possible to obtain an excellent capacitor that maintains the characteristics.

Claims (11)

[Claims] 1. A film obtained by vapor-depositing a metal on at least one surface of a biaxially oriented polypropylene film, wherein the biaxially oriented polypropylene film contains 0.02% to 0.1% by weight of an organic compound having a chlorine capturing ability. A metallized film which is contained and has two or more melting point peaks as measured by a scanning differential calorimeter. 2. The metallized film according to claim 1, wherein the organic compound having a chlorine capturing ability is an epoxy compound. 3. The biaxially oriented polypropylene film has an average surface roughness Ra of 0.1 μm to 0.4 on at least one side.
The metallized film according to claim 1 or 2, wherein the metallized film has a thickness of µm. 4. The metallized film according to claim 1, which has a metal layer having a film resistance of 1 to 40 Ω / □. 5. A capacitor obtained by winding and laminating the metallized film according to any one of claims 1 to 4. 6. The capacitor according to claim 5, further comprising an impregnating agent. 7. The capacitor according to claim 6, wherein the impregnating agent is oil. 8. The capacitor according to claim 7, wherein the oil is a mixture of a rapeseed oil and a synthetic oil having two aromatic rings. 9. A ratio of mixing a synthetic oil having two aromatic rings with rapeseed oil is 30% to 70% by weight / 70% to 30%.
The capacitor according to claim 8, wherein the capacitor is parts by weight. 10. The capacitor according to claim 6, wherein the impregnating agent is a gas. 11. The capacitor according to claim 10, wherein the gas is SF ₆ .