JP2002164249A - Dielectric film for capacitor and the capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric film for a capacitor, whose hygroscopic property is superior when compared to that of the conventional techniques and reduction of electrostatic capacity is stabilized, and a capacitor using the dielectric film for a capacitor. SOLUTION: The dielectric film for a capacitor has a metal oxide layer, which consists of at least one kind of metal belonging to the third to sixth periods of group II, group III or group IV of the periodic table short periodic table, in at least one side of a base plastic film. As the metal, Al, Si, Ti, Ba or Ca is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric film for a capacitor which is excellent in low hygroscopicity and has improved electric characteristics, and a capacitor using the dielectric film for the capacitor.

[0002]

2. Description of the Related Art Hitherto, a dielectric film for a capacitor in which a thermoplastic resin layer is provided on a polyester film and a capacitor using the same have been known. For example, JP-A-10-74663 discloses that one or both sides of a plastic film have a glass transition point of 0 ° C or higher and 40 ° C or lower.
A thermoplastic resin composition mainly comprising the following thermoplastic resin, having a glass transition point of not less than 60 ° C. and not more than 80 ° C. and containing not less than 10% by weight and not more than 30% by weight, and having a thickness of 0.2 μm. There is disclosed a dielectric plastic film for a capacitor provided with a thermoplastic resin layer having a thickness of 1.0 μm or less. According to this, air voids can be sufficiently eliminated at the time of pressing after winding the dielectric film and the electrodes during the production of the capacitor, and the capacitance is not reduced due to the interposition of the air voids. However, even with this method, there is a disadvantage that water is present due to moisture absorption of the plastic film (particularly polyethylene terephthalate film), and there is still room for improvement. In particular, moisture often enters from a deposition margin (portion where no deposition is performed).

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to use a dielectric film for a capacitor, which has a reduced hygroscopicity and an improved capacitance reduction as compared with the prior art, and a dielectric film for the capacitor. It is to provide a condenser.

[0004]

As a result of intensive studies by the present inventors, the object of the present invention has been industrially advantageously achieved by the present invention having the following constitution.

[1] At least one surface of a base plastic film is composed of two, three or four genera of the periodic table.
A dielectric film for a capacitor comprising a metal oxide layer comprising an oxide of at least one metal belonging to the third to sixth periods of the genus.

[2] The dielectric film for a condenser according to [1], wherein the metal is at least one of l, Si, Ti, Ba and Ca.

[3] The thickness of the metal oxide layer is 10 to 5
The dielectric film for capacitors according to the above [1] or [2], which has a thickness of 00 nm.

[4] The dielectric film for a capacitor according to any one of the above [1] to [3], having a layer of a low softening point polymer satisfying the following formula on at least one surface of the base plastic film.

Formula 70 <T ₁ −T ₂ <230 T ₁ : Softening point of base film polymer (° C.) T ₂ : Softening point of low softening point polymer (° C.) [5] Polymer having low softening point is formed from copolymerized polyester A dielectric film for a capacitor according to the above [4].

[6] A dielectric film for a capacitor obtained by alternately laminating the dielectric film for a capacitor according to any one of [1] to [5] and a plastic film on which a metal vapor-deposited film is formed.

[7] A capacitor using the dielectric film for a capacitor according to any one of [1] to [6].

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The dielectric film for a capacitor according to the present invention is provided on at least one surface of a base plastic film, in the second to third or fourth genus of the periodic table.
It is a capacitor dielectric film provided with a metal oxide layer made of an oxide of at least one metal belonging to the sixth period.

The base plastic film used in the present invention is not particularly limited as long as it has coating and vapor deposition processing aptitude. Typical examples include polyethylene terephthalate, polybutylene terephthalate, and polybutylene. Examples of the film or sheet include a polyester such as 6-naphthalate, a polyolefin such as polyethylene and polypropylene, a polyamide such as 6-nylon and 12-nylon, a homopolymer or a copolymer such as aromatic polyamide and polyimide.

There is no problem even if various additives such as an antistatic agent, a lubricant and an antioxidant are added to the polymer or copolymer constituting the base plastic film. The thickness of the base plastic film is not particularly limited, but is preferably about 0.5 to 100 μm in consideration of appropriate machining such as vapor deposition, and more preferably 3 to 100 μm.
２５25 μm.

The metal oxide constituting the metal oxide layer of the present invention may be a third, second, third or fourth group of the periodic table.
To at least one metal belonging to the sixth period. Among them, in order to improve the capacitor characteristics,
oxides such as l, Si, Ti, Ba, and Ca are preferable;
Particularly, aluminum oxide or silicon oxide is preferably used.

In the present invention, a metal oxide layer is provided on one or both sides of a base plastic film. The formation of the metal oxide layer on the base plastic film can be preferably performed by a vacuum deposition method. As the vacuum deposition method, any of known methods such as a heating evaporation method, a sputtering method, and an ion plating method can be used. As the vacuum deposition method, a continuous winding method is usually employed industrially, but it is needless to say that a single-wafer method may be used.

In the present invention, the thickness of the vapor-deposited layer, which is a metal oxide layer, can be arbitrarily set depending on the required characteristics.
It is desirable to set in the range of nm in consideration of general necessary properties such as low water absorption and productivity, and more preferably 10 to 10 nm.
The range is 100 nm.

In the present invention, a metal layer can be further provided on the metal oxide layer. As metal, A
l, Zn, Si, Ti, Ba, Ca, Cu and the like are preferable, and aluminum or zinc is particularly preferably used. The thickness of the metal layer can be set preferably in the range of 10 to 100 nm.

In the present invention, it is preferable to further provide a low softening point polymer layer on the metal oxide layer.

As the polymer having a low softening point, polyester resins, polyurethane resins, polyolefin resins and the like are usually used. Polyester resins are preferred from the viewpoint of electrical characteristics and industrial availability. Polyester resin,
For example, it can be industrially synthesized by a conventional polymerization reaction of a polyvalent carboxylic acid such as terephthalic acid or isophthalic acid with a polyvalent hydroxy compound such as ethylene glycol or 1,2-propylene glycol.

The low-softening point polymer used in the present invention is particularly preferably a copolymerized polyester, and the dicarboxylic acid component constituting the copolymerized polyester is, for example, terephthalic acid, isophthalic acid, phthalic acid, or the like.
Examples thereof include 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and acid. Examples of the aliphatic dicarboxylic acid include straight-chain, branched and alicyclic dicarboxylic acids, such as sulfuric acid. acid,
Examples thereof include malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecaic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and diglycolic acid.

The dicarboxylic acid component can be used alone or in combination of two or more. Among these, it is preferable to use an aromatic dicarboxylic acid component such as terephthalic acid and isophthalic acid. Further, as the glycol component, ethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol,
Propylene glycol, polyalkylene glycol having a molecular weight of 400 to 20,000, 13-propanediol,
1,3-butanediol, 1,4-butanediol,
1,5-pentanediol, 2-ethyl-2-butyl-
1,3-propanediol, 2,2,4-trimethyl-
1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,
1,4-cyclohexanedimethanol, 2,2,4,4
-Tetramethyl-1,3-cyclobutanediol, 4,
Examples thereof include 4'-dihydroquinobiphenol, 4,4'-methylenediphenol, 4,4'-isopropylidenediphenol, 1,5-dihydroquininaphthalene, bisphenol A, bisphenol S, and ethylene oxide adducts thereof. These glycol components are 1
Species or two or more species can be used in combination.

Further, in the low softening polymer used in the present invention, silicon oxide, calcium carbonate and / or aluminum oxide having an average particle diameter of 1 μm or less is preferably used in an amount of 1% by weight or more based on the low softening polymer. % By weight or less.

The glass transition point of the resin as the low softening point polymer is preferably in the range of 0 to 100 ° C. In addition, when a capacitor is made using a resin having a glass transition point of 100 ° C. or higher, air and the like easily remain between layers of the resin and the electrode metal. Lower. More preferably, the glass transition is desirably in the range of 15 to 70 ° C.

The low softening point polymer used in the present invention is
It is preferable that the polymer has a low softening point satisfying the following formula.

Formula 70 <T ₁ −T ₂ <230 T ₁ ; Softening point of base film polymer (° C.) T ₂ ; Softening point of low softening point polymer (° C.) For example, the range of softening point of low softening point polymer is , 30-2
It is preferably in the range of 30 ° C., more preferably 9 ° C.
The range is 0 to 180 ° C. By satisfying the above expression, the adhesiveness is improved. The low softening point polymer layer can be formed by a gravure coater, a reverse coater, or the like. Further, the thickness of the low melting point polymer layer is preferably 0.1 to 3.0 μm from the viewpoint of adhesive strength and blocking.
When forming a low softening point polymer layer, even if one kind of resin is used alone, a mixture of two or more kinds of resins or silicon oxide, calcium carbonate and aluminum oxide having an average particle diameter of 1 μm or less can be used as a low softening point polymer. On the other hand, it is preferable that the content is 1% by weight or more and 20% by weight or less, and a multilayer composite may be used.

The dielectric film for a capacitor of the present invention is particularly suitable for producing a high-voltage type capacitor.

[0028]

The present invention will be described below with reference to examples. The measurement of each characteristic value in the examples was performed using the following apparatus.

(1) Capacitance change rate (%) For the capacitor element before charging, LCR manufactured by Ando Electric Co., Ltd.
Using a meter (type AG-4311), the capacity is measured in an atmosphere at 25 ° C. under the conditions of a voltage of 1 V and a frequency of 1 KHz. Thereafter, the capacitor element was charged with a voltage of 5 KvDC at a high temperature of 110 ° C. for 2000 hours, and the capacity after charging was measured with an LCR meter made by Ando Electric in the same manner as in the measurement of the initial capacitor capacity.

Example 1 A polyethylene terephthalate film Q51 having a thickness of 8.4 μm manufactured by Toray Industries, Inc. (melting point: 26)
(3 ° C.), a 50 nm aluminum oxide layer was provided on each side using a continuous vacuum evaporation apparatus, and a film on which aluminum was evaporated (50 nm thick) using a continuous vacuum evaporation apparatus was placed on one side. Thickness 8.
4 μm polyethylene terephthalate film Q51
(Melting point: 263 ° C.) Two films provided with an aluminum oxide layer having a thickness of 50 nm were alternately wound on both sides using a continuous vacuum vapor deposition apparatus to produce a dielectric film for a capacitor.

Example 2 A dielectric film for a capacitor was manufactured in the same manner as in Example 1 except that SiO ₂ was used for metal deposition.

[Examples 3 to 5] On one side of a laminated wrapping polyethylene terephthalate film provided with an aluminum oxide layer on both sides of Example 1, 50% mol% of terephthalic acid as an acid component as a low softening point polymer, and isophthalic acid 2
Using a gravure coater, 0.2 g of a copolymer solution having a softening point of 163 ° C., comprising 0 mol%, 30 mol% of sebacic acid, 50 mol% of a neobentyl glycol component and 50 mol% of an ethylene glycol component as glycol components, was used.
/ M ² (Example 3), 0.5 g / m ² (Example 4), 1.
Coating was performed so as to have a thickness of 0 g / m ² (Example 5), the coated surface and the vapor-deposited surface were overlapped, and two sheets were alternately wound together to produce a dielectric film for a capacitor.

Comparative Example 1 A polyethylene terephthalate film Q51 having a thickness of 8.4 μm manufactured by Toray Industries, Inc. (melting point: 26)
(3 ° C.), a film on which aluminum was deposited using a continuous vacuum deposition apparatus, and a 8.4 μm thick film manufactured by Toray Industries, Inc.
Comparative Example 1 was obtained by alternately winding two polyethylene terephthalate films Q51 (melting point: 263 ° C.) of m.

[Comparative Examples 2 to 4] 8.4 μm thick, manufactured by Toray Industries, Inc.
m of polyethylene terephthalate film Q51 (melting point
263 ° C) on one side using a continuous vacuum evaporation system.
7. A film on which minium has been deposited and a thickness of 8. manufactured by Toray Industries, Inc.
4 μm polyethylene terephthalate film Q51
(Melting point 263 ° C) on one side as terephthalic acid
50% mol%, isophthalic acid 20 mol%, sebacic acid 3
0 mol%, neobentyl glycol as glycol component
50% by mole of ethylene glycol component, 50% by mole of ethylene glycol component
Of a copolymer solution having a softening point of 163 ° C.
0.2g / m using an coater ^Two(Comparative Example 2), 0.
5g / m^Two(Comparative Example 3), 1.0 g / m^Two(Comparative Example 4)
Coated to a thickness, coated surface and aluminum
The two layers were stacked alternately and wound.

Table 1 shows the results of measuring the moisture resistance load obtained in each of the examples and comparative examples. Table 1 summarizes the capacity change rates obtained in Examples 1 to 5 and Comparative Examples 1 to 4. From Table 1, it can be seen that in each of the examples, a result showing a decrease in capacitance exceeding that of each of the comparative examples was obtained.

[0036]

[Table 1]

[0037]

According to the present invention, by providing a base plastic film with a metal oxide, a low hygroscopic property is excellent and a dielectric film for a capacitor and a capacitor with a stable capacitance reduction are produced. can do.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kaori Hirose 33rd Nagafushi, Mishima City, Shizuoka Pref. FG36 MM23 PP06 PP09

Claims (7)

[Claims] 1. A metal oxide comprising, on at least one side of a base plastic film, an oxide of at least one metal belonging to the third to sixth periods of the second, third or fourth group of the periodic table. A dielectric film for a condenser having a layer. 2. The method according to claim 1, wherein the metal is at least one of Al, Si, Ti, Ba and Ca.
The dielectric film for a condenser according to the above. 3. The metal oxide layer has a thickness of 10 to 500 n.
3. The dielectric film for a capacitor according to claim 1, wherein m is m. 4. A low softening point polymer layer comprising a polymer satisfying the following formula, on the metal oxide layer.
4. The dielectric film for a capacitor according to any one of 3. Formula 70 <T ₁ −T ₂ <230 T ₁ : Softening point of base film polymer (° C.) T ₂ : Softening point of low softening point polymer (° C.) 5. The dielectric film for a capacitor according to claim 4, wherein the low softening point polymer comprises a copolymerized polyester. 6. A dielectric film for a capacitor, wherein the dielectric film for a capacitor according to claim 1 and a plastic film on which a metal deposition film is formed are alternately laminated. 7. A capacitor using the dielectric film for a capacitor according to claim 1.