JPH01108717A - Capacitor - Google Patents

Abstract

PURPOSE:To obtain the title capacitor having low degree of variation per day on tan delta and electrostatic capacitance, especially the variation per day in high humidity, and also having high dielectric breakdown voltage by a method wherein the capacitor is composed of the layer consisting of phenoxy resin and polyisocyanate biaxially oriented polyester fiber and vapor-deposited metal layer. CONSTITUTION:The title capacitor is mainly composed of a layer A consisting of phenoxy resin and polyisocyanate, a biaxially oriented polyester film B, and a vapor-deposited metal layer C. The layer A consisting of phenoxy resin and polyisocyanate is formed by coating the solution, which is obtained by mixing phenoxy resin and polyisocynate in the ordinary state of solution, and by evaporating the solvent in a heated atmosphere of 70-200 deg.C. The biaxially oriented polyester film is the film formed in such a manner that a polyester polymer is melted and extruded, and after it is molded into sheet form, it is orientated and a heat treatment is conducted thereon. The vapor-deposited metal layer C is the thin film metal layer formed in such a manner that aluminum, zinc, copper or their alloy is vapor deposited.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an improved capacitor,
More specifically, the dielectric loss tangent (hereinafter referred to as
This relates to a capacitor whose value (referred to as tan δ) does not change.

[Prior Art] Capacitors are known in which a so-called metallized polyester film, in which metals such as aluminum and zinc are deposited on a biaxially oriented polyester film, is wound or laminated.

[Problems to be Solved by the Invention] However, the above conventional capacitors had the following drawbacks.

(2) Tan δ changes with oral administration, and especially in a high temperature and high humidity atmosphere, tan δ not only increases in a relatively short period of time, but also tends to fluctuate.

(2) Furthermore, as time passes, the capacitance decreases, making it impossible to obtain a stable capacitance.

[Means for solving the problem] The present invention is characterized in that it mainly consists of a layer (A) consisting of a phenoxy resin and a polyisocyanate, a biaxially oriented polyester film (B) and a vapor-deposited metal layer (C). It is related to capacitors.

The polyester in the present invention is a polymer compound having an ester bond in the main chain of the molecule obtained by polycondensation of a dicarboxylic acid and a diol. Typical polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc. , and those copolymerized with comonomers such as terephthalic acid, isophthalic acid, adipic acid, sebacic acid, diethylene glycol, polyethylene glycol, and polytetramethylene glycol. Particularly preferred for the present invention is polyethylene terephthalate (hereinafter referred to as PET).

This polyester may contain known additives such as stabilizers such as phosphorous acid and its esters, powders such as titanium dioxide, particulate silica, calcium carbonate, talc, and kaolin as lubricants.

The biaxially oriented polyester film (B) referred to in the present invention is a biaxially oriented polyester film obtained by melt-extruding the above polyester polymer, forming it into a sheet shape, stretching it in the direction of the two wheels, and subjecting it to heat treatment. The polyester film may be stretched by either a sequential two-wheel stretching method in which the polyester film is stretched in the longitudinal direction and then in the transverse direction, or a simultaneous two-wheel stretching method in which the polyester film is stretched simultaneously in the longitudinal and transverse directions.

The thickness of the polyester film is preferably 0.2 to 2 μm, more preferably 0.2 to 1.5 μm.

The centerline average roughness (Ra) of the surface of the biaxially oriented polyester film is preferably 0.015 to 0.05.

Further, it is preferable that at least one side of the polyester film is subjected to a corona discharge treatment, and a metal is deposited on the surface. When performing corona treatment, the atmospheric gas has an oxygen concentration of 0.
．． It is preferable to carry out the reaction in an atmosphere containing 1% by volume or less of nitrogen, carbon dioxide, argon, or the like. Moreover, the applied energy of corona discharge is preferably about 1 to 6 KJ/1TI2.

The vapor-deposited metal layer (C) of the present invention is aluminum,
It is a thin metal layer formed by vapor deposition of zinc, copper, or an alloy thereof. Although the vapor deposition method is not particularly limited, for example, electric heating melting vapor deposition method, ion beam vapor deposition method, sputtering method, etc. can be used. Further, the thickness of the deposited film is preferably in the range of 10 to 5000,
If this is expressed as a film resistance in the case of an aluminum film, it is 1~
It is in the range of about 10Ω/mouth.

The phenoxy resin referred to in the present invention is represented by the general formula % (1) (where R1 to R7 are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms). Typical examples thereof are resins represented by R1, R2=CH3, and R3 to R7=H.

The polyisocyanate referred to in the present invention refers to a compound containing two or more isocyanate groups per molecule, such as tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, 4,4°, 4"
-Triisocyanate Triphenylmethane, a condensate of 3 moles of hexamethylene diisocyanate and 1 mole of trimethylolpropane, and various other isocyanate compounds.

A layer (A>) consisting of a phenoxy resin and a polyisocyanate of the present invention is a layer formed by coating a solution obtained by mixing a phenoxy resin and a polyisocyanate in a normal solution state.
The process is completed by evaporating the solvent in a heated atmosphere at ℃ to form a film.

The mixing ratio of the phenoxy resin and the polyisocyanate is preferably 0.8 to 2.
．． The range is more preferably 0°9 to 1.5 than 0.01.

A layer consisting of phenoxy resin and polyisocyanate (C
) is preferably 1 μm or less and has a ratio of 0°1 to 1.0 with respect to the thickness of the polyester film.

The repeating unit of the layer structure of the layer (A) consisting of the phenoxy resin and polyisocyanate of the present invention, the biaxially oriented polyester film (B) and the vapor-deposited metal (C) is (A
) layer/(C) layer/(B) layer//(A) layer/(C) layer/(
B) layer, (A) layer/(B) layer/(C) layer//(A) layer/
(B) layer/(C) layer, (A) layer/(C) layer/(B) layer/
(C) layer/(A) layer//(B) layer, (C) layer/(B) layer/(C) layer//(A) layer/(B) layer/(A) layer, (C)
Layer/(B) layer//(A) layer/(C) layer/(B) layer/(A
) layer, preferably (A) layer/(C) layer/(B) layer.
layer //(A) layer/(C) layer/(B) layer, (A) layer/(B)
) layer/(C) layer//((A) layer/(B)1!!/(C)
layer, more preferably (A) layer/(C) layer/(B
) layer//(A) layer/(C) layer/(B) layer (here, / indicates a layer interface formed by vapor deposition or coating, and // indicates a layer between two films. The layers are superimposed to form a capacitor element (showing the thermally bonded layer interface).

When the thickness of the biaxially oriented polyester film of the present invention is thin, for example, 0.2 to 2.0 μm, the laminated state of the polyester film and polyolefin film is required to facilitate processing steps such as vapor deposition, coating, and slitting. The laminated film shown in is preferred. The laminated structure of the laminated film is preferably polyester film/polyolefin film or polyester film/polyolefin film/polyester film. The melting point of the polymer for the polyolefin film is preferably in the range of 110 to 140°C, and specifically, ethylene/propylene copolymer, butylene/propylene copolymer, ethylene/butylene/propylene copolymer, etc. are suitable. .

Next, a specific example of the method for manufacturing the capacitor of the present invention will be explained.

A non-oriented sheet is obtained by extrusion molding polyethylene terephthalate containing particulate silica. Alternatively, the PE
T and the ethylene-propylene copolymer are melt-extruded using separate extruders, and the melts are combined to form a three-layer structure of PET/ethylene-propylene copolymer/PET to obtain a laminated non-oriented sheet. The sheet is heated to a temperature of 80-120°C, stretched 3-5 times in the longitudinal direction, and then stretched 90-1
The film is heated to a temperature of 30° C., stretched 3 to 5 times in the transverse direction to achieve biaxial orientation, and then heat treated at a temperature of 190 to 230° C. to obtain a biaxially oriented polyethylene terephthalate film. When performing heat treatment, relaxation treatment is performed in the lateral direction, if necessary. This film is set in a vacuum evaporation device, and metals such as aluminum and zinc are evaporated to form one metal layer.

Alternatively/or the film is set in a coating device, coated with a mixed solution of phenoxy resin and polyisocyanate, heated with heated air at 70 to 200°C for 5 to 300 seconds to evaporate the solvent, and then coated with a mixed solution of phenoxy resin and polyisocyanate. form a layer. The laminated film obtained in this way is slit into small widths, two of these are stacked and wound to make a capacitor element, and then heat-pressed, taped, metallized, voltage treated, both end faces sealed,
Attach lead wires and use it as a capacitor.

[Measurement method] The measurement method related to the present invention will be explained below.

(1) Thickness of film and thickness of layer (C) consisting of phenoxy resin and polyisocyanate The film is pasted on a glass support in a wrinkle-free state, and the surface is roughened using a stylus. Place the film on the scale ((C)
Measure the step at the boundary between the area (where there is no layer) and the area where the film is present (where the (C) layer is present), and calculate the average value of the 10 measurements as the film thickness (the area where the (C) layer is present). thickness).

(2) Capacitor tan δ increase rate (Δtan δ) and capacitance decrease rate (ΔC) 1.2 μm or less polyethylene terephthalate film with vapor deposited layer (11 films, electric resistance of vapor deposit film: 2 Ω/hole, or/or phenoxy resin and A layer of polyisocyanate is provided, a 3 μF wound capacitor is made by a conventional method, this capacitor is placed in an atmosphere at 85°C, and D
Charge C50V/μ and hold for 500 hours. From the tan δ and capacitance C value after 500R, the rate of change with respect to the initial tan δ and capacitance is expressed in %.

(3) Capacitor breakdown voltage (BDV) 1.2μm
Below is a layer deposited on biaxially oriented polyethylene terephthalate (
Electrical resistance of the AQ film and vapor deposited film = 2 Ω/mouth, or a layer made of phenoxy resin and polyisocyanate is provided, a capacitor element with a capacitance of 3 μF is made by a conventional method, and this element is hot pressed, Electrodes are provided using metallic contacts to create a wound capacitor. This capacitor is charged at a boost rate of 50V/sec, and the voltage at which the capacitor breaks down is divided by the thickness of the laminated film.
Let it be the V value.

[Example] Hereinafter, embodiments of the present invention will be described based on Examples.

Examples 1-3. Comparative Examples 1 to 2 Polyethylene terephthalate (IV: 0.62, containing 0.5% by weight of fine particle silica with an average particle size of 0.3μ) was supplied to an extruder, melted at 280°C, and discharged from the die in the form of a sheet. The mixture was allowed to adhere to and solidify on a drum cooled to 25°C.

This cast sheet was stretched 3.5 times in the longitudinal direction at 95°C and stretched 3.4 times in the width direction at 100°C.
The film was heat-treated for 6 seconds while being relaxed by 4% in the width direction to obtain a two-wheel stretched film with a thickness of 1.2 μm.

The thus obtained film is vapor-deposited and/or coated to form (A) layer/(B) layer/(C) layer, (
A) layer/(C) layer/(B) layer, (C) layer/(B) layer/(
A laminated film of layer C), (A) layer/(B) layer/(A> layer) was obtained. Carbide Co., Ltd.) and polyisocyanate ("Coronate" HL, manufactured by Nippon Polyurethane) (reaction equivalent ratio: 1:1°1) were applied, air-dried for 2 seconds at 70°C, and then heated with hot air at 130°C. So 10
The treatment was carried out for 2 seconds to form a layer with a thickness of 0.3 μm.

Slit each film to 1 cm width (margin 20°51
11111) L/, two sheets of film are wound together, Table 1
A capacitor element (capacitance 3 μF) having a repeating unit of the layer structure shown in FIG. The capacitor element is heat-pressed by a conventional method (temperature: 150°C, pressure 4kMad, time: 30 minutes), electrodes are attached to both ends of the capacitor element, and a DC voltage of 100V/μ (film thickness) is applied to both ends for 1 second. It was applied, self-healed, and turned into a capacitor. Breakdown voltage (BDV) of this capacitor, △tanδ, Δ
C is shown in Table 1.

From the above results, it can be seen that the capacitor characteristics are improved by making the layer made of phenoxy resin and polyisocyanate have the hardness of the present invention.

Examples 4-7. Comparative example 3 The following two types of raw materials (bellets) were prepared.

PET: IVo, 62, containing 0.5% by weight of wet synthetic silica with an average particle size of 0.3 μm.

EPC: Ethylene propylene random copolymer with an ethylene content of 6.5% by weight These two types of raw materials were fed to separate extruders and heated at 280°C.
The melts were melt-extruded, and the respective melts were combined in a T-type nozzle to form a three-layer structure of PET/EPC/PET, which was wound around a cooling drum at 25° C. and cooled and solidified.

This sheet was stretched 5 times in the longitudinal direction at 110°C, then 4.5 times in the width direction at 110°C, and then heat treated at 215°C for 4 seconds while relaxing 5% in the width direction, and then laminated biaxially. It was made into a stretched PET film. The thickness of the EPC layer film is 7
The extrusion amount of the PET layer was changed and the thickness of the PET film was adjusted as shown in Table 2.

After vacuum-depositing aluminum (metal film resistance 2Ω/hole) on the PET surface of the film, phenoxy resin (
A mixed solution of phenoxy resin PKI-1) (manufactured by Union Carbide Co., Ltd.) and polyisocyanate ("Coronate" HL, manufactured by Nippon Polyurethane Industries (LI)) (reaction equivalent ratio 1:'1.1) was applied, and 70 After air drying at ℃ for 2 seconds,
It was treated with hot air at 130°C for 10 seconds. Slit this laminated film into 1cm width (margin 0.5mm) L/,
While peeling off the PET vapor deposition film from the EPC layer surface,
These two films were wound using an element winding machine to produce a capacitor element (capacitance: 3 μF). The repeating unit of the layer structure of the capacitor element is (A) layer/(C) layer/(B) layer/
/(A) layer/(C) layer/(Ba8).

The capacitor element is heat-pressed by a conventional method, electrodes are attached to both ends of the capacitor element, and a DC voltage of 100 V/cm is applied to both ends of the capacitor element.
μ (film thickness) was applied for 1 second to perform self-healing treatment and form a capacitor.

Breakdown voltage (BDV) of this capacitor, Δtan
δ and ΔC were as shown in Table 2.

Example 8 Nitrogen 9 was added to the surface of the biaxially oriented laminated PET film obtained based on Example 5 at an oxygen concentration Q of less than 1% IVO.
Corona discharge treatment was performed under a mixed gas of QVOI% and carbon dioxide gas of 10vo+%. The surface wetting tension of the film after the discharge treatment was 54 dyne/cm. The film was coated with a mixed solution of phenoxy resin and polyisocyanate in the same manner as in Example 5, and then made into a capacitor.
The results of measuring the properties are shown in Table 2.

From the above results, it can be seen that the effects of the present invention are increased by subjecting the surface of the biaxially oriented polyester film of the present invention to a corona discharge treatment and forming a film that is vapor-deposited on the surface of the film.

Comparative Example 4 An organic solvent solution of bisphenol-type polycarbonate was applied to the surface of the vapor-deposited two-wheel stretched polyethylene terephthalate laminate film obtained based on Example 5, and dried by heating with open hot air to give a film thickness of 0. It was set to 2 μm. A capacitor was made using the laminated film according to Example 5.

The capacitor characteristics were as shown in Table 2.

[Effect of the invention] The ultra-thin film capacitor according to the present invention has a tan δ
It has little change in capacitance over time, especially under high humidity, and has a high dielectric breakdown voltage.

Claims (1)

[Claims] (1) Layer (A) mainly consisting of phenoxy resin and polyisocyanate, biaxially oriented polyester film (
A capacitor, characterized in that it consists of (B) and a vapor-deposited metal layer (C).