JPH09106926A - Metalized polyester film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metalized polyester film capacitor having excellent moisture resistance characteristics using a film in enhanced bond properties between a base material film and evaporated metal. SOLUTION: Within a metalized polyester film capacitor using polyester film having a coating layer at least one on surface as a dielectric, the coating layer fills the role of the metalized polyester film capacitor containing polyester base polyurethane.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to metallized polyester film capacitors. More specifically, the present invention relates to a metal-vapor-deposited polyester film capacitor having excellent wet heat resistance using a film having improved adhesion between a base film and a vapor-deposited metal.

[0002]

2. Description of the Related Art Polyester films typified by polyethylene terephthalate have been widely used as substrate films for capacitors because of their excellent mechanical properties, heat resistance and electrical properties. However, with the development of various electronic devices and the like in recent years, higher characteristics of polyester films have been achieved. As one of the requirements for high performance, there is a demand for long-term resistance to moisture and heat. That is,
The metal vapor-deposited polyester film has a drawback that the adhesiveness between the base film and the vapor-deposited metal, particularly in a high temperature and high humidity environment, that is, the so-called wet heat resistance is poor, and the capacitor is exposed to high temperature and high humidity. When placed, there is a problem that moisture permeation occurs at the interface between the base film and the vapor-deposited metal, and the capacitance of the capacitor decreases over time.Therefore, from the viewpoint of long-term stability, improvement of the moisture and heat resistance of the capacitor is required. It was

Japanese Unexamined Patent Publication No. 4-245414 discloses a metal vapor-deposited polyester film capacitor using a polyester film having a polyester polyurethane coating layer as a capacitor excellent in wet heat resistance.
However, even if the resin composition described in the above publication is used, the polyester polyurethane does not always have sufficient performance in a moist heat environment because the polyester polyurethane has poor hydrolysis resistance. In addition, the recent development of various electronic devices has been remarkable, and along with this, the demand for long-term reliability required for capacitors, in particular, the long-term moisture and heat resistance stability of the capacitor performance has further increased. In addition, the present inventors have found that a metal-deposited polyester film capacitor using a polyester film having a polycarbonate polyurethane coating layer is effective for solving the above-mentioned problems. However, the price of polycarbonate polyurethane is still high and it cannot be put to practical use.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal vapor-deposited polyester film capacitor excellent in moisture and heat resistance using a film having improved adhesion between a base film and a vapor-deposited metal. It is in.

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies in view of the above problems, and as a result, a metal-deposited polyester film capacitor element using a polyester film having a specific coating layer as a dielectric has excellent moisture resistance. They have found that they can exhibit heat resistance, and have reached the present invention.

That is, the gist of the present invention is a metal evaporated polyester film capacitor using a polyester film having a coating layer on at least one side of a polyester film as a dielectric, wherein the coating layer contains a polyether polyurethane. The present invention resides in a metal evaporated polyester film capacitor.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The polyester of the polyester film in the present invention refers to polyethylene terephthalate in which at least 80 mol% of its constituent units are ethylene terephthalate, or
Polyethylene naphthalate having 80 mol% or more of its constituent units being ethylene naphthalate, or poly-1,4-cyclohexane dimethylene terephthalate having 80 mol% of its constituent units being 1,4-cyclohexane dimethylene terephthalate. . Examples of the copolymerization component other than the above-mentioned superior constituent components include diethylene glycol, propylene glycol, neopentyl glycol,
Diol components such as polyethylene glycol and polytetramethylene glycol, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid,
Dicarboxylic acid components such as adipic acid, azelaic acid, sebacic acid and ester-forming derivatives thereof, and oxymonocarboxylic acids such as oxybenzoic acid and ester-forming derivatives thereof can be used.

The polyester film constituting the capacitor of the present invention may contain additive particles, precipitated particles and other catalyst residues forming projections on the film surface within a range not deteriorating the characteristics of the capacitor described later. .
Further, as an additive other than the above-mentioned protrusion forming agent, if necessary, an antistatic agent, a stabilizer, a lubricant, a cross-linking agent, an antiblocking agent, an antioxidant, a colorant, a light blocking agent, an ultraviolet absorber, etc. May be contained within a range that does not deteriorate the capacitor characteristics. The polyester film in the present invention may have a multilayer structure as long as the finally obtained properties satisfy the requirements of the present invention. In the case of a multilayer structure, some of the layers may be other than the polyester layer. The coating layer in the present invention contains polyether polyurethane. Polyurethanes are composed of polyols, polyisocyanates, chain extenders or crosslinkers. The polyether polyurethane in the present invention,
Polyether-based polyol is used as one of the polyols which are the main constituents of polyurethane.

Polyether-based polyols include, but are not limited to, polypropylene glycol, polyethylene glycol, polytetramethylene glycol, and copolymers thereof. Among these polyethers, polyethers having a tetramethylene glycol unit are particularly preferable because they have excellent hydrolysis resistance. The proportion of polytetramethylene glycol in the total polyol is preferably 20% by weight or more, more preferably 30% by weight or more, and most preferably 40% by weight or more. If the proportion of polytetramethylene glycol units is low, desired capacitor characteristics may not be obtained.

Examples of polyisocyanates include toluene diisocyanate, phenylene diisocyanate,
4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate and the like can be mentioned. It is particularly preferred to select from aromatic polyisocyanates and / or isophorone diisocyanates. When using aromatic polyisocyanate and / or isophorone diisocyanate, the proportion of aromatic polyisocyanate and / or isophorone diisocyanate in the isocyanate component is preferably 50 mol% or more, more preferably 70 mol% or more.

Examples of chain extenders or crosslinking agents are ethylene glycol, propylene glycol, diethylene glycol, trimethylolpropane, hydrazine, ethylenediamine, diethylenetriamine, triethylenetetramine, 4,4'-diaminodiphenylmethane,
4,4′-diaminodicyclohexylmethane, water and the like can be mentioned. The resin used for coating in the present invention is preferably a coating agent using water as a medium for safety and hygiene, but within the scope of the present invention, a water-soluble or water-dispersible resin auxiliary agent. May contain an organic solvent.

When water is used as a medium, it may be a coating agent forcibly dispersed with a surfactant or the like, but preferably a hydrophilic nonionic component such as polyethers,
It is a self-dispersion type coating agent having a cationic group such as a quaternary ammonium salt, and more preferably a water-soluble or water-dispersible coating agent having an anionic group. A water-soluble or water-dispersible coating agent having an anionic group is one in which a compound having an anionic group is bonded to a resin by copolymerization or grafting, and sulfonic acid, carboxylic acid, phosphoric acid and the like. It is appropriately selected from salts and the like.

The counter ion of the anionic group is preferably selected from amine-based onium ions containing ammonium ions from the viewpoint of the heat and humidity resistance of the capacitor described later. The amount of anionic groups in the water-soluble or water-dispersible coating agent having anionic groups is preferably 0.05 to 8% by weight. When the amount of the anionic group is less than 0.05% by weight, the water solubility or water dispersibility of the resin tends to be poor, and when the amount of the anionic group exceeds 8% by weight, the water resistance of the undercoat layer after coating is poor. There is a possibility that the films may stick to each other due to moisture absorption or the moisture and heat resistance may be deteriorated. The coating liquid in the present invention contains an isocyanate compound, an epoxy compound, an amine compound, an aziridine compound as a cross-linking agent for improving the adhesion (blocking property), water resistance, solvent resistance and mechanical strength of the coating layer. ,Silane coupling agent,
It may contain a titanium coupling agent, a zirco-aluminate coupling agent, a peroxide, a heat- and light-reactive vinyl compound, a photosensitive resin, and the like.

In order to improve the stickiness and slipperiness of the coating layer, silica, silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, calcium phosphate, titanium oxide, sulfuric acid are used as inorganic fine particles in the coating liquid. Barium, carbon black, molybdenum sulfide, antimony oxide sol, etc., organic fine particles such as polystyrene, polyethylene, polyamide, polyester, polyacrylate ester, epoxy resin, silicone resin, fluororesin, etc. You may contain so that it may become in the range.

Further, if necessary, a defoaming agent, a coating property improving agent, a thickener, an antistatic agent, an organic lubricant, an antioxidant,
It may contain an ultraviolet absorber, a foaming agent, a dye, a pigment and the like. Further, the coating liquid used in the present invention may contain a polyurethane resin other than the resin of the present invention, an acrylic resin, a polyester resin, a vinyl resin, etc. for improving the characteristics of the coating liquid or the coating layer. Good. In particular, the polyester resin is preferably used because it improves the interlayer wet heat resistance adhesion between the base polyester film and the coating layer. However, the proportion of the polyester resin in the coating layer is preferably 30% by weight or less.

The proportion of the polyether polyurethane in the coating layer is usually 10% by weight or more, preferably 20% by weight or more, more preferably 30% by weight or more, based on the solid content.
Most preferably, it is 50% by weight or more. If the proportion of polyether polyurethane in the coating layer is low, desired capacitor characteristics may not be obtained. The content of alkali metal in the coating liquid used in the present invention is preferably 1000 ppm or less, more preferably 5 ppm, in the solid content of the coating liquid.
It is at most 00 ppm, most preferably at most 20 ppm. When the content of alkali metal in the coating liquid increases,
The moisture and heat resistance of the capacitor tends to deteriorate. Especially when applying DC voltage to the capacitor and placing it under high temperature and high humidity,
It is known that the capacitance of the capacitor is drastically reduced, and a desired coating liquid may be obtained by performing deionization treatment as needed.

As a method for applying the above-mentioned coating solution to a polyester film, Yuji Harazaki, Maki Shoten, issued in 1979, "River roll coater", "gravure coater", "rod coater", "air doctor coater" or the like is shown in "Coating method". Using a coating device other than
A method of applying the coating liquid outside the biaxially stretched polyester film production process, and more preferably, a method of applying the coating liquid inside the film production process can be mentioned. As a method of applying in the film manufacturing process, a coating solution is applied to a polyester unstretched film, and sequentially or simultaneously, a method of biaxially stretching,
There is a method in which it is applied to a uniaxially stretched polyester film and then stretched in a direction perpendicular to the uniaxially stretched direction, or a method in which it is applied to a biaxially stretched polyester film and further stretched in the transverse and / or longitudinal direction. The above-mentioned stretching step is preferably performed at 60 to 130 ° C., and the stretching ratio is at least 4 times or more, preferably 6 in terms of area ratio.
~ 20 times. The stretched film is 150-250
Heat treated at ℃.

Further, the maximum temperature zone of heat treatment and / or
Alternatively, it is preferable that the cooling zone at the exit of the heat treatment relaxes 0.2 to 20% in the longitudinal direction, the lateral direction, or both directions. Particularly, it is 2 by the roll stretching method at 60 to 130 ° C.
The coating solution is applied to a uniaxially stretched polyester film stretched 6 times to 6 times, and the polyester uniaxially stretched film is immediately dried at 80 to 130 ° C. in a direction perpendicular to the previous stretching direction, with or without suitable drying. Stretched 6 times, 15
A method of performing heat treatment at 0 to 250 ° C. for 1 to 600 seconds is preferable. According to this method, the coating layer can be dried simultaneously with stretching, and the thickness of the coating layer can be thinned according to the stretching ratio, and a film suitable as a polyester film substrate can be manufactured at a relatively low cost. . The coating liquid in the present invention may be applied to only one side of the polyester film, or may be applied to both sides. When coated on only one side, a coating layer other than the coating liquid of the present invention may be formed on the opposite side, if necessary, to give other properties to the polyester film.

The film may be subjected to a chemical treatment or a discharge treatment before the coating in order to improve the coating property and the adhesive property of the coating agent on the film. Further, in order to improve the adhesiveness and coatability of the coating layer of the biaxially stretched polyester film of the present invention, the coating layer may be subjected to a discharge treatment after the coating layer is formed. The thickness of the coating layer is preferably 0.01 to 3 μm. The thickness of the coating layer is preferably thin in view of the demand for miniaturization of the capacitor, and the upper limit of the coating thickness is preferably 3 μm.
m, more preferably 1 μm, most preferably 0.5 μm
m. However, if the thickness of the coating layer is too thin, it is difficult to obtain a uniform coating layer, and coating unevenness easily occurs in the product. The lower limit of the coating thickness is preferably 0.01 μm, more preferably 0.02 μm, and most preferably 0. 0.03 μm
And The water droplet contact angle of the coating layer formed as described above is preferably 60 ° or more. Water droplet contact angle is 6
If it is less than 0 °, the water-resistant adhesion to the metal vapor deposition film is deteriorated, and it becomes difficult to provide the capacitor of the present invention with wet heat resistance. Therefore, attention must be paid to the amount of hydrophilic groups, the amount of emulsifiers, and the amount of hydrophilic compounds of the coating and coating agent.

The center line average roughness (Ra) of the coating layer surface formed as described above is preferably 0.005 to 5.
0.5 μm, more preferably 0.01 to
0.3 μm, most preferably 0.02
The range is 0.1 μm. When Ra is less than 0.005 μm, the slipperiness of the film is insufficient and workability tends to deteriorate. On the other hand, if Ra exceeds 0.5 μm, the surface tends to be too rough, and the resulting capacitor tends to have poor wet heat resistance and withstand voltage characteristics. In the present invention, examples of the metal to be vapor deposited include aluminum, palladium, zinc, nickel, gold, silver, copper, indium, tin, chromium and titanium, and the most preferable metal is aluminum. The above-mentioned metals include metal oxides. The thickness of the metal vapor deposition film is preferably in the range of 1 to 500 nm. The vapor deposition method is generally a vacuum vapor deposition method, but may be an electroplating method, a sputtering method, or the like.

The metal vapor deposition layer may be provided on both sides of the polyester film. After the metal deposition, a surface treatment of the deposited metal layer or a coating treatment with another resin may be performed.
Two metal-deposited polyester films thus obtained are superposed and wound (including a double-sided metal-deposited polyester film and another film including the polyester film according to the present invention) or a plurality of layers are laminated. A capacitor element can be produced by a conventional method, and for example, heat pressing, taping, metallikon, voltage treatment, both end surface sealing, and lead wire attachment can be performed to obtain a capacitor, but the capacitor is not limited to these. It is not done. From the viewpoint of long-term reliability of the capacitor, the capacitor according to the present invention changes in capacitance after being left in an atmosphere of temperature 60 ° C. and humidity 95% RH for 1000 hours while applying a DC voltage of 60 V / μm between its electrodes. The rate is preferably -10% ~
A capacitor in the range of 10%, more preferably,
It is a capacitor in the range of -5% to 5%.

[0022]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. In addition, the evaluation method in an Example is as follows. In Examples and Comparative Examples, "part" means "part by weight". (1) Centerline average roughness (Ra) It was determined as follows using a surface roughness measuring device (SE-3F) manufactured by Kosaka Laboratory Ltd. That is, the reference length L (2.55 mm) from the film section curve in the direction of the center line
The part of is drawn out, and the center line of this extracted part is the x-axis,
When the roughness curve y = f (x) is represented with the direction of the longitudinal magnification as the y-axis, the value given by the following equation is represented by [μm]. The center line average roughness is obtained by obtaining a sectional curve of 10 sample film surfaces,
The average value of the center line average roughness of the extracted portion obtained from these sectional curves was expressed. The tip radius of the stylus is 2μ.
m, the load was 30 mg, and the cutoff value was 0.8 mm.

[0023]

(2) Water Droplet Contact Angle A contact angle meter (CA-DT-A type, manufactured by Kyowa Interface Science Co., Ltd.) was used to measure the contact angle between the sample film and distilled water in an atmosphere of temperature 23 ° C. and humidity 50% RH. ) Was used for the measurement. The contact angle is
A total of six points were measured at two points on the left and right and three points on the sample, and the average value was determined as the contact angle. The diameter of the water droplet was 2 mm,
The number after minutes was read.

(3) Change in capacitance No-load test A capacitor was left in an atmosphere of 85 ° C. and 85% RH for 500 hours, and the capacitance change rate was calculated using the initial capacitance as a reference value. That is, the value obtained by subtracting the initial capacitance from the capacitance after 500 hours was divided by the initial capacitance and expressed as a percentage. Load test While applying a DC voltage of 60V / μm between the electrodes of the capacitor, leave it in an atmosphere of temperature 85 ° C and humidity 85% RH for 500 hours, and obtain it as the rate of change in capacitance with the initial capacitance as the reference value. It was That is, the value obtained by subtracting the initial capacitance from the capacitance after 500 hours was divided by the initial capacitance and expressed as a percentage.

Example 1 (Production of polyester film) Polyethylene terephthalate having an intrinsic viscosity of 0.66 containing 0.3% of silica particles having an average particle size of 1.2 μm was melt extruded at 290 ° C. to obtain an amorphous sheet, After stretching 4.2 times in the direction of 90 ° C. in the direction, 100 parts of polyurethane A having the composition shown in Table 1 below (solid content weight, the same applies below) synthesized according to a conventional method, and a coating solution containing water as a medium is applied to both surfaces of the film. After coating, the film is transversely stretched at 110 ° C. by 3.9 times and heat-treated at 230 ° C. to obtain a biaxially stretched polyester film having a coating layer thickness of 0.05 μm and a base polyester film thickness of 5 μm. It was The content of alkali metal in the coating liquid was 5.0 ppm of Na and 1.8 ppm of K in terms of solid content of the coating liquid, and other alkali metals were below the detection limit. Further, the contact angle of water drop of the coating layer is 63 °, and the center line average roughness (R
a) was 0.025 μm.

(Manufacture of Capacitor) On the coated surface of the obtained film, a resistance heating type metal vapor deposition apparatus was used, and the pressure in the vacuum chamber was set to 10 ⁻⁴ Torr or less, and aluminum of 45 n
It was vapor-deposited to a thickness of m. At that time, the polyester film was vapor-deposited in a stripe shape having a margin portion in the longitudinal direction (a vapor deposition portion width of 8 mm and a margin portion width of 1 mm were repeated). The obtained vapor-deposited polyester film was slit into a 4.5 mm width tape shape having a margin of 1 mm on the left or right. The obtained left and right margin vapor-deposited polyester films were wound one by one to obtain a wound body. At this time, the two films were wound while being shifted so that the vapor deposition portion protruded by 0.5 mm in the width direction. This wound body is heated at a temperature of 150.
Pressed at kg / cm ² for 5 minutes. After applying a lead wire after spraying metallikon on both end surfaces of the wound body after pressing, impregnated layer with liquid bisphenol A type epoxy resin, and a minimum thickness of 0.5 mm by heating and melting the powdery epoxy resin. An exterior was formed to obtain a film capacitor having a capacitance of 0.1 μF. The obtained metal vapor-deposited polyester film capacitor was, as shown in Table 1, a metal vapor-deposited polyester film capacitor having excellent moisture and heat resistance. The results of Examples and Comparative Examples described below are also summarized in Table 2 below.

Comparative Example 1 Example 1 was repeated except that the coating solution was not applied.
A metal-deposited polyester film capacitor was obtained in the same manner as in. The obtained capacitor was compared with Example 1 and
It was inferior in moist heat resistance. Examples 2 to 5 Metal-deposited polyester film capacitors were obtained in the same manner as in Example 1 except that the polyether polyurethanes A to E of Example 1 were coated with polyether polyurethanes B to E having the following compositions. Example 6 Hydran AT-15 (trade name), which is a polyether polyurethane manufactured by Dainippon Ink and Chemicals, Inc., is used as the polyurethane F instead of the polyether polyurethane A of Example 1.
A metal-deposited polyester film capacitor was obtained in the same manner as in Example 1 except that 100 parts was applied.

Example 7 The same as Example 1 except that 100 parts of Olestar UD500 (trade name), which is a polyether polyurethane manufactured by Mitsui Toatsu Co., was used as the polyurethane G instead of the polyether polyurethane A of Example 1. Then, a metal evaporated polyester film capacitor was obtained. In addition, Hydran A
T-15 and Olestar UD500 are polyether polyurethanes having polytetramethylene glycol as a main polyol, toluene diisocyanate as a main polyisocyanate, carboxylate group as a hydrophilic functional group, and an amine compound as a counter ion thereof. is there.

Comparative Example 2 Hydran AP40 (trade name) 1 which is a polyester polyurethane manufactured by Dainippon Ink and Chemicals, Inc. was used as polyurethane H instead of the polyether polyurethane A of Example 1.
A metal-deposited polyester film capacitor was obtained in the same manner as in Example 1 except that 00 parts was applied.

[0031]

[Table 1] (In Table 1, TDI is toluene diisocyanate, PTM
G is polytetramethylene glycol (molecular weight 200
0), PEG is polyethylene glycol (molecular weight 200
0), NPG is neopentyl glycol, DMPA is dimethylolpropionic acid, TMP is trimethylolpropane, and TEA is triethylamine.)

[0032]

[Table 2]

[0033]

The metal-deposited film capacitor of the present invention has excellent resistance to moisture and heat, can contribute to the improvement of long-term reliability of the capacitor, and has a high industrial value.

Claims (2)

[Claims] 1. A metal vapor-deposited polyester film capacitor using a polyester film having a coating layer on at least one side as a dielectric, wherein the coating layer contains polyether polyurethane. . 2. The metallized polyester film capacitor according to claim 1, wherein the polyether forming the polyether polyurethane contains polytetramethylene glycol.