JPH10284339A - Metallized film capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a matellized film capacitor capable of preventing incidence of damage generated in the film manufacturing process and thermal deterioration generated during evaporation and improving dielectric strength and durability of the laminated capacitor manufactured by processing a coated film hardened by an activated energy beam irradiation of a deposited film as a dielectric. SOLUTION: A thermoplastic resin film having a maximum height (Rmax) of its surface 1.5 μm or less and its thickness of 0.3 to 3.0 μm contains 0.01 to 5.0 weight % of a particle A having an average particle size (d50) of 0.3 to 2.0 μm and a particle-size distribution (d25/d75) of 2.0 or less, and has a metal evaporated layer on both its sides. The capacitor is made by laminating films having dielectric layer hardened by irradiation of at least one surface of the metal evaporated layers with an activated energy beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a metallized film capacitor. Specifically, the present invention is a metallized film capacitor using an extremely thin film, the capacitor is obtained by forming a coating layer cured by active energy rays as a dielectric, The present invention relates to a metallized film capacitor capable of preventing troubles such as heat loss of a film in a vapor deposition step and giving high withstand voltage characteristics and durability to both a film and a coating layer.

[0002]

2. Description of the Related Art In recent years, with the development of electronic devices and the like, required characteristics of capacitors used therein have become more severe. Such required characteristics include good electrical characteristics, durability, miniaturization, low cost, and the like. In order to meet such a demand, a so-called multilayer capacitor has recently been used in which an extremely thin film is subjected to vapor deposition, and a dielectric is formed by coating to form an element having a multilayer structure. The film used for such a capacitor must satisfy extremely high required characteristics in addition to being extremely thin. That is, for example, in the case of a thin film having a thickness of 3 μm or less, the roughness of the film surface may be adjusted to an appropriate range in order to improve the handleability and the running property during processing and prevent deterioration in characteristics due to scratches or the like. Required. On the other hand, if the film contains a large amount of particles or contains large particles in order to improve the handleability, the electrical properties and durability will be adversely affected. Therefore, a film that does not adversely affect the electrical characteristics and has excellent handleability is demanded as a dielectric for a small capacitor used in future electronic devices.

[0003] Particularly, electrical characteristics that are strongly required to be improved include withstand voltage characteristics and insulation resistance characteristics, and it is necessary to have advanced characteristics in a wide temperature range from normal temperature to high temperature.
When the film is thin, particularly good withstand voltage characteristics and insulation resistance are required. Factors that have an adverse effect on the withstand voltage characteristics include foreign substances present in the film and uneven thickness. In order to improve the handleability of the film, a method of adding fine particles to the film is employed. However, foreign substances such as aggregates and coarse particles contained in the fine particles affect the withstand voltage characteristics. Furthermore, due to coarse protrusions on the film surface and uneven thickness of the film, the uniformity of the applied dielectric layer may be reduced, and the withstand voltage characteristics may be reduced. From these viewpoints, the surface of the film must be kept extremely uniform and have a specific projection shape.

In recent years, it has been desired to avoid using harmful organic solvents, particularly from the viewpoint of preventing environmental pollution and natural destruction. Even when providing the above-mentioned applied dielectric layer, if an organic solvent is used, it cannot be recovered and volatilizes,
Due to concerns such as leakage, a method that uses a small amount of organic solvent or preferably uses no organic solvent has come to be desired. Under such circumstances, for example, a capacitor using a dielectric coating material that is cured by irradiation with ultraviolet rays as described in Japanese Patent Application Laid-Open No. 7-26193 has been proposed.
In the conventional method using a solvent-containing paint, even when a thin dry film thickness is used, since the solvent is contained at the time of application, the applied thickness can be made relatively thick, and the viscosity of the paint at the time of application is determined by the amount of the solvent. Thus, the coating thickness at the time of drying could be made uniform. However,
In the case of a paint that is cured by irradiation with active energy rays,
It is difficult to improve the uniformity of the thickness of the coating layer because the thickness after curing does not become too thin with respect to the coating thickness, so that an extremely thin coating is required, and the viscosity of the paint is often low. Become. In recent years, since miniaturization of capacitors has been desired, it is necessary to make both the film and the coating layer extremely thin, and it is necessary to highly satisfy such uniformity of the thickness. In particular, the thickness of the coating layer near the protruding portion on the film surface becomes thin, and the problem that the withstand voltage of the coating dielectric decreases tends to occur. It is necessary to maintain a specific shape in which no large protrusion exists on the film surface. .

Heretofore, with respect to a capacitor using such a special paint, the above-mentioned problems have been solved at the same time, and a film capable of highly satisfying electric characteristics such as withstand voltage characteristics has not been obtained. Polyester film among the biaxially oriented thermoplastic resin films has mechanical properties, heat resistance,
Since it has various characteristics such as electrical characteristics and chemical resistance in a highly balanced manner and is excellent in cost performance, it is used for capacitors. Various improvements have been made on the design of the surface shape of the polyester film in various applications.However, a film capable of solving all of the above-mentioned problems in a special application such as the present invention has not been known, and further characteristics have been known. Improvement is strongly desired.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated capacitor obtained by providing an active energy ray irradiation-curable coating layer as a dielectric on a vapor-deposited film. Another object of the present invention is to provide a metallized film capacitor which can prevent troubles such as heat loss of a film and can highly satisfy the withstand voltage characteristics and durability of the obtained capacitor.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, if a thermoplastic resin film containing specific particles and having a designed surface shape is used, it will be extremely thin. Even when it is manufactured as a film, it is possible to prevent troubles such as generation of scratches at the time of film production and loss of the film at the time of film processing. The inventors have found that a reduction in withstand voltage characteristics and durability due to a decrease in uniformity can be prevented, and that a multilayer capacitor having good electrical characteristics can be obtained. Thus, the present invention has been completed.

That is, the gist of the present invention is that the average particle size (d
50) is 0.3 to 2.0 μm and the particle size distribution value (d25 / d
75) contains 0.01 to 5.0% by weight of particles A having a particle size of 2.0 or less, and has a maximum film surface height (Rmax) of 1.5 μm.
m or less, having a metal-deposited layer on both surfaces of a thermoplastic resin film having a thickness of 0.3 to 3.0 μm, and having at least one surface of the metal-deposited layer having a dielectric layer which is cured by irradiation with active energy rays. A metallized film capacitor obtained by laminating films.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Examples of the thermoplastic resin constituting the film in the present invention include resins such as polyester, polypropylene, polymethylpentene, polycarbonate, polyphenylene sulfide, and polyether ether ketone. Among them, polyester is preferred because it has good electrical and mechanical properties and is relatively inexpensive.

[0010] The polyester as used herein refers to a polyester comprising an aromatic dicarboxylic acid component and a glycol component. In particular, 80% or more of the repeating units are ethylene terephthalate units or ethylene-2,6-naphthalate units or 1,4. Polyesters having cyclohexylene dimethylene terephthalate units are preferred. Further, such a polyester may have another third component copolymerized. As the aromatic dicarboxylic acid component, in addition to terephthalic acid and 2,6-naphthalenedicarboxylic acid,
For example, isophthalic acid, phthalic acid, adipic acid, sebacic acid, 4,4′-diphenyldicarboxylic acid, oxycarboxylic acid (eg, p-oxyethoxybenzoic acid, etc.) can be used. As the glycol component, in addition to ethylene glycol and 1,4-cyclohexanedimethanol, for example, one or more of diethylene glycol, triethylene glycol, propylene glycol, butanediol, neopentyl glycol, and the like can be used. Further, a mixture of these polyesters may be used.

The intrinsic viscosity of the polyester is usually 0.45 or more, preferably 0.50 to 1.0, more preferably 0.52 to 0.80. If the intrinsic viscosity is less than 0.45, the productivity during the production of the film may decrease, or the mechanical strength of the film may decrease. On the other hand, from the viewpoint of melt extrusion stability of the polymer, the intrinsic viscosity preferably does not exceed 1.0.

Further, the thermoplastic resin of the present invention has a volume resistivity (ρ value) of more than 5.0 × 10 ⁸ Ω · cm at the time of melting in order to satisfy the insulation resistance characteristics of the film to a high degree. Is preferred. The ρ value here is a resistance value measured by melting the film, keeping the temperature at the extrusion molding temperature, and inserting an electrode. For example, in the case of polyethylene terephthalate, the measurement is performed at 285 ° C. ρ value is 5.0 ×
In the case of 10 ⁸ Ω · cm or less, the insulation resistance characteristic of the film tends to decrease particularly in a temperature range of 80 ° C. or more.
In the case of polyester, phosphoric acid is used to reduce the amount of the catalyst metal added during the production of the polyester, or to reduce the activity of the metal, in order to keep the ρ value in the above range.
Alternatively, a method of adding a phosphorus compound such as a phosphoric ester is used. The addition amount [P] of the phosphorus compound is based on the metal amount [M] of the esterification or transesterification catalyst,
The molar ratio may be selected so that [P] / [M] is in the range of 0.8 to 2.0.

During the production of a polyester, a metal component is used as a reaction catalyst, which is contained in the polyester. Therefore, the upper limit of the ρ value is usually 1.0 × 10 ¹⁰ Ω · cm.
It is about. In the present invention, for the purpose of improving the handleability by giving the film a slippery, for the purpose of preventing the occurrence of scratches during film production, containing particles in the film,
Moderate protrusions are formed on the film surface, and the feature of the present invention is that specific particles are used as such particles. That is, according to the knowledge of the present inventors, when specific particles are contained, the film handling properties and the electrical properties are simultaneously improved. That is, the average particle size (d50)
When particles A having a particle size distribution of 0.3 to 2.0 μm and a particle size distribution value (d25 / d75) of 2.0 or less are contained in an amount of 0.01 to 5.0% by weight, high properties can be obtained.

When the average particle diameter of the particles A is larger than the above range, the insulation resistance of the film itself is reduced, insulation defects occur due to the particles falling off the film surface, and the uniformity of the thickness of the coating layer is caused by roughening of the film. And the problems such as a decrease in the insulation resistance characteristics of the applied dielectric layer occur, which is not preferable. The average particle size is preferably 1.7μ
m, more preferably 1.5 μm or less.

If the particle size distribution value of the particles A is larger than the above range, coarse particles will be contained, causing the same problem as when the average particle size is too large. The particle size distribution value is preferably 1.8 or less, more preferably 1.7.
It is as follows. The lower limit of the particle size distribution value is usually 1.1, preferably 1.2, from the viewpoint of particle production efficiency, cost and the like. On the other hand, when the average particle diameter of the particles A is less than 0.3 μm, the effect of improving the running property of the film becomes insufficient, and the insulation resistance characteristic is lowered due to, for example, scratching of the film. Problems arise. The average particle size of the particles is preferably 0.4 μm or more, more preferably 0.1 μm.
5 μm or more.

If the content of the particles A is less than the above range, the protrusions on the film surface are insufficient, and the slipperiness is insufficient. On the other hand, if the content is too large, the particles easily fall off or the particles aggregate to form coarse projections, which causes problems such as insulation defects. The content of the particles A is preferably 0.05% by weight or more, more preferably 0.1% by weight or more, and preferably 2.0% by weight or less, more preferably 1.0% by weight or less,
0.8% by weight or less is particularly preferred.

In addition to the particles satisfying the above requirements,
Particles B having an average particle size of less than 0.5 μm and a particle size distribution value of 3.0 or less can be contained in a range of 2.0% by weight or less, preferably 1.0% by weight or less. By simultaneously containing such particles having a small average particle size, it is possible to prevent the occurrence of surface flaws in the film manufacturing process and the processing process, and to prevent the deterioration of the insulation resistance characteristics of the capacitor. The average particle size of such particles is more preferably less than 0.4 μm, particularly preferably less than 0.3 μm. On the other hand, if the average particle size is less than 0.1 μm, the effect of preventing scratches tends to decrease. Even when aggregated or chain-like particles are used as such small particles, they can be used as long as the average particle diameter measured by the method described later is in the above range.

Examples of the particles usable in the present invention include calcium carbonate, silica, calcium phosphate, kaolin, talc, titanium dioxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite,
In the case of inorganic particles such as molybdenum sulfide, crosslinked polymer particles, organic particles such as calcium oxalate, and polyester, precipitated particles formed during polymerization can be mentioned.

In the present invention, calcium carbonate and calcium oxalate are particularly preferably used as the particles A satisfying the above-mentioned requirements of an average particle size of 0.3 to 2.0 μm and a particle size distribution value of 2.0 or less. In the case of such particles, the particles do not easily fall off and good electrical characteristics can be provided. On the other hand, it is preferable to contain substantially spherical silica particles or spherical crosslinked polymer particles as particles A satisfying the requirements of an average particle size of 0.3 to 2.0 μm and a particle size distribution value of 2.0 or less. Absent. The substantially spherical particles referred to here include, for example, spherical silica particles as described in JP-A-63-317533 and JP-A-6-317533.
The term refers to spherical crosslinked polymer particles as described in JP-A-3-178144 and JP-A-63-191838, in which the particles have a specific ratio of major axis to minor axis or a specific range. It refers to those having a volume shape factor. Such spherical particles are not preferred because they may fall off the film in the film manufacturing process or the capacitor manufacturing process, causing problems such as fouling the process and causing insulation defects. In particular, spherical silica particles significantly reduce deposition productivity due to contamination in the process due to falling off, and damage the coated dielectric layer when pressure is applied in the lamination process during capacitor manufacturing, and lower withstand voltage characteristics It is not preferable because there are problems such as causing

However, it is possible to contain particles satisfying the requirements of the present invention and, in addition, spherical particles having a particle diameter smaller than the average particle diameter of the particles A. Also in this case, the diameter of the spherical particles is preferably less than 0.5 μm,
More preferably, it is less than 3 μm. Further, the content of the spherical particles is preferably 1.0% by weight or less, more preferably 0.5% by weight or less.

As the particles B satisfying the requirements of an average particle diameter of less than 0.5 μm and a particle diameter distribution of 3.0 or less, in the present invention, fine silica particles or crosslinked polymer particles which are not substantially spherical are preferable. . Such particles are excellent in electrical characteristics, and thus can improve the insulation resistance and withstand voltage characteristics of the film. In producing a thermoplastic resin containing particles, the particles may be added during the production of the resin or may be directly added to the resin. Particularly, in the case of adding polyester during the synthesis reaction, a method of adding the slurry as a slurry in which particles are dispersed in ethylene glycol or the like at an arbitrary stage of polyester synthesis is preferable. On the other hand, when it is directly added to the resin, a method of adding and mixing the resin as a dried particle or a slurry dispersed in water or an organic solvent having a boiling point of 200 ° C. or lower using a twin-screw kneading extruder is preferable. . The particles to be added may be subjected to a process such as crushing, dispersion, classification, and filtration, if necessary, beforehand.

As a method of adjusting the content of particles, a master material containing particles at a high concentration is prepared in the above-described manner, and is diluted with a material substantially free of particles during film formation. A method of adjusting the particle content is effective. In addition, as additives other than the above-mentioned projection-forming agent, if necessary, an antistatic agent, a stabilizer, a lubricant, an anti-blocking agent, an antioxidant, a coloring agent, etc. are contained within a range that does not deteriorate the capacitor characteristics. It may be.

The film of the present invention provides a capacitor having excellent electrical characteristics by satisfying the above requirements, but exhibits an effect when the film is as thin as 0.3 to 3.0 μm. That is, the effect of the surface characteristics of the film of the present invention is exerted in the case of a capacitor formed by applying a thin coating layer as a dielectric layer to the film surface. In the case of a thick film, it is rarely used for such a purpose, and a measure for improving the insulating properties by increasing the thickness of the coating layer can be adopted. Therefore, the necessity of forming a flat surface as in the present invention is low. On the other hand, a thin film having a film thickness of less than 0.3 μm has extremely poor film production productivity due to problems of strength and thickness unevenness, and is not in a practically usable range. The thickness of the film is preferably 0,1.
5 to 2.5 μm, more preferably 1.0 to 2.5 μm
In the case of (1), the effect of the present invention is exhibited to a higher degree, and the contribution to miniaturization of the capacitor is increased.

The film of the present invention may have a multilayer structure as long as the properties finally obtained satisfy the requirements of the present invention. Alternatively, a method may be used in which a film is produced by laminating a target film, a peelable polymer layer and the resin layer of the present invention by a coextrusion method or the like, and a biaxially oriented film is peeled off. The film of the present invention may be provided with an easily adhesive coating layer between the film and the vapor-deposited layer in order to enhance the adhesion to the vapor-deposited metal. Examples of the components constituting the coating layer include resins such as polyester, polyamide, polystyrene, polyacrylate, polycarbonate, polyarylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl butyral, polyvinyl alcohol, and polyurethane, and copolymers of these resins. Can be mentioned. One or two or more such resins may be simultaneously contained, and, if necessary, a projection forming agent such as fine particles, an antistatic agent, a stabilizer, a lubricant, a crosslinking agent, a blocking inhibitor, an antioxidant. , An antifoaming agent, a thickening agent, a coating improver, and the like may be contained within a range that does not deteriorate the capacitor characteristics.

As a method of applying the above-mentioned coating solution to a film, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater or the like other than those described in “Coating System”, written by Yuji Harazaki, Maki Shoten, 1979, is used. A coating device can be used.
The coating layer may be provided in the film manufacturing process, or may be applied after the film is manufactured. In particular, from the viewpoint of uniformity of the coating thickness and production efficiency, a coating method in the film manufacturing process is preferable.

As a method of applying in the film manufacturing process, a coating solution is applied to an unstretched film, and sequentially or
Simultaneous biaxial stretching, coating on a uniaxially stretched film, and further stretching in a direction perpendicular to the uniaxial stretching direction, or applying to a biaxially stretched film and further stretching in the transverse and / or longitudinal directions There are methods. The thickness of the coating layer is usually in the range of 0.005 to 0.2 μm,
Preferably it is in the range of 0.01 to 0.1 μm. It is preferable that the thickness of the coating layer be reduced in view of a demand for miniaturization of the capacitor. In particular, when the thickness of the coating layer exceeds 0.2 μm, the electrical characteristics may be deteriorated. On the other hand, when the thickness of the coating layer is less than 0.005 μm, there is a tendency that coating unevenness and coating slippage tend to occur.

The maximum height (Rmax) of the surface of the film of the present invention thus obtained is 1.5 μm or less, preferably 1.3 μm or less, more preferably 1.1 μm or less. When Rmax exceeds 1.5 μm, the surface is too rough, and the withstand voltage characteristics of the film itself are reduced, and the moisture and heat resistance characteristics of the capacitor are deteriorated, and the thickness uniformity of the applied dielectric layer is reduced. A problem may occur that the insulation resistance characteristics and the withstand voltage characteristics of the applied dielectric layer are reduced. That is, when a coating layer that is cured by irradiation with active energy rays as in the present invention is provided, the viscosity of the coating liquid is low, and leveling of the surface occurs after the coating and before curing. Therefore, the shape of the coating surface does not reflect much the shape of the film surface, and as a result, the projection layer existing on the film surface has a thin coating layer. Due to such unevenness of the applied thickness, the withstand voltage characteristics and the insulation resistance characteristics of the applied dielectric layer are greatly reduced. If the coating thickness is thin, 2.0 μm or less, and even 1.5 μm or less, the deposited layer on the film surface will appear on the surface of the applied dielectric layer, and even if it is attempted to make a capacitor by laminating, a short circuit will easily occur. And the capacitor may not be formed substantially. The effect of the film having a specific surface shape of the present invention is more advantageously exhibited when the thickness of the applied dielectric layer is 3.0 μm or less.

On the other hand, the lower limit of Rmax is usually 0.3 μm in order to satisfy the handling properties and winding characteristics of the film.
Preferably, it is 0.5 μm. In addition to the maximum projection height on the film surface, the center line average roughness (Ra) is preferably 0.020 to 0.20 μm, and more preferably 0.02 to 0.20 μm.
When the thickness is in the range of 30 to 0.12 μm, the film can be easily handled, and the deterioration of the capacitor insulation characteristics due to scratches can be prevented.

Further, regarding the shape of the surface of the film of the present invention, the number of protrusions having a height of 0.1 μm or more on the film surface was 1000 / mm with respect to the number of protrusions measured by a method described later using a three-dimensional roughness meter. ² or more, preferably 1500
Pieces / mm ² or more, the height 1.2μm or more protrusions number 50 / mm ² or less, preferably because it is when it is 30 / mm ² or less, to satisfy highly handling properties and electrical properties . 100 protrusions with a height of 0.1 μm or more
If the number is less than 0 pieces / mm ² , the handleability of the film and the running property during processing become poor, and the capacitor insulation properties tend to be reduced due to scratches and the like. On the other hand, height 1.2 μm
If the number of protrusions exceeds 50 / mm ² , Rma
Similarly to the case where x is too large, the withstand voltage characteristic and the insulation resistance characteristic of the applied dielectric layer may be reduced.

When the Young's modulus in the longitudinal direction of the film is 4.5 GPa or more, preferably 5.0 GPa or more, in addition to the surface characteristics of the film, the electrical characteristics and the handling property during vapor deposition are further enhanced. That is, in the step of performing metal vapor deposition on a film, the film is unwound and vapor-deposited while running under a certain tension. Therefore, if the film does not have sufficient strength against the tension, that is, does not have a high Young's modulus, the film cannot withstand the tension, and will be greatly damaged by heat generated by vapor deposition.
According to the knowledge of the present inventors, when such damage is caused, the heat-resistant dimensional stability of the vapor-deposited film is reduced, so that the yield at the time of manufacturing the capacitor is reduced or the electrical characteristics of the obtained capacitor are reduced. Tend to do so. If the Young's modulus of the film in the longitudinal direction is within the range of the present invention, such electric properties are highly satisfied.

Further, the film of the present invention has a viscosity of 3 ° C. at 180 ° C.
The shrinkage in the longitudinal direction after the treatment for 5 minutes is preferably 5.0% or less, more preferably 4.0% or less. If the heat shrinkage in the longitudinal direction is too large, the film undergoes dimensional change in the step of receiving heat during the production of the capacitor, causing problems such as a decrease in productivity and a reduction in the life of the capacitor. On the other hand, the heat shrinkage is preferably 1.0% or more, more preferably 2.0% or more. If the heat shrinkage is too small, the adhesion between the film and the cooling can becomes insufficient in the vapor deposition step, and the film becomes susceptible to thermal damage. The effect tends to be difficult to obtain. On the other hand, the shrinkage rate in the width direction under the same conditions is preferably smaller than the shrinkage rate in the longitudinal direction,
And less than 2%.

Next, the method for producing the film used in the present invention will be specifically described with respect to a polyester film which is the most preferred embodiment of the present invention. First, a polyester raw material is supplied to an extruder, melt-extruded at a temperature equal to or higher than the melting point of the polyester, and extruded as a molten sheet from a slit die. Next, the molten sheet is quenched and solidified on a rotary cooling drum so as to have a temperature equal to or lower than the glass transition temperature, thereby obtaining a substantially amorphous unoriented sheet. In this case, in order to improve the flatness of the sheet, it is preferable to increase the adhesion between the sheet and the rotary cooling drum. In the present invention, the electrostatic application adhesion method and / or the liquid application adhesion method are preferably employed. In the present invention, the sheet obtained in this way is stretched biaxially to form a film, and the orientation and Young's modulus, which are the characteristics of the film of the present invention, are obtained by adjusting the stretching and heat treatment conditions to appropriate ranges. Can be achieved. Specifically, the biaxial stretching conditions are as follows. The unstretched sheet is first stretched in the first axial direction so that the birefringence (Δn) is usually 0.08 or more, preferably 0.09 or more. The stretching temperature range is 7
The stretching magnification is in the range of 2.5 to 6 times at 0 to 150 ° C., and the desired birefringence is obtained by appropriately combining the temperature and the magnification. Stretching can be performed in one step or two or more steps. Next, the second axis direction, that is, once cooled the uniaxially oriented film in the direction perpendicular to the first axis direction below the glass transition temperature, or without cooling, for example, preheated to a temperature range of 80 to 150 ° C., Further, the film is stretched 2.5 to 5 times, preferably 3.0 to 4.5 times in the same temperature range to obtain a biaxially oriented film.

It is preferable that stretching in the first axial direction is performed in two or more steps, because good thickness uniformity can be achieved. In addition, a method of further stretching in the longitudinal direction after the transverse stretching is possible, but in any case, it is preferable to set the total stretching ratio in the longitudinal direction to 3.5 times or more. Elongation, limited shrinkage within 20%,
Alternatively, heat treatment is performed at a constant length for 1 second to 5 minutes. At this time, re-stretching may be performed in the longitudinal direction, the lateral direction, or both directions during or after the heat treatment step.

[0034] In the present invention, when the polyester film is less than the density of 1.4050g / cm ^3, more desirably to less than 1.4030g / cm ^3, in order to satisfy such characteristics, the heat treatment step described above The temperature is appropriately selected. The heat treatment temperature depends on the stretching conditions, but is preferably 180 to 250 ° C, more preferably 200 to 250 ° C.
It is in the range of 240 ° C. If the heat treatment temperature exceeds 250 ° C., the film density becomes too high, and high electrical characteristics may not be obtained. On the other hand, when the heat treatment temperature is 180
If the temperature is lower than ℃, the heat shrinkage of the film becomes large, causing dimensional change in the step of receiving heat during the production of the capacitor, causing problems such as deterioration of the productivity of the capacitor and deterioration of the capacitor characteristics such as withstand voltage. Sometimes.

When manufacturing a capacitor using the film of the present invention, electrodes are formed by metal evaporation. Examples of the metal to be deposited include aluminum, palladium, zinc, nickel, gold, silver, copper, indium, tin, chromium, titanium, and the like, and a particularly preferred metal is aluminum. The above-mentioned metals include metal oxides. A plurality of types of metals may be mixed or deposited in a stacked state.

The thickness of the metal deposited film is preferably in the range of 1 to 200 nm. The method of vapor deposition is generally a vacuum deposition method, but may be a method such as an electroplating method or a sputtering method. The metal deposition layers are provided on both sides of the film. After the metal deposition, a surface treatment of the deposited metal layer or a coating treatment with another resin may be performed. On one or both sides of the metal-deposited film thus obtained, a dielectric layer is formed by, for example, application.In the present invention, the dielectric layer is formed as a resin layer which is cured by irradiation with active energy rays. Features. According to this method, the amount of the solvent contained in the coating solution is reduced or the coating can be performed without using any solvent, so that the pinhole generation of the coating dielectric layer due to the evaporation of the solvent does not occur. The problem of withstand voltage characteristic deterioration is prevented. In addition, since steps such as drying of the solvent at the time of coating and recovery of the evaporated solvent can be omitted, productivity can be improved. In addition, it is possible to improve the problem of environmental pollution and natural destruction due to evaporation and leakage of the solvent.

The coating layer cured by the active energy ray used in the present invention will be described below. In the present invention, known resin layers can be used as the resin layer that is cured by active energy rays to form a dielectric, and is usually a reactive oligomer, a reactive monomer, a polymerization initiator, a polymerization initiation aid,
It consists of other additives and the like. The reactive oligomer typically includes an oligomer having a reactive acryloyl group or methacryloyl group bonded to an acrylic resin skeleton. Other examples include polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, polyether (meth) acrylate, silicone (meth) acrylate, and polybutadiene (meth) acrylate. Further, an oligomer in which an acryloyl group or a methacryloyl group is bonded to a rigid skeleton such as melamine, isocyanuric acid, and cyclic phosphazene is exemplified.

The reactive monomer is a monomer having, for example, a (meth) acryloyl group or a vinyl group as an unsaturated double bond, and is a monofunctional or polyfunctional compound. The reactive monomer is also called a reactive diluent because it can also serve as a solvent in the coating step as a medium for the coating agent. Specific examples of such a reactive monomer include:
As monofunctional monomers, vinyl compounds such as styrene and N-vinylpyrrolidone, 2-ethylhexyl acrylate, 2-hydroxyethyl (meth) acrylate, butoxyhydroxypropyl (meth) acrylate, n-hexyl acrylate, cyclohexyl acrylate, n
Monofunctional acrylates such as decyl acrylate, isobonyl acrylate, dicyclohexyl acrylate, dicyclohexynyloxyethyl acrylate, phenoxyethyl acrylate, glycidyl (meth) acrylate and tetrafluoropropyl acrylate;

As polyfunctional monomers, propylene glycol diacrylate, tripropylene glycol diacrylate, 1,4-butanediol diacrylate,
1,6-hexanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, bisphenol A diethoxy diacrylate, neopentyl glycol diacrylate hydroxypivalate, hydroxypropyl di (meth) acrylate, penta Erythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate , Trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) Rate, (meth) acryloyloxy propyl triethoxysilane, and (meth) acryloyloxy propyl trimethoxy silane.

Further, when a monofunctional or polyfunctional acrylic compound containing an aliphatic group having a cyclic structure is contained as a reactive monomer, the glass transition temperature of the coating layer is increased, so that the electrical characteristics are improved. In addition, the low shrinkage property is preferable because wrinkles can be prevented from being formed when applied to a thin film. Examples of the aliphatic group having a cyclic structure include a cyclohexyl group, an isobonyl group, a tetrahydrofurfuryl group, a dicyclopentenyl group, an adamantyl group, and hydrogenated bisphenol A.

Examples of the polymerization initiator include 2,2-ethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, dibenzoyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, p-chlorobenzophenone,
Examples include p-methoxybenzophenone, Michler's ketone, acetophenone, 2-chlorothioxanthone, anthraquinone, phenyldisulphide, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, and the like.

Examples of the polymerization initiator include tertiary amines such as triethylamine, triethanolamine and 2-dimethylaminoethanol, alkylphosphines such as triphenylphosphine, and thioethers such as β-thiodiglycol. . Examples of the modifier include a coating improver, an antifoaming agent, a thickener, an inorganic particle, an organic particle, a lubricant, an organic polymer, a dye, a pigment, and a stabilizer. These are blended as a composition of the active energy ray-curable resin layer within a range that does not inhibit the reaction by the active energy ray, and the properties of the active energy ray-curable resin layer can be improved according to the application. A small amount of an organic solvent can be added to the composition of the active energy ray-curable resin layer in order to improve workability during coating and control the coating thickness.

The active energy ray-curable resin layer is formed by applying the curing resin composition to the surface of the coating layer and then irradiating with an active energy ray to crosslink and cure. As the active energy rays, ultraviolet rays, visible rays, electron beams, X-rays, α-rays, β-rays, and γ-rays can be used. Usually, the irradiation of the active energy ray is performed from the coating layer side, but may be performed from the film surface side in order to enhance the adhesion to the film.

When the thickness of the active energy ray-cured dielectric layer is in the range of 0.2 to 3.0 μm, the effect of the present invention is remarkably obtained. When the thickness is less than 0.2 μm, the uniformity of the thickness tends to be insufficient, and the withstand voltage characteristics of the applied dielectric layer may be reduced, or the productivity may be reduced due to a short circuit at the time of manufacturing the capacitor. On the other hand, if it exceeds 3.0 μm, it becomes difficult to produce a small capacitor, and the film may be wrinkled due to curing shrinkage of the coating layer.

The coating dielectric layer is provided by forming a margin portion in a stripe shape.
A method such as appropriately performing a masking treatment at the time of coating is adopted. A capacitor element is formed by laminating a large number of vapor-deposited films having the thus-obtained coated dielectric layer, and a known method can be employed for the process. Therefore, for example, a capacitor can be obtained through processes such as lamination, metallikon, voltage treatment, sealing of both end faces, and formation of an exterior, but of course, the capacitor is not limited to these.

[0046]

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, “parts” means “parts by weight”. (1) Intrinsic viscosity of polymer [η] (dl / g) 1 g of polymer is phenol / tetrachloroethane = 50
/ 50 (weight ratio) in 100 ml of a mixed solvent.
Measured in ° C. (2) Average particle size of particles (d50) (μm) and particle size distribution value (d25 / d75) Centrifugal sedimentation type particle size distribution analyzer (SA-CP, manufactured by Shimadzu Corporation)
The average particle diameter (d50) was the particle diameter at 50% of the integrated volume fraction integrated from the large particle side in the equivalent spherical distribution measured by type 3). The values of the integrated volume fractions of 25% and 75% were d25 and d75, respectively, and the ratio value (d25 / d75) was taken as the particle size distribution value. The smaller the particle size distribution value, the sharper the particle size distribution of the particles. (3) Specific resistance at the time of polymer melting (Ω · cm) The film was melted at 285 ° C., and air bubbles were removed by a method such as reducing the pressure in the system. In the polymer kept at the same temperature,
Two 5m stainless steel electrodes with an area of 1cm2
It was fixed and inserted at intervals of m. A voltage of 100 V was applied between the electrodes, and the specific resistance was calculated from the value of the flowing current. The current value was recorded on a recorder, and the value one second after the voltage was applied was read. (4) Maximum height (Rmax) and center line average roughness (R
a) (μm) It was determined as follows using a surface roughness measuring instrument (SE-3F) manufactured by Kosaka Laboratory Co., Ltd. That is, a portion of the reference length L (2.5 mm) is extracted from the film cross-sectional curve in the direction of the center line, and the center line of the extracted portion is the x-axis, and the direction of the vertical magnification is the y-axis. When represented by f (x), the value given by the following equation was defined as the center line average roughness (Ra) and represented by [μm].

The maximum height (Rmax) is 2 parallel to the average line of the extracted portion of the film cross-sectional curve obtained above.
When the sampled portion is sandwiched by straight lines, the value obtained by measuring the distance between these two straight lines in the direction of the longitudinal magnification of the sectional curve is the maximum height (Rma).
x) and expressed in [μm]. The maximum height and the center line average roughness were obtained by obtaining ten cross-sectional curves from the surface of the sample film, and expressing the average values of the values of the extracted portions obtained from these cross-sectional curves. The tip radius of the stylus is 2μ.
m, the load is 30 mg, and the cutoff value is 0.08 mm
And

[0048]

(Equation 1) (5) Number of surface protrusions Three-dimensional surface roughness tester (SE-3A) manufactured by Kosaka Laboratory Co., Ltd.
Using K), the tip radius of the stylus is 5 μm, the stylus pressure is 30 mg, the measurement length is 0.5 mm, the sampling pitch is 1.0 μm, the cutoff is 0.25 mm, the vertical magnification is 20,000 times, and the horizontal magnification is 20.
The projection height and the number of projections were measured under the condition of 0 times and 500 scanning lines. Here, the projection height (X, μm) is defined as the height of the point where the number of projections is the maximum, and the height from this level is defined as the projection height. The number of projections (Y, / Mm2) is graphically represented as a distribution curve.

Projection height of 0.5 μm or more and 1.0 μm
m or more, the projection height by the above method is 0.5 μm
And the total number of protrusions corresponding to protrusions exceeding 1.0 μm. The measurement was performed at three points in the longitudinal direction of the film and three points in the direction perpendicular to the longitudinal direction, for a total of six points, and the average value was used as the measured value. Note that the measurement film is set on a smooth glass sample table, but is adhered to the glass without any liquid, air, or the like between the film and the glass. (6) Film thickness (μm) The thickness of the film was determined by a gravimetric method. That is, 10
The total weight of 100 pieces of the film cut into a square of cm × 10 cm was measured, and calculated using the density of the film. In addition, the density of the film was measured at 25 degreeC using the density gradient tube by n-heptane / carbon tetrachloride. (7) Shrinkage (%) The film was heat-treated in an oven maintained at 180 ° C. for 3 minutes in a non-tension state, and the length of the film before and after the heat treatment was measured.

[0050]

(Equation 2) (In the above formula, L0 is the film length (mm) before heat treatment, L
1 means the film length (mm) after the heat treatment.) The measurement was performed at 10 points each in the longitudinal direction and the width direction, and the average value was obtained. (8) Young's modulus (GPa) Tensile tester Intesco Model 20 manufactured by Intesco Corporation
The measurement was performed in a room adjusted to a temperature of 23 ° C. and a humidity of 50% RH using a Model 01. That is, length 300m
The sample film having a width of 25 mm and a width of 25 mm is pulled at a strain rate of 10% / min, and is calculated by the following equation using the first straight line portion of the tensile stress-strain curve.

[0051]

E = Δσ / Δε (where E is the tensile modulus, Δσ is the stress difference due to the original average cross-sectional area between two points on the straight line, and Δε is the strain difference between the same two points) (9) Evaluation of electrical characteristics (Manufacture of capacitor) A capacitor was manufactured and evaluated as follows. That is, using a resistance heating type metal vapor deposition apparatus on both surfaces of the film, the pressure in the vacuum chamber was set to 10 ^-4 Torr
Aluminum was deposited to a thickness of 40 nm as follows.
At this time, vapor deposition was performed in a stripe shape having a margin portion in the longitudinal direction of the film. One surface of the obtained vapor-deposited polyester film was coated with an active energy ray-curable coating agent, and the film was cured by irradiating ultraviolet rays under nitrogen while cooling the film to form a dielectric film. A plurality of the films were laminated, and a cover film having a polyphenylene oxide film on the surface of a polyester film was provided on both surfaces thereof to form a capacitor element portion. After forming a metallikon layer on both end surfaces of the capacitor element portion, the capacitor element portion was cut to a predetermined length to form a capacitor strip. Metallicon electrodes of the obtained capacitor strips were subjected to solder plating, cut with a saw blade in a direction perpendicular to the strip direction, further leaded to each capacitor element, subjected to voltage treatment, epoxy exterior treatment, to prepare a capacitor. . (I) Withstand voltage characteristics Using a 10 kV DC withstand voltage tester, 23 ° C., 50% RH
Under an atmosphere of 100 V / sec at a boost rate,
The voltage was read when the capacitor was short-circuited and no longer functioned as a capacitor. The measurement was performed for 110 capacitors, and the average of the values at 100 points was calculated excluding 5 points from the larger value and 5 points from the smaller value. (Ii) Insulation Resistance Characteristics (Measurement of Capacitance) Using a LCR meter 4284A (trade name) manufactured by Yokogawa Hewlett-Packard Company, the capacitance C [F] of the obtained capacitor was measured. Measurement is 23
C. and 50% RH. (Measurement of insulation resistance value) Using a high resistance meter 4329A (trade name) manufactured by Yokogawa Hewlett-Packard Company, a DC voltage of 100 V was applied between the electrodes of the obtained capacitor, and the resistance value R [Ω] of the capacitor was measured. It was measured. The voltage application was performed for 1 minute, and the current value was recorded on the recorder during that time. The current value showed a maximum value immediately after voltage application and then decreased. The maximum value was defined as a measured value R. The measurement was performed at 23 ° C and 130 ° C. The evaluation of the insulation resistance of the capacitor is C × R (CR
Value) [Ω · F]. Larger CR values indicate better insulation resistance.

Example 1 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of calcium acetate monohydrate were placed in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. 4 hours, 2
The temperature was raised to 30 ° C. to substantially complete the transesterification reaction.

Next, the particle size was 1.2 μm, and the particle size distribution value was 1.
1.0 part of calcium carbonate particles of No. 6 was added as an ethylene glycol slurry. After the addition of the slurry, 0.06 parts of phosphoric acid and 0.04 parts of antimony trioxide were further added, and the reaction system was gradually reduced in pressure, the temperature was increased, and the polycondensation reaction was performed for 4 hours. a) was obtained.

Similarly, polyester (b) having an intrinsic viscosity of 0.66 and containing 0.6% by weight of silica particles having an average particle size of 0.20 μm and a particle size distribution value of 1.9 was obtained. Also, a polyester (c) having an intrinsic viscosity of 0.66 was obtained in the same manner except that no particles were contained. 30 parts of polyester (a), 60 parts of polyester (b) and 10 parts of polyester (c)
The raw material obtained by mixing the components is dried by a conventional method, supplied to an extruder, melted at 290 ° C., extruded into a sheet, and quenched on a cooling roll using an electrostatic contact method to form an amorphous sheet. . The obtained sheet was stretched 2.9 times in the longitudinal direction at 84 ° C. using the roll stretching method, and further stretched 1.5 times at 70 ° C. Next, the film was guided to a tenter, stretched 4.1 times in the transverse direction at 110 ° C., heat-treated at 225 ° C., and further subjected to a 3% transverse relaxation treatment in a 200 ° C. zone. A 0 μm biaxially stretched polyester film was obtained. Center line average roughness (Ra) is 0.0
63 μm.

The obtained film was vapor-deposited, and 40 parts of isobonyl acrylate and 30 parts of dicyclopentanyl diacrylate were used as active energy ray-curable coating agents.
, A coated dielectric layer was formed using a composition comprising 27 parts of 1,9-nonanemethylene diacrylate and 3 parts of 1-hydroxycyclohexylphenyl ketone. The thickness of the layer was 1.5 μm on average. As shown in Table 1 below, the metal-deposited film capacitor obtained by laminating the films was a metal-deposited polyester film capacitor having excellent withstand voltage characteristics and excellent insulation resistance characteristics.

Examples 2 to 5 and Comparative Examples 1 to 4 Polyester containing particles was produced in the same manner as in Example 1, and a film having a thickness of 2.0 μm was obtained in the same manner as in Example. . The average particle size, particle size distribution, and content of the particles contained in the film are as shown in Table 1. However, in Comparative Example 3, the film could not be obtained in the form of a good roll because the handleability of the film was extremely poor. Therefore, although a small amount of film was obtained and the characteristics were measured, it was not possible to prepare and evaluate a capacitor.

Example 6 In Example 1, the film stretching conditions were changed as follows. That is, the longitudinal stretching by the roll stretching method,
First, the film was stretched 2.4 times at 85 ° C., then 1.2 times at 75 ° C., and then stretched 4.5 times at 110 ° C. with a tenter. By performing a relaxation treatment, a biaxially oriented polyester film having a thickness of 2.0 μm was obtained. Further, the active energy ray-curable coating composition in Example 1 was added with 40 parts of cyclohexyl acrylate,
A capacitor was prepared in the same manner as in Example 1, except that a composition comprising 37 parts of dicyclopentanyl diacrylate, 20 parts of 1,9-nonanemethylene diacrylate and 3 parts of 1-hydroxycyclohexyl phenyl ketone was used. .

Example 7 A polyester raw material obtained in the same manner as in Example 1 except that the amount of phosphoric acid added after the transesterification reaction was changed to 0.035 parts during the production of polyester was used. The conditions for film formation were 1.8 μm in the same manner as in Example 1.
m biaxially oriented polyester film was obtained. Example 1 was the same as Example 1 except that the active energy ray-curable coating composition in Example 1 was a composition comprising 30 parts of butoxyhydroxypropyl acrylate, 77 parts of hydroxypropyl dimethacrylate and 3 parts of 1-hydroxycyclohexyl phenyl ketone. Similarly, a capacitor was prepared.

Comparative Example 5 Raw materials and film production conditions were the same as in Example 1.
By changing the raw material extrusion amount, a biaxially stretched film having a film thickness of 4.0 μm was obtained. A capacitor was made using the film. However, if it was attempted to obtain a capacity equivalent to that of the example, the capacitor itself became large, and the capacitor could not be used practically, and the effect of the present invention could not be exhibited.

Comparative Example 6 The raw materials and film production conditions were the same as in Example 1.
It was attempted to obtain a biaxially stretched film having a film thickness of 0.2 μm by changing the raw material extrusion amount, but the film thickness was too thin, and frequent breakage and removal of the tenter clip frequently occurred. No film was obtained.

Tables 1 and 2 below show the polyesters obtained in the Examples and Comparative Examples, the physical properties of the films thereof, and the characteristics evaluation results of the vapor deposition capacitors prepared using them. Comparative Example 7 In Example 1, a resin for forming a coating dielectric was polyphenylene oxide, and a film was formed by a conventional method to prepare a capacitor. The coating film was formed on one side of the film, and the thickness was the same as in Example 1. Many of the obtained capacitors were already short-circuited, and even if there was no short-circuit, the withstand voltage characteristics were degraded.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

[Table 3]

[0065]

[Table 4]

[0066]

[Table 5]

[0067]

The metal-deposited film capacitor obtained by using the film of the present invention to form a dielectric using an active energy ray-curable coating agent has excellent withstand voltage characteristics and insulation resistance characteristics. Since the amount of the solvent used is small or the solvent is not used, problems of environmental pollution and natural destruction can be prevented, so that its industrial value is high.

Claims (3)

[Claims] An average particle size (d50) of 0.3 to 2.0 μm.
A having a particle size distribution value (d25 / d75) of 2.0 or less
Is contained in an amount of 0.01 to 5.0% by weight, the maximum height (Rmax) of the film surface is 1.5 μm or less, and the thickness is 0.3 to 0.3%.
Metallization obtained by laminating a film having a metal deposited layer on both sides of a thermoplastic resin film having a thickness of 3.0 μm and a dielectric layer cured on at least one surface of the metal deposited layer by irradiation with active energy rays. Film capacitor. 2. An average particle diameter (d) in a thermoplastic resin film.
The metallized film capacitor according to claim 1, wherein the metallized film capacitor contains 0.1 to 2% by weight of particles B having a particle size distribution value of less than 0.5 µm and a particle size distribution value of 3.0 or less. 3. The shrinkage in the longitudinal direction of the thermoplastic resin film after treating at 180 ° C. for 3 minutes is 1.0 to 1.0.
The metallized film capacitor according to claim 1 or 2, wherein the content is 5.0%.