JP2021190443A - Film capacitor and film for film capacitor - Google Patents

Abstract

To provide a film capacitor which can suppress an increase in ESR when a voltage is applied at high temperature for long time.SOLUTION: A film capacitor 10 includes: a dielectric film 13 having a first surface and a second surface opposite to each other in a thickness direction; and a metal layer 15 provided on at least the first surface of the dielectric film 13. The dielectric film 13 includes a first resin layer 17 made of a cured product of a first organic material and a second organic material. The first organic material is composed of an organic polymer having a hydroxyl group and a benzene ring in a repeating unit. The second organic material is made of 4,4-dipenylmethane diisocyanate, a 4,4'-dipenylmethane diisocyanate modified body or a mixture thereof. A resin layer 19 having a content of chlorine ions of less than 70 ppm is provided between the metal layer 15 provided on the first surface of the dielectric film 13 and the first resin layer 17.SELECTED DRAWING: Figure 1

Description

The present invention relates to a film capacitor and a film for a film capacitor.

As a kind of capacitor, there is a film capacitor having a structure in which a first metal layer and a second metal layer facing each other across the resin film are arranged while using a flexible resin film as a dielectric. In such a film capacitor, for example, a first resin film on which a first metal layer made of aluminum or the like is formed and a second resin film on which a first metal layer made of aluminum or the like is formed are wound. It is made by laminating or laminating.

As a material for a dielectric film for a film capacitor, a thermoplastic resin such as polypropylene has been conventionally used as described in Patent Document 1, but heat is described in Patent Documents 2 and 3. A curable resin such as a curable resin is also used.

In Patent Document 1, a metallized film having a metal-deposited electrode formed on a resin-made dielectric film made of a polypropylene film or the like is laminated or wound so that a pair of metal-deposited electrodes face each other via the dielectric film. Among the above-mentioned pair of metallised films, in a DC metallised film capacitor having a pair of take-out electrodes made of a metallised film formed by spraying metal on both end faces of the condenser element configured by the above. Disclosed is a DC metallized film capacitor in which the film thickness of the metallised film formed on the metallized film on the positive electrode side is thicker than the film thickness of the metallised film formed on the metallized film on the negative electrode side. There is.

Patent Document 2 includes a dielectric resin film and first and second counter electrodes facing each other with the dielectric resin film interposed therebetween, and the dielectric resin film is a first and second organic material. A cured product obtained by reacting at least two kinds of organic materials containing, and containing at least one functional group having a relatively small molar polarization ratio, which is selected from a methylene group, an aromatic ring and an ether group. It comprises one atomic group and a second atomic group containing at least one functional group having a relatively high molar polarization ratio selected from a hydroxyl group, an amino group and a carbonyl group (absorption of the first atomic group). A film capacitor made of a dielectric resin composition having a value represented by (total band strength) / (total absorption band strength of the second atomic group) of 1.0 or more is disclosed. Patent Document 2 describes that it is preferable that the first organic material is a polyol such as a phenoxy resin, and the second organic material is an isocyanate compound, an epoxy resin or a melamine resin.

Patent Document 3 describes a film capacitor including a dielectric resin film and a first opposed electrode and a second opposed electrode that face each other with the dielectric resin film interposed therebetween. The dielectric resin film is the first. A film for a capacitor made of a crosslinked product of an organic material and a second organic material, the second organic material is a polyisocyanate having a plurality of isocyanate groups, and the first organic material has a plurality of hydroxyl groups. However, a film capacitor characterized by having a branched structure is disclosed.

Japanese Unexamined Patent Publication No. 2007-250833 Japanese Unexamined Patent Publication No. 2015-181199 International Publication No. 2017/175511

A dielectric film using a curable resin such as a thermosetting resin has a feature of having higher heat resistance than a dielectric film using a thermoplastic resin. However, in a film capacitor manufactured by using a dielectric film as described in Patent Documents 2 and 3, there is a problem that the equivalent series resistance (ESR) becomes high when a voltage is applied for a long time at a high temperature. Was found to occur.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a film capacitor capable of suppressing an increase in ESR when a voltage is applied for a long time at a high temperature. Furthermore, an object of the present invention is to provide a film for a film capacitor used as a dielectric film of the film capacitor.

The film capacitor of the present invention includes a dielectric film having first and second surfaces facing each other in the thickness direction, and a metal layer provided on at least the first surface of the dielectric film. The dielectric film contains a first resin layer made of a cured product of a first organic material and a second organic material. The first organic material is composed of an organic polymer having a hydroxyl group and a benzene ring in a repeating unit. The second organic material comprises 4,4'-diphenylmethane diisocyanate, a modified 4,4'-diphenylmethane diisocyanate, or a mixture thereof. A resin film having a chlorine ion content of less than 70 ppm is provided between the metal layer provided on the first surface of the dielectric film and the first resin layer.

The film for a film capacitor of the present invention is composed of a dielectric film having a first surface and a second surface facing each other in the thickness direction. The dielectric film includes a first resin layer made of a cured product of a first organic material and a second organic material, and a second resin layer provided on the surface of the first resin layer on the first surface side. including. The first organic material is composed of an organic polymer having a hydroxyl group and a benzene ring in a repeating unit. The second organic material comprises 4,4'-diphenylmethane diisocyanate, a modified 4,4'-diphenylmethane diisocyanate, or a mixture thereof. The content of chlorine ions in the second resin layer is less than 70 ppm.

According to the present invention, it is possible to suppress an increase in ESR when a voltage is applied to a film capacitor at a high temperature for a long time.

FIG. 1 is a cross-sectional view schematically showing an example of the film capacitor of the present invention. FIG. 2 is a plan view schematically showing an example of a metal layer having a fuse portion. FIG. 3 is a cross-sectional view schematically showing a sample film in which the second resin layer is provided on the first resin layer. FIG. 4 is a cross-sectional view schematically showing a sample film in which the second resin layer and the third resin layer are provided on the first resin layer. FIG. 5 is a cross-sectional view schematically showing a sample film to which the second resin layer and the third resin layer are not provided.

Hereinafter, the film capacitor of the present invention and the film for a film capacitor will be described.
However, the present invention is not limited to the following configuration, and can be appropriately modified and applied without changing the gist of the present invention. It should be noted that a combination of two or more of the individual desirable configurations of the present invention described below is also the present invention.

[Film capacitor]
The film capacitor of the present invention includes a dielectric film having first and second surfaces facing each other in the thickness direction, and a metal layer provided on at least the first surface of the dielectric film.

In the film capacitor of the present invention, the dielectric film includes a first resin layer made of a cured product of a first organic material and a second organic material. Specifically, the first resin layer is made of a cured product obtained by reacting a hydroxyl group (OH group) of the first organic material with an isocyanate group (NCO group) of the second organic material.

The first organic material is composed of an organic polymer having a hydroxyl group and a benzene ring in a repeating unit. The first organic material is preferably made of a phenoxy resin.

The second organic material consists of 4,4'-diphenylmethane diisocyanate (MDI), MDI modified product, or a mixture thereof.

When the cured product is obtained by the above reaction, the uncured portion of the starting material may remain in the first resin layer. For example, the first resin layer may contain at least one of a hydroxyl group and an isocyanate group. In this case, the first resin layer may contain either a hydroxyl group or an isocyanate group, or may contain both a hydroxyl group and an isocyanate group.
The presence of hydroxyl groups and / or isocyanate groups can be confirmed using a Fourier transform infrared spectrophotometer (FT-IR).

In the film capacitor of the present invention, the thickness of the first resin layer is not particularly limited, but if the first resin layer is too thin, the withstand voltage resistance and tensile strength of the dielectric film tend to decrease. Therefore, the thickness of the first resin layer is preferably 0.5 μm or more, and more preferably 1 μm or more. On the other hand, if the first resin layer becomes too thick, the capacitance of the film capacitor tends to decrease. Therefore, the thickness of the first resin layer is preferably 10 μm or less, and more preferably 5 μm or less.

The thickness of the first resin layer can be measured using an optical film thickness meter. Similarly, the thickness of the second resin layer or the third resin layer, which will be described later, can be measured using an optical film thickness meter.

In the film capacitor of the present invention, a resin film having a chlorine ion content of less than 70 ppm is provided between the metal layer provided on the first surface of the dielectric film and the first resin layer. It is a feature.

According to the research by the present inventors, a resin film having a chlorine ion content of less than 70 ppm is provided between the metal layer and the first resin layer, so that a voltage is applied to the film capacitor at a high temperature for a long time. It was found that the increase in ESR could be suppressed.

Chlorine ions are contained as impurities in the first resin layer prepared by using the first organic material such as phenoxy resin. As the chlorine ion in the first resin layer, for example, one derived from epichlorohydrin used when synthesizing a first organic material such as a phenoxy resin can be considered.

In such a film capacitor in which the first resin layer is in direct contact with the metal layer, it is presumed that chlorine ions in the first resin layer act as a catalyst to promote a phenomenon called anodization. As a result, it is considered that the ESR increases when a voltage is applied to the film capacitor at a high temperature for a long time.

For example, when the metal layer of a film capacitor is made of aluminum, the aluminum constituting the metal layer on the positive electrode (positive electrode) side and the hydroxide ion derived from the moisture in the atmosphere cause an electrochemical reaction. A film of aluminum hydroxide or aluminum oxide which is an insulator may be formed, and the metal layer may be insulated. This phenomenon is anodizing. It is considered that the metal layer is insulated by anodization, resulting in an increase in ESR. In addition, as a result of the increase in the insulating portion of the metal due to anodization, the electrode area of the film capacitor is reduced, and it is considered that the capacitance is also reduced. It should be noted that these problems caused by anodization are not limited to film capacitors whose metal layer is made of aluminum, but are also common to film capacitors made of metals other than aluminum.

On the other hand, when a resin film having a low chlorine ion content and less than 70 ppm is provided between the metal layer and the first resin layer as in the film capacitor of the present invention, the first resin layer is formed. Since it does not come into direct contact with the metal layer, it is presumed that the influence of chlorine ions from the first resin layer to the metal layer is suppressed, and the above-mentioned anodizing, that is, the insulation of the metal layer is suppressed. As a result, it is considered that an increase in ESR can be suppressed when a voltage is applied to the film capacitor at a high temperature for a long time.

The content of chlorine ions in the resin film can be measured by a combustion ion chromatography method. Similarly, the content of chlorine ions in the first resin layer and the content of chlorine ions in the second resin layer or the third resin layer, which will be described later, can be measured by the combustion ion chromatography method.

The content of chlorine ions in the resin film is, for example, 3.6 ppm or more. The content of chlorine ions in the resin film may be 0 ppm.

As mentioned above, anodization occurs in the metal layer on the positive electrode side. Therefore, in the film capacitor of the present invention, it is preferable that the resin film having a chlorine ion content of less than 70 ppm is provided at least between the metal layer on the positive electrode side and the first resin layer.

In the film capacitor of the present invention, the resin film having a chlorine ion content of less than 70 ppm may be provided as a whole between the metal layer and the first resin layer, and may be provided between the metal layer and the first resin layer. It may be provided in a part of the space.

In the film capacitor of the present invention, the resin film having a chlorine ion content of less than 70 ppm is preferably a part of the dielectric film. That is, it is preferable that the dielectric film further includes, as the resin film, a second resin layer provided on the surface of the first resin layer on the first surface side. In this case, the second resin layer may be provided on all or a part of the surface of the first resin layer on the first surface side facing the metal layer in the thickness direction, but the metal layer and the second resin layer may be provided. In addition to the facing surfaces, it may be provided on all or a part of the surfaces that do not face the metal layer. The second resin layer may be provided on the entire surface of the first resin layer on the first surface side, or may be provided on a part of the surface of the first resin layer on the first surface side.

In the film capacitor of the present invention, the thickness of the resin film or the second resin layer is preferably 100 nm or less. If the resin film or the second resin layer is too thick, the ratio of the first resin layer to the film capacitor becomes small, so that the heat resistance tends to decrease.

In the film capacitor of the present invention, the thickness of the resin film or the second resin layer is preferably 10 nm or more. If the resin film or the second resin layer is too thin, it becomes difficult to obtain the effect of suppressing the increase in ESR.

In the film capacitor of the present invention, the resin film or the second resin layer is preferably made of a resin different from that of the first resin layer. Examples of the resin different from the first resin layer include polyvinyl acetal resins such as polyvinyl acetal acetal (PVAA) resin and polyvinyl butyl acetal (PVBA) resin.

In the film capacitor of the present invention, the resin constituting the resin film or the second resin layer may be a combination of a polyvinyl acetal resin and MDI or toluene diisocyanate (TDI).

In the film capacitor of the present invention, the resin film or the second resin layer may contain silica particles having an average particle diameter of 5 nm or more and 300 nm. In particular, when the dielectric film contains the second resin layer as the resin film, the silica particles are contained in the second resin layer, so that the surface of the dielectric film is provided with irregularities, so that the friction coefficient of the film is lowered. , The slipperiness of the film is improved.

The silica particles existing in the resin film or the second resin layer can be confirmed by observing the surface of the resin film or the second resin layer with a scanning electron microscope (SEM). Further, when the acceleration voltage is increased during observation by SEM, the diameter of the silica particles existing on the surface of the resin film or the second resin layer becomes larger, and the maximum portion of the portion buried in the resin film or the second resin layer is reached. You can see the diameter of. The area of the silica particles when the size of the silica particles is maximized can be converted into a circle-equivalent diameter to obtain the diameter per silica particle. The average particle diameter of the silica particles is obtained as the average value of the diameters of the silica particles in the field of view.

In the film capacitor of the present invention, the dielectric film is preferably provided on the surface of the first resin layer on the second surface side, and further includes a third resin layer having a chlorine ion content of less than 70 ppm. When the dielectric film contains the third resin layer, it is possible to further suppress an increase in ESR when a voltage is applied to the film capacitor at a high temperature for a long time.

When the dielectric film contains the third resin layer, the content of chlorine ions in the third resin layer is, for example, 3.6 ppm or more. The content of chlorine ions in the third resin layer may be 0 ppm. The content of chlorine ions in the third resin layer may be the same as or different from the content of chlorine ions in the resin film or the second resin layer.

When the dielectric film contains the third resin layer, the third resin layer may be provided on the entire surface of the first resin layer on the second surface side, and the third resin layer may be provided on the entire surface of the first resin layer on the second surface side. It may be provided in a part of.

When the dielectric film contains the third resin layer, the thickness of the third resin layer is preferably 100 nm or less. The thickness of the third resin layer is preferably 10 nm or more. The thickness of the third resin layer may be the same as or different from the thickness of the resin film or the second resin layer.

When the dielectric film contains a third resin layer, the third resin layer is preferably made of a resin different from that of the first resin layer. Examples of the resin different from the first resin layer include polyvinyl acetal resins such as PVAA resin and PVBA resin. The resin constituting the third resin layer may be the same as or different from the resin film or the resin constituting the second resin layer.

In the film capacitor of the present invention, the resin constituting the third resin layer may be a combination of a polyvinyl acetal resin and MDI or TDI.

When the dielectric film contains a third resin layer, the third resin layer may contain silica particles having an average particle diameter of 5 nm or more and 300 nm. The resin film or both the second resin layer and the third resin layer may contain silica particles, or one of them may contain silica particles.

Similar to the resin film or the second resin layer, the silica particles existing in the third resin layer can be confirmed by observing the surface of the third resin layer by SEM. Further, the acceleration voltage is increased during observation by SEM, and the area of the silica particles when the size of the silica particles existing on the surface of the third resin layer is maximized is converted into a circle-equivalent diameter to convert silica. The diameter per particle can be determined. The average particle diameter of the silica particles is obtained as the average value of the diameters of the silica particles in the field of view.

The film capacitor of the present invention is, for example, a columnar column having an oblong cross section, and external terminal electrodes formed by, for example, metal spraying (metallic spraying) are provided at both ends in the central axis direction.

Hereinafter, as an embodiment of the film capacitor of the present invention, a first dielectric film provided with a first metal layer and a second dielectric film provided with a second metal layer are laminated. A winding type film capacitor, which is wound in a state, will be described as an example. The film capacitor of the present invention is a laminated film capacitor in which a first dielectric film provided with a first metal layer and a second dielectric film provided with a second metal layer are laminated. And so on. Further, in the film capacitor of the present invention, a first dielectric film provided with a first metal layer and a second metal layer and a second dielectric film not provided with a metal layer are wound or wound. It may be a laminated film capacitor or the like.

FIG. 1 is a cross-sectional view schematically showing an example of the film capacitor of the present invention.
The film capacitor 10 shown in FIG. 1 is a winding type film capacitor, and is a winding of a metallized film wound in a state where a first metallized film 11 and a second metallized film 12 are laminated. The body 40, the first external terminal electrode 41 connected to one end of the metallised film winder 40, and the second end connected to the other end of the metallised film winder 40. It is provided with an external terminal electrode 42.

As shown in FIG. 1, the first metallized film 11 includes a first dielectric film 13 and a first metal layer (counter electrode) 15 provided on the first surface of the first dielectric film 13. The second metallized film 12 includes a second dielectric film 14 and a second metal layer (counter electrode) 16 provided on the first surface of the second dielectric film 14. ing.

The first dielectric film 13 includes a first resin layer 17, a second resin layer 19 provided on the entire surface of the first resin layer 17 on the first surface side, and a second surface of the first resin layer 17. It includes a third resin layer 21 provided on the entire side surface. The second resin layer 19 is provided between the first metal layer 15 and the first resin layer 17. The third resin layer 21 is provided between the second metal layer 16 and the first resin layer 17. The first dielectric film 13 may not be provided with the third resin layer 21.

The second dielectric film 14 has a first resin layer 18, a second resin layer 20 provided on the entire surface of the first resin layer 18 on the first surface side, and a second surface of the first resin layer 18. It includes a third resin layer 22 provided on the entire side surface. The second resin layer 20 is provided between the second metal layer 16 and the first resin layer 18. The third resin layer 22 is provided between the first metal layer 15 and the first resin layer 18. The second dielectric film 14 may not be provided with the third resin layer 22.

The first dielectric film 13 and the second dielectric film 14 may have different configurations or may have the same configuration.

As shown in FIG. 1, the first metal layer 15 and the second metal layer 16 face each other with the first dielectric film 13 or the second dielectric film 14 interposed therebetween. Further, the first metal layer 15 is electrically connected to the first external terminal electrode 41, and the second metal layer 16 is electrically connected to the second external terminal electrode 42.

As mentioned above, anodization occurs in the metal layer on the positive electrode side. Therefore, for example, when the first external terminal electrode 41 is the external terminal electrode on the positive electrode side and the second external terminal electrode 42 is the external terminal electrode on the negative electrode side, the first dielectric film 13 has a second surface. It suffices if the resin layer 19 is provided, and the second dielectric film 14 may not be provided with the second resin layer 20 and the third resin layer 22.

The first metal layer 15 is formed on the first surface of the first dielectric film 13 so as to reach one side edge but not the other side edge. On the other hand, the second metal layer 16 is formed so as to reach one side edge but not reach the other side edge on the first surface of the second dielectric film 14. The first metal layer 15 and the second metal layer 16 are composed of, for example, an aluminum layer.

As shown in FIG. 1, the end of the first metal layer 15 on the side reaching the side edge of the first dielectric film 13 and the second dielectric film 14 in the second metal layer 16. The first dielectric film 13 and the second dielectric film 14 are in the width direction (left-right direction in FIG. 1) so that the end portion of the side reaching the side edge of the film is exposed from the laminated film. ) And are stacked. By winding the first dielectric film 13 and the second dielectric film 14 in a laminated state, the wound body 40 of the metallized film is formed, and the first metal layer 15 and the second metal layer 16 are formed. Holds the exposed state at the end and is regarded as a stacked state.

In FIG. 1, the first dielectric film 14 is located outside the first dielectric film 13, and the first dielectric film 13 and the second dielectric film 14 are each in the first position. Each of the metal layer 15 and the second metal layer 16 is wound so as to face inward.

The first external terminal electrode 41 and the second external terminal electrode 42 are formed by spraying, for example, zinc or the like onto each end surface of the wound body 40 of the metallized film obtained as described above. .. The first external terminal electrode 41 comes into contact with the exposed end of the first metal layer 15 and is thereby electrically connected to the first metal layer 15. On the other hand, the second external terminal electrode 42 comes into contact with the exposed end of the second metal layer 16 and is thereby electrically connected to the second metal layer 16.

In the film capacitor of the present invention, it is preferable that the wound body of the metallized film is pressed into a flat shape such as an ellipse or an oval, and has a more compact shape than when the cross-sectional shape is a perfect circle. .. The film capacitor of the present invention may have a cylindrical winding shaft. The winding shaft is arranged on the central axis of the metallized film in the wound state, and serves as a winding shaft when winding the metallized film.

In the film capacitor of the present invention, examples of the metal contained in the metal layer include aluminum, titanium, zinc, magnesium, tin, and nickel.

In the film capacitor of the present invention, the thickness of the metal layer is not particularly limited, but is, for example, 5 nm or more and 40 nm or less.

The thickness of the metal layer can be determined by observing a cross section of the dielectric film provided with the metal layer cut in the thickness direction using an electron microscope such as a field emission scanning electron microscope (FE-SEM). Can be identified.

In the film capacitor of the present invention, it is preferable that the metal layer is provided with a fuse portion.

The fuse portion means a portion connecting the electrode portion and the electrode portion in which the metal layer serving as the counter electrode is divided into a plurality of portions. The pattern of the metal layer having the fuse portion is not particularly limited, and for example, the electrode patterns disclosed in JP-A-2004-363431 and JP-A-5-251266 can be used.

FIG. 2 is a plan view schematically showing an example of a metal layer having a fuse portion.
The metal layer 50 shown in FIG. 2 is provided with a fuse portion 51a in which a part of the electrodes is thinned and a split electrode 51c separated by an insulating slit 51b.

In the film capacitor of the present invention, when the fuse portion is provided in the metal layer, even if the resin film or the second resin layer is provided only in the portion where the metal layer and the first resin layer face each other in the thickness direction. good.

In the film capacitor of the present invention, the following film for a film capacitor of the present invention can be used as the dielectric film. For example, in the film capacitor 10 shown in FIG. 1, the film for a film capacitor of the present invention may be used for both the first dielectric film 13 and the second dielectric film 14, or only one of them may be used. The film for a film capacitor of the present invention may be used. In the film capacitor of the present invention, as described above, it is preferable to use the film for a film capacitor of the present invention as a dielectric film provided with at least a metal layer on the positive electrode side. In the film capacitor of the present invention, when the film for the film capacitor of the present invention is used for both the first dielectric film and the second dielectric film, the film for the film capacitor of the same embodiment may be used for both. However, films for film capacitors of different aspects may be used.

[Film for film capacitors]
The film for a film capacitor of the present invention is composed of a dielectric film having a first surface and a second surface facing each other in the thickness direction.

In the film for a film capacitor of the present invention, the dielectric film is provided on the surface of the first resin layer made of a cured product of the first organic material and the second organic material and the surface of the first resin layer on the first surface side. The second resin layer obtained is included. The first organic material is composed of an organic polymer having a hydroxyl group and a benzene ring in a repeating unit. The second organic material consists of MDI, a modified MDI, or a mixture thereof.

Other than that, the structure of the first resin layer is the same as the structure of the first resin layer described in the film capacitor of the present invention.

The film for a film capacitor of the present invention is characterized in that the content of chlorine ions in the second resin layer is less than 70 ppm. The content of chlorine ions in the second resin layer is, for example, 3.6 ppm or more. The content of chlorine ions in the second resin layer may be 0 ppm.

In the film for a film capacitor of the present invention, the second resin layer may be provided on the entire surface of the first resin layer on the first surface side, and is a part of the surface of the first resin layer on the first surface side. It may be provided in.

In the film for a film capacitor of the present invention, the thickness of the second resin layer is preferably 100 nm or less. The thickness of the second resin layer is preferably 10 nm or more.

In the film for a film capacitor of the present invention, the second resin layer is preferably made of a resin different from that of the first resin layer. Examples of the resin different from the first resin layer include polyvinyl acetal resins such as PVAA resin and PVBA resin.

In the film for a film capacitor of the present invention, the resin constituting the second resin layer may be a combination of a polyvinyl acetal resin and MDI or TDI.

In the film for a film capacitor of the present invention, the second resin layer may contain silica particles having an average particle diameter of 5 nm or more and 300 nm.

Other than that, the structure of the second resin layer is the same as the structure of the second resin layer described in the film capacitor of the present invention.

The film for a film capacitor of the present invention is preferably provided on the surface of the first resin layer on the second surface side, and further includes a third resin layer having a chlorine ion content of less than 70 ppm.

When the film for a film capacitor of the present invention contains a third resin layer, the content of chlorine ions in the third resin layer is, for example, 3.6 ppm or more. The content of chlorine ions in the third resin layer may be 0 ppm. The content of chlorine ions in the third resin layer may be the same as or different from the content of chlorine ions in the second resin layer.

When the film for a film capacitor of the present invention includes a third resin layer, the third resin layer may be provided on the entire surface of the first resin layer on the second surface side, and the second resin layer may be provided. It may be provided on a part of the surface on the surface side.

When the film for a film capacitor of the present invention contains a third resin layer, the thickness of the third resin layer is preferably 100 nm or less. The thickness of the third resin layer is preferably 10 nm or more. The thickness of the third resin layer may be the same as or different from the thickness of the second resin layer.

When the film for a film capacitor of the present invention contains a third resin layer, it is preferable that the third resin layer is made of a resin different from that of the first resin layer. Examples of the resin different from the first resin layer include polyvinyl acetal resins such as PVAA resin and PVBA resin. The resin constituting the third resin layer may be the same as or different from the resin constituting the second resin layer.

In the film for a film capacitor of the present invention, the resin constituting the third resin layer may be a combination of a polyvinyl acetal resin and MDI or TDI.

When the film for a film capacitor of the present invention contains a third resin layer, the third resin layer may contain silica particles having an average particle diameter of 5 nm or more and 300 nm. It should be noted that both the second resin layer and the third resin layer may contain silica particles, or one of them may contain silica particles.

Other than that, the structure of the third resin layer is the same as the structure of the third resin layer described in the film capacitor of the present invention.

[Manufacturing method of film for film capacitors]
Hereinafter, an example of a method for manufacturing a film for a film capacitor of the present invention will be described.

First, a first resin solution containing the first organic material and the second organic material is applied to the base film. Preferably, after applying the first resin solution to the base film, hot air is blown to dry the solvent. As a result, the first resin layer is formed.

As the base film, for example, a polypropylene (PP) film or the like can be used.

The first resin solution is prepared, for example, by dissolving the above-mentioned first organic material and second organic material in a solvent, mixing them, and adding additives as necessary. The solvent contained in the first resin solution may be present as a residue in the first resin layer after curing. The weight ratio of the first organic material to the second organic material (first organic material / second organic material) is preferably 50/50 or more and 75/25 or less.

As the solvent, methyl ethyl ketone (MEK), tetrahydrofuran (THF) and the like can be used. These solvents may be used alone or in combination of two or more. Above all, it is preferable to use a mixed solvent containing MEK and THF. The weight ratio of MEK to THF (MEK / THF) is preferably 15/85 or more and 85/15 or less.

Next, a second resin solution containing a resin having a chlorine ion content of less than 70 ppm is applied to the first resin layer on the base film. Preferably, after applying the second resin solution to the first resin layer, hot air is blown to dry the solvent. As a result, the second resin layer is formed.

The second resin solution is prepared, for example, by dissolving a resin different from the above-mentioned first resin layer in a solvent and adding an additive as necessary. The second resin solution may contain silica particles having an average particle diameter of 5 nm or more and 300 nm.

As the solvent for dissolving the PVAA resin, for example, MEK or the like can be used. As the solvent for dissolving the PVBA resin, for example, isopropyl alcohol (IPA) or the like can be used. The solvent may be used alone or in combination of two or more.

The two-layer film including the first resin layer and the second resin layer is peeled off from the base film.

If necessary, a third resin solution containing a resin having a chlorine ion content of less than 70 ppm is applied to the surface of the first resin layer opposite to the second resin layer. Preferably, after applying the third resin solution to the first resin layer, hot air is blown to dry the solvent. Thereby, the third resin layer may be formed.

The third resin solution is prepared, for example, by dissolving a resin different from the above-mentioned first resin layer in a solvent and adding an additive as necessary. The third resin solution may contain silica particles having an average particle diameter of 5 nm or more and 300 nm. The third resin solution may be the same as or different from the second resin solution.

Then, the two-layer or three-layer film is heat-treated to cure the resin. From the above, a film for a film capacitor can be obtained.

[Manufacturing method of film capacitors]
Subsequently, an example of the method for manufacturing the film capacitor of the present invention will be described.
First, a metallized film is obtained by forming a metal layer on the first surface of the dielectric film using the film for a film capacitor of the present invention as a dielectric film. At this time, the surface on which the second resin layer is formed is referred to as the first surface of the dielectric film. Examples of the method for forming the metal layer include a method such as thin film deposition.

A laminated body is obtained by stacking two metallized films having a metal layer formed on the first surface of a dielectric film in a state of being displaced by a predetermined distance in the width direction and then winding the film. If necessary, the laminate may be sandwiched from a direction perpendicular to the width direction and pressed into an elliptical cylinder shape.

Subsequently, by forming an external terminal electrode on the end face of the laminated body, a film capacitor as shown in FIG. 1 can be obtained. As a method of forming an external terminal electrode on the end face of the laminated body, thermal spraying can be mentioned.

The film capacitor of the present invention is not limited to the above embodiment, and various applications and modifications can be added within the scope of the present invention regarding the configuration of the film capacitor, manufacturing conditions, and the like.

For example, in the film capacitor of the present invention, the film for a film capacitor of the present invention may not be used as the dielectric film. That is, in the film capacitor of the present invention, the resin film does not have to be a part of the dielectric film.

In the film capacitor of the present invention, the resin film does not have to be in direct contact with the first resin layer. Further, the resin film does not have to be in direct contact with the metal layer provided on the first surface of the dielectric film.

In the film capacitor of the present invention, the second resin layer does not have to be in direct contact with the first resin layer. For example, another resin layer may be provided between the first resin layer and the second resin layer. Further, the second resin layer does not have to be in direct contact with the metal layer provided on the first surface of the dielectric film. For example, another resin layer may be provided between the metal layer provided on the first surface of the dielectric film and the second resin layer.

In the film capacitor of the present invention, when the dielectric film contains the third resin layer, the third resin layer does not have to be in direct contact with the first resin layer. For example, another resin layer may be provided between the first resin layer and the third resin layer. Further, another resin layer may be provided on the surface of the third resin layer opposite to the first resin layer.

Similarly, in the film for a film capacitor of the present invention, the second resin layer does not have to be in direct contact with the first resin layer. For example, another resin layer may be provided between the first resin layer and the second resin layer. Further, another resin layer may be provided on the surface of the second resin layer opposite to the first resin layer.

When the film for a film capacitor of the present invention includes a third resin layer, the third resin layer does not have to be in direct contact with the first resin layer. For example, another resin layer may be provided between the first resin layer and the third resin layer. Further, another resin layer may be provided on the surface of the third resin layer opposite to the first resin layer.

Hereinafter, an example in which the film capacitor of the present invention and the film for a film capacitor are disclosed more specifically will be shown. The present invention is not limited to these examples.

[Preparation of coating liquid (resin solution)]
(Coating liquid 1)
As the first organic material, a phenoxy resin having a chlorine ion content of about 600 ppm was prepared, and as the second organic material, a mixture of MDI and an MDI modified product was prepared. The first organic material and the second organic material are dissolved in a mixed solvent of MEK and THF and mixed, and a silicone-based surface conditioner BYK370 (manufactured by Big Chemie Japan Co., Ltd.) is further added to add the coating liquid 1. Prepared. The weight ratio of the first organic material to the second organic material was set to 1st organic material / 2nd organic material = 70/30, and the weight ratio of MEK to THF was set to MEK / THF = 50/50.

(Coating liquid 2)
A PVAA resin having a chlorine ion content of 3.6 ppm was dissolved in MEK to prepare a coating liquid 2.

(Coating liquid 3)
A PVBA resin having a chlorine ion content of 65 ppm was dissolved in IPA to prepare a coating liquid 3.

(Coating liquid 4)
A phenoxy resin having a chlorine ion content of about 600 ppm was dissolved in a mixed solvent of MEK / THF = 50/50 (weight ratio) to prepare a coating liquid 4.

(Coating liquid 5)
A PVAA resin having a chlorine ion content of 3.6 ppm and a mixture of MDI and a modified MDI were mixed, dissolved in a mixed solvent of MEK and THF, and mixed to prepare a coating liquid 5. The weight ratio of PVAA to the MDI mixture was PVAA / MDI = 70/30, and the weight ratio of MEK to THF was MEK / THF = 50/50.

(Coating liquid 6)
A PVAA resin having a chlorine ion content of 3.6 ppm and a trimethylolpropane adduct of TDI were blended, dissolved in a mixed solvent of MEK and THF, and mixed to prepare a coating liquid 6. The weight ratio of PVAA to the TDI adduct body was PVAA / TDI = 60/40, and the weight ratio of MEK to THF was MEK / THF = 50/50.

(Coating liquid 7)
A phenoxy resin having a chlorine ion content of 600 ppm and a mixture of MDI and a modified MDI were mixed, dissolved in a mixed solvent of MEK and THF, and mixed to prepare a coating liquid 7. The weight ratio of the phenoxy resin to the MDI mixture was phenoxy / MDI = 70/30, and the weight ratio of MEK to THF was MEK / THF = 50/50.

[Preparation of sample film]
Using the prepared coating liquids 1 to 7, a sample film having the structure shown in FIG. 3, FIG. 4 or FIG. 5 was prepared.

FIG. 3 is a cross-sectional view schematically showing a sample film in which the second resin layer is provided on the first resin layer.
In the sample film 100A shown in FIG. 3, the second resin layer 120 is provided on the first resin layer 110.

FIG. 4 is a cross-sectional view schematically showing a sample film in which the second resin layer and the third resin layer are provided on the first resin layer.
In the sample film 100B shown in FIG. 4, the second resin layer 120 and the third resin layer 130 are provided on the first resin layer 110.

FIG. 5 is a cross-sectional view schematically showing a sample film to which the second resin layer and the third resin layer are not provided.
The sample film 100C shown in FIG. 5 contains only the first resin layer 110.

(Sample film 1)
After the coating liquid 1 was applied to a PP film as a base film, the solvent was dried by applying hot air at 70 ° C. to form a first resin layer having a thickness of 3 μm. Next, the coating liquid 2 was applied to the first resin layer on the PP film, and then the solvent was dried by applying hot air at 70 ° C. to form a second resin layer having a thickness of about 50 nm. The two-layer film produced above was peeled off from the PP film. The two-layer film peeled off from the PP film was heat-treated at 150 ° C. for 4 hours to be cured. From the above, the sample film 1 having the structure shown in FIG. 3 was produced.

(Sample film 2)
After the coating liquid 1 was applied to the PP film, the solvent was dried by applying hot air at 70 ° C. to form a first resin layer having a thickness of 3 μm. Next, the coating liquid 2 was applied to the first resin layer on the PP film, and then the solvent was dried by applying hot air at 70 ° C. to form a second resin layer having a thickness of about 50 nm. The two-layer film produced above was peeled off from the PP film. With respect to the two-layered film peeled from the PP film, the coating liquid 2 was applied to the surface of the first resin layer opposite to the second resin layer, and then hot air at 70 ° C. was applied to dry the solvent. A third resin layer having a thickness of about 50 nm was formed. The three-layered film produced above was heat-treated at 150 ° C. for 4 hours to be cured. From the above, the sample film 2 having the structure shown in FIG. 4 was produced.

(Sample film 3)
After the coating liquid 1 was applied to the PP film, the solvent was dried by applying hot air at 70 ° C. to form a first resin layer having a thickness of 3 μm. Next, the coating liquid 3 was applied to the first resin layer on the PP film, and then the solvent was dried by applying hot air at 70 ° C. to form a second resin layer having a thickness of about 50 nm. The two-layer film produced above was peeled off from the PP film. The two-layer film peeled off from the PP film was heat-treated at 150 ° C. for 4 hours to be cured. As described above, the sample film 3 having the structure shown in FIG. 3 was produced.

(Sample film 4)
After the coating liquid 1 was applied to the PP film, the solvent was dried by applying hot air at 70 ° C. to form a first resin layer having a thickness of 3 μm. Next, the coating liquid 3 was applied to the first resin layer on the PP film, and then the solvent was dried by applying hot air at 70 ° C. to form a second resin layer having a thickness of about 50 nm. The two-layer film produced above was peeled off from the PP film. With respect to the two-layered film peeled from the PP film, the coating liquid 3 was applied to the surface of the first resin layer opposite to the second resin layer, and then hot air at 70 ° C. was applied to dry the solvent. A third resin layer having a thickness of about 50 nm was formed. The three-layered film produced above was heat-treated at 150 ° C. for 4 hours to be cured. From the above, the sample film 4 having the structure shown in FIG. 4 was produced.

(Sample film 5)
After the coating liquid 1 was applied to the PP film, the solvent was dried by applying hot air at 70 ° C. to form a first resin layer having a thickness of 3 μm. Next, the coating liquid 5 was applied to the first resin layer on the PP film, and then hot air at 70 ° C. was applied to dry the solvent to form a second resin layer having a thickness of about 50 nm. The two-layer film produced above was peeled off from the PP film. The two-layer film peeled off from the PP film was heat-treated at 150 ° C. for 4 hours to be cured. As a result, the sample film 5 having the structure shown in FIG. 3 was produced.

(Sample film 6)
After the coating liquid 1 was applied to the PP film, the solvent was dried by applying hot air at 70 ° C. to form a first resin layer having a thickness of 3 μm. Next, the coating liquid 6 was applied to the first resin layer on the PP film, and then hot air at 70 ° C. was applied to dry the solvent to form a second resin layer having a thickness of about 50 nm. The two-layer film produced above was peeled off from the PP film. The two-layer film peeled off from the PP film was heat-treated at 150 ° C. for 4 hours to be cured. From the above, the sample film 6 having the structure shown in FIG. 3 was produced.

(Sample film 7)
After the coating liquid 1 was applied to the PP film, the solvent was dried by applying hot air at 70 ° C. to form a first resin layer having a thickness of 3 μm. Next, the coating liquid 5 was applied to the first resin layer on the PP film, and then hot air at 70 ° C. was applied to dry the solvent to form a second resin layer having a thickness of about 50 nm. The two-layer film produced above was peeled off from the PP film. With respect to the two-layered film peeled from the PP film, the coating liquid 5 was applied to the surface of the first resin layer opposite to the second resin layer, and then hot air at 70 ° C. was applied to dry the solvent. A third resin layer having a thickness of about 50 nm was formed. The three-layered film produced above was heat-treated at 150 ° C. for 4 hours to be cured. From the above, the sample film 7 having the structure shown in FIG. 4 was produced.

(Sample film 8)
After the coating liquid 1 was applied to the PP film, the solvent was dried by applying hot air at 70 ° C. to form a first resin layer having a thickness of 3 μm. The one-layer film produced above was peeled off from the PP film. The one-layer film peeled from the PP film was heat-treated at 150 ° C. for 4 hours to be cured. As a result, the sample film 8 having the structure shown in FIG. 5 was produced.

(Sample film 9)
After the coating liquid 1 was applied to the PP film, the solvent was dried by applying hot air at 70 ° C. to form a first resin layer having a thickness of 3 μm. Next, the coating liquid 4 was applied to the first resin layer on the PP film, and then hot air at 70 ° C. was applied to dry the solvent to form a second resin layer having a thickness of about 50 nm. The two-layer film produced above was peeled off from the PP film. The two-layer film peeled off from the PP film was heat-treated at 150 ° C. for 4 hours to be cured. From the above, the sample film 9 having the structure shown in FIG. 3 was produced.

(Sample film 10)
After the coating liquid 1 was applied to the PP film, the solvent was dried by applying hot air at 70 ° C. to form a first resin layer having a thickness of 3 μm. Next, the coating liquid 7 was applied to the first resin layer on the PP film, and then hot air at 70 ° C. was applied to dry the solvent to form a second resin layer having a thickness of about 50 nm. The two-layer film produced above was peeled off from the PP film. The two-layer film peeled off from the PP film was heat-treated at 150 ° C. for 4 hours to be cured. From the above, the sample film 10 having the structure shown in FIG. 3 was produced.

[Sample evaluation]
For the sample films 1 to 10, aluminum films were provided on both sides of the film by vacuum vapor deposition so as to have a thickness of 20 nm. From the above, samples 1 to 10 were prepared.

A DC voltage of 600 V was applied to the prepared sample in an atmosphere of 135 ° C., and the ESR (frequency 1 kHz) of the sample was recorded over time. The measurement was terminated when the rate of change from the initial stage of ESR reached 120%. An LCR meter Z2371 manufactured by N-Neff Circuit Design Block Co., Ltd. was used for the measurement of ESR. The aluminum film provided on the second resin layer was used as the electrode on the positive electrode side.

Table 1 shows the results of summarizing the film composition and the time when the ESR change rate became 120% for the samples 1 to 10.

In Table 1, the samples marked with * are comparative examples outside the scope of the present invention.

As shown in Table 1, in Samples 1 to 7, the increase in ESR is suppressed. It is considered that this is because there are few aluminum films that are in direct contact with the first resin layer. In particular, in the samples 2, 4 and 7 in which the aluminum film is not in direct contact with the first resin layer, the increase in ESR is suppressed.

On the other hand, in the samples 8 to 10 in which the aluminum film is in direct contact with the first resin layer, the time for the ESR to rise is fast. It is presumed that this is because the chlorine ions in the phenoxy resin constituting the first resin layer act as a catalyst to promote the insulation of the aluminum film.

10 Film capacitor 11 First metallized film 12 Second metallized film 13 First dielectric film 14 Second dielectric film 15 First metal layer 16 Second metal layer 17 First dielectric film 1st resin layer 18 1st resin layer of 2nd dielectric film 19 2nd resin layer of 1st dielectric film 20 2nd resin layer of 2nd dielectric film 21 1st of 1st dielectric film 3 Resin layer 22 Third resin layer of second dielectric film 40 Winder of metallized film 41 First external terminal electrode 42 Second external terminal electrode 50 Metal layer 51a Fuse part 51b Insulation slit 51c Divided electrode 100A , 100B, 100C Sample film 110 First resin layer of sample film 120 Second resin layer of sample film 130 Third resin layer of sample film

Claims (9)

A dielectric film having first and second surfaces facing each other in the thickness direction,
A metal layer provided on at least the first surface of the dielectric film is provided.
The dielectric film contains a first resin layer made of a cured product of a first organic material and a second organic material.
The first organic material is composed of an organic polymer having a hydroxyl group and a benzene ring in a repeating unit.
The second organic material comprises 4,4'-diphenylmethane diisocyanate, a modified 4,4'-diphenylmethane diisocyanate, or a mixture thereof.
A film capacitor in which a resin film having a chlorine ion content of less than 70 ppm is provided between the metal layer provided on the first surface of the dielectric film and the first resin layer. The resin film is a part of the dielectric film and is
The film capacitor according to claim 1, wherein the dielectric film further includes a second resin layer provided on the surface of the first resin layer on the first surface side as the resin film. The film according to claim 1 or 2, wherein the dielectric film is provided on the surface of the first resin layer on the second surface side and further includes a third resin layer having a chlorine ion content of less than 70 ppm. Capacitor. The film capacitor according to any one of claims 1 to 3, wherein the thickness of the resin film is 100 nm or less. The film capacitor according to claim 4, wherein the thickness of the resin film is 10 nm or more. It is composed of a dielectric film having a first surface and a second surface facing each other in the thickness direction.
The dielectric film includes a first resin layer made of a cured product of a first organic material and a second organic material, and a second resin layer provided on the surface of the first resin layer on the first surface side. Including
The first organic material is composed of an organic polymer having a hydroxyl group and a benzene ring in a repeating unit.
The second organic material comprises 4,4'-diphenylmethane diisocyanate, a modified 4,4'-diphenylmethane diisocyanate, or a mixture thereof.
A film for a film capacitor in which the content of chlorine ions in the second resin layer is less than 70 ppm. The film for a film capacitor according to claim 6, further comprising a third resin layer provided on the surface of the first resin layer on the second surface side and having a chlorine ion content of less than 70 ppm. The film for a film capacitor according to claim 6 or 7, wherein the thickness of the second resin layer is 100 nm or less. The film for a film capacitor according to claim 8, wherein the thickness of the second resin layer is 10 nm or more.

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