film capacitors

Abstract

The present invention provides a film capacitor in which a metal layer serving as an electrode is not easily oxidized even when a voltage is applied for a long time in a high-temperature environment. The film capacitor (10) comprises a dielectric resin film (13, 14) containing a thermosetting urethane resin and a metal layer (15, 16) provided on at least one surface of the dielectric resin film (13, 14). The dielectric resin film (13, 14) contains at least an isocyanate group and a carbonyl group. The wave number is 2200 cm ‑1 Above 2350cm ‑1 The absorption peak intensity of the isocyanate group detected in the following range is relative to the wave number: 1650 cm ‑1 Over 1800cm ‑1 The ratio of the absorption peak intensity of the carbonyl group detected within the following range (absorption peak intensity of the isocyanate group / absorption peak intensity of the carbonyl group) is 0.08 or more and 1.15 or less.

Description

Technical Field

[0001] The present invention relates to film capacitors. Background Art

[0002] One type of capacitor is a film capacitor that uses a flexible resin film as a dielectric and has first and second opposing electrodes disposed therebetween, facing each other with the resin film interposed therebetween. Typically, a film capacitor has a roughly cylindrical shape formed by winding the aforementioned resin film as a dielectric, with first and second external terminal electrodes formed on the first and second opposing end faces of the cylinder, respectively. Furthermore, the first opposing electrode is electrically connected to the first external terminal electrode, and the second opposing electrode is electrically connected to the second external terminal electrode.

[0003] As the above-mentioned thin film capacitor, International Publication No. 2017 / 175511 (Patent Document 1) discloses the following thin film capacitor, which includes a dielectric resin film, and a first opposing electrode and a second opposing electrode that are opposed to each other with the dielectric resin film sandwiched therebetween. The thin film capacitor is characterized in that the dielectric resin film is a capacitor film comprising a crosslinked product of a first organic material and a second organic material, the second organic material is a polyisocyanate having multiple isocyanate groups, and the first organic material has multiple hydroxyl groups and a branched structure.

[0004] Patent Document 1 discloses that a phenoxy resin such as a high-molecular-weight bisphenol A epoxy resin, a polyol such as a polyether polyol, or a polyester polyol is used as the first organic material. Furthermore, Patent Document 1 discloses that a polyisocyanate such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI) is used as the second organic material.

[0005] Patent Document 1 describes that the weight ratio of the first organic material (phenoxy resin, polyol) is preferably higher than the weight ratio of the second organic material (polyisocyanate).

[0006] Furthermore, Patent Document 1 describes that it is preferable that the number of hydroxyl group residues is larger than the number of isocyanate group residues.

[0007] Patent Document 1 also describes a film capacitor in which the counter electrode is formed, for example, from an aluminum film vapor-deposited on the surface of a dielectric resin film. Furthermore, Patent Document 1 describes a capacitor element obtained by overlapping and winding a first dielectric resin film and a second dielectric resin film, each of which has a counter electrode formed thereon, and forming external terminal electrodes at both ends thereof by, for example, spraying zinc.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: International Publication No. 2017 / 175511 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] Film capacitors are also used for inverter smoothing in electric vehicles, etc. As film capacitors used in such applications have become more energy-dense, voltage is more often applied to them for long periods of time in high-temperature environments than before.

[0013] Thin-film capacitors used in these applications suffer from the problem of gradual oxidation of vapor-deposited electrodes, such as aluminum films, leading to an increase in the film capacitor's equivalent series resistance (ESR). In particular, the vapor-deposited electrode on the positive (+) side is prone to electrochemical reactions with hydroxide ions derived from surrounding water, increasing the tendency of the vapor-deposited electrode to oxidize.

[0014] Furthermore, if oxidation of the vapor-deposited electrode progresses, the electrode function is lost, and the problem of reduced capacitance arises.

[0015] As described in Patent Document 1, thin film capacitors have high heat resistance and can be used even in environments exceeding 125° C. However, the problem of accelerated oxidation of vapor-deposited electrodes has become increasingly prominent.

[0016] Furthermore, for example, in the film capacitor described in Patent Document 1, the dielectric resin film comprises a urethane-based material, which is a polymerized structure of hydroxyl and isocyanate groups. When the dielectric resin film comprises a urethane-based material, due to its high hygroscopicity, the dielectric resin film readily absorbs moisture from the environment. When the dielectric resin film absorbs moisture from the environment, the vapor-deposited electrodes disposed on the dielectric resin film are susceptible to oxidation due to the moisture. Therefore, the inclusion of a urethane-based material in the dielectric resin film is a major factor in exacerbating the problem of oxidation of the vapor-deposited electrodes.

[0017] As described above, in film capacitors whose dielectric resin film comprises a thermosetting urethane resin, as described in Patent Document 1, the phenomenon of the vapor-deposited electrode becoming easily oxidized due to use in a high-temperature environment and the phenomenon of the vapor-deposited electrode becoming easily oxidized due to absorption of ambient moisture tends to occur simultaneously. As a result, oxidation of the vapor-deposited electrode is accelerated, and the problem of increased ESR is becoming increasingly prominent.

[0018] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a thin film capacitor in which a metal layer serving as an electrode is not easily oxidized even when a voltage is applied for a long period of time in a high-temperature usage environment.

[0019] Technical solutions to solve problems

[0020] The film capacitor of the present invention comprises a dielectric resin film containing a thermosetting urethane resin and a metal layer provided on at least one surface of the dielectric resin film, wherein the dielectric resin film contains at least an isocyanate group and a carbonyl group. The wave number is 2200 cm -1 Above 2350cm -1 The absorption peak intensity of the isocyanate group detected in the following range is relative to the wave number: 1650 cm -1 Over 1800cm -1 The ratio of the absorption peak intensity of the carbonyl group detected within the following range (absorption peak intensity of the isocyanate group / absorption peak intensity of the carbonyl group) is 0.08 or more and 1.15 or less.

[0021] Effects of the Invention

[0022] According to the present invention, it is possible to provide a thin film capacitor in which a metal layer serving as an electrode is not easily oxidized even when a voltage is applied for a long period of time in a high-temperature usage environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a perspective view schematically showing an example of the film capacitor of the present invention.

[0024] Figure 2 yes Figure 1 The film capacitor is shown in a cross-sectional view taken along line II-II.

[0025] Figure 3 It schematically shows the structure Figure 1 as well as Figure 2 The figure shows a perspective view of an example of a wound body of a metallized film of a film capacitor. DETAILED DESCRIPTION

[0026] Hereinafter, the film capacitor of the present invention will be described.

[0027] However, the present invention is not limited to the following configurations, and can be applied with appropriate modifications within the scope of the present invention.

[0028] Combinations of two or more of the preferred structures of the present invention described below also constitute the present invention.

[0029] Film capacitors

[0030] The film capacitor of the present invention includes a dielectric resin film and a metal layer provided on at least one surface of the dielectric resin film.

[0031] The film capacitor of the present invention is, for example, in the shape of a column having an oblong cross section, and external terminal electrodes formed by, for example, metallization are provided at both ends in the central axis direction.

[0032] The following describes an embodiment of a film capacitor according to the present invention, using as an example a wound-type film capacitor in which a first dielectric resin film provided with a first metal layer and a second dielectric resin film provided with a second metal layer are wound in a stacked state. The film capacitor according to the present invention may also be a stacked-type film capacitor in which a first dielectric resin film provided with a first metal layer and a second dielectric resin film provided with a second metal layer are stacked.

[0033] Furthermore, the film capacitor of the present invention may be a film capacitor in which a first dielectric resin film having a first metal layer and a second metal layer provided on the front and back surfaces, respectively, and a second dielectric resin film having no metal layer are wound or stacked.

[0034] Figure 1 This is a perspective view schematically showing an example of the film capacitor of the present invention. Figure 2 yes Figure 1 The film capacitor is shown in a cross-sectional view taken along line II-II.

[0035] Figure 1 as well as Figure 2 The film capacitor 10 shown is a wound film capacitor, comprising a wound body 40 of a metalized film in which a first metalized film 11 and a second metalized film 12 are wound in a stacked state, and a first external terminal electrode 41 and a second external terminal electrode 42 connected to both ends of the wound body 40 of the metalized film. Figure 2 As shown, the first metallized film 11 includes a first dielectric resin film 13 and a first metal layer (counter electrode) 15 provided on one surface of the first dielectric resin film 13. The second metallized film 12 includes a second dielectric resin film 14 and a second metal layer (counter electrode) 16 provided on one surface of the second dielectric resin film 14.

[0036] like Figure 2 As shown, the first metal layer 15 and the second metal layer 16 face each other with the first dielectric resin film 13 or the second dielectric resin film 14 interposed therebetween. Furthermore, 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 .

[0037] The first dielectric resin film 13 and the second dielectric resin film 14 may have different structures, but preferably have the same structure. Preferred structures of the first dielectric resin film 13 and the second dielectric resin film 14 will be described later.

[0038] The first metal layer 15 is formed so as to reach one side edge but not the other side edge on one surface of the first dielectric resin film 13. Thus, a strip-shaped first insulating portion 13a is formed on one surface of the first dielectric resin film 13 at the other side edge.

[0039] On the other hand, the second metal layer 16 is formed so as to reach the other side edge instead of one side edge on one surface of the second dielectric resin film 14. Thus, a strip-shaped second insulating portion 14a is formed on one side edge of one surface of the second dielectric resin film 14.

[0040] The first metal layer 15 and the second metal layer 16 include, for example, aluminum layers.

[0041] Figure 3 It schematically shows the structure Figure 1 as well as Figure 2 The figure shows a perspective view of an example of a wound body of a metallized film of a film capacitor.

[0042] like Figure 2 as well as Figure 3 As shown, the first dielectric resin film 13 and the second dielectric resin film 14 are arranged in the width direction (in Figure 2 The first metal layer 15 and the second metal layer 16 are stacked with their ends staggered in the left-right direction (in the left-right direction) so that the end portion of the first metal layer 15 that reaches the side edge of the first dielectric resin film 13 and the end portion of the second metal layer 16 that reaches the side edge of the second dielectric resin film 14 are both exposed from the stacked films. The first dielectric resin film 13 and the second dielectric resin film 14 are wound in a stacked state to form a metallized film roll 40. The first metal layer 15 and the second metal layer 16 are stacked with their ends exposed.

[0043] exist Figure 2 as well as Figure 3 The second dielectric resin film 14 is wound outside the first dielectric resin film 13, and the first metal layer 15 and the second metal layer 16 of each of the first dielectric resin film 13 and the second dielectric resin film 14 are directed inward.

[0044] The first external terminal electrode 41 and the second external terminal electrode 42 are formed by thermally spraying, for example, zinc, onto the end surfaces of the wound body 40 of the metallized film obtained as described above. The first external terminal electrode 41 contacts the exposed end portion of the first metal layer 15 and is thereby electrically connected to the first metal layer 15. Meanwhile, the second external terminal electrode 42 contacts the exposed end portion of the second metal layer 16 and is thereby electrically connected to the second metal layer 16.

[0045] In the film capacitor of the present invention, the wound metallized film is preferably pressed into a flattened shape, such as an elliptical or oblong cross-section, making it more compact than a film capacitor with a perfectly circular cross-section. Furthermore, the film capacitor of the present invention may also include a cylindrical winding shaft. The winding shaft is positioned along the central axis of the wound metallized film and serves as the winding axis for winding the metallized film.

[0046] [Metal layer]

[0047] In the thin film capacitor of the present invention, examples of the metal contained in the metal layer include aluminum (Al), titanium (Ti), zinc (Zn), magnesium (Mg), tin (Sn), and nickel (Ni).

[0048] In the film capacitor of the present invention, the metal layer is formed by, for example, vapor-depositing the above-mentioned metal on a dielectric resin film.

[0049] In the thin film capacitor of the present invention, the thickness of the metal layer is not particularly limited, but is, for example, 5 nm to 40 nm.

[0050] The thickness of the metal layer can be determined by observing a cross section of the dielectric resin 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).

[0051] In the thin film capacitor of the present invention, a fuse portion is preferably provided in the metal layer.

[0052] The so-called fuse portion refers to the portion where the metal layer that will become the counter electrode is divided into multiple electrode portions and the electrode portions are connected. The pattern of the metal layer having the fuse portion is not particularly limited. For example, the electrode patterns disclosed in Japanese Patent Application Publication No. 2004-363431 and Japanese Patent Application Publication No. 5-251266 can be used.

[0053] [Dielectric resin film]

[0054] In the film capacitor of the present invention, the dielectric resin film comprises a thermosetting urethane resin containing at least an isocyanate group and a carbonyl group. Also, the wave number is 2200 cm -1 Above 2350cm -1The absorption peak intensity of the isocyanate group detected in the following range is relative to the wave number: 1650 cm -1 Over 1800cm -1 The ratio of the absorption peak intensity of the carbonyl group detected within the following range (absorption peak intensity of the isocyanate group / absorption peak intensity of the carbonyl group) is 0.08 to 1.15. The ratio of the absorption peak intensity of the isocyanate group to the absorption peak intensity of the carbonyl group is preferably 0.1 to 1.0, more preferably 0.2 to 0.8.

[0055] In the film capacitor of the present invention, when the ratio of the absorption peak intensity of the isocyanate group to the absorption peak intensity of the carbonyl group is within the above-mentioned range, when the dielectric resin film of the film capacitor of the present invention absorbs moisture, the isocyanate group reacts with the moisture first and is consumed, thereby suppressing oxidation of the metal layer due to moisture.

[0056] Based on this principle, even when a voltage is applied to the thin film capacitor of the present invention for a long period of time in a high-temperature usage environment, oxidation of the metal layer serving as the electrode can be suppressed.

[0057] As a result, even when voltage is applied to the film capacitor of the present invention for a long time in a high-temperature environment, the equivalent series resistance (ESR) of the capacitor is unlikely to increase. In other words, it can be said that the film capacitor of the present invention has high high-temperature durability.

[0058] Furthermore, as described above, even when voltage is applied for a long period of time in a high-temperature usage environment, oxidation of the metal layer serving as the electrode can be suppressed. Therefore, in the film capacitor of the present invention, the electrostatic capacitance is less likely to decrease.

[0059] If the ratio of the absorption peak intensity of the isocyanate group to the absorption peak intensity of the carbonyl group is less than 0.08, the number of isocyanate groups present is small, so the equivalent series resistance of the capacitor is likely to increase, and the electrostatic capacitance is likely to decrease.

[0060] On the other hand, if the ratio of the isocyanate group absorption peak intensity to the carbonyl group absorption peak intensity exceeds 1.15, the number of isocyanate groups present increases. Consequently, the dielectric resin film approaches an uncured state, making it difficult to function as a dielectric resin film. Consequently, the capacitor's equivalent series resistance tends to increase, and the capacitance tends to decrease.

[0061] In addition, in this specification, "absorption peak intensity" means a value calculated as follows.

[0062] First, the infrared absorption spectrum of the dielectric resin film is measured by attenuated total reflection (ATR) using a Fourier transform infrared spectrophotometer (FT-IR).

[0063] Next, the absorption band observed in a given wavenumber region is defined as the absorption band based on a given functional group, a baseline is drawn on both sides of each peak, and the value from the baseline to the peak intensity is defined as the "absorption peak intensity" of the functional group.

[0064] In the film capacitor of the present invention, the water content of the dielectric resin film is preferably 0.4 wt % or less.

[0065] If the water content of the dielectric resin film is 0.4% by weight or less, the water content is sufficiently low, thereby suppressing the reaction between water and isocyanate groups in the dielectric resin film, thereby reducing the number of unreacted isocyanate groups. As a result, oxidation of the metal layer can be significantly suppressed.

[0066] Furthermore, in the film capacitor of the present invention, the water content of the dielectric resin film is preferably 0.01% by weight or more.

[0067] If the water content in the dielectric resin film is less than 0.01 wt %, it is expected that the dielectric resin film will become fragile.

[0068] In this specification, the "water content of the dielectric resin film" is a value measured by a hydride reaction method (ISO 15512:2019 Method E) at a heating temperature of 130°C.

[0069] In the film capacitor of the present invention, the thickness of the dielectric resin film is not particularly limited. However, if the dielectric resin film is too thin, it tends to become brittle. Therefore, the thickness of the dielectric resin film is preferably 1 μm or greater, more preferably 3 μm or greater. On the other hand, if the film is too thick, defects such as cracks are more likely to form during film formation. Therefore, the thickness of the dielectric resin film is preferably 10 μm or less, more preferably 5 μm or less.

[0070] The thickness of the dielectric resin film refers to the thickness of the dielectric resin film alone, excluding the thickness of the metal layer. The thickness of the dielectric resin film can be measured using an optical film thickness meter.

[0071] In the film capacitor of the present invention, the dielectric resin film includes, for example, a cured product of a first organic material having a hydroxyl group (OH group) and a second organic material having an isocyanate group (NCO group).

[0072] Specifically, the dielectric resin film includes a cured product obtained by reacting a hydroxyl group of the first organic material with an isocyanate group of the second organic material.

[0073] The first organic material may be an organic polymer having a hydroxyl group and a benzene ring in a repeating unit. Examples of such a compound include phenoxy resins.

[0074] As the phenoxy resin, for example, bisphenol A-type phenoxy resin, bisphenol F-type phenoxy resin, etc. are preferable.

[0075] Examples of the second organic material include diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI). Among these compounds, MDI or TDI is preferred. Furthermore, these may include modified polyisocyanates thereof, and these may be used in combination.

[0076] In the film capacitor of the present invention, the isocyanate groups contained in the dielectric resin film may be isocyanate groups derived from the second organic material.

[0077] In the film capacitor of the present invention, the dielectric resin film may also contain additives to provide other functions. For example, a leveling agent may be added to impart smoothness. The additive may also be a material having functional groups that react with hydroxyl groups and / or isocyanate groups and forming part of the crosslinked structure of the cured product. Examples of such materials include resins having at least one functional group selected from the group consisting of epoxy groups, silanol groups, and carboxyl groups.

[0078] In the film capacitor of the present invention, the CR value represented by the product of the electrostatic capacitance value of the film capacitor and the insulation resistance value measured after standing for 1 hour in an atmosphere at a temperature of 125°C and then applying a voltage of 150 V / μm for 1 minute is preferably 250 Ω·F or more, and more preferably 500 Ω·F or more.

[0079] The capacitor under the above conditions has a CR value of 250Ω·F or more, which indicates high high-temperature durability.

[0080] Furthermore, the CR value is preferably 5000 Ω·F or less.

[0081] Manufacturing a film capacitor with a CR value exceeding 5000Ω·F would result in excessively high costs and reduced production efficiency.

[0082] [Manufacturing method of film capacitor]

[0083] Next, an example of a method for manufacturing a thin film capacitor of the present invention will be described.

[0084] The dielectric resin film of the film capacitor of the present invention can be produced by forming a resin solution containing a first organic material having a hydroxyl group and a second organic material having an isocyanate group into a film, and then curing it by heat treatment.

[0085] In this case, the amount of unreacted isocyanate groups can be controlled by adjusting the heat treatment conditions, such as reaction temperature and reaction time, and by adjusting the molar ratio of the hydroxyl groups in the first organic material to the isocyanate groups in the second organic material. As a result, the ratio of the absorption peak intensity of the isocyanate groups to the absorption peak intensity of the carbonyl groups in the resulting dielectric resin film (absorption peak intensity of isocyanate groups / absorption peak intensity of carbonyl groups) can be set to 0.08 or more and 1.15 or less.

[0086] Next, a metal layer is formed on one surface of the produced dielectric resin film to obtain a metallized film. Examples of methods for forming the metal layer include vapor deposition and the like.

[0087] At this time, the metal layer is formed so as to form a stripe-shaped insulating portion on one side edge of one surface of the dielectric resin film.

[0088] Next, prepare two metallized films each having a metal layer formed on one surface of a dielectric resin film. One of the two metallized films is rotated 180 degrees about the stacking direction so that the insulating portions are positioned differently. The films are then stacked with the film offset by a predetermined distance in the width direction, and then wound to form a laminate. If desired, the laminate can be sandwiched perpendicular to the width direction and pressed into an elliptical cylindrical shape.

[0089] Next, external terminal electrodes are formed on the end faces of the laminate to obtain Figure 1 As a method of forming external terminal electrodes on the end faces of the laminate, thermal spraying can be cited.

[0090] [Example]

[0091] Hereinafter, examples of the thin film capacitor of the present invention will be described in more detail. However, the present invention is not limited to these examples.

[0092] (Example 1-1) and (Example 1-2) and (Comparative Example 1-1) and (Comparative Example 1-2)

[0093] To form a dielectric resin film, a high-molecular-weight bisphenol A-type phenoxy resin and a bifunctional isocyanate (MDI) were mixed so that the molar number of hydroxyl groups in the former was approximately equal to the molar number of isocyanate groups in the latter. This mixture was thinly coated onto a substrate film and then dried to produce a resin film. Aluminum was vapor-deposited to form a metal layer, forming a strip-shaped insulating portion on one side edge of the dielectric resin film. The substrate was then peeled off and thermally cured. The thermal curing temperature was adjusted between 100°C and 180°C for 2 to 50 hours. The resulting dielectric resin films, each with a thickness of 3 μm and a metal layer, were produced in Examples 1-1, 1-2, 1-3, and 1-4.

[0094] The ratio of the absorption peak intensity of the isocyanate group to the absorption peak intensity of the carbonyl group (absorption peak intensity of the isocyanate group / absorption peak intensity of the carbonyl group) of each dielectric resin film was measured by the following method. The results are shown in Table 1.

[0095] <Measurement of Absorption Peak Intensity of Functional Group>

[0096] The dielectric resin film was measured by ATR using a Fourier transform infrared spectrophotometer. The wave number domain was set to 4000 cm -1 ~500cm -1 The measurement was performed using the FT / IR-4100ST manufactured by JASCO Corporation. The number of integrations was set to 64 and the resolution was set to 4 cm. -1 .

[0097] Then, the wave number was calculated: 2200cm -1 Above 2350cm -1 The absorption peak intensity of the isocyanate group detected in the following range is relative to the wave number: 1650cm -1 Over 1800cm -1 The ratio of the absorption peak intensity of the carbonyl group detected in the following range (absorption peak intensity of the isocyanate group / absorption peak intensity of the carbonyl group).

[0098] Next, two sheets of each of the metal-layered dielectric resin films described in Manufacturing Examples 1-1, 1-2, 1-3, and 1-4 were prepared. One sheet was rotated 180 degrees about the stacking direction, overlapping the sheets so that the insulating portions were positioned differently. The resulting sheets were then wound to form capacitor elements. Zinc was sprayed onto both ends of the capacitor element to form external terminal electrodes. Leads were connected to the external terminal electrodes, inserted into a PPS (polyphenylene sulfide) case, and filled with epoxy resin to create an outer package.

[0099] As described above, the thin film capacitors of Comparative Example 1-1, Example 1-1, Example 1-2, and Comparative Example 1-2 were manufactured.

[0100] For the thin film capacitor of Comparative Example 1-1, the dielectric resin film of Production Example 1-1 was used.

[0101] For the thin film capacitor of Example 1-1, the dielectric resin film of Production Example 1-2 was used.

[0102] For the thin film capacitor of Example 1-2, the dielectric resin film of Production Example 1-3 was used.

[0103] For the thin film capacitor of Comparative Example 1-2, the dielectric resin film of Production Example 1-4 was used.

[0104] <Measurement of CR value>

[0105] Under the measurement conditions based on the standard specification (JIS C 5101-1 1998), the capacitance of each thin film capacitor was measured using a capacitance measuring instrument (LCR meter).

[0106] In addition, the insulation resistance value was measured after each thin film capacitor was placed in an atmosphere at 125°C for 1 hour and then a voltage of 150 V / μm (150 V per 1 μm of the thickness of the dielectric resin film) was applied for 1 minute. The insulation resistance value was measured using an insulation resistance meter (Model: DSM-8104, Manufacturer: Hioki Electric Co., Ltd.). Then, the CR value represented by the product of the capacitance value and the insulation resistance value was calculated. The results are shown in Table 1.

[0107] In addition, based on the CR value, the thin film capacitors were evaluated according to the following criteria.

[0108] ○: CR value is 100 Ω·F or more

[0109] ×: CR value is less than 100 Ω·F

[0110] <Measurement of ESR increase rate>

[0111] Each thin film capacitor was subjected to a high-temperature load test at 125°C, a voltage of 200 V / μm (200 V per 1 μm of the thickness of the dielectric resin film), for 2000 hours, and the ESR increase rate before and after the test was measured. The evaluation criteria are as follows.

[0112] The results are shown in Table 1. The ESR was measured using an LCR meter (Model: E4980A, Manufacturer: Agilent Technologies).

[0113] In addition, based on the value of the ESR increase rate, the thin-film capacitors were evaluated according to the following criteria.

[0114] ○: The ESR increase rate is 15% or less.

[0115] ×: The ESR increase rate exceeds 15%.

[0116] Based on the above <Measurement of CR value> and <Measurement of ESR increase rate>, the thin-film capacitors were comprehensively evaluated according to the following criteria.

[0117] ◎: The CR value is 100 Ω·F or more and the ESR increase rate is 15% or less.

[0118] ○: The CR value is less than 100 Ω·F and the ESR increase rate is 15% or less.

[0119] △: The CR value is 100 Ω·F or more and the ESR increase rate exceeds 15%.

[0120] ×: The CR value is less than 100 Ω·F and the ESR increase rate exceeds 15%.

[0121] [Table 1]

[0122]

[0123] As shown in Table 1, it was clarified that in the dielectric resin film, if the ratio of the absorption peak intensity of the isocyanate group to the absorption peak intensity of the carbonyl group (absorption peak intensity of isocyanate group / absorption peak intensity of carbonyl group) is 0.08 or more and 1.15 or less, even when a voltage is applied at a high temperature for a long time, oxidation of the vapor-deposited electrode can be suppressed and the ESR is not likely to increase significantly.

[0124] In addition, the CR values of the thin-film capacitors related to Example 1-1 and Example 1-2 having such a structure are 250 Ω·F or more.

[0125] (Example 2-1) and (Example 2-2) and (Comparative Example 2-1) and (Comparative Example 2-2)

[0126] To form a dielectric resin film, a high-molecular-weight bisphenol A-type phenoxy resin and a trifunctional trimethylolpropane (TMP)-adducted TDI were mixed so that the molar number of hydroxyl groups in the former was approximately equal to the molar number of isocyanate groups in the latter. This mixture was thinly coated onto a substrate film and then dried to produce a resin film. Aluminum was vapor-deposited to form a metal layer, forming a strip-shaped insulating portion on one side edge of the dielectric resin film. The substrate was then peeled off and thermally cured. The thermal curing temperature was adjusted between 100°C and 180°C for 2 to 50 hours. The dielectric resin films with a 5μm-thick metal layer were produced, as described in Production Examples 2-1, 2-2, 2-3, and 2-4.

[0127] The ratio of the absorption peak intensity of the isocyanate group to the absorption peak intensity of the carbonyl group (absorption peak intensity of the isocyanate group / absorption peak intensity of the carbonyl group) of each dielectric resin film was measured by the following method. The results are shown in Table 2.

[0128] The absorption peak intensity of each functional group was measured by the same method as in the above-mentioned “<Measurement of the absorption peak intensity of the functional group>”.

[0129] Next, two sheets of each of the metal-layered dielectric resin films described in Manufacturing Examples 2-1, 2-2, 2-3, and 2-4 were prepared. One sheet was rotated 180 degrees about the stacking direction, overlapping the sheets so that the insulating portions were positioned differently. The resulting films were then wound to form capacitor elements. External terminal electrodes were formed by spraying zinc on both ends of the capacitor element. Leads were connected to the external terminal electrodes, inserted into a PPS case, and filled with epoxy resin to create an outer package.

[0130] As described above, thin film capacitors of Comparative Example 2-1, Example 2-1, Example 2-2, and Comparative Example 2-2 were manufactured.

[0131] The film capacitor according to Comparative Example 2-1 used the dielectric resin film according to Production Example 2-1.

[0132] The film capacitor according to Example 2-1 used the dielectric resin film according to Production Example 2-2.

[0133] The film capacitor according to Example 2-2 used the dielectric resin film according to Production Example 2-3.

[0134] The film capacitor according to Comparative Example 2-2 used the dielectric resin film according to Production Example 2-4.

[0135] Regarding each thin film capacitor, the CR value and the ESR increase rate were measured in the same manner as in the above-mentioned "<Measurement of CR value>" and "<Measurement of ESR increase rate>". The results are shown in Table 2.

[0136] [Table 2]

[0137]

[0138] As shown in Table 2, it was clarified that even if the type of polyisocyanate constituting the dielectric resin film was changed, if the ratio of the absorption peak intensity of the isocyanate group to the absorption peak intensity of the carbonyl group (absorption peak intensity of isocyanate group / absorption peak intensity of carbonyl group) was 0.08 or more and 1.15 or less, oxidation of the vapor-deposited electrode could be suppressed and the ESR was not likely to increase even when a voltage was applied at a high temperature for a long time.

[0139] In addition, the CR values of the thin film capacitors according to Examples 2-1 and 2-2 having such a structure were 250 Ω·F or more.

[0140] (Example 3-1) and (Example 3-2) and (Comparative Example 3-1) and (Comparative Example 3-2)

[0141] As the dielectric resin film, a high molecular weight bisphenol A type phenoxy resin and MDI as a bifunctional isocyanate were mixed so that the ratio of the number of moles of the hydroxyl group of the former to the number of moles of the isocyanate group of the latter became hydroxyl / isocyanate group = 60 / 40, 50 / 50, 40 / 60, and 30 / 70. Four coating liquids were prepared, and each coating liquid was thinly coated on a base film and then dried to obtain a resin film. After vapor-depositing aluminum and forming a metal layer so that a strip-shaped insulating portion was formed on one side edge of the dielectric resin film, the base material was peeled off and thermally cured. The thermal curing was set at 150 °C for 5 hours, and dielectric resin films having a metal layer thickness of 3 μm according to Production Example 3-1 (hydroxyl / isocyanate group = 60 / 40), Production Example 3-2 (hydroxyl / isocyanate group = 50 / 50), Production Example 3-3 (hydroxyl / isocyanate group = 40 / 60), and Production Example 3-4 (hydroxyl / isocyanate group = 30 / 70) were produced.

[0142] Then, regarding each dielectric resin film having a metal layer formed thereon, the absorption peak intensities of the isocyanate group and the carbonyl group were measured in the same manner as in the above-mentioned "<Measurement of absorption peak intensity of functional group>", and the ratio of the absorption peak intensity of the isocyanate group to the absorption peak intensity of the carbonyl group (absorption peak intensity of isocyanate group / absorption peak intensity of carbonyl group) was calculated. The results are shown in Table 3.

[0143] Next, two dielectric resin films with a metal layer formed according to Production Example 3-1, Production Example 3-2, Production Example 3-3, and Production Example 3-4 were prepared respectively. One of them was rotated 180 degrees around the lamination direction, and after overlapping with different positions of the insulating portions, they were wound to obtain a capacitor element. Zinc was sprayed on both ends of the capacitor element to form external terminal electrodes. Leads were connected to the external terminal electrodes, inserted into a PPS case, and filled with epoxy resin, thereby performing outer packaging.

[0144] As described above, film capacitors according to Comparative Example 3-1, Example 3-1, Example 3-2, and Comparative Example 3-2 were manufactured.

[0145] For the film capacitor according to Comparative Example 3-1, the dielectric resin film according to Production Example 3-1 was used.

[0146] For the film capacitor according to Example 3-1, the dielectric resin film according to Production Example 3-2 was used.

[0147] For the film capacitor according to Example 3-2, the dielectric resin film according to Production Example 3-3 was used.

[0148] For the film capacitor according to Comparative Example 3-2, the dielectric resin film according to Production Example 3-4 was used.

[0149] Regarding each film capacitor, the CR value and the ESR increase rate were measured in the same manner as in the above "<Measurement of CR value>" and "<Measurement of ESR increase rate>". The results are shown in Table 3.

[0150] [Table 3]

[0151]

[0152] As shown in Table 3, it was clarified that in the dielectric resin film manufactured by mixing the first organic material and the second organic material with an increased ratio of the molar number of the isocyanate group of the latter to the molar number of the hydroxyl group of the former, if the ratio of the absorption peak intensity of the isocyanate group to the absorption peak intensity of the carbonyl group (absorption peak intensity of the isocyanate group / absorption peak intensity of the carbonyl group) is 0.08 or more and 1.15 or less, even when a voltage is applied at a high temperature for a long time, oxidation of the vapor-deposited electrode can be suppressed and the ESR is not likely to increase.

[0153] In addition, the CR values of the film capacitors according to Example 3-1 and Example 3-2 having such a structure are 250 Ω·F or more.

[0154] In this way, the molar ratio of the isocyanate groups of the second organic material to the hydroxyl groups of the first organic material is adjusted in advance to a certain extent to increase the mixing, whereby the content of the isocyanate groups contained in the dielectric resin film can be easily adjusted.

[0155] (Example 4-1) to (Example 4-4)

[0156] As the dielectric resin film, a high molecular weight bisphenol A type phenoxy resin and MDI as a bifunctional isocyanate were mixed so that the molar number of the hydroxyl groups of the former and the molar number of the isocyanate groups of the latter became substantially equal. After thinly coating on a substrate film, it was dried to obtain a resin film. Aluminum was evaporated and a metal layer was formed so that a strip-shaped insulating portion was formed on one side edge of the dielectric resin film, and then the substrate was peeled off and thermally cured. The thermal curing was carried out at 150 °C for 5 hours to produce a dielectric resin film with a metal layer formed and a thickness of 5 μm, in which the ratio of the absorption peak intensity of the isocyanate groups to the absorption peak intensity of the carbonyl groups (absorption peak intensity of the isocyanate groups / absorption peak intensity of the carbonyl groups) was 0.2.

[0157] In addition, the measurement of the absorption peak intensity of the carbonyl groups and the absorption peak intensity of the isocyanate groups was carried out in the same manner as in the above "<Measurement of the absorption peak intensity of functional groups>".

[0158] Next, two dielectric resin films with a metal layer formed were prepared respectively. One was rotated 180 degrees around the lamination direction, and after overlapping with different positions of the insulating portions, they were wound to obtain a capacitor element. Then, the capacitor element was forced to be humidified in an atmosphere of 85 °C and 85%, and four types of capacitor elements were produced: the non-humidified capacitor element and the capacitor element heated and dried at 125 °C for 1 to 12 hours with the water content contained in the dielectric resin film being the values shown in Table 4. In addition, the water content was measured by the hydride reaction method (ISO 15512:2019 Method E).

[0159] Next, zinc was sprayed on both ends of each capacitor element to form external terminal electrodes. Leads were connected to the external terminal electrodes, inserted into a PPS housing, and filled with epoxy resin, thereby performing outer packaging.

[0160] As described above, the film capacitors according to Examples 4-1 to 4-4 were manufactured.

[0161] Regarding the film capacitors according to Examples 4-1 to 4-4, the CR value and the ESR increase rate were measured in the same manner as in the above "<Measurement of the CR value>" and "<Measurement of the ESR increase rate>". The results are shown in Table 4.

[0162] [Table 4]

[0163]

[0164] As shown in Table 4, it is clear that reducing the water content in the dielectric resin film can suppress the ESR increase rate and increase the CR value. In particular, it is clear that the ESR increase rate can be particularly suppressed when the water content is 0.4 wt % or less.

[0165] In addition, it is expected that the moisture content can be further suppressed by storing the film capacitor in a dry atmosphere or heating and drying it before packaging.

[0166] Description of Reference Numerals

[0167] 10 film capacitors;

[0168] 11. 1st metallized film;

[0169] 12. Second metallized film;

[0170] 13. a first dielectric resin film;

[0171] 13a first insulating portion;

[0172] 14. a second dielectric resin film;

[0173] 14a second insulating portion;

[0174] 15 1st metal layer;

[0175] 16 second metal layer;

[0176] 40. A roll of metallized film;

[0177] 41 first external terminal electrode;

[0178] 42: second external terminal electrode.

Claims

1. A film capacitor comprising: a dielectric resin film comprising a thermosetting urethane resin; and a metal layer provided on at least one surface of the dielectric resin film; The dielectric resin film contains at least an isocyanate group and a carbonyl group, Wave number: 2200cm -1 Above 2350cm -1 The absorption peak intensity of the isocyanate group detected in the following range is relative to the wave number: 1650 cm -1 Over 1800cm -1 The ratio of the absorption peak intensity of the carbonyl group detected within the following range, ie, the absorption peak intensity of the isocyanate group / the absorption peak intensity of the carbonyl group, is 0.08 or more and 1.15 or less.

2. The thin film capacitor according to claim 1, wherein The dielectric resin film contains water at a content of 0.4 wt % or less.

3. The film capacitor according to claim 2, wherein The dielectric resin film contains water in an amount of 0.01 wt % or more.

4. The thin film capacitor according to any one of claims 1 to 3, wherein The dielectric resin film includes a cross-linked product of a phenoxy resin and diphenylmethane diisocyanate and / or toluene diisocyanate.

5. The thin film capacitor according to any one of claims 1 to 4, wherein The film capacitor has a CR value of 250 Ω·F or more, which is a product of the capacitance value and the insulation resistance value measured after standing in an atmosphere at a temperature of 125° C. for 1 hour and then applying a voltage of 150 V / μm for 1 minute. The thin film capacitor according to claim 5 , wherein: The CR value is 5000Ω·F or less.

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