JP2015066910A - Film for film capacitor, and method for producing the film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film for film capacitors, which has both of slidability useful to improve productivity and voltage resistance, and to provide a method for producing the film for film capacitors.SOLUTION: The film for film capacitors includes, at the least, a first film layer and a second film layer which layers are formed from a thermoplastic resin composition by a co-extrusion method. The method for producing the film for film capacitors comprises the steps of: heaping the thermoplastic resin compositions, which are supplied respectively from a plurality of extruders 1A, 1B, 1C, in multiple layers and merging the heaped compositions by a feed block 4; extruding the merged composition from a T-die 7 by co-extrusion method to obtain a molten multilayer film 8; tightly sticking and cooling the molten multilayer film between a pressing roll 9 and a cooling roll 10a; measuring the thickness of the cooled film by a thickness measuring instrument 14; controlling the circumferential speed of the cooling roll 10a according to the measured thickness so that the film has the predetermined thickness; and winding the film 8 around a take-up tube 16 by using a take-up machine 15.

Description

  The present invention relates to a film for a film capacitor and a method for producing the same.

  Currently, a dielectric layer is a film obtained from one of four types of resins, polypropylene resin (PP resin), polyethylene terephthalate resin (PET resin), polyphenylene sulfide resin (PPS resin), and polyethylene naphthalate resin (PEN resin). A film for a film capacitor has been put into practical use by forming a metal vapor deposition layer as an electrode on the surface of the dielectric layer.

  By the way, with the spread of hybrid vehicles, capacitors used for inverters are required to have a heat resistance of 150 ° C. or higher. And since the use temperature of PP resin is 105 degrees C or less and the use temperature of PET resin is 125 degrees C or less, the film for film capacitors made from PP resin and PET resin has low heat resistance. For this reason, in order to apply a film capacitor film made of PP resin or PET resin to a hybrid vehicle capacitor, (1) a method of installing a large cooling device ignoring the demand for weight reduction, (2) space A method of ignoring efficiency and installing a capacitor on the driver's seat or the like far away from the engine room of the heat source has to be adopted, and the weight reduction and cost are problems to be solved.

  On the other hand, a film capacitor film made of PPS resin has good heat resistance at a use temperature of 160 ° C. or lower, but has a low dielectric breakdown strength and inferior voltage resistance. Moreover, the film for film capacitors made of PEN resin can provide good heat resistance at a use temperature of 160 ° C. or less, but has a large dielectric loss and a large temperature dependence of dielectric loss tangent, so that the use range is limited.

  On the other hand, a film made of polyetherimide resin (PEI resin) has attracted attention as a film for a film capacitor (see, for example, Patent Documents 1 and 2). Films for film capacitors made of polyetherimide resin have a glass transition point Tg of 200 ° C. or higher, excellent heat resistance, high dielectric breakdown strength, excellent voltage resistance, and frequency dependence and temperature dependence of dielectric loss tangent. Since it is small, it is suitable as a film for a film capacitor.

JP 2007-300126 A JP 2011-108714 A JP 2009-132874 A JP 2013-125936 A

  However, a film made of a thermoplastic resin used as a film for a film capacitor is inferior in slidability. For example, the film winding or slitting work during film production may be hindered, or the film may be damaged. May occur, or may be wound around a guide roll or the like during film production. In addition, when the capacitor is assembled, the film may be blocked, and when the wound film is unwound, the film may be broken to hinder assembly. For this reason, in order to use a film made of a thermoplastic resin as a film for a film capacitor, it is necessary to improve the slidability.

  As a method for improving slidability, a method using a thermoplastic resin to which a slidability modifier is added is generally used. However, for example, the slidability of the film is improved by dispersing the slidability modifier (filler) in the thermoplastic crystalline resin as disclosed in Patent Document 3 to roughen the film surface. In the method of increasing, there is a problem that the filler portion becomes a defect and the voltage resistance of the film is lowered.

  Then, this invention is made | formed in view of the said problem, Comprising: It aims at providing the film for film capacitors which has the slidability and voltage resistance which improve productivity, and its manufacturing method.

In order to achieve such an object, the present invention is grasped by the following configuration.
(1) The film for a film capacitor of the present invention is a film for a film capacitor, and includes at least a first film layer and a second film layer, and the first film layer and the second film layer. Is characterized in that it is formed from a thermoplastic resin composition by coextrusion.

  (2) The film for a film capacitor of the present invention is characterized in that, in the configuration of (1), the film has a thickness of 2 μm or more and 10 μm or less.

  (3) The film for a film capacitor of the present invention is characterized in that, in the configuration of (1) or (2), the film includes a third film layer.

  (4) The film for a film capacitor of the present invention includes at least one slidable modified film in which the film layer contains a slidable modifier in any one of the constitutions (1) to (3). It is characterized by

  (5) The film for a film capacitor of the present invention is characterized in that, in the configuration of (4), the slidability modifier is polytetrafluoroethylene.

  (6) The film for a film capacitor of the present invention is characterized in that, in any one of the constitutions (1) to (5), the thermoplastic resin composition contains a crystalline resin composition.

  (7) The film for a film capacitor of the present invention is characterized in that, in any one of the constitutions (1) to (6), the thermoplastic resin composition includes an amorphous resin composition.

  (8) The film for a film capacitor of the present invention is characterized in that, in the configuration of (7), the amorphous resin composition is a polyetherimide resin composition.

  (9) In the method for producing a film for a film capacitor having the constitutions (1) to (8) of the present invention, the thermoplastic resin compositions supplied from a plurality of extruders are laminated in multiple layers by a feed block and merged. A step of extruding from a T-die connected to the feed block by a co-extrusion method to obtain a molten multilayer film, a step of bringing the molten multilayer film into close contact between a pressure-bonding roll and a cooling roll, and cooling; A step of measuring the thickness of the molten multilayer film with a thickness measuring device disposed between the pair and the guide roll, and based on the measured thickness, the molten multilayer film has a predetermined thickness It includes a step of controlling the peripheral speed of the cooling roll, and a step of winding the molten multilayer film whose thickness is adjusted around a winding tube with a winder.

  (10) The method for producing a film for a film capacitor of the present invention is characterized in that, in the configuration of (9), the predetermined thickness is 2 μm or more and 10 μm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the film for film capacitors which has the slidability and voltage resistance which improve productivity, and its manufacturing method can be provided.

It is a schematic diagram which shows the laminated structure of the thermoplastic resin composition which concerns on embodiment of this invention. It is a schematic diagram which shows the manufacturing apparatus of the three-layer laminated film of the thermoplastic resin composition which concerns on embodiment of this invention. It is a schematic diagram which shows the feed block in the manufacturing apparatus of the 3 layer laminated film of FIG.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail.

  The film capacitor film 8 according to the present invention includes at least a first film layer and a second film layer, and the first film layer and the second film layer are made of a thermoplastic resin composition. It is formed by extrusion.

  The film capacitor film 8 has a thickness of 2 to 10 μm. When the thickness is less than 2 μm, the tensile strength of the film is lowered, and there is a possibility that a problem may occur in the step of joining a plurality of resin layers and laminating a plurality of layers. If it exceeds 10 μm, the dielectric breakdown strength per thickness of the film is lowered, so that the effect of improving the voltage resistance is reduced.

  The thermoplastic resin composition includes polyethylene resin (PE resin), polypropylene resin (PP resin), polyamide resin (PA resin), polyacetal resin (POM resin), polyethylene terephthalate resin (PET resin), ultra high molecular weight polyethylene resin ( UHPE resin), polybutylene terephthalate resin (PBT resin), polymethylpentene resin (TPX resin), polyphenylene sulfide resin (PPS resin), polyether ether ketone resin (PEEK resin), liquid crystal polymer resin (LCP resin), polytetra One or more crystalline thermoplastic resin compositions selected from the group including fluoroethylene resin (PTFE resin) and syndiotactic polystyrene resin can be used.

  The thermoplastic resin composition includes polystyrene resin (PS resin), acrylonitrile / styrene resin (AS resin), acrylonitrile / butadiene / styrene resin (ABS resin), methacrylic resin (PMMA resin), and vinyl chloride resin (PVC resin). Polycarbonate resin (PC resin), cycloolefin polymer resin (COP resin), polyetherimide resin (PEI resin), polyallelate resin (PAR resin), polysulfone resin (PSF resin), polyethersulfone resin (PES resin) ), One or more amorphous thermoplastic resin compositions selected from the group comprising polyamideimide resin (PAI resin) and the like.

  Films for film capacitors made of polyetherimide resin (PEI resin) have a glass transition point Tg of 200 ° C. or higher, excellent heat resistance, high dielectric breakdown strength, excellent voltage resistance, frequency dependence of dielectric loss tangent and temperature Since the dependency is small, it is suitable as a film for a film capacitor. One PEI resin may be used alone, or two or more PEI resins may be alloyed or blended.

  Furthermore, as a PEI resin composition, a thermoplastic polyimide resin such as a polyimide resin (PI resin) or a polyamideimide resin (PAI resin), or a polyether ether ketone resin (PEEK resin), as long as the characteristics of the present invention are not impaired. Or an aromatic polyether sulfone such as a polyarylene ketone resin such as a polyether ketone resin (PK resin), a polysulfone resin (PSU resin), a polyether sulfone resin (PES resin) or a polyphenylene sulfone resin (PPSU resin). Known thermoplastic resins such as polyarylene sulfide resins (PPS resins), polyarylene sulfide resins such as polyphenylene sulfide sulfone resins, polyphenylene sulfide ketone resins, and liquid crystal polymer resins (LCP resins) can be added. . As the liquid crystal polymer, any of liquid crystal polymers of type I, type II or type III can be used.

  Specific examples of PEI resin include Ultem 1010 (trade name, manufactured by SABIC Innovative Plastics Japan) having a Tg of 217 ° C., Ultem 9011 (trade name, manufactured by SABIC Innovative Plastics Japan, Inc.) having a Tg of 217 ° C., and Tg Examples include 235 ° C Ultem CRS5001 (trade name, manufactured by SABIC Innovative Plastics Japan), Ultem XH6050 (trade name, manufactured by SABIC Innovative Plastics Japan) having a Tg of 247 ° C.

  Specific examples of the slidability modifier include silicone oils such as polydimethylsiloxane, fillers such as carbon fibers and silica, and fluororesins. Among these, a fluororesin is preferable because it can provide necessary slidability without affecting the voltage resistance and is thermally stable even at a molding temperature exceeding 300 ° C.

  The fluororesin is polytetrafluoroethylene resin (PTFE resin), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA resin), tetrafluoroethylene-hexafluoropropyl copolymer resin (FEP resin), tetrafluoroethylene. -One or more resins selected from the group including ethylene copolymer resin (ETFE resin), polyvinylidene fluoride resin (PVDF resin), and polychlorotrifluoroethylene resin (PCTFE resin) can be used. . Among these fluororesins, PFA resin and FEP resin are preferable from the viewpoints of excellent heat resistance at a continuous use temperature of 200 ° C. or higher and cost and ease of handling. The PFA resin and the FEP resin may be used alone or in combination.

  For example, in the case of a fluororesin, the amount of the slidability modifier added is 1.0 to 30.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin, preferably 1.0 parts by mass. It is -20.0 mass parts, More preferably, it is the range of 1.0 mass part-10.0 mass parts. When the addition amount of the fluororesin is less than 1.0 part by mass, the slidability cannot be sufficiently imparted to the film for a film capacitor. Even if added over 30.0 parts by mass, the effect of improving the slidability of the film for film capacitors does not change, and an addition amount of 30.0 parts by mass or less is sufficient. Furthermore, when it is added in excess of 30.0 parts by mass, the ratio of the fluororesin is increased, so that the dielectric breakdown voltage is lowered and the suitability as a film for a film capacitor is lowered. In addition, the tensile strength is reduced and the film is easily broken during the production of the film for a film capacitor, making it difficult to produce a thin film for a film capacitor, generating holes in the film for a film capacitor, or depositing a metal. May adversely affect performance.

  The configuration of each layer in the film for film capacitor 8 is not particularly limited. For example, the surface layer 1 as shown in FIG. 1A is a sliding layer A formed from a slidable modified film, and the central layer is An insulating layer B formed from a thermoplastic resin film, a surface layer 1 as shown in FIG. 1B and a central layer as a sliding layer A, a surface layer 1 as shown in FIG. The surface layer 2 is the sliding layer A and the center layer is the insulating layer B, the surface layer 1 as shown in FIG. 1 (d) is the sliding layer A, the center layer and the surface layer 2 are the insulating layer B, FIG. The surface layer 1, the center layer, and the surface layer 2 as shown in FIG. By making the film into two layers, the defective portions occurring in each layer are compensated for each other, the minimum value of the dielectric breakdown voltage (V / μm) is improved, and as a result, the withstand voltage is improved. Further, by increasing the number of laminated films to 3 layers and 4 layers, the defect portion is further compensated for and the voltage resistance is further improved.

  Decreasing withstand voltage due to the addition of the slidability modifier is the film capacitor film 8 having two layers (sliding layer / insulating layer) or three layers (sliding layer / insulating layer / sliding layer). By adopting a structure, it is possible to ensure the slidability and voltage resistance that are indispensable for the processing of capacitors. When the number of layers is four or more, as shown in (sliding layer / insulating layer / insulating layer / sliding layer), surface layer 1 and surface layer 2 are sliding layers, and the central layer is a plurality of insulating layers. In particular, the voltage resistance is improved.

  The composition ratio of the thickness of each layer in the film for film capacitor 8 is used without particular limitation in the case of lamination of the same type of film, that is, between thermoplastic resin films or slidable modified thermoplastic resin films. be able to. When laminating a combination of different types of films, the slidable modified thermoplastic resin film is preferably thicker than the thermoplastic resin film in order to ensure voltage resistance. Further, in the case of a three-layer laminated film, the slidable modified thermoplastic resin film of the central layer is preferably thicker than the total of the thermoplastic resin films of the surface layer, while suppressing the minimum value of voltage resistance. In order to ensure the slidability, the ratio of the thicknesses of the respective layers is determined as follows: surface layer 1: center layer: surface layer 2 = (0.1 or more and 0.5 or less): (4.0 or more and 4.8 or less): (0. 1 to 0.5).

Next, the melt coextrusion molding method using 7 having the feed block 4 which is a method for producing the film for film capacitor 8 in the present invention will be described.

  Conventionally, as a method for producing a film for a film capacitor, there is a melt extrusion molding method using a T die (see Patent Document 4). For example, in the case of a two-layer laminated film, a molten thermoplastic resin molding material is extruded from the lip portion of a T die, and a film formed into a predetermined thickness and a predetermined width is formed, cooled, and solidified by a feeder. Along with the finished thermoplastic resin film, it is drawn and laminated on the outer peripheral surface of the standard surface cooling roll of the take-up machine, adjusted to a predetermined thickness by pressing with a crimping roll, cooled, solidified, and conveyed by a pair of conveying rolls It is the method of winding and manufacturing to a winding machine.

  In the melt extrusion method using the T die, the distance (air gap) from the lip portion of the T die to the contact of the molten film with the cooling roll is long, and the molten film is solidified due to a decrease in temperature. It has been difficult to produce a film having a thickness of 10 μm or less because the adhesiveness between the films is lowered, the accuracy of the film thickness of each layer is lowered. Therefore, it manufactures by the melt coextrusion method using the T die which has a feed block which is the manufacturing method of the film for film capacitors in this invention from the point which can form a film thinly, and the point of mass-productivity. The molding material containing the thermoplastic resin composition for each layer is melt-kneaded with a twin-screw extrusion kneader, and the molten resin is made into a laminar flow state by a feed block disposed at the tip of the extruder, and the tip of the T die The molten resin is melt co-extruded from the lip of the laminate and laminated, and this molten multilayer film is cooled by closely contacting between the crimping roll and the cooling roll in the take-up machine, and then taken up sequentially on the take-up tube by the winder Provided as a film for a film capacitor.

  Based on FIG.2 and FIG.3, the manufacturing method of the 3 layer lamination | stacking polyetherimide resin (PEI resin) film which concerns on Example 1 of embodiment of this invention is demonstrated in detail.

  As shown in FIG. 2, a three-layer T die extrusion apparatus, which is a three-layer laminated PEI resin film manufacturing apparatus according to Example 1, includes a material charging hopper 2, an extruder 1A, an extruder 1B, an extrusion 1C, feed block 4, T dice 7, press roll 9, standard surface cooling roll 10a, rough surface cooling roll 10b, take-up machine 11, and winder 15 are provided.

  Extruder 1A, Extruder 1B, and Extruder 1C are each fed by an extrusion screw (not shown) and fed in the feed block 4 direction while mixing and stirring the PEI resin composition molding material charged from the material charging hopper 2. At the same time, the molding material is heated and melted by electric heating means incorporated in a cylinder (not shown). The molding material containing the PEI resin composition that is melted and conveyed in this way is fed to the feed block 4 through the connecting pipe 3.

  In the feed block 4, as shown in FIG. 3, the molding materials respectively supplied from the extruders 1 </ b> A to 1 </ b> C are joined in multiple layers at the junction 51 through the selector plug 5. The merged molding material is supplied to a T die 7 composed of a single manifold through a die plate 6.

  In the T die 7, the melt molding material is extruded at a predetermined pressure, and a film 8 having a predetermined thickness and a predetermined width is formed from the lip portion 7 a of the T die 7. The film 8 thus molded is taken on the outer peripheral surface of the standard surface cooling roll 10a of the take-up machine 11 and adjusted to a predetermined thickness by pressing with the pressure-bonding roll 9, and is cooled and solidified to obtain the thickness of the film. Is measured by the thickness measuring instrument 14. Then, the film 8 is conveyed to the winder 15 by the conveying roll pairs 12 and 13.

  A thickness measuring device 14 is disposed between the conveying roll pairs 12 and 13 and the guide roll 15a. The thickness measuring device 14 measures the thickness to a desired thickness, for example, 2 μm to 10 μm. Based on the thickness, the peripheral speeds of the cooling rolls 10a and 10b are adjusted and controlled. And it can wind up and wind up to the winding tube 16 via the guide rolls 15a, 15b, 15c in the winder 15.

  The coextrusion apparatus of this type is not limited to the distribution plug system in which the selector plug 5 is provided in the feed block 4 described above, and a distribution plate system in which a selector plate is provided in the feed block 4 can also be adopted.

  Hereinafter, Examples 1 to 8 and Comparative Examples 1 and 2 of the film capacitor film of the present invention will be described with reference to Table 1 and FIG.

(Adjustment of sample film)
Films of Comparative Examples 1 and 2 and Examples 1 to 8 were produced using a three-layer T die extrusion apparatus shown in FIG. In addition, as for the formation layer of each resin, the resin put into the extruder 1B is a center layer, the resin put into the extruder 1A is the surface layer 1 (winding inner surface side), and the resin put into the extruder 1C is the surface layer 2 (winding outer surface side) ) The thickness of each layer was adjusted by the extrusion amount of each extruder.

(Comparative Example 1)
A polyetherimide resin (PEI resin) was used as the thermoplastic resin composition, and the PEI resin was introduced into the extruder 1B using a three-layer T-die extrusion apparatus shown in FIG. 2 to produce a single-layer film having a thickness of 5 μm. . As the PEI resin, Ultem 9011 (trade name, manufactured by SABIC Innovative Plastics Japan) was used.

Example 1
Polyetherimide resin (PEI resin) is used as the thermoplastic resin composition, and the PEI resin is introduced into each of the extruders 1A, 1B, and 1C using the three-layer T-die extruder shown in FIG. The material extrusion amount of each extruder was adjusted so that surface layer 1: center layer: surface layer 2 = 1: 3: 1, and a three-layer laminated film having a thickness of 5 μm was produced. As the PEI resin, Ultem 9011 (trade name, manufactured by SABIC Innovative Plastics Japan) was used.

(Examples 2-3)
Using the three-layer T-die extrusion apparatus shown in FIG. 2, the slidability modified PEI resin is introduced into the extruder 1A, and the PEI resin is introduced into the extruders 1B and 1C. Was made. As the PEI resin, Ultem 9011 (trade name, manufactured by SABIC Innovative Plastics Japan) was used, and as the slidable modified PEI resin, a blend of PFA resin with Ultem 9011 was used. The thickness ratio of each layer was such that each layer was extruded so that Example 2 had surface layer 1: center layer: surface layer 2 = 2: 2: 1 and Example 3 had surface layer 1: center layer: surface layer 2 = 1: 3: 1. The material extrusion rate of the machine was adjusted.

(Examples 4 to 6)
Using the three-layer T-die extrusion apparatus shown in FIG. 2, the sliding property modified PEI resin is introduced into the extruders 1B and 1C, and the PEI resin is introduced into the extruder 1A. Was made. As the PEI resin, Ultem 9011 (trade name, manufactured by SABIC Innovative Plastics Japan) was used, and as the slidable modified PEI resin, a blend of PFA resin with Ultem 9011 was used. The ratio of the thickness of each layer is as follows: Example 4 is surface layer 1: center layer: surface layer 2 = 1: 3: 1, Example 5 is surface layer 1: center layer: surface layer 2 = 0.5: 4: 0.5 The material extrusion rate of each extruder was adjusted so that Example 6 was surface layer 1: center layer: surface layer 2 = 0.25: 4.5: 0.25.

(Comparative Example 2)
Using the three-layer T-die extrusion apparatus shown in FIG. 2, the slidability modified PEI resin was introduced into the extruder 1B to produce a single layer film having a thickness of 5 μm. As the slidability modified PEI resin, Ultem 9011 (trade name, manufactured by SABIC Innovative Plastics Japan) and PFA resin were used.

(Example 7)
Using the three-layer T-die extrusion apparatus shown in FIG. 2, the slidability modified PEI resin was introduced into the extruders 1B and 1C to produce a two-layer laminated film having a thickness of 5 μm. As the slidability modified PEI resin, Ultem 9011 (trade name, manufactured by SABIC Innovative Plastics Japan) and PFA resin were used. The material extrusion rate of each extruder was adjusted so that the ratio of the thickness of each layer was: surface layer 1: center layer (+ surface layer 2) = 1: 4.

(Example 8)
Using the three-layer T-die extruder shown in FIG. 2, the slidability-modified PEI resin was introduced into the extruders 1A, 1B, and 1C to produce a three-layer laminated film having a thickness of 5 μm. As the slidability modified PEI resin, Ultem 9011 (trade name, manufactured by SABIC Innovative Plastics Japan) and PFA resin were used. The material extrusion rate of each extruder was adjusted so that the ratio of the thickness of each layer would be surface layer 1: center layer: surface layer 2 = 1: 3: 1.

(Measurement and evaluation)
(Film thickness)
The thickness of the film for a film capacitor is determined by the average thickness of 95 points at 19 points in the film width direction and 5 points in the film flow direction using a contact-type thickness meter (trade name: Electronic Micrometer Myrotron 1240 manufactured by Mahr). Asked.

(Surface roughness)
The arithmetic average roughness Ra and the maximum height Rz of the film for a film capacitor were measured according to JISB0601-2001. Ten-point average roughness Rz94 was measured according to JISB0601-1994.

(Static friction coefficient and dynamic friction coefficient)
The static friction coefficient and the dynamic friction coefficient of the film for a film capacitor were measured according to JIS K 7125-1999. Specifically, a universal material testing machine (A & D, Tensilon) is used and the test speed is 100 mm / min and the vertical load is 1.96 N flat indenter specification in an environment of 23 ° C. and 50% RH. The friction resistance between the film front and back was measured.

(Withstand voltage)
The withstand voltage (dielectric breakdown voltage) of the film for a film capacitor is based on JIS C2110-1994, and is a minimum value (Min), a maximum value (Max), an average value (Ave), Standard deviation (σ) was measured. This measurement was performed in an environment of 23 ° C. The shape of the electrode was a columnar shape (upper shape diameter: 25 mm, height: 25 mm, lower shape diameter: 25 mm, height: 15 mm).

  Measurement of the layer thickness (μm), voltage resistance (V / μm), static friction coefficient, dynamic friction coefficient, and inner surface roughness (μm) on the cooling roll side of the films prepared in Comparative Examples 1-2 and Examples 1-8 The results are shown in Table 1.

  In the three-layer laminated film (insulating layer / insulating layer / insulating layer) by coextrusion in Example 1, the minimum value of withstand voltage (dielectric breakdown voltage) per 1 μm thickness is the single layer film (insulating) in Comparative Example 1. 149 V / μm to 191 V / μm, and the average value of the single layer film of Comparative Example 1 is significantly increased from 261 V / μm to 296 V / μm.

  Further, in Example 7 (sliding layer / sliding layer), by adding a slidability modifier to the PEI resin, the dynamic friction coefficient, which is one of the slidability indicators, is shown in Comparative Example 1 ( Insulating layer) is reduced from 0.71 to 0.40. On the other hand, the minimum value of withstand voltage (dielectric breakdown voltage) per 1 μm thickness is significantly increased from 113 V / μm in Comparative Example 2 (sliding layer) to 167 V / μm.

  From the results of Comparative Example 2 (sliding layer), Example 7 (sliding layer / sliding layer) and Example 8 (sliding layer / sliding layer / sliding layer), the sliding property modifier added PEI In the resin film, as the number of laminated layers increases from a single layer to 2 layers and 3 layers, the withstand voltage per 1 μm thickness increases both in the average value and the minimum value while maintaining the slidability. Recognize.

  From the results of Example 1 (withstand voltage layer / insulating layer / withstand voltage layer), Example 3 (sliding layer / insulating layer / withstand voltage layer) and Example 4 (sliding layer / insulating layer / sliding layer) By providing a sliding layer (sliding property modifier added PEI resin film layer) on the surface layer, the dynamic friction coefficient and the static friction coefficient were reduced, and the sliding property was improved.

  Thus, by applying a film obtained by laminating at least two resin film layers formed by coextrusion from a thermoplastic resin composition, slidability is maintained even for thermoplastic resin films having the same thickness. As a result, the effect of mutual compensation of the defective portions occurs, and the improvement of the withstand voltage is achieved. Similarly, with respect to a decrease in voltage resistance due to the addition of a slidability modifier, an increase in voltage resistance is achieved by multilayering by coextrusion.

  As mentioned above, although this invention was demonstrated using embodiment, it cannot be overemphasized that the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. Further, it is apparent from the description of the scope of claims that embodiments with such changes or improvements can also be included in the technical scope of the present invention.

A Sliding layer B Insulating layer 1A Extruder A
1B Extruder B
1C Extruder C
2 Material input hopper 3 Connecting pipe 4 Feed block 5 Selector plug 51 Junction part 6 Die plate 7 T dice 7a Lip part 8 Film capacitor film 9 Crimp roll 10a Standard surface cooling roll 10b Rough surface cooling roll 11 Take-up machine 12, 13 Conveyance Roll pair 14 Thickness measuring device 15 Winding machines 15a, 15b, 15c Guide roll 16 Winding pipe

Claims (10)

A film for a film capacitor,
Comprising at least a first film layer and a second film layer;
The film for a film capacitor, wherein the first film layer and the second film layer are formed from a thermoplastic resin composition by coextrusion.   The film for a film capacitor according to claim 1, wherein the film has a thickness of 2 μm or more and 10 μm or less.   The film for a film capacitor according to claim 1, wherein the film includes a third film layer.   The film for a film capacitor according to any one of claims 1 to 3, wherein the film includes at least one layer of a slidability modifying film containing a slidability modifying agent.   5. The film capacitor film according to claim 4, wherein the slidability modifier is polytetrafluoroethylene.   The film for a film capacitor according to any one of claims 1 to 5, wherein the thermoplastic resin composition contains a crystalline resin composition.   The film for a film capacitor according to any one of claims 1 to 6, wherein the thermoplastic resin composition includes an amorphous resin composition.   The film for a film capacitor according to claim 7, wherein the amorphous resin composition is a polyetherimide resin composition. It is a manufacturing method of the film for film capacitors of any one of Claims 1 thru | or 8, Comprising:
A step of laminating and joining the thermoplastic resin composition supplied from a plurality of extruders in multiple layers by a feed block;
Extruding by a coextrusion method from a T die connected to the feed block to obtain a molten multilayer film;
A step of closely cooling the molten multilayer film between a pressure roll and a cooling roll;
A step of measuring the thickness of the molten multilayer film with a thickness measuring device disposed between a pair of conveying rolls and a guide roll;
Controlling the peripheral speed of the cooling roll based on the measured thickness so that the molten multilayer film has a predetermined thickness;
A method for producing a film for a film capacitor, the method comprising: winding the molten multilayer film, the thickness of which is adjusted, on a winding tube with a winder.   The method for producing a film for a film capacitor according to claim 9, wherein the predetermined thickness is 2 μm or more and 10 μm or less.

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