Wound bodies for electrical / electronic equipment or parts

Abstract

The subject of the present invention is to suppress the film from undulating in a winding body of a conductive film. The winding body includes a cylindrical winding core, a first film and a second film. The first film is wound around the winding core in a circumferential direction and has conductivity. The second film is wound around the winding core in a circumferential direction and has a Young's modulus higher than the first film. The first film and the second film are not bonded. The first film and the second film are wound around the winding core in an overlapping state.

Description

Technical Field

[0001] The invention relates to a winding body. Background Art

[0002] Japanese Patent Application Laid-Open No. 2013-116442 (Patent Document 1) discloses a wound body of a laminated porous film used as a separator for a lithium ion battery, for example.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-116442 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] Compared with the laminated porous film disclosed in the above-mentioned patent document 1, the thickness fluctuation of the conductive film is sometimes greater. When the thickness fluctuation is large, when the film is wound on the winding core, a pressure difference is generated in the plane due to the thickness fluctuation. It is difficult to produce shrinkage of the film in the area with high pressure, and it is easy to produce shrinkage of the film in the area with low pressure. Due to the difference in the degree of shrinkage in each area, the film may fluctuate.

[0008] Figure 5 FIG. 2 is a photograph showing an example of undulations generated in a film. Figure 5 As shown, for example, when the film is pulled out from the wound body and laid flat on a platform, the film undulation is easily observed by visual observation. The film undulation is considered to be caused by the film locally expanding and contracting in the film plane direction during the process of forming the wound body.

[0009] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to suppress the occurrence of undulations in a wound body of a conductive film.

[0010] Technical solutions for solving technical problems

[0011] The winding body according to the present invention comprises a cylindrical winding core, a first film and a second film. The first film is wound around the winding core in a circumferential direction and has conductivity. The second film is wound around the winding core in a circumferential direction and has a Young's modulus higher than the first film. The first film and the second film are not bonded. The first film and the second film are wound around the winding core in an overlapping state.

[0012] In the winding body, the first film having conductivity and the second film having a Young's modulus higher than the first film are wound on the winding core in an overlapping state. Therefore, according to the winding body, the first film is pressed by the second film having a Young's modulus higher than the first film, so that the first film can be suppressed from undulating.

[0013] In the wound body described above, the first film may contain a filler having electrical conductivity.

[0014] If the conductive filler is contained, the thickness fluctuation of the first film becomes large. As described above, when the thickness fluctuation is large, undulations occur in the first film. In the wound body according to the present invention, as described above, the conductive first film and the second film having a higher Young's modulus than the first film are wound on the wound body in an overlapping state. Therefore, with this wound body, even if the first film contains a conductive filler, the first film can be suppressed from undulating because the second film having a higher Young's modulus than the first film presses the first film.

[0015] In the above wound body, the glass transition point of the second film may be higher than the glass transition point of the first film.

[0016] According to this wound body, since the state of the second film is less likely to change than that of the first film, the first film can be reliably pressed by the second film, and as a result, the first film can be suppressed from undulating.

[0017] Effects of the Invention

[0018] According to the present invention, it is possible to suppress the occurrence of undulation in a wound body of a conductive film. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a perspective view schematically showing a winding body.

[0020] Figure 2 It is a figure which shows schematically the front side of a winding body.

[0021] Figure 3 Yes means Figure 2 FIG. 3 is a diagram of a III-III cross section and an enlarged portion of the cross section.

[0022] Figure 4 It is a diagram showing a schematic configuration of a winding body manufacturing apparatus.

[0023] Figure 5 This is a photograph showing an example of undulation generated in a film.

[0024] Explanation of symbols

[0025] 10: winding body; 20: manufacturing device; 100: winding core; 110: conductive film; 120: support film; 210: T-die; 220, 230: casting roll; 240: conveying roll; 250: winding roll. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same or corresponding parts in the drawings are marked with the same reference numerals and their description will not be repeated.

[0027] [1. Structure of winding body]

[0028] Figure 1 It is a perspective view schematically showing the wound body 10 according to the present embodiment. Figure 2 This is a diagram schematically showing the front side of the wound body 10 according to the present embodiment. Figure 3 Yes means Figure 2 FIG. 3 is a diagram of a III-III section and an enlarged portion of the section.

[0029] like Figure 1 , Figure 2 and Figure 3 As shown in FIG. 1 , in the cylindrical winding body 10, the conductive film 110 and the support film 120 are wound around the cylindrical winding core 100. More specifically, the conductive film 110 and the support film 120 are wound around the winding core 100 in an overlapping state along the circumferential direction. That is, in the radial cross section of the winding body 10, the conductive film 110 and the support film 120 are alternately present in the radial direction (refer to FIG. 1 ). Figure 3 The conductive film 110 has conductivity, and the support film 120 has a Young's modulus higher than that of the conductive film 110.

[0030] The conductive film 110 contains, for example, a filler having conductivity (hereinafter, also referred to as a "conductive filler"). When the conductive filler is contained, the thickness fluctuation of the film becomes larger than when the conductive filler is not contained. In the case of large thickness fluctuation, if the conductive film 110 is simply wound on the winding core 100, a pressure difference is generated within the surface of the conductive film 110 due to the thickness fluctuation. The conductive film 110 is difficult to shrink in a region with high pressure, and is easy to shrink in a region with low pressure. Due to the difference in the degree of shrinkage in each region, the conductive film 110 may fluctuate.

[0031] In the winding body 10, the conductive film 110 and the support film 120 having a higher Young's modulus (higher elastic modulus) than the conductive film 110 are wound in an overlapping state on the winding core 100. Therefore, according to the winding body 10, the conductive film 110 is pressed by the support film 120 having a higher Young's modulus than the conductive film 110, so that the generation of undulations in the conductive film 110 can be suppressed.

[0032] Next, the conductive film 110 and the support film 120 will be described in detail, and then the manufacturing process of the wound body 10 will be described.

[0033] [2. Material of the conductive film]

[0034] The conductive film 110 is, for example, a nonporous film containing a thermoplastic resin material and a conductive material (conductive filler). The conductive film 110 is used, for example, as a charged film or a charge-removing film for a copier or printer, or various functional films of other electrical / electronic equipment or parts. In addition, the conductive film 110 may or may not be subjected to surface processing such as corona discharge, plasma, coating or sputtering. As the thermoplastic resin material, any material can be used as long as it is a thermoplastic resin material.

[0035] As thermoplastic resin material, for example, polyolefin resin (homopolymer and copolymer) can be used. In addition, as thermoplastic resin, for example, fluorine-based copolymers such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE) or tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (EPE), polyester-based copolymers such as polyether esters or polyamide-based copolymers such as polyether amide or polyether ester amide etc. can be used. In addition, as thermoplastic resin, for example, polymer alloys, polymer dopants of the above-mentioned substances can also be used.

[0036] As the conductive material, a known material having conductivity can be used. As the conductive material, for example, carbon materials such as graphite or carbon black, ion conductive materials, metal oxides such as zinc oxide or tin oxide, metals such as copper or silver, or conductive polymers can be used. As the conductive material, powdered or granular materials are particularly suitable among these.

[0037] [3. Material of support film]

[0038] As the resin material constituting the support film 120, a resin material that can make the Young's modulus of the support film 120 higher than that of the conductive film 110 can be used. As such a resin material, for example, polyester such as polyethylene terephthalate, polybutylene terephthalate or polycarbonate, polyamide such as polyamide 12, polyamide 6 or polyamide 66, polyimide such as polyetherimide, polyamideimide or polyimide, polymethyl methacrylate, polyetherketone resin (polyketone, polyetherketone, polyetheretherketone, polyetherketoneketone, etc.) or polyethersulfone can be used. In addition, the support film 120 may be subjected to surface processing such as corona discharge, plasma, coating or sputtering, or may not be subjected to surface processing.

[0039] [4. Physical properties of the conductive film and support film]

[0040] (4-1. Glass transition point and melting point)

[0041] The glass transition point of the conductive film 110 may be, for example, 40°C or less, preferably 30°C or less, and more preferably below freezing. On the other hand, the glass transition point of the support film 120 may be, for example, 30°C or more, preferably 70°C or more, and more preferably 100°C or more. For example, if the glass transition point of the support film 120 is 30°C or more, even if the wound body 10 is stored at room temperature, the conductive film 110 is appropriately pressed by the support film 120, thereby suppressing the occurrence of undulations in the conductive film 110. In addition, for example, if the glass transition point of the support film 120 is 70°C or more, even if the wound body 10 is stored in a high temperature environment (for example, 40°C to 60°C), the conductive film 110 is appropriately pressed by the support film 120, thereby suppressing the occurrence of undulations in the conductive film 110. For example, as long as the relationship of "glass transition point of the conductive film 110 <glass transition point of the support film 120" is established. In this case, since the state of the support film 120 is less likely to change than the state of the conductive film 110, even if the state of the conductive film 110 changes, the conductive film 110 can be appropriately pressed on the surface by the support film 120. In addition, it is more preferable that the relationship "glass transition point of the conductive film 110 + 10°C < glass transition point of the support film 120" holds.

[0042] The melting point of the conductive film 110 may be, for example, 300° C. or less, preferably 250° C. or less, and more preferably 200° C. or less. On the other hand, the melting point of the support film 120° C. may be, for example, 100° C. or more, preferably 200° C. or more, and more preferably 250° C. or more.

[0043] (4-2.Thickness)

[0044] The average value of the thickness of the conductive film 110 is, for example, 20 μm to 100 μm, and the deviation thereof is, for example, 3 μm to 20 μm. On the other hand, the average value of the thickness of the support film 120 is, for example, 20 μm to 120 μm, and the deviation thereof is, for example, less than 20 μm. It is known that even when the thickness deviation of the support film 120 is large, the undulation of the conductive film 110 can be suppressed.

[0045] (4-3. Film width)

[0046] The widths of the conductive film 110 and the support film 120 are not particularly limited, as long as the width of the support film 120 is greater than that of the conductive film 110. Thus, even if the conductive film 110 and the support film 120 are slightly misaligned, the conductive film 110 can be pressed against the support film 120.

[0047] (4-4. Winding thickness)

[0048] The winding thickness of the conductive film 110 is not particularly limited, but when the winding thickness of the conductive film 110 is 1 mm or more, the effect of suppressing the undulation of the conductive film 110 by the support film 120 is significant.

[0049] (4-5. Young's modulus)

[0050] The Young's modulus of each of the conductive film 110 and the support film 120 is measured by a method in accordance with ASTM D882 (Standard Test Method for Tensile Properties of Thin Plastic Sheeting). The average value of the Young's modulus of the MD (Machine Direction) and TD (Traverse Direction) of the conductive film 110 is, for example, 1000 MPa to 4000 MPa. On the other hand, the average value of the Young's modulus of the MD and TD of the support film 120 is, for example, 2000 MPa to 6000 MPa. It is sufficient that "the average value of the Young's modulus in MD and TD of the support film 120 / the average value of the Young's modulus in MD and TD of the conductive film 110 is ≥ 1.2", preferably "the average value of the Young's modulus in MD and TD of the support film 120 / the average value of the Young's modulus in MD and TD of the conductive film 110 is ≥ 1.5", and more preferably "the average value of the Young's modulus in MD and TD of the support film 120 / the average value of the Young's modulus in MD and TD of the conductive film 110 is ≥ 2.0". Furthermore, it is further preferred that "Young's modulus of the conductive film 110 × the thickness of the conductive film 110 < Young's modulus of the support film 120 × the thickness of the support film 120".

[0051] Since the support film 120 is less likely to bend than the conductive film 110 , the support film 120 can more effectively suppress the occurrence of undulations in the conductive film 110 .

[0052] (4-6. Surface roughness)

[0053] The surface roughness described below is a value in accordance with the conditions of JIS B601-1982. The average roughness Ra of at least one surface of the conductive film 110 may be, for example, 1.5 μm or less, preferably 1.0 μm or less, and more preferably 0.5 μm or less. In addition, the maximum roughness Rmax of at least one surface of the conductive film 110 may be, for example, 10.0 μm or less, preferably 7.0 μm or less, and more preferably 4.0 μm or less. In addition, the ten-point average roughness Rz of at least one surface of the conductive film 110 may be 10.0 μm or less, preferably 6.0 μm or less, and more preferably 3.0 μm or less.

[0054] The average roughness Ra of at least one surface of the support film 120 may be, for example, 1.5 μm or less, preferably 1.0 μm or less, and more preferably 0.5 μm or less. In addition, the maximum roughness Rmax of at least one surface of the support film 120 may be, for example, 10.0 μm or less, preferably 5.0 μm or less, and more preferably 1.2 μm or less. In addition, the ten-point average roughness Rz of at least one surface of the support film 120 may be 10.0 μm or less, preferably 5.0 μm or less, and more preferably 1.1 μm or less.

[0055] If at least one surface of the conductive film 110 and at least one surface of the support film 120 are smooth to some extent, when the conductive film 110 and the support film 120 are overlapped, the support film 120 is less likely to slide relative to the conductive film 110. As a result, the support film 120 can effectively press the conductive film 110 on the surface, thereby effectively suppressing the conductive film 110 from undulating.

[0056] [5. Manufacturing process]

[0057] Figure 4 FIG. 2 is a diagram showing a schematic structure of a manufacturing device 20 for a wound body 10. Figure 4 As shown, the manufacturing device 20 includes a T-die 210 , casting rolls 220 , 230 , a conveying roll 240 , and a winding roll 250 .

[0058] The T-die 210 is configured to melt and extrude the conductive film 110. The conductive film 110 extruded by the T-die 210 may be formed of multiple layers or a single layer. The casting rolls 220 and 230 are configured to cool the extruded conductive film 110 and send it downstream.

[0059] The conveying roller 240 is configured to convey the support film 120. The winding roller 250 is configured to wind up the conductive film 110 cooled by the casting rollers 220 and 230 and the support film 120 conveyed by the conveying roller 240 in an overlapping state. The conductive film 110 and the support film 120 are simply overlapped, so the conductive film 110 and the support film 120 are not bonded. After the manufacturing process in the manufacturing device 20, the wound body 10 is manufactured.

[0060] [6. Features]

[0061] As described above, in the winding body 10 according to the present embodiment, the conductive film 110 having conductivity and the support film 120 having a higher Young's modulus than the conductive film 110 are wound on the winding core 100 in an overlapping state. Therefore, with the winding body 10, the conductive film 110 can be pressed by the support film 120 having a higher Young's modulus than the conductive film 110, and thus the conductive film 110 can be suppressed from undulating.

[0062] [7. Modifications]

[0063] Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Modifications will be described below.

[0064] (7-1)

[0065] In the above embodiment, the conductive film 110 contains a conductive filler. However, the conductive film 110 does not necessarily need to contain a conductive filler. For example, the conductive film 110 may be formed of a resin having conductivity.

[0066] (7-2)

[0067] In the above embodiment, the glass transition point of the support film 120 is higher than the glass transition point of the conductive film 110 . However, this relationship does not necessarily hold. For example, the glass transition point of the support film 120 may be lower than the glass transition point of the conductive film 110 .

[0068] (7-3)

[0069] In the above embodiment, the conductive film 110 is melt-extruded through the T-die 210. However, the conductive film 110 does not necessarily have to be formed by extrusion through the T-die 210. For example, the conductive film 110 can also be formed by extrusion molding through a circular die and then cutting the tubular film. In addition, in the above embodiment, the conductive film 110 is melt-extruded. However, the film-making method of the conductive film 110 is not limited thereto. The conductive film 110 can be formed, for example, by a calendering method or a solution casting method. For example, in the case where the conductive film 110 is formed by a solution casting method, the conductive film 110 may contain a thermosetting resin.

Claims

1. A wound body for electrical / electronic equipment or parts, It is characterized in that include: A cylindrical winding core; A first film is wound around the winding core in a circumferential direction and has electrical conductivity; and A second film, wound circumferentially on the winding core, has a Young's modulus higher than that of the first film, The first film and the second film are not bonded, The first film and the second film are wound on the winding core in an overlapping state. The glass transition point of the second film is higher than the glass transition point of the first film.

2. The winding body according to claim 1, Features: The first film contains a filler having electrical conductivity.

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