CN114204124A

CN114204124A - Wound body

Info

Publication number: CN114204124A
Application number: CN202010883681.6A
Authority: CN
Inventors: 川户耕佑; 西冈亮
Original assignee: Gunze Ltd
Current assignee: Gunze Ltd
Priority date: 2020-08-28
Filing date: 2020-08-28
Publication date: 2022-03-18

Abstract

The invention aims to prevent a film from undulation in a wound body having 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 the circumferential direction and has conductivity. The second film is wound around the winding core in a circumferential direction and has a higher Young's modulus 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 overlapped state.

Description

Wound body

Technical Field

The present invention relates to a wound body.

Background

Jp 2013-116442 a (patent document 1) discloses a wound body of a laminated porous film used for a separator of a lithium ion battery, for example.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-116442

Disclosure of Invention

Technical problem to be solved by the invention

The fluctuation in the thickness of the film having conductivity may be larger than that of the laminated porous film disclosed in patent document 1. When the thickness fluctuation is large, a pressure difference is generated in the plane due to the thickness fluctuation when the film is wound around the winding core. The film shrinkage is hard to occur in a region where the pressure is high, and the film shrinkage is easy to occur in a region where the pressure is low. Due to the difference in the degree of shrinkage of each region, the film is likely to undulate.

Fig. 5 is a photograph showing an example of the undulation generated in the film. As shown in fig. 5, for example, when the film is drawn out from the wound body and laid flat on a stage, undulation of the film is easily observed by visual observation. The undulation of the film is considered to be caused by the film locally stretching in the planar direction of the film in the process of forming the wound body.

The present invention has been made to solve the above-described problems, and an object of the present invention is to suppress the occurrence of undulation in a film in a wound body having a conductive film.

Technical solution for solving technical problem

The wound body according to the present invention includes a cylindrical winding core, a first film, and a second film. The first film is wound around the winding core in the circumferential direction and has conductivity. The second film is wound around the winding core in a circumferential direction and has a higher Young's modulus 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 overlapped state.

In the wound body, a first film having conductivity and a second film having a higher Young's modulus than the first film are wound around a winding core in an overlapped state. Therefore, according to the wound body, the first film is pressed by the second film having a higher young's modulus than the first film, and thus the first film can be suppressed from being undulated.

In the above wound body, the first film may contain a filler having conductivity.

If the filler having conductivity is contained, the thickness fluctuation of the first film becomes large. As described above, in the case where the thickness fluctuation is large, the undulation may be generated in the first film. In the wound body according to the present invention, as described above, the first film having conductivity and the second film having a higher young's modulus than the first film are wound around the wound body in an overlapped state. Therefore, even if the first film contains a filler having conductivity, the wound body can suppress the first film from undulation by pressing the first film with the second film having a higher young's modulus than the first film.

In the above-described wound body, the glass transition point of the second film may be higher than the glass transition point of the first film.

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 prevented from undulation.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the occurrence of undulation in the film can be suppressed in the wound body having the conductive film.

Drawings

Fig. 1 is a perspective view schematically showing a wound body.

Fig. 2 is a schematic view showing the front of the wound body.

Fig. 3 is a view showing a section III-III of fig. 2 and an enlarged part of the section.

Fig. 4 is a diagram showing a schematic configuration of a wound body manufacturing apparatus.

Fig. 5 is a photograph showing an example of the undulation generated in the film.

Description of the symbols

10: a winding body; 20: a manufacturing device; 100: winding the core; 110: a conductive film; 120: a support film; 210: performing T mold; 220. 230: a casting roll; 240: a conveying roller; 250: and (4) a winding roller.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated.

[1. Structure of wound body ]

Fig. 1 is a perspective view schematically showing a wound body 10 according to the present embodiment. Fig. 2 is a diagram schematically showing the front of the wound body 10 according to the present embodiment. Fig. 3 is a view showing a section III-III of fig. 2 and an enlarged part of the section.

As shown in fig. 1, 2, and 3, in the cylindrical wound body 10, the conductive film 110 and the support film 120 are wound around the cylindrical wound core 100. More specifically, the conductive film 110 and the support film 120 are wound around the winding core 100 in a state of being overlapped in the circumferential direction. That is, the conductive films 110 and the support films 120 are alternately present in the radial direction in the cross section along the radial direction of the wound body 10 (see the enlarged portion of fig. 3). As described in detail below, the conductive film 110 has conductivity, and the support film 120 has a higher young's modulus than the conductive film 110.

The conductive film 110 contains, for example, a filler having conductivity (hereinafter, also referred to as "conductive filler"). When the conductive filler is contained, the thickness fluctuation of the film becomes larger than that in the case where the conductive filler is not contained. When the fluctuation in thickness is large, if only the conductive film 110 is wound around the winding core 100, a pressure difference is generated in the surface of the conductive film 110 due to the fluctuation in thickness. The conductive film 110 is less likely to shrink in a high pressure region, and the conductive film 110 is more likely to shrink in a low pressure region. The conductive film 110 may be undulated due to a difference in the degree of shrinkage of each region.

In the wound 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 around the winding core 100 in an overlapped state. Therefore, according to the wound body 10, the support film 120 having a higher young's modulus than the conductive film 110 presses the conductive film 110, and thus the generation of undulation in the conductive film 110 can be suppressed.

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.

[2. Material for conductive film ]

The conductive film 110 is, for example, a non-porous film, and contains a thermoplastic resin material and a conductive material (conductive filler). The conductive film 110 is used as, for example, a charged film or a neutralization film for a copying machine, a printer, or the like, and various functional films for other electric/electronic devices or parts. 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 may be used as long as it is a resin material having thermoplasticity.

As the thermoplastic resin material, for example, polyolefin-based resins (homopolymers and copolymers) can be used. Examples of the thermoplastic resin include fluorine-based copolymers such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), and tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (EPE), polyester-based copolymers such as polyether ester, and polyamide-based copolymers such as polyether amide and polyether ester amide. Further, as the thermoplastic resin, for example, a polymer alloy or a polymer blend of the above-mentioned materials can be used.

As the conductive material, a known material having conductivity can be used. As the conductive material, for example, a carbon material such as graphite or carbon black, an ion conductive material, a metal oxide such as zinc oxide or tin oxide, a metal such as copper or silver, a conductive polymer, or the like can be used. Among these, powdery or granular materials are particularly preferably used as the conductive material.

[3. Material for supporting film ]

As the resin material constituting the support film 120, a resin material capable of making the young's modulus of the support film 120 higher than that of the conductive film 110 can be used. Examples of the resin material include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polycarbonate, polyamides such as polyamide 12, polyamide 6, and polyamide 66, polyimides such as polyetherimide, polyamideimide, and polyimide, polymethyl methacrylate, polyether ketone resins (polyketone, polyether ketone, polyether ether ketone, and polyether ketone), polyether sulfone, and the like. The support film 120 may or may not have been subjected to surface processing such as corona discharge, plasma, coating, or sputtering.

[4. physical Properties of the conductive film and the supporting film ]

(4-1. glass transition point and melting Point)

The glass transition point of the conductive film 110 may be, for example, 40 ℃ or lower, preferably 30 ℃ or lower, and more preferably below the freezing point. On the other hand, the glass transition point of the support film 120 may be, for example, 30 ℃ or higher, preferably 70 ℃ or higher, and more preferably 100 ℃ or higher. For example, if the glass transition point of the support film 120 is 30 ℃ or higher, the support film 120 appropriately presses the conductive film 110 even when the wound body 10 is stored at room temperature, and the occurrence of undulation in the conductive film 110 is suppressed. Further, for example, if the glass transition point of the support film 120 is 70 ℃ or higher, even if the wound body 10 is stored in a high-temperature environment (for example, 40 ℃ to 60 ℃), the support film 120 appropriately presses the conductive film 110, thereby suppressing the occurrence of undulation in the conductive film 110. For example, the relationship "the glass transition point of the conductive film 110 < the glass transition point of the support film 120" may be satisfied. 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 by the support film 120. In addition, it is more preferable that the relationship of "the glass transition point of the conductive film 110 +10 ℃ < the glass transition point of the support film 120" holds.

The melting point of the conductive film 110 may be, for example, 300 ℃ or lower, preferably 250 ℃ or lower, and more preferably 200 ℃ or lower. On the other hand, the melting point of the support film at 120 ℃ may be, for example, 100 ℃ or higher, preferably 200 ℃ or higher, and more preferably 250 ℃ or higher.

(4-2. thickness)

The average thickness of the conductive film 110 is, for example, 20 to 100 μm, and the variation is, for example, 3 to 20 μm. On the other hand, the average thickness of the support film 120 is, for example, 20 μm to 120 μm, and the variation is, for example, 20 μm or less. It is known that the occurrence of undulation of the conductive film 110 can be suppressed even when the variation in the thickness of the support film 120 is large.

(4-3. film Width)

The width of each of the conductive film 110 and the support film 120 is not particularly limited as long as the width of the support film 120 is longer than the width of the conductive film 110. Thus, even if the positional relationship between the conductive film 110 and the support film 120 is slightly misaligned, the entire conductive film 110 can be pressed against the support film 120.

(4-4. winding thickness)

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

(4-5. Young's modulus)

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, Standard Test Method for Tensile Properties of Plastic Sheeting). The average value of the young's moduli in the MD (Machine Direction) and TD (transverse Direction) of the conductive film 110 is, for example, 1000MPa to 4000 MPa. On the other hand, the average value of the young's moduli of MD and TD of the support film 120 is, for example, 2000MPa to 6000 MPa. The "average value of young's moduli of MD and TD of the support film 120/average value of young's moduli of MD and TD of the conductive film 110" may be equal to or greater than 1.2 ", preferably" average value of young's moduli of MD and TD of the support film 120/average value of young's moduli of MD and TD of the conductive film 110 "is equal to or greater than 1.5", and more preferably "average value of young's moduli of MD and TD of the support film 120/average value of young's moduli of MD and TD of the conductive film 110" is equal to or greater than 2.0 ". Further, it is more preferable that "young's modulus of the conductive film 110 × thickness of the conductive film 110" be smaller than young's modulus of the support film 120 × thickness of the support film 120 ".

Since the support film 120 is less likely to bend than the conductive film 110, the occurrence of undulation of the conductive film 110 can be more effectively suppressed by the support film 120.

(4-6. surface roughness)

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. 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. 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.

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, and 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. 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.

If at least one side of the conductive film 110 and at least one side of the support film 120 are smooth to some extent, the support film 120 is less likely to slide with respect to the conductive film 110 in a case where the conductive film 110 and the support film 120 are overlapped. As a result, the support film 120 can effectively press the conductive film 110 against the surface, and thus the occurrence of undulation in the conductive film 110 can be effectively suppressed.

[5. production Process ]

Fig. 4 is a schematic configuration diagram of the manufacturing apparatus 20 for the wound body 10. As shown in fig. 4, the manufacturing apparatus 20 includes a T die 210, casting

rollers

220, 230, a conveying roller 240, and a take-up roller 250.

The T-die 210 is configured to melt extrude the conductive film 110. The conductive film 110 extruded through the T-die 210 may be formed of a plurality of layers or a single layer. The casting

rollers

220 and 230 are configured to cool the extruded conductive film 110 and send it downstream.

The conveying roller 240 is configured to convey the support film 120. The winding roller 250 is configured to wind the conductive film 110 cooled by the casting

rollers

220 and 230 and the support film 120 conveyed by the conveying roller 240 in a state of being overlapped. Since the conductive film 110 and the support film 120 are simply stacked, the conductive film 110 and the support film 120 are not bonded. The wound body 10 is manufactured through the manufacturing process in the manufacturing apparatus 20.

[6. characteristics ]

As described above, in the wound 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 around the winding core 100 in a superposed state. Therefore, the support film 120 having a higher young's modulus than the conductive film 110 can press the conductive film 110 with the wound body 10, and thus the conductive film 110 can be prevented from undulation.

[7. modification ]

The embodiments have been described above, but the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit thereof. Hereinafter, a modified example will be described.

(7－1)

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

(7－2)

In the above embodiment, the glass transition point of the support film 120 is higher than that 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 that of the conductive film 110.

(7－3)

In the above embodiment, the conductive film 110 is melt-extruded through the T-die 210. However, the conductive film 110 does not have to be extruded through the T-die 210 to be shaped. For example, the conductive film 110 may be formed by extrusion molding using a circular die and then cutting a tubular film. In the above embodiment, the conductive film 110 is melt-extruded. However, the method for forming the conductive film 110 is not limited to this. The conductive film 110 can be formed by, for example, a rolling method or a solution casting method. For example, in the case where the conductive film 110 is molded by a solution casting method, the conductive film 110 may contain a thermosetting resin.

Claims

1. A wound body, comprising:

a cylindrical winding core;

a first film wound around the winding core in a circumferential direction and having conductivity; and

a second film wound around the winding core in a circumferential direction and having a higher Young's modulus 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 overlapped state.

2. The wound body according to claim 1, wherein:

the first film contains a filler having conductivity.

3. The wound body according to claim 1 or 2, wherein:

the second film has a glass transition point higher than that of the first film.