Anomaly detection device and spinning apparatus for nonwoven fabric separators

Abstract

To improve the efficiency of abnormality detection of a non-woven fabric separator.SOLUTION: An abnormality detection device 40 of a non-woven fabric separator S includes a conveying device 14 that conveys a non-woven fabric separator S for a lithium ion battery 60 while being laminated on a carrier sheet 13, and an abnormality detection unit 41 that detects an abnormality in the non-woven fabric separator S on the basis of the light transmitted through the non-woven fabric separator S or the light reflected by the non-woven fabric separator S.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an abnormality detection device for a non-woven separator and a spinning device.

Background Art

[0002] Patent Document 1 discloses a technique for manufacturing a non-woven separator for a lithium ion battery by an electrospinning method (electrostatic spinning method). In the electrospinning method, a charged spinning solution is ejected from the spinning electrode side toward the collector electrode side to form fibers, and the fibers composed of this spinning solution are laminated on a sheet-like collecting member to obtain a non-woven separator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventionally, as a method for detecting abnormalities related to the thickness and fiber distribution of a non-woven separator, a method has been adopted in which a non-woven separator is cut by a certain area to cut out a sample, and the weight of the cut-out sample is measured. Such a method requires a process of cutting out a sample and a process of measuring the weight of the cut-out sample, so the efficiency of abnormality detection is poor.

[0005] The present invention has been completed based on the above circumstances, and an object thereof is to improve the efficiency of detecting abnormalities in a non-woven separator.

Means for Solving the Problems

[0006] The abnormality detection device for a non-woven separator of the present disclosure is A conveying device that transports nonwoven fabric separators for lithium-ion batteries in a stacked state on a carrier sheet, The system includes an abnormality detection unit that detects an abnormality in the nonwoven fabric separator based on light transmitted through the nonwoven fabric separator or light reflected by the nonwoven fabric separator.

[0007] The spinning apparatus of this disclosure is The aforementioned abnormality detection device, A nozzle head having a spinning electrode, The collection comprises a collector electrode positioned to sandwich the carrier sheet between the spinning electrode and the aforementioned spinning electrode, The spinning solution, charged by the spinning electrode and the collector electrode, is sprayed in a fibrous manner from the nozzle head and collected on the carrier sheet to obtain the nonwoven fabric separator. [Effects of the Invention]

[0008] According to the nonwoven fabric separator abnormality detection device and spinning device of this disclosure, abnormalities in the nonwoven fabric separator can be detected while the nonwoven fabric separator is being transported by a transport device. Since the steps of cutting a sample from the nonwoven fabric separator and measuring the weight of the cut sample are unnecessary when detecting abnormalities, the efficiency of abnormality detection can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] Side view showing the configuration of a prevention device to which the abnormality detection device of Embodiment 1 is applied. [Figure 2] A plan view showing the camera of the anomaly detection device positioned at the leftmost end of the round-trip path. [Figure 3] A plan view showing the camera of the anomaly detection device positioned at the rightmost end of the round-trip path. [Figure 4] Front view of a spinning machine [Figure 5] Plan view of the nozzle head [Figure 6] Cross-sectional view of the nozzle head [Figure 7]Block diagram showing the configuration of a spinning machine including an anomaly detection device. [Figure 8] Schematic diagram showing the structure of a lithium-ion battery [Modes for carrying out the invention]

[0010] Herein lies a preferred example of this disclosure. The abnormality detection unit comprises a camera having a lens, an image sensor, and an image processing unit, and a light-emitting unit positioned on the opposite side of the nonwoven fabric separator from the camera, and is used as an abnormality detection device and spinning device for a nonwoven fabric separator. The abnormality detection unit is a nonwoven fabric separator abnormality detection device and spinning device that detects an abnormality in the thickness of the nonwoven fabric separator based on the brightness of light transmitted through the nonwoven fabric separator. The abnormality detection unit comprises a determination unit that determines whether or not there is an abnormality based on image information obtained by the image processing unit, and a control unit that controls the transport device based on the determination result of the determination unit, and is an abnormality detection device for a nonwoven fabric separator and a spinning device. An abnormality detection device for a nonwoven fabric separator and a spinning device, comprising a camera drive unit that moves the camera back and forth in a width direction intersecting the transport direction of the carrier sheet and the nonwoven fabric separator.

[0011] [Embodiment 1] Embodiment 1, which embodies the present disclosure, will be described with reference to Figures 1 to 8. However, the present invention is not limited to these examples, and is intended to be included in the claims, with all modifications within the meaning and scope of equivalence to the claims. In Embodiment 1, the forward direction is defined as the positive direction of the X-axis in Figures 1 to 3, 5. The left-right direction is defined as the positive direction of the Y-axis in Figures 2 to 6. The left-right direction and the width direction are used synonymously. The up-down direction is defined as the positive direction of the Z-axis in Figures 1, 3, 6.

[0012] The spinning device of the first embodiment is a device for manufacturing the non-woven separator S of the lithium-ion battery 60 and detecting abnormalities in the non-woven separator S. As shown in FIG. 8, the non-woven separator S is installed between the positive electrode 62 and the negative electrode 63 in a state of being immersed in the electrolytic solution 61 of the lithium-ion battery 60 to prevent contact (internal short circuit) between the positive electrode 62 and the negative electrode 63. The non-woven separator S has a porous structure for allowing lithium ions to permeate.

[0013] The spinning device includes an electrospinning device 10 and an abnormality detection device 40. The electrospinning device 10 spins nanofiber-level ultra-fine fibers 12 (nanofibers) from the spinning solution 11 to form the non-woven separator S.

[0014] The spinning solution 11 has a resin material for forming the ultra-fine fibers 12 as a solute, and this solute is dissolved or dispersed in a volatile solvent. As the solute, for example, synthetic resins such as polyacrylonitrile (PAN), polypropylene (PP), and polyethylene (PE) are used. As the solvent, for example, compounds such as N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF), and tetrahydrofuran (THF) are used.

[0015] As shown in FIG. 1, the electrospinning device 10 includes a carrier sheet 13, a conveying device 14, a collector electrode 17, a nozzle head 20, an electrode charging unit 31 composed of a DC power source, a tank 32 which is a supply source of the spinning solution 11, and a pump 34.

[0016] The carrier sheet 13 is formed of a flexible material, such as a collection cloth like a non-woven fabric. The conveying device 14 includes a feed roller 15 and a take-up roller 16. The carrier sheet 13 is fed forward from the feed roller 15 and wound around the take-up roller 16 in a horizontally stretched state. A region of the carrier sheet 13 that is horizontally stretched between the two rollers 15 and 16 is defined as a collection region 13G. The fiber aggregate composed of the spun ultra-fine fibers 12 is laminated in a sheet shape on the lower surface of the collection region 13G of the carrier sheet 13, and this becomes the non-woven fabric separator S. The non-woven fabric separator S is peeled off from the carrier sheet 13 after being pulled out from the take-up roll together with the carrier sheet 13.

[0017] The collector electrode 17 is made of a conductive material such as metal and is disposed between the feed roller 15 and the take-up roller 16. The collector electrode 17 is disposed in a state of being close to or in contact with the upper surface of the collection region 13G over the entire width range of the carrier sheet 13. The collection region 13G of the carrier sheet 13 moves forward along the lower surface of the collector electrode 17 (the opposing surface to the spinning electrode 28 described later).

[0018] The nozzle head 20 is a member that is elongated in the left-right direction as a whole and is disposed so as to cover the entire width range of the carrier sheet 13 in the left-right direction. The nozzle head 20 is disposed at a position below the collector electrode 17 and the collection region 13G of the carrier sheet 13 and has a function of injecting the spinning solution 11 toward the collection region 13G of the carrier sheet 13. As shown in FIGS. 5 and 6, the nozzle head 20 includes a solution tank 21 and a spinning electrode 28 (supply electrode).

[0019] The solution tank 21 comprises an outer tube 22 with a circular cross-section extending linearly in the left-right direction along its axis, and an inner tube 23 with a circular cross-section extending linearly in the left-right direction along its axis. The inner tube 23 is concentrically arranged inside the outer tube 22. The interior of the inner tube 23 is defined as the first storage space 24. The space between the outer surface of the inner tube 23 and the inner surface of the outer tube 22 within the internal space of the solution tank 21 is defined as the second storage space 25. The first storage space 24 and the second storage space 25 are supplied with and stored the amount of spinning solution 11 necessary for spinning.

[0020] The outer tube 22 is made of a synthetic resin having solvent resistance and electrical insulation properties, such as fluororesin (PTFE). Multiple spinning holes 26 are formed upward in the outer tube 22, connecting the second storage space 25 to the outside of the solution tank 21 (outer tube 22). The inner tube 23 is made of a conductive metal material, such as stainless steel. The left end of the inner tube 23 protrudes outward from the left end of the outer tube 22. Multiple communication holes 27 are formed in the inner tube 23, connecting the first storage space 24 to the second storage space 25.

[0021] The spinning electrode 28 is composed of an inner tube 23. That is, the entire inner tube 23 functions as the spinning electrode 28. More specifically, the entire area of ​​the inner circumferential surface of the inner tube 23 functions as the spinning electrode 28 that comes into contact with the spinning solution 11 stored in or flowing within the first storage space 24. The entire area of ​​the outer circumferential surface of the inner tube 23 functions as the spinning electrode 28 that comes into contact with the spinning solution 11 stored in or flowing within the second storage space 25. The spinning electrode 28 is arranged along the entire length of the solution tank 21 in the left-right direction and is immersed in the spinning solution 11 in the solution tank 21. The spinning electrode 28 is connected to the positive electrode of the electrode charging section 31 via a conductive closure plate 29 provided at the right end of the inner tube 23 and an electrode plate 30 provided at the right end of the outer tube 22. The negative electrode of the electrode charging section 31 is connected to the collector electrode 17.

[0022] Tank 32 is connected to solution tank 21 via supply pipe 33. The downstream end of supply pipe 33 is connected to the left end of inner pipe 23. A pump 34 is provided in supply pipe 33. The spinning solution 11 stored in tank 32 is pumped into the first storage space 24 by the drive of pump 34. The spinning solution 11 pumped into the first storage space 24 flows into the second storage space 25 through the communication hole 27 of inner pipe 23, and is further sprayed upward to the outside of solution tank 21 from the spinning hole 26 of outer pipe 22.

[0023] Next, the method for manufacturing the nonwoven fabric separator S will be described. When the electrospinning apparatus 10 is started, the carrier sheet 13 is fed at a constant speed from the feed roller 15 towards the winding roller 16 while in contact with or close to the lower surface of the collector electrode 17. In the solution tank 21, the spinning solution 11, which has been pressurized from the tank 32, is supplied to the first storage space 24 and flows into the second storage space 25 through the communication hole 27. The spinning solution 11 comes into contact with the spinning electrode 28 as it flows through the first storage space 24 and the second storage space 25. When a voltage is applied between the spinning electrode 28 and the collector electrode 17 by activating the electrode charging unit 31, the entire spinning solution 11 in the solution tank 21 becomes positively charged.

[0024] In the spinning holes 26, electric charge is induced and accumulated on the surface of the spinning solution 11 exposed to the outer surface of the solution tank 21. These charges repel each other, and this repulsive force counteracts the surface tension of the spinning solution 11. An electrostatic force (Coulomb force) is generated between the charged spinning solution 11 and the collector electrode 17 along the electric field lines. This electrostatic force overcomes the surface tension of the spinning solution 11, causing the charged spinning solution 11 to be ejected from the multiple spinning holes 26 as nano-level ultrafine fibers 12, which are then directed towards the collector electrode 17 by the electrostatic force. The ultrafine fibers 12 of the spinning solution 11 ejected from the spinning holes 26 are layered on the lower surface of the carrier sheet 13 to form a nonwoven fabric separator S.

[0025] As shown in Figure 7, the anomaly detection device 40 is configured to include a transport device 14 shared with the electrospinning device 10 and an anomaly detection unit 41. The anomaly detection unit 41 is configured to include a camera 42, a determination unit 47, a light emission unit 49, a control unit 50, and an output unit 51.

[0026] The camera 42 is positioned below the area in the collection region 13G where the nonwoven fabric separator S is stacked. The camera 42 has a lens 43, an image sensor 44, and an image processing unit 45. The lens 43 is positioned facing upward so as to face the nonwoven fabric separator S and captures light from the carrier sheet 13 side. The angle of view of the lens 43 in the width direction of the carrier sheet 13 is set to an angle that captures a range smaller than the width dimension of the carrier sheet 13.

[0027] The image sensor 44 converts analog data of light from the subject entering through the lens 43 into digital image data and outputs it to the image processing unit 45. The image processing unit 45 extracts necessary information from the image data obtained by the image sensor 44 and outputs it to the determination unit 47. The camera 42 is driven by the camera drive unit 48 to reciprocate in a horizontal direction perpendicular to the transport direction of the carrier sheet 13. While reciprocating, the camera 42 collects image information from the carrier sheet 13 being transported.

[0028] The light-emitting unit 49 is positioned above the collection area 13G. The light-emitting unit 49 irradiates light of a predetermined wavelength toward the upper surface of the collection area 13G. The irradiation range of the light-emitting unit 49 in the width direction of the carrier sheet 13 extends across the entire width of the collection area 13G. The intensity of the light emitted from the light-emitting unit 49 is set to an intensity necessary for the image sensor 44 to receive the light after it has passed through both the carrier sheet 13 and the nonwoven fabric separator S.

[0029] The determination unit 47 determines whether or not there is an abnormality based on the image information obtained by the image processing unit 45. The information obtained from the image processing unit 45 includes, for example, light intensity, color intensity, and unevenness of color tone. Based on this information, the determination unit 47 determines whether or not the state of the nonwoven fabric separator S is abnormal. The control unit 50 controls the transport device 14, the pump 34, the charge charging unit, and the camera drive unit 48 based on the determination result of the determination unit 47. The output unit 51 consists of a monitor that displays the control status in the control unit 50 and the determination result of the determination unit 47, as well as a speaker that emits alarms and sounds to indicate abnormalities.

[0030] Next, the process for detecting abnormalities in the nonwoven fabric separator S will be described. Simultaneously with or before starting the electrospinning device 10, light is emitted from the light-emitting unit 49 toward the carrier sheet 13, and the reciprocating movement of the camera 42 and imaging by the camera 42 are started. The camera 42 captures the condition of the underside of the nonwoven fabric separator S using light that has passed through the carrier sheet 13 and the nonwoven fabric separator S. Since the field of view of the camera 42 captures an area narrower than the entire width of the nonwoven fabric separator S, detailed information about the nonwoven fabric separator S is input to the image sensor 44.

[0031] The image sensor 44 converts the input detailed light information into digital image data and outputs it to the image processing unit 45. The image processing unit 45 performs digital image processing based on the input image data and outputs the digital information necessary to detect whether or not there is an abnormality in the nonwoven fabric separator S to the determination unit 47. The determination unit 47 compares the digital information input from the image processing unit 45 with pre-stored determination data and determines whether or not there is an abnormality in the nonwoven fabric separator S.

[0032] Specific types of abnormalities include: the nonwoven fabric separator S having a basis weight (thickness) that is generally thinner than specified; the nonwoven fabric separator S having a basis weight (thickness) that is generally thicker than specified; the nonwoven fabric separator S having a basis weight that is partially thin; the nonwoven fabric separator S having a basis weight that is partially thick; foreign matter adhering to the nonwoven fabric separator S; and perforations in the nonwoven fabric separator S. These abnormal forms can be detected based on the intensity of light transmitted through the carrier sheet 13 and the nonwoven fabric separator S.

[0033] In this embodiment, the color of the carrier sheet 13 is blue, but any color other than black can be selected. In this embodiment, the thickness of the carrier sheet 13 is 0.2 mm, but it may be thicker or thinner than 0.2 mm. The material of the carrier sheet 13 is, for example, PP (polypropylene). In this embodiment, the color of the nonwoven separator S is white, but any color other than black can be selected. The thickness of the nonwoven separator S is thinner than the carrier sheet 13, and in this embodiment it is 30 μm, but it may be thinner or thicker than 30 μm. In this embodiment, the thickness of the ultrafine fibers 12 constituting the nonwoven separator S is 150 nm to 300 nm, but it may be thinner than 150 nm or thicker than 300 nm. The density of the ultrafine fibers 12 constituting the nonwoven separator S is higher than the density of the fibers constituting the carrier sheet 13. The light emitted from the light-emitting unit 49 is white light, and the light source of the light-emitting unit 49 is an LED.

[0034] When the determination unit 47 detects an abnormality, it outputs an abnormality detection signal to the control unit 50. Upon receiving the abnormality detection signal, the control unit 50 stops the transport of the carrier sheet 13 by the transport device 14, stops the spraying of the ultrafine fibers 12 by the pump 34, and stops the reciprocating movement of the camera 42 by the camera drive unit 48. Simultaneously with these stops, the output unit 51 monitors and displays that an abnormality has occurred, or emits an alarm sound or voice to indicate the abnormality.

[0035] The spinning apparatus of this embodiment 1 comprises an electrospinning apparatus 10 and an abnormality detection apparatus 40. The electrospinning apparatus 10 comprises a nozzle head 20 having a spinning electrode 28 and a collector electrode 17 positioned to sandwich a carrier sheet 13 between the spinning electrode 28 and the collector electrode 17. The electrospinning apparatus 10 obtains a nonwoven fabric separator S for a lithium-ion battery 60 by spraying a spinning solution 11 charged by the spinning electrode 28 and the collector electrode 17 in a fibrous manner from the nozzle head 20 and collecting it on the carrier sheet 13.

[0036] An anomaly detection device 40 and a transport device 14 that transports the nonwoven fabric separator S in a stacked state on the carrier sheet 13 are used to detect an anomaly in the nonwoven fabric separator S based on light transmitted through the nonwoven fabric separator S or light reflected by the nonwoven fabric separator S. Examples of anomaly detection methods for the nonwoven fabric separator S include an anomaly in the basis weight (thickness) of the nonwoven fabric separator S, the presence or absence of defects in the nonwoven fabric separator S, and the presence or absence of foreign matter embedded in the nonwoven fabric separator S.

[0037] According to the abnormality detection device 40 of this embodiment 1, abnormalities in the nonwoven fabric separator S can be detected while the nonwoven fabric separator S is being transported by the transport device 14. Since the steps of cutting a sample from the nonwoven fabric separator S and measuring the weight of the cut sample are unnecessary when detecting abnormalities, the efficiency of abnormality detection can be improved.

[0038] The anomaly detection unit 41 comprises a camera 42 and a light-emitting unit 49. The camera 42 has a lens 43 that captures light from the nonwoven fabric separator S, an image sensor 44, and an image processing unit 45. The image sensor 44 converts analog data of light from the subject that enters through the lens 43 into digital image data. The image processing unit 45 extracts the digital information necessary for anomaly detection from the image data obtained by the image sensor 44. The light-emitting unit 49 is positioned on the opposite side of the nonwoven fabric separator S from the camera 42 and emits light toward the camera 42. Anomaly detection is performed by photographing the nonwoven fabric separator S with light that has passed through the nonwoven fabric separator S using the camera 42, and based on the information obtained by the image processing unit 45. The anomaly detection unit 41 detects anomalies in the basis weight (thickness) of the nonwoven fabric separator S based on the brightness of the light that has passed through the nonwoven fabric separator S.

[0039] The abnormality detection unit 41 includes a determination unit 47 that determines the presence or absence of an abnormality based on image information obtained by the image processing unit 45, and a control unit 50 that controls the transport device 14 based on the determination result of the determination unit 47. When an abnormality in the nonwoven fabric separator S is detected, the transport device 14 can be stopped, so that the carrier sheet 13 is not wound onto the winding roller 16 without collecting the nonwoven fabric separator S.

[0040] The anomaly detection unit 41 includes a camera drive unit 48 that moves the camera 42 back and forth in the width direction intersecting the transport direction of the carrier sheet 13 and the nonwoven fabric separator S. With this configuration, by narrowing the shooting range using a lens 43 with a small field of view, the amount of image information per unit area of ​​the nonwoven fabric separator S can be increased, and high-density digital information can be obtained.

[0041] <Other examples> The present invention is not limited to the embodiments described above and in the drawings, and the following embodiments, for example, are also included in the technical scope of the present invention. Anomalies may be detected based on light reflected by a nonwoven fabric separator. A single camera may be fixed in place. Multiple cameras may be arranged side by side in the width direction. Components other than the inner tube may be used as spinning electrodes. [Explanation of Symbols]

[0042] 10... Spinning solution 13…Carrier seat 14…Conveyor equipment 17...Collector electrode 20…Nozzle head 28... Spinning electrode 40... Anomaly detection device 41... Anomaly detection unit 42... Camera 43... Lens 44…Image sensor 45…Image Processing Unit 47...Judgment section 48...Camera drive unit 49... Lighting unit 50…Control Unit 60…Lithium-ion battery S...Non-woven fabric separator

Claims

1. A conveying device that transports nonwoven fabric separators for lithium-ion batteries in a stacked state on a carrier sheet, The system includes an abnormality detection unit that detects abnormalities in the nonwoven fabric separator based on light transmitted through the nonwoven fabric separator, The abnormality detection unit, A camera having a lens, an image sensor, and an image processing unit, A light-emitting unit is positioned on the opposite side of the camera, with the nonwoven fabric separator in between, The camera has a camera drive unit that moves the camera back and forth in a width direction intersecting the transport direction of the carrier sheet and the nonwoven fabric separator, An abnormality in the nonwoven fabric separator is detected based on the brightness of the light transmitted through the nonwoven fabric separator. An abnormality detection device for a nonwoven fabric separator in which the abnormality detection target by the abnormality detection unit includes at least one of the following forms: abnormality in the thickness of the nonwoven fabric separator, presence or absence of foreign matter attached to the nonwoven fabric separator, presence or absence of perforation in the nonwoven fabric separator, presence or absence of missing parts in the nonwoven fabric separator, and presence or absence of foreign matter embedded in the nonwoven fabric separator.

2. The abnormality detection unit includes a determination unit that determines whether or not there is an abnormality based on the image information obtained by the image processing unit, An abnormality detection device for a nonwoven fabric separator according to claim 1, further comprising a control unit that controls the transport device based on the determination result of the determination unit.

3. The abnormality detection device according to Claim 1 or Claim 2, A nozzle head having a spinning electrode, The collection comprises a collector electrode positioned so as to sandwich the carrier sheet between the spinning electrode and the aforementioned spinning electrode, A spinning apparatus for obtaining a nonwoven fabric separator by spraying a spinning solution, which has been charged by the spinning electrode and the collector electrode, in a fibrous manner from the nozzle head and collecting it on the carrier sheet.

4. The carrier sheet is fed out from the feed roller of the conveying device and wound up on the winding roller, The spinning apparatus according to claim 3, wherein the density of the fibers constituting the carrier sheet is set lower than the density of the ultrafine fibers constituting the nonwoven fabric separator.

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