Film Inspection Equipment

Abstract

To provide a film inspection device capable of quickly and accurately performing inspection for defective sites on a resin film over an entire length of the resin film.SOLUTION: An inspection device 100 disclosed herein is configured nip a resin film 1 between a pair of rollers 22, 23 applied with a given voltage and allow the resin film to run therebetween, where one of the pair of rollers 22 comprises a support body 22a, an elastic layer 22b provided on the support body, and a cylindrical metal 23c provided on a surface of the elastic layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an inspection device that inspects resin films molded into a strip for the presence of defects such as foreign matter adhesion or pinholes, and in particular to a film inspection device that can detect the presence of defects while nipping and running the film between a pair of conductive rolls to which a predetermined voltage is applied. [Background technology]

[0002] Resin films (including porous resin films) are used in a wide variety of applications, such as packaging materials, electrical insulating materials (such as separators for electrochemical elements), metal deposition materials, plate-making materials, magnetic recording materials, display materials, transfer materials, window covering materials, display materials, and healthcare materials.

[0003] For example, as a resin film for a separator of an electrochemical element, a porous resin film containing polyolefin as a main component is used alone or in the form of a laminate in which a coating film of inorganic particles or the like is laminated.

[0004] However, if foreign matter such as metal powder adheres to or gets mixed into the resin film, or if defects such as pinholes are formed, these defective areas may not be able to maintain electrical insulation, or may damage the insulating material when molding electrochemical elements, potentially hindering its use in its intended applications.

[0005] A method for inspecting such resin films for defective parts is a voltage resistance test (insulation defect detection). In a voltage resistance test, electrodes are placed on both sides of the resin film and a high voltage is applied between the electrodes, and the presence of defects such as foreign matter or pinholes is detected by the flow of current between the electrodes. In such a voltage resistance test, a method has been proposed in which the resin film is nipped between a metal roll and a conductive elastic roll, and a voltage is applied between the rolls while the film is running to detect defective parts, and the running of the material is stopped to detect or remove the defective parts (see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-229907 Summary of the Invention [Problem to be solved by the invention]

[0007] The conventional defect inspection method described in Patent Document 1 can inspect a strip-shaped resin film while it is nipped and running in the longitudinal direction, making it possible to detect defective parts that occur after the pressing process, while keeping the size of fracture holes that occur in the defective parts small and enabling inspection of large-area resin films in a short time. Also, by making at least one surface of the rolls that nip the resin film a conductive elastic roll made of carbon-filled rubber, metal powder-filled rubber, carbon sheet, conductive plastic, or the like, it is possible to prevent the resin film from being damaged by protrusions or scratches on the roll surface that occur when the film runs between a pair of metal rolls.

[0008] However, the above-mentioned conventional inspection method has the problem that it is not possible to sufficiently reduce the resistance value of the surface of the conductive elastic roll, and therefore it is not possible to inspect defective parts with high accuracy.

[0009] The present disclosure is intended to solve the above-mentioned conventional problems, and aims to realize a film inspection device that can inspect defective areas in a resin film quickly and with high accuracy over the entire length of the resin film. [Means for solving the problem]

[0010] In order to solve the above problems, the film inspection device disclosed in this application is an inspection device that nips a resin film between a pair of rolls to which a predetermined voltage is applied and runs it, and is characterized in that one of the pair of rolls has a support, an elastic layer arranged on the support, and a cylindrical metal arranged on the surface of the elastic layer. [Effects of the Invention]

[0011] The film inspection device disclosed in the present application has a pair of rolls to which a predetermined voltage is applied, one of which is a roll including a support, an elastic layer disposed on the support, and a cylindrical metal disposed on the surface of the elastic layer. As a result, a withstand voltage test can be performed while a predetermined pressure is applied to a resin film traveling between the rolls, and discharge can be generated in areas of the resin film containing foreign matter, thereby enabling reliable detection of defective areas. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram illustrating the overall configuration of a film inspection device. [Figure 2] FIG. 2 is a schematic perspective view illustrating the shape of a roll that nips a resin film. [Figure 3] 10A and 10B are diagrams illustrating the state after a voltage resistance test is performed by nipping a resin film against a portion where metal powder is present. [Figure 4] 10A and 10B are diagrams illustrating the state after a voltage resistance test is performed on a portion where metal powder is present without applying pressure to the resin film. DETAILED DESCRIPTION OF THE INVENTION

[0013] The film inspection device disclosed in this application is an inspection device that nip a resin film between a pair of rolls to which a predetermined voltage is applied and runs the film, one of the pair of rolls having a support, an elastic layer disposed on the support, and a cylindrical metal member disposed on the surface of the elastic layer.

[0014] By doing this, the film inspection device disclosed in this application can apply appropriate pressure to the resin film being inspected, causing discharges in areas where foreign matter such as metal powder is present, thereby enabling defective areas to be reliably detected.

[0015] In the film inspection device having the above configuration, it is preferable that the elastic layer is made of silicone sponge rubber. cylindrical metal The one roll on which the roller is disposed can be a metal-surfaced roll that applies an appropriate pressing force to the resin film and has durability.

[0016] The thickness of the cylindrical metal is 0.05 mm to 0.3 mm, cylindrical metal It is preferable that the surface of the elastic layer is adhered to the surface of the elastic layer. cylindrical metal The process of placing the resin film can be easily performed, and the resin film can be easily moved. cylindrical metal This can prevent the axial displacement of the shaft.

[0017] It is also preferable to further include a defect inspection unit having an imaging unit that images the surface of the resin film that has run between the pair of rolls. In this way, it is possible to realize a film inspection device that can continuously perform a withstand voltage inspection and an optical inspection.

[0018] (Embodiment) Hereinafter, a film inspection device according to the present disclosure will be described with reference to the drawings.

[0019] FIG. 1 is a conceptual diagram illustrating the overall configuration of a film inspection device according to this embodiment.

[0020] As shown in FIG. 1, the inspection device 100 of this embodiment includes an unwinding roll 10, a withstand voltage inspection section 20, an optical inspection section 30, and a winding roll 40, and performs a withstand voltage inspection and an optical inspection while running the resin film 1 between the unwinding roll 10 and the winding roll 40 at a maximum speed of, for example, 200 m / min.

[0021] In this embodiment, the resin film 1 to be inspected was four types of laminated films (separators for non-aqueous electrolyte secondary batteries), designated laminated films 1 to 4, which were formed by coating one surface of a polyolefin microporous film having a thickness of 9.5 to 19 μm and a porosity of approximately 50%, with an inorganic particle film (proportion of boehmite particles: 95 mass%) having a thickness of 3 to 4.5 μm, in which boehmite particles were bonded with a resin binder, as shown in Table 1 below.

[0022] [Table 1]

[0023] In the withstand voltage testing section 20, a first roll 22 and a second roll 23 are arranged to sandwich the resinous film 1 that has passed through the position restricting roll 21 from above and below, and the resinous film is nipped.

[0024] FIG. 2 shows an enlarged image diagram for explaining the configuration of the first roll 22 and the second roll 23 in the withstand voltage testing section.

[0025] 2, in the withstand voltage testing section 20 of the testing device 100 according to this embodiment, a first roll 22 and a second roll 23 nip the resinous film 1 to be tested. In the testing device according to this embodiment, the first roll 22 is disposed above the resinous film 1 to be tested, and an elastic layer 22b is disposed on a support 22a. cylindrical metalThe resin film 1 is nipped by a metal-surfaced rubber roll 22c bonded to the first roll 22a with an adhesive. On the other hand, the second roll 23 disposed below the resin film 1 is a stainless steel metal roll. In this embodiment, the linear pressure applied to the nipped resin film 1 was 8 g / mm and 150 g / mm, and measurements were carried out under each condition.

[0026] The first roll, the metal-surfaced rubber roll 22, is made of a support 22a made of chrome-plated nickel and having a diameter of 75.3 mm, on which an elastic layer 22b made of silicon sponge rubber and having a thickness of about 10 mm is disposed. cylindrical metal 22c is placed, cylindrical metal 22c is adhered to the surface of the elastic layer 22b with a silicone adhesive, so that when the resin film 1 is run cylindrical metal 22c prevents the metal-surfaced roll 22 from shifting in the axial direction. cylindrical metal 22c and the second roll 23 are electrically connected to high voltage power supplies provided in the withstand voltage testing section 20 so that discharge can occur between them.

[0027] The support 22a including the central shaft portion can be made of a material having high rigidity and high conductivity, such as metals such as iron and aluminum alloys, or carbon fiber reinforced plastics, in addition to the stainless steel mentioned above. If the diameter of the support 22a is large, the weight of the support 22a can be reduced by making the inside hollow.

[0028] In addition to the above-mentioned silicone sponge rubber, the elastic layer 22b may be made of a foam such as acrylonitrile butadiene rubber, ethylene propylene rubber, chloroprene rubber, or urethane rubber. The elastic layer 22b preferably has a Poisson's ratio of 0.4 or less, and more preferably a Poisson's ratio of 0.2 or less. The thickness of the elastic layer 22b is preferably 3 mm or more and 15 mm or less.

[0029] In addition, an intermediate layer formed by molding ebonite, FRP, rubber, resin, etc. can be placed between the support body 22a and the elastic layer 22b, and by placing the intermediate layer, the adhesion between the support body 22a and the elastic layer 22b can be improved.

[0030] cylindrical metal 22c can be a metal sleeve made of nickel, stainless steel, chromium, or the like, with a thickness of 0.05 mm to 0.3 mm. cylindrical metal By making the surface of 22c have a maximum thickness (JIS B 0601:2013) Rz of 0.2 μm or less, it is possible to prevent the surface smoothness of the nipped resinous film 1 from being impaired.

[0031] Elastic layer 22b and cylindrical metal 22c is the elastic layer 22b contracted after applying a silicone adhesive to the surface of the elastic layer 22b. cylindrical metal It can be glued by inserting it into 22c.

[0032] The second roll 23 can be made of metal such as stainless steel, iron, or aluminum alloy, or carbon fiber reinforced plastic. The diameter of the second roll 23 used in the film inspection device according to this embodiment is 60 mm. The diameter of the metal-surfaced rubber roll 22 and the diameter of the second roll 23 can be approximately the same, or the diameter of the metal-surfaced rubber roll 22 can be approximately 1% to 20% larger than the diameter of the second roll 23. The roll diameters of the first roll and the second roll are preferably different from each other and also different from the roll systems of other rolls equipped in the inspection device. This makes it easy to determine which roll a defect occurring in a roll is caused by.

[0033] In the film inspection device 100 according to this embodiment, a voltage resistance test is performed by running the resin film 1 at a predetermined speed (for example, 50 to 200 m / min) while applying a predetermined voltage (for example, 0.5 to 1.6 kV) between the metal-surfaced rubber roll 22 and the second roll. Although not shown in FIG. 1, the voltage resistance test unit 20 is equipped with a detection mechanism that detects discharges that occur between the metal-surfaced rubber roll 22 and the second roll 23, and is capable of determining the position where a discharge occurs on the running resin film 1 as a travel distance (i.e., the distance from the end on the running start side to the point where the discharge occurred).

[0034] Table 2 shows examples of applied voltages that can correctly detect pinholes.

[0035] [Table 2]

[0036] Table 2 shows the range of voltage to be applied to the laminate film so that, when pinholes are formed at regular intervals in advance in the four types of laminate film (Laminate Film 1 to Laminate Film 4) shown in Table 1 and the film is run at a speed of 200 m / min, discharge always occurs at the pinhole positions and no discharge occurs in positions where there are no pinholes, i.e., to correctly identify and detect pinholes. When the voltage applied to the laminate film is smaller than the range shown in Table 2, no discharge occurs in one or more pinholes. On the other hand, when the applied voltage is larger than the range shown in Table 2, discharge occurs in one or more positions where there are no pinholes.

[0037] As a result of investigations by the inventors, it was confirmed that defects in the resinous film 1 can be correctly detected by applying an appropriate voltage, even when the resinous film is run at a speed of 200 m / min. Similar measurements were carried out by changing the running speed of the resinous film 1 to 50 m / min, 100 m / min, and 150 m / min, and the range of applied voltage in which defects could be correctly detected was almost the same as when the resinous film 1 was run at 200 m / min, as shown in Table 2 above.

[0038] Since the resin film 1 is wound up in a roll, defective areas due to the inclusion of foreign matter often appear periodically at predetermined intervals, and since the results of the inventors' verification described above show a periodicity, it can be determined that defective areas in the resin film have been correctly detected.

[0039] The resin film 1 is nipped between the metal-surfaced rubber roll 22 and the second roll, and then travels through the second regulating roll 24 to the optical inspection section 30 .

[0040] In the optical inspection section 30, a camera 31 disposed above observes the surface condition of the resinous film 1. To facilitate detection of defects such as pinholes in the resinous film 1, an illumination device 32 is disposed opposite the lens optical axis 33 of the camera 31 with the resinous film 1 sandwiched between them.

[0041] The optical inspection unit 30 can detect foreign matter such as metal powder, which is recognized as black dots, and defects such as pinholes, which are recognized as white dots, present on the resin film in accordance with the travel distance of the resin film, based on images captured by the imaging unit of the camera 31. In particular, by enlarging and analyzing images captured using a lens that is less likely to cause image distortion, such as a telecentric lens, through data processing, it is expected that metal foreign matter and defects as small as several tens of μm in size can be detected.

[0042] The resin film 1 that has traveled through the optical inspection section 30 is sequentially wound around the winding roll 40, whereupon the withstand voltage inspection and optical inspection are completed.

[0043] Here, the detection of foreign matter (metal powder) contained in a resin film in the film inspection device 100 shown in the above embodiment will be described.

[0044] Figure 3 is a micrograph showing the metal powder contained in a resin film and the surrounding area when a voltage withstand test was conducted by nipping the resin film between a pair of rolls at a linear pressure of 8 g / mm and running it at a speed of 200 m / min, to which a voltage of 1.1 kV was applied.

[0045] Figure 3(a) shows the results of observation of the metal powder using reflected light as viewed from the side where the inorganic particle film was formed, Figure 3(b) shows the results of observation of the metal powder using reflected light as viewed from the side where the original film was formed, Figure 3(c) shows the results of observation of the metal powder using transmitted light as viewed from the side where the inorganic particle film was formed, and Figure 3(d) shows the results of observation of the metal powder using transmitted light as viewed from the side where the original film was formed. Each of Figures 3(a) to 3(d) is image data captured using an optical microscope at 300x magnification. The thin lines in each figure are added to measure dimensions.

[0046] The granular matter indicated by the arrows in Figures 3(a) and 3(b) and the black areas in Figures 3(c) and 3(d) are metal powder, and the white areas next to the metal powder in Figures 3(c) and 3(d) are pinholes with a major axis of approximately 70 μm that were generated by heat generated when discharges occurred as the metal powder passed between the rolls. The occurrence of discharges at the position of the metal powder and the creation of pinholes next to the metal powder due to these discharges make it easy to detect the presence of foreign matter using the inspection device of this embodiment.

[0047] FIG. 4 is a micrograph showing, as a comparative example, the metal powder contained in a resin film and the state of its surroundings when a voltage resistance test was conducted by passing the resin film between rolls without nipping it.

[0048] As in the figures in Figure 3, Figure 4(a) shows the results of observation of the metal powder using reflected light as viewed from the side where the inorganic particle film was formed, Figure 4(b) shows the results of observation of the metal powder using reflected light as viewed from the side where the original film was formed, Figure 4(c) shows the results of observation of the metal powder using transmitted light as viewed from the side where the inorganic particle film was formed, and Figure 4(d) shows the results of observation of the metal powder using transmitted light as viewed from the side where the original film was formed. As in Figure 3, the images shown are image data captured with an optical microscope at 300x magnification.

[0049] As shown in Figure 4, it can be confirmed that no discharge occurred and no pinholes were formed even when a voltage of 1.1 kV, the same voltage as in the voltage withstand test, was applied without nipping (without applying pressure). In the inventors' study, even when metal powder was mixed into the resin film, discharge was confirmed at only two locations out of 450 when no nipping was performed at the location of the metal powder. Therefore, it was confirmed that when the resin film is not nipped with a roll and no pressure is applied, as with the inspection device shown in this embodiment, the presence of foreign matter cannot be easily detected even when a high voltage is applied.

[0050] As described above, when inspecting a resin film traveling at 200 m / min using the inspection device 100 of this embodiment, it was confirmed that, by setting the applied voltage to 1.1 kV at a linear pressure of 8 g / mm, discharge could be achieved at the location of foreign matter such as metal powder present on the resin film. It was also confirmed that discharge could be achieved at the location of fine defects such as pinholes. Of course, the linear pressure for nipping the resin film and the voltage applied between the metal-surfaced roll and the second roll need to be adjusted depending on the material, film thickness, laminate structure, and number of laminated layers of the resin film to be inspected, as well as the traveling speed of the resin film during inspection. However, it was confirmed that the inspection device of this embodiment can accurately detect foreign matter and defects present on the resin film.

[0051] Furthermore, by using the above-mentioned metal-surfaced rubber roll as one of the two rolls when conducting a voltage resistance test, it was confirmed that roll edge marks, which occur on a resin film when both rolls are metal rolls, do not occur. Furthermore, in a voltage resistance test using two metal rolls, it was confirmed that the roll would jump at protruding portions, which are unmelted portions called wedges, contained in the resin film, but it was confirmed that such jumping does not occur when one of the rolls shown in this embodiment is a metal-surfaced rubber roll.

[0052] In the above embodiment, an inspection device equipped with both a charging inspection unit and an optical inspection unit is exemplified, but the optical inspection unit is not a required component of the inspection device disclosed in this application, and the inspection device may have only a charging inspection unit.

[0053] Furthermore, unlike the inspection device described in the above embodiment, the inspection device disclosed in the present application can be incorporated as part of a resin film manufacturing device that applies a film made of specified inorganic particles to a resin substrate, rather than as an inspection device that re-inspects the manufactured resin film, making it possible to carry out the manufacturing and inspection of resin films in a seamless manner. [Industrial Applicability]

[0054] The film inspection device of the present disclosure is configured to: nip one of the rollers that nip the resin film to be inspected; cylindrical metal By using a roll having the above arrangement, it is extremely useful as an inspection device that can reliably detect defective parts such as foreign matter and defects while running a resin film at high speed. [Explanation of symbols]

[0055] 1. Resin film 20. Voltage Resistance Inspection Department twenty two Metal-surfaced rubber roll (first roll) 23 Second Roll 30 Optical Inspection Department 100 Film inspection equipment

Claims

1. A film inspection device that detects defective portions of a resin film by nipping and running a resin film between a pair of rolls to which a predetermined voltage is applied, A film inspection device, characterized in that one of the pair of rolls comprises a support, an elastic layer disposed on the support, and a cylindrical metal disposed on the surface of the elastic layer.

2. 2. The film inspection device according to claim 1, wherein the elastic layer is made of silicone sponge rubber.

3. 2. The film inspection device according to claim 1, wherein the cylindrical metal has a thickness of 0.05 mm to 0.3 mm, and the cylindrical metal is adhered to the surface of the elastic layer.

4. The film inspection device according to claim 1 , further comprising a defect inspection unit having an imaging unit that captures an image of the surface of the resin film that has traveled between the pair of rolls.

Images