Laminated metal plate, welded product, battery cell, method for manufacturing laminated metal plate, method for manufacturing welded product, and method for manufacturing battery cell

Abstract

This laminated metal plate is provided with a base metal plate and a resin coating that covers one or both surfaces of the base metal plate, an exposed part from which the base metal plate is exposed is provided on a part of the surface of the laminated metal plate on which the resin coating is provided, and the resin coating has a main body part and a transition part provided around the exposed part. In the main body part, the interface between the base metal plate and the resin coating film is substantially parallel to the surface of the resin coating film, and in the transition part, the surface of the resin coating film is inclined from the surface of the resin coating film in the main body part toward the surface of the base metal plate in the exposed part. In the surface of the base metal plate, a region in which the transition portion is disposed and a region in which the exposed portion is disposed are continuously connected.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a laminated metal sheet, a welded product, a battery cell, a manufacturing method of a laminated metal sheet, a manufacturing method of a welded product, and a manufacturing method of a battery cell.

[0002] This application claims priority based on Japanese Patent Application No. 2023-149240 filed on September 14, 2023, the contents of which are hereby incorporated by reference. BACKGROUND

[0003] A laminated metal sheet is manufactured by laminating a metal sheet and a resin film (resin coating). The corrosion resistance of the metal sheet (base metal sheet) of the laminated metal sheet is improved by the resin coating. Therefore, the laminated metal sheet is widely used as a material of a mechanical structure such as a battery cell and a canister that requires corrosion resistance.

[0004] However, if the laminated metal sheet is subjected to laser welding or resistance seam welding, defects are easily generated in the welded portion. This is because, at the time of welding, carbon and hydrogen that constitute the resin film intrude into the molten metal, or the resin film evaporates to form a bubble in the molten metal. As a result, the weld bead formed by solidification of the molten metal generates excess hardening, cracking, and destabilization, and the like. In addition, in resistance seam welding, the resin coating interferes with the passage of electricity, and therefore a good welded portion cannot be obtained. Therefore, in the case where the laminated metal sheet is used as a material of a welded product, it is necessary to remove the resin coating before welding.

[0005] The resin coating can be removed mechanically using a grinding tool. In addition, the resin coating can also be removed by laser irradiation. From the viewpoint of shortening the time required for the resin coating, it is preferable to remove the resin coating by laser irradiation. So far, various proposals have been made regarding laser irradiation techniques for removing the resin coating.

[0006] In Patent Literature 1, a manufacturing method of a top plate of an 18-liter canister is disclosed, which is characterized in that laser of a carbon dioxide laser is irradiated to two linear protrusions formed on a top plate of an 18-liter canister made of a varnish resin coated steel sheet and a laminated steel sheet, and only the resin layer of the portion required for surface welding is removed.

[0007] In Patent Literature 2, a coating removal method is disclosed, which is a coating removal method of removing a coating layer provided on a surface of a base material, which comprises: a breaking process of breaking a region of the coating layer that is in contact with the surface before the coating layer is softened; a peeling process of peeling the coating layer in which the region is broken from the surface; and a removing process of removing a residue remaining on the surface exposed by the peeling process, in which laser is irradiated to the surface of the base material exposed by the peeling process in the removing process.

[0008] Prior Art Documents Patent Documents Patent Document 1: Japanese Patent Application Publication No. 2006-7225 Patent Document 2: Japanese Patent Application Publication No. 2022-186272 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION However, the present inventors found that the resin film could not be sufficiently removed using the conventional laser irradiation technique. For example, a thick polypropylene film is difficult to remove even using the conventional laser irradiation technique. The present inventors conducted experiments, and as a result, in the case where a carbon dioxide laser disclosed in Patent Document 1 was irradiated to a resin film composed of polypropylene, the resin film was thinned but remained on the base metal plate continuously. The resin film remaining on the base metal plate could not be removed unless additional mechanical processing such as grinding was performed.

[0010] From the viewpoint of quickly removing the resin film, it is preferable to remove the resin film using only laser. The technique of Patent Document 1 could not exert sufficient effects on a thick polypropylene film. The technique of Patent Document 2 is a technique of removing a film by combining induction heating with laser, and a method for removing a resin film using only laser is not disclosed.

[0011] In view of the above, the present disclosure aims to provide a manufacturing method of a laminated metal plate, a manufacturing method of a soldered product, and a manufacturing method of a battery cell, in which a resin film of the laminated metal plate is easily removed to expose the base metal plate, as well as a laminated metal plate, a soldered product, and a battery cell.

[0012] MEANS FOR SOLVING THE PROBLEMS The gist of the present disclosure is as described below.

[0013] (1) A laminated metal plate according to an aspect of the present disclosure includes a base metal plate and a resin film covering one or both surfaces of the base metal plate, wherein a part of a surface of the laminated metal plate on which the resin film is provided is provided with an exposed portion in which the base metal plate is exposed, the resin film has a main portion and a transition portion provided around the exposed portion, in the main portion, an interface between the base metal plate and the resin film is substantially parallel to a surface of the resin film, in the transition portion, the surface of the resin film is inclined from the surface of the resin film in the main portion toward the surface of the base metal plate in the exposed portion, and a region of the surface of the base metal plate in which the transition portion is disposed and a region of the surface of the base metal plate in which the exposed portion is disposed are continuously connected.

[0014] (2) In the laminated metal plate according to the above (1), it is preferable that the resin film have a polyolefin-based resin as a main component.

[0015] (3) Preferably, in the laminated metal plate described in the above (2), the resin coating film has a polypropylene resin as a main component.

[0016] (4) Preferably, in the laminated metal plate described in any one of the above (1) to (3), the thickness of the resin coating film in the main body portion is 18.0 μm or more.

[0017] (5) Preferably, in the laminated metal plate described in any one of the above (1) to (4), the exposed portion has a belt-like shape extending along the end portion of the laminated metal plate.

[0018] (6) Preferably, in the laminated metal plate described in any one of the above (1) to (5), in the transition portion, the angle formed by the surface of the base metal plate and the surface of the resin coating film is 5 to 70 degrees.

[0019] (7) Preferably, in the laminated metal plate described in any one of the above (1) to (6), the base metal plate is a steel plate.

[0020] (8) A welded product according to another aspect of the present disclosure includes: the laminated metal plate described in any one of the above (1) to (7); a material to be welded that is joined to the laminated metal plate; and a welded portion that is provided to the exposed portion of the laminated metal plate and joins the laminated metal plate and the material to be welded.

[0021] (9) A battery cell according to another aspect of the present disclosure includes the welded product described in the above (8).

[0022] (10) A method for manufacturing a laminated metal plate according to another aspect of the present disclosure includes: a step of irradiating a raw plate of a laminated metal plate including a base metal plate and a resin coating film covering one or both surfaces of the base metal plate with a far-infrared laser to deteriorate the resin coating film in an irradiation area; and a step of irradiating an area where the resin coating film is deteriorated with an ultraviolet laser and / or a near-infrared laser to remove the resin coating film in a manner that the base metal plate is exposed, and the thickness of the resin coating film remaining in the irradiation area after the step of deteriorating the resin coating film is less than 17 μm.

[0023] (11) Preferably, in the method for manufacturing a laminated metal plate described in the above (10), the resin coating film has a polyolefin resin as a main component.

[0024] (12) Preferably, in the method for manufacturing a laminated metal plate described in the above (11), the resin coating film has a polypropylene resin as a main component.

[0025] (13) The manufacturing method of the laminated metal sheet according to any one of (10) to (12), preferably wherein, in the step of removing the resin coating film, the resin coating film is removed by the near-infrared laser.

[0026] (14) The manufacturing method of the laminated metal sheet according to any one of (10) to (13), preferably wherein the wavelength of the far-infrared laser is 9.2 to 10.8 μm.

[0027] (15) The manufacturing method of the laminated metal sheet according to any one of (10) to (14), preferably wherein the wavelength of the ultraviolet laser is 0.24 to 0.40 μm.

[0028] (16) The manufacturing method of the laminated metal sheet according to any one of (10) to (15), preferably wherein the wavelength of the near-infrared laser is 0.79 to 1.09 μm.

[0029] (17) The manufacturing method of the laminated metal sheet according to any one of (10) to (16), preferably wherein the thickness of the resin coating film is 18.0 μm or more.

[0030] (18) The manufacturing method of the laminated metal sheet according to any one of (10) to (17), preferably wherein the resin coating film is removed along the end portion of the base metal sheet.

[0031] (19) The manufacturing method of the laminated metal sheet according to any one of (10) to (18), preferably wherein the base metal sheet is a steel sheet.

[0032] (20) The manufacturing method of a welded product according to another aspect of the present disclosure includes a step of welding a laminated metal sheet obtained by the manufacturing method of the laminated metal sheet according to any one of (10) to (19) to a material to be welded, and welding a region from which the resin coating film is removed.

[0033] (21) The manufacturing method of a battery cell according to another aspect of the present disclosure includes the manufacturing method of a welded product according to (20).

[0034] Effects of Invention According to the present disclosure, it is possible to provide a manufacturing method of a laminated metal sheet, a manufacturing method of a welded product, and a manufacturing method of a battery cell, in which a resin coating film of a laminated metal sheet is easily removed to expose a base metal sheet, and a laminated metal sheet, a welded product, and a battery cell. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic view of a manufacturing method of a laminated metal sheet according to the present disclosure.

[0036] Figure 2is a schematic view of a manufacturing method of a laminated metal plate irradiated with only far infrared laser light.

[0037] Figure 3 is a schematic view of a manufacturing method of a laminated metal plate irradiated with only ultraviolet laser light and / or near infrared laser light.

[0038] Figure 4 is a cross-sectional schematic view of an exposed portion in a laminated metal plate of the present disclosure.

[0039] Figure 5 is a cross-sectional photograph of an exposed portion in an example of a laminated metal plate of the present disclosure.

[0040] Figure 6 is a cross-sectional schematic view of an exposed portion of a laminated metal plate from which a resin coating has been removed by mechanical means.

[0041] Figure 7 is a plan view of an example of a laminated metal plate of the present disclosure.

[0042] Figure 8 is a schematic view of another example of a laminated metal plate of the present disclosure.

[0043] Figure 9A is a surface photograph of a laminated metal plate irradiated with various laser lights.

[0044] Figure 9B is an explanatory view of a photograph. Figure 9A

[0045] Figure 10A is a cross-sectional photograph of a region A that has not been subjected to laser irradiation.

[0046] Figure 10B is a cross-sectional photograph of a region B irradiated with only CO2 laser light.

[0047] Figure 10C is a cross-sectional photograph of a region C irradiated with ultraviolet laser light after irradiation with CO2 laser light.

[0048] Figure 10D is a cross-sectional photograph of a region D irradiated with only ultraviolet laser light.

[0049] Figure 11 is a comparison view in which cross-sectional photographs of regions A to D are arranged. DETAILED DESCRIPTION

[0050] (1. Manufacturing method of laminated metal plate 1) The manufacturing method of a laminated metal plate 1 of one embodiment of the present disclosure is intended to provide a laminated metal plate 1 having an exposed portion 13 in which a base metal plate 11 is exposed, as exemplified in Figure 1 the following process: ​(S1) irradiating the original plate of the laminated metal plate 1 with far-infrared laser light L1 so as to deteriorate the resin film 12 in the irradiation region; and (S2) removing the resin film 12 so as to expose the base metal plate 11 by irradiating the region where the resin film 12 has been deteriorated with ultraviolet laser light and / or near-infrared laser light L2.

[0051] (original plate) In the manufacturing method of the laminated metal plate 1 of one embodiment of the present disclosure, first, an original plate of the laminated metal plate 1 is prepared. The original plate of the laminated metal plate 1 includes the base metal plate 11 and the resin film 12 covering one or both surfaces of the base metal plate 11. The resin film 12 of the original plate covers the entire one or both surfaces of the base metal plate 11 of the original plate. The original plate has the same structure as the laminated metal plate 1 finally obtained, except that the original plate does not have the exposed portion 13. A commercially available general laminated metal plate 1 can be used as the original plate.

[0052] (S1 irradiation of far-infrared laser light L1) Next, the original plate is irradiated with far-infrared laser light L1. In this embodiment, the far-infrared laser light L1 refers to laser light in a wavelength region that is directly converted into vibration energy or rotational energy of molecules or atoms without being converted into other forms of energy when absorbed by a substance or the like. The far-infrared laser light L1 is, for example, CO2 laser light. The far-infrared laser light L1 can be continuously irradiated or intermittently irradiated.

[0053] In the manufacturing method of the laminated metal plate 1 of this embodiment, the resin film 12 is deteriorated by irradiation with the far-infrared laser light L1. Deterioration of the resin film 12 refers to a physical or chemical change in the state of the resin film 12 from the original state. Removal of the resin film 12 from the original plate of the laminated metal plate 1 due to deterioration of the resin film 12 is also included in "deterioration of the resin film 12". That is, part or all of the resin film 12 at the irradiation site can be removed from the laminated metal plate 1 by irradiation with the far-infrared laser light L1. However, in the manufacturing method of the laminated metal plate 1 of this embodiment, irradiation with the far-infrared laser light L1 is performed so that the resin film 12 is deteriorated in some way.

[0054] The thickness of the resin film 12 remaining after irradiation with the far-infrared laser light L1 is less than 17 μm. If the thickness of the resin film 12 remaining after irradiation with the far-infrared laser light L1 is less than 17 μm, the remaining resin film 12 can be easily removed from the original plate by irradiation with the ultraviolet laser light and / or near-infrared laser light L2 in the next step.

[0055] (S2 irradiation of ultraviolet laser light and / or near-infrared laser light L2) In the manufacturing method of the laminated metal sheet 1 of this embodiment, the area where the resin film 12 has been deteriorated by irradiation with far-infrared laser L1 is further irradiated with ultraviolet laser and / or near-infrared laser L2. Ultraviolet laser refers to laser with a wavelength shorter than that of visible radiation. Near-infrared laser refers to laser with a wavelength adjacent to the visible region that may produce photochemical effects when absorbed by matter. The ultraviolet laser and / or near-infrared laser L2 can be used for continuous or intermittent irradiation.

[0056] In the manufacturing method of the laminated metal sheet 1 of this embodiment, the resin film 12 is removed from the original sheet by irradiation with an ultraviolet laser and / or a near-infrared laser L2. This forms the exposed portion 13 of the base metal sheet 11. It should be noted that the concept of "removal of the resin film 12" includes not only completely separating the resin film 12 from the laminated metal sheet 1, but also deteriorating the resin film 12 so that it can be easily separated from the laminated metal sheet 1 by simple means such as blowing air.

[0057] (Effects) In the manufacturing method of the laminated metal sheet 1 of this embodiment, a far-infrared laser L1 is combined with an ultraviolet laser and / or a near-infrared laser L2. This allows for easy removal of the resin coating 12 from the original sheet. The inventors speculate the following reasons for achieving this effect.

[0058] like Figure 2 As shown, the far-infrared laser L1 sometimes fails to degrade the resin film 12 to a degree that allows it to be removed. The far-infrared laser L1 can heat the resin film 12, reducing its thickness. However, when the resin film 12 thins due to irradiation by the far-infrared laser L1, the far-infrared laser becomes difficult for the resin film 12 to absorb. As a result, the deterioration of the resin film 12 caused by irradiation by the far-infrared laser L1 does not progress.

[0059] This tendency is particularly evident in polypropylene films. According to experimental results from the present invention, irradiation with far-infrared laser L1 reduces the thickness of the polypropylene film. However, the thinned polypropylene film adheres firmly to the substrate metal plate 11. The polypropylene film irradiated only with far-infrared laser L1 cannot be removed without the use of powerful mechanical processing methods such as grinding tools.

[0060] like Figure 3As shown, the ultraviolet laser and the near-infrared laser L2 sometimes cannot individually deteriorate the resin film 12 to the extent that the resin film 12 can be removed. According to the inventors' experimental results, the ultraviolet laser and the near-infrared laser L2 can cause the resin film 12 to be peeled from the base metal plate 11. However, the ultraviolet laser and the near-infrared laser L2 sometimes cannot cause the resin film 12 that has been irradiated with the laser to separate from the resin film 12 around it that has not been irradiated with the laser. In addition, the energy of the ultraviolet laser and the near-infrared laser L2 is easily absorbed by the base metal plate 11. Therefore, in the case of increasing the ultraviolet laser and the near-infrared laser L2, the base metal plate 11 sometimes melts before the resin film 12 is sufficiently deteriorated.

[0061] This tendency is particularly noticeable in polypropylene films. According to the inventors' experimental results, the polypropylene film that has been irradiated with the ultraviolet laser or the near-infrared laser L2 is peeled from the base metal plate 11. However, the polypropylene film that has been peeled from the base metal plate 11 is firmly connected to the polypropylene film around it. The peeled polypropylene film cannot be removed without using a strong mechanical processing means such as a grinding tool.

[0062] However, the inventors have found that, as shown in FIG. 1, first, the resin film 12 is irradiated with the far-infrared laser L1, and then the resin film 12 is irradiated with the ultraviolet laser and / or the near-infrared laser L2, whereby the resin film 12 is significantly deteriorated and can be easily removed from the original plate. Figure 1 As shown, first, the resin film 12 is irradiated with the far-infrared laser L1, and then the resin film 12 is irradiated with the ultraviolet laser and / or the near-infrared laser L2, whereby the resin film 12 is significantly deteriorated and can be easily removed from the original plate. The inventors speculate that, by irradiating the ultraviolet laser and / or the near-infrared laser L2 in a state where the resin film 12 has been thinned by the far-infrared laser L1, the resin film 12 that has been peeled from the base metal plate 11 easily separates from the resin film 12 around it.

[0063] (2. Laminated metal plate 1) The laminated metal plate 1 of another aspect of the present disclosure includes a base metal plate 11 and a resin film 12 that covers one or both surfaces of the base metal plate 11, wherein a part of the surface of the laminated metal plate 1 on which the resin film 12 is provided is provided with an exposed portion 13 in which the base metal plate 11 is exposed, and the resin film 12 has a main portion 121 and a transition portion 122 that is provided around the exposed portion 13, in the main portion 121, the interface between the base metal plate 11 and the resin film 12 is substantially parallel to the surface of the resin film 12, in the transition portion 122, the surface of the resin film 12 is inclined from the surface of the resin film 12 in the main portion 121 toward the surface of the base metal plate 11 in the exposed portion 13, and the area of the surface of the base metal plate 11 in which the transition portion 122 is arranged is continuously connected to the area in which the exposed portion 13 is arranged.

[0064] The laminated metal sheet 1 of the present embodiment has a base metal sheet 11 and a resin coating 12 that covers one or both surfaces of the base metal sheet 11. The resin coating 12 of the laminated metal sheet 1 covers one or both surfaces of the base metal sheet 11 of the laminated metal sheet 1. Of these, a portion of the resin coating 12 is removed from the laminated metal sheet 1. The area where the resin coating 12 is removed to expose the base metal sheet 11 is an exposed portion 13.

[0065] (Morphology of the resin coating 12 around the exposed portion 13) The resin coating 12 of the laminated metal sheet 1 of the present embodiment has a unique shape around the exposed portion 13. As shown in Figure 4 , the resin coating 12 is divided into a main portion 121 and a transition portion 122 provided around the exposed portion 13.

[0066] In the main portion 121, the interface between the base metal sheet 11 and the resin coating 12 is substantially parallel to the surface of the resin coating 12. That is, the thickness of the resin coating 12 in the main portion 121 is substantially constant. The resin coating 12 in the main portion 121 is the same as the resin coating 12 of the laminated metal sheet 1 before the removal of the resin coating 12 (i.e., the aforementioned original sheet).

[0067] In the transition portion 122, unlike the main portion 121, the interface between the base metal sheet 11 and the resin coating 12 is not substantially parallel to the surface of the resin coating 12. In the transition portion 122, the surface of the resin coating 12 is inclined from the surface of the resin coating 12 in the main portion 121 toward the surface of the base metal sheet 11 in the exposed portion 13. That is, the thickness of the resin coating 12 at the transition portion 122 decreases as it approaches the exposed portion 13. The transition portion 122 separates the main portion 121 from the exposed portion 13. The transition portion 122 is generated by removing the resin coating 12 using a laser.

[0068] Figure 5 A cross-sectional photograph of the exposed portion 13 and its vicinity formed by first irradiating the resin coating 12 with a far-infrared laser L1 and then irradiating the resin coating 12 with an ultraviolet laser and / or a near-infrared laser L2 is shown in Figure 5 is a photograph obtained by cutting the laminated metal sheet 1 at the exposed portion 13 of the laminated metal sheet 1 in a plane perpendicular to the direction in which the exposed portion 13 extends, then embedding the laminated metal sheet 1 in a cross-sectional observation resin 2, polishing the cut surface of the laminated metal sheet 1, and then photographing the cut surface using an optical microscope. When the photograph is taken, the angle and intensity of the illumination are optimized so that the interface between the cross-sectional observation resin 2 in which the laminated metal sheet 1 is embedded and the resin coating 12 of the laminated metal sheet 1 becomes clear. As a result, in Figure 5 , the cross section of the base metal sheet 11 becomes white.

[0069] As shown in Figure 4 andFigure 5 As shown, the transition portion 122 is formed around the exposed portion 13 formed using laser light. In addition, the region of the surface of the base metal plate 11 in which the transition portion 122 is disposed is continuously connected to the region in which the exposed portion 13 is disposed. Specifically, in the surface of the base metal plate 11, there is no difference in height between the region in which the transition portion 122 is disposed and the region in which the exposed portion 13 is disposed, and the surface of the base metal plate 11 is flatly connected in the region in which the transition portion 122 is disposed and the region in which the exposed portion 13 is disposed. If the surface of the base metal plate 11 of the original plate in the laser light irradiation portion is flat, the surface of the base metal plate 11 also becomes flat in the exposed portion 13 formed using laser light. In addition, even in the case where the surface of the base metal plate 11 is not flat due to reasons such as bending processing of the base metal plate 11, in the exposed portion 13 formed using laser light, no concavo-convex (for example, cutting marks) provided by mechanical processing is generated.

[0070] On the other hand, as shown in FIG. 2, the transition portion 122 is not formed around the exposed portion 13 formed by mechanical processing such as grinding. Figure 6 As shown, the transition portion 122 is not formed around the exposed portion 13 formed by mechanical processing such as grinding. In addition, in the case where the resin film 12 is removed by mechanical processing, the surface layer of the base metal plate 11 is also removed to some extent. Therefore, in the exposed portion 13 formed by mechanical processing, a recess is formed in the surface of the base metal plate 11.

[0071] In the laminated metal plate 1 in which the transition portion 122 is provided around the exposed portion 13 and the region of the surface of the base metal plate 11 in which the transition portion 122 is disposed is continuously connected to the region in which the exposed portion 13 is disposed, the exposed portion 13 is highly likely to be formed by irradiation of laser light. Therefore, the laminated metal plate 1 in which the transition portion 122 is provided around the exposed portion 13 can be easily manufactured.

[0072] The above describes the most basic mode of the laminated metal plate 1 and the manufacturing method thereof according to the present embodiment. Hereinafter, a more preferable mode of the laminated metal plate 1 and the manufacturing method thereof according to the present embodiment is described. The mode described hereinafter can be applied to both the laminated metal plate 1 and the manufacturing method thereof, unless specifically described.

[0073] (Kinds of resin film 12) It is preferable that the resin film 12 have a polyolefin-based resin as a main component. It is particularly preferable that the resin film 12 have a polypropylene-based resin as a main component. The polyolefin-based resin and the polypropylene-based resin have excellent corrosion resistance. In addition, the polyolefin-based resin and the polypropylene-based resin are easily laminated to the surface of a metal plate. By making the resin film 12 a polyolefin-based resin or a polypropylene-based resin, it is possible to improve the corrosion resistance of the laminated metal plate 1 and to easily manufacture the laminated metal plate 1.

[0074] (Thickness of resin film 12) The thickness of the resin coating film 12 is not particularly limited. In order to improve the corrosion resistance of the laminated metal plate 1, it is preferable that the thickness of the resin coating film 12 be large. For example, the thickness of the resin coating film 12 of the original plate and / or the thickness of the resin coating film 12 in the main body portion 121 of the laminated metal plate 1 is preferably 18.0 μm or more, 20.0 μm or more, or 30.0 μm or more.

[0075] Note that thick polyolefin-based resins and polypropylene-based resins are difficult to remove using a laser. In the related art, thick polyolefin-based resins and polypropylene-based resins are removed by mechanical means such as grinding. However, in the manufacturing method of the laminated metal plate 1 of the present embodiment, by using a far infrared laser LI and an ultraviolet laser and / or a near infrared laser L2 in combination, thick polyolefin-based resins and polypropylene-based resins can be easily removed from the original plate, and the exposed portion 13 is formed.

[0076] (Shape of the exposed portion 13 in plan view) The shape of the exposed portion 13 in plan view is not particularly limited. The shape of the exposed portion 13 can be adopted that is suitable for the use of the laminated metal plate 1 and the use of the exposed portion 13.

[0077] For example, in the case where the laminated metal plate 1 is used as a material for a battery cell of a lithium ion battery or a solid-state battery, the exposed portion 13 is preferably provided with a belt-like shape extending along the end portion of the laminated metal plate 1, as exemplified in Figure 7 In addition, in the manufacturing of the laminated metal plate 1, it is preferable that the resin coating film 12 be removed along the end portion of the original plate, and thus the exposed portion 13 having a belt-like shape extending along the end portion of the laminated metal plate 1 is formed. By overlapping Figure 7 two or more of the laminated metal plate 1 exemplified in

[0078] (Coverage of the resin coating film 12 with respect to the laminated metal plate 1) The coverage of the resin coating film 12 with respect to the laminated metal plate 1 is not particularly limited. It can be appropriately set in accordance with the size and shape of the laminated metal plate 1 and the size and shape of the exposed portion 13. In order to improve the corrosion resistance of the laminated metal plate 1, it is preferable that the coverage of the resin coating film 12 with respect to the laminated metal plate 1 be large. For example, the coverage of the resin coating film 12 with respect to the laminated metal plate 1 is preferably 50% or more, 70% or more, or 90% or more.

[0079] The coverage of the resin coating film 12 with respect to the laminated metal plate 1 indicates the proportion of the area of the resin coating film 12 of each face of the laminated metal plate 1 after laser irradiation, with respect to the area of each face of the original plate, which is assumed to be 100%.

[0080] In the case where the laminated metal plate 1 is used as a material of a battery cell, the interval between the exposed portion 13 and the end portion of the laminated metal plate 1 is preferably set to more than 0 mm and 15 mm or less. The smaller the interval between the exposed portion 13 and the end portion of the laminated metal plate 1, the more the capacity of the battery cell can be increased, and the weight of the battery cell can be reduced. In addition, in the case where the laminated metal plate 1 is used as a material of a battery cell, the exposed portion 13 is preferably continuously extended along the end portion of the laminated metal plate 1. However, in order to arrange an electrode in the battery cell, a part of the end portion of the laminated metal plate 1 is not welded. Therefore, it is preferable that the exposed portion 13 is not provided in the part of the end portion of the laminated metal plate 1. The width of the exposed portion 13 is, for example, preferably 1.5 to 15 mm.

[0081] In the case where the laminated metal plate 1 is used as a side wall of a can, the laminated metal plate 1 is set to a rectangular shape. As Figure 8 illustrated, the laminated metal plate 1 is rounded, and the two opposite end portions of the laminated metal plate 1 are seam-welded. Thereby, the laminated metal plate 1 becomes a cylindrical shape. By providing the strip-shaped exposed portion 13 extending along the two end portions of the laminated metal plate 1 which are parallel to each other, and lap-welding the exposed portion 13, a bead without a welding defect can be formed. Note that, in the example shown in Figure 8 , both surfaces of the base metal plate 11 are covered with the resin film 12. Therefore, the strip-shaped exposed portion 13 is provided on both surfaces of the laminated metal plate 1. In Figure 8 , only the exposed portion 13 of the outer side surface of the laminated metal plate 1 is illustrated, but the exposed portion 13 of the inner side surface is also provided at the same position as the exposed portion 13 of the outer side surface.

[0082] (Wavelength of laser light) In the manufacturing method of the laminated metal plate 1, the wavelength of the far infrared laser light LI is not limited, and is, for example, preferably 9.2 to 10.8 μm. The wavelength of the ultraviolet laser light and the near infrared laser light L2 is also not particularly limited, and, for example, the ultraviolet laser light is preferably 0.24 to 0.40 μm, and the near infrared laser light is preferably 0.79 to 1.09 μm. According to the experimental results of the present inventors, the laser light having the above-described wavelength is most suitable for removing the resin film 12 in which a polypropylene-based resin is a main component. As examples of the near infrared laser light, there are a fiber laser, a disc laser, and a semiconductor laser. In addition, the irradiation conditions of the laser light other than the wavelength can be appropriately set according to the kind and thickness of the resin film 12.

[0083] (Shape of transition portion 122) The shape of the transition portion 122 of the resin coating 12 is not particularly limited as long as the surface of the resin coating 12 is inclined from the surface of the resin coating 12 in the main portion 121 toward the surface of the base metal plate 11 in the exposed portion 13. The shape of the transition portion 122 varies depending on the irradiation conditions of the laser at the time of forming the exposed portion 13. For example, the angle between the surface of the base metal plate 11 and the surface of the resin coating is preferably 5 to 70 degrees. Thereby, the resin coating 12 can be more easily removed.

[0084] (Kinds of base metal plate 11) The kind of the base metal plate 11 is not particularly limited. As preferable examples of the base metal plate 11, there can be mentioned steel plates, aluminum plates, titanium plates, and stainless steel plates. The base metal plate 11 can also be a plated steel plate. As preferable examples of the plated steel plate, there can be mentioned zinc-plated steel plates, aluminum-plated steel plates, nickel-plated steel plates, and steel plates subjected to chromate treatment.

[0085] (3. Welded product) (4. Battery cell) (5. Method for manufacturing welded product) (6. Method for manufacturing battery cell) The welded product of another aspect of the present disclosure has the laminated metal plate 1 of the present embodiment, a welded material joined to the laminated metal plate 1, and a welded portion provided to the exposed portion 13 of the laminated metal plate 1 to join the laminated metal plate 1 and the welded material. The battery cell of another aspect of the present disclosure has the welded product of the present embodiment. The method for manufacturing the welded product of another aspect of the present disclosure has a step of welding the laminated metal plate 1 obtained by the method for manufacturing the laminated metal plate 1 of the present embodiment and a welded material, and the welding is performed on the region from which the resin coating 12 is removed. The method for manufacturing the battery cell of another aspect of the present disclosure has the method for manufacturing the welded product of the present embodiment.

[0086] The kind of the welded product is not particularly limited. Various products manufactured using the laminated metal plate 1 as a material can be the welded product of the present embodiment. Preferable examples of the welded product are battery cells, barrels, beverage cans, roofs and walls of buildings, heat exchangers, cooling devices of electric vehicles, and the like.

[0087] The welded material can be any material that can be welded to the base metal plate 11 of the laminated metal plate 1. The welded material can also be the laminated metal plate 1. In the case where the welded material is the laminated metal plate 1, that is, in the case where two laminated metal plates 1 are joined to manufacture a welded product, it is preferable that the exposed portion 13 is provided to each of the two laminated metal plates 1, and the welding is performed by overlapping these exposed portions 13.

[0088] Note that, when the laminated metal plate 1 is welded with the material to be welded, it is preferable that the molten metal not come into contact with the resin coating 12. In the welded product, it is preferable that the welding metal formed by solidification of the molten metal be isolated from the resin coating 12. When the cross section of the welded portion of such a welded product is observed, in the vicinity of the welding metal, it is possible to confirm the presence of: (1) a portion where no resin is attached (corresponding to the exposed portion 13 of the laminated metal plate) that is present adjacent to the welding metal, (2) a portion where a small amount of resin is attached (corresponding to the transition portion 122 of the resin coating 12 of the laminated metal plate 1) that is present adjacent to the portion of (1) above, and (3) a portion where a larger amount of resin is attached (corresponding to the main portion 121 of the resin coating 12 of the laminated metal plate 1) that is present adjacent to the portion of (2) above In the case where the resin coating 12 is sandwiched between the laminated metal plate 1 and the material to be welded, in the portion of (2) above, a gap is generated between the laminated metal plate 1 and the material to be welded, on the other hand, in the portion of (3) above, no gap is generated between the laminated metal plate 1 and the material to be welded. A welded product having the portions of (1), (2), and (3) above is considered to be the welded product of the present embodiment.

[0089] The laminated metal plate 1 of the related art is mostly joined by heat fusion bonding. However, the fusion bonding portion sometimes has low liquid tightness. For example, in the case where the welded product is a battery cell, sometimes moisture intrudes into the inside of the battery cell through the fusion bonding portion, and the battery cell deteriorates. However, in the welded product and the method of manufacturing the same of the present embodiment, the joining portion is the welding portion. By the welding portion, it is possible to prevent the intrusion of moisture into the inside of the welded product. In addition, in the welded product and the method of manufacturing the same of the present embodiment, the welding portion is provided as the exposed portion 13, and the resin coating 12 does not affect the welding. The exposed portion 13 can suppress the generation of welding defects in the weld of the welding portion. In addition, in the case of a battery, the laminated metal plates are surface joined to each other by heat fusion bonding, and furthermore, in the exposed portion in the vicinity thereof, a joint structure of laser welding that uses a lap joint or a fillet joint or a crimp joint structure is formed, and thus it is possible to more effectively suppress the intrusion of moisture. Note that, by heat conduction at the time of laser welding, a fusion bonding portion is formed in the joining surface of the laminated metal plates that is apart from the laser welding portion, and thus it is possible to obtain a joint structure that has no welding defects and that has a high moisture intrusion prevention function that uses fusion bonding.

[0090] Example The effects of one embodiment of the present disclosure are more specifically described through examples. However, the conditions in the examples are merely one example of conditions that are adopted in order to confirm the implementation possibility and effects of the present disclosure. The present disclosure is not limited to this one example of conditions. Various conditions can be adopted as long as the present disclosure is implemented without deviating from the gist of the present disclosure and achieving the object of the present disclosure.

[0091] (Experiment A) A raw sheet having a base metal sheet and a resin film covering one surface of the base metal sheet was used as a test sample. The base metal sheet was a tin-free steel having a sheet thickness of 0.3 mm. The resin film was a polypropylene film (PP) or a polyethylene terephthalate film (PET). The kind and thickness of the resin film possessed by the test sample are described in Table 1.

[0092] The resin film of each test sample was attempted to be removed by the removal method described in Table 1. As for the test sample to which two kinds of laser light were irradiated, the laser light of the first irradiation (S1) and the laser light of the second irradiation (S2) are described in the column of "Removal method" in Table 1, respectively. As for the other test samples, the method of removing the resin film is also described in the column of "Removal method" in Table 1.

[0093] The irradiation conditions of the laser light described in Table 1 were basically as follows. However, as for the laser light irradiated to a part of the test samples, a part of the irradiation conditions was changed, and the output power and the number of irradiations in the changed case are described in the column of "Removal method" in Table 1. The "number of repetitions" means the number of irradiations.

[0094] Irradiation conditions of CO2 laser (far infrared laser) • Wavelength: 9.4 μm • Focal diameter: 0.5 mm • Output power: 360 W • Pulse frequency: 10 kHz • Scanning speed: 1000 to 4000 mm / S • Number of repetitions: 1 to 4 times • Electric scanner processing range: 5 mm width Irradiation conditions of fiber laser (near infrared laser) • Wavelength: 1.07 μm • Focal diameter: 0.68 mm • Output power: 500 W • Pulse frequency: 60 kHz • Scanning speed: 3000 to 9000 mm / S • Number of repetitions: 1 time • Electric scanner processing range: 5 mm width Irradiation conditions of ultraviolet laser • Wavelength: 0.355 μm • Focal diameter: 38 μm • Output power: 6 W • Pulse frequency: 10 kHz • Scanning speed: 800 to 2000 mm / S • Number of repetitions: 1 to 4 times • Processing range of electric scanner: 5 mm width After the resin coating was removed, the sample was observed to confirm whether the exposed portion was formed. As for the sample in which the resin coating was removed and the base metal plate was exposed, and the sample in which the resin coating was sufficiently deteriorated and the base metal plate was exposed by the tester by air injection to remove the resin coating, it was recorded as "pass" in the "coating removal result" column of Table 1. As for the sample in which the base metal plate was not removed and the tester could not remove the resin coating by air injection, it was recorded as "fail" in the "coating removal result" column of Table 1.

[0095] In addition, as for the sample in which the coating removal result was "pass", it was confirmed whether the inclined portion was formed in the vicinity of the exposed portion in the resin coating. The sample was resin-embedded, the sample was cut perpendicularly in the extension direction of the exposed portion, the cross section was polished and observed under a microscope, whereby the inclined portion was brought to a state that could be visually recognized. Figure 5 The sample in which the transition portion was confirmed to be formed was judged to be a sample in which the inclined portion was formed, and was recorded as "yes" in the "inclined portion" column of Table 1. As for the sample judged not to form the inclined portion, it was recorded as "no" in the "inclined portion" column of Table 1.

[0096] In the sample in which the resin coating was first irradiated with far infrared laser light (CO2 laser light) and then irradiated with ultraviolet laser light and / or near infrared laser light (fiber laser light), the resin coating could be easily removed to form the exposed portion. The cross section of the exposed portion of these samples was observed, and as a result, the inclined portion was formed. In addition, the surface of the base metal plate of these samples was not deformed and was flat.

[0097] In Examples 6, 10, 12, 13, and 14, the sample was irradiated with far infrared laser light, but not with ultraviolet laser light and / or near infrared laser light. In the samples of Examples 6, 10, and 12, the thickness of the resin coating was reduced, but the resin coating could not be deteriorated to the extent that it could be easily separated from the base metal plate by air. In Example 13, the number of times of irradiation with far infrared laser light was increased compared to the other examples, but the resin coating could not be deteriorated to the extent that it could be easily separated from the base metal plate by air. In Example 14, the output power of the far infrared laser light was increased compared to the other examples, but as a result, the base metal plate was melted.

[0098] In Example 7, the resin film was first irradiated with the fiber laser, and then the resin film was irradiated with the ultraviolet laser. In Example 9, the resin film was first irradiated with the ultraviolet laser, and then the resin film was irradiated with the fiber laser. In Example 11, the resin film was irradiated only with the fiber laser. That is, in Example 7, Example 9, and Example 11, the sample was not irradiated with the far infrared laser. In the samples of Example 7, Example 9, and Example 11, the resin film was peeled from the base metal plate, but the resin film could not be deteriorated to a degree that the resin film could be easily separated from the base metal plate by air.

[0099] In Example 8, the resin film was first irradiated with the ultraviolet laser, and then the resin film was irradiated with the far infrared laser. In the sample of Example 8, the resin film could not be completely removed as a result.

[0100] In Example 17, the resin film was mechanically cut. Thus, in Example 17, the resin film could be removed to form the exposed portion. However, in Example 17, the concave-convex was formed on the surface of the base metal plate. In Example 17, it was possible that the strength of the base metal plate was damaged. In addition, in Example 17, the inclined portion was not formed around the exposed portion.

[0101] In Example 18, the output power of the CO2 laser was set to 120 W, and the number of irradiations was set to one time. Thus, after the CO2 laser irradiation, the thickness of the resin film remaining in the portion irradiated with the CO2 laser was 17 μm or more. In Example 18, the resin film could not be removed from the original plate by the irradiation of the fiber laser, and the exposed portion could not be formed.

[0102] In Example 19, the output power of the CO2 laser was set to 360 W, and the number of irradiations was set to three times. Thus, after the CO2 laser irradiation, the thickness of the resin film remaining in the portion irradiated with the CO2 laser was less than 17 μm. In Example 19, the resin film remaining by the irradiation of the fiber laser could be removed from the original plate to form the exposed portion.

[0103] (Experiment B) One or both of a CO2 laser and an ultraviolet laser was irradiated to a tin-free steel plate having a thickness of 0.3 mm, which was covered with a polypropylene film having a thickness of 150 μm. The irradiation conditions were as follows.

[0104] Irradiation conditions of the CO2 laser (far infrared laser) • Wavelength: 9.4 μm • Pulse width: 5.6 μs • Repetition: 10 kHz • Average output power: 400 W (on WORK) • fθ lens focal length: 482 mm • Condensing diameter: 494 μm • Electric scanner processing range: 4 mm width Irradiation conditions of the ultraviolet laser • Wavelength: 0.355 μm • Pulse width: 20 ns • Repetition: 50 kHz • Average output power: 6 W (on WORK) • fθ lens focal length: 250 mm • Condensing diameter: 38 μm • Electric scanner processing range: 4 mm width A photograph of the resin coating 12 after irradiation is shown in Figure 9A . Figure 9B An explanatory diagram showing a photograph of Figure 9A is shown. The area marked with the symbol A in Figure 9B is an area where no laser irradiation was performed. The area marked with the symbol B is an area where only CO2laser irradiation was performed. The area marked with the symbol C is an area where ultraviolet laser irradiation was performed after CO2laser irradiation. The area marked with the reference numeral D is an area where only ultraviolet laser irradiation was performed. After a photograph of Figure 9A was taken, the sample was cut along the single-dot line described in Figure 9B , embedded in the resin for cross-sectional observation 2, and polished. Then, the cross section of the sample was observed.

[0105] Figure 10A is a cross-sectional photograph of the area A where no laser irradiation was performed. Figure 10B is a cross-sectional photograph of the area B where only CO2laser irradiation was performed. Figure 10C is a cross-sectional photograph of the area C where ultraviolet laser irradiation was performed after CO2laser irradiation. Figure 10D is a cross-sectional photograph of the area D where only ultraviolet laser irradiation was performed. Note that the resin for cross-sectional observation 2 in which the sample is embedded is photographed above Figure 10A to Figure 10D . Figure 11 is a comparison diagram of the cross-sectional photographs of the areas A to D.

[0106] In the area B where only CO2laser irradiation was performed shown in Figure 10B , the resin coating 12 is thinned, but remains on the surface of the base metal plate 11. In the area D where only ultraviolet laser irradiation was performed shown in Figure 10D , the resin coating 12 is peeled from the base metal plate 11. As a result, when the sample for cross-sectional observation is prepared, the resin for cross-sectional observation 2 intrudes between the resin coating 12 and the base metal plate 11.

[0107] On the other hand, in the area C where ultraviolet laser irradiation was performed after CO2laser irradiation shown in Figure 10CIn the region C shown as having been irradiated with the ultraviolet laser after the CO2laser, the resin film 12 is peeled off, and an exposed portion 13 in which the base metal plate 11 is exposed can be formed.

[0108] Explanation of Reference Numerals 1 Laminated Metal Plate 11 Base Metal Plate 12 Resin Film 121 Main Body Portion 122 Transition Portion 13 Exposed Portion L1 Far Infrared Laser L2 Ultraviolet Laser and / or Near Infrared Laser 2 Resin for Cross-Section Observation A Region Not Irradiated with Laser B Region Irradiated with CO2 Laser Only C Region Irradiated with Ultraviolet Laser after Irradiation with CO2 Laser D Region Irradiated with Ultraviolet Laser Only

Claims

1. A laminated metal sheet, comprising: base metal plate, and A resin film covering one or both surfaces of the substrate metal plate. in, A portion of the surface of the laminated metal plate on which the resin film is disposed has an exposed portion of the base metal plate. The resin film has a main body and a transition portion disposed around the exposed portion. In the main body, the interface between the base metal plate and the resin film is substantially parallel to the surface of the resin film. In the transition section, the surface of the resin film slopes from the surface of the resin film in the main body section toward the surface of the base metal plate in the exposed section. The region on the surface of the base metal plate in which the transition portion is disposed and the region in which the exposed portion is disposed are continuously connected.

2. The laminated metal sheet according to claim 1, characterized in that, The resin coating is mainly composed of polyolefin resin.

3. The laminated metal sheet according to claim 2, characterized in that, The resin coating is mainly composed of polypropylene resin.

4. The laminated metal sheet according to claim 1, characterized in that, The thickness of the resin film in the main body is 18.0 μm or more.

5. The laminated metal sheet according to claim 1, characterized in that, The exposed portion has a strip-like shape extending along the end of the laminated metal plate.

6. The laminated metal sheet according to claim 1, characterized in that, In the transition section, the angle between the surface of the base metal plate and the surface of the resin film is 5 to 70 degrees.

7. The laminated metal sheet according to claim 1, characterized in that, The base metal plate is a steel plate.

8. A welded article, comprising: Laminated metal sheet according to any one of claims 1 to 7; The material being welded, which is bonded to the laminated metal plate; and A welding section, which is provided at the exposed portion of the laminated metal plate, joins the laminated metal plate and the material to be welded.

9. A battery cell comprising the welded article of claim 8.

10. A method for manufacturing a laminated metal sheet, characterized in that, It has the following processes: A process of irradiating a base metal plate having a substrate metal plate and a resin film covering one or both surfaces of the substrate metal plate with a far-infrared laser, thereby degrading the resin film in the irradiated area; and The process of removing the resin coating by irradiating the area where the resin coating has deteriorated with ultraviolet laser and / or near-infrared laser to expose the substrate metal plate. After the process of degrading the resin film, the thickness of the resin film remaining in the irradiated area is less than 17 μm.

11. The method for manufacturing a laminated metal sheet according to claim 10, characterized in that, The resin coating is mainly composed of polyolefin resin.

12. The method for manufacturing a laminated metal sheet according to claim 11, characterized in that, The resin coating is mainly composed of polypropylene resin.

13. The method for manufacturing a laminated metal sheet according to claim 10, characterized in that, In the process of removing the resin coating, the near-infrared laser is used to remove the resin coating.

14. The method for manufacturing a laminated metal sheet according to claim 10, characterized in that, The wavelength of the far-infrared laser is 9.2~10.8μm.

15. The method for manufacturing a laminated metal sheet according to claim 10, characterized in that, The wavelength of the ultraviolet laser is 0.24~0.40μm.

16. The method for manufacturing a laminated metal sheet according to claim 10, characterized in that, The wavelength of the near-infrared laser is 0.79~1.09μm.

17. The method for manufacturing a laminated metal sheet according to claim 10, characterized in that, The thickness of the resin film is 18.0 μm or more.

18. The method for manufacturing a laminated metal sheet according to claim 10, characterized in that, Remove the resin coating along the end of the original plate.

19. The method for manufacturing a laminated metal sheet according to claim 10, characterized in that, The base metal plate is a steel plate.

20. A method for manufacturing a weldable article, comprising a step of welding a laminated metal sheet obtained by the method for manufacturing a laminated metal sheet according to any one of claims 10 to 19 to a material to be welded. Welding is performed on the areas where the resin coating has been removed.

21. A method for manufacturing a battery cell, comprising the method for manufacturing the welded article as described in claim 20.

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