Insulating film and composite member

Abstract

The utility model provides an insulating covering film and a composite component, the insulating covering film is excellent in insulating property and heat resistance, does not need winding operation like a ceramic tape, does not generate the problems of uneven winding, gaps or stripping, and can easily cope with a conductive base material with a complex shape. The insulating film (1) is obtained by dispersing at least an inorganic material (20) in a first base material (10) containing silicone. In addition, a material of the first base material (10) or a material of a second base material having a component different from that of the first base material (10) may be impregnated. The insulating film (1) is formed, for example, by dip coating.

Description

Technical Field

[0001] The utility model relates to an insulating film and a composite component in which the insulating film is covered on a base material including a conductive base material such as a busbar. Background Art

[0002] In order to electrically connect the components, a conductive member having an insulating coating formed on the surface of the metal sheet is used. For example, in various electronic devices, electric vehicles or hybrid vehicles driven by electric motors, batteries, etc., a power storage device is mounted that uses a busbar as a conductive member to connect multiple battery cells in series or in parallel. In addition, lithium-ion secondary batteries that have high capacity and high power compared to lead-acid batteries, nickel-hydrogen batteries, etc. are mainly used in battery cells.

[0003] In a battery cell, an overcurrent may flow during charging and discharging, causing the busbar to heat up and sometimes ignite a flame. Therefore, the busbar is required to have insulation and heat resistance. For example, Patent Document 1 describes a busbar in which a ceramic tape such as a mica tape is wound around a copper busbar body as a fire-resistant layer.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Chinese Utility Model No. 216902355 Utility Model Content

[0007] Issues to be Solved by Utility Models

[0008] However, in Patent Document 1, it is necessary to wind the ceramic tape around the busbar body. Due to space limitations at the battery cell installation location, the busbar sometimes has a complex shape, but if the busbar has a complex shape, it is difficult to wind the ceramic tape around every corner of the busbar body. If there are uneven windings or gaps in the ceramic tape, insulation and heat resistance cannot be fully achieved. In addition, it is also assumed that the adhesive surface of the ceramic tape can be peeled off. Furthermore, a nylon tape is wound around the outside of the mica tape as an insulating layer, but the nylon tape is not heat-resistant and there are problems with heat resistance.

[0009] Therefore, an object of the present invention is to provide an insulating film which has excellent heat resistance in addition to insulation, does not require winding work like a ceramic tape, does not cause problems such as uneven winding, gaps, or peeling, and can easily cope with complex shapes.

[0010] Means for solving problems

[0011] The above-mentioned object of the present invention is achieved by the following structure [1] of the insulating coating.

[0012] [1] An insulating film characterized in that at least an inorganic material is dispersed in a first matrix material containing organic silicon, and a layer composed of a material of the first matrix material is provided on at least a portion of a film surface.

[0013] In addition, preferred embodiments of the present invention of the insulating coating relate to the following [2] to [6].

[0014] [2] The insulating coating according to [1], characterized in that the insulating coating has a layer made of a second base material having a composition different from that of the first base material on at least a portion of the film surface.

[0015] [3] The insulating coating according to [1] or [2], wherein the inorganic material is silicon dioxide, aluminum oxide, mullite or zirconium oxide.

[0016] [4] The insulating coating according to [1] or [2] is characterized in that the above-mentioned inorganic material is a glass-based material, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth or halloysite.

[0017] [5] The insulating coating according to [1] or [2], wherein the inorganic material is in at least one form selected from the group consisting of flaky, fibrous, and granular.

[0018] [6] The insulating coating according to [1] or [2], wherein the inorganic material is a flaky glass-based material or mica.

[0019] The above-mentioned object of the present invention is achieved by the following structure [7] of the composite component.

[0020] [7] A composite member characterized in that at least a portion of a base material is covered with the insulating film according to any one of [1] to [6].

[0021] In addition, a preferred embodiment of the present invention of the composite member relates to the following [8].

[0022] [8] The composite member according to [7], wherein the substrate is a bus bar connecting a plurality of battery cells or battery modules.

[0023] Effect of utility model

[0024] The insulating film of the utility model uses silicone as the base material. The silicone is thermally decomposed and the functional groups disappear, thereby forming SiO bonds and changing to SiO2. SiO2 will not burn even if exposed to flames, and the heat resistance is improved. In addition, the heat resistance of inorganic materials is also excellent. In addition, both silicone and inorganic materials have excellent insulation properties.

[0025] In addition, by further impregnating the insulating film made of silicone as the base material and in which the inorganic material is dispersed, the volatile components of the film material volatilize during film formation and fill the bubbles generated in the insulating film, so that the insulating film becomes denser and the film strength is improved. In addition, the material of the base material remains on at least a part of the surface of the insulating film and solidifies to form a layer as a top coating layer, so that the inorganic material and the like can be prevented from falling off and the film surface can be damaged, thereby improving the impact resistance.

[0026] Furthermore, the film forming method of the insulating film also uses a coating liquid containing a base material and an inorganic material for immersion coating, so the manufacturing process is simple. In addition, when the base material is impregnated, it is also very simple to immerse only in the base material.

[0027] Insulation coating is particularly useful for covering conductive components such as busbars. In this case, since it is dip-coated, there is no need for winding work like ceramic tape, and there are no problems such as uneven winding, gaps, or peeling, and it is easy to deal with complex shapes. In addition, silicone and inorganic materials have excellent heat resistance, so even if a battery cell of a storage device using a busbar has thermal runaway and a flame occurs, it can be fully handled. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a photograph taken in place of a drawing showing a cross section of the insulating coating according to the first embodiment of the present invention.

[0029] Figure 2 This is a photograph taken in place of a drawing showing a cross section of an insulating coating according to a second embodiment of the present invention.

[0030] Figure 3 It is a perspective view schematically showing a bus bar which is an electrically conductive member as an example of the composite member of the present invention.

[0031] Figure 4 Schematic diagram showing a test apparatus used in Examples.

[0032] Figure 5 It means use Figure 4 The test device shown is a diagram showing the results of observing whether or not the insulating coating 1A (test piece A / utility example) and the mica tape (test piece B / comparative example) after heating are peeled off. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to the embodiments described below, and can be implemented with arbitrary changes within the scope not departing from the gist of the present invention.

[0034] [Insulation coating]

[0035] (First Embodiment)

[0036] Figure 1 This is a photograph of a cross section of the insulating film of the present embodiment. In the insulating film 1, an inorganic material (white line segment in the figure: symbol 20) is dispersed in a first base material (gray portion in the figure: symbol 10) having organic silicon.

[0037] In silicone, when thermally decomposed, the functional group disappears and SiO bonds are generated, which burn out and change into SiO2. SiO2 will not burn even when exposed to flames, and the insulation coating 1 has excellent heat resistance. It should be noted that silicone includes silicone resin and silicone rubber, and can be either one, but silicone resin is preferred from the viewpoint of making the formed SiO2 high-density.

[0038] As described later, the insulating film 1 is obtained by dip coating, but in order to improve the coating performance of the coating liquid containing the material of the first base material 10 and the inorganic material 20, it is preferable to use a thixotropic agent in combination.

[0039] The inorganic material 20 has a high melting point and excellent heat resistance, and preferably contains a silicate compound. As described above, organic silicon may be changed into SiO2 due to thermal decomposition, but the silicate compound has the same composition as SiO2 formed by organic silicon, so the bonding strength between the first matrix 10 having organic silicon and the inorganic material 20 is improved. It should be noted that as the silicate compound, it is preferably selected from at least one of glass-based materials, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth and halloysite.

[0040] In addition, as the inorganic material 20, from the viewpoint of having a high melting point and high insulation, at least one selected from silica, alumina, mullite and zirconia is preferred. It should be noted that, as an example of the composite member of the utility model, when a busbar as a conductive member is applied, these materials are inorganic materials having a melting point above the heat exposure temperature (assuming that the heat exposure temperature is above the melting point of the metal material used in the general busbar body), and are therefore suitable for the insulating film 1 for the busbar.

[0041] The inorganic material 20 is preferably in the form of at least one selected from the group consisting of flakes, fibers, and particles. When the inorganic material 20 is dispersed in the first base material 10 , the adhesion with the first base material 10 is improved, which contributes to improving the strength of the insulating film 1 .

[0042] In addition, when a glass-based material is included as the inorganic material 20, the glass-based material is preferably at least one selected from flaky glass, glass particles, and glass fibers. Among them, flaky glass is oriented in a plane in the film and exhibits excellent insulation and heat resistance, so it is particularly preferable to include flaky glass. In addition, for the same reason as the flaky glass, the above-mentioned mica is also preferably used.

[0043] The content of the inorganic material 20 relative to the total components in the insulating film 1 is preferably 3 to 70% by volume, more preferably 10 to 50% by volume, and further preferably 20 to 40% by volume. When the content of the inorganic material 20 is less than 3% by volume, it may not be possible to obtain sufficient insulation and heat resistance. On the other hand, when it exceeds 70% by volume, the viscosity of the coating liquid for dip coating becomes too high, and the film-forming property is poor.

[0044] In addition, silicone and the inorganic material 20 are excellent in insulation in addition to heat resistance, and therefore are useful as components of the insulating film 1 .

[0045] It should be noted that the insulating film 1 may contain other materials such as a flame retardant, a dispersant, a pigment, etc. in addition to the first base material 10 and the inorganic material 20 as long as the insulating film 1 does not affect the insulating property and the heat resistance.

[0046] (Second Embodiment)

[0047] In the insulating film 1 of the first embodiment, the inorganic material 20 is dispersed in the first base material 10. However, in the insulating film 1, the volatile components of the film material volatilize during film formation, and bubbles are generated in the film. Figure 1 In the figure, the black parts are bubbles 30, and a plurality of them are dispersed in the film.

[0048] Therefore, in order to fill the bubbles 30, the insulating film 1 of the first embodiment is impregnated with a material that is the same as the first base material 10 or a material of a second base material that is different in composition from the first base material depending on the situation (hereinafter, also collectively referred to as "base material material") In other words, the insulating film 1A of the second embodiment is obtained by filling the bubbles 30 of the insulating film 1 of the first embodiment with the base material, and the coating becomes denser and the film strength is improved. Figure 2 This is a cross-sectional photograph of the insulating coating 1A according to the second embodiment. However, unlike the insulating coating 1 according to the first embodiment, the bubbles 30 are hardly seen, and it is known that the bubbles 30 are filled with the base material.

[0049] As the base material to be impregnated, from the viewpoint of affinity, it is preferable to use the same material as the first base material 10 of the insulating film 1. In addition, since the first base material 10 is silicone, the amount of silicone is increased, and the adhesion with the substrate forming the insulating film 1A is further improved, and the retention of the inorganic material 20 is also improved. Furthermore, as a result of the increase in silicone, SiO2 is also increased, and the insulating film 1A can be more effectively maintained even when exposed to flames.

[0050] The material of the second matrix also preferably has high affinity with the material of the first matrix, and is preferably the same material as the first matrix 10. Even when the material of the second matrix is ​​used, the heat resistance of SiO2 derived from silicone can be maintained because the first matrix 10 is present in the film.

[0051] The matrix material permeates from the film surface into the film, so a portion of the matrix material remains on the film surface and directly solidifies to form a layer. In addition, if the amount of the matrix material is large enough, the excess matrix material spreads on the film surface, unlike the portion immersed in the film, and directly solidifies to form a layer. Moreover, depending on the amount of the matrix material, the layer is formed in a manner that covers the entire surface of the film.

[0052] That is, in the insulating film 1A, if Figure 2 As shown, a layer 40 exists on a part or the entire surface of the film. Such a layer 40 functions as a top coat layer, prevents the inorganic material 20 and the like from falling off, suppresses damage to the film surface, and mitigates the impact of collision objects.

[0053] In addition, in the insulating coating 1A, since it is obtained by further impregnation with the base material, it has an inclined composition in which the base material increases as it approaches the film surface. This is particularly advantageous from the perspective of preventing the above-mentioned inorganic material 20 from falling off, inhibiting damage to the film surface, and alleviating the impact of collision objects.

[0054] [Method for forming insulating film]

[0055] Since the base material is in liquid form, dip coating is preferred as a method for forming the insulating film. Dip coating does not require winding work like ceramic tape, so the process is simple and there is no problem of uneven winding, gaps, or peeling. It can also easily handle conductive substrates with complex shapes.

[0056] That is, in order to form the insulating coating 1 of the first embodiment, the substrate is immersed in a coating liquid containing the first base material and at least an inorganic material, and after being pulled out, the coating liquid is dried.

[0057] In order to form the insulating film 1A of the second embodiment, the substrate having the insulating film 1 formed thereon is immersed in a coating liquid containing a matrix material to impregnate it, and then the coating liquid is dried. The amount of the matrix material impregnated is controlled by the immersion time.

[0058] [Conductive member]

[0059] The present invention also relates to a conductive member formed by covering a conductive substrate with the insulating film 1 or the insulating film 1A. The conductive member is not limited, and here, a bus bar for connecting a plurality of battery cells or battery modules in a power storage device is used as an example for description.

[0060] Figure 3 1 is an exploded perspective view showing a state where the busbar 100 of the present embodiment is mounted on a battery cell 130. The busbar body 110 is, for example, a metal plate member that is Z-shaped as a whole, and an electrode 135 of the battery cell 130 is inserted into a connection hole 115a at one end, and is covered and fixed with a terminal cover 136. In addition, an adjacent battery cell (not shown) and an external device (not shown) are connected to a connection hole 115b at the other end of the busbar body 110. The busbar 100 is formed by covering the portion of the busbar body 110 other than the connection holes 115a and 115b with an insulating film 1 or an insulating film 1A.

[0061] It should be noted that, although not shown in the drawings, the bus bar body 110 may be in an overall I-shape or in an irregular shape such as having a bent portion, and may be in various shapes depending on the location where the battery unit 130 is installed.

[0062] If the busbar body 110 has a shape having a zigzag-shaped bent portion 110a or a curved portion (not shown), in the manner of winding the ceramic tape as in the busbar of the above-mentioned Patent Document 1, in order to prevent uneven winding and gaps from occurring at the bent portion 110a or the curved portion, it is expected that the winding operation will take time, gaps will occur due to vibration, or adhesive peeling will occur. However, in the present embodiment, the insulating film 1 or the insulating film 1A is formed by "dip coating", so such problems will not occur.

[0063] In addition, in order to manufacture the busbar 100, during the "dip coating", the connection holes 115a and 115b are masked and dipped in the coating liquid.

[0064] Since the insulating film 1 or the insulating film 1A covering the bus bar 100 contains silicone, SiO is generated without burning even when it is exposed to flames from the battery cell 130 that has thermal runaway.

[0065] [Composite components]

[0066] In addition, the present invention is not limited to the above-mentioned conductive member, but also relates to a composite member formed by covering a substrate with the above-mentioned insulating film 1 or insulating film 1A. The composite member is not particularly limited, and in addition to the busbar as an example of the above-mentioned conductive member, for example, the substrate can be a connector, a protective component of a battery module, a housing of an electronic component, a battery cell, a battery module, a battery pack, or a coil of a motor.

[0067] It should be noted that, when used as a conductive substrate for a busbar, the substrate itself is electrified, but the substrate covered with the insulating coating 1 or insulating coating 1A of the present invention is not limited to this and does not hinder the application of the present invention in a substrate that itself is not electrified.

[0068] [Example]

[0069] In this embodiment, the technical effect of the insulating coating 1A of the utility model example was verified.

[0070] First, a coating liquid containing silicone resin and mica was applied to a copper plate (C1100) of 30 mm × 75 mm and 2 mm thick, and the coating liquid attached to the copper plate was dried and cured to form an intermediate of the insulating film 1A. Next, the intermediate of the insulating film 1A formed was further impregnated with silicone resin, and then dried and cured to produce a test piece A having the insulating film 1A on the copper plate. It should be noted that the thickness of the final insulating film 1A formed by further impregnation with silicone resin was 1006 μm.

[0071] For comparison, a mica tape having a thickness of 150 μm was double-wound around the same copper plate to prepare a test piece B.

[0072] Then, use Figure 4 The test device shown observes whether the insulating film 1A (test piece A / utility model example) and the mica tape (test piece B / comparative example) after heating are peeled off. The test device 200 is composed of an aluminum movable part 220 with a test piece 210 mounted on one end and a base 230 that supports the other end of the movable part 220 rotatably and is vertically installed on a support table 250. The movable part 220 is manually lifted at one end (the test piece side) at a predetermined angle θ relative to the base 230. When the hand is released, it collides with the base 230 in a vibrator-like trajectory (arrow in the figure).

[0073] The test assumes that the busbar is exposed to flames from a battery cell that has thermal runaway. After heating the test piece A or the test piece B at about 1000°C for a predetermined time (60 minutes) using an electric furnace, the test piece A or the test piece B is mounted on the movable part 220, and the angle θ is changed to 15°, 30°, 60°, and 90°, respectively, and then collides with the base 230. Then, the damage state of the insulating film 1A of the test piece A and the mica tape of the test piece B after the collision is visually confirmed.

[0074] The results of the test are as follows Figure 5 As shown. Figure 5 As shown, in the test piece A as the utility model example, when the collision occurred at any of the positions of angle θ=15°, 30° and 60°, the insulation coating 1A of the test piece A was not peeled off after the first repeated test. Furthermore, when the collision occurred at the position of angle θ=90°, the insulation coating 1A of the test piece A was not peeled off after the fifth repeated test.

[0075] On the other hand, in the test piece B serving as a comparative example, when the collision occurred at any of the angles θ=15°, 30°, and 60°, no peeling of the mica tape of the test piece B was observed after the first repeated test. However, when the collision occurred at an angle θ=90°, peeling of the mica tape of the test piece B was observed after the second repeated test (see arrow in the figure).

[0076] This shows that the insulating coating 1A of the test piece A as the utility model example can maintain a sufficient coating even when exposed to high temperature, and is suitable for use in busbar applications, for example.

[0077] Various embodiments have been described above, but the present invention is certainly not limited to these examples. It should be understood that it is obvious that a person skilled in the art can easily think of various variations or modifications within the scope of the claims, and they certainly belong to the technical scope of the present invention. In addition, the various constituent elements in the above embodiments may also be arbitrarily combined within the scope of the purpose of the present invention.

[0078] It should be noted that the present application is based on the Japanese patent application (Japanese Patent Application No. 2023-036021) filed on March 8, 2023, and the contents thereof are incorporated herein by reference.

[0079] Explanation of symbols

[0080] 1. 1A insulation coating

[0081] 10 First base material

[0082] 20 Inorganic materials

[0083] 30 Bubbles

[0084] 40th floor

[0085] 100 Busbar

[0086] 110 busbar body

[0087] 115a, 115b connection holes

[0088] 130 battery cells

[0089] 135 Electrode

[0090] 136 Terminal cover

[0091] 200 Test equipment

[0092] 210 Test piece

[0093] 220 Moving Parts

[0094] 230 base

[0095] 250 Support Table

Claims

1. An insulating coating, characterized in that: This is an insulating film in which at least an inorganic material is dispersed in a first matrix containing organic silicon, and has a layer made of the material of the first matrix on at least a part of the film surface.

2. The insulating film according to claim 1, characterized in that: The film has a layer formed of a second base material having a different composition from that of the first base material on at least a portion of the film surface.

3. The insulating film according to claim 1 or 2, characterized in that: The inorganic material is silicon dioxide, aluminum oxide, mullite or zirconium oxide.

4. The insulating film according to claim 1 or 2, characterized in that: The inorganic material is a glass material, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth or halloysite.

5. The insulating film according to claim 1 or 2, characterized in that: The inorganic material is in at least one form selected from the group consisting of flakes, fibers and particles.

6. The insulating film according to claim 1 or 2, characterized in that: The inorganic material is a flaky glass material or mica.

7. A composite component, characterized in that: At least a portion of the substrate is covered with the insulating film according to claim 1 or 2.

8. The composite component according to claim 7, characterized in that The substrate is a bus bar connecting a plurality of battery cells or battery modules.

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