Composite member

Abstract

The present invention provides a composite member which is excellent in terms of heat resistance, and is particularly excellent in terms of insulation properties, and which does not require winding work that is necessary for a ceramic tape and can be easily suited to a complicated shape without causing winding unevenness or a gap. This composite member is able to maintain excellent insulation properties and excellent heat resistance even if heated at high temperatures. This composite member (1) has a base material (2) and an insulating coating film (3) that covers at least a part of the surface of the base material (2). The insulating coating film (3) is obtained by alternately stacking a plurality of first coating films (11) and a plurality of second coating films (12) in this order from the base material (2) side. The first coating films (11) each have a matrix (10) that contains a compound having a siloxane bond, and an inorganic material (20) that is dispersed in the matrix (10). The second coating films are formed of the material of the matrix (10).

Description

Composite materials

[0001] The present invention relates to a composite member in which a substrate is coated with an insulating coating.

[0002] Conductive materials, which are metal pieces with insulating coatings formed on their surfaces, are used to electrically connect components. For example, various electronic devices, electric vehicles or hybrid vehicles driven by electric motors, and storage batteries are equipped with power storage devices in which multiple battery cells are connected in series or parallel by conductive bus bars. Furthermore, lithium-ion secondary batteries, which have higher capacity and higher output than lead-acid batteries or nickel-metal hydride batteries, are primarily used as battery cells.

[0003] When a battery cell is charged or discharged, an overcurrent may flow through the bus bar, causing the bus bar to heat up and possibly even burst into flames. Therefore, the bus bar must be heat-resistant as well as insulating. For example, Patent Document 1 (JP-A-2003-125566) describes a bus bar in which a ceramic tape, such as mica tape, is wrapped around a copper bus bar body as a fire-resistant layer.

[0004] Chinese Utility Model No. 216902355

[0005] However, in Patent Document 1, the ceramic tape must be wrapped around the busbar body. Due to spatial limitations in the installation location of the battery cells, the busbar may have a complex shape, making it difficult to wrap the ceramic tape thoroughly around every corner of the busbar body. If the ceramic tape has uneven wrapping or gaps, sufficient insulation and heat resistance cannot be achieved. It is also possible that the adhesive surface of the ceramic tape may peel off. Furthermore, while nylon tape is wrapped around the outside of the mica tape as an insulating layer, nylon tape has poor heat resistance and is therefore prone to damage from heat, preventing the desired insulation from being maintained.

[0006] Therefore, an object of the present invention is to provide a composite member that has excellent heat resistance and particularly excellent insulation properties, does not require winding work like ceramic tape, does not produce uneven winding or gaps, can easily be adapted to complex shapes, and can maintain excellent insulation properties and heat resistance even when heated at high temperatures.

[0007] The above object of the present invention is achieved by the following configuration [1] relating to a composite member.

[0008] [1] A composite member having a substrate and an insulating coating covering at least a portion of the surface of the substrate, wherein the insulating coating comprises: a first coating having a matrix containing a compound having a siloxane bond and an inorganic material dispersed in the matrix; and a second coating made of the material of the matrix, wherein the first coating and the second coating are alternately stacked in this order from the substrate side.

[0009] Furthermore, preferred embodiments of the present invention relating to the composite member relate to the following [2] to

[14] .

[0010] [2] The composite material according to [1], wherein the insulating coating has a thickness of 150 μm or more.

[0011] [3] The composite material according to [1] or [2], characterized in that, when a cross section of the insulating coating is observed in a direction parallel to the thickness of the insulating coating, a porosity P1 in a rectangular region R1 having sides of 50 μm in the thickness direction of the insulating coating and sides of 300 μm perpendicular to the thickness direction in any range of the first coating is 10% or less.

[0012] [4] The composite material according to any one of [1] to [3], wherein the second coating is present on at least a portion of the surface of the insulating coating.

[0013] [5] The composite material according to [4], characterized in that the thickness of the second coating present on at least a portion of the surface of the insulating coating is 10 μm or more and 100 μm or less.

[0014] [6] The composite material according to any one of [1] to [5], characterized in that at least a part of the surface of the insulating coating has a resin layer containing a resin different from the material of the matrix.

[0015] [7] The composite material according to [6], characterized in that the resin layer has a thickness of 100 μm or more and 600 μm or less.

[0016] [8] The composite material according to any one of [1] to [7], wherein the compound having a siloxane bond is at least one of silicone and silica sol.

[0017] [9] The composite member according to any one of [1] to [8], characterized in that the inorganic material contains at least one selected from silica, alumina, mullite, and zirconia.

[0018]

[10] The composite member according to any one of [1] to [8], characterized in that the inorganic material contains at least one selected from glass-based materials, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth, and halloysite.

[0019]

[11] The composite member according to any one of [1] to [8], wherein the inorganic material contains at least one selected from the group consisting of flakes, fibers, and particles.

[0020]

[12] The composite member according to any one of [1] to [8], wherein the inorganic material contains at least one of a glass flake material and mica.

[0021]

[13] The composite member according to any one of [1] to

[12] , which is applied to a bus bar that connects a plurality of battery cells or battery modules.

[0022]

[14] The composite member according to any one of [1] to

[12] , which is applied to a connector, a protective part for a battery module, a case for an electronic component, a battery cell, a battery module, a battery pack, or a motor coil.

[0023] The composite member of the present invention has an insulating coating that covers at least a portion of the substrate, and therefore has a first coating that has a matrix containing a compound having a siloxane bond and an inorganic material. Furthermore, the first coating and the second coating made of the matrix material are alternately laminated in multiple layers, which further improves the insulating properties and allows the composite member to maintain excellent insulating properties and heat resistance even when heated at high temperatures.

[0024] FIG. 1 is a photograph showing a cross section of a composite member according to the present embodiment. FIG. 2 is a perspective view showing a bus bar to which the composite member according to the present embodiment is applied. FIG. 3A is a diagram showing the steps of a method for manufacturing a composite member according to the present embodiment, and is a schematic diagram showing the state after the first first coating material curing step. FIG. 3B is a diagram showing the steps of a method for manufacturing a composite member according to the present embodiment, and is a schematic diagram showing the state after the first immersion step. FIG. 3C is a diagram showing the steps of a method for manufacturing a composite member according to the present embodiment, and is a schematic diagram showing the state after the second first coating material curing step. FIG. 3D is a diagram showing the steps of a method for manufacturing a composite member according to the present embodiment, and is a schematic diagram showing the state after the resin layer forming step.

[0025] The present inventors conducted extensive research to obtain a composite member that can solve the above problems without using an insulating tape such as ceramic tape. As a result, they discovered that by applying an insulating coating material to the surface of a substrate and forming an insulating coating that covers the surface of the substrate, it is possible to easily adapt the composite member to complex shapes.

[0026] Furthermore, the inventors conducted extensive research to further improve the insulating properties of the insulating coating and found that it is effective to alternately stack multiple first coatings each having a matrix containing a compound having a siloxane bond and an inorganic material, and multiple second coatings made of the matrix material.

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and can be implemented with any modifications within the scope of the gist of the present invention.

[0028] [Composite Member] Figure 1 is a photograph showing a cross section of a composite member according to this embodiment. The composite member 1 has a substrate 2 and an insulating coating 3 that covers at least a portion of the surface of the substrate 2. The insulating coating 3 is formed by alternately laminating multiple first coatings 11 and second coatings 12 in order from the substrate 2 side. The first coatings 11 and second coatings 12 that constitute the insulating coating 3 of the composite member 1 according to this embodiment, as well as the substrate 2, will be described in detail below.

[0029] <Insulating Coating> As shown in FIG. 1 , the insulating coating 3 of the composite member 1 according to this embodiment is formed by alternately stacking three layers of first coatings 11 and three layers of second coatings 12 from the substrate 2 side.

[0030] (First Coating) The first coating 11 has a matrix 10 containing a compound having a siloxane bond and an inorganic material 20 dispersed in this matrix 10. Both the compound having a siloxane bond and the inorganic material 20 are materials with excellent heat resistance and insulating properties, and therefore, when the compound having a siloxane bond and the inorganic material 20 are included as components of the first coating 11 that constitutes the insulating coating 3, excellent heat resistance and insulating properties can be obtained. Furthermore, a plurality of pores 30 are formed inside the first coating 11.

[0031] Examples of compounds having a siloxane bond (Si—O—Si bond) include silicone and silica sol (silica: SiO ２ From the viewpoint of excellent heat resistance and insulating properties, the compound having a siloxane bond contained in the matrix 10 is preferably at least one of silicone and silica sol, and more preferably silicone. It is also a preferred embodiment that the matrix 10 contains both silicone and silica sol.

[0032] (Thickness of First Coating) The thickness of each of the first coatings 11 is not particularly limited, but is preferably a thickness that can be easily formed in a single application when applying a coating liquid to the substrate surface, as shown in the manufacturing process described below. The thickness of each of the first coatings 11 is preferably 50 μm or more, and more preferably 100 μm or more. On the other hand, if the thickness of the first coating 11 is too thick, it may be difficult to fill some of the pores formed during the manufacturing process with the second coating 12 in the step of forming the second coating 12, which may increase the porosity described below. Therefore, the thickness of each of the first coatings 11 is preferably 400 μm or less, and more preferably 300 μm or less.

[0033] (Porosity of First Coating) As shown in FIG. 1 , pores 30 are formed in the first coating 11. However, depending on the manufacturing method of the insulating coating 3, a large number of pores 30 may be generated within the first coating 11, potentially reducing the strength of the insulating coating 3. In this embodiment, it is preferable to control the porosity in an arbitrary region R1 of the first coating 11 when observing a cross section of the insulating coating 3 parallel to the thickness of the insulating coating 3. Note that region R1 refers to a rectangular region within the first coating 11, with sides measuring 50 μm in the thickness direction and sides perpendicular to the thickness direction being 300 μm. If the porosity P1 in region R1 is 10% or less, the number of pores 30 is reduced overall within the insulating coating 3. As a result, the spaces between the inorganic material 20 in the first coating 11 are nearly filled with the matrix 10, resulting in a dense structure for the first coating 11, thereby ensuring sufficient strength for the entire insulating coating 3. Therefore, the porosity P1 is preferably 10% or less, more preferably 8% or less, and even more preferably 6% or less.

[0034] In this embodiment, the porosity P1 is calculated by the following method. First, a micrograph is taken of a cross section parallel to the thickness direction of the composite member 1 on which the insulating coating 3 is formed. Next, an arbitrary region R1 is selected from the obtained photograph, the pores 30 present in the region R1 are extracted, and the total area of ​​the pores 30 in the region R1 is calculated. The total area of ​​the pores 30 is then divided by the area of ​​the region R1 to calculate the porosity P1 in the region R1. The porosity P1 is preferably obtained by sampling the region R1 from three locations within the above range and calculating the average of the porosities obtained, and more preferably by calculating the average of the porosities obtained from five locations within the above range.

[0035] (Second Coating) Unlike the first coating 11, the second coating 12 does not contain the inorganic material 20 and is made of the matrix 10 material. Therefore, high adhesion is achieved between the first coating 11 and the second coating 12. Furthermore, the second coating 12 is a hard, dense layer. Because the matrix material containing a compound with a siloxane bond has excellent insulating properties, stacking multiple second coatings 12 further improves the insulating properties. In this embodiment, the second coating 12 is preferably present on at least a portion of the surface of the insulating coating 3. The presence of the second coating 12 on the surface of the insulating coating 3 can suppress damage to the surface of the composite member 1 and mitigate the impact of a colliding object. The presence of the second coating 12 on the surface of the insulating coating 3 can also prevent the inorganic material 20 and other components contained in the first coating 11 from falling off.

[0036] (Thickness of Second Coating) When the thickness of the second coating 12 present on the surface of the insulating coating 3 is 10 μm or more, the second coating 12 can protect the composite member 1 and prevent the inorganic material 20 and other components in the first coating 11 from falling off. Therefore, the thickness of each second coating 12 is preferably 10 μm or more. Furthermore, when the thickness of the second coating 12 is 100 μm or less, peeling can be suppressed. Therefore, the thickness of each second coating 12 is preferably 100 μm or less. Furthermore, when the thickness of each second coating 12 is 10 μm or more, the insulating property can be sufficiently improved, and when the thickness is 100 μm or less, peeling can be suppressed. Therefore, the thickness of each second coating 12 is preferably 10 μm or more, except for the surface, except for the surface. Furthermore, the thickness of each second coating 12 is preferably 100 μm or less, except for the surface.

[0037] (Thickness of the Insulating Coating) If the thickness of the insulating coating 3 is less than 150 μm, the strength of the insulating coating 3 will be insufficient, which may result in peeling, making it difficult to ensure insulation. Therefore, the thickness of the insulating coating 3 is set to 150 μm or more, and preferably 200 μm or more. On the other hand, the strength of the insulating coating 3 improves as the thickness of the insulating coating 3 having porosity, as described below, increases, so there is no particular upper limit to the thickness. However, if the thickness is too thick, it becomes difficult to control the size of the composite member 1 and the manufacturing cost increases. Furthermore, peeling is more likely to occur. Therefore, the thickness of the insulating coating 3 is preferably set to 800 μm or less, and more preferably 600 μm or less.

[0038] In the composite member 1 configured as described above, the base material 2 is not wrapped with tape to provide insulation, but rather an insulating coating material is applied to the surface of the base material 2, forming the insulating coating 3 that adheres closely to the base material 2. Therefore, when manufacturing the composite member 1 according to this embodiment, no wrapping operation is required, there are no problems such as uneven winding, gaps, or peeling, and complex shapes can be easily accommodated. In addition, the first coating 11 that constitutes the insulating coating 3 is made of silicone or silica sol (silica: SiO２ Since the composite member 1 includes the matrix 10 containing a compound having a siloxane bond (Si—O—Si bond), such as ethylenediamine fluoride, and the inorganic material 20, the composite member 1 is less likely to deteriorate even when exposed to high temperatures, and can maintain excellent heat resistance and insulating properties. Furthermore, since the second coating 12 having a dense structure made of the material of the matrix 10 is repeatedly layered, even better insulating properties can be obtained.

[0039] The materials contained in the first coating 11 and the second coating 12 that constitute the insulating coating 3 in the composite member 1 according to this embodiment will be described in more detail below.

[0040] (Compound having siloxane bonds: silicone) Silicone, which is a suitable example of a compound having siloxane bonds and is contained in the matrix 10 of the insulating coating 3, is heated in the curing step of the coating material in the manufacturing method described below, whereby functional groups disappear and SiO bonds are generated. Furthermore, if a fire or the like occurs near the composite member and the insulating coating is heated to a temperature of, for example, 700°C or higher, the silicone will be thermally decomposed to form SiO ２ is generated. Then, this SiO ２ Since the insulating coating 3 containing silicone is not burned even when exposed to flames, the insulating coating 3 can obtain excellent heat resistance. That is, even when the composite member 1 according to this embodiment is heated at high temperatures, the insulating coating 3 adheres to the substrate 2 without peeling off, and excellent insulating properties and heat resistance can be maintained. Silicone includes silicone resin and silicone rubber, and either can be used, but selecting silicone resin is preferable because the SiO formed ２ This is preferable from the viewpoint of increasing the density.

[0041] (Inorganic Material) Inorganic material 20 has a high melting point and excellent heat resistance, and therefore, by including inorganic material 20 in first coating 11 constituting insulating coating 3, it is possible to improve the heat resistance of the entire insulating coating 3. Furthermore, inorganic material 20 can also function as a skeleton in first coating 11, thereby improving the strength of insulating coating 3.

[0042] The inorganic material 20 preferably contains a silicate compound. As described above, silicone, which is an example of a compound having a siloxane bond, is thermally decomposed to form SiO ２ However, silicate compounds can be converted into SiO ２ Since the silicate compound has the same components as those of the silicone matrix 10, it is possible to improve the bonding strength between the silicone matrix 10 and the inorganic material 20. The silicate compound preferably contains at least one selected from glass-based materials, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth, and halloysite.

[0043] The main component of silica sol (silica), which is another suitable example of a compound having a siloxane bond, is SiO ２ and the silicate compound is silica sol (SiO ２ ), the bonding strength between the matrix 10 containing silica sol (silica) and the inorganic material 20 can also be improved.

[0044] It is also preferable that the inorganic material 20 contains at least one selected from silica, alumina, mullite, and zirconia. These materials have high melting points and high insulating properties. Therefore, including these materials in the first coating 11 can further improve the heat resistance and insulating properties of the insulating coating 3 as a whole. When a busbar is used as an example of the composite member of the present invention, the expected heat exposure temperature of the busbar is equal to or higher than the melting point of the metal material typically used in busbar bodies. In this embodiment, including silica, alumina, mullite, zirconia, or the like as the inorganic material 20 can prevent the busbar body from being exposed to high heat because these materials have melting points equal to or higher than the heat exposure temperature. Therefore, these materials are suitable for use as materials for the insulating coating 3 of a busbar.

[0045] The shape of inorganic material 20 preferably includes at least one selected from flakes, fibers, and particles. When inorganic material 20 has such a shape, the adhesive strength between inorganic material 20 and matrix 10 is increased when inorganic material 20 is dispersed in matrix 10, thereby improving the strength of insulating coating 3.

[0046] Furthermore, when the inorganic material 20 includes a glass-based material, it is preferable to use at least one selected from a flaky glass-based material, glass particles, and glass fibers as the glass-based material. Among these, the flaky glass-based material is oriented in a planar shape inside the insulating coating 3 and exhibits excellent insulating properties and heat resistance. Therefore, it is particularly preferable that the glass-based material includes a flaky glass-based material. Furthermore, for the same reasons as for the flaky glass-based material, it is particularly preferable that mica be used as the inorganic material 20.

[0047] The content of inorganic material 20 relative to all components in first coating 11 is preferably 3 to 70 volume %, more preferably 10 to 50 volume %, and even more preferably 20 to 40 volume %. If the content of inorganic material 20 is less than 3 volume %, sufficient insulation and heat resistance may not be obtained. On the other hand, if the content exceeds 70 volume %, the viscosity of the coating liquid used for dip coating becomes too high, resulting in poor film-forming properties.

[0048] The content of the inorganic material 20 in the first coating 11 can be measured, for example, using a method similar to the porosity measurement method described above. Specifically, a cross section of the insulating coating 3 taken in a direction parallel to the thickness direction is photographed using an electron microscope. A specific region is selected from the photograph, and within this region, portions that can be determined to be inorganic material are colored. The total area of ​​the colored region (inorganic material) is then divided by the area of ​​the selected region to calculate the content (volume %) of the inorganic material 20. The larger the size of the measurement region, the smaller the error. For example, similar to the porosity measurement region described above, a rectangular region of the first coating 11 with sides of 50 μm in the thickness direction and sides of 300 μm perpendicular to the thickness direction can be selected. The content of the inorganic material 20 in the first coating 11 is preferably determined by sampling regions of the above size from three different locations in the first coating 11 and averaging the obtained contents, or more preferably by averaging the contents obtained from five different locations.

[0049] In addition to the matrix 10 and inorganic material 20 described above, the first coating 11 constituting the insulating coating 3 may contain other materials such as a flame retardant, a dispersant, or a pigment, as long as the materials do not affect the insulating properties or heat resistance. As will be described later, the first coating 11 is formed by applying a coating material (coating liquid) that will become the first coating material to the surface of the substrate. In order to improve the application performance of the coating liquid that contains the material of the matrix 10 and the inorganic material 20, it is preferable that the first coating 11 contain a thixotropic agent.

[0050] Similar to first coating 11, second coating 12 may also contain other materials such as flame retardants, dispersants, pigments, etc., as long as they do not affect the insulating properties or heat resistance.

[0051] <Resin Layer> The composite material 1 may have a resin layer (not shown) containing a resin different from the matrix material on at least a portion of its surface. The resin layer may be made of an insulating resin, such as epoxy resin, nylon resin, SBR (styrene butadiene rubber), or silicone rubber. Having a resin layer in the composite material 1 can further improve insulation and heat resistance.

[0052] (Thickness of Resin Layer) When the composite material 1 has a resin layer, if the thickness of the resin layer is 100 μm or more, the effect of improving insulation and heat resistance can be sufficiently obtained. Therefore, the thickness of the resin layer is preferably 100 μm or more, more preferably 120 μm or more, and even more preferably 150 μm or more. Furthermore, if the thickness of the resin layer is 600 μm or less, it does not affect the size of the composite material 1 and can also suppress an increase in manufacturing costs. Therefore, the thickness of the resin layer is preferably 600 μm or less, more preferably 550 μm or less, and even more preferably 500 μm or less.

[0053] <Substrate> In this embodiment, the substrate 2 is not particularly limited, and the main body of various products to which the composite material 1 according to this embodiment is applied can be used as the substrate 2. For example, when a bus bar, which will be described later, is applied as the composite material 1, a conductive bus bar body can be used as the substrate 2. Note that the bus bar body is conductive, and the substrate itself is electrically conductive; however, in this embodiment, the substrate 2 to be coated with the insulating coating 3 is not limited to a conductive material. For example, a substrate made of a non-electrically conductive material can also be used.

[0054] [Specific Application Examples of the Composite Material] There are no particular limitations on the products to which the composite material 1 can be applied, but it can be applied, for example, to bus bars used to connect multiple battery cells or battery modules in an energy storage device. The configuration of the composite material 1 will be described below using a bus bar as an example.

[0055] FIG. 2 is a perspective view showing a busbar to which the composite member according to this embodiment is applied. Note that FIG. 2 shows the busbar (composite member) 100 in a state immediately before being attached to a battery cell 130. The busbar body (base material) 110 is, for example, a Z-shaped metal plate member. The busbar body is secured in place by inserting an electrode 135 of the battery cell 130 into a connection hole 115a at one end and covering it with a terminal cap 136. The busbar body 110 also has a connection hole 115b at the other end, which is used to connect an adjacent battery cell (not shown) or an external device (not shown). The busbar body 110 is covered with an insulating coating 3 throughout its entirety, excluding the connection holes 115a and 115b. This is how the busbar 100 is configured.

[0056] Although not shown in the figures, the busbar body 110 may be I-shaped overall or may have an irregular shape with curved portions, and may have various shapes depending on the installation location of the battery cell 130.

[0057] If the busbar body 110 has a shape with a bent portion 110a or a curved portion (not shown), such as the Z-shape shown in the figure, the following problems may occur. For example, in a method in which ceramic tape is wrapped around the body, as in the busbar disclosed in Patent Document 1, the wrapping process is time-consuming to prevent unevenness or gaps in the winding at the bent portion 110a or the curved portion. In addition, it is possible that gaps may occur in the ceramic tape due to vibration or the adhesive between the ceramic tape and the body may peel off.

[0058] In contrast, in the busbar 100 configured as described above, the busbar body 110 is not insulated by wrapping tape around it, but rather the material of the first coating 11 (first coating material) and the material of the second coating 12 (second coating material) that form the insulating coating 3 are alternately applied multiple times to the surface of the busbar body 110, forming the insulating coating 3 that adheres closely to the busbar body 110. Therefore, no winding operation is required when manufacturing the busbar 100, and there are no problems such as uneven winding, gaps, or peeling, and the busbar can easily be made into a complex shape.

[0059] The coating material for the first coating 11 can be applied to the surface of the busbar body 110 by "dip coating," in which the busbar body 110 is immersed in a coating liquid, or by painting with a brush or spray. When dip coating is used, the insulating coating 3 is not formed on the connection holes 115a and 115b, so these areas are masked before being immersed in the coating liquid. Furthermore, a preferred method for applying the coating liquid for the second coating 12 to the surface of the first coating 11 is to mask the areas of the busbar body 110 on which the first coating 11 has been formed, on which the insulating coating 3 is not to be formed, and then immerse the busbar body 110 in the coating liquid for the second coating 12. By repeating this process multiple times, the insulating coating 3 can be formed to cover at least a portion of the surface of the busbar body 110.

[0060] In addition to the bus bar, the composite member according to this embodiment can be applied to connectors, protective parts for battery modules, cases for electronic components, battery cells, battery modules, battery packs, or motor coils.

[0061] [Method for Manufacturing Composite Member] The composite member according to this embodiment can be manufactured, for example, by the manufacturing method described below. FIGS. 3A to 3D are schematic diagrams illustrating the manufacturing method for the composite member according to this embodiment in the order of steps. In FIGS. 3A to 3D, the same components as those shown in FIG. 1 are designated by the same reference numerals, and detailed descriptions thereof are omitted or simplified. However, for ease of explanation, in FIGS. 3A to 3D, the reference numerals for the first and third first coating layers, counting in the order of lamination from the substrate 2, are differentiated. Furthermore, the reference numerals for the second and fourth second coating layers are differentiated. Note that, although the manufacturing method described below will be described for a case in which the compound having a siloxane bond contained in the matrix 10 is silicone, it is equally applicable when the compound having a siloxane bond is silica sol (silica).

[0062] 3A , first, a material for the first coating 11a (first coating material) is applied to at least a portion of the surface of the substrate 2. The first coating material is, for example, an organic solvent to which a material for the matrix 10 containing silicone and an inorganic material 20 have been added.

[0063] (First Coating Material Drying Step) After the above-mentioned coating step, the first coating material is dried at a temperature of, for example, 50° C. In this first coating material drying step, the organic solvent is volatilized.

[0064] (First Coating Material Curing Step) The dried first coating material is then heated to a temperature of, for example, 200° C. and cured. This first coating material curing step causes dehydration condensation of the silicone, forming the first coating 11 a with a three-dimensional network structure. At this point, numerous pores 30 are formed in the first coating 11 a.

[0065] <Formation of Second Layer> (First Immersion Step) The substrate 2 on which the first coating 11a is formed is then immersed in a material for the second coating 12a (second coating material). The second coating material does not contain the inorganic material 20, but is an organic solvent to which the silicone-containing matrix 10 material has been added. As shown in FIG. 3B , this immersion step fills some of the numerous pores 30 formed in the first coating 11a with the second coating material, thereby reducing the porosity of the first coating 11a. Furthermore, excess second coating material not absorbed into the pores 30 remains on the surface of the first coating 11a. The second coating material is then dried, for example, at 50°C, and then heated, for example, at 200°C to harden it. This results in the formation of a second coating 12a made of the silicone-containing matrix 10 material on the surface of the first coating 11a.

[0066] <Formation of Third Layer> (Second Coating Process) Then, as shown in Fig. 3C, the first coating material is again laminated on the surface of the second coating 12a. This first coating material is the same material as that used in the first coating process.

[0067] (First Coating Material Drying Step: Second Time) After the second coating step, the first coating material is dried, for example, at a temperature of 50° C. This second first coating material drying step volatilizes the organic solvent in the first coating material applied in the second coating step.

[0068] (Second First Coating Material Curing Process) The dried first coating material is then heated to a temperature of, for example, 200° C. and cured. This second first coating material curing process causes dehydration condensation of the silicone, resulting in the formation of a first coating 11 b with a three-dimensional network structure. At this point, numerous pores 30 are formed in the first coating 11 b.

[0069] <Formation of the Fourth Layer> (Second Dipping Process) Then, as shown in FIG. 3D , the substrate 2 on which the first coating 11b is formed is immersed in a second coating material. The second coating material is the same material as used in the first immersion process. This second immersion process fills some of the numerous pores 30 formed in the first coating 11b with the second coating material, reducing the porosity of the first coating 11b. Furthermore, any second coating material not absorbed into the pores 30 remains on the surface of the first coating 11b. The second coating material is then dried, for example, at 50°C, and then heated, for example, at 200°C to harden it. This results in the formation of a second coating 12b made of the silicone-containing matrix 10 material on the surface of the first coating 11b.

[0070] The immersion times in the first and second immersion steps are not particularly limited, but may be selected so that excess second coating material remains on the surfaces of the first coatings 11 a and 11 b, resulting in the formation of second coatings 12 a and 12 b. These second coatings 12 a and 12 b are made of the second coating material remaining on the surfaces, and therefore have a dense structure that does not contain inorganic material 20.

[0071] (Resin Layer Forming Process) Thereafter, the resin layer 7 is formed on the second coating 12b by, for example, electrostatic powder coating or fluidized bed dip coating of an epoxy resin paint. When forming the resin layer 7, part of the material constituting the resin layer 7 may penetrate into the layer below it.

[0072] As described above, the second coating material used in the immersion process does not contain the inorganic material 20 of the first coating material used in the immersion process. In addition, since the material of the matrix 10 is silicone, the amount of silicone is increased by including silicone in the second coating material, and the amount of SiO ２This increases the resistance to fire and allows the insulating coating 3 to be more effectively maintained even when subjected to flames.

[0073] In the above-described manufacturing method, the series of steps from the deposition step to the immersion step was repeated twice, but it may be repeated multiple times until the desired film thickness is achieved. Even if the series of steps is repeated three or more times, since the immersion step of immersing in the second coating material after forming the first coating is included, the first coating and the second coating are repeatedly stacked, thereby forming an insulating coating 3 with high insulating properties.

[0074] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0075] This application is based on a Japanese patent application (Patent Application No. 2023-170683) filed on September 29, 2023, the contents of which are incorporated herein by reference.

[0076] REFERENCE SIGNS LIST 1 composite member 2 substrate 3 insulating coating 7 resin layer 10 matrix 11, 11a, 11b first coating 12, 12a, 12b second coating 20 inorganic material 30 pores 100 busbar 110 busbar body 115a, 115b connection hole 130 battery cell 135 electrode 136 terminal cap

Claims

1. A composite member having a substrate and an insulating coating covering at least a portion of a surface of the substrate, wherein the insulating coating comprises a first coating having a matrix containing a compound having a siloxane bond and an inorganic material dispersed in the matrix, and a second coating made of the material of the matrix, wherein the first coating and the second coating are laminated alternately in this order from the substrate side in multiple layers.

2. The composite material according to claim 1, wherein the insulating coating has a thickness of 150 μm or more.

3. The composite material described in claim 1, characterized in that, when a cross section of the insulating coating is observed in a direction parallel to the thickness of the insulating coating, in any range of the first coating, the porosity P1 in a rectangular region R1 having a side of 50 μm in the thickness direction of the insulating coating and a side of 300 μm perpendicular to the thickness direction is 10% or less.

4. The composite member according to claim 1, wherein the second coating is present on at least a portion of the surface of the insulating coating.

5. The composite material according to claim 4, characterized in that the thickness of the second coating present on at least a portion of the surface of the insulating coating is 10 μm or more and 100 μm or less.

6. A composite member according to any one of claims 1 to 5, characterized in that at least a portion of the surface of the insulating coating has a resin layer containing a resin different from the material of the matrix.

7. The composite material according to claim 6, wherein the thickness of the resin layer is 100 μm or more and 600 μm or less.

8. The composite member according to any one of claims 1 to 5, wherein the compound having a siloxane bond is at least one of silicone and silica sol.

9. The composite member according to any one of claims 1 to 5, characterized in that the inorganic material contains at least one selected from the group consisting of silica, alumina, mullite and zirconia.

10. The composite member according to any one of claims 1 to 5, characterized in that the inorganic material includes at least one selected from the group consisting of glass-based materials, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth, and halloysite.

11. The composite member according to any one of claims 1 to 5, characterized in that the inorganic material contains at least one type selected from the group consisting of flake-shaped, fibrous and particulate inorganic materials.

12. The composite member according to any one of claims 1 to 5, wherein the inorganic material includes at least one of a flake-like glass-based material and mica.

13. A composite member according to any one of claims 1 to 5, which is used as a bus bar for connecting a plurality of battery cells or battery modules.

14. The composite member according to any one of claims 1 to 5, which is applied to a connector, a protective part for a battery module, a case for an electronic component, a battery cell, a battery module, a battery pack, or a coil for a motor.

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