Method for manufacturing an electrically conductive member and electrically conductive member

Abstract

A method for manufacturing an electrically conductive member, which includes: attaching a powder to a surface of a metal member by an electrostatic coating method, the powder containing a thermoplastic polyimide containing a structural unit represented by formula (1); and forming an insulating coating film by melting the attached powder by heating, in an IR spectrum of the insulating coating film, at least one of the following conditions is satisfied: a ratio I ‑1 / I 1487 of an absorption intensity I ‑1 at 1487 cm 1778 to an absorption intensity I 1487 at 1778 cm 1778 is 3.0 to 5.0; and a ratio I ‑1 / I 1232 of an absorption intensity I ‑1 at 1232 cm 1778 to an absorption intensity I 1232 at 1778 cm 1778 is 3.0 to 5.0.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing a conductive component and the conductive component itself. Background Technology

[0002] Polyimide typically exhibits excellent heat resistance and superior insulation properties at high temperatures. Therefore, polyimide is being investigated as a material for forming insulating layers in conductive components such as busbars.

[0003] For example, Patent Document 1 discloses a method for adhering a powder coating of thermoplastic polyimide polymer to a pipe using a flow impregnation method to form a coating with heat resistance, weather resistance, and corrosion resistance. In the flow impregnation method, strict management of the particle shape and particle size of the powder coating is required.

[0004] Patent Document 1: Japanese Patent Application Publication No. 4-339880 Summary of the Invention

[0005] The problem that the invention aims to solve

[0006] In addition to flow impregnation, electrostatic coating is also known as a method for forming films using powder coatings. Electrostatic coating involves spraying charged powder particles onto a desired substrate, causing the powder to adhere to the substrate. After the powder adheres and forms a powder layer on the substrate, heating is applied to melt the particles contained in the powder layer, thereby smoothing the powder layer and forming a film (also called a coating). Electrostatic coating can form thin films with high uniformity of thickness even on substrates with complex shapes, such as those with bent shapes or shapes with inconsistent thickness or width.

[0007] However, in conventional electrostatic coating methods, after spraying powder onto the substrate, the powder layer is annealed at a certain high temperature for a considerable period of time in order to smooth or homogenize it. Therefore, depending on the composition of the powder, sometimes the desired coating properties cannot be obtained due to heating.

[0008] This disclosure was made in view of the above circumstances, and relates to a method for manufacturing a conductive member that suppresses the reduction of insulation breakdown voltage, and a conductive member manufactured by the above manufacturing method.

[0009] Methods for solving problems

[0010] The specific means used to solve the above problems include the following methods.

[0011] <1> A method for manufacturing a conductive component includes: attaching powder to the surface of a metal component by electrostatic coating, wherein the powder comprises a thermoplastic polyimide containing structural units as shown in formula (1); and melting the attached powder by heating it to form an insulating coating.

[0012] In the IR spectrum of the aforementioned insulating coating, at least one of the following conditions must be met: 1487 cm⁻¹ -1 Absorption intensity I 1487 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1487 / I 1778 3.0~5.0; 1232cm -1 Absorption intensity I 1232 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1232 / I 1778 The value is 3.0~5.0.

[0013] [Chemistry 1]

[0014]

[0015] [Chemistry 2]

[0016]

[0017] In the above formula (1), X is a direct bond, -SO2-, -CO-, -C(CH3)2-, -C(CF3)2- or -S-. R1, R2, R3 and R4 are each independently a hydrogen atom, alkyl, alkoxy, haloalkyl, haloalkoxy or halogen atom.

[0018] In formula (1) above, Y is any of the groups represented in formulas (2-1) to (2-4) above. In formulas (2-1) to (2-4) above, This indicates a bond, and aromatic rings can have substituents.

[0019] <2> according to <1> In the method for manufacturing the conductive component, the heating temperature is 390℃~430℃.

[0020] <3> according to <1> or <2> In the method for manufacturing the conductive component, the heating time is more than 0 minutes and less than 30 minutes.

[0021] <4> according to <1> ~ <3> The method for manufacturing a conductive component according to any one of the following methods, wherein the powder satisfies at least one of the following conditions: the cumulative 50% of the particle size d50 in the volume-based particle size distribution is 5 μm to 100 μm; and the cumulative 90% of the particle size d90 in the volume-based particle size distribution is 10 μm to 200 μm.

[0022] <5> according to <1> ~ <4> The method for manufacturing a conductive component according to any one of the following methods, wherein the raw material for the metal component is any one of copper, copper alloy, iron, steel-containing iron alloy, aluminum, or aluminum alloy.

[0023] <6> according to <1> ~ <5> The method for manufacturing a conductive component according to any one of the following methods, wherein the metal component is a surface-treated metal component.

[0024] <7> according to <1> ~ <6> The manufacturing method of the conductive component according to any one of the above-mentioned methods, wherein the thickness of the insulating coating is 5 μm to 1000 μm.

[0025] <8> A conductive component comprising a metal component and an insulating film covering at least a portion of the surface of the metal component.

[0026] The aforementioned insulating coating comprises a thermoplastic polyimide containing structural units as shown in formula (1), and in the IR spectrum satisfies at least one of the following conditions: 1487 cm⁻¹ -1 Absorption intensity I 1487 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1487 / I 1778 3.0~5.0; 1232cm -1 Absorption intensity I 1232 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1232 / I 1778 The value is 3.0~5.0.

[0027] [Chemistry 3]

[0028]

[0029] [Chemistry 4]

[0030]

[0031] In the above formula (1), X is a direct bond, -SO2-, -CO-, -C(CH3)2-, -C(CF3)2- or -S-. R1, R2, R3 and R4 are each independently a hydrogen atom, alkyl, alkoxy, haloalkyl, haloalkoxy or halogen atom.

[0032] In formula (1) above, Y is any of the groups represented in formulas (2-1) to (2-4) above. In formulas (2-1) to (2-4) above, This indicates a bond, and aromatic rings can have substituents.

[0033] <9> according to <8> The conductive component, wherein the raw material of the metal component is any one of copper, copper alloy, aluminum or aluminum alloy.

[0034] <10> according to <8> The conductive component, wherein the raw material of the aforementioned metal component is copper or a copper alloy.

[0035] <11> according to <8> ~ <10> In any one of the conductive components, wherein, when the cross-cut test according to ISO 2409:1992 is performed, the number of grids in which the insulating coating is not peeled off from the metal component is 80% or more relative to the total number of grids.

[0036] Invention Effects

[0037] According to this disclosure, a method for manufacturing a conductive component that suppresses the reduction of insulation breakdown voltage and a conductive component manufactured by the above method are provided. Detailed Implementation

[0038] The following is a detailed description of one embodiment of this disclosure. However, this disclosure is not limited to the following embodiment. In the following disclosure, unless specifically stated otherwise, its constituent elements (including element steps, etc.) are not essential. Similarly, numerical values ​​and their ranges are not limiting of this disclosure.

[0039] In this disclosure, the numerical range represented by “~” includes the values ​​recorded before and after “~” as the lower limit and upper limit, respectively.

[0040] In the numerical ranges described in this disclosure, the upper or lower limit of one numerical range can be replaced by the upper or lower limit of another numerical range described in other stages. Furthermore, the upper or lower limit of the numerical range described in this disclosure can also be replaced by the values ​​shown in the embodiments.

[0041] In this disclosure, when multiple substances equivalent to each component are present in the composition, unless otherwise specified, the content of each component in the composition refers to the total content of the multiple substances present in the composition.

[0042] In this disclosure, when “or” or “or” is used to list multiple elements, unless otherwise expressly stated, the combination of multiple elements is not excluded as long as it does not create a technical contradiction.

[0043] In this disclosure, even when elements are expressed in a singular form, the existence of multiple elements is not excluded unless otherwise expressly stated, provided that no technical contradiction arises.

[0044] In this disclosure, multiple illustrative methods described individually can be combined to form new methods as long as they do not contradict each other.

[0045] Manufacturing Methods for Conductive Components

[0046] The method for manufacturing a conductive component disclosed herein includes: attaching powder to the surface of a metal component by electrostatic coating, wherein the powder comprises a thermoplastic polyimide containing structural units as shown in formula (1); and melting the attached powder by heating it to form an insulating coating.

[0047] In the IR spectrum of the aforementioned insulating coating, at least one of the following conditions must be met: 1487 cm⁻¹ -1 Absorption intensity I 1487 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1487 / I 1778 The dimensions are 3.0~5.0; and 1232cm. -1 Absorption intensity I 1232 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1232 / I 1778 The value is 3.0~5.0.

[0048] [Chemistry 5]

[0049]

[0050] [Chemistry 6]

[0051]

[0052] In the above formula (1), X is a direct bond, -SO2-, -CO-, -C(CH3)2-, -C(CF3)2- or -S-. R1, R2, R3 and R4 are each independently a hydrogen atom, alkyl, alkoxy, haloalkyl, haloalkoxy or halogen atom.

[0053] In formula (1) above, Y is any of the groups represented in formulas (2-1) to (2-4) above. In formulas (2-1) to (2-4) above, This indicates a bond, and aromatic rings can have substituents.

[0054] According to the method for manufacturing the conductive component disclosed herein, a method for manufacturing a conductive component that suppresses the reduction of insulation breakdown voltage can be provided. The function of the method for manufacturing the conductive component disclosed herein is not explicitly stated, but is presumed to be so.

[0055] As described above, in the case of using electrostatic coating, after spraying powder onto the substrate, the powder is heated at a certain high temperature for a period of time to melt it, thereby forming a smooth coating. However, depending on the composition of the powder, sometimes the composition of the powder changes due to decomposition or other reasons due to heating, and a coating with the desired physical properties cannot be obtained. In this case, the inventors discovered a new problem: when forming an insulating coating by electrostatic coating using a powder containing thermoplastic polyimide with structural units shown in formula (1), the insulation breakdown voltage of the formed coating decreases due to heating after electrostatic coating. Furthermore, they discovered a method for manufacturing conductive components in which the decrease in insulation breakdown voltage is suppressed.

[0056] In the method for manufacturing the conductive component disclosed herein, electrostatic coating and subsequent heating are performed. However, the heating is carried out in a manner that satisfies at least one of the following conditions in the IR spectrum of the insulating coating, thereby suppressing the decrease in insulation breakdown voltage: 1487 cm⁻¹ -1 The absorption strength is 1778cm -1 The ratio of absorption intensity I 1487 / I 1778 For sizes 3.0~5.0 and 1232cm -1 The absorption strength is 1778cm -1 The ratio of absorption intensity I 1232 / I 1778 The value is 3.0~5.0.

[0057] It should be noted that in the IR spectrum, at 1778 cm⁻¹ -1 The absorption peak that appears is from the imide group (O=CNC=O), at 1487 cm⁻¹. -1 The absorption peak that appears is from the carbon-carbon double bond (C=C) in the aromatic ring, at 1232 cm⁻¹. -1The absorption peaks that appear are from the ether bond (-O-).

[0058] Here, when a powder containing a thermoplastic polyimide with the structural unit shown in formula (1) is heated, the thermoplastic polyimide may decompose depending on the heating conditions such as heating temperature and heating time. In this case, typically, the aromatic ring decomposition or ether bond breakage is likely to occur in the structural unit shown in formula (1). On the other hand, the imide group contained in the structural unit shown in formula (1) has higher thermal stability than the aromatic ring and ether bond, and is therefore less prone to decomposition and breakage.

[0059] Therefore, the above ratio I 1487 / I 1778 It can be said to be an indicator of the degree of decomposition of aromatic rings in thermoplastic polyimides containing the structural units shown in formula (1) above. Additionally, compared to I... 1232 / I 1778 It can be said to be an indicator of the degree of ether bond breakage in thermoplastic polyimides containing the structural units shown in equation (1) above. Furthermore, in the IR spectrum of the insulating coating, when satisfying the ratio I... 1487 / I 1778 The value is 3.0~5.0, compared to I. 1232 / I 1778 When the value is at least one of 3.0 to 5.0, it means that in the thermoplastic polyimide containing the structural unit shown in the above formula (1), the decomposition of the aromatic ring or the breaking of the ether bond is suppressed.

[0060] As can be seen from the above, in this disclosure, the reduction in insulation breakdown voltage in the coating of a thermoplastic polyimide containing the structural unit shown in formula (1) is suppressed. Furthermore, this disclosure is not limited by the above-mentioned presumed mechanism.

[0061] Electrostatic Coating Method

[0062] The method for manufacturing a conductive component disclosed herein includes: attaching powder to the surface of a metal component by electrostatic coating, wherein the powder comprises a thermoplastic polyimide containing the structural unit shown in formula (1) above. In this disclosure, the electrostatic coating method is not particularly limited as long as it enables the powder containing the thermoplastic polyimide containing the structural unit shown in formula (1) above to adhere to the surface of the metal component.

[0063] [Powder]

[0064] (Thermoplastic polyimide containing the structural unit shown in formula (1))

[0065] -Structural unit shown in equation (1)-

[0066] The powder disclosed herein comprises a thermoplastic polyimide containing structural units as shown in formula (1) below. Preferably, the powder of this disclosure comprises a plurality of particles, wherein the plurality of particles comprise a thermoplastic polyimide containing structural units as shown in formula (1) below.

[0067] [Chemistry 7]

[0068]

[0069] In the above formula (1), X is a direct bond, -SO2-, -CO-, -C(CH3)2-, -C(CF3)2- or -S-.

[0070] From the viewpoint of suppressing the decrease in insulation breakdown voltage, X is preferably directly bonded, -C(CH3)2-, or -C(CF3)2-, and more preferably directly bonded. It should be noted that direct bonding means that the two aromatic rings adjacent to X are bonded by carbon-carbon single bonds. That is, X being directly bonded means that X is absent.

[0071] In the above formula (1), R1, R2, R3 and R4 are each independently a hydrogen atom, alkyl, alkoxy, haloalkyl, haloalkoxy or halogen atom.

[0072] The alkyl group can be straight-chain or branched. The number of carbon atoms in the alkyl group is preferably 1 to 40, more preferably 1 to 10. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, 2-ethylbutyl, and n-hexyl.

[0073] Alkoxy groups can be linear or branched. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, and n-hexoxy.

[0074] The haloalkyl group is preferably a group in which the hydrogen atom in the above-mentioned alkyl group is replaced by a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. Examples of haloalkyl groups include fluoromethyl and trifluoromethyl.

[0075] The haloalkoxy group is preferably a group in which the hydrogen atom of the above-mentioned alkoxy group is replaced by a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. Examples of haloalkoxy groups include fluoromethoxy groups.

[0076] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0077] From the viewpoint of suppressing the decrease in insulation breakdown voltage, R1, R2, R3, and R4 are each preferably hydrogen atoms or methyl groups, more preferably hydrogen atoms. R1, R2, R3, and R4 may be the same as or different from each other, but from the viewpoint of ease of synthesis, they are preferably the same as each other.

[0078] In formula (1) above, Y is a group represented by any of formulas (2-1) to (2-4) below. In formulas (2-1) to (2-4) below, This indicates a bond, and aromatic rings can have substituents.

[0079] [Chemistry 8]

[0080]

[0081] From the viewpoint of suppressing the reduction of insulation breakdown voltage, Y is preferably a group represented by formula (2-1) or formula (2-3), and more preferably represented by formula (2-1).

[0082] It should be noted that when Y in the above formula (1) is a group represented by formula (2-1) in formulas (2-1) to (2-4), the melting point of thermoplastic polyimide is most likely to increase. Therefore, when Y is a group represented by formula (2-1), the heating temperature required to form the coating is most likely to increase, and thus it can be said that it is easy to decompose when the coating is formed by melting it by heating. Therefore, as long as the reduction of insulation breakdown voltage is suppressed in the insulating coating of conductive components made with thermoplastic polyimide using the group represented by formula (2-1), the same applies to thermoplastic polyimide using the groups represented by formulas (2-2) to (2-4), and it can be said that the reduction of insulation breakdown voltage is sufficiently suppressed.

[0083] The substituents that the aromatic rings in formulas (2-1) to (2-4) may have are preferably hydrogen atoms, alkyl groups, alkoxy groups, haloalkyl groups, haloalkoxy groups, or halogen atoms. When the aromatic rings in formulas (2-1) to (2-4) have multiple substituents, the substituents may be the same or different from each other.

[0084] In this disclosure, "thermoplastic polyimide" refers to a polyimide that is thermoplastic. Thermoplastic polyimide is preferably a polyimide with a load deformation temperature of 200°C or higher.

[0085] Examples of thermoplastic polyimides containing structural units as shown in formula (1) include thermoplastic polyimides containing structural units as shown in formula (3), thermoplastic polyimide copolymers containing structural units as shown in formulas (4) and (5), and thermoplastic polyimide copolymers containing structural units as shown in formulas (6) and (7).

[0086] [Chemistry 9]

[0087]

[0088] [Chemistry 10]

[0089]

[0090] [Chemistry 11]

[0091]

[0092] Wherein, m in formula (4) and n in formula (5) represent the copolymerization ratio of the thermoplastic polyimide copolymer, and m / n (mol% / mol%) is preferably 4~99, more preferably 5~50, further preferably 6~20, particularly preferably 7~15, and most preferably 9.

[0093] [Chemistry 12]

[0094]

[0095] [Chemistry 13]

[0096]

[0097] Wherein, p in formula (6) and q in formula (7) represent the copolymerization ratio of the thermoplastic polyimide copolymer, and p / q (molar% / molar%) is preferably 0.01~100, more preferably 0.1~50, further preferably 0.3~10, particularly preferably 0.5~3, and most preferably 1.

[0098] The thermoplastic polyimide containing the structural unit shown in formula (1) is preferably a thermoplastic polyimide resin composed of the structural unit shown in formula (1). The coating formed from the thermoplastic polyimide containing the structural unit shown in formula (1) has excellent electrical properties and heat resistance.

[0099] The thermoplastic polyimide containing the structural unit shown in formula (1) is preferably a thermoplastic polyimide containing the structural unit shown in formula (3) above, and more preferably a thermoplastic polyimide composed of the structural unit shown in formula (3) above. The coating formed from the thermoplastic polyimide containing the structural unit shown in formula (3) above has superior electrical properties and heat resistance.

[0100] The thermoplastic polyimide containing the structural unit shown in formula (1) is preferably a thermoplastic polyimide copolymer containing the structural units shown in formula (4) and formula (5) above, and more preferably a thermoplastic polyimide composed of the structural units shown in formula (4) and formula (5) above.

[0101] The thermoplastic polyimide containing the structural unit shown in formula (1) is preferably a thermoplastic polyimide copolymer containing the structural units shown in formula (6) and formula (7) above, and more preferably a thermoplastic polyimide composed of the structural units shown in formula (6) and formula (7) above.

[0102] In thermoplastic polyimide containing the structural unit shown in formula (1), the structural unit shown in formula (1) may contain 1 to 10 types, 1 to 5 types, 1 or 2 types, or only 1 type.

[0103] -Structural units other than those shown in equation (1)-

[0104] The thermoplastic polyimide containing the structural unit shown in formula (1) can also be a thermoplastic polyimide copolymer composed of the structural unit shown in formula (1) and structural units other than those shown in formula (1).

[0105] The structural unit other than that shown in formula (1) can be, for example, a structural unit from an aromatic hydrocarbon that may have substituents, or a structural unit from an aliphatic hydrocarbon that may have substituents. Examples of substituents include halogen atoms, carboxyl groups, carbonyl groups, alkoxy groups, amino groups, amide groups, epoxy groups, (meth)acryloyl groups, vinyl groups, and sulfonyl groups. Multiple substituents may be present, and in the case of multiple substituents, the substituents may be the same or different from each other.

[0106] -Number average molecular weight of thermoplastic polyimides-

[0107] The number-average molecular weight of the thermoplastic polyimide containing the structural unit shown in formula (1) is preferably 3,000 to 100,000, more preferably 4,000 to 70,000, and even more preferably 5,000 to 40,000. It should be noted that, in this disclosure, the number-average molecular weight is determined by GPC (gel permeation chromatography).

[0108] In this disclosure, the number-average molecular weight can be determined using gel permeation chromatography (GPC). Specifically, 1.5 mL of 4-chlorophenol is added to 5 mg of the sample, and the mixture is slowly stirred at 130–140 °C. After the resulting solution is cooled to room temperature, 3.5 mL of chloroform is added. The solution is then filtered using a 0.2 μm filter to prepare the sample solution. The determination is performed using the prepared sample solution under the following conditions.

[0109] Detector: Differential refractive index detector RI (Tosoh RI-8020)

[0110] Pillars: 2 TSKgel GMHXL, 1 G2500HXL (7.8mm ID×300mm, manufactured by Tosoh)

[0111] Column temperature: 23℃

[0112] Solvent: 4-Chlorophenol / Chloroform (3 / 7) (volume / volume)

[0113] Flow rate: 0.8 mL / min, sample concentration: 1 mg / mL, injection volume: 0.3 mL

[0114] Standard sample: Monodisperse polystyrene manufactured by Tosoh

[0115] -Melt index of thermoplastic polyimide-

[0116] The melt index (hereinafter also referred to as "MI") of the thermoplastic polyimide containing the structural unit shown in formula (1) is not particularly limited, but is preferably 2 g / 10 min to 30 g / 10 min, more preferably 4 g / 10 min to 20 g / 10 min. In this disclosure, MI can be measured using a melt indexer (manufactured by Toyo Seiki Co., Ltd., model: A-371401705). Specifically, it can be measured under a load of 1.05 kg with the barrel temperature set to 400 °C according to JIS K7210 (ISO 1133). The unit of MI is g / 10 min.

[0117] -Logarithmic viscosity of thermoplastic polyimide-

[0118] The logarithmic viscosity of the thermoplastic polyimide containing the structural unit shown in formula (1) is not particularly limited, but is preferably 0.1 dl / g to 3.0 dl / g, more preferably 0.2 dl / g to 2.0 dl / g, even more preferably 0.3 dl / g to 1.5 dl / g, and particularly preferably 0.4 dl / g to 1.0 dl / g. When the logarithmic viscosity is 0.1 dl / g to 3.0 dl / g, the molecular weight of the thermoplastic polyimide is more preferably higher, the thermoplastic polyimide has excellent flowability, and therefore it is easier to form a smoother coating, and the mechanical strength of the formed coating is also better.

[0119] Logarithmic viscosity is measured in a mixed solvent of p-chlorophenol / phenol (90 / 10 by weight) at a concentration of 0.5 g / 100 ml by heating to 200 °C and then cooling to 35 °C. The definition of logarithmic viscosity is found on page 58 of the 1995 first edition of *Polymer Handbook*, published by Asakura Shoten and edited by the Japan Society for Analytical Chemistry.

[0120] - Glass transition temperature Tg of thermoplastic polyimide-

[0121] The lower limit of the glass transition temperature Tg of the thermoplastic polyimide containing the structural unit shown in formula (1) is not particularly limited, but from the viewpoint of heat resistance, it is preferably 200°C or higher, more preferably 210°C or higher, and even more preferably 220°C or higher. The upper limit of the glass transition temperature Tg is not particularly limited, but it is preferably 300°C or lower, more preferably 290°C or lower, and even more preferably 280°C or lower. The upper limit of the glass transition temperature Tg can be 270°C or lower, 260°C or lower, 250°C or lower, or 240°C or lower.

[0122] In this disclosure, the glass transition temperature (Tg) can be determined using a differential scanning calorimeter (DSC220C type, manufactured by Seiko Instruments). Specifically, approximately 5 mg of material is sealed in an aluminum measuring dish and placed in the differential scanning calorimeter. It is then heated from room temperature to 450°C at a rate of 10°C / min. To allow the substance to be measured to completely melt, it is held at 450°C for 5 minutes, and then cooled to 30°C at a rate of 10°C / min. After being held at 30°C for 5 minutes, it is heated a second time to 450°C at a rate of 10°C / min. The point of displacement corresponding to the glass transition is defined as the glass transition temperature (Tg).

[0123] -Melting point of thermoplastic polyimide-

[0124] The lower limit of the melting point of the thermoplastic polyimide containing the structural unit shown in formula (1) is not particularly limited, but from the viewpoint of heat resistance, it is preferably 340°C or higher, more preferably 350°C or higher, even more preferably 360°C or higher, even more preferably 370°C or higher, even more preferably 380°C or higher, and even more preferably 385°C or higher. The upper limit of the melting point of the thermoplastic polyimide resin is not particularly limited, but from the viewpoint of molding processability, it is preferably 430°C or lower, more preferably 420°C or lower, even more preferably 410°C or lower, even more preferably 400°C or lower, even more preferably 395°C or lower, and even more preferably 390°C or lower.

[0125] In this disclosure, the melting point can be determined using a DSC (Differential Scanning Calorimeter, manufactured by Shimadzu Corporation, DT-40 series, "DSC-41M").

[0126] -Methods for obtaining thermoplastic polyimides-

[0127] {synthesis}

[0128] The thermoplastic polyimide containing the structural unit shown in formula (1) can be synthesized by reacting an aromatic diamine compound (e.g., the compound shown in formula (8) below) and an aromatic tetracarboxylic dianhydride (e.g., the compound shown in formula (9) below) as raw materials in the presence or absence of an organic solvent, and imidizing the resulting polyamic acid. The manufacturing process can utilize the conditions of known polyimide manufacturing methods. It should be noted that at least a portion of the raw materials of at least one of the above-mentioned aromatic diamine compound and the above-mentioned aromatic tetracarboxylic dianhydride can be a biomass-derived compound. That is, the thermoplastic polyimide containing the structural unit shown in formula (1) of this disclosure can be a biomass-derived thermoplastic polyimide.

[0129] [Chemistry 14]

[0130]

[0131] In equation (8) above, the definitions of X and R1~R4 are the same as those in equation (1) above.

[0132] [Chemistry 15]

[0133]

[0134] In the above formula (9), the definition of Y is the same as that in the above formula (1). It should be noted that when Y is formula (2-1) without substituents on the aromatic ring, the aromatic tetracarboxylic acid dianhydride in formula (9) becomes formula (11) as described later, and formula (11) is pyromellitic dianhydride.

[0135] More specifically, thermoplastic polyimides containing the structural units shown in formula (1) can be synthesized by the following method. A diamine (4,4'-bis(3-aminophenoxy)biphenyl (m-BP)) shown in formula (10) is dehydrated and co-condensed with a tetracarboxylic acid dianhydride (pyromellitic dianhydride (PMDA)) shown in formula (11) to obtain a thermoplastic polyimide composed of the structural units shown in formula (3).

[0136] [Chemistry 16]

[0137]

[0138] [Chemistry 17]

[0139]

[0140] The synthesis of thermoplastic polyimides containing the structural unit shown in formula (1) can be achieved by using known imidization reactions.

[0141] Regarding the amount of the raw material compound used, it is typically 0.90 to 0.99 equivalents of tetracarboxylic dianhydride relative to 1 equivalent of diamine. The amount of the raw material compound used is preferably 0.93 to 0.985 equivalents, more preferably 0.95 to 0.98 equivalents. When the amount of the raw material compound used is 0.90 to 0.99 equivalents, the molecular weight of the thermoplastic polyimide is sufficiently increased, the thermoplastic polyimide exhibits excellent flowability, thus facilitating the formation of a smoother coating, and the resulting coating also possesses superior mechanical strength.

[0142] In the synthesis of thermoplastic polyimides, phthalic anhydride or similar substances are preferably used to cap the reaction ends of the molecules. By capping the reaction ends, the thermal stability of thermoplastic polyimide resins is significantly improved.

[0143] The reaction is particularly preferably carried out in an organic solvent. Examples of organic solvents include N,N-dimethylformamide, N,N-diethylacetamide, N,N-dimethoxyacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolinone, N-methylcaprolactam, 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl] ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, pyrrolidone, methylpyridine, dimethyl sulfoxide, dimethyl sulfone, tetramethylurea, hexamethylphosphoramide, phenol, o-cresol, m-cresol, p-cresol, p-chlorophenol, anisole, benzene, toluene, and xylene. Organic solvents can be used alone or in mixtures of two or more.

[0144] The reaction temperature is typically between room temperature (e.g., 25°C) and 250°C, preferably between 140°C and 200°C. The reaction pressure is not particularly limited and can be fully implemented under normal atmospheric pressure. The reaction time varies depending on the type of solvent and the reaction temperature, but is typically preferred to be between 4 and 24 hours. As a method of imidization, polyamic acid, as a precursor, is heated to 100°C to 300°C for imidization, or chemical imidization is performed using an imidizing agent such as acetic anhydride, thereby obtaining the desired thermoplastic polyimide.

[0145] {Commercially Available Products}

[0146] Thermoplastic polyimides containing the structural unit shown in Formula (1) can be commercially available products. Examples of commercially available thermoplastic polyimides containing the structural unit shown in Formula (1) include AURUM (registered trademark) PD400, PD450, PD500A and PD500M (all manufactured by Mitsui Chemicals Co., Ltd.).

[0147] (additive)

[0148] The particles contained in the powder of this disclosure may include components (i.e., additives) other than thermoplastic polyimide containing the structural unit shown in formula (1). As an additive, there are no particular limitations, and for example, it may be at least one selected from the group consisting of carbon fiber, glass fiber, potassium titanate fiber, aluminum borate fiber, metal fiber, ceramic fiber, boron fiber, silicon carbide fiber, asbestos fiber, rock wool fiber and aramid fiber.

[0149] Additives may contain, as needed, at least one of the following, within a range that does not impair the properties of thermoplastic polyimide: mica, synthetic mica, wollastonite, talc, silicone oil, fluorinated oil, glass beads, molybdenum disulfide, clay, silica, alumina, diatomaceous earth, hydrated alumina, white sand hollow microspheres, carbon nanotubes, calcium carbonate, hydrotalcite, fluorine, graphite (e.g., artificial graphite, natural graphite (e.g., flake graphite, scaly graphite, earthy graphite) etc.), metal particles (e.g., metals, alloys etc.), pigment particles (e.g., inorganic pigments, organic pigments etc.), lubricants, release agents, stabilizers, colorants, crystal nucleating agents, ultraviolet absorbers, infrared reflectors, infrared absorbers, or antireflective agents.

[0150] The additive may contain at least one of the following substances, within a range that does not impair the properties of the thermoplastic polyimide: various liquid crystal polymers, thermoplastic resins (e.g., fluoropolymers, polyetherimides, polyether nitriles, polyether ketones, polyether ether ketones, polyether ketone ketones, polyether ketone ketones, polyamide imides, polyether sulfones, polysulfones, polyarylates and / or polyphenylene sulfides), or thermosetting resins (e.g., epoxy resins, polybenzimidazole resins, polyimide resins, etc.).

[0151] When the particles contained in the powder disclosed herein contain additives, there are no particular restrictions on the content of the additives and the content of thermoplastic polyimide, which can be appropriately selected according to the type of additives, etc.

[0152] From the viewpoint of superior electrical properties and heat resistance, the content of thermoplastic polyimide containing the structural unit shown in formula (1) in the particles contained in the powder of this disclosure is preferably 50% to 100% by mass, more preferably 60% to 100% by mass, even more preferably 70% to 100% by mass, even more preferably 80% to 100% by mass, and even more preferably 90% to 100% by mass. That is, from the viewpoint of superior electrical properties and heat resistance, the content of additives in the particles contained in the powder of this disclosure is preferably 0% to 50% by mass, more preferably 0% to 40% by mass, even more preferably 0% to 30% by mass, even more preferably 0% to 20% by mass, and even more preferably 0% (i.e., not contained) to 10% by mass.

[0153] (particle size of powder)

[0154] In the method for manufacturing the conductive component disclosed herein, the powder of this disclosure preferably satisfies at least one of the following conditions: the cumulative 50% of the particle size d50 in the volume-based particle size distribution is 5 μm to 100 μm; and the cumulative 90% of the particle size d90 in the volume-based particle size distribution is 10 μm to 200 μm. By making the particle size of the powder uniform, it is easy to manufacture conductive components with uniform thickness and high surface smoothness. From the viewpoint of manufacturing conductive components with uniform thickness and high surface smoothness, the powder of this disclosure more preferably satisfies both of the following conditions: the cumulative 50% of the particle size d50 in the volume-based particle size distribution is 5 μm to 100 μm; and the cumulative 90% of the particle size d90 in the volume-based particle size distribution is 10 μm to 200 μm.

[0155] It should be noted that in this disclosure, the cumulative particle size distribution reaching any percentage (%) in the volumetric particle size distribution is determined by laser diffraction scattering (wet method). More specifically, the powder is mixed with distilled water (Fujifilm and Kodenki Chemical Co., Ltd., refractive index 1.33) and dispersed for 2 minutes using a built-in ultrasonic homogenizer at an output power of 25W. Then, the particle size distribution is measured in a laser diffraction / scattering particle size distribution measuring device (Microtrac Corporation, model: Microtrac MT3300EXII) under the following particle conditions.

[0156] Transmittance: Transmittance; Refractive Index: 1.81; Shape: Non-spherical

[0157] The cumulative 50% of the particle size d50 in the volumetric particle size distribution is more preferably 5 μm to 100 μm, further preferably 10 μm to 70 μm, and particularly preferably 20 μm to 40 μm.

[0158] The cumulative 90% of the particle size d90 in the volumetric particle size distribution is more preferably 10 μm to 200 μm, further preferably 25 μm to 150 μm, and particularly preferably 40 μm to 100 μm.

[0159] (Particle shape of powder)

[0160] Particle shapes in powders can include, for example, spherical, elliptical, needle-like, plate-like, rod-like, conical, cylindrical, cubic, cuboid, diamond-like, star-like, and irregular shapes. Particles in powders can be solid, hollow, or porous particles, etc.

[0161] (Thermoplastic polyimide and additives in the powder)

[0162] In this disclosure, the powder containing the thermoplastic polyimide with the structural unit shown in formula (1) can be a powder containing the thermoplastic polyimide with the structural unit shown in formula (1) and an additive in the same particle. Alternatively, the powder containing the thermoplastic polyimide with the structural unit shown in formula (1) can also be a mixed powder formed by mixing the powder containing the thermoplastic polyimide with the structural unit shown in formula (1) with the powder containing the additive.

[0163] [Metal Components]

[0164] (raw materials)

[0165] There are no particular restrictions on the materials used for the metal components. Preferred raw materials for the metal components are any one of gold, gold alloys, silver, silver alloys, copper, copper alloys, iron, ferroalloys containing steel, aluminum, aluminum alloys, tungsten, or tungsten alloys. From the viewpoints of excellent electrical conductivity and productivity, copper, copper alloys, iron, ferroalloys containing steel, aluminum, or aluminum alloys are more preferred as raw materials for the metal components; copper, copper alloys, aluminum, or aluminum alloys are even more preferred; and copper or copper alloys are particularly preferred.

[0166] If a metal component is heated to approximately 400°C or higher in air, an oxide coating is easily formed if the raw material of the metal component is copper, copper alloy, aluminum, or aluminum alloy. However, the aforementioned oxide coating formed on copper, copper alloy, aluminum, or aluminum alloy has poor compatibility with thermoplastic polyimide containing the structural unit shown in formula (1). Therefore, if an insulating coating is formed after heating the metal component to approximately 400°C or higher, as in the existing flow impregnation method, an insulating coating will form on the oxide coating, reducing the adhesion between the metal component and the insulating coating.

[0167] On the other hand, as in the manufacturing method of the conductive component disclosed herein, if it is an electrostatic coating method, a powder containing thermoplastic polyimide with structural units shown in formula (1) is used to cover the surface of a metal component that has almost no oxide coating, and then heating is performed to form an insulating coating. Therefore, even if the raw material of the metal component is copper, copper alloy, aluminum or aluminum alloy, it is difficult to form an oxide coating, and the adhesion between the insulating coating and the metal component can be sufficiently improved.

[0168] Examples of gold alloys include alloys containing 40% or more gold by mass, alloys containing 80% or more gold by mass, and alloys containing 99% or more gold by mass. Examples of silver alloys include alloys containing 40% or more silver by mass, alloys containing 80% or more silver by mass, and alloys containing 99% or more silver by mass. Examples of copper alloys include alloys containing 40% or more copper by mass, alloys containing 80% or more copper by mass, and alloys containing 99% or more copper by mass. Specifically, examples of copper alloys include beryllium copper, titanium copper, phosphor bronze, Cosne alloy, red copper, brass, cupronickel, bronze, and zinc cupronickel. Examples of iron alloys include alloys containing 40% or more iron by mass, alloys containing 80% or more iron by mass, and alloys containing 99% or more iron by mass. Specifically, examples of iron alloys include stainless steel, mild steel, carbon steel, iron-nickel alloys, and steel. Examples of aluminum alloys include alloys containing 40% by mass or more of aluminum, alloys containing 80% by mass or more of aluminum, and alloys containing 99% by mass or more of aluminum. Examples of tungsten alloys include alloys containing 40% by mass or more of tungsten, alloys containing 80% by mass or more of tungsten, and alloys containing 99% by mass or more of tungsten.

[0169] There is no particular limitation on the lower limit of the purity of the metal in the metal component. The purity of any one of the metals selected from gold, silver, copper, iron, aluminum, or tungsten is preferably 50.00% by mass or more, more preferably 60.00% by mass or more, further preferably 70.00% by mass or more, particularly preferably 80.00% by mass or more, even more preferably 90.00% by mass or more, further more preferably 95.00% by mass or more, even more preferably 98.00% by mass or more, particularly more preferably 99.00% by mass or more, even more preferably 99.50% by mass or more, significantly more preferably 99.90% by mass or more, and most preferably 99.95% by mass or more. There is no particular limitation on the upper limit of the purity of the metal in the metal component, and it can be 100.00% by mass.

[0170] From the viewpoint of use as a conductive component, copper is preferably pure copper (i.e., copper purity of 99.90% by mass or higher). Examples of pure copper include oxygen-free copper (copper purity of 99.96% by mass or higher), low-oxygen copper, tough copper (copper purity of 99.90% by mass or higher), and phosphorus-deoxidized copper (copper purity of 99.90% by mass or higher). It should be noted that the oxygen content of low-oxygen copper is 30 ppm or less, preferably 20 ppm or less. From the viewpoint of excellent conductivity, oxygen-free copper is more preferred.

[0171] (Surface treatment)

[0172] From the viewpoint of improving the adhesion between the metal component and the coating, the metal component disclosed herein can be surface treated. There are no particular limitations on the surface treatment method; examples include roughening treatment, polishing, UV ozone treatment, excimer laser treatment, alkali treatment, silane coupling agent treatment, and combinations thereof. As a surface treatment, from the viewpoint of improving the adhesion between the metal component and the coating, roughening treatment is preferred. As a roughening treatment, dry roughening treatment or wet roughening treatment can be mentioned. Examples of dry roughening treatments include corona discharge treatment, plasma treatment, sandblasting (e.g., sandblasting, blowing, or shot peening), scrubbing and grinding, and rolling treatment using embossing rollers. Examples of wet roughening treatments include etching.

[0173] The arithmetic mean roughness Ra of the surface of the metal component disclosed herein is preferably 0.01 μm to 100 μm, more preferably 0.05 μm to 50 μm, and even more preferably 0.1 μm to 30 μm. In this disclosure, the arithmetic mean roughness Ra of the surface can be measured using a surface roughness tester (MITUTOYO, Surftest SV-3200) according to JIS B 0601-1994 (ISO 4287:1997).

[0174] (shape)

[0175] There are no particular restrictions on the shape of the metal components; for example, they can be plate-shaped, rod-shaped, coil-shaped, ring-shaped, L-shaped, U-shaped, or T-shaped. There are also no particular restrictions on the size of the metal components; they can be appropriately determined according to their intended use.

[0176] [Electrostatic Coating]

[0177] (device)

[0178] Electrostatic coating equipment used for electrostatic coating can be any known electrostatic coating equipment. Examples of such equipment include electrostatic spray guns such as the Encore XT manufactured by Nordson.

[0179] There are two methods for charging powder: triboelectric charging and corona charging. Triboelectric charging involves treating the powder with triboelectric charge before spraying. Corona charging involves treating the powder with corona discharge before spraying.

[0180] (Voltage)

[0181] The applied voltage for electrostatic coating is preferably 10kV to 300kV, more preferably 20kV to 200kV, even more preferably 30kV to 100kV, and even more preferably 50kV to 70kV. By applying the above voltage to the powder, the powder becomes charged, resulting in higher adhesion efficiency to the metal component and a more uniform thickness of the adhered powder.

[0182] (Number of electrostatic coating operations)

[0183] In the manufacturing method of the conductive component disclosed herein, there is no particular limitation on the number of times the electrostatic coating is performed on the metal component. To obtain a coating of desired thickness, the metal component may be electrostatically coated 1 to 10 times, 1 to 5 times, 1 to 3 times, 1 or 2 times, or even just once. It should be noted that when multiple electrostatic coatings are performed, it is preferable to perform the heating (i.e., annealing) described later after each electrostatic coating.

[0184] (Powder thickness)

[0185] The thickness of the powder (powder layer) adhering to the metal component is preferably 1 μm to 1500 μm, more preferably 5 μm to 1000 μm, even more preferably 5 μm to 500 μm, even more preferably 10 μm to 300 μm, and even more preferably 20 μm to 200 μm. Regarding the thickness of the powder adhering to the metal component, the thickness before and after adhesion is measured, and the thickness at three different locations is measured and averaged.

[0186] [Formation of the insulating coating]

[0187] The method for manufacturing the conductive component disclosed herein includes: heating (i.e., annealing) the attached powder to melt it and form an insulating coating. The heating of the attached powder can be performed by heating the entire metal component to which the powder is attached.

[0188] (heating)

[0189] The heating conditions for the attached powder only need to meet at least one of the following conditions, without particular limitation: in the IR spectrum of the insulating coating, 1487 cm⁻¹ -1 Absorption intensity I 1487 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1487 / I 1778 The dimensions are 3.0~5.0 cm, and 1232 cm. -1 Absorption intensity I 1232 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1232 / I 1778 The value is 3.0 to 5.0. As a heating condition, by adjusting at least one of the heating temperature and heating time, the above ratio (I) can be achieved. 1487 / I 1778 Or I1232 / I 1778 () becomes the desired numerical range.

[0190] From the viewpoint of suppressing the decrease in insulation breakdown voltage, the temperature at which the attached powder is heated is preferably 390°C to 430°C, more preferably 392°C to 420°C, even more preferably 393°C to 410°C, and particularly preferably 395°C to 405°C.

[0191] From the viewpoint of being able to suppress the decrease in insulation breakdown voltage, the heating time of the attached powder is preferably more than 0 minutes and less than 30 minutes, more preferably 1 minute to 20 minutes, even more preferably 2 minutes to 15 minutes, and particularly preferably 3 minutes to 10 minutes.

[0192] -Melting-

[0193] After the powder is applied to the surface of a metal component using an electrostatic coating method, a powder layer containing the powder is formed on the surface of the metal component. However, through the aforementioned heating, the particles in the powder containing thermoplastic polyimide with structural units shown in formula (1) melt and adjacent particles fuse together. As a result, the powder layer is smoothed, and an insulating coating is formed on the surface of the metal component. When the aforementioned heating is performed, the powder containing thermoplastic polyimide with structural units shown in formula (1) melts.

[0194] (Number of heating operations)

[0195] In the method for manufacturing conductive components disclosed herein, when performing multiple electrostatic coatings on a metal component, as described above, it is preferable to perform heating once after each electrostatic coating. That is, when performing multiple electrostatic coatings on a metal component, it is preferable to repeatedly perform electrostatic coating and heating.

[0196] The thermoplastic polyimide containing the structural unit shown in formula (1) is prone to decomposition due to high temperature and / or long-term heating. Therefore, when the metal component is heated multiple times, the multiple heatings are preferably within the above-mentioned preferred heating temperature range and the multiple heatings are preferably within the above-mentioned preferred heating time range. Furthermore, the total time of the multiple heatings is more preferably within the above-mentioned preferred heating time range.

[0197] (Insulating film)

[0198] -Thickness of the insulating coating-

[0199] The thickness of the insulating coating is preferably 1μm to 1500μm, more preferably 5μm to 1000μm, even more preferably 5μm to 500μm, even more preferably 10μm to 300μm, and even more preferably 20μm to 200μm.

[0200] Regarding the thickness of the insulating coating, the thickness of the metal before and after adhesion was measured, and the thickness at three different points was averaged. Regarding the thickness after powder adhesion, the thickness of the metal component after heating was measured.

[0201] -Arithmetic mean roughness of the insulating coating surface-

[0202] The arithmetic mean roughness Ra of the insulating coating surface is preferably 0.1 μm to 100 μm, more preferably 0.3 μm to 50 μm, and even more preferably 0.5 μm to 30 μm. It should be noted that the arithmetic mean roughness Ra can be measured using a surface roughness meter (MITUTOYO, Surftest SV-3200) according to JIS B 0601-1994 (ISO 4287:1997). It is preferable to heat the attached powder so that the surface of the insulating coating falls within the aforementioned arithmetic mean roughness Ra range, thereby smoothing the powder layer.

[0203] -IR spectrum of insulating coating-

[0204] In this disclosure, IR spectra can be determined using an infrared spectrophotometer via a micro-transmission method.

[0205] In the IR spectrum of the insulating coating, from the viewpoint of suppressing the decrease in insulation breakdown voltage, it is preferable to satisfy at least one of the following conditions: 1487 cm⁻¹ -1 Absorption intensity I 1487 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1487 / I 1778 The dimensions are 3.0~5.0; and 1232cm. -1 Absorption intensity I 1232 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1232 / I 1778 The range is 3.0 to 5.0. Furthermore, from the viewpoint of suppressing the decrease in insulation breakdown voltage, the IR spectrum of the insulating coating more preferably satisfies the following two conditions: 1487 cm⁻¹ -1 Absorption intensity I 1487 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1487 / I 1778 The dimensions are 3.0~5.0; and 1232cm. -1 Absorption intensity I 1232 With 1778cm -1 Absorption intensity I 1778The ratio of I 1232 / I 1778 The value is 3.0~5.0.

[0206] In comparison I 1487 / I 1778 Compared to I 1232 / I 1778 When both of these values ​​are less than 3.0, it can be said that the ether bonds in the thermoplastic polyimide containing the structural unit shown in formula (1) are significantly cleaved, and the aromatic rings are significantly decomposed, resulting in a reduction in the insulation breakdown voltage to less than 50 kV / mm and a deterioration in electrical properties. On the other hand, if I 1487 / I 1778 And I 1232 / I 1778 If at least one of them is 3.0 or higher, then the chemical structure of the thermoplastic polyimide containing the structural unit shown in formula (1) is maintained to some extent, and the insulation breakdown voltage is 50kV / mm or higher, so it can be said that the electrical properties are good.

[0207] It should be noted that the I in the chemical structure of the thermoplastic polyimide containing the structural unit shown in formula (1) before heating 1487 / I 1778 The value is 5.0, I 1232 / I 1778 The value is 5.0. This is due to the ratio of imide groups, carbon-carbon double bonds (C=C) from aromatic rings, and ether bonds present in the chemical structure of the thermoplastic polyimide containing the structural unit shown in formula (1) before heating.

[0208] Than I 1487 / I 1778 More preferably, it is 3.1 to 5.0; even more preferably, it is 3.1 to 4.5; and particularly preferably, it is 3.2 to 4.0. Compared to I... 1232 / I 1778 More preferably, it is 3.1 to 5.0; even more preferably, it is 3.1 to 4.5; and particularly preferably, it is 3.1 to 4.0.

[0209] -Cross-cross test for insulating coating-

[0210] When performing the cross-cut test according to ISO 2409:1992 (JIS K5600-5-6), the ratio of the number of grids in which the insulating film has not been peeled off from the metal component to the total number of grids is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. The ratio of the number of grids in which the insulating film has not been peeled off from the metal component to the total number of grids is, for example, 100% or less.

[0211] It should be noted that the details of the cross-cut test are as follows. More specifically, the insulating film applied to the planar area of ​​the metal component is cut into a grid pattern with a width of 1 mm, forming 25 squares. After applying adhesive tape (NICHIBAN Co., Ltd. cellophane tape) to the gridded areas of the insulating film, the tape is quickly pulled off at an angle of approximately 60 degrees. Then, the grids after the tape is removed are observed, and the percentage (%) of the number of squares where the insulating film was not peeled off from the metal component relative to the total number of squares (25) is calculated.

[0212] Conductive Components

[0213] The conductive component of this disclosure comprises a metal component and an insulating film covering at least a portion of the surface of the metal component. The insulating film comprises a thermoplastic polyimide containing structural units as shown in formula (1), and in the IR spectrum, satisfies at least one of the following conditions: 1487 cm⁻¹ -1 Absorption intensity I 1487 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1487 / I 1778 3.0~5.0; 1232cm -1 Absorption intensity I 1232 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1232 / I 1778 The value is 3.0~5.0.

[0214] [Chemistry 18]

[0215]

[0216] [Chemistry 19]

[0217]

[0218] In the above formula (1), X is a direct bond, -SO2-, -CO-, -C(CH3)2-, -C(CF3)2- or -S-. R1, R2, R3 and R4 are each independently a hydrogen atom, alkyl, alkoxy, haloalkyl, haloalkoxy or halogen atom.

[0219] In formula (1) above, Y is any of the groups represented in formulas (2-1) to (2-4) above. In formulas (2-1) to (2-4) above, This indicates a bond, and aromatic rings can have substituents.

[0220] The definition, examples, and preferred embodiments of formula (1) in the conductive component of this disclosure are the same as those of formula (1) described in the above-described method for manufacturing the conductive component of this disclosure. Furthermore, the definitions, examples, and preferred embodiments of the conductive component in the conductive component of this disclosure are also the same as those of the conductive component described in the above-described method for manufacturing the conductive component of this disclosure.

[0221] In the conductive components of this disclosure, an insulating film covers at least a portion of the surface of the metal component. More preferably, the insulating film covers 50% or more of the surface area of ​​the metal component, even more preferably 70% or more, even more preferably 90% or more, and still more preferably the entire surface.

[0222] Example

[0223] The present disclosure will be described in more detail below through embodiments, but the present disclosure is not limited to the following embodiments as long as it does not depart from its spirit.

[0224] Synthesis of thermoplastic polyimide

[0225] Thermoplastic polyimide is synthesized according to the following steps.

[0226] It should be noted that the chemical formula of 4,4'-bis(3-aminophenoxy)biphenyl (m-BP) is represented by the above formula (10).

[0227] The chemical formula of pyromellitic dianhydride (PMDA) is represented by the above formula (11).

[0228] 4,4'-Oxydiphenylamine (ODA) is represented by the following formula (12).

[0229] The chemical formula of biphenyl tetracarboxylic dianhydride (BPDA) is represented by the following formula (13).

[0230] [Chemistry 20]

[0231]

[0232] [Chemistry 21]

[0233]

[0234] [Synthesis of thermoplastic polyimide composed of the structural units shown in formula (3) above (1)]

[0235] Prepare a container equipped with a stirrer, reflux cooler, water separator, and nitrogen inlet pipe. Add 3.680 kg (10 mol) of 4,4'-bis(3-aminophenoxy)biphenyl, 2.071 kg (9.5 mol) of pyromellitic dianhydride, 0.148 kg (1.0 mol) of phthalic anhydride, and 21.53 kg of m-cresol to the container. Then, heat to 200 °C under a nitrogen atmosphere with stirring. During this process, confirm that approximately 350 ml of water has distilled off. Further react at 200 °C for 6 hours. Then, cool to room temperature and add 10.8 kg of toluene. Filter to obtain a yellow polyimide powder. Wash the polyimide powder with toluene and dry at 180 °C for 24 hours to obtain 5.46 kg (98.5% by mass) of polyimide powder. The polyimide powder was further sieved through a sieve with a mesh size of 90 μm and dried at 200°C for 8 hours to obtain polyimide powder (a thermoplastic polyimide composed of the structural units shown in formula (3), hereinafter also referred to as "PI-1").

[0236] The physical properties of PI-1 (number-average molecular weight, melt index, glass transition temperature Tg, melting point, and particle size) are shown in Table 1. It should be noted that the methods for determining each physical property are as described above.

[0237] [Synthesis of thermoplastic polyimide composed of the structural units shown in formula (3) above (2)]

[0238] Prepare a container equipped with a stirrer, reflux cooler, water separator, and nitrogen inlet pipe. Add 2.873 kg (7.8 mol) of 4,4'-bis(3-aminophenoxy)biphenyl, 1.570 kg (7.25 mol) of pyromellitic dianhydride, 0.148 kg (1.0 mol) of phthalic anhydride, and 21.53 kg of m-cresol to the container. Then, heat to 200 °C under a nitrogen atmosphere with stirring. During this process, confirm that approximately 350 ml of water has distilled off. Further reaction is carried out at 200 °C for 6 hours. Then, cool to room temperature and add 10.8 kg of toluene. Filter to obtain a yellow polyimide powder. Wash the polyimide powder with toluene and dry at 180 °C for 24 hours to obtain 5.46 kg (98.5% by mass) of polyimide powder. The polyimide powder was further sieved through a sieve with a mesh size of 90 μm and dried at 200°C for 8 hours to obtain polyimide powder (thermoplastic polyimide composed of structural units shown in formula (3), hereinafter also referred to as "PI-2").

[0239] The physical properties of the obtained PI-2 (number-average molecular weight, melt index, glass transition temperature Tg, melting point and particle size) are shown in Table 1.

[0240] [Synthesis of thermoplastic polyimide composed of structural units shown in formulas (4) and (5) above]

[0241] Prepare a container equipped with a stirrer, reflux cooler, water separator, and nitrogen inlet pipe. Add 3.312 kg (9.0 mol) of 4,4'-bis(3-aminophenoxy)biphenyl, 0.2 kg (1.0 mol) of 4,4'-oxodiphenylamine, 2.071 kg (9.5 mol) of pyromellitic dianhydride, 0.148 kg (1.0 mol) of phthalic anhydride, and 21.53 kg of m-cresol to the container. Then, heat to 200 °C under a nitrogen atmosphere with stirring. During this period, confirm that approximately 350 ml of water has distilled off. Further react at 200 °C for 6 hours. Then, cool to room temperature and add 10.8 kg of methanol. Then, filter to separate the product, obtaining a yellow polyimide powder. After washing the polyimide powder with methanol, dry it at 180 °C for 24 hours to obtain 5.26 kg (98% by mass) of polyimide powder. The polyimide powder was further sieved through a sieve with a mesh size of 90 μm and dried at 200°C for 8 hours to obtain polyimide powder (thermoplastic polyimide (m / n=9 / 1) composed of the structural units shown in the above formula (4) and above formula (5), hereinafter also referred to as "PI-3").

[0242] The physical properties of the obtained PI-3 (number-average molecular weight, melt index, glass transition temperature Tg, melting point and particle size) are shown in Table 1.

[0243] [Synthesis of thermoplastic polyimide composed of structural units shown in formulas (6) and (7) above]

[0244] Prepare a container equipped with a stirrer, reflux cooler, water separator, and nitrogen inlet pipe. Add 3.684 kg (10.0 mol) of 4,4'-bis(3-aminophenoxy)biphenyl, 1.081 kg (4.96 mol) of pyromellitic dianhydride, 1.459 kg (4.86 mol) of biphenyltetracarboxylic dianhydride, 0.148 kg (1.0 mol) of phthalic anhydride, and 21.53 kg of m-cresol to the container. Then, heat to 200°C under a nitrogen atmosphere with stirring. During this period, confirm that approximately 350 ml of water has distilled off. Further react at 200°C for 6 hours. Then, cool to room temperature and add 10.8 kg of methanol. Then, filter to obtain a yellow polyimide powder. The polyimide powder was washed with methanol and dried at 180°C for 24 hours to obtain 5.46 kg (yield 98.5% by mass) of polyimide powder. The polyimide powder was further sieved through a sieve with a mesh size of 90 μm and dried at 200°C for 8 hours to obtain polyimide powder (thermoplastic polyimide composed of the structural units shown in the above formulas (6) and (7) (p / q=1 / 1), hereinafter also referred to as "PI-4").

[0245] The physical properties of the obtained PI-4 (number-average molecular weight, melt index, glass transition temperature Tg, melting point and particle size) are shown in Table 1.

[0246] [Table 1]

[0247]

[0248] <Metal Components>

[0249] As a metal component, an oxygen-free copper plate (100mm×200mm×1mm, C1020) is prepared. The arithmetic mean surface roughness Ra of the metal component is 0.1μm.

[0250] <Manufacturing of Conductive Components>

[0251] [Example 1]

[0252] Using an electrostatic coating apparatus (Nordson Encore XT), thermoplastic polyimide PI-1 powder was electrostatically coated onto a metal component at a voltage of 60 kV, allowing the powder to adhere to the metal component. Next, the powder-coated metal component was heated (annealed) at 400°C for 7 minutes using an electric furnace (YamatoScientific FO810). Further, electrostatic coating was performed again, followed by heating at 400°C for 4 minutes. Further, electrostatic coating was performed again, followed by heating at 400°C for 3 minutes, to obtain an insulating coating. That is, the electrostatic coating and heating process was repeated three times. It should be noted that the powder was adhered to the metal component with an insulating coating thickness of 0.2 mm. Furthermore, the arithmetic mean surface roughness Ra of the insulating coating was 0.5 μm.

[0253] [Example 2]

[0254] Using an electrostatic coating apparatus (Nordson Encore XT), thermoplastic polyimide PI-2 powder was electrostatically coated onto the metal component at a voltage of 60 kV, allowing the powder to adhere to the metal component. It should be noted that the powder was adhered to the metal component so that the resulting insulating film thickness was 0.05 mm. Next, using an electric furnace (YamatoScientific FO810), the powder-coated metal component was heated to 400°C for 2.5 minutes to obtain the insulating film.

[0255] [Example 3]

[0256] Using an electrostatic coating apparatus (Nordson Encore XT), thermoplastic polyimide PI-1 powder was electrostatically coated onto the metal component at a voltage of 60 kV, allowing the powder to adhere to the metal component. It should be noted that the powder was adhered to the metal component so that the resulting insulating film thickness was 0.03 mm. Next, the powder-coated metal component was heated at 400°C for 3 minutes using an electric furnace (YamatoScientific FO810) to obtain the insulating film.

[0257] [Example 4]

[0258] Using an electrostatic coating apparatus (Nordson Encore XT), thermoplastic polyimide PI-1 powder was electrostatically coated onto the metal component at a voltage of 60 kV, allowing the powder to adhere to the metal component. It should be noted that the powder was adhered to the metal component so that the resulting insulating film thickness was 0.05 mm. Next, the powder-coated metal component was heated at 400°C for 10 minutes using an electric furnace (YamatoScientific FO810) to obtain the insulating film.

[0259] [Example 5]

[0260] Except that the powder was attached to the metal component in such a way that the thickness of the resulting insulating film was 0.2 mm, the same procedure as in Example 4 was followed to obtain the insulating film.

[0261] [Example 6]

[0262] Except for electrostatic coating using thermoplastic polyimide PI-3 powder, the same procedure as in Example 4 was followed to obtain an insulating coating.

[0263] [Example 7]

[0264] Except for electrostatic coating using thermoplastic polyimide PI-4 powder, the same procedure as in Example 4 was followed to obtain an insulating coating.

[0265] [Example 8]

[0266] Except for heating at 420°C, the same procedure as in Example 4 was followed to obtain the insulating coating.

[0267] [Example 9]

[0268] Except for heating for 20 minutes, the same procedure as in Example 8 was followed to obtain the insulating coating.

[0269] [Comparative Example 1]

[0270] Except for heating at 450°C for 5 minutes, the same procedure as in Example 4 was followed to obtain the insulating coating.

[0271] [Comparative Example 2]

[0272] Except for heating at 450°C for 30 minutes, the same procedure as in Example 4 was followed to obtain the insulating coating.

[0273] [Comparative Example 3]

[0274] Except for heating at 450°C for 60 minutes, the same procedure as in Example 4 was followed to obtain the insulating coating.

[0275] Evaluation of conductive components

[0276] [IR Spectroscopy]

[0277] The IR spectrum of the insulating coating on the conductive component was measured using an infrared spectrophotometer (Agilent Cary 620 / 670) via microscopy-transmission method. The detailed measurement conditions are as follows.

[0278] • Measurement area: 4000cm -1 ~600cm -1

[0279] • Resolution: 4cm -1

[0280] Total number of times: 128

[0281] Based on the IR spectra measured from the insulating coatings of each conductive component, the 1487 cm⁻¹ was calculated. -1 The absorption strength is 1778cm -1 The ratio of absorption intensity I 1487 / I 1778 and 1232cm -1 The absorption strength is 1778cm -1 The ratio of absorption intensity I 1232 / I 1778 It should be noted that 1778cm -1 The peak originates from the imide group, at 1487 cm⁻¹. -1 The peak originates from a carbon-carbon double bond (C=C) in an aromatic ring, at 1232 cm⁻¹. -1 The peak originates from the ether bond (-O-).

[0282] The results are recorded in Table 2.

[0283] Insulation breakdown voltage

[0284] The insulation breakdown voltage (BDV) of the insulating film on conductive components is determined according to IEC 60243-1, using an insulation breakdown tester and the short-time breakdown method (test environment 23°C, 50%RH). The measured value is the average value of the number of tests n=3.

[0285] Furthermore, the insulation breakdown voltage (kV / mm) per 1 mm thickness of the insulating film is calculated from the measured insulation breakdown voltage (kV).

[0286] The results are recorded in Table 2.

[0287] [Cross-cross test]

[0288] The insulating film was subjected to a cross-cut test according to ISO 2409:1992 (JIS K5600-5-6). More specifically, the insulating film, placed on a flat area of ​​the metal component, was cut into a grid pattern with a width of 1 mm, forming 25 grids. After applying adhesive tape (NICHIBAN Co., Ltd., cellophane tape) to the grid areas of the insulating film, the tape was quickly pulled off at an angle of approximately 60 degrees. The grids after the tape was removed were observed, and the percentage (%) of the number of grids in which the insulating film was not peeled off from the metal component was calculated relative to the total number of grids (25).

[0289] The results are recorded in Table 2.

[0290] [Table 2]

[0291]

[0292] As shown in Table 2, the insulation breakdown voltage is high in the conductive components obtained in Examples 1 to 9. Therefore, the conductive component manufacturing method of this disclosure provides a conductive component in which the reduction of insulation breakdown voltage is suppressed.

[0293] The disclosure of Japanese Patent Application No. 2023-219957, filed on December 26, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as those specifically described and individually incorporated herein by reference.

Claims

1. A method for manufacturing a conductive component, comprising: Powder is applied to the surface of a metal component by electrostatic coating, wherein the powder comprises a thermoplastic polyimide containing structural units as shown in formula (1); as well as By heating the attached powder, the powder is melted to form an insulating coating. The IR spectrum of the insulating coating satisfies at least one of the following conditions: 1487 cm⁻¹ -1 Absorption intensity I 1487 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1487 / I 1778 The dimensions are 3.0~5.0; and 1232cm. -1 Absorption intensity I 1232 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1232 / I 1778 The value is 3.0~5.

0. [Chemistry 1] [Chemistry 2] In formula (1), X is a direct bond, -SO2-, -CO-, -C(CH3)2-, -C(CF3)2-, or -S-, and R1, R2, R3, and R4 are each independently a hydrogen atom, alkyl group, alkoxy group, haloalkyl group, haloalkoxy group, or halogen atom. In formula (1), Y is a group represented by any of formulas (2-1) to (2-4) above. This indicates a bond, and aromatic rings can have substituents.

2. The method for manufacturing a conductive component according to claim 1, wherein, The heating temperature is 390℃~430℃.

3. The method for manufacturing a conductive component according to claim 1 or 2, wherein, The heating time is more than 0 minutes and less than 30 minutes.

4. The method for manufacturing a conductive component according to claim 1 or 2, wherein, The powder satisfies at least one of the following conditions: the cumulative 50% of the particle size d50 in the volumetric particle size distribution is 5 μm to 100 μm; and the cumulative 90% of the particle size d90 in the volumetric particle size distribution is 10 μm to 200 μm.

5. The method for manufacturing a conductive component according to claim 1 or 2, wherein, The raw material for the metal component is any one of copper, copper alloy, iron, steel-containing iron alloy, aluminum, or aluminum alloy.

6. The method for manufacturing a conductive component according to claim 1 or 2, wherein, The metal component is a surface-treated metal component.

7. The method for manufacturing a conductive component according to claim 1 or 2, wherein, The thickness of the insulating coating is 5μm to 1000μm.

8. A conductive component comprising a metal component and an insulating coating covering at least a portion of the surface of the metal component. The insulating coating comprises a thermoplastic polyimide containing structural units as shown in formula (1), which, in the IR spectrum, satisfies at least one of the following conditions: 1487 cm⁻¹ -1 Absorption intensity I 1487 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1487 / I 1778 3.0~5.0; 1232cm -1 Absorption intensity I 1232 With 1778cm -1 Absorption intensity I 1778 The ratio of I 1232 / I 1778 The value is 3.0~5.

0. [Chemistry 3] [Chemistry 4] In formula (1), X is a direct bond, -SO2-, -CO-, -C(CH3)2-, -C(CF3)2-, or -S-, and R1, R2, R3, and R4 are each independently a hydrogen atom, alkyl group, alkoxy group, haloalkyl group, haloalkoxy group, or halogen atom. In formula (1), Y is a group represented by any of formulas (2-1) to (2-4) above. This indicates a bond, and aromatic rings can have substituents.

9. The conductive member according to claim 8, wherein, The raw material for the metal component is any one of copper, copper alloy, aluminum, or aluminum alloy.

10. The conductive member according to claim 8, wherein, The raw material for the metal component is copper or a copper alloy.

11. The conductive member according to any one of claims 8 to 10, wherein, When the cross-cut test according to ISO 2409:1992 is performed, the number of grids in which the insulating coating is not peeled off from the metal component is more than 80% of the total number of grids.

Images