Coil wire manufacturing method

Abstract

To provide a method for manufacturing a coil wire which can reduce manufacturing cost.SOLUTION: A method for manufacturing a coil wire is a method for manufacturing a coil wire 1 including a conductor wire 11, and an insulation film 12 coating the conductor wire 11. A method for manufacturing a coil wire includes the steps of: spraying a coating liquid in which a fluorine-containing acrylic resin is dissolved in a volatile solvent onto the conductor wire 11; and standing the conductor wire 11 to which the coating liquid is applied, and volatilizing a volatile solvent.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing coil wire. [Background technology]

[0002] Fluorine-containing resins have excellent electrical insulation properties and are sometimes used as a material for insulating coatings on coil wires. For example, Patent Document 1 describes an electric wire having an insulating layer made of a thermosetting resin and a fluororesin. The electric wire described in Patent Document 1 is formed by applying a mixture obtained by mixing a thermosetting resin solution and a fluororesin organosol onto a conductor and baking it. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2011 / 024809 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Incidentally, fluoropolymer resins tend to contain water as an impurity. When attempting to apply a fluoropolymer resin containing water as an impurity to a water-repellent conductor, the fluoropolymer resin may be repelled by the conductor, preventing the formation of a proper insulating film.

[0005] In this case, although an insulating coating can be formed by baking as described in Patent Document 1, for example, the manufacturing process is increased, which leads to an increase in manufacturing costs. In other words, the conventional method for manufacturing coil wires has the problem that the manufacturing cost of coil wires having an insulating coating made of fluororesin cannot be suppressed.

[0006] This disclosure was made to solve these problems and aims to provide a method for manufacturing coil wire that can suppress manufacturing costs.

Means for Solving the Problem

[0007] A method for manufacturing a coil wire according to an aspect of the present disclosure is a method for manufacturing a coil wire including a conductive wire and an insulating coating that coats the conductive wire, a step of spray-applying a coating liquid in which a fluorine-containing acrylic resin is dissolved in a volatile solvent to the conductive wire, and a step of allowing the conductive wire coated with the coating liquid to stand and volatilizing the volatile solvent. It is a method for manufacturing a coil wire.

[0008] According to such a configuration, a resin material having adhesiveness to the conductive wire can be rapidly deposited on the conductive wire under normal temperature and pressure. Therefore, the conductive wire can be appropriately coated with an insulating coating without going through processes such as over-baking. As a result, the method for manufacturing a coil wire according to an aspect of the present disclosure can suppress the manufacturing cost of the coil wire.

[0009] In the method for manufacturing a coil wire according to an aspect of the present disclosure, the volatile solvent may be one or more selected from the group consisting of water, ethanol, and acetone. According to such a configuration, the method for manufacturing a coil wire according to an aspect of the present disclosure can improve the safety of the manufacturing process.

[0010] In the method for manufacturing a coil wire according to an aspect of the present disclosure, the coating liquid may contain 5% by mass or more and 19% by mass or less of a fluorine-containing acrylic resin based on the total amount of the coating liquid. According to such a configuration, the method for manufacturing a coil wire according to an aspect of the disclosure can improve the film-forming property of the insulating coating.

Effects of the Invention

[0011] According to the present disclosure, a method for manufacturing a coil wire capable of suppressing the manufacturing cost can be provided.

Brief Description of the Drawings

[0012] [Figure 1] It is a cross-sectional view showing the configuration of the coil wire according to the first embodiment. [Figure 2] It is a cross-sectional view showing the configuration of the coil wire according to the first embodiment. [Figure 3] It is a flowchart showing the manufacturing method of the coil wire according to the first embodiment.

Mode for Carrying Out the Invention

[0013] (First Embodiment) <Configuration of Coil Wire> Hereinafter, the first embodiment according to the present disclosure will be described in detail with reference to the drawings. First, the configuration of the coil wire manufactured by the manufacturing method of the coil wire according to the present embodiment will be described in detail.

[0014] FIG. 1 and FIG. 2 are cross-sectional views showing the configuration of the coil wire according to the first embodiment. More specifically, FIG. 1 is a cross-sectional view when the coil wire according to the first embodiment is cut perpendicular to the central axis of the coil wire, and FIG. 2 is a cross-sectional view when the coil wire according to the first embodiment is cut parallel to the central axis of the coil wire. Of course, the right-handed xyz orthogonal coordinates shown in FIGS. 1 and 2 are for convenience of explaining the positional relationship of the components and are common among the drawings.

[0015] The coil wire 1 is a metal wire coated with an insulating film. After the coil wire 1 is wound in a spiral shape and a current is passed through it, it operates as a coil. The coil wire 1 may be, for example, a coil wire used for a stator coil mounted on an automobile. The coil wire 1 includes a conductor 11 and an insulating film 12.

[0016] The conductor 11 is a metal wire through which a current flows during the operation of the coil. The conductor 11 is, for example, a metal wire made of copper, aluminum, or the like. Since the conductor 11 is a metal wire made of copper, aluminum, or the like, it has water repellency. The conductor 11 needs to have its sides properly insulated in order to prevent short circuits in the coil. Therefore, the sides of the conductor 11 are covered with an insulating coating 12.

[0017] As shown in Figure 1, the wire 11 according to this embodiment has a circular cross-section when cut perpendicular to its central axis. However, the shape of the cross-section of the wire 11 is not limited to a circle; for example, it may be rectangular.

[0018] The insulating coating 12 is a coating formed on the side surface of the conductor 11, and is made of a fluorine-containing acrylic resin. The insulating coating 12 electrically insulates the conductor 11 in order to suppress short circuits in the coil.

[0019] <Manufacturing method for coil wire> Next, the method for manufacturing a coil wire according to this embodiment will be described in detail with reference to the drawings. Figure 3 is a flowchart of the method for manufacturing a coil wire according to the first embodiment.

[0020] In the method for manufacturing coil wire according to this embodiment, an insulating coating 12 is formed on the side surface of the conductor 11. First, in the method for manufacturing a coil wire according to this embodiment, a coating solution obtained by dissolving a fluorine-containing acrylic resin in a volatile solvent is spray-applied to the conductor 11 (step S1). Subsequently, the wire 11 is left to stand to allow the volatile solvent to evaporate (step S2). Once the volatile solvent has evaporated, the fluorine-containing acrylic resin precipitates on the wire 11, forming an insulating film 12.

[0021] Here, the fluorine-containing acrylic resin contained in the coating solution has adhesive properties, or in other words, good adhesion, to metal components due to the acrylic structure in the compound. Furthermore, the volatile solvent contained in the coating solution readily evaporates at normal pressure and temperature.

[0022] The fluorine-containing acrylic resin contained in the coating liquid adheres to metal and is therefore not repelled by the conductor 11. Furthermore, the volatile solvent contained in the coating liquid evaporates easily at normal pressure and temperature, so it can be removed from the conductor 11 without heating. As a result, the coil wire manufacturing method according to this embodiment can properly form an insulating film 12 on the conductor 11 without performing processes such as baking.

[0023] <Composition of the coating solution> The coating solution used in step S1 will be described in more detail below. As described above, the coating solution according to this embodiment is a coating solution obtained by dissolving a fluorine-containing acrylic resin in a volatile solvent. In other words, the coating solution according to this embodiment contains a fluorine-containing acrylic resin and a volatile solvent as components.

[0024] The fluorine-containing acrylic resin contained in the coating liquid according to this embodiment precipitates on the conductor 11 as the volatile solvent evaporates, forming an insulating film 12. In other words, the fluorine-containing acrylic resin contained in the coating liquid according to this embodiment becomes the main component of the insulating film 12.

[0025] The fluorine-containing acrylic resin is preferably a compound represented by formulas (1) and (2) below, and may also be a mixture of multiple compounds represented by formulas (1) and (2) below. Hereinafter, the compounds represented by formulas (1) and (2) below will be referred to as compound 1 and compound 2, respectively.

[0026] [ka] ...Equation (1) [ka] ...Equation (2)

[0027] however, R 11 , R12 , R 21 , and R 22 is a hydrogen atom, a fluorine atom, an alkyl group, or a fluoroalkyl group, R 13 is a hydrogen atom, a fluorine atom, a methyl group, or a fluoromethyl group, R 14 and R 24 is a hydrogen atom, an alkyl group which may have a functional group at the terminal, or a fluoroalkyl group which may have a functional group at the terminal, n is an integer of 1 or more, R 21 , R 22 , R 23 , and R 24 When there are a plurality of R 21 , R 22 , R 23 , and R 24 may be the same as or different from each other, Compound 1 and Compound 2 contain at least one fluorine atom.

[0028] Compound 1 is acrylic acid, an acrylic acid ester, methacrylic acid, or a methacrylic acid ester in which some or all of the hydrogen atoms are substituted with fluorine atoms. Compound 2 is polyacrylic acid, a polyacrylic acid ester, polymethacrylic acid, or a polymethacrylic acid ester in which some or all of the hydrogen atoms are substituted with fluorine atoms. Note that the terminal structure of Compound 2 is not particularly limited, and may be, for example, a hydrogen atom, a fluorine atom, an alkyl group, or a fluoroalkyl group.

[0029] As described above, Compound 1 and Compound 2 contain fluorine atoms. According to such a configuration, the insulation property of the insulating film 12 containing Compound 1 and Compound 2 as main components is improved. Furthermore, compounds 1 and 2 contain carboxyl groups or carboxylic acid ester bonds as substructures. Since these substructures interact with metal atoms on the surface of the conductor 11, the insulating coating 12, which mainly contains compounds 1 and 2, has good adhesion to the conductor 11.

[0030] R 11 and R 12 R is a hydrogen atom, a fluorine atom, an alkyl group, or a fluoroalkyl group. 11 and R 12 From the viewpoint of improving the hydrophobicity of compound 1, it is preferable that at least one of the components is an alkyl group or a fluoroalkyl group. As the hydrophobicity of compound 1 improves, the amount of water contained as an impurity in the fluorine-containing acrylic resin decreases. Here, metals such as copper and aluminum used as the material for the conductor 11 are water-repellent. Therefore, as the amount of water contained as an impurity in the fluorine-containing acrylic resin decreases, the adhesion between the conductor 11 and the insulating coating 12 improves further.

[0031] R 21 and R 22 R is a hydrogen atom, a fluorine atom, an alkyl group, or a fluoroalkyl group. 21 and R 22 From the viewpoint of ease of synthesis and increasing the degree of polymerization, it is preferable that n be a hydrogen atom or a fluorine atom. When the degree of polymerization of compound 2 increases, that is, when n in formula (2) increases, the hydrophobicity of the fluorine-containing acrylic resin improves, and as a result, the adhesion between the conductor 11 and the insulating coating 12 is further improved.

[0032] R 14 and R 24 R is a hydrogen atom, an alkyl group which may have a functional group at its terminal, or a fluoroalkyl group which may have a functional group at its terminal. 14 and R 24 From the viewpoint of improving hydrophobicity, it is preferable that the element be an alkyl group or a fluoroalkyl group. R 14 and R 24However, in the case of an alkyl group or fluoroalkyl group having a functional group at its terminal, examples of the functional group at the terminal include alkoxy groups, fluoroalkoxy groups, and tosyl groups.

[0033] The proportion of compound 1, compound 2, or a mixture thereof contained in the coating liquid according to this embodiment is preferably 5% by mass or more of the total amount of the coating liquid. In other words, the coating liquid according to this embodiment preferably contains 5% by mass or more of a fluorine-containing acrylic resin based on the total amount of the coating liquid. With this configuration, the method for manufacturing coil wire according to this embodiment can form an insulating coating 12 on the conductor 11 while suppressing the occurrence of uncoated areas.

[0034] Furthermore, the proportion of compound 1, compound 2, or a mixture thereof contained in the coating liquid according to this embodiment is preferably 19% by mass or less, and particularly preferably 15% by mass or less, relative to the total amount of the coating liquid. In other words, the coating solution according to this embodiment preferably contains 19% by mass or less of a fluorine-containing acrylic resin based on the total amount of the coating solution. With this configuration, the method for manufacturing coil wire according to this embodiment can form an insulating coating 12 with a uniform thickness on the conductor 11.

[0035] In other words, from the viewpoint of film-forming properties, the coating solution according to this embodiment preferably contains 5% to 19% by mass of fluorine-containing acrylic resin relative to the total amount of the coating solution.

[0036] The volatile solvent contained in the coating liquid according to this embodiment refers to a solvent that readily evaporates under normal temperature and pressure. For example, the volatile solvent may refer to a mixture of volatile organic compounds defined in accordance with the World Health Organization's definition, with water added. Furthermore, the volatile solvent may include a mixed solvent obtained by mixing multiple volatile solvents.

[0037] In particular, from the viewpoint of safety, the volatile solvent according to this embodiment is preferably one or more selected from the group consisting of water, ethanol, and acetone. In other words, the volatile solvent according to this embodiment is preferably water, ethanol, acetone, or a mixed solution of two or more of these solvents.

[0038] With this configuration, the solvent evaporates from the applied coating liquid without the need for heating processes, and the fluorine-containing acrylic resin rapidly precipitates as an insulating film 12.

[0039] The coating solution according to this embodiment may contain one or more additives. However, the term "additive" here refers to a compound added to the coating solution for the purpose of suppressing the deterioration of the insulating film 12 or imparting further functionality to the insulating film 12. For example, the coating solution according to this embodiment may contain polymerization inhibitors, colorants, and the like as additives.

[0040] The coating solution according to this embodiment may be a commercially available coating agent containing a fluorine-containing acrylic resin, diluted with a volatile solvent to an appropriate concentration. Furthermore, the coating solution according to this embodiment may contain by-products from the synthesis of the fluorine-containing acrylic resin and the volatile solvent.

[0041] As described above, the method for manufacturing a coil wire according to this disclosure involves applying a coating liquid containing a volatile solvent that readily evaporates at room temperature and atmospheric pressure, and a fluorine-containing acrylic resin that has high adhesion to the conductor wire 11, to the side surface of the conductor wire 11 by spray application. With this configuration, the method for manufacturing coil wire according to this disclosure can form an insulating coating 12 without performing processes such as baking. As a result, the method for manufacturing coil wire according to this embodiment can reduce the manufacturing cost of the coil wire. [Examples]

[0042] The present disclosure will be described in more detail below based on examples and comparative examples, but the present disclosure is not limited to these examples.

[0043] [Example 1] A commercially available fluorine-containing agent was dissolved in water to a concentration of 8% by mass relative to the total volume of the coating solution, thereby preparing the coating solution. The prepared coating solution was sprayed onto a copper plate measuring 100 mm in width, 100 mm in length, and 2 mm in thickness, and left to stand for 15 seconds to create a test specimen.

[0044] [Comparative Example 1] A commercially available fluorine-containing agent was dissolved in water to a concentration of 8% by mass relative to the total volume of the coating solution, thereby preparing the coating solution. A copper plate measuring 100 mm in width and length, 100 mm in height, and 2 mm in thickness was immersed in the prepared coating solution for XX seconds, and then left to stand for 10 seconds to create a test specimen.

[0045] [Comparative Example 2] Test specimens were prepared in the same manner as in Comparative Example 1, except that a commercially available agent containing fluorine was dissolved in water at a concentration of 4% by mass relative to the total volume of the coating solution.

[0046] [Comparative Example 3] Test specimens were prepared in the same manner as in Comparative Example 1, except that a commercially available agent containing fluorine was dissolved in water at a concentration of 20% by mass relative to the total volume of the coating solution.

[0047] <Film Forming Evaluation> The test specimens obtained in the above examples and comparative examples were observed with the naked eye to check for any areas where film formation was not achieved and for any irregularities on the insulating coating. The results are shown in Table 1.

[0048] [Table 1]

[0049] As a result of the above film formation evaluation, as shown in Table 1, it was found that using the coating solutions of Example 1 and Comparative Example 1 resulted in the formation of insulating films with better properties compared to using the coating solutions of Comparative Examples 2 and 3. Furthermore, it was found that an insulating film could be formed by spraying the coating solution as in Example 1, similar to the case in Comparative Example 1.

[0050] Although the present invention has been described above in reference to the embodiments described above, the present invention is not limited to the configuration of the embodiments described above, and of course includes various modifications, alterations, and combinations that can be made by a person skilled in the art within the scope of the claims of the present patent application. [Explanation of symbols]

[0051] 1. Coil wire 11 Conductor 12. Insulating coating

Claims

[Claim 1] A method for manufacturing a coil wire comprising a conductor and an insulating coating covering the conductor, A step of spraying a coating solution, obtained by dissolving a fluorine-containing acrylic resin in a volatile solvent, onto the wire, The process includes a step of allowing the wire to stand after the coating liquid has been applied to it to evaporate the volatile solvent, The coating liquid contains 5% by mass or more and 19% by mass or less of a fluorine-containing acrylic resin relative to the total amount of the coating liquid. The volatile solvent includes water. A method for manufacturing coil wire.

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