Thermoplastic polyimide, insulated wire, and method for manufacturing insulated wire

Abstract

A thermoplastic polyimide is provided that can be used to make insulated wires with excellent productivity and heat resistance. [Solution] The thermoplastic polyimide of this disclosure has a recurring structural unit containing an imide bond. The recurring structural unit satisfies all of the following (a) to (c). (a) The main chain contains 5 to 10 aromatic rings. (b) Five to ten of the aforementioned aromatic rings include at least one substituted aromatic ring in which at least one hydrogen atom is substituted with an alkyl group, The total number of carbon atoms in the alkyl groups of all the substituted aromatic rings is between 2 and 6. (c) Five to ten of the aforementioned aromatic rings include at least one divalent aromatic ring, All of the aforementioned divalent aromatic rings are linked in a para coordination.

Description

[Technical Field]

[0001] This disclosure relates to thermoplastic polyimide, insulated wires, and methods for manufacturing insulated wires. [Background technology]

[0002] Polyimide possesses excellent mechanical properties and heat resistance. Therefore, it is widely used as an insulating material in various components (e.g., industrial materials, automobiles, electrical and electronic equipment, etc.).

[0003] Patent Document 1 discloses a method for producing polyimide. In this method, a specific diamine and a specific tetracarboxylic dianhydride are reacted in a specific ratio, and the resulting polyamic acid is imidized thermally or chemically. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 3083215 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, the fluidity of the polyimide molten material disclosed in Patent Document 1 may not be sufficient. To improve the productivity of insulated wires, polyimide with high fluidity in the molten state is required. An insulated wire comprises a conductor and an insulating coating covering the conductor. The insulating coating contains polyimide.

[0006] The embodiments of this disclosure have been made in view of the above, and aim to provide a thermoplastic polyimide, an insulated wire, and a method for manufacturing an insulated wire that can be made into an insulated wire with excellent productivity and heat resistance. [Means for solving the problem]

[0007] Means for solving the above problems include the following embodiments. <1> A thermoplastic polyimide having a constituent repeating unit containing an imide bond, wherein the constituent repeating unit satisfies all of the following (a) to (c). (a) The main chain contains 5 to 10 aromatic rings. (b) The 5 to 10 aromatic rings include at least one substituted aromatic ring in which at least one hydrogen atom is substituted with an alkyl group, and the total number of carbon atoms of the alkyl groups of all the substituted aromatic rings is 2 to 6. (c) The 5 to 10 aromatic rings include at least one divalent aromatic ring, and all of the divalent aromatic rings are linked in a para configuration. <2> The thermoplastic polyimide according to <1> above, wherein the constituent repeating unit has a constituent repeating unit represented by the following formula (I).

[0008]

Chemical formula

[0010]

Chem.

[0011] In Formulae (X-1) to (X-5), * indicates the bonding position. In Formula (I), Y represents a group represented by the following Formula (Y-1), Formula (Y-2), Formula (Y-3), Formula (Y-4), Formula (Y-5), Formula (Y-6), Formula (Y-7), or Formula (Y-8).

[0012]

Chem.

[0013] In Formulae (Y-1) to (Y-8), * indicates the bonding position. <3> The thermoplastic polyimide according to <2>, wherein the constitutional repeating unit represented by Formula (I) includes a constitutional repeating unit represented by the following Formula (I-1).

[0014]

Chem.

[0015] <4> The thermoplastic polyimide according to <3>, wherein in Formula (I-1), Y is a group represented by Formula (Y-1). <5> The thermoplastic polyimide according to <2>, wherein the constitutional repeating unit represented by Formula (I) includes a constitutional repeating unit represented by the following Formula (I-2).

[0016]

Chem.

[0017] <6> The thermoplastic polyimide according to <5>, wherein in Formula (I-2), Y is a group represented by Formula (Y-1). <7> The glass transition temperature Tg is 250 °C or higher, and In accordance with JIS K7210-1:2014, the melt flow rate is 10 g / 10 min or more at 400°C and a load of 1.05 kg. <1> ~ <6> A thermoplastic polyimide as described in any one of the following. <8> It comprises a conductor and an insulating film covering the conductor, The insulating film, <1> ~ <7> An insulated wire containing a thermoplastic polyimide as described in any one of the following. <9> The insulating film is made of one type of thermoplastic polyimide, <8> Insulated wire as described above. <10> The aforementioned <8> or <9> A method for manufacturing an insulated wire, which is used to manufacture the insulated wire described above. To prepare the composition containing the thermoplastic polyimide and the conductor, The molten material of the composition is applied to the conductor flowing at a line speed of 10 m / min to 25 m / min. A method for manufacturing insulated wires, including [the specified part of the invention]. [Effects of the Invention]

[0018] According to embodiments of this disclosure, a thermoplastic polyimide, an insulated wire, and a method for manufacturing an insulated wire are provided that can be made into an insulated wire with excellent productivity and heat resistance. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 is a cross-sectional view of an example of an insulated wire according to this disclosure. [Figure 2] Figure 2 is a schematic diagram of an example of a manufacturing apparatus for insulated wires according to the present disclosure. [Modes for carrying out the invention]

[0020] In this disclosure, the "~" symbol indicating a numerical range is used to mean that the numbers before and after it are included as the lower and upper limits, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. In numerical ranges described in this disclosure, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. In this disclosure, the term "process" includes not only independent processes but also any process that cannot be clearly distinguished from other processes, as long as its intended purpose is achieved. In this disclosure, when referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, it means the total amount of all substances present in the composition unless otherwise specified.

[0021] (1) Thermoplastic polyimide The thermoplastic polyimide of this disclosure (hereinafter also simply referred to as "thermoplastic polyimide") has a recurring unit comprising an imide bond. The recurring unit satisfies all of the following (a) to (c). (a) The main chain contains 5 to 10 aromatic rings. (b) Five to ten of the aforementioned aromatic rings include at least one substituted aromatic ring in which at least one hydrogen atom is substituted with an alkyl group, The total number of carbon atoms in the alkyl groups of all the substituted aromatic rings (hereinafter also referred to as the "total number of carbon atoms in the alkyl groups") is between 2 and 6. (c) Five to ten of the aforementioned aromatic rings include at least one divalent aromatic ring, All of the aforementioned divalent aromatic rings are linked in a para coordination.

[0022] In this disclosure, "thermoplastic polyimide" refers to a polyimide having thermoplastic properties. More specifically, "thermoplastic polyimide" refers to a polyimide whose main chain has divalent flexible linking groups (for example, an ether group (-O-), a carbonyl group (-CO-), a sulfonyl group (-SO2-), an isopropylidene group (-C(CH3)2-), a methylene group (-CH2-), a perfluoroisopropylidene group (-C(CF3)2-), etc.).

[0023] Because the thermoplastic polyimide of this disclosure has the above-described structure, it can be used to make an insulated wire with excellent productivity and heat resistance. This effect is presumed to be due to, but is not limited to, the following reasons. In this disclosure, the constituent repeating units satisfy (a) and (b). When the constituent repeating units satisfy (a), the thermoplastic polyimide of this disclosure can improve the heat resistance of insulated wires due to the rigidity of the main chain and the action of intermolecular forces (e.g., π-π stacking of aromatic rings, Coulomb forces, and hydrogen bonds). In this disclosure, the constituent repeating units satisfy (b). When the constituent repeating units satisfy (b), the fluidity of the molten thermoplastic polyimide is improved. As a result, the thermoplastic polyimide of this disclosure can improve the productivity of insulated wires. From the above, it is presumed that the thermoplastic polyimide of this disclosure can be used to make an insulated wire with excellent productivity and heat resistance.

[0024] The melt flow rate (hereinafter also referred to as "MFR") of thermoplastic polyimide is not particularly limited. From the viewpoint of improving the productivity of insulated wires, the MFR of thermoplastic polyimide is preferably 10 g / 10 min or more, more preferably 14 g / 10 min or more. The MFR of thermoplastic polyimide may be 60 g / 10 min or less, 30 g / 10 min or less, or 19 g / 10 min or less. If the MFR of thermoplastic polyimide is 60 g / 10 min or less, sagging may occur in the molten insulating film coated on the conductor during the manufacture of the current collector, and the accuracy of the insulating film thickness may not be stable. The MFR of thermoplastic polyimide may be between 10 g / 10 min and 60 g / 10 min. MFR is measured at 400°C and under a load of 1.05 kg, in accordance with JIS K7210-1:2014.

[0025] The glass transition temperature (hereinafter also referred to as "Tg") of thermoplastic polyimide is not particularly limited. From the viewpoint of improving the heat resistance of insulated wires, the Tg of thermoplastic polyimide is preferably 250°C or higher, more preferably 260°C or higher. The Tg of thermoplastic polyimide may be 280°C or lower, or 260°C or lower. The Tg of thermoplastic polyimide may be between 250°C and 280°C. The method for measuring Tg is the same as that described in the examples.

[0026] Preferably, the glass transition temperature (Tg) is 250°C or higher, and the melt flow rate, measured at 400°C and a load of 1.05 kg in accordance with JIS K7210-1:2014, is 10 g / 10 min or higher. This improves the productivity and heat resistance of the insulated wire.

[0027] (1.1) Constituent repeating units The constituent repeating units of thermoplastic polyimide satisfy all of the following conditions (a) to (c). (a) The main chain contains 5 to 10 aromatic rings. (b) Five to ten of the aforementioned aromatic rings include at least one substituted aromatic ring in which at least one hydrogen atom is substituted with an alkyl group, The total number of carbon atoms in the alkyl groups of all the substituted aromatic rings (i.e., the total number of carbon atoms in the alkyl groups) is between 2 and 6. (c) Five to ten of the aforementioned aromatic rings include at least one divalent aromatic ring, All of the aforementioned divalent aromatic rings are linked in a para coordination.

[0028] The number of aromatic rings in the main chain of the constituent repeating unit is between 5 and 10. If the number of aromatic rings is less than 5, the heat resistance of the insulated wire may not be sufficient. If the number of aromatic rings is more than 10, the synthesis of thermoplastic polyimide may become difficult. The number of aromatic rings may be between 6 and 8, or between 6 and 7. Examples of aromatic rings include phenylene groups, naphthylene groups, anthracenylene groups, and biphenylylene groups.

[0029] The number of substituted aromatic rings in the main chain of the constituent repeating unit is 1 or more, may be between 1 and 6, or may be 2. The number of alkyl groups in one substituted aromatic ring is 1 or more, and may be 1 to 6, 2 to 4, 4, or 2. The total number of carbon atoms in all alkyl groups of the substituted aromatic rings included in the main chain of the constituent repeating unit (i.e., the total number of carbon atoms in the alkyl groups) is between 2 and 6. If the total number of carbon atoms in the alkyl groups is 1, the productivity of insulated wires may be insufficient. If the total number of carbon atoms in the alkyl groups is greater than 6, the synthesis of thermoplastic polyimides may become difficult. The total number of carbon atoms in the alkyl groups may be between 2 and 4, may be 4, or may be 2. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl groups.

[0030] The number of divalent aromatic rings in the 5 to 10 aromatic rings is at least 1, may be 5 to 9, 5 to 8, 5 to 6, 5, or 6. The divalent aromatic rings linked by para coordination may or may not include substituted aromatic rings.

[0031] The repeating units of thermoplastic polyimides typically contain divalent linking groups that connect aromatic rings. These divalent linking groups are usually divalent flexible linking groups (e.g., ether groups, carbonyl groups, sulfonyl groups, isopropylidene groups, methylene groups, and perfluoroisopropylidene groups) and may have single bonds.

[0032] (1.1.1) Equation (I) The aforementioned repeating unit preferably has a repeating unit represented by the following formula (I). This allows the thermoplastic polyimide to be used as an insulated wire with excellent productivity and heat resistance.

[0033] [ka]

[0034] In formula (I), A 1 , A 2 , A 3 and A 4 Each of these independently represents a single bond, an ether group, a carbonyl group, a sulfonyl group, or an isopropylidene group. 1 , R 2 , R 3 and R 4 Each of these independently represents an alkyl group. n, m, p, and q each independently represent an integer from 0 to 4. n R 1 The number of carbon atoms in the alkyl group and m R 2 The number of carbon atoms in the alkyl group and the number of R 3 The number of carbon atoms in the alkyl group and the q R 4 The total number of carbon atoms in the alkyl group (i.e., the total number of carbon atoms in the alkyl group) is between 2 and 6. In equation (I), X represents a group represented by the following equations (X-1), (X-2), (X-3), (X-4), or (X-5).

[0035] [ka]

[0036] In equations (X-1) to (X-5), * indicates the bond position. In formula (I), Y represents a group represented by the following formulas (Y-1), (Y-2), (Y-3), (Y-4), (Y-5), (Y-6), (Y-7), or (Y-8).

[0037] [ka]

[0038] In equations (Y-1) to (Y-8), * indicates the bond position.

[0039] A "substituted phenylene group" is a phenylene group in which at least one hydrogen atom is R1 or R 2 This indicates a phenylene group that is substituted with R. An "unsubstituted phenylene group" is one in which all hydrogen atoms of the phenylene group are R. 1 or R 2 This shows an unsubstituted phenylene group.

[0040] R 1 and R 2 Examples of alkyl groups represented by include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl groups. n, m, p, and q each independently represent an integer between 1 and 4. Each of n, m, p, and q may be between 1 and 2, or 1. n R 1 The number of carbon atoms in the alkyl group and m R 2 The number of carbon atoms in the alkyl group and the number of R atoms 3 The number of carbon atoms in the alkyl group and q R 4 The total number of carbon atoms, including the alkyl group, is between 2 and 6. The total number of carbon atoms may be between 2 and 4, 4, or 2.

[0041] (1.1.1.1) Equation (I-1) It is preferable that the repeating unit of the structure represented by formula (I) includes the repeating unit of the structure represented by formula (I-1) below. This allows the thermoplastic polyimide to be used as an insulated wire with excellent productivity and heat resistance.

[0042] [ka]

[0043] The constructive repeating unit represented by equation (I) may consist of constructive repeating units represented by equation (I-1).

[0044] In formula (I-1), Y is preferably the group represented by formula (Y-1). This allows the thermoplastic polyimide to be used as an insulated wire with excellent productivity and heat resistance.

[0045] Specifically, examples of constructive repeating units represented by formula (I-1) include constructive repeating units represented by the constructive repeating unit shown in formula (I-1A) below.

[0046] [ka]

[0047] (1.1.1.2) Equation (I-2) It is preferable that the repeating unit of structure represented by formula (I) includes the repeating unit of structure represented by formula (I-2) below. This allows the thermoplastic polyimide to be used as an insulated wire with excellent productivity and heat resistance.

[0048] [ka]

[0049] The constructive repeating unit represented by equation (I) may consist of constructive repeating units represented by equation (I-2).

[0050] In formula (I-2), Y is preferably the group represented by formula (Y-1). This allows the thermoplastic polyimide to be used as an insulated wire with excellent productivity and heat resistance.

[0051] Specifically, examples of constructive repeating units represented by formula (I-2) include the constructive repeating unit represented by formula (I-2A) below.

[0052] [ka]

[0053] (1.2) Raw materials The thermoplastic polyimide resins of this disclosure can be obtained, for example, by polycondensation of a diamine (a) and an acid dianhydride (b). The reaction between the diamine (a) and the acid dianhydride (b) may be carried out in or without an organic solvent. Examples of reaction methods for the diamine (a) and the acid dianhydride (b) include a two-step synthesis method via a precursor polyamic acid and a one-step synthesis method of direct imidation. The reaction conditions may be known conditions. At least one of the diamine (a) and the acid dioxide (b) may be a biomass-derived compound.

[0054] Examples of diamine(a) include the diamine represented by formula (a-1), formula (a-2), formula (a-3), formula (a-4), formula (a-5), formula (a-6), formula (a-7), formula (a-8), formula (a-9), and formula (a-10). Diamine(a) may be used alone or in combination of two or more types.

[0055] Diamine (a) has two amino groups in its molecule, preferably has 3 to 9 para-position divalent aromatic rings in the molecular chain between the two amino groups, more preferably has 4 to 8 para-position divalent aromatic rings, and even more preferably has 5 to 7 para-position divalent aromatic rings.

[0056] The thermoplastic polyimide resin of this disclosure preferably contains structural units derived from diamine (a) and structural units derived from acid dianhydride (b). The thermoplastic polyimide resin of this disclosure preferably has 3 to 9 para-position divalent aromatic rings in the structural units derived from diamine (a), more preferably 4 to 8 para-position divalent aromatic rings, and even more preferably 5 to 7 para-position divalent aromatic rings.

[0057] [ka]

[0058] Examples of dianhydride(b) include the dianhydride represented by formula (b-1), formula (b-2), formula (b-3), formula (b-4), formula (b-5), formula (b-6), formula (b-7), and formula (b-8). Dianhydride(b) may be used individually or in combination of two or more types.

[0059] [ka]

[0060] The repeating structural unit represented by formula (I-1A) is obtained by polycondensation of the diamine represented by formula (a-1) and the acidic dianhydride represented by formula (b-1b). The repeating structural unit represented by formula (I-2A) is obtained by polycondensation of the diamine represented by formula (a-2) and the acidic dianhydride represented by formula (b-1).

[0061] (2) Insulated wires The insulated wire of this disclosure comprises a conductor and an insulating coating covering the conductor. The insulating coating includes the thermoplastic polyimide of this disclosure.

[0062] The insulated wire of this disclosure has the above configuration and therefore offers excellent productivity and heat resistance.

[0063] Figure 1 shows a cross-sectional view of an example of an insulated wire. As shown in Figure 1, the insulated wire 10 comprises a conductor 11 and an insulating coating 12. The insulating coating 12 directly covers the conductor 11.

[0064] (2.1) Conductors A conductor has the function of conducting electric current.

[0065] The shape of the conductor is not particularly limited. The cross-sectional shape of the conductor when cut by a plane perpendicular to the axial direction of the insulated wire (hereinafter also simply referred to as "cross-sectional shape") is not particularly limited and can be rectangular (e.g., square, rectangle, etc.), polygonal (except for rectangles), circular, elliptical, etc. Among these, a rectangular cross-sectional shape of the conductor is preferred. Hereinafter, a conductor having a rectangular cross-sectional shape will also be referred to as a "rectangular conductor".

[0066] From the viewpoint of suppressing the occurrence of partial discharge, the cross-sectional shape of the rectangular conductor is preferably such that chamfers (radius of curvature) are provided at all four corners of the rectangular conductor, as shown in Figure 1. The radius of curvature is not particularly limited and is appropriately selected according to the application of the insulated wire, and is preferably 0.6 mm or less, more preferably 0.2 mm to 0.4 mm.

[0067] The size of the conductor is not particularly limited. In the cross-section of a rectangular conductor when cut in a plane perpendicular to the axial direction of an insulated wire, the lengths of the long side and short side of the rectangular conductor are not particularly limited and are appropriately selected according to the application of the insulated wire, and are preferably within the following ranges. The length of the long side of the rectangular conductor is preferably 1.0 mm to 5.0 mm, more preferably 1.4 mm to 4.0 mm. The length of the short side of the rectangular conductor is preferably 0.4 mm to 3.0 mm, more preferably 0.5 mm to 2.5 mm. The ratio of the length of the long side of the rectangular conductor to the length of the short side of the rectangular conductor (length of the long side of the rectangular conductor / length of the short side of the rectangular conductor) is preferably 1 to 4. When the cross-sectional shape of the conductor is circular, the diameter of the conductor is preferably 0.3 mm to 3.0 mm, more preferably 0.4 mm to 2.7 mm.

[0068] The material of the conductor may be a metal. The metal is not particularly limited and includes, for example, copper, iron, nickel, gold, silver, platinum, cobalt, zinc, lead, tin, titanium, chromium, aluminum, magnesium, manganese, and alloys thereof (e.g., stainless steel, brass, and phosphor bronze). The copper may be low-oxygen copper or oxygen-free copper. The oxygen content of low-oxygen copper is 30 ppm or less, preferably 20 ppm or less.

[0069] (2.2) Insulating coating The insulating coating has the function of covering the conductor and providing electrical insulation to the insulated wire.

[0070] The thickness of the insulating coating is not particularly limited and may be appropriately selected depending on the application of the insulated wire, and may be 30 μm to 300 μm, 40 μm to 250 μm, or 80 μm to 150 μm.

[0071] The ratio of the variation in the thickness of the insulating coating to the average thickness of the insulating coating (hereinafter also referred to as the "thickness variation ratio") is preferably 20% or less. This ensures that the insulation properties of the insulated wire are reliably maintained even when the insulating coating is thin (for example, 100 μm). Consequently, the quality of the insulated wire is improved. The lower the film thickness variation rate, the better. Preferably, the film thickness variation rate is 7% or less, preferably 5% or less, and more preferably 3% or less. The film thickness variation rate may be 0%, or 1% or more. The method for measuring the variation in insulating film thickness involved taking a 5m length of insulated wire for evaluation and measuring the thickness of the insulating film along the long side of a cross-section perpendicular to the axial direction of the insulated wire at 100mm intervals. The unbiased standard deviation of multiple measured values ​​was defined as the "variation in insulating film thickness." Methods for adjusting the film thickness variation rate to 20% or less include, for example, adjusting the MFR of thermoplastic polyimide.

[0072] The insulating film includes the thermoplastic polyimide of the Disclosure. The insulating film may consist of the thermoplastic polyimide of the Disclosure.

[0073] The insulating film may further contain additives in addition to the thermoplastic polyimide of this disclosure.

[0074] Examples of additives include carbon fibers, glass fibers, potassium titanate fibers, aluminum borate fibers, metal fibers, ceramic fibers, boron fibers, silicon carbide fibers, asbestos fibers, rock wool fibers, and aramid fibers.

[0075] Examples of additives include fillers, lubricants, release agents, stabilizers, colorants, and nucleating agents. Examples of fillers include mica, synthetic mica, wollastonite, talc, silicone oil, fluorinated oil, glass beads, molybdenum disulfide, clay, silica, alumina, diatoms, soil, hydrated alumina, shirasu balloons, carbon nanotubes, calcium carbonate, hydrotalcite, fluorine, and graphite (e.g., artificial graphite, natural graphite (e.g., flake graphite, scaly graphite, and earthy graphite)).

[0076] Examples of additives include various liquid crystal polymers, thermoplastic resins (e.g., fluororesins, polyetherimides, polyethernitriles, polyetherketones, polyetheretherketones, polyetherketoneketones, polyetherketones, polyamideimides, polyethersulfones, polysulfones, polyarylates, and polyphenylene sulfides), and thermosetting resins (e.g., epoxy resins, polybenzimidazole resins, and polyimide resins).

[0077] The insulating coating is preferably made of one type of thermoplastic polyimide of this disclosure. If the insulating coating is not made of multiple types of thermoplastic polyimide, interfaces are likely to form between different types of resins constituting the insulating coating, which may result in insufficient heat resistance of the insulating coating. By making the insulating coating of one type of thermoplastic polyimide, no interfaces are formed between the resins constituting the insulating coating. As a result, the heat resistance of the insulating coating of the insulated wire is improved.

[0078] (2.3) Other layers Depending on the intended use of the insulated wire, other layers different from the insulating coating may be provided on the outer periphery of the insulating coating. Examples of these other layers include an electrical insulating layer and an adhesive layer.

[0079] (2.4) Application The applications of insulated wires are not particularly limited, and include windings in electrical equipment (e.g., electric motors, transformers, etc.). In particular, insulated wires are preferably used as windings in electric motors.

[0080] (3) Method of manufacturing insulated wires The method for manufacturing an insulated wire according to the present disclosure is a method for manufacturing an insulated wire according to the present disclosure. The manufacturing method includes preparing a composition containing the thermoplastic polyimide and the conductor (hereinafter also referred to as the "preparation step") and coating the conductor, which flows at a line speed of 10 m / min to 25 m / min, with a molten material of the composition (hereinafter also referred to as the "coating step"). The preparation step and the coating step are carried out in this order.

[0081] Because the method for manufacturing insulated wires according to this disclosure has the above configuration, insulated wires can be manufactured with excellent productivity.

[0082] (3.1) Preparation process In the preparation step, the composition containing the thermoplastic polyimide and the conductor are prepared.

[0083] The method for preparing the composition containing thermoplastic polyimide and the conductor may be a known method. The composition may consist solely of thermoplastic polyimide.

[0084] (3.2) Coating process In the coating process, the molten material of the composition is coated onto the conductor flowing at a line speed of 10 m / min to 25 m / min. This yields the insulated wire of the present disclosure.

[0085] For example, a known extruder and a known winding machine may be used in the coating process. The extruder extrudes the molten composition. The winding machine conveys the insulated wire at a specific line speed.

[0086] An example of an insulated wire manufacturing apparatus is shown in Figure 2. In Figure 2, "90" indicates the insulated wire manufacturing apparatus. "91" indicates the feeder. "92" indicates the preheating device. "93" indicates the extruder. "94" indicates the cooling device. "95" indicates the winding machine. "D" indicates the winding direction of the insulated conductor. "11" indicates the conductor. "10" indicates the insulated wire.

[0087] The line speed is 10 m / min to 25 m / min, may be 20 m / min to 30 m / min, or may be 10 m / min to 20 m / min, from the viewpoint of improving the productivity of insulated wires. The line speed is appropriately selected according to the MFR of the thermoplastic polyimide, etc. If the line speed is within the above range, an insulating film with a film thickness variation rate of 20% or less can be formed.

[0088] The method for coating the molten composition onto the conductor is not particularly limited and may be a known method. [Examples]

[0089] The present disclosure will be described in further detail below based on examples. However, the present disclosure is not limited to these examples.

[0090] [1] Examples of diamine synthesis The diamine was synthesized as shown below.

[0091] [1.1] Synthesis Example 1 (Diamine (a-1)) 35.5 g (0.20 mol) of 1-chloro-4-nitro-5-methylbenzene and 44.04 g (0.40 mol) of hydroquinone were dissolved in 150 g of dimethylformamide. Then, 13.8 g (0.10 mol) of potassium carbonate was added, and the reaction was carried out at 120°C. After 13 hours, it was confirmed that the starting material 1-chloro-4-nitro-5-methylbenzene had disappeared, and the mixture was cooled. 400 g of distilled water and 600 g of toluene were added to the reaction mixture, and extraction and liquid-liquid separation were performed. The resulting organic phase was concentrated, and the resulting residue was dissolved in ethanol. Then, distilled water was added, reprecipitation occurred, the mixture was filtered, and dried. This yielded 41.8 g of crystals of the nitro intermediate. The yield was 83.2%.

[0092] 20.0 g (0.080 mol) of the crystal was dissolved in 120 g of ethanol. Catalytic hydrogenation reduction was carried out in the presence of a 5% Pd / C catalyst. After the reaction was complete, the catalyst was filtered off, and distilled water was added to the resulting solution to reprecipitation. The solution was then filtered and dried. This yielded 15.0 g of amine intermediate crystals. The yield was 85.0%.

[0093] 1.8 g (0.008 mol) of the amine intermediate was reacted with 1.15 g (0.0038 mol) of 4,4-dichlorophenylsulfone in 12 mL of dry NMP (N-methyl-2-pyrrolidone) and 10 mL of dry toluene, and the mixture was placed in a two-neck flask. The two-neck flask was equipped with a magnetic stirrer, condenser, Dean-Stark trap, and nitrogen inlet tube. Next, 1.7 g (0.32 mol) of K2CO3 was added to the mixture, and the reaction mixture was heated to 140°C while continuously stirring. The water produced was removed from the reaction by azeotropic distillation. The reaction temperature was raised to 160°C and continued for 20 hours to remove residual water and toluene. The resulting reaction mixture was cooled and poured into 200 mL of water, then 20 mL of 5% NaOH was added to the mixture and it was filtered. The mixture was repeatedly washed with 5% NaOH solution and water. The resulting diamine was dried in a vacuum oven at 70°C for 24 hours. This yielded 2.02 g of diamine (a-1). The yield was 82%.

[0094] The reaction scheme for Synthesis Example 1 was as follows:

[0095] [ka]

[0096] [1.2] Synthesis Example 2 (Diamine (a-2)) 25.92 g, 0.2 mol of aniline hydrochloride and 3.06 g, 0.012 mol of 2,2-bis(4-hydroxy-3-methylphenyl)propane were placed in a flask. The mixture was then heated at 180°C for 30 minutes under a nitrogen atmosphere. The reaction mixture was poured into water, and the aqueous solution was shaken with ethyl acetate to remove phenol impurities. The aqueous solution was neutralized with aqueous NaHCO3 until the pH was 8. This precipitated the crude product. The intermediate amine was collected by filtration, dried, and recrystallized from ethyl acetate. This yielded 2.45 g of the intermediate amine. The yield was 80%.

[0097] 2.04 g (0.008 mol) of the intermediate amine was reacted with 1.15 g (0.0038 mol) of 4,4-dichlorophenylsulfone in 12 mL of dry NMP and 10 mL of dry toluene, and the mixture was placed in a two-neck flask. The two-neck flask was equipped with a magnetic stirrer, condenser, Dean-Stark trap, and nitrogen inlet tube. Next, 1.7 g (0.32 mol) of K2CO3 was added to the mixture, and the reaction mixture was heated to 140°C while continuously stirring. The water produced was removed from the reaction by azeotropic distillation. The reaction temperature was raised to 160°C and continued for 20 hours to remove residual water and toluene. The resulting reaction mixture was cooled and poured into 200 mL of water, then 20 mL of 5% NaOH was added to the mixture, and it was filtered. The mixture was repeatedly washed with 5% NaOH solution and water. The resulting diamine was dried in a vacuum oven at 70°C for 24 hours. 2.34 g of diamine (a-2) was obtained. The yield was 85%.

[0098] The reaction scheme for Synthesis Example 2 was as follows:

[0099] [ka]

[0100] [1.3] Synthesis Example 3 (Diamine(a)) 10.50 g (0.10 mol) of 2-methylaniline, 1.61 g (0.012 mol) of aluminum chloride, and 10 ml of heptane were heated to 80°C. Then, a solution of 10.72 g (0.68 mol) of 1,4-diisopropenylbenzene dissolved in 40 ml of heptane was added. The resulting clear solution was transferred to an autoclave and heated to 150°C for 1.5 hours. After cooling to 60°C, the contents of the autoclave were added to a mixture of 200 ml of heptane and 50 ml of caustic soda (30%), and the mixture was stirred gently with heating until two clear phases formed. The upper heptane phase was separated while still warm, washed with water, and left at 0°C for 1-2 days. The precipitated crystals were collected on a Buchner funnel, briefly washed with heptane, and dried at 65°C and 20 mbar. 14.45 g of almost white crystalline 4,4'-(phenylene-1,4-diisopropyl)-bis(2-methylaniline) (the diamine (ai) represented by the following formula (ai)) was obtained. The yield was 88%.

[0101] [ka]

[0102] [1.4] Synthesis Example 4 (Diamine (a-ii)) 31.5 g (0.20 mol) of p-nitrochlorobenzene and 44.04 g (0.40 mol) of hydroquinone were dissolved in 150 g of dimethylformamide. Then, 13.8 g (0.10 mol) of potassium carbonate was added, and the reaction was carried out at 120°C. After 13 hours, it was confirmed that the p-nitrochlorobenzene had disappeared, and the mixture was cooled. 300 g of distilled water and 500 g of toluene were added to the reaction mixture, and the mixture was extracted and separated. The organic phase was concentrated, and the resulting residue was dissolved in ethanol. After reprecipitation by adding distilled water, the mixture was filtered and dried. This yielded 40.2 g of brown crystals of 4-(4'-nitrophenoxy)phenol. The yield was 87.0%.

[0103] 20.0 g of the crystal was dissolved in 120 g of ethanol, and in the presence of a 5% Pd / C catalyst, Catalytic hydrogenation reduction was carried out. After the reaction was complete, the catalyst was filtered off, and distilled water was added to the resulting solution to reprecipitation. The solution was then filtered and dried. This yielded 14.8 g of 4-(4'-aminophenoxy)phenol (APP) crystals. The yield was 85.0%.

[0104] 1.64 g (0.008 mol) of APP was reacted with 1.15 g (0.0038 mol) of 4,4-dichlorophenylsulfone in 12 mL of dry NMP and 10 mL of dry toluene, and the mixture was placed in a two-neck flask. The two-neck flask was equipped with a magnetic stirrer, condenser, Dean-Stark trap, and nitrogen inlet tube. Next, 1.7 g (0.32 mol) of K2CO3 was added to the mixture, and the reaction mixture was heated to 140°C while continuously stirring. The water produced was removed from the reaction by azeotropic distillation. The reaction temperature was raised to 160°C and continued for 20 hours to remove residual water and toluene. The resulting reaction mixture was cooled and poured into 200 mL of water. Then, 20 mL of 5% NaOH was added to the mixture, and it was filtered. The mixture was repeatedly washed with 5% NaOH solution and water. The resulting diamine was dried in a vacuum oven at 70°C for 24 hours. This yielded 1.92 g of diamine (a-ii). The yield was 82.0%.

[0105] The reaction scheme for Synthesis Example 4 was as follows:

[0106] [ka]

[0107] [1.5] Synthesis Example 5 (Diamine (a-iii)) 37.9 g (0.20 mol) of 1-chloro-3-methyl-4-nitro-5-methylbenzene and 138.6 g (0.40 mol) of 1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene were dissolved in 150 g of dimethylformamide. Then, 13.8 g (0.10 mol) of potassium carbonate was added, and the reaction was carried out at 120°C. After 26 hours, it was confirmed that the starting material 1-chloro-3-methyl-4-nitro-5-methylbenzene had disappeared, and the mixture was cooled. 300 g of distilled water and 500 g of toluene were added to the reaction mixture, and extraction and liquid-liquid separation were performed. The resulting organic phase was concentrated, and the resulting residue was dissolved in ethanol. Then, distilled water was added to reprecipitation, the mixture was filtered, and dried. This yielded 52.2 g of crystals of the intermediate dinitro compound. The yield was 81.0%.

[0108] 20.0 g (0.031 mol) of the crystal was dissolved in 120 g of ethanol, and catalytic hydrogenation reduction was carried out in the presence of a 5% Pd / C catalyst. After the reaction was complete, the catalyst was filtered off, and distilled water was added to the resulting solution to reprecipitation. The solution was then filtered and dried. This yielded 14.9 g of diamine (a-iii) crystals. The yield was 82.0%.

[0109] The reaction scheme for Synthesis Example 5 was as follows:

[0110] [ka]

[0111] [2] Examples and Comparative Examples [2.1] Example 1 A container equipped with a stirrer, reflux condenser, water separator, and nitrogen inlet tube was prepared. 5.054 kg (7.8 mol) of diamine (a-1), 1.570 kg (7.25 mol) of pyromellitic dianhydride (acid dianhydride (b-1)), 0.148 kg (1.0 mol) of phthalic anhydride, and 21.53 kg of m-cresol were added to this container. The mixture was then heated to 200°C while stirring under a nitrogen atmosphere. During this time, approximately 350 ml of water was observed to distillate. The reaction was continued at 200°C for 6 hours. Afterward, the mixture was cooled to room temperature, and 10.8 kg of toluene was added. The mixture was then filtered to obtain a yellow polyimide powder. This polyimide powder was washed with toluene and dried at 180°C for 24 hours to obtain 9.59 kg (yield 98.3%) of polyimide powder (thermoplastic polyimide 1 powder). Using a Takayasu-type 25mmΦ extruder, this polyimide powder was extruded at 400°C to obtain pellets (1). Thermoplastic polyimide 1 had the constituent repeating units of formula (I-1A).

[0112] [ka]

[0113] [2.2] Example 2 A container equipped with a stirrer, reflux condenser, water separator, and nitrogen inlet tube was prepared. 5.647 kg (7.8 mol) of diamine (a-1), 1.570 kg (7.25 mol) of pyromellitic dianhydride (acid dianhydride (b-1)), 0.148 kg (1.0 mol) of phthalic anhydride, and 21.53 kg of m-cresol were added to this container. The mixture was then heated to 200°C while stirring under a nitrogen atmosphere. During this time, approximately 350 ml of water was observed to distillate. The reaction was continued at 200°C for 6 hours. Afterward, the mixture was cooled to room temperature, and 10.8 kg of toluene was added. The mixture was then filtered to obtain a yellow polyimide powder. This polyimide powder was washed with toluene and dried at 180°C for 24 hours to obtain 10.60 kg (yield 97.2%) of polyimide powder (thermoplastic polyimide 2 powder). Using a Takayasu-type 25mmΦ extruder, this polyimide powder was extruded at 400°C to obtain pellets (2). Thermoplastic polyimide 2 had the constituent repeating units of formula (I-2A).

[0114] [ka]

[0115] [2.4] Comparative Example 1 A container equipped with a stirrer, reflux condenser, water separator, and nitrogen inlet tube was prepared. 4.559 kg (7.8 mol) of diamine (Ai), 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 were added to this container. The mixture was then heated to 200°C while stirring under a nitrogen atmosphere. During this time, approximately 350 ml of water was observed to distillate. The reaction was continued at 200°C for 6 hours. Afterward, the mixture was cooled to room temperature, and 10.8 kg of toluene was added. The mixture was then filtered to obtain a yellow polyimide powder. This polyimide powder was washed with toluene and dried at 180°C for 24 hours to obtain 8.72 kg (yield 99.0%) of polyimide powder (thermoplastic polyimide 3 powder). Using a Takayasu-type 25mmΦ extruder, this polyimide powder was extruded at 400°C to obtain pellets (3). Thermoplastic polyimide 3 had the constituent repeating units of formula (Ii).

[0116] [ka]

[0117] [2.5] Comparative Example 2 A container equipped with a stirrer, reflux condenser, water separator, and nitrogen inlet tube was prepared. 4.805 kg (7.8 mol) of diamine (a-ii), 1.570 kg (7.25 mol) of pyromellitic dianhydride (acid dianhydride (b-1)), 0.148 kg (1.0 mol) of phthalic anhydride, and 21.53 kg of m-cresol were added to this container. The mixture was then heated to 200°C while stirring under a nitrogen atmosphere. During this time, approximately 350 ml of water was observed to distillate. The reaction was continued at 200°C for 6 hours. Afterward, the mixture was cooled to room temperature, and 10.8 kg of toluene was added. The mixture was then filtered to obtain a yellow polyimide powder. This polyimide powder was washed with toluene and dried at 180°C for 24 hours to obtain 9.14 kg (yield 98.5%) of polyimide powder (thermoplastic polyimide 4 powder). Using a Takayasu-type 25mmΦ extruder, this polyimide powder was extruded at 400°C to obtain pellets (4). Thermoplastic polyimide 4 had the constituent repeating units of formula (I-ii).

[0118] [ka]

[0119] [2.6] Comparative Example 3 A container equipped with a stirrer, reflux condenser, water separator, and nitrogen inlet tube was prepared. 4.559 kg (7.8 mol) of diamine (a-iii), 1.570 kg (7.25 mol) of pyromellitic dianhydride (acid dianhydride (b-1)), 0.148 kg (1.0 mol) of phthalic anhydride, and 21.53 kg of m-cresol were added to this container. The mixture was then heated to 200°C while stirring under a nitrogen atmosphere. During this time, approximately 350 ml of water was observed to distillate. The reaction was continued at 200°C for 6 hours. Afterward, the mixture was cooled to room temperature, and 10.8 kg of toluene was added. The mixture was then filtered to obtain a yellow polyimide powder. This polyimide powder was washed with toluene and dried at 180°C for 24 hours to obtain 8.72 kg (yield 99.0%) of polyimide powder (thermoplastic polyimide 5 powder). Using a Takayasu-type 25mmΦ extruder, this polyimide powder was extruded at 400°C to obtain pellets (5). Thermoplastic polyimide 5 had the constituent repeating units of formula (I-iii).

[0120] [ka]

[0121] [3]Measurement method

[0122] [3.1] Melt flow rate (MFR) A melt indexer (manufactured by Toyo Seiki Seisakusho Co., Ltd., model number: A-371401705) was used to measure the MFR. Measurement was performed in accordance with JIS K7210-1:2014, with the cylinder temperature set to 400°C and a load of 1.05 kg.

[0123] [3.2] Glass transition temperature The glass transition temperature was measured using a differential scanning calorimeter (DSC220C model, Seiko Instruments Inc.). Specifically, approximately 5 mg of the material was sealed in a measuring aluminum pan and placed in the differential scanning calorimeter. It was then heated from room temperature to 450°C at a rate of 10°C / min. To completely melt the resin, it was held at 450°C for 5 minutes, and then cooled to 30°C at a rate of 10°C / min. After being left at 30°C for 5 minutes, it was heated a second time to 450°C at a rate of 10°C / min. The displacement point corresponding to the glass transition was defined as the glass transition temperature (Tg).

[0124] [3.3] Productivity As described below, insulated wires for evaluation were fabricated using the pellets from Examples 1-2 and Comparative Examples 1-3 while varying the line speed, and productivity was evaluated. The measurement results are shown in Table 1.

[0125] [3.3.1] Insulated wire for evaluation As a conductor, a rectangular copper wire (material: copper with an oxygen content of 15 ppm) was prepared. The length of the long side of the rectangular cross-section of the rectangular copper wire was 2.99 mm. The length of the short side of the rectangular cross-section of the rectangular copper wire was 1.54 mm. The radius of curvature of the chamfers at the four corners of the rectangular cross-section of the rectangular copper wire was 6 mm.

[0126] An extruder equipped with dies (screw: 20mm diameter full flight, L / D=24, compression ratio: 3.0) was prepared. The heating temperature in the cylinder section of the extruder was controlled by dividing it into three zones, C1, C2, and C3, starting from the material input side. The heating temperatures were set to 380°C for zone C1, 410°C for zones C2 and C3, and 420°C for the head section at the rear of the extruder cylinder and the die at the front of the head section. The shape of the die holes was similar to the cross-sectional shape of the flat copper wire described above.

[0127] A conductor was passed through the die of an extruder, and an insulating film was formed on the conductor by extrusion coating while the conductor was fed out at a constant speed. Pellets (1) to (5) were fed into the extruder, and the molten pellets (1) to (5) were directly coated onto the outer circumference of the conductor, which was preheated to a temperature of 260°C, and then allowed to cool. This obtained the evaluation insulated wire of Example 1. The evaluation insulated wire comprises a conductor and an insulating film that directly covers the conductor. The insulating film is made of thermoplastic polyimide (1) to (5). The cross-sectional shape of the evaluation insulated wire was similar to the shape of the conductor. The thickness of the insulating film was 100 μm.

[0128] For the thermoplastic polyimides of Examples 1-2 and Comparative Examples 1-3, evaluation insulated wires were fabricated and the thickness of the insulating coating on the obtained evaluation insulated wires was evaluated while changing the line speed. The maximum line speed at which the variation in the thickness of the insulating coating on the evaluation insulated wires was 20 μm or less was identified. The maximum line speed is shown in Table 1. The acceptable line speed is 10 m / min or higher.

[0129] [3.3.2] Film thickness of insulating coating A 5m length of insulated wire was taken for evaluation, and the thickness of the insulating coating on the long side of the cross-section perpendicular to the axial direction of the insulated wire was measured every 100mm. The average thickness obtained by arithmetic mean of multiple measurements was defined as the "insulating coating thickness."

[0130] [3.3.3] Variation in the thickness of the insulating film A 5m length of insulated wire was taken for evaluation, and the thickness of the insulating coating on the long side of the cross-section perpendicular to the axial direction of the insulated wire was measured every 100mm. The unbiased standard deviation of multiple measurements was defined as the "variation in insulating coating thickness."

[0131] [3.4] Heat resistance Ten straight test specimens, each 400 mm long, were obtained by cutting an insulated wire for evaluation. The straight test specimens were bent 180° (U-shape) along a round bar (diameter: 8 mm) with the center of the specimen as the axis. These bent test specimens were heated for 30 minutes in a forced-circulation constant temperature bath maintained at 240°C. After being removed from the bath and allowing the specimens to return to room temperature, the presence or absence of cracks in the insulating coating was checked visually or at a magnification of 6x or less. The heat resistance of the insulated wire was evaluated according to the following evaluation criteria. An acceptable evaluation of the heat resistance of an insulated wire is "A" or "B".

[0132] [3.4.1] Evaluation Criteria A: No cracks were found in any of the test specimens. B: A crack was observed in only one test specimen. C: Cracks were observed in 2 to 4 test specimens. D: Cracks were observed in 5 to 10 test specimens.

[0133] [Table 1]

[0134] In Table 1, "PI" indicates thermoplastic polyimide. "CRU" indicates the constituent repeating unit. "Non-para-coordinate aromatic ring" refers to phenylene groups that are not linked by para coordination among the substituted or unsubstituted phenylene groups constituting the main chain.

[0135] The repeating unit configuration of Comparative Example 1 did not satisfy (a). The repeating unit configuration of Comparative Example 2 did not satisfy (b). Therefore, the heat resistance evaluation of Comparative Example 1 and Comparative Example 2 was "C" or "D". The repeating unit configuration of Comparative Example 3 did not satisfy (c). Therefore, the line speed of Comparative Example 3 was not 10 m / min or higher. From these results, it was found that thermoplastic polyimides 3 to 5 of Comparative Examples 1 to 3 are not "thermoplastic polyimides that can be used to make insulated wires with excellent productivity and heat resistance".

[0136] The repeating units of Examples 1 and 2 satisfied all of (a) to (c). Therefore, the heat resistance evaluation of Examples 1 and 2 was "A" or "B". The line speed of Examples 1 to 3 was 10 m / min or higher. From these results, it was found that thermoplastic polyimides 1 and 2 of Examples 1 to 3 are "thermoplastic polyimides that can be used to make insulated wires with excellent productivity and heat resistance". [Explanation of Symbols]

[0137] 10: Insulated wire, 11: Conductor, 12: Insulating coating

Claims

1. It has a repeating structural unit containing an imide bond, The aforementioned repeating structural unit satisfies all of the following conditions (a) to (c), and is a thermoplastic polyimide. (a) The main chain contains 5 to 10 aromatic rings. (b) Five to ten of the aforementioned aromatic rings include at least one substituted aromatic ring in which at least one hydrogen atom is substituted with an alkyl group, The total number of carbon atoms in the alkyl groups of all the substituted aromatic rings is between 2 and 6. (c) Five to ten of the aforementioned aromatic rings include at least one divalent aromatic ring, All of the aforementioned divalent aromatic rings are linked in a para coordination.

2. The thermoplastic polyimide according to claim 1, wherein the recurring unit has a recurring unit represented by the following formula (I). 【Chemistry 1】 In formula (I), A １ , A ２ , A ３ and A ４ each independently represents a single bond, an ether group, a carbonyl group, a sulfonyl group, or an isopropylidene group. R １ , R ２ , R ３ and R ４ each independently represents an alkyl group. n, m, p, and q each independently represent an integer from 0 to 4. The total number of carbon atoms of the alkyl groups of n R １ , the total number of carbon atoms of the alkyl groups of m R ２ , the total number of carbon atoms of the alkyl groups of p R ３ [[ID=NO-BREAK SPACE]] , and the total number of carbon atoms of the alkyl groups of q R ４ is from 2 to 6. In equation (I), X represents a base represented by the following equations (X-1), (X-2), (X-3), (X-4), or (X-5). 【Chemistry 2】 In equations (X-1) to (X-5), * indicates the bond position. In formula (I), Y represents a base represented by the following formulas: (Y-1), (Y-2), (Y-3), (Y-4), (Y-5), (Y-6), (Y-7), or (Y-8). 【Transformation 3】 In equations (Y-1) to (Y-8), * indicates the bonding position.

3. The thermoplastic polyimide according to claim 2, wherein the repeating unit of structure represented by formula (I) includes the repeating unit of structure represented by the following formula (I-1). 【Chemistry 4】

4. The thermoplastic polyimide according to claim 3, wherein Y is a group represented by formula (Y-1) in formula (I-1).

5. The thermoplastic polyimide according to claim 2, wherein the repeating unit of structure represented by formula (I) includes the repeating unit of structure represented by the following formula (I-2). 【Transformation 5】

6. The thermoplastic polyimide according to claim 5, wherein Y is a group represented by formula (Y-1) in formula (I-2).

7. The glass transition temperature Tg is 250°C or higher, and The thermoplastic polyimide according to claim 1, wherein the melt flow rate measured at 400°C and a load of 1.05 kg in accordance with JIS K7210-1:2014 is 10 g / 10 min or more.

8. It comprises a conductor and an insulating film covering the conductor, An insulated wire wherein the insulating coating contains the thermoplastic polyimide described in any one of claims 1 to 7.

9. The insulated wire according to claim 8, wherein the insulating coating is made of one type of thermoplastic polyimide.

10. A method for manufacturing an insulated wire as described in claim 8, The preparation of the composition containing the thermoplastic polyimide and the conductor, The molten material of the composition is applied to the conductor flowing at a line velocity of 10 m / min to 25 m / min. A method for manufacturing insulated wires, including [the specified part of the invention].

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