Thermoplastic resin composition, insulated wire, coil, and motor

Abstract

A thermoplastic resin composition comprising: a thermoplastic polyimide resin or an aromatic polyether ketone resin; and titanium-containing particles having an oil absorption of 0.0 g / 100 g to 17.0 g / 100 g.

Description

Thermoplastic resin compositions, insulated wires, coils, and motors

[0001] This disclosure relates to thermoplastic resin compositions, insulated wires, coils, and motors.

[0002] Insulated wires are used in the coils of industrial motors and home appliance motors. In recent years, insulated wires have also been used in electric motors for electric vehicles (EVs), and in this field, there is a focus on increasing the power density of drive motors from the perspective of improving power performance and fuel efficiency, such as increasing power output and miniaturization.

[0003] Insulated wires use resin materials as insulating films, which have high heat resistance, excellent moldability, mechanical properties, and chemical resistance. These are mainly materials known as super engineering plastics. Super engineering plastics are widely used as materials for various parts in industrial materials, automobiles, electrical and electronic equipment, and other industrial applications. Polyimide resin, in particular, has the best heat resistance, and Patent Document 1 discloses an insulated wire in which a thermoplastic polyimide is extruded onto the outer circumference of a conductor to form an insulating film.

[0004] Patent Document 1: International Publication No. 2014 / 084063 Patent Document 2: Japanese Unexamined Patent Publication No. 2023-165640

[0005] As described above, EV motors have a technological trend toward higher output and miniaturization from the viewpoint of improving power performance and fuel efficiency. One way to address this is to increase voltage, but when high voltage is applied to an insulated wire, partial discharge is likely to occur on the surface of the insulating film. This partial discharge causes premature erosion of the insulating film, leading to dielectric breakdown and shortening the motor's lifespan. Therefore, in order to extend the motor's lifespan, Patent Document 2 discloses a magnet wire having an enamel layer formed by coating a varnish made by suspending a thermosetting polyimide resin and curing it by heat treatment, wherein titanium-containing particles are added to the enamel layer to improve corona resistance.

[0006] However, after diligent research by the inventors of this application, it was found that when thermoplastic polyimide resin or aromatic polyetherketone resin is used as a coating material for insulated wires, the addition of titanium-containing particles can worsen the fluidity of the coating material and reduce its processing stability.

[0007] One embodiment of this disclosure aims to solve the problem of a thermoplastic resin composition that has corona resistance and improved processing stability, and an insulated wire, coil, and motor using the same.

[0008] The means for solving the above problems include the following embodiments: <1> A thermoplastic resin composition comprising a thermoplastic polyimide resin or an aromatic polyetherketone resin and titanium-containing particles having an oil absorption capacity of 0.0 g / 100 g to 17.0 g / 100 g. <2> The thermoplastic resin composition according to <1>, wherein at least a portion of the surface of the titanium-containing particles is surface-treated with at least one selected from the group consisting of hydrated alumina, silica, siloxane, and alkylsilane. <3> The thermoplastic resin composition according to <1> or <2>, wherein the titanium-containing particles are titanium oxide particles. <4> The thermoplastic resin composition according to any one of <1> to <3>, wherein the titanium-containing particles have a number-average primary particle diameter of 0.1 μm to 1.0 μm. <5> The thermoplastic resin composition according to any one of <2> to <4>, wherein the titanium-containing particles are surface-treated to a degree of 1% to 10% by mass relative to the total mass of the titanium-containing particles. <6> The thermoplastic resin composition according to any one of <1> to <5>, wherein the content of the titanium-containing particles is 5% to 15% by mass relative to the total mass of the thermoplastic resin composition. <7> The thermoplastic resin composition according to any one of <1> to <6>, wherein, in accordance with JIS K 7210-1:2014, the MFR retention rate (%) calculated by the following formula under the conditions of a cylinder temperature of 410°C, a load of 2.16 kg, and preheating times of 6 min and 30 min is 80% to 100%. MFR retention rate (%) = [MFR (g / 10 min) with 30 min preheating ÷ MFR (g / 10 min) with 6 min preheating] × 100 (%) <8> The thermoplastic resin composition according to any one of <1> to <7>, wherein the thermoplastic polyimide resin comprises the thermoplastic polyimide resin comprising a structural unit represented by the following formula (1). In equation (1) above, X is a direct bond, -SO ２ -, -CO-, -C(CH ３ ) ２ -, -C (CF ３ ) ２The group is - or -S-, where R1, R2, R3, and R4 are each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogenated alkyl group, a halogenated alkoxy group, or a halogen atom, and Y is a group selected from the group consisting of four groups represented by any of the following formulas (2-1) to (2-4). In the following formulas (2-1) to (2-4), * represents the bond position, and the hydrogen atom of the aromatic ring may be substituted. Also, the position of the bond group whose bond position has not been determined in formula (1) is either the para or meta position relative to the position to which the oxygen atom is bonded. <9> A thermoplastic resin composition according to any one of <1> to <8>, comprising the thermoplastic polyimide resin or aromatic polyetherketone resin as a main component. <10> A thermoplastic resin composition according to any one of <1> to <9> for forming an insulating film by extrusion coating. <11> An insulated wire comprising a conductor and a film covering the conductor, wherein the film comprises the thermoplastic resin composition according to any one of <1> to <10>. <12> A coil comprising the insulated wire according to <11>. <13> A motor comprising the coil according to <12>.

[0009] According to one embodiment of the present disclosure, a thermoplastic resin composition having corona resistance and improved processing stability is provided, as well as an insulated wire, coil, and motor using the same.

[0010] Figure 1 is a schematic diagram showing an example of an apparatus used in the manufacture of insulated wires according to this disclosure.

[0011] The embodiments of this disclosure are described below. The description is illustrative and does not limit the scope of this disclosure.

[0012] In this disclosure, numerical ranges indicated using "~" represent a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages within an embodiment, 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. Furthermore, in numerical ranges described within an embodiment, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the example.

[0013] In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved.

[0014] In the present disclosure, each component may comprise a plurality of corresponding substances. When referring to the amount of each component in the composition in the present disclosure, if a plurality of substances corresponding to each component exist in the composition, it means the total amount of the plurality of substances present in the composition, unless otherwise specified.

[0015] <Thermoplastic resin composition> The thermoplastic resin composition of the present disclosure comprises a thermoplastic polyimide resin or an aromatic polyether ketone resin, and titanium-containing particles having an oil absorption of 0.0 g / 100 g to 17.0 g / 100 g.

[0016] With the above configuration, the thermoplastic resin composition of the present disclosure has corona resistance and improved processing stability.

[0017] -Thermoplastic polyimide resin- Examples of the thermoplastic polyimide resin include a thermoplastic polyimide resin (a1) having a structural unit represented by the following chemical formula (1), a thermoplastic polyimide resin (a1)' having a structural unit represented by the following chemical formula (1)', a thermoplastic polyimide resin (a2) having a structural unit represented by the following chemical formula (3), a thermoplastic polyimide copolymer resin (a3) having structural units represented by the following chemical formula (4) and the following chemical formula (5), a thermoplastic polyimide resin (a4) having a structural unit represented by the following chemical formula (6), and a thermoplastic polyimide copolymer resin (a5) having a structural unit represented by the following chemical formula (6) and a structural unit represented by the following chemical formula (7).

[0018]

[0019] In the chemical formula (1), X is a direct bond, -SO ２ -, -CO-, -C(CH ３ ) ２ -, -C(CF ３ ) ２The compound is - or -S-, and R1, R2, R3, and R4 are each independently a hydrogen atom, an alkyl group, an alkoxy group, an alkyl halide, an alkoxy halide, or a halogen atom, and Y is a tetravalent aromatic group selected from any of the following linking group groups (2-1) to (2-4). Furthermore, the position of the linking group whose bond position in formula (1) has not been determined is either the para or meta position relative to the position to which the oxygen atom is bonded.

[0020]

[0021] In the aforementioned chemical formula (1), the position of the bonding group whose bond position has not been determined is preferably the meta position relative to the position to which the oxygen atom is bonded. That is, chemical formula (1) is preferably the following chemical formula (1)', and the thermoplastic polyimide preferably contains the structural unit represented by the following chemical formula (1)'.

[0022]

[0023] From the viewpoint of suppressing a decrease in dielectric breakdown voltage, Y is preferably a group represented by formula (2-1) or formula (2-3), and more preferably a group represented by formula (2-1).

[0024] The substituents that the aromatic ring in formulas (2-1) to (2-4) may have are preferably an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted halogenated alkyl group, an optionally substituted halogenated alkoxy group, or a halogen atom. If the aromatic ring in formulas (2-1) to (2-4) has multiple substituents, the substituents may be the same or different from each other.

[0025]

[0026]

[0027] However, n in chemical formula (4) and m in chemical formula (5) represent the copolymerization ratio of the polyimide copolymer, where n / m = 4 to 99 (mol% / mol%), more preferably 5 to 50, even more preferably 6 to 20, particularly preferably 7 to 15, and most preferably 9.

[0028]

[0029] Provided that p in the above formula (6) and q in the above formula (7) represent the copolymerization ratio of the thermoplastic polyimide copolymer, and p / q (mol% / mol%) is preferably 0.01 to 100, more preferably 0.1 to 50, still more preferably 0.3 to 10, particularly preferably 0.5 to 3, and most preferably 1.

[0030] Each of the above thermoplastic polyimide resins (a1) to (a5) can be produced by using, as raw materials, an aromatic diamine compound and an aromatic tetracarboxylic dianhydride that form the structural unit represented by each chemical formula, causing the reaction in the presence or absence of an organic solvent, and imidizing the obtained polyamic acid. Conditions of known polyimide production methods can be used for the production. At least one of the aromatic diamine compound and the aromatic tetracarboxylic dianhydride may be a biomass-derived compound in which at least a part of the raw material is derived from biomass. That is, the thermoplastic polyimide may be a biomass-derived thermoplastic polyimide.

[0031] To more specifically explain the thermoplastic polyimide resin (a1)' having a structural unit represented by chemical formula (1)' as an example, an aromatic diamine compound represented by the following chemical formula (8) and an aromatic tetracarboxylic dianhydride represented by the following chemical formula (9) are used as raw materials.

[0032]

[0033] In chemical formula (8), X and R1 to R4 are the same as X and R1 to R4 in chemical formula (1)'.

[0034]

[0035] In chemical formula (9), Y is the same as Y in chemical formula (1)'.

[0036] In chemical formulas (1), (1)' and (8), specific examples of R1, R2, R3, and R4 include: hydrogen atom; alkyl groups such as methyl group and ethyl group; alkoxy groups such as methoxy group and ethoxy group; halogenated alkyl groups such as fluoromethyl group and trifluoromethyl group; halogenated alkoxy groups such as fluoromethoxy group; and halogen atoms such as chlorine atom and fluorine atom, with hydrogen atom being preferable.

[0037] In chemical formulas (1), (1)' and (9), Y is a tetravalent aromatic group selected from the above linking group group (2-1) to (2-4), and is preferably a benzene ring. In this case, the aromatic tetracarboxylic dianhydride of chemical formula (9) is pyromellitic dianhydride.

[0038] The thermoplastic polyimide resin is preferably thermoplastic polyimide resin (a1), thermoplastic polyimide resin (a1)', thermoplastic polyimide resin (a2), thermoplastic polyimide copolymer resin (a3), thermoplastic polyimide resin (a4), or thermoplastic polyimide copolymer resin (a5).

[0039] The thermoplastic polyimide preferably comprises a structural unit represented by the above chemical formula (1), and more preferably consists of a structural unit represented by the above chemical formula (1). By comprising the structural unit represented by the above chemical formula (1), when the thermoplastic polyimide is used for a coating of an insulated wire, the electrical properties and heat resistance of the coating are more excellent.

[0040] The thermoplastic polyimide more preferably comprises a structural unit represented by the above chemical formula (1)', and further preferably consists of a structural unit represented by the above chemical formula (1)'. By comprising the structural unit represented by the above chemical formula (1)', when the thermoplastic polyimide is used for a coating of an insulated wire, the electrical properties and heat resistance of the coating are more excellent.

[0041] The thermoplastic polyimide is more preferably composed of the structural unit represented by the above chemical formula (3), and even more preferably composed of the structural unit represented by the above chemical formula (3). When the thermoplastic polyimide is used as a coating for insulated wires, the electrical properties and heat resistance of the coating are better when it is composed of the structural unit represented by the above chemical formula (3). When the thermoplastic polyimide is composed of the structural unit represented by the above chemical formula (3), the adhesion between the conductor and the coating made of thermoplastic polyimide resin is better.

[0042] The thermoplastic polyimide is more preferably further comprising the structural unit represented by the above chemical formula (7), and is particularly preferably comprising the structural unit represented by the above chemical formula (1)' and the structural unit represented by the above chemical formula (7). By further comprising the structural unit represented by the above chemical formula (7), the thermoplastic polyimide exhibits particularly excellent adhesion between the conductor and the coating composed of the thermoplastic polyimide resin.

[0043] In manufacturing thermoplastic polyimide resins, copolymerization can be carried out using one or more other aromatic diamine compounds or aromatic tetracarboxylic dianhydrides as raw materials, to the extent that the issues of this disclosure are not impaired.

[0044] The thermoplastic polyimide resins preferably used in this disclosure, or other polyimide resins, may be used in polymer blends as desired, provided that they do not impair the issues addressed in this disclosure.

[0045] The weight-average molecular weight (Mw) of thermoplastic polyimide is preferably 20,000 or more from the viewpoint of heat resistance. The weight-average molecular weight (Mw) of thermoplastic polyimide is preferably 35,000 or less from the viewpoint of adhesion. The weight-average molecular weight (Mw) of thermoplastic polyimide is preferably 20,000 to 40,000, more preferably 22,000 to 35,000, and even more preferably 25,000 to 30,000.

[0046] In this disclosure, the weight-average molecular weight (Mw) of a thermoplastic polyimide refers to the value measured using gel permeation chromatography (GPC), and the measurement method is the same as that described in the examples. When two or more types of thermoplastic polyimides are used in combination, the weight-average molecular weight (Mw) value of the thermoplastic polyimide shall be the value of the mixture of the two or more types of thermoplastic polyimides.

[0047] The melt flow rate (MFR) of thermoplastic polyimide resin, measured under conditions of 400°C and a 1.05 kg load in accordance with JIS K 7210-1:2014, is not particularly limited, but is preferably 2 g / 10 min to 30 g / 10 min, and more preferably 4 g / 10 min to 20 g / 10 min. When two or more types of thermoplastic polyimide are used in combination, the MFR of the thermoplastic polyimide shall be the value of the mixture of the two or more types of thermoplastic polyimide contained in the coating. The MFR of thermoplastic polyimide resin is not particularly limited, but can be measured using a melt indexer (manufactured by Toyo Seiki Seisakusho Co., Ltd., model number: A-371401705).

[0048] The logarithmic viscosity of the thermoplastic polyimide resin 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 resin is appropriate. Therefore, the film composed of the thermoplastic polyimide resin or a resin composition containing the thermoplastic polyimide resin has excellent mechanical strength, and the thermoplastic polyimide resin has excellent fluidity for manufacturing the film composed of the thermoplastic polyimide resin or a resin composition containing the thermoplastic polyimide resin by injection molding or extrusion molding. When two or more types of thermoplastic polyimide are used in combination, the logarithmic viscosity of the thermoplastic polyimide is the value of the mixture of the two or more types of thermoplastic polyimide contained in the film.

[0049] Logarithmic viscosity is measured by heating a 0.5 g / 100 ml solution of parachlorophenol / phenol (90 / 10 weight ratio) to 200°C and then cooling it to 35°C. The definition of logarithmic viscosity is described on page 58 of the 1995 first edition of the 'Polymer Handbook' published by Asakura Shoten, Japan Society for Analytical Chemistry.

[0050] The glass transition temperature Tg of the thermoplastic polyimide resin is not particularly limited, but from the viewpoint of heat resistance, it is preferably 200°C or higher, more preferably 210°C or higher, even more preferably 220°C or higher, and particularly preferably 230°C or higher. The glass transition temperature Tg of the thermoplastic polyimide resin is not particularly limited, but is preferably 300°C or lower, more preferably 290°C or lower, even more preferably 280°C or lower, and particularly preferably 260°C or lower.

[0051] The glass transition temperature Tg can be determined using a differential scanning calorimeter (DSC220C model, manufactured by Seiko Instruments Inc.). Approximately 5 mg of the material is sealed in a measuring aluminum pan, placed in the differential scanning calorimeter, heated from room temperature to 450°C at a rate of 10°C / min, held at 450°C for 5 minutes to completely melt the resin, then cooled to 30°C at a rate of 10°C / min, left at 30°C for 5 minutes, and then heated a second time to 450°C at a rate of 10°C / min. The displacement point corresponding to the glass transition is then determined as the glass transition temperature (Tg).

[0052] The melting point of the thermoplastic polyimide resin 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, and particularly preferably 380°C or higher. The melting point of the thermoplastic polyimide resin is not particularly limited, but from the viewpoint of moldability, it is preferably 420°C or lower, more preferably 410°C or lower, even more preferably 400°C or lower, and particularly preferably 390°C or lower. The method for measuring the melting point is the same as in the example.

[0053] A commercially available thermoplastic polyimide resin having the repeating structural unit of the above chemical formula (1)' is AURUM (registered trademark, manufactured by Mitsui Chemicals, Inc., glass transition temperature 250°C, melting point 388°C).

[0054] While the above-mentioned commercially available thermoplastic polyimide resin may be used, thermoplastic polyimide resin can also be synthesized by the following method. Specifically, thermoplastic polyimide resin is obtained by dehydration cocondensation of a diamine represented by formula (10) and a tetracarboxylic dianhydride represented by formula (11).

[0055]

[0056]

[0057] A known imidization reaction can be applied to the method for producing thermoplastic polyimide resin. The amount of raw material compound used is usually 0.90 to 0.99 equivalents of tetracarboxylic dianhydride per 1 equivalent of diamine. Preferably, the amount of raw material compound used is 0.93 to 0.985 equivalents, more preferably 0.95 to 0.98 equivalents. When the amount of raw material compound used is 0.90 to 0.99 equivalents, the molecular weight of the thermoplastic polyimide resin is sufficiently high, so the mechanical properties of the film composed of the thermoplastic polyimide resin or a resin composition containing the thermoplastic polyimide resin are excellent, and the fluidity of the thermoplastic polyimide resin is also excellent.

[0058] In the synthesis of thermoplastic polyimide resins, it is preferable to encapsulate the reaction ends of the molecules with phthalic anhydride or the like. By encapsulating the reaction ends, the thermal stability of the thermoplastic polyimide resin is significantly improved.

[0059] 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-imidazolidinone, 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, pyrroline, picoline, dimethyl sulfoxide, dimethyl sulfone, tetramethylurea hexamethylphosphoramide, phenol, o-cresol, m-cresol, p-cresol, p-chlorophenol, anisole, benzene, toluene, xylene, etc. Organic solvents may be used individually or in mixtures of two or more types.

[0060] The reaction temperature is usually room temperature to 250°C, preferably 140°C to 200°C. The reaction pressure is not particularly limited and can be carried out at atmospheric pressure. The reaction time varies depending on the type of solvent and the reaction temperature, but is usually 4 to 24 hours. As for the imidation method, the desired polyimide resin can be obtained by imidizing the precursor polyamic acid by heating it to 100°C to 300°C, or by chemical imidation using an imidizing agent such as acetic anhydride.

[0061] From the viewpoint of improving electrical properties and heat resistance, the thermoplastic resin composition of this disclosure preferably contains thermoplastic polyimide resin as a main component. Containing thermoplastic polyimide resin as a main component means that the thermoplastic resin composition contains 51% by mass or more of thermoplastic polyimide resin.

[0062] - Aromatic Polyetherketone Resins - Aromatic polyetherketone resins are a general term for resins in which a benzene ring is bonded with an ether group and a ketone group, and are also called polyaryletherketone resins. Examples of aromatic polyetherketone resins include polyetheretherketone (PEEK) resin, polyetherketone (PEK) resin, polyetherketoneketone (PEKK) resin, and polyetherketoneetherketoneketone (PEKEKK) resin. When using aromatic polyetherketone resins, PEEK resin is more preferable from a cost perspective.

[0063] From the viewpoint of improving electrical properties and heat resistance, the thermoplastic resin composition of this disclosure preferably contains an aromatic polyetherketone resin as a main component. Containing an aromatic polyetherketone resin as a main component means that the thermoplastic resin composition contains 51% by mass or more of aromatic polyetherketone resin.

[0064] -Titanium-containing particles- Titanium-containing particles are particles that contain at least Ti and have an oil absorption capacity of 0.0 g / 100 g to 17.0 g / 100 g. The type of titanium-containing particles is not particularly limited as long as they have an oil absorption capacity of 17.0 g / 100 g or less, but when a thermoplastic resin composition is applied as a coating for an insulated wire, titanium oxide (TiO) is preferred from the viewpoint of having excellent corona resistance. ２ It is preferable that the titanium-containing particles include titanium black, barium titanate, strontium titanate, titanium nitride, and titanium oxide (TiO2). ２ Examples of insulating materials include those listed above.

[0065] In the thermoplastic resin composition of this disclosure, the titanium-containing particles have an oil absorption amount of 0.0 g / 100 g to 17.0 g / 100 g, resulting in good dispersibility and dispersion stability in the thermoplastic resin composition. Therefore, it is presumed that the thermoplastic resin composition will have improved processing stability without a decrease in moldability (fluidity). The oil absorption amount of the titanium-containing particles can be determined in accordance with JIS K 5101-13-2. The oil absorption amount may also be measured by taking a coating from an insulated wire, heating the collected coating at 600°C in air for 5 hours, and measuring the oil absorption amount of the ash obtained by removing the resin components from the coating.

[0066] Furthermore, in the thermoplastic resin composition of this disclosure, it is preferable that at least a portion of the surface of the titanium-containing particles is surface-treated, from the viewpoint of preventing the binder from gelling by directly or indirectly (catalytically) reacting with the thermoplastic polyimide resin or aromatic polyetherketone resin. Surface treatment prevents the binder from gelling and suppresses a decrease in processing stability. In particular, it is preferable that the titanium-containing particles are surface-treated with at least one selected from the group consisting of hydrated alumina, silica, siloxane, and alkylsilane, from the viewpoint of improving the dispersion stability in the thermoplastic resin composition by imparting a surface charge, and also improving the processing stability of the thermoplastic resin composition. The amount of oil absorbed by the titanium-containing particles can be adjusted by surface treatment.

[0067] As titanium-containing particles having the above oil absorption capacity, commercially available products on the market may be used. Examples of commercially available products include JR-405 manufactured by Teika Co., Ltd., and PC-3, PFC312, and PFC317 manufactured by Ishihara Sangyo Co., Ltd.

[0068] From the viewpoint of dispersion stability in the thermoplastic resin composition, the titanium-containing particles are preferably surface-treated to a degree of 1% to 10% by mass relative to the total mass of the titanium-containing particles, and more preferably to a degree of 5% to 8% by mass. The ratio of the surface-treated layer (coverage amount) to the total mass of the titanium-containing particles can be determined by X-ray fluorescence analysis or ICP emission spectroscopy.

[0069] Furthermore, from the viewpoint of dispersibility and dispersion stability in thermoplastic resin compositions, titanium-containing particles are preferably number-average primary particle diameters of 0.1 μm to 1.0 μm. The number-average primary particle diameter is determined by selecting 200 particles arbitrarily using electron microscopy and calculating the arithmetic mean.

[0070] From the viewpoint of dispersibility and dispersion stability in the thermoplastic resin composition, the content of titanium-containing particles is preferably 5% to 15% by mass relative to the total mass of the thermoplastic resin composition.

[0071] Titanium-containing particles are titanium dioxide (TiO2). ２ If it contains ), the crystalline structure of titanium dioxide may be rutile or anatase. Amorphous titanium dioxide may be included in part, as long as the purpose of this disclosure is not impaired.

[0072] -Physical Properties- The MFR retention rate (%) of the thermoplastic resin composition of this disclosure is preferably 80% to 100%, more preferably 84% to 100%, even more preferably 88% to 100%, and particularly preferably 92% to 100% from the viewpoint of processing stability. The MFR retention rate (%) can be calculated in accordance with JIS K 7210-1:2014, under the conditions of a cylinder temperature of 410°C, a load of 2.16 kg, and preheating times of 6 min and 30 min, by the following formula: MFR retention rate (%) = [MFR with 30 min preheating (g / 10 min) ÷ MFR with 6 min preheating (g / 10 min)] × 100 (%)

[0073] The dielectric breakdown time (in minutes) of the thermoplastic resin composition of this disclosure is preferably 30 minutes or more, more preferably 60 minutes or more, and even more preferably 80 minutes or more, from the viewpoint of corona resistance. A dielectric breakdown time of 60 minutes or more results in good corona resistance. The dielectric breakdown time (in minutes) is determined by placing a 0.1 mm thick film of the thermoplastic resin composition between electrodes and measuring the time until a short circuit occurs under the following conditions: Ambient temperature: 155°C, Pulse flat voltage: 1,500 V, Pulse application time: 50%, Frequency: 20 kHz

[0074] The retention rate (%) of the thermoplastic resin composition of this disclosure is preferably 70% to 100%, more preferably 75% to 100%, and even more preferably 80% to 100%, from the viewpoint of toughness when formed into a molded article. The retention rate (%) of the tensile elongation can be calculated by performing a tensile test in accordance with ASTM D638 under conditions of a temperature of 23°C and a relative humidity of 50%, using the following formula: Retention rate (%) of tensile elongation = [Tensile elongation of the thermoplastic resin composition (%) / Tensile elongation of the thermoplastic polyimide resin or aromatic polyetherketone resin contained in the thermoplastic resin composition (%)] × 100 (%)

[0075] -Manufacturing Method- The manufacturing method for the thermoplastic resin composition of this disclosure is not particularly limited. For example, it may include the steps of adding titanium-containing particles to a thermoplastic polyimide resin or an aromatic polyetherketone resin, and melt-kneading them. In this case, the addition may be dry-blended, and the melt-kneading may be performed using an extruder.

[0076] The thermoplastic resin composition of this disclosure can be formed into any molded article, such as a film or sheet. Various methods can be applied to manufacture the molded article, including injection molding, extrusion coating, co-extrusion, T-die method, and inflation method. From the viewpoint of excellent corona resistance, the thermoplastic resin composition of this disclosure is preferably extruded onto a conductor to form a coating (insulating coating) for an insulated wire.

[0077] The insulated wires described herein will be explained below.

[0078] <Insulated Wire> The insulated wire of the present disclosure comprises a conductor and a coating that covers the conductor, wherein the coating comprises the thermoplastic resin composition of the present disclosure.

[0079] (Conductor) As the conductor, metals with excellent electrical conductivity such as copper, copper alloys, nickel-plated copper, copper-clad aluminum, and aluminum can be used. Among these, copper wire is preferred from the viewpoint of excellent electrical conductivity and cost.

[0080] The shape of the conductor is not particularly limited, but from the viewpoint of improving the space factor when applied to a motor, a rectangular cross-section is preferable. In other words, the conductor is preferably a rectangular wire.

[0081] From the viewpoint of improving adhesion with the coating, the paraffin used during manufacturing of the conductor may be degreased with alcohol. Furthermore, the surface of the conductor may be plated or otherwise treated to prevent the formation of an oxide film.

[0082] The conductor may be surface-modified to improve adhesion with the coating. Examples of surface modification treatments include mechanical treatments such as blasting, polishing, and embossing; physical treatments such as laser treatment, corona treatment, plasma treatment, and dry etching; electrochemical treatments such as plating and anodizing; and chemical treatments such as chemical etching (wet etching) and surface coating.

[0083] In blasting, particulate or finely powdered media is sprayed onto a conductor and impacted, creating irregularities on the conductor's surface. This increases the surface roughness of the conductor, making it easier for the coating to adhere due to frictional resistance (anchor effect). Therefore, the adhesion between the conductor and the coating can be improved. Furthermore, blasting can also remove oxide films formed on the conductor's surface, which further contributes to improved adhesion with the coating, making it a suitable method. Examples of media that can be used include those composed of metal particles, carbon particles, oxide particles, carbide particles, nitride particles, and the like.

[0084] Corona treatment modifies (makes hydrophilic) the conductor surface through corona discharge. Chemical interactions can improve the adhesion between the conductor and the coating.

[0085] In the plating process, the conductor is coated with a plating material. From the viewpoint of cost and productivity, wet plating is preferred. Furthermore, electrolytic plating is more preferred. Examples of plating materials include nickel plating and silver plating. The plating thickness is preferably 0.1 μm to 10 μm, and more preferably 0.5 μm to 5 μm.

[0086] In surface coating, a coating agent is applied or sprayed onto the conductor. Coating prevents surface oxidation of the conductor, and chemical interactions improve the adhesion between the coated conductor and the coating film. Silane coupling agents can be used as the coating agent.

[0087] Examples of silane coupling agents include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)- 3-aminopropylmethyldimethoxysilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, hexamethyldisilazane, 3-(2-aminoethylaminopropyl)dimethoxymethylsilane, 3-(2-aminoethylaminopropyl)trimethoxysilane, 2-(2-aminoethylthioethyl)diethoxymethylsilane, 2-(2-aminoethylthioethyl)triethoxysilane, 3-[2-(2-aminoethylaminoethylamino)propyl]trimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatetopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, imidazolylalkyl-trialkoxysilane, diphenyldimethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, trifluoropropyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyltriethoxysilane, phenyltriethoxysilane, 3-trimethoxysilylpropyl succinic anhydride, etc. can be used. Among the silane coupling agents listed above, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropyltrimethoxysilane are preferred. Commercially available silane coupling agents can be used, such as KBE-903, KBM-602, KBM-603, KBM-903, KBE-402, KBE-403, KBM-303, KBM-402, and KBM-403 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0088] (Coating) The coating covers the conductor and is molded using the thermoplastic resin composition of this disclosure. The coating may be single-layer or multi-layer. The coating may have a thickness of, for example, 0.05 mm to 0.15 mm.

[0089] The insulated wire of this disclosure is obtained by preheating a conductor, extruding the preheated conductor with a thermoplastic resin composition, and winding it onto a bobbin.

[0090] Figure 1 is a schematic diagram showing an example of an apparatus used in the manufacture of an insulated electric wire according to the present disclosure. The apparatus 100 includes a feeding unit 30 for feeding out a conductor 20, a preheating unit 40 for preheating the conductor 20 fed out from the feeding unit 30, an extrusion coating unit 50 for molding an insulated electric wire 10 by extruding a thermoplastic resin composition onto the preheated conductor 20, a cooling unit 60 for cooling the molded insulated electric wire 10, and a winding unit 70 for winding up the cooled insulated electric wire 10.

[0091] After being fed out from the dispensing section 30, the conductor 20 is preheated in the preheating section 40, enters the extrusion coating section 50, is coated with a thermoplastic resin composition, and is wound onto a bobbin in the winding section 70 while running through the cooling section 60, and recovered as an insulated wire.

[0092] Preheating is preferably performed so that the conductor reaches a temperature higher than 250°C and 400°C or lower. Preheating is preferably performed so that the conductor reaches a temperature higher than 250°C and below the melting point of the thermoplastic polyimide resin or aromatic polyetherketone resin, and more preferably so that the conductor reaches a temperature higher than 250°C and below the melting point of the thermoplastic polyimide resin or aromatic polyetherketone resin. Specifically, preheating is preferably performed so that the conductor reaches a temperature higher than 250°C and 388°C or lower, and more preferably so that the conductor reaches a temperature higher than 250°C and below 388°C. By preheating the conductor within the above temperature range, the temperature difference between the conductor and the molten thermoplastic resin composition is reduced during extrusion coating, and stress strain is relieved, thereby improving the adhesion between the conductor and the coating. Furthermore, because the temperature difference is small, the time that the molten thermoplastic resin composition remains in contact with the surface of the conductor in a molten state can be extended. As a result, the thermoplastic resin composition can be impregnated into the fine irregularities formed on the surface of the conductor, improving the adhesion between the conductor and the coating. Furthermore, by preheating the conductor to a temperature below the melting point of the thermoplastic polyimide resin or aromatic polyetherketone resin, the fluidity of the thermoplastic resin composition extruded onto the conductor during the extrusion coating process can be moderately reduced, thereby improving adhesion while also improving the uniformity of the film thickness.

[0093] The preheating method is not particularly limited and may be a contact heating method in which a heat source or flame heated to a high temperature is brought into direct contact with the conductor, or a non-contact heating method using microwaves, high frequencies, etc. When preheating using a non-contact heating method, induction heating using high frequencies is preferred from the viewpoint of preheating at a high temperature. The preheating section may be provided integrally with the dispensing section. Alternatively, the winding core (bobbin) of the dispensing section around which the conductor is wound may be heated.

[0094] When the conductor is a copper wire and it is a high-frequency induction heating device, the preheating time is preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 1 minute.

[0095] Extrusion coating can be performed in the extrusion coating section (see Figure 1). In the extrusion coating section, a thermoplastic resin composition supplied from the hopper and melted at a predetermined temperature is extruded onto a preheated conductor fed out from the preheating section. The extrusion coating may be performed so that the coating has a thickness of, for example, 0.05 mm to 0.15 mm.

[0096] The shape of the screw is not particularly limited when extruding the coating. For example, it can be appropriately selected from full-flight shape, rapid compression shape, slow compression shape, barrier-flight shape, mixing-flight shape, etc.

[0097] The effective screw length L may be, for example, 625 mm. The screw diameter D may be, for example, φ25 mm. The ratio of the effective screw length L to the screw diameter D (L / D) may be, for example, 25. The screw compression ratio (ratio of the flight groove depths of cylinder sections C-1 and C-3) may be, for example, 3.0. The screw rotation speed may be, for example, 3.0 rpm.

[0098] The heating temperature of the extruder is, for example, 390°C to 400°C in cylinder section C-1, 410°C to 420°C in cylinder section C-2, 420°C to 430°C in cylinder section C-3, 420°C to 430°C in the neck section, 420°C to 430°C in the head section, and 410°C to 420°C in the die section.

[0099] A standard crosshead die can be used for the die. The die diameter may be, for example, φ7.2 mm. The die tip may have a diameter of φ6.0 mm and a length of 9.0 mm.

[0100] The land length of the die is not particularly limited. A longer land is preferable from the viewpoint of allowing the molten thermoplastic resin composition to flow well and increasing the back pressure to improve the adhesion between the conductor and the coating.

[0101] The cylinder may have a filter, and the filter mesh is preferably less than 200 mesh from the viewpoint of reducing resin pressure. For example, 30 mesh to 100 mesh. Multiple meshes may be combined.

[0102] In this manner, the insulated wire of this disclosure can be manufactured.

[0103] <Coil> The coil of the present disclosure comprises an insulated wire of the present disclosure. The coil of the present disclosure is obtained by winding the insulated wire into a coil shape.

[0104] <Motor> The motor of the present disclosure comprises the coil of the present disclosure. The motor of the present disclosure is obtained by combining the coil of the present disclosure with a rotor and a stator. From the viewpoint of constructing the motor, the coil of the present disclosure is preferably wound around the rotor.

[0105] An embodiment of this disclosure will be described in more detail below with reference to examples. The embodiments of this disclosure are not limited to the following examples.

[0106] The various measurement and evaluation methods are described below.

[0107] • MFR retention rate (%) The MFR retention rate (%) was calculated using a melt indexer (manufactured by Toyo Seiki Seisakusho Co., Ltd., model number: A-371401705) in accordance with JIS K 7210-1:2014, under the conditions of a cylinder temperature of 410°C, a load of 2.16 kg, and preheating times of 6 min and 30 min, using the following formula: MFR retention rate (%) = [MFR (g / 10g) with 30 min preheating ÷ MFR (g / 10g) with 6 min preheating] × 100 (%)

[0108] • Dielectric breakdown time (minutes) and corona-resistant dielectric breakdown time (minutes) were measured by placing a 0.1 mm thick film of a thermoplastic resin composition between electrodes and measuring the time until a short circuit occurred under the following conditions. In Tables 2 to 5, "Good" corona resistance indicates a dielectric breakdown time of 60 minutes or more, and "Poor" corona resistance indicates a dielectric breakdown time of less than 60 minutes. • Ambient temperature: 155°C • Pulse flat voltage: 1,500 V • Pulse application time: 50% • Frequency: 20 kHz

[0109] • Tensile elongation retention rate (%) The tensile elongation retention rate (%) was calculated by performing a tensile test in accordance with ASTM D638 under conditions of 23°C and 50% relative humidity, using the following formula: Tensile elongation retention rate (%) = [Tensile elongation rate of thermoplastic resin composition (%) / Tensile elongation rate of thermoplastic polyimide resin or aromatic polyetherketone resin contained in the thermoplastic resin composition (%)] × 100 (%)

[0110] - Oil absorption (g / 100g): The oil absorption (g / 100g) of titanium-containing particles was measured according to the oil absorption measurement method specified in JIS K 5101-13-2.

[0111] -Preparation- The following materials were prepared: ・Thermoplastic polyimide resin TPI1 to TPI5 ・Titanium-containing particles Titanium-containing particles A: Manufactured by Teika Co., Ltd., titanium dioxide, JR-405 Titanium-containing particles B: Manufactured by Ishihara Sangyo Co., Ltd., titanium dioxide, PC-3 Titanium-containing particles C: Manufactured by Ishihara Sangyo Co., Ltd., titanium dioxide, PFC312 Titanium-containing particles D: Manufactured by Ishihara Sangyo Co., Ltd., titanium dioxide, PFC317 Titanium-containing particles E: Manufactured by Teika Co., Ltd., titanium dioxide, JR Titanium-containing particles F: Manufactured by Ishihara Sangyo Co., Ltd., titanium dioxide, A-100

[0112] TPI1 to TPI5 were synthesized using the following procedure.

[0113] (Synthesis Example 1) Thermoplastic polyimide resin (molecular weight) TPI1 containing the structural unit represented by formula (3) was synthesized by the following procedure. A container equipped with a stirrer, reflux condenser, water separator, and nitrogen inlet tube was prepared. 2.886 kg (7.83 mol) of 4,4'-bis(3-aminophenoxy)biphenyl, 1.605 kg (7.36 mol) of pyromellitic dianhydride, 0.141 kg (0.95 mol) of phthalic anhydride, and 13.71 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 further carried out at 200°C for 6 hours. After that, 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. After washing the polyimide powder with toluene, it was dried at 180°C for 24 hours to obtain 4.35 kg (yield 98.4%) of polyimide powder (thermoplastic polyimide). Using a 25 mmΦ extruder manufactured by Takayasu Co., Ltd., this polyimide powder was extruded at 400°C to obtain pellets. The melting point of the thermoplastic polyimide resin TPI1 was 388°C, the glass transition temperature was 245°C, and the imide group concentration was 25.5%. The melting point and glass transition temperature of the thermoplastic polyimide resin were measured using a differential scanning calorimeter (DSC) (DSC220C model, manufactured by Seiko Instruments Inc.) (the same method was used for each synthesis example below). The weight-average molecular weight Mw of the thermoplastic polyimide resin TPI1 was 32,500.

[0114] The weight-average molecular weight Mw of the thermoplastic polyimide resin TPI1 was measured using gel permeation chromatography (GPC) as follows. The weight-average molecular weight Mw of the other thermoplastic polyimide resins in this example was measured similarly. 5 mg of the sample was added to 1.5 mL of 4-chlorophenol and gently stirred at 130°C to 140°C. After the resulting solution was air-cooled to room temperature, 3.5 mL of chloroform was added. The sample solution was then filtered using a 0.2 μm filter to prepare it. The prepared sample solution was measured under the following conditions. Detector: Differential refractive index detector RI (Tosoh RI-8020) Column: TSKgel GMHXL x 2, G2500HXL x 1 (7.8 mm I.D. x 300 mm, Tosoh) Column temperature: 23°C Solvent: 4-chlorophenol / chloroform (3 / 7) (volt / volt) Flow rate: 0.8 mL / min, Sample concentration: 1 mg / ml, Injection volume: 0.3 mL Standard sample: Tosoh monodisperse polystyrene

[0115] (Synthesis Example 2) Thermoplastic polyimide resin (high molecular weight) TPI3 containing the structural unit represented by formula (3) was synthesized using the following procedure. A container equipped with a stirrer, reflux condenser, water separator, and nitrogen inlet tube was prepared. 2.886 kg (7.83 mol) of 4,4'-bis(3-aminophenoxy)biphenyl, 1.627 kg (7.46 mol) of pyromellitic dianhydride, 0.112 kg (0.75 mol) of phthalic anhydride, and 13.71 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 further carried out at 200°C for 6 hours. After that, 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. After washing the polyimide powder with toluene, it was dried at 180°C for 24 hours to obtain 4.34 kg (yield 98.6%) of polyimide powder (thermoplastic polyimide powder). Using a 25 mmΦ extruder manufactured by Takayasu Co., Ltd., this polyimide powder was extruded at 400°C to obtain pellets. The melting point of the thermoplastic polyimide resin TPI3 was 389°C, the glass transition temperature was 248°C, and the imide group concentration was 25.5%. The weight-average molecular weight Mw of the thermoplastic polyimide resin TPI3 was 36,900. Mw was measured by the method described above.

[0116] (Synthesis Example 3) Thermoplastic polyimide resin (low molecular weight) TPI2 containing the structural unit represented by formula (3) was synthesized by the following procedure. A container equipped with a stirrer, reflux condenser, water separator, and nitrogen inlet tube was prepared. 2.880 kg (7.82 mol) of 4,4'-bis(3-aminophenoxy)biphenyl, 1.580 kg (7.24 mol) of pyromellitic dianhydride, 0.170 kg (1.147 mol) of phthalic anhydride, and 13.71 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 further carried out at 200°C for 6 hours. After that, 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. After washing the polyimide powder with toluene, it was dried at 180°C for 24 hours to obtain 4.35 kg (yield 98.2%) of polyimide powder (thermoplastic polyimide powder). Using a 25 mmΦ extruder manufactured by Takayasu Co., Ltd., this polyimide powder was extruded at 400°C to obtain pellets. The melting point of the thermoplastic polyimide resin TPI2 was 386°C, the glass transition temperature was 240°C, and the imide group concentration was 25.5%. The weight-average molecular weight Mw of the thermoplastic polyimide resin TPI2 was 28,200. Mw was measured by the method described above.

[0117] (Synthesis Example 4) A thermoplastic polyimide resin TPI4 containing structural units represented by formula (4) and structural units represented by formula (5) was synthesized using the following procedure. 1.760 kg (4.77 mol) of 4,4'-bis(3-aminophenoxy)biphenyl, 0.106 kg (0.53 mol) of 4,4'-diaminodiphenyl ether, 1.097 kg (5.03 mol) of pyromellitic dianhydride, 0.082 kg (0.55 mol) of phthalic anhydride, and 11.45 kg of cresolic acid were added to a container equipped with a stirrer, reflux condenser, water separator, and nitrogen inlet tube. The mixture was then heated to 145°C while stirring under a nitrogen atmosphere. During this time, approximately 190 ml of water was observed to distillate. The reaction was further carried out at 145°C for 4 hours. After that, the mixture was cooled to room temperature and 5.74 kg of methyl ethyl ketone was added. The mixture was then filtered to obtain a yellow polyimide powder. The polyimide powder was washed with methyl ethyl ketone and then dried at 180°C for 24 hours to obtain 2.82 kg (yield 97%) of polyimide powder (thermoplastic polyimide). Using a 25 mmΦ extruder manufactured by Takayasu Co., Ltd., the polyimide powder was extruded at 400°C to obtain pellets. The melting point of the thermoplastic polyimide resin TPI4 could not be determined, the glass transition temperature was 253°C, and the imide group concentration was 23.9%. In TPI4, the ratio of structural units represented by formula (4) to structural units represented by formula (5) was 9:1.

[0118] (Synthesis Example 5) Thermoplastic polyimide resin TPI5 containing structural units represented by formula (6) and structural units represented by formula (7) was synthesized according to the following procedure. A container equipped with a stirrer, reflux condenser, water separator and nitrogen inlet tube was prepared. 1.916 kg (5.20 mol) of 4,4'-bis(3-aminophenoxy)biphenyl, 0.538 kg (2.47 mol) of pyromellitic dianhydride, 0.726 kg (2.47 mol) of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 0.079 kg (0.54 mol) of phthalic anhydride, and 11.30 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 190 ml of water was observed to have distilled off. The reaction was then carried out at 200°C for 6 hours. After that, the mixture was cooled to room temperature and 5.68 kg of methanol was added. Subsequently, the mixture was filtered to obtain a yellow polyimide powder. This polyimide powder was washed with methanol and then dried at 180°C for 24 hours to obtain 2.87 kg (yield 98.5%) of polyimide powder (thermoplastic polyimide powder). Using a 25 mmΦ extruder manufactured by Takayasu Co., Ltd., this polyimide powder was extruded at 400°C to obtain pellets. The melting point of the thermoplastic polyimide resin TPI5 could not be determined, the glass transition temperature was 235°C, and the imide group concentration was 23.9%. In TPI5, the ratio of structural units represented by formula (6) to structural units represented by formula (7) was 1:1.

[0119] Table 1 shows the physical properties of the titanium-containing particles used.

[0120] <Example 1> 95 parts by mass of TPI1 pellets produced in Synthesis Example 1 and 5 parts by mass of titanium-containing particles A were dry-blended using a mixer. Then, pellets were obtained by extruding and granulating the mixture using a twin-screw extruder at 400°C to 420°C. Next, the processing stability of the thermoplastic resin composition of the obtained pellets was evaluated by the MFR retention rate (%) using the MFR measurement described above. The results are shown in Table 2. Next, the obtained pellets were pressed using a press molding machine (Shinto Metal Industry Co., Ltd., YS-10H type, mold temperature 400°C, pressure 5 MPa, preheating time 5 minutes, pressing time 1 minute) to produce a film with a thickness of 0.1 mm, and the dielectric breakdown time (seconds) was measured to evaluate the corona resistance. The results are shown in Table 2. The obtained pellets were fed into an injection molding machine (Sumitomo Heavy Industries, Ltd., SE100EV, cylinder temperature 400°C to 420°C, mold temperature 180°C) to produce tensile test specimens, and tensile tests were also performed. The results are shown in Table 2.

[0121] <Examples 2-15 and Comparative Examples 1-5> Examples 2-15 and Comparative Examples 1-5 were prepared in the same manner as in Example 1, except that the thermoplastic polyimide resin and titanium-containing particles were blended in the amounts shown in Tables 2-4, respectively. Various molding and evaluation processes were then carried out. The results are shown in Tables 2-4.

[0122]

[0123]

[0124]

[0125]

[0126] As shown in Tables 2 to 5, the films using the thermoplastic resin compositions of Examples 1 to 15 (containing titanium-containing particles with oil absorption rates of 0.0 g / 100 g to 17.0 g / 100 g) exhibited better corona resistance compared to the films using only thermoplastic polyimide resin as raw material in Reference Examples 1 to 5. Furthermore, the thermoplastic resin compositions of Examples 1 to 15 all showed good MFR retention rates (%) of 90% or higher, indicating a significant improvement in processing stability compared to the films using the thermoplastic resin compositions of Comparative Examples 1 to 5. Processing stability was also improved compared to the films using only thermoplastic polyimide resin as raw material in Reference Examples 1 to 5. The thermoplastic resin compositions of this disclosure can be suitably used as insulating coatings for insulated electric wires.

[0127] The disclosure of Japanese Patent Application No. 2025-057230, filed on 28 March 2025, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

[0128] 100 Insulated wire manufacturing apparatus 10 Insulated wire 20 Conductor 30 Feeding section 40 Preheating section 50 Extrusion coating section 51 Hopper 52 Cylinder 53 Die (crosshead die) 60 Cooling section 70 Winding section

Claims

1. A thermoplastic resin composition comprising a thermoplastic polyimide resin or an aromatic polyetherketone resin, and titanium-containing particles having an oil absorption capacity of 0.0 g / 100 g to 17.0 g / 100 g.

2. The thermoplastic resin composition according to claim 1, wherein at least a portion of the surface of the titanium-containing particles is surface-treated with at least one selected from the group consisting of hydrated alumina, silica, siloxane, and alkylsilane.

3. The thermoplastic resin composition according to claim 1, wherein the titanium-containing particles are titanium oxide particles.

4. The thermoplastic resin composition according to claim 1, wherein the titanium-containing particles have a number-average primary particle diameter of 0.1 μm to 1.0 μm.

5. The thermoplastic resin composition according to claim 2, wherein the titanium-containing particles are surface-treated in an amount ranging from 1% by mass to 10% by mass relative to the total mass of the titanium-containing particles.

6. The thermoplastic resin composition according to claim 1, wherein the content of the titanium-containing particles is 5% by mass to 15% by mass with respect to the total mass of the thermoplastic resin composition.

7. The thermoplastic resin composition according to claim 1, wherein, in accordance with JIS K 7210-1:2014, the MFR retention rate (%) calculated by the following formula under the conditions of a cylinder temperature of 410°C, a load of 2.16 kg, and preheating times of 6 min and 30 min, is 80% to 100%. MFR retention rate (%) = [MFR (g / 10 min) with 30 min preheating ÷ MFR (g / 10 min) with 6 min preheating] × 100 (%) 8. The thermoplastic resin composition according to claim 1, comprising the thermoplastic polyimide resin, wherein the thermoplastic polyimide resin comprises a structural unit represented by the following formula (1). In equation (1) above, X is a direct bond, -SO ２ -, -CO-, -C(CH ３ ) ２ -, -C (CF ３ ) ２ The group is - or -S-, where R1, R2, R3, and R4 are each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogenated alkyl group, a halogenated alkoxy group, or a halogen atom, and Y is a group selected from the group consisting of four groups represented by any of the following formulas (2-1) to (2-4). In the following formulas (2-1) to (2-4), * represents the bond position, and the hydrogen atom of the aromatic ring may be substituted. Also, the position of the bond group whose bond position has not been determined in formula (1) is either the para or meta position relative to the position to which the oxygen atom is bonded.

9. The thermoplastic resin composition according to claim 1, comprising the thermoplastic polyimide resin or aromatic polyetherketone resin as a main component.

10. The thermoplastic resin composition according to claim 1, for use in forming an insulating film by extrusion coating.

11. An insulated wire comprising a conductor and a coating covering the conductor, wherein the coating contains the thermoplastic resin composition described in any one of claims 1 to 10.

12. A coil comprising an insulated wire as described in claim 11.

13. A motor comprising the coil described in claim 12.

Images