JP5407059B2 - Insulated wire - Google Patents

Description

  The present invention relates to an insulated wire formed by applying and baking an insulating coating on a conductor, and more particularly to an insulated wire that can be suitably used for a coil of an electric device such as a rotating electrical machine.

  In general, insulated wires (enamel-covered insulated wires) used in coils of electrical equipment such as rotating electrical machines and transformers are molded into a cross-sectional shape (for example, round or flat) that matches the coil application and shape. A single layer or a plurality of layers of insulating coatings are formed on the outer layer of the formed conductor. In particular, a rotating electrical machine for automobiles has recently been required to be highly efficient and small, and an insulated wire that can be wound around a stator core at a high density to form a coil is required.

  As such an insulated wire, for example, in Patent Document 1, a resin composition such as a polyamideimide having an adhesion strength with a conductor of 30 g / mm or more and a glass transition temperature (Tg) of 250 ° C. or more on a conductor. An insulating layer is formed, and a mixture of a resin composition such as polyamideimide having a Tg of 250 ° C. or higher and a resin composition such as polyetherimide or polyethersulfone having a Tg of 140 ° C. or higher is formed on the insulating film. An insulated wire having an insulating layer with an elongation at break of 40% or more is disclosed. The insulated wire described in Patent Document 2 is excellent in the flexibility of the insulating film, has excellent workability that does not cause cracking in the insulating film even when severe winding or rolling is performed, and is equivalent to polyamideimide It is said to have heat resistance.

  In addition, when forming the coil by connecting the ends of relatively short insulated wires by welding or the like, an insulated wire that does not cause a problem even if it is welded is required.

  As such an insulated wire, for example, in Patent Document 2, (1) a first insulating layer substantially made of polyamideimide and / or polyimide is formed on a conductor, and (2) glass is formed on (2) polyamideimide A. A thermoplastic resin B (polyetherimide, polyethersulfone, etc.) having a transition temperature of 140 ° C. or higher is blended at a ratio of A / B = 70/30 to 30/70 in terms of weight ratio A / B. 2 insulating layers are coated and laminated, and the ratio of the thickness T1 of the first insulating layer to the thickness T2 of the second insulating layer is within the range of T1 / T2 = 5/95 to 40/60 and remains An insulated wire having a solvent amount of 0.05% by weight or less of the total amount of the insulating film is disclosed. The insulated wire described in Patent Document 2 has excellent work resistance that does not cause damage to the coating even when severe rolling and winding processes are performed, and high heat resistance equivalent to that of polyamideimide. In the process of joining the ends of the insulated wires, it is said that the insulating coating in the vicinity of the joining portion has excellent joining properties such that the insulating coating does not foam due to the heat of joining, or the discoloration length does not increase.

JP 2000-235818 A JP 2001-155551 A

  In recent years, inverter control in rotating electrical machines has been rapidly spreading due to demands for downsizing, high performance, energy saving, and the like for electrical equipment. In order to satisfy this requirement, higher voltage and higher current (higher power) are being developed in inverter control. In that case, there is a concern that a high inverter surge voltage generated by the inverter control may adversely affect the coil insulation system in the rotating electrical machine. In order to prevent deterioration of the insulating film due to the inverter surge voltage, it is necessary to suppress the occurrence of partial discharge in the insulating film, that is, to increase the partial discharge start voltage in the insulating film.

  On the other hand, with the further increase in efficiency of electrical equipment, further improvement in the space factor of insulated wires is required, and partial discharge starts without increasing the thickness of the insulation coating (at a maximum thickness of 45 μm). There is a demand for further improvement in voltage (for example, partial discharge start voltage of 1000 Vp or more). The conventional insulated wires as described in Patent Documents 1 and 2 are considered to have resistance (mechanical characteristics) to the wire processing and rolling, but the conventional insulation wires maintain the thickness of the insulation coating. It is not sufficient to obtain a partial discharge starting voltage even higher than that.

  Accordingly, an object of the present invention is to solve the above-mentioned problems and provide an insulated wire having a high partial discharge starting voltage with a thickness equivalent to that of a conventional insulation coating.

［化学式１において、Ｒは３つ以上の芳香環を有する２価の芳香族基を有する芳香族ジアミン類であり、ｎは繰り返し数であって、正の整数である。］ In order to achieve the above object, the present invention provides an insulated wire in which an insulating coating made of a polymer alloy containing an amorphous thermoplastic resin (A) and an amorphous thermosetting resin (B) is formed. The amorphous thermosetting resin (B) is composed of a polyamide-imide resin having a repeating unit represented by the following chemical formula 1, the insulating coating has a sea-island structure, and the amorphous thermosetting resin Another object of the present invention is to provide an insulated wire in which the functional resin (B) forms a sea component of the sea-island structure and the amorphous thermoplastic resin (A) forms an island component of the sea-island structure.

[In Chemical Formula 1, R is an aromatic diamine having a divalent aromatic group having three or more aromatic rings, and n is a repeating number, which is a positive integer. ]

Moreover, in order to achieve the said objective, this invention can add the following improvements and changes in the insulated wire which concerns on said invention.
(1) The polyamide-imide resin having a repeating unit represented by the above chemical formula 1 comprises an azeotropic solvent comprising a diamine component and an acid component each consisting of an aromatic diamine having a divalent aromatic group having three or more aromatic rings. It comprises a polyamide-imide resin obtained by reacting an imide group-containing dicarboxylic acid synthesized by the reaction with a diisocyanate component comprising an aromatic diisocyanate.
(2) In the polymer alloy, 10 to 150 parts by weight of the amorphous thermoplastic resin (A) is blended with 100 parts by weight of the polyamideimide resin having the repeating unit represented by the chemical formula 1.
(3) The island component has an average diameter of less than 1 μm.
(4) The amorphous thermoplastic resin (A) is made of a polyetherimide resin.
(5) The insulating coating has a thickness of 1 μm or more and 45 μm or less.

  According to the present invention, it is possible to provide an insulated wire having a high partial discharge starting voltage with a thickness equivalent to that of a conventional insulating coating.

  In order to achieve the above object, the present inventors have intensively studied the microstructure of the insulating film (particularly, the microphase separation structure), and as a result, when the microstructure of the insulating film has a specific sea-island structure, good characteristics are obtained. The present invention has been completed based on the finding that it can be obtained. Embodiments according to the present invention will be described below. It should be noted that the present invention is not limited to the embodiments taken up here, and combinations and improvements can be appropriately made without departing from the scope of the invention.

  In the insulated wire according to the present invention, the polymer alloy microstructure (microphase separation structure) constituting the insulating coating is preferably a sea-island structure. The sea-island structure is preferably configured such that the island component (dispersed phase component) is an amorphous thermoplastic resin (A) and the sea component (continuous phase component) is an amorphous thermosetting resin (B). . In the case of the reverse configuration (when the sea component is an amorphous thermoplastic resin (A) and the island component is an amorphous thermosetting resin (B)), the insulating coating as a whole has a thermoplastic behavior (glass This is not preferable because the transition temperature Tg is low and the heat resistance is poor. Further, when the microphase separation structure of the polymer alloy forms a co-continuous structure (for example, a lamellar structure or a gyroid structure), it is not preferable because the insulating coating exhibits a thermoplastic behavior as a whole.

［化学式２において、Ｒは３つ以上の芳香環を有する２価の芳香族基を有する芳香族ジアミン類であり、ｎは繰り返し数であって、正の整数である。］
非晶質の熱硬化性樹脂（Ｂ）として上記化学式２で示される繰り返し単位を有するポリアミドイミド樹脂を適用するとともに、この上記化学式２で示される繰り返し単位を有するポリアミドイミド樹脂が海島構造の海成分で非晶質の熱可塑性樹脂（Ａ）が島成分であることにより、絶縁被膜が低い比誘電率（例えば、３．０未満の比誘電率）を有することになるため、導体の周囲に形成された絶縁被膜の厚さ（膜厚）が４５μｍ以下である場合においても、部分放電開始電圧の高い（例えば、１０００Ｖｐ以上の部分放電開始電圧を有する）絶縁電線を提供することができる。 The amorphous thermosetting resin (B) in the present invention is preferably composed of a polyamideimide resin having a repeating unit represented by the following chemical formula 2.

[In Chemical Formula 2, R is an aromatic diamine having a divalent aromatic group having three or more aromatic rings, and n is a repeating number, which is a positive integer. ]
As the amorphous thermosetting resin (B), a polyamideimide resin having a repeating unit represented by the above chemical formula 2 is applied. Since the amorphous thermoplastic resin (A) is an island component, the insulating film has a low relative dielectric constant (for example, a relative dielectric constant of less than 3.0), so it is formed around the conductor. Even in the case where the thickness (film thickness) of the insulating coating is 45 μm or less, an insulated wire having a high partial discharge start voltage (for example, having a partial discharge start voltage of 1000 Vp or more) can be provided.

  Further, as a polyamide-imide resin having a repeating unit represented by the chemical formula 2, a diamine component composed of an aromatic diamine having a divalent aromatic group having three or more aromatic rings and an acid component are mixed with an azeotropic solvent. It is preferable to use a polyamide-imide resin obtained by reacting a synthetically reacted imide group-containing dicarboxylic acid with a diisocyanate component composed of an aromatic diisocyanate. By using such a polyamide-imide resin, the molecular weight of the polyamide-imide resin can be increased without reducing the heat resistance of the polyamide-imide resin, so both the maintenance of heat resistance and the reduction of the dielectric constant are effective. Can be realized.

  As the diamine component, aromatic diamines having a divalent aromatic group having three or more aromatic rings are preferable. For example, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [ 4- (4-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] ether, 9,9-bis (4-aminophenyl) fluorene, 4,4′-bis (4-aminophenoxy) ) Biphenyl, 1,4-bis (4-aminophenoxy) benzene, or isomers thereof. These can be selected from at least one.

  A part of the diamine components listed above can be used in place of the diisocyanate component by using phosgene or the like. When using a diamine component in which such a portion is replaced with a diisocyanate component, the diamine component is mixed with a diisocyanate component used in a reaction with an imide group-containing dicarboxylic acid, and synthesized to obtain a polyamideimide resin. It is also possible.

  As the diisocyanate component, aromatic diisocyanates are preferable. For example, 4,4′-diphenylmethane diisocyanate (MDI), 2,2-bis [4- (4-isocyanatophenoxy) phenyl] propane (BIPP), tolylene diisocyanate ( TDI), naphthalene diisocyanate, xylylene diisocyanate, biphenyl diisocyanate, diphenyl sulfone diisocyanate, diphenyl ether diisocyanate and the like aromatic diisocyanates, isomers and multimers. These can be selected from at least one. If necessary, use together with aliphatic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and xylylene diisocyanate, or alicyclic diisocyanates and isomers obtained by hydrogenating the aromatic diisocyanates exemplified above. You may do it. The blending ratio of the diisocyanate component is not particularly limited, but it is preferable to set the blending ratio so that the imide group-containing dicarboxylic acid obtained by the first-stage synthesis is equal to the diisocyanate component.

  As the acid component, for example, aromatic tricarboxylic acid anhydrides such as trimet acid anhydride and benzophenone tricarboxylic acid anhydride can be used, and trimet acid anhydride is preferable.

  In the synthesis of the polyamideimide resin, a reaction catalyst such as amines, imidazoles and imidazolines may be used as long as the stability of the polyamideimide resin is not impaired. Moreover, you may use sealing agents, such as alcohol, for the purpose of stopping the synthesis reaction of a polyamideimide resin.

  Moreover, as an azeotropic solvent used when making a diamine component and an acid component react, aromatic hydrocarbons, such as toluene, benzene, xylene, ethylbenzene, can be illustrated, for example, and xylene is especially suitable. Moreover, the reaction temperature in reaction of a diamine component and an acid component is 160 to 200 degreeC, Preferably it is 170 to 190 degreeC. In addition, the reaction temperature in reaction of imide group containing dicarboxylic acid and a diisocyanate component is 110 to 130 degreeC.

  In the present invention, the amorphous thermoplastic resin (A) that is an island component of the sea-island structure preferably has an average diameter of less than 1 μm. When the average diameter of the island component is less than 1 μm, the mechanical properties and heat resistance of the insulating coating are greatly improved, and the appearance after the insulating coating is formed is improved. On the other hand, when the average diameter of the island component is 1 μm or more, a phenomenon such as deterioration of mechanical properties due to generation of microcracks or surfaceization of thermoplastic behavior due to large island component occurs, and the appearance is deteriorated after the insulating coating is formed. It is not preferable because there are cases.

  In the polymer alloy in the present invention, the amorphous thermoplastic resin (A) is contained in 100 parts by weight of the amorphous thermosetting resin (B) made of the polyamideimide resin having the repeating unit represented by the chemical formula 2. It is preferably blended in an amount of 10 to 150 parts by weight. If the amount of the amorphous thermoplastic resin (A) is too small, it is difficult to obtain an insulated wire having a high partial discharge starting voltage. In particular, the blending amount of the amorphous thermoplastic resin (A) is more preferably 30 parts by weight or more and 130 parts by weight or less with respect to 100 parts by weight of the amorphous thermosetting resin (B). The compounding amount of the crystalline thermoplastic resin (A) is more preferably 50 parts by weight or more and 120 parts by weight or less. When the blending amount of the amorphous thermoplastic resin (A) is 50 parts by weight or more and 120 parts by weight or less, the balance between the dielectric constant and the heat resistance of the insulating coating becomes the best.

  On the other hand, in the case of a polymer alloy in which the amorphous thermoplastic resin (A) is blended in an amount of about 151 to 300 parts by weight with respect to 100 parts by weight of the amorphous thermosetting resin (B), thermosetting Since the thermoplastic resin (B) and the thermoplastic resin (A) form a co-continuous phase separation structure, it exhibits thermoplastic behavior as a whole (for example, the glass transition temperature Tg is low and the heat resistance is poor). become. Further, in the case of a polymer alloy in which the amorphous thermoplastic resin (A) is blended at 300 parts by weight or more with respect to 100 parts by weight of the amorphous thermosetting resin (B), the thermosetting resin (B ) Becomes an island component, and a sea-island structure in which the thermoplastic resin (A) becomes a sea component is formed. This case is also not preferable because it exhibits a thermoplastic behavior as a whole.

  The production method of the polymer alloy is not particularly limited as long as an insulating coating satisfying the requirements defined in the present invention is obtained, and a normal method can be used. For example, a method of mixing separate solutions in which each resin is dissolved in a solvent, a method in which each resin is simultaneously dissolved in the same solvent, or a method in which one resin is dissolved in a solvent and then the other resin is added. And a method in which one resin is dissolved in a solvent and then the other resin is synthesized and mixed in the solution. In the present invention, in order to facilitate the formation of a sea-island structure in the insulating coating, the amorphous thermosetting resin (B) and the amorphous are improved in order to improve the compatibility between the resin and the solvent in the polymer alloy production stage. It is particularly preferable to use a thermoplastic resin (A) and a polar solvent as the solvent.

  The insulated wire manufacturing method is not particularly limited as long as an insulated wire satisfying the requirements defined in the present invention is obtained, and a normal method for manufacturing enameled wire can be used. For example, the polymer alloy solution (insulating coating material) manufactured as described above can be applied to a conductor and baked to form an insulating film. The insulated wire according to the present invention may be further provided with a self-lubricating film on the outermost layer of the insulating film as necessary, or a film for improving adhesion between the conductor and the insulating film. May be further provided. The self-lubricating film and the adhesion improving film can be formed by selecting one or more kinds of resins such as polyimide, polyamideimide, polyesterimide, and H-type polyester as the base resin.

  The molecular weight of the amorphous thermosetting resin that is the sea component of the polymer alloy is preferably 10,000 to 200,000, and more preferably 15,000 to 100,000. If the molecular weight of the thermosetting resin is less than 10,000, there are problems that the mechanical strength of the insulating coating is lowered and the dielectric constant is increased because the resin has many molecular ends. On the other hand, if the molecular weight of the thermosetting resin is larger than 200,000, problems such as a decrease in solubility in a solvent, a decrease in compatibility with a thermoplastic resin, and difficulty in becoming a sea part of a sea-island structure are caused.

  The amorphous thermoplastic resin (A) which is an island component of the polymer alloy is preferably a thermoplastic resin having a low dielectric constant, and specifically, a thermoplastic resin having a dielectric constant of less than 3.3 is preferable. When a thermoplastic resin having a dielectric constant of 3.3 or more is used as an island component, it is difficult to reduce the dielectric constant of the entire insulating coating. The molecular weight of the amorphous thermoplastic resin is preferably 15,000 to 200,000, and more preferably 20,000 to 100,000. If the molecular weight of the thermoplastic resin is less than 15,000, the mechanical strength of the coating is lowered and the island part of the sea-island structure is hardly formed. On the other hand, when the molecular weight of the thermoplastic resin is larger than 200,000, the solubility in a solvent and the compatibility with a thermosetting resin are reduced.

  As the amorphous thermoplastic resin (A) in the present invention, a polyetherimide resin is preferably used from the viewpoints of solubility in a solvent, heat resistance, and dielectric constant. The polyetherimide resin used is not particularly limited as long as it is a polyether having two or more imide groups. There is no special restriction | limiting in the manufacturing method of polyetherimide resin, A known method can be utilized. As a specific example, a polyetherimide resin obtained by condensation of 4.4 '[isopropylidenebis (P-phenyleneoxy)] diphthalic acid dihydrate and metaphenylenediamine can be preferably used. As the amorphous thermoplastic resin (A) in the present invention, for example, a commercially available polyetherimide resin (for example, Ultem (registered trademark) manufactured by SABIC Innovative Plastics) can be used. Further, the polyetherimide resin may be a single composition or a composition in which two or more kinds are mixed.

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, this invention is not limited to these.

[Synthesis Method of Polyamideimide Resin a According to the Present Invention]
In a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet pipe, and a thermometer, 451.1 g of 2,2-bis [4- (4-aminophenoxy) phenyl] propane as a diamine component and trimethyl as an acid component are added. After blending 453.9 g of merit acid anhydride, 2542.1 g of N-methyl-2-pyrrolidone as a solvent and 254.2 g of xylene as an azeotropic solvent were added, stirring rotation speed 180 rpm, nitrogen flow rate 1 L / min The reaction was carried out at a system temperature of 180 ° C. for 4 hours (the first-stage synthesis reaction step). In addition, water and xylene generated during the dehydration ring-closing reaction in this step once accumulated in a receiver and appropriately distilled out of the system.
After the imide group-containing dicarboxylic acid obtained in the first-stage synthesis reaction step is cooled to 90 ° C., this imide group-containing dicarboxylic acid is mixed with 319.7 g of 4,4′-diphenylmethane diisocyanate, which is a diisocyanate component. The reaction was carried out for 1 hour at a stirring speed of 150 rpm, a nitrogen flow rate of 0.1 L / min, and a system temperature of 120 ° C. Thereafter, 89.3 g of benzyl alcohol as a sealant and 635.4 g of N, N-dimethylformamide were added to stop the reaction (the second-stage synthesis reaction step). By such a synthesis reaction, a polyamideimide resin a (amorphous thermosetting resin (B)) having a viscosity of 2000 mPa · s measured with an E-type viscometer was obtained.

Example 1
Polyamideimide resin a obtained by the above synthesis and 25% by mass polyetherimide solution in which polyetherimide (SABIC Innovative Plastics, Ultem 1040A) is dissolved in N-methyl-2-pyrrolidone are used as the respective resins. The mass ratio was 100/100, and the mixture was stirred and stirred in the flask. Next, add N-methyl-2-pyrrolidone to this mixed solution, and further dilute until the mass concentration of non-volatiles is almost constant (27 ± 2%) until it becomes a uniform brown transparent solution to produce an insulation coating. did. The viscosity of the insulating coating was 860 mPa · s. After that, the insulation coating paint is applied and baked on the outer periphery of a copper wire with a conductor outer diameter of 0.8 mm by a general method of enamel coating to produce an insulated wire (Example 1) having an insulation coating with a thickness of 0.043 mm. did.

  Regarding the properties of the insulating coating, the appearance of the insulating coating is visually observed, and the viscosity of the insulating coating is measured at room temperature using a cone-plate rotary viscometer (TV-20, manufactured by Toki Sangyo Co., Ltd.). did. Moreover, the thickness of the insulating coating was measured from cross-sectional observation of an insulated wire manufactured using a scanning electron microscope (manufactured by Hitachi, Ltd., S-3500N).

(Example 2)
An insulating coating material was prepared by the same method as in Example 1 except that the mass ratio of the polyamideimide resin and the polyetherimide resin was 100/10. The viscosity of the insulating coating was 2520 mPa · s. After that, the insulation coating paint is applied and baked on the outer periphery of a copper wire having a conductor outer diameter of 0.8 mm by a general method of enamel coating to produce an insulated wire (Example 2) having a thickness of 0.043 mm. did.

(Example 3)
An insulating coating was prepared in the same manner as in Example 1 except that the mass ratio of the polyamideimide resin and the polyetherimide resin was 100/150. The viscosity of the insulating coating was 720 mPa · s. Thereafter, the insulation coating is applied and baked on the outer periphery of a copper wire having a conductor outer diameter of 0.8 mm by a general method of enamel coating to produce an insulated wire having a thickness of 0.042 mm (Example 3). did.

Example 4
An insulating coating material was prepared by the same method as in Example 1 except that the mass ratio of the polyamideimide resin and the polyetherimide resin was 100/5. The viscosity of the insulating coating was 2550 mPa · s. Thereafter, the insulation coating is applied and baked on the outer periphery of a copper wire having a conductor outer diameter of 0.8 mm by a general method of enamel coating to produce an insulated wire having a thickness of 0.044 mm (Example 4). did.

(Comparative Example 1)
An insulating coating was prepared in the same manner as in Example 1 except that the mass ratio of the polyamideimide resin and the polyetherimide resin was 100/160. The viscosity of the insulating coating was 700 mPa · s. Thereafter, the insulation coating is applied and baked on the outer circumference of a copper wire having a conductor outer diameter of 0.8 mm by a general method of enamel coating to produce an insulated wire having a thickness of 0.044 mm (Comparative Example 1). did.

(Comparative Example 2)
Insulating film was produced in the same manner as in Example 1 except that the mass ratio of the polyamideimide resin and the polyetherimide resin was 100/0 (that is, only the polyamideimide resin was used). A paint was made. The viscosity of the insulating coating was 2740 mPa · s. After that, the insulation coating paint is applied and baked on the outer circumference of a copper wire with a conductor outer diameter of 0.8 mm by a general method of enamel coating to produce an insulated wire having a thickness of 0.045 mm (Comparative Example 2). did.

(Comparative Example 3)
Insulation was conducted in the same manner as in Example 1 except that the mass ratio of the polyamideimide resin component and the polyetherimide resin component was 0/100 (that is, only the polyetherimide resin component was used). A coating was prepared. The viscosity of the insulating coating was 600 mPa · s. Thereafter, the insulation coating is applied and baked on the outer periphery of a copper wire having a conductor outer diameter of 0.8 mm by a general method of enamel coating to produce an insulated wire having a thickness of 0.045 mm (Comparative Example 3). did.

  The following test was done with respect to the insulated wires (Examples 1 to 4 and Comparative Examples 1 to 3) produced as described above. The surface of each insulating coating was observed using a scanning electron microscope (manufactured by Hitachi, Ltd., S-3500N), and the microphase separation structure of the insulating coating was determined. In addition, the average diameter of the island component in the sea-island structure was calculated by arbitrarily extracting 50 island components from the photographed images and measuring their diameters.

  The flexibility test of the insulated wire was evaluated by a self-diameter winding method. The self-diameter winding method is a method in which an insulated wire is wound around a round bar (winding bar) having the same diameter as the conductor diameter, and the presence or absence of cracks in the insulating coating is investigated using an optical microscope. In this specification, the insulated wire was wound as 5 coils / coil for 5 coils and observed using a 50 × optical microscope. The case where no crack was observed was defined as “pass”.

  The wear resistance test of the insulating coating was performed as a unidirectional wear test according to the following procedure. The insulated wire was cut out with a length of 120 mm, and the insulation coating on one end was peeled off with an abisofix device to obtain an evaluation sample. A Taber type wear tester (manufactured by Toyo Seiki Co., Ltd.) was used for the wear resistance evaluation. An electrode was attached to the peeled end portion of the evaluation sample, and when a slope was slid while applying a load from the vertical direction to the surface of the insulating coating, the load when electricity was conducted was measured and evaluated.

  The relative dielectric constant of the insulating coating was measured as follows. In the same manner as described above, a strip-shaped evaluation film of 25 μm (thickness) × 2 mm × 100 mm was produced. Relative permittivity of film for evaluation by cavity resonator perturbation method (cavity resonator perturbation method dielectric constant measuring device: Kanto Electronics Application Development, S-parameter vector network analyzer: Agilent Technologies 8720ES) Frequency: 10 GHz).

  The partial discharge start voltage was measured according to the following procedure. Two insulated wires having a length of 500 mm were cut out and twisted while applying a tension of 14.7 N (1.5 kgf) to prepare a twisted pair sample having nine twisted portions in the range of 120 mm in the central portion. After peeling off the insulating coating at the sample edge 10 mm, the partial discharge starting voltage was measured using a partial discharge automatic test system. The measurement conditions were an atmosphere with a relative humidity of 50% at 25 ° C., and the twisted pair sample was charged while increasing the voltage of 50 Hz at 10 to 30 V / s. The voltage at which 50 pC discharge occurred 50 times in the twisted pair sample was defined as the partial discharge start voltage.

  The evaluation method of Tg (glass transition temperature) of the insulating coating was performed as follows. A strip-shaped evaluation film of 25 μm (thickness) × 5 mm × 200 mm was prepared using each insulating coating. Using a dynamic viscoelasticity measuring device (DVA-200, manufactured by IT Measurement Control Co., Ltd.), the storage elastic modulus at 100Hz vibration of the evaluation film is measured while increasing the temperature from room temperature to 400 ° C at 10 ° C / min. The temperature at the inflection point at which the storage elastic modulus at the time of 100 Hz vibration decreases is defined as Tg.

  Various measurement evaluation results are shown in Table 1.

  As shown in Table 1, the insulated wires (Examples 1 to 4) according to the present invention had 1000 Vp without increasing the thickness of the insulating coating formed on the conductor (at a maximum thickness of 45 μm). It turns out that it has the above partial discharge start voltage. That is, according to the present invention, it is possible to provide an insulated wire having a high partial discharge start voltage with a thickness equivalent to that of a conventional insulation coating. In addition, the insulated wires (Examples 1 to 4) according to the present invention have a high balance of mechanical characteristics (flexibility test results and wear resistance test results) in addition to the partial discharge start voltage. I understand. From this, it is considered that the insulated wire according to the present invention also has sufficient resistance (mechanical characteristics) to the winding process and the rolling process. On the other hand, it can be seen that all of the insulated wires (Comparative Examples 1 to 3) deviating from the provisions of the present invention have an insulating coating thickness of about 45 μm and cannot obtain a partial discharge start voltage of 1000 Vp or more. That is, the insulated wires (Comparative Examples 1 to 3) that deviate from the provisions of the present invention have a thickness equivalent to that of the conventional insulation coating and cannot obtain a high partial discharge starting voltage.

  As described above, the insulated wire according to the present invention is an insulating wire on which an insulating film made of a polymer alloy containing an amorphous thermoplastic resin (A) and an amorphous thermosetting resin (B) is formed. The amorphous thermosetting resin (B), which is an electric wire, is composed of a polyamide-imide resin having a repeating unit represented by the chemical formula 2, and the insulating coating has a sea-island structure, and is amorphous thermosetting. The resin (B) forms a sea component having a sea-island structure, and the amorphous thermoplastic resin (A) forms a island component having a sea-island structure. With this feature, it was confirmed that an insulated wire having a high partial discharge starting voltage can be obtained with a thickness equivalent to that of a conventional insulating coating.

Claims (6)

An insulated wire having an insulating coating made of a polymer alloy containing an amorphous thermoplastic resin (A) and an amorphous thermosetting resin (B),
The amorphous thermosetting resin (B) is composed of a polyamide-imide resin having a repeating unit represented by the following chemical formula 1,
The insulating coating has a sea-island structure, the amorphous thermosetting resin (B) constitutes a sea component of the sea-island structure, and the amorphous thermoplastic resin (A) becomes an island component of the sea-island structure. An insulated wire characterized by the following.

[In Chemical Formula 1, R is an aromatic diamine having a divalent aromatic group having three or more aromatic rings, and n is a repeating number, which is a positive integer. ]   The polyamideimide resin having a repeating unit represented by the chemical formula 1 is a synthetic reaction of a diamine component composed of an aromatic diamine having a divalent aromatic group having three or more aromatic rings and an acid component using an azeotropic solvent. The insulated wire according to claim 1, comprising a polyamide-imide resin obtained by reacting an imide group-containing dicarboxylic acid and a diisocyanate component comprising an aromatic diisocyanate.   The polymer alloy is blended with 10 to 150 parts by weight of the amorphous thermoplastic resin (A) with respect to 100 parts by weight of the polyamideimide resin having a repeating unit represented by the chemical formula 1. 2. The insulated wire according to 2.   The insulated wire according to any one of claims 1 to 3, wherein the island component has an average diameter of less than 1 µm.   The insulated wire according to any one of claims 1 to 4, wherein the amorphous thermoplastic resin (A) is made of a polyetherimide resin.   The insulated wire according to any one of claims 1 to 5, wherein the insulating coating has a thickness of 1 µm to 45 µm.