JP2007294312A - Insulation wire and electric coil using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulating wire capable of effectively preventing generation of partial discharge, preventing deterioration due to heat generation, and superior in mechanical characteristics and an electric coil using this. <P>SOLUTION: The insulting wire 1 comprises a conductor 2, an insulating layer 3 formed on the conductor 2, and a semiconductive layer 4 formed on the insulating layer 3. This semiconductive layer 4 is constructed of a mixture of resin and carbon black. The surface resistance of the semiconductive layer 4 is established at 10<SP>8</SP>Ω or more and less than 10<SP>12</SP>Ω. As a result, generation of partial discharge can be prevented effectively. Furthermore, deterioration of the surface of the insulating wire 1 due to heat generation can be prevented effectively, and mechanical characteristics (flexibility) of the insulating wire 1 can be improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an insulated wire used for a motor coil and the like, and an electric coil formed by the insulated wire.

  Conventionally, in an insulated wire used as a coil winding of a rotating electrical machine such as a motor, a severe partial discharge (corona discharge) occurs on the surface of the insulating film when used in a state where a high voltage is applied. . And when the said partial discharge generate | occur | produced, the effect | action of the ozone and ion which generate | occur | produced local temperature accelerated | stimulated, and the insulating layer deteriorated rapidly, As a result, the problem that the lifetime of an apparatus shortened had arisen.

  In particular, in recent years, in order to obtain a small and high-power motor, it is desired to increase the voltage applied to the coil, and therefore, there is a problem that partial discharge is likely to occur. Therefore, suppression of partial discharge is strongly desired.

  Thus, an electric coil is disclosed in which an insulated wire in which a conductive layer made of a varnish such as a polyimide resin containing a conductive oxide is formed on a conductor is wound to suppress partial discharge. More specifically, the electric coil uses a conductive layer obtained by baking and applying an insulating paint obtained by mixing triiron tetroxide, talc, and silica on a polyimide resin, and the content of the polyimide resin is 100. Assuming parts by weight, the content of ferric tetroxide, talc and silica is set to 5 to 100 parts by weight. And according to this structure, since the discharge charge amount of a conductor is suppressed, it describes that corona resistance improves (for example, refer patent document 1).

An electric coil using an insulated wire in which a conductive layer having a predetermined surface resistance value is formed on an insulating layer formed on a conductor is disclosed. More specifically, in the insulated wire, an insulating layer made of polyamide-imide is formed on the conductor, and the insulating layer is made of an oil-based enamel mixed with carbon black as a conductive filler, and has a surface resistance. A conductive layer set to 1 kΩ to 1 MΩ is formed. And according to this structure, since the electric potential difference of the surface of the said insulated wire can be made low compared with the breakdown voltage of the air between insulated wires, generation | occurrence | production of partial discharge is described (for example, patent document 2). reference).
JP-A-10-41122 JP 2004-254457 A

  However, in the electric coil described in Patent Document 1, since the specific gravity of the conductive oxide is large, the dispersibility of the conductive oxide in the conductive layer decreases and the conductive oxide aggregates in the insulating layer. There has been a problem that the mechanical properties (flexibility) of the insulated wire are lowered.

  Moreover, in the electric coil described in Patent Document 2, the partial discharge start voltage is improved. However, as described above, the surface resistance of the conductive layer is set to 1 kΩ to 1 MΩ, so that the electric coil is formed by an insulated wire. The capacitance of the electric coil increases. As a result, there has been a problem that the leakage current during AC energization increases and the surface of the insulated wire deteriorates due to heat generation (generation of Joule heat).

  Therefore, the present invention has been made in view of the above problems, and can effectively prevent the occurrence of partial discharge, prevent deterioration due to heat generation, and an insulated wire excellent in mechanical characteristics. It aims at providing the used electric coil.

In order to achieve the above object, an invention according to claim 1 is an insulated wire having a conductor, an insulating layer formed on the conductor, and a semiconductive layer formed on the insulating layer. The conductive layer is composed of a mixture of a resin and carbon black, and the surface resistance of the semiconductive layer is 10 ⁸ Ω or more and less than 10 ¹² Ω. Here, “surface resistance” refers to a resistance value specific to the material of the semiconductive layer, and refers to a resistance value (unit: Ω) per 1 cm width of an insulated wire in which the semiconductive layer is provided with a thickness of 5 μm. In addition, this surface resistance is obtained from an insulated electric wire having a conductor having a diameter of 1.0 mm, an insulating layer having a thickness of 30 μm formed on the conductor, and a semiconductive layer having a thickness of 5 μm formed on the insulating layer. The electrode spacing is 1 mm on the surface, silver paste is applied so that the electrode width is 1 cm to form three electrodes, and the resistance value between the electrodes can be measured and calculated.

According to this configuration, since the surface resistance of the semiconductive layer is less than 10 ¹² Ω, it is possible to maintain an equipotential state between the semiconductive layers between the insulated wires forming the electric coil. Therefore, the concentration of the electric field between the insulated wires when a high voltage is applied is alleviated, and no voltage is applied to the air existing between the insulated wires, so that the partial discharge start voltage becomes high and the occurrence of partial discharge is effective. Can be prevented. As a result, it is possible to effectively prevent the occurrence of dielectric breakdown due to partial discharge.

In addition, since the surface resistance of the semiconductive layer is 10 ⁸ Ω or more, the capacitance between the insulated wires forming the electric coil is reduced, and the leakage current flowing between the insulated wires can be reduced during AC energization. Become. As a result, it is possible to effectively suppress deterioration of the semiconductive layer of the insulated wire due to heat generation.

In addition, since the surface resistance of the semiconductive layer is 10 ⁸ Ω or more and less than 10 ¹² Ω, it is possible to achieve both a high partial discharge start voltage and a small leakage current during AC energization between the insulated wires forming the electric coil. It becomes possible.

When the surface resistance of the semiconductive layer is 10 ¹² Ω or more, the equipotential state between the semiconductive layers cannot be maintained between the insulated wires forming the electric coil. Therefore, the partial discharge start voltage between the insulated wires forming the coil is reduced to 1 kV or less. Therefore, when high voltage is applied, the concentration of electrolysis between insulated wires cannot be relaxed, partial discharge occurs in the air existing between the insulated wires, and the deterioration of the insulating layer proceeds at an accelerated rate. As a result, the lifetime of the device is shortened. In addition, when the surface resistance of the semiconductive layer is less than 10 ⁸ Ω, the capacitance between the insulated wires forming the electric coil increases, and the leakage current flowing between the insulated wires when energized with alternating current increases. Therefore, the semiconductive layer of the insulated wire is deteriorated by heat generation, and as a result, the life of the device is shortened.

  Further, by using carbon black having excellent dispersion stability with respect to the resin, it is possible to avoid aggregation of carbon black in the semiconductive layer. Therefore, the mechanical characteristics (flexibility) of the insulated wire can be improved.

  In addition, from the viewpoint of applying to a wide range of applications such as a motor and an electric coil that load a high voltage, the insulated wire according to claim 1 as in the invention according to claim 2, wherein the conductor has a diameter of It is preferable that it is 0.1 mm-3.0 mm.

  According to a third aspect of the present invention, there is provided an electric coil formed by winding the insulated wire according to the first or second aspect. According to this structure, since it is set as the structure provided with the insulated wire of Claim 1 or Claim 2, it becomes possible to acquire the same effect as the insulated wire of Claim 1.

The invention according to claim 4 is the electric coil according to claim 3, wherein another semiconductive layer made of a mixture of resin and carbon black is provided between the insulated wires, and the other half The surface resistance of the conductive layer is 10 ⁸ Ω or more and less than 10 ¹² Ω. Here, the “surface resistance” means a resistance value specific to the material of the semiconductive layer. Similar to the surface resistance according to claim 1, the width of the insulated wire provided with the semiconductive layer with a thickness of 5 μm is 1 cm. The resistance value (unit is Ω). In addition, this surface resistance is obtained from an insulated electric wire having a conductor having a diameter of 1.0 mm, an insulating layer having a thickness of 30 μm formed on the conductor, and a semiconductive layer having a thickness of 5 μm formed on the insulating layer. The electrode spacing is 1 mm on the surface, silver paste is applied so that the electrode width is 1 cm to form three electrodes, and the resistance value between the electrodes can be measured and calculated.

According to this configuration, another semiconductive layer having a surface resistance of 10 ⁸ Ω or more and less than 10 ¹² Ω, which is formed of a mixture of resin and carbon black, is provided between the insulated wires of the electric coil. Even when the contact between the insulated wires forming the electric coil is insufficient, it is possible to achieve both a high partial discharge start voltage and a small leakage current during AC energization.

In addition, when there is no other semiconductive layer having a surface resistance of 10 ⁸ Ω or more and less than 10 ¹² Ω, which is composed of a mixture of resin and carbon black, between the insulated wires of the electric coil, When the contact between the insulated wires forming the electric coil is insufficient, the equipotential state of the semiconductive layer cannot be maintained between the insulated wires forming the electric coil. Therefore, the partial discharge start voltage between the insulated wires forming the coil is reduced to 1 kV or less. As a result, when high voltage is applied, the concentration of electrolysis between insulated wires cannot be relaxed, partial discharge occurs in the air existing between insulated wires, and the deterioration of the insulating layer proceeds at an accelerated rate. As a result, the lifetime of the device is shortened.

The invention according to claim 5 is an electric coil formed by winding an insulated wire having a conductor and an insulating layer formed on the conductor, and is composed of a mixture of resin and carbon black between the insulated wires. The semiconductive layer is provided, and the surface resistance of the semiconductive layer is 10 ⁸ Ω or more and less than 10 ¹² Ω.

According to this configuration, a semiconductive layer made of a mixture of resin and carbon black and having a surface resistance of 10 ⁸ Ω or more and less than 10 ¹² Ω is provided between the insulated wires of the electric coil. Even when the contact between the insulated wires forming the coil is insufficient, it is possible to achieve both a high partial discharge start voltage and a small leakage current during AC energization.

In addition, it is a case where the semiconductive layer which is composed of a mixture of resin and carbon black and has a surface resistance of 10 ⁸ Ω or more and less than 10 ¹² Ω is not provided between the insulated wires of the electric coil, When the contact between the insulated wires forming the conductor is insufficient, the equipotential state of the semiconductive layer cannot be maintained between the insulated wires forming the electric coil. Therefore, the partial discharge start voltage between the insulated wires forming the coil is reduced to 1 kV or less. As a result, when high voltage is applied, the concentration of electrolysis between insulated wires cannot be relaxed, partial discharge occurs in the air existing between insulated wires, and the deterioration of the insulating layer proceeds at an accelerated rate. As a result, the lifetime of the device is shortened.

  According to the present invention, it is possible to effectively prevent the occurrence of dielectric breakdown due to partial discharge in an insulated wire. In addition, it is possible to effectively suppress the surface of the insulated wire from being deteriorated by heat generation. In addition, the mechanical characteristics (flexibility) of the insulated wire can be improved.

Hereinafter, a preferred embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing the structure of an insulated wire forming an electric coil according to the present embodiment.
As shown in FIG. 1, an insulated wire 1 includes a conductor 2, an insulating layer 3 formed on the conductor 2, and a mixture of a resin and a conductive filler such as carbon black formed on the insulating layer 3. And a semiconductive layer 4. And as shown in FIG. 2, the electric coil 5 for rotary electric machines, such as a motor, is formed by winding the said insulated wire 1, for example.

  Here, the conductor 2 is not particularly limited as long as the necessary power transmission capacity can be secured, and the material and configuration are not particularly limited. Examples of the material include copper wire, tin-plated copper wire, and aluminum wire. , Aluminum alloy wire, steel core aluminum wire, copper fly wire, nickel-plated copper wire, silver-plated copper wire, copper-covered aluminum wire, and the like. In addition, it is preferable that the diameter of the conductor 2 is 0.1 mm-3.0 mm from a viewpoint of applying to wide uses, such as a motor and an electric coil which load a high voltage.

  The resin used for the insulating layer 3 is not particularly limited as long as it is a resin having high insulation and high heat resistance, but a resin having a long-term insulation heat-resistant temperature of 150 ° C. or higher is preferable. Polyimide resin, polyamideimide resin, polyester Imide resin, H-type polyester resin, and the like can be preferably used. By setting the long-term insulating heat-resistant temperature of the insulating layer 3 to 150 ° C. or higher, it is possible to obtain an insulated wire that can withstand long-term use at high temperatures. In addition, these resin may be used independently and may be used in combination of 2 or more type.

  The long-term insulation heat resistance temperature referred to here is the heat resistance temperature indicated by the heat resistance index of JISC3003-1999. The dielectric breakdown voltage after heat treatment at a predetermined temperature for 20000 hours is a predetermined test voltage (the thickness of the film is In the case of 0.071 to 0.090 mm, the predetermined temperature is 1 KV).

  Moreover, the semiconductive layer 4 in this embodiment is comprised with the mixture of resin and a conductive filler. Here, the resin constituting the semiconductive layer 4 is not particularly limited as long as it has a long-term insulating heat-resistant temperature of 150 ° C. or higher and has adhesiveness by heating. More specifically, polyethersulfone resin, polyetherimide resin, polyetheretherketone resin, tetrafluoroethylene / hexafluoropropylene copolymer resin, thermoplastic polyimide resin, polyamideimide resin, polyesterimide resin, and H type Examples include polyester resins. In addition, these resin may be used independently and may be used in combination of 2 or more type.

  In these resins, when a polyethersulfone resin, polyetherimide resin, polyetheretherketone resin, tetrafluoroethylene / hexafluoropropylene copolymer resin, or thermoplastic polyimide resin is used, high insulation and adhesion can be obtained. As well as high hydrolysis properties. In addition, when a polyethersulfone resin or a polyetherimide resin is used, the removal process of the semiconductive layer 4 at the terminal portion of the electric coil 5 necessary for preventing conduction between the semiconductive layer 4 and the conductor 2 is performed by an organic solvent. This can be easily performed, and the productivity of the electric coil 5 and the motor is increased.

  In addition, the resin which comprises the semiconductive layer 4 may add a plastic component in order to improve the adhesiveness by heating in the range which does not impair the characteristic, and may be polymer-alloyed. Moreover, it is good also as a structure which adds a hardening component in order to improve the heat resistance after the fusion | melting by heating.

  The semiconductive layer 4 is formed of a kneaded material (conductive material) obtained by kneading the above-described resin with a conductive filler. Examples of the conductive filler include conductive particles such as carbon black, carbon nanotubes, gold, silver, and the like. In the present invention, carbon black is preferably used. . This is because conductive carbon black has better dispersion stability with respect to resin compared to conductive fillers made of metal particles, so the stirring process for preventing aggregation of conductive fillers is simple or unnecessary. This is because the semiconductive layer 4 can be manufactured at low cost. Further, by using carbon black as the conductive filler, as described above, since the carbon black is excellent in dispersion stability with respect to the resin, the conductive filler is aggregated in the semiconductive layer 4. It can be avoided. Therefore, the mechanical characteristics (flexibility) of the insulated wire 1 can be improved.

  As a method for forming the semiconductive layer 4, a method in which a varnish kneaded with a conductive filler is applied to a solution in which a resin is dissolved in an organic solvent and baked, or a mixture in which a conductive filler is melt kneaded in a resin is melted. Examples of the method include extrusion. Moreover, the thickness of the formed semiconductive layer 4 is preferably 1 μm to 10 μm.

  In addition, for each of the insulating layer 3 and the semiconductive layer 4, a material in which two or more kinds of materials are combined may be used, but each of them may be configured by stacking layers made of different materials. For example, the insulating layer 3 may have two or more layers, and the semiconductive layer 4 may be formed on the outermost layer of the insulating layer 3.

  The insulating layer 3 and the semiconductive layer 4 may contain various additives such as a lubricant and a small amount of an inorganic filler. Furthermore, an insulating lubricating layer may be formed on the surface of the electric coil 5 within a range where the corona suppressing effect after the fusion treatment is not lowered. Forming the insulating lubricating layer is preferable because the workability when the insulated wire 1 is wound to form the electric coil 5 is improved and the insulating layer 3 is hardly damaged.

Here, in this embodiment, the semiconductive layer 4 is composed of a mixture of a resin and carbon black, and the surface resistance of the semiconductive layer 4 is 10 ⁸ Ω or more and less than 10 ¹² Ω. There is.

Thus, by making the surface resistance of the semiconductive layer 4 less than 10 ¹² Ω, there is no surface potential difference between the semiconductive layers 4 between the insulated wires 1 forming the electric coil 5, and the semiconductive layers 4 An equipotential state can be maintained. Therefore, when the electric coil 5 is loaded with a high voltage, the concentration of the electric field between the insulated wires 1 is alleviated, and no voltage is applied to the air existing between the insulated wires 1, so that the partial discharge start voltage increases, The occurrence of discharge can be effectively prevented. As a result, it is possible to effectively prevent the occurrence of dielectric breakdown due to partial discharge.

In addition, by setting the surface resistance of the semiconductive layer 4 to 10 ⁸ Ω or more, the capacitance between the insulated wires 1 forming the electric coil 5 is reduced, and the leakage current flowing between the insulated wires 1 is reduced when alternating current is applied. It becomes possible to do. As a result, it is possible to effectively suppress degradation of the semiconductive layer 4 of the insulated wire 1 due to heat generation (generation of Joule heat). Note that the leakage current I of the electric coil 5 referred to here is, when the capacitance of the electric coil 5 is C, the applied voltage to the electric coil 5 is V, and the frequency of the applied voltage V is f = I = Set by 2πfCV.

In addition, since the surface resistance of the semiconductive layer 4 is 10 ⁸ Ω or more and less than 10 ¹² Ω, a high partial discharge start voltage and a small leakage current during AC energization are compatible between the insulated wires 1 forming the electric coil 5. It becomes possible to make it.

  In the present embodiment, the partial discharge start voltage is preferably 1 kV or more. As described above, in recent years, in order to obtain a small and high output motor, it is desired to increase the voltage applied to the electric coil 5, but the partial discharge start voltage is set to 1 kV or more. This is because even when the voltage applied to the electric coil 5 is set high, the occurrence of partial discharge can be prevented.

  Moreover, it is preferable that the electrostatic capacity of the electric coil 5 is less than 2 nF in the electric coil 5 formed by, for example, arranging two insulated wires 1 in parallel and winding them. This is because, when the defective value of the electric coil 5 is detected with respect to the electric coil 5 formed by the insulated wire 1 based on the value of the leakage current described above, if the electric coil 5 has a capacitance of 2 nF or less, the leakage This is because the current value is also small, so that it can be used as a good product.

  The conductivity of the semiconductive layer 4 composed of a mixture of resin and carbon black can be adjusted by the characteristics of carbon black (pH, average particle diameter of primary particles, DBP oil absorption, etc.). .

  For example, since the surface functional group of carbon black captures π electrons that play a role of conduction, the conductivity of the carbon black compounded resin can be controlled. Moreover, the surface functional group of the carbon black can be indirectly evaluated by the pH and hydrogen content of the carbon black. In addition, pH of carbon black means the value when the liquid mixture of carbon black and distilled water is measured with an electrode meter.

  Further, when the average particle size of the primary particles of carbon black is reduced, the number of carbon black particles per unit weight is increased, so that the distance between the carbon black particles in the matrix resin is reduced. Therefore, the conductivity of the semiconductive layer 4 composed of a mixture of resin and carbon black is improved. In addition, the average particle diameter of the primary particles of carbon black can be evaluated by the arithmetic average diameter by observation using a transmission electron microscope.

  Furthermore, the DBP oil absorption (dibutyl phthalate oil absorption) measured according to JIS K6217-4 of the carbon black used represents the degree of development of carbon black aggregation based on the bonds between the carbon black particles. However, when the DBP oil absorption amount increases, the conductivity of the semiconductive layer 4 formed of a mixture of resin and carbon black is improved.

Moreover, while providing the other semiconductive layer (not shown) comprised with the mixture of resin and carbon black mentioned above between the insulated wires 1 which comprise the electric coil 5, surface resistance of the said other semiconductive layer is provided. May be set to 10 ⁸ Ω or more and less than 10 ¹² Ω. With such a configuration, even when the contact between the insulated wires 1 forming the electric coil 5 is insufficient, it is possible to achieve both a high partial discharge start voltage and a small leakage current during AC energization.

  As another method for forming the semiconductive layer, for example, the insulated wire 1 constituting the electric coil 5 is impregnated in a varnish obtained by kneading carbon black in a solution obtained by dissolving a resin in an organic solvent, and the varnish is cured. By making it, the method of forming another semiconductive layer between the insulated wires 1 which comprise the electric coil 5 is mentioned.

Moreover, it is good also as a structure which provides a semiconductive layer between the insulated wires which comprise an electric coil instead of providing the semiconductive layer 4 in the above-mentioned insulated wire 1. FIG. That is, in an electric coil (not shown) formed by winding an insulated wire (not shown) having a conductor 2 and an insulating layer 3 formed on the conductor 2, a resin and carbon black are interposed between the insulated wires. A semiconductive layer (not shown) made of a mixture may be provided, and the surface resistance of the semiconductive layer may be set to 10 ⁸ Ω or more and less than 10 ¹² Ω. With such a configuration, even when the contact between the insulated wires forming the electric coil is insufficient, it is possible to achieve both a high partial discharge start voltage and a small leakage current during AC energization.

  Below, this invention is demonstrated based on an Example and a comparative example. In addition, this invention is not limited to these Examples, These Examples can be changed and changed based on the meaning of this invention, and they are excluded from the scope of the present invention. is not.

Example 1
(Production of insulated wires)
1500 g of a polyethersulfone resin (manufactured by Sumitomo Chemical Co., Ltd., trade name Sumika Excel 4800G), 15 g of an antioxidant (manufactured by API Corporation, trade name Seenox 412S), 4054 g of an organic solvent (N- Methyl-2-pyrrolidone) to prepare a polyethersulfone solution having a solid content of 27%. The temperature during dissolution was 80 ° C., and the dissolution time was 3 hours. Next, carbon black (Mitsubishi) having a specific gravity of 1.4, a pH of 6.5, an average primary particle size of 55 nm, and a DBP oil absorption of 130 ml / 100 g with respect to 100 parts by weight of the produced polyethersulfone solution. A polyethersulfone varnish containing carbon black was prepared by kneading the product of Chemical Co., Ltd. (trade name # 3030B) to 13 parts by weight. In addition, the dispersibility of carbon black in the polyethersulfone varnish was good, and the good dispersibility was maintained even after being left for 10 days. Next, a polyamideimide insulating varnish (made by Taoka Chemical Industry Co., Ltd., trade name AE2) is applied on a copper conductor having a diameter of 0.996 mm in a vertical baking furnace to form an insulating layer. Then, the above-described polyethersulfone varnish containing carbon black was applied and baked to form a semiconductive layer on the insulating layer to produce an insulated wire. The finished outer diameter of the insulated wire was 1.067 mm, the thickness of the insulating layer was 30.5 μm, and the thickness of the semiconductive layer was 5.0 μm. Further, in the manufactured insulated wire, no abnormality in the appearance in the normal state was observed.

(Measurement of surface resistance)
Next, a silver paste having a width of 1 cm (manufactured by Fujikura Kasei Co., Ltd., trade name Doutite D550) was applied to the surface of the manufactured insulated wire, and three electrodes were formed at intervals of 1 cm. Then, using an insulation resistance meter (product name 4329A, manufactured by Yokogawa Hewlett-Packard Co., Ltd.) or a digital multimeter (product name 7544, manufactured by Yokogawa Electric Corp.), the resistance value between the electrodes was measured. The surface resistance of the semiconductive layer was measured by calculating the average value. The results are shown in Table 1.

(Measurement of partial discharge start voltage)
Next, using the produced insulated wire, two stranded wires are produced in accordance with the two-strand method defined in JIS C3003-1999, and the partial discharge start voltage of the two stranded wires is subjected to a partial discharge test. It measured using the machine (Mitsubishi Electric Cable Co., Ltd. make, brand name QM-50). The results are shown in Table 1. In addition, the discharge amount start threshold value of the partial discharge start voltage was set to 100 pC.

(Measurement of capacitance)
Next, the produced two insulated wires are arranged in parallel and wound around a pipe made of polyvinyl chloride having a diameter of 60 mm so that the insulated wires are in contact with each other 20 times to produce an electric coil. The semiconductive layer 20 mm at the end of the wire is removed with N-methyl-2-pyrrolidone, and the capacitance between the two insulated wires is measured by an LCZ meter (trade name 4276A, manufactured by Yokogawa Hewlett-Packard Co., Ltd.). It measured using. The results are shown in Table 1. In addition, the frequency of the voltage applied to the insulated wire was measured as 1 kHz.

(Example 2)
Carbon black (manufactured by Mitsubishi Chemical Co., Ltd., trade name # 3030B) was kneaded to 15 parts by weight with respect to 100 parts by weight of the polyethersulfone solution to prepare a polyethersulfone varnish containing carbon black. Except for this, an insulated wire was produced in the same manner as in Example 1 described above. In addition, the dispersibility of carbon black in the polyethersulfone varnish was good, and the good dispersibility was maintained even after being left for 10 days. Further, under the same conditions as in Example 1 described above, the surface resistance was measured, the partial discharge start voltage was measured, and the capacitance was measured. The results are shown in Table 1.

(Example 3)
Carbon black having a specific gravity of 1.4, a pH of 6.5, an average primary particle size of 38 nm, and a DBP oil absorption of 135 ml / 100 g based on 100 parts by weight of the produced polyethersulfone solution (Tokai Carbon ( Co., Ltd., trade name Talker Black # 4400) was kneaded to 13 parts by weight to produce a polyethersulfone varnish containing carbon black, and a copper conductor with a diameter of 0.997 mm was used. In the same manner as in Example 1 described above, an insulated wire was produced. In addition, the dispersibility of carbon black in the polyethersulfone varnish was good, and the good dispersibility was maintained even after being left for 10 days. Further, under the same conditions as in Example 1 described above, the surface resistance was measured, the partial discharge start voltage was measured, and the capacitance was measured. The results are shown in Table 1.

(Comparative Example 1)
An insulated wire was produced in the same manner as in Example 1 except that carbon black was not kneaded with the polyethersulfone solution and a copper conductor having a diameter of 0.993 mm was used. The finished outer diameter of the insulated wire was 1.065 mm, the thickness of the insulating layer was 30.5 μm, and the thickness of the semiconductive layer was 5.5 μm. Further, under the same conditions as in Example 1 described above, the surface resistance was measured, the partial discharge start voltage was measured, and the capacitance was measured. The results are shown in Table 2.

(Comparative Example 2)
Carbon black (trade name # 3030B, manufactured by Mitsubishi Chemical Corporation) was kneaded to 10 parts by weight with respect to 100 parts by weight of the polyethersulfone solution to prepare a polyethersulfone varnish containing carbon black. Insulated wires were produced in the same manner as in Example 1 except that a copper conductor having a diameter of 1.000 mm was used. The finished outer diameter of the insulated wire was 1.074 mm, the thickness of the insulating layer was 30.0 μm, and the thickness of the semiconductive layer was 6.5 μm. Further, the dispersibility of carbon black in the polyethersulfone varnish was good, and the good dispersibility was maintained even after being left for 10 days. Further, under the same conditions as in Example 1 described above, the surface resistance was measured, the partial discharge start voltage was measured, and the capacitance was measured. The results are shown in Table 2.

(Comparative Example 3)
Carbon black (manufactured by Mitsubishi Chemical Corporation, trade name # 3030B) was kneaded to 100 parts by weight of the polyethersulfone solution to 17 parts by weight to prepare a polyethersulfone varnish containing carbon black. Except for this, an insulated wire was produced in the same manner as in Example 1 described above. In addition, the dispersibility of carbon black in the polyethersulfone varnish was good, and the good dispersibility was maintained even after being left for 10 days. Further, under the same conditions as in Example 1 described above, the surface resistance was measured, the partial discharge start voltage was measured, and the capacitance was measured. The results are shown in Table 2.

(Comparative Example 4)
Carbon black (manufactured by Tokai Carbon Co., Ltd., trade name Talker Black # 4400) is kneaded with 100 parts by weight of the polyethersulfone solution so as to be 10 parts by weight. An insulated wire was produced in the same manner as in Example 3 except that it was produced and a copper conductor having a diameter of 1.000 mm was used. The finished outer diameter of the insulated wire was 1.074 mm, the thickness of the insulating layer was 30.0 μm, and the thickness of the semiconductive layer was 6.5 μm. Further, the dispersibility of carbon black in the polyethersulfone varnish was good, and the good dispersibility was maintained even after being left for 10 days. Further, under the same conditions as in Example 1 described above, the surface resistance was measured, the partial discharge start voltage was measured, and the capacitance was measured. The results are shown in Table 2.

(Comparative Example 5)
To 100 parts by weight of the polyethersulfone solution, carbon black (trade name Talker Black # 4400, manufactured by Tokai Carbon Co., Ltd.) is kneaded to 15 parts by weight, and a polyethersulfone varnish containing carbon black is mixed. An insulated wire was produced in the same manner as in Example 3 except that it was produced and a copper conductor having a diameter of 0.996 mm was used. The finished outer diameter of the insulated wire was 1.067 mm, the thickness of the insulating layer was 30.5 μm, and the thickness of the semiconductive layer was 5.0 μm. Further, the dispersibility of carbon black in the polyethersulfone varnish was good, and the good dispersibility was maintained even after being left for 10 days. Further, under the same conditions as in Example 1 described above, the surface resistance was measured, the partial discharge start voltage was measured, and the capacitance was measured. The results are shown in Table 2.

(Comparative Example 6)
To 100 parts by weight of the polyethersulfone solution prepared in Example 1, triiron tetroxide having a specific gravity of 5.2 (manufactured by Wako Pure Chemical Industries, Ltd.) was kneaded so as to be 50 parts by weight. A polyethersulfone varnish containing triiron oxide was prepared. However, the stability of the produced polyethersulfone varnish was poor, and the dispersibility of triiron tetroxide in the polyether sulfone varnish was poor, and the triiron tetroxide was precipitated after standing for 10 days. Therefore, an insulated wire could not be produced. For the same reason, the surface resistance, the partial discharge start voltage, and the capacitance cannot be measured.

(Comparative Example 7)
Talc is blended to 100 parts by weight of the prepared polyethersulfone solution so that talc (trade name: Microace P4, manufactured by Nippon Talc Co., Ltd.) having a specific gravity of 2.8 is mixed with talc. In addition to producing the polyethersulfone varnish, an insulated wire was produced in the same manner as in Example 1 except that a copper conductor having a diameter of 1.017 mm was used. The finished outer diameter of the insulated wire was 1.093 mm, the thickness of the insulating layer was 31.5 μm, and the thickness of the semiconductive layer was 6.5 μm. Further, the dispersibility of talc in the polyethersulfone varnish was poor, and talc was precipitated after standing for 10 days. Further, under the same conditions as in Example 1 described above, the surface resistance was measured, the partial discharge start voltage was measured, and the capacitance was measured. The results are shown in Table 2.

  As shown in Table 1, in Examples 1 to 3, it can be seen that in any case, the partial discharge start voltage is high (1 kV or more), and it has good partial discharge characteristics. Moreover, it turns out that the electrostatic capacitance of an electric coil is small (less than 2 nF), and the leakage current at the time of alternating current supply can be made small. On the other hand, in Comparative Examples 1, 2, 4, and 7, as shown in Table 2, in all cases, although the capacitance of the electric coil is small (2 nF or less), the partial discharge start voltage is low (less than 1 kV) It can be seen that good partial discharge characteristics cannot be obtained. In Comparative Examples 3 and 5, as shown in Table 2, in any case, although the partial discharge start voltage is high (1 kV or more) and has good partial discharge characteristics, the capacitance of the electric coil is large. (2 nF or more), it can be seen that the leakage current during AC energization cannot be reduced. Moreover, in Comparative Example 6, as described above, the stability of the produced polyethersulfone varnish was poor, and an insulated wire could not be produced.

As shown in Table 1, the semiconductive layer used in each of Examples 1 to 3 is composed of a mixture of resin (polyethersulfone resin) and carbon black, and the semiconductive layer It is considered that the surface resistance is 10 ⁸ Ω or more and less than 10 ¹² Ω.

  As examples of utilization of the present invention, examples of utilization of the present invention include insulated wires used for motor coils and the like, and electric coils formed by the insulated wires.

It is sectional drawing which shows the structure of the insulated wire which concerns on this embodiment. It is a perspective view which shows the structure of the electric coil formed with the insulated wire which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulated wire, 2 ... Conductor, 3 ... Insulating layer, 4 ... Semiconductive layer, 5 ... Electric coil

Claims (5)

An insulated wire having a conductor, an insulating layer formed on the conductor, and a semiconductive layer formed on the insulating layer,
The semiconductive layer is composed of a mixture of a resin and carbon black, and the surface resistance of the semiconductive layer is 10 ⁸ Ω or more and less than 10 ¹² Ω.   The insulated wire according to claim 1, wherein the conductor has a diameter of 0.1 mm to 3.0 mm.   An electric coil comprising the insulated wire according to claim 1 or 2 wound thereon. Another semiconductive layer composed of a mixture of the resin and the carbon black is provided between the insulated wires, and the surface resistance of the other semiconductive layer is 10 ⁸ Ω or more and less than 10 ¹² Ω. The electric coil according to claim 3. An electric coil formed by winding an insulated wire having a conductor and an insulating layer formed on the conductor,
A semiconductive layer made of a mixture of resin and carbon black is provided between the insulated wires, and the surface resistance of the semiconductive layer is 10 ⁸ Ω or more and less than 10 ¹² Ω, .

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