JP2011210519A - Insulated wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulated wire with higher partial discharge starting voltage as compared with a prior art, while having an insulation coating thickness equivalent to a conventional one.SOLUTION: Of the insulated wire with an insulation coating containing at least one layer of an extrusion coating layer formed on a conductor, at least that one layer of the extrusion coating layer is made by extrusion coating of a first resin composition obtained by mixing a resin (A) consisting of polyphenylene sulfide and a resin (B) consisting of syndiotactic polystyrene. In the first resin composition, the resin (A) and the resin (B) are mixed with a ratio of parts by weight of the resin (A) to parts by weight of the resin (B) is in a range of 10/90 to 50/50.

Description

  The present invention relates to an insulated wire used for a coil of an electric device such as a rotating electric machine or a transformer, and more particularly to an insulated wire on which an insulation coating including an extrusion coating layer is formed.

  Insulated wires (enamel-covered insulated wires) used in coils of electrical equipment such as rotating electrical machines and transformers generally have a cross-sectional shape (for example, round shape or rectangular shape) that matches the coil application and shape. It has a structure in which a single-layer or multiple-layer insulation coating is formed on the outer periphery of the molded conductor. As a method for forming the insulating coating, there are a method in which an insulating paint in which a resin is dissolved in an organic solvent is applied and baked on the conductor, and a method in which a resin composition prepared in advance is coated on the conductor by extrusion.

  In recent years, due to the demand for miniaturization of electrical equipment, insulated wires have been wound at high density around small diameter cores under high tension in the coil winding process, and the insulation coating can withstand severe processing stress. Mechanical properties (for example, adhesion and wear resistance) are required. In addition, inverter control and higher voltage are progressing due to demands for higher efficiency and higher output of electrical equipment. As a result, the operating temperature of the coil tends to be higher than before, and the insulation coating is also required to have high heat resistance. In addition, since a higher voltage such as an inverter surge voltage is applied to the coil in the electric device, there has been a problem that the insulation coating may be deteriorated or damaged due to the occurrence of partial discharge.

  In order to prevent deterioration and damage of the insulation coating due to partial discharge, development of insulation coating with a high partial discharge starting voltage is underway. Examples of means for increasing the partial discharge start voltage of the insulating coating include a method using a resin having a low relative dielectric constant for the insulating coating and a method of increasing the thickness of the insulating coating.

  For example, Patent Document 1 discloses an insulating coating material for a winding including a fluorine-based polyimide resin having a specific structure. The insulating coating material described in Patent Document 1 has a relative dielectric constant of 2.3 to 2.8, which is significantly lower than the relative dielectric constant (about 3 to 4) of conventional insulating coatings. It is said that the amount is reduced and deterioration due to heat is suppressed.

  In Patent Document 2, the conductor has at least one enamel baked layer on the outer periphery and at least one extruded coated resin layer on the outer side thereof, and the total thickness of the enamel baked layer and the extruded coated resin layer is 60 μm or more, the thickness of the enamel baking layer is 50 μm or less, the extrusion-coated resin layer has a tensile elastic modulus at 25 ° C. of 1000 MPa or more, and a tensile elastic modulus at 250 ° C. of 10 MPa or more. An inverter surge-insulated wire characterized by being made of a certain resin material (excluding polyether ether ketone) is disclosed. The insulated wire described in Patent Document 2 is said to be able to provide an insulated wire having a high partial discharge starting voltage (about 900 Vp) without lowering the adhesive strength between the conductor and the insulating coating layer.

  Moreover, in patent document 3, it is a multilayer insulated wire of two or more layers which has a conductor and the extrusion insulation layer which coat | covers the said conductor, Comprising: At least 1 layer other than the innermost layer of the said insulation layer is polyphenylene sulfide resin. The insulating layer made of a resin mixture having a continuous layer and an olefin copolymer component as a dispersed phase, the resin mixture comprising 100 parts by mass of a polyphenylene sulfide resin, and 3 to 40 masses of an olefin copolymer component The multilayer insulated wire characterized by containing a part is disclosed. The insulated wire described in Patent Document 3 is said to be excellent in heat resistance and chemical resistance.

JP 2002-56720 A Japanese Patent No. 4177295 Republished 2005-106898

  However, when an insulating coating is formed using an insulating paint made of a fluorine-based polyimide resin as described in Patent Document 1, the dielectric constant of the insulating coating can be lowered, but it is formed from a fluorine-based polyimide resin. Since the insulating coating has low adhesion to the conductor, for example, there is a concern that a phenomenon (coating floating) of the insulating coating may be peeled off from the conductor due to severe processing stress in a coil winding process or the like. Cover floating is a cause of dielectric breakdown in the worst case.

  In addition, as described above, with further increase in efficiency and output of electrical equipment, it is required to improve the seating ratio of insulated wires for coils, and partial discharge starts for insulated wires. Further improvement in voltage (for example, partial discharge start voltage of 1500 Vp or more) is required. Here, it is considered that the conventional insulated wire having the extrusion-coated resin layer as described in Patent Document 2 can increase the partial discharge start voltage by increasing the thickness of the extrusion-coated resin layer. However, since the thickness of the entire insulation coating is also increased, there is a problem that it is difficult to improve the space factor of the insulated wires.

  Accordingly, an object of the present invention is to solve the above-described problems and provide an insulated wire having a partial discharge start voltage higher than that of the prior art while having an insulation coating thickness equivalent to that of the prior art.

  In order to achieve the above object, the present invention provides an insulated wire in which an insulation coating including at least one extrusion coating layer is formed on a conductor, and the at least one extrusion coating layer is made of polyphenylene sulfide. A layer obtained by extrusion-coating a first resin composition in which a resin (A) and a resin (B) made of syndiotactic polystyrene are mixed, wherein the first resin composition comprises the resin (A) and the resin Provided is an insulated wire characterized by being mixed with (B) in the range of “(A) / (B) = 10/90 to 50/50” by weight ratio. “10/90 to 50/50” means “10/90 or more and 50/50 or less”.

In order to achieve the above object, the present invention can make the following improvements and changes in the insulated wire according to the present invention.
(1) The insulating coating has a second coating layer between the first coating layer formed of the at least one extrusion coating layer formed on the outer periphery of the conductor and the conductor, and immediately above the conductor. The second coating layer has a formed structure, and is a layer obtained by extrusion coating a second resin composition in which the resin (A) made of polyphenylene sulfide and the resin (C) made of polyamide are mixed. In the second resin composition, the resin (C) and the resin (A) are mixed in a weight part ratio of “(C) / (A) = 5/95 to 30/70”. Yes. “5/95 to 30/70” means “5/95 or more and 30/70 or less”.
(2) The second coating layer is heat-treated at a temperature of 250 ° C. or higher after extrusion coating.
(3) The resin (C) is a resin made of polyamide having a melting point of 280 ° C. or higher.
(4) The resin (C) contains at least one resin selected from the group consisting of nylon 46, nylon 6T, nylon 6I, nylon 9T, and nylon M-5T.

  ADVANTAGE OF THE INVENTION According to this invention, the insulated wire which has a partial discharge start voltage higher than before can be provided, having the insulation coating thickness equivalent to the past.

It is a cross-sectional schematic diagram which shows an example of embodiment of the insulated wire which concerns on this invention. It is a cross-sectional schematic diagram which shows another example of embodiment of the insulated wire which concerns on this invention.

  As a result of intensive studies on the resin composition and structure of the insulating coating in order to improve the partial discharge resistance in the insulated wire, the present inventors have found that the resin (A) made of polyphenylene sulfide and the resin (B) made of syndiotactic polystyrene It has been found that it is effective to form an extrusion coating layer using a resin composition in which is mixed in a predetermined weight part ratio. The present invention has been completed based on these findings.

  Embodiments according to the present invention will be described below. However, the present invention is not limited to the embodiment taken up here, and can be appropriately combined and improved without departing from the scope of the invention. In addition, the same reference numerals are given to the synonymous parts, and redundant description is omitted.

  FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of an insulated wire according to the present invention. As shown in FIG. 1, the insulated wire 1 according to the present invention has an insulating coating 5 (a first coating layer 3 and a second coating layer 4) formed on a conductor 2. The first coating layer 3 is a layer (extrusion coating layer) obtained by extrusion coating a first resin composition in which a resin (A) made of polyphenylene sulfide and a resin (B) made of syndiotactic polystyrene are mixed. In the first resin composition, the resin (A) and the resin (B) are mixed in a weight part ratio of “(A) / (B) = 10/90 to 50/50”. It is characterized by that. By forming at least the first coating layer 3 on the outer periphery of the conductor 2, the partial discharge start voltage higher than the conventional one (for example, a higher partial discharge start voltage of 1500 Vp or more) while having the same insulation coating thickness as the conventional one ) Can be achieved.

  Furthermore, it is preferable to form the second coating layer 4 between the conductor 2 and the first coating layer 3 and immediately above the conductor 2. The second coating layer 4 is a layer (extrusion coating layer) obtained by extrusion coating a second resin composition obtained by mixing a resin (A) made of polyphenylene sulfide and a resin (C) made of polyamide. In the resin composition, the resin (A) and the resin (C) are mixed in a weight ratio of “(B) / (A) = 5/95 to 30/70”. By forming the second coating layer 4 directly on the conductor 2, there is an effect of improving the adhesion between the conductor 2 and the insulating coating 5. In other words, the conductor 2 and the second coating layer 4 are in good contact with each other, and the second coating layer 4 and the first coating layer 3 are in good contact with each other. In addition, although it is preferable to form the 2nd coating layer 4 from a viewpoint of improving adhesiveness more, the case where it is not formed is not denied (refer FIG. 2). FIG. 2 is a schematic cross-sectional view showing another example of the embodiment of the insulated wire according to the present invention.

  In the first coating layer 3, the resin (A) made of polyphenylene sulfide has high heat resistance and high mechanical properties. However, since the relative dielectric constant is about 3.5, a partial discharge occurs when it is present in a high ratio in the insulating coating. It becomes difficult to improve the starting voltage. Therefore, a first resin composition in which a resin (B) made of syndiotactic polystyrene was mixed to reduce the relative dielectric constant was examined. If the ratio (parts by weight) for mixing the resin (A) and the resin (B) is “(A) / (B)> 50/50”, the relative dielectric constant of the first coating layer 3 is sufficient. The partial discharge start voltage is not improved sufficiently. On the other hand, when the weight part ratio becomes “(A) / (B) <10/90”, the resin (A) is too little and the heat resistance and mechanical properties (for example, mechanical strength and wear resistance) decrease. To do.

  On the other hand, in the second coating layer 4, the resin (A) made of polyphenylene sulfide alone may not be sufficient in adhesion to the conductor 2. Therefore, in order to improve the adhesion to the conductor 2, a second resin composition in which a resin (C) made of polyamide was mixed was examined. If the mixing ratio (parts by weight) of resin (A) and resin (C) is "(C) / (A) <5/95", there is too little resin (C) and adhesion to the conductor The improvement effect cannot be obtained sufficiently. On the other hand, when the weight part ratio is “(C) / (A)> 30/70”, the resin (C) is too much and the influence of the polar group in the polyamide molecular structure is relatively increased, It becomes a factor to lower the discharge start voltage.

  As the resin (C), it is preferable to use a resin made of polyamide having a melting point of 280 ° C. or higher. Examples of the polyamide having a melting point of 280 ° C. or higher include nylon 46 which is an aliphatic polyamide, nylon 6T which is an aromatic polyamide (copolycondensation polymer of hexamethylenediamine and terephthalic acid) and nylon 6I (hexamethylenediamine). And isophthalic acid), nylon 9T (nonanediamine and terephthalic acid), nylon M-5T (methylpentadiamine and terephthalic acid), nylon 6T / 66 ( Nylon 6T and nylon 66 copolymer), Nylon 6T / 6I (nylon 6T and nylon 6I copolymer), Nylon 6T / 6I / 66 (Nylon 6T, nylon 6I and nylon 66 copolymer) Nylon 6T / M-5T (a copolymer of nylon 6T and nylon M-5T), nylon 6T / 6 (a copolymer of nylon 6T and nylon 6), and the like. As the resin (C), the above polyamides may be used alone or in combination.

  In addition, as a resin (C) in which the above polyamide is the main component and nylon 6 (polycondensate of ε-caprolactam) or nylon 66 (co-condensation polymer of hexamethylenediamine and adipic acid) is further mixed. Good. In this case, for example, when the resin (C) is thermally analyzed using a differential scanning calorimeter (DSC) at a temperature increase rate of 10 ° C./min, the amount of nylon is within a range that does not decrease the main peak of the melting point. 6 or nylon 66 is preferably mixed.

  It is preferable to heat-treat at a temperature of 250 ° C. or higher after the second resin composition is extrusion coated onto the conductor 2. Thereby, the adhesiveness between the conductor 2 and the second coating layer 4 is further improved. By improving the adhesion, even if the insulated wire 1 is bent to a small diameter (for example, a self-diameter), generation of wrinkles can be prevented and wear resistance is also improved. There is no particular limitation on the heating time, but it is preferable to hold for several tens of seconds to several minutes. Also, the heating method is not particularly limited, and an electric furnace, burner, hot air heating device, induction heating device, or the like can be used. The heating temperature is 100 ° C. or more higher than the glass transition temperature (Tg) of the resin composition, and a great effect is obtained when the heating temperature is 250 ° C. or more, which is the temperature at which the resin composition starts to melt. In addition, when the heating temperature is less than 250 ° C., a further effect by the heat treatment is merely not obtained.

  The thicknesses of the first coating layer 3 and the second coating layer 4 are each preferably 20 μm or more, and the total thickness of the insulating coating 5 is preferably 70 to 100 μm. Moreover, you may add antioxidant, a copper damage inhibitor, a lubricant, a coloring agent, etc. in the resin composition which comprises each coating layer as needed. A lubricating layer may be separately formed on the outer periphery of the first coating layer 3. Further, in order to improve the flexibility of the insulation coating, a resin composition obtained by modifying a polyolefin resin with maleic anhydride or glycidyl methacrylate is blended with the first and / or second resin composition as a secondary material. Also good.

  The material of the conductor 2 is not particularly limited, and a material commonly used in enamel-coated insulated wires (for example, oxygen-free copper or low-oxygen copper) can be used. Furthermore, although the example which has a round-shaped cross section as the conductor 2 was shown in FIG. 1, it is not limited to it, The conductor which has a rectangular-shaped cross section may be sufficient.

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, this invention is not limited to these. In addition, the composition of the resin composition which comprises each insulation coating of Examples 1-10 and Comparative Examples 1-5 was shown in Table 1 and Table 2 which are mentioned later, respectively.

(Production of Examples 1 to 10 and Comparative Examples 1 to 5)
A copper wire having an outer diameter of 1.25 mm was used as a conductor, and the resin composition shown in Tables 1 and 2 was extrusion coated on the outer layer of the copper wire using an extruder to form the shape as shown in FIG. Insulated wires having the shapes (Examples 9 to 10) shown in Examples 1 to 8 and Comparative Examples 1 to 5) and FIG. 2 were produced. In Examples 1-8 and Comparative Examples 1-5, the thickness of the 2nd coating layer was about 20 micrometers, and the 1st coating layer was extrusion-coated so that the whole thickness of an insulation coating might be set to 70-100 micrometers. On the other hand, in Examples 9 to 10, extrusion coating was performed so that the thickness of the first coating layer was 100 μm. The temperature during extrusion coating was about 300 ° C. Furthermore, after the entire insulating coating was extrusion-coated, heat treatment was performed through an electric furnace having a heating temperature (set temperature) of 200 to 300 ° C.

  The following measurements and tests were performed on the insulated wires (Examples 1 to 10 and Comparative Examples 1 to 5) produced as described above.

(1) Partial discharge start voltage measurement 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 39 N (4 kgf) to prepare a twisted pair sample having six twisted portions in the range of 120 mm at the center. The insulating coating at the 10 mm edge of the sample was peeled off with an abisofix device. Thereafter, in order to dry the insulating coating, it was kept in a constant temperature bath at 120 ° C. for 30 minutes and left in a desiccator for 18 hours until it reached room temperature. The partial discharge start voltage was measured using a partial discharge automatic test system (manufactured by Soken Denki Co., Ltd., DAC-6024). 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 (Vp).

(2) Adhesion evaluation Adhesion was evaluated by carrying out a rapid extension test based on JIS C3003. As a result of the rapid extension test, when the length of the insulation coating floats (peel) is 2 mm or less from the breaking point, “◎: Excellent meaning”, 2-20 mm of “○: Meaning of pass”, 20 Those longer than mm were defined as “x: meaning of failure”.

(3) Heat resistance evaluation The heat resistance test was performed in the following procedure. Two pieces of the manufactured insulated wire were cut out at a length of 500 mm and twisted while applying a tension of 39 N (4 kgf) to prepare a twisted pair sample having six twisted parts in the range of 120 mm in the central part. . Next, it was heat-aged by holding at 150 ° C. for 2000 hours in an aging tester (manufactured by Toyo Seiki Co., Ltd., Gear Oven STD60P). Thereafter, a twisted pair sample was wound around a round bar (winding bar) having a diameter of 4 mm, and the presence or absence of cracks in the insulation coating was examined using a 50 × optical microscope. “◎: Excellent” means that no cracks (for example, cracks, crazing, wrinkles) are generated, “O: Means that pass” means that no cracks are generated, and “×” means that cracks are generated. : Meaning of failure.

  The composition and measurement evaluation results of the resin compositions of Examples 1 to 10 are shown in Table 1, and the composition and measurement evaluation results of the resin compositions of Comparative Examples 1 to 5 are shown in Table 2.

  As shown in Table 1, the insulated wires of Examples 1 to 10 according to the present invention have a high partial discharge starting voltage of 1500 Vp or more even with an insulation coating thickness (about 70 to 100 μm) equivalent to that of the prior art. It was confirmed that Furthermore, also about adhesiveness and heat resistance evaluation, it was confirmed that the insulated wire of Examples 1-10 has a favorable characteristic.

  On the other hand, Comparative Example 1 and Comparative Example 2 are examples in which the blending of the resin (A) in the second resin composition is larger than that of the present invention, and the adhesion evaluation and the heat resistance evaluation were unacceptable. It was. Comparative Example 3 is an example in which the blending of the resin (B) in the first resin composition is more than that of the present invention, and the heat resistance was insufficient. Comparative Example 4 is an example in which the blending of the resin (A) is less in the second resin composition than in the present invention and more in the first resin composition than in the present invention, and the partial discharge start voltage The improvement effect of was insufficient. Comparative Example 5 is an example where the melting point of the resin (C) in the second resin composition is lower than the preferred form of the present invention, and the heat resistance evaluation was unacceptable.

  From the above, it was demonstrated that the insulated wires of Examples 1 to 10 according to the present invention have a partial discharge start voltage higher than that of the conventional one while having an insulation coating thickness equivalent to that of the conventional insulated wire. It was done.

  DESCRIPTION OF SYMBOLS 1 ... Insulated electric wire, 2 ... Conductor, 3 ... 1st coating layer, 4 ... 2nd coating layer, 5 ... Insulation coating.

Claims (5)

An insulated wire in which an insulation coating including at least one extruded coating layer is formed on a conductor,
The at least one extrusion coating layer is a layer obtained by extrusion coating a first resin composition in which a resin (A) made of polyphenylene sulfide and a resin (B) made of syndiotactic polystyrene are mixed,
In the first resin composition, the resin (A) and the resin (B) are mixed in a weight part ratio of “(A) / (B) = 10/90 to 50/50”. An insulated wire characterized by that. The insulated wire according to claim 1,
The insulating coating has a second coating layer formed between the first coating layer formed of the at least one extrusion coating layer formed on the outer periphery of the conductor and the conductor, and immediately above the conductor. Has a structure,
The second coating layer is a layer obtained by extrusion-coating a second resin composition obtained by mixing the resin (A) made of polyphenylene sulfide and the resin (C) made of polyamide.
In the second resin composition, the resin (C) and the resin (A) are mixed in a weight ratio of “(C) / (A) = 5/95 to 30/70”. An insulated wire characterized by that. The insulated wire according to claim 2,
The insulated wire according to claim 1, wherein the second coating layer is heat-treated at a temperature of 250 ° C or higher after extrusion coating. In the insulated wire according to claim 2 or claim 3,
The insulated wire, wherein the resin (C) is a resin made of polyamide having a melting point of 280 ° C or higher. In the insulated wire according to any one of claims 2 to 4,
The insulated wire, wherein the resin (C) contains at least one resin selected from the group consisting of nylon 46, nylon 6T, nylon 6I, nylon 9T, and nylon M-5T.

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