JP2015099742A - Inverter surge-resistant insulation wire and method for production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter surge resistant insulation wire excellent in all of adhesive strength of a conductor and a resin layer coating the conductor, adhesive strength of an enamel layer and a film layer such as an extrusion coating resin layer, wear resistance, solvent resistance and characteristics maintaining the electrical insulation properties before and after processing and further, capable of maintaining excellent heat aging resistance over a long period, and to provide a method for production of the wire.SOLUTION: An inverter surge resistant insulation wire has at least one enamel printed layer and at least one extrusion coated resin layer outside on the outer periphery of a conductor having a rectangular cross section, and has an adhesion layer having a thickness of 2-20 μm between the enamel printed layer and the extrusion coated resin layer. Every extrusion coated resin layer on the adhesion layer comprises the same resin. The sectional shapes of the enamel printed layer and the extrusion coated resin layer in the cross section of the insulation wire are rectangular. In the rectangular sectional shape formed by the enamel printed layer and the extrusion coated resin layer surrounding the conductor in a sectional view, the thickness of the enamel printed layer is 60 μm or less and that of the extrusion coated resin layer is 200 μm or less in both of two sides of at least a pair of two sides of two pairs facing up and down or on the sides of the conductor. The resin of the enamel printed layer is polyamide-imide and that of the extrusion coated resin layer has a melting point of 300-370°C. The breakdown voltage of the insulation wire after heat treatment at 300°C for 168 hrs is 90% or more compared with that before heat treatment.

Description

  The present invention relates to an inverter surge resistant wire and a method for manufacturing the same.

  Inverters have come to be attached to many electrical devices as efficient variable speed control devices. The inverter is switched at several kHz to several tens of kHz, and a surge voltage is generated for each pulse. Inverter surge is a phenomenon in which reflection occurs at a discontinuous point of impedance in the propagation system, for example, at the beginning and end of the connected wiring, and as a result, a voltage twice as large as the inverter output voltage is applied. In particular, an output pulse generated by a high-speed switching element such as an IGBT has a high voltage agility, so that even if the connection cable is short, the surge voltage is high, and further, the voltage attenuation by the connection cable is also small. A voltage nearly twice as large is generated.

  Insulator-related equipment, such as high-speed switching elements, inverter motors, transformers and other electrical equipment coils, use mainly insulated wires that are enameled wires as magnet wires. Moreover, as described above, in inverter-related equipment, a voltage nearly twice as high as the inverter output voltage is applied, so that it is possible to minimize inverter surge deterioration of enameled wire, which is one of the materials constituting these electrical equipment coils. It is becoming required.

  The inverter surge deterioration of the enameled wire is a phenomenon in which partial discharge occurs in the insulating wire due to a surge voltage having a high peak value generated in the inverter, and the coating of the insulating wire causes deterioration due to the partial discharge, that is, high frequency partial discharge deterioration.

If the enamel layer is made thicker in order to suppress inverter surge deterioration, the number of times of passing through the baking furnace in the manufacturing process increases, and the thickness of the copper oxide film on the copper surface that is the conductor grows. Adhesive strength with the enamel layer decreases. For example, when an enamel layer having a thickness of 60 μm or more is obtained, the number of passes through the baking furnace exceeds 12 times. It has been found that if the baking furnace is passed more than 12 times, the adhesion between the conductor and the enamel layer is extremely reduced.
On the other hand, there is a method of increasing the thickness that can be applied by one baking so as not to increase the number of times of passing through the baking furnace, but in this method, the solvent of the varnish cannot be completely evaporated and remains as bubbles in the enamel layer. There were drawbacks.

  By the way, conventionally, an attempt has been made to improve the characteristics by providing a coating resin outside the enameled wire. Examples of conventional techniques in which an enamel layer is provided with an extrusion coating layer include Patent Documents 1 and 2. In an insulated wire provided with such a coating resin, adhesion between the enamel layer and the coating resin is also required. In addition to this, a technique (Patent Document 3) tackled from the viewpoint of partial discharge starting voltage and adhesion between a conductor and an enamel layer, and an attempt to make two extrusion-coated resin layers (Patent Document 4) can be mentioned.

  Further, in recent electrical equipment, various performances such as heat resistance, mechanical characteristics, chemical characteristics, electrical characteristics, reliability, and the like have been required to be further enhanced from conventional ones. Among them, insulation wires such as enameled wires used as magnet wires for space electrical equipment, aircraft electrical equipment, nuclear electrical equipment, energy electrical equipment, and automotive electrical equipment have excellent wear resistance. However, heat aging characteristics and solvent resistance have been demanded. For example, in recent electrical equipment, it may be required that excellent heat aging characteristics can be maintained for a longer period of time.

  In addition, in recent years, electrical devices represented by motors and transformers have become smaller and have higher performance, and there are many uses such as pushing insulated wires into very narrow parts. became. Specifically, it is no exaggeration to say that the performance of a rotating machine such as a motor is determined depending on how many wires can be put in the stator slot. As a result, the ratio (space factor) of the conductor cross-sectional area to the stator slot cross-sectional area has become very high. When the electric wire having a round cross-section is densely filled in the stator slot, the gap that becomes a dead space and the cross-sectional area of the insulating film become a problem. For this reason, as means for improving the space factor, very recently, it has been attempted to use a rectangular wire whose cross-sectional shape is similar to a square shape (square or rectangle). The use of a flat wire has a dramatic effect on improving the space factor, but it is difficult to uniformly apply an insulating film on a flat conductor, especially for an insulated wire with a small cross-sectional area. It is not so popular because it is difficult to control.

  The characteristics of the insulating film necessary for coiling a motor or a transformer include a characteristic for maintaining electrical insulation before and after coil processing (hereinafter referred to as electrical insulation characteristics before and after processing). Even if the cross-sectional shape of the conductor is a rectangular wire, if the wire film is damaged by the coil processing step, the electrical insulation performance is lowered, resulting in loss of product reliability.

Various methods are conceivable for imparting the electrical insulation property before and after the processing to the electric wire film. For example, there is a method in which lubricity is imparted to the film to reduce the coefficient of friction and to reduce damage during coil processing.
However, adding lubrication performance to the coating does not improve the strength of the wire coating itself, so it seems to be effective against trauma factors, but there are actually limitations to the effect of coil processing. It was.

  On the other hand, an adhesive layer is also provided between the enamel layer on the conductor and the extrusion-coated resin layer (see Patent Documents 3 and 4).

Japanese Patent Publication No. 7-031944 JP-A 63-195913 JP 2005-203334 A JP 2010-123390 A

  The present invention provides adhesion strength between a conductor and a resin layer covering the conductor, adhesion strength between coating layers such as an enamel layer and an extrusion-coated resin layer, wear resistance, solvent resistance, and electrical insulation before and after processing. It is an object of the present invention to provide an inverter surge insulation wire that is excellent in all of the characteristics and can maintain excellent heat aging characteristics over a long period of time, and a method for manufacturing the same.

In the above-described prior art, particularly the insulated wires shown in Patent Documents 3 and 4, since the adhesive strength between the coating layers is not sufficient, an adhesive layer is provided between the enamel layer and the extrusion-coated resin layer. Further studies were conducted on the provided insulated wires.
As a result, in the insulated wire in which the adhesive layer is provided between the enamel layer and the extrusion-coated resin layer, the characteristics of the resin constituting the extrusion-coated resin layer, the thickness of the adhesive layer, the thickness of each of the enamel layer and the extrusion-coated resin layer And the total thickness was found to be important for solving the problem. The present invention has been made based on this finding.

That is, the said subject is solved by the following means.
(1) An inverter surge-insulating wire having at least one enamel-baked layer on the outer periphery of a conductor having a rectangular cross section and at least one extrusion-coated resin layer on the outside thereof, the enamel-baked layer And the extrusion coating resin layer, and the extrusion coating resin layer on the adhesion layer is made of the same resin, and the enamel in the cross section of the inverter surge insulation wire The cross-sectional shape of the baking layer and the extrusion-coated resin layer is rectangular, and in the rectangular cross-sectional shape formed by the enamel baking layer and the extrusion-coated resin layer surrounding the conductor in a cross-sectional view, with respect to the conductor At least one of the two pairs of two sides facing each other in the vertical direction or the right and left sides has a thickness of the enamel baking layer of 60 μm or less and a thickness of the extrusion coating resin layer of 200 μm or less. The resin of the enamel baking layer is polyamideimide, the resin of the extrusion-coated resin layer has a melting point of 300 ° C. or higher and 370 ° C. or lower, and the inverter surge insulation wire is insulated after heat treatment at 300 ° C. for 168 hours. An inverter surge resistant wire characterized by having a breakdown voltage of 90% or more as compared with that before heat treatment.
(2) The inverter surge-insulated wire according to (1), wherein the extrusion-coated resin layer is one layer.
(3) The inverter surge insulation wire according to (1) or (2), wherein the adhesive strength between the coating layers of the inverter surge insulation wire is 100 g or more and less than 400 g.
(4) In the rectangular cross-sectional shape formed by the enamel-baked layer and the extrusion-coated resin layer surrounding the conductor in a cross-sectional view, at least of two pairs of two sides facing the conductor vertically or horizontally The inverter-resistant inverter according to any one of (1) to (3), wherein a total thickness of the enamel baking layer and the extrusion-coated resin layer is 80 μm or more for both of the pair of two sides Surge insulated wire.
(5) The extrusion coating resin layer is a layer of at least one thermoplastic resin selected from the group consisting of polyetheretherketone, modified polyetheretherketone, thermoplastic polyimide, and aromatic polyamide. The inverter surge insulation wire according to any one of (1) to (4).
(6) The adhesive layer is a layer of at least one thermoplastic resin selected from the group consisting of polyetherimide, polyphenylsulfone, and polyethersulfone (1) to (5) ) Inverter surge resistant wire according to any one of the above.
(7) Extrusion coating in which the adhesive layer is formed by baking a varnished resin on the outer periphery of the enamel baking layer, and then becomes a molten state at a temperature higher than the glass transition temperature of the resin used for the adhesive layer A thermoplastic resin forming a resin layer is extruded and brought into contact with the adhesive layer, and the extrusion coating resin layer is formed by thermally fusing the extrusion coating resin through the adhesive layer to the enamel baking layer. The manufacturing method of the inverter surge-proof insulated wire of any one of (1)-(6).

  The inverter surge-insulating wire of the present invention has an adhesive strength between a conductor and a resin layer covering the conductor, an adhesive strength between an enamel layer and a coating layer such as an extrusion-coated resin layer, wear resistance, solvent resistance, and before and after processing. It is excellent in both of the electrical insulating property maintaining properties and the heat aging property can be maintained over a long period of time.

The inverter surge-insulating wire of the present invention has at least one enamel-baked layer on the outer periphery of the conductor, and at least one extrusion-coated resin layer on the outer side thereof, and the enamel layer and the extrusion-coated resin layer. Inverter surge insulated wire having an adhesive layer in between.
Accordingly, the present invention solves the problems of the present invention in an inverter surge-insulated wire having at least an enamel-baked layer, an adhesive layer, and an extrusion-coated resin layer on the outer periphery of a conductor.
The thickness of the adhesive layer is 2 to 20 μm, the thickness of the enamel baking layer is 60 μm or less, the thickness of the extrusion coating resin layer is 200 μm or less, the resin of the enamel baking layer is polyamideimide, and the extrusion coating resin layer The resin has a melting point of 300 ° C. or more and 370 ° C. or less, and the inverter surge insulated wire has a dielectric breakdown voltage after heat treatment at 300 ° C. for 168 hours is 90% or more as compared with that before heat treatment.

(conductor)
As the conductor in the insulated wire of the present invention, those conventionally used for insulated wires can be used. Preferably, the oxygen content is low oxygen copper of 30 ppm or less, more preferably 20 ppm or less. Copper or oxygen-free copper conductor. If the oxygen content is 30 ppm or less, when the conductor is melted with heat to prevent welding, voids due to oxygen contained in the welded portion are not generated, and the electrical resistance of the welded portion is prevented from deteriorating. The strength of the welded portion can be maintained.
Further, the conductor having a desired cross-sectional shape can be used, but in terms of the occupation ratio with respect to the stator slot, a conductor having a shape other than a circle is preferable, and a rectangular shape is particularly preferable. Furthermore, in terms of suppressing partial discharge from the corner, it is desirable that the shape has chamfers (radius r) at the four corners.

(Enamel baking layer)
The enamel-baked layer (hereinafter also simply referred to as “enamel layer”) in the insulated wire of the present invention is formed of at least one layer of enamel resin, and may be one layer or a plurality of layers.
In the present invention, the term “one layer” means that the resin constituting the layer and the additive to be contained are the same layer when the same layer is laminated. The number of layers is counted when the composition composing the layers is different, such as when the amount is different.
The same applies to layers other than the enamel layer.

In the present invention, polyamideimide is used as the enamel resin for forming the enamel layer.
In the present invention, when enamel resin layers are laminated in a plurality of layers, it is preferable to use the same resin between these layers, and each layer is preferably made of one kind of resin. In the present invention, the case where the enamel layer is one layer is particularly preferable.

  Even if the thickness of the enamel layer is increased, the number of passing through a baking furnace when forming the enamel layer can be reduced, and the adhesive force between the conductor and the enamel layer can be prevented from being extremely reduced. It is preferable that it is 50 micrometers or less. Moreover, in order not to impair the withstand voltage characteristic and the heat resistance characteristic, which are characteristics necessary for an enameled wire as an insulating wire, it is preferable that the enamel layer has a certain thickness. The thickness of the enamel layer is not particularly limited as long as it does not cause pinholes, and is preferably 3 μm or more, more preferably 10 μm or more, and further preferably 30 μm or more. In this preferred embodiment, the thickness of each enamel layer provided on one of the two sides and the other two sides is 60 μm or less.

  This enamel layer can be formed by applying and baking a resin varnish containing the above-mentioned enamel resin on a conductor, preferably a plurality of times. The method of applying the resin varnish may be a conventional method, for example, a method using a varnish application die having a similar shape to the conductor shape, and a “universal die” formed in a cross-beam shape if the conductor cross-sectional shape is a square. There is a method using a so-called die. The conductor coated with these resin varnishes is baked in a baking furnace in a conventional manner. The specific baking conditions depend on the shape of the furnace used, but if it is a natural convection type vertical furnace of about 5 m, the passage time is set to 10 to 90 seconds at 400 to 500 ° C. Can be achieved.

(Extruded resin layer)
The extrusion-coated resin layer in the insulated wire of the present invention is provided at least one layer outside the enamel layer, and may be one layer or a plurality of layers. In the present invention, when a plurality of extrusion-coated resin layers are provided, the same resin is used between the layers. That is, a layer formed of the same resin as that contained in the extrusion-coated resin layer closest to the enamel layer side is laminated. Here, as long as the resin is the same, the presence / absence, type, and blending amount of additives other than the resin may be different between the respective layers. In the present invention, the extrusion-coated resin layer is preferably one or two layers, particularly preferably one layer.

The extrusion coating resin layer is a thermoplastic resin layer, and the thermoplastic resin forming the extrusion coating resin layer is an extrudable thermoplastic resin, in addition to heat aging characteristics, electrical insulation before and after processing. A thermoplastic resin having a melting point of 310 ° C. or higher and 370 ° C. or lower is used in that it has excellent maintenance characteristics, an enamel layer, an extrusion-coated resin layer, adhesive strength, and solvent resistance. The lower limit of the melting point is preferably 330 ° C. or higher, and the upper limit of the melting point is preferably 360 ° C. or lower. The melting point of the thermoplastic resin can be measured by differential scanning calorimetry (DSC) by a method described later.
This thermoplastic resin has a relative dielectric constant of preferably 4.5 or less, and more preferably 4.0 or less. Here, the relative dielectric constant can be measured with a commercially available dielectric constant measuring apparatus. The measurement temperature and frequency are changed as necessary. In the present invention, unless otherwise specified, it means values measured at 25 ° C. and 50 Hz.

Examples of the thermoplastic resin forming the extrusion coating resin layer include polyether ether ketone (PEEK), modified polyether ether ketone (modified PEEK), thermoplastic polyimide (PI), and polyamide having an aromatic ring (referred to as aromatic polyamide). ), Polyester having an aromatic ring (referred to as aromatic polyester), polyketone (PK) and the like. Among these, at least one thermoplastic resin selected from the group consisting of polyetheretherketone, modified polyetheretherketone, thermoplastic polyimide, and aromatic polyamide is preferred, and in particular, polyetheretherketone resin, modified polyetherether Ketone resins are preferred. Among these thermoplastic resins, a thermoplastic resin having a melting point of 300 ° C. or higher and preferably a relative dielectric constant of 4.5 or lower is used. One type of thermoplastic resin may be used, or two or more types may be used. The thermoplastic resin may be blended with other resins, elastomers, or the like as long as at least the melting point does not deviate from the above range.
In the present invention, polyether ether ketone resins and modified polyether ether ketone resins are preferred, but these may be used alone or in a blended form, but it is particularly preferred to use them alone.

  The thickness of the extrusion-coated resin layer is 200 μm or less, and 180 μm or less is preferable for realizing the effects of the invention. If the thickness of the extrusion-coated resin layer is too thick, a portion that is whitened on the surface of the insulated wire may be generated when the insulated wire is wound around an iron core and heated. Thus, if the extrusion-coated resin layer is too thick, the extrusion-coated resin layer itself has rigidity, so that the flexibility as an insulating wire is poor, which affects the change in electrical insulation maintaining characteristics before and after processing. Sometimes. On the other hand, the thickness of the extrusion-coated resin layer is preferably 5 μm or more, more preferably 15 μm or more, and even more preferably 40 μm or more from the viewpoint of preventing poor insulation. In this preferred embodiment, each of the extrusion-coated resin layers provided on one of the two sides and the other two sides has a thickness of 200 μm or less.

The extrusion-coated resin layer can be formed by extruding the thermoplastic resin described above into an enamel layer formed on a conductor. The conditions at the time of extrusion molding, for example, the extrusion temperature conditions are appropriately set according to the thermoplastic resin to be used. As an example of a preferable extrusion temperature, specifically, in order to obtain a melt viscosity suitable for extrusion coating, the extrusion temperature is set at a temperature about 40 ° C. to 60 ° C. higher than the melting point. Thus, when the extrusion coating resin layer is formed by extrusion molding, it is not necessary to pass through a baking furnace when forming the coating resin layer in the manufacturing process, so without growing the thickness of the oxide film layer of the conductor, There is an advantage that the thickness of the insulating layer, that is, the extrusion-coated resin layer can be increased.
When forming an extrusion coating resin layer by extrusion molding, after extruding the thermoplastic resin on the enamel layer, cool it for 10 seconds or more, for example, cool it with water, or put the thermoplastic resin on the enamel layer. After extrusion, for example, by water cooling to about 250 ° C. and then exposing to the outside temperature for 2 seconds or more, a desired breakdown voltage can be maintained.

(Adhesive layer)
The adhesive layer is a layer of a thermoplastic resin, and any resin may be used as the thermoplastic resin as long as the extrusion-coated resin layer can be thermally fused to the enamel layer. Such a resin is preferably an amorphous resin that is easily dissolved in a solvent because it needs to be varnished. Furthermore, it is preferable that the resin is excellent in heat resistance in order not to lower the heat resistance as an insulating wire. In view of these, preferable thermoplastic resins include, for example, polysulfone (PSU), polyethersulfone (PES), polyetherimide (PEI), polyphenylsulfone (PPSU) and the like. Among these, at least one selected from the group consisting of polyetherimide, polyphenylsulfone and polyethersulfone, which is an amorphous resin having a glass transition temperature (Tg) exceeding 200 ° C. and excellent in heat resistance. It is preferably a kind of thermoplastic resin, more preferably polyetherimide having high compatibility with the extrusion coating resin.

The thickness of the adhesive layer is 2 to 20 μm, more preferably 3 to 15 μm, further preferably 3 to 12 μm, and particularly preferably 3 to 10 μm.
Further, the adhesive layer may have a laminated structure of two or more layers. In this case, the resins of the respective layers are preferably the same resin. In the present invention, the adhesive layer is preferably one layer.

  If the adhesive force between the extrusion-coated resin layer and the enamel layer is not sufficient, when severe processing conditions such as bending to a small radius, wrinkles of the extrusion-coated resin layer may occur inside the bending arc. is there. When such wrinkles occur, a space is generated between the enamel layer and the extrusion-coated resin layer. Therefore, it is necessary to prevent wrinkles from occurring inside the arc of bending. By introducing a layer having an adhesive function between them to further increase the adhesive strength, the generation of wrinkles as described above can be highly prevented. Since the insulated wire of the present invention has high adhesive strength between the enamel layer and the extrusion-coated resin layer, it is possible to effectively prevent inverter surge deterioration. Moreover, problems such as delamination during processing can be solved by further increasing the adhesive strength between the enamel layer and the extrusion-coated resin layer.

The adhesive layer can be formed by baking the above-described thermoplastic resin on the enamel layer formed on the conductor. The insulated wire in another preferred embodiment of the present invention having such an adhesive layer is preferably formed by baking a varnished thermoplastic resin on the outer periphery of the enamel layer, and then forming the adhesive layer. By extruding and contacting the thermoplastic resin forming the extrusion coating resin layer, which is in a molten state at a temperature higher than the glass transition temperature of the resin used for the adhesion layer in the extrusion coating process, onto the adhesion layer and the extrusion layer It can be manufactured by thermally fusing the coating resin layer.
In this manufacturing method, in order to sufficiently heat-bond the adhesive layer, that is, the enamel layer and the extrusion-coated resin layer, the heating temperature of the thermoplastic resin forming the extrusion-coated resin layer in the extrusion coating process is as follows. It is preferably at least the glass transition temperature (Tg) of the thermoplastic resin to be formed, more preferably at a temperature higher by 30 ° C. than Tg, and particularly preferably at a temperature higher by 50 ° C. than Tg. Here, the heating temperature of the thermoplastic resin forming the extrusion coating resin layer is the temperature of the die portion.
The solvent for varnishing the thermoplastic resin forming the adhesive layer may be any solvent that can dissolve the selected thermoplastic resin.

In this preferred embodiment, the total thickness of the enamel layer and the extrusion-coated resin layer is preferably 80 μm or more. A total thickness of 50 μm or more is preferable from the viewpoint of preventing inverter surge deterioration. This total thickness is particularly preferably 100 μm or more from the viewpoint that inverter surge deterioration can be highly prevented. In this preferred embodiment, at least the total thickness of the two enamel layers on one side and the extrusion coating resin layer is 80 μm or more, and the total thickness of the enamel layer on the other side and the extrusion coating resin layer is 50 μm. It is preferable that the total thickness of the enamel layer and the extrusion-coated resin layer provided on both two sides is 80 μm or more, and the total thickness of at least one of the two sides is preferable. Is more preferably 100 μm or more, particularly preferably the total thickness of both of the two sides is 100 μm or more.
In addition, when the thickness of the extrusion coating resin layer is different between the pair of two opposing sides of the cross section and the other pair of two opposing sides, the thickness of the pair of two opposing sides is already 1. The thickness of a pair of two opposing sides is preferably in the range of 1.01 to 5, more preferably in the range of 1.01 to 3.

  As described above, when the thickness of the enamel layer is 60 μm or less, the thickness of the extrusion-coated resin layer is 200 μm or less, and the total thickness of the enamel layer and the extrusion-coated resin layer is 80 μm or more, the inverter surge deterioration can be prevented. The adhesive strength between the resin layer covering this and the adhesive strength between the coating layers such as the enamel layer and the extrusion-coated resin layer can be satisfied. In addition, the total thickness of the enamel layer and the extrusion-coated resin layer is preferably 260 μm or less, and more preferably 235 μm or less in order to be able to process without problems in consideration of the electrical insulation property before and after processing.

  Therefore, the insulating wire in this preferred embodiment has high adhesive strength between the conductor and the coating layer such as the enamel layer and the adhesive strength between the coating layers. These adhesive strengths are measured by, for example, JIS C 3003 enamel wire test method. Adhesion, 8.1b) It can be performed in the same manner as the torsion method, and can be evaluated by the number of revolutions until enamel layer floats. The same can be done for a rectangular wire having a square cross section. In the present invention, the number of rotations until the enamel layer floats or the upper film layer floats between the film layers is 15 rotations or more, and the adhesive wire in this preferred embodiment has good adhesion. The number of rotations is 15 or more.

  Specifically, the adhesive strength between the conductor and the coating layer (coating layer) and the adhesive strength between the coating layers are measured as follows, and preferred adhesive strengths thereof are as follows.

(Adhesive strength with conductor)
An electric wire sample from which only the insulating coating layer closest to the conductor of the insulated wire is partially peeled is set in a tensile tester (for example, a tensile tester “Autograph AG-X” manufactured by Shimadzu Corporation) at a speed of 4 mm / min. When the extrusion-coated resin layer is peeled upward (180 ° C. peeling), the tensile load at which floating occurs is the adhesive strength.
The case where the tensile load at which lifting occurs is 20 g or more and less than 100 g is preferable, and 40 g or more and less than 100 g is particularly preferable.

(Adhesive strength between coating layers)
An electric wire sample from which only the extrusion coating resin layer of the insulated wire has been partially peeled is set in a tensile tester (for example, tensile tester “Autograph AG-X” manufactured by Shimadzu Corporation), and the extrusion coating resin at a speed of 4 mm / min. When the layer is peeled upward (180 ° C. peeling), the tensile load at which floating occurs is the adhesive strength.
The case where the tensile load in which the float has occurred is preferably 100 g or more and less than 400 g.

  When the adhesive strength between the coating layers is 400 g or more, the adhesive strength is too strong, so when one of the two layers undergoes oxidative degradation or thermal degradation and cracks occur in the coating, the other layer degrades. Even if not, it may crack with the layer that caused the crack.

  The insulated wire of the present invention is also excellent in insulation performance. The superiority or inferiority of the insulation performance can be judged by the level of the dielectric breakdown voltage value of the electric wire. A high dielectric breakdown voltage indicates high reliability as an electric wire. The enamel layer is PAI (40 μm), the adhesive layer is PEI (6 μm), the extrusion coating resin layer is PEEK (20 μm), the total film thickness is 66 μm, the enamel layer is PAI (15 μm), the adhesive layer is PEI (6 μm), extruded Since the insulation breakdown voltage of an insulating wire having a coating film layer of PEEK (42 μm) and an overall film thickness of 63 μm is less than 10 kV, the reliability as an electric wire is inevitably low. On the other hand, the insulation breakdown voltage of an insulated wire with an enamel layer of PAI (40 μm), an adhesive layer of PEI (5 μm), and an extrusion coating resin layer of PEEK (40 μm) with an overall film thickness of 85 μm exceeds 10 kV, and is reliable as an electric wire. Sex is fully satisfied. It can be said that an insulated wire having an overall film thickness of 85 μm or more has higher reliability.

  The measuring method of the dielectric breakdown voltage is as follows. A straight piece of insulated wire is cut out by 300 mm, an aluminum foil is wound around the central portion, the coating layer of one end of 300 mm is peeled off, and a current is passed between the terminal peeling portion and the aluminum foil portion. The voltage is increased at 500 V / min, and the voltage causing dielectric breakdown is read.

  The total film thickness of the insulated wire of the present invention is preferably 85 μm or more, more preferably 85 μm or more and less than 280 μm, and still more preferably 85 to 250 μm in terms of the above insulation performance.

The insulated wire of the present invention is excellent in heat aging characteristics. This heat aging characteristic is an index for maintaining reliability that the insulation performance does not deteriorate for a long time even when used in a high temperature environment. The dielectric breakdown voltage after heat treatment at 300 ° C. for 168 hours is the same as that before heat treatment. Compared to the dielectric breakdown voltage, it is 90% or more.
The dielectric breakdown voltage after heat treatment at 300 ° C. is measured as follows, and the dielectric breakdown voltage change ratio is obtained.

(Measurement of dielectric breakdown voltage after heat treatment at 300 ° C)
A straight piece of insulated wire is cut out by 300 mm and heat-treated at 300 ° C. for 168 hours. After the heat treatment, an aluminum foil is wound around the central portion, the coating layer of one end of 300 mm is peeled off, and current is passed between the end peeling portion and the aluminum foil portion. The voltage is increased at 500 V / min, and the voltage causing dielectric breakdown is measured.
When this voltage is V ₁ and the pre-heating breakdown voltage is V ₀ , the breakdown voltage change ratio is obtained by the following equation.

Dielectric breakdown voltage change ratio = (V ₁ / V ₀ ) × 100

In this invention, it is excellent also in the electrical insulation maintenance characteristic before and behind a process.
The electrical insulation property before and after processing is evaluated by measuring the dielectric breakdown voltage before and after heating by winding around an iron core as follows.

(Iron core winding, dielectric breakdown voltage measurement after heating)
The electrical insulating property before and after heating is evaluated as follows.
An insulating wire is wound around an iron core having a diameter of 30 mm, heated to 280 ° C. in a thermostatic bath, and held for 30 minutes. After being taken out of the thermostat, the iron core is inserted into a copper grain while being wound around the iron core, and the one end wound is connected to the electrode and can be kept energized for 1 minute without causing dielectric breakdown at a voltage of 10 kV. Is preferred.

  As described above, the insulated wire of the present invention selects the thermoplastic resin that forms the extrusion-coated resin layer, and has high adhesive strength between the conductor and the coating layer or the coating layer. Excellent in resistance and solvent resistance. Abrasion resistance is an indicator of the degree of scratches when an insulated wire is processed into a motor or the like, and a static friction coefficient is a degree of ease of insertion into a stator slot. Solvent resistance is required for insulated wires due to diversification of usage environment and assembly process.

  For example, the abrasion resistance is 25 ° C. according to JIS C 3003 enamel wire test method. It can be evaluated in the same manner as wear resistance (round line). When the cross-sectional shape is a flat wire, the four corners are used. Specifically, using a wear tester determined by JIS C 3003, the film is slid in one direction until the film peels off under a certain load. The scale from which the film is peeled is read, and it can be evaluated that the product of the scale value and the load used is 2000 g or more, which is very excellent. In the insulated wire of the present invention, the product of the above-described scale value and the load used is 2000 g or more.

  The solvent resistance is, for example, as described in JIS C 3003 enamel wire test method. What was wound according to flexibility can be performed by immersing the film in a solvent for 10 seconds and then visually checking the surface of the enamel layer or the extrusion-coated resin layer. In the present invention, three types of solvents, acetone, xylene and styrene, are used, and the temperature is set according to two levels of normal temperature and 150 ° C. (the sample is immersed in a solvent in a hot state after being heated at 150 ° C. for 30 minutes). If there is no abnormality on the surface of the enamel layer or the extrusion-coated resin layer, it can be evaluated as very excellent. The insulating wire of the present invention is not found on the surfaces of the enamel layer and the extrusion-coated resin layer even when the solvent is acetone, xylene, or styrene, or at room temperature and 150 ° C.

(Insulated wire manufacturing method)
The method of manufacturing the insulated wire is as described for the individual layers.
That is, an extrusion coating resin in which a varnished resin is baked on the outer periphery of the enamel baking layer to form the adhesive layer, and then becomes a molten state at a temperature higher than the glass transition temperature of the resin used for the adhesive layer. A thermoplastic resin forming a layer is extruded and brought into contact with the adhesive layer, and the extrusion coating resin layer is formed by thermally fusing the extrusion coating resin to the enamel baking layer through the adhesive layer.
Here, in the present invention, the adhesive layer is not coated by extrusion, but is provided by applying a varnished resin.

The inverter surge-insulating wire of the present invention has an adhesive strength between a conductor and a resin layer covering the conductor, an adhesive strength between an enamel layer and a coating layer such as an extrusion-coated resin layer, wear resistance, solvent resistance, and before and after processing. It is excellent in any of the electrical insulation properties at the same time, and can further maintain excellent heat aging properties over a long period of time.
Therefore, the inverter surge-proof insulated wire (hereinafter simply referred to as “insulated wire”) of the present invention is suitable for heat-resistant windings. For example, electrical equipment such as inverter-related equipment, high-speed switching elements, inverter motors, transformers, etc. It can be used for coils, space electrical equipment, aircraft electrical equipment, nuclear electrical equipment, energy electrical equipment, magnet wire for automotive electrical equipment, and the like.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

Example 1
A flat rectangular conductor (copper having an oxygen content of 15 ppm) having a corner chamfer radius r = 0.3 mm of 1.8 × 3.4 mm (thickness × width) was prepared. When forming the enamel layer, a polyamideimide resin (PAI) varnish (manufactured by Hitachi Chemical Co., Ltd., trade name: HI406) is coated on the conductor using a die similar to the shape of the conductor, and set to 450 ° C. The oven was passed through a baking oven having a length of 8 m at a speed that would result in a baking time of 15 seconds, and an enamel having a thickness of 5 μm was formed in this single baking process. By repeating this eight times, an enamel layer having a thickness of 40 μm was formed, and an enameled wire was obtained.
Next, a resin varnish in which a polyetherimide resin (PEI) (manufactured by Subic Innovative Plastics, trade name: Ultem 1010) is dissolved in N-methyl-2-pyrrolidone (NMP) to form a 20% by mass solution is obtained. The enameled wire is coated using a die having a shape similar to that of the above and passed through a baking furnace with a furnace length of 8 m set at 450 ° C. at a speed of 15 seconds, and this is repeated once. Thus, an adhesive layer having a thickness of 5 μm was formed (the thickness formed in one baking process was 5 μm), and an enameled wire with an adhesive layer having a thickness of 45 μm was obtained.

  The obtained enameled wire with an adhesive layer was a core wire, and the screw of the extruder used 30 mm full flight, L / D = 20, and a compression ratio of 3. The material used was polyether ether ketone (PEEK) (manufactured by Solvay Specialty Polymers, trade name: KetaSpire KT-820, relative dielectric constant 3.1), and the extrusion temperature conditions were as shown in Table 1. C1, C2, and C3 indicate cylinder temperatures in the extruder, and indicate temperatures in three zones in order from the resin charging side. H indicates the temperature of the head portion, and D indicates the temperature of the die portion. At this time, the extrusion temperature of the thermoplastic resin forming the extrusion-coated resin layer was 183 ° C. higher than the glass transition temperature (217 ° C.) of PEI forming the adhesive layer at point D (400 ° C.). After performing PEEK extrusion coating using an extrusion die, a time of 10 seconds was left and water-cooled to form an extrusion-coated resin layer having a thickness of 40 μm on the outer side of the enamel layer. In this way, an insulating wire made of PEEK extrusion-coated enameled wire having a total thickness (the total thickness of the enamel layer and the extrusion-coated resin layer) of 80 μm was obtained.

(Examples 2 to 17 and Comparative Examples 1 to 5, 8 and Reference Examples 1 and 2)
Each insulated wire was obtained in the same manner as in Example 1, except that the resin of the enamel layer, the resin of the adhesive layer, and the type and thickness of the resin of the extrusion coating resin layer were changed as shown in Tables 2 to 5 below. The extrusion temperature conditions were performed according to Table 1. In Tables 2 to 5, the extruded resin coating layer is shown as “extruded coating layer”.
Here, in Tables 2 to 5, polyphenylsulfone resin (PPSU) (manufactured by Solvay Specialty Polymers, trade name: Radel R5800, glass transition temperature 220 ° C.) was used for the adhesive layers of Examples 9 and 10. Further, in Example 13, modified polyetheretherketone resin (modified PEEK) (manufactured by Solvay Specialty Polymers, trade name: AvaSpire AV-650, relative dielectric constant 3.1) was used as the extrusion coating resin layer.

(Extrusion temperature condition)
The extrusion temperature conditions in the examples and comparative examples are shown in Table 1 below.
In Table 1, C1, C2, and C3 indicate three zones in order from the material input side in which temperature control is separately performed in the cylinder portion of the extruder. H indicates the head behind the cylinder of the extruder. D indicates a die at the tip of the head.

(Comparative Examples 6 and 7)
Using the polyamide-imide resin (PAI) used in Example 1 as the resin for the enamel layer and using phenoxy resin as the resin for the adhesive layer, the adhesives having the thicknesses shown in Table 5 below are used. A layered enameled wire was obtained. The extrusion coating resin layer is made of a different resin as shown in Table 5 below. On the adhesive layer side, polyethersulfone resin (PES) (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumika Excel 4800G), opposite to the adhesive layer On the side, the modified polyetheretherketone resin (modified PEEK) or polyphenylene sulfide resin (PPS) used in Example 13 (made by DIC, trade name: FZ-2100, relative dielectric constant 3.4) is extrusion-coated resin. A layer was formed. Unlike Example 1, water cooling after performing extrusion coating using an extrusion die was not performed.

  The following measurements were performed on the insulated wires of Examples 1 to 17, Comparative Examples 1 to 8, and Reference Examples 1 and 2 manufactured as described above.

(Measurement of melting point)
When 10 mg of the extrusion-coated resin layer is heated at a rate of 5 ° C./min using a thermal analyzer “DSC-60” (manufactured by Shimadzu Corporation), it results from melting seen in a region exceeding 250 ° C. The peak temperature of the amount of heat was read and taken as the melting point. When there are a plurality of peak temperatures, the higher peak temperature is taken as the melting point.

(Measurement of dielectric breakdown voltage change ratio)
A straight piece of insulated wire was cut out by 300 mm and heat-treated at 300 ° C. for 168 hours. After the heat treatment, an aluminum foil was wound around the central portion, the coating layer of one end of 300 mm was peeled off, and electricity was applied between the end peeling portion and the aluminum foil portion. The voltage was increased at 500 V / min, and the voltage causing dielectric breakdown was measured.
When this voltage is V ₁ and the pre-heating breakdown voltage is V ₀ , the breakdown voltage change ratio is obtained by the following equation.

Dielectric breakdown voltage change ratio = (V ₁ / V ₀ ) × 100

  In Tables 2 to 5 described later, when the obtained breakdown voltage change ratio is 90% or more and 100% or less, “A”, when 70% or more and less than 90%, “B”, 30% The case of less than 70% was indicated as “C”, and the case of less than 30% was indicated as “D”.

  Next, the following electric wire characteristics were evaluated about the insulated wire of Examples 1-17 and Comparative Examples 1-8. As reference data, the data of Reference Examples 1 and 2 are also shown in Table 5.

(Iron core winding, dielectric breakdown voltage measurement after heating)
The electrical insulation property before and after heating was evaluated as follows. That is, an insulating wire was wound around an iron core having a diameter of 30 mm, heated to 280 ° C. in a thermostatic bath, and held for 30 minutes. If the iron core is inserted into a copper grain while being wound around the iron core after being taken out from the thermostat, the one end wound is connected to the electrode, and a current of one minute can be maintained without causing dielectric breakdown at a voltage of 10 kV. Pass. In Tables 2-5, the pass was shown by "(circle)" and the failure was shown by "x". In addition, the energization of the voltage of 10 kV was not able to be maintained for 1 minute, and the case where the dielectric breakdown occurred was regarded as rejected. When dielectric breakdown occurs, the flexibility of the electric wire becomes poor, and a change such as whitening occurs on the surface of the electric wire, which may cause a crack.

(Adhesive strength with conductor)
First, an electric wire sample in which only the insulating coating layer closest to the conductor of the insulated wire was partially peeled was set on a tensile tester “Autograph AG-X” manufactured by Shimadzu Corporation, and the extrusion coating resin layer was applied at a speed of 4 mm / min. It peeled upwards (180 degreeC peeling).
The case where the tensile load read at that time was 40 g or more and less than 100 g is shown by “◎” in Tables 2 to 5, the case where it was 20 g or more and less than 40 g was shown by “◯”, and the case where it was less than 20 g Indicated by “x”.

(Adhesive strength between coating layers)
First, an electric wire sample from which only the extruded coated resin layer of the insulated wire was partially peeled was set on a tensile tester “Autograph AG-X” manufactured by Shimadzu Corporation, and the extruded coated resin layer was pulled upward at a speed of 4 mm / min. It peeled off (180 degreeC peeling).
The case where the tensile load read at that time was 100 g or more and less than 400 g is shown by “◎” in Tables 2 to 5, the case where it was 40 g or more and less than 100 g was shown by “◯”, and the case where it was less than 40 g Indicated by “x”.

(Comprehensive evaluation)
Comprehensive evaluation includes the ability to maintain excellent heat aging characteristics over a long period of time, and the dielectric breakdown voltage change ratio satisfies 90% or more, and the core winding, the dielectric breakdown voltage after heating, the adhesive strength with the conductor and the coating When the adhesive strength between them is “◯”, the overall evaluation is “◯”, and the overall evaluation in other cases is “×”.
These results are summarized and shown in Tables 2 to 5 below.

As is apparent from Tables 2 to 5, the adhesive layer having a thickness of 2 to 20 μm, the thickness of the enamel baking layer is 60 μm or less, the thickness of the extrusion coating resin layer is 200 μm or less, and the extrusion coating resin When the resin layer has a melting point of 300 ° C. or higher and 370 ° C. or lower and the dielectric breakdown voltage change ratio is 90% or higher, the adhesive strength between the conductor and the coating layer and the adhesive strength between the coating layers, wear resistance, solvent resistance and processing It was found that both of the electrical insulation properties before and after were excellent.
In addition, when the dielectric breakdown voltage change ratio is 90% or more, long-term heat aging characteristics can be satisfied.

  Specifically, the adhesive strength between the coating layers is inferior to Examples 1 to 17 unless only the adhesive layer is provided as in Comparative Examples 1 and 8. Moreover, when there is no enamel layer like the comparative example 2, or when the thickness of the enamel layer is thick like the comparative examples 3 and 4, it is inferior to the adhesive strength with a conductor. On the other hand, as in Comparative Example 5, when the thickness of the extrusion-coated resin layer exceeds 200 μm, the insulation breakdown voltage evaluation after heating with iron core is poor. In Comparative Examples 6 and 7, the adhesive strength between the coating layers is inferior. This is presumably because the adhesive strength between the extrusion-coated resin layers is particularly poor because of the two-layer laminated structure in which the extrusion-coated resin layers are formed of different resins. In addition, from the comparison with Comparative Examples 1 and 8, Reference Examples 1 and 2 have only the extrusion-coated resin layer, or have the enamel baking layer and the adhesive layer, but do not have only the extrusion-coated resin layer. In both cases, the breakdown voltage change ratio is less than 90%, which is insufficient in that the breakdown voltage changes greatly due to heating.

  In addition, it has confirmed that each insulated wire of Examples 1-17 satisfy | fills the above-mentioned abrasion resistance and solvent resistance.

Claims (7)

  An inverter surge-resistant insulated wire having at least one enamel-baked layer on the outer periphery of a conductor having a rectangular cross section and at least one extrusion-coated resin layer on the outside thereof, the enamel-baked layer and the extruded wire An adhesive layer having a thickness of 2 to 20 μm between the coating resin layer and the extruded coating resin layer on the adhesive layer is made of the same resin, and the enamel-baked layer in the cross section of the inverter surge insulation wire The cross-sectional shape of the extrusion-coated resin layer is rectangular, and the enamel-baked layer surrounding the conductor in the cross-sectional view and the rectangular cross-sectional shape formed by the extrusion-coated resin layer are vertically or horizontally to the conductor. The thickness of the enamel baking layer is 60 μm or less and the thickness of the extrusion-coated resin layer is 200 μm or less in both of the two pairs of two sides facing each other. The resin of the enamel baking layer is polyamideimide, the resin of the extrusion-coated resin layer has a melting point of 300 ° C. or higher and 370 ° C. or lower, and the inverter surge insulation wire has a dielectric breakdown voltage after heat treatment at 300 ° C. for 168 hours. Inverter surge-insulated wire, characterized in that is 90% or more compared to before heat treatment.   2. The inverter surge-insulated wire according to claim 1, wherein the extrusion-coated resin layer is a single layer.   The inverter surge-insulated wire according to claim 1 or 2, wherein the adhesive strength between the coating layers of the inverter surge-insulated wire is 100 g or more and less than 400 g.   In the rectangular cross-sectional shape formed by the enamel baking layer surrounding the conductor and the extrusion-coated resin layer surrounding the conductor in a cross-sectional view, at least one pair of two pairs of two sides facing each other in the vertical and horizontal directions The inverter surge insulation wire according to any one of claims 1 to 3, wherein the two sides have a total thickness of the enamel baking layer and the extrusion-coated resin layer of 80 µm or more.   The extrusion coating resin layer is a layer of at least one thermoplastic resin selected from the group consisting of polyetheretherketone, modified polyetheretherketone, thermoplastic polyimide, and aromatic polyamide. The inverter surge-insulated wire according to any one of 1 to 4.   6. The adhesive layer according to claim 1, wherein the adhesive layer is a layer of at least one thermoplastic resin selected from the group consisting of polyetherimide, polyphenylsulfone, and polyethersulfone. The inverter surge resistant wire as described in the item.   An extrusion-coated resin layer is formed on the outer periphery of the enamel baking layer by baking the varnished resin to form the adhesive layer, and then in a molten state at a temperature higher than the glass transition temperature of the resin used for the adhesive layer. A thermoplastic resin to be formed is extruded and brought into contact with the adhesive layer, and the extrusion coating resin layer is formed by thermally fusing the extrusion coating resin to the enamel baking layer through the adhesive layer. Item 7. A method for manufacturing an inverter surge resistant wire according to any one of Items 1 to 6.