WO2016072425A1 - 絶縁ワイヤおよび回転電機 - Google Patents
絶縁ワイヤおよび回転電機 Download PDFInfo
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- WO2016072425A1 WO2016072425A1 PCT/JP2015/081074 JP2015081074W WO2016072425A1 WO 2016072425 A1 WO2016072425 A1 WO 2016072425A1 JP 2015081074 W JP2015081074 W JP 2015081074W WO 2016072425 A1 WO2016072425 A1 WO 2016072425A1
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- insulating layer
- resin
- foamed
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- conductor
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B7/00—Insulated conductors or cables characterised by their form
- H01B7/02—Disposition of insulation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
- C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
- C08J9/14—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent organic
- C08J9/142—Compounds containing oxygen but no halogen atom
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D179/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen, with or without oxygen, or carbon only, not provided for in groups C09D161/00 - C09D177/00
- C09D179/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C09D179/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
- H01B3/303—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups H01B3/38 or H01B3/302
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
- H01B3/303—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups H01B3/38 or H01B3/302
- H01B3/306—Polyimides or polyesterimides
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B7/00—Insulated conductors or cables characterised by their form
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F5/00—Coils
- H01F5/06—Insulation of windings
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
- H02K11/30—Structural association with control circuits or drive circuits
- H02K11/33—Drive circuits, e.g. power electronics
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K3/00—Details of windings
- H02K3/30—Windings characterised by the insulating material
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2201/00—Foams characterised by the foaming process
- C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
- C08J2201/05—Elimination by evaporation or heat degradation of a liquid phase
- C08J2201/0502—Elimination by evaporation or heat degradation of a liquid phase the liquid phase being organic
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2203/00—Foams characterized by the expanding agent
- C08J2203/18—Binary blends of expanding agents
- C08J2203/182—Binary blends of expanding agents of physical blowing agents, e.g. acetone and butane
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2207/00—Foams characterised by their intended use
- C08J2207/06—Electrical wire insulation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
- C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
Definitions
- the present invention relates to an insulated wire and a rotating electrical machine.
- Inverters have come to be attached to many electric devices as an efficient variable speed control device. However, switching is performed at several kHz to several tens of kHz, and a surge voltage is generated for each of these pulses. Such inverter surges cause reflections at impedance discontinuities in the propagation system, for example, at the beginning or end of the connected wiring, and as a result, a voltage twice as high as the inverter output voltage is applied at the maximum.
- the output pulse generated by a high speed switching element such as an insulated gate bipolar transistor (IGBT) has a high voltage steepness, whereby the surge voltage is high even if the connection cable is short, and the voltage attenuation by the connection cable is also As a result, a voltage close to twice the inverter output voltage is generated.
- a high speed switching element such as an insulated gate bipolar transistor (IGBT)
- an insulated wire which is mainly an enameled wire is used as a magnet wire. Therefore, as described above, in the inverter related apparatus, since a voltage close to twice the inverter output voltage is applied, it is required for the insulated wire to minimize the partial discharge deterioration caused by the inverter surge. It is coming.
- partial discharge degradation refers to degradation of molecular chains by collision of charged particles generated by partial discharge (discharge of a part having minute void-like defects etc.) of electrical insulating material, sputtering degradation, thermal melting due to local temperature rise or It refers to the phenomenon that thermal degradation and chemical degradation due to ozone generated by discharge occur in a complicated way. In the electrical insulation material that has been partially discharged and deteriorated, a decrease in its thickness can be seen.
- the insulated wire is required to have excellent flexibility.
- the use frequency of the electric device coil has been expanded to the GHz range.
- the higher the frequency used the higher the dielectric loss of the insulator part of the insulated wire.
- a foam insulation layer made of a plurality of thermoplastic resins is provided to increase the foam density of the foam insulation layer on the central conductor side (see Patent Document 1), or the outside It has been proposed to adjust the foam density of the foamed insulation layer to 30 to 60% (see Patent Document 2).
- JP 2007-35417 A Japanese Patent Application Publication No. 2007-188742
- the present invention solves the above-mentioned subject by using a thermosetting resin excellent in heat resistance, mechanical strength, creep resistance, and solvent resistance for resin which forms a foaming insulating layer in view of the above-mentioned situation. It is an object of the present invention to provide an insulated wire with much higher performance than before. In particular, in the prior art, although high partial discharge inception voltages can be obtained, it has been difficult to achieve extremely excellent flexibility which can withstand increasingly severe winding processing. That is, an object of the present invention is to provide an insulating wire having high partial discharge inception voltage and high dielectric breakdown voltage and excellent in flexibility and wear resistance. Another object of the present invention is to provide a rotating electrical machine using such an insulated wire of excellent performance.
- the insulated wire according to (1) wherein a cell density difference in a thickness direction of the foamed insulating layer is 3% or more.
- thermosetting resin is selected from polyamide imide resin, polyimide resin, polyamide resin, polyether imide resin, polyester imide resin and polyether sulfone resin (1) to (4)
- a rotating electrical machine comprising the insulated wire according to any one of (1) to (5).
- air bubbles means voids having a diameter of 0.1 ⁇ m or more or voids generated by foaming
- the foam layer means an area of 1 ⁇ 1 in the vertical and horizontal directions when the thickness of one layer is 1. It means a layer containing 5 or more air bubbles.
- different layers are not only layers different in resin, but foam layers having bubbles and non-foam layers having no bubbles are different layers even if the resins are the same.
- the same resin varnish is repeatedly applied and baked in a non-foamed layer having no bubbles, and the layer whose thickness is simply adjusted is the same layer.
- the foam layer even if the foam density is different in the thickness direction, if it is composed of the same resin, it is the same layer, and the resin varnish is applied to adjust the thickness or simply change the foam density. And even if the printing is repeated, if at least the resin is the same, it is the same layer.
- the resin in the resin varnish is the same, and the resin varnish in which only the type and amount of the foaming agent for changing the foam density differ is repeatedly applied and baked. In each case, they are all the same layer, ie, one layer.
- it can be judged by analyzing an infrared absorption spectrum or a Raman spectrum whether the resin used is different. Further, whether or not air bubbles are present can be determined by observing (photographing) a cross section in the thickness direction with a scanning electron microscope (SEM) at 300 to 3000 times.
- SEM scanning electron microscope
- the present invention it has become possible to provide an insulated wire which is high in both partial discharge inception voltage and dielectric breakdown voltage and is excellent in flexibility and wear resistance. As a result, it is possible to provide a rotating electrical machine using such excellent performance of the insulated wire.
- FIG.1 (a) is sectional drawing which showed one embodiment of the insulated wire of this invention
- FIG.1 (b) is sectional drawing which showed another embodiment of the insulated wire of this invention
- Fig.2 (a) is sectional drawing which showed further another embodiment of the insulated wire of this invention
- FIG.2 (b) is sectional drawing which showed further another embodiment of the insulated wire of this invention.
- FIG. 3 (a) is a cross-sectional view showing another embodiment of the insulated wire of the present invention
- FIG. 3 (b) is a cross-sectional view showing another embodiment of the insulated wire of the present invention.
- FIG. 4 is a scanning electron micrograph of the cross section of the insulated wire for explaining the method of calculating the bubble density.
- FIG. 4 is a scanning electron micrograph of the cross section of the insulated wire for explaining the method of calculating the bubble density.
- FIG. 5 is a scanning electron micrograph of the cross section of the insulating wire for explaining the method of calculating the cell density, in which the cell density above and below the foam insulating layer is determined.
- FIG. 6 is a schematic view showing the difference in bubble density of each sample in the example.
- the insulated wire (also referred to as an insulated wire) of the present invention has a foamed insulating layer made of a thermosetting resin having at least one layer of air bubbles directly or indirectly directly or indirectly on the outer peripheral surface of the conductor.
- the bubble density is different in the longitudinal direction.
- an inner insulating layer made of a thermosetting resin may be provided between the conductor and the foamed insulating layer made of a thermosetting resin, and a thermoplastic resin may be provided outside the foamed insulating layer made of a thermosetting resin.
- An outer insulating layer made of resin may be provided.
- an outer insulating layer may be provided on the outer side of the foamed insulating layer made of a thermosetting resin, with the inner insulating layer interposed therebetween.
- the inner insulating layer is a layer which is formed on the outer peripheral surface of the conductor and which is formed of a thermosetting resin forming a foamed insulating layer to be described later and which has no bubbles.
- the internal insulating layer is a layer formed of a thermosetting resin forming a foamed insulating layer, which will be described later, inside the foamed insulating layer without bubbles.
- an inner insulating layer and an inner insulating layer are provided as needed.
- the total thickness of the wire coating (the total thickness of all the insulating layers; the total thickness from the conductor to the surface) in a cross section perpendicular to the longitudinal direction of the insulated wire is preferably 20 to 300 ⁇ m, more preferably 50 to 200 ⁇ m.
- an insulating wire having a conductor, a foamed insulating layer made of a thermosetting resin, and an outer insulating layer made of a thermoplastic resin will be described by way of example with reference to the drawings. However, the present invention is not limited to what is described in the drawings.
- One embodiment of the insulating wire according to the present invention comprises a conductor 1 having a circular cross section and a thermosetting resin covering the outer peripheral surface of the conductor 1 And an outer insulating layer 3 made of a thermoplastic resin covering the outer peripheral surface of the foamed insulating layer 2.
- the foamed insulating layer 2 and the outer insulating layer 3 are also circular in cross section.
- Another embodiment of the insulated wire according to the present invention, the cross-sectional view of which is shown in FIG. 1 (b) uses a rectangular cross-section as the conductor 1, and the others are basically shown in FIG. 1 (a). It is similar to the insulated wire.
- the foam insulating layer 2 made of a thermosetting resin and the outer insulating layer 3 made of a thermoplastic resin also have a rectangular cross section.
- FIG. 2 (a) a cross-sectional view of which is shown in FIG. 2 (a) is a conductor which is an inner side of the foamed insulation layer 2 which is made of a thermosetting resin having air bubbles It is the same as the insulated wire shown in FIG. 1A except that the inner insulating layer 25 made of a thermosetting resin is provided on the outer periphery of 1.
- an internal insulating layer 26 is provided which divides the foamed insulating layer 2 into two layers in the thickness direction, and the cross section of the conductor 1 is rectangular. It is the same as the insulated wire shown in FIG.
- the inner insulating layer 25, the foamed insulating layer 2, the internal insulating layer 26, the foamed insulating layer 2 and the outer insulating layer 3 are laminated in this order on the conductor 1.
- the “inner insulating layer” is basically the same as the foamed insulating layer except that it has no bubbles, and the “inner insulating layer” is different from the inner insulating layer except that the positions where it is formed are different. It is basically the same.
- an adhesive layer is formed between the foamed insulating layer 2 made of thermosetting resin having bubbles and the outer insulating layer 3.
- adhesion is made between the foamed insulating layer 2 and the outer insulating layer 3 which are made of a thermosetting resin having cells and whose cell density differs in the thickness direction. It is the same as the insulated wire shown in FIG. 2 (b) except that an internal insulating layer 35 such as a layer is provided instead of the internal insulating layer 26 in FIG. 2 (b).
- the conductor 1 used for this invention what is conventionally used by the insulated wire or the insulated wire can be used, For example, copper, copper alloy, aluminum, aluminum alloy, or those combination etc. are mentioned.
- it is a conductor of low oxygen copper having an oxygen content of 30 ppm or less, more preferably 20 ppm or less of low oxygen copper or oxygen free copper.
- the oxygen content is 30 ppm or less, there is no generation of a void due to the contained oxygen in the welded portion when it is melted by heat for welding the conductor, and the electrical resistance of the welded portion is prevented from being deteriorated. The strength of the welded portion can be maintained.
- the cross-sectional shape of the conductor 1 used in the present invention may be any shape such as circular (round shape), rectangular (flat angle) or hexagonal, but the rectangular conductor 1 has a winding compared with the circular one. Sometimes it is preferable because the space factor for the stator slots is high.
- the size of the rectangular conductor 1 is not particularly limited, but the width (long side) is preferably 1 to 5 mm, more preferably 1.4 to 4.0 mm, and the thickness (short side) is 0.4 to 3. 0 mm is preferable, and 0.5 to 2.5 mm is more preferable.
- the ratio of the width (long side) to the thickness (short side) is preferably 1: 1 to 1: 4.
- curvature radius r is a shape which provided chamfer (curvature radius r) in four corners of a rectangle.
- the curvature radius r is preferably equal to or less than 0.6 mm, and more preferably 0.2 to 0.4 mm.
- the size is not particularly limited, but the diameter is preferably 0.3 to 3.0 mm, and more preferably 0.4 to 2.7 mm.
- the thickness of the foamed insulating layer is not limited, in the present invention, 10 to 200 ⁇ m is preferable. Further, in the present invention, the foam insulating layer may be composed of one layer or a plurality of two or more layers.
- the foamed insulating layer is preferably one that can be applied to a conductor and baked to form an insulating film.
- a thermosetting resin is used as the resin constituting the foamed insulation layer.
- the thermosetting resin those conventionally used can be used.
- resins selected from polyamideimide (PAI), polyimide (PI), polyamide (PA), polyetherimide (PEI), polyesterimide (PEsI) and polyether sulfone (PES) are preferred, among which Polyamideimide (PAI) and polyimide (PI), which are excellent in solvent resistance, are more preferable, and polyamideimide (PAI) is particularly preferable.
- the thermosetting resin to be used may be used individually by 1 type, and may mix and use 2 or more types.
- polyamideimide resin a commercially available product (for example, HI406 (manufactured by Hitachi Chemical Co., Ltd., trade name) or the like may be used, or it may be obtained by direct reaction of tricarboxylic acid anhydride and diisocyanates in a polar solvent by a conventional method. Can be used.
- polyimide for example, U-imide (product name made by Unitika Co., Ltd.), U-varnish (product name made by Ube Industries, Ltd.), HCI series (product name made by Hitachi Chemical Co., Ltd.), Aurum (Mitsui Chemical Co., Ltd. It is possible to use company-made, brand names, etc.
- thermoplastic resin having a melting point of 240 ° C. or more in the case of a crystalline resin, or a thermoplastic resin having a glass transition temperature of 240 ° C. or more in the case of an amorphous resin, for a thermosetting resin forming a foamed insulating layer May be added.
- the thermoplastic resin at this time preferably has a storage elastic modulus at 25 ° C. of 1 GPa or more. By containing a thermoplastic resin, flexibility and elongation properties are improved.
- the glass transition temperature of the thermoplastic resin is preferably 180 ° C. or higher, and more preferably 210 to 350 ° C.
- the addition amount of such a thermoplastic resin is preferably 5 to 50% by mass of the resin solid content.
- the thermoplastic resin that can be used for this purpose is preferably an amorphous resin.
- at least one selected from polyetherimide, polyethersulfone, polyphenylene ether, polyphenylsulfone (PPSU) and polyimide is preferable.
- polyether imide for example, Ultem (manufactured by GE Plastics Co., Ltd., trade name) can be used.
- polyether sulfone for example, Sumika Excel PES (manufactured by Sumitomo Chemical Co., Ltd., trade name), PES (Mitsui Chemical Co., Ltd., trade name), Ultrazone E (manufactured by BASF Japan Ltd., trade name), Radel A (Solvay Advanced Polymers Co., Ltd., brand name) etc.
- PES Mitsubishi Engineering Plastics, Inc., trade name
- Ultrazone E manufactured by BASF Japan Ltd., trade name
- Radel A Solvay Advanced Polymers Co., Ltd., brand name
- polyphenylene ether for example, Zylon (manufactured by Asahi Kasei Chemicals, Inc., trade name), Upiace (manufactured by Mitsubishi Engineering Plastics, Inc., trade name), and the like can be used.
- polyphenyl sulfone for example, Radel R (manufactured by Solvay Advanced Polymers, Inc., trade name) can be used.
- polyimide for example, U-varnish (made by Ube Industries, Ltd., trade name), HCI series (made by Hitachi Chemical, trade name), U imide (made by Unitika, trade name), Aurum (Mitsui Chemical Co., Ltd. It is possible to use company-made, brand names, etc. Polyphenylsulfone and polyetherimide are more preferable in that they are easily soluble in solvents.
- a bubble forming nucleating agent, an antioxidant, an antistatic agent, an ultraviolet light inhibitor, a light stabilizer, a fluorescent light, and the like for the thermosetting resin forming the foamed insulating layer within a range not affecting the characteristics. Even if various additives such as brighteners, pigments, dyes, compatibilizers, lubricants, reinforcing agents, flame retardants, crosslinking agents, crosslinking aids, plasticizers, thickeners, thickeners, and elastomers are blended Good.
- a layer made of a resin containing these additives may be laminated on the obtained insulating wire, or a coating containing these additives may be coated.
- the foaming ratio of the foamed insulating layer is preferably 1.2 or more, and more preferably 1.4 or more.
- the upper limit of the expansion ratio is not limited, it is usually preferably 5.0 times or less.
- the foaming ratio is calculated by ( ⁇ s / ⁇ f), and the density ( ⁇ f) of the resin coated for foaming and the density ( ⁇ s) before foaming are measured by the water substitution method.
- the cell density is different in the thickness direction in order to improve the flexibility of the foamed insulating layer.
- the difference in cell density is the difference in density within the same foamed resin layer, and the cell density can be determined by observing the insulating film of the insulating wire by the following method.
- the insulating film of the insulating wire is cleaved in the thickness direction while being cooled in liquid nitrogen, and a cross section in the thickness direction is photographed with a scanning electron microscope (SEM) at a magnification of 300 to 3000.
- the magnification is adjusted so that the entire thickness of the film fits all on the observation screen. For example, it may be 300 times when the thickness of the whole film is 200 ⁇ m and 3000 times when it is 10 ⁇ m.
- An SEM photograph of the taken cross section is taken into an image analysis software, for example, “WinROOF ver. 7.1” (manufactured by Mitani Corporation). The area ratio can be calculated by this image analysis software. As in the photograph shown in FIG. 4, the thickness on the entire screen is made visible in the vertical direction on the screen.
- the thickness of each distribution is 1 and the area of 1 ⁇ 1 in the vertical and horizontal directions is set as the measurement range.
- the measurement range is set every 5 ⁇ m ⁇ 5 ⁇ m from the conductor side.
- the SEM photograph shown in FIG. 4 corresponds to this case.
- the measurement range is six in total in the longitudinal direction. Image analysis of the measurement range is performed to calculate the area ratio.
- the area ratio is the ratio of voids in the area of the measurement range.
- the area ratio (%) calculated is taken as the cell density (%).
- the cell density difference (%) in the present invention refers to the difference between the maximum cell density (%) and the minimum cell density (%) in the same layer.
- the difference in cell density in the thickness direction of the foamed insulating layer is preferably 3% or more, and particularly preferably 5% or more. If there is a difference in cell density of 3% or more in the thickness direction, it is judged that the cell density has a slope. In the present invention, it has been found that when the cell density has a slope of 3% or more, the flexibility is significantly improved as compared to the case where the cell density has no slope.
- the difference in cell density is desirable for the difference in cell density to differ by at most 90%, with a minimum of 3%, and especially with a maximum of 90%, a minimum of 5%.
- the number of vertical and horizontal pixels arbitrarily set from the above viewpoint is not limited to the range of “middle” and “middle”, and the number of vertical and horizontal pixels arbitrarily set on the conductor side
- the range of the number of vertical and horizontal pixels set on the film surface side not including the range of “lower” and “middle” is classified as “upper”.
- the furnace temperature is adjusted and varnish application and baking are repeated multiple times as shown in the examples. It is possible.
- the average cell diameter of the foamed insulating layer is preferably 10 ⁇ m or less, more preferably 5 ⁇ m or less, still more preferably 3 ⁇ m or less, and particularly preferably 1 ⁇ m or less. If it exceeds 10 ⁇ m, the dielectric breakdown voltage may decrease. By setting the thickness to 10 ⁇ m or less, the dielectric breakdown voltage can be favorably maintained. Furthermore, by setting the thickness to 5 ⁇ m or less and 3 ⁇ m or less, the dielectric breakdown voltage can be held more reliably. Although the lower limit of the average cell diameter is not limited, it is practical and preferable to be 1 nm or more.
- the average cell diameter was obtained by observing the cross section of the foamed insulating layer with a scanning electron microscope (SEM), and randomly selecting a total of 50 bubbles from the range where the foam density was observed, image dimension measurement software (Mitani Corporation stock It is the value which measured in diameter measurement mode using company make WinROOF, calculated these averages.
- the cell diameter can be adjusted by the manufacturing process such as the expansion ratio, the concentration of the resin, the viscosity, the temperature, the amount of the foaming agent added, the temperature of the baking furnace and the like.
- the foamed insulating layer can lower the relative dielectric constant, and can suppress partial discharge and corona discharge generated in the air gap between the lines when a voltage is applied.
- the foamed insulating layer is coated and baked around the conductor with an insulating varnish obtained by mixing a thermosetting resin, two or more types, preferably three or more types, of a specific organic solvent and at least one high boiling point solvent. It can be obtained by The application of the varnish may be performed directly on the conductor or may be performed with another insulating layer (resin layer) interposed therebetween.
- the organic solvent of the varnish used for the foamed insulating layer acts as a solvent for dissolving the thermosetting resin.
- the organic solvent is not particularly limited as long as it does not inhibit the reaction of the thermosetting resin, and, for example, N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide (DMAC), dimethyl sulfoxide, N, N -Amide solvents such as dimethylformamide, urea solvents such as N, N-dimethylethyleneurea, N, N-dimethylpropyleneurea and tetramethylurea, lactone solvents such as ⁇ -butyrolactone and ⁇ -caprolactone, propylene carbonate etc.
- NMP N-methyl-2-pyrrolidone
- DMAC N-dimethylacetamide
- dimethyl sulfoxide N, N -Amide solvents
- urea solvents such as N, N-dimethylethyleneurea, N, N-dimethylpropylene
- ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone
- ethyl acetate n-butyl acetate
- butyl cellosolve acetate buty
- amide solvents and urea solvents are preferred in view of high solubility, high reaction acceleration, etc.
- N-methyl-2 is preferred in that they do not have a hydrogen atom which easily inhibits the crosslinking reaction by heating.
- -Pyrrolidone, N, N-dimethylacetamide, N, N-dimethylethyleneurea, N, N-dimethylpropyleneurea, tetramethylurea are more preferred, and N-methyl-2-pyrrolidone is particularly preferred.
- the boiling point of the organic solvent is preferably 160 ° C. to 250 ° C., more preferably 165 ° C. to 210 ° C.
- the high boiling point solvents which can be used for bubble formation preferably have a boiling point of 180 ° C. to 300 ° C., more preferably 210 ° C. to 260 ° C.
- diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dibutyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol monomethyl ether and the like can be used.
- Triethylene glycol dimethyl ether is more preferable in that the variation in the cell diameter is small.
- dipropylene glycol dimethyl ether diethylene glycol ethyl methyl ether, dipropylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol butyl methyl ether, tripropylene glycol dimethyl ether, diethylene glycol monobutyl ether, ethylene glycol monophenyl ether, tripropylene glycol Ethylene glycol monomethyl ether, triethylene glycol butyl methyl ether, polyethylene glycol dimethyl ether, polyethylene glycol monomethyl ether, propylene glycol monomethyl ether, etc. can be used.
- the high-boiling point solvent may be of one type, but it is preferable to use at least two types in combination in that the effect of generating bubbles in a wide temperature range is obtained.
- Preferred combinations of at least two high-boiling solvents are tetraethylene glycol dimethyl ether and diethylene glycol dibutyl ether, diethylene glycol dibutyl ether and triethylene glycol dimethyl ether, triethylene glycol monomethyl ether and tetraethylene glycol dimethyl ether, triethylene glycol butyl methyl ether and tetraethylene.
- Glycol dimethyl ether more preferably one containing a combination of diethylene glycol dibutyl ether and triethylene glycol dimethyl ether, triethylene glycol monomethyl ether and tetraethylene glycol dimethyl ether.
- the high boiling point solvent for bubble formation is preferably higher in boiling point than the solvent in which the thermosetting resin is dissolved, and when one type is added to the varnish, it is 10 ° C. or more higher than the solvent of the thermosetting resin. preferable.
- the high boiling point solvent plays the role of both a cell nucleating agent and a foaming agent when used alone.
- the one with the highest boiling point acts as a foaming agent
- the high boiling point solvent for bubble formation having an intermediate boiling point acts as a bubble nucleating agent.
- the solvent having the highest boiling point is preferably 20 ° C. or more higher than the specific organic solvent, and more preferably 30 to 60 ° C. higher.
- a high boiling point solvent for bubble formation having an intermediate boiling point may have a boiling point between the boiling point of the solvent acting as a foaming agent and the specific organic solvent, and has a boiling point difference of 10 ° C. or more with the boiling point of the foaming agent. Is preferred.
- a high boiling point solvent for bubble formation having an intermediate boiling point can form uniform bubbles after varnish baking if the solubility of thermosetting is higher than the solvent acting as a foaming agent.
- the use ratio is, for example, 99/1 to 1 in mass ratio with respect to the high boiling point solvent having the highest boiling point to the high boiling point solvent having an intermediate boiling point. It is preferably / 99, and more preferably 10/1 to 1/10 in terms of the ease of formation of bubbles.
- the insulated wire of the present invention may have an inner insulating layer made of a thermosetting resin between a conductor and a foamed insulating layer made of a thermosetting resin.
- the inner insulating layer is not a foamed insulating layer.
- the thickness of the inner insulating layer is preferably 1 to 40 ⁇ m, and more preferably 1 to 25 ⁇ m.
- an outer insulating layer may be formed on the outer periphery of the foamed insulating layer directly or via an inner insulating layer.
- the inventors of the present invention take advantage of the fact that the foam insulation layer is deformed by inclusion of air, and the air gap is filled by providing a layer of thermoplastic resin as an outer insulation layer on the upper layer of the foam insulation layer. It has been found that the present invention is excellent in the ability to suppress the occurrence of partial discharge.
- a thermoplastic resin used for the outer insulating layer in the case of an amorphous resin, a thermoplastic resin having a glass transition temperature of 240 ° C. or higher, or a crystalline resin It is preferable to use a thermoplastic resin having a melting point of 240.degree. C. or more.
- thermoplastic resin excellent in heat resistance and chemical resistance as a material of the outer insulating layer.
- thermoplastic resins such as engineering plastics and super engineering plastics are suitable.
- Polyamide (PA) nylon
- polyacetal (POM) polycarbonate
- PC polyphenylene ether
- PBT polybutylene terephthalate
- PET polyethylene terephthalate
- Other than general purpose engineering plastics such as syndiotactic polystyrene resin (SPS), polyethylene naphthalate (PEN) and ultrahigh molecular weight polyethylene
- PSF syndiotactic polystyrene resin
- PES polyethersulfone
- PPS polyphenylene sulfide
- U Polymer
- Polyamide imide polyether ketone
- PEK polyaryl ether ketone
- Super engineering plastics such as polyetheretherketone (PEEK), polyimide (PI), thermoplastic polyimide resin (TPI), polyamide imide (PAI), liquid crystal polyester, and further, polyethylene terephthalate (PET), polyethylene naphthalate (PEN)
- syndiotactic polystyrene resin SPS
- polyphenylene sulfide PPS
- polyaryletherketone PAEK
- polyetheretherketone PEEK
- thermoplastic polyimide thermoplastic polyimide in terms of heat resistance and stress crack resistance.
- Resin (TPI) can be particularly preferably used.
- the resin used is not limited by the resin name shown above, and it is needless to say that it is possible to use any resin other than the above listed resins, as long as the resin is superior in performance to those resins.
- thermoplastic resin for example, general-purpose materials such as polyamide (PA), polyacetal (POM), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), and ultrahigh molecular weight polyethylene
- PA polyamide
- POM polyacetal
- PBT polybutylene terephthalate
- PET polyethylene terephthalate
- PPS polyphenylene sulfide
- ultrahigh molecular weight polyethylene examples include engineering plastics, polyetheretherketone (PEEK), polyetherketone (PEK), polyaryletherketone (PAEK) (including modified PEEK), and thermoplastic polyimide resin (TPI).
- PEEK polyetheretherketone
- PEK polyetherketone
- PAEK polyaryletherketone
- TPI thermoplastic polyimide resin
- the polymer alloy using the said crystalline resin is mentioned.
- thermoplastic resin for example, polycarbonate (PC), polyphenylene ether, polyarylate, syndiotactic polystyrene resin (SPS), polyamideimide (PAI), polybenzimidazole (PBI), polysulfone (PSF) And polyether sulfone (PES), polyether imide (PEI), polyphenyl sulfone (PPSU), and amorphous thermoplastic polyimide resin.
- PC polycarbonate
- SPS syndiotactic polystyrene resin
- PAI polyamideimide
- PBI polybenzimidazole
- PSF polysulfone
- PES polyether sulfone
- PEI polyether imide
- PPSU polyphenyl sulfone
- thermoplastic resins the thermal properties of a crystalline thermoplastic resin having a melting point (mp) of 240 ° C. or higher, or an amorphous resin having a glass transition temperature (Tg) of 240 ° C. or higher. It is preferred to select a plastic resin.
- thermoplastic thermoplastic resin having a melting point of 240 ° C. or higher thermoplastic polyimide resin (TPI) (mp. 388 ° C.), PPS (mp. 275 ° C.), PEEK (mp. 340 ° C.), polyaryl Ether ketone (PAEK) (mp. 340 ° C.) and the like can be mentioned.
- TPI thermoplastic polyimide resin
- PPS mp. 275 ° C.
- PEEK mp. 340 ° C.
- PAEK polyaryl Ether ketone
- thermoplastic resin of non-crystalline resin having a glass transition temperature of 240 ° C. or higher non-crystalline thermoplastic polyimide resin (Tg. 250 ° C.), polyamideimide (PAI) (Tg. 280-290 ° C.), polyamideimide (PAI) (Tg. 435 ° C.), syndiotactic polystyrene resin (SPS) (Tg. 280 ° C.) and the like.
- the melting point can be measured by observing the melting point at a heating rate of 10 ° C./min using a DSC (differential scanning calorimetry), for example, DSC-60 (trade name) manufactured by Shimadzu Corporation. .
- the glass transition temperature can be measured by observing the glass transition temperature at a heating rate of 10 ° C./min using a sample of 10 mg and a temperature rising rate of 10 ° C./min.
- the outer insulating layer preferably contains a thermoplastic resin of a crystalline thermoplastic resin having a melting point of 240 ° C. or higher, or an amorphous resin having a glass transition temperature of 240 ° C. or higher. If a crystalline thermoplastic resin having a melting point of 270 ° C. or more is contained, the heat resistance is further improved, and the mechanical strength tends to be increased. It is preferable in that the effect of improving performance is obtained.
- the content of the crystalline thermoplastic resin having a melting point of 270 ° C. or more in the outer insulating layer is preferably 10% by mass or more, and particularly preferably 60% by mass or more in the resin component forming the outer insulating layer.
- fusing point is 270 degreeC or more is as the previous art.
- the outer insulating layer is not limited to the thermoplastic resin as described above, and a thermosetting resin may be used.
- the thermoplastic resin contained in the outer insulating layer more preferably has a storage elastic modulus of 1 GPa or more at 25 ° C.
- the storage elastic modulus at 25 ° C. is less than 1 GPa, the thermoplastic resin is highly effective in deforming, but the wear characteristics deteriorate, which causes problems such as having to be in a low load condition when coil forming. .
- the storage elastic modulus of the thermoplastic resin at 25 ° C. is more preferably 2 GPa or more.
- the upper limit value of the storage elastic modulus is not particularly limited, but it is preferably, for example, 6 GPa because there is a problem that the flexibility required for the winding decreases if the storage elastic modulus is too high.
- the storage elastic modulus of the thermoplastic resin forming each insulating layer of the insulating wire is a value measured using a viscoelasticity analyzer (manufactured by Seiko Instruments Inc .: DMS 200 (trade name)). Specifically, using a 0.2 mm-thick test piece made of a thermoplastic resin that forms each insulating layer of the insulating wire, the temperature is raised to 25 ° C. at a temperature rising rate of 2 ° C./min and a frequency of 10 Hz. The measured value of storage elastic modulus in a stabilized state is recorded, and this recorded value is taken as the 25 ° C. storage elastic modulus of the thermoplastic resin.
- thermoplastic resin contained in the outer insulating layer having a storage elastic modulus at 25 ° C. of 1 GPa or more is, for example, PEEK 450 G (trade name, storage elastic modulus at 25 ° C .: 3840 MPa, 300 as trade name PEEK 450K, trade name).
- modified PEEK 345 ° C) or AV-651 (trade name, storage modulus at 25 ° C: 3500MPa, storage modulus at 300 ° C: 130MPa, melting point: 345 ° C), Aurum PL450C of Mitsui Chemical Co., Ltd. as TPI (trade name, 25 ° C) Storage modulus of 1880MPa, storage modulus of 300 ° C: 18.9MP Melting point: 388 ° C.), PPS manufactured by Polyplastics Co., Ltd.
- Fortone 0220A9 (trade name, storage modulus at 25 ° C .: 2800 MPa, storage modulus at 300 ° C .: ⁇ 10 MPa, melting point: 278 ° C) or DIC stock PPS FZ-2100 (trade name, 25 ° C. storage elastic modulus: 1600 MPa, 300 ° C. storage elastic modulus: ⁇ 10 MPa, melting point: 275 ° C.) manufactured by Idemitsu Kosan Co., Ltd.
- thermoplastic resin of the outer insulating layer is particularly preferably PEEK or modified PEEK.
- the outer insulating layer is substantially free of a partial discharge resistant material.
- the partial discharge resistant substance is an insulating material that is not susceptible to partial discharge deterioration, and refers to a substance that has the function of improving the charge life characteristics by dispersing it in the insulating film of the electric wire.
- the partial discharge resistant substance include oxides (oxides of metal or nonmetal elements), nitrides, glass, mica, etc.
- the partial discharge resistant substance 3 is silica, titanium dioxide, Fine particles of alumina, barium titanate, zinc oxide, gallium nitride and the like can be mentioned.
- substantially free of the partial discharge resistant material means that the partial discharge resistant material is not positively contained in the outer insulating layer, and in addition to not being completely contained, It also includes the case where the content is such that the object of the present invention is not impaired.
- content of the grade which does not impair the objective of this invention content of 30 mass parts or less is mentioned with respect to 100 mass parts of resin components which form an outer side insulating layer.
- Various additives such as lubricants, reinforcing agents, flame retardants, crosslinking agents, crosslinking aids, plasticizers, thickeners, viscosity reducing agents, and elastomers may be blended.
- the thickness of the outer insulating layer is not limited, but 20 to 150 ⁇ m is practical and preferred. Also, the ratio of the thickness of the foamed insulation layer to the thickness of the outer insulation layer should be appropriate. That is, as the foamed insulating layer is thicker, the relative dielectric constant is lowered, and the partial discharge inception voltage can be increased. If it is desired to increase mechanical properties such as strength and flexibility, the outer insulating layer may be designed to be thick. It has been found that when the ratio of the thickness of the foamed insulating layer to the thickness of the outer insulating layer is 5/95 to 95/5, the characteristics of strength and firing voltage are exhibited. In particular, when mechanical properties are required, 5/95 to 60/40 is preferable.
- no bubbles means to the extent that the object of the present invention is not impaired in addition to the completely bubble free state, that is, in the case of voids having a diameter of less than 0.1 .mu.m, no bubbles. Is included. The presence or absence of a bubble diameter less than 0.1 ⁇ m in diameter can be confirmed by observing the cross section of the foamed insulating layer with a scanning electron microscope (SEM).
- the outer insulating layer can be formed by molding a thermoplastic resin composition containing a thermoplastic resin around the foamed insulating layer by a molding method such as extrusion molding.
- the molding of the thermoplastic resin composition can also include another resin layer, ie, an inner insulating layer, directly or in the periphery of the foamed insulating layer.
- the resin forming the inner insulating layer is preferably a thermoplastic resin, and the thermoplastic resin mentioned in the outer insulating layer may be mentioned.
- the thermoplastic resin composition for forming the internal insulating layer affects the properties of, for example, various additives added to the varnish forming the foamed insulating layer, the organic solvent, etc. in addition to the thermoplastic resin. You may contain, as long as it does not exist.
- the inner insulating layer is preferably, for example, an adhesive layer for improving the adhesion between the foamed insulating layer and the outer insulating layer.
- the adhesive layer is preferably formed between the foamed insulating layer and the outer insulating layer, as described above, with an amorphous thermoplastic resin similar to the amorphous thermoplastic resin forming the outer insulating layer.
- the adhesion layer and the outer insulating layer may be formed of the same non-crystalline thermoplastic resin or may be formed of different non-crystalline thermoplastic resins.
- the inner insulating layer, preferably the adhesion layer is formed as a thin film of, for example, less than 40 ⁇ m (preferably, 1 ⁇ m or more and less than 25 ⁇ m).
- the adhesive layer and the outer insulating layer are mixed to form an insulated wire, it may not be possible to accurately measure the film thickness.
- the insulated wire of the present invention can be manufactured by forming a foamed insulating layer on the outer peripheral surface of a conductor and then forming an outer insulating layer.
- a varnish for forming a foamed insulating layer is applied directly or indirectly to the outer peripheral surface of the conductor directly or indirectly, that is, optionally via an inner insulating layer, etc. and foamed in the process of baking to form a foamed insulating layer
- It can manufacture by implementing the process and the process of extrusion-molding the thermoplastic resin composition which forms an outer side insulating layer in the outer peripheral surface of a foaming insulating layer, and forming an outer side insulating layer.
- the inner insulating layer or the inner insulating layer is coated with a varnish that forms the inner insulating layer or the inner insulating layer, and the inner insulating layer is baked, whereby the inner insulating layer is formed by extruding the resin composition, solvent evaporation, etc.
- a coating obtained by dissolving an amorphous thermoplastic resin similar to the amorphous thermoplastic resin forming the outer insulating layer on a foamed insulating layer is applied to evaporate the solvent. It can be formed by
- the insulated wire of the present invention can be used in fields requiring voltage resistance and heat resistance such as various electric devices (also referred to as electronic devices).
- the insulated wire of the present invention is used for a motor, a transformer, etc., and can constitute a high-performance electric device.
- it is suitably used as a winding for a drive motor of an HV (hybrid car) or an EV (electric car).
- HV hybrid car
- EV electric car
- the insulated wire of the present invention is used for a motor coil, it is also referred to as an insulated wire for a motor coil.
- % indicating the composition means mass%.
- the insulated wires of the example and the comparative example were produced as follows on the basis of the insulated wire shown in FIG. 2 (a).
- Example 1 An insulated wire shown in FIG. 2A was manufactured as follows except that the outer insulating layer 3 was not provided.
- a foamed polyamideimide varnish used to form the foamed insulating layer 2 was produced as follows. In a 2L separable flask, 1000 g of HI-406 series [32% by mass resin component N-methylpyrrolidone (NMP) solution, boiling point 202 ° C. of NMP] (trade name, manufactured by Hitachi Chemical Co., Ltd.) is placed.
- NMP N-methylpyrrolidone
- the polyamide-imide varnish for forming the inner insulating layer used to form the conductor-side insulating layer which is the inner insulating layer 25 is HI-406 series (NMP solution of 32 mass% resin component) (trade name, manufactured by Hitachi Chemical Co., Ltd.) Was used. NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution. Each varnish was applied by dip coating, and the amount of application was adjusted by a die.
- the prepared polyamideimide varnish for forming an inner insulating layer was applied to a 1.0 mm ⁇ copper conductor 1 and baked at a furnace temperature of 500 ° C. to form an inner insulating layer 25 having a thickness of 5 ⁇ m.
- the foamed polyamideimide varnish prepared above is applied onto the inner insulating layer 25 and baked at a furnace temperature of 580 ° C. in the first half and at a furnace temperature of 420 ° C. in the second half to form a foamed insulation layer 2 having a thickness of 80 ⁇ m. did.
- the insulated wire in which the inner side insulating layer 25 and the foaming insulating layer 2 were formed was produced.
- Example 2 Only the foamed insulating layer 2 with a thickness of 80 ⁇ m was provided on the 1.0 mm ⁇ copper conductor 1 without providing the inner insulating layer 25 of Example 1.
- a foamed polyimide varnish used to form the foamed insulation layer 2 was produced as follows.
- the formed insulated wire was produced.
- the portion baked at a furnace temperature of 540 ° C. in the “first half” corresponds to a portion with a cell density of 50%
- the portion baked at a furnace temperature of 520 ° C. in the “second half” corresponds to a portion with a cell density of 45%.
- the insulated wire in which the foaming insulation layer 2 was formed was produced.
- Example 3 As in Example 1, the inner insulating layer 25 and the foamed insulating layer 2 were provided on the conductor 1.
- a foamed polyimide varnish used to form the foamed insulation layer 2 was produced as follows. In a 2 L separable flask, 1000 g of U-imide (resin component 25 mass% in NMP solution) (trade name, manufactured by UNITIKA CO., LTD.) Is placed, 75 g NMP (boiling point 202 ° C.), 150 g DMAC (boiling point 165 ° C.) and tetraethylene Obtained by adding 200 g of glycol dimethyl ether (boiling point 275 ° C.).
- the polyimide varnish for inner-insulation layer formation used to form the conductor side insulation layer which is the inner-insulation layer 25 used U imide (NMP solution of 25 mass% of resin components) (brand name, product made by Unitika, Inc.) . NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution. Each varnish was applied by dip coating, and the amount of application was adjusted by a die. Specifically, on the same copper conductor 1 as in Example 1, the inner insulating layer forming polyimide varnish was applied and baked at a furnace temperature of 500 ° C. to form an inner insulating layer 25 having a thickness of 5 ⁇ m.
- the foamed polyimide varnish prepared above was coated on the inner insulating layer 25 and baked at a furnace temperature of 440 ° C. in the first half and at a furnace temperature of 460 ° C. in the second half to form a foamed insulation layer 2 with a thickness of 50 ⁇ m.
- the portion baked at a furnace temperature of 440 ° C. in the “first half” corresponds to a portion with a cell density of 20%
- the portion baked at a furnace temperature of 460 ° C. in the “second half” corresponds to a portion with a cell density of 23%.
- Example 4 As in Example 1, the inner insulating layer 25 and the foamed insulating layer a were provided on the conductor 1, and further, the foamed insulating layer b different from the foamed insulating layer a was provided on the foamed insulating layer a.
- a foamed polyamideimide varnish used to form the foamed insulating layer a was produced as follows. In a 2L separable flask, 1000 g of HI-406 series [32% by mass resin component N-methylpyrrolidone (NMP) solution, boiling point 202 ° C. of NMP] (trade name, manufactured by Hitachi Chemical Co., Ltd.) is placed.
- NMP N-methylpyrrolidone
- the polyamide-imide varnish for forming the inner insulating layer used to form the conductor-side insulating layer which is the inner insulating layer 25 is HI-406 series (NMP solution of 32 mass% resin component) (trade name, manufactured by Hitachi Chemical Co., Ltd.) Was used. NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution. Each varnish was applied by dip coating, and the amount of application was adjusted by a die. The prepared polyamideimide varnish for inner insulating layer formation was applied to the same copper conductor 1 as in Example 1 and baked at a furnace temperature of 500 ° C. to form an inner insulating layer 25 with a thickness of 3 ⁇ m.
- the foamed polyamideimide varnish for forming the foamed insulating layer a prepared above is applied on the inner insulating layer 25 and baked at a furnace temperature of 560 ° C. in the first half and at a furnace temperature of 440 ° C. in the second half.
- a foamed insulation layer a was formed.
- the portion baked at a furnace temperature of 560 ° C. in the “first half” corresponds to a portion having a cell density of 60%
- the portion baked at a furnace temperature of 440 ° C. in the “second half” corresponds to a portion having a cell density of 20%.
- the foamed polyimide varnish for forming the foamed insulation layer b adjusted above is applied onto the foamed insulation layer a, and the former is baked at a furnace temperature of 560 ° C. and the latter half at a furnace temperature of 520 ° C.
- An insulating layer b was formed.
- the portion baked at a furnace temperature of 560 ° C. in the “first half” corresponds to a portion with a cell density of 55%
- the portion baked at a furnace temperature of 520 ° C. in the “second half” corresponds to a portion with a cell density of 45%.
- Example 5 As in Example 1, the inner insulating layer 25 and the foamed insulating layer 2 were provided on the conductor 1.
- a foamed polyamideimide varnish used to form the foamed insulating layer 2 was produced as follows. In a 2L separable flask, 1000 g of HI-406 series [32% by mass resin component N-methylpyrrolidone (NMP) solution, boiling point 202 ° C. of NMP] (trade name, manufactured by Hitachi Chemical Co., Ltd.) is placed.
- NMP N-methylpyrrolidone
- the polyamide-imide varnish for forming the inner insulating layer used to form the conductor-side insulating layer which is the inner insulating layer 25 is HI-406 series (NMP solution of 32 mass% resin component) (trade name, manufactured by Hitachi Chemical Co., Ltd.) Was used. NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution. Each varnish was applied by dip coating, and the amount of application was adjusted by a die.
- the same polyamide-imide varnish for forming an inner insulating layer prepared on the same copper conductor 1 as in Example 1 was applied and baked at a furnace temperature of 500 ° C. to form an inner insulating layer 25 having a thickness of 5 ⁇ m.
- the foamed polyamideimide varnish prepared above is coated on the inner insulating layer 25 and baked at a furnace temperature of 600 ° C. in the first half, 500 ° C. in the furnace temperature, and 400 ° C. in the second half.
- a foamed insulation layer 2 was formed.
- the insulated wire in which the inner side insulating layer 25 and the foaming insulating layer 2 were formed was produced.
- Example 6 As in Example 1, the inner insulating layer 25 and the foamed insulating layer 2 were provided on the conductor 1, and the outer insulating layer 3 was further provided on the foamed insulating layer 2.
- a foamed polyamideimide varnish used to form the foamed insulating layer 2 was produced as follows. In a 2L separable flask, 1000 g of HI-406 series [32% by mass resin component N-methylpyrrolidone (NMP) solution, boiling point 202 ° C. of NMP] (trade name, manufactured by Hitachi Chemical Co., Ltd.) is placed.
- NMP N-methylpyrrolidone
- the polyamide-imide varnish for forming the inner insulating layer used to form the conductor-side insulating layer which is the inner insulating layer 25 is HI-406 series (NMP solution of 32 mass% resin component) (trade name, manufactured by Hitachi Chemical Co., Ltd.) Was used. NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution. Each varnish was applied by dip coating, and the amount of application was adjusted by a die.
- the same polyamide-imide varnish for forming an inner insulating layer prepared on the same copper conductor 1 as in Example 1 was applied and baked at a furnace temperature of 500 ° C. to form an inner insulating layer 25 having a thickness of 4 ⁇ m.
- the foamed polyamideimide varnish prepared above is coated on the inner insulating layer 25 and baked at a furnace temperature of 600 ° C. in the first half of the furnace temperature, 440 ° C. in the middle of the furnace and 600 ° C. in the second half.
- a 40 ⁇ m foam insulation layer 2 was formed.
- “middle” corresponds to the portion with a cell density of 20% at a furnace temperature of 440 ° C.
- the portion baked at a furnace temperature of 600 ° C. in the “second half” corresponds to a portion having a cell density of 70%.
- the resin to be extrusion coated on the outside of the foamed insulating layer 2 is polyetheretherketone (PEEK) (manufactured by Solvay Specialty Polymers Co., Ltd., trade name: KetaSpire KT-880, relative permittivity of 25 ° C. 3.2, 200
- PEEK polyetheretherketone
- the outer insulating layer 3 which is an extrusion-coated resin layer was formed using a dielectric constant of 4.5 ° C.).
- the extrusion temperature conditions were set to C1: 300 ° C., C2: 370 ° C., C3: 380 ° C., H: 390 ° C., D: 390 ° C.
- C1, C2, and C3 are temperatures of cylinders in the extruder, and indicate temperatures of three zones in order from the resin input side.
- H indicates the temperature of the head
- D indicates the temperature of the die.
- the above resin is extrusion-coated using an extrusion die, and then the outer insulating layer 3 which is an extrusion-coated resin layer with a thickness of 30 ⁇ m is formed by cooling with water for 10 seconds to form an inner insulating layer 25, foam An insulated wire having the insulating layer 2 and the outer insulating layer 3 was produced.
- Example 7 As in Example 1, the inner insulating layer 25 and the foamed insulating layer 2 were provided on the conductor 1.
- a foamed polyimide varnish used to form the foamed insulation layer 2 was produced as follows. In a 2 L separable flask, 1000 g of U-imide (resin component 25 mass% in NMP solution) (trade name, manufactured by UNITIKA CO., LTD.) Is added, 75 g of NMP (boiling point 202 ° C.) as bubble forming agent, DMAC (boiling point 165 ° C.) Obtained by adding 150 g and 200 g of tetraethylene glycol dimethyl ether (boiling point 275 ° C.).
- the polyamide-imide varnish for forming the inner insulating layer used to form the conductor-side insulating layer which is the inner insulating layer 25 is HI-406 series (NMP solution of 32 mass% resin component) (trade name, manufactured by Hitachi Chemical Co., Ltd.) Was used. NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution. Each varnish was applied by dip coating, and the amount of application was adjusted by a die. The prepared polyamideimide varnish for forming an inner insulating layer was applied to the same copper conductor 1 as in Example 1, and baked at a furnace temperature of 500 ° C. to form an inner insulating layer 25 having a thickness of 5 ⁇ m.
- the foamed polyimide varnish adjusted above is applied on the inner insulating layer 25 and baked at a furnace temperature of 540 ° C. in the first half and at a furnace temperature of 440 ° C. in the second half to form a 30 ⁇ m thick foamed insulation layer 2 did.
- the portion baked at a furnace temperature of 540 ° C. in the “first half” corresponds to a portion with a cell density of 50%
- the portion baked at a furnace temperature of 440 ° C. in the “second half” corresponds to a portion with a cell density of 35%.
- Example 8 As in Example 1, the inner insulating layer 25 and the foamed insulating layer 2 were provided on the conductor 1, and the outer insulating layer 3 was further provided on the foamed insulating layer 2.
- a foamed polyimide varnish used to form the foamed insulation layer 2 was produced as follows.
- the polyamide-imide varnish for forming the inner insulating layer used to form the conductor-side insulating layer which is the inner insulating layer 25 is HI-406 series (NMP solution of 32 mass% resin component) (trade name, manufactured by Hitachi Chemical Co., Ltd.) Was used. NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution. Each varnish was applied by dip coating, and the amount of application was adjusted by a die. The prepared polyamideimide varnish for forming an inner insulating layer was applied to the same copper conductor 1 as in Example 1, and baked at a furnace temperature of 500 ° C. to form an inner insulating layer 25 having a thickness of 5 ⁇ m.
- the foamed polyimide varnish adjusted above is applied on the inner insulating layer 25 and baked at a furnace temperature of 420 ° C. in the first half and 560 ° C. in the second half to form a foamed insulation layer 2 having a thickness of 8 ⁇ m. did.
- the portion baked at a furnace temperature of 420 ° C. in the “first half” corresponds to the portion with a bubble density of 15%
- the portion baked at a furnace temperature of 560 ° C. in the “second half” corresponds to a portion with a cell density of 55%.
- the polyimide varnish for forming the outer insulating layer used to form the outer insulating layer on the outside of the foamed insulating layer 2 is U-imide (NMP solution of 25 mass% resin component) (trade name, manufactured by UNITICA CORPORATION) Using. NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution. This was applied onto the foamed insulating layer 2 by dip coating, and baked at a furnace temperature of 500 ° C. to form an outer insulating layer 3 with a thickness of 25 ⁇ m. Thus, an insulated wire having the inner insulating layer 25, the foamed insulating layer 2 and the outer insulating layer 3 was produced.
- thermosetting resin On the conductor 1, an inner insulating layer 25 and an insulating layer made of an ordinary thermosetting resin other than a foamed insulating layer were provided.
- a polyamideimide varnish used to form an insulating layer made of a thermosetting resin was produced as follows. In a 2L separable flask, 1000 g of HI-406 series (32% by mass resin component, NMP solution, boiling point 202 ° C of NMP) (trade name, manufactured by Hitachi Chemical Co., Ltd.) (trade name, manufactured by Hitachi Chemical Co., Ltd.) is used. It was used as a 30% by mass resin solution.
- U-imide NMP solution with 25% by mass of resin component
- U-imide (trade name, manufactured by UNITICA CORPORATION) was used as the polyimide for forming the inner insulating layer used to form the conductor-side insulating layer which is the inner insulating layer 25.
- NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution.
- Each varnish was applied by dip coating, and the amount of application was adjusted by a die.
- a polyamideimide varnish for forming an inner insulating layer prepared on the same copper conductor 1 as in Example 1 was applied and baked at a furnace temperature of 500 ° C. to form an inner insulating layer 25 having a thickness of 3 ⁇ m. .
- the polyamideimide varnish prepared above was applied onto the inner insulating layer 25 and baked at a furnace temperature of 500 ° C. to form an insulating layer made of a thermosetting resin having a thickness of 30 ⁇ m.
- an insulated wire having the inner insulating layer 25 and a normal insulating layer which is not a foamed insulating layer was produced.
- a foamed polyimide varnish used to form the foamed insulation layer 2 was produced as follows. In a 2 L separable flask, 1000 g of U-imide (resin component 25 mass% in NMP solution) (trade name, manufactured by UNITIKA CO., LTD.) Is placed, 75 g NMP (boiling point 202 ° C.), 150 g DMAC (boiling point 165 ° C.) and tetraethylene Obtained by adding 200 g of glycol dimethyl ether (boiling point 275 ° C.).
- the polyimide varnish for inner-insulation layer formation used to form the conductor side insulation layer which is the inner-insulation layer 25 used U imide (NMP solution of 25 mass% of resin components) (brand name, product made by Unitika, Inc.) . NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution. Each varnish was applied by dip coating, and the amount of application was adjusted by a die. Specifically, on the same copper conductor 1 as in Example 1, the inner insulating layer forming polyimide varnish was applied and baked at a furnace temperature of 500 ° C. to form an inner insulating layer 25 with a thickness of 3 ⁇ m.
- the foamed polyimide varnish prepared above was applied onto the inner insulating layer 25 and baked at a furnace temperature of 600 ° C. to form a foamed insulating layer 2 having a cell density of 70% and a thickness of 50 ⁇ m.
- the insulated wire in which the inner side insulating layer 25 and the foaming insulating layer 2 were formed was produced.
- Example 3 As in Example 1, the inner insulating layer 25 and the foamed insulating layer 2 were provided on the conductor 1.
- a foamed polyamideimide varnish used to form the foamed insulating layer 2 was produced as follows. In a 2L separable flask, 1000 g of HI-406 series [32% by mass resin component N-methylpyrrolidone (NMP) solution, boiling point 202 ° C. of NMP] (trade name, manufactured by Hitachi Chemical Co., Ltd.) is placed.
- NMP N-methylpyrrolidone
- the polyamide-imide varnish for forming the inner insulating layer used to form the conductor-side insulating layer which is the inner insulating layer 25 is HI-406 series (NMP solution of 32 mass% resin component) (trade name, manufactured by Hitachi Chemical Co., Ltd.) Was used. NMP was used as a solvent for 1000 g of this resin and used as a 30% by mass resin solution. Each varnish was applied by dip coating, and the amount of application was adjusted by a die.
- the prepared polyamideimide varnish for forming an inner insulating layer was applied to the same copper conductor 1 as in Example 1, and baked at a furnace temperature of 500 ° C. to form an inner insulating layer 25 having a thickness of 5 ⁇ m. Then, the foamed polyimide varnish prepared above was applied onto the inner insulating layer 25 and baked at a furnace temperature of 580 ° C. to form a foamed insulating layer 2 having a cell density of 65% and a thickness of 25 ⁇ m. Thus, the insulated wire in which the inner side insulating layer 25 and the foaming insulating layer 2 were formed was produced.
- each insulating layer of each obtained insulating wire The thickness, cell density, and average cell diameter of each insulating layer of each obtained insulating wire are measured, and the evaluation of partial discharge inception voltage, flexibility, one-way wearability, and breakdown voltage is further performed as follows. went.
- each layer in Examples and Comparative Examples the thickness of each insulating layer including the foamed insulating layer, and the average cell diameter in the foamed insulating layer are measured by a scanning electron microscope (SEM) image of the cross section in the thickness direction of the insulating wire And calculated.
- the average cell diameter in the foamed insulating layer is 50 cells at random in the above scanning electron microscope (SEM) image, and is averaged in the diameter measurement mode using an image dimension measurement software (WinROOF manufactured by Mitani Corporation). The bubble diameter was calculated, and the obtained value was taken as the bubble diameter.
- a test piece is prepared by twisting each of the insulated wires manufactured above into two twisted wires for each insulated wire, and an alternating current voltage of 50 Hz sine wave is applied between the two conductors to continuously boost the voltage.
- the voltage (effective value) was measured when the discharge charge amount was 10 pC while the pressure was reduced.
- the measurement temperature was normal temperature.
- a partial discharge tester manufactured by Kikusui Electronics, KPD 2050 was used to measure the partial discharge inception voltage. If the partial discharge inception voltage is 850 V or more, partial discharge hardly occurs and partial deterioration of the insulating wire can be prevented. For this reason, the obtained partial discharge inception voltage was evaluated by the following rank.
- Evaluation rank A Partial discharge inception voltage is 900V or more
- B Partial discharge inception voltage is 850V or more and less than 900V
- C Partial discharge inception voltage is 500V or more and less than 850V
- D Partial discharge inception voltage is less than 500V
- the one-way wear test was performed according to JIS C 3216.
- the test apparatus used NEMA scrape tester (made by Toyo Seiki Seisaku-sho, Ltd.). This test is such that a continuously increasing force is applied to the needle for a straight specimen, which rubs against the surface of the specimen. The force at which conduction occurred between the needle and the conductor was taken as the destructive force. The obtained result was evaluated by the following rank.
- Evaluation rank A Destructive force is 2500 g or more
- B Destructive force is 1500 g or more and less than 2500 g
- C Destructive force is 1000 g or more and less than 1500 g
- D Destructive force is less than 1000 g
- Evaluation rank A Breakdown voltage is 10 kV or more
- B Breakdown voltage is 8 kV or more and less than 10 kV
- C Breakdown voltage is 5 kV or more and less than 8 kV
- D Breakdown voltage is less than 5 kV
- C is the level which all should achieve at least in the above-mentioned each evaluation item, and is an evaluation rank of B or more.
- the insulated wires of Examples 1 to 8 all have a partial discharge inception voltage of 900 V or more (evaluation rank A), and flexibility also has an evaluation rank of A, and It is excellent in direction abrasion resistance and high in breakdown voltage as high as 5 kV. As a result, it was possible to simultaneously achieve high partial discharge inception voltage and excellent flexibility, which were initially predicted to be difficult to achieve simultaneously. On the other hand, in the comparative example 1 which does not have a foaming insulation layer, the partial discharge inception voltage was low.
- Comparative Examples 2 and 3 in which there is no difference in the foam density in the thickness direction of the foam insulation layer and the uniform foam density, the partial discharge inception voltage is high, but the flexibility is the insulating wire of the present invention
- the rank was lower than Examples 1 to 8).
- the dielectric breakdown voltage was low, and in Comparative Examples 2 and 3, both of the dielectric breakdown voltage and the destructive force in one-way friction were low. That is, in all of Comparative Examples 1 to 3, the rank A was one and the rank C was two, which was inferior overall.
- the insulated wire of the present invention can be used in fields requiring voltage resistance and heat resistance, such as automobiles and various electric / electronic devices.
- the insulated wire of the present invention can be used for a motor, a transformer or the like to provide a high performance electric / electronic device.
- a rotating electrical machine such as a winding for a drive motor of an HV (hybrid car) or an EV (electric car).
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Abstract
Description
すなわち、本発明は、部分放電開始電圧および絶縁破壊電圧がともに高く、可とう性と耐摩耗性に優れた絶縁ワイヤを提供することを課題とする。さらにこのような優れた性能の絶縁ワイヤを用いた回転電機を提供することを課題とする。
(1)導体の外周面上に直接または間接的に少なくとも1層の気泡を有する熱硬化性樹脂からなる発泡絶縁層を有し、該発泡絶縁層が厚さ方向において気泡密度が異なることを特徴とする絶縁ワイヤ。
(2)前記発泡絶縁層の厚さ方向における気泡密度差が、3%以上であることを特徴とする(1)に記載の絶縁ワイヤ。
(3)前記発泡絶縁層における平均気泡径が、10μm以下であることを特徴とする(1)または(2)に記載の絶縁ワイヤ。
(4)前記発泡絶縁層の厚さが、10~200μmであることを特徴とする(1)~(3)のいずれか1項に記載の絶縁ワイヤ。
(5)前記熱硬化性樹脂が、ポリアミドイミド樹脂、ポリイミド樹脂、ポリアミド樹脂、ポリエーテルイミド樹脂、ポリエステルイミド樹脂およびポリエーテルサルフォン樹脂から選択されることを特徴とする(1)~(4)のいずれか1項に記載の絶縁ワイヤ。
(6)前記(1)~(5)のいずれか1項に記載の絶縁ワイヤを用いてなることを特徴とする回転電機。
ここで、本発明において、異なった層とは、樹脂が異なる層だけでなく、樹脂が同一であっても、気泡を有する発泡層と気泡を有しない無発泡層はそれぞれ異なった層である。
また、熱硬化性樹脂を使用する場合、気泡を有さない無発泡層において、同一樹脂ワニスを塗布および焼き付けを繰り返して、単に厚みを調節した層は同一層である。
一方、発泡層の場合、厚さ方向に発泡密度が異なっても同一樹脂で構成されていれば、同一層であり、厚みを調節したり、単に発泡密度を変化させるために、樹脂ワニスを塗布および焼き付けを繰り返したとしても、少なくとも樹脂が同一であれば、同一層である。例えば、同一樹脂ワニスで、塗布後、焼き付け条件を変更した場合、樹脂ワニス中の樹脂が同一で、発泡密度を変更するための発泡剤の種類や量のみ異なる樹脂ワニスで、塗布および焼き付けを繰り返した場合は、いずれも同一層、すなわち、1層である。
なお、使用されている樹脂が異なっているかどうかは赤外吸収スペクトルまたはラマンスペクトルを分析することで判断できる。また、気泡を有するかどうかは、厚み方向での断面を走査電子顕微鏡(SEM)により300~3000倍で観測(撮影)することで判断できる。
<<絶縁ワイヤ>>
本発明の絶縁ワイヤ(絶縁電線とも称す)は、導体の外周面上に直接または間接的に少なくとも1層の気泡を有する熱硬化性樹脂からなる発泡絶縁層を有し、該発泡絶縁層が厚さ方向において気泡密度が異なる。
なお、内側絶縁層は、導体の外周面に形成され、後述する発泡絶縁層を形成する熱硬化性樹脂で気泡をもたない状態に形成される層である。また、内部絶縁層は、発泡絶縁層の内部に、後述する発泡絶縁層を形成する熱硬化性樹脂で気泡をもたない状態に形成される層である。本発明では、必要に応じて、内側絶縁層や内部絶縁層が設けられる。
絶縁ワイヤの長手方向と垂直な断面における電線皮膜の総厚み(全ての絶縁層の厚みの合計;導体から表面までの合計厚さ)は20~300μmが好ましく、50~200μmがより好ましい。
ただし、本発明は、図面に記載のものに限定されるものではない。
図1(b)に断面図を示した本発明の絶縁ワイヤの別の実施態様は、導体1として断面が矩形のものを用いたもので、それ以外は基本的に図1(a)に示す絶縁ワイヤと同様である。この実施態様は、導体1の断面が矩形であるので、熱硬化性樹脂からなる発泡絶縁層2および熱可塑性樹脂からなる外側絶縁層3も断面が矩形である。
図2(b)に示した本発明の絶縁ワイヤのさらにまた別の実施態様では、発泡絶縁層2を厚さ方向に2つの層に分割する内部絶縁層26を設け、導体1の断面が矩形のものを用いた以外は図2(a)に示す絶縁ワイヤと同様である。すなわち、この実施態様では、導体1上に、内側絶縁層25、発泡絶縁層2、内部絶縁層26、発泡絶縁層2および外側絶縁層3がこの順で積層形成されている。
本発明において、「内側絶縁層」は、気泡を有していないこと以外は発泡絶縁層と基本的に同様であり、「内部絶縁層」は形成される位置が異なること以外は内側絶縁層と基本的に同様である。
図3(b)に示した本発明の絶縁ワイヤの別の実施態様では、気泡を有する熱硬化性樹脂からなり厚み方向に気泡密度が異なる発泡絶縁層2と外側絶縁層3との間に密着層のような内部絶縁層35を、図2(b)の内部絶縁層26の代わりに設けた以外は図2(b)に示す絶縁ワイヤと同様である。
本発明に用いる導体1としては、従来、絶縁電線もしくは絶縁ワイヤで用いられているものを使用することができ、例えば、銅、銅合金、アルミニウム、アルミニウム合金またはそれらの組み合わせ等が挙げられる。好ましくは、酸素含有量が30ppm以下の低酸素銅、さらに好ましくは20ppm以下の低酸素銅または無酸素銅の導体である。酸素含有量が30ppm以下であれば、導体を溶接するために熱で溶融させた場合、溶接部分に含有酸素に起因するボイドの発生がなく、溶接部分の電気抵抗が悪化することを防止するとともに溶接部分の強度を保持することができる。
矩形の導体1の大きさは、特に限定はないが、幅(長辺)は1~5mmが好ましく、1.4~4.0mmがより好ましく、厚み(短辺)は0.4~3.0mmが好ましく、0.5~2.5mmがより好ましい。幅(長辺)と厚み(短辺)の長さの割合は、1:1~1:4が好ましい。
また、矩形の4隅に面取り(曲率半径r)を設けた形状であることが望ましい。曲率半径rは、0.6mm以下が好ましく、0.2~0.4mmがより好ましい。
発泡絶縁層の厚さに制限はないが、本発明では、10~200μmが好ましい。
また、本発明では、発泡絶縁層は1層でも2層以上の複数の層からなっていてもよい。
熱硬化性樹脂としては、従来用いられているものを使用することができる。本発明では、ポリアミドイミド(PAI)、ポリイミド(PI)、ポリアミド(PA)、ポリエーテルイミド(PEI)、ポリエステルイミド(PEsI)およびポリエーテルサルフォン(PES)から選択される樹脂が好ましく、なかでも耐溶剤性に優れるポリアミドイミド(PAI)およびポリイミド(PI)がより好ましく、ポリアミドイミド(PAI)が特に好ましい。
使用する熱硬化性樹脂は、1種を単独で用いてもよく、2種以上を混合して用いてもよい。
ポリイミドとしては、例えば、Uイミド(ユニチカ株式会社製、商品名)、U-ワニス(宇部興産株式会社製、商品名)、HCIシリーズ(日立化成株式会社製、商品名)、オーラム(三井化学株式会社製、商品名)などを使用することができる。
ここで、気泡密度の差は、同一発泡樹脂層内での密度差であり、以下の方法で絶縁ワイヤの絶縁皮膜を観測して、気泡密度を求めることができる。
厚み方向のSEM写真より、空孔の分布が明確ではない場合、導体側より5μm×5μmごとに計測範囲を設定する。なお、図4に示すSEM写真がこの場合に相当する。例えば、発泡絶縁層の厚みが30μmの場合、計測範囲は縦方向に計6ヵ所となる。
計測範囲を画像解析し、面積率を算出する。
ここで、面積率とは、計測範囲の面積における空隙の割合である。算出した面積率(%)を気泡密度(%)とする。
なお、厚み方向で3%以上の気泡密度の差があれば、気泡密度に傾斜が有ると判断される。
本発明では、気泡密度に3%以上の傾斜があれば、気泡密度に傾斜を有しない場合と比較して可とう性が優位に向上することを見出したものである。
本発明で、気泡密度を論じる際は、上記の観点で任意に設定した縦横ピクセル数の範囲を「中」、「中」の範囲を含まずにこれより導体側に設定した任意の縦横ピクセル数の範囲を「下」、「中」の範囲を含まずにこれより皮膜表面側に設定した任意の縦横ピクセル数の範囲を「上」と分類することがある。
本発明の絶縁ワイヤは、導体と熱硬化性樹脂からなる発泡絶縁層の間に、熱硬化性樹脂からなる内側絶縁層を有してもよい。なお、この内側絶縁層は、発泡絶縁層でないことが好ましい。
内側絶縁層の厚みは、1~40μmが好ましく、1~25μmがより好ましい。
本発明の絶縁ワイヤは、発泡絶縁層の外周に、直接もしくは内部絶縁層を介して、外側絶縁層が形成されていてもよい。
本発明者らは、発泡絶縁層に空気が含まれることによって形状を変形させられることを利用し、この発泡絶縁層の上層に外側絶縁層として熱可塑性樹脂の層を設けることで空気ギャップを埋めることができ、よって部分放電の発生を抑制する性能に優れることを見出した。この効果をさらに高めるために、外側絶縁層に使用される熱可塑性樹脂として、非晶性樹脂である場合には240℃以上のガラス転移温度を有する熱可塑性樹脂、または、結晶性樹脂である場合には240℃以上の融点を有する熱可塑性樹脂を用いることが好ましい。
本発明において「気泡をもたない」とは完全に気泡のない状態に加えて、本発明の目的を損なわない程度、すなわち、直径0.1μm未満の空隙の場合は気泡をもたない状態に包含される。直径0.1μm未満の気泡径の有無については、発泡絶縁層の断面を走査電子顕微鏡(SEM)で観察することで確認できる。
熱可塑性樹脂組成物の成形は発泡絶縁層の周囲に直接または間に別の樹脂層、すなわち内部絶縁層を介在させることもできる。
内部絶縁層を形成する樹脂は、熱可塑性樹脂が好ましく、外側絶縁層で挙げた熱可塑性樹脂が挙げられる。内部絶縁層を形成するための熱可塑性樹脂組成物は、熱可塑性樹脂に加えて、例えば、発泡絶縁層を形成するワニスに添加される各種添加剤または前記有機溶剤などを、特性に影響を及ぼさない範囲で、含有していてもよい。
内側絶縁層や内部絶縁層は、内側絶縁層または内部絶縁層を形成するワニスを塗布し、内側絶縁層は焼付けることによって、内部絶縁層は、樹脂組成物を押出成形、溶媒蒸発などの成形方法によって、それぞれ、形成できる。
なお、厚みの薄い密着層では、発泡絶縁層上に、外側絶縁層を形成する非晶性熱可塑性樹脂と同様の非晶性熱可塑性樹脂を溶媒に溶解させた塗料を塗布し、溶媒を蒸発させることによって、形成できる。
外側絶縁層3を有しない以外は、図2(a)に示す絶縁ワイヤを下記のようにして作製した。
まず、発泡絶縁層2を形成するのに用いる発泡ポリアミドイミドワニスを以下のように作製した。2L容セパラブルフラスコに、HI-406シリーズ〔樹脂成分32質量%のN-メチルピロリドン(NMP)溶液、NMPの沸点202℃〕(商品名、日立化成株式会社製)1000gを入れ、この溶液に気泡形成剤としてトリエチレングリコールジメチルエーテル(沸点216℃)100gとジエチレングリコールジブチルエーテル(沸点256℃)150gを添加することにより得た。
また、内側絶縁層25である導体側絶縁層を形成するのに用いる内側絶縁層形成用ポリアミドイミドワニスはHI-406シリーズ(樹脂成分32質量%のNMP溶液)(商品名、日立化成株式会社製)を用いた。この樹脂1000gに溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
各ワニスはディップコーティングにより塗布し、ダイスによって塗布量を調節した。具体的には、1.0mmφの銅導体1に調製した内側絶縁層形成用ポリアミドイミドワニスを塗布し、これを炉温500℃にて焼き付けて厚さ5μmの内側絶縁層25を形成した。次いで、内側絶縁層25上に、上記で調製した発泡ポリアミドイミドワニスを塗布し、これを前半は炉温580℃、後半は炉温420℃にて焼き付けて厚さ80μmの発泡絶縁層2を形成した。「前半」で、炉温580℃で焼き付けた部分は気泡密度が65%の部分に相当し、「後半」の炉温420℃で焼き付けた部分は気泡密度が15%の部分に相当する。
このようにして内側絶縁層25および発泡絶縁層2が形成された絶縁ワイヤを作製した。
実施例1の内側絶縁層25を設けないで、1.0mmφの銅導体1上に80μmの厚みの発泡絶縁層2のみを設けた。
まず、発泡絶縁層2を形成するのに用いる発泡ポリイミドワニスを以下のように作製した。2L容セパラブルフラスコに、Uイミド(樹脂成分25質量%のNMP溶液)(商品名、ユニチカ株式会社製)1000gを入れ、気泡形成剤としてNMP(沸点202℃)75g、DMAC(沸点165℃)150gおよびテトラエチレングリコールジメチルエーテル(沸点275℃)200gを添加することにより得た。実施例1と同じ導体1上に、上記で調整した発泡ポリイミドワニスを塗布し、これを前半は炉温540℃、後半は炉温520℃にて焼き付けて、厚さ80μmの発泡絶縁層2が形成された絶縁ワイヤを作製した。「前半」で、炉温540℃で焼き付けた部分は気泡密度が50%の部分に相当し、「後半」の炉温520℃で焼き付けた部分は気泡密度が45%の部分に相当する。
このようにして発泡絶縁層2が形成された絶縁ワイヤを作製した。
実施例1と同様に、導体1上に、内側絶縁層25、発泡絶縁層2を設けた。
まず、発泡絶縁層2を形成するのに用いる発泡ポリイミドワニスを以下のように作製した。2L容セパラブルフラスコに、Uイミド(樹脂成分25質量%のNMP溶液)(商品名、ユニチカ株式会社製)1000gを入れ、NMP(沸点202℃)75g、DMAC(沸点165℃)150gおよびテトラエチレングリコールジメチルエーテル(沸点275℃)200gを添加することにより得た。
また、内側絶縁層25である導体側絶縁層を形成するのに用いる内側絶縁層形成用ポリイミドワニスはUイミド(樹脂成分25質量%のNMP溶液)(商品名、ユニチカ株式会社製)を用いた。この樹脂1000gに溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
各ワニスはディップコーティングにより塗布し、ダイスによって塗布量を調節した。具体的には、実施例1と同じ銅導体1上に調製した内側絶縁層形成用ポリイミドワニスを塗布し、これを炉温500℃にて焼き付けて厚さ5μmの内側絶縁層25を形成した。次いで、内側絶縁層25上に、上記で調製した発泡ポリイミドワニスを塗布し、これを前半は炉温440℃、後半は炉温460℃で焼き付けて厚さ50μmの発泡絶縁層2を形成した。「前半」で、炉温440℃で焼き付けた部分は気泡密度が20%の部分に相当し、「後半」の炉温460℃で焼き付けた部分は気泡密度が23%の部分に相当する。
このようにして内側絶縁層25および発泡絶縁層2が形成された絶縁ワイヤを作製した。
実施例1と同様に、導体1上に、内側絶縁層25、発泡絶縁層aを設け、さらに、該発泡絶縁層a上に、発泡絶縁層aとは異なる発泡絶縁層bを設けた。
まず、発泡絶縁層aを形成するのに用いる発泡ポリアミドイミドワニスを以下のように作製した。2L容セパラブルフラスコに、HI-406シリーズ〔樹脂成分32質量%のN-メチルピロリドン(NMP)溶液、NMPの沸点202℃〕(商品名、日立化成株式会社製)1000gを入れ、この溶液に気泡形成剤としてトリエチレングリコールジメチルエーテル(沸点216℃)100gとジエチレングリコールジブチルエーテル(沸点256℃)150gを添加することにより得た。
また、発泡絶縁層bを形成するのに用いる発泡ポリイミドワニスを以下のように作製した。2L容セパラブルフラスコに、Uイミド(樹脂成分25質量%のNMP溶液)(商品名、ユニチカ株式会社製)1000gを入れ、NMP(沸点202℃)75g、DMAC(沸点165℃)150gおよびテトラエチレングリコールジメチルエーテル(沸点275℃)200gを添加することにより得た。
さらに、内側絶縁層25である導体側絶縁層を形成するのに用いる内側絶縁層形成用ポリアミドイミドワニスはHI-406シリーズ(樹脂成分32質量%のNMP溶液)(商品名、日立化成株式会社製)を用いた。この樹脂1000gに溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
各ワニスはディップコーティングにより塗布し、ダイスによって塗布量を調節した。
実施例1と同じ銅導体1に、調製した内側絶縁層形成用ポリアミドイミドワニスを塗布し、これを炉温500℃にて焼き付けて厚さ3μmの内側絶縁層25を形成した。次いで、内側絶縁層25上に、上記で調製した発泡絶縁層aを形成する発泡ポリアミドイミドワニスを塗布し、これを前半は炉温560℃、後半は炉温440℃で焼き付けて厚さ30μmの発泡絶縁層aを形成した。「前半」で、炉温560℃で焼き付けた部分は気泡密度が60%の部分に相当し、「後半」の炉温440℃で焼き付けた部分は気泡密度が20%の部分に相当する。
次いで、発泡絶縁層a上に、上記で調整した発泡絶縁層bを形成する発泡ポリイミドワニスを塗布し、これを前半は炉温560℃、後半は炉温520℃で焼き付けて厚さ30μmの発泡絶縁層bを形成した。「前半」で、炉温560℃で焼き付けた部分は気泡密度が55%の部分に相当し、「後半」の炉温520℃で焼き付けた部分は気泡密度が45%の部分に相当する。
このようにして内側絶縁層25および2層の発泡絶縁層2(aおよびb)が形成された絶縁ワイヤを作製した。
実施例1と同様に、導体1上に、内側絶縁層25、発泡絶縁層2を設けた。
まず、発泡絶縁層2を形成するのに用いる発泡ポリアミドイミドワニスを以下のように作製した。2L容セパラブルフラスコに、HI-406シリーズ〔樹脂成分32質量%のN-メチルピロリドン(NMP)溶液、NMPの沸点202℃〕(商品名、日立化成株式会社製)1000gを入れ、この溶液に気泡形成剤としてトリエチレングリコールジメチルエーテル(沸点216℃)100gとジエチレングリコールジブチルエーテル(沸点256℃)150gを添加することにより得た。
また、内側絶縁層25である導体側絶縁層を形成するのに用いる内側絶縁層形成用ポリアミドイミドワニスはHI-406シリーズ(樹脂成分32質量%のNMP溶液)(商品名、日立化成株式会社製)を用いた。この樹脂1000gに溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
各ワニスはディップコーティングにより塗布し、ダイスによって塗布量を調節した。具体的には、実施例1と同じ銅導体1上に調製した内側絶縁層形成用ポリアミドイミドワニスを塗布し、これを炉温500℃にて焼き付けて厚さ5μmの内側絶縁層25を形成した。次いで、内側絶縁層25上に、上記で調製した発泡ポリアミドイミドワニスを塗布し、これを前半は炉温600℃、中間は炉温500℃、後半は炉温400℃で焼き付けて厚さ150μmの発泡絶縁層2を形成した。「前半」で、炉温600℃で焼き付けた部分は気泡密度が70%の部分に相当し、「中間」で、炉温500℃で焼き付けた部分は気泡密度が40%の部分に相当し、「後半」の炉温400℃で焼き付けた部分は気泡密度が10%の部分に相当する。
このようにして内側絶縁層25および発泡絶縁層2が形成された絶縁ワイヤを作製した。
実施例1と同様に、導体1上に、内側絶縁層25、発泡絶縁層2を設け、さらに該発泡絶縁層2上に、外側絶縁層3を設けた。
まず、発泡絶縁層2を形成するのに用いる発泡ポリアミドイミドワニスを以下のように作製した。2L容セパラブルフラスコに、HI-406シリーズ〔樹脂成分32質量%のN-メチルピロリドン(NMP)溶液、NMPの沸点202℃〕(商品名、日立化成株式会社製)1000gを入れ、この溶液に気泡形成剤としてトリエチレングリコールジメチルエーテル(沸点216℃)100gとジエチレングリコールジブチルエーテル(沸点256℃)150gを添加することにより得た。
また、内側絶縁層25である導体側絶縁層を形成するのに用いる内側絶縁層形成用ポリアミドイミドワニスはHI-406シリーズ(樹脂成分32質量%のNMP溶液)(商品名、日立化成株式会社製)を用いた。この樹脂1000gに溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
各ワニスはディップコーティングにより塗布し、ダイスによって塗布量を調節した。具体的には、実施例1と同じ銅導体1上に調製した内側絶縁層形成用ポリアミドイミドワニスを塗布し、これを炉温500℃にて焼き付けて厚さ4μmの内側絶縁層25を形成した。次いで、内側絶縁層25上に、上記で調製した発泡ポリアミドイミドワニスを塗布し、これを炉温前半は炉温600℃、中間は炉温440℃、後半は炉温600℃で焼き付けて厚さ40μmの発泡絶縁層2を形成した。「前半」で、炉温600℃で焼き付けた部分は気泡密度が70%の部分に相当し、「中間」で、炉温440℃で焼き付けた部分は気泡密度が20%の部分に相当し、「後半」の炉温600℃で焼き付けた部分は気泡密度が70%の部分に相当する。
実施例1と同様に、導体1上に、内側絶縁層25、発泡絶縁層2を設けた。
まず、発泡絶縁層2を形成するのに用いる発泡ポリイミドワニスを以下のように作製した。2L容セパラブルフラスコに、Uイミド(樹脂成分25質量%のNMP溶液)(商品名、ユニチカ株式会社製)1000gを入れ、気泡形成剤としてNMP(沸点202℃)75g、DMAC(沸点165℃)150gおよびテトラエチレングリコールジメチルエーテル(沸点275℃)200gを添加することにより得た。
また、内側絶縁層25である導体側絶縁層を形成するのに用いる内側絶縁層形成用ポリアミドイミドワニスはHI-406シリーズ(樹脂成分32質量%のNMP溶液)(商品名、日立化成株式会社製)を用いた。この樹脂1000gに溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
各ワニスはディップコーティングにより塗布し、ダイスによって塗布量を調節した。
実施例1と同じ銅導体1に、調製した内側絶縁層形成用ポリアミドイミドワニスを塗布し、これを炉温500℃にて焼き付けて厚さ5μmの内側絶縁層25を形成した。次いで、内側絶縁層25上に、上記で調整した発泡ポリイミドワニスを塗布し、これを前半は炉温540℃、後半は炉温440℃にて焼き付けて、厚さ30μmの発泡絶縁層2を形成した。「前半」で、炉温540℃で焼き付けた部分は気泡密度が50%の部分に相当し、「後半」の炉温440℃で焼き付けた部分は気泡密度が35%の部分に相当する。
このようにして内側絶縁層25および発泡絶縁層2が形成された絶縁ワイヤを作製した。
実施例1と同様に、導体1上に、内側絶縁層25、発泡絶縁層2を設け、さらに該発泡絶縁層2上に、外側絶縁層3を設けた。
まず、発泡絶縁層2を形成するのに用いる発泡ポリイミドワニスを以下のように作製した。2L容セパラブルフラスコに、Uイミド(樹脂成分25質量%のNMP溶液)(商品名、ユニチカ株式会社製)1000gを入れ、気泡形成剤としてNMP(沸点202℃)75g、DMAC(沸点165℃)150gおよびテトラエチレングリコールジメチルエーテル(沸点275℃)200gを添加することにより得た。
また、内側絶縁層25である導体側絶縁層を形成するのに用いる内側絶縁層形成用ポリアミドイミドワニスはHI-406シリーズ(樹脂成分32質量%のNMP溶液)(商品名、日立化成株式会社製)を用いた。この樹脂1000gに溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
各ワニスはディップコーティングにより塗布し、ダイスによって塗布量を調節した。
実施例1と同じ銅導体1に、調製した内側絶縁層形成用ポリアミドイミドワニスを塗布し、これを炉温500℃にて焼き付けて厚さ5μmの内側絶縁層25を形成した。次いで、内側絶縁層25上に、上記で調整した発泡ポリイミドワニスを塗布し、これを前半は炉温420℃、後半は炉温560℃にて焼き付けて、厚さ8μmの発泡絶縁層2を形成した。「前半」で、炉温420℃で焼き付けた部分は気泡密度が15%の部分に相当し、「後半」の炉温560℃で焼き付けた部分は気泡密度が55%の部分に相当する。
これを発泡絶縁層2上にディップコーティングにより塗布し、炉温500℃にて焼き付けて厚さ25μmの外側絶縁層3を形成した。
このようにして、内側絶縁層25、発泡絶縁層2および外側絶縁層3を有する絶縁ワイヤを作製した。
導体1上に、内側絶縁層25と発泡絶縁層でない通常の熱硬化性樹脂からなる絶縁層を設けた。
まず、熱硬化性樹脂からなる絶縁層を形成するのに用いるポリアミドイミドワニスを以下のように作製した。2L容セパラブルフラスコに、HI-406シリーズ(樹脂成分32質量%のNMP溶液、NMPの沸点202℃)(商品名、日立化成株式会社製)1000gを入れ、この溶液に溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
また、内側絶縁層25である導体側絶縁層を形成するのに用いる内側絶縁層形成用ポリイミドはUイミド(樹脂成分25質量%のNMP溶液)(商品名、ユニチカ株式会社製)を用いた。この樹脂1000gに溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
各ワニスはディップコーティングにより塗布し、ダイスによって塗布量を調節した。具体的には、実施例1と同じ銅導体1上に調製した内側絶縁層形成用ポリアミドイミドワニスを塗布し、これを炉温500℃にて焼き付けて厚さ3μmの内側絶縁層25を形成した。次いで、内側絶縁層25上に、上記で調製したポリアミドイミドワニスを塗布し、これを炉温500℃で焼き付けて厚さ30μmの熱硬化性樹脂からなる絶縁層を形成した。
このようにして、内側絶縁層25、発泡絶縁層でない通常の絶縁層を有する絶縁ワイヤを作製した。
実施例1と同様に、導体1上に、内側絶縁層25、発泡絶縁層2を設けた。
まず、発泡絶縁層2を形成するのに用いる発泡ポリイミドワニスを以下のように作製した。2L容セパラブルフラスコに、Uイミド(樹脂成分25質量%のNMP溶液)(商品名、ユニチカ株式会社製)1000gを入れ、NMP(沸点202℃)75g、DMAC(沸点165℃)150gおよびテトラエチレングリコールジメチルエーテル(沸点275℃)200gを添加することにより得た。
また、内側絶縁層25である導体側絶縁層を形成するのに用いる内側絶縁層形成用ポリイミドワニスはUイミド(樹脂成分25質量%のNMP溶液)(商品名、ユニチカ株式会社製)を用いた。この樹脂1000gに溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
各ワニスはディップコーティングにより塗布し、ダイスによって塗布量を調節した。具体的には、実施例1と同じ銅導体1上に調製した内側絶縁層形成用ポリイミドワニスを塗布し、これを炉温500℃にて焼き付けて厚さ3μmの内側絶縁層25を形成した。次いで、内側絶縁層25上に、上記で調製した発泡ポリイミドワニスを塗布し、これを炉温600℃で焼き付けて厚さ50μmで、気泡密度70%の発泡絶縁層2を形成した。
このようにして内側絶縁層25および発泡絶縁層2が形成された絶縁ワイヤを作製した。
実施例1と同様に、導体1上に、内側絶縁層25、発泡絶縁層2を設けた。
まず、発泡絶縁層2を形成するのに用いる発泡ポリアミドイミドワニスを以下のように作製した。2L容セパラブルフラスコに、HI-406シリーズ〔樹脂成分32質量%のN-メチルピロリドン(NMP)溶液、NMPの沸点202℃〕(商品名、日立化成株式会社製)1000gを入れ、この溶液に気泡形成剤としてトリエチレングリコールジメチルエーテル(沸点216℃)100gとジエチレングリコールジブチルエーテル(沸点256℃)150gを添加することにより得た。
また、内側絶縁層25である導体側絶縁層を形成するのに用いる内側絶縁層形成用ポリアミドイミドワニスはHI-406シリーズ(樹脂成分32質量%のNMP溶液)(商品名、日立化成株式会社製)を用いた。この樹脂1000gに溶剤としてNMPを用いて30質量%樹脂溶液として用いた。
各ワニスはディップコーティングにより塗布し、ダイスによって塗布量を調節した。
実施例1と同じ銅導体1に、調製した内側絶縁層形成用ポリアミドイミドワニスを塗布し、これを炉温500℃にて焼き付けて厚さ5μmの内側絶縁層25を形成した。次いで、内側絶縁層25上に、上記で調製した発泡ポリイミドワニスを塗布し、これを炉温580℃で焼き付けて厚さ25μmで、気泡密度65%の発泡絶縁層2を形成した。
このようにして内側絶縁層25および発泡絶縁層2が形成された絶縁ワイヤを作製した。
前述のようにして、絶縁ワイヤの絶縁皮膜を液体窒素中で冷却しながら厚み方向にへき開し、厚み方向での断面を走査電子顕微鏡(SEM)により300~3000倍で撮影した。皮膜全体の厚さが観察画面に全て収まるように倍率を調整した。撮影した断面のSEM写真を、面積率が算出できる画像解析ソフト「WinROOF ver.7.1」(三谷商事社製)に取り込んだ。得られた計測範囲を画像解析し、面積率(%)を算出し、気泡密度(%)とした。
なお、下記表1中の「上」、「中」、「下」は、SEM写真を視覚的に判断した大まかな気泡密度の区分であり、表の個々のセルに記載の気泡密度は、観測した視野における実際の観測範囲における気泡密度である。
実施例及び比較例における各層の厚さ、発泡絶縁層を含む各絶縁層の厚さおよび発泡絶縁層中の平均気泡径は、絶縁ワイヤの厚み方向の断面の走査電子顕微鏡(SEM)像で測定および算出した。発泡絶縁層中の平均気泡径は上記走査電子顕微鏡(SEM)像において、50個の気泡を無作為に選び、画像寸法計測ソフト(三谷商事社製WinROOF)を用い、径測定モードにて平均の気泡径を算出し、得られた値を気泡径とした。
上記で製造した各絶縁ワイヤを絶縁ワイヤ毎に、それぞれ2本をツイスト状に撚り合わせた試験片を作製し、2本の導体間に正弦波50Hzの交流電圧を印加して、連続的に昇圧させながら放電電荷量が10pCのときの電圧(実効値)を測定した。測定温度は常温とした。部分放電開始電圧の測定には部分放電試験機(菊水電子工業製、KPD2050)を用いた。部分放電開始電圧は、850V以上であれば、部分放電が発生しにくく絶縁ワイヤの部分劣化を防止できる。このため、得られた部分放電開始電圧を下記のランクで評価した。
A:部分放電開始電圧が900V以上
B:部分放電開始電圧が850V以上900V未満
C:部分放電開始電圧が500V以上850V未満
D:部分放電開始電圧が500V未満
可とう性の試験はJIS C 3216-3に従って実施した。直線状の絶縁ワイヤを、個別規格に規定する直径をもつ表面の滑らかな丸棒に沿って線と線とが接触するように10回巻いた。丸棒の回転速度は、毎秒1~3回の割合とし、線と丸棒とが接触するように張力をかけた。作製した試験片について、目視および15倍の拡大鏡にて亀裂の有無を調べ、可とう性を、以下のランクで評価した。
A:目視および15倍の拡大鏡で観察して全く亀裂がみられない
B:目視にて亀裂は観測されず15倍の拡大鏡では僅かな亀裂がみられる
C:JIS C 3216-5規定のピンホール試験で微小な欠陥が観測される
D:目視で亀裂が観測される
一方向摩耗試験はJIS C 3216に準じて実施した。試験装置はNEMAスクレープテスター(株式会社東洋精機製作所社製)を用いた。この試験は直線状の試験片について連続的に増加する力が針に加わるようにし、その針で試験片の表面を擦っていくものである。針と導体の間で導通が生じたときの力を破壊力とした。得られた結果を、下記ランクで評価した。
A:破壊力が2500g以上
B:破壊力が1500g以上2500g未満
C:破壊力が1000g以上1500g未満
D:破壊力が1000g未満
以下に示す導電性銅箔テープ法で評価した。
上記で作製した絶縁ワイヤを、適切な長さ(約20cmの長さ)に切り出し、中央付近に20mm幅の導電性銅箔テープを巻き付け、銅箔と導体間に正弦波50Hzの交流電圧を印加して、連続的に昇圧させながら絶縁破壊した。電圧(実効値)を測定した。なお、測定温度は25℃で行った。この結果を下記ランクで評価した。
A:絶縁破壊電圧が10kV以上
B:絶縁破壊電圧が8kV以上10kV未満
C:絶縁破壊電圧が5kV以上8kV未満
D:絶縁破壊電圧が5kV未満
総合評価は、4項目における「A」の個数により判定した。「A」が3個以上のものは「A」、2個のものは「B」、1個のものは「D」とした。また、「C」が2個の場合も総合評価は「D」とした。すなわち、総合評価は、少なくとも「B」以上が要求される。
また、実施例1~8および比較例1~3の絶縁ワイヤの厚さ方向での模式的な断面図を図6に示した。
この結果、当初、両立が困難と予想された、高い部分放電開始電圧と優れた可とう性を両立させることができた。
これに対し、発泡絶縁層を有さない比較例1では、部分放電開始電圧が低かった。また、発泡絶縁層の厚さ方向で発泡密度に差がなく、均一な発泡密度である比較例2、3では、部分放電開始電圧は高いものの、可とう性は、本発明の絶縁ワイヤ(実施例1~8)より、ランクが低かった。
これに加えて、発泡絶縁層を有さない比較例1では、絶縁破壊電圧が低く、比較例2、3では絶縁破壊電圧および一方向摩擦性での破壊力がともに低かった。
すなわち、比較例1~3はいずれも、ランクAが1つであって、しかもランクCが2つであり、総合的に劣っていた。
2 発泡絶縁層
3 外側絶縁層
25 内側絶縁層
26 内部絶縁層
35 内部絶縁層
Claims (6)
- 導体の外周面上に直接または間接的に少なくとも1層の気泡を有する熱硬化性樹脂からなる発泡絶縁層を有し、該発泡絶縁層が厚さ方向において気泡密度が異なることを特徴とする絶縁ワイヤ。
- 前記発泡絶縁層の厚さ方向における気泡密度差が、3%以上であることを特徴とする請求項1に記載の絶縁ワイヤ。
- 前記発泡絶縁層における平均気泡径が、10μm以下であることを特徴とする請求項1または2に記載の絶縁ワイヤ。
- 前記発泡絶縁層の厚さが、10~200μmであることを特徴とする請求項1~3のいずれか1項に記載の絶縁ワイヤ。
- 前記熱硬化性樹脂が、ポリアミドイミド樹脂、ポリイミド樹脂、ポリアミド樹脂、ポリエーテルイミド樹脂、ポリエステルイミド樹脂およびポリエーテルサルフォン樹脂から選択されることを特徴とする請求項1~4のいずれか1項に記載の絶縁ワイヤ。
- 請求項1~5のいずれか1項に記載の絶縁ワイヤを用いてなることを特徴とする回転電機。
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EP4156470A1 (en) | 2021-09-27 | 2023-03-29 | Hitachi Metals, Ltd. | Insulated electrical wire and method of manufacturing insulated electrical wire |
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KR20200006975A (ko) * | 2018-03-12 | 2020-01-21 | 후루카와 덴키 고교 가부시키가이샤 | 집합 도선, 집합 도선의 제조 방법 및 세그먼트 코일 |
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