WO2018180847A1 - Insulated electric cable - Google Patents

Insulated electric cable Download PDF

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Publication number
WO2018180847A1
WO2018180847A1 PCT/JP2018/011304 JP2018011304W WO2018180847A1 WO 2018180847 A1 WO2018180847 A1 WO 2018180847A1 JP 2018011304 W JP2018011304 W JP 2018011304W WO 2018180847 A1 WO2018180847 A1 WO 2018180847A1
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Prior art keywords
insulating layer
resin
conductor
insulated wire
film thickness
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PCT/JP2018/011304
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French (fr)
Japanese (ja)
Inventor
槙弥 太田
雅晃 山内
吉田　健吾
田村　康
Original Assignee
住友電気工業株式会社
住友電工ウインテック株式会社
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Application filed by 住友電気工業株式会社, 住友電工ウインテック株式会社 filed Critical 住友電気工業株式会社
Priority to JP2019509639A priority Critical patent/JP7214625B2/en
Publication of WO2018180847A1 publication Critical patent/WO2018180847A1/en

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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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F5/00—Coils
    • H01F5/06—Insulation of windings

Definitions

  • the present invention relates to an insulated wire.
  • This application claims priority based on Japanese Patent Application No. 2017-069028 filed on Mar. 30, 2017, and incorporates all the description content described in the above Japanese application.
  • an electric device having a high applied voltage for example, a motor used at a high voltage
  • a high voltage is applied to an insulated wire constituting the electric device, and partial discharge (corona discharge) is likely to occur on the surface of the insulating layer.
  • partial discharge corona discharge
  • dielectric breakdown occurs at an early stage, and the life of the insulated wire and thus the electrical equipment is shortened.
  • an insulated wire used for an electric device having a high applied voltage is required to improve the corona discharge start voltage.
  • the dielectric constant of the insulating layer As a device for increasing the corona discharge starting voltage, it is effective to lower the dielectric constant of the insulating layer.
  • the methods for reducing the dielectric constant there is a method of forming pores in the insulating layer.
  • a method for forming pores in the insulating layer As a method for forming pores in the insulating layer, a method using a foaming agent such as azobisisobutyronitrile or a heat-expandable microcapsule (see Japanese Patent Laid-Open Nos. 5-20928 and 8-77849), and A method using a solvent of a thermosetting resin, a mixed solvent of a solvent having a boiling point higher than that of the solvent and a bubble forming agent has been proposed.
  • a foaming agent such as azobisisobutyronitrile or a heat-expandable microcapsule
  • An insulated wire according to an aspect of the present invention is an insulated wire including a linear conductor and an insulating layer coated on an outer peripheral surface of the conductor, the insulating layer including a plurality of pores, and the insulating layer
  • the porosity of the insulating wire is 20 volume% or more and 65 volume% or less, and the thickness of the insulating layer at 8 points is measured for each cross section at 30 cross sections at 50 cm intervals in the longitudinal direction of the insulated wire.
  • the variation ratio of the following formula (1) calculated from the measured value is 25% or less.
  • Variation ratio (%) (4 ⁇ / average film thickness) ⁇ 100 (1) (In the above formula (1), the average film thickness indicates the average value of each measurement value, and ⁇ indicates the standard deviation of each measurement value.)
  • the dielectric constant can be lowered by increasing the porosity of the insulating layer.
  • the insulating layer formed by the above-described conventional technology it is difficult to control the foaming ratio of the foaming agent, or a plurality of solvents having different volatilization rates are used. Becomes non-uniform around the conductor cross section. Further, the thickness of the insulating layer has a great influence on the insulation and strength of the insulated wire, and there is a possibility that the insulation and strength are insufficient particularly in a portion where the insulating layer is thin.
  • the present invention has been made based on the above circumstances, and an object thereof is to provide an insulated wire excellent in insulation and strength while achieving a low dielectric constant of an insulating layer.
  • the insulated wire of the present invention is excellent in insulation and strength while achieving a low dielectric constant of the insulating layer.
  • An insulated wire according to an aspect of the present invention is an insulated wire including a linear conductor and an insulating layer coated on an outer peripheral surface of the conductor, the insulating layer including a plurality of pores, and the insulating layer
  • the porosity of the insulating wire is 20 volume% or more and 65 volume% or less, and the thickness of the insulating layer at 8 points is measured for each cross section at 30 cross sections at 50 cm intervals in the longitudinal direction of the insulated wire.
  • the variation ratio of the following formula (1) calculated from the measured value is 25% or less.
  • Variation ratio (%) (4 ⁇ / average film thickness) ⁇ 100 (1) (In the above formula (1), the average film thickness indicates the average value of each measurement value, and ⁇ indicates the standard deviation of each measurement value.)
  • the insulated wire includes pores in the insulating layer, and by setting the porosity of the insulating layer within the above range, it is possible to achieve a low dielectric constant of the insulating layer.
  • the insulated wire can reduce the minimum film thickness by increasing the uniformity of the film thickness by setting the variation rate of the film thickness of the insulating layer to the above value or less, and as a result, the corona discharge starting voltage is improved.
  • it has excellent insulating properties and excellent strength.
  • porosity means the percentage of the volume of the pores with respect to the volume including the pores of the insulating layer.
  • the average film thickness of the insulating layer is preferably 60 ⁇ m or more.
  • the insulated wire can improve insulation and intensity
  • the conductor is preferably a rectangular conductor having a rectangular cross section. In general, even in the case of a rectangular conductor in which it is difficult to make the thickness of the insulating layer uniform, it is possible to reduce the dielectric constant of the insulating layer and to provide an insulated wire excellent in insulation and strength.
  • the insulated wire in FIG. 1 includes a linear conductor 1 and an insulating layer 2 that covers the outer peripheral surface of the conductor 1.
  • the insulating layer 2 includes a plurality of pores 3.
  • the cross-sectional shape of the conductor 1 examples include a circular shape, an elliptical shape, a racetrack shape, a hexagonal shape, a triangular shape, a polygonal shape such as a square shape such as a square, and a rectangle.
  • the conductor 1 is preferably a square conductor with a square cross section or a flat conductor with a rectangular cross section.
  • the conductor 1 may be a stranded wire obtained by twisting a plurality of strands.
  • the material of the conductor 1 is preferably a metal having high electrical conductivity and high mechanical strength.
  • metals include copper, copper alloys, aluminum, nickel, silver, soft iron, steel, and stainless steel.
  • the insulating layer 2 includes a plurality of pores 3 as shown in FIG.
  • the lower limit of the porosity of the insulating layer 2 is 20% by volume, preferably 25% by volume, and more preferably 30% by volume.
  • the upper limit of the porosity of the insulating layer 2 is 65% by volume, preferably 60% by volume, and more preferably 55% by volume.
  • the porosity (volume%) of the insulating layer 2 is the same as the mass W1 when there is no pore determined by multiplying the apparent volume V1 calculated from the outer shape of the insulating layer 2 by the density ⁇ 1 of the material of the insulating layer 2, and the insulating layer 2 This is a value obtained from the actual mass W2 of the layer 2 by the formula of (W1-W2) ⁇ 100 / W1.
  • the lower limit of the average film thickness of the insulating layer 2 is preferably 10 ⁇ m, more preferably 60 ⁇ m, further preferably 80 ⁇ m, and particularly preferably 100 ⁇ m.
  • the upper limit of the average film thickness of the insulating layer 2 is preferably 300 ⁇ m, and more preferably 200 ⁇ m. If the average film thickness of the insulating layer 2 is less than the above lower limit, the insulating layer 2 may be torn and insulation of the conductor 1 may be insufficient. On the contrary, when the average film thickness of the insulating layer 2 exceeds the upper limit, the volume efficiency of a coil or the like formed using the insulated wire may be lowered.
  • the upper limit of the film thickness variation ratio of the insulating layer 2 is 25%, preferably 20%, more preferably 15%, still more preferably 12%, and particularly preferably 10%.
  • the lower limit of the variation ratio of the film thickness of the insulating layer 2 is preferably 1% and more preferably 5%. If the variation ratio of the film thickness of the insulating layer 2 exceeds the above upper limit, the insulation and strength of the insulated wire may be insufficient.
  • the variation ratio of the thickness of the insulating layer 2 is determined by measuring the thickness of the insulating layer at 8 points for each cross section at 30 sections at intervals of 50 cm in the longitudinal direction of the insulated wire. Calculated according to (1).
  • Variation ratio (%) (4 ⁇ / average film thickness) ⁇ 100 (1) (In the above formula (1), the average film thickness indicates the average value of each measurement value, and ⁇ indicates the standard deviation of each measurement value.)
  • the lower limit of the average diameter of the pores 3 is preferably 0.1 ⁇ m, and more preferably 1 ⁇ m.
  • the upper limit of the average diameter of the pores 3 is preferably 10 ⁇ m, more preferably 8 ⁇ m.
  • the average diameter of the pores 3 is less than the lower limit, the generation of corona discharge in the insulating layer 2 may not be sufficiently suppressed.
  • the average diameter of the pores 3 exceeds the upper limit, it is difficult to make the distribution of the pores 3 uniform, and there is a risk that the distribution of the dielectric constant is likely to be biased.
  • the insulating layer 2 is formed of an insulating resin composition and pores 3 scattered in the resin composition. This insulating layer 2 is formed by applying and baking varnish on the outer peripheral surface of the conductor 1 described later.
  • thermosetting resin such as polyamideimide or thermosetting polyimide
  • thermoplastic resin such as polyetherimide, polyphenylene ether, polyethersulfone or thermoplastic polyimide.
  • the “main component” is a component having the largest content, for example, a component contained in an amount of 50% by mass or more.
  • the resin composition which forms the insulating layer 2 contain a hardening
  • Curing agents include titanium-based curing agents, isocyanate compounds, blocked isocyanates, urea and melamine compounds, amino resins, alicyclic acid anhydrides such as methyltetrahydrophthalic anhydride, aliphatic acid anhydrides, and aromatic acid anhydrides. Etc. are exemplified. These curing agents are appropriately selected according to the type of resin contained in the resin composition to be used. For example, in the case of polyamideimide, imidazole, triethylamine and the like are preferably used as the curing agent.
  • examples of the titanium-based curing agent include tetrapropyl titanate, tetraisopropyl titanate, tetramethyl titanate, tetrabutyl titanate, and tetrahexyl titanate.
  • isocyanate compounds include aromatic diisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexane diisocyanate, C3-C12 aliphatic diisocyanate such as lysine diisocyanate, 1,4-cyclohexane diisocyanate (CDI), isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), methylcyclohexane diisocyanate, isopropylidene Dicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane (hydrogenated XDI , Hydrogenated TDI
  • Examples thereof include aliphatic diisocyanates having an aromatic ring such as 5-18 alicyclic isocyanate, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and modified products thereof.
  • Examples of the blocked isocyanate include diphenylmethane-4,4′-diisocyanate (MDI), diphenylmethane-3,3′-diisocyanate, diphenylmethane-3,4′-diisocyanate, diphenylether-4,4′-diisocyanate, and benzophenone-4,4.
  • melamine compound examples include methylated melamine, butylated melamine, methylolated melamine, and butyrololized melamine.
  • the method of manufacturing the insulated wire includes diluting a resin that forms the insulating layer 2 and particles (thermally decomposable resin-containing particles) containing a thermally decomposable resin that thermally decomposes at a temperature lower than the baking temperature of the resin. (Varnish preparation process), the process of applying the varnish to the outer peripheral surface of the conductor 1 (varnish application process), and the process of removing the thermally decomposable resin in the thermally decomposable resin-containing particles by heating (heating) Step).
  • the resin forming the insulating layer 2 and the thermally decomposable resin-containing particles are diluted with a solvent to prepare a varnish.
  • the heat decomposable resin contained in the heat decomposable resin-containing particles is not particularly limited as long as the resin has a heat decomposition temperature lower than the baking temperature of the resin forming the insulating layer 2.
  • the baking temperature of the resin forming the insulating layer 2 is appropriately set according to the type of the resin, but is usually about 200 ° C. or higher and 350 ° C. or lower. Therefore, 200 degreeC is preferable as a minimum of the thermal decomposition temperature of the said thermally decomposable resin, and 300 degreeC is preferable as an upper limit.
  • the thermal decomposition temperature means a temperature at which the temperature is increased from room temperature to 10 ° C./min in a nitrogen atmosphere and the mass reduction rate becomes 50%.
  • the thermal decomposition temperature can be determined, for example, by measuring the thermogravimetry using a thermogravimetry-differential thermal analyzer (“TG / DTA” manufactured by SII Nano Technology).
  • the thermally decomposable resin is not particularly limited.
  • the thermally decomposable resin can be evenly distributed as an island phase of fine particles in the sea phase of the resin forming the insulating layer 2 in that independent pores can be formed. Therefore, the thermally decomposable resin is preferably a resin that is excellent in compatibility with the resin forming the insulating layer 2 and can be collected into a spherical shape, and specifically, a crosslinked resin.
  • the above-mentioned crosslinked poly (meth) acrylic polymer can be obtained by polymerizing, for example, a (meth) acrylic monomer and a polyfunctional monomer by emulsion polymerization, suspension polymerization, solution polymerization or the like.
  • the (meth) acrylic monomer acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, dodecyl acrylate, stearyl acrylate, acrylic acid 2 -Ethylhexyl, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate , Dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, diethylaminoethyl methacrylate and the like.
  • examples of the polyfunctional monomer include divinylbenzene, ethylene glycol di (meth) acrylate, trimethylolpropane triacrylate and the like.
  • (meth) acrylic monomer and multifunctional monomer may be used as the constituent monomer of the crosslinked poly (meth) acrylic polymer.
  • Other monomers include glycol esters of (meth) acrylic acid such as ethylene glycol mono (meth) acrylate and polyethylene glycol mono (meth) acrylate, alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, vinyl acetate and vinyl butyrate Vinyl esters, N-alkyl substituted (meth) acrylamides such as N-methylacrylamide, N-ethylacrylamide, N-methylmethacrylamide and N-ethylmethacrylamide, nitriles such as acrylonitrile and methacrylonitrile, styrene, p -Styrene monomers such as methylstyrene, p-chlorostyrene, chloromethylstyrene, ⁇ -methylstyrene, and the like.
  • the heat-decomposable resin-containing particles are preferably spherical.
  • the lower limit of the average particle size of the thermally decomposable resin-containing particles is preferably 0.1 ⁇ m, more preferably 0.5 ⁇ m, and even more preferably 1 ⁇ m.
  • the upper limit of the average particle size of the thermally decomposable resin-containing particles is preferably 100 ⁇ m, more preferably 50 ⁇ m, further preferably 30 ⁇ m, and particularly preferably 10 ⁇ m.
  • the thermally decomposable resin-containing particles form pores in portions where they were thermally decomposed when the resin forming the insulating layer 2 was baked.
  • the average particle size of the thermally decomposable resin-containing particles means a particle size showing the highest content ratio in the particle size distribution measured with a laser diffraction particle size distribution measuring device.
  • the lower limit of the content of the thermally decomposable resin in the varnish is preferably 5 parts by mass, more preferably 10 parts by mass, and even more preferably 15 parts by mass with respect to 100 parts by mass of the resin forming the insulating layer 2.
  • the upper limit of the content of the thermally decomposable resin in the varnish is preferably 350 parts by weight, more preferably 150 parts by weight, and still more preferably 90 parts by weight with respect to 100 parts by weight of the resin forming the insulating layer 2. . If the content of the thermally decomposable resin is less than the lower limit, the dielectric constant of the insulating layer 2 may not be sufficiently reduced. Conversely, if the content of the thermally decomposable resin exceeds the upper limit, the insulated wire may not be able to ensure sufficient strength.
  • the diluting solvent a known organic solvent conventionally used for insulating varnish can be used. Specifically, polar organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, tetramethylurea, hexaethylphosphoric triamide, ⁇ -butyrolactone and the like are used.
  • ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, esters such as methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether (butyl cellosolve) ), Ethers such as diethylene glycol dimethyl ether and tetrahydrofuran, hydrocarbons such as hexane, heptane, benzene, toluene and xylene, dichloro Examples include halogenated hydrocarbons such as methane and chlorobenzene, phenols such as cresol and chlorophenol, and tertiary amines such as pyridine. These organic solvents are used alone or in admixture of two or more. It is done.
  • the upper limit of the resin solid content concentration of the varnish is preferably 50% by mass, and more preferably 28% by mass.
  • the resin solid content concentration of the varnish is less than the lower limit, the amount of application at one time when applying the varnish decreases, and therefore the number of repetitions of the varnish application step for forming the insulating layer 2 having a desired thickness is reduced. There is a risk that the time for the varnish application process will be increased.
  • the resin solid content concentration of the varnish exceeds the above upper limit, the varnish thickens, so that the storage stability of the varnish may be deteriorated and the adhesion at the time of varnish application may be deteriorated.
  • the heat-decomposable resin-containing particles may be particles composed only of the heat-decomposable resin, but a core having the heat-decomposable resin as a main component and a thermal decomposition temperature of the heat-decomposable resin.
  • Core-shell particles having a shell mainly composed of a resin having a high thermal decomposition temperature are preferred.
  • the main component resin of the shell a resin having a low dielectric constant and high heat resistance is preferable.
  • the main resin of the shell include polystyrene, silicone, fluororesin, and polyimide.
  • silicone is preferable in that elasticity is imparted to the shell and insulation and heat resistance are easily improved.
  • the “fluororesin” is a fluorine atom or an organic group in which at least one hydrogen atom bonded to a carbon atom constituting the repeating unit of the polymer chain has a fluorine atom (hereinafter also referred to as “fluorine atom-containing group”). ).
  • the fluorine atom-containing group is a group in which at least one hydrogen atom in a linear or branched organic group is substituted with a fluorine atom, and examples thereof include a fluoroalkyl group, a fluoroalkoxy group, and a fluoropolyether group. Can do.
  • a metal may be contained in a shell in the range which does not impair insulation.
  • the same kind of resin as the resin forming the insulating layer 2 may be used as the main resin of the shell, or a different one may be used.
  • the thermal decomposition temperature is higher than that of the thermally decomposable resin. Since the main component resin is difficult to be thermally decomposed, the effect of suppressing the communication of the pores 3 can be obtained.
  • the insulated wire formed of such a varnish may not be able to confirm the presence of a shell even when observed with an electron microscope.
  • the shell can be made difficult to be integrated with the insulating layer 2 by using a resin different from the resin forming the insulating layer 2 as the main resin of the shell, the same kind of resin as the resin forming the insulating layer 2 can be used. Compared to the case of using a resin, the effect of suppressing the communication of the pores 3 is easily obtained.
  • the upper limit of the average thickness of the shell is preferably 0.5 ⁇ m, and more preferably 0.4 ⁇ m. If the average thickness of the shell is less than the above lower limit, the effect of suppressing the communication of the pores 3 may not be sufficiently obtained. On the contrary, if the average thickness of the shell exceeds the above upper limit, the volume of the pores 3 becomes too small, so that the porosity of the insulating layer 2 may not be increased beyond a predetermined level.
  • the shell may be formed of one layer or a plurality of layers. When the shell is formed of a plurality of layers, the average of the total thickness of the plurality of layers may be within the range of the thickness.
  • the upper limit of the CV value of the thermally decomposable resin-containing particles is preferably 30%, more preferably 20%.
  • the upper limit of the CV value of the thermally decomposable resin-containing particles is preferably 30%, more preferably 20%.
  • the insulating layer 2 is deteriorated due to the concentration of electric charges in the pores caused by the difference in pore size, and the strength of the insulating layer 2 is decreased due to the concentration of processing stress. Can be suppressed.
  • grain For example, it is 1%.
  • the “CV value” means a variable defined in JIS-Z8825 (2013).
  • ⁇ Varnish application process> In the varnish application step, after the varnish prepared in the varnish preparation step is applied to the outer peripheral surface of the conductor 1, the application amount of the varnish of the conductor 1 is adjusted and the applied varnish surface is smoothed by an application die.
  • the coating die has an opening, and when the conductor 1 coated with the varnish passes through the opening, the excess varnish is removed and the coating amount of the varnish is adjusted. Thereby, as for the said insulated wire, the thickness of the insulating layer 2 becomes more uniform, and the insulation and the intensity
  • the heating step the conductor 1 coated with the varnish is passed through a baking furnace, and the varnish is baked to form the insulating layer 2 on the surface of the conductor 1.
  • the thermally decomposable resin of the thermally decomposable resin-containing particles contained in the varnish is gasified and removed by thermal decomposition.
  • pores 3 derived from the thermally decomposable resin-containing particles are formed in the insulating layer 2.
  • the heating process also serves as a varnish baking process.
  • the insulating layer 2 includes the pores 3 and the porosity of the insulating layer 2 is within the above range, whereby the dielectric constant of the insulating layer 2 can be reduced.
  • the insulated wire can reduce the minimum film thickness by reducing the variation ratio of the film thickness of the insulating layer to the above value or less, thereby improving the corona discharge start voltage. In addition, it has excellent insulating properties and excellent strength.
  • the insulated wire in which one insulating layer is laminated on the outer peripheral surface of the conductor has been described, but an insulated electric wire in which a plurality of insulating layers are laminated on the outer peripheral surface of the conductor may be used. That is, one or a plurality of insulating layers may be laminated between the conductor 1 in FIG. 1 and the insulating layer 2 including the pores 3, and one or more insulating layers 2 including the pores 3 in FIG. A plurality of insulating layers may be stacked, or one or a plurality of insulating layers may be stacked on both the outer peripheral surface and the inner peripheral surface of the insulating layer 2 including the pores 3 in FIG.
  • an additional layer such as a primer treatment layer may be provided between the conductor and the insulating layer.
  • a primer process layer is a layer provided in order to improve the adhesiveness between layers, for example, can be formed with a well-known resin composition.
  • the resin composition forming this primer treatment layer is, for example, one or more kinds of resins selected from polyimide, polyamideimide, polyesterimide, polyester and phenoxy resin. It is good to include.
  • the resin composition forming the primer treatment layer may contain an additive such as an adhesion improver.
  • the resin composition forming the primer treatment layer may contain other resins such as an epoxy resin, a phenoxy resin, a melamine resin and the like together with the above resin.
  • the lower limit of the average thickness of the primer treatment layer is preferably 1 ⁇ m, and more preferably 2 ⁇ m.
  • an upper limit of the average thickness of a primer process layer 30 micrometers is preferable and 20 micrometers is more preferable. There exists a possibility that sufficient adhesiveness with a conductor cannot be exhibited as the average thickness of a primer process layer is less than the said minimum. Conversely, if the average thickness of the primer-treated layer exceeds the above upper limit, the insulated wire may be unnecessarily increased in diameter.
  • the insulated wire shown in 1 was manufactured as follows. First, polyimide as a resin for forming an insulating layer was diluted with N-methyl-2-pyrrolidone as a solvent. Next, the core as the thermally decomposable resin-containing particles is PMMA (polymethyl methacrylate resin) particles and the shell is a core-shell particle having an average particle diameter of 3 ⁇ m of silicone, and the calculated porosity is 30 volumes of the insulating layer. The varnish was prepared by dispersing in an amount of%.
  • PMMA polymethyl methacrylate resin
  • the insulated wire shown in 2 was manufactured as follows. First, polyimide as a resin for forming an insulating layer was diluted with N-methyl-2-pyrrolidone as a solvent. Next, core-shell particles having an average particle diameter of 3 ⁇ m, in which the core as the thermally decomposable resin-containing particles is PMMA particles and the shell is silicone, are dispersed in an amount such that the calculated porosity of the insulating layer is 30% by volume. A varnish was prepared. Using this varnish, using a vertical coating equipment, after immersing a square conductor with a cross section of 2 mm x 2 mm, a die having an opening similar to the conductor is passed at a speed of 6 m / min and baked. It was passed through a furnace and baked at 350 ° C. for 1 minute to form an insulating film. This varnish application, die passing and baking were repeated 15 times to produce an insulated wire (No. 2) having a polyimide resin coating as an insulating layer.
  • the insulated wire shown in 3 was manufactured as follows. First, polyimide as a resin for forming an insulating layer was diluted with N-methyl-2-pyrrolidone as a solvent. Next, core-shell particles having an average particle diameter of 3 ⁇ m, in which the core as the thermally decomposable resin-containing particles is PMMA particles and the shell is silicone, are dispersed in an amount such that the calculated porosity of the insulating layer is 30% by volume. A varnish was prepared. Using this varnish, using a vertical coating equipment, after immersing a square conductor with a cross section of 2 mm x 2 mm, a die having an opening similar to the conductor is passed at a speed of 6 m / min and baked.
  • the insulated wire shown in 4 was manufactured as follows. First, polyimide as a resin for forming an insulating layer was diluted with N-methyl-2-pyrrolidone as a solvent. Next, core-shell particles having an average particle diameter of 3 ⁇ m whose core as the thermally decomposable resin-containing particles is PMMA particles and whose shell is silicone are dispersed in an amount such that the calculated porosity of the insulating layer is 55% by volume. A varnish was prepared. Using this varnish, using a vertical coating equipment, after immersing a square conductor with a cross section of 2 mm x 2 mm, a die having an opening similar to the conductor is passed at a speed of 6 m / min and baked.
  • the insulated wire shown in 5 was manufactured as follows. First, polyimide as a resin for forming an insulating layer was diluted with N-methyl-2-pyrrolidone as a solvent. Next, an azo-based thermally expandable microcapsule particle as a pore-forming material was dispersed in an amount such that the calculated porosity of the insulating layer was 30% by volume to prepare a varnish. Using this varnish, using a vertical coating equipment, after immersing a square conductor with a cross section of 2 mm x 2 mm, a die having an opening similar to the conductor is passed at a speed of 6 m / min and baked. It was passed through a furnace and baked at 350 ° C. for 1 minute to form an insulating film. Application of this varnish, passing through a die, and baking were repeated 15 times to produce an insulated wire (No. 5) having a polyimide resin coating as an insulating layer.
  • FIG. 3 is a schematic diagram for explaining a dielectric constant measurement method.
  • a silver sample P was applied to three places on the surface of an insulated wire, and a measurement sample was prepared in which the conductor 1 was exposed by peeling off the insulating layer 2 on one end side of the insulated wire.
  • the coating length in the longitudinal direction of the insulated wire of the silver paste P applied to the three places on the surface of the insulated wire was 10 mm, 100 mm, and 10 mm in order along the longitudinal direction.
  • the two silver pastes P applied with a length of 10 mm are grounded, and the electrostatic capacity between the silver paste P with a length of 100 mm applied between these two silver pastes and the exposed conductor 1 is determined. Measured with LCR meter M.

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Abstract

This insulated electric cable is an insulated electric cable comprising a linear conductor and an insulating layer coated on the outer peripheral surface of this conductor, wherein the insulating layer contains a plurality of pores, the porosity of the insulating layer falls within the range of 20% by volume to 65% by volume (inclusive), the film thickness of the insulating layer is measured at 8 points on cross sections at 30 locations at 50 cm intervals in the longitudinal direction of the insulating cable, and the variability ratio according to formula (1) calculated from these measurements does not exceed 25%. Formula (1): variability ratio (%)=(4σ/average film thickness)×100 (in formula (1), average film thickness represents an average value of different measurements, and σ represents the standard deviation of the different measurements)

Description

絶縁電線Insulated wire
　本発明は、絶縁電線に関する。本出願は、２０１７年３月３０日出願の日本出願第２０１７－０６９０２８号に基づく優先権を主張し、前記日本出願に記載された全ての記載内容を援用するものである。 The present invention relates to an insulated wire. This application claims priority based on Japanese Patent Application No. 2017-069028 filed on Mar. 30, 2017, and incorporates all the description content described in the above Japanese application.
　適用電圧が高い電気機器、例えば高電圧で使用されるモーター等では、電気機器を構成する絶縁電線に高電圧が印加され、その絶縁層表面で部分放電（コロナ放電）が発生し易くなる。コロナ放電の発生により、局部的な温度上昇、オゾンの発生、イオンの発生等が引き起こされると、早期に絶縁破壊を生じ、絶縁電線ひいては電気機器の寿命が短くなる。このため、適用電圧が高い電気機器に使用される絶縁電線には、優れた電気絶縁性、機械的強度等に加えてコロナ放電開始電圧の向上も求められる。 In an electric device having a high applied voltage, for example, a motor used at a high voltage, a high voltage is applied to an insulated wire constituting the electric device, and partial discharge (corona discharge) is likely to occur on the surface of the insulating layer. When a local temperature rise, ozone generation, ion generation, or the like is caused by the generation of corona discharge, dielectric breakdown occurs at an early stage, and the life of the insulated wire and thus the electrical equipment is shortened. For this reason, in addition to excellent electrical insulation properties, mechanical strength, etc., an insulated wire used for an electric device having a high applied voltage is required to improve the corona discharge start voltage.
　コロナ放電開始電圧を上げる工夫としては、絶縁層の低誘電率化が有効であり、この低誘電率化の方法の１つとして、絶縁層中に気孔を形成する方法がある。 As a device for increasing the corona discharge starting voltage, it is effective to lower the dielectric constant of the insulating layer. As one of the methods for reducing the dielectric constant, there is a method of forming pores in the insulating layer.
　絶縁層中に気孔を形成する方法として、アゾビスイソブチロニトリル等の発泡剤又は熱膨張性マイクロカプセルを用いる方法（特開平５－２０９２８号公報及び特開平８－７７８４９号公報参照）、及び熱硬化性樹脂の溶剤とこの溶剤よりも沸点が高い溶剤と気泡形成剤との混合溶剤を用いる方法が提案されている。 As a method for forming pores in the insulating layer, a method using a foaming agent such as azobisisobutyronitrile or a heat-expandable microcapsule (see Japanese Patent Laid-Open Nos. 5-20928 and 8-77849), and A method using a solvent of a thermosetting resin, a mixed solvent of a solvent having a boiling point higher than that of the solvent and a bubble forming agent has been proposed.
特開平５－２０９２８号公報Japanese Patent Laid-Open No. 5-20928 特開平８－７７８４９号公報JP-A-8-77849
　本発明の一態様に係る絶縁電線は、線状の導体と、この導体の外周面に被覆される絶縁層とを備える絶縁電線であって、上記絶縁層が複数の気孔を含み、上記絶縁層の気孔率が２０体積％以上６５体積％以下であり、上記絶縁電線の長手方向に５０ｃｍ間隔で３０個所の断面で、各断面毎に８点の上記絶縁層の膜厚を測定し、これらの測定値から算定される下記式（１）のバラツキ割合が２５％以下である。
　バラツキ割合（％）＝（４σ／平均膜厚）×１００　・・・（１）
（上記式（１）中、平均膜厚は各測定値の平均値を示し、σは各測定値の標準偏差を示す。） An insulated wire according to an aspect of the present invention is an insulated wire including a linear conductor and an insulating layer coated on an outer peripheral surface of the conductor, the insulating layer including a plurality of pores, and the insulating layer The porosity of the insulating wire is 20 volume% or more and 65 volume% or less, and the thickness of the insulating layer at 8 points is measured for each cross section at 30 cross sections at 50 cm intervals in the longitudinal direction of the insulated wire. The variation ratio of the following formula (1) calculated from the measured value is 25% or less.
Variation ratio (%) = (4σ / average film thickness) × 100 (1)
(In the above formula (1), the average film thickness indicates the average value of each measurement value, and σ indicates the standard deviation of each measurement value.)
本発明の実施形態に係る絶縁電線の模式的断面図である。It is a typical sectional view of an insulated wire concerning an embodiment of the present invention. 実施例におけるバラツキ割合の測定方法を説明するための図である。It is a figure for demonstrating the measuring method of the variation ratio in an Example. 実施例における誘電率の測定方法を説明するための模式図である。It is a schematic diagram for demonstrating the measuring method of the dielectric constant in an Example.
［本開示が解決しようとする課題］
　一般に絶縁層の気孔率を上げることにより誘電率を低下させることができる。しかし、上述の従来技術で形成された絶縁層では、発泡剤の発泡倍率の制御が難しいため、又は揮発速度が互いに異なる複数の溶剤を用いているため、気孔率を上げると絶縁層の膜厚が導体の断面の周囲において不均一になる。また、絶縁層の厚みは絶縁電線の絶縁性及び強度に大きな影響を与え、特に絶縁層が薄い部分において絶縁性及び強度が不十分になるおそれがある。さらに、近年、占積率が高く、各種機器の小型化を図ることができることから、断面が略長方形状の平角導体が広く使用されるようになっている。しかし、この平角導体を用いる場合、絶縁層の厚みは特に不均一になり易いため、絶縁電線の絶縁性及び強度が低下し易い。また、絶縁層の厚みが不均一である平角導体を用いると、巻線の状態において、電線同士が接触せず不要な空間が形成され、占積率が低下するおそれがある。 [Problems to be solved by the present disclosure]
In general, the dielectric constant can be lowered by increasing the porosity of the insulating layer. However, in the insulating layer formed by the above-described conventional technology, it is difficult to control the foaming ratio of the foaming agent, or a plurality of solvents having different volatilization rates are used. Becomes non-uniform around the conductor cross section. Further, the thickness of the insulating layer has a great influence on the insulation and strength of the insulated wire, and there is a possibility that the insulation and strength are insufficient particularly in a portion where the insulating layer is thin. Furthermore, in recent years, since the space factor is high and various devices can be miniaturized, flat conductors having a substantially rectangular cross section have been widely used. However, when this flat conductor is used, the insulating layer thickness tends to be particularly uneven, so that the insulation and strength of the insulated wire are likely to decrease. In addition, when a rectangular conductor having a non-uniform thickness of the insulating layer is used, in the winding state, the wires do not contact each other and an unnecessary space is formed, which may reduce the space factor.
　本発明は以上のような事情に基づいてなされたものであり、絶縁層の低誘電率化を達成しつつ、絶縁性及び強度に優れる絶縁電線を提供することを目的とする。 The present invention has been made based on the above circumstances, and an object thereof is to provide an insulated wire excellent in insulation and strength while achieving a low dielectric constant of an insulating layer.
［本開示の効果］ [Effects of the present disclosure]
　本発明の絶縁電線は、絶縁層の低誘電率化を達成しつつ、絶縁性及び強度に優れる。 The insulated wire of the present invention is excellent in insulation and strength while achieving a low dielectric constant of the insulating layer.
［本発明の実施形態の説明］
　本発明の一態様に係る絶縁電線は、線状の導体と、この導体の外周面に被覆される絶縁層とを備える絶縁電線であって、上記絶縁層が複数の気孔を含み、上記絶縁層の気孔率が２０体積％以上６５体積％以下であり、上記絶縁電線の長手方向に５０ｃｍ間隔で３０個所の断面で、各断面毎に８点の上記絶縁層の膜厚を測定し、これらの測定値から算定される下記式（１）のバラツキ割合が２５％以下である。
　バラツキ割合（％）＝（４σ／平均膜厚）×１００　・・・（１）
（上記式（１）中、平均膜厚は各測定値の平均値を示し、σは各測定値の標準偏差を示す。） [Description of Embodiment of the Present Invention]
An insulated wire according to an aspect of the present invention is an insulated wire including a linear conductor and an insulating layer coated on an outer peripheral surface of the conductor, the insulating layer including a plurality of pores, and the insulating layer The porosity of the insulating wire is 20 volume% or more and 65 volume% or less, and the thickness of the insulating layer at 8 points is measured for each cross section at 30 cross sections at 50 cm intervals in the longitudinal direction of the insulated wire. The variation ratio of the following formula (1) calculated from the measured value is 25% or less.
Variation ratio (%) = (4σ / average film thickness) × 100 (1)
(In the above formula (1), the average film thickness indicates the average value of each measurement value, and σ indicates the standard deviation of each measurement value.)
　当該絶縁電線は、絶縁層に気孔を含み、この絶縁層の気孔率を上記範囲内とすることにより、絶縁層の低誘電率化を達成できる。また、当該絶縁電線は、絶縁層の膜厚のバラツキ割合を上記値以下とし、膜厚の均一性を高めることにより、最低膜厚を小さくすることができ、その結果、コロナ放電開始電圧が向上し、絶縁性に優れ、かつ強度にも優れる。　ここで、「気孔率」とは、絶縁層の気孔を含む体積に対する気孔の容積の百分率を意味する。 The insulated wire includes pores in the insulating layer, and by setting the porosity of the insulating layer within the above range, it is possible to achieve a low dielectric constant of the insulating layer. In addition, the insulated wire can reduce the minimum film thickness by increasing the uniformity of the film thickness by setting the variation rate of the film thickness of the insulating layer to the above value or less, and as a result, the corona discharge starting voltage is improved. In addition, it has excellent insulating properties and excellent strength. Here, “porosity” means the percentage of the volume of the pores with respect to the volume including the pores of the insulating layer.
　上記絶縁層の平均膜厚としては６０μｍ以上が好ましい。このように、絶縁層の平均膜厚を上記値以上とすることにより、当該絶縁電線は、絶縁性及び強度をより向上させることができる。 The average film thickness of the insulating layer is preferably 60 μm or more. Thus, the insulated wire can improve insulation and intensity | strength more by making the average film thickness of an insulating layer more than the said value.
　上記導体が、断面長方形の平角導体であるとよい。一般に絶縁層の膜厚を均一にすることが難しい平角導体の場合でも、絶縁層の低誘電率化を達成でき、かつ絶縁性及び強度に優れる絶縁電線とすることができる。 The conductor is preferably a rectangular conductor having a rectangular cross section. In general, even in the case of a rectangular conductor in which it is difficult to make the thickness of the insulating layer uniform, it is possible to reduce the dielectric constant of the insulating layer and to provide an insulated wire excellent in insulation and strength.
［本発明の実施形態の詳細］
　以下、図面を参照しつつ、本発明の実施形態に係る絶縁電線及び絶縁電線の製造方法を説明する。 [Details of the embodiment of the present invention]
Hereinafter, an insulated wire and a method for manufacturing an insulated wire according to an embodiment of the present invention will be described with reference to the drawings.
［絶縁電線］
　図１の当該絶縁電線は、線状の導体１と、この導体１の外周面に被覆される絶縁層２とを備える。この絶縁層２は、複数の気孔３を含む。 [Insulated wire]
The insulated wire in FIG. 1 includes a linear conductor 1 and an insulating layer 2 that covers the outer peripheral surface of the conductor 1. The insulating layer 2 includes a plurality of pores 3.
＜導体＞
　上記導体１の断面の形状としては、例えば円形状、楕円形状、レーストラック形状、六角形状、三角形状、正方形、長方形等の四角形状などの多角形状などが挙げられる。導体１としては、これらの中で、断面正方形の角導体又は断面長方形の平角導体が好ましい。
　また、導体１は、複数の素線を撚り合わせた撚り線であってもよい。 <Conductor>
Examples of the cross-sectional shape of the conductor 1 include a circular shape, an elliptical shape, a racetrack shape, a hexagonal shape, a triangular shape, a polygonal shape such as a square shape such as a square, and a rectangle. Among these, the conductor 1 is preferably a square conductor with a square cross section or a flat conductor with a rectangular cross section.
The conductor 1 may be a stranded wire obtained by twisting a plurality of strands.
　導体１の材質としては、導電率が高くかつ機械的強度が大きい金属が好ましい。このような金属としては、例えば銅、銅合金、アルミニウム、ニッケル、銀、軟鉄、鋼、ステンレス鋼等が挙げられる。導体１として、これらの金属を線状に形成した材料や、このような線状の材料にさらに別の金属を被覆した多層構造のもの、例えばニッケル被覆銅線、銀被覆銅線、銅被覆アルミニウム線、銅被覆鋼線等を用いることができる。 The material of the conductor 1 is preferably a metal having high electrical conductivity and high mechanical strength. Examples of such metals include copper, copper alloys, aluminum, nickel, silver, soft iron, steel, and stainless steel. As the conductor 1, a material in which these metals are linearly formed, or a multilayer structure in which such a linear material is further coated with another metal, such as nickel-coated copper wire, silver-coated copper wire, copper-coated aluminum Wire, copper-coated steel wire, etc. can be used.
　導体１の平均断面積の下限としては、０．０１ｍｍ２が好ましく、０．１ｍｍ２がより好ましい。一方、導体１の平均断面積の上限としては、２０ｍｍ２が好ましく、５ｍｍ２がより好ましい。導体１の平均断面積が上記下限未満であると、導体１に対する絶縁層２の体積が大きくなり、当該絶縁電線を用いて形成されるコイル等の体積効率が低くなるおそれがある。逆に、導体１の平均断面積が上記上限を超えると、誘電率を十分に低下させるために絶縁層２を厚く形成しなければならず、当該絶縁電線が不必要に大径化するおそれがある。 The lower limit of the average cross-sectional area of the conductor 1, preferably from 0.01 mm 2, 0.1 mm 2 is more preferable. In contrast, the upper limit of the average cross-sectional area of the conductor 1, preferably from 20 mm 2, 5 mm 2 is more preferable. If the average cross-sectional area of the conductor 1 is less than the lower limit, the volume of the insulating layer 2 with respect to the conductor 1 increases, and the volume efficiency of a coil or the like formed using the insulated wire may be reduced. Conversely, if the average cross-sectional area of the conductor 1 exceeds the above upper limit, the insulating layer 2 must be formed thick in order to sufficiently reduce the dielectric constant, and the insulated wire may be unnecessarily increased in diameter. is there.
＜絶縁層＞
　上記絶縁層２は、図１に示すように、複数の気孔３を含む。 <Insulating layer>
The insulating layer 2 includes a plurality of pores 3 as shown in FIG.
　絶縁層２の気孔率の下限としては、２０体積％であり、２５体積％が好ましく、３０体積％がより好ましい。一方、絶縁層２の気孔率の上限としては、６５体積％であり、６０体積％が好ましく、５５体積％がより好ましい。絶縁層２の気孔率が上記下限未満であると、絶縁層２の誘電率が十分に低下せず、コロナ放電開始電圧を十分に向上できないおそれがある。逆に、絶縁層２の気孔率が上記上限を超えると、当該絶縁電線の強度を確保できないおそれがある。絶縁層２の気孔率（体積％）は、絶縁層２についてその外形から算出される見かけの体積Ｖ１に絶縁層２の材質の密度ρ１を乗じて求められる気孔がない場合の質量Ｗ１と、絶縁層２の実際の質量Ｗ２とから、（Ｗ１－Ｗ２）×１００／Ｗ１の式により求められる値である。 The lower limit of the porosity of the insulating layer 2 is 20% by volume, preferably 25% by volume, and more preferably 30% by volume. On the other hand, the upper limit of the porosity of the insulating layer 2 is 65% by volume, preferably 60% by volume, and more preferably 55% by volume. When the porosity of the insulating layer 2 is less than the above lower limit, the dielectric constant of the insulating layer 2 is not sufficiently lowered, and the corona discharge starting voltage may not be sufficiently improved. Conversely, if the porosity of the insulating layer 2 exceeds the above upper limit, the strength of the insulated wire may not be ensured. The porosity (volume%) of the insulating layer 2 is the same as the mass W1 when there is no pore determined by multiplying the apparent volume V1 calculated from the outer shape of the insulating layer 2 by the density ρ1 of the material of the insulating layer 2, and the insulating layer 2 This is a value obtained from the actual mass W2 of the layer 2 by the formula of (W1-W2) × 100 / W1.
　絶縁層２の平均膜厚の下限としては、１０μｍが好ましく、６０μｍがより好ましく、８０μｍがさらに好ましく、１００μｍが特に好ましい。一方、絶縁層２の平均膜厚の上限としては、３００μｍが好ましく、２００μｍがより好ましい。絶縁層２の平均膜厚が上記下限未満であると、絶縁層２に破れが生じ、導体１の絶縁が不十分となるおそれがある。逆に、絶縁層２の平均膜厚が上記上限を超えると、当該絶縁電線を用いて形成されるコイル等の体積効率が低くなるおそれがある。 The lower limit of the average film thickness of the insulating layer 2 is preferably 10 μm, more preferably 60 μm, further preferably 80 μm, and particularly preferably 100 μm. On the other hand, the upper limit of the average film thickness of the insulating layer 2 is preferably 300 μm, and more preferably 200 μm. If the average film thickness of the insulating layer 2 is less than the above lower limit, the insulating layer 2 may be torn and insulation of the conductor 1 may be insufficient. On the contrary, when the average film thickness of the insulating layer 2 exceeds the upper limit, the volume efficiency of a coil or the like formed using the insulated wire may be lowered.
　絶縁層２の膜厚のバラツキ割合の上限としては、２５％であり、２０％が好ましく、１５％がより好ましく、１２％がさらに好ましく、１０％が特に好ましい。一方、絶縁層２の膜厚のバラツキ割合の下限としては、１％が好ましく、５％がより好ましい。絶縁層２の膜厚のバラツキ割合が上記上限を超えると、当該絶縁電線の絶縁性及び強度が不十分となるおそれがある。 The upper limit of the film thickness variation ratio of the insulating layer 2 is 25%, preferably 20%, more preferably 15%, still more preferably 12%, and particularly preferably 10%. On the other hand, the lower limit of the variation ratio of the film thickness of the insulating layer 2 is preferably 1% and more preferably 5%. If the variation ratio of the film thickness of the insulating layer 2 exceeds the above upper limit, the insulation and strength of the insulated wire may be insufficient.
　絶縁層２の膜厚のバラツキ割合は、当該絶縁電線の長手方向に５０ｃｍ間隔で３０個所の断面で、各断面毎に８点の絶縁層の膜厚を測定し、これらの測定値から下記式（１）により算定される。
　バラツキ割合（％）＝（４σ／平均膜厚）×１００　・・・（１）
（上記式（１）中、平均膜厚は各測定値の平均値を示し、σは各測定値の標準偏差を示す。） The variation ratio of the thickness of the insulating layer 2 is determined by measuring the thickness of the insulating layer at 8 points for each cross section at 30 sections at intervals of 50 cm in the longitudinal direction of the insulated wire. Calculated according to (1).
Variation ratio (%) = (4σ / average film thickness) × 100 (1)
(In the above formula (1), the average film thickness indicates the average value of each measurement value, and σ indicates the standard deviation of each measurement value.)
　気孔３の平均径の下限としては、０．１μｍが好ましく、１μｍがより好ましい。一方、上記気孔３の平均径の上限としては、１０μｍが好ましく、８μｍがより好ましい。上記気孔３の平均径が上記下限未満であると、絶縁層２中でのコロナ放電の発生を十分に抑制できないおそれがある。逆に、上記気孔３の平均径が上記上限を超えると、気孔３の分布を均一にし難くなり、誘電率の分布に偏りが生じ易くなるおそれがある。 The lower limit of the average diameter of the pores 3 is preferably 0.1 μm, and more preferably 1 μm. On the other hand, the upper limit of the average diameter of the pores 3 is preferably 10 μm, more preferably 8 μm. When the average diameter of the pores 3 is less than the lower limit, the generation of corona discharge in the insulating layer 2 may not be sufficiently suppressed. Conversely, if the average diameter of the pores 3 exceeds the upper limit, it is difficult to make the distribution of the pores 3 uniform, and there is a risk that the distribution of the dielectric constant is likely to be biased.
　絶縁層２は、絶縁性を有する樹脂組成物、この樹脂組成物中に散在する気孔３で形成される。この絶縁層２は、後述するワニスの導体１外周面への塗布及び焼付により形成される。 The insulating layer 2 is formed of an insulating resin composition and pores 3 scattered in the resin composition. This insulating layer 2 is formed by applying and baking varnish on the outer peripheral surface of the conductor 1 described later.
　絶縁層２を形成する樹脂としては、特に限定されないが、例えばポリビニルホルマール、熱硬化ポリウレタン、熱硬化アクリル、エポキシ、熱硬化ポリエステル、熱硬化ポリエステルイミド、熱硬化ポリエステルアミドイミド、芳香族ポリアミド、熱硬化ポリアミドイミド、熱硬化ポリイミド等の熱硬化性樹脂や、例えばポリエーテルイミド、ポリフェニレンエーテル、ポリエーテルサルフォン、熱可塑性ポリイミド等の熱可塑性樹脂を主成分とする。ここで「主成分」とは、最も含有量の多い成分であり、例えば５０質量％以上含有される成分である。 Although it does not specifically limit as resin which forms the insulating layer 2, For example, polyvinyl formal, thermosetting polyurethane, thermosetting acrylic, epoxy, thermosetting polyester, thermosetting polyester imide, thermosetting polyester amide imide, aromatic polyamide, thermosetting The main component is a thermosetting resin such as polyamideimide or thermosetting polyimide, or a thermoplastic resin such as polyetherimide, polyphenylene ether, polyethersulfone or thermoplastic polyimide. Here, the “main component” is a component having the largest content, for example, a component contained in an amount of 50% by mass or more.
　また、絶縁層２を形成する樹脂組成物に、上記樹脂と共に硬化剤を含有させてもよい。
硬化剤としては、チタン系硬化剤、イソシアネート系化合物、ブロックイソシアネート、尿素やメラミン化合物、アミノ樹脂、メチルテトラヒドロ無水フタル酸等の脂環式酸無水物、脂肪族酸無水物、芳香族酸無水物などが例示される。これらの硬化剤は、使用する樹脂組成物が含有する樹脂の種類に応じて、適宜選択される。例えば、ポリアミドイミド系の場合、硬化剤として、イミダゾール、トリエチルアミン等が好ましく用いられる。 Moreover, you may make the resin composition which forms the insulating layer 2 contain a hardening | curing agent with the said resin.
Curing agents include titanium-based curing agents, isocyanate compounds, blocked isocyanates, urea and melamine compounds, amino resins, alicyclic acid anhydrides such as methyltetrahydrophthalic anhydride, aliphatic acid anhydrides, and aromatic acid anhydrides. Etc. are exemplified. These curing agents are appropriately selected according to the type of resin contained in the resin composition to be used. For example, in the case of polyamideimide, imidazole, triethylamine and the like are preferably used as the curing agent.
　なお、上記チタン系硬化剤としては、テトラプロピルチタネート、テトライソプロピルチタネート、テトラメチルチタネート、テトラブチルチタネート、テトラヘキシルチタネート等が例示される。上記イソシアネート系化合物としては、トリレンジイソシアネート（ＴＤＩ）、ジフェニルメタンジイソシアネート（ＭＤＩ）、ｐ－フェニレンジイソシアネート、ナフタレンジイソシアネート等の芳香族ジイソシアネート、ヘキサメチレンジイソシアネート（ＨＤＩ）、２，２，４－トリメチルヘキサンジイソシアネート、リジンジイソシアネート等の炭素数３～１２の脂肪族ジイソシアネート、１，４－シクロヘキサンジイソシアネート（ＣＤＩ）、イソホロンジイソシアネート（ＩＰＤＩ）、４，４’－ジシクロヘキシルメタンジイソシアネート（水添ＭＤＩ）、メチルシクロヘキサンジイソシアネート、イソプロピリデンジシクロヘキシル－４，４’－ジイソシアネート、１，３－ジイソシアナトメチルシクロヘキサン（水添ＸＤＩ）、水添ＴＤＩ、２，５－ビス（イソシアナトメチル）－ビシクロ［２．２．１］ヘプタン、２，６－ビス（イソシアナトメチル）－ビシクロ［２．２．１］ヘプタン等の炭素数５～１８の脂環式イソシアネート、キシリレンジイソシアネート（ＸＤＩ）、テトラメチルキシリレンジイソシアネート（ＴＭＸＤＩ）等の芳香環を有する脂肪族ジイソシアネート、これらの変性物などが例示される。上記ブロックイソシアネートとしては、ジフェニルメタン－４，４’－ジイソシアネート（ＭＤＩ）、ジフェニルメタン－３，３’－ジイソシアネート、ジフェニルメタン－３，４’－ジイソシアネート、ジフェニルエーテル－４，４’－ジイソシアネート、ベンゾフェノン－４，４’－ジイソシアネート、ジフェニルスルホン－４，４’－ジイソシアネート、トリレン－２，４－ジイソシアネート、トリレン－２，６－ジイソシアネート、ナフチレン－１，５－ジイソシアネート、ｍ－キシリレンジイソシアネート、ｐ－キシリレンジイソシアネート等のイソシアネート基にジメチルピラゾール等のブロック剤が付加した化合物などが例示される。上記メラミン化合物としては、メチル化メラミン、ブチル化メラミン、メチロール化メラミン、ブチロール化メラミン等が例示される。 In addition, examples of the titanium-based curing agent include tetrapropyl titanate, tetraisopropyl titanate, tetramethyl titanate, tetrabutyl titanate, and tetrahexyl titanate. Examples of the isocyanate compounds include aromatic diisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexane diisocyanate, C3-C12 aliphatic diisocyanate such as lysine diisocyanate, 1,4-cyclohexane diisocyanate (CDI), isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), methylcyclohexane diisocyanate, isopropylidene Dicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane (hydrogenated XDI , Hydrogenated TDI, 2,5-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, 2,6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane, etc. Examples thereof include aliphatic diisocyanates having an aromatic ring such as 5-18 alicyclic isocyanate, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and modified products thereof. Examples of the blocked isocyanate include diphenylmethane-4,4′-diisocyanate (MDI), diphenylmethane-3,3′-diisocyanate, diphenylmethane-3,4′-diisocyanate, diphenylether-4,4′-diisocyanate, and benzophenone-4,4. '-Diisocyanate, diphenylsulfone-4,4'-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, naphthylene-1,5-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, etc. Examples thereof include compounds in which a blocking agent such as dimethylpyrazole is added to the isocyanate group. Examples of the melamine compound include methylated melamine, butylated melamine, methylolated melamine, and butyrololized melamine.
［絶縁電線の製造方法］
　次に、当該絶縁電線の製造方法について説明する。当該絶縁電線の製造方法は、絶縁層２を形成する樹脂と、この樹脂の焼付温度よりも低い温度で熱分解する熱分解性樹脂を含む粒子（熱分解性樹脂含有粒子）とを希釈しワニスを調製する工程（ワニス調製工程）、導体１の外周面へ上記ワニスを塗布する工程（ワニス塗布工程）、及び加熱により上記熱分解性樹脂含有粒子中の熱分解性樹脂を除去する工程（加熱工程）を備える。 [Insulated wire manufacturing method]
Next, a method for manufacturing the insulated wire will be described. The method of manufacturing the insulated wire includes diluting a resin that forms the insulating layer 2 and particles (thermally decomposable resin-containing particles) containing a thermally decomposable resin that thermally decomposes at a temperature lower than the baking temperature of the resin. (Varnish preparation process), the process of applying the varnish to the outer peripheral surface of the conductor 1 (varnish application process), and the process of removing the thermally decomposable resin in the thermally decomposable resin-containing particles by heating (heating) Step).
＜ワニス調製工程＞
　上記ワニス調製工程において、絶縁層２を形成する樹脂及び熱分解性樹脂含有粒子を溶剤で希釈してワニスを調製する。 <Varnish preparation process>
In the varnish preparation step, the resin forming the insulating layer 2 and the thermally decomposable resin-containing particles are diluted with a solvent to prepare a varnish.
　上記熱分解性樹脂含有粒子が含む熱分解性樹脂としては、上記絶縁層２を形成する樹脂の焼付温度よりも低い熱分解温度を有する樹脂であれば特に限定されない。絶縁層２を形成する樹脂の焼付温度は、樹脂の種類に応じて適宜設定されるが、通常２００℃以上３５０℃以下程度である。従って、上記熱分解性樹脂の熱分解温度の下限としては、２００℃が好ましく、上限としては３００℃が好ましい。ここで、熱分解温度とは、窒素雰囲気下で室温から１０℃／分で昇温し、質量減少率が５０％となるときの温度を意味する。熱分解温度は、例えば熱重量測定－示差熱分析装置（エスアイアイ・ナノテクノロジー社の「ＴＧ／ＤＴＡ」）を用いて熱重量を測定することにより求めることができる。 The heat decomposable resin contained in the heat decomposable resin-containing particles is not particularly limited as long as the resin has a heat decomposition temperature lower than the baking temperature of the resin forming the insulating layer 2. The baking temperature of the resin forming the insulating layer 2 is appropriately set according to the type of the resin, but is usually about 200 ° C. or higher and 350 ° C. or lower. Therefore, 200 degreeC is preferable as a minimum of the thermal decomposition temperature of the said thermally decomposable resin, and 300 degreeC is preferable as an upper limit. Here, the thermal decomposition temperature means a temperature at which the temperature is increased from room temperature to 10 ° C./min in a nitrogen atmosphere and the mass reduction rate becomes 50%. The thermal decomposition temperature can be determined, for example, by measuring the thermogravimetry using a thermogravimetry-differential thermal analyzer (“TG / DTA” manufactured by SII Nano Technology).
　上記熱分解性樹脂としては、特に限定されないが、例えばポリエチレングリコール、ポリプロピレングリコール等の片方、両方の末端又は一部をアルキル化、（メタ）アクリレート化又はエポキシ化した化合物、ポリ（メタ）アクリル酸メチル、ポリ（メタ）アクリル酸エチル、ポリ（メタ）アクリル酸プロピル、ポリ（メタ）アクリル酸ブチル等の（メタ）アクリル酸の炭素数１以上６以下のアルキルエステル重合体、ウレタンオリゴマー、ウレタンポリマー、ウレタン（メタ）アクリレート、エポキシ（メタ）アクリレート、ε－カプロラクトン（メタ）アクリレート等の変性（メタ）アクリレートの重合物、ポリ（メタ）アクリル酸、これらの架橋物、ポリスチレン、架橋ポリスチレン等が挙げられる。
これらのうち、（メタ）アクリル系重合体の架橋物が好ましく、架橋ポリ（メタ）アクリレートがより好ましい。また、上記熱分解性樹脂は、上記絶縁層２を形成する樹脂の海相に微小粒子の島相となって均等分布できることが、独立気孔を形成できる点で好ましい。
従って、上記熱分解性樹脂としては、上記絶縁層２を形成する樹脂との相溶性に優れると共に、球状にまとまることができる樹脂であることが好ましく、具体的には架橋樹脂が好ましい。 The thermally decomposable resin is not particularly limited. For example, one of polyethylene glycol and polypropylene glycol, a compound obtained by alkylating, (meth) acrylated or epoxidizing both ends or a part thereof, poly (meth) acrylic acid C1-C6 alkyl ester polymers, urethane oligomers, urethane polymers of (meth) acrylic acid such as methyl, poly (meth) ethyl acrylate, poly (meth) acrylic acid propyl, poly (meth) acrylic acid butyl , Polymers of modified (meth) acrylates such as urethane (meth) acrylate, epoxy (meth) acrylate, ε-caprolactone (meth) acrylate, poly (meth) acrylic acid, cross-linked products thereof, polystyrene, cross-linked polystyrene, etc. It is done.
Among these, a crosslinked product of a (meth) acrylic polymer is preferable, and a crosslinked poly (meth) acrylate is more preferable. In addition, it is preferable that the thermally decomposable resin can be evenly distributed as an island phase of fine particles in the sea phase of the resin forming the insulating layer 2 in that independent pores can be formed.
Therefore, the thermally decomposable resin is preferably a resin that is excellent in compatibility with the resin forming the insulating layer 2 and can be collected into a spherical shape, and specifically, a crosslinked resin.
　上記架橋ポリ（メタ）アクリル系重合体は、例えば（メタ）アクリル系モノマーと多官能性モノマーとを乳化重合、懸濁重合、溶液重合等により重合することで得られる。 The above-mentioned crosslinked poly (meth) acrylic polymer can be obtained by polymerizing, for example, a (meth) acrylic monomer and a polyfunctional monomer by emulsion polymerization, suspension polymerization, solution polymerization or the like.
　ここで、（メタ）アクリル系モノマーとしては、アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ－ブチル、アクリル酸イソブチル、アクリル酸ｔ－ブチル、アクリル酸ドデシル、アクリル酸ステアリル、アクリル酸２－エチルヘキシル、アクリル酸テトラヒドロフルフリル、アクリル酸ジエチルアミノエチル、メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸プロピル、メタクリル酸ｎ－ブチル、メタクリル酸イソブチル、メタクリル酸ｔ－ブチル、メタクリル酸ｎ－オクチル、メタクリル酸ドデシル、メタクリル酸２－エチルヘキシル、メタクリル酸ステアリル、メタクリル酸ジエチルアミノエチル等が挙げられる。 Here, as the (meth) acrylic monomer, acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, dodecyl acrylate, stearyl acrylate, acrylic acid 2 -Ethylhexyl, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate , Dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, diethylaminoethyl methacrylate and the like.
　また、多官能性モノマーとしては、ジビニルベンゼン、エチレングリコールジ（メタ）アクリレート、トリメチロールプロパントリアクリレート等が挙げられる。 Further, examples of the polyfunctional monomer include divinylbenzene, ethylene glycol di (meth) acrylate, trimethylolpropane triacrylate and the like.
　なお、架橋ポリ（メタ）アクリル系重合体の構成モノマーとしては、（メタ）アクリル系モノマー及び多官能性モノマー以外に他のモノマーを使用してもよい。他のモノマーとしては、エチレングリコールモノ（メタ）アクリレート、ポリエチレングリコールモノ（メタ）アクリレート等の（メタ）アクリル酸のグリコールエステル類、メチルビニルエーテル、エチルビニルエーテル等のアルキルビニルエーテル類、酢酸ビニル、酪酸ビニル等のビニルエステル類、Ｎ－メチルアクリルアミド、Ｎ－エチルアクリルアミド、Ｎ－メチルメタクリルアミド、Ｎ－エチルメタクリルアミド等のＮ－アルキル置換（メタ）アクリルアミド類、アクリロニトリル、メタアクリロニトリル等のニトリル類、スチレン、ｐ－メチルスチレン、ｐ－クロロスチレン、クロロメチルスチレン、α－メチルスチレン等のスチレン系単量体などが挙げられる。 In addition to the (meth) acrylic monomer and multifunctional monomer, other monomers may be used as the constituent monomer of the crosslinked poly (meth) acrylic polymer. Other monomers include glycol esters of (meth) acrylic acid such as ethylene glycol mono (meth) acrylate and polyethylene glycol mono (meth) acrylate, alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, vinyl acetate and vinyl butyrate Vinyl esters, N-alkyl substituted (meth) acrylamides such as N-methylacrylamide, N-ethylacrylamide, N-methylmethacrylamide and N-ethylmethacrylamide, nitriles such as acrylonitrile and methacrylonitrile, styrene, p -Styrene monomers such as methylstyrene, p-chlorostyrene, chloromethylstyrene, α-methylstyrene, and the like.
　上記熱分解性樹脂含有粒子は球状であることが好ましい。上記熱分解性樹脂含有粒子の平均粒子径の下限としては、０．１μｍが好ましく、０．５μｍがより好ましく、１μｍがさらに好ましい。一方、上記熱分解性樹脂含有粒子の平均粒子径の上限としては、１００μｍが好ましく、５０μｍがより好ましく、３０μｍがさらに好ましく、１０μｍが特に好ましい。上記熱分解性樹脂含有粒子は絶縁層２を形成する樹脂の焼付け時に熱分解して存在していた部分に気孔を形成する。そのため、上記熱分解性樹脂含有粒子の平均粒子径が上記下限未満であると、絶縁層２に気孔が形成され難くなるおそれがある。逆に、上記熱分解性樹脂含有粒子の平均粒子径が上記上限を超えると、絶縁層２表面に凹凸が生じ易くなるおそれがある。ここで、上記熱分解性樹脂含有粒子の平均粒子径とは、レーザー回折式粒度分布測定装置で測定した粒度分布において、最も高い含有割合を示す粒径を意味する。 The heat-decomposable resin-containing particles are preferably spherical. The lower limit of the average particle size of the thermally decomposable resin-containing particles is preferably 0.1 μm, more preferably 0.5 μm, and even more preferably 1 μm. On the other hand, the upper limit of the average particle size of the thermally decomposable resin-containing particles is preferably 100 μm, more preferably 50 μm, further preferably 30 μm, and particularly preferably 10 μm. The thermally decomposable resin-containing particles form pores in portions where they were thermally decomposed when the resin forming the insulating layer 2 was baked. Therefore, when the average particle diameter of the thermally decomposable resin-containing particles is less than the lower limit, it is difficult to form pores in the insulating layer 2. Conversely, if the average particle size of the thermally decomposable resin-containing particles exceeds the above upper limit, the surface of the insulating layer 2 may be easily uneven. Here, the average particle size of the thermally decomposable resin-containing particles means a particle size showing the highest content ratio in the particle size distribution measured with a laser diffraction particle size distribution measuring device.
　上記ワニスにおける熱分解性樹脂の含有量の下限としては、絶縁層２を形成する樹脂１００質量部に対して、５質量部が好ましく、１０質量部がより好ましく、１５質量部がさらに好ましい。一方、上記ワニスにおける熱分解性樹脂の含有量の上限としては、絶縁層２を形成する樹脂１００質量部に対して、３５０質量部が好ましく、１５０質量部がより好ましく、９０質量部がさらに好ましい。上記熱分解性樹脂の含有量が上記下限未満であると、絶縁層２の誘電率を十分に低下できないおそれがある。逆に、上記熱分解性樹脂の含有量が上記上限を超えると、当該絶縁電線が十分な強度を確保できないおそれがある。 The lower limit of the content of the thermally decomposable resin in the varnish is preferably 5 parts by mass, more preferably 10 parts by mass, and even more preferably 15 parts by mass with respect to 100 parts by mass of the resin forming the insulating layer 2. On the other hand, the upper limit of the content of the thermally decomposable resin in the varnish is preferably 350 parts by weight, more preferably 150 parts by weight, and still more preferably 90 parts by weight with respect to 100 parts by weight of the resin forming the insulating layer 2. . If the content of the thermally decomposable resin is less than the lower limit, the dielectric constant of the insulating layer 2 may not be sufficiently reduced. Conversely, if the content of the thermally decomposable resin exceeds the upper limit, the insulated wire may not be able to ensure sufficient strength.
　希釈用溶剤としては、絶縁ワニスに従来より用いられている公知の有機溶剤を用いることができる。具体的には、例えばＮ－メチル－２－ピロリドン、Ｎ，Ｎ－ジメチルアセトアミド、Ｎ，Ｎ－ジメチルホルムアミド、ジメチルスルホキシド、テトラメチル尿素、ヘキサエチルリン酸トリアミド、γ－ブチロラクトン等の極性有機溶媒をはじめ、アセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノン等のケトン類、酢酸メチル、酢酸エチル、酢酸ブチル、シュウ酸ジエチル等のエステル類、ジエチルエーテル、エチレングリコールジメチルエーテル、ジエチレングリコールモノメチルエーテル、エチレングリコールモノブチルエーテル（ブチルセロソルブ）、ジエチレングリコールジメチルエーテル、テトラヒドロフラン等のエーテル類、ヘキサン、ヘプタン、ベンゼン、トルエン、キシレン等の炭化水素類、ジクロロメタン、クロロベンゼン等のハロゲン化炭化水素類、クレゾール、クロルフェノール等のフェノール類、ピリジン等の第三級アミン類などが挙げられ、これらの有機溶媒はそれぞれ単独であるいは２種以上を混合して用いられる。 As the diluting solvent, a known organic solvent conventionally used for insulating varnish can be used. Specifically, polar organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, tetramethylurea, hexaethylphosphoric triamide, γ-butyrolactone and the like are used. First, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, esters such as methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether (butyl cellosolve) ), Ethers such as diethylene glycol dimethyl ether and tetrahydrofuran, hydrocarbons such as hexane, heptane, benzene, toluene and xylene, dichloro Examples include halogenated hydrocarbons such as methane and chlorobenzene, phenols such as cresol and chlorophenol, and tertiary amines such as pyridine. These organic solvents are used alone or in admixture of two or more. It is done.
　なお、これらの有機溶剤により希釈して調製したワニスの樹脂固形分濃度の下限としては、１５質量％が好ましく、２２質量％がより好ましい。一方、上記ワニスの樹脂固形分濃度の上限としては、５０質量％が好ましく、２８質量％がより好ましい。上記ワニスの樹脂固形分濃度が上記下限未満であると、ワニスを塗布する際の１回の塗布量が少なくなるため、所望の厚みの絶縁層２を形成するためのワニス塗布工程の繰り返し回数が多くなり、ワニス塗布工程の時間が長くなるおそれがある。逆に、上記ワニスの樹脂固形分濃度が上記上限を超える場合、ワニスが増粘することにより、ワニスの保存安定性が悪化するおそれや、ワニス塗布時の付着性が悪化するおそれがある。 In addition, as a minimum of the resin solid content density | concentration of the varnish prepared by diluting with these organic solvents, 15 mass% is preferable and 22 mass% is more preferable. On the other hand, the upper limit of the resin solid content concentration of the varnish is preferably 50% by mass, and more preferably 28% by mass. When the resin solid content concentration of the varnish is less than the lower limit, the amount of application at one time when applying the varnish decreases, and therefore the number of repetitions of the varnish application step for forming the insulating layer 2 having a desired thickness is reduced. There is a risk that the time for the varnish application process will be increased. On the other hand, when the resin solid content concentration of the varnish exceeds the above upper limit, the varnish thickens, so that the storage stability of the varnish may be deteriorated and the adhesion at the time of varnish application may be deteriorated.
　上記熱分解性樹脂含有粒子としては、上記熱分解性樹脂のみからなる粒子であってもよいが、上記熱分解性樹脂を主成分とするコアと、上記熱分解性樹脂の熱分解温度よりも高い熱分解温度を有する樹脂を主成分とするシェルとを有するコアシェル粒子が好ましい。 The heat-decomposable resin-containing particles may be particles composed only of the heat-decomposable resin, but a core having the heat-decomposable resin as a main component and a thermal decomposition temperature of the heat-decomposable resin. Core-shell particles having a shell mainly composed of a resin having a high thermal decomposition temperature are preferred.
　上記シェルの主成分の樹脂としては、誘電率が低く、耐熱性が高いものが好ましい。シェルの主成分の樹脂としては、例えばポリスチレン、シリコーン、フッ素樹脂、ポリイミド等が挙げられる。これらの中でも、シェルに弾性を付与すると共に絶縁性及び耐熱性を向上させ易い点において、シリコーンが好ましい。ここで、「フッ素樹脂」とは、高分子鎖の繰り返し単位を構成する炭素原子に結合する水素原子の少なくとも１つが、フッ素原子又はフッ素原子を有する有機基（以下「フッ素原子含有基」ともいう）で置換されたものをいう。フッ素原子含有基は、直鎖状又は分岐状の有機基中の水素原子の少なくとも１つがフッ素原子で置換されたものであり、例えばフルオロアルキル基、フルオロアルコキシ基、フルオロポリエーテル基等を挙げることができる。なお、絶縁性を損なわない範囲でシェルに金属が含まれてもよい。 As the main component resin of the shell, a resin having a low dielectric constant and high heat resistance is preferable. Examples of the main resin of the shell include polystyrene, silicone, fluororesin, and polyimide. Among these, silicone is preferable in that elasticity is imparted to the shell and insulation and heat resistance are easily improved. Here, the “fluororesin” is a fluorine atom or an organic group in which at least one hydrogen atom bonded to a carbon atom constituting the repeating unit of the polymer chain has a fluorine atom (hereinafter also referred to as “fluorine atom-containing group”). ). The fluorine atom-containing group is a group in which at least one hydrogen atom in a linear or branched organic group is substituted with a fluorine atom, and examples thereof include a fluoroalkyl group, a fluoroalkoxy group, and a fluoropolyether group. Can do. In addition, a metal may be contained in a shell in the range which does not impair insulation.
　なお、シェルの主成分の樹脂は、上記絶縁層２を形成する樹脂と同種のものを用いてもよく、異なるものを用いてもよい。例えばシェルの主成分の樹脂として、上記絶縁層２を形成する樹脂と同種のものを用いた場合でも、上記熱分解性樹脂より熱分解温度が高いので、熱分解性樹脂がガス化してもシェルの主成分の樹脂は熱分解し難いため、気孔３の連通抑制効果が得られる。このようなワニスで形成された当該絶縁電線は、電子顕微鏡で観察してもシェルの存在を確認できない場合がある。一方、シェルの主成分の樹脂として上記絶縁層２を形成する樹脂と異なるものを用いることにより、シェルを上記絶縁層２と一体化され難くできるので、上記絶縁層２を形成する樹脂と同種の樹脂を用いる場合に比べて、気孔３の連通抑制効果が得易くなる。 In addition, the same kind of resin as the resin forming the insulating layer 2 may be used as the main resin of the shell, or a different one may be used. For example, even when the same type of resin as the resin forming the insulating layer 2 is used as the main component resin of the shell, the thermal decomposition temperature is higher than that of the thermally decomposable resin. Since the main component resin is difficult to be thermally decomposed, the effect of suppressing the communication of the pores 3 can be obtained. The insulated wire formed of such a varnish may not be able to confirm the presence of a shell even when observed with an electron microscope. On the other hand, since the shell can be made difficult to be integrated with the insulating layer 2 by using a resin different from the resin forming the insulating layer 2 as the main resin of the shell, the same kind of resin as the resin forming the insulating layer 2 can be used. Compared to the case of using a resin, the effect of suppressing the communication of the pores 3 is easily obtained.
　シェルの平均厚みの下限としては、特に制限はないが、例えば０．０１μｍが好ましく、０．０２μｍがより好ましい。一方、シェルの平均厚みの上限としては、０．５μｍが好ましく、０．４μｍがより好ましい。シェルの平均厚みが上記下限未満であると、気孔３の連通抑制効果が十分に得られないおそれがある。逆に、シェルの平均厚みが上記上限を超えると、気孔３の体積が小さくなり過ぎるため、絶縁層２の気孔率を所定以上に高められないおそれがある。なお、シェルは、１層で形成されてもよいし、複数の層で形成されてもよい。シェルが複数の層で形成される場合、複数の層の合計厚みの平均が、上記厚みの範囲内であればよい。 Although there is no restriction | limiting in particular as a minimum of the average thickness of a shell, For example, 0.01 micrometer is preferable and 0.02 micrometer is more preferable. On the other hand, the upper limit of the average thickness of the shell is preferably 0.5 μm, and more preferably 0.4 μm. If the average thickness of the shell is less than the above lower limit, the effect of suppressing the communication of the pores 3 may not be sufficiently obtained. On the contrary, if the average thickness of the shell exceeds the above upper limit, the volume of the pores 3 becomes too small, so that the porosity of the insulating layer 2 may not be increased beyond a predetermined level. Note that the shell may be formed of one layer or a plurality of layers. When the shell is formed of a plurality of layers, the average of the total thickness of the plurality of layers may be within the range of the thickness.
　上記熱分解性樹脂含有粒子のＣＶ値の上限としては、３０％が好ましく、２０％がより好ましい。このように、ＣＶ値が上記上限以下の熱分解性樹脂含有粒子を用いることで、気孔サイズの違いで生じる気孔部分での電荷集中による絶縁性低下や加工応力の集中による絶縁層２の強度低下を抑制できる。なお、熱分解性樹脂含有粒子のＣＶ値の下限としては、特に限定されないが、例えば１％である。ここで、「ＣＶ値」とは、ＪＩＳ－Ｚ８８２５（２０１３）に規定される変動変数を意味する。 The upper limit of the CV value of the thermally decomposable resin-containing particles is preferably 30%, more preferably 20%. Thus, by using thermally decomposable resin-containing particles having a CV value equal to or lower than the above upper limit, the insulating layer 2 is deteriorated due to the concentration of electric charges in the pores caused by the difference in pore size, and the strength of the insulating layer 2 is decreased due to the concentration of processing stress. Can be suppressed. In addition, although it does not specifically limit as a minimum of CV value of a thermally decomposable resin containing particle | grain, For example, it is 1%. Here, the “CV value” means a variable defined in JIS-Z8825 (2013).
＜ワニス塗布工程＞
　上記ワニス塗布工程において、上記ワニス調製工程で調製したワニスを導体１の外周面に塗布した後、塗布ダイスにより導体１のワニスの塗布量の調節及び塗布されたワニス面の平滑化を行う。 <Varnish application process>
In the varnish application step, after the varnish prepared in the varnish preparation step is applied to the outer peripheral surface of the conductor 1, the application amount of the varnish of the conductor 1 is adjusted and the applied varnish surface is smoothed by an application die.
　上記塗布ダイスは開口部を有し、ワニスを塗布した導体１がこの開口部を通過することで余分なワニスが除去され、ワニスの塗布量が調整される。これにより、当該絶縁電線は、絶縁層２の厚みがより均一になり、当該絶縁電線の絶縁性及び強度がより向上する。 The coating die has an opening, and when the conductor 1 coated with the varnish passes through the opening, the excess varnish is removed and the coating amount of the varnish is adjusted. Thereby, as for the said insulated wire, the thickness of the insulating layer 2 becomes more uniform, and the insulation and the intensity | strength of the said insulated wire are improved more.
＜加熱工程＞
　次に、上記加熱工程において、上記ワニスが塗布された導体１を焼付炉に通して、ワニスを焼付けることで、導体１表面に絶縁層２を形成する。焼付の際、ワニスに含まれる熱分解性樹脂含有粒子の熱分解性樹脂が熱分解によりガス化して除去される。その結果、熱分解性樹脂含有粒子に由来する気孔３が絶縁層２内に形成される。このように、上記加熱工程は、ワニスの焼付工程を兼ねる。 <Heating process>
Next, in the heating step, the conductor 1 coated with the varnish is passed through a baking furnace, and the varnish is baked to form the insulating layer 2 on the surface of the conductor 1. During baking, the thermally decomposable resin of the thermally decomposable resin-containing particles contained in the varnish is gasified and removed by thermal decomposition. As a result, pores 3 derived from the thermally decomposable resin-containing particles are formed in the insulating layer 2. Thus, the heating process also serves as a varnish baking process.
［利点］
　当該絶縁電線は、絶縁層２が気孔３を含み、この絶縁層２の気孔率が上記範囲内であることにより、絶縁層２の低誘電率化を達成できる。また、当該絶縁電線は、絶縁層の膜厚のバラツキ割合を上記値以下として、膜厚の均一性に優れることにより、最低膜厚を小さくすることができ、その結果、コロナ放電開始電圧が向上し、絶縁性に優れ、かつ強度にも優れる。 [advantage]
In the insulated wire, the insulating layer 2 includes the pores 3 and the porosity of the insulating layer 2 is within the above range, whereby the dielectric constant of the insulating layer 2 can be reduced. In addition, the insulated wire can reduce the minimum film thickness by reducing the variation ratio of the film thickness of the insulating layer to the above value or less, thereby improving the corona discharge start voltage. In addition, it has excellent insulating properties and excellent strength.
［その他の実施形態］
　今回開示された実施の形態は全ての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は、上記実施形態の構成に限定されるものではなく、特許請求の範囲によって示され、特許請求の範囲と均等の意味及び範囲内での全ての変更が含まれることが意図される。 [Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The
　上記実施形態においては、１層の絶縁層が導体の外周面に積層される絶縁電線について説明したが、複数の絶縁層が導体の外周面に積層される絶縁電線としてもよい。つまり、図１の導体１と気孔３を含む絶縁層２との間に１又は複数の絶縁層が積層されていてもよいし、図１の気孔３を含む絶縁層２の外周面に１又は複数の絶縁層が積層されてもよいし、図１の気孔３を含む絶縁層２の外周面及び内周面の両方に１又は複数の絶縁層が積層されていてもよい。 In the above embodiment, the insulated wire in which one insulating layer is laminated on the outer peripheral surface of the conductor has been described, but an insulated electric wire in which a plurality of insulating layers are laminated on the outer peripheral surface of the conductor may be used. That is, one or a plurality of insulating layers may be laminated between the conductor 1 in FIG. 1 and the insulating layer 2 including the pores 3, and one or more insulating layers 2 including the pores 3 in FIG. A plurality of insulating layers may be stacked, or one or a plurality of insulating layers may be stacked on both the outer peripheral surface and the inner peripheral surface of the insulating layer 2 including the pores 3 in FIG.
　また、例えば当該絶縁電線において、導体と絶縁層との間にプライマー処理層等のさらなる層が設けられてもよい。プライマー処理層は、層間の密着性を高めるために設けられる層であり、例えば公知の樹脂組成物により形成することができる。 Further, for example, in the insulated wire, an additional layer such as a primer treatment layer may be provided between the conductor and the insulating layer. A primer process layer is a layer provided in order to improve the adhesiveness between layers, for example, can be formed with a well-known resin composition.
　導体と絶縁層との間にプライマー処理層を設ける場合、このプライマー処理層を形成する樹脂組成物は、例えばポリイミド、ポリアミドイミド、ポリエステルイミド、ポリエステル及びフェノキシ樹脂の中の１種又は複数種の樹脂を含むとよい。また、プライマー処理層を形成する樹脂組成物は、密着向上剤等の添加剤を含んでもよい。このような樹脂組成物によって導体と絶縁層との間にプライマー処理層を形成することで、導体と絶縁層との間の密着性を向上することが可能であり、その結果、当該絶縁電線の強度等の特性を効果的に高めることができる。 When providing a primer treatment layer between a conductor and an insulating layer, the resin composition forming this primer treatment layer is, for example, one or more kinds of resins selected from polyimide, polyamideimide, polyesterimide, polyester and phenoxy resin. It is good to include. Moreover, the resin composition forming the primer treatment layer may contain an additive such as an adhesion improver. By forming the primer treatment layer between the conductor and the insulating layer with such a resin composition, it is possible to improve the adhesion between the conductor and the insulating layer. Properties such as strength can be effectively enhanced.
　また、プライマー処理層を形成する樹脂組成物は、上記樹脂と共に他の樹脂、例えばエポキシ樹脂、フェノキシ樹脂、メラミン樹脂等を含んでもよい。また、プライマー処理層を形成する樹脂組成物に含まれる各樹脂として、市販の液状組成物（絶縁ワニス）を使用してもよい。 Further, the resin composition forming the primer treatment layer may contain other resins such as an epoxy resin, a phenoxy resin, a melamine resin and the like together with the above resin. Moreover, you may use a commercially available liquid composition (insulation varnish) as each resin contained in the resin composition which forms a primer process layer.
　プライマー処理層の平均厚みの下限としては、１μｍが好ましく、２μｍがより好ましい。一方、プライマー処理層の平均厚みの上限としては、３０μｍが好ましく、２０μｍがより好ましい。プライマー処理層の平均厚みが上記下限未満であると、導体との十分な密着性を発揮できないおそれがある。逆に、プライマー処理層の平均厚みが上記上限を超えると、当該絶縁電線が不必要に大径化するおそれがある。 The lower limit of the average thickness of the primer treatment layer is preferably 1 μm, and more preferably 2 μm. On the other hand, as an upper limit of the average thickness of a primer process layer, 30 micrometers is preferable and 20 micrometers is more preferable. There exists a possibility that sufficient adhesiveness with a conductor cannot be exhibited as the average thickness of a primer process layer is less than the said minimum. Conversely, if the average thickness of the primer-treated layer exceeds the above upper limit, the insulated wire may be unnecessarily increased in diameter.
　以下、実施例によって本発明をさらに詳細に説明するが、本発明はこれらの実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
［絶縁電線の製造］
　表１のＮｏ．１に示す絶縁電線を以下のようにして製造した。まず、絶縁層を形成する樹脂としてのポリイミドを、溶剤としてのＮ－メチル－２－ピロリドンで希釈した。次に、これに、熱分解性樹脂含有粒子としてのコアがＰＭＭＡ（ポリメタクリル酸メチル樹脂）粒子でシェルがシリコーンの平均粒子径３μｍのコアシェル粒子を、計算値で絶縁層の気孔率が３０体積％となる量分散させてワニスを調製した。このワニスを用い、竪型塗装設備を使用して、断面が２ｍｍ×２ｍｍの角形状の導体を浸漬した後、導体と相似形状の開口部を有するダイスを、速度６ｍ／分で通過させ、焼付炉中を通過させて、３５０℃で１分間焼付を行い、絶縁被膜を形成した。このワニスの塗布、ダイス通過、焼付を１３回繰り返して、ポリイミド樹脂被膜を絶縁層とする絶縁電線（Ｎｏ．１）を製造した。 [Manufacture of insulated wires]
No. in Table 1 The insulated wire shown in 1 was manufactured as follows. First, polyimide as a resin for forming an insulating layer was diluted with N-methyl-2-pyrrolidone as a solvent. Next, the core as the thermally decomposable resin-containing particles is PMMA (polymethyl methacrylate resin) particles and the shell is a core-shell particle having an average particle diameter of 3 μm of silicone, and the calculated porosity is 30 volumes of the insulating layer. The varnish was prepared by dispersing in an amount of%. Using this varnish, using a vertical coating equipment, after immersing a square conductor with a cross section of 2 mm x 2 mm, a die having an opening similar to the conductor is passed at a speed of 6 m / min and baked. It was passed through a furnace and baked at 350 ° C. for 1 minute to form an insulating film. Application of this varnish, passing through a die, and baking were repeated 13 times to produce an insulated wire (No. 1) having a polyimide resin coating as an insulating layer.
　表１のＮｏ．２に示す絶縁電線を以下のようにして製造した。まず、絶縁層を形成する樹脂としてのポリイミドを、溶剤としてのＮ－メチル－２－ピロリドンで希釈した。次に、これに、熱分解性樹脂含有粒子としてのコアがＰＭＭＡ粒子でシェルがシリコーンの平均粒子径３μｍのコアシェル粒子を、計算値で絶縁層の気孔率が３０体積％となる量分散させてワニスを調製した。このワニスを用い、竪型塗装設備を使用して、断面が２ｍｍ×２ｍｍの角形状の導体を浸漬した後、導体と相似形状の開口部を有するダイスを、速度６ｍ／分で通過させ、焼付炉中を通過させて、３５０℃で１分間焼付を行い、絶縁被膜を形成した。このワニスの塗布、ダイス通過、焼付を１５回繰り返して、ポリイミド樹脂被膜を絶縁層とする絶縁電線（Ｎｏ．２）を製造した。 No. in Table 1. The insulated wire shown in 2 was manufactured as follows. First, polyimide as a resin for forming an insulating layer was diluted with N-methyl-2-pyrrolidone as a solvent. Next, core-shell particles having an average particle diameter of 3 μm, in which the core as the thermally decomposable resin-containing particles is PMMA particles and the shell is silicone, are dispersed in an amount such that the calculated porosity of the insulating layer is 30% by volume. A varnish was prepared. Using this varnish, using a vertical coating equipment, after immersing a square conductor with a cross section of 2 mm x 2 mm, a die having an opening similar to the conductor is passed at a speed of 6 m / min and baked. It was passed through a furnace and baked at 350 ° C. for 1 minute to form an insulating film. This varnish application, die passing and baking were repeated 15 times to produce an insulated wire (No. 2) having a polyimide resin coating as an insulating layer.
表１のＮｏ．３に示す絶縁電線を以下のようにして製造した。まず、絶縁層を形成する樹脂としてのポリイミドを、溶剤としてのＮ－メチル－２－ピロリドンで希釈した。次に、これに、熱分解性樹脂含有粒子としてのコアがＰＭＭＡ粒子でシェルがシリコーンの平均粒子径３μｍのコアシェル粒子を、計算値で絶縁層の気孔率が３０体積％となる量分散させてワニスを調製した。このワニスを用い、竪型塗装設備を使用して、断面が２ｍｍ×２ｍｍの角形状の導体を浸漬した後、導体と相似形状の開口部を有するダイスを、速度６ｍ／分で通過させ、焼付炉中を通過させて、３５０℃で１分間焼付を行い、絶縁被膜を形成した。このワニスの塗布、ダイス通過、焼付を３０回繰り返して、ポリイミド樹脂被膜を絶縁層とする絶縁電線（Ｎｏ．３）を製造した。 No. in Table 1 The insulated wire shown in 3 was manufactured as follows. First, polyimide as a resin for forming an insulating layer was diluted with N-methyl-2-pyrrolidone as a solvent. Next, core-shell particles having an average particle diameter of 3 μm, in which the core as the thermally decomposable resin-containing particles is PMMA particles and the shell is silicone, are dispersed in an amount such that the calculated porosity of the insulating layer is 30% by volume. A varnish was prepared. Using this varnish, using a vertical coating equipment, after immersing a square conductor with a cross section of 2 mm x 2 mm, a die having an opening similar to the conductor is passed at a speed of 6 m / min and baked. It was passed through a furnace and baked at 350 ° C. for 1 minute to form an insulating film. Application of this varnish, passing through a die, and baking were repeated 30 times to produce an insulated wire (No. 3) having a polyimide resin coating as an insulating layer.
　表１のＮｏ．４に示す絶縁電線を以下のようにして製造した。まず、絶縁層を形成する樹脂としてのポリイミドを、溶剤としてのＮ－メチル－２－ピロリドンで希釈した。次に、これに、熱分解性樹脂含有粒子としてのコアがＰＭＭＡ粒子でシェルがシリコーンの平均粒子径３μｍのコアシェル粒子を、計算値で絶縁層の気孔率が５５体積％となる量分散させてワニスを調製した。このワニスを用い、竪型塗装設備を使用して、断面が２ｍｍ×２ｍｍの角形状の導体を浸漬した後、導体と相似形状の開口部を有するダイスを、速度６ｍ／分で通過させ、焼付炉中を通過させて、３５０℃で１分間焼付を行い、絶縁被膜を形成した。このワニスの塗布、ダイス通過、焼付を３０回繰り返して、ポリイミド樹脂被膜を絶縁層とする絶縁電線（Ｎｏ．４）を製造した。 No. in Table 1. The insulated wire shown in 4 was manufactured as follows. First, polyimide as a resin for forming an insulating layer was diluted with N-methyl-2-pyrrolidone as a solvent. Next, core-shell particles having an average particle diameter of 3 μm whose core as the thermally decomposable resin-containing particles is PMMA particles and whose shell is silicone are dispersed in an amount such that the calculated porosity of the insulating layer is 55% by volume. A varnish was prepared. Using this varnish, using a vertical coating equipment, after immersing a square conductor with a cross section of 2 mm x 2 mm, a die having an opening similar to the conductor is passed at a speed of 6 m / min and baked. It was passed through a furnace and baked at 350 ° C. for 1 minute to form an insulating film. Application of this varnish, passing through a die, and baking were repeated 30 times to produce an insulated wire (No. 4) having a polyimide resin coating as an insulating layer.
　表１のＮｏ．５に示す絶縁電線を以下のようにして製造した。まず、絶縁層を形成する樹脂としてのポリイミドを、溶剤としてのＮ－メチル－２－ピロリドンで希釈した。次に、これに、気孔形成材としてのアゾ系熱膨張性マイクロカプセル粒子を、計算値で絶縁層の気孔率が３０体積％となる量分散させてワニスを調製した。このワニスを用い、竪型塗装設備を使用して、断面が２ｍｍ×２ｍｍの角形状の導体を浸漬した後、導体と相似形状の開口部を有するダイスを、速度６ｍ／分で通過させ、焼付炉中を通過させて、３５０℃で１分間焼付を行い、絶縁被膜を形成した。このワニスの塗布、ダイス通過、焼付を１５回繰り返して、ポリイミド樹脂被膜を絶縁層とする絶縁電線（Ｎｏ．５）を製造した。 No. in Table 1. The insulated wire shown in 5 was manufactured as follows. First, polyimide as a resin for forming an insulating layer was diluted with N-methyl-2-pyrrolidone as a solvent. Next, an azo-based thermally expandable microcapsule particle as a pore-forming material was dispersed in an amount such that the calculated porosity of the insulating layer was 30% by volume to prepare a varnish. Using this varnish, using a vertical coating equipment, after immersing a square conductor with a cross section of 2 mm x 2 mm, a die having an opening similar to the conductor is passed at a speed of 6 m / min and baked. It was passed through a furnace and baked at 350 ° C. for 1 minute to form an insulating film. Application of this varnish, passing through a die, and baking were repeated 15 times to produce an insulated wire (No. 5) having a polyimide resin coating as an insulating layer.
［評価］
　Ｎｏ．１～Ｎｏ．５の絶縁電線について、絶縁層の気孔率、絶縁層の平均膜厚、標準偏差σ、バラツキ割合、誘電率及びコロナ放電開始電圧（ＰＤＩＶ）を、下記方法に従い評価した。評価結果を表１に合わせて示す。 [Evaluation]
No. 1-No. For the insulated wire No. 5, the porosity of the insulating layer, the average film thickness of the insulating layer, the standard deviation σ, the variation ratio, the dielectric constant, and the corona discharge initiation voltage (PDIV) were evaluated according to the following methods. The evaluation results are shown in Table 1.
（絶縁層の気孔率）
　得られた絶縁電線において、絶縁層を導体から筒状に剥離し、この筒状の絶縁層の質量Ｗ２を測定した。また、筒状の絶縁層の外形から見かけの体積Ｖ１を求め、このＶ１に絶縁層の材質の密度ρ１を乗じて気孔がない場合の質量Ｗ１と算出した。これらＷ１及びＷ２の値から、下記式により気孔率を算出した。
　気孔率＝（Ｗ１－Ｗ２）×１００／Ｗ１　（体積％） (Insulation layer porosity)
In the obtained insulated wire, the insulating layer was peeled from the conductor in a cylindrical shape, and the mass W2 of the cylindrical insulating layer was measured. Further, an apparent volume V1 was obtained from the outer shape of the cylindrical insulating layer, and this mass V1 was calculated by multiplying this V1 by the density ρ1 of the material of the insulating layer and having no pores. From the values of W1 and W2, the porosity was calculated by the following formula.
Porosity = (W1-W2) × 100 / W1 (volume%)
（絶縁層の平均膜厚）
　得られた絶縁電線の断面について、図２の丸数字で示した８点の膜厚を測定した。５０ｃｍ間隔で、Ｎ＝３０の断面について、膜厚を測定し、８点×３０＝２４０点について、測定した膜厚の平均値（算術平均）を求め、これを平均膜厚とした。また、測定値の標準偏差σを求めた。平均膜厚が同程度であっても、４σの値が大きいものは、バラツキが大きいことを意味する。 (Average film thickness of insulating layer)
About the cross section of the obtained insulated wire, the film thickness of 8 points | pieces shown with the circled number of FIG. 2 was measured. The film thickness was measured for a cross section of N = 30 at intervals of 50 cm, and the average value (arithmetic average) of the measured film thickness was obtained for 8 points × 30 = 240 points, which was defined as the average film thickness. Further, the standard deviation σ of the measured value was obtained. Even if the average film thickness is about the same, a large 4σ value means a large variation.
（バラツキ割合）
　上記求めた平均膜厚及び標準偏差σの値を用いて、絶縁層の膜厚のバラツキ割合を下記式により求めた。
　バラツキ割合＝（４σ／平均膜厚）×１００（％）
　バラツキ割合２５％を超えるものは、膜厚の均一性が低く、いわゆるドッグボーン形状の絶縁層が形成され易いといえる。 (Dispersion ratio)
Using the above-obtained average film thickness and standard deviation σ value, the variation ratio of the film thickness of the insulating layer was determined by the following formula.
Variation ratio = (4σ / average film thickness) × 100 (%)
When the variation ratio exceeds 25%, the uniformity of the film thickness is low, and it can be said that a so-called dogbone-shaped insulating layer is easily formed.
（誘電率）
　Ｎｏ．１～Ｎｏ．５の絶縁電線について、絶縁層２の誘電率εを測定した。図３は、誘電率の測定方法を説明するための模式図である。まず、絶縁電線の表面３カ所に銀ペーストＰを塗布すると共に、絶縁電線の一端側の絶縁層２を剥離して導体１を露出させた測定用のサンプルを作製した。ここで、絶縁電線の表面３カ所に塗布した銀ペーストＰの絶縁電線長手方向の塗布長さは、長手方向に沿って順に１０ｍｍ、１００ｍｍ、１０ｍｍとした。長さ１０ｍｍで塗布した２カ所の銀ペーストＰを接地し、これらの２カ所の銀ペーストの間に塗布した長さ１００ｍｍの銀ペーストＰと上記露出させた導体１との間の静電容量をＬＣＲメータＭで測定した。この測定した静電容量及び絶縁層２の平均膜厚から絶縁層２の誘電率εを算出した。なお、上記誘電率εの測定は、１０５℃で１時間加熱した後にｎ＝３で実施し、その平均値を求めた。 (Dielectric constant)
No. 1-No. For the insulated wire No. 5, the dielectric constant ε of the insulating layer 2 was measured. FIG. 3 is a schematic diagram for explaining a dielectric constant measurement method. First, a silver sample P was applied to three places on the surface of an insulated wire, and a measurement sample was prepared in which the conductor 1 was exposed by peeling off the insulating layer 2 on one end side of the insulated wire. Here, the coating length in the longitudinal direction of the insulated wire of the silver paste P applied to the three places on the surface of the insulated wire was 10 mm, 100 mm, and 10 mm in order along the longitudinal direction. The two silver pastes P applied with a length of 10 mm are grounded, and the electrostatic capacity between the silver paste P with a length of 100 mm applied between these two silver pastes and the exposed conductor 1 is determined. Measured with LCR meter M. The dielectric constant ε of the insulating layer 2 was calculated from the measured capacitance and the average film thickness of the insulating layer 2. The dielectric constant ε was measured at n = 3 after heating at 105 ° C. for 1 hour, and the average value was obtained.
（コロナ放電開始電圧の測定）
　部分放電試験機（菊水電子工業社の「ＫＰＤ２０５０Ｓ」）を使用して測定した。２本の絶縁電線の面同士を長さ１００ｍｍにわたって隙間が無いように密着させ、２本の導体間に電極を繋いだ。２５℃にて、周波数６０Ｈｚで昇圧し、１００ｐＣ以上の部分放電が発生した時の電圧を読み取った。ｎ＝５で実施し、その平均値で評価した。　 (Measurement of corona discharge start voltage)
Measurement was performed using a partial discharge tester (“KPD2050S” manufactured by Kikusui Electronics Corporation). The surfaces of the two insulated wires were brought into close contact with each other over a length of 100 mm, and electrodes were connected between the two conductors. The voltage was increased at 25 ° C. at a frequency of 60 Hz, and the voltage when a partial discharge of 100 pC or more occurred was read. It implemented by n = 5 and evaluated by the average value.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１の結果より、絶縁層の気孔率及びバラツキ割合が上記範囲であるＮｏ．１～Ｎｏ．４の絶縁電線は、誘電率が低く、コロナ放電開始電圧が高く、絶縁層の低誘電率化を促進すると共に、絶縁性に優れることが分かる。一方、Ｎｏ．５の絶縁電線は、バラツキ割合が上記範囲外であり、膜厚が近似するＮｏ．２に比べコロナ放電開始電圧が低下していた。これらの差異は、コアシェル粒子では膨張・発泡が起こり難いが、気孔形成材（発泡材など）を使用すると皮膜内の気孔膨張に伴い膜厚のバラツキが大きくなることに起因すると考えられる。 From the results in Table 1, No. in which the porosity and variation ratio of the insulating layer are in the above range. 1-No. It can be seen that the insulated wire No. 4 has a low dielectric constant, a high corona discharge starting voltage, promotes a reduction in the dielectric constant of the insulating layer, and is excellent in insulation. On the other hand, no. In the insulated wire No. 5, the variation ratio is out of the above range, and the film thickness is approximate. Compared to 2, the corona discharge starting voltage was lowered. These differences are considered to be due to the fact that when the pore-forming material (foaming material or the like) is used, the variation in the film thickness increases with the expansion of the pores in the film when the core-shell particles are hardly expanded or foamed.
　１　導体
　２　絶縁層
　３　気孔
　Ｍ　ＬＣＲメータ
　Ｐ　銀ペースト 1 Conductor 2 Insulating Layer 3 Pore M LCR Meter P Silver Paste

Claims (3)

  1. 　線状の導体と、この導体の外周面に被覆される絶縁層とを備える絶縁電線であって、
    　上記絶縁層が複数の気孔を含み、
    　上記絶縁層の気孔率が２０体積％以上６５体積％以下であり、
    　上記絶縁電線の長手方向に５０ｃｍ間隔で３０個所の断面で、各断面毎に８点の上記絶縁層の膜厚を測定し、これらの測定値から算定される下記式（１）のバラツキ割合が２５％以下である絶縁電線。
    　バラツキ割合（％）＝（４σ／平均膜厚）×１００　・・・（１）
    （上記式（１）中、平均膜厚は各測定値の平均値を示し、σは各測定値の標準偏差を示す。）     An insulated wire comprising a linear conductor and an insulating layer coated on the outer peripheral surface of the conductor,
    The insulating layer includes a plurality of pores;
    The porosity of the insulating layer is 20 volume% or more and 65 volume% or less,
    The thickness of the insulating layer at 8 points is measured for each cross section at 30 cross sections at 50 cm intervals in the longitudinal direction of the insulated wire, and the variation ratio of the following formula (1) calculated from these measured values is Insulated wires that are 25% or less.
    Variation ratio (%) = (4σ / average film thickness) × 100 (1)
    (In the above formula (1), the average film thickness indicates the average value of each measurement value, and σ indicates the standard deviation of each measurement value.)
  2. 　上記絶縁層の平均膜厚が６０μｍ以上である請求項１に記載の絶縁電線。 The insulated wire according to claim 1, wherein an average film thickness of the insulating layer is 60 µm or more.
  3. 　上記導体が、断面長方形の平角導体である請求項１又は請求項２に記載の絶縁電線。 3. The insulated wire according to claim 1, wherein the conductor is a rectangular conductor having a rectangular cross section.
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JP2024014433A (en) * 2022-07-22 2024-02-01 株式会社プロテリアル Insulated wire and method for manufacturing insulated wire

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