Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/303—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups H01B3/38 or H01B3/302
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B17/00—Insulators or insulating bodies characterised by their form
  • H01B17/56—Insulating bodies
  • H01B17/62—Insulating-layers or insulating-films on metal bodies
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/303—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups H01B3/38 or H01B3/302
  • H01B3/305—Polyamides or polyesteramides
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/303—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups H01B3/38 or H01B3/302
  • H01B3/306—Polyimides or polyesterimides

Definitions

• Patent Document 1 discloses a polyurethane-based insulated wire coating capable of producing an insulated wire with excellent insulation properties by extremely reducing the amount of residual solvent in the insulating film. are doing.
• the insulated wire of the present disclosure is an insulated wire including a linear conductor and an insulating layer covering the outer peripheral surface of the conductor, wherein the insulating layer contains a first solvent having a relative dielectric constant of 15 or more as a residual solvent. , and a second solvent having a dielectric constant of less than 15, and the first ratio, which is the ratio of the content of the second solvent to the total content of the first solvent and the second solvent contained in the insulating layer, is 50% by mass or more of the content of the second solvent with respect to the total content of the first solvent and the second solvent contained in the insulating layer after the heat treatment of heating the insulated wire at 350 ° C. for 1 minute A second ratio, which is a ratio, is higher than the first ratio.
• an object of the present disclosure is to provide an insulated wire in which the dielectric constant of the insulating layer is reduced.
• An insulated wire is an insulated wire including a linear conductor and an insulating layer covering the outer peripheral surface of the conductor, wherein the insulating layer has a relative dielectric constant as a residual solvent A ratio of the content of the second solvent to the total content of the first solvent and the second solvent contained in the insulating layer, including a first solvent of 15 or more and a second solvent having a dielectric constant of less than 15
• the first ratio is 50% by mass or more, and the above with respect to the total content of the first solvent and the second solvent contained in the insulating layer after the heat treatment of heating the insulated wire at 350 ° C. for 1 minute
• the second ratio which is the content ratio of the second solvent, is higher than the first ratio.
• the insulated wire having such characteristics can reduce the dielectric constant of the insulating layer, thereby improving the insulating properties.
• the insulating layer preferably contains one or more resins selected from the group consisting of polyimide resins, polyamideimide resins, polyesterimide resins and polyetherimide resins. As a result, the dielectric constant can be reduced in the insulating layer containing resin that is commonly used in insulated wires.
• the insulating layer preferably contains 0.2% by mass or more and 10% by mass or less of the first solvent and the second solvent in total. Thereby, the dielectric constant of the insulating layer can be further reduced.
• the insulating layer contains 5% by mass or less of the first solvent, and the insulating layer contains 0.1% by mass or more and 5% by mass or less of the second solvent. Thereby, the dielectric constant of the insulating layer can be further reduced.
• the insulating layer contains a curing agent, and the curing agent is an alicyclic acid anhydride, an aliphatic acid anhydride, an aromatic acid anhydride imidazole, triethylamine, a titanium-based compound, an isocyanate-based compound, a block It preferably contains one or more selected from the group consisting of isocyanate, urea, melamine, melamine compounds and acetylene derivatives. This can facilitate the formation of an insulating layer with the above characteristics from the insulating varnish.
• solvent means a substance used to dissolve another substance. Therefore, in the present specification, the category of “solvent” includes not only materials that are liquid at room temperature but also materials that are solid at room temperature, as long as they are materials used for dissolving other substances.
• An insulated wire according to the present embodiment is an insulated wire including a linear conductor and an insulating layer covering the outer peripheral surface of the conductor.
• the insulating layer contains a first solvent having a dielectric constant of 15 or more and a second solvent having a dielectric constant of less than 15 as residual solvents.
• a first ratio which is a ratio of the content of the second solvent to the total content of the first solvent and the second solvent contained in the insulating layer, is 50% by mass or more.
• a second ratio that is the ratio of the content of the second solvent to the total content of the first solvent and the second solvent contained in the insulating layer after the heat treatment of heating the insulated wire at 350 ° C. for 1 minute is higher than the first ratio.
• the insulated wire having such characteristics can reduce the dielectric constant of the insulating layer, thereby improving the insulating properties.
• the insulated wire according to the present embodiment contains not only the first solvent with a relative dielectric constant of 15 or more but also the second solvent with a relative dielectric constant of less than 15 as residual solvents in the insulating layer. Furthermore, a first ratio, which is a ratio of the content of the second solvent to the total content of the first solvent and the second solvent contained in the insulating layer, is 50% by mass or more. Since the first solvent has a dielectric constant of 15 or more, it is a high dielectric constant solvent, and the second solvent has a dielectric constant of less than 15, so it is a low dielectric constant solvent. It is considered that the dielectric constant of the insulating layer can be kept low.
• the content of the second solvent with respect to the total content of the first solvent and the second solvent contained in the insulating layer is higher than the first ratio.
• the fact that the second ratio is higher than the first ratio means that the first solvent more actively volatilizes from the insulating layer than the second solvent in the heat treatment.
• the second solvent since the above heat treatment simulates a part of the drying process performed in the manufacturing process of the insulated wire, the second solvent has priority over the insulating layer in the manufacturing process of the insulated wire.
• the content of the second solvent in the insulating varnish is small and the content of the first solvent is sufficient, thereby maintaining the storage stability of the resin, while the insulated wire is included in the insulating layer. It is understood that more than half of the residual solvent can be the second solvent, thereby reducing the dielectric constant of the insulating layer as described above. From the above, it is presumed that the insulated wire according to the present embodiment can reduce the dielectric constant of the insulating layer while maintaining the storage stability of the insulating varnish, thereby improving the insulating properties. .
• the insulated wire according to this embodiment includes a linear conductor as described above.
• the conductor is a conductor.
• a metal having high electrical conductivity and high mechanical strength is preferable. Specific examples include copper, copper alloys, aluminum, aluminum alloys, nickel, silver, soft iron, steel, and stainless steel.
• the conductor may be a wire formed by forming these metals into a linear shape, a coated wire in which the surface of the wire is coated with another metal, or a stranded wire in which a plurality of wires are twisted together. There may be.
• Examples of the coated wire include, but are not limited to, nickel-coated copper wire, silver-coated copper wire, silver-coated aluminum wire, and copper-coated steel wire.
• the shape of the conductor is not particularly limited, and a round wire, square wire, or the like can be appropriately selected according to the intended use and electrical characteristics of the insulated wire. That is, in a cross section obtained by cutting the insulated wire along a plane perpendicular to its longitudinal direction, the cross-sectional shape of the conductor may be circular or rectangular.
• the diameter or length of the outer circumference of the conductor is not particularly limited, either, and can be appropriately selected according to the intended use of the insulated wire, the electrical properties, and the like.
• the "flat angle" which is one of the cross-sectional shapes of the conductor, includes rectangles and squares, and shapes in which the four corners of these rectangles and squares are chamfered, and rounded shapes (R shapes). The shape etc. which have are also included.
• the lower limit of the cross-sectional area of the conductor is preferably 0.01 mm 2 , more preferably 0.1 mm 2
• the upper limit is preferably 20 mm 2 , more preferably 10 mm 2 . If the cross-sectional area of the conductor is less than 0.01 mm 2 , the volume ratio of the insulating layer to the conductor increases, and for example, the volumetric efficiency of the coil formed using the insulated wire may decrease. When the cross-sectional area of the conductor exceeds 20mm2 , it becomes necessary to increase the thickness of the insulation layer in order to sufficiently improve the insulation of the insulated wire. it tends to be difficult.
• the insulated wire according to this embodiment includes an insulating layer covering the outer peripheral surface of the conductor as described above.
• the insulating layer can contain any of conventionally known resins that are used to form insulating layers in this type of insulated wire.
• the resin contained in the insulating layer includes polyvinyl formal resin, polyurethane resin, alkyl resin, epoxy resin, phenoxy resin, polyester resin, polyesterimide resin, polyesteramideimide resin, polyamideimide resin, polyimide resin, and the like.
• examples include thermosetting resins and thermoplastic resins such as polyetherimide resins, polyetheretherketone resins, polyethersulfone resins, and polyimide resins. These resins can be contained singly or in combination of two or more.
• the insulating layer preferably contains one or more resins selected from the group consisting of polyimide resins, polyamideimide resins, polyesterimide resins and polyetherimide resins.
• the dielectric constant can be reduced in the insulating layer containing resin that is commonly used in insulated wires.
• the insulating layer more preferably contains a thermosetting polyimide resin.
• the polyimide resin preferably contains a small amount of a monomer other than polyimide, or may be a polyimide resin into which a functional group is introduced.
• the lower limit of the thickness of the insulating layer is preferably 5 ⁇ m, and the upper limit is preferably 200 ⁇ m. If the thickness of the insulating layer is less than 5 ⁇ m, the insulating layer tends to be easily broken, and the insulation of the conductor may become insufficient. If the thickness of the insulating layer exceeds 200 ⁇ m, the volume efficiency of the coil formed using the insulated wire tends to be low.
• the thickness of the insulating layer is the thickness of two pairs of the outer peripheral surfaces of the conductor in the cross section obtained by cutting the insulated wire along a plane perpendicular to its longitudinal direction. It means the average value of the thickness of the insulating layer covering the opposing surfaces (upper surface, lower surface, left surface and right surface).
• the surface to be measured is prepared by cutting the insulated wire along a plane perpendicular to its longitudinal direction and polishing the resulting cross section.
• an image is obtained by imaging the measurement target surface using a digital microscope VHX-7000 (manufactured by Keyence Corporation).
• the thickness of the insulating layer covering the two pairs of opposite surfaces of the outer peripheral surface of the conductor in the image for example, one point each from the upper surface, the lower surface, the left surface, and the right surface of the conductor is selected.
• An average value can be calculated from the values obtained by measuring the thickness of the insulating layer at each location, and this can be used as the thickness of the insulating layer.
• the thickness of the insulating layer when the cross-sectional shape of the conductor is circular is obtained by selecting four measurement points at equal intervals on the annular insulating layer in the image of the surface to be measured taken by the digital microscope, and then The thickness of the insulating layer can be measured at the four measurement points, and the average value of the thicknesses can be obtained.
• the insulating layer contains a first solvent having a dielectric constant of 15 or more and a second solvent having a dielectric constant of less than 15 as residual solvents.
• residual solvent refers to the solvent component contained in the insulating varnish applied to the outer periphery of the conductor in the manufacturing process of the insulated wire, and the insulating layer is formed by baking the insulating varnish on the conductor. It means a solvent component that remains in the insulating layer afterward.
• the insulating varnish may be prepared by diluting the above resin, or a resin precursor thereof, with an organic solvent comprising at least a first solvent and a second solvent.
• the organic solvent can consist of the first solvent and the second solvent described above.
• the first solvent is a high dielectric constant solvent having a relative dielectric constant of 15 or more.
• the first solvent as long as it is a high dielectric constant solvent having a relative dielectric constant of 15 or more, any of conventionally known organic solvents and materials that are solid at room temperature can be used.
• the first solvent examples include N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, dimethylsulfoxide, tetramethylurea, hexaethylphosphate
• NMP N-methyl-2-pyrrolidone
• DMAc N,N-dimethylacetamide
• N,N-dimethylformamide dimethylsulfoxide
• tetramethylurea hexaethylphosphate
• polar organic solvents such as triamide and ⁇ -butyrolactone
• ketone organic solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone.
• the first solvent one of these organic solvents can be used alone, or two or more of them can be mixed and used.
• Second solvent is a low dielectric constant solvent having a relative dielectric constant of less than 15.
• any conventionally known organic solvent which is a low dielectric constant solvent having a relative dielectric constant of less than 15 and which satisfies the conditions described later in relation to the first solvent and a material which is solid at room temperature can be used. can be done.
• Specific examples of the second solvent include ester organic solvents such as methyl acetate, ethyl acetate, butyl acetate and diethyl oxalate, diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether (butyl cellosolve), and diethylene glycol.
• Ether-based organic solvents such as dimethyl ether and tetrahydrofuran; hydrocarbon-based organic solvents such as hexane, heptane, benzene, toluene, xylene and naphtha; halogen-based organic solvents such as dichloromethane and chlorobenzene; phenol-based organic solvents such as cresol and chlorophenol; Amine-based organic solvents such as pyridine can be exemplified. Paraffin wax etc. can be illustrated as a material which becomes solid at room temperature of a 2nd solvent. As the second solvent, one of these organic solvents and materials that are solid at room temperature can be used alone, or two or more of them can be mixed and used.
• the "boiling point" of the second solvent is the boiling point of the compound with the highest boiling point (so-called “dry point") contained in the second solvent. shall mean
• the low dielectric constant solvent that can be used as the second solvent here satisfies the following two conditions in relation to the first solvent (high dielectric constant solvent). That is, the first condition is that the first ratio, which is the ratio of the content of the second solvent to the total content of the first solvent and the second solvent contained in the insulating layer of the insulated wire, is 50% by mass or more. It is to be. Therefore, the second solvent has a relationship of being equal to or greater than the first solvent in terms of mass as a residual solvent contained in the insulating layer.
• the second condition is the content of the second solvent with respect to the total content of the first solvent and the second solvent contained in the insulating layer after the heat treatment of heating the insulated wire at 350 ° C. for 1 minute.
• a second ratio which is a ratio, is higher than the first ratio.
• the first solvent more actively volatilizes than the second solvent in the heat treatment, so the second solvent has a higher boiling point than the first solvent. It is understood. That is, the second solvent preferably has a boiling point higher than that of the first solvent as a residual solvent contained in the insulating layer.
• the content of the second solvent in the insulating varnish is small and the content of the first solvent is sufficient by satisfying the first condition and the second condition described above. While maintaining the storage stability of the resin, more than half of the residual solvent contained in the insulating layer of the insulated wire can be used as the second solvent to keep the dielectric constant of the insulating layer low.
• the value is preferably 70% by mass or more, more preferably 80% by mass or more.
• the upper limit of the 1st ratio is 99.99% by mass.
• the value of the second ratio is not particularly limited as long as it is higher than the value of the first ratio.
• the difference between the value of the second ratio and the value of the first ratio is preferably 5 or more, and 10 or more. It is more preferable to have The upper limit of the second ratio is also 100% by mass as an ideal value.
• the insulation layer contains the first solvent and the second solvent in a total amount of 0.2% by mass or more and 10% by mass. % or less is preferable. Thereby, the dielectric constant of the insulating layer can be further reduced.
• the insulating layer contains the first solvent and the second solvent in a total amount of 0.5% by mass or more and 5% by mass or less, and more preferably 1% by mass or more and 4% by mass or less.
• the insulating layer contains 5 mass % or less of the first solvent, and the insulating layer contains 0.1 mass % or more and 5 mass % or less of the second solvent. Also in this case, the dielectric constant of the insulating layer can be further reduced.
• the lower limit of the content of the first solvent may be 0.02% by mass. If the content of the second solvent in the insulating layer before the heat treatment is less than 0.1% by mass, the effect of reducing the dielectric constant based on the second solvent may be insufficient. If the content of the second solvent exceeds 5% by mass, the strength of the insulating layer before the heat treatment may be impaired.
• the insulating layer before the heat treatment more preferably contains the first solvent in an amount of 3% by mass or less, more preferably 1.5% by mass or less.
• the insulating layer more preferably contains 0.5% by mass or more and 4.5% by mass or less of the second solvent, and more preferably 1.5% by mass or more and 4% by mass or less.
• Each content of the first solvent and the second solvent in the insulation layer of the insulated wire can be measured by, for example, a pyrolysis gas chromatography mass spectrometer (Py-GC/MS, trade name: “6890N/5973 Network", Agilent technologies (manufactured).
• the atmosphere is He gas and the flow rate is 1 mL/min.
• the thermal decomposition temperature 500° C. ⁇ 1 min. and
• Pyrolyzer Double-Shot Pyrolyzer (trade name: "PY-2020iD", manufactured by Frontier Laboratories) and MicroJet Cryotrap (Trade name: MJT-1030E, manufactured by Frontier Laboratories) Column: UA-5 (inner diameter 0.25 mm x length 30 m, film thickness 0.25 ⁇ m, manufactured by Frontier Labs) Thermal decomposition (temperature x time): 500°C x 1 min.
• each content (each residual amount) of the first solvent and the second solvent remaining in the insulating layer after the heat treatment of heating the insulated wire at 350 ° C. for 1 minute is the above-mentioned first solvent of the insulating layer of the insulated wire.
• 1 solvent and the second solvent can be obtained by using the above pyrolysis gas chromatography mass spectrometer in which the atmosphere is He gas (flow rate 1 mL/min). That is, from the respective contents of the first solvent and the second solvent remaining in the insulating layer, the thermal decomposition temperature among the above-described measurement conditions was determined as 350° C. ⁇ 1 min. By subtracting the amount of solvent generated by measuring under the changed conditions, each remaining amount after heat treatment can be obtained.
• the insulating layer preferably contains a curing agent.
• the curing agent includes alicyclic acid anhydrides, aliphatic acid anhydrides, aromatic acid anhydrides imidazole, triethylamine, titanium compounds, isocyanate compounds, blocked isocyanates, urea, melamine, melamine compounds and acetylene derivatives. It preferably contains one or more selected from the group consisting of This can facilitate the formation of an insulating layer with a reduced dielectric constant from the insulating varnish.
• These curing agents are appropriately selected depending on the type of resin or resin precursor in the insulating varnish, and imidazole, melamine, melamine compounds, etc. are preferably used.
• the insulated wire according to the present embodiment can be obtained by applying a conventionally known manufacturing method for this type of insulated wire, except for preparing a predetermined insulating varnish containing at least the first solvent and the second solvent. can.
• the insulated wire according to the present embodiment is preferably obtained using the following method for manufacturing an insulated wire, for example, from the viewpoint of manufacturing with high yield.
• the method for manufacturing an insulated wire according to the present embodiment preferably includes a step of preparing a conductor and an insulating varnish (first step) and a step of coating the outer peripheral surface with an insulating layer (second step). Further, the covering step (second step) preferably includes a step of applying insulating varnish to the outer peripheral surface (step A) and a step of baking the insulating varnish on the conductor (step B).
• first step preparing a conductor and an insulating varnish
• second step preferably includes a step of applying insulating varnish to the outer peripheral surface (step A) and a step of baking the insulating varnish on the conductor (step B).
• the first step is to prepare the conductor and insulating varnish.
• Conductors can be prepared, for example, by obtaining commercial products. It can also be prepared by casting, stretching, wire-drawing, and further softening the metals mentioned above as conductor materials.
• the insulating varnish can be prepared by diluting the resin described above as the material of the insulating layer or its resin precursor with an organic solvent containing at least the first solvent and the second solvent described above.
• the lower limit of the resin solid content concentration in the insulating varnish is preferably 15% by mass, more preferably 20% by mass, and the upper limit is preferably 50% by mass, more preferably 30% by mass.
• the resin solid content concentration means the concentration of the resin precursor.
• the insulating varnish can contain a curing agent in addition to the first solvent, the second solvent, and the resin or its resin precursor, and may further contain fillers, various additives, and the like.
• the insulating varnish may further contain a solvent other than the first solvent and second solvent described above.
• the content of the first solvent contained in the insulating varnish can be 55-97% by mass, and the content of the second solvent contained in the insulating varnish can be 0.1-30% by mass.
• the curing agent that can be contained in the insulating varnish one that has the function of curing the resin or the function of promoting the polymerization of the resin precursor can be used.
• alicyclic acid anhydrides such as methyltetrahydrophthalic anhydride, aliphatic acid anhydrides, aromatic acid anhydrides imidazole, triethylamine, titanium compounds, isocyanate compounds, blocked isocyanates, urea, melamine compounds and acetylene derivatives and the like.
• These curing agents are appropriately selected according to the type of resin or resin precursor in the insulating varnish.
• the insulating varnish contains a thermosetting polyimide precursor, imidazole or the like is preferably used as the curing agent.
• titanium-based compounds examples include tetrapropyl titanate, tetraisopropyl titanate, tetramethyl titanate, tetrabutyl titanate, tetrahexyl titanate, and the like.
• isocyanate-based compounds include aromatic diisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate, and naphthalene diisocyanate; hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexane diisocyanate, Aliphatic diisocyanates having 3 to 12 carbon atoms such as lysine diisocyanate; 1,4-cyclohexane diisocyanate (CDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), methylcyclo
• blocked isocyanate examples include diphenylmethane-4,4'-diisocyanate (MDI), diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenylether-4,4'-diisocyanate, 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.
• MDI diphenylmethane-4,4'-diisocyanate
• diphenylmethane-3,3'-diisocyanate diphenylmethane-3,4'-diisocyanate
• Examples of the melamine compound include melamine, methylated melamine, butylated melamine, methylolated melamine, and butyrolated melamine.
• Examples of the acetylene derivative include ethynylaniline and ethynylphthalic anhydride.
• the second step is to cover the outer peripheral surface of the conductor with an insulating layer.
• the second step can include a step of applying insulating varnish to the outer peripheral surface of the conductor (step A) and a step of baking the insulating varnish on the conductor (step B).
• the A process is a process of applying the insulating varnish prepared in the first process to the outer peripheral surface of the conductor. Specifically, step A can be performed by passing the conductor coated with the insulating varnish through an opening of a die. In the A process, it is preferable to apply the insulating varnish to the outer peripheral surface of the conductor with a uniform thickness by using a die having an opening.
• Step B is a step of baking the insulating varnish on the conductor.
• the B step can be performed by placing the conductor coated with the insulating varnish through the A step in a baking furnace and baking the insulating varnish on the conductor.
• the solvent in the insulating varnish is gasified and the resin is solidified, thereby forming an insulating layer on the outer peripheral surface of the conductor.
• the baking temperature and time of the insulating varnish in the baking furnace are appropriately selected from temperature conditions and time conditions known for manufacturing this type of insulated wire, depending on the type of resin and organic solvent in the insulating varnish. can do. Specifically, first, the amount of heat that is sufficient to form an insulating layer on the outer peripheral surface of the conductor and the desired amount of residual solvent is obtained according to the type of the resin, and then the amount of heat is determined. Baking temperature and time can be determined by The amount of heat can correspond to the product of baking temperature and time. If the baking temperature is high, the amount of heat can be dealt with by shortening the time. If the baking temperature is low, the amount of heat can be dealt with by lengthening the time.
• one or more insulating layers are laminated by repeating the application of the insulating varnish and the baking of the insulating varnish so that the insulating layer has a predetermined thickness.
• Conventionally known methods can be used for the method of applying the insulating varnish and the method of baking. After that, an insulated wire can be obtained by drying the insulating layer by a conventionally known method.
• an insulating layer obtained by applying an insulating varnish and baking the insulating varnish once is referred to as a “single layer” insulating layer.
• the insulating layer obtained by baking the varnish is referred to as a "multi-layered" insulating layer.
• the insulated wire according to the present embodiment can be manufactured. Since the dielectric constant of the insulating layer of the insulated wire manufactured by the manufacturing method described above is reduced, the insulation properties can be improved.
• An insulated wire including a linear conductor and an insulating layer covering the outer peripheral surface of the conductor,
• the insulating layer contains a first solvent having a relative dielectric constant of 15 or more and a second solvent having a relative dielectric constant of less than 15 as residual solvents,
• a first ratio which is a ratio of the content of the second solvent to the total content of the first solvent and the second solvent contained in the insulating layer, is 50% by mass or more,
• the insulated wire wherein the boiling point of the second solvent is higher than the boiling point of the first solvent.
• ⁇ Appendix 2> The insulated wire according to appendix 1, wherein the insulating layer contains one or more resins selected from the group consisting of polyimide resins, polyamideimide resins, polyesterimide resins, and polyetherimide resins.
• ⁇ Appendix 3> The insulated wire according to appendix 1 or appendix 2, wherein the insulating layer contains 0.2% by mass or more and 10% by mass or less of the first solvent and the second solvent in total.
• the insulating layer contains 5% by mass or less of the first solvent,
• the insulated wire according to any one of additional remarks 1 to 3, wherein the insulating layer contains 0.1% by mass or more and 5% by mass or less of the second solvent.
• Insulated wires of samples 2, 4, 6, 8, 10 and 12, which will be described later, are examples, and samples 1, 3, 5, 7, 9, 11, 13 and 13 are examples. 14 insulated wires are comparative examples.
• the thickness (unit: ⁇ m) of the insulating layer was obtained by using a digital microscope VHX-7000 (manufactured by KEYENCE CORPORATION) based on the measurement method described above.
• the dielectric constant of the insulating layer was obtained by using an impedance analyzer (trade name (model number): "ZA5405", manufactured by NF Circuit Design Block Co., Ltd.). Furthermore, in each test described later, the difference in dielectric constant in the insulating layer between the samples was also calculated.
• step 2 Second step The insulating varnish was applied to the outer peripheral surface of the conductor by immersing the conductor prepared in the first step in the insulating varnish prepared in the first step.
• the conductor coated with the insulating varnish was passed through an opening of a coating die having a cross-sectional shape similar to that of the conductor (step A).
• the conductor, to which the insulating varnish was uniformly applied through the above step A was baked in a baking furnace to coat the outer peripheral surface of the conductor with an insulating layer (step B).
• a predetermined amount of heat (+++) sufficient to form the insulating layer was calculated, and the baking temperature and time for applying the amount of heat (+++) were determined.
• Example 2 In the first step, naphtha (relative dielectric constant: 1.8, boiling point: 247° C.) as a second solvent is added to the first solvent, and the mass ratio of the first solvent and the second solvent is the first solvent:
• An insulated wire of sample 2 was obtained in the same manner as sample 1 except that the insulating varnish was prepared by adding the second solvent in a ratio of 9:1.
• sample 3 The insulated wire of sample 3 was made in the same manner as sample 1, except that the amount of heat (++) used to execute the baking treatment was two-thirds that of sample 1 in step B in the second step. got
• Example 4 In the first step, naphtha (relative dielectric constant: 1.8, boiling point: 247° C.) as a second solvent is added to the first solvent, and the mass ratio of the first solvent and the second solvent is the first solvent:
• An insulated wire of sample 4 was obtained in the same manner as sample 3 except that the insulating varnish was prepared by adding the second solvent in a ratio of 9:1.
• Example 6 In the first step, naphtha (relative dielectric constant: 1.8, boiling point: 247° C.) as a second solvent is added to the first solvent, and the mass ratio of the first solvent and the second solvent is the first solvent:
• An insulated wire of Sample 6 was obtained in the same manner as Sample 5 except that the insulating varnish was prepared by adding the second solvent in a ratio of 9:1.
• Example 8 In the first step, naphtha (relative dielectric constant: 1.8, boiling point: 247° C.) as a second solvent is added to the first solvent, and the mass ratio of the first solvent and the second solvent is the first solvent:
• An insulated wire of Sample 8 was obtained in the same manner as Sample 7, except that the insulating varnish was prepared by adding the second solvent in a ratio of 9:1.
• An insulated wire of Sample 10 was obtained in the same manner as Sample 9, except that the insulating varnish was prepared by adding 0.5:1.5.
• sample 11 In the first step, pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic acid are used at a molar ratio of 3:7 as tetracarboxylic dianhydrides that are raw materials for polyamic acid.
• An insulated wire of sample 11 was obtained in the same manner as sample 3 except that the insulating varnish was prepared by the method. The insulating varnish does not contain a second solvent.
• Example 12 In the first step, naphtha (relative dielectric constant: 1.8, boiling point: 247° C.) as a second solvent is added to the first solvent, and the mass ratio of the first solvent and the second solvent is the first solvent:
• An insulated wire of sample 12 was obtained in the same manner as sample 11 except that the insulating varnish was prepared by adding the second solvent in a ratio of 9:1.
• Example 14 In the first step, naphtha (relative permittivity: 1.8, boiling point: 175° C.) is added as a second solvent to the first solvent, and the mass ratio of the first solvent and the second solvent is the first solvent:
• An insulated wire of sample 14 was obtained in the same manner as sample 13 except that the insulating varnish was prepared by adding the second solvent in a ratio of 8:2.
• the insulating layer contains the first solvent and the second solvent as residual solvents
• the second solvent is the ratio of the content of the second solvent to the total content of the first solvent and the second solvent contained in the insulating layer. 1 ratio is 50% by mass or more, and the ratio of the residual amount of the second solvent to the total residual amount of the first solvent and the second solvent remaining in the insulating layer after the heat treatment of heating the insulated wire at 350 ° C. for 1 minute is higher than the first ratio, the effect of reducing the dielectric constant was confirmed. That is, in the first test, sample 2 had a lower dielectric constant in the insulating layer than sample 1. In the second test, sample 4 had a lower dielectric constant in the insulating layer than sample 3.
• sample 6 the dielectric constant of the insulating layer was lower than that of the sample 5.
• sample 8 had a lower dielectric constant in the insulating layer than sample 7;
• sample 10 had a lower dielectric constant in the insulating layer than sample 9;
• sample 12 had a lower dielectric constant in the insulating layer than sample 11.
• the boiling point of naphtha as the second solvent is 175°C, which is lower than the boiling point (204°C) of NMP as the first solvent, and naphtha (second solvent) volatilized in a large amount compared to NMP (first solvent).
• the insulated wire of Sample 14 had a first ratio of less than 50% by mass and a second ratio lower than the first ratio, so that the dielectric constant did not decrease as compared with Sample 13. From the above, it is understood that the insulated wires of Sample 2, Sample 4, Sample 6, Sample 8, Sample 10 and Sample 12 have a reduced dielectric constant of the insulating layer, thereby improving the insulating properties.

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