JP2019067683A - Manufacturing method for continuously manufacturing insulation wire in which conductor is insulated by aggregate of maghemite fine particles - Google Patents

Abstract

To provide a manufacturing method for continuously manufacturing an insulation wire superior to conventional performance for all wires by inexpensive manufacturing method regardless of conductor thickness of a flat wire, conductor width and size of gaps of a wound part of a coil, even when the conductor is a single wire, a twisted wire or the flat wire.SOLUTION: An insulation wire in which a conductor is insulated by an aggregate of magnetically adsorbed maghemite fine particles is continuously manufactured by impregnating a conductor (naked copper single wire 1) into a dispersion in which fine particles of ferrous oxide are dispersed in an organic compound diluted by alcohol and passing, then a temperature of the conductor is increased from a room temperature to a temperature at which an organic compound is volatilized, further temperature of the conductor is increased at which the fine particles of ferrous oxide are oxidized to maghemite fine particles 2, and further passing the conductor through a space where a magnetic field in which magnetization of the maghemite fine particles are saturated is generated, and then winding the conductor.SELECTED DRAWING: Figure 1

Description

The present invention relates to a manufacturing method for continuously manufacturing an insulated wire in which a conductor is insulated by a collection of fine particles in which saturated and magnetized maghemite fine particles are magnetically adsorbed.

A wire in which a conductor is covered with an insulator is called an insulated wire and is used in various applications. The conductor consists of a single or stranded wire. Moreover, the conductor has a round wire whose cross section has a substantially circular shape and a flat wire whose cross section is processed into a rectangular shape. Furthermore, although many of the conductors are made of copper or aluminum, copper alloys or aluminum alloys having high conductivity may be used if the merit of the alloy is greater than the disadvantage of the cost increase of the alloy material. A wire obtained by bundling a plurality of insulated wires and having a sheath (protective outer coating) outside is called a cable, and there are a metal communication cable for transmitting an electrical signal and an optical fiber cable for transmitting an optical signal.

Insulated wires consisting of round wires can be divided into wires for power transmission, distribution and wiring according to the allowable current. In addition, the electric wire used outdoors consists of a black insulating layer as a countermeasure against ultraviolet rays, and the standard of the service life by the Japan Wire Industry Association is 15 to 20 years.
Among the insulated wires for power transmission, there is a high voltage distribution line that delivers a voltage of more than 700 V DC, more than 600 V AC and less than 7 kV. The conductor is formed by twisting 7 to 19 strands, and the insulating layer is formed of a crosslinked polyethylene resin having a continuous maximum use temperature of 90 ° C. or a polyethylene resin having a continuous maximum use temperature of 75 ° C. There is also a high voltage service lead from the 3300-6600 V outdoor distribution line to the transformer on the pole. The conductor is formed by twisting seven strands, and the insulating layer is formed of a crosslinked polyethylene resin having a continuous maximum use temperature of 90 ° C. or an ethylene propylene rubber having a continuous maximum use temperature of 80 ° C. In addition, there are low voltage overhead wires used in low voltage distribution lines that use a transformer to drop power received from high voltage drop lines into single or three phases of 100V or 200V. The conductor is formed by twisting 7-19 strands, and the insulating layer is made of a vinyl resin having a continuous maximum operating temperature of 60.degree.
Among the insulated wires for power distribution, there is a low voltage lead-in wire used for an overhead lead-in wire for drawing electricity from a utility pole into a building. The conductor is formed by twisting 7-19 strands, and the insulating layer is made of a vinyl resin having a continuous maximum operating temperature of 60.degree.
Insulated wires for wiring vary widely depending on the final use place, but the main insulated wires include indoor wiring in buildings. Most of the indoor wiring is low voltage indoor wiring up to 600 V, the conductor is made by twisting seven strands, and the insulating layer is made of vinyl resin having a continuous maximum operating temperature of 60 ° C. In addition, the standard of the useful life of the indoor by the Japan Wire Industry Association is 20-30 years.

Furthermore, there is a coil (also referred to as a magnet wire) that uses an insulated wire made of a round wire for a coil, a motor, a plunger, a relay, and an electrical component of a car. The winding includes an enameled wire for applying and baking an insulating material, a transverse winding for winding a fiber, a film, a tape, a paper, a thread and the like, and an electric wire combining these. Enamel wire is divided by the heat resistance temperature of the insulating layer, polyvinyl formal copper wire of 105 ° C, polyurethane copper wire of 120 ° C, polyester copper wire of 155 ° C, polyesterimide copper wire of 180 ° C, polyamideimide copper wire of 200 ° C, There is a polyimide copper wire at 220 ° C. The insulating layer of the winding requires various performances such as dielectric breakdown, wear resistance, solvent resistance, chemical resistance, oil resistance, hydrolysis resistance, thermal shock resistance, heat resistance life and the like. Depending on the equipment in which the round wire is used, the environment to be used and the load to be applied largely change, and thereby the performance required for the insulating layer also changes greatly. In particular, the windings used for various electrical components mounted on automobiles have high required performance.

On the other hand, flat conductors with a relatively small aspect ratio are produced by wire drawing, and those with a large aspect ratio are produced by rolling of a round wire or slitting of a rolled sheet. Therefore, the processing cost to the flat wire can be low. The flat wire has an insulating layer on the surface, and when used as a coil winding or as a coil, the cross-sectional area ratio of the conductor in the cross-sectional area of the coil becomes higher than that of the round wire, resulting in miniaturization It is used as a winding or coil in various electric and electronic parts that require high performance.
That is, flat conductors are used in consumer devices as personal computers, televisions, control circuits, etc., as surface mount coils, as tablet terminals, smart phones, etc., as small surface mount coils. In automobiles, coils are used as coils for electric vehicles such as drive motors for hybrid vehicles, motors for electric compressors, motors for electric power steering, wiper motors, alternators, starters, ignition coils and the like. Moreover, it is used as a winding of various motors, such as an industrial motor, a motor for household appliances, and a small motor. In addition, various coils such as relay coils and clutch coils are used as coils of various transformers such as transformers for electric power, transformers for lighting equipment, and small transformers.
On the other hand, the insulating layer of the flat wire needs various performances such as insulation breakdown, wear resistance, solvent resistance, chemical resistance, oil resistance, hydrolysis resistance, thermal shock resistance, heat resistant life, etc. Depending on the equipment used, the environment to be used and the load to be applied may be largely changed, which in turn greatly changes the performance required for the insulating layer. Similar to the windings, the windings used for various electrical components mounted in automobiles have high required performance.
Also, the thickness and width of the flat wire vary depending on the device in which the flat wire is used. For example, in the case of an extremely thin rectangular wire used for a small surface mount coil, the conductor thickness is 0.02 mm, the conductor width is 0.1 to 0.3 mm, and the thickness of the insulating layer is only 0.005 mm. On the other hand, in a general rectangular wire, the conductor thickness is 0.8-1.0 mm, the conductor width is 1.7-3.5 mm, and the thickness of the insulating layer is 0.05 mm. Thus, the thickness of the insulating layer changes by one digit according to the thickness of the conductor. Also, the coil spacing varies by an order of magnitude depending on the conductor thickness.
Furthermore, there are various shapes of coils using flat wire. For example, an edgewise coil obtained by bending a flat wire in a width direction which is difficult to bend has shapes such as a rectangular edgewise coil, a circular edgewise coil, an oval edgewise coil, an elliptical edgewise coil, etc. There are coils of various shapes such as a tortoise shell coil wound in a loop shape and a toroidal coil wound in a toroidal shape.

As explained above, insulated wires are used in different applications and in different environments, and different loads are applied to the insulating layer. Therefore, the performance required for the insulating layer varies depending on the application. Therefore, there is no insulating layer that fulfills all the performances of all the insulated wires in one kind of insulating layer. In addition, the conductor thickness and the conductor width of the flat wire largely change depending on the application. Thus, there is no insulating layer that can accommodate all conductor thicknesses and conductor widths.

For example, according to Patent Document 1, when forming an insulating layer by electrodeposition coating on a coil made of a flat wire, the coil is stretched by opening a plurality of winding portions in advance in an elastic deformation region of the coil. It is described that the insulating layer is formed by maintaining the state and performing the electrodeposition coating process and the baking process in the extended state.
However, the process of maintaining the stretched state by opening the coil windings is required, which increases the cost of forming the insulating layer. Furthermore, a coil with a spacing of only 0.01 mm between the turns of the coil can not be maintained in an extended state with a spacing between the turns. Therefore, the insulating layer can be formed only on the limited coil.

In patent document 2, in order to make the thermal expansion coefficient of an insulating layer close to the thermal expansion coefficient of copper and to improve a thermal shock resistance, the composite material of spherical silica and polyphenylene sulfide resin is extruded and an insulating film is formed on a flat wire. It is described.
However, since spherical silica having an average particle diameter of 0.5 to 10 μm is compounded with the dissolved PPS resin at a volume ratio of 25 to 32%, the compounding ratio of spherical silica is increased, that is, the composite material The closer the coefficient of thermal expansion to copper, the lower the flexibility of the composite. When a coil is formed using a winding insulated with such a composite material, the insulating layer is cracked at the bend and can not be processed into a coil. Therefore, the application of the winding which is limited to the use of the winding which does not require bending, and which can be used is very narrow.
The thermal expansion coefficient of the spherical silica is 0.55 × ^{10 -6} / K, a thermal expansion coefficient of the PPS resin is 49-55 × ^{10 -6} / K, the thermal expansion coefficient of copper is 16.8 × 10 ^{- Since} it is ⁶ / K, in order to make the coefficient of thermal expansion of the composite material match the coefficient of thermal expansion of copper, it is necessary to increase the mixing ratio of silica spheres to a volume ratio of 2/3. However, as the proportion of the silica spheres is increased, the viscosity of the composite material increases and extrusion becomes difficult. In addition, the abrasion of the extruder becomes remarkable. Therefore, since the blending ratio of spherical silica is limited, the thermal expansion coefficient of the composite material is also limited. Therefore, there is a limit to the improvement of the thermal shock resistance of the insulating layer made of a composite material.

In Patent Document 3, a varnish used for electrodeposition coating is used in order to make the thickness of the insulating layer in the portion corresponding to the short side in the cross sectional shape of the flat wire larger than the thickness of the insulating layer in the portion corresponding to the long side. It is described that it comprises a resin for coating, water and a water-soluble solvent.
However, the insulating layer is required to have various performances such as insulation breakdown, wear resistance, solvent resistance, chemical resistance, oil resistance, hydrolysis resistance, thermal shock resistance, heat resistance life, etc. Even if the target insulating layer can be formed with such a varnish, the performance of the insulating layer is restricted by the water-soluble resin, and the use of the flat wire is limited.

Patent Document 4 describes an insulated wire in which a plurality of insulating layers are formed by an insulating paint having a low dielectric constant. That is, for example, due to the influence of the inverter surge voltage, partial discharge accompanied by dielectric polarization occurs on the surface of the insulating layer as the insulating layer has a larger dielectric constant, and the insulating layer is eroded due to deterioration due to partial discharge. Breakdown occurs. Therefore, in the inner first layer, a low dielectric constant polyesterimide resin having a dielectric constant of less than 3.8, a low dielectric constant polyamideimide resin having a dielectric constant of less than 4.0, or a dielectric constant of less than 3.2 The low dielectric constant insulating paint mainly composed of any one kind of low dielectric constant polyimide resin is baked and painted, and any one kind of polyester imide resin, polyamide imide resin, or polyimide resin is mainly used as the second layer. At the same time, it is described that a low dielectric constant insulating paint containing inorganic fine particles as a secondary component is baked and coated.
On the other hand, the insulating material most excellent in conventional arc resistance and tracking resistance is a silicone varnish having a dielectric constant of 3.1 to 3.2. However, even silicone varnishes have limitations on arc resistance and tracking resistance. Therefore, even if the low dielectric constant insulating paint described in Patent Document 4 is used, arc resistance and tracking resistance are limited. Furthermore, the first layer and the second layer are separately baked and coated, and interfaces made of different materials are not fused due to the difference in melting point, and gaps due to layer separation are formed in the interfaces. When such a gap is present, partial discharge occurs in the gap. In the repetition of this discharge, the insulator is gradually eroded and eventually leads to dielectric breakdown. In addition, the manufacturing cost is increased as compared with the conventional insulating layer consisting of a single layer.

JP, 2017-115242, A JP, 2014-029779, A JP, 2017-016956, A JP, 2016-181344, A

As described in the patent documents described above, the described techniques are effective only for limited applications and are not universal. Therefore, there is no insulating layer that fulfills all the performances of all the insulated wires in one kind of insulating layer.
In the present invention, regardless of the environment in which the insulated wire is used, and whether the wire is a single wire, a stranded wire or a flat angle wire, regardless of the wire, the flat angle Regardless of the conductor thickness of the conductor, the conductor width, and regardless of the size of the coil winding interval, it is superior to the conventional performance for all the wires, and it is continuous in an inexpensive manufacturing method. It is an object of the present invention to realize a method of manufacturing an insulated wire.

The manufacturing method for continuously manufacturing the insulated wire includes a first step of immersing and passing the conductor in a suspension in which fine particles of ferrous oxide are dispersed in an organic compound diluted with alcohol, and an air atmosphere. The first heat treatment apparatus is heated to a temperature at which the organic compound evaporates from room temperature, the second step of passing the conductor, and the fine particles of ferrous oxide are oxidized into fine particles of maghemite in the air atmosphere. The conductor is passed through the third heat treatment apparatus, which is heated to a predetermined temperature, and the space of the atmospheric atmosphere in which the magnetic field to saturate the magnetization of the maghemite fine particles is generated. A manufacturing method comprising the fourth step and the fifth step of winding the conductor, wherein the five steps are carried out successively, continuously produces an insulated wire in which the conductor is insulated with a collection of maghemite fine particles. The It is a manufacturing method.

That is, when the conductor is immersed in the suspension and passes through the suspension, the suspension adheres to the conductor with a thickness corresponding to the viscosity of the suspension. Therefore, regardless of whether the conductor is a round conductor consisting of a single wire or a stranded wire or a flat angle conductor, the thickness of the single wire, the number of strands, the conductor thickness of the flat wire, the conductor width Also, regardless of the type of conductor, the suspension adheres at a thickness corresponding to the viscosity of the suspension. Thereafter, the conductor is moved through the first heat treatment apparatus to raise the temperature, and after alcohol is vaporized from the suspension, the organic compound is vaporized, and ferrous oxide (represented by the chemical formula of FeO) is formed on the surface of the conductor. A collection of particles adheres. Furthermore, the conductor moves to the second heat treatment apparatus, is left for a certain time, and all ferrous oxide divalent iron ions (Fe ²⁺ ) are oxidized to trivalent iron ions (Fe ³⁺ ), ferrous is oxidized to maghemite (represented by the chemical formula of _γ-Fe 2 _{O 3} in the gamma phase of ferric oxide _Fe 2 _{O 3)} oxide. As a result, the conductor is covered with a collection of magnetically adsorbed maghemite fine particles. Furthermore, the conductor passes through the space where the magnetic field is generated, the magnetization of the maghemite particles is saturated, the conductors are covered with a collection of maghemite particles in which the saturated magnetizations are magnetically adsorbed, and the insulating layer is composed of a collection of maghemite particles. It is formed on a conductor. After this, the conductor is wound up. Thus, the insulated wire is continuously manufactured.
The manufacturing method of the above-mentioned insulated wire brings about the outstanding effect by the following features.
First, since all five steps are treated in the atmosphere, the five steps can be carried out continuously. Thereby, the insulated wire can be manufactured continuously. In addition, all five processes are extremely simple processes, and insulated wires are continuously manufactured at low cost.
In addition, a plurality of single-wire or stranded-wire conductors or a plurality of flat-angle conductors are moved in parallel at intervals, and the above-mentioned five steps are continuously carried out. It can be manufactured continuously. This further reduces the cost of manufacturing the insulated wire.
Second, in the first step, the thickness of the insulating layer is determined by the viscosity of the suspension, and the viscosity of the suspension can be changed in any way by the dilution rate of alcohol. By this, the thickness of the insulating layer can be changed in any way. That is, as described in the fifth paragraph, the thickness and width of the flat conductor greatly vary depending on the device in which the flat conductor is used, whereby the thickness of the insulating layer changes by one digit according to the conductor thickness, and the flat conductor The spacing of the coils using V varies by an order of magnitude depending on the conductor thickness. Therefore, the suspension is made of an organic compound diluted with alcohol so that the thickness of the insulating layer can be easily changed by one digit, and the viscosity of the suspension can be changed by one digit at the dilution rate of alcohol. Thereby, the thickness of the insulating layer can be changed in any way, and the insulated wire can be used as a winding for any coil. Therefore, when used as a winding in which the distance between turns of the coil is narrow, the dilution rate of alcohol is increased. For example, the insulating layer can be formed even for a winding in which the distance between turns of the coil is narrow and the thickness of the insulating layer is only 0.005 mm.
Thirdly, by conducting the fourth step as the step of saturating the magnetization of the maghemite fine particles, the conductor insulated in the fifth manufacturing step can be wound up, whereby the insulated wire is continuously formed. It can be manufactured. That is, the wound up insulated wire receives magnetic attraction from the insulating layer of the adjacent insulated wire. However, since maghemite fine particles having magnetizations saturated in the same direction magnetically adsorb each other, the magnetic attractive force of the maghemite fine particles forming the insulating layer is larger than the magnetic attractive force received from the insulating layer of the adjacent insulated wire. For this reason, the magnetite particulates of the insulating layer are not pulled up by the magnetic attraction force from the insulating layer of the adjacent insulated wire, and the insulated wire can be wound up by this. Furthermore, the magnetic Curie point of maghemite is 675 ° C, and phase transition is gradually made to hematite (shown by the chemical formula of α-Fe ₂ O ₃ ), which is the α phase of ferric oxide, at a temperature of 450 ° C or higher in the atmosphere. . This phase transition is an irreversible change. Therefore, the magnetic adsorption force of the maghemite fine particles has a heat resistance close to 450 ° C. Therefore, the wound insulated wire can be left at high temperature for a long time.
Fourth, by making the magnetization of the maghemite fine particles saturate in the fourth step, the insulated wire can be wound as a winding for any coil. That is, since a large load is applied to the insulating layer when the insulated wire is used as a winding, the magnetization of the maghemite fine particles is saturated. That is, the maghemite fine particles are not separated from a collection of maghemite fine particles in which the maghemite fine particles are particulate fine particles having a very small mass of 10 to 100 nm and adjacent granular fine particles magnetically adsorbed with saturated magnetization. . Therefore, when winding the insulated wire as a winding around various coils, a load is applied to the collection of maghemite fine particles, but the collection of the magnetically adsorbed maghemite fine particles is only temporarily deformed, so that the insulating layer can The particles are not pulled off. Furthermore, compared with the diameter of the conductor, the thickness of the insulating layer is as small as three digits, and the insulated wire can be wound even for a coil having a small winding interval. Also, the deformed insulating layer returns to its original shape by magnetic attraction, and the insulating layer has excellent flexibility. Furthermore, as described above, since maghemite has heat resistance close to 450 ° C., the coil also has heat resistance close to 450 ° C. Moreover, the pinhole size of the conventional insulating layer is three orders of magnitude larger than that of the maghemite fine particles, and even if the thickness of the insulating layer is thin, the pinhole which is an electrical weak point is the insulating layer to which the maghemite fine particles are magnetically adsorbed. not exist.
Furthermore, the insulated wire manufactured by the above-mentioned manufacturing method has an effect that all the performance required for the insulating layer is significantly improved over the performance of the insulating layer of the conventional insulated wire.
First, maghemite is a ferromagnetic material with spontaneous magnetization. For this reason, the maghemite fine particles magnetically adsorb to each other. Furthermore, when the magnetization of the maghemite fine particles is saturated, the magnetization is saturated in the same direction, and the magnetic attraction between the maghemite fine particles is significantly increased. Thereby, as described above, the insulated wire can be wound up, and the insulated wire can be used as a winding for any coil.
Second, the magnetic Curie point of maghemite is 675 ° C, and it gradually phase-transfers to hematite at a temperature of 450 ° C or higher in the atmosphere. Therefore, the magnetic adsorption power of the maghemite fine particles has heat resistance close to 450 ° C. On the other hand, among polymer materials used for the insulating layer, polyamideimide resin is the polymer material having the highest heat resistance, the softening point of the polyamideimide resin is 270 ° C., and the heat resistance temperature is 270 of the softening point. ° C. Accordingly, the heat resistance temperature of the insulated wire is improved by 150 ° C. or more than the heat resistance temperature of the conventional insulating layer, and the heat resistance life is also significantly extended.
Third, even if the temperature of the insulated wire changes, the magnitude of thermal expansion and thermal contraction of the maghemite fine particles having a size of 10 to 100 nm is extremely small, and the maghemite fine particles hardly thermally expand and shrink. For this reason, the insulating layer also hardly thermally expands and contracts. Also, since the magnetic Curie point of maghemite is high, if the temperature of the insulated wire is lower than 450 ° C., the magnetic attraction hardly changes. Therefore, even if the temperature of the device on which the insulated wire is mounted changes rapidly, no thermal stress is generated in the maghemite fine particles. As a result, the thermal shock resistance of the insulated wire is significantly improved over the conventional insulated wire.
Fourth, maghemite is an insulator having a specific resistance of 10 ⁶ Ωm and a relative dielectric constant of 1.6 to 1.8. Among the conventional insulating layers, the dielectric constant of the silicone varnish which is most excellent in arc resistance and tracking resistance is 3.1-3.2. For this reason, the insulating layer formed of a collection of maghemite fine particles is remarkably excellent in arc resistance and tracking resistance than silicone varnish. Therefore, the dielectric breakdown of the insulating layer is significantly improved over the conventional insulating layer. In the insulating layer, there are many holes of several nano-sized size surrounded by the maghemite fine particles. However, since the size of the pores is three orders of magnitude smaller than the void (bubble) generated by baking coating of the conventional insulating paint, and the dielectric constant of the maghemite fine particles surrounding the pores is low, partial discharge to the pores Does not happen. Therefore, even if this insulated wire is used for the motor of inverter control, partial discharge erosion by the inverter surge does not occur in the insulating layer, and the dielectric breakdown does not occur. In addition, even if the thickness is significantly thinner than the conventional insulating layer, no dielectric breakdown occurs. For this reason, it can be used as a winding in which the thickness of the insulating layer is only 0.005 mm, as in the case of an ultra-fine rectangular wire used for a small surface mount coil. The relative dielectric constant of the above-described polyamideimide resin has a high value of 3.8 to 4.1.
Fifth, maghemite is an inorganic substance consisting of a very stable black metal oxide and is known as a substance that forms a passive film of iron. Therefore, it does not react at all with any solvent, acid, alkali, naphtha, kerosene, gasoline, etc. at all. In addition, all the liquid can not penetrate into the collection of magnetically adsorbed maghemite fine particles, that is, the insulating layer by surface tension. For this reason, solvent resistance, chemical resistance and oil resistance are superior to conventional insulating layers. In addition, it does not hydrolyze, does not cause electrical degradation, and does not cause degradation due to ultraviolet light. In addition, the insulating layer hardly causes thermal expansion and thermal contraction. Therefore, the insulating layer does not cure at low temperatures and does not soften at high temperatures, as in conventional polymeric materials. Therefore, the insulating layer is not weakened even if it is left at a very low temperature for a long time, and the insulating layer is not thermally deteriorated even if it is left at high temperature for a long time.
Sixth, it has a Mohs hardness of 6.5, which is a significantly harder material than electromagnetic steel sheet, and does not wear when it comes in contact with other parts or substrates. In addition, since the insulating layer is deformed temporarily only slightly when it contacts, it does not attack the contacted component or the base material. On the other hand, when the insulated wire is wound around the device as a winding, a load is applied to the collection of maghemite fine particles, but the maghemite fine particles are granular fine particles, and the granular fine particles slip slightly at the contact site. Particulates are not destroyed by contact. Therefore, the wear resistance is significantly improved over the conventional insulating layer. For this reason, the surface of the insulating layer is scratched by abrasion, and a partial discharge is generated therefrom, which does not lead to dielectric breakdown.
As described above, the insulated wire insulated with a collection of maghemite particles in which the magnetite particles of the maghemite particles are magnetically adsorbed with saturation magnetization is independent of the environment in which the insulated wire is used, and the wire is a single wire. Regarding all the wires regardless of the wire thickness of the flat wire, regardless of the wire thickness regardless of the wire whether it is a wire, a stranded wire, a round wire or a flat wire The required performance is significantly improved over conventional insulated wires. Furthermore, since the insulated wire having such excellent performance is continuously manufactured by continuously performing the above-described five simple steps, the manufacturing cost of the insulated wire is low. As a result, the problems described in the 12th paragraph were solved.

The production method for producing the above-mentioned suspension comprises the first step of dispersing an organic iron compound which precipitates ferrous oxide by thermal decomposition in alcohol to prepare an alcohol dispersion, and dissolving or mixing in the alcohol. The first property, the second property having a viscosity higher than that of the alcohol, and the boiling point that is higher than the thermal decomposition temperature of the organic iron compound and lower than the temperature at which the ferrous oxide is oxidized to maghemite A second step of mixing an organic compound having the following properties into the alcohol dispersion liquid to form a liquid mixture, and raising the temperature of the liquid mixture to a temperature at which the organic iron compound is thermally decomposed in an air atmosphere. A manufacturing method comprising three steps and a fourth step of mixing the alcohol with the heat-treated mixed solution, wherein the four steps are continuously performed is oxidation of an organic compound diluted with alcohol. Microparticles monoferric is a method of manufacturing the suspension dispersed.

That is, when the organic iron compound which precipitates ferrous oxide by thermal decomposition is dispersed in alcohol, the organic iron compound is uniformly dispersed in the alcohol. Next, when an organic compound having three properties is mixed in an alcohol dispersion, the organic compound dissolves or mixes with the alcohol, the organic iron compound is uniformly dispersed in the mixture, and a mixture having a viscosity higher than that of the alcohol is obtained. . Further, the mixture is heated to the thermal decomposition temperature of the organic iron compound in the air atmosphere. First, the alcohol is vaporized to precipitate fine crystals of the organic iron compound in the organic compound. The size of the fine crystals is close to the size of the ferrous oxide fine particles. Furthermore, if the boiling point of the organic acid which comprises an organic iron compound is exceeded, an organic iron compound will decompose | disassemble into an organic acid and ferrous oxide. When the temperature is further raised, the vaporization of the organic acid proceeds, and when the vaporization of the organic acid is completed, particulate microparticles of ferrous oxide precipitate in the organic compound. The ferrous oxide is a nonmagnetic substance, and the fine particles are not magnetically adsorbed, and are uniformly dispersed in the organic compound. The suspension is diluted with alcohol to produce a suspension of ferrous oxide microparticles dispersed in an alcohol-diluted organic compound.
The above organic iron compounds and organic compounds are general-purpose industrial chemicals and inexpensive. In addition, since all of the four steps are treatment in the air atmosphere, the four steps can be performed continuously. For this reason, a suspension can be manufactured at low cost using inexpensive chemicals as raw materials.

In the production method for producing the above-mentioned suspension, the production method for producing the above-mentioned suspension, wherein the organic iron compound is a carboxylic acid iron compound in which an oxygen ion constituting a carboxyl group coordinates to an iron ion. .

That is, an iron carboxylate compound in which an oxygen ion (O ⁻ ) constituting a carboxyl group becomes a ligand and approaches a divalent iron ion (Fe ²⁺ ) to coordinate bond is a ferrous oxide by thermal decomposition. Precipitate out. Therefore, when the organic iron compound described in the 16th paragraph is composed of an iron carboxylate compound and the liquid mixture in which the iron carboxylate compound is dispersed is heat-treated in the atmosphere, the iron carboxylate compound is thermally decomposed at a temperature lower than 350 ° C. A collection of particulate ferrous oxide particulates falling in the range of 10-100 nm in size precipitates in the organic compound. The suspension is diluted with alcohol to produce the suspension described in paragraph 16.
That is, an iron carboxylate compound in which an oxygen ion constituting a carboxyl group becomes a ligand and approaches a divalent iron ion and coordinates is coordinated with an oxygen ion approaching an iron ion which is the largest ion. Because of the coupling, the distance between the two becomes short. As a result, the distance between the oxygen ion coordinated to the iron ion and the ion covalently bonded to the opposite side of the iron ion is maximized. The iron carboxylate compound having such a molecular structural feature is bound to an ion in which the oxygen ion constituting the carboxyl group is covalently bonded on the opposite side of the iron ion when the boiling point of the carboxylic acid constituting the iron carboxylate compound is exceeded. The part is first divided and decomposed into ferrous oxide, which is a compound of iron ion and oxygen ion, and carboxylic acid. When the temperature is further raised, the carboxylic acid takes heat of vaporization and is vaporized, and after vaporization of the carboxylic acid is completed, ferrous oxide is deposited.
As such an iron carboxylate compound, there are an iron acetate compound, an iron caprylate compound, an iron benzoate compound, and an iron naphthenate compound in the order of molecular weight. In all of iron acetate, iron caprylate and iron benzoate, oxygen ions approach iron ions and coordinate bond to form a dinuclear complex salt. On the other hand, the substances produced in the course of thermal decomposition are the most stable substances produced in the thermal decomposition of iron naphthenate. For this reason, iron naphthenate is the simplest heat treatment for depositing ferrous oxide by thermal decomposition of the iron carboxylate compound. Naphthenic acid is a mixture of saturated fatty acids having a 5-membered ring and is represented by a general formula consisting of C _n H _{2 n-1} COOH, the main component having a boiling point of 268 ° C. and a molecular weight of 170 C ₉ H ₁₇ COOH Become. Therefore, the thermal decomposition of iron naphthenate is completed at 340 ° C. in the air atmosphere to precipitate ferrous oxide.
Furthermore, the above-mentioned iron carboxylates are inexpensive industrial chemicals that can be easily synthesized. That is, when a general purpose carboxylic acid is reacted with a strong alkali, a carboxylic acid alkali metal compound is formed. Thereafter, an alkali metal carboxylate compound is reacted with an inorganic iron compound to synthesize an iron carboxylate compound. In addition, since the carboxylic acid as the raw material is an organic acid having a relatively low boiling point among the boiling points of the organic acid, fine particles of ferrous oxide are contained in the organic compound by heat treatment lower than 350 ° C. in the atmosphere. It precipitates.
As described above, a metal carboxylate compound which is an inexpensive raw material and which deposits ferrous oxide by thermal decomposition is suitable as the organic iron compound described in the 16th paragraph.

In the manufacturing method which manufactures the above-mentioned suspension, the manufacturing method which manufactures the above-mentioned suspension whose said organic compound is an organic compound which belongs to carboxylic acid ester.

That is, the carboxylic acid esters are first dissolved or mixed in alcohol, secondly higher in viscosity than the alcohol, thirdly higher in boiling point than the thermal decomposition temperature of the organic iron compound, and first oxidized Organic compounds that combine these three properties below the temperature at which iron is oxidized to maghemite are present in the organic compounds belonging to carboxylic esters. In addition, such carboxylic esters are general-purpose industrial chemicals used for fiber oil agents, metal oil agents, synthetic lubricating oils, synthetic resins, cosmetics, and surfactants.
Therefore, when the carboxylic acid esters having three properties are mixed with the alcohol dispersion of the organic iron compound described in the 16th paragraph, the carboxylic esters are dissolved or mixed in the alcohol, and the viscosity is higher in the 16th stage than the alcohol. The described mixture is made.
For this reason, carboxylic acid esters are suitable as the organic compound described in the 16th paragraph.

FIG. 6 is an explanatory view schematically illustrating a cross section covered with a collection of maghemite fine particles to which a copper wire is magnetically adsorbed.

Embodiment 1
In this embodiment, using iron naphthenate as the organic iron compound, the suspension described in the 16th paragraph is prepared, and the conductor to which the suspension is attached is heat-treated to form the insulating layer on the conductor. Do.
Iron naphthenate is a complex in which an oxygen ion constituting a carboxyl group of naphthenic acid becomes a ligand, approaches a divalent iron ion, and coordinates to a divalent iron ion. That is, since the oxygen ion approaches and coordinates with the divalent iron ion which is the largest ion, the distance between the two becomes short. As a result, the distance between the oxygen ion coordinated to the divalent iron ion and the ion covalently bonded to the opposite side of the iron ion is maximized. When iron naphthenate having such a molecular structural feature exceeds the boiling point of the main component of naphthenic acid, an ion in which an oxygen ion constituting a carboxyl group in iron naphthenate is covalently bonded on the opposite side of a divalent iron ion At first, the bond portion with is decomposed to decompose into ferrous oxide and naphthenic acid, which are compounds of divalent iron ions and oxygen ions. When the temperature is further raised, naphthenic acid takes heat of vaporization and is vaporized, and when vaporization of naphthenic acid is completed, ferrous oxide is precipitated and thermal decomposition is finished. For this reason, iron naphthenate is an organic iron compound which precipitates ferrous oxide by the thermal decomposition described in the sixteenth paragraph.
When iron naphthenate is dispersed in alcohol, iron naphthenate is uniformly dispersed in the alcohol. Next, when the organic compound having the three properties described in the sixteenth paragraph is mixed with the alcohol dispersion, the organic compound is dissolved or mixed with the alcohol, and a mixed solution having a viscosity higher than that of the alcohol is produced. Further, the temperature of the mixture is raised by the first heat treatment apparatus. First, the alcohol is vaporized to precipitate fine crystals of iron naphthenate in the organic compound. Next, if it exceeds 268 ° C. which is the boiling point of the main component of naphthenic acid, iron naphthenic acid is decomposed into naphthenic acid and ferrous oxide. Thereafter, the temperature rising rate is increased to vaporize naphthenic acid, and particulate particles of ferrous oxide precipitate in the organic compound at 340 ° C. at which the vaporization is completed. The ferrous oxide is a nonmagnetic substance, and the fine particles of ferrous oxide are not magnetically adsorbed to one another, and uniformly dispersed in the organic compound. The suspension is diluted with alcohol to form a suspension.
Next, the conductor is immersed in the suspension and passed, and in the second heat treatment apparatus, the temperature rising rate is suppressed in the air atmosphere, the temperature is raised from 340 ° C. to 380 ° C., and it is left at 380 ° C. for a fixed time. At this time, an oxidation reaction proceeds in which divalent iron ions of ferrous oxide become trivalent iron ions. At the initial stage of this oxidation reaction, part of the divalent iron ions of ferrous oxide (FeO) becomes trivalent iron ions to form ferric oxide (Fe ₂ O ₃ ), and the composition formula is FeO ·· It is oxidized to magnetite of Fe ₂ O ₃ . Furthermore, when it is left for a long time, the oxidation reaction proceeds further, and all of the ferrous oxide is oxidized to magnetite. Further, if the standing is extended, all of the divalent iron ions constituting magnetite become trivalent iron ions, become ferric oxide, and complete the oxidation reaction. The ferric oxide is maghemite (γ-Fe ₂ O ₃ ), which is a gamma system of ferric oxide, which is a cubic system similar to magnetite. On the other hand, the crystal structure of hematite (α-Fe ₂ O ₃ ), which is the alpha phase of ferric oxide, is a trigonal system, and the crystal structure is different from that of magnetite. As a result, the conductor is covered with a collection of magnetically adsorbed maghemite fine particles. Furthermore, when the conductor passes a magnetic field that saturates the magnetization of the maghemite particles, an insulated wire is manufactured.
In addition, iron naphthenate is an inexpensive industrial chemical that can be easily synthesized, as described in the eighteenth paragraph, and is one of the least expensive compounds among organic acid iron compounds. In addition, since naphthenic acid as a raw material has a relatively low boiling point among the boiling points of organic acids, ferrous oxide is precipitated by heat treatment at about 340 ° C. in the air atmosphere. Naphthenic acid having such properties is widely used in paint / printing ink driers, rubber / tire adhesives, lubricant extreme pressure agents, polyester curing agents, flame retardants, polymerization catalysts, etc. There is.

Embodiment 2
In this embodiment, first, it is dissolved or mixed with alcohol, secondly, its viscosity is higher than that of the alcohol, and third, its boiling point is higher than the thermal decomposition temperature of the organic iron compound, and ferrous oxide is maghemite The organic compound combines these three properties below the temperature at which it is oxidized. Here, the boiling point of the organic compound is required to be higher than 340 ° C. and lower than 380 ° C. in order to use the organic iron compound as iron naphthenic acid. Also, methanol, which is the most versatile industrial alcohol, is used as the alcohol.
Among the organic compounds that combine these three properties, there are organic compounds belonging to carboxylic esters. On the other hand, three kinds of carboxylic acid esters consist of a first ester consisting of saturated carboxylic acid, a second ester consisting of unsaturated carboxylic acid, and a third ester consisting of aromatic carboxylic acid. Can be divided into esters of

Among the esters consisting of the first saturated carboxylic acid, carboxylic acid esters which are dissolved in methanol and whose viscosity is higher than the boiling point of methanol and whose boiling point falls within the range of 340-380 ° C. have higher molecular weight than capric acid esters. Present in esters. Among the laurates, only octyl laurate having a boiling point of 355 ° C. is relevant. There is no corresponding ester in myristic esters. The boiling point of ethyl myristate is 295 ° C., and the boiling point of butyl myristate is 389 ° C. Further, among palmitic acid esters, only butyl palmitate having a boiling point of 362 ° C. corresponds. Further, among stearic esters, only propyl stearate having a boiling point of 376 ° C. is applicable.

Among the esters composed of the second unsaturated carboxylic acid, carboxylic acid esters which are dissolved in methanol and whose viscosity is higher than the boiling point of methanol and whose boiling point falls within the range of 340 to 380 ° C. are oleic acid esters and linoleic acid esters And linolenic acid esters. Among oleic acid esters, methyl oleate having a boiling point of 351 ° C. corresponds, and among linoleic acid esters, methyl linoleate having a boiling point of 373 ° C. corresponds, and among linolenic acid esters, a boiling point There is 364 ° C of methyl linolenate.

Among esters composed of a third aromatic carboxylic acid, carboxylic acid esters which are dissolved in methanol and whose viscosity is higher than the boiling point of methanol and which has a boiling point of 340-380 ° C. are slightly present in phthalic acid esters. And the boiling point of dihexyl phthalate is 350 ° C.

Example 1
In Example 1, according to Embodiment 1, a method of forming an insulating layer on a copper wire with a collection of fine particles of magnetite is described. The naphthenic acid iron used the naphthenic acid iron (For example, the product of Toei Kako Co., Ltd.) marketed as metal soap. As the organic compound, methyl oleate having a boiling point of 351 ° C. (for example, a product of Wako Pure Chemical Industries, Ltd.) was used. Methyl oleate is used in synthetic fiber oils, metal oils, synthetic lubricants, synthetic resins, cosmetics, and surfactant raw materials. As methanol, a first-grade reagent was used. As a conductor, a bare copper single wire (for example, a product of Fukuda Electric Wire Co., Ltd.) having a cross-sectional area of 0.785 mm ² and a wire diameter of 1.0 mm is used. The viscosity of methanol is 0.59 mPa, and the viscosity of methyl oleate is 5.5 mPa, which corresponds to a viscosity 9.3 times that of methanol.
First, iron naphthenate was weighed to a ratio of 10% by weight to methanol, and iron naphthenate was mixed with methanol and stirred to prepare a methanol dispersion of iron naphthenate. Next, it was mixed with a methanol dispersion of iron naphthenate so that methyl oleate was 20% by weight. The mixture is transferred to a vessel, and the vessel passes through a heat treatment apparatus, and is heated to 270 ° C. at a heating rate of 20 ° C./min in the air atmosphere, and then to 340 ° C. at a heating rate of 50 ° C./min. The temperature was raised, and left at 340 ° C. for 1 minute, and then returned to room temperature, after which methanol was mixed in the container so that the volume of the mixture became 4 times, to prepare a suspension.
Next, the bare copper single wire is dipped in the above suspension and taken out, then the heat treatment apparatus is moved, and the temperature is raised to 340 ° C. at a heating rate of 20 ° C./min in the air atmosphere, and further 1 ° C. The temperature was raised to 380 ° C. at a temperature rising rate of 1 / min, left at 380 ° C. for 30 minutes, and returned to room temperature. A bare copper single wire was taken out from the heat treatment apparatus, and a magnetic field of 12 kilooersteds was allowed to pass through the magnetic field generated along the length of the bare copper single wire to prepare a sample.
Furthermore, the surface and the cross section of the sample were observed with an electron microscope. The electron microscope used the ultra-low acceleration voltage SEM of JFE Techno Research Ltd. This device is capable of surface observation with an extremely low accelerating voltage from 100 V, and further has a feature that the surface of the sample can be observed directly without forming a conductive film on the sample.
First, the secondary electron beam between 900 and 1000 V of the reflected electron beam was taken out for image processing, and the sample surface was observed. The surface of the sample was evenly covered with particulate particles of 40-60 nm in size, and no defects were observed. Next, the energy of the characteristic X-ray and its intensity were subjected to image processing, and the types of elements constituting the film formed on the surface and their distribution states were analyzed. Since both iron atoms and oxygen atoms were uniformly present on the surface and no particularly uneven distribution was found, it was confirmed that they were fine particles of iron oxide. Furthermore, the EBSP analysis function was added to the function of ultra-low acceleration voltage SEM to analyze the crystal structure. From these results, it was confirmed that the fine particles formed on the sample surface were maghemite, which is the γ phase of ferric oxide. In the EBSP analysis function, when a sample is irradiated with an electron beam, reflected electrons are diffracted by atomic planes in the sample to form a band-like pattern, and the symmetry of this band corresponds to the crystal system. Since the band spacing corresponds to the atomic plane spacing, the function of measuring crystal orientation and crystal system by analyzing this pattern is said.
From the above observation results of the sample surface, it can be confirmed that the entire surface of the bare copper single wire is covered with fine particles of maghemite. From these results, it has been confirmed that when the iron naphthenate is heat-treated, magnetic particles of magnet fines uniformly adsorb to the surface of the bare copper single wire.
Next, the insulation resistance of the sample was measured. Using an insulation resistance meter of Kyoritsu Electric Instrument, the length of the sample was 1 m, and the electrical resistance between the bare single copper wire and the insulating layer was measured. The insulation resistance showed a value close to 1 MΩ. Therefore, it turned out that an insulating layer has the insulation resistance required for a wire.
Furthermore, the sample was continuously wound five times around a pipe having a diameter of 5 mm while changing the tension during winding, and the surface of the pipe after removing the sample was observed by SEM, but the presence of the maghemite fine particles was not recognized. Furthermore, the tension was changed so that the sample was triple-folded, and the pipe was continuously wound around the pipe five times continuously. After that, the surface of the sample was observed by SEM, but it was not different from the initial state. Moreover, in any case, no abnormality such as a crack was observed on the surface of the sample. Therefore, it was found that the fine particles of maghemite are strongly magnetically adsorbed. From these results, the sample can be used as a winding used for a coil.
Moreover, after exposing the pipe in which the sample was wound to -40 degreeC and 400 degreeC each for 30 minutes, although the sample surface was observed with SEM, it was not different from the initial state. From this result, it was found that it has cold resistance of -40 ° C, heat resistance of 400 ° C and excellent thermal shock resistance.
Next, the sample was cut into round slices and the cross section was observed by SEM. Twenty to twenty-two particulate particles of maghemite were stacked to cover the bare copper single wire. Accordingly, 20 to 22 maghemite fine particles are magnetically adsorbed to form an insulating layer having a thickness close to 1 μm. The cross section of the sample is schematically shown enlarged in FIG. 1 is a bare copper single wire and 2 is a maghemite fine particle.
Furthermore, the dielectric breakdown voltage was measured based on the dielectric breakdown test of the winding test method of JIS C 3216-1 using dielectric breakdown tester EB0181 of Tokyo Seiden Co., Ltd. As a result, the dielectric breakdown voltage of the sample was 12 kV. This insulation withstand voltage is equivalent to that of an enameled wire (for example, heat resistant enameled wire IMW of Hitachi Metals, Ltd.) having a polyimide insulation layer thickness of 0.035 mm and a bare copper single wire diameter of 1.0 mm. . On the other hand, the thickness of the insulating layer of the sample is only 1/35 of the thickness of the insulating layer of the heat-resistant wire, but has the same withstand voltage, so the insulating layer consisting of aggregation of maghemite particles has high withstand voltage I found that.
As described above, the sample is excellent in heat resistance, cold resistance, thermal shock resistance, dielectric breakdown voltage, flexibility, adhesion between the insulating layer and the conductor, abrasion resistance, and winding resistance. On the other hand, the sample is manufactured continuously by performing five steps consisting of the simple process described in the 13th paragraph in succession. In addition, the organic iron compounds described in the eighteenth paragraph, which are the raw materials of ferrous oxide, are iron carboxylate compounds which can be easily synthesized. Furthermore, the organic compound which comprises a suspension is also an organic compound which belongs to general purpose carboxylic acid esters. Therefore, an insulated wire with excellent performance can be manufactured continuously at low processing costs using inexpensive raw materials.

1 bare copper single wire 2 maghemite fine particles

The present invention relates to a manufacturing method for continuously manufacturing an insulated wire in which a conductor is insulated by a collection of fine particles in which saturated and magnetized maghemite fine particles are magnetically adsorbed.

A wire in which a conductor is covered with an insulator is called an insulated wire and is used in various applications. The conductor consists of a single or stranded wire. Moreover, the conductor has a round wire whose cross section has a substantially circular shape and a flat wire whose cross section is processed into a rectangular shape. Furthermore, although many of the conductors are made of copper or aluminum, copper alloys or aluminum alloys having high conductivity may be used if the merit of the alloy is greater than the disadvantage of the cost increase of the alloy material. A wire obtained by bundling a plurality of insulated wires and having a sheath (protective outer coating) outside is called a cable, and there are a metal communication cable for transmitting an electrical signal and an optical fiber cable for transmitting an optical signal.

Insulated wires consisting of round wires can be divided into wires for power transmission, distribution and wiring according to the allowable current. In addition, the electric wire used outdoors consists of a black insulating layer as a countermeasure against ultraviolet rays, and the standard of the service life by the Japan Wire Industry Association is 15 to 20 years.
Among the insulated wires for power transmission, there is a high voltage distribution line that delivers a voltage of more than 700 V DC, more than 600 V AC and less than 7 kV. The conductor is formed by twisting 7 to 19 strands, and the insulating layer is formed of a crosslinked polyethylene resin having a continuous maximum use temperature of 90 ° C. or a polyethylene resin having a continuous maximum use temperature of 75 ° C. There is also a high voltage service lead from the 3300-6600 V outdoor distribution line to the transformer on the pole. The conductor is formed by twisting seven strands, and the insulating layer is formed of a crosslinked polyethylene resin having a continuous maximum use temperature of 90 ° C. or an ethylene propylene rubber having a continuous maximum use temperature of 80 ° C. In addition, there are low voltage overhead wires used in low voltage distribution lines that use a transformer to drop power received from high voltage drop lines into single or three phases of 100V or 200V. The conductor is formed by twisting 7-19 strands, and the insulating layer is made of a vinyl resin having a continuous maximum operating temperature of 60.degree.
Among the insulated wires for power distribution, there is a low voltage lead-in wire used for an overhead lead-in wire for drawing electricity from a utility pole into a building. The conductor is formed by twisting 7-19 strands, and the insulating layer is made of a vinyl resin having a continuous maximum operating temperature of 60.degree.
Insulated wires for wiring vary widely depending on the final use place, but the main insulated wires include indoor wiring in buildings. Most of the indoor wiring is low voltage indoor wiring up to 600 V, the conductor is made by twisting seven strands, and the insulating layer is made of vinyl resin having a continuous maximum operating temperature of 60 ° C. In addition, the standard of the useful life of the indoor by the Japan Wire Industry Association is 20-30 years.

Furthermore, there is a coil (also referred to as a magnet wire) that uses an insulated wire made of a round wire for a coil, a motor, a plunger, a relay, and an electrical component of a car. The winding includes an enameled wire for applying and baking an insulating material, a transverse winding for winding a fiber, a film, a tape, a paper, a thread and the like, and an electric wire combining these. Enamel wire is divided by the heat resistance temperature of the insulating layer, polyvinyl formal copper wire of 105 ° C, polyurethane copper wire of 120 ° C, polyester copper wire of 155 ° C, polyesterimide copper wire of 180 ° C, polyamideimide copper wire of 200 ° C, There is a polyimide copper wire at 220 ° C. The insulating layer of the winding requires various performances such as dielectric breakdown, wear resistance, solvent resistance, chemical resistance, oil resistance, hydrolysis resistance, thermal shock resistance, heat resistance life and the like. Depending on the equipment in which the round wire is used, the environment to be used and the load to be applied largely change, and thereby the performance required for the insulating layer also changes greatly. In particular, the windings used for various electrical components mounted on automobiles have high required performance.

On the other hand, flat conductors with a relatively small aspect ratio are produced by wire drawing, and those with a large aspect ratio are produced by rolling of a round wire or slitting of a rolled sheet. Therefore, the processing cost to the flat wire can be low. The flat wire has an insulating layer on the surface, and when used as a coil winding or as a coil, the cross-sectional area ratio of the conductor in the cross-sectional area of the coil becomes higher than that of the round wire, resulting in miniaturization It is used as a winding or coil in various electric and electronic parts that require high performance.
That is, flat conductors are used in consumer devices as personal computers, televisions, control circuits, etc., as surface mount coils, as tablet terminals, smart phones, etc., as small surface mount coils. In automobiles, coils are used as coils for electric vehicles such as drive motors for hybrid vehicles, motors for electric compressors, motors for electric power steering, wiper motors, alternators, starters, ignition coils and the like. Moreover, it is used as a winding of various motors, such as an industrial motor, a motor for household appliances, and a small motor. In addition, various coils such as relay coils and clutch coils are used as coils of various transformers such as transformers for electric power, transformers for lighting equipment, and small transformers.
On the other hand, the insulating layer of the flat wire needs various performances such as insulation breakdown, wear resistance, solvent resistance, chemical resistance, oil resistance, hydrolysis resistance, thermal shock resistance, heat resistant life, etc. Depending on the equipment used, the environment to be used and the load to be applied may be largely changed, which in turn greatly changes the performance required for the insulating layer. Similar to the windings, the windings used for various electrical components mounted in automobiles have high required performance.
Also, the thickness and width of the flat wire vary depending on the device in which the flat wire is used. For example, in the case of an extremely thin rectangular wire used for a small surface mount coil, the conductor thickness is 0.02 mm, the conductor width is 0.1 to 0.3 mm, and the thickness of the insulating layer is only 0.005 mm. On the other hand, in a general rectangular wire, the conductor thickness is 0.8-1.0 mm, the conductor width is 1.7-3.5 mm, and the thickness of the insulating layer is 0.05 mm. Thus, the thickness of the insulating layer changes by one digit according to the thickness of the conductor. Also, the coil spacing varies by an order of magnitude depending on the conductor thickness.
Furthermore, there are various shapes of coils using flat wire. For example, an edgewise coil obtained by bending a flat wire in a width direction which is difficult to bend has shapes such as a rectangular edgewise coil, a circular edgewise coil, an oval edgewise coil, an elliptical edgewise coil, etc. There are coils of various shapes such as a tortoise shell coil wound in a loop shape and a toroidal coil wound in a toroidal shape.

As explained above, insulated wires are used in different applications and in different environments, and different loads are applied to the insulating layer. Therefore, the performance required for the insulating layer varies depending on the application. Therefore, there is no insulating layer that fulfills all the performances of all the insulated wires in one kind of insulating layer. In addition, the conductor thickness and the conductor width of the flat wire largely change depending on the application. Thus, there is no insulating layer that can accommodate all conductor thicknesses and conductor widths.

For example, according to Patent Document 1, when forming an insulating layer by electrodeposition coating on a coil made of a flat wire, the coil is stretched by opening a plurality of winding portions in advance in an elastic deformation region of the coil. It is described that the insulating layer is formed by maintaining the state and performing the electrodeposition coating process and the baking process in the extended state.
However, the process of maintaining the stretched state by opening the coil windings is required, which increases the cost of forming the insulating layer. Furthermore, a coil with a spacing of only 0.01 mm between the turns of the coil can not be maintained in an extended state with a spacing between the turns. Therefore, the insulating layer can be formed only on the limited coil.

In patent document 2, in order to make the thermal expansion coefficient of an insulating layer close to the thermal expansion coefficient of copper and to improve a thermal shock resistance, the composite material of spherical silica and polyphenylene sulfide resin is extruded and an insulating film is formed on a flat wire. It is described.
However, since spherical silica having an average particle diameter of 0.5 to 10 μm is compounded with the dissolved PPS resin at a volume ratio of 25 to 32%, the compounding ratio of spherical silica is increased, that is, the composite material The closer the coefficient of thermal expansion to copper, the lower the flexibility of the composite. When a coil is formed using a winding insulated with such a composite material, the insulating layer is cracked at the bend and can not be processed into a coil. Therefore, the application of the winding which is limited to the use of the winding which does not require bending, and which can be used is very narrow.
The thermal expansion coefficient of the spherical silica is 0.55 × ^{10 -6} / K, a thermal expansion coefficient of the PPS resin is 49-55 × ^{10 -6} / K, the thermal expansion coefficient of copper is 16.8 × 10 ^{- Since} it is ⁶ / K, in order to make the coefficient of thermal expansion of the composite material match the coefficient of thermal expansion of copper, it is necessary to increase the mixing ratio of silica spheres to a volume ratio of 2/3. However, as the proportion of the silica spheres is increased, the viscosity of the composite material increases and extrusion becomes difficult. In addition, the abrasion of the extruder becomes remarkable. Therefore, since the blending ratio of spherical silica is limited, the thermal expansion coefficient of the composite material is also limited. Therefore, there is a limit to the improvement of the thermal shock resistance of the insulating layer made of a composite material.

In Patent Document 3, a varnish used for electrodeposition coating is used in order to make the thickness of the insulating layer in the portion corresponding to the short side in the cross sectional shape of the flat wire larger than the thickness of the insulating layer in the portion corresponding to the long side. It is described that it comprises a resin for coating, water and a water-soluble solvent.
However, the insulating layer is required to have various performances such as insulation breakdown, wear resistance, solvent resistance, chemical resistance, oil resistance, hydrolysis resistance, thermal shock resistance, heat resistance life, etc. Even if the target insulating layer can be formed with such a varnish, the performance of the insulating layer is restricted by the water-soluble resin, and the use of the flat wire is limited.

Patent Document 4 describes an insulated wire in which a plurality of insulating layers are formed by an insulating paint having a low dielectric constant. That is, for example, due to the influence of the inverter surge voltage, partial discharge accompanied by dielectric polarization occurs on the surface of the insulating layer as the insulating layer has a larger dielectric constant, and the insulating layer is eroded due to deterioration due to partial discharge. Breakdown occurs. Therefore, in the inner first layer, a low dielectric constant polyesterimide resin having a dielectric constant of less than 3.8, a low dielectric constant polyamideimide resin having a dielectric constant of less than 4.0, or a dielectric constant of less than 3.2 The low dielectric constant insulating paint mainly composed of any one kind of low dielectric constant polyimide resin is baked and painted, and any one kind of polyester imide resin, polyamide imide resin, or polyimide resin is mainly used as the second layer. At the same time, it is described that a low dielectric constant insulating paint containing inorganic fine particles as a secondary component is baked and coated.
On the other hand, the insulating material most excellent in conventional arc resistance and tracking resistance is a silicone varnish having a dielectric constant of 3.1 to 3.2. However, even silicone varnishes have limitations on arc resistance and tracking resistance. Therefore, even if the low dielectric constant insulating paint described in Patent Document 4 is used, arc resistance and tracking resistance are limited. Furthermore, the first layer and the second layer are separately baked and coated, and interfaces made of different materials are not fused due to the difference in melting point, and gaps due to layer separation are formed in the interfaces. When such a gap is present, partial discharge occurs in the gap. In the repetition of this discharge, the insulator is gradually eroded and eventually leads to dielectric breakdown. In addition, the manufacturing cost is increased as compared with the conventional insulating layer consisting of a single layer.

JP, 2017-115242, A JP, 2014-029779, A JP, 2017-016956, A JP, 2016-181344, A

As described in the patent documents described above, the described techniques are effective only for limited applications and are not universal. Therefore, there is no insulating layer that fulfills all the performances of all the insulated wires in one kind of insulating layer.
In the present invention, regardless of the environment in which the insulated wire is used, and whether the wire is a single wire, a stranded wire or a flat angle wire, regardless of the wire, the flat angle Regardless of the conductor thickness of the conductor, the conductor width, and regardless of the size of the coil winding interval, it is superior to the conventional performance for all the wires, and it is continuous in an inexpensive manufacturing method. It is an object of the present invention to realize a method of manufacturing an insulated wire.

Manufacturing method for continuously producing insulated wires, conductors, and the first step particles of ferrous oxide to an organic compound that is diluted with alcohol you pass immersed in the suspension dispersed, conductor comprises a second step you over through the first heat treatment apparatus is heated to a temperature for vaporizing said organic compound from room air atmosphere, the conductor is, the ferrous oxide in the atmosphere atmospheric particles and the second heat treatment apparatus move third you steps to be heated to a temperature which is oxidized to fine particles of maghemite, conductor is, the magnetic field the magnetization of the maghemite particles is saturated occurs a fourth step you over through the space atmosphere consists fifth step of winding the conductor, insulated production process be carried out continuously these five steps, the conductor is a collection of maghemite particles Manufacturing method to continuously manufacture insulated wires That.

That is, when the conductor is immersed in the suspension and passes through the suspension, the suspension adheres to the conductor with a thickness corresponding to the viscosity of the suspension. Therefore, regardless of whether the conductor is a round conductor consisting of a single wire or a stranded wire or a flat angle conductor, the thickness of the single wire, the number of strands, the conductor thickness of the flat wire, the conductor width Also, regardless of the type of conductor, the suspension adheres at a thickness corresponding to the viscosity of the suspension. Thereafter, the conductor is moved through the first heat treatment apparatus to raise the temperature, and after alcohol is vaporized from the suspension, the organic compound is vaporized, and ferrous oxide (represented by the chemical formula of FeO) is formed on the surface of the conductor. A collection of particles adheres. Furthermore, the conductor moves to the second heat treatment apparatus, is left for a certain time, and all ferrous oxide divalent iron ions (Fe ²⁺ ) are oxidized to trivalent iron ions (Fe ³⁺ ), ferrous is oxidized to maghemite (represented by the chemical formula of _γ-Fe 2 _{O 3} in the gamma phase of ferric oxide _Fe 2 _{O 3)} oxide. As a result, the conductor is covered with a collection of magnetically adsorbed maghemite fine particles. Furthermore, the conductor passes through the space where the magnetic field is generated, the magnetization of the maghemite particles is saturated, the conductors are covered with a collection of maghemite particles in which the saturated magnetizations are magnetically adsorbed, and the insulating layer is composed of a collection of maghemite particles. It is formed on a conductor. After this, the conductor is wound up. Thus, the insulated wire is continuously manufactured.
The manufacturing method of the above-mentioned insulated wire brings about the outstanding effect by the following features.
First, since all five steps are treated in the atmosphere, the five steps can be carried out continuously. Thereby, the insulated wire can be manufactured continuously. In addition, all five processes are extremely simple processes, and insulated wires are continuously manufactured at low cost.
In addition, a plurality of single-wire or stranded-wire conductors or a plurality of flat-angle conductors are moved in parallel at intervals, and the above-mentioned five steps are continuously carried out. It can be manufactured continuously. This further reduces the cost of manufacturing the insulated wire.
Second, in the first step, the thickness of the insulating layer is determined by the viscosity of the suspension, and the viscosity of the suspension can be changed in any way by the dilution rate of alcohol. By this, the thickness of the insulating layer can be changed in any way. That is, as described in the fifth paragraph, the thickness and width of the flat conductor greatly vary depending on the device in which the flat conductor is used, whereby the thickness of the insulating layer changes by one digit according to the conductor thickness, and the flat conductor The spacing of the coils using V varies by an order of magnitude depending on the conductor thickness. Therefore, the suspension is made of an organic compound diluted with alcohol so that the thickness of the insulating layer can be easily changed by one digit, and the viscosity of the suspension can be changed by one digit at the dilution rate of alcohol. Thereby, the thickness of the insulating layer can be changed in any way, and the insulated wire can be used as a winding for any coil. Therefore, when used as a winding in which the distance between turns of the coil is narrow, the dilution rate of alcohol is increased. For example, the insulating layer can be formed even for a winding in which the distance between turns of the coil is narrow and the thickness of the insulating layer is only 0.005 mm.
Thirdly, by conducting the fourth step as the step of saturating the magnetization of the maghemite fine particles, the conductor insulated in the fifth manufacturing step can be wound up, whereby the insulated wire is continuously formed. It can be manufactured. That is, the wound up insulated wire receives magnetic attraction from the insulating layer of the adjacent insulated wire. However, since maghemite fine particles having magnetizations saturated in the same direction magnetically adsorb each other, the magnetic attractive force of the maghemite fine particles forming the insulating layer is larger than the magnetic attractive force received from the insulating layer of the adjacent insulated wire. For this reason, the magnetite particulates of the insulating layer are not pulled up by the magnetic attraction force from the insulating layer of the adjacent insulated wire, and the insulated wire can be wound up by this. Furthermore, the magnetic Curie point of maghemite is 675 ° C, and phase transition is gradually made to hematite (shown by the chemical formula of α-Fe ₂ O ₃ ), which is the α phase of ferric oxide, at a temperature of 450 ° C or higher in the atmosphere. . This phase transition is an irreversible change. Therefore, the magnetic adsorption force of the maghemite fine particles has a heat resistance close to 450 ° C. Therefore, the wound insulated wire can be left at high temperature for a long time.
Fourth, by making the magnetization of the maghemite fine particles saturate in the fourth step, the insulated wire can be wound as a winding for any coil. That is, since a large load is applied to the insulating layer when the insulated wire is used as a winding, the magnetization of the maghemite fine particles is saturated. That is, the maghemite fine particles are not separated from a collection of maghemite fine particles in which the maghemite fine particles are particulate fine particles having a very small mass of 10 to 100 nm and adjacent granular fine particles magnetically adsorbed with saturated magnetization. . Therefore, when winding the insulated wire as a winding around various coils, a load is applied to the collection of maghemite fine particles, but the collection of the magnetically adsorbed maghemite fine particles is only temporarily deformed, so that the insulating layer can The particles are not pulled off. Furthermore, compared with the diameter of the conductor, the thickness of the insulating layer is as small as three digits, and the insulated wire can be wound even for a coil having a small winding interval. Also, the deformed insulating layer returns to its original shape by magnetic attraction, and the insulating layer has excellent flexibility. Furthermore, as described above, since maghemite has heat resistance close to 450 ° C., the coil also has heat resistance close to 450 ° C. Moreover, the pinhole size of the conventional insulating layer is three orders of magnitude larger than that of the maghemite fine particles, and even if the thickness of the insulating layer is thin, the pinhole which is an electrical weak point is the insulating layer to which the maghemite fine particles are magnetically adsorbed. not exist.
Furthermore, the insulated wire manufactured by the above manufacturing method has an effect that all performances required for the insulating layer are significantly improved over the performance of the insulating layer of the conventional insulated wire.
First, maghemite is a ferromagnetic material with spontaneous magnetization. For this reason, the maghemite fine particles magnetically adsorb to each other. Furthermore, when the magnetization of the maghemite fine particles is saturated, the magnetization is saturated in the same direction, and the magnetic attraction between the maghemite fine particles is significantly increased. Thereby, as described above, the insulated wire can be wound up, and the insulated wire can be used as a winding for any coil.
Second, the magnetic Curie point of maghemite is 675 ° C, and it gradually phase-transfers to hematite at a temperature of 450 ° C or higher in the atmosphere. Therefore, the magnetic adsorption power of the maghemite fine particles has heat resistance close to 450 ° C. On the other hand, among polymer materials used for the insulating layer, polyamideimide resin is the polymer material having the highest heat resistance, the softening point of the polyamideimide resin is 270 ° C., and the heat resistance temperature is 270 of the softening point. ° C. Accordingly, the heat resistance temperature of the insulated wire is improved by 150 ° C. or more than the heat resistance temperature of the conventional insulating layer, and the heat resistance life is also significantly extended.
Third, even if the temperature of the insulated wire changes, the magnitude of thermal expansion and thermal contraction of the maghemite fine particles having a size of 10 to 100 nm is extremely small, and the maghemite fine particles hardly thermally expand and shrink. For this reason, the insulating layer also hardly thermally expands and contracts. Also, since the magnetic Curie point of maghemite is high, if the temperature of the insulated wire is lower than 450 ° C., the magnetic attraction hardly changes. Therefore, even if the temperature of the device on which the insulated wire is mounted changes rapidly, no thermal stress is generated in the maghemite fine particles. As a result, the thermal shock resistance of the insulated wire is significantly improved over the conventional insulated wire.
Fourth, maghemite is an insulator having a specific resistance of 10 ⁶ Ωm and a relative dielectric constant of 1.6 to 1.8. Among the conventional insulating layers, the dielectric constant of the silicone varnish which is most excellent in arc resistance and tracking resistance is 3.1-3.2. For this reason, the insulating layer formed of a collection of maghemite fine particles is remarkably excellent in arc resistance and tracking resistance than silicone varnish. Therefore, the dielectric breakdown of the insulating layer is significantly improved over the conventional insulating layer. In the insulating layer, there are many holes of several nano-sized size surrounded by the maghemite fine particles. However, since the size of the pores is three orders of magnitude smaller than the void (bubble) generated by baking coating of the conventional insulating paint, and the dielectric constant of the maghemite fine particles surrounding the pores is low, partial discharge to the pores Does not happen. Therefore, even if this insulated wire is used for the motor of inverter control, partial discharge erosion by the inverter surge does not occur in the insulating layer, and the dielectric breakdown does not occur. In addition, even if the thickness is significantly thinner than the conventional insulating layer, no dielectric breakdown occurs. For this reason, it can be used as a winding in which the thickness of the insulating layer is only 0.005 mm, as in the case of an ultra-fine rectangular wire used for a small surface mount coil. The relative dielectric constant of the above-described polyamideimide resin has a high value of 3.8 to 4.1.
Fifth, maghemite is an inorganic substance consisting of a very stable black metal oxide and is known as a substance that forms a passive film of iron. Therefore, it does not react at all with any solvent, acid, alkali, naphtha, kerosene, gasoline, etc. at all. In addition, all the liquid can not penetrate into the collection of magnetically adsorbed maghemite fine particles, that is, the insulating layer by surface tension. For this reason, solvent resistance, chemical resistance and oil resistance are superior to conventional insulating layers. Also, does not hydrolyze, it does not occur even call-degradation does not occur deterioration due to ultraviolet rays. In addition, the insulating layer hardly causes thermal expansion and thermal contraction. Therefore, the insulating layer does not cure at low temperatures and does not soften at high temperatures, as in conventional polymeric materials. Therefore, the insulating layer is not weakened even if it is left at a very low temperature for a long time, and the insulating layer is not thermally deteriorated even if it is left at high temperature for a long time.
Sixth, it has a Mohs hardness of 6.5, which is a significantly harder material than electromagnetic steel sheet, and does not wear when it comes in contact with other parts or substrates. In addition, since the insulating layer is deformed temporarily only slightly when it contacts, it does not attack the contacted component or the base material. On the other hand, when the insulated wire is wound around the device as a winding, a load is applied to the collection of maghemite fine particles, but the maghemite fine particles are granular fine particles, and the granular fine particles slip slightly at the contact site. Particulates are not destroyed by contact. Therefore, the wear resistance is significantly improved over the conventional insulating layer. For this reason, the surface of the insulating layer is scratched by abrasion, and a partial discharge is generated therefrom, which does not lead to dielectric breakdown.
As described above, the insulated wire insulated with a collection of maghemite particles in which the magnetite particles of the maghemite particles are magnetically adsorbed with saturation magnetization is independent of the environment in which the insulated wire is used, and the wire is a single wire. Regarding all the wires regardless of the wire thickness of the flat wire, regardless of the wire thickness regardless of the wire whether it is a wire, a stranded wire, a round wire or a flat wire The required performance is significantly improved over conventional insulated wires. Furthermore, since the insulated wire having such excellent performance is continuously manufactured by continuously performing the above-described five simple steps, the manufacturing cost of the insulated wire is low. As a result, the problems described in the 12th paragraph were solved.

The production method for producing the suspension described in paragraph 13 comprises: a first step of dispersing an organic iron compound that precipitates ferrous oxide by thermal decomposition in alcohol to form an alcohol dispersion, and dissolving it in the alcohol The first property to be miscible, the second property having a viscosity higher than that of the alcohol, and the boiling point is higher than the thermal decomposition temperature of the organic iron compound, and the temperature at which the ferrous oxide is oxidized to maghemite A second step of mixing an organic compound having a low third property with the alcohol dispersion to form a mixture, and raising the mixture to a temperature at which the organic iron compound is thermally decomposed in an air atmosphere. An organic compound comprising: a third step of warming; and a fourth step of mixing the alcohol with the heat-treated mixed solution, the method of continuously carrying out these four steps comprising: Particles of ferrous oxide is a method of manufacturing the suspension dispersed in.

That is, when the organic iron compound which precipitates ferrous oxide by thermal decomposition is dispersed in alcohol, the organic iron compound is uniformly dispersed in the alcohol. Next, when an organic compound having three properties is mixed in an alcohol dispersion, the organic compound dissolves or mixes with the alcohol, the organic iron compound is uniformly dispersed in the mixture, and a mixture having a viscosity higher than that of the alcohol is obtained. . Further, the mixture is heated to the thermal decomposition temperature of the organic iron compound in the air atmosphere. First, the alcohol is vaporized to precipitate fine crystals of the organic iron compound in the organic compound. The size of the fine crystals is close to the size of the ferrous oxide fine particles. Furthermore, if the boiling point of the organic acid which comprises an organic iron compound is exceeded, an organic iron compound will decompose | disassemble into an organic acid and ferrous oxide. When the temperature is further raised, the vaporization of the organic acid proceeds, and when the vaporization of the organic acid is completed, particulate microparticles of ferrous oxide precipitate in the organic compound. The ferrous oxide is a nonmagnetic substance, and the fine particles are not magnetically adsorbed, and are uniformly dispersed in the organic compound. The suspension is diluted with alcohol to produce a suspension of ferrous oxide microparticles dispersed in an alcohol-diluted organic compound.
The above organic iron compounds and organic compounds are general-purpose industrial chemicals and inexpensive. In addition, since all of the four steps are treatment in the air atmosphere, the four steps can be performed continuously. For this reason, a suspension can be manufactured at low cost using inexpensive chemicals as raw materials.

Method of manufacturing a suspension as described in 15 paragraphs, as the organic iron compound, using acid iron compound oxygen ions constituting the carboxyl group is coordinated to an iron ion, as the organic compound, carboxylic acid It is a manufacturing method which manufactures a suspension according to the manufacturing method which manufactures the above-mentioned suspension using the organic compound which belongs to ester .

That is, an iron carboxylate compound in which an oxygen ion (O ⁻ ) constituting a carboxyl group becomes a ligand and approaches a divalent iron ion (Fe ²⁺ ) to coordinate bond is a ferrous oxide by thermal decomposition. Precipitate out. Therefore, when the organic iron compound described in the 16th paragraph is composed of an iron carboxylate compound and the liquid mixture in which the iron carboxylate compound is dispersed is heat-treated in the atmosphere, the iron carboxylate compound is thermally decomposed at a temperature lower than 350 ° C. A collection of particulate ferrous oxide particulates falling in the range of 10-100 nm in size precipitates in the organic compound. The suspension is diluted with alcohol to produce the suspension described in paragraph 16.
That is, an iron carboxylate compound in which an oxygen ion constituting a carboxyl group becomes a ligand and approaches a divalent iron ion and coordinates is coordinated with an oxygen ion approaching an iron ion which is the largest ion. Because of the coupling, the distance between the two becomes short. As a result, the distance between the oxygen ion coordinated to the iron ion and the ion covalently bonded to the opposite side of the iron ion is maximized. The iron carboxylate compound having such a molecular structural feature is bound to an ion in which the oxygen ion constituting the carboxyl group is covalently bonded on the opposite side of the iron ion when the boiling point of the carboxylic acid constituting the iron carboxylate compound is exceeded. The part is first divided and decomposed into ferrous oxide, which is a compound of iron ion and oxygen ion, and carboxylic acid. When the temperature is further raised, the carboxylic acid takes heat of vaporization and is vaporized, and after vaporization of the carboxylic acid is completed, ferrous oxide is deposited.
As such an iron carboxylate compound, there are an iron acetate compound, an iron caprylate compound, an iron benzoate compound, and an iron naphthenate compound in the order of molecular weight. In all of iron acetate, iron caprylate and iron benzoate, oxygen ions approach iron ions and coordinate bond to form a dinuclear complex salt. On the other hand, the substances produced in the course of thermal decomposition are the most stable substances produced in the thermal decomposition of iron naphthenate. For this reason, iron naphthenate is the simplest heat treatment for depositing ferrous oxide by thermal decomposition of the iron carboxylate compound. Naphthenic acid is a mixture of saturated fatty acids having a 5-membered ring and is represented by a general formula consisting of C _n H _{2 n-1} COOH, the main component having a boiling point of 268 ° C. and a molecular weight of 170 C ₉ H ₁₇ COOH Become. Therefore, the thermal decomposition of iron naphthenate is completed at 340 ° C. in the air atmosphere to precipitate ferrous oxide.
Furthermore, the above-mentioned iron carboxylates are inexpensive industrial chemicals that can be easily synthesized. That is, when a general purpose carboxylic acid is reacted with a strong alkali, a carboxylic acid alkali metal compound is formed. Thereafter, an alkali metal carboxylate compound is reacted with an inorganic iron compound to synthesize an iron carboxylate compound. In addition, since the carboxylic acid as the raw material is an organic acid having a relatively low boiling point among the boiling points of the organic acid, fine particles of ferrous oxide are contained in the organic compound by heat treatment lower than 350 ° C. in the atmosphere. It precipitates.
As described above, a metal carboxylate compound which is an inexpensive raw material and which deposits ferrous oxide by thermal decomposition is suitable as the organic iron compound described in the 16th paragraph.
In addition, carboxylic acid esters are first dissolved or mixed in alcohol, secondly higher in viscosity than the alcohol, thirdly higher in boiling point than the thermal decomposition temperature of the organic iron compound, and first oxidized Organic compounds that combine these three properties below the temperature at which iron is oxidized to maghemite are present in the organic compounds belonging to carboxylic esters. In addition, such carboxylic esters are general-purpose industrial chemicals used for fiber oil agents, metal oil agents, synthetic lubricating oils, synthetic resins, cosmetics, and surfactants .
Therefore, when the carboxylic acid esters having three properties are mixed with the alcohol dispersion of the organic iron compound described in the 16th paragraph, the carboxylic esters are dissolved or mixed in the alcohol, and the viscosity is higher in the 16th stage than the alcohol. The described mixture is made .
For this reason, carboxylic acid esters are suitable as the organic compound described in the 16th paragraph .

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FIG. 6 is an explanatory view schematically illustrating a cross section covered with a collection of maghemite fine particles to which a copper wire is magnetically adsorbed.

Embodiment 1
In this embodiment, using iron naphthenate as the organic iron compound, the suspension described in the 16th paragraph is prepared, and the conductor to which the suspension is attached is heat-treated to form the insulating layer on the conductor. Do.
Iron naphthenate is a complex in which an oxygen ion constituting a carboxyl group of naphthenic acid becomes a ligand, approaches a divalent iron ion, and coordinates to a divalent iron ion. That is, since the oxygen ion approaches and coordinates with the divalent iron ion which is the largest ion, the distance between the two becomes short. As a result, the distance between the oxygen ion coordinated to the divalent iron ion and the ion covalently bonded to the opposite side of the iron ion is maximized. When iron naphthenate having such a molecular structural feature exceeds the boiling point of the main component of naphthenic acid, an ion in which an oxygen ion constituting a carboxyl group in iron naphthenate is covalently bonded on the opposite side of a divalent iron ion At first, the bond portion with is decomposed to decompose into ferrous oxide and naphthenic acid, which are compounds of divalent iron ions and oxygen ions. When the temperature is further raised, naphthenic acid takes heat of vaporization and is vaporized, and when vaporization of naphthenic acid is completed, ferrous oxide is precipitated and thermal decomposition is finished. For this reason, iron naphthenate is an organic iron compound which precipitates ferrous oxide by the thermal decomposition described in the sixteenth paragraph.
When iron naphthenate is dispersed in alcohol, iron naphthenate is uniformly dispersed in the alcohol. Next, when the organic compound having the three properties described in the sixteenth paragraph is mixed with the alcohol dispersion, the organic compound is dissolved or mixed with the alcohol, and a mixed solution having a viscosity higher than that of the alcohol is produced. Further, the temperature of the mixture is raised by the first heat treatment apparatus. First, the alcohol is vaporized to precipitate fine crystals of iron naphthenate in the organic compound. Next, if it exceeds 268 ° C. which is the boiling point of the main component of naphthenic acid, iron naphthenic acid is decomposed into naphthenic acid and ferrous oxide. Thereafter, the temperature rising rate is increased to vaporize naphthenic acid, and particulate particles of ferrous oxide precipitate in the organic compound at 340 ° C. at which the vaporization is completed. The ferrous oxide is a nonmagnetic substance, and the fine particles of ferrous oxide are not magnetically adsorbed to one another, and uniformly dispersed in the organic compound. The suspension is diluted with alcohol to form a suspension.
Next, the conductor is immersed in the suspension and passed, and in the second heat treatment apparatus, the temperature rising rate is suppressed in the air atmosphere, the temperature is raised from 340 ° C. to 380 ° C., and it is left at 380 ° C. for a fixed time. At this time, an oxidation reaction proceeds in which divalent iron ions of ferrous oxide become trivalent iron ions. At the initial stage of this oxidation reaction, part of the divalent iron ions of ferrous oxide (FeO) becomes trivalent iron ions to form ferric oxide (Fe ₂ O ₃ ), and the composition formula is FeO ·· It is oxidized to magnetite of Fe ₂ O ₃ . Furthermore, when it is left for a long time, the oxidation reaction proceeds further, and all of the ferrous oxide is oxidized to magnetite. Further, if the standing is extended, all of the divalent iron ions constituting magnetite become trivalent iron ions, become ferric oxide, and complete the oxidation reaction. The ferric oxide is maghemite (γ-Fe ₂ O ₃ ), which is a gamma system of ferric oxide, which is a cubic system similar to magnetite. On the other hand, the crystal structure of hematite (α-Fe ₂ O ₃ ), which is the alpha phase of ferric oxide, is a trigonal system, and the crystal structure is different from that of magnetite. As a result, the conductor is covered with a collection of magnetically adsorbed maghemite fine particles. Furthermore, when the conductor passes a magnetic field that saturates the magnetization of the maghemite particles, an insulated wire is manufactured.
In addition, iron naphthenate is an inexpensive industrial chemical that can be easily synthesized, as described in the eighteenth paragraph, and is one of the least expensive compounds among organic acid iron compounds. In addition, since naphthenic acid as a raw material has a relatively low boiling point among the boiling points of organic acids, ferrous oxide is precipitated by heat treatment at about 340 ° C. in the air atmosphere. Naphthenic acid having such properties is widely used in paint / printing ink driers, rubber / tire adhesives, lubricant extreme pressure agents, polyester curing agents, flame retardants, polymerization catalysts, etc. There is.

Embodiment 2
In this embodiment, first, it is dissolved or mixed with alcohol, secondly, its viscosity is higher than that of the alcohol, and third, its boiling point is higher than the thermal decomposition temperature of the organic iron compound, and ferrous oxide is maghemite The organic compound combines these three properties below the temperature at which it is oxidized. Here, the boiling point of the organic compound is required to be higher than 340 ° C. and lower than 380 ° C. in order to use the organic iron compound as iron naphthenic acid. Also, methanol, which is the most versatile industrial alcohol, is used as the alcohol.
Among the organic compounds that combine these three properties, there are organic compounds belonging to carboxylic esters. On the other hand, three kinds of carboxylic acid esters consist of a first ester consisting of saturated carboxylic acid, a second ester consisting of unsaturated carboxylic acid, and a third ester consisting of aromatic carboxylic acid. Can be divided into esters of

Among the esters consisting of the first saturated carboxylic acid, carboxylic acid esters which are dissolved in methanol and whose viscosity is higher than the boiling point of methanol and whose boiling point falls within the range of 340-380 ° C. have higher molecular weight than capric acid esters. Present in esters. Among the laurates, only octyl laurate having a boiling point of 355 ° C. is relevant. There is no corresponding ester in myristic esters. The boiling point of ethyl myristate is 295 ° C., and the boiling point of butyl myristate is 389 ° C. Further, among palmitic acid esters, only butyl palmitate having a boiling point of 362 ° C. corresponds. Further, among stearic esters, only propyl stearate having a boiling point of 376 ° C. is applicable.

Among the esters composed of the second unsaturated carboxylic acid, carboxylic acid esters which are dissolved in methanol and whose viscosity is higher than the boiling point of methanol and whose boiling point falls within the range of 340 to 380 ° C. are oleic acid esters and linoleic acid esters And linolenic acid esters. Among oleic acid esters, methyl oleate having a boiling point of 351 ° C. corresponds, and among linoleic acid esters, methyl linoleate having a boiling point of 373 ° C. corresponds, and among linolenic acid esters, a boiling point There is 364 ° C of methyl linolenate.

Among esters composed of a third aromatic carboxylic acid, carboxylic acid esters which are dissolved in methanol and whose viscosity is higher than the boiling point of methanol and which has a boiling point of 340-380 ° C. are slightly present in phthalic acid esters. And the boiling point of dihexyl phthalate is 350 ° C.

Example 1
In Example 1, according to Embodiment 1, a method of forming an insulating layer on a copper wire with a collection of fine particles of magnetite is described. The naphthenic acid iron used the naphthenic acid iron (For example, the product of Toei Kako Co., Ltd.) marketed as metal soap. As the organic compound, methyl oleate having a boiling point of 351 ° C. (for example, a product of Wako Pure Chemical Industries, Ltd.) was used. Methyl oleate is used in synthetic fiber oils, metal oils, synthetic lubricants, synthetic resins, cosmetics, and surfactant raw materials. As methanol, a first-grade reagent was used. As a conductor, a bare copper single wire (for example, a product of Fukuda Electric Wire Co., Ltd.) having a cross-sectional area of 0.785 mm ² and a wire diameter of 1.0 mm is used. The viscosity of methanol is 0.59 mPa, and the viscosity of methyl oleate is 5.5 mPa, which corresponds to a viscosity 9.3 times that of methanol.
First, iron naphthenate was weighed to a ratio of 10% by weight to methanol, and iron naphthenate was mixed with methanol and stirred to prepare a methanol dispersion of iron naphthenate. Next, it was mixed with a methanol dispersion of iron naphthenate so that methyl oleate was 20% by weight. The mixture is transferred to a vessel, and the vessel passes through a heat treatment apparatus, and is heated to 270 ° C. at a heating rate of 20 ° C./min in the air atmosphere, and then to 340 ° C. at a heating rate of 50 ° C./min. The temperature was raised, and left at 340 ° C. for 1 minute, and then returned to room temperature, after which methanol was mixed in the container so that the volume of the mixture became 4 times, to prepare a suspension.
Next, the bare copper single wire is dipped in the above suspension and taken out, then the heat treatment apparatus is moved, and the temperature is raised to 340 ° C. at a heating rate of 20 ° C./min in the air atmosphere, and further 1 ° C. The temperature was raised to 380 ° C. at a temperature rising rate of 1 / min, left at 380 ° C. for 30 minutes, and returned to room temperature. A bare copper single wire was taken out from the heat treatment apparatus, and a magnetic field of 12 kilooersteds was allowed to pass through the magnetic field generated along the length of the bare copper single wire to prepare a sample.
Furthermore, the surface and the cross section of the sample were observed with an electron microscope. The electron microscope used the ultra-low acceleration voltage SEM of JFE Techno Research Ltd. This device is capable of surface observation with an extremely low accelerating voltage from 100 V, and further has a feature that the surface of the sample can be observed directly without forming a conductive film on the sample.
First, the secondary electron beam between 900 and 1000 V of the reflected electron beam was taken out for image processing, and the sample surface was observed. The surface of the sample was evenly covered with particulate particles of 40-60 nm in size, and no defects were observed. Next, the energy of the characteristic X-ray and its intensity were subjected to image processing, and the types of elements constituting the film formed on the surface and their distribution states were analyzed. Since both iron atoms and oxygen atoms were uniformly present on the surface and no particularly uneven distribution was found, it was confirmed that they were fine particles of iron oxide. Furthermore, the EBSP analysis function was added to the function of ultra-low acceleration voltage SEM to analyze the crystal structure. From these results, it was confirmed that the fine particles formed on the sample surface were maghemite, which is the γ phase of ferric oxide. In the EBSP analysis function, when a sample is irradiated with an electron beam, reflected electrons are diffracted by atomic planes in the sample to form a band-like pattern, and the symmetry of this band corresponds to the crystal system. Since the band spacing corresponds to the atomic plane spacing, the function of measuring crystal orientation and crystal system by analyzing this pattern is said.
From the above observation results of the sample surface, it can be confirmed that the entire surface of the bare copper single wire is covered with fine particles of maghemite. From these results, it has been confirmed that when the iron naphthenate is heat-treated, magnetic particles of magnet fines uniformly adsorb to the surface of the bare copper single wire.
Next, the insulation resistance of the sample was measured. Using an insulation resistance meter of Kyoritsu Electric Instrument, the length of the sample was 1 m, and the electrical resistance between the bare single copper wire and the insulating layer was measured. The insulation resistance showed a value close to 1 MΩ. Therefore, it turned out that an insulating layer has the insulation resistance required for a wire.
Furthermore, the sample was continuously wound five times around a pipe having a diameter of 5 mm while changing the tension during winding, and the surface of the pipe after removing the sample was observed by SEM, but the presence of the maghemite fine particles was not recognized. Furthermore, the tension was changed so that the sample was triple-folded, and the pipe was continuously wound around the pipe five times continuously. After that, the surface of the sample was observed by SEM, but it was not different from the initial state. Moreover, in any case, no abnormality such as a crack was observed on the surface of the sample. Therefore, it was found that the fine particles of maghemite are strongly magnetically adsorbed. From these results, the sample can be used as a winding used for a coil.
Moreover, after exposing the pipe in which the sample was wound to -40 degreeC and 400 degreeC each for 30 minutes, although the sample surface was observed with SEM, it was not different from the initial state. From this result, it was found that it has cold resistance of -40 ° C, heat resistance of 400 ° C and excellent thermal shock resistance.
Next, the sample was cut into round slices and the cross section was observed by SEM. Twenty to twenty-two particulate particles of maghemite were stacked to cover the bare copper single wire. Accordingly, 20 to 22 maghemite fine particles are magnetically adsorbed to form an insulating layer having a thickness close to 1 μm. The cross section of the sample is schematically shown enlarged in FIG. 1 is a bare copper single wire and 2 is a maghemite fine particle.
Furthermore, the dielectric breakdown voltage was measured based on the dielectric breakdown test of the winding test method of JIS C 3216-1 using dielectric breakdown tester EB0181 of Tokyo Seiden Co., Ltd. As a result, the dielectric breakdown voltage of the sample was 12 kV. This insulation withstand voltage is equivalent to that of an enameled wire (for example, heat resistant enameled wire IMW of Hitachi Metals, Ltd.) having a polyimide insulation layer thickness of 0.035 mm and a bare copper single wire diameter of 1.0 mm. . On the other hand, the thickness of the insulating layer of the sample is only 1/35 of the thickness of the insulating layer of the heat-resistant wire, but has the same withstand voltage, so the insulating layer consisting of aggregation of maghemite particles has high withstand voltage I found that.
As described above, the sample is excellent in heat resistance, cold resistance, thermal shock resistance, dielectric breakdown voltage, flexibility, adhesion between the insulating layer and the conductor, abrasion resistance, and winding resistance. On the other hand, the sample is manufactured continuously by performing five steps consisting of the simple process described in the 13th paragraph in succession. In addition, the organic iron compounds described in the eighteenth paragraph, which are the raw materials of ferrous oxide, are iron carboxylate compounds which can be easily synthesized. Furthermore, the organic compound which comprises a suspension is also an organic compound which belongs to general purpose carboxylic acid esters. Therefore, an insulated wire with excellent performance can be manufactured continuously at low processing costs using inexpensive raw materials.

1 bare copper single wire 2 maghemite fine particles

Claims (4)

The manufacturing method for continuously manufacturing the insulated wire includes a first step of immersing and passing the conductor in a suspension in which fine particles of ferrous oxide are dispersed in an organic compound diluted with alcohol, and an air atmosphere. The first heat treatment apparatus is heated to a temperature at which the organic compound evaporates from room temperature, the second step of passing the conductor, and the fine particles of ferrous oxide are oxidized into fine particles of maghemite in the air atmosphere. The conductor is passed through the third heat treatment apparatus, which is heated to a predetermined temperature, and the space of the atmospheric atmosphere in which the magnetic field to saturate the magnetization of the maghemite fine particles is generated. A manufacturing method comprising a fourth step and a fifth step of winding the conductor, wherein the five steps are carried out continuously is a series of continuous insulated wires in which the conductor is insulated with a collection of magnetically adsorbed maghemite fine particles. Manufacturing method to be manufactured, continuously producing insulated wire. A manufacturing method for producing the suspension according to claim 1 comprises: a first step of dispersing an organic iron compound which deposits ferrous oxide by thermal decomposition in an alcohol to form an alcohol dispersion, and the alcohol The first property to be dissolved or mixed with the second property, the second property having a viscosity higher than the alcohol, and the boiling point is higher than the thermal decomposition temperature of the organic iron compound, and the ferrous oxide is oxidized to maghemite A second step of mixing an organic compound having a third property lower than the temperature into the alcohol dispersion to form a mixture, and a temperature at which the organic iron compound thermally decomposes the mixture in an air atmosphere. And a fourth step of mixing the alcohol with the heat-treated mixed solution, and a manufacturing method in which these four steps are continuously performed is an organic solution diluted with alcohol. At the object, a manufacturing method in which fine particles of ferrous oxide to produce a suspension which is dispersed, to produce a suspension as claimed in claim 1. The method according to claim 2, wherein the organic iron compound is an iron carboxylate compound in which an oxygen ion constituting a carboxyl group is coordinated to an iron ion. Production method for producing a suspension. The method according to claim 2, wherein the organic compound is an organic compound belonging to a carboxylic acid ester.

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