JP2017183076A - Insulated wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulated wire capable of improving fusion property between wires.SOLUTION: An insulated wire includes a linear conductor and an expansion layer which is laminated on an outer peripheral surface side of the conductor directly or through other layer and expands by heating, where the expansion layer has matrix containing a phenoxy resin as a main component and a chemical foaming agent or thermally expansive microcapsule dispersed in the matrix, the phenoxy resin has a bisphenol A type skeleton and a bisphenol F type skeleton in the same molecule or different molecules, and an average thickness expansion ratio after the expansion layer is heated is 1.1 times or more and 5 times or less. The insulated wire may further have an insulating layer as the other layer. The phenoxy resin may be a copolymer having the bisphenol A type skeleton and the bisphenol F type skeleton in the same molecule. The matrix may further contain a polyfunctional epoxy compound.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an insulated wire.

  For example, when manufacturing a coil for a motor using an insulated wire, after winding the wire on the core, the gap between the wires and the gap between the wires and the core are impregnated with varnish to fix the wires and between the wires and the core. It is common. However, it is difficult to ensure complete impregnation of the varnish, and there is a possibility that the fixing of the electric wire is partially insufficient. Moreover, man-hours increase by impregnation of the varnish, and the coil may be expensive.

  On the other hand, in order to simplify the motor manufacturing process, a self-bonding insulated wire having a fusion layer that is fused to the outer periphery of a conductor has been proposed (see International Publication No. 2015/121999).

International Publication No. 2015/121999

  However, in the self-bonding insulated wire described in the above publication, if the winding density of the wire is small, there is a risk that the bonding between the wires or between the wire and the core may be insufficient. If the fusion layer is thickened, the density of the windings is lowered, and the volumetric efficiency of the coil may be lowered. Further, in the self-bonding insulated wire described in the above publication, if the heat-sealing layer of the wire is thickened, the workability when inserting the wire into the motor may be deteriorated.

  This invention is made | formed based on the above situations, and it aims at providing the self-bonding insulated wire which can improve the meltability between electric wires.

  An insulated wire according to one aspect of the present invention made to solve the above problems is a linear conductor and an expansion layer that is laminated on the outer peripheral surface side of the conductor directly or via another layer and expands by heating. The expansion layer has a matrix mainly composed of a phenoxy resin and a chemical foaming agent or a thermally expandable microcapsule dispersed in the matrix, and the phenoxy resin is in the same or different molecule. It has a bisphenol A skeleton and a bisphenol F skeleton, and the average thickness expansion coefficient after heating of the expansion layer is 1.1 to 5 times.

  The insulated wire of the present invention can enhance the fusion property between the wires.

It is a typical sectional view showing the insulated wire concerning one embodiment of the present invention. It is typical sectional drawing which shows the insulated wire which concerns on embodiment different from the insulated wire of FIG.

[Description of Embodiment of the Present Invention]
An insulated wire according to one aspect of the present invention made to solve the above problems is a linear conductor and an expansion layer that is laminated on the outer peripheral surface side of the conductor directly or via another layer and expands by heating. The expansion layer has a matrix mainly composed of a phenoxy resin and a chemical foaming agent or a thermally expandable microcapsule dispersed in the matrix, and the phenoxy resin is in the same or different molecule. It has a bisphenol A skeleton and a bisphenol F skeleton, and the average thickness expansion coefficient after heating of the expansion layer is 1.1 to 5 times.

  In the insulated wire, the expansion layer has a matrix mainly composed of phenoxy resin, and the expansion layer has self-bonding property. In particular, in the insulated wire, since the phenoxy resin has a bisphenol A skeleton and a bisphenol F skeleton in the same or different molecules, it is easy to form an expanded layer having self-bonding properties by extrusion molding. Therefore, when the said insulated wire is shape | molded by extrusion molding, a chemical foaming agent or a thermally expansible microcapsule can be uniformly disperse | distributed in a matrix, and, thereby, an expansion layer can be expanded substantially uniformly over the whole surface. In this way, the insulated wire is excellent in the uniform expansion property of the expansion layer, and the average thickness expansion coefficient after heating is 1.1 times or more and 5 times or less. The insulation after fusion can be improved while ensuring the reliability of fusion.

  The insulated wire may further include an insulating layer as the other layer. Thus, by further providing an insulating layer between the conductor and the expansion layer, the insulating property can be easily and reliably increased.

  The phenoxy resin may be a copolymer having a bisphenol A skeleton and a bisphenol F skeleton in the same molecule. Thus, when the phenoxy resin is a copolymer having a bisphenol A skeleton and a bisphenol F skeleton in the same molecule, a chemical foaming agent or a thermally expandable microcapsule in the matrix when extruded. Can be more uniformly dispersed.

  The matrix may further include a polyfunctional epoxy compound. Thus, when the said matrix further contains a polyfunctional epoxy compound, this polyfunctional epoxy compound can be bridge | crosslinked with the said phenoxy resin, and expansion | swelling layers can be fuse | melted still more firmly.

  As a content rate of the said polyfunctional epoxy compound with respect to 100 mass parts of said phenoxy resins, 5 to 80 mass parts is preferable. Thus, when the content ratio of the polyfunctional epoxy compound with respect to 100 parts by mass of the phenoxy resin is within the above range, it is possible to further improve the fusion property between the expanded layers.

  The decomposition temperature of the chemical foaming agent or the expansion temperature of the thermally expandable microcapsule is preferably 150 ° C. or higher and 250 ° C. or lower. Thus, when the decomposition temperature of the chemical foaming agent or the expansion temperature of the thermally expandable microcapsule is within the above range, for example, the chemical foaming agent or the thermally expandable microcapsule expands during extrusion molding. It is easy to melt and expand the expanded layers by heating after the extrusion molding. Therefore, the fusibility between the expanded layers can be further enhanced.

  In the present invention, the “main component” means a component having the highest content, for example, a component contained in an amount of 50% by mass or more. The “average thickness expansion coefficient” means the ratio of the average thickness of the expanded layer after expansion by heating to the average thickness of the expanded layer before heating. “The expansion temperature of the thermally expandable microcapsule” refers to the decomposition temperature of the internal foaming agent of the thermally expandable microcapsule. Specifically, the temperature at which generation of gas from the internal foaming agent is confirmed or the internal foaming agent The temperature at which the volume is 1.05 times that before expansion (normal temperature: 25 ° C.). The “decomposition temperature of the chemical foaming agent” is a temperature at which gas generation from the chemical foaming agent is confirmed or a temperature at which the volume of the chemical foaming agent is 1.05 times that before expansion (normal temperature: 25 ° C.). Say.

[Details of the embodiment of the present invention]
Hereinafter, one embodiment of an insulated wire according to the present invention will be described in detail with reference to the drawings.

[First embodiment]
<Insulated wire>
An insulated wire 1 in FIG. 1 includes a linear conductor 2 and an expansion layer 3 that is directly laminated on the outer peripheral surface side of the conductor 2 and expands by heating. The expansion layer 3 constitutes the outermost layer of the insulation front. The expansion layer 3 has a matrix 4 mainly composed of phenoxy resin and a foaming agent 5 dispersed in the matrix 4. The phenoxy resin has a bisphenol A skeleton and a bisphenol F skeleton in the same or different molecules. As the foaming agent 5, a chemical foaming agent or a thermally expandable microcapsule is used. That is, the insulated wire 1 has a chemical foaming agent or a thermally expandable microcapsule dispersed in the matrix 4. The average thickness expansion coefficient after heating of the expansion layer 3 is set to 1.1 times or more and 5 times or less.

  In the insulated wire 1, the expansion layer 3 has a matrix 4 whose main component is a phenoxy resin, and the expansion layer 3 has a self-bonding property. In particular, in the insulated wire 1, since the phenoxy resin has a bisphenol A skeleton and a bisphenol F skeleton in the same or different molecules, the expansion layer 3 having self-bonding property is formed by extrusion molding. easy. Therefore, when the insulated wire 1 is formed by extrusion molding, the chemical foaming agent or the heat-expandable microcapsules can be uniformly dispersed in the matrix, whereby the expanded layer 3 can be expanded substantially uniformly over the entire surface. . The insulated wire 1 is excellent in the uniform expansion property of the expansion layer 3 as described above, and the average thickness expansion coefficient after heating is 1.1 times or more and 5 times or less. Therefore, the expansion layer particularly in the case of forming a coil. The insulating property after fusion can be improved while ensuring the reliability of fusion between the three.

(conductor)
The conductor 2 is, for example, a round wire having a circular cross section, but may be a square wire having a circular cross section or a stranded wire obtained by twisting a plurality of strands.

  The material of the conductor 2 is preferably a metal having high conductivity and high mechanical strength. Examples of such metals include copper, copper alloys, aluminum, nickel, silver, soft iron, steel, and stainless steel. The conductor 2 is a material in which these metals are formed in a linear shape, or a multilayer structure in which such a linear material is coated with another metal, such as a nickel-coated copper wire, a silver-coated copper wire, or a copper-coated aluminum. Wire, copper-coated steel wire, etc. can be used.

The lower limit of the average cross-sectional area of the conductor 2 (average cross-sectional area of the axial cross section perpendicular) preferably is 0.01 mm ^2, 0.1 mm ² is more preferable. In contrast, the upper limit of the average cross-sectional area of the conductor 2 is preferably 10 mm ^2, 5 mm ² is more preferable. If the average cross-sectional area of the conductor 2 is less than the lower limit, the volume of the expansion layer 3 with respect to the conductor 2 is increased, and the volume efficiency of a coil or the like using the insulated wire 1 may be reduced. On the other hand, when the average cross-sectional area of the conductor 2 exceeds the upper limit, the insulated wire 1 may unnecessarily increase in diameter. The “average cross-sectional area of the conductor” refers to an average value of cross-sectional areas in any ten cross sections perpendicular to the axis of the conductor.

(Expanded layer)
The expansion layer 3 has the matrix 4 which has a phenoxy resin as a main component and the foaming agent 5 disperse | distributed in the matrix 4 as mentioned above. The expansion layer 3 is expanded by the expansion of the foaming agent 5 by being heated, and expands as a whole. When the insulated wire 1 is formed by extrusion, the expansion layer 3 does not expand at the heating temperature at the time of extrusion, and preferably expands by being heated after the extrusion. Thus, the expansion layer 3 does not expand at the heating temperature at the time of extrusion molding, but expands by heating after the extrusion molding, so that the expansion layers 3 can be fused while being expanded by heating after the extrusion molding. It is easy, and thereby, the fusion property between the expansion layers 3 can be further enhanced.

  As a minimum of average thickness before heating of expansion layer 3 (before heating after extrusion molding), 30 micrometers is preferred and 50 micrometers is more preferred. On the other hand, the upper limit of the average thickness of the expanded layer 3 before heating is preferably 300 μm, and more preferably 200 μm. If the average thickness of the expanded layer 3 before heating is less than the lower limit, the insulated wires 1 may not be firmly fixed to each other. On the other hand, if the average thickness of the expansion layer 3 before heating exceeds the upper limit, the volume efficiency of the coil using the insulated wire 1 may be reduced.

  The lower limit of the average thickness expansion coefficient after heating the expanded layer 3 (after heating after extrusion) is 1.1 times, and preferably 2 times. On the other hand, the upper limit of the average thickness expansion coefficient after heating of the expansion layer 3 is 5 times, and preferably 4 times. If the average thickness expansion coefficient after heating of the expansion layer 3 is less than the above lower limit, when the insulated wire 1 is subjected to a winding process, the adjacent expansion layers 3 may be insufficiently fused. On the contrary, when the average thickness expansion coefficient after heating of the expansion layer 3 exceeds the above upper limit, the density of the expansion layer 3 becomes insufficient and the strength of the insulated wire 1 may be insufficient. The expansion rate of the expansion layer 3 can be controlled by selecting the type and amount of the foaming agent 5 and the elastic modulus of the matrix 4 at the foaming start temperature of the foaming agent 5.

  The lower limit of the average diameter of the pores formed in the expansion layer 3 by foaming of the foaming agent 5 by heating is preferably 1 μm and more preferably 5 μm. On the other hand, the upper limit of the average diameter of the pores formed in the expansion layer 3 is preferably 300 μm, and more preferably 200 μm. If the average diameter of the holes formed in the expansion layer 3 is less than the lower limit, a sufficient expansion rate may not be obtained. Conversely, if the average diameter of the pores formed in the expansion layer 3 exceeds the upper limit, the expansion layer 3 may be unnecessarily thick or the expansion of the expansion layer 3 may be uneven. The “average diameter of pores” refers to a value obtained by measuring a cross section with a pore diameter distribution measuring device (for example, “Porous Material Automatic Pore Diameter Distribution Measuring System” manufactured by Porus Materials).

  As a minimum of the porosity after heating of expansion layer 3, 10% is preferred and 50% is more preferred. On the other hand, the upper limit of the porosity after heating of the expansion layer 3 is preferably 80% and more preferably 70%. If the porosity of the expanded layer 3 after heating is less than the above lower limit, the contact pressure between the adjacent expanded layers 3 may be insufficient, resulting in insufficient fusion. On the other hand, when the porosity after heating of the expansion layer 3 exceeds the above upper limit, the strength of the expansion layer 3 after expansion may be insufficient. The “porosity” is the percentage of the volume of the gas in the expansion layer relative to the volume of the expansion layer, and is calculated from the mass and density of the expansion layer matrix and the outer shell of the thermally expandable microcapsule. It is an amount calculated by (V1−V0) / V1 × 100, where V0 is the volume and V1 is the apparent volume including the voids of the expanded layer.

<matrix>
The matrix 4 has a phenoxy resin as a main component as described above, and this phenoxy resin has a bisphenol A skeleton and a bisphenol F skeleton in the same or different molecules. When the insulated wire 1 is formed by extrusion, the matrix 4 has a self-bonding property after the extrusion.

  As a minimum of the content rate of the said phenoxy resin in the matrix 4, 60 mass% is preferable, 65 mass% is more preferable, 70 mass% is further more preferable. On the other hand, as an upper limit of the said content rate, 95 mass% is preferable, 90 mass% is more preferable, and 85 mass% is further more preferable. If the content ratio is less than the lower limit, the self-bonding property of the expansion layer 3 may be insufficient. On the other hand, when the content ratio exceeds the upper limit, a polyfunctional epoxy compound to be described later cannot be sufficiently contained in the matrix 4, and the fusion property between the expansion layers 3 may not be sufficiently improved. There is.

  The phenoxy resin may have a bisphenol A skeleton and a bisphenol F skeleton in different molecules, but is preferably a copolymer having a bisphenol A skeleton and a bisphenol F skeleton in the same molecule. . When the phenoxy resin is a copolymer having a bisphenol A skeleton and a bisphenol F skeleton in the same molecule, the expansion layer 3 can be easily formed by extrusion molding, and the foaming agent 5 is uniformly dispersed in the matrix 4 by extrusion molding. Easy to do. Therefore, in the insulated wire 1, the expanded layer 3 is uniformly expanded on the entire surface by the phenoxy resin being a copolymer having a bisphenol A type skeleton and a bisphenol F type skeleton in the same molecule. The fusion property between each other can be further increased.

  It is preferable that the matrix 4 further includes a polyfunctional epoxy compound. The insulated wire 1 can crosslink the phenoxy resin and the polyfunctional epoxy compound at the time of heating after the extrusion molding because the matrix 4 contains the polyfunctional epoxy compound. That is, when the insulated wire 1 includes a polyfunctional epoxy compound in the matrix 4, the phenoxy resin and the polyfunctional epoxy compound are not crosslinked in the state after the extrusion, while the expanded layer 3 is heated by heating after the extrusion. The phenoxy resin and the polyfunctional epoxy compound can be cross-linked at the same time that the expansion layer 3 is firmly fused with each other. Therefore, the insulated wire 1 can fuse | fuse the expansion layers 3 more firmly by making the said phenoxy resin into a part thermosetting type because the matrix 4 has a polyfunctional epoxy compound.

  Examples of the polyfunctional epoxy compound include bisphenol-A type epoxy resin, novolac type epoxy resin, cyclic aliphatic epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, and the like. A mixture of seeds or more can be used.

  As a minimum of the content rate of the above-mentioned polyfunctional epoxy compound to 100 mass parts of the above-mentioned phenoxy resin, 5 mass parts is preferred, 10 mass parts is more preferred, and 15 mass parts is still more preferred. On the other hand, as an upper limit of the said content rate, 80 mass parts is preferable, 50 mass parts is more preferable, and 30 mass parts is further more preferable. If the said content rate is less than the said minimum, the said phenoxy resin and a polyfunctional epoxy compound cannot fully be bridge | crosslinked, and there exists a possibility that the meltability of the expansion layers 3 may not fully become high. On the contrary, if the content ratio exceeds the upper limit, the content ratio of the phenoxy resin in the matrix 4 is insufficient, and the self-bonding property of the expansion layer 3 may be insufficient.

  The matrix 4 may contain a crosslinking accelerator in addition to the polyfunctional epoxy compound. Examples of the crosslinking accelerator include amines, imidazoles, aromatic sulfonium salts, diazabicycloundecene salts, and the like.

  The matrix 4 may contain, for example, a melamine resin, a phenol resin, an isocyanate, or the like as a cross-linking agent instead of the polyfunctional epoxy compound or together with the polyfunctional epoxy compound.

  Further, the matrix 4 is formed of, for example, copolyester, polybutylene terephthalate, polyethylene terephthalate, thermoplastic polyurethane, polycarbonate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyetherimide, polyether ether ketone, polyether ketone, polyether sulfone, A thermoplastic resin such as polyphenylsulfone, semi-aromatic polyamide, thermoplastic polyamideimide, and polyimide may further be included.

  The lower limit of the elastic modulus of the matrix 4 at the foaming start temperature of the foaming agent 5 (expansion temperature of thermally expandable microcapsules or decomposition temperature of chemical foaming agent) is preferably 1 kPa. If the elastic modulus of the matrix 4 at the foaming start temperature of the foaming agent 5 is less than the lower limit, the expansion layer 3 may flow more than necessary during expansion, and the shape of the expansion layer 3 may become uneven. The “elastic modulus of the matrix” means a shear modulus measured according to JIS-K-6868-2 (1999).

<Foaming agent>
As the foaming agent 5, a chemical foaming agent or a thermally expandable microcapsule is used as described above. In the insulated wire, the foaming agent 5 is uniformly dispersed in the matrix 4, and the expansion layer 3 expands substantially uniformly by foaming of the foaming agent 5.

  As a minimum of the content rate in the expansion layer 3 of the foaming agent 5, 1 mass% is preferable and 2 mass% is more preferable. On the other hand, as an upper limit of the content rate in the expansion layer 3 of the foaming agent 5, 15 mass% is preferable and 10 mass% is more preferable. If the content of the foaming agent 5 in the expansion layer 3 is less than the lower limit, the expansion rate of the expansion layer 3 is small, and the insulated wires 1 may not be firmly fixed to each other. On the contrary, when the content rate of the foaming agent 5 in the expansion layer 3 exceeds the above upper limit, the matrix 4 is relatively decreased, and thus the strength and the fusibility of the expansion layer 3 may be insufficient.

<Chemical foaming agent>
The chemical foaming agent is decomposed by heating to generate, for example, nitrogen gas, carbon dioxide gas, carbon monoxide, ammonia gas or the like, and an organic foaming agent or an inorganic foaming agent can be used.

  Examples of the organic blowing agent include azo blowing agents such as azodicarbonamide (ADCA) and azobisisobutyronitrile (AIBN), such as dinitrosopentamethylenetetramine ( D.P.T.), N, N′dinitroso-N, N′-dimethylterephthalamide (D.N.D.M.T.A) and the like, for example, P-toluenesulfonyl hydrazide (T. Hydrazides such as S.H), P, P-oxybisbenzenesulfonyl hydrazide (O.B.S.H), benzenesulfonyl hydrazide (B.S.H), and other trihydrazinotriazines (T.H. .T), acetone-P-sulfonylhydrazone, etc., are exemplified, and these can be used alone or in combination of two or more.

  Examples of the inorganic foaming agent include sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, sodium borohydride, sodium boron hydride, silicon oxyhydride and the like. In general, an inorganic foaming agent has a slower gas generation rate than an organic foaming agent, and adjustment of gas generation is difficult. Therefore, an organic foaming agent is preferable as the chemical foaming agent.

  As a minimum of decomposition temperature of a chemical foaming agent, 150 ° C is preferred and 170 ° C is more preferred. On the other hand, the upper limit of the decomposition temperature of the chemical foaming agent is preferably 250 ° C and more preferably 200 ° C. If the decomposition temperature of the chemical foaming agent is less than the lower limit, for example, the chemical foaming agent expands at the heating temperature at the time of extrusion molding, making it difficult to fuse the expanded layers 3 together while expanding the expanded layers 3. As a result, there is a possibility that the fusion property between the expanded layers 3 cannot be sufficiently improved. On the contrary, if the decomposition temperature of the chemical foaming agent exceeds the above upper limit, the energy cost required for expanding the expansion layer 3 may be excessive, and motor components other than the coil when the expansion layer 3 is expanded. May be adversely affected by excessive heat load.

  The expansion layer 3 may contain a foaming aid together with the chemical foaming agent. The foaming aid is not particularly limited as long as it promotes thermal decomposition of the chemical foaming agent. For example, the vulcanization accelerator, filler, vulcanization acceleration aid, PVC stabilizer, anti-aging agent, vulcanization Agents, urea compounds and the like. Such a foaming aid accelerates the decomposition of the chemical foaming agent and lowers the foaming temperature.

  Examples of the vulcanization accelerator include guanidine, aldehyde-ammonia, sulfenamide, thiuram, xanthate, aldehyde-amine, thiazole, thiourea, and dithiocarbamate. Examples of the filler include silica, magnesium carbonate, calcium carbonate, magnesium silicate, aluminum carbonate, talc, barium sulfate, aluminum sulfate, and calcium sulfate. Examples of vulcanization accelerators include zinc white, activated zinc white, zinc carbonate, magnesium oxide, lead monoxide, basic lead carbonate, calcium hydroxide, stearic acid, oleic acid, lauric acid, diethylene glycol, di- Examples thereof include n-butylamine, dicyclohexylamine, diethanolamine, and organic amine. Examples of the stabilizer for PVC include tribasic lead sulfate, dibutyltin dilaurate, dibutyltin dimaleate, zinc stearate, cadmium stearate, barium stearate, calcium stearate and the like. Examples of the anti-aging agent include naphthylamine, diphenylamine, P-phenylene, quinoline, monophenol, polyphenol, thiobisphenol, and phosphite esters. Examples of the vulcanizing agent include Thaik and ammonium sulfur benzoate. Examples of other chemicals include phthalic anhydride, salicylic acid, benzoic acid, antimony trioxide, white petrolatum, titanium oxide, cadmium oxide, borax, glycerin, and dibutyltin dimaleate. Among these, zinc oxide, tribasic lead sulfate, and various vulcanization accelerators are preferable as the foaming aid.

  As a minimum of the compounding ratio with respect to 100 mass parts of chemical foaming agents of these foaming assistants, 5 mass parts is preferred and 50 mass parts is more preferred. On the other hand, the upper limit of the blending ratio of the foaming aid is preferably 200 parts by weight, and more preferably 150 parts by weight. If the blending ratio of the foaming aid is less than the lower limit, the effect of decomposing the chemical foaming agent may be insufficient. On the other hand, when the blending ratio of the foaming aid exceeds the upper limit, the expansion layer 3 may expand unintentionally when the insulated wire 1 is manufactured or stored.

<Thermal expandable microcapsule>
The thermally expandable microcapsule has a core material (inner package) made of an internal foaming agent and an outer shell that encloses the core material, and the outer shell expands due to the expansion of the core material.

  The internal foaming agent of the heat-expandable microcapsule may be anything that expands or generates gas when heated, and its principle is not limited. As the internal foaming agent of the thermally expandable microcapsule, for example, a low boiling point liquid, a chemical foaming agent and a mixture thereof can be used.

  As the low boiling point liquid, for example, alkanes such as butane, i-butane, n-pentane, i-pentane and neopentane, and freons such as trichlorofluoromethane are preferably used.

As the chemical foaming agent, a thermally decomposable substance such as azobisisobutyronitrile that generates N ₂ gas by heating is preferably used.

  The expansion temperature of the heat-expandable microcapsule (expansion start temperature of the internal foaming agent of the heat-expandable microcapsule), that is, the boiling point of the low-boiling liquid or the thermal decomposition temperature of the chemical foaming agent is as follows. It should be above the softening temperature of the shell.

  More specifically, the lower limit of the expansion temperature of the thermally expandable microcapsule is preferably 150 ° C., more preferably 170 ° C. On the other hand, the upper limit of the expansion temperature of the thermally expandable microcapsule is preferably 250 ° C., more preferably 200 ° C. If the expansion temperature of the thermally expandable microcapsule is less than the above lower limit, for example, the thermally expandable microcapsule expands at the heating temperature at the time of extrusion molding, and the expanded layer 3 is expanded while the expanded layer 3 is melted. There is a possibility that it will be difficult to attach, and as a result, there is a possibility that the fusibility between the expansion layers 3 cannot be sufficiently improved. Conversely, if the expansion temperature of the thermally expandable microcapsule exceeds the above upper limit, the energy cost required to expand the expansion layer 3 may be excessive, and other than the coil when expanding the expansion layer 3 Excessive heat load on motor parts may cause adverse effects.

  On the other hand, the outer shell of the thermally expandable microcapsule is formed of a stretchable material that can expand without breaking when the internal foaming agent is foamed to form a microballoon containing the generated gas. As a material for forming the outer shell of the thermally expandable microcapsule, a resin composition mainly composed of a polymer such as a thermoplastic resin is usually used.

  The thermoplastic resin used as the main component of the outer shell of the thermally expandable microcapsule is formed from monomers such as vinyl chloride, vinylidene chloride, acrylonitrile, acrylic acid, methacrylic acid, acrylate, methacrylate, styrene, etc. Polymers formed from two or more types of monomers are preferably used. An example of a preferred thermoplastic resin is an acrylonitrile-based copolymer. In this case, the expansion temperature of the thermally expandable microcapsule is 150 ° C. or more and 250 ° C. or less.

  The lower limit of the average diameter of the thermally expandable microcapsules before heating is preferably 1 μm and more preferably 5 μm. On the other hand, the upper limit of the average diameter of the thermally expandable microcapsules before heating is preferably 300 μm, and more preferably 200 μm. If the average diameter of the thermally expandable microcapsules before heating is less than the above lower limit, a sufficient expansion rate may not be obtained. Conversely, if the average diameter of the thermally expandable microcapsules before heating exceeds the above upper limit, the expansion layer 3 may be unnecessarily thick or the expansion of the expansion layer 3 may be nonuniform. The “average diameter” of the thermally expandable microcapsule is an average value of the maximum diameter in a plan view when 10 or more samples of the thermally expandable microcapsule are observed with a microscope and the diameter in a direction perpendicular to the maximum diameter. Say.

  The lower limit of the ratio of the average diameter of the thermally expandable microcapsule to the average thickness of the expansion layer 3 is preferably 1/16 and more preferably 1/8. On the other hand, the lower limit of the ratio of the average diameter of the thermally expandable microcapsule to the average thickness of the expansion layer 3 is preferably 9/10, and more preferably 8/10. If the average diameter of the heat-expandable microcapsules is less than the above lower limit, the thickness of the outer shell may be insufficient and it may be broken at the time of expansion, or the internal volume may be reduced and the foaming agent may be insufficient to sufficiently expand. Conversely, if the average diameter of the thermally expandable microcapsule exceeds the above upper limit, the thermally expandable microcapsule may protrude from the matrix 4 and the expandable layer 3 may not be sufficiently expanded, or the expandable layer 3 may partially expand. Therefore, there is a possibility that it cannot expand uniformly.

  The lower limit of the expansion coefficient of the thermally expandable microcapsule is preferably 3 times, and more preferably 5 times. On the other hand, the upper limit of the expansion coefficient of the thermally expandable microcapsule is preferably 20 times, and more preferably 10 times. If the expansion coefficient of the thermally expandable microcapsule is less than the lower limit, the expansion coefficient of the expansion layer 3 may be insufficient. Conversely, if the expansion coefficient of the thermally expandable microcapsule exceeds the above upper limit, the matrix 4 of the expanded layer 3 cannot follow the thermally expandable microcapsule, and the expanded layer 3 may not be expanded as a whole. There is. The “expansion coefficient” of the thermally expandable microcapsule means a ratio of the maximum value of the average diameter during heating to the average diameter before heating of the thermally expandable microcapsule.

<Insulated wire manufacturing method>
The insulated wire 1 can be manufactured by extruding the expansion layer 3 on the outer peripheral surface side of the conductor 2. The method for manufacturing an insulated wire includes a preparation step for preparing a composition for forming an expanded layer, and an extrusion step for extruding the composition for forming an expanded layer prepared in the preparation step to the outer peripheral surface side of the conductor 2.

(Preparation process)
In the preparation step, the composition for forming an expanded layer is kneaded using a Banbury mixer, a pressure kneader, a kneading extruder, a biaxial kneading extruder, a roll or the like. In the said preparation process, it heats more than the glass transition temperature of the above-mentioned phenoxy resin which comprises the matrix 4, and makes the composition for expansion layer formation into a molten state. In this preparation step, it is preferable to keep the heating temperature lower than the decomposition temperature of the chemical foaming agent and the expansion temperature of the thermally expandable microcapsules. In this way, by suppressing the heating temperature to be lower than the decomposition temperature of the chemical foaming agent and the expansion temperature of the thermally expandable microcapsule, the expanded layers 3 are expanded by heating after the extrusion of the insulated wire, and the expanded layers 3 are firmly melted. It becomes easy to wear.

  As a minimum of the above-mentioned heating temperature in the above-mentioned preparation process, 90 ° C is preferred and 100 ° C is more preferred. On the other hand, the upper limit of the heating temperature is preferably 140 ° C and more preferably 130 ° C. If the heating temperature is less than the lower limit, the composition for forming an expanded layer may not be sufficiently melted. Conversely, when the heating temperature exceeds the upper limit, the foaming agent 5 (chemical foaming agent or thermally expandable microcapsule) may expand during heating.

(Extrusion process)
In the extrusion step, the expansion layer 3 is formed on the outer peripheral surface side of the conductor 2 by extruding and curing the composition for forming the expansion layer prepared in the preparation step on the outer peripheral surface side of the conductor 2 by a known extruder.

  The manufacturing method of the said insulated wire can manufacture the said insulated wire 1 mentioned above which can improve the meltability between wires easily and reliably.

[Second Embodiment]
<Insulated wire>
An insulated wire 11 in FIG. 2 includes a linear conductor 2 and an expansion layer 3 that is laminated on the outer peripheral surface side of the conductor 2 via another layer and expands by heating. The insulated wire 11 in FIG. 2 includes an insulating layer 12 stacked between the conductor 2 and the expansion layer 3 as the other layer. The insulated wire 11 includes the insulating layer 12 laminated between the conductor 2 and the expansion layer 3, so that the insulation can be easily and reliably increased. The insulated wire 11 includes a conductor 2, an insulating layer 12 stacked on the outer peripheral surface of the conductor, and an expansion layer 3 stacked on the outer peripheral surface of the insulating layer 12. Since the conductor 2 is the same as the insulated wire 1 of FIG. 1, it attaches | subjects the same code | symbol and abbreviate | omits description. Moreover, since the expansion layer 3 is the same as the insulated wire 1 of FIG. 1 except being laminated | stacked on the outer peripheral surface side of the insulating layer 12, it attaches | subjects the same code | symbol and abbreviate | omits description.

(Insulating layer)
The insulating layer 12 contains a synthetic resin as a main component. Examples of the synthetic resin include thermosetting resins such as polyvinyl formal, thermosetting polyurethane, thermosetting acrylic resin, epoxy resin, thermosetting polyester, thermosetting polyester imide, thermosetting polyester amide imide, thermosetting polyamide imide, and polyimide. , Thermoplastic resins such as polyphenylsulfone, polyphenylene sulfide, polyetherimide, polyetheretherketone, and polyethersulfone.

  The insulating layer 12 is preferably not melted when the expansion layers 3 are fused. Therefore, when the main component of the insulating layer 12 is a thermoplastic resin, the melting point of the thermoplastic resin is preferably higher than the melting point of the phenoxy resin described above, which is the main component of the matrix 4.

  The lower limit of the average thickness of the insulating layer 12 is preferably 5 μm and more preferably 10 μm. On the other hand, the upper limit of the average thickness of the insulating layer 12 is preferably 200 μm, and more preferably 150 μm. If the average thickness of the insulating layer 12 is less than the above lower limit, the insulating layer 12 may be broken and insulation of the conductor 2 may be insufficient. Conversely, if the average thickness of the insulating layer 12 exceeds the above upper limit, the volume efficiency of a coil or the like using the insulated wire 11 may be reduced.

<Manufacturing method>
The method of manufacturing the insulated wire 11 includes a laminating step of laminating the insulating layer 12 on the outer peripheral surface side of the conductor 2, a preparation step of preparing a composition for forming an expansion layer, and a composition for forming an expansion layer prepared in the preparation step. And an extruding step of extruding an object to the outer peripheral surface side of the insulating layer 12. Since the preparation process and the extrusion process in the manufacturing method of the insulated wire can be performed in the same manner as the preparation process and the extrusion process in the first embodiment described above, description thereof is omitted.

(Lamination process)
The said lamination process can be performed by apply | coating the resin varnish for insulating layer formation which diluted the composition for insulating layer formation with the solvent to the outer peripheral surface side of the conductor 2, and making it dry, for example. Moreover, the said lamination process can also be performed by extruding the composition for insulating layer formation to the outer peripheral surface side of the conductor 2, when the main component of an insulating layer is a thermoplastic resin. In addition, when performing the said lamination | stacking process by apply | coating the resin varnish for insulating layer formation to the outer peripheral surface side of the conductor 2, and drying, you may repeat the said application | coating and drying several times.

[Third embodiment]
<Coil wire>
A coil wire according to another embodiment of the present invention is formed by subjecting the insulated wire 1 or the insulated wire 11 described above to a winding process and expanding the expansion layer 3.

  As a heating method for expanding the expansion layer 3, for example, a method using heat generated by energization of the conductor 2 can be applied as well as a conventionally known method such as hot air heating, infrared heating, and high frequency heating. .

  As a minimum of heating temperature for expanding expansion layer 3, 160 ° C is preferred and 170 ° C is more preferred. On the other hand, the upper limit of the heating temperature is preferably 280 ° C, more preferably 220 ° C. If the heating temperature is less than the lower limit, it may be difficult to fuse the expanded layers 3 together while accurately expanding the chemical foaming agent or the thermally expanded microcapsules contained in the matrix 4. On the other hand, if the heating temperature exceeds the upper limit, the energy cost may be excessive, and an excessive heat load may be applied to the motor components other than the coil, which may cause adverse effects.

  In the coil wire, the expansion layers 3 are firmly bonded to each other, and the insulation between the conductors 2 is high.

[Fourth embodiment]
<Winding bundle>
A winding bundle according to another embodiment of the present invention is formed by winding a plurality of the insulated wires 1 or the plurality of insulated wires 11 and bundling them.

  In the winding bundle, the expansion layers 3 are firmly fused together, and the insulation between the conductors 2 is high.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  For example, the insulated wire may include other layers such as a primer treatment layer between the conductor and the expansion layer or between the conductor and the insulating layer.

(Primer treatment layer)
A primer process layer is a layer provided in order to improve the adhesiveness between layers, for example, can be formed with a well-known resin composition.

  When providing the primer treatment layer between the conductor and the expansion layer, the resin composition for forming the primer treatment layer is, for example, one or more kinds of resins selected from polyimide, polyamideimide, polyesterimide, polyester and phenoxy resin. It is good to include. Moreover, the resin composition forming the primer treatment layer may contain an additive such as an adhesion improver. By forming a primer treatment layer between the conductor and the expansion layer with such a resin composition, it is possible to improve the adhesion between the conductor and the expansion layer. Properties such as flexibility, abrasion resistance, scratch resistance, and workability can be effectively enhanced.

  Moreover, the resin composition which forms a primer process layer may contain other resin, for example, an epoxy resin, a phenoxy resin, a melamine resin, etc. with the said resin.

  Moreover, you may use a commercially available liquid composition (insulation varnish) as each resin contained in the resin composition which forms a primer process layer.

  As a minimum of the average thickness of a primer processing layer, 1 micrometer is preferable and 2 micrometers is more preferable. On the other hand, the upper limit of the average thickness of the primer treatment layer is preferably 20 μm, and more preferably 10 μm. When the average thickness of the primer treatment layer is less than the above lower limit, there is a possibility that sufficient adhesion with the conductor cannot be exhibited. Conversely, when the average thickness of the primer-treated layer exceeds the above upper limit, the insulated wire may be unnecessarily increased in diameter.

  The insulated wire may further include another layer such as a fusion layer on the outer peripheral surface side of the expansion layer. Moreover, as a main component of this melt | fusion layer, thermoplastic resins, such as a phenoxy resin, polyamide, a butyral resin, are mentioned, for example. The average thickness of the fusion layer can be, for example, 5 μm or more and 200 μm or less.

  The method for producing the insulated wire is not particularly limited, and in addition to the above-described extrusion molding method, for example, an expanded layer forming resin varnish obtained by diluting the expanded layer forming composition with a solvent is applied to the outer peripheral surface side of the conductor. It is also possible to adopt a drying method.

  Moreover, the said insulated wire can be used also for the other use which makes it the state which has arrange | positioned the several insulated wire in parallel besides forming a coil.

  Since the insulated wire according to the present invention can enhance the fusion property between the wires, it can be suitably used to form a coil, a motor, or the like.

DESCRIPTION OF SYMBOLS 1,11 Insulated wire 2 Conductor 3 Expansion layer 4 Matrix 5 Foaming agent 12 Insulation layer

Claims (6)

A linear conductor, and an expansion layer that is laminated directly or via another layer on the outer peripheral surface side of the conductor and expands by heating,
The expansion layer has a matrix mainly composed of a phenoxy resin, and a chemical foaming agent or a thermally expandable microcapsule dispersed in the matrix,
The phenoxy resin has a bisphenol A skeleton and a bisphenol F skeleton in the same or different molecules,
An insulated wire having an average thickness expansion coefficient after heating of the expansion layer of 1.1 to 5 times.   The insulated wire according to claim 1, further comprising an insulating layer as the other layer.   The insulated wire according to claim 1 or 2, wherein the phenoxy resin is a copolymer having a bisphenol A skeleton and a bisphenol F skeleton in the same molecule.   The insulated wire according to claim 1, 2, or 3, wherein the matrix further contains a polyfunctional epoxy compound.   The insulated wire according to claim 4, wherein a content ratio of the polyfunctional epoxy compound with respect to 100 parts by mass of the phenoxy resin is 5 parts by mass or more and 80 parts by mass or less.   The insulated wire according to any one of claims 1 to 5, wherein a decomposition temperature of the chemical foaming agent or an expansion temperature of the thermally expandable microcapsule is 150 ° C or higher and 250 ° C or lower.

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