Insulated wire, coil, rotary electric machine, and electric / electronic apparatus

Abstract

To provide an insulated wire that has excellent adhesion between a conductor and a resin-coated layer (layer containing crystalline thermoplastic resin) contacting the conductor, and excellent long-term heat resistance, flexibility, dimensional accuracy (external appearance), and can increase production efficiency, and a coil using the insulated wire, a rotary electric machine and an electric / electronic apparatus.SOLUTION: An insulated wire has a conductor and at least one layer of resin-coated layer formed on the conductor, where a resin-coated layer (i) contacting the conductor out of the resin-coated layers contains crystalline thermoplastic resin, the resin-coated layer (i) has the degree of crystallinity of an inside region lower than the degree of crystallinity of an outside region, and a value obtained by dividing the minimum value of thickness of the resin-coated layer (i) by the maximum value of the thickness is 0.800 or more and 1.000 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to insulated wires, coils, rotating electrical machines, and electrical and electronic devices.

Background Art

[0002] In inverter-related devices (such as high-speed switching elements, inverter motors, coils for electrical and electronic devices such as transformers, etc.), as magnet wire, an insulated wire provided with an insulating film containing an insulating resin around a conductor is used. For insulated wires used in miniaturized electrical and electronic devices, it is required that the insulating film cover the conductor with high adhesion. That is, in such devices, the insulated wire is used after being wound so as to be pushed into a narrow portion. For example, in a rotating electrical machine or a transformer, etc., the number of coils that can be inserted into the slots of the stator core greatly affects its performance. Therefore, the insulated wire is bent with a complex and small bending radius. At this time, if the adhesion between the conductor and the coating resin layer is not sufficient, the insulating film will peel off from the conductor.

[0003] As the insulating film, an extrusion coating layer using a crystalline thermoplastic resin is known, and by controlling the crystallinity of the thermoplastic resin, desired properties such as adhesion and chemical resistance can be imparted to the obtained insulated wire. For example, Patent Document 1 discloses an insulated wire characterized in that two or more insulating layers made of polyether ether ketone (PEEK) are provided on a conductor. In the insulated wire, by lowering the crystallinity of PEEK in the inner first insulating layer and increasing the crystallinity of PEEK in the outer second insulating layer, it is described that good chemical resistance and high flexibility can be achieved.

[0004] Further, Patent Document 2 discloses an insulated wire including a central conductor and an insulating coating that covers the central conductor and is made of a thermoplastic resin. For the degree of crystallinity, which is the ratio of the crystalline region to the total of the crystalline region and the amorphous region of the thermoplastic resin, the degree of crystallinity of the coating region on the central conductor side is greater than that of the coating region on the outer surface side. In this insulated wire, during bending, since the degree of crystallinity on the outer surface side is low, it can stretch well and suppress cracking on the outer surface. When pressurized during winding, it is described that the region with a high degree of crystallinity on the central conductor side can withstand compression and suppress film collapse.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] For example, as described in the above Patent Document 1, when controlling the degree of crystallinity of the insulating layer so that the inner side is lower, two or more insulating layers with different degrees of crystallinity must be provided, which restricts the improvement of manufacturing efficiency.

[0007] An object of the present invention is to provide an insulated electric wire that has excellent adhesion between a conductor and a resin coating layer (a layer containing a crystalline thermoplastic resin), is also excellent in long-term heat resistance, flexibility, and dimensional accuracy (appearance), and can improve manufacturing efficiency. Another object of the present invention is to provide a coil, a rotating electric machine, and an electric and electronic device using this insulated electric wire.

Means for Solving the Problems

[0008] As a result of investigations to solve the above problems, the inventors of the present invention preheat a conductor to a temperature higher than the extrusion temperature during the formation process of the resin coating layer, extrude and coat a resin containing a crystalline thermoplastic resin onto the conductor, hold (heat) it in a die for a certain period of time as it is, and then cool it. By doing so, even when the resin coating layer is a single layer, the crystallinity of the inner region of the resin coating layer can be controlled to be lower than the crystallinity of the outer region of the resin coating layer, and the adhesion between the resin coating layer and the conductor can be effectively enhanced. It has been found that the insulated electric wire thus obtained is excellent in long-term heat resistance, flexibility, and dimensional accuracy. The present invention has been further investigated and completed based on these findings.

[0009] That is, the above problems of the present invention have been solved by the following means. 〔1〕 An insulated electric wire having a conductor and at least one resin coating layer formed on the conductor, wherein the resin coating layer (i) in contact with the conductor among the resin coating layers contains a crystalline thermoplastic resin, and the crystallinity of the inner region of the resin coating layer (i) is lower than the crystallinity of the outer region, and the value obtained by dividing the minimum value of the thickness of the resin coating layer (i) by the maximum value of the thickness is 0.800 or more and 1.000 or less. Insulated electric wire. 〔2〕 The insulated electric wire according to the above 〔1〕, wherein in the resin coating layer (i), the crystallinity of the inner region is 20% or more. 〔3〕 The insulated electric wire according to the above 〔1〕 or 〔2〕, wherein the resin coating layer (i) contains polyaryletherketone and / or polyphenylene sulfide. 〔4〕 The insulated electric wire according to the above 〔3〕, wherein the polyaryletherketone contains one or more of polyetheretherketone, polyetherketoneketone, polyetherketone, and polyetherketoneetherketoneketone. 〔5〕 The insulated electric wire according to any one of the above 〔1〕 to 〔4〕, wherein the conductor is a copper conductor or an aluminum conductor. 〔6〕 A coil using the insulated wire described in 〔5〕 above. 〔7〕 A rotating electrical machine and an electric / electronic device having the coil described in 〔6〕 above.

Advantages of the Invention

[0010] The insulated wire of the present invention has excellent adhesion between the conductor and the resin coating layer (layer containing a crystalline thermoplastic resin) in contact with the conductor, and is further excellent in all of long-term heat resistance, flexibility, and dimensional accuracy, and can be produced at a lower manufacturing cost. Furthermore, according to the present invention, a coil, a rotating electrical machine, and an electric / electronic device using the insulated wire are provided.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0012] Preferred embodiments of the present invention will be described, but the present invention is not limited to the following embodiments except as defined in the present invention.

[0013] In the present invention or in this specification, the shape of the insulated wire including the conductor and the resin coating layer, which is a cross-sectional shape orthogonal to the longitudinal direction of the insulated wire, may be simply referred to as the cross-sectional shape. The cross-sectional shape in the present invention is not merely that only the cut surface has a specific shape, but this cross-sectional shape is continuously connected in the longitudinal direction of the entire insulated wire. Unless otherwise specified, it means that the cross-sectional shape orthogonal to this direction is substantially the same for any part in the longitudinal direction of the insulated wire. In the present invention or in this specification, the numerical range represented by "~" means a range including the numerical values described before and after as the lower limit value and the upper limit value.

[0014] [Insulated wire] The insulated wire of the present invention has a conductor and a resin coating layer that functions as an insulating film and is formed on the conductor. This resin coating layer may have a single-layer structure or a structure of two or more layers. However, the layer of the resin coating layer that contacts the conductor is a layer containing a crystalline thermoplastic resin. Therefore, when the resin coating layer has a single-layer structure, the resin coating layer is a layer containing a crystalline thermoplastic resin. The layer of the resin coating layer that contacts the conductor will be referred to as the resin coating layer (i) in the following description. FIG. 1 shows a cross-sectional view of an embodiment of the insulated wire of the present invention. The insulated wire 1 has a conductor 11 and a resin coating layer (i) 12 containing a crystalline thermoplastic resin extruded and coated on the outer peripheral surface of the conductor 11. In the form shown in FIG. 1, the conductor 11 has a rectangular (flat shape) cross-sectional shape. The cross-sectional shape of the insulated wire 1 of the present invention is preferably similar to that of the conductor 11. The configuration of the insulated wire of the present invention will be described in more detail below.

[0015] [Conductor] As the conductor used in the present invention, those conventionally used for insulated wires can be used, and copper, aluminum, or their alloys can be widely applied. When the conductor is copper (copper conductor), from the viewpoint of preventing the generation of voids during welding, low-oxygen copper with an oxygen content of 30 ppm or less is preferred, and low-oxygen copper or oxygen-free copper with an oxygen content of 20 ppm or less is more preferred. Further, when the conductor is aluminum (aluminum conductor), various aluminum alloys can be used according to the application in consideration of the required mechanical strength. For example, for applications such as rotating electrical machines, pure aluminum with a purity of 99.00% or more, which can obtain a high current value, is preferred.

[0016] The cross-sectional shape perpendicular to the longitudinal direction of the conductor used in the present invention is not particularly limited. For example, conductors having a circular or rectangular (flat shape) cross-sectional shape can be mentioned. In the present invention, a conductor having a rectangular cross-sectional shape, that is, a flat conductor, is preferred. A conductor having a rectangular cross-sectional shape has a higher space occupancy ratio with respect to the slots of the stator core during winding compared to a circular one. Therefore, it is preferred for applications such as incorporating a large number of insulated wires into a certain narrow space. As a preferred example of the conductor used in the present invention, FIG. 1 shows the case where the conductor has a rectangular cross-section (flat shape). The conductor having a rectangular cross-sectional shape is preferably shaped with chamfers (radius of curvature r) provided at the four corners as shown in FIG. 1 in terms of suppressing partial discharge from the corner portions. The radius of curvature r is preferably 0.6 mm or less, and more preferably 0.2 to 0.4 mm. The size of the conductor is not particularly limited. However, in the case of a flat conductor, in the rectangular cross-sectional shape, the width (long side) is preferably 1.0 to 7.0 mm, more preferably 1.4 to 4.0 mm, the thickness (short side) is preferably 0.4 to 3.0 mm, and more preferably 0.5 to 2.5 mm. The ratio of the length of the thickness (short side) to the width (long side) (thickness: width) is preferably 1:1 to 1:4. On the other hand, in the case of a conductor having a circular cross-sectional shape, the diameter is preferably 0.3 to 3.0 mm, and more preferably 0.4 to 2.7 mm.

[0017] <Resin coating layer (i)> The resin coating layer (i) in the insulated wire of the present invention is a layer containing a crystalline thermoplastic resin formed (extrusion-coated) in contact with the conductor.

[0018] The type of the crystalline thermoplastic resin is not particularly limited as long as it is a crystalline (including semi-crystalline) and thermoplastic resin. For example, general-purpose plastics such as polyethylene (PE) (including high-density polyethylene (HDPE), low-density polyethylene (LDPE), etc.), and polypropylene (PP), engineering plastics such as polyamide (PA) (nylon 6, nylon 66), polyacetal (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and ultra-high molecular weight polyethylene (U-PE), super engineering plastics such as aromatic polyamide (PPA), polyamideimide (PAI), polyethersulfone (PES), polybenzimidazole (PBI), polyphenylene sulfide (PPS), polyaryl ether ketone (PAEK), liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), and polyvinylidene fluoride (PVDF), and further polymer alloys containing the above plastics, etc. Among them, the crystalline thermoplastic resin preferably contains PAEK and / or PPS.

[0019] In the present invention or in this specification, "PAEK" is a resin composed of a polymer having a phenylene group, an ether group bonding phenylene groups to each other, and a carbonyl group bonding phenylene groups to each other. The phenylene group may be unsubstituted or may have a substituent within a range that does not impair the effects of the present invention. Examples of such a substituent include an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). Examples of the PAEK include polyether ketone (PEK), polyether ether ketone (PEEK) (including modified polyether ether ketone (modified PEEK)), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK), polyether ketone ester, and the like. The PAEK may be used alone as one of the above resins, or may be used by mixing two or more resin components. Among them, the PAEK preferably contains at least one of polyether ketone (PEK), polyether ether ketone (PEEK), and polyether ketone ketone (PEKK), and more preferably contains PEEK.

[0020] Specific examples of the PAEK and PPS include, for example, commercially available products such as KT-880 (trade name) manufactured by Solvay as PEEK, NovaSpire (trade name) manufactured by Solvay as PEKK, and VICTREX HT (trade name) manufactured by VICTREX as PEK, and commercially available products such as Susteil (trade name) manufactured by Tosoh Corporation as PPS.

[0021] The content of the crystalline thermoplastic resin in the resin coating layer (i) is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, still further preferably 80% by mass or more, and still further preferably 90% by mass or more. Also, the content may be 100% by mass, may be 99% by mass or less, or may be 98% by mass or less. Among the resin coating layer (i), the remainder excluding the crystalline thermoplastic resin may contain various additives described later.

[0022] The thickness of the resin coating layer (i) is not particularly limited and can be 20 to 200 μm, and may be 50 to 100 μm. Further, it is also preferable to be 20 to 50 μm. The thickness of the resin coating layer (i) can be determined by analyzing a cross-sectional image using a microscope with respect to a plane orthogonal to the longitudinal direction of the insulated wire. When the conductor is a flat conductor, in the cross-sectional shape of the flat conductor, without considering the chamfered portions (curved portions) at the four corners, based on the straight lines along the four straight sides, the thickness of the resin coating layer (i) in the direction perpendicular to the side is measured. Note that the resin coating layer (i) corresponding to the four straight sides rather than the chamfered portions at the four corners in the cross-sectional shape of the flat conductor, which is the measurement target of the thickness, has a flat surface. When the conductor cross-section is circular, in the cross-sectional shape of the conductor, the value obtained by subtracting the length corresponding to the radius of the conductor from the length from the center point of the conductor to a certain point of the resin coating layer (i) is defined as the thickness of the resin coating layer (i).

[0023] The insulated wire of the present invention is excellent in dimensional accuracy of the resin coating layer (i), and the absolute value of the film thickness error (the value obtained by subtracting the minimum value of the thickness in the resin coating layer (i) from the maximum value of the thickness) can be controlled to be small. In the insulated wire of the present invention, the absolute value of the film thickness error is preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 16 μm or less. Further, although the smaller the film thickness error is, the more preferable it is, it may be 0 μm or more, 1 μm or more, or 2 μm or more. Also, in the insulated wire of the present invention, the relative value of the film thickness error of the resin coating layer (i) (the value obtained by dividing the minimum value (min) of the thickness of the resin coating layer (i) by the maximum value (max) of the thickness (min / max)) is 0.800 or more and 1.000 or less. The relative value of the film thickness error is preferably 0.850 or more, more preferably 0.900 or more, still more preferably 0.920 or more, still more preferably 0.930 or more, still more preferably 0.940 or more, still more preferably 0.950 or more, still more preferably 0.960 or more, still more preferably 0.970 or more, still more preferably 0.980 or more, still more preferably 0.985 or more, still more preferably 0.990 or more. Also, the error ratio can be 0.999 or less, and can also be 0.995 or less. That the relative value of the film thickness error of the resin coating layer (i) is "1.000" means that the thickness of the resin coating layer (i) is uniform. Incidentally, the maximum value and the minimum value of the thickness in the resin coating layer (i) are determined by measuring the thickness of the entire resin coating layer (i). For example, when the conductor is a flat conductor, instead of the maximum value and the minimum value of the thickness on the same surface, the thicknesses on four surfaces are all measured, and the maximum value and the minimum value are determined. As described above, the maximum value and the minimum value of the thickness in the resin coating layer (i) are, in the case of a flat conductor, the maximum value and the minimum value of the thickness of the resin coating layer (i) on the flat portion excluding the corner portion of the resin coating layer (i).

[0024] The above resin coating layer (i) may contain various additives such as a nucleating agent for foaming, an antioxidant, an antistatic agent, an ultraviolet absorber, a light stabilizer, a fluorescent brightening agent, a pigment, a dye, a compatibilizer, a lubricant, a reinforcing agent, a flame retardant, a crosslinking agent, a crosslinking aid, a plasticizer, a thickening agent, a viscosity reducing agent, and an elastomer, as long as the effects of the present invention are not impaired.

[0025] The insulated wire of the present invention may have another resin coating layer (reinforcing insulating layer) on the outer periphery of the resin coating layer (i). The constituent material of such a reinforcing insulating layer is not particularly limited, and general-purpose thermosetting resins and thermoplastic resins can be applied. Also, the type of resin contained in the reinforcing insulating layer may be the same as or different from the type of resin contained in the resin coating layer (i). For example, examples of the thermosetting resin that may be included in the reinforcing insulating layer include thermosetting resins having an imide bond such as polyimide (PI), polyamideimide (PAI), and polyesterimide (PEsI), polyurethane (PU), thermosetting polyester (PEst), H-type polyester (HPE), polyimide hydantoin-modified polyester, polyhydantoin, polybenzimidazole, melamine resin, or epoxy resin. Also, for example, as the thermoplastic resin that may be included in the reinforcing insulating layer, in addition to the above-described crystalline (or semi-crystalline) thermoplastic resins, amorphous thermoplastic resins such as polyvinyl chloride (PVC), polystyrene (PS), polymethyl methacrylate (PMMA), polycarbonate (PC), modified PPE (m-PPE), polyphenylsulfone (PPSU), polysulfone (PSU), polyarylate (PAR), and polyetherimide (PEI) can also be used. The thickness of the reinforcing insulating layer is not particularly limited and can be appropriately set according to the purpose.

[0026] "Crystallinity" means the ratio of crystalline matter in a sample in which crystalline and amorphous substances are mixed. In the insulating electric wire of the present invention, in the resin coating layer (i), the crystallinity of the inner (conductor side) region is controlled to be lower than that of the outer (outer surface side) region. By thus controlling the crystallinity of the inner region to be low and the crystallinity of the outer region to be high, it is possible to obtain an insulating electric wire that is excellent in flexibility, long-term heat resistance, etc., while sufficiently enhancing the adhesion between the conductor and the resin coating layer (i). In the present invention or this specification, the "outer region of the resin coating layer (i)" means a 50% region located on the outer surface side (opposite to the conductor) when the thickness of the resin coating layer (i) is taken as 100% in the cross-sectional shape of the insulating electric wire, and the "inner region of the resin coating layer" means a 50% region located on the conductor side. The phrase "the crystallinity of the inner region is lower than that of the outer region" can be determined by measuring and comparing the crystallinity of the outer region and the inner region of the resin coating layer (i). This comparison of crystallinity can be carried out by comparing the average values of the crystallinity of each region. The average value of the crystallinity in the comparison of the crystallinity of each region can be, for example, the arithmetic mean value obtained by randomly measuring the crystallinity at 20 locations for each region. As shown in the examples described later, in the thickness direction of the resin coating layer (i), the crystallinity tends to increase or decrease from one side to the other side. Therefore, in the above comparison of crystallinity, when the thickness of the resin coating layer (i) is taken as 100%, the crystallinity (Out) of the 10% region on the outer surface side and the crystallinity (In) of the 10% region on the conductor side are compared. If the crystallinity (In) is lower than the crystallinity (Out), it can be determined that "the crystallinity of the inner region is lower than that of the outer region". For example, as shown in Figure 2, when the region from the outer surface to 10% inward of the resin coating layer (i) is defined as region (I), the central 10% region of the resin coating layer (i) is defined as region (II), and the region from the surface in contact with the conductor of the resin coating layer to 10% outward is defined as region (III), when the crystallinity in these regions satisfies region (I) > region (III), it can be determined that the crystallinity of the inner region is lower than that of the outer region. At this time, the crystallinity of region (II) only needs to be less than or equal to the crystallinity of region (I) and greater than or equal to the crystallinity of region (III), and it may be the same as the crystallinity of region (I) or the same as the crystallinity of region (III).

[0027] In the insulated wire of the present invention, the crystallinity of the inner region in the resin coating layer (i) is preferably 20% or more, more preferably 25% or more, and even more preferably 28% or more. Also, from the viewpoint of the adhesion between the conductor and the resin coating layer (i), the crystallinity of the inner region is preferably 37% or less, more preferably 35% or less, and even more preferably 33% or less. By controlling the crystallinity of the inner region to be low, the flexibility can be further improved. The preferable range of the crystallinity of the inner region is 20 to 37%, more preferably 25 to 35%, and even more preferably 28 to 33%. Further, when the crystallinity of the inner region is 20% or more, since the crystallinity of the outer region exceeds 20%, higher long-term heat resistance can be imparted to the insulated wire of the present invention. From the same viewpoint, the crystallinity of the outer region is preferably 25% or more, more preferably 30% or more, and even more preferably 35% or more. Also, usually the crystallinity of the outer region is 45% or less, may be 42% or less, or may be 40% or less. The preferable range of the crystallinity of the outer region is 25 to 45%, more preferably 30 to 42%, and even more preferably 35 to 40%. Also, the difference between the crystallinity of the inner region and the crystallinity of the outer region (the value obtained by subtracting the crystallinity of the inner region from the crystallinity of the outer region) is preferably 2 to 25%, more preferably 4 to 20%, and even more preferably 6 to 15%.

[0028] For example, when the crystalline thermoplastic resin is PEEK, the crystallinity of the outer region (preferably the region (I)) is preferably 30% or more, more preferably 32% or more, even more preferably 34% or more, and even more preferably 36% or more. Also, the crystallinity is preferably 46% or less, more preferably 44% or less, even more preferably 42% or less, and even more preferably 40% or less. When the crystallinity is shown in the preferable range, it is 30 to 46%, more preferably 32 to 44%, even more preferably 34 to 42%, and even more preferably 36 to 40%. Also, when the crystalline thermoplastic resin is PEEK, the crystallinity of the inner region (preferably, the region (III)) is preferably 22% or more, more preferably 24% or more, still more preferably 26% or more, and even more preferably 28% or more. Further, the crystallinity is preferably 39% or less, more preferably 37% or less, still more preferably 35% or less, and even more preferably 33% or less. When the crystallinity is shown within a preferable range, it is 22 to 39%, more preferably 24 to 37%, still more preferably 26 to 35%, and even more preferably 28 to 33%. When the crystalline thermoplastic resin is PEEK, the difference in crystallinity between the outer region (preferably, the region (I)) and the inner region (preferably, the region (III)) (the value obtained by subtracting the crystallinity of the inner region from the crystallinity of the outer region) is preferably 3% or more, more preferably 4% or more, still more preferably 5% or more, and even more preferably 6% or more. Further, the difference is preferably 24% or less, more preferably 20% or less, still more preferably 16% or less, even more preferably 13% or less, even more preferably 12% or less, even more preferably 11% or less, and even more preferably 10% or less. When the difference is shown within a preferable range, it is 3 to 24%, more preferably 4 to 20%, still more preferably 5 to 16%, even more preferably 6 to 12%, even more preferably 6 to 11%, and even more preferably 6 to 10%.

[0029] In particular, when the crystalline thermoplastic resin is PEEK, the difference in crystallinity between the region (I) and the region (III) is preferably 3 to 13%, more preferably 4 to 12%, still more preferably 5 to 11%, and even more preferably 6 to 10%.

[0030] Further, for example, when the crystalline thermoplastic resin is PEKK, the crystallinity of the outer region (preferably, the region (I)) is preferably 27% or more, more preferably 29% or more, still more preferably 31% or more, and even more preferably 33% or more. Also, the crystallinity is preferably 41% or less, more preferably 39% or less, still more preferably 37% or less, and even more preferably 35% or less. When the crystallinity is shown within a preferred range, it is 27 to 41%, more preferably 29 to 39%, still more preferably 31 to 37%, and even more preferably 33 to 35%. Further, when the crystalline thermoplastic resin is PEKK, the crystallinity of the inner region (preferably, the region (III)) is preferably 20% or more, more preferably 21% or more, still more preferably 22% or more, and even more preferably 24% or more. Also, the crystallinity is preferably 32% or less, more preferably 30% or less, still more preferably 28% or less, and even more preferably 26% or less. When the crystallinity is shown within a preferred range, it is 20 to 32%, more preferably 21 to 30%, still more preferably 22 to 28%, and even more preferably 24 to 26%. When the crystalline thermoplastic resin is PEKK, the difference between the crystallinity of the outer region (preferably, the region (I)) and the crystallinity of the inner region (preferably, the region (III)) (the value obtained by subtracting the crystallinity of the inner region from the crystallinity of the outer region) is preferably 1% or more, more preferably 3% or more, still more preferably 4% or more, even more preferably 5% or more, still more preferably 6% or more, and even more preferably 7% or more. Also, the difference is preferably 21% or less, more preferably 18% or less, still more preferably 15% or less, even more preferably 14% or less, still more preferably 13% or less, even more preferably 12% or less, and even more preferably 11% or less. When the difference is shown within a preferred range, it is 1 to 21%, more preferably 3 to 18%, still more preferably 5 to 15%, and even more preferably 7 to 11%.

[0031] In particular, when the crystalline thermoplastic resin is PEKK, the difference in crystallinity between the region (I) and the region (III) is preferably 4 to 14%, more preferably 5 to 13%, still more preferably 6 to 12%, and still more preferably 7 to 11%.

[0032] For example, when the crystalline thermoplastic resin is PEK, the crystallinity of the outer region (preferably the region (I)) is preferably 26% or more, more preferably 28% or more, still more preferably 30% or more, and still more preferably 32% or more. Also, the crystallinity is preferably 40% or less, more preferably 38% or less, still more preferably 36% or less, and still more preferably 34% or less. When the crystallinity is shown in a preferable range, it is 26 to 40%, preferably 28 to 38%, more preferably 30 to 36%, and still more preferably 32 to 34%. Further, when the crystalline thermoplastic resin is PEK, the crystallinity of the inner region (preferably the region (III)) is preferably 20% or more, more preferably 21% or more, and still more preferably 22% or more. Also, the crystallinity is preferably 30% or less, more preferably 28% or less, still more preferably 26% or less, and still more preferably 24% or less. When the crystallinity is shown in a preferable range, it is 20 to 30%, more preferably 20 to 28%, still more preferably 21 to 26%, and still more preferably 22 to 24%. When the crystalline thermoplastic resin is PEK, the difference in crystallinity between the outer region (preferably the region (I)) and the inner region (preferably the region (III)) (the value obtained by subtracting the crystallinity of the inner region from the crystallinity of the outer region) is preferably 2% or more, more preferably 4% or more, still more preferably 6% or more, and even more preferably 8% or more. Also, the difference is preferably 20% or less, more preferably 18% or less, still more preferably 16% or less, even more preferably 15% or less, even more preferably 14% or less, and even more preferably 12% or less. When the difference is shown within a preferable range, it is 2 to 20%, more preferably 4 to 18%, still more preferably 6 to 16%, even more preferably 6 to 15%, even more preferably 6 to 14%, and even more preferably 8 to 12%.

[0033] In particular, when the crystalline thermoplastic resin is PEK, the difference in crystallinity between the region (I) and the region (III) is preferably 2 to 18%, more preferably 4 to 16%, still more preferably 6 to 14%, and even more preferably 8 to 12%.

[0034] For example, when the crystalline thermoplastic resin is PPS, the crystallinity of the outer region (preferably the region (I)) is preferably 31% or more, more preferably 33% or more, still more preferably 35% or more, and even more preferably 37% or more. Also, the crystallinity is preferably 45% or less, more preferably 43% or less, still more preferably 41% or less, and even more preferably 39% or less. When the crystallinity is shown within a preferable range, it is 31 to 45%, more preferably 33 to 43%, still more preferably 35 to 41%, and even more preferably 37 to 39%. Also, when the crystalline thermoplastic resin is PPS, the crystallinity of the inner region (preferably the region (III)) is preferably 20% or more, more preferably 21% or more, still more preferably 22% or more, and even more preferably 23% or more. Also, the crystallinity is preferably 31% or less, more preferably 29% or less, still more preferably 27% or less, and even more preferably 25% or less. When the crystallinity is shown within a preferable range, it is 20 to 31%, more preferably 21 to 29%, still more preferably 22 to 27%, and even more preferably 23 to 25%. When the crystalline thermoplastic resin is PPS, the difference in crystallinity between the outer region (preferably the region (I)) and the inner region (preferably the region (III)) (the value obtained by subtracting the crystallinity of the inner region from the crystallinity of the outer region) is preferably 2% or more, more preferably 4% or more, still more preferably 6% or more, even more preferably 8% or more, even more preferably 10% or more, and even more preferably 12% or more. Also, the difference is preferably 25% or less, more preferably 24% or less, still more preferably 22% or less, even more preferably 20% or less, even more preferably 19% or less, even more preferably 18% or less, and even more preferably 16% or less. When the difference is shown within a preferable range, it is 2 to 25%, more preferably 4 to 22%, still more preferably 6 to 20%, even more preferably 8 to 19%, even more preferably 10 to 18%, and even more preferably 12 to 16%.

[0035] In particular, when the crystalline thermoplastic resin is PPS, the difference in crystallinity between the region (I) and the region (III) is preferably 4 to 24%, more preferably 6 to 22%, still more preferably 8 to 20%, even more preferably 10 to 18%, and even more preferably 12 to 16%.

[0036] In the present invention, the crystallinity is measured by the following measurement method. <Measurement method> The resin coating layer (i) of the insulated wire is cut into specific regions using an ultramicrotome, and each is used as a measurement sample. X-ray diffraction (XRD) measurement is performed by a transmission method using an X-ray diffractometer (trade name: D8 Discover, manufactured by Bruker). More specifically, it is performed under the following measurement conditions. (Measurement conditions) First slit: 0.5 mm φ Second slit: 0.5 mm φ X-ray wavelength (λ): 0.154 nm X-ray output: 40 kV, 40 mA Camera distance: 100 mm The two-dimensional X-ray diffraction pattern obtained by a two-dimensional detector (trade name: Vantec500, manufactured by Bruker) is made one-dimensional by circular averaging, and air cell scattering correction is performed. The obtained one-dimensional X-ray diffraction profile is fitted with a Gaussian function to separate the crystalline peak and the amorphous peak (halo) using software (trade name: DIFFRAC.EVA V6, manufactured by Bruker), and peak separation is performed. The area of each peak obtained by peak separation is calculated, and the crystallinity Xc is calculated from the obtained area according to the following (Equation 1). Xc (%) = [Ac / (Aa + Ac)] × 100 ··· (Equation 1) Xc: Crystallinity (%) Aa: Amorphous peak area Ac: Crystalline peak area

[0037] As described above, the insulated wire of the present invention is controlled such that the crystallinity of the inner region is lower than that of the outer region of the resin coating layer (i), whereby the adhesion between the conductor and the resin coating layer (i) is excellent. In the insulated wire of the present invention, the adhesion strength (adhesive force) between the conductor and the resin coating layer (i) is preferably 1.0 N / mm or more, more preferably 1.5 N / mm or more, and even more preferably 2.0 N / mm or more. Further, this adhesion strength is usually 10.0 N / mm or less, and may be 5.0 N / mm or less. Note that the adhesion strength between the conductor and the resin coating layer (i) can be determined by the method described in the examples.

[0038] Also, the insulated wire of the present invention is excellent in long-term heat resistance and can maintain a sufficient dielectric breakdown voltage even after heat treatment over a long period. For example, even when the insulated wire of the present invention is heat-treated at 250°C for 168 hours, the value of [dielectric breakdown voltage after heating] / [dielectric breakdown voltage before heating] can be 0.7 or more, can also be 0.8 or more, and can also be 0.9 or more.

[0039] [Method for manufacturing insulated wire] The insulated wire of the present invention described above can be obtained by the method for manufacturing the insulated wire of the present invention (hereinafter, also referred to as "the manufacturing method of the present invention") described below. The insulated wire of the present invention can be obtained by using a conductor as a core wire and, for example, extruding and coating a resin containing the above-mentioned crystalline thermoplastic resin onto the conductor using a screw of an extruder to form a resin coating layer. The extrusion coating method itself can be carried out by a conventional method except for controlling the crystallinity as described below.

[0040] In the insulated wire of the present invention, as a method for controlling the crystallization state of the resin in the resin coating layer (i) such that the crystallinity of the inner region is lower than that of the outer region, for example, a method of preheating the conductor before resin coating to a considerably higher temperature than usual can be mentioned. In general extrusion coating, when preheating the conductor before extrusion coating, the preheating temperature of the conductor is about 200 to 300°C. In the manufacturing method of the present invention, by preheating the conductor to a considerably higher temperature (preferably higher than the temperature of the resin to be extrusion coated), a temperature gradient can be formed in the resin coating layer (i) formed by extrusion coating the conductor such that the temperature of the inner region is higher than that of the outer region. Thereafter, the insulated wire discharged from the extrusion die is air-cooled for the resin coating layer (i) and then water-cooled, whereby the cooling rate of the outer region where the initial resin temperature is low can be slowed down, and the cooling rate of the inner region where the initial resin temperature is high can be accelerated. In the insulated wire thus obtained, the crystallinity of the inner region is lower than that of the outer region. Note that it is preferable to water-cool the insulated wire discharged from the extrusion die when the surface temperature of the resin coating layer (i) has dropped to about the glass transition temperature or below that temperature.

[0041] The temperature of the conductor preheating is not particularly limited as long as a temperature gradient can be formed in the resin coating layer (i) after extrusion coating (including inside the extrusion die after extrusion coating and during air-cooling after die discharge) such that the temperature of the inner region is higher than that of the outer region of the resin as described above. The temperature of the conductor preheating is preferably higher than the melting temperature of the resin used, more preferably [conductor preheating temperature (°C)] > [extrusion temperature (°C)], even more preferably [conductor preheating temperature (°C)] > [extrusion temperature (°C) + 5°C], and even more preferably [conductor preheating temperature (°C)] > [extrusion temperature (°C) + 10°C]. The extrusion temperature can be appropriately set according to the resin used, and it is preferably higher than the melting temperature of the resin used. In addition, in this specification, the above-mentioned "extrusion temperature" means the temperature of the resin when the conductor is coated with the resin. For example, as the extrusion temperature, the temperature inside the barrel can also be regarded as the above-mentioned extrusion temperature.

[0042] In the manufacturing method of the present invention, it is preferable that the conductor before extrusion coating is preheated to a temperature higher than the above-mentioned extrusion temperature as described above. Therefore, it takes time until the surface temperature of the resin coating layer (i) decreases. When an extrusion die with a normal length (land length) of about 5 cm is used, the resin (or a part thereof) in the resin coating layer (i) flows after the insulated wire is discharged, and the dimensional accuracy of the insulating layer deteriorates. Regarding this, by setting the land length of the extrusion die to be long, the dimensional accuracy of the insulated wire obtained by the manufacturing method of the present invention can be maintained in a good state. The land length is preferably 5 cm or more, more preferably 10 cm or more, and even more preferably 15 cm or more. Also, it is practical that the land length is 30 cm or less.

[0043] The temperature of the extrusion die at the land length is not particularly limited and can be set as appropriate. From the viewpoint of gently reducing the cooling rate of the outer region of the resin coating layer (i) and increasing the crystallinity of the outer region, the temperature of the extrusion die at the land length may be the same as the temperature of the resin during resin coating, or may be a temperature equal to or higher than the glass transition temperature of the resin and lower than the melting point. In addition, while the resin coating layer (i) is fixed by applying pressure with an extrusion die, by holding it at a temperature equal to or higher than the glass transition temperature and lower than the melting point for a certain period of time, the dimensional accuracy can be maintained well while more precisely controlling the crystallinity. Note that the above-mentioned "certain period of time" can be controlled as the time when the insulated wire passes through the extrusion die.

[0044] [Coil, rotating electrical machine, and electric / electronic equipment] The insulated electric wire of the present invention can be used as a coil in fields that require electrical characteristics (voltage resistance) and heat resistance, such as rotating electrical machines and various electrical and electronic devices. For example, the insulated electric wire of the present invention is used in motors, transformers, etc., and can constitute high-performance rotating electrical machines and electrical and electronic devices. In particular, it is preferably used as a winding for drive motors of hybrid vehicles (HV) and electric vehicles (EV).

[0045] Examples of the coil of the present invention include those formed by coiling the insulated electric wire of the present invention, and those formed by electrically connecting predetermined portions after bending the insulated electric wire of the present invention. The coil formed by coiling the insulated electric wire of the present invention is not particularly limited, and examples include those obtained by spirally winding a long insulated electric wire. In such a coil, the number of turns of the insulated electric wire is not particularly limited. Usually, an iron core or the like is used when winding the insulated electric wire.

[0046] Examples of the coil formed by electrically connecting predetermined portions after bending the insulated electric wire of the present invention include coils used in stators of rotating electrical machines. Such a coil is, for example, as shown in FIG. 3, the insulated electric wire of the present invention is cut to a predetermined length and bent into a U-shape or the like to produce a plurality of wire segments 34, and two open ends (ends) 34a of the U-shape or the like of each wire segment 34 are alternately connected to produce the coil 33 (see FIGS. 3 and 4).

[0047] The electrical and electronic device using this coil is not particularly limited. A preferred embodiment of such an electrical and electronic device is a transformer. Further, for example, a rotating electrical machine (particularly a drive motor for HV and EV) provided with a stator 30 shown in FIGS. 3 and 4 can be mentioned. This rotating electrical machine can have the same configuration as a conventional rotating electrical machine except that it is provided with a stator 30. The stator 30 can have the same configuration as a conventional stator except that the wire segment 34 is formed of the insulated wire of the present invention. That is, the stator 30 has a stator core 31 and a coil 33 in which a wire segment 34 made of the insulated wire of the present invention, as shown in FIG. 3 for example, is incorporated into a slot 32 of the stator core 31 and open ends 34a are electrically connected. In this coil 33, adjacent fusion layers or a fusion layer and the slot 32 are fixed and immobilized. Here, the wire segment 34 may be incorporated into the slot 32 alone, but is preferably incorporated in pairs of two as shown in FIG. 4. In this stator 30, a coil 33 formed by alternately connecting open ends 34a, which are two ends of the wire segment 34 bent as described above, is housed in a slot 32 of the stator core 31. At this time, the open ends 34a of the wire segment 34 may be connected and then housed in the slot 32, or after the wire segment 34 is housed in the slot 32, the open ends 34a of the wire segment 34 may be bent and connected.

Example

[0048] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these forms.

[0049] Details of the resin used in this example are as follows. -Resin- ·PEEK: PEEK 381G (trade name), glass transition temperature: 143 ° C, melting point: 343 ° C, manufactured by Victrex Japan Co., Ltd. ·PEKK: Super Engineering Plastics PEKK (trade name), glass transition temperature: 162 ° C, melting point: 375 ° C, manufactured by Arkema ·PEK: HT-G22 (trade name), glass transition temperature: 152 ° C, melting point: 373 ° C, manufactured by Victrex Japan Co., Ltd. ·PPS: Durafide 0220A9 (trade name), glass transition temperature: 93 ° C, melting point: 278 ° C, manufactured by Polyplastics Co., Ltd.

[0050] [Example 1] As the conductor, a flat conductor (copper with an oxygen content of 15 ppm) with a flat cross-section (long side 3.5 mm × short side 2.0 mm, and the curvature radius r of the chamfer at the four corners = 0.3 mm) was used, and the copper wire was heated to 430 °C in a nitrogen atmosphere by an induction heating device to preheat the flat copper wire. Using the flat conductor as the core wire, an extruder equipped with a 30 mm full flight screw (screw L / D = 25, screw compression ratio = 3) was used, and an extrusion die with a land length of 150 mm of the extrusion die was used. With the temperature (extrusion temperature) set at 400 °C, a crystalline thermoplastic resin layer (resin coating layer (i)) with an average thickness of 100 μm was formed (extrusion molding) on the outside of the core wire. By water-cooling when the surface temperature of the resin coating layer (i) fell below the glass transition temperature, an insulated wire having an insulating film composed of an extruded layer was obtained. Note that a PEEK resin was used as the crystalline thermoplastic resin.

[0051] [Examples 2 to 5] Except that the type and thickness of the resin constituting the insulating film, the conductor preheating temperature, the extrusion temperature, and the land length of the extrusion die were the same as those described in Table 1 below, the insulated wires of Examples 2 to 5 shown in the following table were produced in the same manner as above.

[0052] [Comparative Examples 1 and 2] Except that the type and thickness of the resin constituting the insulating film, the conductor preheating temperature, the extrusion temperature, and the land length of the extrusion die were the same as those described in Table 1 below, a crystalline thermoplastic resin layer (resin coating layer (i)) was formed (extrusion molding) on the conductor in the same manner as above to obtain the insulated wires of Comparative Examples 1 and 2.

[0053] The properties and physical properties of the obtained insulated wires of Examples 1 to 5, Comparative Examples 1 and 2 were determined by the following tests respectively. The results are summarized in Table 1.

[0054] [Degree of crystallinity] For each resin coating layer of the insulated wires of Examples 1 to 5, Comparative Examples 1 and 2, using an ultramicrotome, the regions were divided into Region (I) (the region from the outer surface of the resin coating layer to 10% inward), Region (II) (the region of the central 10% of the resin coating layer), and Region (III) (the region from the surface of the resin coating layer in contact with the conductor to 10% outward). For each of Regions (I) to (III), X-ray diffraction (XRD) measurements were performed by a transmission method using an X-ray scattering device (trade name: Discover8, manufactured by Bruker). The measurement conditions were as follows. (Measurement conditions) First slit: 0.5 mmφ Second slit: 0.5 mmφ X-ray wavelength (λ): 0.154 nm X-ray output: 40 kV, 40 mA Camera distance: 100 mm The two-dimensional X-ray diffraction pattern obtained by a two-dimensional detector (trade name: Vantec500, manufactured by Bruker) was made one-dimensional by circular averaging, and air cell scattering correction was performed. The obtained one-dimensional X-ray diffraction profile was fitted with a Gaussian function for crystalline peaks and amorphous peaks (halos) using software (trade name: DIFFRAC.EVA V6, manufactured by Bruker) to perform peak separation. The area of each peak obtained by peak separation was calculated, and the crystallinity Xc was calculated according to the following (Equation 1) from the obtained area. The results are shown in Table 1 below. Xc (%) = [Ac / (Aa + Ac)] × 100 ··· (Equation 1) Xc: Crystallinity (%) Aa: Amorphous peak area Ac: Crystalline peak area

[0055] <Dimensional accuracy> Using a microscope, a cross-section of the insulated wire cut perpendicular to its longitudinal axis direction was observed to determine the thickness of the resin coating layer. Then, the film thickness of the resin layer to be measured was measured by the method described above, and the minimum value and maximum value of the film thickness were determined. From the obtained minimum and maximum values, the absolute value of the film thickness error (the value obtained by subtracting the minimum value of the thickness of the resin coating layer from the maximum value of the thickness of the resin coating layer, "dimensional accuracy (absolute value of film thickness error, μm)"), and the relative value of the film thickness error (the value obtained by dividing the minimum value of the thickness of the resin coating layer by the maximum value of the thickness of the resin coating layer, "dimensional accuracy (relative value of film thickness error)") were calculated respectively. The results are shown in Table 1.

[0056] <Conductor adhesion> The adhesion strength between the conductor and the resin coating layer (i) was measured by the following method in accordance with Japanese Industrial Standard: JIS Z 0237 2009. For each of the insulated electric wires of the examples and comparative examples manufactured above, a cut with a width of 1 mm parallel to the longitudinal direction was made for 50 mm or more. This cut reached the conductor. The entire resin coating layer (i) between the cuts was peeled off from the conductor using a tensile testing machine (manufactured by Shimadzu Corporation, device name "Autograph AGSJ"), and the force applied during this peeling (180° peel strength, peel speed 4 mm / min) was measured, and the maximum peel strength was taken as the adhesion strength (adhesive force). The results are shown in Table 1. -Evaluation criteria- ◎: 2 N / mm or more 〇: 1 N / mm or more and less than 2 N / mm ×: Less than 1 N / mm

[0057] <Edgewise bend processability (ductility)> The edgewise bend test was carried out in accordance with JIS C3216-3:2011, except that a cut with a depth of 5 μm was made using a Feather razor S single-edge blade (manufactured by Feather Safety Razor Co., Ltd.) at the bent part of the insulated electric wire, making it a test under more severe conditions. The state when the insulated electric wire with the cut was bent by winding it around a stainless steel rod with a diameter of 1.5 mm so that the cut part was in the center and on the outside was judged based on the following evaluation criteria. -Evaluation criteria- ◎: The cut part also stretched together and the cut did not progress. 〇: Cracks progressed in the insulating coating layer, but did not reach the conductor. ×: The insulating coating is cracked and the crack has spread over the entire surface of the conductor.

[0058] <Long-term heat resistance> The insulated electric wire manufactured above was cut out to a length of 300 mm and heat-treated at 250 °C for 168 hours. After the heat treatment, an aluminum foil was wound around the central part of the insulated electric wire with a width of 20 mm for one turn (that is, an aluminum foil with a width of 20 mm was wound around the part where the distance from one end of the insulated electric wire was 140 mm to 160 mm for one turn). The resin coating layer between 5 mm from one end of this insulated electric wire was peeled off, and an electric charge was applied between the conductor at the terminal peeling part and the aluminum foil part. The voltage was increased at 500 V / second, and the voltage at the time of dielectric breakdown was defined as the "dielectric breakdown voltage after heating". On the other hand, the dielectric breakdown voltage of the insulated electric wire without the above heat treatment was also measured in the same manner and defined as the "dielectric breakdown voltage before heating". Based on the obtained voltage values, the long-term heat resistance was evaluated according to the following evaluation criteria. - Evaluation criteria - ◎: The value of [dielectric breakdown voltage after heating / dielectric breakdown voltage before heating] is 0.9 or more. 〇: The value of [dielectric breakdown voltage after heating / dielectric breakdown voltage before heating] is 0.7 or more and less than 0.9. ×: The value of [dielectric breakdown voltage after heating / dielectric breakdown voltage before heating] is less than 0.7.

[0059]

Table 1

[0060] From Table 1, in the insulated wire of Comparative Example 2 obtained by using PEEK resin and setting the conductor preheating temperature to 260°C, which is the conventional normal preheating temperature, no crystallinity gradient was formed such that the crystallinity in the inner region was lower than that in the outer region. Also, the crystallinity in the inner region showed a high value of 40, resulting in poor conductor adhesion and flexibility. Further, in the insulated wire of Comparative Example 1 obtained by using PEEK resin, setting the conductor preheating temperature to 350°C (a temperature slightly higher than normal conductor preheating), and using an extrusion die with a short normal land length, although the crystallinity in the inner region was low, resulting in excellent conductor adhesion and flexibility, no crystallinity gradient was formed such that the crystallinity in the inner region was lower than that in the outer region, the dimensional accuracy was poor, and the long-term heat resistance was also poor. On the other hand, in the insulated wires of the present invention (Examples 1 to 5) obtained by setting the conductor preheating temperature to a temperature higher than the extrusion temperature and using an extrusion die with a long land length, for the resin coating layer (i) in each case, the crystallinity in the inner region was controlled to be lower than the crystallinity in the outer region, the dimensional accuracy was excellent, and further, all of the conductor adhesion, flexibility, and long-term heat resistance were excellent.

Explanation of Reference Numerals

[0061] 1 Insulated wire 11 Conductor 12 Resin coating layer (i) 30 Stator 31 Stator core 32 Slot 33 Coil 34 Wire segment 34a Open end

Claims

1. An insulated electric wire having a conductor and at least one resin coating layer formed on the conductor, wherein the resin coating layer (i) in contact with the conductor among the resin coating layers contains a crystalline thermoplastic resin, and the crystallinity of the inner region of the resin coating layer (i) is lower than that of the outer region, and the value obtained by dividing the minimum value of the thickness of the resin coating layer (i) by the maximum value of the thickness is 0.800 or more and 1.000 or less. Insulated electric wire.

2. The insulated electric wire according to Claim 1, wherein in the resin coating layer (i), the crystallinity of the inner region is 20% or more.

3. The insulated electric wire according to Claim 1 or 2, wherein the resin coating layer (i) contains polyaryletherketone and / or polyphenylene sulfide.

4. The insulated electric wire according to Claim 3, wherein the polyaryletherketone contains one or more of polyetheretherketone, polyetherketoneketone, polyetherketone, and polyetherketoneetherketoneketone.

5. The insulated electric wire according to Claim 1 or 2, wherein the conductor is a copper conductor or an aluminum conductor.

6. A coil using the insulated electric wire according to Claim 5.

7. A rotating electric machine and an electric / electronic device having the coil according to Claim 6.

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