Heat-resistant electric wire

Abstract

The present disclosure provides a heat-resistant electric wire which has excellent characteristics as an electric wire while suppressing the amount of fluorine-based resin used. A heat-resistant electric wire has: a conductor; and an insulator covering the conductor, the ratio of the outer diameter of the conductor to the outer diameter of the insulator being 0.45-0.55, the conductor being a compressed conductor obtained by compressing a twisted wire obtained by twisting a plurality of conductor wires, the insulator containing, as a resin material, one or more types selected from the group consisting of a fluororesin and a fluororubber, the insulator includes voids, and the void ratio of the insulator is 10% or more and 60% or less.

Description

Technical Field

[0001] The present disclosure relates to a heat-resistant electric wire. Background Art

[0002] Patent Document 1 discloses an electrically insulated cable using cross-linked fluororubber for an insulation layer.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-106131

[0006] In order to improve heat resistance, etc., fluorine-based resins such as fluororubber have been used for insulating wires in the past. However, in recent years, from the perspective of SDGs (Sustainable Development Goals), there is a demand for wires that have excellent properties as wires in terms of withstand voltage characteristics, elongation tensile strength, etc., and that reduce the amount of fluorine-based resins used. Summary of the invention

[0007] Therefore, an object of the present disclosure is to provide a heat-resistant electric wire having excellent characteristics as an electric wire while suppressing the usage amount of a fluorine-based resin.

[0008] The heat-resistant electric wire disclosed herein comprises: a conductor; and an insulator covering the conductor, wherein a ratio of an outer diameter of the conductor to an outer diameter of the insulator is greater than or equal to 0.45 and less than or equal to 0.55, wherein the conductor is a compressed conductor obtained by compressing a stranded wire formed by twisting a plurality of conductor wires, wherein the insulator contains one or more selected from fluororesins and fluororubbers as a resin material, and wherein the insulator contains voids, and wherein a void ratio of the insulator is greater than or equal to 10% and less than or equal to 60%.

[0009] Effects of the Invention

[0010] According to the present disclosure, it is possible to provide a heat-resistant electric wire having excellent characteristics as an electric wire while suppressing the usage amount of a fluorine-based resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a cross-sectional view of a heat-resistant electric wire according to one aspect of the present disclosure, taken along a plane perpendicular to the longitudinal direction.

[0012] Figure 2A This is a diagram for explaining Dmax used in calculating the void ratio.

[0013] Figure 2B This is a diagram for explaining Dmin used in calculating the void ratio.

[0014] Figure 3 This is a partial perspective view of an extruder that can be used when manufacturing a heat-resistant electric wire according to one embodiment of the present disclosure.

[0015] Figure 4 This is a cross-sectional view of the heat-resistant electric wire produced in Experimental Example 2, taken along a plane perpendicular to the longitudinal direction.

[0016] Description of Reference Numerals

[0017] 10: Heat-resistant wire;

[0018] 40: Heat-resistant wire;

[0019] 11: Conductor (compressed conductor);

[0020] 111: conductor wire;

[0021] 11A: aggregate;

[0022] 11B: aggregate;

[0023] 11C: Conductor (conductor without compression);

[0024] 112: gap;

[0025] 12: Insulator;

[0026] 121: first solid layer;

[0027] 122: void containing layer;

[0028] 123: second solid layer;

[0029] 13: gap;

[0030] D11: outer diameter of the conductor;

[0031] Dmax: outer diameter of the conductor (maximum value);

[0032] Dmin: outer diameter of the conductor (minimum value);

[0033] D11C: outer diameter of the conductor;

[0034] D12: outer diameter of the insulator;

[0035] 30: Extruder;

[0036] 31: Mould;

[0037] 311: Export;

[0038] 32: point fixture;

[0039] 321: cylindrical part;

[0040] 322: center hole;

[0041] 33: Columnar member;

[0042] 331: vent;

[0043] 34: Flow path;

[0044] 35: Flow path. DETAILED DESCRIPTION

[0045] Hereinafter, specific implementation methods will be described.

[0046] [Description of Embodiments of the Present Disclosure]

[0047] First, the embodiments of the present disclosure will be described by way of example. In the following description, the same reference numerals are given to the same or corresponding elements, and the same description thereof will not be repeated.

[0048] (1) A heat-resistant electric wire according to one embodiment of the present disclosure comprises: a conductor; and an insulator covering the conductor, wherein a ratio of an outer diameter of the conductor to an outer diameter of the insulator is 0.45 or more and 0.55 or less, the conductor being a compressed conductor obtained by compressing a stranded wire formed by twisting a plurality of conductor wires, the insulator containing one or more selected from fluororesins and fluororubbers as a resin material, and the insulator containing voids, and the void ratio of the insulator being 10% or more and 60% or less.

[0049] The insulator may contain fluorine-based resin such as fluororesin or fluororubber as a resin material. However, since the insulator includes voids, the amount of fluorine-based resin used can be reduced.

[0050] By using a compressed conductor as the conductor, the size of the gap between the conductor wires constituting the conductor can be suppressed. Therefore, it is possible to suppress the material of the insulator covering the conductor from entering between the conductor wires constituting the conductor, and the shape of the gap in the insulator can be formed into a desired shape. In addition, the thickness of the insulator can be suppressed from being uneven.

[0051] As a result, the withstand voltage characteristics and elongation tensile strength of the heat-resistant electric wire according to one aspect of the present disclosure can satisfy the required standards.

[0052] By setting the ratio of the outer diameter of the conductor to the outer diameter of the insulator to 0.55 or less, the thickness of the insulator can be sufficiently ensured, and the withstand voltage characteristics and elongation tensile strength of the heat-resistant electric wire according to one aspect of the present disclosure can be particularly improved.

[0053] By setting the ratio of the outer diameter of the conductor to the outer diameter of the insulator to be 0.45 or more, it is possible to suppress the insulator from becoming too thick, thereby improving workability during wiring, handling efficiency during transportation, and the like.

[0054] By setting the porosity of the insulator to 10% or more, the amount of fluorine-based resin used can be reduced. In addition, the weight of the heat-resistant wire can be reduced, and the workability during wiring and the handling during transportation can be improved.

[0055] By setting the void ratio of the insulator to 60% or less, the ratio of the resin portion contained in the insulator can be increased, and the withstand voltage characteristics and tensile strength of the heat-resistant electric wire according to one aspect of the present disclosure can be particularly improved.

[0056] (2) In (1), the insulator may have a porosity of 40% or more and 60% or less.

[0057] By setting the porosity of the insulator to be 40% or more and 60% or less, the amount of fluorine-based resin used can be particularly reduced, and the weight of the heat-resistant wire can be reduced, which can particularly improve the workability during wiring and the operability during transportation. In addition, the withstand voltage characteristics and elongation tensile strength of the heat-resistant wire of one embodiment of the present disclosure can be improved.

[0058] [Details of the embodiments of the present disclosure]

[0059] Hereinafter, a specific example of a heat-resistant wire of one embodiment of the present disclosure (hereinafter referred to as "this embodiment") is described with reference to the accompanying drawings. It should be noted that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0060] (Heat-resistant wire)

[0061] Figure 1 1 shows a configuration example of a cross section perpendicular to the longitudinal direction of the heat-resistant electric wire according to the present embodiment.

[0062] like Figure 1 As shown, the heat-resistant electric wire 10 of the present embodiment includes: a conductor 11 ; and an insulator 12 covering the conductor 11 .

[0063] Hereinafter, each member included in the heat-resistant electric wire 10 of the present embodiment will be described.

[0064] (1) Conductor

[0065] (1-1) About materials

[0066] like Figure 1 As shown, the conductor 11 may be a compressed conductor obtained by compressing a stranded wire obtained by twisting a plurality of conductor wires 111 , and more specifically, a compressed conductor obtained by compressing the stranded wire from the outer circumference, for example.

[0067] By using a compressed conductor as the conductor 11, the size of the gap 112 generated between the conductor wires 111 constituting the conductor 11 can be suppressed. Therefore, it is possible to suppress the material of the insulator 12 covering the conductor 11 from entering between the conductor wires 111 constituting the conductor 11, and the shape of the gap 13 possessed by the insulator 12 can be formed into a desired shape. In addition, the unevenness of the thickness of the insulator 12 can be suppressed.

[0068] As a result, the heat-resistant electric wire 10 of the present embodiment can satisfy the required standards in terms of withstand voltage characteristics and elongation tensile strength.

[0069] The withstand voltage characteristic refers to the insulation characteristic of the insulator 12 included in the heat-resistant electric wire 10 of the present embodiment.

[0070] The tensile strength after elongation refers to the elongation until the insulation 12 of the heat-resistant electric wire 10 of the present embodiment is broken when the insulation 12 is pulled at a predetermined speed in the longitudinal direction.

[0071] The material of the conductor wire 111 constituting the conductor 11 is not particularly limited, but for example, one or more conductor materials selected from copper, copper alloy, silver-plated annealed copper, and tin-plated annealed copper can be used. As copper, annealed copper can be preferably used.

[0072] (1-2) Compression rate

[0073] The compression rate, which is the degree of compression of the conductor 11 , is not particularly limited, but can be set to, for example, 30% or more and 70% or less.

[0074] By setting the compression rate of the conductor 11 to 30% or more, the size of the gaps generated between the conductor wires 111 constituting the conductor 11 can be particularly suppressed. Therefore, the shape of the gaps in the insulator 12 can be particularly easily controlled and can be formed into a desired shape. Therefore, the withstand voltage characteristics and elongation tensile strength of the heat-resistant wire 10 can be particularly improved.

[0075] By setting the compression rate of the conductor 11 to 70% or less, the time required to compress the strands of the conductor wires 111 when manufacturing the compressed conductor can be reduced, and the productivity of the heat-resistant electric wire 10 can be improved.

[0076] When calculating the circle equivalent diameter of the conductor wire 111, first, the cross-sectional area of ​​the conductor 11 after removing the gap 112 in any cross section of the conductor 11 is measured, and the number of conductor wires included in the conductor is counted. Next, the calculated cross-sectional area of ​​the conductor 11 is divided by the number of conductor wires 111 to obtain the cross-sectional area of ​​each conductor wire 111. Then, the diameter of a circle having the cross-sectional area of ​​the conductor wire 111 (circle equivalent diameter of the conductor wire 111) is calculated.

[0077] Then, if Figure 2A As shown in FIG. 1 , the diameter of the circumscribed circle of the aggregate 11A when the circles found above are in contact with each other and the aggregate of the circles is in a shape closest to a circle is found, and this diameter is set as Dmax.

[0078] Then, if Figure 2B As shown, assuming that the conductor (assembly 11B) becomes a circle when the compression rate is 100%, that is, when the conductor wires 111 are compressed so that the gaps 112 between them completely disappear, the diameter of the circle is determined and is defined as Dmin.

[0079] Then, the compression rate R can be calculated by the following equation (1) based on the outer diameter D11 of the conductor 11 for which the compression rate is to be calculated.

[0080] R=(Dmax-D11)÷(Dmax-Dmin)×100……(1)

[0081] (2) Insulator

[0082] (2-1) About resin materials

[0083] The insulator 12 may contain one or more selected from fluororesins and fluororubbers as a resin material. When the insulator 12 contains one or more selected from fluororesins and fluororubbers as a resin material, heat resistance can be imparted to the heat-resistant wire 10 .

[0084] For example, as the fluororesin, one or more selected from ethylene-tetrafluoroethylene copolymer (E-TFE copolymer), polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyvinylidene fluoride resin (PVDF) and the like can be used.

[0085] For example, as the fluororubber, one or more selected from vinylidene fluoride rubber (FKM), tetrafluoroethylene-propylene rubber (FEPM), tetrafluoroethylene-perfluoromethyl vinyl ether rubber (FFKM), tetrafluoroethylene / propylene copolymer (TFE-P copolymer), a mixture of TFE-P copolymer and ethylene-tetrafluoroethylene copolymer (E-TFE copolymer), and a mixture of FKM and vinylidene fluoride resin (PVDF) can be used.

[0086] The insulator 12 may contain additives such as a filler and a lubricant in addition to the resin material.

[0087] The resin material included in the insulator 12 may or may not be cross-linked.

[0088] (2-2) Regarding the gap

[0089] (About the shape of the gap)

[0090] The insulator 12 may contain voids 13 .

[0091] The insulator 12 may include fluorine-based resin such as fluorine resin or fluorine rubber as a resin material. However, since the insulator 12 includes the voids 13 , the amount of fluorine-based resin used can be reduced.

[0092] The form of the gaps 13 included in the insulator 12 is not particularly limited.

[0093] For example, the void 13 may have a shape that is continuous along the long dimension direction of the heat-resistant wire 10. For example, the void 13 may have a columnar shape in which the central axis of the void 13 is formed along the long dimension direction of the conductor 11. Figure 1 In the figure, an example in which the cross section of the void 13 is circular, i.e., cylindrical, is shown, but the present invention is not limited to this form, and the shape of the cross section perpendicular to the long dimension direction of the conductor 11 may also be a polygonal columnar shape such as a quadrilateral or a triangle. When the void 13 has a columnar shape, the porosity of the insulator 12 and the arrangement of the void 13 in the insulator 12 can be accurately controlled, and therefore, it is preferred.

[0094] It should be noted that the columnar shape of the void 13 does not have a strict geometrical meaning, and for example, the shape and size of the cross section of the void 13 perpendicular to the longitudinal direction may vary depending on the location due to errors in the manufacturing process.

[0095] (About porosity)

[0096] In the insulator 12 , the porosity is not particularly limited, but is preferably 10% or more and 60% or less.

[0097] By setting the porosity of the insulator 12 to 10% or more, the amount of fluorine-based resin used can be reduced. In addition, the weight of the heat-resistant wire 10 can be reduced, and the workability during wiring and the handling during transportation can be improved.

[0098] By setting the porosity of the insulator 12 to 60% or less, the ratio of the resin portion contained in the insulator 12 can be increased, and the withstand voltage characteristics and elongation tensile strength of the heat-resistant wire 10 can be particularly improved.

[0099] The porosity of the insulator 12 is more preferably 40% or more and 60% or less.

[0100] By setting the porosity of the insulator 12 to 40% or more and 60% or less, the amount of fluorine-based resin used can be particularly reduced, and the weight of the heat-resistant wire 10 can be reduced, which can improve the workability during wiring and the handling during transportation. In addition, the withstand voltage characteristics and elongation tensile strength of the heat-resistant wire 10 can be improved.

[0101] The porosity of the insulator 12 refers to the area ratio of the voids 13 in the insulator 12 found in any cross section perpendicular to the longitudinal direction of the heat-resistant wire 10 .

[0102] (2-3) Method for manufacturing an insulator

[0103] Figure 1 The insulator 12 shown including the voids 13 may be used, for example, Figure 3 The extruder 30 shown is a combination of a die 31 and a point fixture 32.

[0104] The columnar members 33 may be provided in advance on the spot jig 32 in the same number as the number of the gaps 13 to be provided in the insulator 12. The columnar members 33 may be formed in a shape corresponding to the shape of the gaps 13.

[0105] The die 31 has a circular outlet 311, and the resin is extruded from the flow paths 34 and 35 between the point jig 32 and the die 31. At this time, the conductor is pulled out from the center hole 322 of the cylindrical portion 321 of the point jig 32. By performing the above operation, the extruded resin covers the conductor. At this time, the resin does not flow to the columnar member 33, so a gap is formed in the resin.

[0106] The resin coating can be performed by a drawing method in which the resin coming out of the outlet of the die 31 is stretched to reduce the diameter for coating.

[0107] The columnar member 33 may be provided with a vent hole 331 so as to communicate with the outside atmosphere and blow air into the voids formed in the resin.

[0108] In the above-described extruder 30 , the void ratio of the insulator can be easily adjusted by adjusting the diameter and number of the columnar members 33 provided in the spot jig 32 .

[0109] (2-4) Regarding the structure of the insulator 12

[0110] The insulator 12 may have a solid layer that does not contain voids 13 in addition to the void-containing layer 122 that contains voids 13 .

[0111] For example Figure 1 As shown, the insulator 12 may include a first solid layer 121 at a position closer to the conductor 11 than the void-containing layer 122. In addition, the insulator 12 may include a second solid layer 123 at a position farther from the conductor 11 than the void-containing layer 122.

[0112] Only one of the first solid layer 121 and the second solid layer 123 may be provided, but from the viewpoint of improving the withstand voltage characteristics and tensile strength of the heat-resistant wire 10 , it is preferable to provide both.

[0113] The first solid layer 121 , the void-containing layer 122 , and the second solid layer 123 may have the same structure except for the presence or absence of the voids 13 , and may be formed integrally.

[0114] (3) Outer diameter of the insulator

[0115] The outer diameter D11 of the conductor 11 and the outer diameter D12 of the insulator 12 are not particularly limited. For example, the ratio D11 / D12 of the outer diameter D11 of the conductor 11 to the outer diameter D12 of the insulator 12 may be set to 0.45 or more and 0.55 or less.

[0116] By setting D11 / D12 to be 0.55 or less, the thickness of the insulator 12 can be sufficiently ensured, and the withstand voltage characteristics and elongation tensile strength of the heat-resistant wire 10 can be particularly improved.

[0117] By setting D11 / D12 to be 0.45 or more, it is possible to suppress the insulator 12 from becoming too thick, thereby improving workability during wiring, operability during transportation, and the like.

[0118] [Example]

[0119] Hereinafter, specific examples will be given for description, but the present invention is not limited to these examples.

[0120] (Evaluation method)

[0121] First, a method for evaluating the heat-resistant electric wires produced in the following experimental examples will be described.

[0122] (1) The outer diameter of the conductor and the outer diameter of the insulator

[0123] The outer diameter D11 of the conductor 11 and the outer diameter D12 of the insulator 12 were measured in accordance with JIS C 3005 (2014).

[0124] Specifically, in any cross section perpendicular (at right angles) to the longitudinal direction of the heat-resistant wire 10 , the outer diameter of the conductor 11 is measured along two orthogonal diameters, and the average value is defined as the outer diameter D11 of the conductor 11 .

[0125] Here, the conductor 11 is described as an example, but the outer diameter D12 of the insulator 12 can be obtained by the same procedure except that the insulator 12 is used as the evaluation object.

[0126] Furthermore, D11 / D12 is calculated from the measured outer diameter D11 of the conductor 11 and the outer diameter D12 of the insulator 12 .

[0127] In the heat-resistant electric wire 40 of Experimental Example 2, the outer diameter D11C of the conductor 11C is obtained in place of the conductor 11 by the same procedure as in the case of the outer diameter D11 of the conductor 11 , and D11C / D12 is calculated.

[0128] (2) Compression rate of conductor

[0129] The method of obtaining the conductor compression rate has been described above, so the description is omitted.

[0130] (3) Porosity of insulator

[0131] The area ratio of the voids 13 in the insulator 12 obtained in any cross section perpendicular to the longitudinal direction of the heat-resistant electric wire is defined as the porosity of the insulator 12 .

[0132] (4) Withstand voltage test

[0133] In the withstand voltage test, the evaluation test was conducted in accordance with JIS C 3005 (2014). The heat-resistant wire was placed in water for evaluation. The heat-resistant wire with a withstand voltage of 1000VAC / 1min or more was evaluated as A, and the heat-resistant wire with a withstand voltage of less than 1000VAC / 1min was evaluated as B.

[0134] When the evaluation is A, it means that the heat-resistant electric wire is excellent in withstand voltage characteristics, and when the evaluation is B, it means that the withstand voltage characteristics are insufficient.

[0135] (5) Elongation tensile strength

[0136] Regarding the elongation tensile strength, the conductor 11 of the heat-resistant electric wire produced in the experimental example was removed, and the insulator 12 portion was evaluated.

[0137] The sample to be evaluated was subjected to a tensile test with the distance between the marking lines set to 25 mm and the tensile speed set to 50 mm / min, and the elongation tensile strength (%) was measured and calculated.

[0138] The elongation tensile strength ε can be calculated by the following formula (2).

[0139] ε=(L1-L0) / L0×100……(2)

[0140] In the formula (2), L1 is the distance between the marking lines at the time of cutting, and L0 is the distance between the marking lines before the start of the test (25 mm).

[0141] When the tensile strength at elongation ε was 100% or more, the evaluation was A, and when the tensile strength at elongation ε was less than 100%, the evaluation was B.

[0142] When the evaluation is A, it means that the heat-resistant electric wire has sufficient elongation tensile strength, and when the evaluation is B, it means that the elongation tensile strength is insufficient.

[0143] Hereinafter, the heat-resistant electric wire in each experimental example will be described.

[0144] Experimental Example 1 is an embodiment, and Experimental Example 2 is a comparative example.

[0145] [Experimental Example 1]

[0146] Produce a Figure 1 A heat-resistant electric wire 10 having the cross-sectional shape shown was prepared and evaluated.

[0147] The conductor 11 was prepared by twisting 12 conductor wires 111, which were annealed copper wires, into a stranded wire. The stranded wire was compressed from the outside to form a compressed conductor, which was used as the conductor 11. The compression rate of the conductor 11 was 52%.

[0148] The insulator 12 includes a first solid layer 121 and a second solid layer 123 in addition to a void-containing layer 122 including voids 13 .

[0149] Insulator 12 use Figure 3 The insulator 12 is manufactured by extruding and pulling the fluororubber using an extruder 30 composed of a die 31 and a point jig 32. Tetrafluoroethylene-propylene rubber (FEPM) is used as the fluororubber.

[0150] The insulator 12 has columnar voids 13 that are continuous along the longitudinal direction of the heat-resistant wire 10, and the void ratio is 40%. The ratio D11 / D12 of the outer diameter D11 of the conductor 11 to the outer diameter D12 of the insulator 12 is 0.47.

[0151] Table 1 shows the evaluation results.

[0152] [Experimental Example 2]

[0153] Produce a Figure 4 A heat-resistant electric wire 40 having the cross-sectional shape shown was prepared and evaluated.

[0154] Figure 4 The heat-resistant electric wire 40 shown uses a conductor 11C that is not compressed, instead of the conductor 11 that is a compressed conductor. A heat-resistant electric wire was produced under the same conditions as in the case of Experimental Example 1 except for the above point.

[0155] Table 1 shows the evaluation results.

[0156] [Table 1]

[0157] Experimental Example 1 Experimental Example 2 Compression ratio [%] 52 0 Withstand voltage test A B Elongation tensile strength A B

Claims

1. A heat-resistant electric wire having: Conductors; and an insulator, covering the conductor, The ratio of the outer diameter of the conductor to the outer diameter of the insulator is 0.45 or more and 0.55 or less, The conductor is a compressed conductor obtained by compressing a stranded wire formed by twisting a plurality of conductor wires. The insulator includes one or more selected from fluororesins and fluororubbers as a resin material, and the insulator includes voids, The insulator has a porosity of 10% to 60%.

2. The heat-resistant electric wire according to claim 1, wherein The insulator has a porosity of 40% to 60%.

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