Wires and multi-core cables

Abstract

The electric wire includes a conductor and a coating that coats the conductor. The coating includes a first layer and a second layer formed on the first layer. The first layer contains a fluororesin as a main component, and the second layer contains silsesquioxane as a main component. The silsesquioxane is (RSiO 3 / 2 ) as a constituent unit, wherein R is a polymerizable group, and the second layer has a thickness of 0.1 μm or more and 100 μm or less.

Description

[Technical field]

[0001] The present disclosure relates to electrical wires and multi-conductor cables. [Background technology]

[0002] Conventionally, "electric wires having a conductor and a coating that covers the conductor" and "multi-core cables having an electric wire" have been used for various purposes such as automobiles, aircraft, rockets, artificial satellites, industrial robots, electrical equipment, and thermal equipment (Patent Documents 1 to 5). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-288914 [Patent Document 2] Japanese Utility Model Application Publication No. 4-61808 [Patent Document 3] JP 2000-30535 A [Patent Document 4] Japanese Patent Application Publication No. 8-255513 [Patent Document 5] JP 2016-192374 A Summary of the Invention

[0004] The electric wire of the present disclosure comprises: An electric wire comprising a conductor and a coating covering the conductor, The coating includes a first layer and a second layer formed on the first layer, The first layer contains a fluororesin as a main component, The second layer contains silsesquioxane as a main component, The silsesquioxane is (RSiO 3 / 2 ) is a polymer having structural units, R is a polymerizable group, The second layer has a thickness of 0.1 μm or more and 100 μm or less. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a schematic perspective view of an electric wire according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. [Diagram 3] FIG. 3 is a schematic diagram illustrating a part of the evaluation method of Evaluation Tests 1 to 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] [Problem that this disclosure aims to solve] When electric wires are used for various purposes such as automobiles, aircraft, rockets, artificial satellites, industrial robots, electrical equipment, and thermal equipment, the conditions under which the electric wires are used may be severe. In particular, when the temperature conditions among the conditions under which the electric wires are used are severe, it is required to prevent oxidative degradation due to oxygen, ozone, atomic oxygen, and the like, and to impart excellent heat resistance to the electric wires. Oxidative degradation progresses as oxygen in the air reacts with a polymer. Oxidative degradation tends to be accelerated as the temperature increases. This is because the higher the temperature, the easier it is for oxygen molecules to diffuse in a polymer, and the easier it is for the polymer to react with oxygen. When the temperature conditions are severe, by suppressing oxidative degradation, it is possible to suppress deterioration of the electric wire due to heating (in other words, it is possible to improve the heat resistance of the electric wire).

[0007] Therefore, an object of the present disclosure is to provide an electric wire having excellent heat resistance and a multi-core cable including the electric wire.

[0008] [Effects of this disclosure] According to the present disclosure, it is possible to provide an electric wire having excellent heat resistance and a multi-core cable including the electric wire.

[0009] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described. (1) The electric wire of the present disclosure is An electric wire comprising a conductor and a coating covering the conductor, The coating includes a first layer and a second layer formed on the first layer, The first layer contains a fluororesin as a main component, The second layer contains silsesquioxane as a main component, The silsesquioxane is (RSiO 3 / 2 ) is a polymer having structural units, The R is a polymerizable group, The second layer has a thickness of not less than 0.1 μm and not more than 100 μm.

[0010] According to the present disclosure, it is possible to provide an electric wire having excellent heat resistance and a multi-core cable including the electric wire.

[0011] (2) In the above (1), the fluororesin of the first layer may be at least one fluororesin selected from the group consisting of perfluoroalkoxyalkane resin, fluorinated ethylene propylene resin, ethylene tetrafluoroethylene copolymer resin, and crosslinked ethylene tetrafluoroethylene copolymer resin, thereby making it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0012] (3) In the above (1), the fluororesin of the first layer may be a resin modified with a first functional group, and the first functional group may have a carboxyl group or an ether group. This makes it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0013] (4) In the above (3), the first functional group may be at least one functional group selected from the group consisting of a carboxyl group, a maleic anhydride group, and an epoxy group, thereby making it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0014] (5) In the above (1), the fluororesin of the first layer may be a resin that has been subjected to a hydrophilic surface treatment, thereby making it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0015] (6) In the above (5), the hydrophilic surface treatment may be at least one surface treatment selected from the group consisting of corona treatment, plasma treatment, ozone treatment, and etching treatment with active sodium, thereby making it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0016] (7) In any one of the above (1) to (6), the coating may further include a third layer formed between the first layer and the second layer, and the third layer may include a fluororesin as a main component. This makes it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0017] (8) In the above (7), the fluororesin of the third layer may be at least one fluororesin selected from the group consisting of perfluoroalkoxyalkane resin, fluorinated ethylene propylene resin, ethylene tetrafluoroethylene copolymer resin, and crosslinked ethylene tetrafluoroethylene copolymer resin, thereby making it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0018] (9) In the above (7), the fluororesin of the third layer may be a resin modified with a second functional group, and the second functional group may have a carboxyl group or an ether group. This makes it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0019] (10) In the above (9), the second functional group may be at least one functional group selected from the group consisting of a carboxyl group, a maleic anhydride group, and an epoxy group, thereby making it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0020] (11) In any one of the above (1) to (10), the polymerizable group may be a radically polymerizable group or a cationic polymerizable group, thereby making it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0021] (12) In any one of the above (1) to (10), the polymerizable group may be one type of polymerizable group selected from the group consisting of an acryloyl group, a methacryloyl group, and an oxetanyl group, thereby making it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0022] (13) The multi-core cable of the present disclosure comprises: The electric wire is provided as described in (1) to (12) above.

[0023] According to the present disclosure, it is possible to provide a multi-core cable including electric wires having excellent heat resistance.

[0024] [Details of the embodiment of the present disclosure] Specific examples of electric wires and multi-core cables according to an embodiment of the present disclosure (hereinafter also referred to as the "present embodiment") will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference symbols represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0025] In this disclosure, an expression in the form "A to B" means the upper and lower limits of a range (i.e., A or more and B or less). When no unit is specified for A and a unit is specified only for B, the unit of A and the unit of B are the same.

[0026] In the present disclosure, when a compound or the like is represented by a chemical formula, unless the atomic ratio is particularly limited, it is intended to include any conventionally known atomic ratio, and should not necessarily be limited to only those within the stoichiometric range.

[0027] [Embodiment 1: Electric Wire] An electric wire according to an embodiment of the present disclosure will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a schematic perspective view of an electric wire according to an embodiment of the present disclosure. Fig. 2 is a schematic cross-sectional view taken along II-II in Fig. 1. One embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") is An electric wire 1 including a conductor 2 and a coating 5 that covers the conductor 2, The coating 5 includes a first layer 3 and a second layer 4 formed on the first layer 3, The first layer 3 contains a fluororesin as a main component, The second layer 4 contains silsesquioxane as a main component, The silsesquioxane is (RSiO 3 / 2 ) is a polymer having structural units, R is a polymerizable group, The second layer 4 has a thickness of 0.1 μm or more and 100 μm or less.

[0028] According to the present disclosure, it is possible to provide an electric wire 1 having excellent heat resistance and a multi-core cable including the electric wire 1. The reason for this is presumably as follows.

[0029] In the electric wire 1 of the present embodiment, the coating 5 includes a first layer 3 and a second layer 4 formed on the first layer 3. The first layer 3 includes a fluororesin as a main component, and the second layer 4 includes a silsesquioxane as a main component. The silsesquioxane is (RSiO 3 / 2) as a constituent unit, R is a polymerizable group, and the thickness of the second layer 4 is 0.1 μm or more and 100 μm or less. Since the second layer 4 serves as a dense protective film, it is possible to prevent oxidative deterioration due to oxygen in the air, and therefore it is possible to provide an electric wire 1 having excellent heat resistance and a multi-core cable including the electric wire 1.

[0030] ≪Electric wire≫ The equivalent circle diameter of a cross section perpendicular to the longitudinal direction of the electric wire 1 may be 0.1 mm or more and 50 mm or less, 0.2 mm or more and 20 mm or less, or 0.5 mm or more and 10 mm or less. Here, the longitudinal direction can be rephrased as a "first direction" described later.

[0031] The equivalent circle diameter of the cross section perpendicular to the longitudinal direction of the electric wire 1 can be determined by the following method. First, the average cross-sectional area of ​​the electric wire 1 is determined by the same method as for the average cross-sectional area of ​​the conductor 2, except that the measurement target is the electric wire 1. Next, the equivalent circle diameter is calculated based on the "average cross-sectional area of ​​the electric wire 1", whereby the equivalent circle diameter of the cross section perpendicular to the longitudinal direction of the electric wire 1 can be determined.

[0032] It has been confirmed that, as long as the same electric wire 1 is measured by the above method, there is no variation in the measurement results even if the measurement points are changed arbitrarily.

[0033] Conductor The electric wire 1 includes a conductor 2. The material of the conductor 2 may be a metal material having high electrical conductivity and high mechanical strength. Examples of such metal materials include copper, copper alloys, aluminum, aluminum alloys, nickel, silver, soft iron, steel, and stainless steel. The conductor 2 may be a wire material formed into a linear shape from one type of metal material. The conductor 2 may also be a multi-layered structure in which a wire material is further coated with another metal by a technique such as plating. Examples of the conductor 2 having a multi-layered structure include a tin-plated copper wire, a nickel-plated copper wire, a silver-plated copper wire, a copper-plated aluminum wire, and a copper-plated steel wire.

[0034] The shape of the conductor 2 is not particularly limited, and any conventionally known shape can be used. Examples of the shape of the conductor 2 include a round wire having a circular cross section, a rectangular wire having a square cross section, and a twisted wire made by twisting together a plurality of wires.

[0035] The equivalent circle diameter of a cross section perpendicular to the longitudinal direction of the conductor 2 may be 0.05 mm or more and 30 mm or less, 0.1 mm or more and 15 mm or less, or 0.3 mm or more and 8 mm or less. Here, the longitudinal direction can be rephrased as the "first direction" described later.

[0036] The equivalent circle diameter of a cross section perpendicular to the longitudinal direction of the conductor 2 can be determined in a manner similar to that of the equivalent circle diameter of a cross section perpendicular to the longitudinal direction of the wire 1, except that the measurement object is the conductor 2.

[0037] It has been confirmed that, as long as the same conductor 2 is measured using the above method, there is no variation in the measurement results even if the measurement location is changed arbitrarily.

[0038] The average cross-sectional area of ​​the conductor 2 is not particularly limited and can be appropriately selected depending on the application. 2 More than 550mm 2 It may be less than 0.006 mm 2 More than 140mm 2 It may be less than 0.05 mm 2 More than 40mm 2 or less. In the present disclosure, the method for measuring the average cross-sectional area of ​​the conductor 2 is as follows. One conductor 2 is stretched in a straight line, cut along a plane connecting one end of the conductor 2 to the other end of the conductor 2 with a first direction as its normal line, and the cross section is exposed to measure the cross-sectional area. For one conductor 2, the conductor 2 is cut along a plane with the first direction as its normal line at any five points to measure the cross-sectional areas, and an average value is calculated. The average value corresponds to the average cross-sectional area of ​​the conductor 2.

[0039] ≪Coating≫ The electric wire 1 includes a coating 5 that covers the conductor 2. The coating 5 includes a first layer 3 and a second layer 4 formed on the first layer 3. The coating 5 may consist of only the first layer 3 and the second layer 4 formed on the first layer 3, or may further include a third layer formed between the first layer 3 and the second layer 4, or may further include other layers described below in addition to the first layer 3 and the second layer 4 formed on the first layer 3.

[0040] The thickness of the coating 5 may be 0.025 mm or more and 10 mm or less. If the thickness of the coating 5 is less than 0.025 mm, the coating 5 tends to be easily damaged. If the thickness of the coating 5 exceeds 10 mm, the electric wire 1 tends to be hard and difficult to bend, and the cost tends to be high. The thickness of the coating 5 may be 0.050 mm or more and 2.5 mm or less, or 0.150 mm or more and 1 mm or less.

[0041] In the present disclosure, the thickness of the coating 5 can be specified by the following method. The electric wire 1 is stretched in a straight line, and cut along a plane that connects one end of the electric wire 1 to the other end and has a first direction as its normal line, to expose a cross section. The thicknesses of the coating 5 are measured at three arbitrary points on the cross section, and their average value is calculated. The electric wire 1 is cut along a plane that has a first direction as its normal line at a total of five arbitrary points to obtain the average values, and the thickness of the coating 5 is specified by calculating the average value.

[0042] It has been confirmed that, as long as the same electric wire 1 is measured by the above method, there is no variation in the measurement results even if the measurement points are changed arbitrarily.

[0043] <1st layer> The first layer 3 contains a fluororesin as a main component. Here, "containing a fluororesin as a main component" means that the fluororesin is contained in an amount of, for example, 50% by mass or more. The first layer 3 may be made of a fluororesin. "The first layer 3 may be made of a fluororesin" means that the first layer 3 may be made of only a fluororesin, or may contain other components (such as a first inevitable impurity) in addition to the fluororesin within a range that does not impair the effects of the present disclosure. Examples of the first inevitable impurities include crosslinking aids (such as triallyl isocyanurate and trimethylpentene trimethacrylate), fillers (such as silica, talc, calcium carbonate, clay, and zinc oxide), lubricants (such as oleic acid amide, erucic acid amide, stearic acid, and zinc stearate), coloring pigments (such as inorganic pigments such as titanium oxide, organic pigments, and carbon), and flame retardants (such as bromine-based flame retardants, antimony trioxide, melamine cyanurate, magnesium hydroxide, and aluminum hydroxide).

[0044] The fluororesin of the first layer 3 may be at least one fluororesin selected from the group consisting of perfluoroalkoxyalkane resin, fluorinated ethylene propylene resin, ethylene tetrafluoroethylene copolymer resin, and crosslinked ethylene tetrafluoroethylene copolymer resin. This makes it possible to provide an electric wire 1 having better heat resistance and a multicore cable including the electric wire 1. In the present disclosure, the perfluoroalkoxyalkane resin can be rephrased as PFA resin, the fluorinated ethylene propylene resin can be rephrased as FEP resin, the ethylene tetrafluoroethylene copolymer resin can be rephrased as ETFE resin, and the crosslinked ethylene tetrafluoroethylene copolymer resin can be rephrased as crosslinked ETFE resin.

[0045] The fluororesin of the first layer 3 is a resin modified with a first functional group, and the first functional group may have a carboxyl group or an ether group. This makes it possible to provide an electric wire 1 having better heat resistance and a multi-core cable including the electric wire 1. Examples of the resin modified with the first functional group include a resin modified with a maleic anhydride group by PFA resin, a resin modified with a carboxyl group by PFA resin, a resin modified with an epoxy group by PEP resin, a resin modified with a maleic anhydride group by FEP resin, a resin modified with a carboxyl group by FEP resin, a resin modified with an epoxy group by FEP resin, a resin modified with a maleic anhydride group by ETFE resin, a resin modified with a carboxyl group by ETFE resin, a resin modified with an epoxy group by ETFE resin, a resin modified with a crosslinked ETFE resin by maleic anhydride group, a resin modified with a crosslinked ETFE resin by carboxyl group, and a resin modified with a crosslinked ETFE resin by epoxy group. The state of being "modified with a first functional group" means a state in which the first functional group is graft-bonded to an end or non-end of a polymer molecular chain, or a state in which the first functional group is copolymerized in a polymer molecular chain.

[0046] The first functional group may be at least one functional group selected from the group consisting of a carboxyl group, a maleic anhydride group, and an epoxy group, thereby making it possible to provide an electric wire 1 having superior heat resistance and a multi-core cable including the electric wire 1.

[0047] The fluororesin of the first layer 3 may be a resin that has been subjected to a hydrophilic surface treatment. This makes it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0048] The hydrophilic surface treatment may be at least one surface treatment selected from the group consisting of corona treatment, plasma treatment, ozone treatment, and etching treatment with active sodium. This makes it possible to provide an electric wire having superior heat resistance and a multi-core cable including the electric wire.

[0049] The composition of the first layer 3 can be identified by a combination of an analysis of the chemical bonding state based on the measurement of the infrared absorption spectrum by nuclear magnetic resonance (NMR) spectrum and Fourier transform infrared spectroscopy (FT-IR), and the measurement of the crystalline melting temperature and the heat of crystalline melting by a differential scanning calorimeter.

[0050] The weight average molecular weight of the fluororesin of the first layer 3 may be 10,000 or more and 5,000,000 or less, 50,000 or more and 2,000,000 or less, or 100,000 or more and 1,000,000 or less. The weight average molecular weight of the fluororesin in the first layer 3 can be determined by measurement using gel permeation chromatography (GPC) in accordance with JIS-K7252-1:2008 "Plastics - Determination of average molecular weight and molecular weight distribution of polymers by size exclusion chromatography - Part 1: General rules".

[0051] The thickness of the first layer 3 may be 0.025 mm or more and 10 mm or less. This can impart better heat resistance to the electric wire 1. In addition, the electric wire 1 can be made easier to bend. The lower limit of the thickness of the first layer 3 may be 0.025 mm or more, 0.050 mm or more, 0.100 mm or more, or 0.200 mm or more. The upper limit of the thickness of the first layer 3 may be 10 mm or less, 2.5 mm or less, 1 mm or less, or 0.500 mm or less. The thickness of the first layer 3 may be 0.050 mm or more and 2.5 mm or less, or 0.100 mm or more and 1 mm or less.

[0052] The thickness of the first layer 3 can be determined in a manner similar to that of the coating 5, except that the measurement target is the first layer 3.

[0053] It has been confirmed that, as long as the same electric wire 1 is measured by the above method, there is no variation in the measurement results even if the measurement points are changed arbitrarily.

[0054] <3rd layer> The coating 5 further includes a third layer (not shown) formed between the first layer 3 and the second layer 4, and the third layer may include a fluororesin as a main component. This can impart better heat resistance to the electric wire 1. Here, "including a fluororesin as a main component" means that the fluororesin is included in an amount of, for example, 50 mass% or more. The third layer may be made of a fluororesin. "The third layer may be made of a fluororesin" means that the third layer may be made of only a fluororesin, or may include other components (such as a third inevitable impurity) in addition to the fluororesin within a range that does not impair the effects of the present disclosure. Examples of the third unavoidable impurities include crosslinking aids (triallyl isocyanurate, trimethylpentene trimethacrylate, etc.), fillers (silica, talc, calcium carbonate, clay, zinc oxide, etc.), lubricants (oleic acid amide, erucic acid amide, stearic acid, zinc stearate, etc.), coloring pigments (inorganic pigments such as titanium oxide, organic pigments, carbon, etc.), flame retardants (bromine-based flame retardants, antimony trioxide, melamine cyanurate, magnesium hydroxide, aluminum hydroxide, etc.), and the like.

[0055] The fluororesin of the third layer may be at least one fluororesin selected from the group consisting of perfluoroalkoxyalkane resin, fluorinated ethylene propylene resin, ethylene tetrafluoroethylene copolymer resin, and crosslinked ethylene tetrafluoroethylene copolymer resin, thereby making it possible to provide an electric wire 1 having superior heat resistance and a multi-core cable including the electric wire 1.

[0056] The fluororesin of the third layer is a resin modified with a second functional group, and the second functional group may have a carboxyl group or an ether group. This makes it possible to provide an electric wire 1 having better heat resistance and a multi-core cable including the electric wire 1. Examples of the resin modified with a second functional group include a resin modified with a maleic anhydride group by PFA resin, a resin modified with a carboxyl group by PFA resin, a resin modified with an epoxy group by PEP resin, a resin modified with a maleic anhydride group by FEP resin, a resin modified with a carboxyl group by FEP resin, a resin modified with an epoxy group by FEP resin, a resin modified with a maleic anhydride group by ETFE resin, a resin modified with a carboxyl group by ETFE resin, a resin modified with an epoxy group by ETFE resin, a resin modified with a crosslinked ETFE resin by maleic anhydride group, a resin modified with a crosslinked ETFE resin by carboxyl group, and a resin modified with a crosslinked ETFE resin by epoxy group. The state of being "modified with a second functional group" means a state in which the second functional group is graft-bonded to an end or non-end of the polymer molecular chain, or a state in which the second functional group is copolymerized in the polymer molecular chain.

[0057] The second functional group may be at least one functional group selected from the group consisting of a carboxyl group, a maleic anhydride group, and an epoxy group. This makes it possible to provide the electric wire 1 having better heat resistance and the multi-core cable including the electric wire 1.

[0058] The composition of the third layer can be determined in a manner similar to the measurement method for the "composition of the first layer 3," except that the measurement target is the "third layer."

[0059] The weight average molecular weight of the fluororesin of the third layer may be 10,000 or more and 5,000,000 or less, 50,000 or more and 2,000,000 or less, or 100,000 or more and 1,000,000 or less. In the third layer, the weight average molecular weight of the fluororesin can be determined by measurement using gel permeation chromatography (GPC) in accordance with JIS-K7252-1:2008 "Plastics - Determination of average molecular weight and molecular weight distribution of polymers by size exclusion chromatography - Part 1: General rules".

[0060] The thickness of the third layer may be 0.025 mm or more and 10 mm or less. This can impart better heat resistance to the electric wire 1. In addition, the electric wire 1 can be made easier to bend. The lower limit of the thickness of the third layer may be 0.025 mm or more, 0.050 mm or more, 0.100 mm or more, or 0.200 mm or more. The upper limit of the thickness of the third layer may be 10 mm or less, 2.5 mm or less, 1 mm or less, or 0.500 mm or less. The thickness of the third layer may be 0.050 mm or more and 2.5 mm or less, or 0.100 mm or more and 1 mm or less.

[0061] The thickness of the third layer can be determined in a manner similar to that of the coating 5, except that the measurement target is the third layer.

[0062] It has been confirmed that, as long as the same electric wire 1 is measured by the above method, there is no variation in the measurement results even if the measurement points are changed arbitrarily.

[0063] <2nd layer> The second layer 4 contains silsesquioxane as a main component. Here, "containing silsesquioxane as a main component" means that silsesquioxane is contained in an amount of, for example, 50 mass % or more. Silsesquioxane is a (RSiO 3 / 2) as a structural unit, and the R is a polymerizable group. These can impart excellent heat resistance to the electric wire 1. The second layer 4 may be made of silsesquioxane. "The second layer 4 may be made of silsesquioxane" means that the second layer 4 may be made of only silsesquioxane, or may contain other components (such as a second inevitable impurity) in addition to silsesquioxane as long as the effects of the present disclosure are not impaired. Examples of the second inevitable impurities include a photoradical polymerization initiator, a thermal polymerization initiator, an acrylic monomer, an organic solvent, a lubricant, and a pigment.

[0064] Silsesquioxane may contain at least one structure selected from the group consisting of a random structure, a ladder structure, a complete cage structure, and an incomplete cage structure. Here, the term "random structure" refers to the structure represented by formula 1, the term "ladder structure" refers to the structure represented by formula 2, the term "complete cage structure" refers to the structure represented by formula 3 or the structure represented by formula 4, and the term "incomplete cage structure" refers to the structure represented by formula 5 or the structure represented by formula 6. The structure represented by formula 3 can be rephrased as "T8", and the structure represented by formula 4 can be rephrased as "T 10 " This can be rephrased as "

[0065] [ka]

[0066] [ka]

[0067] [ka]

[0068] The polymerizable group may be a radically polymerizable group or a cationic polymerizable group. These polymerizable groups have excellent polymerization reactivity, particularly photopolymerization reactivity, and therefore can provide the electric wire 1 and the multi-core cable including the electric wire 1 having excellent heat resistance.

[0069] The polymerizable group may be one selected from the group consisting of an acryloyl group, a methacryloyl group, and an oxetanyl group. These polymerizable groups have excellent polymerization reactivity, particularly photopolymerization reactivity, and therefore can provide an electric wire 1 and a multi-core cable including the electric wire 1 having excellent heat resistance.

[0070] The composition of the second layer 4 can be identified by a combination of an analysis of the chemical bonding state based on the measurement of the infrared absorption spectrum by nuclear magnetic resonance (NMR) spectrum and Fourier transform infrared spectroscopy (FT-IR), and the measurement of the ash content by thermogravimetry (TG).

[0071] The thickness of the second layer 4 is 0.1 μm or more and 100 μm or less. This allows the second layer 4 to fully exhibit its heat resistance effect, and therefore it is possible to provide the electric wire 1 having excellent heat resistance and a multi-core cable including the electric wire 1. The lower limit of the thickness of the second layer 4 may be 0.1 μm or more, 0.5 μm or more, 1 μm or more, or 2 μm or more. The upper limit of the thickness of the second layer 4 may be 100 μm or less, 50 μm or less, 20 μm or less, or 10 μm or less. The thickness of the second layer 4 may be 0.5 μm or more and 50 μm or less, or 1 μm or more and 20 μm or less.

[0072] The thickness of the second layer 4 can be determined in a manner similar to that of the coating 5, except that the measurement target is the second layer 4.

[0073] It has been confirmed that, so long as the same second layer 4 is measured by the above method, there is no variation in the measurement results even if the measurement location is changed arbitrarily.

[0074] <Other layers> The coating 5 may further include other layers. Such other layers include a surface layer, an intermediate layer, and the like. The surface layer is a layer located on the surface of the coating 5. The intermediate layer is a layer located between the conductor 2 and the first layer 3 or between the first layer 3 and the second layer 4.

[0075] <Electric wire manufacturing method> In the case where the coating 5 does not include a third layer formed between the first layer 3 and the second layer 4, the method for producing the electric wire 1 of this embodiment includes, for example, a first step of preparing the conductor 2, a compound for forming the first layer 3, and a varnish for forming the second layer 4, a second step of forming the first layer 3 on the outer peripheral surface of the conductor 2, and a third step of forming the second layer 4 on the surface of the first layer 3, in this order. In the case where the coating 5 further includes a third layer formed between the first layer 3 and the second layer 4, the method for producing the electric wire 1 of this embodiment further includes, for example, a step 2A between the second step and the third step. The first step includes a step 1A of preparing the conductor 2, a step 1B of preparing the compound for forming the first layer 3, and a step 1C of preparing the varnish for forming the second layer 4. In the case where the coating 5 further includes a third layer formed between the first layer 3 and the second layer 4, the first step further includes a 1D step of preparing a varnish for forming the third layer. The method for producing the electric wire 1 of the present embodiment may further include a "step of forming other layers". The "step of forming other layers" may be performed by a conventionally known method.

[0076] <1st process> <Step 1A: Step of preparing the conductor> In step 1A, the conductor 2 is prepared. The conductor 2 may be prepared by manufacturing using a conventionally known method, or may be prepared by purchasing a commercially available product.

[0077] <Step 1B: Step of preparing compound for forming first layer> In step 1B, a compound for forming the first layer 3 is prepared. For example, the compound for forming the first layer 3 can be prepared by the following method. First, a fluororesin is prepared as a raw material. In addition to the fluororesin, for example, a crosslinking aid, a lubricant, a filler, etc. may be prepared as raw materials. Next, the raw materials are kneaded to prepare the compound for forming the first layer 3.

[0078] Examples of fluororesins include perfluoroalkoxyalkane resins, fluorinated ethylene propylene resins, ethylene tetrafluoroethylene copolymer resins, crosslinked ethylene tetrafluoroethylene copolymer resins, and resins obtained by modifying these resins with maleic anhydride groups, carboxyl groups, or epoxy groups.

[0079] The weight average molecular weight of the fluororesin may be 10,000 or more and 5,000,000 or less, 50,000 or more and 2,000,000 or less, or 100,000 or more and 1,000,000 or less.

[0080] The kneading can be carried out, for example, by using rolls heated to 280° C. or more and 350° C. or less. The kneading time can be 5 minutes or more and 30 minutes or less.

[0081] <Step 1C: Step of preparing varnish for forming second layer> In step 1C, a varnish for forming the second layer 4 is prepared. For example, the varnish for forming the second layer 4 can be prepared by the following method. First, a silsesquioxane derivative is prepared as a raw material. The silsesquioxane derivative may be prepared by manufacturing it by a conventionally known method, or may be prepared by purchasing a commercially available product. In addition to the silsesquioxane derivative, for example, a photoradical polymerization initiator, an acrylic monomer, a solvent, etc. may be prepared as raw materials. Next, a photoradical polymerization initiator, etc. is added to the silsesquioxane derivative and stirred, so that a varnish for forming the second layer 4 can be prepared.

[0082] The stirring speed may be, for example, 10 rpm or more and 1000 rpm or less. The temperature during stirring may be 10° C. or more and 40° C. or less. The temperature during stirring may be room temperature. The stirring time may be 5 minutes or more and 30 minutes or less.

[0083] <1D process: process of preparing varnish for forming the third layer> In step 1D, a compound for forming the third layer is prepared. Step 1D is performed in the same manner as step 1B, except that the "compound for forming the first layer" is replaced with the "compound for forming the third layer."

[0084] <Second process> In the second step, the first layer 3 is formed on the outer peripheral surface of the conductor 2. For example, the first layer 3 can be formed by the following method. First, the compound for forming the first layer 3 is pressed into an extruder with the head set to 300°C to 350°C and the cylinder set to 280°C to 320°C. Next, the compound for forming the first layer 3 is extrusion coated onto the outer peripheral surface of the conductor 2. When the fluororesin of the first layer is a crosslinked ETFE resin, the extrusion-coated compound for forming the first layer 3 may be irradiated with an electron beam of 0.1 kGy to 500 kGy. In this manner, the first layer 3 can be formed on the outer peripheral surface of the conductor 2.

[0085] In step 2A, a third layer is formed on the surface of the first layer 3. For example, the third layer can be formed by the following method. First, the compound for forming the third layer is pressed into an extruder with the head set to 300°C to 350°C and the cylinder set to 280°C to 320°C. Next, the compound for forming the third layer is extrusion coated onto the surface of the first layer 3. When the fluororesin of the third layer is a crosslinked ETFE resin, the extrusion-coated compound for forming the third layer may be irradiated with an electron beam of 0.1 kGy to 500 kGy. In this manner, the third layer can be formed on the surface of the first layer 3.

[0086] <3rd process> In the case where the manufacturing method of the electric wire 1 of the present embodiment does not include step 2A between step 2 and step 3, in step 3, the second layer 4 is formed on the surface of the first layer 3. For example, the second layer 4 can be formed by the following method. First, a varnish for forming the second layer 4 is applied onto the surface of the first layer 3. Next, the varnish for forming the second layer 4 applied onto the surface of the first layer 3 is subjected to a photocuring treatment under the following conditions, thereby forming the second layer 4 on the surface of the first layer 3. Note that step 3 may be repeatedly performed until the thickness of the second layer 4 reaches a predetermined thickness. (Light curing treatment conditions) Light source: High pressure mercury lamp (input power: 10W / cm or more, 300W / cm or less) Lamp height: 1cm to 50cm Conveyor speed: 1m / min to 10m / min Accumulated light intensity per pass: 1,000mJ / cm 2 More than 30,000mJ / cm 2 below Number of passes: 1 to 10 Atmosphere: Air

[0087] In the case where the manufacturing method of the electric wire 1 of the present embodiment further includes a step 2A between the step 2 and the step 3, the second layer 4 is formed on the surface of the third layer in the step 3. For example, the second layer 4 can be formed by the following method. First, a varnish for forming the second layer 4 is applied on the surface of the third layer. Next, the varnish for forming the second layer 4 applied on the surface of the third layer is subjected to a photocuring treatment under the following conditions, thereby forming the second layer 4 on the surface of the third layer. The third step may be repeatedly performed until the thickness of the second layer 4 reaches a predetermined thickness. (Light curing treatment conditions) Light source: High pressure mercury lamp (input power: 10W / cm or more, 300W / cm or less) Lamp height: 1cm to 50cm Conveyor speed: 1m / min to 10m / min Accumulated light intensity per pass: 1,000mJ / cm 2 More than 30,000mJ / cm 2 below Number of passes: 1 to 10 Atmosphere: Air

[0088] [Embodiment 2: Multi-core cable] The multi-core cable of this embodiment includes the electric wire according to the first embodiment.

[0089] According to the present disclosure, it is possible to provide a multi-core cable including electric wires having excellent heat resistance.

[0090] The multi-core cable according to the present embodiment is not particularly limited as long as it includes the electric wire described in embodiment 1. In the present disclosure, the multi-core cable means a cable including a plurality of electric wires. "The multi-core cable according to the present embodiment includes the electric wire described in embodiment 1" means that at least one of the plurality of electric wires included in the multi-core cable described in the present embodiment is the electric wire described in embodiment 1.

[0091] <Manufacturing method of multi-core cable> The method for producing the multi-core cable according to this embodiment can be carried out in the same manner as the conventionally known method, except that the electric wire according to the first embodiment is used. EXAMPLES

[0092] The present embodiment will be described more specifically with reference to examples, although the present embodiment is not limited to these examples.

[0093] <Making Electric Wires> Electric wires according to Samples 1 to 19 and 101 to 112 were produced as follows.

[0094] <1st process> The conductors shown in Tables 11 and 12 were prepared by purchasing commercially available products (step 1A). In addition, the raw materials shown in Tables 1 and 2 were kneaded with rolls heated to the temperatures shown in Tables 1 and 2 in the compositions shown in Tables 1 and 2 for the times shown in Tables 1 and 2 to prepare a compound for forming the first layer (step 1B). As the fluororesin, the resins shown in the "Composition" column of the "First Layer" column of Tables 11 and 12 were used, except when the "Composition" column of the "First Layer" column of Tables 11 and 12 states "crosslinked ETFE resin, crosslinked ETFE resin (modified with maleic anhydride group), crosslinked ETFE resin (modified with carboxyl group), or crosslinked ETFE resin (modified with epoxy group)". As the PFA resin, "P-63P" (trademark) made by AGC was used, as the FEP resin, "9494" (trademark) made by Chemours was used, and as the ETFE resin, "C-55AXP" (trademark) made by AGC was used. In the "Composition" column of the "First Layer" column in Tables 11 and 12, when "Crosslinked ETFE resin", "Crosslinked ETFE resin (modified with maleic anhydride group)", "Crosslinked ETFE resin (modified with carboxyl group)", or "Crosslinked ETFE resin (modified with epoxy group)" is stated, "C-55AXP" (trademark) manufactured by AGC was used as the fluororesin. "EBECRYL" (trademark) manufactured by Allnex was used as the crosslinking assistant. Maleic anhydride manufactured by Tokyo Chemical Industry Co., Ltd. was used as the "unsaturated monomer having a maleic anhydride group". Acrylic acid manufactured by Tokyo Chemical Industry Co., Ltd. was used as the "unsaturated monomer having a carboxyl group". Allyl glycidyl ether manufactured by Tokyo Chemical Industry Co., Ltd. was used as the "unsaturated monomer having an epoxy group".

[0095] In addition, the raw materials shown in Tables 3 and 4 (in other words, raw materials other than the silsesquioxane derivative) were added to the silsesquioxane derivative so as to obtain the composition shown in Tables 3 and 4, and the mixture was stirred under the conditions shown in Tables 3 and 4 to prepare a varnish for forming a second layer (step 1C). Note that when "-" is written in all columns of the "step 1C" column, it means that the "step 1C" was not performed. Note that the silsesquioxane derivatives shown in Tables 15 and 16 were used as the "silsesquioxane derivatives". As the silsesquioxane derivative in which R (polymerizable group) is an acryloyl group (radical polymerizable group), "AC-SQ TA-100" (trademark) manufactured by Toagosei Co., Ltd. was used, as the silsesquioxane derivative in which R (polymerizable group) is a methacryloyl group (radical polymerizable group), "MAC-SQ TM-100" (trademark) manufactured by Toagosei Co., Ltd. was used, and as the silsesquioxane derivative in which R (polymerizable group) is an oxetanyl group (cationic polymerizable group), "QX-SQ SI-20" (trademark) manufactured by Toagosei Co., Ltd. was used. As the photoradical polymerization initiator, "BLUESIL PI 2074" (trademark) manufactured by ELKEM was used.

[0096] In addition, the raw materials shown in Tables 5 and 6 were kneaded for the time shown in Tables 5 and 6 using rolls heated to the temperatures shown in Tables 5 and 6 in the compositions shown in Tables 5 and 6 to prepare a compound for forming the third layer (step 1D). As the fluororesin, the resins shown in the "Composition" column of the "Third Layer" column of Tables 13 and 14 were used, except when the "Composition" column of the "Third Layer" column of Tables 13 and 14 states "crosslinked ETFE resin, crosslinked ETFE resin (modified with maleic anhydride group), crosslinked ETFE resin (modified with carboxyl group), or crosslinked ETFE resin (modified with epoxy group)". When the "Composition" column of the "Third Layer" column of Tables 13 and 14 states "crosslinked ETFE resin, crosslinked ETFE resin (modified with maleic anhydride group), crosslinked ETFE resin (modified with carboxyl group), or crosslinked ETFE resin (modified with epoxy group)", "C-55AXP" (trademark) manufactured by AGC was used as the fluororesin. Furthermore, if "-" is written in all the fields of the "1st D step" column, it means that the "1st D step" was not performed.

[0097] <Second process> First, the compound for forming the first layer was pressed into an extruder whose head was set to the temperature shown in Tables 7 and 8, and whose cylinder was set to the temperature shown in Tables 7 and 8. Next, the compound for forming the first layer was extrusion-coated on the outer periphery of the conductor so that the thickness of the first layer was as shown in Tables 11 and 12. Next, except for the cases where "0" is written in the "Electron beam [kGy]" column in the "Second step" column, the extrusion-coated compound for forming the first layer was irradiated with an electron beam at a dose shown in Tables 7 and 8. In this way, the first layer was formed on the outer periphery of the conductor.

[0098] <2nd A process> First, the compound for forming the third layer was pressed into an extruder whose head was set to the temperature shown in Tables 7 and 8, and whose cylinder was set to the temperature shown in Tables 7 and 8. Next, the compound for forming the third layer was extrusion-coated on the outer circumference of the conductor so that the thickness of the third layer was as shown in Tables 13 and 14. Next, the extrusion-coated compound for forming the third layer was irradiated with electron beams at the doses shown in Tables 7 and 8, except when "-" or "0" is written in the "Electron beam [kGy]" column in the "2A process" column. In this way, the third layer was formed on the surface of the first layer. Note that when "-" is written in all columns of the "2A process", it means that the "2A process" was not performed.

[0099] <3rd process> First, in the case where the 2A step was not performed, the varnish for forming the second layer was applied on the surface of the first layer, and in the case where the 2A step was performed, the varnish for forming the second layer was applied on the surface of the third layer. Next, in the case where the 2A step was not performed, the varnish for forming the second layer applied on the surface of the first layer was subjected to a light curing treatment under the following conditions to form a second layer on the surface of the first layer. In the case where the 2A step was performed, the varnish for forming the second layer applied on the surface of the third layer was subjected to a light curing treatment under the following conditions to form a second layer on the surface of the third layer. The application of the varnish for forming the second layer and the light curing treatment were repeatedly performed until the thickness of the second layer became as shown in Table 2. Note that when "-" is written in all columns of the "third step", it means that the "third step" was not performed. (Light curing treatment conditions) Light source: High pressure mercury lamp (input power [W / cm] is as shown in Tables 9 and 10) Ramp Height: As per Tables 9 and 10 Conveyor speed: As per Table 9 and Table 10 Accumulated light amount per pass: As shown in Tables 9 and 10 Number of passes: As shown in Tables 9 and 10 Atmosphere: Air

[0100] In this manner, electric wires according to Samples 1 to 19 and 101 to 112 were produced.

[0101] [Table 1]

[0102] [Table 2]

[0103] [Table 3]

[0104] [Table 4]

[0105] [Table 5]

[0106] [Table 6]

[0107] [Table 7]

[0108] [Table 8]

[0109] [Table 9]

[0110] [Table 10]

[0111] [Table 11]

[0112] [Table 12]

[0113] [Table 13]

[0114] [Table 14]

[0115] [Table 15]

[0116] [Table 16]

[0117] [Table 17]

[0118] [Table 18]

[0119] <Evaluation of electrical wire characteristics> <Composition of the first layer> The composition of the first layer of each sample electric wire was determined by the method described in embodiment 1. The results obtained are shown in the "Composition" column of the "First Layer" column in Tables 11 and 12. When a component name is listed in the "Composition" column of the "First Layer" column in Tables 11 and 12, it means that the first layer contains the component listed in the "Composition" column of the "First Layer" column in Tables 11 and 12 as a main component. For example, when "PFA resin" is listed in the "Composition" column of the "First Layer" column in Tables 11 and 12, it means that the first layer contains a fluororesin as a main component, and the fluororesin is a perfluoroalkoxyalkane resin.

[0120] <Composition of the second layer> The composition of the second layer of each sample electric wire was determined by the method described in embodiment 1. The obtained results are shown in the "Composition" column of the "Second Layer" column in Tables 15 and 16. When a component name is listed in the "Composition" column of the "Second Layer" column in Tables 15 and 16, it means that the second layer contains the component listed in the "Composition" column of the "Second Layer" column in Tables 15 and 16 as a main component. For example, when "Silsesquioxane" is listed in the "Composition" column of the "Second Layer" column in Tables 15 and 16, and "Acryloyl group (radical polymerizable group)" is listed in the "R" column of the "Second Layer" column in Tables 15 and 16, the second layer contains silsesquioxane as a main component, and the silsesquioxane is (RSiO 3 / 2 ) as a constituent unit, and R is a polymerizable group, which is a radically polymerizable group and an acryloyl group.

[0121] <Composition of the third layer> The composition of the third layer of each sample electric wire was determined by the method described in embodiment 1. The results obtained are shown in the "Composition" column of the "Third Layer" column in Tables 13 and 14. When the component name is listed in the "Composition" column of the "Third Layer" column in Tables 13 and 14, it means that the third layer contains the component listed in the "Composition" column of the "Third Layer" column in Tables 13 and 14 as a main component. For example, when "PFA resin" is listed in the "Composition" column of the "Third Layer" column in Tables 13 and 14, it means that the third layer contains a fluororesin as a main component, and the fluororesin is a perfluoroalkoxyalkane resin.

[0122] <Coating thickness> The thickness of the coating of each sample electric wire was determined by the method described in embodiment 1. The results are shown in the "Thickness [μm]" column of the "Coating" column in Tables 15 and 16.

[0123] <Circular diameter of the cross section perpendicular to the longitudinal direction of the wire> For each sample electric wire, the equivalent circle diameter of a cross section perpendicular to the longitudinal direction of the electric wire was determined by the method described in embodiment 1. The results obtained are shown in the "equivalent circle diameter [mm]" column of the "electric wire" column in Tables 15 and 16.

[0124] <Evaluation Test 1> First, eight electric wires (length: 350 mm) for each sample were prepared. Next, the coating was peeled off from both ends of the electric wire in the area between the end and a position 25 mm away from the end in the longitudinal direction of the electric wire. Next, each of the eight electric wires (length: 350 mm) for each sample was left in a thermostatic chamber at temperatures of 85±2°C, 100±2°C, 125±3°C, 150±3°C, 175±3°C, 200±3°C, 225±4°C, and 250±4°C for 3000 hours. Next, the electric wire was taken out of the thermostatic chamber and left at room temperature for 16 hours. Next, a weight 13 of 5 kg was placed on a mandrel 11 having a diameter 1.5 times the equivalent circle diameter of a cross section perpendicular to the longitudinal direction of the electric wire 12, and a winding speed of 1 s was set. -1The wire was wound twice at two locations at room temperature (FIG. 3). Next, after visually checking that the conductor was not exposed in each sample electric wire, the electric wire was immersed in salt water (3% by mass) for 10 minutes. Next, a voltage of 1 kV was applied to the electric wire for 1 minute. Next, the electric wire was visually observed to determine whether the coating was broken or not. Next, the heat resistance of the electric wire was evaluated based on the following evaluation criteria. The obtained results are shown in the "Evaluation Test 1" column of Tables 17 and 18. The closer the evaluation result is to H, the better the heat resistance of the electric wire is. Note that, considering that the heat resistance of the electric wire differs depending on the type of fluororesin in the first layer (in other words, depending on the composition of the first layer), a relative comparison was made between samples having the same resin listed in the "Composition" column of the "First Layer" column in Tables 11 and 12. (Evaluation Criteria) A: When the temperature of the thermostatic chamber is 85±2℃ or less, the coating is not damaged. B: When the temperature of the thermostatic chamber is 100±2℃ or less, the coating is not damaged. C: When the temperature of the thermostatic chamber is 125±3℃ or less, no damage to the coating occurs. D: When the temperature of the thermostatic chamber is 150±3℃ or less, no damage to the coating occurs. E: When the temperature of the thermostatic chamber is 175±3℃ or less, no damage to the coating occurs. F: When the temperature of the thermostatic chamber is 200±3℃ or less, no damage to the coating occurs. G: No damage to the coating when the temperature of the thermostatic chamber is 225±4℃ or less H: No damage to the coating when the temperature of the thermostatic chamber is 250±4℃ or less

[0125] <Evaluation test 2> First, eight electric wires (length: 350 mm) for each sample were prepared. Next, the coating of the area between the end and a position 25 mm away from the end in the longitudinal direction of the electric wire was peeled off from both ends of the electric wire. Next, each of the eight electric wires (length: 350 mm) for each sample was left in a thermostatic bath at temperatures of 110±2°C, 125±3°C, 150±3°C, 175±3°C, 200±3°C, 225±4°C, 250±4°C, and 275±4°C for 240 hours. Next, the electric wire was taken out of the thermostatic bath and left at room temperature for 16 hours. Next, a weight 13 of 5 kg was placed on a mandrel 11 having a diameter 5 times the equivalent circle diameter of a cross section perpendicular to the longitudinal direction of the electric wire 12, and a winding speed of 1 s was set. -1 The wire was wound twice at two locations at room temperature (FIG. 3). Next, after visually checking that the conductor was not exposed in each sample electric wire, the electric wire was immersed in salt water (3 mass%) for 10 minutes. Next, a voltage of 1 kV was applied to the electric wire for 1 minute. Next, the electric wire was visually observed to determine whether the coating was broken or not. Next, the heat resistance of the electric wire was evaluated based on the following evaluation criteria. The obtained results are shown in the "Evaluation Test 2" column of Tables 17 and 18. The closer the evaluation result is to H', the better the heat resistance of the electric wire is. Note that, considering that the heat resistance of the electric wire differs depending on the type of fluororesin in the first layer (in other words, depending on the composition of the first layer), a relative comparison was made between samples having the same resin listed in the "Composition" column of the "First Layer" column in Tables 11 and 12. (Evaluation Criteria) A': When the temperature of the thermostatic chamber is 110±2℃ or less, no damage to the coating occurs. B': When the temperature of the thermostatic chamber is 125±3℃ or less, no damage to the coating occurs. C': When the temperature of the thermostatic chamber is 150±3℃ or less, no damage to the coating occurs. D': No damage to the coating when the temperature of the thermostatic chamber is 175±3℃ or less E': No damage to the coating when the temperature of the thermostatic chamber is 200±3℃ or less F': No damage to the coating when the temperature of the thermostatic chamber is 225±4℃ or less G': No damage to the coating when the temperature of the thermostatic chamber is 250±4℃ or less H': No damage to the coating when the temperature of the thermostatic chamber is 275±4℃ or less

[0126] <Evaluation test 3> First, eight electric wires (length: 350 mm) for each sample were prepared. Next, the coating was peeled off from both ends of the electric wire in the area between the end and a position 25 mm away from the end in the longitudinal direction of the electric wire. Next, each of the eight electric wires (length: 350 mm) for each sample was left in a thermostatic bath at a temperature of 135±3°C, 150±3°C, 175±3°C, 200±3°C, 225±4°C, 250±4°C, 275±4°C, and 300±4°C for six hours. Next, the electric wire was taken out of the thermostatic bath and left at room temperature for 16 hours. Next, a weight 13 of 5 kg was placed on a mandrel 11 having a diameter 1.5 times the equivalent circle diameter of a cross section perpendicular to the longitudinal direction of the electric wire 12, and a winding speed of 1 s was set. -1 The wire was wound twice at two locations at room temperature (FIG. 3). Next, after visually checking that the conductor was not exposed in each sample electric wire, the electric wire was immersed in salt water (3 mass%) for 10 minutes. Next, a voltage of 1 kV was applied to the electric wire for 1 minute. Next, the electric wire was visually observed to determine whether the coating was broken or not. Next, the heat resistance of the electric wire was evaluated based on the following evaluation criteria. The obtained results are shown in the "Evaluation Test 3" column of Tables 17 and 18. The closer the evaluation result is to H'', the better the heat resistance of the electric wire is. Note that, considering that the heat resistance of the electric wire differs depending on the type of fluororesin in the first layer (in other words, depending on the composition of the first layer), a relative comparison was made between samples having the same resin listed in the "Composition" column of the "First Layer" column in Tables 11 and 12. (Evaluation Criteria) A: When the temperature of the thermostatic chamber is 135±3℃ or less, no damage to the coating occurs. B): When the temperature of the thermostatic chamber is 150±3℃ or less, no damage to the coating occurs. C): When the temperature of the thermostatic chamber is 175±3℃ or less, no damage to the coating occurs. D): When the temperature of the thermostatic chamber is 200±3℃ or less, no damage to the coating occurs. E): When the temperature of the thermostatic chamber is 225±4℃ or less, no damage to the coating occurs. F): When the temperature of the thermostatic chamber is 250±4℃ or less, no damage to the coating occurs. G): When the temperature of the thermostatic chamber is 275±4℃ or less, no damage to the coating occurs. H): When the temperature of the thermostatic chamber is 300±4℃ or less, no damage to the coating occurs.

[0127] The electric wires according to Samples 1 to 19 correspond to Examples. The electric wires according to Samples 101 to 112 correspond to Comparative Examples. From the results in Tables 17 and 18, it was found that the electric wires according to Samples 1 to 19 have superior heat resistance compared to the electric wires according to Samples 101 to 112.

[0128] From the above, it was found that the electric wires according to Samples 1 to 19 had excellent heat resistance.

[0129] Although the embodiments and examples of the present disclosure have been described above, it is intended from the outset that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways.

[0130] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the embodiments and examples described above, and is intended to include the meaning equivalent to the claims and all modifications within the scope. [Explanation of symbols]

[0131] 1 wire, 2 conductor, 3 first layer, 4 second layer, 5 coating, 11 mandrel, 12 wire, 13 weight

Claims

1. An electric wire comprising a conductor and a coating that covers the conductor, the coating includes a first layer and a second layer formed on the first layer; the first layer contains a fluororesin as a main component, the second layer contains silsesquioxane as a main component, The silsesquioxane is (RSiO ３／２ ) is a polymer having structural units, R is a polymerizable group, The electric wire, wherein the second layer has a thickness of 0.1 μm or more and 100 μm or less.

2. 2. The electric wire according to claim 1, wherein the fluororesin of the first layer is at least one fluororesin selected from the group consisting of perfluoroalkoxyalkane resin, fluorinated ethylene propylene resin, ethylene tetrafluoroethylene copolymer resin, and crosslinked ethylene tetrafluoroethylene copolymer resin.

3. the fluororesin of the first layer is a resin modified with a first functional group, The electric wire according to claim 1 , wherein the first functional group has a carboxyl group or an ether group.

4. The electric wire according to claim 3 , wherein the first functional group is at least one functional group selected from the group consisting of a carboxyl group, a maleic anhydride group, and an epoxy group.

5. The electric wire according to claim 1 , wherein the fluororesin of the first layer is a resin that has been subjected to a hydrophilic surface treatment.

6. 6. The electric wire according to claim 5, wherein the hydrophilic surface treatment is at least one surface treatment selected from the group consisting of a corona treatment, a plasma treatment, an ozone treatment, and an etching treatment with active sodium.

7. the coating further includes a third layer formed between the first layer and the second layer, The electric wire according to claim 1 , wherein the third layer contains a fluororesin as a main component.

8. 8. The electric wire according to claim 7, wherein the fluororesin of the third layer is at least one fluororesin selected from the group consisting of perfluoroalkoxyalkane resin, fluorinated ethylene propylene resin, ethylene tetrafluoroethylene copolymer resin, and crosslinked ethylene tetrafluoroethylene copolymer resin.

9. the fluororesin of the third layer is a resin modified with a second functional group, The electric wire according to claim 7 , wherein the second functional group has a carboxyl group or an ether group.

10. The electric wire according to claim 9 , wherein the second functional group is at least one functional group selected from the group consisting of a carboxyl group, a maleic anhydride group, and an epoxy group.

11. The electric wire according to claim 1 , wherein the polymerizable group is a radically polymerizable group or a cationically polymerizable group.

12. The electric wire according to claim 1 , wherein the polymerizable group is one type of polymerizable group selected from the group consisting of an acryloyl group, a methacryloyl group, and an oxetanyl group.

13. A multi-core cable comprising the electric wire according to any one of claims 1 to 6.

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