Insulated electric wire and heat-shrinkable tube

Abstract

An insulated wire includes a conductor and an insulating layer covering the conductor. The insulating layer is formed of a composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide. The first component is composed of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer. The second component is composed of at least one selected from the group consisting of magnesium oxide, calcium carbonate, and hydrotalcite. In the composition, the mass ratio M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer is M2 / M1, which is 10 / 90 or more and 40 / 60 or less. In the composition, the content of the brominated flame retardant is 1.0 part by mass or more and 40 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the content of the zinc oxide is 1.0 part by mass or more and 25 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the total content of the second component is 5.0 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the first component.

Description

Technical Field

[0001] This disclosure relates to insulated wires and heat shrink tubing. Background Technology

[0002] One of the required properties of the insulation layer of a coated conductor is flame retardancy. Patent Document 1 discloses a coated wire in which antimony trioxide is added to a blend polymer composed of tetrafluoroethylene-propylene copolymer and ethylene-tetrafluoroethylene copolymer, thereby obtaining a composition with improved flame retardancy, which is used as an insulation layer.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2010-186585 Summary of the Invention

[0004] The insulated wire disclosed herein comprises a conductor and an insulating layer covering the conductor. The insulating layer is formed of a composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide. The first component is composed of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer. The second component is composed of at least one selected from the group consisting of magnesium oxide, calcium carbonate, and hydrotalcite. In the composition, the mass ratio M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer, M2 / M1, is 10 / 90 or more and 40 / 60 or less. In the composition, the content of the brominated flame retardant is 1.0 part by mass or more and 40 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the content of the zinc oxide is 1.0 part by mass or more and 25 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the total content of the second component is 5.0 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the first component. Attached Figure Description

[0005] Figure 1 This is a schematic perspective view of an insulated wire representing one embodiment of the present disclosure.

[0006] Figure 2 This is a schematic perspective view of a heat shrink tube according to one embodiment of the present disclosure. Detailed Implementation

[0007] [The problem this disclosure aims to solve] In addition to flame retardancy, the insulation layer of insulated wires must also suppress smoke generation during combustion. Furthermore, the insulation layer of insulated wires is required to have excellent flexibility and excellent tensile elongation.

[0008] Therefore, the purpose of this disclosure is to provide an insulated wire with an insulation layer that has excellent flame retardancy, suppresses smoke during combustion, has excellent flexibility and excellent tensile elongation.

[0009] Therefore, the purpose of this disclosure is to provide a heat shrink tube with excellent flame retardancy, suppression of smoke during combustion, excellent flexibility, and excellent tensile elongation.

[0010] [Effects of this disclosure] According to this disclosure, an insulated wire with an insulation layer that has excellent flame retardancy, suppresses smoke during combustion, has excellent flexibility, and excellent tensile elongation can be provided.

[0011] Furthermore, according to this disclosure, a heat shrink tube with excellent flame retardancy, suppression of smoke during combustion, excellent flexibility, and excellent tensile elongation can be provided.

[0012] [Description of embodiments of this disclosure] First, the implementation plan disclosed herein is listed for explanation.

[0013] (1) The insulated wire of the present disclosure comprises a conductor and an insulating layer covering the conductor, the insulating layer being formed of a composition comprising a first component, a second component, a brominated flame retardant and zinc oxide, the first component being composed of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer, the second component being composed of at least one selected from the group consisting of magnesium oxide, calcium carbonate and hydrotalcite, wherein in the composition, the mass ratio M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer is M2 / M1 being 10 / 90 or more and 40 / 60 or less, in the composition, the content of the brominated flame retardant is 1.0 part by mass or more and 40 parts by mass or less relative to 100 parts by mass of the first component, in the composition, the content of the zinc oxide is 1.0 part by mass or more and 25 parts by mass or less relative to 100 parts by mass of the first component, and in the composition, the total content of the second component is 5.0 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the first component.

[0014] According to this disclosure, an insulated wire with an insulation layer that has excellent flame retardancy, suppresses smoke during combustion, has excellent flexibility, and excellent tensile elongation can be provided.

[0015] (2) In (1) above, the average particle size of the second component may be 0.05 μm or more and 5 μm or less. In this way, an insulating layer with a good appearance can be obtained.

[0016] (3) In (1) or (2) above, the average particle size of the zinc oxide may be 0.05 μm or more and 5 μm or less. In this way, an insulating layer with a good appearance can be obtained.

[0017] (4) In any of (1) to (3) above, the energy storage modulus of the insulating layer at 250°C is 0.1 MPa or more and 10 MPa or less. In this way, the insulating layer is not easily deformed by heating at high temperature, and its flexibility at high temperature is also good.

[0018] (5) In any of (1) to (4) above, the heat of fusion of the insulating layer at 70°C or higher, as measured by differential scanning calorimetry, is 1 J / g or higher and 12 J / g or lower. With a heat of fusion of 1 J / g or higher, the crystalline composition prevents adhesion between wires. With a heat of fusion of 12 J / g or lower, the insulating layer exhibits good flexibility.

[0019] (6) In any of (1) to (5) above, the first component may be present in the composition at a content of 50% by mass or more. In this way, the insulating layer can have sufficient strength and heat resistance.

[0020] (7) In any of (1) to (6) above, the insulating layer may be an electron beam crosslinker of the composition. In this way, the strength of the insulating layer is increased.

[0021] (8) The heat shrink tube of this disclosure is formed from a composition comprising a first component, a second component, a brominated flame retardant and zinc oxide, wherein the first component is composed of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer, and the second component is composed of at least one selected from the group consisting of magnesium oxide, calcium carbonate and hydrotalcite, wherein in the composition, the mass ratio M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer is M2 / M1 of 10 / 90 or more and 40 / 60 or less, wherein in the composition, the content of the brominated flame retardant is 1.0 part by mass or more and 40 parts by mass or less relative to 100 parts by mass of the first component, wherein in the composition, the content of the zinc oxide is 1.0 part by mass or more and 25 parts by mass or less relative to 100 parts by mass of the first component, and wherein in the composition, the total content of the second component is 5.0 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the first component.

[0022] According to this disclosure, a heat shrink tube with excellent flame retardancy, suppression of smoke during combustion, excellent flexibility, and excellent tensile elongation can be provided.

[0023] (9) In (8) above, the heat shrink tubing can be used as a cover for the wire. In this way, a wire that suppresses smoke during combustion can be provided.

[0024] (10) In (8) or (9) above, the composition may be an electron beam crosslinker. In this way, the strength of the heat shrink tube is improved.

[0025] [Details of the embodiments disclosed herein] Specific examples of insulated wires and heat shrink tubing of this disclosure are described below with reference to the accompanying drawings. In the drawings of this disclosure, the same reference numerals denote the same or equivalent parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately modified for clarity and simplification of the drawings and do not necessarily represent actual dimensional relationships.

[0026] In this specification, the term "A~B" refers to A above and B below. When there is no unit for A but only for B, the unit of A is the same as the unit of B.

[0027] In this specification, when compounds are represented by chemical formulas, the atomic ratio is not specifically limited, including all previously known atomic ratios, and should not be limited to compounds within the stoichiometric range.

[0028] In this disclosure, when more than one value is recorded as the lower limit and the upper limit of the numerical range, it is also considered that a combination of any value recorded in the lower limit and any value recorded in the upper limit is also disclosed.

[0029] [Implementation Method 1: Insulated Wire] An insulated wire according to one embodiment of this disclosure (hereinafter also referred to as "Embodiment 1") includes a conductor and an insulating layer covering the conductor. The insulating layer is formed of a composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide. The first component is composed of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer. The second component is composed of at least one selected from the group consisting of magnesium oxide, calcium carbonate, and hydrotalcite. In the composition, the mass ratio M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer is M2 / M1, which is 10 / 90 or more and 40 / 60 or less. In the composition, the content of the brominated flame retardant is 1.0 part by mass or more and 40 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the content of the zinc oxide is 1.0 part by mass or more and 25 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the total content of the second component is 5.0 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the first component.

[0030] <Structure of Insulated Wires> like Figure 1 As shown, the insulated wire 1 of Embodiment 1 has a conductor 2 and an insulation layer 3 that directly or indirectly covers the conductor 2. In the insulated wire, an additional layer such as a primer layer may be provided between the conductor and the insulation layer. In this disclosure, insulated wire refers to the concept of an insulated wire in the narrow sense, consisting of a conductor and an insulation coating, and an insulated cable formed by further covering one or more insulated wires in the narrow sense with a protective coating.

[0031] <Conductor> Conductor 2 can be made of copper wire or other conductors used in insulated wires and cables for equipment wiring, automotive wiring, etc. Conductor 2 is constructed by twisting multiple wires together at a certain spacing. There are no particular limitations on the wire material; examples include copper wire, copper alloy wire, aluminum wire, and aluminum alloy wire. Furthermore, conductor 2 is preferably a stranded wire formed by twisting multiple wires together, and further twisted together to form a stranded wire. The stranded wire to be twisted can be formed by twisting the same number of wires together.

[0032] The average area (including the gaps between wires) in the cross-section of conductor 2 with the extension direction as the normal (hereinafter also referred to as the "cross-section of conductor 2") can be appropriately set according to the application. The lower limit of the average area in the cross-section of conductor 2 can be 0.01 mm². 2 The average area in the cross-section of conductor 2 is less than 0.01 mm². 2 In this case, there is a possibility that the allowable current may decrease. On the other hand, the upper limit of the average area in the cross-section of conductor 2 can be 200 mm². 2The following applies to areas with an average area exceeding 200mm². 2 In such cases, there is a possibility of flexibility damage and difficulty in wiring. The lower limit of the average area in the cross-section of conductor 2 (including the gaps between wires) can be 0.05 mm². 2 The above can be 0.10mm 2 The above. The upper limit of the average area in the cross-section of conductor 2 (including the gaps between wires) can be 100 mm². 2 The following can be 80mm 2 The average area in the cross-section of conductor 2 can be 0.01 mm². 2 Above and 200mm 2 The following can be 0.05mm 2 Above and 100mm 2 The following can be 0.10mm 2 Above and 80mm 2 the following.

[0033] <Insulation layer> In the insulated wire of Embodiment 1, the insulation layer is formed from a composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide.

[0034] The First Component The first component consists of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer.

[0035] The first component contains a tetrafluoroethylene-propylene copolymer, which improves the flexibility of the insulation layer. The tetrafluoroethylene-propylene copolymer is obtained by low-temperature emulsion copolymerization of tetrafluoroethylene and propylene. The tetrafluoroethylene-propylene copolymer may contain appropriate amounts of other copolymerizable monomers as components, such as one or more of ethylene, isobutylene, acrylic acid and its alkyl esters, methacrylic acid and its alkyl esters, vinyl fluoride, vinylidene fluoride, hexafluoropropylene, chloroethyl vinyl ether, chlorotrifluoroethylene, and perfluoroalkyl vinyl ether. Tetrafluoroethylene-propylene copolymers are generally known and readily available as commercially available products.

[0036] The first component contains an ethylene-tetrafluoroethylene copolymer, which improves the heat resistance and strength of the insulation layer. The ethylene-tetrafluoroethylene copolymer may contain appropriate amounts of ethylene and other copolymerizable monomers, such as one or more of ethylene, isobutylene, acrylic acid and its alkyl esters, methacrylic acid and its alkyl esters, vinyl fluoride, vinylidene fluoride, hexafluoropropylene, chloroethyl vinyl ether, chlorotrifluoroethylene, and perfluoroalkyl vinyl ether. Ethylene-tetrafluoroethylene copolymers are generally known and readily available as commercially available products.

[0037] In the composition constituting the insulating layer, the ratio of the mass M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer, M2 / M1, is 10 / 90 or more and 40 / 60 or less. If the ratio M2 / M1 is less than 10 / 90, there is a possibility that the heat resistance of the insulating layer becomes insufficient. If the ratio M2 / M1 exceeds 40 / 60, there is a possibility that the flexibility of the insulated wire 1 becomes insufficient. The ratio M2 / M1 can be 15 / 85 or more and 37 / 63 or less, or 20 / 80 or more and 30 / 70 or less.

[0038] The ratio M2 / M1 was calculated by solid-state NMR.

[0039] The lower limit of the content of the first component in the insulating layer 3 can be 50% by mass or more, 60% by mass or more, or 65% by mass or more. The upper limit of the content of the first component in the insulating layer 3 can be 97% by mass or less, or 95% by mass or less. If the content of the first component in the insulating layer 3 is less than 50% by mass, there is a possibility that sufficient strength and heat resistance may not be obtained. On the other hand, if the content of the first component exceeds 97% by mass, there is a possibility that the effects of other compounding agents may become insufficient due to insufficient content of other compounding agents besides the first component. The content of the first component in the insulating layer 3 can be 50% by mass or more and 97% by mass or less, 60% by mass or more and 97% by mass or less, or 65% by mass or more and 95% by mass or less.

[0040] The method for determining the content of the first component in the insulating layer 3 is as follows. The mass concentration (%) of fluorine in the insulating layer 3 is determined by combustion ion chromatography, and the content of the first component in the insulating layer 3 is calculated based on the ratio M2 / M1 determined by solid-state NMR.

[0041] Tetrafluoroethylene-propylene copolymers and ethylene-tetrafluoroethylene copolymers can be cross-linked by irradiation with an electron beam. Therefore, the insulating layer can be an electron beam cross-linked composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide.

[0042] The Second Component The second component comprises at least one selected from the group consisting of magnesium oxide, calcium carbonate, and hydrotalcite. In the composition constituting the insulating layer, the total content of the second component relative to 100 parts by mass of the first component is 5.0 parts by mass or more and 50 parts by mass or less. The lower limit of the total content of the second component relative to 100 parts by mass of the first component is 5.0 parts by mass or more, but can be 10 parts by mass or more, or 20 parts by mass or more. The upper limit of the total content of the second component relative to 100 parts by mass of the first component is 50 parts by mass or less, but can be 45 parts by mass or less, or 40 parts by mass or less. If the total content of the second component relative to 100 parts by mass of the first component is less than 5.0 parts by mass, there is a possibility that the flame-retardant effect may not be sufficiently obtained. On the other hand, if the total content of the second component relative to 100 parts by mass of the first component exceeds 50 parts by mass, there is a possibility that the mechanical strength of the insulating layer, such as tensile strength and elongation at break, may decrease. In the composition constituting the insulating layer, the total content of the second component may be 10 parts by mass or more and 45 parts by mass or less, or 20 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the first component.

[0043] In the composition constituting the insulating layer, the total content of the second component relative to 100 parts by mass of the first component is calculated by determining the mass concentration (%) of each filler in the composition constituting the insulating layer using fluorescence X-ray analysis.

[0044] The lower limit of the average particle size of the second component can be 0.05 μm or more, or 0.5 μm or more. The upper limit of the average particle size of the second component can be 5 μm or less, or 3 μm or less. If the lower limit of the average particle size of the second component is less than 0.05 μm, there is a possibility of poor dispersion leading to agglomeration, which may reduce the mechanical strength of the insulation layer, such as tensile strength and elongation. If the upper limit of the average particle size of the second component exceeds 5 μm, there is a possibility of mold waste being generated during molding, resulting in an insulation layer with an unsatisfactory appearance. The average particle size of the second component can be 0.05 μm or more and 5 μm or 0.5 μm or more and 5 μm or less.

[0045] The method for determining the average particle size of the second component contained in the insulating layer is as follows. A cross-section of the insulating layer is observed using SEM. For the cross-sectional SEM image, the diameter of 100 second components is measured, and their average value is calculated. This average value corresponds to the average particle size of the second component contained in the insulating layer.

[0046] Brominated flame retardants Examples of bromine-based flame retardants include decabromodiphenyl ether, hexabromobenzene, ethylene bis(tetrabromophthalimide), 2,2-bis(4-bromoethyl ether-3,5-dibromophenyl)propane, ethylene bis(dibromonorbornene)dicarboximide, tetrabromo-bisphenol S, tris(2,3-dibromopropyl-1)isocyanurate, hexabromocyclododecane (HBCD), octabromophenyl ether, tetrabromobisphenol A (TBA) epoxy oligomers or polymers, TBA-bis(2,3-dibromopropyl ether), polydibromophenyl ether, bis(tribromophenoxy)ethane, ethylene bis(pentabromobenzene), and dibromoethyl-dibromocyclohexane. Alkane, dibromoneopentyl glycol, tribromophenol, tribromophenol allyl ether, tetradecylbromo-diphenoxybenzene, 1,2-bis(2,3,4,5,6-pentabromophenyl)ethane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxyethoxy-3,5-dibromophenyl)propane, pentabromophenol, pentabromotoluene, pentabromodiphenyl ether, hexabromodiphenyl ether, octabromodiphenyl ether, dibromoneopentyl glycol tetracarbonate, bis(tribromophenyl)fumaramide, N-methylhexabromoaniline, etc., can be used alone or in combination of two or more.

[0047] In the composition constituting the insulating layer, the content of the brominated flame retardant is 1.0 part by mass and 40 parts by mass or less per 100 parts by mass of the first component. The lower limit of the content of the brominated flame retardant per 100 parts by mass of the first component is 1.0 part by mass or more, but can be 3 parts by mass or more, or 5 parts by mass or more. The upper limit of the content of the brominated flame retardant per 100 parts by mass of the first component is 40 parts by mass or less, but can be 30 parts by mass or less, or 20 parts by mass or less. If the content of the brominated flame retardant per 100 parts by mass of the first component is less than 1.0 part by mass, there is a possibility that the flame retardant effect may not be sufficiently obtained. On the other hand, if the content of the brominated flame retardant per 100 parts by mass of the first component exceeds 40 parts by mass, there is a possibility that the mechanical strength of the insulating layer, such as tensile strength and elongation at break, may decrease. The content of the brominated flame retardant per 100 parts by mass of the first component can be 3 parts by mass and 30 parts by mass or 5 parts by mass and 20 parts by mass or less.

[0048] The method for determining the content of brominated flame retardant in the composition constituting the insulating layer relative to 100 parts by mass of the first component is as follows. The type of brominated flame retardant is identified by IR determination. The content of brominated flame retardant relative to 100 parts by mass of the first component is calculated based on the mass concentration (%) of bromine in the composition constituting the insulating layer determined by combustion ion chromatography.

[0049] Zinc oxide As zinc oxide, it can be used without particular restrictions, for example, by oxidizing the zinc vapor produced by adding a reducing agent such as coke to zinc ore and then calcining it with air; zinc oxide obtained from zinc sulfate or zinc chloride as raw materials, etc.

[0050] In the composition constituting the insulating layer, the content of zinc oxide relative to 100 parts by mass of the first component is 1.0 part by mass or more and 25 parts by mass or less. The lower limit of the zinc oxide content relative to 100 parts by mass of the first component is 1.0 part by mass or more, but can be 3 parts by mass or more, or 5 parts by mass or more. The upper limit of the zinc oxide content relative to 100 parts by mass of the first component is 25 parts by mass or less, but can be 20 parts by mass or less, or 10 parts by mass or less. If the zinc oxide content relative to 100 parts by mass of the first component is less than 1.0 part by mass, it becomes a cause of burn mark during the mixing and extrusion processes. If the zinc oxide content relative to 100 parts by mass of the first component exceeds 25 parts by mass, there is a possibility of a decrease in the mechanical strength of the insulating layer, such as tensile strength and elongation at break. In the composition constituting the insulating layer, the content of zinc oxide relative to 100 parts by mass of the first component can be 3 parts by mass or more and 20 parts by mass or 5 parts by mass or more and 10 parts by mass or less.

[0051] In the composition constituting the insulating layer, the content of zinc oxide relative to 100 parts by mass of the first component is determined by calculating the zinc oxide content based on the zinc mass concentration (%) of the composition constituting the insulating layer obtained by fluorescence X-ray analysis.

[0052] The lower limit of the average particle size of zinc oxide can be above 0.05 μm or above 0.5 μm. The upper limit of the average particle size of zinc oxide can be below 5 μm or below 3 μm. If the lower limit of the average particle size of zinc oxide is less than 0.05 μm, there is a possibility of poor dispersion leading to agglomeration, which may reduce the mechanical strength of the insulation layer, such as tensile strength and elongation. If the upper limit of the average particle size of zinc oxide exceeds 5 μm, there is a possibility of mold waste being generated during molding, resulting in an insulation layer with an unsatisfactory appearance. The average particle size of zinc oxide can be above 0.05 μm and below 5 μm, or above 0.5 μm and below 3 μm.

[0053] The method for determining the average particle size of zinc oxide contained in the insulating layer is as follows. A cross-section of the insulating layer is observed using SEM. For the cross-sectional SEM image, the diameter of 100 zinc oxide particles is measured, and their average value is calculated. This average value corresponds to the average particle size of zinc oxide contained in the insulating layer.

[0054] Storage modulus of insulation layer at 250°C The lower limit of the energy storage modulus of the insulating layer 3 at 250°C can be 0.1 MPa or more, 0.5 MPa or more, or 1.0 MPa or more. The upper limit of the energy storage modulus of the insulating layer 3 at 250°C can be 10 MPa or less, 8 MPa or less, or 6 MPa or less. If the energy storage modulus of the insulating layer 3 at 250°C is less than 0.1 MPa, there is a possibility that the insulating layer 3 may easily deform under high temperature. On the other hand, if the energy storage modulus of the insulating layer 3 at 250°C exceeds 10 MPa, there is a possibility that the flexibility of the insulating layer 3 may decrease at high temperature. Therefore, the energy storage modulus of the insulating layer 3 at 250°C can be 0.1 MPa or more and 10 MPa or less, 0.5 MPa or more and 8 MPa or less, or 1.0 MPa or more and 6 MPa or less.

[0055] In this disclosure, "storage modulus at 250°C" refers to the value determined according to the test method for dynamic mechanical properties described in JIS K7244-4:1999. The insulation layer is removed from the wire to prepare the sample. Using a viscoelasticity measuring apparatus, the storage modulus at 250°C is measured under tensile conditions, strain 0.08%, and frequency 10 Hz. The heating rate from room temperature to 250°C is set to 10°C / min. For example, the "DVA-220" manufactured by IT Measurement & Control Co., Ltd. can be used as the viscoelasticity measuring apparatus.

[0056] Heat of fusion of insulating layers above 70°C, determined by differential scanning. The lower limit of the heat of fusion of the insulation layer 3 at 70°C or higher, as measured by differential scanning calorimetry, can be 1 J / g or higher, or 2 J / g or higher. If the heat of fusion is 1 J / g or higher, the crystalline composition can prevent adhesion between wires. On the other hand, the upper limit of the heat of fusion can be 12 J / g or lower, or 10 J / g or lower. If the upper limit of the heat of fusion is 12 J / g or lower, the insulation layer can have good flexibility. The heat of fusion of the insulation layer 3 at 70°C or higher, as measured by differential scanning calorimetry, can be 1 J / g or higher and 12 J / g or lower, or 2 J / g or higher and 10 J / g or lower.

[0057] The heat of fusion mentioned above can be obtained from the melting curve obtained by differential scanning calorimetry (DSC). The melting curve is obtained by performing DSC under the following conditions: Using a differential scanning calorimeter, a 5 mg sample consisting of an insulating layer is heated from -50 °C to 300 °C in a nitrogen atmosphere at a heating rate of 10 °C / min. The area of ​​all endothermic peaks appearing after 70 °C is calculated. It should be noted that in the case of multi-peaked peaks, the area of ​​the entire peak is calculated.

[0058] Insulation layer thickness The average thickness of the insulating layer 3 is not particularly limited; for example, it can be 0.1 mm or more and 10 mm or less, 0.2 mm or more and 5 mm or less, or 0.5 mm or more and 2 mm or less. Here, "average thickness" refers to the average of the thickness measured at any ten locations. It should be noted that the same definition applies when referring to "average thickness" for other components, etc., below.

[0059] The composition constituting the insulating layer may include other components together with the first component, the second component, the brominated flame retardant, and the zinc oxide, provided that this does not impair the effects of the present disclosure. Examples of such other components include, for instance, crosslinking aids and other additives described later.

[0060] To promote the crosslinking of the resin achieved by electron beam irradiation, the composition constituting the insulating layer may contain a crosslinking aid. The content of the crosslinking aid varies depending on the type of crosslinking aid, and is generally between 1 and 10 parts by mass relative to 100 parts by mass of the first component. Examples of crosslinking aids include: oximes such as p-quinone dioxime and dibenzoyl-p-quinone dioxime; acrylates or methacrylates such as ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, cyclohexyl methacrylate, acrylate / zinc oxide mixtures, allyl methacrylate, and trimethacryloyl isocyanurate (hereinafter also referred to as TMIC); and divinylbenzene, vinyltoluene, vinylpyridine, etc. Vinyl monomers; allyl compounds such as hexamethylene diallyl nadicimide, diallyl itaconic acid, diallyl phthalate, diallyl isophthalate, diallyl monoglycidyl isocyanurate, triallyl cyanurate, and triallyl isocyanurate (hereinafter also referred to as TAIC); and maleimide compounds such as N,N'-m-phenylenebismaleimide and N,N'-(4,4'-methylenediphenyl)dimaleimide. These crosslinking aids can be used alone or in combination.

[0061] The composition constituting the insulating layer may contain other additives as needed. Examples of such additives include strength retainers, antioxidants, copper-damaging agents, colorants, heat stabilizers, and ultraviolet absorbers. The content of additives in the composition constituting the insulating layer may be less than 40% by mass or less than 25% by mass. When the content of additives is 40% by mass or more, there is a possibility of a decrease in the ratio of the first component of the insulating layer and a decrease in strength.

[0062] <Applications of Insulated Wires> The insulated wire of Implementation Method 1 can be used as wiring inside equipment or inside automobiles.

[0063] <Manufacturing Method of Insulated Wires> The manufacturing method of the insulated wire in Embodiment 1 is not particularly limited, but may include the following steps.

[0064] (1) The process of preparing a resin composition for forming an insulating layer (resin composition preparation process).

[0065] (2) The process of coating a conductor with a resin composition (coating process).

[0066] (3) The process of crosslinking the resin composition by irradiation (crosslinking process).

[0067] (1) Resin composition preparation process In the resin composition preparation process, a resin composition for forming an insulating layer is prepared by mixing a first component, a second component, a brominated flame retardant, zinc oxide, and other additives added as needed using a melt mixer or the like. Known melt mixers can be used, such as open mills, Banbury mixers, pressure kneaders, single-screw mixers, and multi-screw mixers.

[0068] (2) Coating process In the coating process, for example, a melt extrusion molding machine is used to extrude a resin composition onto a conductor to coat the conductor with the resin composition.

[0069] (3) Crosslinking process In the crosslinking process, the resin composition of the coated conductor is crosslinked by irradiation. By crosslinking the first component of the resin composition (tetrafluoroethylene-propylene copolymer and ethylene-tetrafluoroethylene copolymer), the insulating layer acquires shape retention at high temperatures. One method for crosslinking the first component is to irradiate the resin composition with an electron beam. Since it is difficult to mold after crosslinking the first component by electron beam irradiation, electron beam irradiation is performed after the extrusion molding process. By performing electron beam irradiation after extrusion molding, molding can be reliably performed, and the effects achieved by electron beam irradiation can be fully obtained.

[0070] The electron beam irradiation dose can be in the range of 50 kGy or more and 400 kGy or less. When the electron beam irradiation dose is less than 50 kGy, there is a possibility that the degree of cross-linking will decrease and the shape retention at high temperatures will be reduced. On the other hand, when the electron beam irradiation dose exceeds 400 kGy, manufacturing will take longer.

[0071] [Implementation Method 2: Heat Shrink Tube] In another embodiment of this disclosure (hereinafter also referred to as "Embodiment 2"), the heat shrink tube is formed from a composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide. The first component is composed of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer. The second component is composed of at least one selected from the group consisting of magnesium oxide, calcium carbonate, and hydrotalcite. In the composition, the mass ratio M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer, M2 / M1, is 10 / 90 or more and 40 / 60 or less. In the composition, the content of the brominated flame retardant is 1.0 part by mass or more and 40 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the content of the zinc oxide is 1.0 part by mass or more and 25 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the total content of the second component is 5.0 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the first component.

[0072] <Structure of heat shrink tubing> like Figure 2 As shown, the heat shrink tube 10 of Embodiment 2 is composed of a single-layer substrate layer in a cylindrical shape. The heat shrink tube 10 is used for coating purposes such as protection, insulation, waterproofing, and corrosion prevention in connection parts between objects, wiring terminals, and metal pipes. The heat shrink tube of Embodiment 2 is not limited to... Figure 2 The single-layer substrate layer shown is formed into a cylindrical heat shrink tube, for example, the substrate layer can be formed into a cap-shaped heat shrink tube. Such a heat shrink tube is manufactured by heating and shrinking one end of the cylindrical heat shrink tube to seal it. This heat shrink tube can be preferably used, for example, for the termination treatment of wiring.

[0073] The average inner diameter and average thickness of the heat shrink tubing 10 are appropriately selected according to the application and other factors. The average inner diameter of the heat shrink tubing 10 before heat shrinking can be, for example, 1 mm or more and 60 mm or less. Furthermore, the average inner diameter of the heat shrink tubing 10 after heat shrinking can be, for example, 30% or more and 50% or less of the average inner diameter before heat shrinking. Furthermore, the average thickness of the heat shrink tubing 10 can be, for example, 0.1 mm or more and 5 mm or less.

[0074] <Composition> The composition constituting the heat shrink tube of Embodiment 2 is formed from a composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide. The composition constituting the heat shrink tube of Embodiment 2 can be configured to have the same structure as the composition constituting the insulating layer of the insulated wire of Embodiment 1, therefore this description will not be repeated. The heat shrink tube of Embodiment 2 exhibits excellent flame retardancy, suppresses smoke during combustion, and possesses excellent flexibility and excellent tensile elongation.

[0075] <Applications of Heat Shrink Tubing> In Embodiment 2, the heat shrink tubing is used as a covering for protecting a coated object. More specifically, examples include heat shrink tubing that shrinks in the inner diameter direction when heated above the melting point of an ethylene-tetrafluoroethylene copolymer. The heat shrink tubing, with the coated object inserted, is heated onto the coated object, causing it to shrink. This protects the coated object. The heat shrink tubing is also used as a covering for protecting the connection parts of wires, pipes, etc., and other coated objects.

[0076] <Manufacturing Method of Heat Shrink Tube> The manufacturing method of the heat shrink tube in Embodiment 2 is not particularly limited, but may include the following steps.

[0077] (1) The process of preparing a resin composition for forming a heat shrink tube (resin composition preparation process).

[0078] (2) The process of extruding the resin composition through a melt extrusion molding machine (extrusion molding process).

[0079] (3) The process of cross-linking extruded products by irradiation (cross-linking process).

[0080] (4) The process of expanding the diameter of the cross-linked extruded product to obtain a heat shrink tube (diameter expansion process).

[0081] (1) Resin composition preparation process In the resin composition preparation process, a resin composition for forming heat shrink tubes is prepared by mixing a first component, a second component, a brominated flame retardant, zinc oxide, and other additives added as needed, using a melt mixer or the like. Known melt mixers can be used, such as open mills, Banbury mixers, pressure kneaders, single-screw mixers, and multi-screw mixers.

[0082] (2) Extrusion molding process In the extrusion molding process, a resin composition is extruded through a melt extrusion molding machine. Specifically, an extrusion die with a cylindrical space is used to extrude the resin composition into a cylindrical shape. This yields an extruded molded article. The dimensions of the extruded molded article can be designed according to its intended use, etc.

[0083] (3) Crosslinking process In the crosslinking process, the extruded molded article is crosslinked by irradiation. The irradiation conditions can be set to the same conditions as those in the crosslinking process of the above-described method for manufacturing insulated wires.

[0084] (4) Diameter expansion process In the diameter expansion process, the cross-linked extruded molded article is expanded in diameter. Commonly known diameter expansion methods used in the manufacture of heat shrink tubes can be used for this purpose. Examples include: introducing compressed air into the extruded molded article while heating it to a temperature above its melting point; expanding the diameter to a predetermined inner diameter by external decompression or inserting a metal rod; and then cooling to fix the shape. This diameter expansion is typically performed such that the inner diameter of the extruded molded article is, for example, 1.2 times or more but less than 4 times its original size. The heat shrink tube is obtained by fixing the shape of the expanded extruded molded article. Examples of methods for fixing this shape include cooling to a temperature below the melting point of the base resin component. It should be noted that, in the diameter expansion process, to reduce the impact on the surface roughness of the inner surface of the heat shrink tube, the roughness of the metal rod can be reduced, or a coating or lubricant can be applied. Furthermore, reducing the diameter expansion speed can also reduce the impact on the surface roughness of the inner surface of the heat shrink tube. In this way, the cross-linked extruded product, with its expanded diameter and fixed shape, becomes a heat shrink tube.

[0085] [Appendix 1] A heat shrinkable tube is formed from a composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide. The first component is composed of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer. The second component is composed of at least one selected from the group consisting of magnesium oxide, calcium carbonate, and hydrotalcite. In the composition, the mass ratio M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer is M2 / M1, which is 10 / 90 or more and 40 / 60 or less. In the composition, the content of the brominated flame retardant is 1.0 part by mass or more and 40 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the content of the zinc oxide is 1.0 part by mass or more and 25 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the total content of the second component is 5.0 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the first component.

[0086] [Appendix 2] According to the heat shrink tube described in Appendix 1, the average particle size of the second component is 0.05 μm or more and 5 μm or less.

[0087] [Appendix 3] According to Appendix 1 or Appendix 2, the heat shrink tube has an average particle size of 0.05 μm or more and 5 μm or less.

[0088] [Appendix 4] The heat shrink tube according to any one of Annexes 1 to 3, wherein the energy storage modulus of the insulating layer at 250°C is 0.1 MPa or more and 10 MPa or less.

[0089] [Appendix 5] According to any one of Annexes 1 to 4, the heat shrink tube of the insulating layer, as measured by differential scanning calorimetry, has a melting heat of 1 J / g or more and 12 J / g or less at 70°C or higher.

[0090] [Appendix 6] The heat shrink tube according to any one of Annexes 1 to 5, wherein the first component is present in a content of 50% by mass or more in the composition.

[0091] [Appendix 7] The heat shrink tube according to any one of Annexes 1 to 6, wherein the insulating layer is an electron beam crosslinker of the composition.

[0092] [Appendix 8] The heat shrink tube according to any one of Annexes 1 to 7, wherein the composition is free of antimony trioxide.

[0093] [Appendix 9] An insulated wire includes a conductor and an insulating layer covering the conductor. The insulating layer is formed of a composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide. The first component is composed of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer. The second component is composed of at least one selected from the group consisting of magnesium oxide, calcium carbonate, and hydrotalcite. In the composition, the mass ratio M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer is M2 / M1, which is 10 / 90 or more and 40 / 60 or less. In the composition, the content of the brominated flame retardant is 1.0 part by mass or more and 40 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the content of the zinc oxide is 1.0 part by mass or more and 25 parts by mass or less relative to 100 parts by mass of the first component. In the composition, the total content of the second component is 5.0 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the first component. The composition does not contain antimony trioxide.

[0094] Example The present embodiment is further described in detail through examples. However, the present embodiment is not limited by these examples.

[0095] [Making Insulated Wires] <Sample 1 to Sample 16, Sample 101 to Sample 108> As a conductor, a cross-sectional area of ​​0.35 mm² is prepared. 2 Copper wire.

[0096] The raw materials for the resin composition are described.

[0097] The First Component The following raw materials are prepared as the first component.

[0098] Tetrafluoroethylene-propylene copolymer (referred to as "TFE-P" in the table): "AFLAS 150CS" manufactured by AGC.

[0099] Ethylene-tetrafluoroethylene copolymer (referred to as "ETFE" in the table): "Fluon LM730AP" manufactured by AGC.

[0100] The Second Component The following raw materials are prepared as the second component.

[0101] Calcium carbonate (1): "WHITON SB" manufactured by Whitestone Calcium Company.

[0102] Calcium carbonate (2): Vigot 15 manufactured by White Stone Industries.

[0103] Calcium carbonate (3): “BF300” manufactured by Beibei Powder Chemical Co., Ltd.

[0104] Magnesium oxide: Kyowa Chemical Industry Co., Ltd.'s "Kyowamag 150".

[0105] Hydrotalcite: "DHT-4A" manufactured by Kyowa Chemical Industry Co., Ltd.

[0106] The average particle size of the second component used in each sample is shown in the "Average Particle Size" column of "Second Component" in Tables 1 to 3.

[0107] Brominated flame retardants As a brominated flame retardant, prepare the following.

[0108] Bromine-based flame retardants (1): Albemarle Japan's "SAYTEX8010" (ethylene bis-pentabromobenzene).

[0109] Bromine-based flame retardants (2) Albemarle's "SAYTEXBT-93" (ethylene bis(tetrabromophthalimide)) manufactured by Japan.

[0110] Zinc oxide Prepare the following as zinc oxide.

[0111] Zinc oxide (1): “Zinc Oxide Type I” manufactured by Sakai Chemical Industry Co., Ltd.

[0112] Zinc oxide (2): "Fine zinc oxide" manufactured by Sakai Chemical Industry Co., Ltd.

[0113] The average particle size of zinc oxide used in each sample is shown in the "Average Particle Size" column of "Zinc Oxide" in Tables 1 to 3.

[0114] Mix the raw materials according to the formula in the table to prepare the resin composition. "-" in the table indicates that the corresponding component was not used. The conductor was coated with the resin composition by extruding it onto the conductor. An extrusion die was used in the extrusion molding process. The extrusion molding was performed at a die temperature of 250°C and a linear speed of 5 m / min. Next, the resin composition was irradiated with an electron beam in all samples except sample 16 to obtain insulated wires for each sample. The electron beam irradiation dose was set to 100 kGy. Sample 16 was not irradiated with an electron beam. The average thickness of the insulation layer in all samples was 1 mm.

[0115] Although multiple insulated wires were fabricated for sample 102, they stuck together before the various tests were conducted, making it impossible to maintain the shape of the insulated wires. Therefore, the following tests were not performed on sample 102. In Table 3, items that were not tested are indicated as "N / A".

[0116] During the extrusion of the insulating layer, resin scorching occurred in sample 105, preventing the formation of a good insulating layer. Therefore, the following various measurements were not performed on sample 105.

[0117] [Evaluation of the insulation layer] For the insulation layer of each insulated wire sample, the storage modulus at 250°C, the heat of fusion above 70°C, the 2% secant modulus, the tensile strength, and the tensile elongation were evaluated.

[0118] Storage modulus of insulation layer at 250°C The energy storage modulus of the insulation layer at 250°C was measured according to the test method for dynamic mechanical properties described in JIS K7244-4:1999, based on the method described in Embodiment 1.

[0119] Heat of fusion of the insulating layer above 70°C, measured by differential scanning calorimetry The heat of fusion above 70°C of the insulating layer measured by differential scanning calorimetry was determined by differential scanning calorimetry (trade name "DSC8500", manufactured by Perkin Elmer) based on the method described in Embodiment 1.

[0120] 《Tensile Strength and Tensile Elongation of Insulating Layer》 The tensile strength [MPa] and tensile elongation [%] of the insulating layer were measured according to JIS K7161-2:2014. The test temperature was set at 23 ± 2°C, the test humidity was set at 50 ± 10%, and the test speed was set at 500 mm / min. In the present disclosure, when the tensile strength is 10.3 MPa or more, it is judged that the insulating layer has excellent tensile strength. In the present disclosure, when the tensile elongation is 200% or more, it is judged that the insulating layer has excellent tensile elongation.

[0121] 《2% Secant Modulus of Insulating Layer》 The insulating layer with a length of 100 mm was stretched at a stretching speed of 50 mm / min using a tensile testing machine, and the value obtained by dividing the load at an elongation of 2% by the cross-sectional area was multiplied by 50 times the tensile strength as the 2% secant modulus. The test temperature was set at 23 ± 2°C, the test humidity was set at 50 ± 10%, and the test speed was set at 50 mm / min. In the present disclosure, when the 2% secant modulus is 120 MPa or less, it is judged that the insulating layer has excellent flexibility.

[0122] The evaluation results of the above insulating layer are shown in Tables 1 to 3.

[0123] [Flame Retardant Test] For the insulated wires of each specimen, 5 test samples were prepared. The 5 test samples were subjected to the VW-1 vertical flame retardant test described in UL standard 1581, item 1080. During the test, when the test sample was repeatedly ignited for 15 seconds 5 times, a sample that extinguished within 60 seconds, the absorbent cotton laid under it did not burn due to the burning debris, and the kraft paper assembled on the upper part of the test sample did not burn or char was rated as qualified. When all 5 were rated as qualified, it was set as qualified "OK". When even 1 of the 5 did not reach the qualified grade, it was set as unqualified "NG". The results are shown in the "Flame Retardant Test" column of Tables 1 to 3.

[0124] [Smoke Generation Test] Test samples were prepared with the same composition as the insulating layer of each specimen. Test samples other than specimen 16 were irradiated with an electron beam. Test samples for specimen 16 were not irradiated with an electron beam. Smoke production tests were conducted using the test samples in an NBS smoke density test chamber. The maximum value Dm of the specific optical density (Ds) described in JIS C0081:2002 (IEC 60695-6-31:1000) was determined. The results are shown in the "Smoke Production Test Dm" column of Tables 1 to 3. If the maximum value Dm is 100 or less, it is determined that smoke production during combustion of the test sample is suppressed.

[0125] [Heating Deformation Test] For each sample of insulated wire, according to ISO 6722, a 0.7 mm thick cutting edge was pressed onto the surface of the insulation layer with a load based on Formula 1 below, and held at 200°C for 4 hours. Then, a voltage of 1 kV was applied to the insulated wire in water for 1 minute to check for insulation breakdown.

[0126] Load [N] = 0.8 × √{i × (2D - i)} Equation 1 In Formula 1 above, D: the finished outer diameter of the insulated wire [mm], and i: the thickness of the insulator [mm].

[0127] If no insulation breakdown occurs, mark it as "OK" (qualified). If insulation breakdown occurs, mark it as "NG" (unqualified). Show the results in the "Heating Deformation Test" column of Tables 1 to 3.

[0128] [Inspection] The insulated wires of Specimens 1 to 16 are equivalent to the Examples. For the insulated wires of Specimens 1 to 16 (Examples), it was confirmed that the 2% secant modulus of the insulation layer is less than 120 MPa, exhibiting excellent flexibility; the tensile elongation of the insulation layer is more than 200%, exhibiting excellent tensile elongation; it has excellent flame retardancy with a passing grade in the flame retardant test; and smoke generation during combustion is suppressed.

[0129] The insulated wires of samples 101 to 108 are equivalent to comparative examples.

[0130] In the insulated wire of sample 101, 2% of the wires had a cleavage modulus exceeding 120 MPa, indicating insufficient flexibility.

[0131] Although multiple insulated wires were fabricated for sample 102, they adhered to each other before various tests were conducted, making it impossible to maintain the shape of the insulated wires. Therefore, various tests were not performed on sample 102.

[0132] In the smoke emission test, the maximum value Dm of sample 103 was 118, indicating that smoke emission was not suppressed during combustion.

[0133] In samples 104, 106 and 108, the tensile elongation was less than 200%, indicating insufficient tensile elongation.

[0134] During the extrusion of the insulating layer, resin scorching occurred in sample 105, preventing the formation of a good insulating layer. Therefore, various measurements were not performed on sample 105.

[0135] In sample 107, the flame retardant test result was unqualified (NG).

[0136] The embodiments and examples of this disclosure have been described as above, but it is also intended that the above embodiments and examples be appropriately combined or modified.

[0137] The embodiments and examples disclosed herein should be considered exemplary rather than limiting in all respects. The scope of the invention is not shown by the above embodiments and examples, but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0138] Explanation of reference numerals in the attached figures 1: Insulated wire; 2: Conductor; 3: Insulation layer; 10: Heat shrink tubing.

Claims

1. An insulated wire comprising a conductor and an insulating layer covering the conductor, The insulating layer is formed of a composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide. The first component is composed of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer. The second component consists of at least one selected from the group consisting of magnesium oxide, calcium carbonate, and hydrotalcite. In the composition, the mass ratio M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer, M2 / M1, is 10 / 90 or more and 40 / 60 or less. In the composition, the content of the brominated flame retardant is 1.0 part by weight or more and 40 parts by weight or less, relative to 100 parts by weight of the first component. In the composition, the content of zinc oxide is 1.0 part by weight or more and 25 parts by weight or less relative to 100 parts by weight of the first component. In the composition, the total content of the second component is 5.0 parts by mass and 50 parts by mass or less relative to 100 parts by mass of the first component.

2. The insulated wire according to claim 1, wherein, The average particle size of the second component is greater than 0.05 μm and less than 5 μm.

3. The insulated wire according to claim 1 or 2, wherein, The average particle size of the zinc oxide is greater than 0.05 μm and less than 5 μm.

4. The insulated wire according to any one of claims 1 to 3, wherein, The energy storage modulus of the insulating layer at 250°C is above 0.1 MPa and below 10 MPa.

5. The insulated wire according to any one of claims 1 to 4, wherein, The heat of fusion of the insulating layer at 70°C or higher, as measured by differential scanning calorimetry, is 1 J / g or higher and 12 J / g or lower.

6. The insulated wire according to any one of claims 1 to 5, wherein, In the composition, the first component is present in an amount of 50% by mass or more.

7. The insulated wire according to any one of claims 1 to 6, wherein, The insulating layer is an electron beam crosslinker of the composition.

8. A heat shrinkable tube formed of a composition comprising a first component, a second component, a brominated flame retardant, and zinc oxide. The first component is composed of a tetrafluoroethylene-propylene copolymer and an ethylene-tetrafluoroethylene copolymer. The second component consists of at least one selected from the group consisting of magnesium oxide, calcium carbonate, and hydrotalcite. In the composition, the mass ratio M2 of the ethylene-tetrafluoroethylene copolymer to the mass M1 of the tetrafluoroethylene-propylene copolymer, M2 / M1, is 10 / 90 or more and 40 / 60 or less. In the composition, the content of the brominated flame retardant is 1.0 part by weight or more and 40 parts by weight or less, relative to 100 parts by weight of the first component. In the composition, the content of zinc oxide is 1.0 part by weight or more and 25 parts by weight or less relative to 100 parts by weight of the first component. In the composition, the total content of the second component is 5.0 parts by mass and 50 parts by mass or less relative to 100 parts by mass of the first component.

9. The heat shrink tubing according to claim 8, wherein, The heat shrink tubing is the coating for the electrical wire.

10. The heat shrink tubing according to claim 8 or 9, wherein, The composition is an electron beam crosslinker.

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