Insulated wire

Abstract

To provide an insulated wire which has high dynamic cut through characteristics, and holds high flame retardancy and excellent electric characteristics.SOLUTION: An insulated wire has a conductor, and a flame-retardant insulation layer of a single layer which is provided on the conductor, wherein the flame-retardant insulation layer is composed of a resin material containing a polymer component and a metal hydroxide, the polymer component contains high density polyethylene, maleic anhydride-modified high density polyethylene, an ethylene-acrylate-maleic anhydride terpolymer, ethylene-α-polyolefin modified with maleic anhydride, and an ethylene-acrylate copolymer, the metal hydroxide has a specific surface area by BET method of 8 to 11 m2 / g, an average particle diameter of the metal hydroxide is 0.6 to 1.5 μm, and the average particle diameter is a particle diameter in a 50% integrated value in particle size distribution determined by a laser diffraction / scattering method.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an insulated wire. [Background technology]

[0002] Electric wires and cables used in railroad cars, automobiles, and equipment are required to have high dynamic cut-through, low-temperature properties, flame retardancy, etc. It is known that the coating layer of electric wires and cables is based on a highly crystalline polymer (such as high-density polyethylene (HDPE)) to achieve high abrasion resistance. However, because such polymers have low filler acceptability, the only way to impart flame retardancy is to use halogen-based flame retardants or phosphorus-based flame retardants such as red phosphorus, which are effective in flame retardancy with only a small amount of addition.

[0003] However, the use of halogen-based flame retardants generates halogen gases during combustion, which is a serious environmental issue worldwide. The use of phosphorus-based flame retardants, such as red phosphorus, also generates phosphine during combustion and phosphoric acid during disposal, which can contaminate groundwater veins.

[0004] On the other hand, metal hydroxides used as flame retardants do not cause the problems mentioned above compared to halogen-based flame retardants or phosphorus-based flame retardants, but they require high loadings, which can lead to problems such as deterioration of mechanical properties and low-temperature properties, as well as reduced electrical properties.

[0005] To address these problems, flame-retardant resin compositions based on high-density polyethylene (HDPE) and containing metal hydroxides as flame retardants are known (see, for example, Patent Document 1). However, when using such flame-retardant resin compositions, in order to achieve high electrical properties, it is necessary to form a wire with a two-layer structure, with an inner layer being a resin composition containing a small amount of metal hydroxide. In other words, if this resin composition is used to form a wire with a single layer structure, it will be impossible to obtain high electrical properties.

[0006] Meanwhile, for electric wires for railway vehicles, there is a dynamic cut-through test in which an edge is pressed against the electric wire and the load applied until a short circuit occurs is measured. Although this test can provide good characteristics for the electric wire described in Patent Document 1, there are limitations on the conductors that can be used to obtain such good characteristics. Specifically, during the dynamic cut-through test, the twist of the conductor strands breaks, increasing the contact area with the edge, and stress is relieved, resulting in a high short-circuit load. Therefore, any conductor that can be deformed in this way can be used. On the other hand, in the case of a conductor that is difficult to deform (for example, a conductor configuration in which the strands do not break), the short-circuit load decreases due to stress concentration between the edge and the conductor, making it difficult to obtain sufficient dynamic cut-through characteristics. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-54283 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a flame-retardant electric wire that has a halogen-free coating layer and has high dynamic cut-through characteristics, and is capable of maintaining high flame retardancy and excellent electrical properties even when using a conductor that is difficult to deform. [Means for solving the problem]

[0009] An insulated wire according to one embodiment includes a conductor and a single-layer flame-retardant insulating layer provided on the conductor, wherein the flame-retardant insulating layer is made of a resin material containing a polymer component and a metal hydroxide, the polymer component including high-density polyethylene, maleic anhydride-modified high-density polyethylene, an ethylene-acrylic acid ester-maleic anhydride terpolymer, an ethylene-α-polyolefin modified with maleic anhydride, and an ethylene-acrylic acid ester copolymer, and the metal hydroxide has a specific surface area of ​​8 to 11 m as measured by a BET method.2 / g, and the average particle size of the metal hydroxide is 0.6 to 1.5 μm, and the average particle size is the particle size at an integrated value of 50% in the particle size distribution determined by a laser diffraction / scattering method. [Effects of the Invention]

[0010] According to a representative embodiment, an insulated wire can be obtained that is halogen-free, yet has high dynamic cut-through properties, and combines flame retardancy and electrical properties. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a structural example of an insulated wire according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0013] [Insulated wire] FIG. 1 is a cross-sectional view showing an example of the structure of an insulated wire according to an embodiment.

[0014] 1 includes a conductor 11a and a flame-retardant insulating layer 11b covering the conductor 11a. The insulated wire 11 is an insulated wire with a single-layer flame-retardant insulating layer. As will be described later, the flame-retardant insulating layer 11b is made of a cross-linked polymer material, and the insulated wire 11 can also be called a single-layer cross-linked flame-retardant insulated wire.

[0015] The features of the insulated wire 11 will be described below.

[0016] <Flame-retardant insulating layer> The flame-retardant insulating layer 11b, which is the coating layer for the conductor 11a, is a single-layer resin layer (flame-retardant insulating layer) composed of a material containing a specific polymer material. While FIG. 1 shows an example in which the flame-retardant insulating layer 11b is provided directly on the conductor 11a, it may also be provided indirectly via another layer. This polymer material can be obtained by using a resin composition containing a specific polymer component and a metal hydroxide, and curing it through a crosslinking reaction, as described below. The polymer component and metal hydroxide used here will be described in detail below.

[0017] (polymer component) The polymer components are raw materials for forming the flame-retardant insulating layer 11b and include high-density polyethylene, maleic anhydride-modified high-density polyethylene, ethylene-acrylic ester-maleic anhydride terpolymer, maleic anhydride-modified ethylene-α-polyolefin, and ethylene-acrylic ester copolymer. Each component will be described below.

[0018] [High-density polyethylene (HDPE)] The high-density polyethylene (HDPE; hereafter referred to simply as "HDPE") used here is a synthetic resin belonging to the crystalline thermoplastic resin category, in which the repeating unit ethylene is bonded in a linear chain with almost no branching, and is polyethylene with a density of 0.942 or higher. There are no particular restrictions on the melting point, density, or molecular weight of this HDPE. HDPE is an essential component for improving mechanical properties (especially dynamic cut-through), and is also a necessary component for controlling viscosity during wire extrusion molding.

[0019] The amount of HDPE added is preferably 5 to 35 mass % and more preferably 5 to 20 mass % of 100 mass % of the polymer component.

[0020] [Maleic anhydride-modified high-density polyethylene (maleic anhydride-modified HDPE)] The maleic anhydride-modified high-density polyethylene (maleic anhydride-modified HDPE) used here is a compound obtained by modifying HDPE with maleic anhydride, and its melting point, density, and molecular weight are not particularly limited. This maleic anhydride-modified HDPE is preferably modified HDPE with 0.5 to 1.5 mass% maleic anhydride grafted. This component is necessary to ensure electrical properties. However, adding too much can cause the flame-retardant insulation layer to become very rough in appearance, reduce the insulation thickness, and conversely, degrade the electrical properties.

[0021] The amount of maleic anhydride modified HDPE added is preferably 10 to 40 mass %, more preferably 20 to 30 mass %, of 100 mass % of the polymer component.

[0022] [Ethylene-acrylic ester-maleic anhydride terpolymer] The ethylene-acrylic acid ester-maleic anhydride terpolymer used here is a copolymer with ethylene as the base component, obtained by copolymerizing three raw materials: ethylene, acrylic acid ester, and maleic anhydride.

[0023] This ethylene-acrylic acid ester-maleic anhydride terpolymer contains a larger amount of maleic anhydride than a maleic anhydride graft copolymer, and therefore has stronger adhesion to the filler and can improve mechanical strength, making it particularly effective in imparting abrasion resistance to flame-retardant insulating layers.

[0024] Examples of ethylene-acrylic acid ester-maleic anhydride terpolymers include ethylene-methyl acrylate-maleic anhydride terpolymer, ethylene-ethyl acrylate-maleic anhydride terpolymer, ethylene-butyl acrylate-maleic anhydride terpolymer, etc. These ethylene-acrylic acid ester-maleic anhydride terpolymers can be used alone or in combination of two or more.

[0025] In the ethylene-acrylic acid ester-maleic anhydride terpolymer, the amount of acrylic acid ester and the amount of maleic anhydride are not particularly limited, but from the viewpoint of adhesion to the filler, the amount of acrylic acid ester is preferably in the range of 5 to 30 mass % and the amount of maleic anhydride is preferably in the range of 2.8 to 3.6 mass %.

[0026] The amount of ethylene-acrylic acid ester-maleic anhydride terpolymer added is preferably 30 to 50% by mass of 100% by mass of the polymer component. If the amount of ethylene-acrylic acid ester-maleic anhydride terpolymer added is less than 30% by mass, abrasion resistance tends to decrease, and if it is more than 50% by mass, elongation tends to decrease.

[0027] [Maleic anhydride modified ethylene-α-polyolefin] The maleic anhydride-modified ethylene-α-polyolefin used here is a compound in which an ethylene-α-polyolefin copolymer is modified with maleic anhydride. Ethylene-α-polyolefins have excellent flexibility in low-temperature environments, and when modified with maleic anhydride, it is possible to strengthen the adhesion to fillers such as magnesium hydroxide. Therefore, by blending this maleic anhydride-modified ethylene-α-polyolefin, the low-temperature properties of the flame-retardant insulation layer can be improved.

[0028] Preferred examples of ethylene-α-polyolefins include copolymers of ethylene and an α-olefin having 3 to 12 carbon atoms, and examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methylpentene, 1-heptene, 1-octene, etc. These α-olefins can be used alone or in combination of two or more, and among these, 1-butene is preferred.

[0029] Although not particularly limited, ethylene-α-polyolefins modified with maleic anhydride having a glass transition temperature of lower than −55° C. are preferred.

[0030] The amount of maleic anhydride-modified ethylene-α-polyolefin added is preferably 5 to 20% by mass of 100% by mass of the polymer component. If the amount is less than 5% by mass, the low-temperature properties tend to deteriorate, and if it is more than 20% by mass, the dynamic cut-through properties tend to deteriorate.

[0031] [Ethylene-acrylic acid ester copolymer] The ethylene-acrylic acid ester copolymer used here is a copolymer obtained by polymerizing ethylene and acrylic acid ester, and has high filler acceptability and the effect of forming a charred layer upon combustion. It also functions to improve the dispersibility of the maleic anhydride-modified polymer species and metal hydroxide. Examples of ethylene-acrylic acid ester copolymers include ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-butyl acrylate copolymer. These can be used alone or in combination of two or more.

[0032] In the ethylene-ethyl acrylate copolymer, the amount of acrylic acid ester is preferably relatively large, preferably 10 to 30 mass %, from the viewpoint of filler acceptance.Moreover, methyl acrylate is suitable as the acrylic acid ester species.

[0033] The amount of ethylene-ethyl acrylate copolymer added is preferably 10 to 30% by mass of 100% by mass of the polymer component. If the amount added is less than 10% by mass, the elongation of the flame-retardant insulation layer tends to be low, and if it is more than 30% by mass, the abrasion resistance of the flame-retardant insulation layer tends to be reduced.

[0034] It is preferable not to contain ethylene vinyl acetate copolymer because a deacetylation reaction occurs in a high temperature environment, resulting in a significant deterioration in physical properties.

[0035] In this embodiment, the polymer component contains the above five components as essential ingredients. While the mechanism of this embodiment is unclear, it is composed of polymers with different filler acceptabilities (HDPE, maleic anhydride-modified HDPE, and ethylene-acrylic ester copolymer) and polymers with different filler interface adhesion and low-temperature properties (ethylene-acrylic ester-maleic anhydride terpolymer and maleic anhydride-modified ethylene-α-polyolefin). This is thought to enhance filler acceptability and improve dynamic cut-through and low-temperature properties by being compatible with the maleic anhydride-modified ethylene-α-polyolefin, while the ethylene-acrylic ester copolymer is thought to improve electrical properties by strengthening the filler interface by being compatible with the ethylene-acrylic ester-maleic anhydride terpolymer. This is thought to enable a high level of balance between mechanical and electrical properties in addition to flame retardancy.

[0036] (metal hydroxide) The metal hydroxide is a flame retardant that imparts flame retardancy to the flame-retardant insulating layer 11b, and any metal hydroxide known as a flame retardant can be used without particular limitation. Examples of such metal hydroxides include magnesium hydroxide and calcium hydroxide. Among them, magnesium hydroxide is preferred because the main dehydration reaction temperature is as high as 350°C, and this improves the flame retardancy of the flame-retardant insulating layer 11b.

[0037] The metal hydroxide is added in particulate form, and the particle size is preferably small. For example, it is preferable to use particles with an average particle size D50 in the range of 0.6 to 1.5 μm. In this specification, the average particle size refers to the particle size at 50% of the cumulative value in the particle size distribution determined by laser diffraction / scattering.

[0038] Furthermore, if the specific surface area of ​​the metal hydroxide particles is large, a reinforcing effect as a resin composition is expected, and high dynamic cut-through properties can be obtained. Specifically, when the specific surface area by the BET method is 8 to 11 m, 2 / g.2 If it is less than 11m / g, sufficient strength may not be obtained. 2 If it is greater than 1 / g, the viscosity of the material may become too high, making molding difficult.

[0039] Taking dispersibility into consideration, this metal hydroxide can be surface-treated with a silane coupling agent, a titanate coupling agent, a fatty acid such as stearic acid, or the like, either alone or in combination. To impart high heat resistance, surface treatment with a silane coupling agent is preferred. The amount of this surface treatment agent added is preferably 140 to 200 parts by mass, more preferably 150 to 180 parts by mass, per 100 parts by mass of the polymer component. If the amount added is less than 140 parts by mass, flame retardancy may be insufficient, while if it is more than 200 parts by mass, electrical properties tend to deteriorate.

[0040] In addition to the above components, other components may be added as needed. Examples of such other components include metal soaps, silicone processing aids, and metal chelating agents. These additional components will be described below.

[0041] (Metal soap and silicone processing aids) Metal soaps and silicone processing aids can be added to prevent scum from forming in the die and nipple during extrusion. These components can be used alone or in combination. Multiple types of metal soaps and silicone processing aids can also be used.

[0042] The higher the melting point of the metal soap, the better the effect tends to be, and therefore the melting point is preferably 140°C or higher, and more preferably 220°C or higher. Specific examples of this metal soap include magnesium stearate such as EM-112 and EM-144 (product names, manufactured by Katsuta Chemical Industry Co., Ltd.), and magnesium 12-hydroxystearate such as EMS-6 and EMS-6P (product names, manufactured by Katsuta Chemical Industry Co., Ltd.).

[0043] Examples of silicone processing aids include organopolysiloxanes, such as dimethylpolysiloxane, methylvinylpolysiloxane, and methylphenylpolysiloxane, as well as modified polysiloxanes having functional groups such as vinyl groups at their terminals.

[0044] Silicone-based processing aids have excellent long-length stability, but adding too much tends to reduce mechanical properties. Furthermore, because metal soaps and silicone-based processing aids are flammable, adding too much can reduce flame retardancy. Therefore, the total amount of these components is preferably 10 parts by mass or less per 100 parts by mass of the polymer component. If the amount added exceeds 10 parts by mass, sufficient flame retardancy may not be achieved.

[0045] (metal chelating agent) The metal chelating agent is a component that suppresses thermal degradation of the flame-retardant insulating layer, and is not particularly limited. The flame-retardant insulating layer of this embodiment has a single-layer structure and is disposed on a conductor. In particular, when the flame-retardant insulating layer is disposed directly on the conductor and in direct contact with the conductor, it is exposed to a high-temperature environment, and there is a risk that the catalytic action of metal ions such as copper ions diffused into the flame-retardant insulating layer may accelerate thermal degradation. However, the metal chelating agent can suppress this.

[0046] Preferred examples of the metal chelating agent include hydrazide compounds and salicylic acid derivatives.

[0047] The amount of metal chelating agent added is preferably 1 to 10 parts by mass per 100 parts by mass of the polymer component. If the amount added is less than 1 part by mass, the flame-retardant insulation layer may not be able to sufficiently suppress thermal degradation, while if it exceeds 10 parts by mass, the dispersibility of the metal chelating agent may be poor, causing particles to form and resulting in cracking when bent at low temperatures.

[0048] In addition to the above, the resin composition may further contain other additive components as needed, such as a crosslinking agent, a crosslinking aid, a flame retardant aid, an ultraviolet absorber, a light stabilizer, a softener, a lubricant, a colorant, a reinforcing agent, a surfactant, an inorganic filler, a plasticizer, a metal chelating agent, a foaming agent, a compatibilizer, a processing aid, and a stabilizer.

[0049] After coating the conductor with the resin composition described above, the resin composition is subjected to a cross-linking treatment to form a flame-retardant insulating layer 11b as an outer layer on the insulated wire 11, which makes it possible to suppress dripping (the phenomenon in which part of the resin composition melts off) when the wire burns.

[0050] Crosslinking treatments include chemical crosslinking using organic peroxides, silane compounds, etc., irradiation crosslinking using energy beams such as electron beams or radioactive rays, and other crosslinking methods that utilize chemical reactions, and any of these crosslinking methods can be applied. However, chemical crosslinking carries the risk of scorching. Irradiation crosslinking is preferred because it can be carried out near room temperature, is easy to process, and has the advantage of not changing the glass transition temperature or melting temperature of the polymer crystals before and after the crosslinking treatment.

[0051] <conductor> The conductor used in this embodiment is a stranded wire made by twisting together a plurality of strands. Any known conductor used for electric wires can be used as this conductor, without any particular limitations. Among these, a conductor that is less likely to deform due to collapse of the strands, such as a compressed conductor, is preferred, as it is more likely to achieve the desired effect of this embodiment in a dynamic cut-through test or the like.

[0052] Specifically, the diameter of the stranded wire (conductor) is 0.80 to 0.95 mm or the nominal cross-sectional area is 0.5 mm. 2 In the case of wire pitch of 11 mm or less, diameter of 1.00 to 1.15 mm or nominal cross-sectional area of ​​0.75 mm 2 In the case of wire pitch of 15 mm or less, diameter of 1.10 to 1.30 mm or nominal cross-sectional area of ​​1.0 mm 2In this case, the wire pitch is 15 mm or less, the diameter is 1.45 to 1.65 mm, or the nominal cross-sectional area is 1.5 mm. 2 In this case, the wire pitch is 16 mm or less, the diameter is 1.85 to 2.15 mm, or the nominal cross-sectional area is 2.5 mm. 2 In this case, the effect is easily exhibited when the wire pitch is 20 mm or less. Preferably, the diameter of the stranded wire is 0.80 to 0.95 mm or the nominal cross-sectional area is 0.5 mm. 2 In this case, the wire pitch is 7 to 11 mm, the diameter is 1.00 to 1.15 mm, or the nominal cross-sectional area is 0.75 mm. 2 11 to 15 mm, diameter 1.10 to 1.30 mm or nominal cross-sectional area 1.0 mm 2 11 to 15 mm, diameter 1.45 to 1.65 mm or nominal cross-sectional area 1.5 mm 2 12 to 16 mm, diameter 1.85 to 2.15 mm or nominal cross-sectional area 2.5 mm 2 In this case, it is 16 to 20 mm.

[0053] If the pitch is increased beyond the above range, there is a concern that the conductor may become frayed, resulting in stray wires, which may result in a reduction in the insulation thickness and a deterioration in electrical properties. Also, if the pitch distance is too small, the flexibility may be low and handling may be impaired.

[0054] Furthermore, if the conductor is not compressed into a strand of multiple strands, sufficient dynamic cut-through characteristics can be obtained, but in this case, there is a risk of deterioration in electrical characteristics due to the occurrence of stray wires. [Example] First, a tin-plated conductor was prepared as the conductor 11a, in which a plurality of tin-plated copper wires were twisted together. The diameter of the wires used here was 0.18 mm.

[0055] Next, resin compositions were prepared according to the formulations (parts by mass) shown in Tables 1 to 3, kneaded in a 25 L kneader, and pelletized in a granulator. The resulting pellets were used to coat the conductor in a 40 mm extruder so that the insulating layer had a thickness of 0.26 mm and had the composition shown in Tables 1 to 3. The resulting coated wire was irradiated with a 10 Mrad electron beam for crosslinking, yielding an insulated wire 11 coated with a single layer having the configuration shown in FIG. 1.

[0056] Table 1 shows Examples 1 to 11, Table 2 shows Examples 12 to 21, and Table 3 shows Comparative Examples 1 to 7, respectively.

[0057] <Evaluation> Furthermore, the single-layer insulated wire 11 obtained in each example was evaluated for the following properties, and the results are shown in Tables 1 to 3. [Low temperature test] For the low-temperature test, single-layer insulated wires were left in a -40°C low-temperature chamber for four hours or more and then wound six times around mandrels of 5.6 mm and 7.0 mm diameters. Wires that did not crack when wound around the 5.6 mm diameter mandrel were marked with a ◎, those that cracked at both the 5.6 mm diameter and 7.0 mm diameter mandrels were marked with a ○, and those that cracked at both the 5.6 mm diameter and 7.0 mm diameter mandrels were marked with an ×. [Heat aging test] For the heat aging test, single-layer insulated wires were left in an aging tester at 180°C for 100 hours and 168 hours, and then wound six times around a 5.6 mm diameter (φ5.6 mm) mandrel. Wires that did not crack after 168 hours were marked with a ◎, those that cracked after 168 hours and did not crack after 100 hours were marked with a ○, and those that cracked after 100 hours were marked with an ×.

[0058] [Flame retardancy test] To evaluate flame retardancy, 37 wires were twisted together and held vertically in 14 rows in accordance with European standard EN50305.9.1.2. The wires were irradiated with a flame from a burner for 20 minutes, after which the char length was measured. Char lengths of less than 1 m were marked with ◎, those between 1 m and 1.5 m with ○, and those over 1.5 m with ×. [Dynamic Cut-Through] Dynamic cut-through characteristics were evaluated in accordance with the European standard EN50305.5.6. 2 In this case, if the load is 90N or more, it is marked as ◎, if it is 80N or more, it is marked as 〇, and if it is less than 80N, it is marked as ×. 2 In this case, if the load is 120N or more, it is marked as ◎, if it is less than 120N and 100N or more, it is marked as ○, and if it is less than 100N, it is marked as ×. 2 In this case, if the load was 140N or more, it was marked as ◎; if it was less than 140N but 120N or more, it was marked as 〇; if it was less than 120N, it was marked as ×.

[0059] [Wire workability] For the wire workability evaluation, 1000m of wire was extruded and either no die scatter or, if die scatter occurred, could be blown away with air, and the wire had no abnormalities in appearance or no nipple scatter, given an ◎; no die scatter or, if die scatter occurred, could be blown away with air, and the wire had no abnormalities in appearance but a small amount of scatter due to nipple scatter, given an ◯; nodules due to nipple scatter occurred and no short circuit occurred for more than 240 hours in the electrical test described below, given an △; nodules due to nipple scatter occurred and a short circuit occurred in less than 240 hours in the electrical test described below, or the wire had a severely rough appearance, given an ×. [Electrical test (DC stability short circuit time)] Electrical testing was carried out in accordance with the European standard EN50305.6.7, and a 300V DC stability test was carried out. Tests that did not short-circuit for 300 hours were marked with a ◎, those that short-circuited for 240 to 300 hours were marked with a ○, and those that short-circuited for less than 240 hours were marked with an ×. [comprehensive evaluation] In the above test method, the overall evaluation was as follows: ◎ if all the evaluations were ⊚ or ◯, ◯ if some of the evaluations were △, and × if some of the evaluations were ×.

[0060] [Table 1]

[0061] [Table 2]

[0062] [Table 3]

[0063] The resin compositions in each example were prepared as follows.

[0064] (Examples 1 to 11) 10 or 30 parts by mass of HDPE (Hi-Zex 5305E, manufactured by Prime Polymer), 5 or 25 parts by mass of maleic anhydride-modified HDPE (Fusabond E265, manufactured by Dipont), 30 parts by mass of ethylene-ethyl acrylate-maleic anhydride terpolymer (Bondine LX4110, manufactured by Arkema; ​​maleic anhydride content 3% by mass, acrylic acid ester content 5% by mass), 10 parts by mass of maleic anhydride-modified ethylene-α-olefin (Tafuma MH7020, manufactured by Mitsui Chemicals; glass transition temperature -55°C), 25 parts by mass of ethylene-ethyl acrylate copolymer (Elbaloy 1125AC, manufactured by DuPont; acrylic acid ester content 25% by mass), magnesium hydroxide (Magnifin H10A, manufactured by Huber; BET 10m 2 A resin composition was obtained by kneading 140 to 200 parts by mass of PEG-140 / g), 2 parts by mass of Irganox 1010 manufactured by BASF as an antioxidant, 8 parts by mass of TMPT (trimethylolpropane trimethacrylate) manufactured by Shin-Nakamura Chemical as a crosslinking aid, 0 to 1 part by mass of zinc stearate (manufactured by Sakai Chemical Industry; melting point 120°C) as metal soap 1, 0 to 4 parts by mass of magnesium 12-hydroxystearate (manufactured by Katsuta Chemical Industry; melting point 220°C) as metal soap 2, 0 to 5 parts by mass of silicone 1 (manufactured by Evonik, V-Si4042), 0 to 3 parts by mass of silicone 2 (manufactured by Shin-Etsu Chemical, KE76S), and 1 to 10 parts by mass of a metal chelating agent (manufactured by Adeka, CDA-6).

[0065] Examples 12 to 21 10 parts by mass of HDPE (Hi-Zex 5305E, manufactured by Prime Polymer), 25 parts by mass of maleic anhydride-modified HDPE (Fusabond E265, manufactured by Dipont), 30 parts by mass of ethylene-ethyl acrylate-maleic anhydride terpolymer (Bondine LX4110, manufactured by Arkema; ​​maleic anhydride content 3% by mass, acrylic acid ester content 5% by mass), 10 parts by mass of maleic anhydride-modified ethylene-α-olefin (Tafuma MH7020, manufactured by Mitsui Chemicals; glass transition temperature -55°C), 25 parts by mass of ethylene-ethyl acrylate copolymer (Elbaloy 1125AC, manufactured by Japan Polyethylene; acrylic acid ester content 25% by mass), magnesium hydroxide (Magnifin H10A, manufactured by Huber; BET 10m 2 A resin composition was obtained by kneading 150 parts by mass of 12-hydroxystearate (manufactured by Katsuta Chemical Industry Co., Ltd.; melting point: 220°C) as metal soap 2, 3 parts by mass of silicone 1 (manufactured by Evonik; V-Si4042), and 4 parts by mass of metal chelating agent (manufactured by Adeka Chemical Co., Ltd.; CDA-6).

[0066] (Comparative Examples 1 to 7) The insulating layer contained 10 parts by mass of HDPE (Hi-Zex 5305E manufactured by Prime Polymer), 25 parts by mass of maleic anhydride-modified HDPE (Fusabond E265 manufactured by DuPont), 30 parts by mass of ethylene-ethyl acrylate-maleic anhydride terpolymer (Bondine LX4110 manufactured by Arkema; ​​maleic anhydride content 3% by mass, acrylic acid ester content 5% by mass), 10 parts by mass of maleic anhydride-modified ethylene-α-olefin (Tafuma MH7020 manufactured by Mitsui Chemicals; glass transition temperature -55°C), 25 parts by mass of ethylene-ethyl acrylate copolymer (Elbaloy 1125AC manufactured by Japan Polyethylene; acrylic acid ester content 25% by mass), magnesium hydroxide (Kisuma 5L manufactured by Kyowa Chemical Co., Ltd.; BET 5m 2A resin composition was obtained by kneading 150 parts by mass of 12-hydroxystearate (manufactured by Katsuta Chemical Industry Co., Ltd.; melting point: 220°C) as metal soap 2, 3 parts by mass of silicone 1 (manufactured by Evonik; V-Si4042), and 4 parts by mass of metal chelating agent (manufactured by Adeka Chemical Co., Ltd.; CDA-6).

[0067] In Examples 1 to 5 and 7 to 10 shown in Table 1, all evaluations were rated as ◎ or ○, and therefore the overall evaluation was rated as ◎. In Examples 6 and 11, only the wire processability was rated as △, and the other evaluations were rated as ◎ or ○, so the overall evaluation was rated as ○.

[0068] In Examples 12 to 21 shown in Table 2, all evaluations were rated as ⊚ or ◯, and therefore the overall evaluation was ⊚.

[0069] In Comparative Examples 1 to 7 shown in Table 3, the specific surface area of ​​the magnesium hydroxide used was small, and the dynamic cut-through properties were poor, so the overall evaluation was poor.

[0070] From the above results, it was found that the dynamic cut-through property deteriorates as the specific surface area of ​​the metal hydroxide, which is a flame retardant, decreases.

[0071] Although the present invention has been described with reference to the above embodiments and examples, the present invention is not limited to the above embodiments and examples and can be modified in various ways without departing from the spirit of the present invention. [Industrial Applicability]

[0072] The present invention is applicable to wires and cables. [Explanation of symbols]

[0073] 11 Insulated wire 11a conductor 11b Flame-retardant insulating layer

Claims

1. An insulated wire having a conductor and a single-layer flame-retardant insulating layer provided on the conductor, the flame-retardant insulating layer is made of a resin material containing a polymer component and a metal hydroxide, The polymer component includes high density polyethylene, maleic anhydride modified high density polyethylene, ethylene-acrylic acid ester-maleic anhydride terpolymer, maleic anhydride modified ethylene-α-polyolefin, ethylene-acrylic acid ester copolymer, Including, The metal hydroxide has a specific surface area of ​​8 to 11 m2 as measured by the BET method. ２ / g, The average particle size of the metal hydroxide is 0.6 to 1.5 μm, The insulated wire, wherein the average particle size is a particle size at 50% of the integrated value in a particle size distribution determined by a laser diffraction / scattering method.

2. The insulated wire according to claim 1, An insulated wire using a compressed conductor as the conductor.

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