JP5182580B2 - Halogen-free flame retardant insulated wire - Google Patents

Description

  The present invention relates to a halogen-free flame-retardant insulated wire used for wiring in electronic equipment such as a liquid crystal television, a copying machine, and a computer.

  In a liquid crystal panel such as a liquid crystal television, a mobile phone, a digital camera, and a personal computer, a light source (backlight) is usually installed behind the liquid crystal panel, and transmitted light from the light source is used for display. A cold cathode tube or the like is used as a light source of the backlight, and a high frequency, high voltage current generated by a lighting circuit (boost circuit) is supplied to the cold cathode tube. Since the frequency and voltage of the power supplied to the cold cathode tubes are increasing, it is necessary to reduce the leakage current in the insulated wires used to supply the above high frequency and high voltage currents to the cold cathode tubes. Therefore, reduction of the dielectric constant of the insulating layer is required.

  On the other hand, as the liquid crystal panel becomes thinner, the wiring space becomes narrower, and the above-described insulated wire is required to have a reduced diameter and flexibility. On the other hand, electric wires such as insulated wires and insulated cables used for in-machine wiring of electronic devices are generally required to have various characteristics conforming to UL (Underwriters Laboratories Inc.) standards. The UL standard stipulates in detail various properties such as flame retardancy, heat deformability, low temperature properties, tensile properties after heat aging of coating materials, and the like to be satisfied by products. Among these, regarding flame retardancy, it is necessary to pass a vertical combustion test called a VW-1 test, which is one of the strictest requirements in the UL standard.

  As an insulated wire used for such applications, Patent Document 1 discloses an insulating layer comprising a flame retardant resin composition containing ultra-low density polyethylene polymerized with a single-site type metallocene catalyst, a halogen-based flame retardant, and zinc white. An insulated wire used as is disclosed. The dielectric constant of the flame retardant resin composition used for the insulating layer is as low as less than 3.3, and the leakage current of high frequency / high voltage current can be reduced even if the thickness of the insulating layer is reduced.

  On the other hand, in order to meet the demand for reducing the environmental burden, a halogen-free insulated wire that does not contain a halogen element is required. This is because when the insulated wire contains a halogen element, a toxic gas such as hydrogen chloride may be generated when the insulated wire after use is incinerated.

Generally, as a coating material for halogen-free electric wires, a resin composition that is flame-retardant by blending a polyolefin-based resin such as polypropylene with a metal hydroxide such as magnesium hydroxide or aluminum hydroxide is used. For example, Patent Document 2 discloses an insulated wire using a flame retardant resin composition in which magnesium hydroxide is blended as a flame retardant in an ethylene-vinyl acetate copolymer (EVA) as an insulating layer. However, in order to pass the vertical combustion test VW-1, it is necessary to mix a large amount of metal hydroxide in the polyolefin resin. As a result, the dielectric constant of the insulating layer increases, and the leakage current increases in high frequency and high voltage applications. There is also the problem of reduced flexibility.
Japanese Patent No. 3279206 JP 2000-211981

As described above, in a flame retardant resin composition using a metal hydroxide as a non-halogen flame retardant, increasing the compounding amount of the metal hydroxide to satisfy the flame retardancy increases the dielectric constant and increases the leakage current. Become. On the other hand, if the compounding amount of the metal hydroxide is reduced in order to lower the dielectric constant, the flame retardancy cannot be satisfied.
In view of these circumstances, the present invention provides a halogen-free flame-retardant insulated electric wire that can reduce leakage current at high frequency and high voltage, satisfy the required characteristics of flame retardancy and flexibility, and help reduce environmental load. This is the issue.

The present invention relates to a halogen-free flame-retardant insulated electric wire having a conductor, a first insulating layer covering the conductor, and a second insulating layer covering the first insulating layer, the first insulating layer comprising a polyester resin 20 to 50 parts by mass, 20 to 50 parts by mass of a polyphenylene ether resin, and 100 parts by mass of a resin component composed of 30 to 60 parts by mass of a styrene elastomer: polyolefin resin ratio of 0: 100 to 100: 0 On the other hand, it comprises a first resin composition containing 5-70 parts by mass of a nitrogen-based flame retardant and having a dielectric constant of 3.2 or less, and the second insulating layer is composed of 100 parts by mass of an ethylene vinyl acetate copolymer. On the other hand, it is a halogen-free flame-retardant insulated electric wire comprising the second resin composition containing 150 to 250 parts by mass of a metal hydroxide (claim 1).

  In order to reduce the leakage current, it is necessary to lower the dielectric constant of the insulating layer, but it has been found that the use of a low dielectric constant material for the inner layer portion in contact with the conductor is effective in reducing the leakage current. . Therefore, the first resin composition having a dielectric constant of 3.2 or less is used for the first insulating layer in contact with the conductor. The first resin composition has a certain degree of flame retardancy due to the synergistic effect of polyphenylene ether, nitrogen-based flame retardant, and polyester resin.

  On the other hand, for the second insulating layer on the outer side, a second resin composition containing metal hydroxide having a high flame retardant effect at a certain ratio is used with emphasis on flame retardancy. Although the dielectric constant of the second resin composition is increased, the leakage current can be reduced by reducing the dielectric constant of the inner layer. By adopting such a configuration, it is possible to achieve both reduction of leakage current at high frequency and high voltage and flame retardancy.

  The first resin composition used as the first insulating layer covering the conductor is a mixture of three components: a polyester resin, a polyphenylene ether resin, and a styrene elastomer / polyolefin resin component. The resin composition containing a polyphenylene ether resin and a styrene elastomer / polyolefin resin component has an elastic modulus and a hard polyphenylene ether resin as an island at room temperature, and a styrene elastomer / polyolefin resin component having a large elongation and the sea as a sea. Presumed to be a polymer alloy with a sea-island structure. If a polyester resin is further added thereto, a three-component polymer alloy is obtained. The polyester resin is a crystalline resin, and can maintain an appropriate elastic modulus and maintain flexibility and extensibility even at a temperature higher than the glass transition temperature. Moreover, if the compatibility with a styrene-type elastomer is comparatively high and it can disperse | distribute uniformly in a styrene-type elastomer, tensile strength and tensile strength will be expressed as a whole. By including a nitrogen-based flame retardant in such a resin component, flexibility can be exhibited, the dielectric constant is low, and a certain degree of flame retardancy can be imparted.

  In addition, the mixing ratio of a styrene-type elastomer and polyolefin resin can be set arbitrarily. Styrenic elastomers may be used alone, or polyolefin resins may be used alone. By mixing the polyolefin resin, the crosslinking efficiency of the resin composition can be increased, and the heat resistance can be improved.

  It is preferable that a styrene elastomer having a functional group is contained as a part of the styrene elastomer (claim 2). Styrenic elastomers with functional groups act as compatibilizers. By adding a compatibilizing agent, the polyester resin and the styrene elastomer or polyolefin resin are mixed well, and the tensile elongation property is improved.

  It is preferable that the first resin composition further contains trimethylolpropane trimethacrylate in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin component. Trimethylolpropane trimethacrylate is a crosslinking aid. By further containing a crosslinking aid, a plasticizing effect of the resin is obtained, and the extrusion processability is improved. Moreover, the crosslinking efficiency at the time of irradiation of ionizing radiation increases. Furthermore, trimethylolpropane trimethacrylate has good compatibility with the resin and can be easily mixed.

  The deflection temperature under load of the polyphenylene ether resin is preferably 95 ° C. or higher. By using a polyphenylene ether resin having a deflection temperature under load of 95 ° C. or higher, an insulating layer having high mechanical strength can be obtained.

  The nitrogen-based flame retardant is preferably melamine cyanurate (Claim 5). By using melamine cyanurate as a nitrogen-based flame retardant, thermal stability during mixing is improved, and flame retardancy is also improved.

  In the halogen-free flame-retardant insulated wire of the present invention, the outer diameter of the conductor is 0.1 mm to 1 mm, and the total thickness of the first insulating layer and the second insulating layer is 0.1 mm to 1 mm. Preferred (claim 6). Such a small-diameter halogen-free flame-retardant insulated wire can be wired in a narrow space.

  The first insulating layer and the second insulating layer are preferably cross-linked by irradiation with ionizing radiation. Since the insulating layer is cross-linked, heat resistance and mechanical strength are improved.

  ADVANTAGE OF THE INVENTION According to this invention, the halogen-free flame-retardant insulated wire which can reduce the leakage current in a high frequency and a high voltage, satisfy | fills the required characteristic of a flame retardance and a softness | flexibility, and is useful for reduction of an environmental load can be provided.

  Polyphenylene ether is an engineering plastic obtained by oxidative polymerization of 2,6-xylenol synthesized using methanol and phenol as raw materials. In order to improve the moldability of polyphenylene ether, various materials are commercially available as modified polyphenylene ether resins in which polystyrene is blended with polyphenylene ether. As the polyphenylene ether resin used in the present invention, any of the above-mentioned polyphenylene ether resin alone and a polyphenylene ether resin obtained by melt blending polystyrene can be used. Moreover, what introduce | transduced carboxylic acid, such as maleic anhydride, can also be blended suitably and used.

In such a polyphenylene ether resin, but the load deflection temperature varies depending on the blending ratio of polystyrene, deflection temperature under load and improved tensile properties of the electric wire coating With more than 95 ° C., and the thermal deformation characteristics Is preferable because it is excellent. The deflection temperature under load is a value measured at a load of 1.80 MPa by the method of ISO75-1,2.

  A polyphenylene ether resin not blended with polystyrene can also be used as the polyphenylene ether resin. In this case, if a low-viscosity polyphenylene ether resin is used, the resin pressure during extrusion can be reduced while maintaining the mechanical strength. The intrinsic viscosity of the polyphenylene ether resin is preferably 0.1 to 0.6 dl / g, and more preferably 0.3 to 0.5 dl / g.

  Styrene elastomers used in the present invention include styrene / ethylene butene / styrene copolymers, styrene / ethylene propylene / styrene copolymers, styrene / ethylene / ethylene propylene / styrene copolymers, styrene / butylene / styrene copolymers. Examples thereof include hydrogenated polymers and partially hydrogenated polymers. Moreover, what introduce | transduced carboxylic acid, such as maleic anhydride, can also be blended suitably and used.

  Among these, use of a block copolymer elastomer of styrene and a rubber component is preferable from the viewpoints of improving extrudability, improving tensile elongation at break, and improving impact resistance. Block copolymers include hydrogenated styrene / butylene / styrene block copolymers, triblock copolymers such as styrene / isobutylene / styrene copolymers, styrene / ethylene copolymers, styrene / ethylene propylene, etc. It is preferable that the triblock component in the styrene elastomer is contained in an amount of 50% by weight or more because the strength and hardness of the electric wire coating is improved.

Also, those having a styrene content of 20% by weight or more contained in the styrene elastomer can be suitably used from the viewpoint of mechanical properties and flame retardancy. When the styrene content is less than 20% by weight, the hardness and extrusion processability are lowered. On the other hand, if the styrene content exceeds 50% by weight, the tensile elongation at break decreases, which is not preferable.
Further, the melt flow rate (abbreviated as “MFR”; measured at 230 ° C. × 2.16 kgf in accordance with JIS K 7210) serving as an index of molecular weight is preferably in the range of 0.8 to 15 g / 10 min. This is because if the melt flow rate is smaller than 0.8 g / 10 min, the extrudability is lowered, and if it exceeds 15 g / 10 min, the mechanical strength is lowered.

  Examples of the polyolefin resin used in the present invention include polyethylene, ultra-low density polyethylene, polypropylene, ethylene vinyl acetate copolymer, ethylene binary or ternary copolymer, and the above-mentioned polymer graft resin, olefin A thermoplastic elastomer etc. can be illustrated. Among these, ultra-low density polyethylene and ethylene vinyl acetate copolymer are preferable because of their excellent flexibility.

  As the polyester resin, a PET (polyethylene terephthalate) resin, a PBT (polybutylene terephthalate) resin, or the like can be used. In particular, PBT resin has a melting point close to the glass transition temperature of polyphenylene ether and has good extrudability. It also has excellent flame retardancy.

  The polyester resin, polyphenylene ether resin, and styrene elastomer / polyolefin resin component can be melt-mixed at an arbitrary ratio. From the viewpoint of extrudability and flexibility of the wire, the polyester resin is the total resin component. 20 to 50 parts by mass, 30 to 60 parts by mass of the styrene elastomer / polyolefin resin component, and 20 to 50 parts by mass of the polyphenylene ether resin. When the content of the polyphenylene ether-based resin exceeds 50 parts by mass, the extrudability decreases, and when the content is less than 20 parts by weight, the mechanical strength and flame retardancy are decreased. Similarly, when the content of the polyester resin exceeds 50 parts by mass, the extrudability is lowered, and when it is less than 20 parts by mass, the mechanical strength and flame retardancy are lowered. The more preferable content of the polyester resin is 25 to 40 parts by mass.

  Further, when a styrene elastomer having a functional group is contained as a part of the styrene elastomer, the adhesion between the polyester resin and the styrene elastomer is improved, and the high temperature characteristics can be improved. Examples of the functional group include an epoxy group, an oxazoline group, an acid anhydride group, and a carboxyl group, which can be appropriately selected according to the type of resin. The content of the styrenic elastomer having a functional group is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the resin component, and more preferably 1 to 10 parts by weight.

  Furthermore, as a resin component, it is possible to mix various resin in the range which does not impair the meaning of this invention.

  Examples of the nitrogen-based flame retardant used in the present invention include melamine resin and melamine cyanurate. Nitrogen-based flame retardants do not generate toxic gases such as hydrogen halides even when incinerated after use, and can reduce the environmental burden. When melamine cyanurate is used as a nitrogen-based flame retardant, it is preferable in terms of heat stability at the time of mixing and a flame retardant improvement effect. Melamine cyanurate can also be used after surface treatment with a silane coupling agent or a titanate coupling agent.

  Content of the said nitrogen-type flame retardant shall be 5-70 mass parts with respect to 100 mass parts of resin compositions. This is because if the amount is less than 5 parts by mass, the flame resistance of the insulated wire is insufficient, and if it exceeds 70 parts by mass, the elongation and extrusion processability are deteriorated. As for content of a nitrogen-type flame retardant, 10-40 mass parts is further more preferable.

  Furthermore, a crosslinking aid can be added to the first resin composition. As the crosslinking aid, a polyfunctional monomer having a plurality of carbon-carbon double bonds in the molecule such as trimethylolpropane trimethacrylate, triallyl cyanurate, triallyl isocyanurate and the like can be preferably used. Moreover, it is preferable that a crosslinking adjuvant is a liquid at normal temperature. This is because it is easy to mix with a polyphenylene ether-based resin, a styrene-based elastomer, or a polyolefin resin when it is liquid. In particular, use of trimethylolpropane trimethacrylate as a crosslinking aid is preferable because compatibility with the resin is improved. In order to improve flame retardancy, a phosphorus-based flame retardant may be added. Examples of the phosphorus-based flame retardant include phosphate esters.

As a resin component used in the second resin composition, it is possible to use ethylene-vinyl acetate copolymer. An ethylene vinyl acetate copolymer can be preferably used from the viewpoints of extrudability and flexibility when a resin composition is used.

  Examples of the metal hydroxide used as the flame retardant include aluminum hydroxide, magnesium hydroxide, calcium hydroxide and the like. Among these, from the viewpoint of extrusion processability, magnesium hydroxide having a particle size in the range of 0.1 to 3 μm is preferable.

  Content of a metal hydroxide shall be 150-250 mass parts with respect to 100 mass parts of resin components. This is because if the amount is less than 150 parts by mass, the flame retardancy of the insulated wire is insufficient, and if the amount exceeds 250 parts by mass, the elongation and extrusion processability are deteriorated. A more preferable range is 150 to 200 parts by mass.

  The first resin composition and the second resin composition include an antioxidant, an anti-aging agent, a lubricant, a processing stabilizer, a colorant, a heavy metal deactivator, a foaming agent, and a polyfunctional monomer as necessary. Etc. can be appropriately mixed. These materials are mixed using a known melt mixer such as a short-shaft extrusion mixer, a pressure kneader, or a Banbury mixer to produce a resin composition.

  In the halogen-free flame retardant insulated wire of the present invention, the conductor is coated with the first insulating layer made of the first resin composition, and the second insulating layer made of the second resin composition is applied to the first insulating layer. It is coated. A known extruder can be used to form the first insulating layer and the second insulating layer. In order to simplify the manufacturing process, it is preferable that the first insulating layer and the second insulating layer are simultaneously coated by extrusion.

  As a conductor, a copper wire, an aluminum wire, etc. which are excellent in electroconductivity can be used. The diameter of the conductor can be appropriately selected according to the intended use, but is preferably 1 mm or less in order to enable wiring in a narrow space. In consideration of ease of handling, the thickness is preferably 0.1 mm or more.

  The thickness of the first insulating layer and the second insulating layer can be appropriately selected according to the conductor diameter, but the total thickness of the entire insulating coating layer including the first insulating layer and the second insulating layer is 0.1 mm. It is preferable to be set to ˜1 mm. The thinner the insulating coating layer, the better the flexibility. However, if the insulating coating layer is too thin, flame retardancy cannot be ensured. The insulated wire of the present invention is excellent in that it can ensure flame retardancy that passes the VW-1 flame retardancy test even if the thickness of the entire insulating layer is reduced.

  Further, it is preferable that the first insulating layer and the second insulating layer are cross-linked by irradiation with ionizing radiation in that the mechanical strength is improved. Examples of ionizing radiation sources include accelerating electron beams, gamma rays, X-rays, α rays, ultraviolet rays, and the like. Lines are most preferably available.

  Next, the best mode for carrying out the invention will be described by way of examples. The examples are not intended to limit the scope of the invention.

[Examples 1 to 14]
(Preparation of resin composition 1)
Each component was melt-mixed according to the formulation shown in Table 1. Using a twin-screw mixer (26 mmφ, L / D = 48), melt-mixed at a cylinder temperature of 230 ° C. and a screw rotation speed of 200 to 400 rpm, melt-extruded into a strand, and then cooled and cut the molten strand to produce pellets. Produced.

(Preparation of resin composition 2)
Each component was mixed according to the formulation shown in Table 2. After using an open roll machine having a diameter of 304.8 mm and mixing at 130 to 160 ° C., the stripped sample was pelletized using a pelletizer.

(Production of insulated wires)
A 30 mmφ extruder and a 25 mmφ extruder were used, and the inner layer material was simultaneously extruded with the 30 mmφ extruder, and the outer layer material was simultaneously coated with the 25 mmφ extruder to produce an insulated wire. As the conductor, 19 tin-plated copper wires (outer diameter 0.64 mm) were used. The thickness of the first insulating layer (inner layer) made of the resin composition 1 was 0.38 mm, and the thickness of the second insulating layer (outer layer) made of the resin composition 2 was 0.10 mm. The extrusion conditions were conductor preheating 60 ° C., cylinder and die temperatures were set to 190-200 ° C., and the line linear velocity was 25 m / min. Each insulated wire was irradiated with an accelerating electron beam so that the irradiation amount was 120 kGray. The insulated wire was evaluated for each of the unirradiated and irradiated ones.

(Evaluation of coating layer: tensile properties)
A conductor was extracted from the produced electric wire, and a tensile test of the coating layer was performed. The test conditions were tensile rate = 500 mm / min, distance between marked lines = 25 mm, temperature = 23 ° C., tensile strength and tensile elongation at break were measured with three samples, and the average value was obtained. A sample having a tensile strength of 10.3 MPa or more and a tensile elongation at break of 150% or more was judged as “pass”.

(Evaluation of coating layer: second modulus)
Using a sample similar to the above tensile test, after performing a tensile test at a tensile rate of 50 mm / min, a distance between marked lines of 25 mm, and a temperature of 23 ° C., the elongation becomes 2% from the stress-elongation curve. The elastic modulus was calculated. The evaluation of the second modulus was performed only with the non-irradiated insulated wire.

(Evaluation of coating layer: dielectric constant, tanD)
The dielectric constant (ε) of the insulation coating of the insulated wire sample was measured by the following method. First, as shown in FIG. 1, in the state where the insulated wire 1 is immersed in the water 3 together with the metal plate 2, the impedance analyzer 4 (4276A LCZ meter made by Yokogawa Hured Packard) is used and the frequency is 1 kHz. Capacitance and tanD were measured. The measured capacitance value was divided by the immersion length L (m) of the insulation coating in water to obtain the capacitance C (pF / m) per 1 m of the insulation coating length. And according to the following formula, the dielectric constant (ε) of the insulating coating was calculated. Here, d1 is a conductor outer diameter, and d2 is an insulation outer diameter.
ε = C × log (d2 / d1) /24.12

(Evaluation of coating layer: residual elongation rate, residual tensile strength rate)
After the insulated wire irradiated with the electron beam was heat-treated under the conditions shown in Table 1, the conductor was extracted and the coating layer was subjected to a tensile test. The measurement conditions are the same as in the above tensile test. With the original value as 100, the residual elongation rate and the residual tensile strength rate were determined.

(Evaluation of insulated wires: Flame resistance test)
Five samples were provided for the VW-1 vertical flame retardant test described in UL Standard 1581, 1080, and how many of them passed were determined. The criterion is that if each sample is ignited 15 seconds 5 times, the fire extinguishes within 60 seconds, the absorbent cotton laid on the bottom is not burned by the burning fallen objects, and the kraft paper attached to the top of the sample burns. Or that does not burn. In addition, the flame retardance test was performed only with the irradiated insulated wire.

(footnote)
(* 1) DURANEX 800FP, melting point 224 ° C, manufactured by Wintech Polymer Co., Ltd.
(* 2) DURANEX 600LP, melting point 170 ° C, manufactured by Wintech Polymer Co., Ltd.
(* 3) Polyphenylene ether with glass transition temperature of 215 ° C manufactured by Mitsubishi Engineering Plastics Co., Ltd.
(* 4) Polystyrene-modified polyphenylene ether with a softening point of 210 ° C and a deflection temperature under load of 125 ° C
(* 5) Polystyrene-modified polyphenylene ether with a softening point of 210 ° C and a deflection temperature under load of 95 ° C
(* 6) Styrene / ethylene / butylene / styrene copolymer, styrene content 30 wt%, melt flow rate 3.5 (200 ° C. × 5 kg)
(* 7) Ethylene vinyl acetate copolymer with 25% vinyl acetate content
(* 8) Ultra low density polyethylene with a density of 0.87 and a melt flow rate of 0.5 (190 ° C x 2.16 kg)
(* 9) Maleic acid-modified styrene / ethylene / butylene / styrene copolymer, styrene content 30 wt%, melt flow rate 4.0 (200 ° C. × 5 kg)
(* 10) Epofriend (registered trademark) AT501 manufactured by Daicel Chemical Industries, Ltd.
(* 11) Nippon Shokubai Co., Ltd. Oxazoline group-containing polymer EPOCROS (registered trademark) RPS1005
(* 12) MC6000 manufactured by Nissan Chemical Industries, Ltd.
(* 13) Irganox1010 manufactured by Ciba Specialty Chemicals Co., Ltd.
(* 14) Sripax O, manufactured by Nippon Kasei Co., Ltd.
(* 15) ADK STAB CDA-1 manufactured by Asahi Denka Kogyo Co., Ltd.
(* 16) Ethylene vinyl acetate copolymer with 70% vinyl acetate
(* 17) Ethylene vinyl acetate copolymer with 32% vinyl acetate
(* 18) Average particle size 0.7μm, stearic acid surface treatment
(* 19) FlammardH manufactured by Nippon Light Metal Co., Ltd.
(* 20) Burgess # 30, manufactured by Shiraishi Calcium Co., Ltd.
(* 21) White Shiraka CCR (stearic acid treatment), manufactured by Shiraishi Calcium Co., Ltd.
(* 22) Sripax E, manufactured by Nippon Kasei Co., Ltd.

  Resin composition 1 used as the inner layer in Examples 1 to 14 had a low dielectric constant of 3.0 or less in any formulation, and exhibited good electrical characteristics. Moreover, the flame retardance also passed the VW-1 combustion test with all the samples. Furthermore, since the tensile elongation is large and the elongation residual ratio after heat aging is large, the flexibility is also good. Moreover, the inner layer and the outer layer can be simultaneously extruded, and the productivity is excellent.

  As an application example of the present invention, there is a wire harness of an internal wiring of an electronic device such as a liquid crystal television, a mobile phone, a digital camera, or a personal computer.

It is a figure explaining the method of measuring the dielectric constant of an insulated wire.

Explanation of symbols

1 Insulated wire 2 Metal plate 3 Water 4 Impedance analyzer L Dipping length of insulation coating in water

Claims (7)

A halogen-free flame-retardant insulated electric wire having a conductor, a first insulating layer covering the conductor, and a second insulating layer covering the first insulating layer,
The first insulating layer includes
100 mass parts of a resin component comprising 20-50 mass parts of a polyester resin, 20-50 mass parts of a polyphenylene ether resin, and 30-60 mass parts of a styrene elastomer: polyolefin resin ratio of 0: 100-100: 0. Containing 5-70 parts by mass of a nitrogen-based flame retardant with respect to parts,
A first resin composition having a dielectric constant of 3.2 or less;
The second insulating layer is
It consists of a second resin composition containing 150 to 250 parts by mass of a metal hydroxide with respect to 100 parts by mass of an ethylene vinyl acetate copolymer ,
Halogen-free flame-retardant insulated wire.   The halogen-free flame-retardant insulated wire according to claim 1, wherein a styrene-based elastomer having a functional group is contained as a part of the styrene-based elastomer.   The halogen-free flame-retardant insulated electric wire according to claim 1 or 2, wherein the first resin composition further contains 0.1 to 10 parts by mass of trimethylolpropane trimethacrylate with respect to 100 parts by mass of the resin component.   The halogen-free flame-retardant insulated wire according to any one of claims 1 to 3, wherein a deflection temperature under load of the polyphenylene ether resin is 95 ° C or higher.   The halogen-free flame-retardant insulated wire according to any one of claims 1 to 4, wherein the nitrogen-based flame retardant is melamine cyanurate. The outer diameter of the conductor is 0.1 mm to 1 mm;
The total thickness of the first insulating layer and the second insulating layer is 0.1 mm to 1 mm.
The halogen-free flame-retardant insulated electric wire according to any one of claims 1 to 5.   The halogen-free flame-retardant insulated electric wire according to any one of claims 1 to 6, wherein the first insulating layer and the second insulating layer are crosslinked by irradiation with ionizing radiation.

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