JPH10340635A - Insulated wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sufficient flame resistance, and improve abrasion resistance and heating deformation resistance by laminating an inner layer composed of a C -α-olefin copolymer and a metallic hydroxide and an outer layer composed of an olefin type resin having specific physical properties and a metallic hydroxide on an outer periphery, and setting the thickness dimension ratio of the inner layer to the outer layer to a range of a specific value. SOLUTION: An outer periphery of a copper conductor 1 is covered with an insulating layer composed of an inner layer 2 and an outer layer 3, and the inner layer 2 is composed of a resin composition by blending a metallic hydroxide by 50 to 400 pts.wt. to 100 pts.wt. of an ethylene-α-olefin copolymer. The outer layer 3 is composed of a resin composition by blending a metallic hydroxide by 0 to 50 pts.wt. to 100 pts.wt. of an olefin type resin having a melting point not less than 100 deg.C and Shore D hardness not less than 50. The thickness dimension ratio of the inner layer 2 to the outer layer 3 is set to the inner layer 2/the outer layer 3=4/6 to 9/1. When a carboxylic acid denatured polyolefine resin is used at the same time as an olefin type resin of the outer layer 3, drip at combustion time can be restrained.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、耐摩耗性、難燃
性、耐加熱変形性等の特性に優れた２層構造の絶縁電線
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-layer insulated wire having excellent properties such as abrasion resistance, flame retardancy, and heat deformation resistance.

【０００２】[0002]

【従来の技術】例えば自動車用の絶縁電線に使用される
絶縁被覆材としては、適度な柔軟性や難燃性の面から、
ポリ塩化ビニル樹脂が従来より多く採用されている。と
ころが、この電線は、車両の廃車処分に伴って焼却廃棄
されると、焼却炉内で絶縁被覆が燃えることから塩化水
素ガスを発生し、焼却炉を傷めたり、大気中に排出され
て環境汚染の原因となるという問題点を有している。2. Description of the Related Art For example, as an insulating covering material used for insulated wires for automobiles, from the viewpoint of appropriate flexibility and flame retardancy,
Polyvinyl chloride resin is used more often than ever. However, when this wire is incinerated and disposed of with the scrapping of vehicles, the insulation coating burns in the incinerator, generating hydrogen chloride gas, damaging the incinerator or being discharged into the atmosphere, resulting in environmental pollution. Has the problem of causing

【０００３】そこで、近年、塩素等のハロゲン成分を含
まない難燃性の樹脂組成物を絶縁被覆材として使用する
電線が研究されており、その構成はポリオレフィン系樹
脂に金属水酸化物を混合したものが一般的である。[0003] Therefore, in recent years, electric wires using a flame-retardant resin composition containing no halogen component such as chlorine as an insulating coating material have been studied, and the structure thereof is a mixture of a polyolefin resin and a metal hydroxide. Things are common.

【０００４】[0004]

【発明が解決しようとする課題】しかしながら、従来の
この種の難燃性樹脂組成物では、ポリ塩化ビニルと比べ
ると柔軟性や屈曲性が劣り、しかも難燃性を与えるため
に多量の金属水酸化物を混合するため、耐摩耗性や引張
強さ等の機械的強度が低下するという問題があった。However, conventional flame-retardant resin compositions of this type are inferior in flexibility and flexibility as compared with polyvinyl chloride, and have a large amount of metallic water to provide flame retardancy. Mixing the oxide has a problem that mechanical strength such as wear resistance and tensile strength is reduced.

【０００５】そこで例えば特開平６−１７６６３１号公
報に示されるように、内層で難燃剤を多量に配合した難
燃オレフィン材料を使用し、外層では難燃剤配合量が少
ないまたは全く含有しないオレフィン樹脂を使用する２
層構造の絶縁電線が考えられている。Therefore, as shown in, for example, Japanese Patent Application Laid-Open No. 6-176631, a flame-retardant olefin material containing a large amount of a flame retardant is used in the inner layer, and an olefin resin containing little or no flame retardant is contained in the outer layer. Use 2
Layered insulated wires have been considered.

【０００６】ところがこのような例では、高温下におい
て絶縁電線が変形し易いという問題があった。However, such an example has a problem that the insulated wire is easily deformed at a high temperature.

【０００７】そこで、本発明の目的は、焼却時に有害ガ
スを発生せず、しかも柔軟性や屈曲性に優れるととも
に、十分な難燃性を備えつつ耐摩耗性や耐加熱変形性に
も優れる絶縁電線を提供するところにある。Accordingly, an object of the present invention is to provide an insulating material which does not generate harmful gas during incineration, has excellent flexibility and bendability, has sufficient flame retardancy, and has excellent wear resistance and heat deformation resistance. To provide the wires.

【０００８】[0008]

【課題を解決するための手段】請求項１の発明に係る絶
縁電線は、導電芯線の外周に内層と外層とからなる絶縁
層を被覆した絶縁電線であって、内層はエチレン−α−
オレフィン共重合体の１００重量部に対して金属水酸化
物を５０〜４００重量部配合してなる樹脂組成物からな
ると共に、外層は融点が１００℃以上かつショアＤ硬さ
が５０以上のオレフィン系樹脂の１００重量部に対して
金属水酸化物を０〜５０重量部配合してなる樹脂組成物
からなり、内層及び外層の厚さ寸法比が内層／外層＝４
／６〜９／１であるところに特徴を有する。The insulated wire according to the first aspect of the present invention is an insulated wire in which the outer periphery of a conductive core is covered with an insulating layer composed of an inner layer and an outer layer, wherein the inner layer is ethylene-α-.
The outer layer is composed of an olefin resin having a melting point of 100 ° C. or higher and a Shore D hardness of 50 or higher, and a resin composition comprising 50 to 400 parts by weight of a metal hydroxide with respect to 100 parts by weight of the olefin copolymer. A resin composition comprising 0 to 50 parts by weight of a metal hydroxide with respect to 100 parts by weight of a resin, wherein the thickness dimension ratio of the inner layer and the outer layer is inner layer / outer layer = 4
/ 6 to 9/1.

【０００９】請求項２の発明に係る絶縁電線は、請求項
１の発明において、外層の樹脂組成物は、カルボン酸変
性オレフィン系樹脂を含むところに特徴を有する。The insulated wire according to the invention of claim 2 is characterized in that, in the invention of claim 1, the resin composition of the outer layer contains a carboxylic acid-modified olefin resin.

【００１０】本発明で使用されるエチレン−α−オレフ
ィン共重合体としては、エチレン−酢酸ビニル共重合
体、エチレン−エチルアクリレート共重合体及びエチレ
ン−メチルメタクリレート共重合体等がある。このよう
な分子内に酸素原子を含むエチレン−α−オレフィン共
重合体は、通常のオレフィン樹脂に比べて本来的に難燃
性が高いから、金属水酸化物の添加量の削減に寄与す
る。また、内層にエチレン−α−オレフィン共重合体を
使用するのは、これ以外の硬い樹脂では柔軟性や耐寒性
が不足するためである。金属水酸化物としては、水酸化
マグネシウム、水酸化アルミニウム、水酸化カルシウム
等が好適である。これらの金属水酸化物の粒径はポリマ
ーへの分散性、作業性、電線特性等の点から平均粒径
０．１〜５μｍのものが好ましいが、この範囲を越えて
も本発明の所期の目的は達成することができる。また、
金属水酸化物の凝集防止、ポリマーへの分散性向上及び
ポリマーへの接着性向上の目的で、シランカップリング
剤、チタネートカップリング剤、脂肪酸及びその金属塩
等を用いて表面処理を施したものを用いることが好まし
い。The ethylene-α-olefin copolymer used in the present invention includes an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer and an ethylene-methyl methacrylate copolymer. Such an ethylene-α-olefin copolymer containing an oxygen atom in the molecule inherently has higher flame retardancy than a normal olefin resin, and thus contributes to a reduction in the amount of metal hydroxide added. Further, the reason why the ethylene-α-olefin copolymer is used for the inner layer is that the other hard resins are insufficient in flexibility and cold resistance. As the metal hydroxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide and the like are preferable. The average particle size of these metal hydroxides is preferably from 0.1 to 5 μm from the viewpoint of dispersibility in a polymer, workability, electric wire characteristics, and the like. The objective of can be achieved. Also,
Surface treated with silane coupling agent, titanate coupling agent, fatty acid and its metal salt for the purpose of preventing aggregation of metal hydroxide, improving dispersibility in polymer and improving adhesion to polymer It is preferable to use

【００１１】またオレフィン系樹脂としては、直鎖状低
密度ポリエチレン、高密度ポリエチレン、ポリプロピレ
ン等がある。これらは融点が１００℃以上かつショアＤ
硬さが５０以上であることが必要である。この数値に満
たないと、耐加熱変形性や耐摩耗性、引張強さが不足す
るからである。[0011] Examples of the olefin resin include linear low-density polyethylene, high-density polyethylene, and polypropylene. These have a melting point of 100 ° C or higher and Shore D
It is necessary that the hardness is 50 or more. If the value is less than this value, heat deformation resistance, wear resistance, and tensile strength are insufficient.

【００１２】内層において、エチレン−α−オレフィン
共重合体１００重量部に対して金属水酸化物を５０〜４
００重量部配合させたが、これは５０重量部以下では電
線の難燃性が不足し、逆に４００重量部以上になると電
線の耐白化性や柔軟性、更に耐摩耗性、引張強さ等が不
足するためである。In the inner layer, 50 to 4 parts by weight of a metal hydroxide is added to 100 parts by weight of the ethylene-α-olefin copolymer.
When the amount is less than 50 parts by weight, the flame retardancy of the wire is insufficient, and when the amount is more than 400 parts by weight, the whitening resistance, flexibility, abrasion resistance, tensile strength and the like of the wire are further reduced. Is not enough.

【００１３】また外層において、オレフィン系樹脂１０
０重量部に対して金属水酸化物を０〜５０重量部配合さ
せたが、これは外層に必要な耐摩耗性や引張り強さ等の
特性を維持しつつ、難燃性をさらに高めるためである。
さらに、難燃性を高めるために、ハイドロタルサイト類
やシリカ、カーボンブラック、ホウ酸亜鉛、リン化合物
等の難燃助剤を添加してもよく、また、酸化防止剤、滑
剤、分散剤、銅害防止剤、架橋剤、架橋助剤或いは着色
剤等を添加してもよく、また、各種の架橋方法にてポリ
マーの架橋を行ってもよい。In the outer layer, the olefin resin 10
0 to 50 parts by weight of the metal hydroxide was added to 0 parts by weight, in order to further enhance the flame retardancy while maintaining the properties such as abrasion resistance and tensile strength required for the outer layer. is there.
Further, in order to enhance the flame retardancy, a flame retardant auxiliary such as hydrotalcites, silica, carbon black, zinc borate, and a phosphorus compound may be added, and an antioxidant, a lubricant, a dispersant, A copper damage inhibitor, a cross-linking agent, a cross-linking assistant or a coloring agent may be added, and the polymer may be cross-linked by various cross-linking methods.

【００１４】内層及び外層の厚さ寸法比を内層／外層＝
４／６〜９／１としたのは、４／６以下では絶縁電線の
柔軟性が不足し、逆に９／１以上では耐摩耗性や引張強
さが不足するためである。The thickness dimension ratio of the inner layer and the outer layer is defined as inner layer / outer layer =
The reason why the ratio is set to 4/6 to 9/1 is that if the ratio is 4/6 or less, the flexibility of the insulated wire is insufficient, and if it is 9/1 or more, the wear resistance and the tensile strength are insufficient.

【００１５】[0015]

【発明の効果】以上述べたように、請求項１の発明の絶
縁電線によれば、分子内に酸素原子を含むエチレン−α
−オレフィン共重合体が通常のポリオレフィン樹脂に比
べて難燃性に優れるから、内層において難燃性を高める
ことができる。これによって外層ではその分、難燃剤と
しての金属水酸化物の配合比率を減少させることが可能
となり、高い難燃性を確保しつつ耐摩耗性や引張強さ等
の機械的強度を高く保持できると共に柔軟性も高いとい
う効果が得られる。また、融点を１００℃以上、ショア
Ｄ硬さが５０以上のオレフィン系樹脂を使用することに
より、耐加熱変形性、耐摩耗性、引張強さがさらに向上
する。As described above, according to the insulated wire of the first aspect of the present invention, ethylene-α containing an oxygen atom in the molecule is used.
-Since the olefin copolymer is more excellent in flame retardancy than the ordinary polyolefin resin, it is possible to enhance the flame retardancy in the inner layer. As a result, in the outer layer, it is possible to reduce the compounding ratio of the metal hydroxide as a flame retardant, and it is possible to maintain high mechanical strength such as abrasion resistance and tensile strength while securing high flame retardancy. In addition, the effect that flexibility is high can be obtained. Further, by using an olefin resin having a melting point of 100 ° C. or more and a Shore D hardness of 50 or more, the heat deformation resistance, abrasion resistance and tensile strength are further improved.

【００１６】また、請求項２の発明のように、外層のオ
レフィン系樹脂にカルボン酸変性ポリオレフィン樹脂を
併用すると、燃焼時のドリップが抑えられるという効果
を奏する。Further, when a carboxylic acid-modified polyolefin resin is used in combination with the olefin resin of the outer layer as in the second aspect of the present invention, there is an effect that dripping during combustion can be suppressed.

【００１７】[0017]

【実施例】以下、本発明のいくつかの実施例について説
明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below.

【００１８】本発明の実施例１〜３として、エチレン−
酢酸ビニル共重合体（酢酸ビニル含量＝２０％）、エチ
レン−エチルアクリレート共重合体（エチルアクリレー
ト含量＝２５％）、高密度ポリエチレン（融点＝１３５
℃，ショアＤ硬さ＝６３）、カルボン酸変性ポリプロピ
レン、ポリプロピレン（融点＝１６０℃，ショアＤ硬さ
＝６９）、水酸化アルミニウム、水酸化マグネシウム、
シリカ、赤リンを表１に示す割合で混練した樹脂組成物
を作製した。In Examples 1 to 3 of the present invention, ethylene-
Vinyl acetate copolymer (vinyl acetate content = 20%), ethylene-ethyl acrylate copolymer (ethyl acrylate content = 25%), high density polyethylene (melting point = 135)
C, Shore D hardness = 63), carboxylic acid-modified polypropylene, polypropylene (melting point = 160 ° C., Shore D hardness = 69), aluminum hydroxide, magnesium hydroxide,
A resin composition was prepared by kneading silica and red phosphorus at the ratios shown in Table 1.

【００１９】一方、比較例１〜８として、エチレン−酢
酸ビニル共重合体（酢酸ビニル含量＝２０％）、エチレ
ン−エチルアクリレート共重合体（エチルアクリレート
含量＝２５％）、高密度ポリエチレン（融点＝１３５
℃，ショアＤ硬さ＝６３）、低密度ポリエチレン（融点
＝９８℃，ショアＤ硬さ＝４８）、直鎖状低密度ポリエ
チレン（融点＝１１０℃，ショアＤ硬さ＝５８）、カル
ボン酸変性ポリプロピレン、ポリプロピレン（融点＝１
６０℃，ショアＤ硬さ＝６９）、水酸化アルミニウム、
水酸化マグネシウム、シリカ、赤リンを表２及び表３に
示す割合で混練した樹脂組成物を作成した。On the other hand, as Comparative Examples 1 to 8, ethylene-vinyl acetate copolymer (vinyl acetate content = 20%), ethylene-ethyl acrylate copolymer (ethyl acrylate content = 25%), high density polyethylene (melting point = 135
° C, Shore D hardness = 63), low density polyethylene (melting point = 98 ° C, Shore D hardness = 48), linear low density polyethylene (melting point = 110 ° C, Shore D hardness = 58), modified with carboxylic acid Polypropylene, polypropylene (melting point = 1
60 ° C., Shore D hardness = 69), aluminum hydroxide,
A resin composition was prepared by kneading magnesium hydroxide, silica, and red phosphorus at the ratios shown in Tables 2 and 3.

【００２０】なお、エチレン−酢酸ビニル共重合体は東
ソー社製ウルトラセン（商品名）、エチレン−エチルア
クリレート共重合体は三井デュポンポリケミカル社製エ
バフレックスＥＥＡ（商品名）、高密度ポリエチレンは
日本ポリオレフィン社製ジェイレクスＨＤ（商品名）、
低密度ポリエチレンは日本ポリオレフィン社製ジェイレ
クスＬＤ（商品名）、直鎖状低密度ポリエチレンは日本
ポリオレフィン社製ジェイレクスＬＬ（商品名）、カル
ボン酸変性ポリプロピレンは日本ポリオレフィン社製ア
ドテックス（商品名）を使用した。The ethylene-vinyl acetate copolymer is Ultracene (trade name) manufactured by Tosoh Corporation, the ethylene-ethyl acrylate copolymer is Evaflex EEA (trade name) manufactured by DuPont-Mitsui Polychemicals, and high-density polyethylene is Japan. J-LEX HD (trade name) manufactured by Polyolefin,
For low-density polyethylene, use Jakelex LD (trade name) manufactured by Japan Polyolefin Co., Ltd. For linear low-density polyethylene, use Jakelex LL (trade name) manufactured by Japan Polyolefin Co., and for carboxylic acid-modified polypropylene, use Adtex (trade name) manufactured by Japan Polyolefin Co. did.

【００２１】これらの樹脂組成物を、図１に示すよう
に、銅芯線１の外周に内層２、外層３をそれぞれの表に
示す厚みで押出して作成した薄肉電線にて、次の特性評
価を行った。 難燃性：長さ３００mmの電線試料を水平に支持し、口
径１０mmのブンゼンバーナーを用いて、還元炎の先端を
試料中央部の下側から３０秒以内で燃焼するまで当て、
炎を静かに取り去った後、試料の燃焼の程度を調べた。 耐摩耗性：２３±５℃の室温で、台上に固定した長さ
７５０mmの電線試料の絶縁被覆表面を軸方向に１０mm以
上の長さに渡ってブレードで往復して摩耗させる。ブレ
ードを毎分５０回又は６０回の速さで往復させたとき、
絶縁体の摩耗により、ブレードが芯線導体に接触するま
での往復回数を測定する。次に試料を１００mm移動させ
て、時計方向に９０度回転し、上記の測定を繰り返す。
この測定は、同一試料で計４回行い、その最小値を摩耗
抵抗とした。 耐白化性：半径６mmの筒に静かに数回巻き付け、その
状態で表面の白化度合いを目視にて確認した。As shown in FIG. 1, these resin compositions were extruded on the outer periphery of a copper core wire 1 with an inner layer 2 and an outer layer 3 at the thicknesses shown in the respective tables. went. Flame retardancy: A 300 mm long wire sample is supported horizontally, and the tip of the reducing flame is applied from below the center of the sample using a Bunsen burner with a diameter of 10 mm until it burns within 30 seconds.
After gently removing the flame, the degree of combustion of the sample was determined. Abrasion resistance: At room temperature of 23 ± 5 ° C., the insulating coating surface of a 750 mm long wire sample fixed on a table is reciprocated and abraded by a blade over a length of 10 mm or more in the axial direction. When the blade is reciprocated 50 or 60 times per minute,
The number of reciprocations until the blade contacts the core conductor due to wear of the insulator is measured. Next, the sample is moved 100 mm, rotated 90 degrees clockwise, and the above measurement is repeated.
This measurement was performed a total of four times with the same sample, and the minimum value was defined as abrasion resistance. Whitening resistance: The film was gently wound several times around a cylinder having a radius of 6 mm, and the degree of whitening of the surface was visually checked in that state.

【００２２】評価結果を表１ないし表３に示す。The evaluation results are shown in Tables 1 to 3.

【００２３】[0023]

【表１】 [Table 1]

【００２４】[0024]

【表２】 [Table 2]

【表３】 まず、表１に示すように、本発明の樹脂組成物に係る実
施例１〜３では難燃性、耐加熱変形性、耐白化性、柔軟
性のいずれも良好であった。また耐摩耗性も目標値であ
る３００回を大きく上回り、引張強さや伸びも良い特性
値が得られた。[Table 3] First, as shown in Table 1, in Examples 1 to 3 relating to the resin composition of the present invention, all of the flame retardancy, the heat deformation resistance, the whitening resistance, and the flexibility were good. Further, the abrasion resistance greatly exceeded the target value of 300 times, and characteristic values with good tensile strength and elongation were obtained.

【００２５】これに対し、外層にオレフィン系樹脂を用
いなかった比較例１や３では、耐摩耗性や引張強さ、加
熱変形率が大きく低下している。また、比較例２のよう
にオレフィン系樹脂であっても低密度ポリエチレンのよ
うな融点９８℃、ショアＤ硬さ４８の樹脂を使用する
と、比較例１や３と同様に、耐摩耗性や引張強さ、加熱
変形率が低下する。On the other hand, in Comparative Examples 1 and 3 in which no olefin resin was used for the outer layer, the abrasion resistance, the tensile strength, and the heat deformation rate were significantly reduced. Further, when a resin having a melting point of 98 ° C. and a Shore D hardness of 48, such as low-density polyethylene, is used as in Comparative Examples 2 and 3, as in Comparative Examples 1 and 3, wear resistance and tensile strength are reduced. The strength and the heat deformation rate decrease.

【００２６】また、内層にエチレン−α−オレフィン共
重合体以外の樹脂を使用した比較例３では、内層樹脂に
必要な特性である柔軟性が不足している。比較例６のよ
うに内層における金属水酸化物の量が少ないと、電線の
難燃性が不足する。難燃性を向上させるために外層樹脂
にカルボン酸変性ポリエチレンを使用しても、所望の難
燃性は得られない。また、難燃性を確保するために外層
樹脂の金属水酸化物量を増加させると、難燃性は向上す
るが、耐摩耗性や引張強さ等の特性が低下する（比較例
５）。逆に、比較例７のように内層において金属水酸化
物量が多すぎると、難燃性は向上するが、耐摩耗性や引
張強さ、柔軟性等が低下してしまう。さらに、内層及び
外層の厚さ寸法比が内層／外層＝４／６以下では絶縁電
線の柔軟性が不足し（比較例４）、逆に９／１以上では
耐摩耗性や引張強さが不足する（比較例８）。In Comparative Example 3 in which a resin other than the ethylene-α-olefin copolymer was used for the inner layer, the flexibility required for the inner layer resin was insufficient. When the amount of the metal hydroxide in the inner layer is small as in Comparative Example 6, the electric wire has insufficient flame retardancy. Even if carboxylic acid-modified polyethylene is used for the outer layer resin to improve the flame retardancy, the desired flame retardancy cannot be obtained. In addition, when the amount of metal hydroxide in the outer layer resin is increased in order to ensure flame retardancy, flame retardancy is improved, but characteristics such as wear resistance and tensile strength are reduced (Comparative Example 5). Conversely, if the amount of metal hydroxide in the inner layer is too large as in Comparative Example 7, the flame retardancy is improved, but the abrasion resistance, tensile strength, flexibility and the like are reduced. Furthermore, when the thickness dimension ratio of the inner layer and the outer layer is 4/6 or less, the flexibility of the insulated wire is insufficient (Comparative Example 4), and when it is 9/1 or more, the wear resistance and tensile strength are insufficient. (Comparative Example 8).

【図面の簡単な説明】[Brief description of the drawings]

【図１】絶縁電線の断面図FIG. 1 is a sectional view of an insulated wire.

【符号の説明】[Explanation of symbols]

１…銅芯線（導電芯線） ２…内層 ３…外層 1: Copper core wire (conductive core wire) 2: Inner layer 3: Outer layer

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 導電芯線の外周に内層と外層とからなる
絶縁層を被覆した絶縁電線において、前記内層はエチレ
ン−α−オレフィン共重合体の１００重量部に対して金
属水酸化物を５０〜４００重量部配合してなる樹脂組成
物からなると共に、前記外層は融点が１００℃以上かつ
ショアＤ硬さが５０以上のオレフィン系樹脂の１００重
量部に対して金属水酸化物を０〜５０重量部配合してな
る樹脂組成物からなり、前記内層及び外層の厚さ寸法比
が内層／外層＝６／４〜９／１であることを特徴とする
絶縁電線。1. An insulated wire in which an outer peripheral layer of a conductive core wire is coated with an insulating layer composed of an inner layer and an outer layer, wherein the inner layer contains 50 to 50 parts by weight of a metal hydroxide with respect to 100 parts by weight of an ethylene-α-olefin copolymer. The outer layer is made of a resin composition mixed with 400 parts by weight, and the outer layer has a melting point of 100 ° C. or more and a Shore D hardness of 50 to 50 parts by weight with respect to 100 parts by weight of a metal hydroxide. An insulated wire comprising a resin composition obtained by blending parts, wherein the thickness dimension ratio of the inner layer and the outer layer is inner layer / outer layer = 6/4 to 9/1. 【請求項２】 前記外層の樹脂組成物は、カルボン酸変
性オレフィン系樹脂を含むことを特徴とする請求項１記
載の絶縁電線。2. The insulated wire according to claim 1, wherein the resin composition of the outer layer contains a carboxylic acid-modified olefin resin.