JP2004346100A - Non-halogen flame-retardant resin composition and electric wire coated therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a white non-halogen flame-retardant resin composition having excellent heat-resistance and light stability, resistant to the lowering of mechanical properties and electric properties even by exposing to intense light at a high temperature exceeding 100°C over a long period, free from problems of powdering and discoloration and usable as a coating material for electric wire, and provide an electric wire coated with the resin composition. <P>SOLUTION: The non-halogen flame-retardant resin composition contains 100 pts. wt. of a polyolefin resin, 50-250 pts. wt. of a metal hydroxide, 0.1-3 pts. wt. of a compound expressed by formula (1), 0.2-6 wt.% of a compound containing the chemical structure expressed by formula (2), 0.1-3 pts. wt. of a hindered phenol oxidation inhibitor and 0.1-30 pts. wt. of titanium oxide. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

［式（１）中、Ｒ_１〜Ｒ_１２は、炭素数１〜４のアルキル基を表す。］

［式（２）中、Ｒ_１３〜Ｒ_１６は、炭素数１〜４のアルキル基を表し、Ｒ_１７は、水素原子、炭素数１〜４のアルキル基またはアセチル基を表し、Ｒ_１８は、水素原子またはシアノ基を表し、Ｘは、Ｏまたは−ＮＨを表す。］
【００１５】
本発明の第二の態様は、導体上に第一の態様のノンハロゲン難燃性樹脂組成物を被覆してなることを特徴とする電線である。
本発明者は、さらに、この電線を被覆するノンハロゲン難燃性樹脂組成物を、過酸化物架橋剤や電子線照射などにより架橋すると、電線に必要な柔軟性を有し、かつ安価であるが、架橋前の融点が１００℃以下である樹脂組成物を用いた場合でも、高温での機械特性に優れる電線が得られることを見出した。例えば、この電線は、ハンダゴテなどの高温体が接触しても絶縁が切れることがないとの特性を有する。本発明の第三の態様は、この好ましい態様に該当するものであって、導体上に第一の態様のノンハロゲン難燃性樹脂組成物が被覆されてなる電線であって、該ノンハロゲン難燃性樹脂組成物が架橋されていることを特徴とする電線を提供するものである。
該ノンハロゲン難燃性樹脂組成物を架橋する方法の好ましい態様としては、過酸化物架橋剤による架橋および電子線照射による架橋が挙げられる。
【００１６】
【発明の実施の形態】
本発明のノンハロゲン難燃性樹脂組成物に含有されるポリオレフィンとしては、ポリエチレン、ポリプロピレン、あるいはエチレンとα−オレフィンの共重合体などが挙げられる。ポリエチレンとしては、超低密度ポリエチレン、低密度ポリエチレン、直鎖状低密度ポリエチレン、中密度ポリエチレン、高密度ポリエチレンが例示される。また、α−オレフィンとしては、プロピレン、ブテン、ペンテン、ヘキセン、オクテン、酢酸ビニル、アクリル酸メチル、アクリル酸エチル、メタクリル酸メチル、メタクリル酸エチルなどが挙げられる。
【００１７】
このようなポリオレフィンの中でも、光安定剤との相溶性の観点から、エチレン−アクリル酸エチル共重合体（以下、ＥＥＡという）、またはエチレン−酢酸ビニル共重合体（以下、ＥＶＡという）が好ましい。
ポリオレフィンは１種を単独で使用してもよいが、２種以上を混合して使用してもよい。
【００１８】
金属水酸化物としては、好ましくは、水酸化マグネシウム、水酸化アルミニウムが例示される。これは、粉体として添加されるが、その平均粒子径（Ｄ５０）としては、０．５〜９．０μｍ の範囲のものが好ましく、１．０〜７．０μｍ の範囲のものがより好ましい。
【００１９】
水酸化マグネシウムとしては、天然のブルーサイト鉱石を原料とするものや、海水などを原料とした合成品が例示されるが、両者とも同様に使用することができる。合成品の方が純度の点で勝るため、高い難燃性が得られる傾向にあるが、一方の天然ブルーサイトから製造したものを使用した樹脂組成物は、非常に高いコストパフォーマンスを提供する。このように、いずれについても長所短所があるので、選択に当たり適用する最終製品の特性を考慮して使用する水酸化物の種類を決定すればよい。
【００２０】
また、金属水酸化物は、樹脂中への分散性を高めるために脂肪酸、あるいは、ビニルシラン、エポキシシラン、アミノシラン、アクリルシラン、メタクリルシランなどのシランカップリング剤などで表面処理されたものであっても良い。
金属水酸化物は１種を単独で使用してもよいが、２種以上を混合して使用してもよい。
【００２１】
金属水酸化物は、ハロゲンを含まない難燃剤の中でも難燃効果の高いものである。その樹脂組成物中の含有量は、ポリオレフィン系樹脂の１００重量部に対して、５０〜２５０重量部である。含有量が５０重量部より小さい場合は、充分な難燃効果が得られない。含有量が２５０重量部より大きい場合は、樹脂組成物としての機械特性が低下する。
【００２２】
式（１）で示される化合物、式（２）で示される化学構造を含む化合物、及び、ヒンダードフェノール系酸化防止剤は、絶縁材で被覆された電線が１００℃以上の高温下で紫外線を含む光に晒された場合でも、絶縁のひび割れの発生や機械強度の低下を生じないようにするために必要である。
【００２３】
式（１）で示される化合物は、紫外線吸収剤として用いられるものである。式（１）においてＲ_１〜Ｒ_１２は、それぞれ同一でもよく異なってもよい。好ましくは、式（１）においてＲ_１〜Ｒ_１２がメチル基の場合である２，４−ジ−ｔｅｒｔ−ブチルフェニル−３，５−ジ−ｔｅｒｔ−ブチル−４’−ヒドロキシルベンゾエートが例示され、この化合物としては市販品を用いることができる。
【００２４】
式（１）で示される化合物の、樹脂組成物中の含有量は、ポリオレフィン系樹脂の１００重量部に対して、０．１〜３重量部である。含有量が０．１部未満であると充分な耐熱性、光安定性が得られず、３部よりも多いとそれ以上耐熱性、光安定性が向上しないばかりか表面に移行して粉ふきや、着色などを生じる。
【００２５】
式（２）で示される化学構造を含む化合物は、ヒンダードアミン系光安定剤である。式（２）で示される化学構造の中でも、Ｒ_１３〜Ｒ_１６がメチル基を表し、Ｒ_１７が水素原子またはメチル基を表し、Ｒ_１８が水素原子を表し、ＸがＯを表す場合が、好ましい。
このような化合物としては、テトラキス（２，２，６，６−テトラメチル−４−ピペリジル）−１，２，３，４−ブタンテトラカルボン酸（旭電化・アデカスタブＬＡ−５７など）、テトラキス（１，２，２，６，６，−ペンタメチル−ピペリジル）−１，２，３，４−ブタンテトラカルボン酸（旭電化・アデカスタブＬＡ−５２など）などが挙げられる。また、ビニル基に式（２）で示される化学構造を結合させてなるビニルモノマーとエチレンや他のオレフィン化合物との共重合体も用いることができる。
【００２６】
式（２）で示される化合物の、樹脂組成物中の含有量は、ポリオレフィン系樹脂の１００重量部に対して、０．２〜６重量部である。含有量が０．２部未満であると充分な耐熱性、光安定性が得られず、６部よりも多いとそれ以上耐熱性、光安定性が向上しないばかりか表面に移行して粉ふきや、着色などを生じる。
【００２７】
ヒンダードフェノール系酸化防止剤としては、４，４’−ブチリデンビス（３−メチル−６−ｔ−ブチルフェノール）、テトラキス［メチレン−３−（３’５’−ジ−ｔ−ブチル−４’−ヒドロキシフェニル）プロピオネート］メタン、ｎ−オクタデシル−３−（４’−ヒドロキシ−３’，５’−ジ−ｔ−ブチルフェニル）プロピオネートなどが挙げられ、市販品を用いることができるが、ポリオレフィン樹脂との相溶性の観点から、テトラキス［メチレン−３−（３’５’−ジ−ｔ−ブチル−４’−ヒドロキシフェニル）プロピオネート］メタンが好ましい。
【００２８】
ヒンダードフェノール系酸化防止剤の、樹脂組成物中の含有量は、ポリオレフィン系樹脂の１００重量部に対して、０．１〜３．０重量部である。含有量が０．１重量部未満であると充分な耐熱性、光安定性が得られず、３重量部よりも多いとそれ以上耐熱性、光安定性が向上しないばかりか表面に移行して粉ふきや、着色などを生じる。
【００２９】
酸化チタンは、樹脂組成物を白色に着色するために含有される。この白色の樹脂組成物により絶縁された電線は、その白色により他色の電線と識別される。酸化チタンの樹脂組成物中の含有量は、ポリオレフィン系樹脂の１００重量部に対して、０．１〜３０重量部である。含有量が０．１重量部未満であると、白色化が不十分になる場合がある。また、３０重量部より多いと樹脂組成物の機械特性を低下させる場合がある。
酸化チタンとして、ルチル型、アナターゼ型どちらも用いることができるが、より耐熱性に優れた樹脂組成物を与えることから、ルチル型を用いることが望ましい。ルチル型、アナターゼ型ともに市販品を用いることができる。
【００３０】
本発明の、ノンハロゲン難燃性樹脂組成物は、上記の必須組成に加えて、他の組成を、本発明の効果を損なわない範囲で含有することができる。
例えば、一般的に使用される無機充填剤を含有することができる。この無機充填剤としては、クレー（カオリン）、マイカ、シリカ、酸化マグネシウム、炭酸マグネシウム、炭酸カルシウムなどが挙げられ、これらを使用することにより、押出成形時のソリ、ヒケ等の防止、熱伝導率向上による冷却速度の向上などの効果を発現させることができる。これらの添加量は先に添加する金属水酸化物の添加量を基準とし、材料強度等の機械特性を損なわない範囲で決定する。また必要に応じて、赤リン、リン酸塩等の難燃助剤を使用することもできる。
【００３１】
さらに本発明の難燃性樹脂組成物には、その特性を阻害しない範囲で、リン系、硫黄系、ビタミンＥ系、ラクトン系等の酸化防止剤、ヒドラジン系等の金属不活性剤、着色用顔料等、一般的に樹脂成形材料に使用される添加剤を配合してもよい。
【００３２】
本発明の電線は、上記の組成を有する樹脂組成物を、電線用導線へ被覆することにより得られる。通常、本発明の樹脂組成物は、コンパウンド化され、電線用導線への被覆は、該コンパウンドを用いて行われる。該コンパウンドの製造は、単軸及び二軸混練押出機、混練ニーダー、バンバリー、混練ロールなどの設備を使用して、上記の組成を溶融混合することにより行うことができる。溶融混合後は、必要に応じ、造粒、ペレット化などが行われる。こうして製造されたペレットなどを用いて行われる電線用絶縁体の押出被覆は、一軸スクリュー押出機によって行うことができ、この被覆により導線が絶縁されて電線が製造される。
【００３３】
電線は、配線過程などで、ハンダゴテなどの高温体が接触することがあり、高温体が接触しても絶縁が切れないとの機械特性を有することが好ましい。上記のように、電線を被覆している本発明の樹脂組成物を、過酸化物架橋剤や電子線照射などにより架橋すると、ハンダゴテなどの高温体が接触しても絶縁が切れないとの機械特性が得られるので好ましい。この優れた効果は、電線に必要な柔軟性を有し、かつ安価であるが、架橋前の融点が１００℃以下である樹脂組成物を用いても得られる。
【００３４】
過酸化物架橋剤は、導線への被覆前の樹脂組成物中に予め添加される。電子線照射は、導線への被覆後に行うことができる。電子線の代わりに他の放射線を用いることも可能である。照射量としては、通常２０〜１０００ｋＧｙ程度が採用される。
【００３５】
次に実施例を用いて本発明をより具体的に説明するが、本発明は実施例に限定されるものではない。
【実施例】
【００３６】
［光安定性の評価］
電線の高温での光安定性の評価には、試験を加速して行うために、照明器具に使われる白色蛍光灯に近い発光スペクトルを持ち、発光強度がはるかに強い高圧水銀ランプ（４００Ｗ、透明型）を用いた。このランプを、ギアオーブン式恒温槽の中心に設置し、ランプの光が絶縁表面に当たるように電線を固定して行った。電線は、ランプの表面から電線表面までの距離が１８ｃｍになるような回転式の枠で固定した。試験温度は屋外用照明器具内の最高温度となる１２０℃とした。サンプルとしては、電線を、電線外径と同じ外径のステンレス棒の周囲に１０回巻き付けたもの、及び、導体を抜いて１５ｃｍの長さに切断したものを用意して、前者については、１５００時間の試験後に電線表面に亀裂が入っていなければ合格、後者については、１５００時間の試験後に引張破断伸びが５０％以上であれば合格と判定した。
【００３７】
［難燃性の評価］
電線の難燃性はＪＩＳ Ｃ３００５に記載されている方法で評価した。
すなわち、内火炎の高さを３５ｍｍ、外火炎の高さを１３０ｍｍに調整したブンゼンバーナーを垂直に立てて、６０度に傾斜させた長さ３００ｍｍの電線の下端から２０ｍｍの位置に内火炎の先端が接するように炎を当て、電線が燃焼し始めるまで３０秒以内で当てて、炎を静かに取り去り、６０秒以内に消火するかどうかで判断した。
【００３８】
［電線の外観の評価］
初期の着色の有無、更に６０℃で１ヶ月間放置した後に絶縁表面の粉ふきや着色を生じないか評価した。
【００３９】
実施例
表１の実施例１〜２に示した重量比で各配合成分を計量して、８インチオープンロールを用いて１４０±５℃で１０分間混練した後、厚み約３ｍｍの帯状に引き出して、造粒機により約３ｍｍ角のペレット状に切断成形した。
これを、φ７５ｍｍの一軸スクリュー押出機を用いて、直径０．８ｍｍの銅線に０．８ｍｍの厚さになるよう１６０℃の押出温度で１００ｍ／ｍｉｎの線速で押出被覆した後、照射線量１００ｋＧｙで電子線照射架橋を行なった。次いで、押出架橋した電線について前述の光安定性の評価、難燃性の評価、外観の評価を行った。結果を表１に示すが、いずれの試験にも合格し、良好な結果が得られることが分かった。
【００４０】
比較例
実施例１〜２と同様な方法で、比較例１〜１０についても電線サンプルを作製し、光安定性の評価、難燃性の評価、外観の評価を行った。その結果を表１〜３に示す。
式（１）の化合物（紫外線吸収剤）、式（２）の構造を含む化合物（ヒンダードアミン系光安定剤）、ヒンダードフェノール系酸化防止剤の量が、請求項１の範囲より少ない比較例１については、光安定性の評価後に絶縁にひび割れが認められ、また、引張破断伸びも５０％を下回った。
【００４１】
請求項１の範囲より、紫外線吸収剤、ヒンダードアミン系光安定剤、ヒンダードフェノール系酸化防止剤の量が多い比較例２については、光安定性の評価は合格したが、６０℃１ヶ月放置後に絶縁表面が褐色に変化し、また、粉ふきが認められた。
【００４２】
紫外線吸収剤、ヒンダードアミン系光安定剤、ヒンダードフェノール系酸化防止剤のいずれかが添加されていない比較例３〜５については、どれも光安定性の評価後に絶縁にひび割れが認められ、また、引張破断伸びも５０％を下回った。
【００４３】
紫外線吸収剤として、式（１）の化合物以外の化合物を使用した比較例６については、光安定性の評価には合格したが、絶縁が黄色に着色し、電線に用いるには不適当であった。
また、ヒンダードアミン系光安定剤として、式（２）の構造を有する化合物以外の化合物を使用した比較例７については、光安定性の評価には合格したが、６０℃１ヶ月間放置後に絶縁の表面が褐色に変色し、また粉ふきが認められ、電線に用いるには不適当であった。
【００４４】
金属水酸化物の量が、請求項１の範囲よりも多い比較例８については、光安定性の評価後に絶縁にひび割れが認められ、また、引張破断伸びも５０％を下回った。金属水酸化物の量が、請求項１の範囲よりも少ない比較例９については、難燃性の評価に合格しなかった。
酸化チタンの量が、請求項１の範囲よりも多い比較例１０については、光安定性の評価後に絶縁にひび割れが認められ、また、引張破断伸びも５０％を下回った。また、絶縁表面が褐色に変色した。
【００４５】
なお、実施例および比較例で用い、表１〜３に記載された各配合成分は、以下のとおりである。
ポリオレフィン樹脂： ＥＶＡ（日本ユニカ製、商品名：ＮＵＣ６５２０）
紫外線吸収剤１： ２，４−ジ−ｔｅｒｔ−ブチルフェニル−３，５−ジ−ｔｅｒｔ−ブチル−４’−ヒドロキシルベンゾエート（シプロ化成製、商品名：ＳＥＥＳＯＲＢ７１２）
紫外線吸収剤２： ２−［２’−ヒドロキシ−３’，５’−ビス（ａ，ａ’−ジメチルベンジル）フェニル］ベンゾトリアゾール（チバガイギー製、商品名：ＴＩＮＵＶＩＮ２３４）
ヒンダードアミン系光安定剤１： テトラキス（２，２，６，６−テトラメチル−４−ピペリジル）−１，２，３，４−ブタンテトラカルボン酸（旭電化製、商品名：アデカスタブＬＡ−５７）
ヒンダードアミン系光安定剤２： ビス−［２，２，６，６−テトラメチル−４−ピペリジニル］セバシン酸（旭電化製、商品名：アデカスタブＬＡ−７７）
ヒンダードフェノール系酸化防止剤： テトラキス［メチレン−３−（３’５’−ジ−ｔ−ブチル−４’−ヒドロキシフェニル）プロピオネート］メタン（チバガイギー製、商品名：イルガノックス１０１０）
金属水酸化物： 水酸化マグネシウム（協和化学製、商品名：キスマ５Ａ）
酸化チタン： ルチル型酸化チタン（堺化学製、商品名：Ｒ２５）
【００４６】
【表１】

【００４７】
【表２】

【００４８】
【表３】

【発明の効果】
【００４９】
本発明のノンハロゲン難燃性樹脂組成物は、ハロゲンを含まず、優れた絶縁性、難燃性を有し、鮮明な白色に着色されている。さらに、優れた耐熱性、光安定性を有する。その結果、導体上に本発明のノンハロゲン難燃性樹脂組成物が被覆されてなる本発明の電線は、その焼却に際してもハロゲン化水素等の有害ガスを発生することがなく、また優れた耐熱性、光安定性を有し、高温で紫外線を含む光に晒された場合でも、絶縁にひび割れを生じず、また、機械特性の低下が小さい。さらに、長期間保存した場合でも表面の粉ふきや着色の問題を生じることがない。従って、本発明の電線は、配線が１００℃以上の高温で紫外線を含む光に晒されることになる屋外用照明器具等の配線に用いることができ、しかも鮮明な白色に着色されているので配線同士を識別しやすいとの特徴も有し、商品価値の高い難燃性電線を与える。
また、この本発明の電線に、架橋を施すと、ハンダゴテなどの高温体の接触により絶縁が切れるなどの問題が無く、より商品価値の高い難燃性電線を与える。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a halogen-free flame-retardant resin composition that can be suitably used as an insulating material for electric wires and the like, and an electric wire coated with the resin composition. In particular, a non-halogen flame-retardant resin composition having heat resistance and light stability that does not cause problems such as insulation failure even in an environment where the surface of an insulating material is exposed to light such as ultraviolet light at a high temperature, and this resin composition The present invention relates to an electric wire covered with an object.
[0002]
[Prior art]
Insulating materials such as electric wires often require flame retardancy. Therefore, a halogen-based resin composition using a flame-retardant polyvinyl chloride or a halogen-based flame-retardant material containing chlorine or the like in a molecule has been used as an insulating material. However, there is a problem that harmful gas such as hydrochloric acid gas may be generated during incineration of electric wires using these. As an insulating material that does not have such a problem, a non-halogen flame-retardant insulating material to which a metal hydroxide such as magnesium hydroxide or aluminum hydroxide is added as a flame retardant is known, and an electric wire coated with this insulating material is used. It is being switched from conventional polyvinyl chloride wires and the like.
[0003]
However, non-halogen flame-retardant insulating materials to which metal hydroxides are added have poorer light stability and stronger light intensity than insulating materials using polyvinyl chloride, halogen-based flame retardants, and insulating materials not containing flame retardants. In an environment exposed to water, the mechanical and electrical characteristics are easily damaged. Therefore, there is a problem that it is not suitable as an insulating material for electric wires placed in such an environment, for example, an insulating material for wiring in lighting equipment.
[0004]
In order to improve light stability, addition of a light stabilizer is conceivable. Conventionally, as a non-halogen flame-retardant resin composition for use as an insulation material of an electric wire, a composition containing a light stabilizer is known. .
For example, claim 1 (Patent Document 1) of JP-A-2000-143883 discloses polyolefin, an inorganic flame retardant such as a metal hydroxide, and ethylene and a vinyl monomer having a specific structure as a light stabilizer. A non-halogen flame-retardant resin composition characterized by containing a copolymer containing as an essential component is disclosed, and this resin composition has good dispersibility in a polyethylene-based copolymer and excellent weather resistance. It is described as having a suitable material as an insulating material for electric wires.
[0005]
Japanese Patent Application Laid-Open No. 2001-126747 discloses a non-halogen composition containing a polymer having a polar group as a base polymer on the outermost layer surface of an insulated wire or cable. An insulated wire / cable provided with a coating layer having a thickness of 0.1 mm to 1 mm added thereto is disclosed. Claim 2 describes that the weathering agent comprises an ultraviolet absorber and / or a light stabilizer. Have been.
[0006]
However, these conventional non-halogen flame-retardant resin compositions are inferior in heat resistance, and have a problem that when left in a high-temperature environment for a long period of time, the light stabilizing effect is reduced and the mechanical and electrical properties are impaired. Was. For example, if the wire insulated with these non-halogen flame-retardant resin compositions is used for a long time in applications such as outdoor lighting fixtures where the temperature inside the fixture is 100 ° C. or higher, the insulation will crack and cause insulation. There was a possibility that problems such as defects might occur. Therefore, it cannot be used for such an application, and there is a problem that the application is limited. This is because the light stabilizer migrates to the surface of the insulating material and evaporates due to long-term use at high temperature, the light stabilizer is lost due to thermal decomposition, and the resin deteriorates due to the synergistic effect of thermal deterioration and light deterioration. Is considered to be promoted.
[0007]
As a method for compensating for a decrease in the light stabilizing effect due to long-term use at a high temperature, (1) a method of adding a pigment having a light shielding function such as carbon, (2) a method of increasing the amount of a light stabilizer, and (3) light A method using a light stabilizer having a high stabilizing effect can be considered.
[0008]
However, the wiring material of the lighting fixture needs to be colored so that each wiring can be identified, and in particular, since a large amount of white is used, a clear white coloring is desired as an insulating material covering such an electric wire. .
However, when a pigment such as carbon is added, it is difficult to obtain a white color even when a white pigment such as titanium oxide is added. Therefore, the method (1) is difficult to employ. In addition, when the amount of the light stabilizer is increased, the electric wire is colored by the color of the light stabilizer itself, or the light stabilizer is deteriorated by heat during use, and there is a problem that the discoloration of the electric wire is increased. The method is similarly difficult to adopt. Further, when a large amount of the light stabilizer is added, the amount exceeds the limit amount that can be dissolved in the resin, and the light stabilizer migrates to the surface, causing a problem of dusting.
Further, currently known light stabilizers having a high light stabilizing effect absorb light having a wavelength in the visible light region (400 nm to 800 nm) and are colored yellow. Is also difficult to adopt.
[0009]
[Patent Document 1]
JP-A-2000-143883 (Claim 1)
[0010]
[Patent Document 2]
JP-A-2001-126747 (Claims 1 and 2)
[0011]
[Problems to be solved by the invention]
The present invention is a white, non-halogen, flame-retardant resin composition that can be used as an insulating material for electric wires, and has excellent heat resistance, light stability, and strong light at a high temperature exceeding 100 ° C. for a long time. It is an object of the present invention to provide a resin composition which does not deteriorate in mechanical properties and electrical properties even when exposed to water, and does not cause problems such as dusting and coloring.
[0012]
The present invention also provides a white electric wire which is coated and insulated with such a resin composition, has excellent heat resistance and light stability as well as flame retardancy, and does not generate corrosive gas even when incinerated. The task is to
[0013]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a specific ultraviolet absorber, a light stabilizer, an antioxidant, and a white pigment are added to a polyolefin resin to which a metal hydroxide is added as a flame retardant. It has been found that this object can be achieved by adding a fixed amount, and the present invention has been completed.
[0014]
In the first embodiment of the present invention, 100 parts by weight of a polyolefin resin, 50 to 250 parts by weight of a metal hydroxide, 0.1 to 3 parts by weight of a compound represented by the following formula (1), ) Containing 0.2 to 6 parts by weight of a compound having the chemical structure represented by the formula (1), 0.1 to 3 parts by weight of a hindered phenolic antioxidant, and 0.1 to 30 parts by weight of titanium oxide. It is a non-halogen flame-retardant resin composition characterized by the following.

[In the formula (1), R _{1 to} R ₁₂ represent an alkyl group having 1 to 4 carbon atoms. ]

[In the formula (2), R _{13 to} R ₁₆ represent an alkyl group having 1 to 4 carbon atoms, R ₁₇ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an acetyl group, and R ₁₈ represents X represents a hydrogen atom or a cyano group, and X represents O or -NH. ]
[0015]
According to a second aspect of the present invention, there is provided an electric wire formed by coating a conductor with the non-halogen flame-retardant resin composition of the first aspect.
The present inventor further provides a necessary flexibility for the electric wire when the non-halogen flame-retardant resin composition covering the electric wire is crosslinked with a peroxide cross-linking agent or electron beam irradiation, and is inexpensive. Also, it has been found that even when a resin composition having a melting point before crosslinking of 100 ° C. or less is used, an electric wire having excellent mechanical properties at a high temperature can be obtained. For example, this electric wire has a characteristic that insulation does not break even when a high-temperature body such as a soldering iron comes in contact with the electric wire. A third aspect of the present invention is a wire corresponding to this preferred aspect, wherein the electric wire comprises a conductor coated with the non-halogen flame-retardant resin composition of the first aspect, An object of the present invention is to provide an electric wire characterized in that a resin composition is crosslinked.
Preferred embodiments of the method for crosslinking the non-halogen flame-retardant resin composition include crosslinking with a peroxide crosslinking agent and crosslinking with electron beam irradiation.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Examples of the polyolefin contained in the non-halogen flame-retardant resin composition of the present invention include polyethylene, polypropylene, and a copolymer of ethylene and an α-olefin. Examples of polyethylene include ultra low density polyethylene, low density polyethylene, linear low density polyethylene, medium density polyethylene, and high density polyethylene. Examples of the α-olefin include propylene, butene, pentene, hexene, octene, vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and the like.
[0017]
Among such polyolefins, an ethylene-ethyl acrylate copolymer (hereinafter, referred to as EEA) or an ethylene-vinyl acetate copolymer (hereinafter, referred to as EVA) is preferable from the viewpoint of compatibility with the light stabilizer.
One type of polyolefin may be used alone, or two or more types may be used in combination.
[0018]
Preferred examples of the metal hydroxide include magnesium hydroxide and aluminum hydroxide. This is added as a powder, and the average particle diameter (D50) is preferably in the range of 0.5 to 9.0 μm, more preferably in the range of 1.0 to 7.0 μm.
[0019]
Examples of magnesium hydroxide include those using natural brucite ore as a raw material and synthetic products using seawater or the like as a raw material, and both can be used similarly. Synthetic products tend to have higher flame retardancy because they are superior in purity, but on the other hand, resin compositions using those made from natural brucite provide very high cost performance. As described above, each of these has advantages and disadvantages, and the type of hydroxide to be used may be determined in consideration of the characteristics of the final product to be applied in selection.
[0020]
Further, the metal hydroxide has been subjected to a surface treatment with a fatty acid, or a silane coupling agent such as vinyl silane, epoxy silane, amino silane, acrylic silane, methacryl silane, etc. in order to enhance dispersibility in the resin. Is also good.
One metal hydroxide may be used alone, or two or more metal hydroxides may be used in combination.
[0021]
Metal hydroxide has a high flame retardant effect among flame retardants containing no halogen. The content in the resin composition is 50 to 250 parts by weight based on 100 parts by weight of the polyolefin resin. If the content is less than 50 parts by weight, a sufficient flame retardant effect cannot be obtained. If the content is more than 250 parts by weight, the mechanical properties of the resin composition will decrease.
[0022]
The compound represented by the formula (1), the compound having the chemical structure represented by the formula (2), and the hindered phenol-based antioxidant are used for an electric wire coated with an insulating material to emit ultraviolet light at a high temperature of 100 ° C. or more. It is necessary to prevent the occurrence of cracks in the insulation and a decrease in mechanical strength even when exposed to the light containing.
[0023]
The compound represented by the formula (1) is used as an ultraviolet absorber. In the formula (1), R _{1 to} R ₁₂ may be the same or different. Preferably, 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4′-hydroxylbenzoate in which R _{1 to} R ₁₂ in the formula (1) are a methyl group is exemplified, As this compound, a commercially available product can be used.
[0024]
The content of the compound represented by the formula (1) in the resin composition is 0.1 to 3 parts by weight based on 100 parts by weight of the polyolefin-based resin. When the content is less than 0.1 part, sufficient heat resistance and light stability cannot be obtained. When the content is more than 3 parts, the heat resistance and light stability are not further improved, and the powder migrates to the surface and causes And coloring.
[0025]
The compound having the chemical structure represented by the formula (2) is a hindered amine light stabilizer. Among the chemical structures represented by the formula (2), when R _{13 to} R ₁₆ represent a methyl group, R ₁₇ represents a hydrogen atom or a methyl group, R ₁₈ represents a hydrogen atom, and X represents O, preferable.
Examples of such a compound include tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylic acid (Asahi Denka Adecastab LA-57, etc.), tetrakis ( 1,2,2,6,6-pentamethyl-piperidyl) -1,2,3,4-butanetetracarboxylic acid (Asahi Denka, Adekastab LA-52, etc.). Further, a copolymer of a vinyl monomer having a chemical structure represented by the formula (2) bonded to a vinyl group and ethylene or another olefin compound can also be used.
[0026]
The content of the compound represented by the formula (2) in the resin composition is 0.2 to 6 parts by weight based on 100 parts by weight of the polyolefin resin. When the content is less than 0.2 part, sufficient heat resistance and light stability cannot be obtained, and when the content is more than 6 parts, the heat resistance and light stability are not further improved, and the powder migrates to the surface and causes And coloring.
[0027]
Hindered phenolic antioxidants include 4,4′-butylidenebis (3-methyl-6-t-butylphenol), tetrakis [methylene-3- (3′5′-di-t-butyl-4′-hydroxy) Phenyl) propionate] methane, n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate and the like, and commercially available products can be used. From the viewpoint of compatibility, tetrakis [methylene-3- (3′5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane is preferred.
[0028]
The content of the hindered phenol-based antioxidant in the resin composition is 0.1 to 3.0 parts by weight based on 100 parts by weight of the polyolefin-based resin. When the content is less than 0.1 part by weight, sufficient heat resistance and light stability cannot be obtained. When the content is more than 3 parts by weight, not only heat resistance and light stability are not further improved but also the surface is transferred. This causes dusting and coloring.
[0029]
Titanium oxide is included to color the resin composition white. An electric wire insulated by this white resin composition is distinguished from another color electric wire by its white color. The content of titanium oxide in the resin composition is 0.1 to 30 parts by weight based on 100 parts by weight of the polyolefin-based resin. If the content is less than 0.1 part by weight, whitening may be insufficient. If the amount is more than 30 parts by weight, the mechanical properties of the resin composition may be reduced.
As the titanium oxide, either a rutile type or an anatase type can be used, but it is desirable to use a rutile type in order to provide a resin composition having more excellent heat resistance. Commercial products can be used for both rutile type and anatase type.
[0030]
The non-halogen flame-retardant resin composition of the present invention may contain other components in addition to the above-mentioned essential components as long as the effects of the present invention are not impaired.
For example, it may contain commonly used inorganic fillers. Examples of the inorganic filler include clay (kaolin), mica, silica, magnesium oxide, magnesium carbonate, calcium carbonate and the like. By using these, prevention of warpage, sink mark, etc. during extrusion molding, thermal conductivity Effects such as improvement of the cooling rate by the improvement can be exhibited. These addition amounts are determined based on the addition amount of the metal hydroxide added earlier, within a range that does not impair the mechanical properties such as the material strength. If necessary, a flame retardant auxiliary such as red phosphorus or a phosphate may be used.
[0031]
Further, the flame-retardant resin composition of the present invention may contain phosphorus-based, sulfur-based, vitamin E-based, lactone-based antioxidants, hydrazine-based metal deactivators, and coloring agents as long as their properties are not impaired. Additives generally used in resin molding materials, such as pigments, may be blended.
[0032]
The electric wire of the present invention can be obtained by coating a resin wire having the above-described composition on an electric wire. Usually, the resin composition of the present invention is formed into a compound, and the coating of the conductor for an electric wire is performed using the compound. The compound can be produced by melt-mixing the above composition using equipment such as a single-screw or twin-screw kneading extruder, a kneading kneader, a Banbury, and a kneading roll. After the melt mixing, granulation, pelletization, and the like are performed as necessary. Extrusion coating of the insulator for electric wires, which is performed using the pellets or the like thus produced, can be performed by a single screw extruder, and the coating insulates the conductive wire to produce an electric wire.
[0033]
The electric wire preferably has a mechanical property that a high-temperature body such as a soldering iron may come into contact during a wiring process or the like, and insulation does not break even when the high-temperature body comes into contact. As described above, when the resin composition of the present invention covering an electric wire is cross-linked by a peroxide cross-linking agent or electron beam irradiation, the insulation cannot be cut even by contact with a high-temperature body such as a soldering iron. It is preferable because characteristics can be obtained. This excellent effect can be obtained by using a resin composition which has the flexibility required for electric wires and is inexpensive, but has a melting point of 100 ° C. or less before crosslinking.
[0034]
The peroxide crosslinking agent is added in advance to the resin composition before coating the conductive wire. The electron beam irradiation can be performed after coating the conductive wire. It is also possible to use other radiations instead of electron beams. The irradiation amount is usually about 20 to 1000 kGy.
[0035]
Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples.
【Example】
[0036]
[Evaluation of light stability]
In order to evaluate the light stability of electric wires at high temperatures, a high-pressure mercury lamp (400 W, transparent Type). This lamp was installed in the center of a gear oven type thermostat, and the electric wire was fixed so that the light of the lamp hit the insulating surface. The electric wire was fixed with a rotary frame such that the distance from the lamp surface to the electric wire surface was 18 cm. The test temperature was 120 ° C., which is the highest temperature in the outdoor lighting fixture. As a sample, a wire prepared by winding a wire around a stainless steel rod having an outer diameter equal to the outer diameter of the wire 10 times and a wire cut out to a length of 15 cm by removing a conductor were prepared. If the wire surface had no crack after the time test, the test was passed. If the tensile elongation at break was 50% or more after the test for 1500 hours, the test was judged to be acceptable.
[0037]
[Evaluation of flame retardancy]
The flame retardancy of the electric wire was evaluated by the method described in JIS C3005.
That is, a Bunsen burner in which the height of the inner flame is adjusted to 35 mm and the height of the outer flame is adjusted to 130 mm is set up vertically, and the tip of the inner flame is positioned 20 mm from the lower end of the 300 mm long wire inclined at 60 degrees. Was applied within 30 seconds until the electric wire started burning, the flame was gently removed, and it was judged whether or not the fire was extinguished within 60 seconds.
[0038]
[Evaluation of wire appearance]
Evaluation was made as to whether or not there was an initial coloring, and further whether the insulating surface was wiped or colored after being left at 60 ° C. for one month.
[0039]
EXAMPLES Each of the ingredients was weighed at the weight ratio shown in Examples 1 and 2 of Table 1, kneaded at 140 ± 5 ° C. for 10 minutes using an 8-inch open roll, and then pulled out into a strip having a thickness of about 3 mm. Then, it was cut and formed into pellets of about 3 mm square by a granulator.
This was extruded onto a 0.8 mm diameter copper wire at a extrusion temperature of 160 ° C. at a linear speed of 100 m / min using a φ75 mm single screw extruder so as to have a thickness of 0.8 mm. Electron beam irradiation crosslinking was performed at 100 kGy. The extruded and crosslinked electric wire was evaluated for light stability, flame retardancy, and appearance as described above. The results are shown in Table 1, and all of the tests passed, and it was found that good results were obtained.
[0040]
Comparative Examples In the same manner as in Examples 1 and 2, electric wire samples were prepared for Comparative Examples 1 to 10, and evaluations of light stability, flame retardancy, and appearance were performed. The results are shown in Tables 1 to 3.
Comparative Example 1 wherein the amounts of the compound of formula (1) (ultraviolet absorber), the compound having the structure of formula (2) (hindered amine light stabilizer) and the hindered phenol antioxidant are less than the range of claim 1. With regard to, cracks were observed in the insulation after the evaluation of photostability, and the tensile elongation at break was less than 50%.
[0041]
From the range of claim 1, the comparative example 2 in which the amounts of the ultraviolet absorber, the hindered amine light stabilizer, and the hindered phenol antioxidant were large passed the evaluation of the light stability, but left at 60 ° C. for one month. The insulating surface turned brown and dusting was observed.
[0042]
Regarding Comparative Examples 3 to 5 in which any one of an ultraviolet absorber, a hindered amine light stabilizer, and a hindered phenol antioxidant was not added, cracks were observed in the insulation after evaluation of light stability, and The tensile elongation at break was also less than 50%.
[0043]
Comparative Example 6 using a compound other than the compound of the formula (1) as an ultraviolet absorber passed the evaluation of photostability, but the insulation was colored yellow and was unsuitable for use in electric wires. Was.
In Comparative Example 7 using a compound other than the compound having the structure of the formula (2) as the hindered amine-based light stabilizer, the light stability evaluation was passed. The surface turned brown and dusting was observed, which was unsuitable for use in electric wires.
[0044]
In Comparative Example 8 in which the amount of the metal hydroxide was larger than the range of Claim 1, cracks were observed in the insulation after the evaluation of photostability, and the tensile elongation at break was less than 50%. Comparative Example 9 in which the amount of the metal hydroxide was smaller than the range of Claim 1 did not pass the evaluation of flame retardancy.
In Comparative Example 10 in which the amount of titanium oxide was larger than the range of Claim 1, cracks were observed in the insulation after the evaluation of photostability, and the tensile elongation at break was less than 50%. Further, the insulating surface turned brown.
[0045]
The components used in Examples and Comparative Examples and described in Tables 1 to 3 are as follows.
Polyolefin resin: EVA (product name: NUC6520, manufactured by Nippon Yunika)
Ultraviolet absorber 1: 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4′-hydroxylbenzoate (Cipro Kasei, trade name: SEESORB712)
UV absorber 2: 2- [2'-hydroxy-3 ', 5'-bis (a, a'-dimethylbenzyl) phenyl] benzotriazole (Ciba Geigy, trade name: TINUVIN 234)
Hindered amine light stabilizer 1: tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylic acid (manufactured by Asahi Denka, trade name: ADK STAB LA-57)
Hindered amine light stabilizer 2: bis- [2,2,6,6-tetramethyl-4-piperidinyl] sebacic acid (trade name: ADK STAB LA-77, manufactured by Asahi Denka)
Hindered phenolic antioxidant: tetrakis [methylene-3- (3′5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane (Ciba Geigy, trade name: Irganox 1010)
Metal hydroxide: magnesium hydroxide (Kyowa Chemical Co., trade name: Kisuma 5A)
Titanium oxide: Rutile-type titanium oxide (manufactured by Sakai Chemical Co., trade name: R25)
[0046]
[Table 1]

[0047]
[Table 2]

[0048]
[Table 3]

【The invention's effect】
[0049]
The non-halogen flame-retardant resin composition of the present invention contains no halogen, has excellent insulating properties and flame retardancy, and is colored vivid white. Furthermore, it has excellent heat resistance and light stability. As a result, the electric wire of the present invention in which the conductor is coated with the non-halogen flame-retardant resin composition of the present invention does not generate harmful gases such as hydrogen halide even when incinerated, and has excellent heat resistance. It has light stability and does not crack the insulation even when exposed to light including ultraviolet rays at high temperature, and the deterioration of mechanical properties is small. Further, even when stored for a long time, there is no problem of dusting or coloring of the surface. Therefore, the electric wire of the present invention can be used for wiring of outdoor lighting fixtures and the like that are exposed to light including ultraviolet rays at a high temperature of 100 ° C. or more, and furthermore, since the wiring is clearly colored white, It also has the feature of being easily distinguishable from each other, and provides a flame-retardant electric wire having high commercial value.
Further, when the electric wire of the present invention is crosslinked, there is no problem such as insulation being cut off by contact with a high-temperature body such as a soldering iron, and a flame-retardant electric wire having higher commercial value is provided.

Claims (6)

100 parts by weight of a polyolefin resin, 50 to 250 parts by weight of a metal hydroxide, 0.1 to 3 parts by weight of a compound represented by the following formula (1), and a compound having a chemical structure represented by the following formula (2) A non-halogen flame-retardant resin composition, comprising 0.2 to 6 parts by weight of a hindered phenolic antioxidant and 0.1 to 30 parts by weight of a titanium oxide. object.

[In the formula (1), R _{1 to} R ₁₂ represent an alkyl group having 1 to 4 carbon atoms. ]

[In the formula (2), R _{13 to} R ₁₆ represent an alkyl group having 1 to 4 carbon atoms, R ₁₇ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an acetyl group, and R ₁₈ represents X represents a hydrogen atom or a cyano group, and X represents O or -NH. ] The non-halogen according to claim 1, wherein the compound represented by the formula (1) is 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4'-hydroxylbenzoate. Flame retardant resin composition. In the formula (2), R _{13 to} R ₁₆ represent a methyl group, R ₁₇ represents a hydrogen atom or a methyl group, R ₁₈ represents a hydrogen atom, and X represents O. The non-halogen flame-retardant resin composition according to claim 2. An electric wire comprising a conductor coated with the non-halogen flame-retardant resin composition according to any one of claims 1 to 3. The electric wire according to claim 4, wherein the halogen-free flame-retardant resin composition is cross-linked. The electric wire according to claim 5, wherein the crosslinking is performed by a peroxide crosslinking agent or electron beam irradiation.