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JP3580608B2 - Fire resistant wire - Google Patents

Fire resistant wire Download PDF

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Publication number
JP3580608B2
JP3580608B2 JP21039895A JP21039895A JP3580608B2 JP 3580608 B2 JP3580608 B2 JP 3580608B2 JP 21039895 A JP21039895 A JP 21039895A JP 21039895 A JP21039895 A JP 21039895A JP 3580608 B2 JP3580608 B2 JP 3580608B2
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Japan
Prior art keywords
fire
ethylene
sheath
resin composition
resistant
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JP21039895A
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JPH0963361A (en
Inventor
智行 鈴木
道宏 島田
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THE FURUKAW ELECTRIC CO., LTD.
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THE FURUKAW ELECTRIC CO., LTD.
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Description

【0001】
【発明の属する技術分野】
本発明は導体上に耐火層、絶縁層を順次設け、その外側にシースを設けた耐火電線に関し、更に詳しくは、絶縁層ならびにシースに用いる材料に改良を加えた高難燃の耐火電線に関するものである。
【0002】
【従来の技術】
従来の耐火電線は、導体上に耐火層を形成し、該耐火層外周に絶縁層を設けた絶縁線心上に、シースを設けた構造、もしくは前記の絶縁線心を数本撚り合わせ、その外側に介在物、押さえ巻きテープ等を介してシースを設けた構造となっている。そして、通常、耐火層には集成マイカをプラスチックフィルムまたはガラスクロスの片面に張り合わせたテープが使用され、絶縁層にはポリエチレン、架橋ポリエチレンが使用され、シースには塩化ビニル樹脂組成物、ポリエチレン系樹脂組成物が使用される。
【0003】
耐火電線は非常用電源ケーブルとして用いられるもので、火災時に30分間の電力供給が出来る耐火性能を有するものである。そのため、耐火電線の要求特性は電気用品取締法等に定められた一般物性の他に、消防庁告示第7号の耐火電線の基準に規定された性能を満足するものとなっている。この耐火性能は、日本電線工業会の「耐火・耐熱電線認定委員会」によって規定されている耐火試験によって評価される。この耐火試験は、耐火炉により耐火電線1.3mを、JIS A 1304に定める火災温度曲線に準じて30分間加熱し、その時の絶縁耐力、絶縁抵抗、燃焼性について評価するものである。耐火電線の必要性能として定められている規格は、30分間の加熱中にAC600V、加熱前後にAC1500Vの印加において絶縁破壊を起こさない絶縁耐力を有すること、30分間の加熱終了直前の絶縁抵抗が0.4MΩ以上であること、さらに炉内壁より150mm以上延焼しないだけの燃焼性を有することである。ここで、多心型耐火電線の場合は、隣接する線心を二つに分け、接地・線心間の絶縁抵抗を実測し、その測定値に非接地側の線心数を乗じた値を絶縁抵抗とすることが定められている。
【0004】
耐火電線の実線路での布設状態は、露出配線のような電線がむき出しで開放された状態で布設される場合と、電線管配線のような電線が密閉した状態で布設される場合の2種類ある。耐火試験においても、露出配線を模擬した露出試験と、電線管配線を模擬した電線管試験の2つの試験がある。2つの試験が共に上記の耐火性能を満たすとき、電線管用耐火電線として認定される。
【0005】
【発明が解決しようとする課題】
シースに塩化ビニル樹脂組成物を使用した電線は、火災において被炎時にハロゲンガスや大量の煙を発生するために、消火活動などを妨げ、二次災害が問題になってきている。このため最近は、シース材料にその分子構造内にハロゲン元素を含まないエチレン系樹脂組成物を使用した耐火電線が製造されている。
しかし、通常の耐火電線は、シースに塩化ビニル樹脂組成物を使用した場合も、分子構造内にハロゲン元素を含まないエチレン系樹脂組成物を使用した場合も、シース材料に求められる耐燃性能は、JIS C 3342(600Vビニル絶縁ビニルシースケーブルの規格)やJIS C 3621(600VEPゴム絶縁ケーブルの規格)における難燃の規定に適合する水平及び傾斜試験に合格し、耐火試験で規定する前記の燃焼特性を具備していればよいことになっているが、電線の難燃性が未だ不十分のために、近時、火災時の電線延焼による被害拡大が問題となってきている。
【0006】
そこで、シースの構成材料にハロゲン元素を含まない材料を使用し、同時にIEEE383に定められた垂直トレイ難燃性試験に合格する高度の難燃性能を持つ耐火電線が要求されている。
しかし、IEEE383に定められた垂直トレイ難燃性試験に合格する高難燃耐火電線とする為に、そのシースに高難燃性エチレン系樹脂組成物を用いた場合、耐火性能が低下してしまうという予期せぬ問題が生じた。
そこで、本発明は上記問題に鑑み、優れた耐火性能を維持し、かつIEEE383に定められた垂直トレイ難燃性試験に合格する高難燃性を有する、ノンハロゲンの耐火電線を提供することを目的とする。
【0007】
【発明を解決するための手段】
上記目的を達成するために、発明者らは上記した耐火性能低下の原因を追求したところ、以下のような事実、すなわち、IEEE383に合格するような高難燃性エチレン系樹脂組成物は、一般に、難燃性が低い組成物と比較して着火温度(ASTM D 1929 に定められた試験による)が高いものとなっており、着火温度が高いシースを使用した電線を耐火試験に供した場合においては、JIS A 1304に定める火災温度曲線に準じて耐火炉の温度を上昇させた時に、より高温の状態で電線に着火する。電線に着火した後、電線自身の燃焼により、電線周辺ならびに耐火層の温度が、急激に上昇するが、高温で着火が起きた場合は、低温で着火が起きた場合に比べて、電線周辺ならびに耐火層の最高到達温度が高くなる。耐火層に使用されるテープ類の主材料であるマイカは、絶縁性能に温度依存性があり、温度が上昇すると絶縁抵抗が減少する。このため、耐火層の著しい温度上昇は、急激な絶縁抵抗の低下を引き起こし、結果として電線の耐火性能を著しく低下させるという事実、を突き止め、本発明を完成させた。
本発明の耐火電線は、導体上にマイカを主材料とする耐火層、絶縁層を順次設け、その外側にシースを設けた耐火電線において、前記絶縁層は、エチレン系樹脂100重量部に対して金属水酸化物を50〜150重量部配合したエチレン系樹脂組成物で形成され、前記シースは、ASTM D 1929 に定められた試験で着火点420℃以上のエチレン系樹脂組成物で形成されていることを特徴とする。
【0008】
本発明の耐火電線は、シースに着火温度の高い高難燃の材料を使用しており、被炎時には高温で着火、燃焼するが、耐火層の近傍にある絶縁層に、エチレン系樹脂をベース材にしてこれに金属水酸化物を配合することで、金属水酸化物の加熱分解による吸熱と、その際に発生する水分の蒸発潜熱の作用により、周囲温度を降下させることができる。その結果、耐火層の温度上昇を防ぎ、主材料であるマイカの高温化による絶縁抵抗の著しい低下を防止できる。すなわち、本発明の耐火電線は、シースに高難燃材料を用いた場合の耐火層の絶縁抵抗低下を、絶縁層に金属水酸化物の特定量を配合することによって回避した高難燃ノンハロゲンの耐火電線である。
【0009】
【発明の実施の形態】
本発明の耐火電線は、従来の耐火電線と構造自体は変わらない。即ち、単線もしくは撚線からなる導体上にプラスチックフィルムもしくはガラスクロスに集成マイカを張り合わせたいわゆるマイカテープをラップ巻きした耐火層を形成し、該耐火層外周に絶縁層を設けた絶縁線心上にシースを設けた構造、もしくは前記の絶縁線心を数本撚り合わせ、その外側に介在物、押さえ巻きテープ等を介してシースを設けた構造となっている。
【0010】
本発明の耐火電線においては、絶縁層材料として、金属水酸化物を配合したエチレン系樹脂組成物を用いるとともに、シース材料として、ASTM D 1929 に定められた試験で測定した着火点が420℃以上のエチレン系樹脂組成物を用いる。絶縁層を形成するエチレン系樹脂組成物のベース樹脂としては、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、エチレンメ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の群から選ばれた少なくとも一種からなるエチレン系共重合体を主成分とし、必要に応じてポリエチレン、エチレンプロピレン共重合体、ポリプロピレン、不飽和カルボン酸またはその誘導体等によって変性されたポリオレフィンを適当量配合したエチレン系樹脂を用いる。
【0011】
絶縁層に配合する金属水酸化物としては、例えば水酸化マグネシウム、水酸化アルミニウム、水酸化ニッケル、水酸化カルシウム、水酸化鉄等、またはこれらの固溶体等を挙げることができるが、絶縁層の加工時、押出温度において金属水酸化物の加熱分解が進まないものを選択し使用する。
また、絶縁層における金属水酸化物の配合量は、上記のエチレン系樹脂100重量部に対して50〜150重量部の範囲とすることが好ましい。配合量が50重量部未満では電線の絶縁抵抗低下防止効果が不十分であり、150重量部を超えると、引張強さ、引張伸びなどの絶縁層の機械的物性が低下する。
【0012】
さらに絶縁層のエチレン系樹脂組成物には、難燃性を向上させるために、各種の難燃剤、難燃助剤を併用することも可能である。難燃剤、難燃助剤の具体例としては、ほう酸亜鉛、炭酸カルシウム、ハイドロタルサイト、酸化マグネシウム、酸化モリブデン、酸化アンチモン、赤リン等をあげることができ、これらを単独で、または2種以上混合して使用することができる。
また、絶縁層のエチレン系樹脂組成物には、上記した成分に加えて、その他の充填剤、酸化防止剤、滑剤、分散剤、着色剤等の添加剤を必要に応じて使用することも可能である。
【0013】
本発明におけるシースを形成するエチレン系樹脂組成物のベース樹脂として、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、エチレンメ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の群から選ばれた少なくとも一種からなるエチレン系共重合体を主成分とし、必要に応じてポリエチレン、エチレンプロピレン共重合体、ポリプロピレン、不飽和カルボン酸またはその誘導体等によって変性されたポリオレフィンを適当量配合したエチレン系樹脂を用いる。
【0014】
また、本発明のシースのエチレン系樹脂組成物には、難燃剤、難燃助剤を配合する。難燃剤、難燃助剤の具体例としては、水酸化マグネシウムのような金属水酸化物、ほう酸亜鉛、炭酸カルシウム、ハイドロタルサイト、酸化マグネシウム、酸化モリブデン、酸化アンチモン、赤リン等をあげることができ、これらを単独で、または2種以上混合して使用することができる。このときシースのエチレン系樹脂組成物はASTM D 1929 に定められた試験における着火温度が420℃以上であることを要する。着火温度が420℃未満であると、IEEE383に規定する垂直トレイ燃焼性試験に合格するような高難燃性を発揮することができない。
【0015】
【実施例】
以下に、本発明を実施例に基づいて、さらに具体的に説明する。
実施例1〜4、比較例1〜3
まず直径1.0mmの軟銅単線導体上に、厚さ0.13mmのプラスチックフィルムベースのマイカテープを1/2ラップ巻きにて2枚重ね巻きをして耐火層を形成する。その上に表1に示す材料組成の絶縁層を押し出し被覆し絶縁線心を得た。 得られた絶縁線心7本を、ポリプロピレン紐を介在とし撚り合わせ、ポリエステルテープで押さえ巻きし、続いてその上にシース材料を押出成形して7×1.0mmの導体からなる耐火電線を得た。シースに使用したエチレン系樹脂組成物は、実施例1〜4、比較例2〜3では、ASTM D 1929 に定められた試験で着火温度が450℃のもの(種類A)を使用し、比較例1では、ASTM D 1929 に定められた試験で着火温度が400℃のもの(種類B)を使用した。
【0016】
なお、シースの種類Aとしては、エチレンエチルアクリレート共重合体(=EEA:EA含量15%)100重量部に対して、水酸化マグネシウム(協和化学社製キスマ5A)50重量部、赤リン(燐化学工業社製ノーバレッド120UF)5重量部、カーボンブラック(旭カーボン社製旭70)5重量部、ステアリン酸カルシウム0.5重量部、酸化防止剤(チバガイギー社製イルガノックス1010)1重量部の割合で配合したエチレン系樹脂組成物を用い、種類Bとしては、エチレンエチルアクリレート共重合体(同上)100重量部に対して、水酸化マグネシウム(同上)50重量部、カーボンブラック(旭カーボン社製旭70)5重量部、ステアリン酸カルシウム0.5重量部、酸化防止剤(チバガイギー社製イルガノックス1010)1重量部の割合で配合したエチレン系樹脂組成物を用いた。
【0017】
得られた各例の耐火電線は、耐火試験、引張試験、IEEE383に定められた垂直トレイ難燃性試験を評価し、その結果を表1に示した。
耐火試験としては、消防庁告示第7号第3に準拠し、露出試験を行った。この試験は、1.3mの耐火電線試料をパーライト板に水平にとりつけ、その2倍の荷重を加えて、これをJIS A 1305に定める耐火炉内に収納し、JIS A 1304に定める火災温度曲線に準じて30分間加熱し、加熱中にAC600V30分間、加熱後にAC1500Vを1分間印加し、これに耐え、さらに加熱終了直前の接地−線心間の絶縁抵抗と非接地側の線心数を乗じた値が0.4MΩ以上であることを基準として評価するもので、この基準を満たしたものを○、満たさないものを×で示した。
【0018】
引張試験では、電気用品の技術基準付表第14の試験を行ったとき、その試験結果がポリエチレン混合物絶縁のその他のものの基準の値である、室温における引張強さが10MPa以上、伸びが350%以上のものを○とし、一方でも満たさない時を×とした。
IEEE383に定められた垂直トレイ難燃性試験では、電線が自己鎮火後、その電線シースの損傷長が、トレイ上端まで達していない場合○とし、トレイ上端まで達した場合×とした。
【0019】
【表1】

Figure 0003580608
【0020】
表1の結果から以下のことがわかる。比較例1では、シース材料に着火点400℃のエチレン系樹脂組成物を用いているため、耐火試験、引張試験は基準を満たすが、IEEE383に定められた垂直トレイ難燃性試験は不合格となる。また、各実施例と比較例2〜3の対比から、絶縁層の樹脂組成物中の金属水酸化物の配合量が本発明の範囲より少ないと耐火性能低下を防ぐに不十分であり、多すぎると引張試験の結果が基準値を満たさず、絶縁層の機械的物性が低下することがわかる。
【0021】
【発明の効果】
以上の結果から明らかなように、本発明の耐火電線は、シースに着火点420℃以上のエチレン系樹脂組成物を使用しているので、IEEE383に定められた垂直トレイ難燃性試験に合格する高い難燃性を有するとともに、絶縁層に金属水酸化物を特定量配合したエチレン系樹脂組成物を用いたことにより、耐火層の温度上昇を抑え、マイカの高温化による絶縁抵抗の低下を防止できるため、きわめて優れた耐火性能を有する。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fire-resistant electric wire in which a fire-resistant layer and an insulating layer are sequentially provided on a conductor, and a sheath is provided outside the conductor. More particularly, the present invention relates to a highly flame-retardant fire-resistant electric wire in which the material used for the insulating layer and the sheath is improved. It is.
[0002]
[Prior art]
A conventional fire-resistant wire has a structure in which a fire-resistant layer is formed on a conductor, and a sheath is provided on an insulation wire provided with an insulation layer on the outer periphery of the fire-resistant layer, or several insulated wires are twisted together. It has a structure in which a sheath is provided on the outside via an inclusion, a holding tape, or the like. Usually, a tape in which laminated mica is adhered to one side of a plastic film or glass cloth is used for the refractory layer, polyethylene and cross-linked polyethylene are used for the insulating layer, and a vinyl chloride resin composition and a polyethylene resin are used for the sheath. A composition is used.
[0003]
The fire-resistant electric wire is used as an emergency power cable, and has a fire-resistant property capable of supplying power for 30 minutes in case of fire. Therefore, the required characteristics of the fire-resistant electric wire satisfy not only the general physical properties specified in the Electrical Appliance and Material Control Law, etc., but also the performance specified in the fire-resistant electric wire notification No. 7 fire-resistant electric wire standard. This fire resistance performance is evaluated by a fire resistance test defined by the “Fire and Heat Resistant Wire Certification Committee” of the Japan Cable Manufacturers Association. In this fire resistance test, 1.3 m of a refractory electric wire is heated by a refractory furnace for 30 minutes in accordance with a fire temperature curve specified in JIS A 1304, and the insulation strength, insulation resistance and flammability at that time are evaluated. The standard defined as the required performance of a fireproof electric wire is that it has a dielectric strength that does not cause dielectric breakdown when a voltage of 600 V AC is applied during heating for 30 minutes and 1500 V AC before and after heating, and an insulation resistance immediately before the completion of heating for 30 minutes is 0. 0.4 MΩ or more, and further, has such a flammability that it does not spread more than 150 mm from the inner wall of the furnace. Here, in the case of a multi-core type refractory wire, the adjacent core is divided into two, the insulation resistance between the ground and the core is measured, and the measured value is multiplied by the number of the non-ground side cores. It is prescribed that the insulation resistance be used.
[0004]
There are two types of laying of fire-resistant electric wires on actual tracks: when laying exposed wires such as exposed wiring and in an open state, and when laying closed wires such as conduit wiring. is there. Also in the fire resistance test, there are two tests, an exposure test simulating exposed wiring and a conduit test simulating conduit wiring. If both tests meet the above fire performance, they are qualified as fire conduit for conduit.
[0005]
[Problems to be solved by the invention]
An electric wire using a vinyl chloride resin composition for a sheath generates halogen gas or a large amount of smoke in a fire when fired, which hinders fire extinguishing activities and causes secondary disasters. Therefore, recently, fire-resistant electric wires using an ethylene-based resin composition containing no halogen element in its molecular structure as a sheath material have been manufactured.
However, ordinary fire-resistant electric wires, even when using a vinyl chloride resin composition for the sheath, even when using an ethylene-based resin composition containing no halogen element in the molecular structure, the flame resistance required for the sheath material is as follows: It has passed the horizontal and tilt tests conforming to the flammability requirements of JIS C 3342 (standard for 600V vinyl insulated vinyl sheath cable) and JIS C 3621 (standard for 600VEP rubber insulated cable), and has the above-mentioned combustion characteristics specified in fire resistance test It is suffice to provide the wire, but the flame retardancy of the wire is still inadequate, and recently, the spread of damage due to the spread of the wire during a fire has become a problem.
[0006]
Accordingly, there is a demand for a fire-resistant electric wire that uses a material that does not contain a halogen element as a constituent material of the sheath and has a high flame-retardant performance that simultaneously passes a vertical tray flame-retardant test defined in IEEE 383.
However, when a highly flame-retardant ethylene-based resin composition is used for the sheath in order to obtain a highly flame-retardant fire-resistant electric wire that passes the vertical tray flame retardancy test defined in IEEE 383, the fire resistance performance is reduced. The unexpected problem arose.
In view of the above problems, an object of the present invention is to provide a non-halogen fire-resistant electric wire that maintains excellent fire resistance and has high flame retardancy that passes a vertical tray flame retardancy test defined in IEEE 383. And
[0007]
[Means for Solving the Invention]
In order to achieve the above object, the present inventors have pursued the cause of the above-mentioned decrease in fire resistance performance. As a result, the following facts, that is, a highly flame-retardant ethylene-based resin composition that passes IEEE 383, are generally used. The ignition temperature (according to the test specified in ASTM D 1929) is higher than that of the composition having low flame retardancy, and when the electric wire using the sheath having the high ignition temperature is subjected to the fire resistance test, When the temperature of the refractory furnace is increased in accordance with the fire temperature curve defined in JIS A 1304, the electric wire is ignited at a higher temperature. After the wire is ignited, the temperature around the wire and the refractory layer rises sharply due to the burning of the wire itself, but when ignition occurs at a high temperature, the temperature around the wire and the refractory layer are lower than when the ignition occurs at a lower temperature. The maximum temperature of the refractory layer increases. Mica, which is the main material of tapes used for the refractory layer, has a temperature dependency in insulation performance, and the insulation resistance decreases as the temperature rises. For this reason, the fact that a remarkable rise in the temperature of the refractory layer causes a sharp decrease in insulation resistance and consequently remarkably lowers the fire resistance of the electric wire has been found, and the present invention has been completed.
The fire-resistant wire of the present invention is provided with a fire-resistant layer mainly composed of mica on a conductor and an insulating layer in order, and in a fire-resistant wire provided with a sheath outside thereof, the insulating layer is based on 100 parts by weight of ethylene resin. The sheath is formed of an ethylene-based resin composition containing 50 to 150 parts by weight of a metal hydroxide, and the sheath is formed of an ethylene-based resin composition having an ignition point of 420 ° C. or higher in a test specified in ASTM D 1929. It is characterized by.
[0008]
The fire-resistant electric wire of the present invention uses a highly flame-retardant material having a high ignition temperature for the sheath, and ignites and burns at a high temperature when exposed to a flame, but the insulating layer near the fire-resistant layer is based on an ethylene-based resin. By blending the metal hydroxide with the material, the ambient temperature can be lowered by the action of heat absorption by heat decomposition of the metal hydroxide and latent heat of evaporation of water generated at that time. As a result, it is possible to prevent the temperature of the refractory layer from rising, and to prevent a remarkable decrease in insulation resistance due to a high temperature of mica as a main material. That is, the fire-resistant electric wire of the present invention is a highly flame-retardant non-halogen, which is capable of avoiding a decrease in insulation resistance of a fire-resistant layer when a highly flame-retardant material is used for a sheath by blending a specific amount of a metal hydroxide in the insulation layer. It is a fire-resistant electric wire.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The structure of the fire-resistant electric wire of the present invention is not different from that of the conventional fire-resistant electric wire. That is, a so-called mica tape formed by laminating so-called mica tape formed by laminating a mica tape on a plastic film or a glass cloth on a conductor made of a single wire or a stranded wire is formed, and an insulating layer provided on the outer periphery of the fire-resistant layer is provided on an insulated wire core. It has a structure in which a sheath is provided, or a structure in which several of the above-mentioned insulated wires are twisted, and a sheath is provided on the outside thereof via an inclusion, a holding tape, or the like.
[0010]
In the fire-resistant electric wire of the present invention, as the insulating layer material, an ethylene-based resin composition containing a metal hydroxide is used, and as a sheath material, the ignition point measured by a test defined in ASTM D 1929 is 420 ° C. or higher. An ethylene-based resin composition is used. The base resin of the ethylene-based resin composition forming the insulating layer was selected from the group consisting of ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl acrylate copolymer, and ethylene methyl methacrylate copolymer. An ethylene-based resin containing, as a main component, an ethylene-based copolymer composed of at least one kind, and, if necessary, polyethylene, an ethylene-propylene copolymer, polypropylene, and an appropriate amount of a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof, etc. Used.
[0011]
Examples of the metal hydroxide to be incorporated in the insulating layer include magnesium hydroxide, aluminum hydroxide, nickel hydroxide, calcium hydroxide, iron hydroxide, and the like, and solid solutions thereof, and the like. At this time, a metal hydroxide that does not undergo thermal decomposition at the extrusion temperature is selected and used.
The amount of the metal hydroxide in the insulating layer is preferably in the range of 50 to 150 parts by weight based on 100 parts by weight of the ethylene resin. If the amount is less than 50 parts by weight, the effect of preventing the insulation resistance of the electric wire from lowering is insufficient, and if it exceeds 150 parts by weight, the mechanical properties of the insulating layer such as tensile strength and tensile elongation are reduced.
[0012]
Furthermore, various flame retardants and flame retardant auxiliaries can be used in combination with the ethylene resin composition of the insulating layer in order to improve the flame retardancy. Specific examples of the flame retardant and the flame retardant auxiliary include zinc borate, calcium carbonate, hydrotalcite, magnesium oxide, molybdenum oxide, antimony oxide, red phosphorus and the like. These may be used alone or in combination of two or more. They can be mixed and used.
In addition, in addition to the above-described components, other additives such as a filler, an antioxidant, a lubricant, a dispersant, and a coloring agent can be used in the ethylene-based resin composition of the insulating layer as necessary. It is.
[0013]
As the base resin of the ethylene-based resin composition forming the sheath in the present invention, selected from the group consisting of ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl acrylate copolymer, and ethylene methyl methacrylate copolymer. Ethylene-based resin containing an ethylene-based copolymer consisting of at least one kind as a main component and, if necessary, a suitable amount of a polyolefin modified with polyethylene, ethylene-propylene copolymer, polypropylene, unsaturated carboxylic acid or a derivative thereof, etc. Is used.
[0014]
Further, a flame retardant and a flame retardant auxiliary are blended in the ethylene resin composition of the sheath of the present invention. Specific examples of flame retardants and flame retardant aids include metal hydroxides such as magnesium hydroxide, zinc borate, calcium carbonate, hydrotalcite, magnesium oxide, molybdenum oxide, antimony oxide, and red phosphorus. These can be used alone or in combination of two or more. At this time, the ethylene-based resin composition of the sheath needs to have an ignition temperature of 420 ° C. or higher in a test specified in ASTM D 1929. If the ignition temperature is lower than 420 ° C., high flame retardancy that passes the vertical tray flammability test specified in IEEE 383 cannot be exhibited.
[0015]
【Example】
Hereinafter, the present invention will be described more specifically based on examples.
Examples 1-4, Comparative Examples 1-3
First, a plastic film-based mica tape having a thickness of 0.13 mm is wound twice on a soft copper single-wire conductor having a diameter of 1.0 mm by a 1/2 wrap winding to form a fire-resistant layer. An insulating layer having the material composition shown in Table 1 was extruded and coated thereon to obtain an insulated core. The obtained seven insulated wires are twisted with a polypropylene string as an interposition, pressed and wound with a polyester tape, and then a sheath material is extruded thereon to obtain a refractory wire made of a 7 × 1.0 mm conductor. Was. In Examples 1-4 and Comparative Examples 2-3, the ethylene-based resin composition used for the sheath used was one having an ignition temperature of 450 ° C. (type A) in the test specified in ASTM D 1929. In No. 1, the one having an ignition temperature of 400 ° C. (type B) in a test specified in ASTM D 1929 was used.
[0016]
As the sheath type A, 50 parts by weight of magnesium hydroxide (Kisuma 5A manufactured by Kyowa Chemical Co., Ltd.) and 100 parts by weight of ethylene ethyl acrylate copolymer (= EEA: EA content: 15%) and red phosphorus (phosphorus) were used. 5 parts by weight of Nova Red 120UF manufactured by Chemical Industry Co., Ltd., 5 parts by weight of carbon black (Asahi 70 manufactured by Asahi Carbon Co.), 0.5 parts by weight of calcium stearate, and 1 part by weight of an antioxidant (Irganox 1010 manufactured by Ciba Geigy) The ethylene resin composition blended in the above was used, and as the type B, 100 parts by weight of an ethylene ethyl acrylate copolymer (same as above), 50 parts by weight of magnesium hydroxide (same as above), and carbon black (Asahi by Asahi Carbon Co., Ltd.) 70) 5 parts by weight, calcium stearate 0.5 parts by weight, antioxidant (Irganox 10 manufactured by Ciba Geigy) 0) was used ethylene resin composition blended at a ratio of 1 part by weight.
[0017]
The fire-resistant electric wire of each of the obtained examples was evaluated for a fire resistance test, a tensile test, and a vertical tray flame retardancy test defined in IEEE 383, and the results are shown in Table 1.
As a fire resistance test, an exposure test was performed in accordance with the Fire and Disaster Management Agency Notification No. 7, No. 3. In this test, a 1.3 m refractory wire sample was horizontally mounted on a pearlite plate, a load twice that of the sample was applied, and this was stored in a refractory furnace specified in JIS A 1305, and a fire temperature curve specified in JIS A 1304 was used. Heat for 30 minutes, apply AC600V for 30 minutes during heating, apply AC1500V for 1 minute after heating, endure this, and multiply the insulation resistance between the ground and the core immediately before the end of heating by the number of non-grounded cores. Is evaluated on the basis that the measured value is 0.4 MΩ or more.
[0018]
In the tensile test, when the test in Table 14 with the technical standard attached to electrical appliances was performed, the test result was the standard value of the others of the polyethylene mixture insulation. The tensile strength at room temperature was 10 MPa or more and the elongation was 350% or more. Was evaluated as ○, and when none was satisfied, as ×.
In the vertical tray flame retardancy test defined in IEEE 383, after the electric wire self-extinguished, the damage length of the electric wire sheath did not reach the upper end of the tray, and was evaluated as 、.
[0019]
[Table 1]
Figure 0003580608
[0020]
The following can be seen from the results in Table 1. In Comparative Example 1, since the ethylene resin composition having an ignition point of 400 ° C. was used as the sheath material, the fire resistance test and the tensile test met the criteria, but the vertical tray flame retardancy test specified in IEEE 383 failed. . Also, from the comparison of each Example and Comparative Examples 2 and 3, if the amount of the metal hydroxide in the resin composition of the insulating layer is less than the range of the present invention, it is insufficient to prevent the fire resistance performance from being lowered, and If too much, the result of the tensile test does not satisfy the reference value, and it is understood that the mechanical properties of the insulating layer are reduced.
[0021]
【The invention's effect】
As is clear from the above results, the fire-resistant wire of the present invention uses an ethylene-based resin composition having an ignition point of 420 ° C. or higher for the sheath, and therefore, passes the vertical tray flame retardancy test specified in IEEE 383. The use of an ethylene-based resin composition that has flame retardancy and a specific amount of metal hydroxide in the insulating layer suppresses the temperature rise of the refractory layer and prevents a decrease in insulation resistance due to the high temperature of mica. Therefore, it has extremely excellent fire resistance performance.

Claims (1)

導体上にマイカを主材料とする耐火層、絶縁層を順次設け、その外側にシースを設けた耐火電線において、前記絶縁層は、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、エチレンメ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からなる群から選ばれた少なくとも1種を主成分とする樹脂100重量部に対して金属水酸化物を50〜150重量部配合したエチレン系樹脂組成物で形成され、前記シースは、赤リン及び金属水酸化物を含有するエチレン系樹脂組成物であり、かつASTM D 1929に定められた試験で着火点420℃以上であることを特徴とする耐火電線。In a fire-resistant electric wire in which a fire-resistant layer mainly composed of mica and an insulating layer are sequentially provided on a conductor, and a sheath is provided outside the fire-resistant layer, the insulating layer includes an ethylene vinyl acetate copolymer, an ethylene ethyl acrylate copolymer, and an ethylene methyl copolymer. Ethylene-based resin composition in which 50 to 150 parts by weight of a metal hydroxide is blended with respect to 100 parts by weight of a resin containing at least one selected from the group consisting of an acrylate copolymer and an ethylene methyl methacrylate copolymer Wherein the sheath is an ethylene-based resin composition containing red phosphorus and a metal hydroxide, and has an ignition point of 420 ° C. or higher in a test defined by ASTM D 1929.
JP21039895A 1995-08-18 1995-08-18 Fire resistant wire Expired - Fee Related JP3580608B2 (en)

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