JPH0511752B2 - - Google Patents
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- Publication number
- JPH0511752B2 JPH0511752B2 JP62259353A JP25935387A JPH0511752B2 JP H0511752 B2 JPH0511752 B2 JP H0511752B2 JP 62259353 A JP62259353 A JP 62259353A JP 25935387 A JP25935387 A JP 25935387A JP H0511752 B2 JPH0511752 B2 JP H0511752B2
- Authority
- JP
- Japan
- Prior art keywords
- heat treatment
- organic
- organic polymer
- oxygen
- crosslinking agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 229920000620 organic polymer Polymers 0.000 claims description 29
- 238000010438 heat treatment Methods 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 20
- 239000003431 cross linking reagent Substances 0.000 claims description 16
- 150000001451 organic peroxides Chemical class 0.000 claims description 16
- XMNIXWIUMCBBBL-UHFFFAOYSA-N 2-(2-phenylpropan-2-ylperoxy)propan-2-ylbenzene Chemical group C=1C=CC=CC=1C(C)(C)OOC(C)(C)C1=CC=CC=C1 XMNIXWIUMCBBBL-UHFFFAOYSA-N 0.000 claims description 9
- 238000000354 decomposition reaction Methods 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 6
- -1 polyethylene Polymers 0.000 claims description 6
- 239000002530 phenolic antioxidant Substances 0.000 claims description 5
- 239000004698 Polyethylene Substances 0.000 claims description 4
- 229920000573 polyethylene Polymers 0.000 claims description 4
- 239000011247 coating layer Substances 0.000 claims description 3
- 239000000470 constituent Substances 0.000 claims description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 238000006297 dehydration reaction Methods 0.000 description 9
- 239000000203 mixture Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- 239000003963 antioxidant agent Substances 0.000 description 7
- 238000004132 cross linking Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- OIGWAXDAPKFNCQ-UHFFFAOYSA-N 4-isopropylbenzyl alcohol Chemical compound CC(C)C1=CC=C(CO)C=C1 OIGWAXDAPKFNCQ-UHFFFAOYSA-N 0.000 description 5
- XYLMUPLGERFSHI-UHFFFAOYSA-N alpha-Methylstyrene Chemical compound CC(=C)C1=CC=CC=C1 XYLMUPLGERFSHI-UHFFFAOYSA-N 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 238000009413 insulation Methods 0.000 description 5
- 239000012299 nitrogen atmosphere Substances 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000010292 electrical insulation Methods 0.000 description 4
- 229920001684 low density polyethylene Polymers 0.000 description 4
- 239000004702 low-density polyethylene Substances 0.000 description 4
- RLSSMJSEOOYNOY-UHFFFAOYSA-N m-cresol Chemical compound CC1=CC=CC(O)=C1 RLSSMJSEOOYNOY-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- GJYCVCVHRSWLNY-UHFFFAOYSA-N 2-butylphenol Chemical compound CCCCC1=CC=CC=C1O GJYCVCVHRSWLNY-UHFFFAOYSA-N 0.000 description 2
- HXIQYSLFEXIOAV-UHFFFAOYSA-N 2-tert-butyl-4-(5-tert-butyl-4-hydroxy-2-methylphenyl)sulfanyl-5-methylphenol Chemical compound CC1=CC(O)=C(C(C)(C)C)C=C1SC1=CC(C(C)(C)C)=C(O)C=C1C HXIQYSLFEXIOAV-UHFFFAOYSA-N 0.000 description 2
- GPNYZBKIGXGYNU-UHFFFAOYSA-N 2-tert-butyl-6-[(3-tert-butyl-5-ethyl-2-hydroxyphenyl)methyl]-4-ethylphenol Chemical compound CC(C)(C)C1=CC(CC)=CC(CC=2C(=C(C=C(CC)C=2)C(C)(C)C)O)=C1O GPNYZBKIGXGYNU-UHFFFAOYSA-N 0.000 description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 229920000098 polyolefin Polymers 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 150000003509 tertiary alcohols Chemical class 0.000 description 2
- XCPFSALHURPPJE-UHFFFAOYSA-N (3,5-ditert-butyl-4-hydroxyphenyl) propanoate Chemical compound CCC(=O)OC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 XCPFSALHURPPJE-UHFFFAOYSA-N 0.000 description 1
- KGRVJHAUYBGFFP-UHFFFAOYSA-N 2,2'-Methylenebis(4-methyl-6-tert-butylphenol) Chemical compound CC(C)(C)C1=CC(C)=CC(CC=2C(=C(C=C(C)C=2)C(C)(C)C)O)=C1O KGRVJHAUYBGFFP-UHFFFAOYSA-N 0.000 description 1
- OPLCSTZDXXUYDU-UHFFFAOYSA-N 2,4-dimethyl-6-tert-butylphenol Chemical compound CC1=CC(C)=C(O)C(C(C)(C)C)=C1 OPLCSTZDXXUYDU-UHFFFAOYSA-N 0.000 description 1
- XRCRJFOGPCJKPF-UHFFFAOYSA-N 2-butylbenzene-1,4-diol Chemical compound CCCCC1=CC(O)=CC=C1O XRCRJFOGPCJKPF-UHFFFAOYSA-N 0.000 description 1
- PFANXOISJYKQRP-UHFFFAOYSA-N 2-tert-butyl-4-[1-(5-tert-butyl-4-hydroxy-2-methylphenyl)butyl]-5-methylphenol Chemical compound C=1C(C(C)(C)C)=C(O)C=C(C)C=1C(CCC)C1=CC(C(C)(C)C)=C(O)C=C1C PFANXOISJYKQRP-UHFFFAOYSA-N 0.000 description 1
- BVCOHOSEBKQIQD-UHFFFAOYSA-N 2-tert-butyl-6-methoxyphenol Chemical compound COC1=CC=CC(C(C)(C)C)=C1O BVCOHOSEBKQIQD-UHFFFAOYSA-N 0.000 description 1
- NLZUEZXRPGMBCV-UHFFFAOYSA-N Butylhydroxytoluene Chemical compound CC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 NLZUEZXRPGMBCV-UHFFFAOYSA-N 0.000 description 1
- 239000004971 Cross linker Substances 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 240000005572 Syzygium cordatum Species 0.000 description 1
- 235000006650 Syzygium cordatum Nutrition 0.000 description 1
- 239000007983 Tris buffer Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- FQUNFJULCYSSOP-UHFFFAOYSA-N bisoctrizole Chemical compound N1=C2C=CC=CC2=NN1C1=CC(C(C)(C)CC(C)(C)C)=CC(CC=2C(=C(C=C(C=2)C(C)(C)CC(C)(C)C)N2N=C3C=CC=CC3=N2)O)=C1O FQUNFJULCYSSOP-UHFFFAOYSA-N 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000010382 chemical cross-linking Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 229920006037 cross link polymer Polymers 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000005038 ethylene vinyl acetate Substances 0.000 description 1
- 229920006244 ethylene-ethyl acrylate Polymers 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- NFHFRUOZVGFOOS-UHFFFAOYSA-N palladium;triphenylphosphane Chemical compound [Pd].C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1.C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1.C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1.C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1 NFHFRUOZVGFOOS-UHFFFAOYSA-N 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
Landscapes
- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Treatments Of Macromolecular Shaped Articles (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
Description
【発明の詳細な説明】
産業上の利用分野
本発明は有機過酸化物分解残渣を含有する有機
高分子、たとえば架橋性ポリエチレン組成物など
の新規な加熱処理方法に関する。
従来の技術
電気絶縁性が要求される架橋有機高分子、たと
えば絶縁ケーブルの絶縁被覆の構成材料に於いて
はできるだけ水分含有量が少ないことが必要であ
る。その理由は、水分含有量が多いと絶縁被覆中
にボイドが発生し、送電時などの電圧印加状態に
おいて水ツリーと称される現象が生じて電気特性
特に絶縁破壊強度が大幅に低下してしまうからで
ある。
絶縁ケーブルの絶縁被覆層は、耐熱性を向上さ
せるために、通常はその構成材料を架橋して使用
する。現在、該絶縁被覆層構成材料の架橋方法と
して高圧絶縁ケーブルの製造に最も広く採用され
ているのは有機過酸化物架橋剤を用いた化学架橋
方法であるが、本発明者らは先に有機過酸化物架
橋剤を配合した有機高分子を酸素の存在下で加熱
すると、あるいは有機過酸化物架橋剤の分解残渣
を含んだ有機高分子を酸素の存在下で加熱すると
多量の水分が発生し、それが有機高分子中に残存
することを知つた。
本発明者らの研究によれば、水分の発生は、有
機過酸化物架橋剤から生成したアルコールが酸素
存在下では該酸素の触媒作用により分子内脱水反
応を起こすことに起因する。たとえば有機過酸化
物架橋剤がジクミルパーオキサイドの場合、分解
生成物の１種たるキユミルアルコールからα−メ
チルスチレンが生成する際に水が生成する。一般
にこの種の脱水反応は、150℃以上で容易に進行
し、その結果架橋高分子中に水が生成することに
なり、水と高分子との相容性の点から水は凝集
し、ボイドの発生につながるのである。
さらに、ポリエチレンなどの有機過酸化物架橋
剤架橋性有機高分子には、通常、４，4′−チオビ
ス（６−ｔ−ブチル−３−メチル−フエノール）
のような酸化条件下で容易にプロトンを放出して
共嗚安定下する酸化防止剤が配合されているが、
かかる種類の酸化防止剤は上記した分子内脱水反
応を、而して水分生成反応を促進する作用のある
ことも判明した。
解決を要すべき問題点
本発明は、酸化防止剤を配合した有機高分子を
架橋、あるいはそのたの目的で加熱処理しても水
分生成の問題の少ない加熱処理方法を提供しよう
とするものである。
問題点を解決するための手段
本発明は、有機過酸化物架橋剤の分解残渣を含
有する架橋された有機高分子を加熱処理する際
に、該有機高分子中にヒンダードフエノール系酸
化防止剤の存在下でしかも酸素フリーの状態で加
熱することを特徴とする有機高分子の加熱処理方
法である。
作 用
本発明においては、有機過酸化物架橋剤の分解
残渣を含有する有機高分子を酸素フリーの状態で
加熱するので上記した有機過酸化物架橋剤から生
成したアルコールの分子内脱水反応が生じない
か、または軽度で済む。
一方、有機高分子は一般に酸化防止剤が配合さ
れた状態で使用されるが、本発明においては、か
かる酸化防止剤として酸化条件下でもプロトンを
放出し難いヒンダードフエノール系のもの用いる
ので、たとえアルコールの分子内脱水反応が生じ
ることがあつてもその反応を促進するようなこと
がない。したがつて本発明の加熱処理方法を実施
した場合は、有機高分子中の水分含有量は従来の
加熱処理方法と比較して極めて低度に維持され、
この結果、加熱処理後の有機高分子の電気特性に
何等悪影響を及ぼさないという長所がある。
発明の具体的な説明
本発明の加熱処理方法が対象とする有機高分子
は、後記するヒンダードフエノール系酸化防止剤
の他、有機過酸化物架橋剤の分解残渣を含有する
架橋済のものである。
有機高分子としては有機過酸化物架橋剤を用い
て架橋されるもので、特に電気絶縁性を有するも
のがあげられ、たとえばポリオレフインなどにお
いてとくに有用である。ポリオレフインとしては
ポリエチレン、エチレン−プロピレン共重合体、
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などがあげられ、それら
のうち密度が0.88〜0.95のポリエチレンにとくに
顕著な効果を奏する。
ヒンダードフエノール系酸化防止剤としては分
子中に少なくとも１個以上のフエノール性水酸基
を有し、さらにその水酸基のうちの少なくとも１
個以上がその隣接位（すなわちオルソ位）に第３
個（tert−）ブチル基を有する構造を有するもの
が用いられ、具体例としては２，６−ジ−ｔ−ブ
チル−ｐ−クレゾール、２，４−ジメチル−６−
ｔ−ブチルフエノール、４，4′−チオビス（３−
メチル−６−ｔ−ブチルフエノール）、２，2′−
メチレンビス（４−メチル−６−ｔ−ブチルフエ
ノール）、４，4′−ブチリデンビス（３−メチル
−６−ｔ−ブチルフエノール）、テトラキス〔メ
チレン−３（３，５−ジ−ｔ−ブチル−４−ヒド
ロキシフエニルプロピオネート〕メタン、１，
１，３−トリス（２−メチル−４−ヒドロキシ−
５−ｔ−ブチルフエニル）ブタン、ｔ−ブチルヒ
ドロキシアニソールなどがあげられる。
ヒンダードフエノール系酸化防止剤の配合量は
有機高分子100重量部あたり0.1〜10重量部、特に
0.5〜５重量部程度が好ましい。
有機過酸化物架橋剤としては、分解により前記
した脱水反応を生起する分解生成物を生ぜしめる
ものがあげられ、たとえば分解して第３級アルコ
ールを生ずるクミルパーオキサイドやジクミルパ
ーオキサイドなど、就中ジクミルパーオキサイド
があげられる。本発明においては、加熱処理され
る有機高分子中に含まれる有機過酸化物架橋剤の
分解残渣の含有量が10重量％以上の高濃度であつ
ても本発明の方法は効果がある。しかし、それら
の濃度は通常0.1〜５重量％程度であつて、本発
明は勿論そのような濃度範囲において特に顕著な
効果が得られる。
本発明の方法は、前記脱水反応を可能な限り生
起させないために、酸素フリーの状態で有機高分
子を加熱処理することに特徴がある。酸素フリー
の状態としては、酸素の存在量ができるだけ少な
い雰囲気が例示される。その場合、該雰囲気の酸
素含有量が５％（容量％、以下同様）以下、好ま
しくは２％以下、特に0.5％以下とするのかよい。
雰囲気ガスとしては、たとえば、Nz、He、
CO2、Ar、SF6などの不活性ガス中が例示される
が、それ以外のガスでもよい。かかる酸素フリー
の雰囲気ガス下で加熱処理するためにはたとえば
そのようなガスを加熱処理を行う個所に常時送風
する、加熱処理個所を適当なケースなどで囲み、
その内部を上記ガスで置換するなどの方法を採用
することができる。
酸素フリーの他の状態としては、被加熱処理体
が気体不透過性の材料で気体が入らないように密
着カバーされている場合がある。この場合、気体
不透過性の材料、たとえば鉛などの金属のテープ
やナイロン、ポリフツ化ビニリデンなどの樹脂テ
ープを被加熱処理体部分に捲巻して酸素との接触
を断つ方法や、加熱される部分にぴつたり合う金
型を用いるなどの方法がある。
本発明の加熱処理方法が効果を奏しうる加熱処
理温度は、対象とする有機高分子、架橋剤残渣と
して存在する第３級アルコールの種類などによつ
て異なるが、通常100℃以上または有機高分子の
融点以上である。
効 果
本発明の加熱処理方法は、有機高分子組成物成
形体、たとえば高圧絶縁ケーブルの加熱、架橋済
の有機高分子成形体の加熱処理などに適用でき
る。特につぎに述べる架橋済絶縁ケーブル同士の
接続作業に適用して顕著な効果が得られる。
絶縁ケーブルの接続においては、通常まず接続
すべきケーブルの端部の絶縁被覆を剥ぎとり、絶
縁被覆端部をペンシリングする。ついで導体同士
を接続し、最後にペンシリングした部分に有機過
酸化物架橋剤を含む補強用の有機高分子絶縁物を
施し、加熱された金型により加圧して絶縁被覆部
および補強部両者を一体に架橋接合する。従来は
この接続時の加熱により水分が多量に生成して接
続部の電気絶縁不良がしばしばみられたが、本発
明の方法により水分の生成が抑えられて電気絶縁
不良の事故発生率が激減する。
実施例
以下、実施例および比較例により本発明を一層
詳細に説明する。
比較例 １
低密度ポリエチレン100重量部、およびジクミ
ルパーオキサイド2.0重量部とからなる架橋性組
成物を180℃で20分間プレス架橋して厚さ１mm、
１×２cm角の架橋シートを得た。ついでこの架橋
シートを180℃の空気中で40分間加熱した。
比較例 ２
低密度ポリエチレン100重量部およびジクミル
パーオキサイド2.0重量部とからなる架橋性組成
物を180℃で20分間プレス架橋して厚さ１mm、１
×２cm角の架橋シートを得た。ついで、この架橋
シートを180℃に加熱保持された酸素濃度が４容
量％の窒素雰囲気中で40分間加熱した。
比較例 ３
低密度ポリエチレン100重量部、ジクミルパー
オキサイド2.0重量部、および４，4′−チオビス
（６−ｔ−ブチル−１，３−メチルフエノール）
0.3重量部とからなる架橋性組成物を用いた以外
は比較例１と同様にして架橋並びに空気中での加
熱を行つた。
比較例 ４
比較例３で得た架橋シートを180℃に加熱保持
された酸素濃度が４容量％の窒素雰囲気中で40分
間加熱した。
実施例 １
低密度ポリエチレン100重量部およびジクミル
パーオキサイド2.0重量部、および２，2′−メチ
レンビス（４−エチル−６−ｔ−ブチルフエノー
ル）0.3重量部とからなる架橋性組成物を180℃で
20分間プレス架橋して厚さ１mm、１×２cm角の架
橋シートを得た。ついでこの架橋シートを180℃
に加熱保持された酸素濃度が４容量％の窒素雰囲
気中で40分間加熱した。
実施例 ２
２，2′−メチレンビス（４−エチル−６−ｔ−
ブチルフエノール）に代わつて２，2′−メチレン
ビス（４−メチル−６−ｔ−ブチルフエノール）
を用いた以外は実施例１と同様の架橋性組成物を
用い、実施例１と同様にして架橋並びに４容量％
の窒素雰囲気中での加熱を行つた。
実施例 ３
２，2′−メチレンビス（４−エチル−６−ｔ−
ブチルフエノール）に代わつて２，５−ジ−ｔ−
ブチルハイドロキノンを用いた以外は実施例１と
同様の架橋性組成物を用い、実施例１と同様にし
て架橋並びに４容量％の窒素雰囲気中での加熱を
行つた。
比較例１〜４、および実施例１〜３で加熱処理
された各試料につきガスクロマトグラフイーによ
り各試料中に残存するクミルアルコールの量およ
びα−メチルスチレンの量を測定し、〔α−メチ
ルスチレン）／〔クミルアルコール〕のモル比を
を調べた。結果を第１表に示す。
なお、該モル比が大きくなることはクミルアル
コールが脱水反応を起こし、α−メチルスチレン
との水の生成が大きくなることを意味している。
同表よりプロトンを放出し易い酸化防止剤たる
４，4′−チオビス（６−ｔ−ブチル−１，３−メ
チルフエノール）を使用した場合には、クミルア
ルコールの脱水反応に大きな促進作用がみられる
が、各実施例からの試料の〔α−メチルスチレ
ン）／〔クミルアルコール〕のモル比は、酸化防
止剤が配合されたものであるにもかかわらず極め
て小さく、水分の生成に実質促進作用を示さない
ことを示している。
【表】DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a novel method for heat treating organic polymers, such as crosslinkable polyethylene compositions, containing organic peroxide decomposition residues. BACKGROUND OF THE INVENTION Crosslinked organic polymers that require electrical insulation properties, such as materials constituting insulation coatings for insulated cables, need to have as little water content as possible. The reason for this is that when the moisture content is high, voids occur in the insulation coating, and a phenomenon called water tree occurs when voltage is applied during power transmission, resulting in a significant decrease in electrical properties, especially dielectric breakdown strength. It is from. The insulating coating layer of an insulated cable is usually used by crosslinking its constituent materials in order to improve heat resistance. Currently, the chemical crosslinking method using an organic peroxide crosslinking agent is the most widely used crosslinking method for the material constituting the insulation coating layer in the production of high voltage insulated cables. When an organic polymer containing a peroxide crosslinking agent is heated in the presence of oxygen, or an organic polymer containing the decomposition residue of an organic peroxide crosslinking agent is heated in the presence of oxygen, a large amount of water is generated. I learned that it remains in organic polymers. According to the research conducted by the present inventors, the generation of water is caused by the fact that the alcohol produced from the organic peroxide crosslinking agent undergoes an intramolecular dehydration reaction in the presence of oxygen due to the catalytic action of the oxygen. For example, when the organic peroxide crosslinking agent is dicumyl peroxide, water is produced when α-methylstyrene is produced from cucumyl alcohol, which is one type of decomposition product. In general, this type of dehydration reaction easily proceeds at temperatures above 150°C, resulting in the formation of water in the crosslinked polymer, and due to the compatibility between water and the polymer, the water aggregates and voids form. This leads to the occurrence of In addition, organic peroxide crosslinkers such as polyethylene and crosslinkable organic polymers typically include 4,4'-thiobis(6-t-butyl-3-methyl-phenol).
It contains antioxidants that easily release protons under oxidizing conditions such as
It has also been found that these types of antioxidants have the effect of promoting the above-mentioned intramolecular dehydration reaction, and thus the water production reaction. Problems to be Solved The present invention seeks to provide a heat treatment method that reduces the problem of moisture generation even when heat-treated organic polymers containing antioxidants for crosslinking or other purposes. be. Means for Solving the Problems The present invention provides that when heat treating a crosslinked organic polymer containing a decomposition residue of an organic peroxide crosslinking agent, a hindered phenolic antioxidant is added to the organic polymer. This is a method for heat treatment of organic polymers, which is characterized by heating in the presence of oxygen and in an oxygen-free state. Effect In the present invention, since the organic polymer containing the decomposition residue of the organic peroxide crosslinking agent is heated in an oxygen-free state, an intramolecular dehydration reaction of the alcohol generated from the organic peroxide crosslinking agent described above occurs. None or only mild. On the other hand, organic polymers are generally used with antioxidants mixed in, but in the present invention, hindered phenol-based antioxidants that are difficult to release protons even under oxidizing conditions are used. Even if an intramolecular dehydration reaction of alcohol occurs, the reaction is not promoted. Therefore, when the heat treatment method of the present invention is carried out, the water content in the organic polymer is maintained at an extremely low level compared to conventional heat treatment methods,
As a result, there is an advantage that there is no adverse effect on the electrical properties of the organic polymer after heat treatment. DETAILED DESCRIPTION OF THE INVENTION The organic polymer targeted by the heat treatment method of the present invention is a crosslinked one containing decomposition residue of an organic peroxide crosslinking agent in addition to the hindered phenolic antioxidant described below. be. Examples of organic polymers include those that are crosslinked using an organic peroxide crosslinking agent and have particularly electrical insulation properties, and are particularly useful in polyolefins and the like. Polyolefins include polyethylene, ethylene-propylene copolymer,
Examples include ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer, among which polyethylene with a density of 0.88 to 0.95 is particularly effective. Hindered phenolic antioxidants have at least one phenolic hydroxyl group in the molecule, and at least one of the hydroxyl groups.
or more is the third in its adjacent position (i.e. ortho position)
Those having a structure having tert-butyl groups are used, and specific examples include 2,6-di-t-butyl-p-cresol, 2,4-dimethyl-6-
t-Butylphenol, 4,4'-thiobis(3-
methyl-6-t-butylphenol), 2,2'-
Methylenebis(4-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), Tetrakis[methylene-3(3,5-di-t-butyl-4 -Hydroxyphenylpropionate]methane, 1,
1,3-tris(2-methyl-4-hydroxy-
Examples include 5-t-butylphenyl)butane and t-butylhydroxyanisole. The blending amount of hindered phenolic antioxidant is 0.1 to 10 parts by weight per 100 parts by weight of organic polymer, especially
It is preferably about 0.5 to 5 parts by weight. Examples of organic peroxide crosslinking agents include those that produce decomposition products that cause the dehydration reaction described above, such as cumyl peroxide and dicumyl peroxide, which decompose to produce tertiary alcohols. Among them is dicumyl peroxide. In the present invention, the method of the present invention is effective even when the content of the decomposition residue of the organic peroxide crosslinking agent contained in the heat-treated organic polymer is at a high concentration of 10% by weight or more. However, their concentration is usually about 0.1 to 5% by weight, and the present invention can of course obtain particularly remarkable effects within such a concentration range. The method of the present invention is characterized in that the organic polymer is heat-treated in an oxygen-free state in order to prevent the dehydration reaction from occurring as much as possible. An example of an oxygen-free state is an atmosphere in which the amount of oxygen present is as small as possible. In that case, the oxygen content of the atmosphere may be 5% (volume %, the same applies hereinafter) or less, preferably 2% or less, particularly 0.5% or less.
Examples of atmospheric gas include Nz, He,
Examples include inert gases such as CO 2 , Ar, and SF 6 , but other gases may also be used. In order to carry out heat treatment under such an oxygen-free atmospheric gas, for example, such a gas may be constantly blown onto the area to be heat treated, the area to be heated may be surrounded by a suitable case, etc.
A method such as replacing the inside with the above gas can be adopted. As another oxygen-free state, the object to be heated may be tightly covered with a gas-impermeable material to prevent gas from entering. In this case, gas-impermeable materials such as metal tape such as lead or resin tape such as nylon or polyvinylidene fluoride may be wrapped around the object to be heated to cut off contact with oxygen; There are methods such as using a mold that fits the part exactly. The heat treatment temperature at which the heat treatment method of the present invention is effective varies depending on the target organic polymer, the type of tertiary alcohol present as a crosslinking agent residue, etc., but is usually 100°C or higher or is above the melting point of Effects The heat treatment method of the present invention can be applied to heating an organic polymer composition molded article, for example, a high-voltage insulated cable, heat treatment of a crosslinked organic polymer molded article, and the like. In particular, remarkable effects can be obtained when applied to the connection work between cross-linked insulated cables, which will be described below. When connecting insulated cables, the insulation coating is usually first stripped off from the ends of the cables to be connected, and the insulation coating ends are penciled. Next, the conductors are connected, and a reinforcing organic polymer insulator containing an organic peroxide crosslinking agent is applied to the final penciled part, and both the insulating coating and the reinforcing part are pressed together using a heated mold. Cross-linked together. Conventionally, a large amount of moisture was generated due to the heating during this connection, often resulting in poor electrical insulation at the connection part, but the method of the present invention suppresses the generation of moisture and dramatically reduces the incidence of electrical insulation defects. . Examples Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Comparative Example 1 A crosslinkable composition consisting of 100 parts by weight of low-density polyethylene and 2.0 parts by weight of dicumyl peroxide was press-crosslinked at 180°C for 20 minutes to a thickness of 1 mm.
A 1×2 cm square crosslinked sheet was obtained. This crosslinked sheet was then heated in air at 180°C for 40 minutes. Comparative Example 2 A crosslinkable composition consisting of 100 parts by weight of low-density polyethylene and 2.0 parts by weight of dicumyl peroxide was press-crosslinked at 180°C for 20 minutes to a thickness of 1 mm.
A crosslinked sheet measuring 2 cm square was obtained. Next, this crosslinked sheet was heated for 40 minutes in a nitrogen atmosphere with an oxygen concentration of 4% by volume and maintained at 180°C. Comparative Example 3 100 parts by weight of low density polyethylene, 2.0 parts by weight of dicumyl peroxide, and 4,4'-thiobis(6-t-butyl-1,3-methylphenol)
Crosslinking and heating in air were carried out in the same manner as in Comparative Example 1, except that a crosslinkable composition consisting of 0.3 parts by weight was used. Comparative Example 4 The crosslinked sheet obtained in Comparative Example 3 was heated for 40 minutes in a nitrogen atmosphere with an oxygen concentration of 4% by volume and maintained at 180°C. Example 1 A crosslinkable composition consisting of 100 parts by weight of low density polyethylene, 2.0 parts by weight of dicumyl peroxide, and 0.3 parts by weight of 2,2'-methylenebis(4-ethyl-6-t-butylphenol) was heated at 180°C. in
Press crosslinking was performed for 20 minutes to obtain a crosslinked sheet with a thickness of 1 mm and a square size of 1 x 2 cm. Next, this crosslinked sheet was heated to 180℃.
The sample was heated for 40 minutes in a nitrogen atmosphere with an oxygen concentration of 4% by volume. Example 2 2,2'-methylenebis(4-ethyl-6-t-
2,2'-methylenebis(4-methyl-6-t-butylphenol) instead of (butylphenol)
The same crosslinkable composition as in Example 1 was used except that the same crosslinking composition as in Example 1 was used.
Heating was performed in a nitrogen atmosphere. Example 3 2,2'-methylenebis(4-ethyl-6-t-
butylphenol) instead of 2,5-di-t-
The same crosslinkable composition as in Example 1 was used except that butylhydroquinone was used, and crosslinking and heating in a 4% by volume nitrogen atmosphere were carried out in the same manner as in Example 1. For each sample heat-treated in Comparative Examples 1 to 4 and Examples 1 to 3, the amount of cumyl alcohol and the amount of α-methylstyrene remaining in each sample were measured by gas chromatography, and the amount of [α-methylstyrene] The molar ratio of styrene/cumyl alcohol was investigated. The results are shown in Table 1. Incidentally, an increase in the molar ratio means that cumyl alcohol undergoes a dehydration reaction, and the amount of water produced with α-methylstyrene increases.
From the same table, when 4,4'-thiobis(6-t-butyl-1,3-methylphenol), which is an antioxidant that easily releases protons, is used, it has a large accelerating effect on the dehydration reaction of cumyl alcohol. However, the molar ratio of [α-methylstyrene]/[cumyl alcohol] in the samples from each example was extremely small despite the fact that they contained antioxidants, and did not substantially affect water production. This indicates that it does not exhibit any promoting effect. 【table】
Claims (1)
橋された有機高分子を加熱処理する際に、該有機
高分子中にヒンダードフエノール系酸化防止剤の
存在下でしかも酸素フリーの状態で加熱すること
を特徴とする有機高分子の加熱処理方法。 ２ 有機高分子が電気絶縁性のものである特許請
求の範囲第１項に記載の加熱処理方法。 ３ 有機高分子が絶縁ケーブルの絶縁被覆層の構
成材料である特許請求の範囲第２項に記載の加熱
処理方法。 ４ 有機高分子がポリエチレンである特許請求の
範囲第１項、第２項又は第３項に記載の加熱処理
方法。 ５ 有機過酸化物架橋剤がジクミルパーオキサイ
ドである特許請求の範囲第１項、第２項、第３項
又は第４項に記載の加熱処理方法。[Scope of Claims] 1. When heat treating a crosslinked organic polymer containing decomposition residue of an organic peroxide crosslinking agent, in the presence of a hindered phenolic antioxidant in the organic polymer, A method for heat treatment of organic polymers, which is characterized by heating in an oxygen-free state. 2. The heat treatment method according to claim 1, wherein the organic polymer is electrically insulating. 3. The heat treatment method according to claim 2, wherein the organic polymer is a constituent material of the insulating coating layer of the insulated cable. 4. The heat treatment method according to claim 1, 2 or 3, wherein the organic polymer is polyethylene. 5. The heat treatment method according to claim 1, 2, 3, or 4, wherein the organic peroxide crosslinking agent is dicumyl peroxide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25935387A JPH01101338A (en) | 1987-10-14 | 1987-10-14 | Heating process for organic polymer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25935387A JPH01101338A (en) | 1987-10-14 | 1987-10-14 | Heating process for organic polymer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01101338A JPH01101338A (en) | 1989-04-19 |
| JPH0511752B2 true JPH0511752B2 (en) | 1993-02-16 |
Family
ID=17332930
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25935387A Granted JPH01101338A (en) | 1987-10-14 | 1987-10-14 | Heating process for organic polymer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01101338A (en) |
-
1987
- 1987-10-14 JP JP25935387A patent/JPH01101338A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01101338A (en) | 1989-04-19 |
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