EP1025568A1 - Composition destinee a des cables electriques - Google Patents

Composition destinee a des cables electriques

Info

Publication number
EP1025568A1
EP1025568A1 EP98951849A EP98951849A EP1025568A1 EP 1025568 A1 EP1025568 A1 EP 1025568A1 EP 98951849 A EP98951849 A EP 98951849A EP 98951849 A EP98951849 A EP 98951849A EP 1025568 A1 EP1025568 A1 EP 1025568A1
Authority
EP
European Patent Office
Prior art keywords
composition
peroxide
additives
tetramethylpiperidine compound
weight
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.)
Withdrawn
Application number
EP98951849A
Other languages
German (de)
English (en)
Inventor
Ruth Dammert
Bill Gustafsson
Karin Liebig
Annika Smedberg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Borealis AS
Original Assignee
Borealis AS
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Borealis AS filed Critical Borealis AS
Publication of EP1025568A1 publication Critical patent/EP1025568A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
    • H01B3/441—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from alkenes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/16—Nitrogen-containing compounds
    • C08K5/34—Heterocyclic compounds having nitrogen in the ring
    • C08K5/3467—Heterocyclic compounds having nitrogen in the ring having more than two nitrogen atoms in the ring
    • C08K5/3477—Six-membered rings
    • C08K5/3492—Triazines
    • C08K5/34926—Triazines also containing heterocyclic groups other than triazine groups

Definitions

  • the present invention relates to a composition for electric cables, more particularly an ethylene polymer composition for the insulating layer of an electric cable, preferably a medium, or high or very high voltage electric power cable.
  • the composition comprises an ethylene polymer and additives, including a peroxide cross-linking agent and stabilising agents.
  • Electric cables and particularly electric power cables for medium voltage (MV; 1-35 kV) , high voltage (HV; 35-500 kV) and extra high voltage (EHV; >500 kV) may be composed of a plurality of polymer layers extruded around the electric conductor.
  • the elect- ric conductor is usually coated first with an inner semiconductor layer followed by an insulating layer, then an outer semiconductor layer followed by water barrier layers, if any, and on the outside a sheath layer.
  • some HV and EHV cables are enclosed in a tube, usually of aluminium.
  • the layers of the cable are based on different types of ethylene polymers, which usually are crosslinked.
  • ethylene polymer is meant, generally and in connection with the present invention, a polymer based on polyethylene or a copolymer of ethylene, wherein the ethylene monomer constitutes the major part of the mass.
  • ethylene polymers may be composed of homopolymers or copolymers of ethylene, wherein the copolymers may be copolymers of ethylene and one or more monomers which are copolymerisable with ethylene or graft copolymers.
  • LDPE low-density polyethylene, i.e. polyethylene prepared by radical polymerisation at a high pressure
  • LDPE low-density polyethylene, i.e. polyethylene prepared by radical polymerisation at a high pressure
  • the ethylene polymer may be an ethylene copolymer, and in that case it includes from 0 to about 25% by weight, pre- erably about 1-20% by weight of one or more comonomers which are copolymerisable with ethylene.
  • Such monomers are well known to those skilled in the art and no extensive enumeration will be required, but as examples, mention can be made of vinylically unsaturated monomers, such as C 3 -Cs alpha olefins, for instance propene, butene; dienes, for instance 1, 7-octadiene, 1, 9-decadiene; vinylically unsaturated monomers containing functional groups, such as hydroxyl groups, alkoxy groups, carbonyl groups, carboxyl groups and ester groups.
  • vinylically unsaturated monomers such as C 3 -Cs alpha olefins, for instance propene, butene
  • dienes for instance 1, 7-octadiene, 1, 9-decadiene
  • vinylically unsaturated monomers containing functional groups such as hydroxyl groups, alkoxy groups, carbonyl groups, carboxyl groups and ester groups.
  • Such monomers may consist of, for instance, (meth) acrylic acid and alkyl esters thereof, such as methyl-, ethyl- and butyl- (meth) acrylate; vinylically unsaturated, hydrolysable silane compounds, such as vinyl trimethoxysilane; vinyl acetate etc.
  • the ethylene polymer is an ethylene copolymer the amount of polar comonomer should be kept low, such that the polar comonomer comprises at most 10% by weight of the ethylene polymer in order not to increase the dissipation factor too much.
  • the remainder of the composition according to the present invention is made up of the ethylene polymer specified above. This means that the amount of ethylene polymer in the composition should lie in the range from about 95% by weight to about 99.7%, preferably about 96-99% by weight of the composition.
  • the ethylene polymer contains additives the total amount of which usually is about 0.3-5% by weight, preferably about 1-4% by weight.
  • additives include stabilising additives such as antioxidants to counteract degradation due to oxidation, radiation, etc.; lubricating additives, such as stearic acid; additives for water-tree resistance, such as polyethylene glycol, silicones etc.; and crosslinking additives such as peroxides which decompose upon heating and initiate crosslinking of the ethylene plastic of the insulating composition, optional-ly used in combination with unsaturated compounds having the ability to form crosslinks when initiated by radical forming agents.
  • peroxide-crosslinked polymers such as peroxide-crosslinked ethylene polymer insulating layers
  • moisture is generated due to decomposition of the peroxide and interaction with additives in the polymer.
  • the prevailing peroxide-crosslinking agent is dicumyl peroxide, which during crosslinking inter alia gives rise to cumyl alcohol, which in turn is prone to decompose to ⁇ -methylstyrene and water.
  • This reaction is strongly catalysed by acids, i.e. the decomposition and formation of water is strongly increased if the polymer composition of the insulating layer contains acidic substances.
  • Antioxidant additives in polymer compositions of electric cables are usually sulphur containing com- pounds that due to oxidation and decomposition form acids, such as sulphenic acids, and these acidic substances strongly influence the decomposition of peroxide to formation of water and decomposition products such as ⁇ -methylstyrene .
  • HALS hindered amine light stabilising
  • the HALS compound acts not only as an effective light stabilising agent, but also as an effective antioxidant making it possible for the composition to pass stringent requirements for thermo-oxidative stability in spite of the fact that the composition contains little or no conventional antioxidants.
  • the present invention provides a peroxide-crosslinkable ethylene polymer composition for an insulating layer of an electric cable, which composi- tion contains up to about 5% by weight of additives including a peroxide crosslinking agent and stabilising agents, characterised in that the stabilising agents comprise an N-substitued 2,2,6,6-tetramethylpiperidine compound as an antioxidant and light stabilising agent; and that the composition after 21 days at 135°C has a retained ultimate tensile strength of at least 75% and a retained ultimate elongation of at least 75% when tested in accordance with IEC 811.
  • the stabilising agents comprise an N-substitued 2,2,6,6-tetramethylpiperidine compound as an antioxidant and light stabilising agent
  • antioxidants While as indicated above sulphur containing antioxidants are prone to form acidic substances on oxidation and decomposition which accelerate moisture formation by peroxide decomposition, it has been found that certain N-substitued hindered amine stabilisers comprised of 2,2,6,6-tetramethylpiperidine compounds can be used as antioxidants that do not form acidic substances and thus do not contribute to moisture generation but at the same time give excellent ageing resistance.
  • the 2,2,6,6-tetramethylpiperidine compounds are preferably used alone as antioxidants. Different 2, 2, 6, 6-tetrametylpiperidine compounds may be used singly or in combination with each other as stabilising agents in the composition according to the present invention.
  • the composition includes little or no conventional antioxidants.
  • the combined amounts of conventional antioxidants such as phenolic antioxidants, organic phosphite antioxidants and sulphur containing antioxi- dants are at most 0.15% by weight of the composition, preferably at most 0.10% by weight of the composition. Most preferably the composition does not contain any such conventional antioxidant at all.
  • the 2,2,6,6-tetramethylpiperidine compounds can be incorporated in the ethylene polymer composition by compounding together with other additives, such as peroxide crosslinking agent, lubricating additives, additives for water tree resistance, etc.
  • the total amount of antioxidant (s) should lie in a range of about 0.1-1.0% by weight, preferably about 0.1-0.5% by weight .
  • the 2,2,6,6-tetramethylpiperidine compounds of the present invention not only act as effective light stabilising agents, but surprisingly also as very effective antioxidants providing thermo-oxidative stability to the composition.
  • thermo-oxidative stability provided by the N-substituted 2,2,6,6-tetramethylpiperidine compound is usually sufficient for the requirement of an electric cable insulating layer composition, so that no other antioxidants are required for thermo-oxidative stability. That the 2,2,6,6- tetramethylpiperidine compound alone is able to provide sufficient thermo-oxidative stability is particularly surprising in view of the fact that the requirement for thermo-oxidative stability is very rigourus for electric cables which have a service life of about 30-40 years.
  • thermo-oxidative stability is determined according to the International Standard IEC 811.
  • dumbbell test pieces are made of the composition to be evaluated and are tested for thermo-oxidative ageing. Normal test temperature is 135°C but the testing has been performed also at 150°C.
  • the ultimate tensile strength at break and the ultimate elongation at break of the composition are determined before the testing is started and thereafter at predetermined time intervals. The results are expressed as percent retained ultimate tensile strength at break (RUTS) and percent retained ultimate elongation at break (RUE) , the initial values (ageing time 0 days) being given as 100%.
  • the requirement according to IEC 811 is that after 21 days at 135°C the retained ultimate tensile strength at break (RUTS) should be least 75% and that the retained ultimate elongation at break (RUE) should be at least 75%.
  • RUTS retained ultimate tensile strength at break
  • RUE retained ultimate elongation at break
  • An increasingly common request i the cable industry is, however, that 75% RUTS and RUE should be kept also after 10 days at 150°C. It is a requisite that the 2,2,6,6-tetramethylpiperidine compound is N-substituted.
  • the substituent is preferably a C ⁇ -C 8 alkyl, C 6 -C ⁇ 2 cycloalkyl, C ⁇ -C ⁇ o acyl or acyloxy group or a C -C 3 alkoxy group.
  • substituents are preferably C ⁇ -C 8 alkyl or C ⁇ -C 8 alkoxy groups are preferred. Particularly preferred are C ⁇ C 4 alkyl groups, such as methyl, ethyl, propyl or butyl, or C ⁇ -C 4 alkoxy groups, such as methoxy, ethoxy, propoxy or butoxy.
  • Chimassorb 119 is particularly preferred at present as an antioxidant according to the present invention.
  • the N-substituted 2, 2, 6, 6-tetrametyl- piperidine compound should be compatible with the ethylene polymer resin of the composition.
  • compatible in this connection is meant that it should be possible to homogeneously blend the 2,2,6,6-tetramethylpiperidine compound v/ith the ethylene polymer resin without migration or exudation of the 2,2,6,6-tetramethylpiperidine compound.
  • the N-substituted 2,2,6,6- -tetramethylpiperidine compound is preferably incorporated in the ethylene polymer composition by compounding together with the other additives of the composition.
  • compositions for insulating layers of electric cables v/ere made by compounding an ethylene polymer resin consisting of low density polyethylene (LDPE) (density 922 kg/m 3 , MFR 2 0.9 g/10 min) v/ith various additives listed in Table 1.
  • LDPE low density polyethylene
  • compositions according to the present invention (A, B and C) and tv/o comparative compositions (D and E) v/ere made.
  • the contents of the polymer compositions A-E are shown in Table 1. Table 1
  • composition in % by weight Component A B_ C D E
  • compositions B-E The following properties of the compositions B-E were evaluated: the peroxide response determined as the change in G ⁇ ttfert elastograph-value in Nm after 10 min at 180°C; and the ⁇ -methylstyrene content after 40 min at 220°C and 250°C, respectively (which is a measure of moisture generation originating from the decomposition of the peroxide), determined by HPLC analysis. The results are shown in Table 2.
  • compositions A-D in Example 1 were also tested in a thermo-oxidative ageing test.
  • heat ageing properties were determined.
  • Dumbbell test pieces were punched out from crosslinked, compression moulded plaques made of the compositions and tested for thermo-oxidative ageing at 135°C (Compositions C and D) and at 150°C (Compositions A-D) for various periods of time.
  • the ultimate tensile strength and the ultimate elongation at break of the compositions were determined before the testing started and subsequently at predetermined time intervals.
  • Table 2 the values are expressed as percent retained ultimate tensile strength at break (RUTS) and percent retained ultimate elongation at break (RUE) The initial values, ageing time 0 days, being given as 100%.
  • the scorch properties were evaluated at 135°C in a Brabender Plasticorder PL 2000-6.
  • the oil-heated kneader 350, 287 cm 3 with walzenkneaders W 7646 was used.
  • the torque was measured as a function of time and the reported value, T10, is the time when an 10 Nm increase in torque, using the minimum value as a reference point, was observed.
  • Composition B was tested with and without the methylstyrene dimer present in a scorch test.
  • the scorch retardant effect of the methylstyrene dimer is easily seen from the tests since a TIO value of 33 min was measured in the composition without the methylstyrene dimer compared to a TIO value of 55 min for the composi- tion containing the methylstyrene dimer.

Abstract

L'invention concerne une composition polymère d'éthylène réticulable par péroxide et destinée à un câble électrique. La composition est caractérisée en ce que les additifs de la composition comprennent un composé 2, 2,6,6-tétraméthylpipéridine substitué par N comme antioxydant et un stabilisant UV; en ce que la composition après 21 jours à 135 °C a une résistance à la traction finale conservée d'au moins 75 % et un allongement final conservé d'au moins 75 % une fois testée selon la norme CEI 811. Cet additif agit comme un agent combiné stabilisant UV et thermo-oxydant et inhibe la génération de moisissure réduisant ainsi le risque de formation de nervures d'eau. De préférence, la composition ne contient aucun antioxydant classique tel que les antioxydants phénoliques, les oxydants phosphites organiques et les antioxydants contenant du soufre.
EP98951849A 1997-10-22 1998-10-21 Composition destinee a des cables electriques Withdrawn EP1025568A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9703844A SE9703844D0 (sv) 1997-10-22 1997-10-22 Composition for electric cables
SE9703844 1997-10-22
PCT/SE1998/001894 WO1999021194A1 (fr) 1997-10-22 1998-10-21 Composition destinee a des cables electriques

Publications (1)

Publication Number Publication Date
EP1025568A1 true EP1025568A1 (fr) 2000-08-09

Family

ID=20408696

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98951849A Withdrawn EP1025568A1 (fr) 1997-10-22 1998-10-21 Composition destinee a des cables electriques

Country Status (13)

Country Link
EP (1) EP1025568A1 (fr)
JP (1) JP2001521264A (fr)
KR (1) KR20010052091A (fr)
CN (1) CN1114928C (fr)
AU (1) AU726326B2 (fr)
BR (1) BR9812937A (fr)
CA (1) CA2306125A1 (fr)
NO (1) NO20001913L (fr)
PL (1) PL340078A1 (fr)
RU (1) RU2191439C2 (fr)
SE (1) SE9703844D0 (fr)
TW (1) TW589645B (fr)
WO (1) WO1999021194A1 (fr)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6455616B1 (en) * 2000-03-07 2002-09-24 Union Carbide Chemicals & Plastics Technology Corporation Polyethylene crosslinkable composition
US6858296B1 (en) 2000-10-05 2005-02-22 Union Carbide Chemicals & Plastics Technology Corporation Power cable
US6656986B2 (en) * 2001-03-01 2003-12-02 Union Carbide Chemicals & Plastics Technology Corporation Polyethylene crosslinkable composition
CN100347792C (zh) * 2005-02-24 2007-11-07 无锡江南电缆有限公司 轨道交通用阻燃电力电缆及制备方法
CN103222012B (zh) * 2010-11-25 2015-09-02 普睿司曼股份公司 具有电压稳定的热塑性电绝缘层的能量电缆
HUE025342T2 (hu) 2010-12-23 2016-02-29 Prysmian Spa Stabilizált dielektromos ellenállással rendelkezõ elektromos kábel
RU2505565C1 (ru) * 2012-12-07 2014-01-27 Закрытое акционерное общество "МЕТАКЛЭЙ" (ЗАО "МЕТАКЛЭЙ") Силанольносшиваемая композиция для кабельной изоляции
EP3044258B1 (fr) 2013-09-13 2017-09-06 Dow Global Technologies LLC Compositions réticulables par peroxyde et leurs procédés de production
WO2016204951A1 (fr) * 2015-06-17 2016-12-22 Dow Global Technologies Llc Compositions d'isolation de câble comprenant un antioxydant à base de phosphore
TR201815867T4 (tr) 2016-01-15 2018-11-21 Buss Ag Çapraz bağlanabilir polietilen bileşikleri üretim tertibatı ve yöntemi.
MX2019012569A (es) 2017-04-27 2020-01-21 Dow Global Technologies Llc Composicion de mezcla de polietileno.
EP3401929A1 (fr) 2017-05-09 2018-11-14 Borealis AG Isolation des câbles
BR112020012194A2 (pt) * 2017-12-18 2020-11-24 Borealis Ag composição reticulável com formação de metano e antioxidante e artigo

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0214099A3 (fr) * 1985-08-28 1988-09-21 Ciba-Geigy Ag Stabilisation de polymères d'éthylène réticulés
JPH01100803A (ja) * 1987-10-13 1989-04-19 Hitachi Cable Ltd 電線・ケーブル用電気絶縁体
US5611253A (en) * 1993-09-07 1997-03-18 Tohoku Ricoh Co., Ltd. Cutting device
US5453322A (en) * 1994-06-03 1995-09-26 Union Carbide Chemicals & Plastics Technology Corporation Telephone cables
US5719218A (en) * 1995-06-01 1998-02-17 At Plastics Inc. Water resistant electrical insulation compositions
US5807635A (en) * 1997-01-24 1998-09-15 Union Carbide Chemicals & Plastics Technology Corporation Telephone cables
JPH11803A (ja) * 1997-06-13 1999-01-06 Yachiyo Koken:Kk 内燃機関用ピストン材の加工装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9921194A1 *

Also Published As

Publication number Publication date
BR9812937A (pt) 2000-11-21
TW589645B (en) 2004-06-01
SE9703844D0 (sv) 1997-10-22
PL340078A1 (en) 2001-01-15
AU9769098A (en) 1999-05-10
WO1999021194A1 (fr) 1999-04-29
NO20001913D0 (no) 2000-04-12
NO20001913L (no) 2000-04-12
AU726326B2 (en) 2000-11-02
CN1276907A (zh) 2000-12-13
WO1999021194A8 (fr) 1999-06-24
RU2191439C2 (ru) 2002-10-20
CN1114928C (zh) 2003-07-16
CA2306125A1 (fr) 1999-04-29
JP2001521264A (ja) 2001-11-06
KR20010052091A (ko) 2001-06-25

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