WO1985005216A1 - Insulation composition for cables - Google Patents

Insulation composition for cables Download PDF

Info

Publication number
WO1985005216A1
WO1985005216A1 PCT/SE1985/000190 SE8500190W WO8505216A1 WO 1985005216 A1 WO1985005216 A1 WO 1985005216A1 SE 8500190 W SE8500190 W SE 8500190W WO 8505216 A1 WO8505216 A1 WO 8505216A1
Authority
WO
WIPO (PCT)
Prior art keywords
ethylene
copolymer
acrylate
cross
per cent
Prior art date
Application number
PCT/SE1985/000190
Other languages
French (fr)
Inventor
Andras Antal Farkas
Original Assignee
Unifos Kemi Ab
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
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=20355746&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=WO1985005216(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Unifos Kemi Ab filed Critical Unifos Kemi Ab
Priority to DE8585902211T priority Critical patent/DE3572246D1/en
Publication of WO1985005216A1 publication Critical patent/WO1985005216A1/en
Priority to DK583985A priority patent/DK161278C/en
Priority to KR1019850700395A priority patent/KR860700178A/en
Priority to FI855184A priority patent/FI82320C/en

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
    • 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
    • C08K5/04—Oxygen-containing compounds
    • C08K5/14—Peroxides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/08—Copolymers of ethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2203/00—Applications
    • C08L2203/20—Applications use in electrical or conductive gadgets
    • C08L2203/202—Applications use in electrical or conductive gadgets use in electrical wires or wirecoating
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/08—Copolymers of ethene
    • C08L23/0846—Copolymers of ethene with unsaturated hydrocarbons containing atoms other than carbon or hydrogen
    • C08L23/0869—Copolymers of ethene with unsaturated hydrocarbons containing atoms other than carbon or hydrogen with unsaturated acids, e.g. [meth]acrylic acid; with unsaturated esters, e.g. [meth]acrylic acid esters
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2312/00—Crosslinking

Definitions

  • the present invention relates to an insulation composition particularly suitable for medium and high voltage cables.
  • the composition which is cross-linkable or cross-linked, consists essentially of a combination of a homopolymer of ethylene, or a copolymer of ethylene and an aIpha-oIefin, and an ethyIene-aIkyI acrylate or ethylenealkyl methacrylate copolymer.
  • the compositions of the invention have very good thermal and electrical stability properties.
  • Polyethylene is widely used as a cable insulating material.
  • copolymers of ethylene and polar materials such as vinyl acetate and ethylene acrylate are essentially used only as jacketing material and only to an insignificant extent as insulation material, and then only for low voltage purposes.
  • the thermomechanical stability is generally improved by cross-linking and cross- linked materials are thus predominantly used.
  • Copolymers of ethylene and alpha-olefins, linear ethylene polymers have, as such, better thermomechanical properties than conventional branched homopolymers of corresponding density.
  • additives have been suggested in order to solve the problems of water treeing, eg different silanes. It has also been suggested to add an ethylene-vinyl acetate copolymer as a water treeing inhibitor to polyethylene.
  • compositions of ethylene polymers and ethyIene-aIkyI acrylate or ethylene-alkyl methacrylate copolylers have very good thermal properties and that they are particularly suitable as insulation material for high voltage wire and cable, conferring resistance to water tree formation.
  • compositions of the invention are utilized cross- linked on the cables. They can be cross-linked by radiation or by chemical cross-linking without risk of degradation. A particular advantage is that they can stand the very high cross-linking temperatures which are utilized in the more recent cross-linking processes such as in dry cross- linking e.g. in nitrogen atmosphere, without being degraded and giving rise to corrosive degradation products.
  • the present invention thus relates to a cross-linkable or cross-linked cable insulation composition, for medium and high voltage cable, which consists essentially of an ethylene polymer, said ethylene polymer being a homopolymer of ethylene or a copolymer of ethylene and an alpha-olefin, and an ethylene-aIkyI acrylate or an ethylene-aIkyI methacrylate copolymer in an amount of 10 to 40 per cent by weight based on the combination of ethylene polymer and acrylate polymer.
  • the invention relates particularly to a composition as stated above which contains a cross-Linking agent.
  • the base polymer in the present compositions is a homopolymer of ethylene or a linear copolymer of ethylene and one or several alpha-olefins.
  • the latter ethylene polymers are essentially linear and are produced by copolymerization of ethylene and alpha-olefins having 3 to 14 carbon atoms. Generally 1 to 20 per cent by weight of the copolymer is used.
  • the ethylene polymer in the present compositions suitably has a density which does not exceed 940 kg/m 3 , as non-cross-linked material, and the density is suitably within the range of from 915 to 935 kg/m 3 .
  • the melt index for the ethylene base polymer, MI 2 (measured according to ISO 1133, 2.16 kg weight at 190°C) should preferably be within the range of 0.1 to 20 g/10 min., and most preferably within the range of from 0.5 to 10.
  • the base polymer in the compositions is preferably a homopolymer of ethylene, and preferably high pressure polyethylene.
  • the acrylate copolymers in the compositions are co polymers of ethylene and alkyl acrylate or alkyl methacrylate wherein the alkyl groups usually have 1 to 8 carbon atoms, eg methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, i-butyl acrylate, methyl methacrylate, ethyl methacrylate.
  • Copolymers of two or more of the mentioned acrylates or methacrylates may of course also be used.
  • the copolymers can be present in amounts of 10 to 50 per cent by weight and suitably in an amount of 25 to 40 per cent based on the combination with the ethylene base polymer.
  • Ethylene-alkyl acrylate copolymers are preferred and especially copolymers of ethylene and n-butyl acrylate which have especially satisfactory thermo-oxidative stability in contact with copper.
  • the acrylate copolymer suitably has a melt index of 2 to 60 g/10 min. ( MI 2 measured as stated earlier).
  • the content of acrylate in the copolymer should suitably be within the range of from 9 to 50 per cent by weight. Higher acrylate contents in the copolymers seem to lead to shorter trees and lower tree density, and thus a copolymer with an acrylate content of 15 to 35 per cent by weight is preferably used, and most preferably a copolymer with an acrylate content within the range of from 18 to 30 per cent by weight.
  • the acrylate copolymer is present in an amount of 10 to 40 per cent by weight and preferably in an amount of 10 to 35 per cent by weight.
  • the mentioned values are per cent of the acrylate copolymer based on the combination of this and the ethylene polymer.
  • the insulation composition is particularly suitable for medium and high voltage cable and hereby is meant wire and cable for an electrical field strength above 1 kV/mm and particularly above 1.8 kV/mm.
  • compositions according to the invention are used in a cross-linked stage on the cables and they can be cross- linked in a known manner by radiation cross-linking or using chemical cross-linking agents.
  • Chemical cross-linking agents are conventional such agents such as organic peroxides and azo compounds and also si lanes. Chemical cross- linking agents can be present in the compositions of the invention or be added afterwards, at the cable production.
  • Preferred compositions contain an effective amount of a cross-linking agent selected from organic peroxides, azo compounds and silanes.
  • Organic peroxides are preferred and as examples of such can be mentioned dicumyl peroxide and di-tert. butyl peroxide.
  • the required amount of cross- linking agent depends among other things on the desired degree of cross-linking, the type of cross-linking agent and the type of ethylene base polymer.
  • the amount of cross-linking agent is suitably within the range of from 0.5 to 6 per cent by weight, based on the combination of ethylene base polymer and acrylate copolymer.
  • the amount is here suitably within the range of from 0.2 to 5 per cent by weight.
  • compositions according to the present invention comprise polyethylene as base polymer, an ethy lene-alkyI acrylate copolymer and a cross-linking agent, preferably an organic peroxide.
  • a cross-linking agent preferably an organic peroxide.
  • an outer bonded semiconducting layer of an ethylene-aIkylacrylate copolymer is often used.
  • the present compositions give the highest compatibility with such layers and thus the highest adhesion.
  • Medium and high voltage cables with a bonded outer semiconducting layer of an ethylene-acrylate copolymer and an insulation of the present composition will thus have the best possible total electrical properties.
  • the present insulation compositions consist essentially of the ethylene polymer and the ethylene-acrylate copolymer as previously defined. Even if other polymeric materials may be included the compositions do preferably not contain any other polymeric materials, and at least not more than 10 per cent by weight of such materials.
  • the compositions can of course contain additives which are conventional for this type of materials such as antioxidants, cross-linking accelerators and cross-linking retardants, other additives to inhibit water treeing, prorads, field strength regulators etc, which are used in minor amounts with regard to the base composition.
  • Inorganic materials for example fillers such as aluminium hydroxides, kaolin and antimony oxides, should preferably not be present in the compositions, and at least not in higher amounts than 2 per cent by weight as most such materials have a negative effect on dielectric losses in higher amounts.
  • compositions can be prepared in a conventional manner by mixing in conventional, batch or continuous, mixing equipment.
  • the added ethylene-acrylate copolymer can suitably be used as a carrier for other additives such as cross-linking agents, antioxidants etc.
  • compositions are applied to a metal conductor, over the on this usually present semi-conducting layer, as insulation.
  • One embodiment of the present invention also relates to an insulated cable comprising a metal conductor, a semi-conducting layer and an insulation of the present composition and an outer semiconducting layer extruded over this and then cross-linked.
  • the compositions can be cross-linked and at this the recently developed and increasingly utilized high temperature cross-linking processes, dry curing processes where the temperatures are at about 250°C or higher, can be used.
  • the present compositions with acrylate copolymers can be treated at these high temperatures without any substantial degradation and without release of corrosive degradation products. This means that insulation according to the invention has an extremely good resistance to thermal degradation and thus an increased service life. Insulation according to the invention also has a very good electrical stability and reduced or inhibited water tree formation.
  • compositions according to the invention to withstand formation of water trees was examined by testing on Rogowsky objects.
  • the presence of so-called bow tie trees and so-called vented trees were examined and also the average size of the longest trees.
  • Bow tie trees grow from irregularities inside the insulation while vented trees grow from the interface between insulation and semiconductor.
  • Rogowsky objects give a homogeneous electrical field as in a cable in service. The objects look Like small containers and from the earth side there is an aluminium sheet serving as a water diffusion barrier and earth electrode. Next to this sheet there is a semiconductor and the two sheets are moulded together. Next to the semiconductor is the insulation, prepressed from extruded tape. Upon the insulation a water container is placed and the water is connected with a high voltage generator.
  • the container, insulation and semiconductor with the aluminium sheet are assembled in a mould and pressed and the insulation is cross-linked.
  • the samples are conditioned three days at 90°C in an oven with air circulation.
  • the objects are then subjected to an electrical stress of 6kV/mm at 90°C for 3 weeks.
  • Slices are then microtomed from the objects, dyed and examined in a microscope.
  • the results are shown in the following table.
  • compositions according to the invention were completely free from vented trees while both the reference compositions showed high amounts of such trees and also higher amounts of bow tie trees. It should also be mentioned that most commercial cross-linked polyethylene cable insulations at these test show a bow tie tree density according to the above scale of 3 to 5.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Organic Insulating Materials (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

Insulation composition for cables comprising a homopolymer of ethylene or a copolymer of ethylene and an alpha-olefin and an ethylene-acrylate copolymer. The compositions have very good thermal and electrical stability properties. They are preferably used for medium and high voltage cable. The insulation composition is preferably cross-linked.

Description

Insulation composition for cables
The present invention relates to an insulation composition particularly suitable for medium and high voltage cables. The composition, which is cross-linkable or cross-linked, consists essentially of a combination of a homopolymer of ethylene, or a copolymer of ethylene and an aIpha-oIefin, and an ethyIene-aIkyI acrylate or ethylenealkyl methacrylate copolymer. The compositions of the invention have very good thermal and electrical stability properties.
The development in the field of power cables goes towards higher and higher service temperatures and higher demands are thus made on the ability of the insulation material to withstand these and to withstand increased, very high, temperatures due to overload and short-circuit currents. It is further extremely important that the material can withstand formation of so-called water trees, which are initiated, among other things, from sites with specially high electrical stress, but will grow at a lower stress, and which gradually can lead to breakdown and considerably reduce the service life of the wire or cable.
Polyethylene is widely used as a cable insulating material. On the other hand, copolymers of ethylene and polar materials such as vinyl acetate and ethylene acrylate are essentially used only as jacketing material and only to an insignificant extent as insulation material, and then only for low voltage purposes. The thermomechanical stability is generally improved by cross-linking and cross- linked materials are thus predominantly used. Copolymers of ethylene and alpha-olefins, linear ethylene polymers, have, as such, better thermomechanical properties than conventional branched homopolymers of corresponding density. Several additives have been suggested in order to solve the problems of water treeing, eg different silanes. It has also been suggested to add an ethylene-vinyl acetate copolymer as a water treeing inhibitor to polyethylene.
According to the present invention it has been found that compositions of ethylene polymers and ethyIene-aIkyI acrylate or ethylene-alkyl methacrylate copolylers have very good thermal properties and that they are particularly suitable as insulation material for high voltage wire and cable, conferring resistance to water tree formation.
The compositions of the invention are utilized cross- linked on the cables. They can be cross-linked by radiation or by chemical cross-linking without risk of degradation. A particular advantage is that they can stand the very high cross-linking temperatures which are utilized in the more recent cross-linking processes such as in dry cross- linking e.g. in nitrogen atmosphere, without being degraded and giving rise to corrosive degradation products.
The present invention thus relates to a cross-linkable or cross-linked cable insulation composition, for medium and high voltage cable, which consists essentially of an ethylene polymer, said ethylene polymer being a homopolymer of ethylene or a copolymer of ethylene and an alpha-olefin, and an ethylene-aIkyI acrylate or an ethylene-aIkyI methacrylate copolymer in an amount of 10 to 40 per cent by weight based on the combination of ethylene polymer and acrylate polymer. The invention relates particularly to a composition as stated above which contains a cross-Linking agent.
The base polymer in the present compositions is a homopolymer of ethylene or a linear copolymer of ethylene and one or several alpha-olefins. The latter ethylene polymers are essentially linear and are produced by copolymerization of ethylene and alpha-olefins having 3 to 14 carbon atoms. Generally 1 to 20 per cent by weight of the copolymer is used. The ethylene polymer in the present compositions suitably has a density which does not exceed 940 kg/m3, as non-cross-linked material, and the density is suitably within the range of from 915 to 935 kg/m3. The melt index for the ethylene base polymer, MI2, (measured according to ISO 1133, 2.16 kg weight at 190°C) should preferably be within the range of 0.1 to 20 g/10 min., and most preferably within the range of from 0.5 to 10. The base polymer in the compositions is preferably a homopolymer of ethylene, and preferably high pressure polyethylene.
The acrylate copolymers in the compositions are co polymers of ethylene and alkyl acrylate or alkyl methacrylate wherein the alkyl groups usually have 1 to 8 carbon atoms, eg methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, i-butyl acrylate, methyl methacrylate, ethyl methacrylate. Copolymers of two or more of the mentioned acrylates or methacrylates may of course also be used. The copolymers can be present in amounts of 10 to 50 per cent by weight and suitably in an amount of 25 to 40 per cent based on the combination with the ethylene base polymer. Ethylene-alkyl acrylate copolymers are preferred and especially copolymers of ethylene and n-butyl acrylate which have especially satisfactory thermo-oxidative stability in contact with copper. The acrylate copolymer suitably has a melt index of 2 to 60 g/10 min. ( MI2 measured as stated earlier). The content of acrylate in the copolymer should suitably be within the range of from 9 to 50 per cent by weight. Higher acrylate contents in the copolymers seem to lead to shorter trees and lower tree density, and thus a copolymer with an acrylate content of 15 to 35 per cent by weight is preferably used, and most preferably a copolymer with an acrylate content within the range of from 18 to 30 per cent by weight. In the present compositions the acrylate copolymer is present in an amount of 10 to 40 per cent by weight and preferably in an amount of 10 to 35 per cent by weight. The mentioned values are per cent of the acrylate copolymer based on the combination of this and the ethylene polymer.
The insulation composition is particularly suitable for medium and high voltage cable and hereby is meant wire and cable for an electrical field strength above 1 kV/mm and particularly above 1.8 kV/mm.
The compositions according to the invention are used in a cross-linked stage on the cables and they can be cross- linked in a known manner by radiation cross-linking or using chemical cross-linking agents. Chemical cross-linking agents are conventional such agents such as organic peroxides and azo compounds and also si lanes. Chemical cross- linking agents can be present in the compositions of the invention or be added afterwards, at the cable production. Preferred compositions contain an effective amount of a cross-linking agent selected from organic peroxides, azo compounds and silanes. Organic peroxides are preferred and as examples of such can be mentioned dicumyl peroxide and di-tert. butyl peroxide. The required amount of cross- linking agent depends among other things on the desired degree of cross-linking, the type of cross-linking agent and the type of ethylene base polymer. When the base material is polyethylene the amount of cross-linking agent is suitably within the range of from 0.5 to 6 per cent by weight, based on the combination of ethylene base polymer and acrylate copolymer. For linear ethylene polymers smaller amounts of cross-linking agent can be used to obtain the same degree of cross-linking and the amount is here suitably within the range of from 0.2 to 5 per cent by weight.
Particularly preferred compositions according to the present invention comprise polyethylene as base polymer, an ethy lene-alkyI acrylate copolymer and a cross-linking agent, preferably an organic peroxide. For high voltage cables an outer bonded semiconducting layer of an ethylene-aIkylacrylate copolymer is often used. The present compositions give the highest compatibility with such layers and thus the highest adhesion. Medium and high voltage cables with a bonded outer semiconducting layer of an ethylene-acrylate copolymer and an insulation of the present composition will thus have the best possible total electrical properties.
If an ethylene-vinyI acetate copolymer, or a non-acrylate copolymer, is used in the outer semiconducting layer for strippable such layers, which are sometimes desired, the strippability will presumably be improved in combination with the present insulation composition.
The present insulation compositions consist essentially of the ethylene polymer and the ethylene-acrylate copolymer as previously defined. Even if other polymeric materials may be included the compositions do preferably not contain any other polymeric materials, and at least not more than 10 per cent by weight of such materials. The compositions can of course contain additives which are conventional for this type of materials such as antioxidants, cross-linking accelerators and cross-linking retardants, other additives to inhibit water treeing, prorads, field strength regulators etc, which are used in minor amounts with regard to the base composition. Inorganic materials, for example fillers such as aluminium hydroxides, kaolin and antimony oxides, should preferably not be present in the compositions, and at least not in higher amounts than 2 per cent by weight as most such materials have a negative effect on dielectric losses in higher amounts.
The compositions can be prepared in a conventional manner by mixing in conventional, batch or continuous, mixing equipment. The added ethylene-acrylate copolymer can suitably be used as a carrier for other additives such as cross-linking agents, antioxidants etc.
The compositions are applied to a metal conductor, over the on this usually present semi-conducting layer, as insulation. One embodiment of the present invention also relates to an insulated cable comprising a metal conductor, a semi-conducting layer and an insulation of the present composition and an outer semiconducting layer extruded over this and then cross-linked. The compositions can be cross-linked and at this the recently developed and increasingly utilized high temperature cross-linking processes, dry curing processes where the temperatures are at about 250°C or higher, can be used. In contrast to other types of copolymers, such as ethyIene-vinyI acetate copolymers, the present compositions with acrylate copolymers can be treated at these high temperatures without any substantial degradation and without release of corrosive degradation products. This means that insulation according to the invention has an extremely good resistance to thermal degradation and thus an increased service life. Insulation according to the invention also has a very good electrical stability and reduced or inhibited water tree formation.
The invention is further illustrated in the following examples, which, however, are not intended to limit the same. Parts and per cent relate to parts by weight and per cent by weight, respectively, unless otherwise stated. Example
The ability of compositions according to the invention to withstand formation of water trees was examined by testing on Rogowsky objects. The presence of so-called bow tie trees and so-called vented trees were examined and also the average size of the longest trees. Bow tie trees grow from irregularities inside the insulation while vented trees grow from the interface between insulation and semiconductor. Rogowsky objects give a homogeneous electrical field as in a cable in service. The objects look Like small containers and from the earth side there is an aluminium sheet serving as a water diffusion barrier and earth electrode. Next to this sheet there is a semiconductor and the two sheets are moulded together. Next to the semiconductor is the insulation, prepressed from extruded tape. Upon the insulation a water container is placed and the water is connected with a high voltage generator. The container, insulation and semiconductor with the aluminium sheet are assembled in a mould and pressed and the insulation is cross-linked. The samples are conditioned three days at 90°C in an oven with air circulation. The objects are then subjected to an electrical stress of 6kV/mm at 90°C for 3 weeks. Slices are then microtomed from the objects, dyed and examined in a microscope. The following compositions were examined as described above (In all compositions the base polymer was a polyethylene with a density of 922 kg/m3 and a MI2 of 2): a) 70 % polyethylene and 30 % of an ethy lene-n-buty lacrylate copolymer (MI2 = 4) with an acrylate content of 27 %. b) 81.5 % of polyethylene and 18.5 % of ethy Lene-n-butyl- acrylate copolymer according to a) c) 70 % of polyethylene and 30 % of an ethy lene-n-butyl- acrylate copolymer (M 12 = 4) with an acrylate content of 17 %. d) 75 % of polyethylene and 25 % of ethy Iene-n-buty Lacrylate copolymer according to a)
Comparison was made with the polyethylene base polymer (e) ref.) and also with an ethylene-ethyLacrylate copolymer containing 1.8 % of ethylacrylate (f) ref.). AIL samples were cross-linked with peroxide and tested in the cross- linked stage.
The results are shown in the following table. The tree density has been classified according to a scale where 0 = 0 trees per cm3, 1 = up to 300 trees, 2 = 301 to 800 trees, 3 = 801 to 1500 trees, 4 = 1501 to 2000 trees and
5 = more than 2000 trees.
Composition Bow tie trees Vented trees d e n s i t y s i z e μm density size μ m a) 0-1 ≤ 10 0 0 b ) 0- 1 35 0 0 c ) 1 25 0 0 d ) 0- 1 1 5 0 0 e ) ref. 3 90 2 180 f) ref. 1-2 27 1-2 35
It should be noted that all compositions according to the invention were completely free from vented trees while both the reference compositions showed high amounts of such trees and also higher amounts of bow tie trees. It should also be mentioned that most commercial cross-linked polyethylene cable insulations at these test show a bow tie tree density according to the above scale of 3 to 5.

Claims

C l a i m s
1. Crdss-linkable or cross-linked cable insulation composition for medium and high voltage cables characterized in that it consists essentially of an ethylene polymer, which is a homopolymer of ethylene or a copolymer of ethylene and an aIpha-olefin, and an ethylene-alkyI acrylate or ethy lene-aIkyI methacrylate copolymer in an amount of 10 to 40 per cent by weight, based on the combination of ethylene polymer and acrylate copolymer.
2. A composition according to claim 1, characterized in that it contains a cross-linking agent.
3. A composition according to claim 2, characterized in that the cross-linking agent is an organic peroxide.
4. A composition according to claim 1, characterized in that it contains 10 to 35 per cent by weight of acrylate copolymer, based on the combination of ethylene polymer and acrylate copolymer.
5. A composition according to any of the preceding claims, characterized in that the acrylate copolymer is ethy lene-n-butyI acrylate copolymer.
6. A composition according to any of the preceding claims, characterized in that the acrylate content in the acrylate copolymer is within the range of from 9 to 50 per cent by weight.
7. An insulated cable comprising a metal conductor, a semiconducting layer and an insulation of a composition consisting essentially of an ethylene polymer, which is a homopolymer of ethylene or a copolymer of ethylene and an a Ipha-olefin, and an ethy lene-aIkyI acrylate or ethylene-alkyl methacrylate copolymer in an amount of 10 to 40 per cent by weight, based on the combination of ethylene polymer and acrylate copolymer, and an outer semiconducting layer extruded over this and then cross-linked.
PCT/SE1985/000190 1984-05-03 1985-04-30 Insulation composition for cables WO1985005216A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DE8585902211T DE3572246D1 (en) 1984-05-03 1985-04-30 Insulation composition for cables
DK583985A DK161278C (en) 1984-05-03 1985-12-16 CABLE INSULATION MATERIAL AND INSULATED CABLE
KR1019850700395A KR860700178A (en) 1984-05-03 1985-12-17 Insulator composition for cables
FI855184A FI82320C (en) 1984-05-03 1985-12-30 Insulation composition for cables

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8402396-9 1984-05-03
SE8402396A SE8402396L (en) 1984-05-03 1984-05-03 CABLE INSULATION COMPOSITION

Publications (1)

Publication Number Publication Date
WO1985005216A1 true WO1985005216A1 (en) 1985-11-21

Family

ID=20355746

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1985/000190 WO1985005216A1 (en) 1984-05-03 1985-04-30 Insulation composition for cables

Country Status (10)

Country Link
EP (1) EP0179845B1 (en)
JP (1) JPS61502085A (en)
KR (1) KR860700178A (en)
AU (1) AU578095B2 (en)
DE (1) DE3572246D1 (en)
DK (1) DK161278C (en)
FI (1) FI82320C (en)
NO (1) NO860009L (en)
SE (1) SE8402396L (en)
WO (1) WO1985005216A1 (en)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0248148A1 (en) * 1986-03-08 1987-12-09 BASF Aktiengesellschaft Cable insulation based on ethylene polymers
EP0341621A2 (en) * 1988-05-13 1989-11-15 BASF Aktiengesellschaft Electrical cables containing insulations based on ethylene polymerisates with a high resistance capability against the formation of water trees
US5066724A (en) * 1986-04-25 1991-11-19 Rexene Products Company Novel film compositions
US5468259A (en) * 1992-12-07 1995-11-21 Sheth; Paresh J. Dyeable polyolefin compositions and dyeing polyolefin compositions
US5550192A (en) * 1992-12-07 1996-08-27 Lyondell Petrochemical Company Dyeable polyolefin compositions and dyeing polyolefin compositions
WO1998041995A1 (en) * 1997-03-20 1998-09-24 Union Carbide Chemicals & Plastics Technology Corporation Tree resistant cable
EP1731565A1 (en) * 2005-06-08 2006-12-13 Borealis Technology Oy Polyolefin composition for use as an insulating material
EP1731563A1 (en) 2005-06-08 2006-12-13 Borealis Technology Oy Polymer composition having improved wet ageing properties
EP1731566A1 (en) * 2005-06-08 2006-12-13 Borealis Technology Oy Polymer composition having improved wet ageing properties
WO2010072396A1 (en) 2008-12-22 2010-07-01 Borealis Ag Masterbatch and process for preparing a polymer composition
EP2439234A1 (en) 2010-10-07 2012-04-11 Borealis AG Polymer Composition
WO2014051954A1 (en) 2012-09-27 2014-04-03 Dow Global Technologies Llc Process for reducing peroxide migration in crosslinkable ethylene-based polymer compositions
US10208196B2 (en) 2010-03-17 2019-02-19 Borealis Ag Polymer composition for W and C application with advantageous electrical properties
US10811164B2 (en) 2010-03-17 2020-10-20 Borealis Ag Polymer composition for W and C application with advantageous electrical properties
WO2022074086A1 (en) 2020-10-06 2022-04-14 Borealis Ag Cable
EP4261846A1 (en) 2022-04-12 2023-10-18 Borealis AG Submarine cable

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3702209A1 (en) * 1987-01-26 1988-08-04 Licentia Gmbh PLASTIC INSULATION AND METHOD FOR THEIR PRODUCTION
WO2017078430A1 (en) * 2015-11-06 2017-05-11 엘에스전선 주식회사 Insulation composition having excellent original form recovery and mechanical properties, and cable having insulation layer formed therefrom
TWI805586B (en) 2017-06-29 2023-06-21 美商陶氏全球科技有限責任公司 A crosslinkable composition, an article and a method of conducting electricity

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE369244B (en) * 1972-07-21 1974-08-12 Raychem Corp
GB2019412A (en) * 1978-04-07 1979-10-31 Raychem Ltd Cross-Linked Low Density Linear Polyethylenes
EP0061125A1 (en) * 1981-03-19 1982-09-29 LES CABLES DE LYON Société anonyme dite: Fire retardant insulating material
EP0085390A2 (en) * 1982-01-29 1983-08-10 Sanpack Lagertechnik GmbH Method for wrapping a stack of articles with a plurality of convolutions of a web of extensible material
GB2141719A (en) * 1983-06-20 1985-01-03 Unifos Kemi Ab Ethylene polymer compositions

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5158691A (en) * 1974-11-19 1976-05-22 Fujikura Ltd DENRYOKUKEEBURU
JPS5868804A (en) * 1981-10-19 1983-04-23 日立電線株式会社 Electric insulator
JPS58103702A (en) * 1981-11-13 1983-06-20 古河電気工業株式会社 Crosslinked polyethylene insulated power cable
US4430468A (en) * 1982-07-21 1984-02-07 E. I. Du Pont De Nemours And Company Surfactant-containing filled and plasticized thermoplastic compositions based on ethylene interpolymers
JPS5935314A (en) * 1982-08-24 1984-02-27 日立電線株式会社 Electric insulator for electric wire and cable

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE369244B (en) * 1972-07-21 1974-08-12 Raychem Corp
GB2019412A (en) * 1978-04-07 1979-10-31 Raychem Ltd Cross-Linked Low Density Linear Polyethylenes
EP0061125A1 (en) * 1981-03-19 1982-09-29 LES CABLES DE LYON Société anonyme dite: Fire retardant insulating material
EP0085390A2 (en) * 1982-01-29 1983-08-10 Sanpack Lagertechnik GmbH Method for wrapping a stack of articles with a plurality of convolutions of a web of extensible material
GB2141719A (en) * 1983-06-20 1985-01-03 Unifos Kemi Ab Ethylene polymer compositions

Cited By (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0248148A1 (en) * 1986-03-08 1987-12-09 BASF Aktiengesellschaft Cable insulation based on ethylene polymers
US5047482A (en) * 1986-03-08 1991-09-10 Basf Aktiengesellschaft Cable insulation based on ethylene polymers having high resistance to the formation of water trees
US5066724A (en) * 1986-04-25 1991-11-19 Rexene Products Company Novel film compositions
EP0341621A2 (en) * 1988-05-13 1989-11-15 BASF Aktiengesellschaft Electrical cables containing insulations based on ethylene polymerisates with a high resistance capability against the formation of water trees
EP0341621A3 (en) * 1988-05-13 1991-06-05 BASF Aktiengesellschaft Electrical cables containing insulations based on ethylene polymerisates with a high resistance capability against the formation of water trees
US5468259A (en) * 1992-12-07 1995-11-21 Sheth; Paresh J. Dyeable polyolefin compositions and dyeing polyolefin compositions
US5550192A (en) * 1992-12-07 1996-08-27 Lyondell Petrochemical Company Dyeable polyolefin compositions and dyeing polyolefin compositions
WO1998041995A1 (en) * 1997-03-20 1998-09-24 Union Carbide Chemicals & Plastics Technology Corporation Tree resistant cable
US5919565A (en) * 1997-03-20 1999-07-06 Union Carbide Chemicals & Plastics Technology Corporation Tree resistant cable
AU724031B2 (en) * 1997-03-20 2000-09-07 Union Carbide Chemicals & Plastics Technology Corporation Tree resistant cable
US8912284B2 (en) 2005-06-08 2014-12-16 Borealis Technology Oy Polymer composition having improved wet ageing properties
EA014839B1 (en) * 2005-06-08 2011-02-28 Бореалис Текнолоджи Ой Polymer composition having improved wet ageing properties, articles and a process for preparing thereof
EP1731566A1 (en) * 2005-06-08 2006-12-13 Borealis Technology Oy Polymer composition having improved wet ageing properties
WO2006131264A1 (en) * 2005-06-08 2006-12-14 Borealis Technology Oy Polymer composition having improved wet ageing properties
WO2006131265A1 (en) * 2005-06-08 2006-12-14 Borealis Technology Oy Polymer composition having improved wet ageing properties
WO2006131267A1 (en) * 2005-06-08 2006-12-14 Borealis Technology Oy Poyolefin composition for use as an insulating material
NO340219B1 (en) * 2005-06-08 2017-03-20 Borealis Tech Oy Polymer composition with improved wet aging properties
EA014056B1 (en) * 2005-06-08 2010-08-30 Бореалис Текнолоджи Ой Crosslinkable polymer composition, a crosslinked polymer composition, a process for preparing thereof, an article comprising the composition (embodiments), a method for producing the article
US7803860B2 (en) 2005-06-08 2010-09-28 Borealis Technology Oy Polymer compositions having improved wet ageing properties
EP1731565A1 (en) * 2005-06-08 2006-12-13 Borealis Technology Oy Polyolefin composition for use as an insulating material
CN101193969B (en) * 2005-06-08 2012-03-14 北方科技有限公司 Polymer composition having improved wet ageing properties
EP1731563A1 (en) 2005-06-08 2006-12-13 Borealis Technology Oy Polymer composition having improved wet ageing properties
WO2010072396A1 (en) 2008-12-22 2010-07-01 Borealis Ag Masterbatch and process for preparing a polymer composition
US10626265B2 (en) 2010-03-17 2020-04-21 Borealis Ag Polymer composition for W and C application with advantageous electrical properties
US10811164B2 (en) 2010-03-17 2020-10-20 Borealis Ag Polymer composition for W and C application with advantageous electrical properties
US10208196B2 (en) 2010-03-17 2019-02-19 Borealis Ag Polymer composition for W and C application with advantageous electrical properties
WO2012045777A1 (en) 2010-10-07 2012-04-12 Borealis Ag Polymer composition
EP2439234A1 (en) 2010-10-07 2012-04-11 Borealis AG Polymer Composition
US9390834B2 (en) 2010-10-07 2016-07-12 Borealis Ag Polymer composition
WO2014051954A1 (en) 2012-09-27 2014-04-03 Dow Global Technologies Llc Process for reducing peroxide migration in crosslinkable ethylene-based polymer compositions
US10259930B2 (en) 2012-09-27 2019-04-16 Dow Global Technologies Llc Process for reducing peroxide migration in crosslinkable ethylene-based polymer compositions
US9758638B2 (en) 2012-09-27 2017-09-12 Dow Global Technologies Llc Process for reducing peroxide migration in crosslinkable ethylene-based polymer compositions
WO2022074086A1 (en) 2020-10-06 2022-04-14 Borealis Ag Cable
EP4261846A1 (en) 2022-04-12 2023-10-18 Borealis AG Submarine cable
WO2023198762A1 (en) 2022-04-12 2023-10-19 Borealis Ag Submarine cable

Also Published As

Publication number Publication date
KR860700178A (en) 1986-03-31
DK161278C (en) 1991-12-30
SE8402396L (en) 1985-11-04
FI855184A0 (en) 1985-12-30
FI855184A (en) 1985-12-30
FI82320C (en) 1991-02-11
NO860009L (en) 1986-01-02
JPS61502085A (en) 1986-09-18
EP0179845A1 (en) 1986-05-07
DK583985D0 (en) 1985-12-16
AU4294885A (en) 1985-11-28
DK161278B (en) 1991-06-17
FI82320B (en) 1990-10-31
DE3572246D1 (en) 1989-09-14
DK583985A (en) 1985-12-16
EP0179845B1 (en) 1989-08-09
SE8402396D0 (en) 1984-05-03
AU578095B2 (en) 1988-10-13

Similar Documents

Publication Publication Date Title
AU578095B2 (en) Insulation composition for cables
EP0750319B1 (en) Polymeric composition for coating electric cables having an improved resistance to water treeing and electric cable comprising said composition
US4576993A (en) Low density polyethylene polymeric compositions
JP4030153B2 (en) Water tree resistant insulating composition
CA1287420C (en) Stabilized olefin polymer insulating compositions
EP0334992B1 (en) Easily peelable semiconductive resin composition
CA2524252C (en) Improved strippable cable shield compositions
US5807635A (en) Telephone cables
US4451536A (en) Heat distortion-resistant thermoplastic semi-conductive composition
CA2112543C (en) Telephone cables
EP2207845A1 (en) Crosslinkable polyolefin composition comprising dihydrocarbyl tin dicarboxylate as silanol condensation catalyst
US8501864B2 (en) Insulating composition for an electric power cable
WO1993024938A1 (en) Telephone cables
CA1290879C (en) Compositions based on mixtures of ethylene-ethyl acrylate copolymersand ethylene-vinyl acetate-vinyl chloride terpolymers
EP0848385B1 (en) Telephone cables
CA1281832C (en) Insulation composition for cables
EP0152911B1 (en) Insulated electric cable
JPS5889708A (en) Waterproof crosslinked electrically insulator having excellent tree property
KR100291669B1 (en) A semiconductive power cable shield
CA1041189A (en) Styrene in dielectric layer of electric wires or cables
CA1039436A (en) Dielectric polyolefin compositions
AU755732B2 (en) Polymeric composition for coating electric cables having an improved resistance to water treeing and electric cable comprising said composition
JPS62115047A (en) Tree delaying high voltage composition and its production
JPH03255143A (en) Semiconductive composition
JPS58201204A (en) Power cable

Legal Events

Date Code Title Description
AK Designated states

Designated state(s): AU DK FI JP KR NO US

AL Designated countries for regional patents

Designated state(s): AT BE CH DE FR GB IT LU NL SE

WWE Wipo information: entry into national phase

Ref document number: 1985902211

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 855184

Country of ref document: FI

WWP Wipo information: published in national office

Ref document number: 1985902211

Country of ref document: EP

WWG Wipo information: grant in national office

Ref document number: 1985902211

Country of ref document: EP

WWW Wipo information: withdrawn in national office

Ref document number: 1985902211

Country of ref document: EP