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US20020001714A1 - Polymeric composition for coating electric cables having an improved resistance to water treeing and electric cable comprising said composition - Google Patents

Polymeric composition for coating electric cables having an improved resistance to water treeing and electric cable comprising said composition Download PDF

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US20020001714A1
US20020001714A1 US09/791,225 US79122501A US2002001714A1 US 20020001714 A1 US20020001714 A1 US 20020001714A1 US 79122501 A US79122501 A US 79122501A US 2002001714 A1 US2002001714 A1 US 2002001714A1
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carbon atoms
branched
linear
phenyl
alkyl
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US6436536B2 (en
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Franco Peruzzotti
Valeria Garcia
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Prysmian Cavi e Sistemi Energia SRL
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
    • H01B7/282—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
    • H01B7/2825—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable using a water impermeable sheath
    • 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
    • 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
    • C08L23/06—Polyethene
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
    • H01B7/2813—Protection against damage caused by electrical, chemical or water tree deterioration
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
    • H01B7/282—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
    • 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
    • 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
    • C08L23/0884—Epoxide-containing esters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2933—Coated or with bond, impregnation or core

Definitions

  • the present invention relates to electric cables comprising at least one conducting core and at least one insulation coating comprising a polyolefin polymeric base.
  • the present invention relates to an electric cable comprising an insulation coating having an improved resistance against the formation of the so-called water trees.
  • the present invention also relates to a polymeric composition which has a preferred, although not exclusive, use in the manufacture of an insulation coating in electric cables for power transmission at medium or high voltage.
  • medium and high voltage are used to indicate voltages of from 1 to 35 kV and, respectively, over 35 kV.
  • the best material for manufacturing the insulation coating is constituted by olefin polymers and in particular by polyethylene and copolymers or terpolimers thereof.
  • cross-linked polyethylene commonly indicated by the acronym XLPE—has either good dieletric characteristics or a low loss factor (minimum dissipated power).
  • olefin polymers generally possess a low resistance against a particular degradation phenomenon, known in the art by the term: “water treeing”, which may cause in time a degradation of the electric characteristic of the insulation material.
  • Such phenomenon essentially consists in the formation of microfractures having a branched shape (trees), progressively growing in time and responsible, in some cases, for an electric weakening of the insulation coating.
  • European Patent EP 0 179 845 discloses, on the other hand, the combined use of an ethylene polymer or of an ethylene copolymer with an alpha-olefin, with an ethylene-alkylacrylate or an ethylene-alkylmethacrylate copolymer, in a cross-linkable coating composition resistant to the formation of water trees, for medium/high voltage energy cables.
  • ester groups and epoxy groups in a polyolefin polymeric composition may impart to said composition a particular resistance to the phenomenon of water trees in the working condition of an electric cable.
  • the present invention therefore provides an electric cable comprising at least a conductor and at least an insulation coating comprising a polyolefin polymeric base, which is characterized in that said polyolefin polymeric base comprises, in parts by weight to the total weight of the same:
  • a cable which is characterized in that said polyolefin polymeric base comprises a first predetermined amount of ester groups and a second predetermined amount of epoxy groups, said first and second predetermined amounts being such as to reduce the water tree formation in the insulation coating material after electric ageing in water.
  • electric water ageing is used to indicate an ageing treatment of the insulation coating carried out in water and in the presence of an electric field such as—for instance—the treatment proposed by EFI (Norwegian Electric Power Research Institute), illustrated below, or analogous treatments well known in the art.
  • EFI Newegian Electric Power Research Institute
  • the present invention also provides a polyolefin polymeric composition resistant to water treeing, in particular for the manufacture of an insulation coating for electric cables, which is characterized in that it comprises—in parts by weight to the total weight thereof—from 0.05 to 15 parts of ester groups and from 0.01 to 5 parts of epoxy groups.
  • polyolefin polymeric base is used to indicate a polymer selected from the group comprising high-, medium- and low-density polyethylene homopolymers, ethylene copolymers and ethylene terpolymers with an alpha-olefin having 3 to 20 carbon atoms, ethylene-alpha-olefin-diene terpolymers and mixtures thereof.
  • polyolefin polymeric composition is used to indicate a polymeric composition comprising a polyolefin polymeric base of the above defined type.
  • the polyolefin polymeric base of the invention is an ethylene polymer selected from the group comprising: polyethylene, copolymers obtainable by polymerizing ethylene with at least one alpha-olefin, linear or branched, having 3 to 14 carbon atoms, terpolymers obtainable by polymerizing ethylene, an alpha-olefin, linear or branched, having 3 to 14 carbon atoms and a diene having 4 to 25 carbon atoms having a density (measured according to ASTM D-792) of from 0.860 g/cm 3 to 0.940 g/cm 3 and a Melt Index (measured according to ASTM D-1238) of from 0.1 g/10′ to 40 g/10′.
  • ethylene polymer selected from the group comprising: polyethylene, copolymers obtainable by polymerizing ethylene with at least one alpha-olefin, linear or branched, having 3 to 14 carbon atoms, terpolymers obtainable by polymerizing ethylene
  • the above diene is preferably selected from the group comprising: 1,4 pentadiene, 1,4 hexadiene, 1,5 hexadiene, dicyclopentadiene, 4-vinyl-cyclohexene, 1-vinyl-1-cyclopentene, ethyl norbornene (LNB), alkylbicyclononadiene, indene, norbornene and mixtures thereof.
  • the polyolefin matrix forming the insulation coating of the cable conducting core should preferably comprise at least 0.5% by weight of ester groups and at least 0.01% by weight of epoxy groups.
  • a polymeric composition comprising the above minimum amount of ester groups and epoxy groups may be prepared by adding to a polyolefin polymeric base a first compound, either polymeric or not, incorporating an ester group and, respectively, a second compound, either polymeric or not, incorporating an epoxy group.
  • the above compound incorporating an ester group is an acrylic or vinyl polymer selected from the group comprising:
  • R 1 is H or CH 3
  • R 2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms
  • R 3 is hydrogen or an alkyl or aryl hydrocarbon group, preferably a phenyl, linear or branched, having 1 to 10 carbon atoms;
  • R 2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms.
  • the acrylic copolymers having the formula (I) of preferred use comprise ethylene copolymers with a comonomer selected from the group comprising the following acrylic esters: methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, iso-butyl acrylate, methyl methacrylate, ethyl methacrylate, and mixtures thereof.
  • acrylic ester-ethylene copolymers and, more particularly, those having an amount of acrylic comonomer of from 2% to 40% by weight, such as for instance those commercially available under the trade names ENATHENE EATM (Quantum Chemical Corporation, Cincinnati, Ohio, U.S.A.), OPTEMATM (Exxon Chemical) and LOTRYLTM (Elf Atochem).
  • ENATHENE EATM Quantum Chemical Corporation, Cincinnati, Ohio, U.S.A.
  • OPTEMATM Exxon Chemical
  • LOTRYLTM Elf Atochem
  • the vinyl copolymers of preferred use comprise ethylene copolymers with a comonomer selected from the group comprising vinyl acetate and vinyl propionate, such as for instance those commercially available under the trade names LEVAPRENTM (Bayer), ESCORENETM (Exxon Chemical), ELVAXTM (Du Pont de Nemours International S.A.) and EVATANETM (Elf Atochem).
  • a comonomer selected from the group comprising vinyl acetate and vinyl propionate
  • optimal homogeneity characteristics of the polymeric composition may be achieved when the acrylic or vinyl copolymers having the formula (I) and (II) have a Melt Index value near that of the polyolefin polymeric base in which they may be easily incorporated.
  • such Melt Index value (measured according to ASTM D-1238) preferably ranges from 0.1 g/10′ to 40 g/10′.
  • the above amount of ester groups may be reached when the polymeric composition comprises at least 5% by weight of the above acrylic or vinyl polymers having the formula (I) and (II), or greater values depending upon the ester groups content within said polymers.
  • the polymeric composition of the invention preferably comprises from S% to 40k by weight of the aforementioned acrylic or vinyl polmers having the formula (I) and (II).
  • the above-identified compound incorporating an epoxy group may be:
  • R 4 , R 6 and R 7 are independently a hydrogen atom, an alkyl or aryl hydrocarbon group, linear or branched, preferably an optionally substituted phenyl, having 1 to 25 carbon atoms or a glycidyl ether group of the formula:
  • the glycidyl ethers having the formula (III) may be mono-, bi-, tri- or tetrafunctional; those of preferred use are mono- and bifunctional glycidyl ethers selected from the group comprising: p-t-butyl-phenyl-glycidyl ether, 2-ethyl-hexyl-glycidyl ether, dodecyl-glycidyl ether, tetradecyl-glycidyl ether, glycidyl-isopropyl-etherbutyl-glycidyl ether, 1,4-butanediol-diglycidyl ether, 1,6-hexen-diol-diglycidyl ether and mixtures thereof.
  • Epoxy resins of preferred use comprise instead resins of the aliphatic, cycloaliphatic or aromatic type, preferably having a dynamic viscosity at 25° C. of from 60 to 55,000 mPa ⁇ s, preferably between 7,000 and 10,000 mPa ⁇ s, and an epoxy content (measured according to ASTM D-1652) of from 0.1 to 0.7 gram eq/100 g of resin, preferably between 0.53 and 0.55 gram eq/100 g of resin.
  • Examples of such resins are those commercially available under the trade name EUREPOXTM (SCHERING) and preferably those named EUREPOXTM 730.
  • the polymeric composition comprises from 0.2 to 10% by weight of at least one glicydyl ether having the formula (III) or polyfunctional derivatives thereof and/or from 0.2 to 10% by weight of said epoxy resin, so as to reach the aforementioned amount of epoxy groups indicated hereinabove.
  • the above-identified minimum amount of ester groups and epoxy groups may be reached by adding to a polyolefin polymeric base a compound, either polymeric or not, incorporating either an ester group or an epoxy group.
  • Bifunctional compounds of preferred and advantageous use are, more particularly, those selected from the group comprising the glycidyl esters of the formula:
  • R 3 and R 5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R 1 is H or CH 3 .
  • the glycidyl esters of the acrylic or methacrylic acid are preferred.
  • GMA glycidyl methacrylate
  • the aforementioned amount of ester and epoxy groups may be reached when the polymeric composition preferably comprises from 0.03 to 15% by weight of at least a glycidyl ester having the formula (IV).
  • Bifunctional compounds of the polymeric type of preferred and advantageous use are those selected from the group comprising:
  • R 1 is H or CH 3
  • R 2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms
  • R 3 is hydrogen or an alkyl or aryl hydrocarbon group, preferably a phenyl, linear or branched, having 1 to 10 carbon atoms;
  • R 2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
  • R 3 and R 5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R 1 is H or CH 3 .
  • glycidyl esters having the formula (IV) of preferred use are the glycidyl esters of the acrylic or methacrylic acids and, particularly, glycidyl methacrylate.
  • Ethylene/acrylic ester/glycidyl methacrylate terpolymers and ethylene/glycidyl methacrylate copolymers of preferred and advantageous use are commercially available under the trade names LOTADERTM GMA AX8900 and LOTADERTM GMA AX8840 (Elf Atochem), respectively.
  • the aforementioned amount of ester and epoxy groups may be reached when the polymeric composition comprises from 3 to 30% by weight of at least an ethylene/acrylic ester/glycidyl methacrylate terpolymer or ethylene/vinyl ester/glycidyl methacrylate terpolymer and from 1 to 40 by weight of at least an ethylene/glycidyl methacrylate copolymer.
  • both the bifunctional compounds may be used in the polymeric composition of the invention, either alone or combined with the aforementioned monofunctional compounds (acrylic or vinyl polymers, glycidyl ether, epoxy resin), so as to reach the desired amount of ester and epoxy groups.
  • the present invention relates to a new use of one of the above bifunctional compounds—either polymeric or not—incorporating either an ester group or an epoxy group, as a tree retardant additive in a polymeric composition for coating an electric cable.
  • the amount of the ester and epoxy groups falls within said range of 0.5-15% parts by weight and, respectively, of 0.01-5% parts by weight to the total weight of the composition so obtained.
  • the polymeric composition of the invention is cross-linked by means of one of the methods known in the art to this end.
  • the polymeric composition is chemically cross-linked; for this purpose, it incorporates an effective amount of at least one cross-linking agent, such as for instance tei-butyl-cumyl peroxide.
  • at least one cross-linking agent such as for instance tei-butyl-cumyl peroxide.
  • the polymeric composition of the invention advantageously incorporates an effective amount of at least one antioxidant agent, such as for instance 4,4′-thio-bis(3-methyl-6-ter-butyl)phenol.
  • at least one antioxidant agent such as for instance 4,4′-thio-bis(3-methyl-6-ter-butyl)phenol.
  • the polymeric composition of the invention may incorporate other additives and fillers conventional in themselves; such as instance pigments, dyes, stabilizers, lubricants, etc.
  • reference 1 indicates a cable comprising an electric conducting core 2 including a plurality of wires, i.e. of copper, all indicated by 3 .
  • the conducting core 2 is enclosed within several coaxial coating layers, including an inner semiconducting layer 4 , an insulation layer 5 , an outer semiconducting layer 6 , a metal screen 7 and an outer polymeric sheath 8 .
  • the above described cable 1 may be produced starting from the conducting core 2 according to known methods, for instance by subsequently extruding layers 4 , 5 and 6 , by applying the metal screen 7 and by finally extruding the external sheath 8 .
  • a polymeric composition according to the invention was prepared by mixing in an extruder the following ingredients, in parts by polymeric base 90 phr ethylene/acrylic ester/glycidyl methacrilate 10 phr terpolymer peroxide 2 phr antioxidant 0.34 phr
  • LDPE low-density polyethylene
  • LOTADERTM GMA AX 8900 TM (Elf Atochem) was used.
  • the peroxide and the antioxidant used were ter-butyl-cumyl peroxide (TRIGONOXTM T produced by AKZO) and 4-4′-thio-bis(3-methyl-6-ter-butyl)phenol (SANTONOXTMR produced by MONSANTO).
  • polymeric composition having the following composition in parts by weight for each 100 parts of polymeric base (phr): polymeric base 85 phr ethylene/acrylic ester/glycidyl methacrilate 15 phr terpolymer peroxide 2 phr antioxidant 0.34 phr
  • polymeric composition having the following composition in parts by weight for each 100 parts of polymeric base (phr): polymeric base 80 phr ethylene/acrylic ester/glycidyl methacrilate 20 phr terpolymer peroxide 2 phr antioxidant 0.34 phr
  • polymeric composition including acrylic ester groups was prepared, having the following composition in parts by weight for each 100 parts of polymeric base (phr): polymeric base 82.5 phr ethylene/acrylic-ester copolymer 17.5 phr peroxide 2 phr antioxidant 0.34 phr
  • epoxy resin the resin commercially available under the trade name EUREPOXTM (SCHERING) was used.
  • the cable is simulated by preparing cup-shaped multilayered test-samples, wherein the material constituting the insulation coating is sandwiched between two layers of semiconducting material.
  • the layer of insulation material is heat-moulded in the shape of a cup at the temperature of 120° C., starting from a tape having a thickness of 5-7 mm, in an electric press capable of developing a pressure of about 90 t, so as to obtain a thickness of about 0.50 mm.
  • test-samples so obtained once cooled at room temperature, are then submitted to an accelerated electric ageing test, filling with water the cavity defined inside the cup-shaped test-sample, immersing in the water a high voltage electrode and laying the resulting equipment on a metal plate (earth electrode).
  • the accelerated trees growth is then induced in the insulation layer by applying a voltage generally of from 2 to 15 kV between the electrodes.
  • test is heat-performed, for instance in a suitable oven.
  • test-samples were produced which were submitted to accelerated water ageing in the following test conditions: - electric gradient: 5 kV/mm - temperature: 70° C.
  • the loss factor was measured by using as test-samples moulded flat plates of 20 ⁇ 20 cm of side, 1.0 mm thick, and using circular electrodes with guard ring.
  • test-samples had been submitted to heat treatment at 90° C. in order to remove the cross-linking by-products in each plate.
  • ester groups and epoxy groups in the polymeric composition of the invention may bring about an increase in the loss factor; hence, the content of said groups may be selected having regard to the desired resistance characteristics to the formation of water trees and to the other performances required to the cable.
  • ester groups and epoxy groups in the polymeric composition may be selected by a man skilled in the art in relation to the specific application requirements of the cable.
  • the cable of the invention possesses a combination of features that render the same useable for all those applications—and in particular for power transmission at medium/high voltage—where a particular resistance to water treeing is required.
  • ester groups and epoxy groups in predetermined amount in a given polymeric composition allows to increase the resistance to the phenomenon of water treeing compared to the case when—in the same polymeric composition—such groups are not present and, as a consequence, to increase, after electric water ageing, the dielectric strength of the insulation coating of a cable manufactured with the same polymeric base.

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Abstract

A polymeric composition for coating electric cables for power transmission at medium/high voltage, having an improved resistance against the formation of the so-called water trees, comprises a polymeric polyolefin base including, in parts by weight to the total weight thereof, from 0.5 to 15 parts of ester groups and from 0.01 to 5 parts of epoxy groups. Electric cables according to the invention comprise at least one electrically conducting core (2) and an insulation coating (5) comprising the aforementioned polymeric composition.

Description

  • In a general aspect, the present invention relates to electric cables comprising at least one conducting core and at least one insulation coating comprising a polyolefin polymeric base. [0001]
  • More particularly, the present invention relates to an electric cable comprising an insulation coating having an improved resistance against the formation of the so-called water trees. [0002]
  • The present invention also relates to a polymeric composition which has a preferred, although not exclusive, use in the manufacture of an insulation coating in electric cables for power transmission at medium or high voltage. [0003]
  • In the following description, the terms: medium and high voltage, are used to indicate voltages of from 1 to 35 kV and, respectively, over 35 kV. [0004]
  • As is known, one of the more difficult problems to solve in the manufacture of electric cables for power transmission or energy cable, is that of ensuring that the insulation coating of the conducting core achieves an effective control of the electric field generated during the energy transmission, dissipates as little power as possible and preserves its dielectric and structural characteristics along time. [0005]
  • It is also known that to obtain such characteristics the best material for manufacturing the insulation coating is constituted by olefin polymers and in particular by polyethylene and copolymers or terpolimers thereof. [0006]
  • More particularly, among the latter, cross-linked polyethylene—commonly indicated by the acronym XLPE—has either good dieletric characteristics or a low loss factor (minimum dissipated power). [0007]
  • But together with these good characteristics, olefin polymers generally possess a low resistance against a particular degradation phenomenon, known in the art by the term: “water treeing”, which may cause in time a degradation of the electric characteristic of the insulation material. [0008]
  • Such phenomenon essentially consists in the formation of microfractures having a branched shape (trees), progressively growing in time and responsible, in some cases, for an electric weakening of the insulation coating. [0009]
  • Even though the mechanism leading to the formation of these microfractures or weak zones has not yet been fully clarified, the formation of such zones or “trees” is anyhow attributed to the combined action of the electric field generated by the current flow in the conducting core of the cable and of the moisture existing in the inside of the insulation coating. [0010]
  • The problem represented by the formation of the above water trees is particularly felt in the cables for power transmission at medium or high voltage which are not provided with external protection elements, wherein the insulation coating may be directly in touch with water or anyhow with humid environments. [0011]
  • In order to reduce somehow the formation of water trees, different solutions have been proposed in the art, which are essentially based either on the selection of suitable polymeric materials for the manufacture of the insulation coatings, or on the use of suitable retarding additives, so-called tree-retardants. [0012]
  • So, for instance, it is known from U.S. Pat. No. 5,246,783 the use of an ethylene copolymer and of an alpha-olefin having 3 to 20 carbon atoms, having a molecular weight distribution of from 1.5 to 30 and a distribution index of the alpha-olefin comonomer greater than 45%. [0013]
  • European Patent EP 0 179 845 discloses, on the other hand, the combined use of an ethylene polymer or of an ethylene copolymer with an alpha-olefin, with an ethylene-alkylacrylate or an ethylene-alkylmethacrylate copolymer, in a cross-linkable coating composition resistant to the formation of water trees, for medium/high voltage energy cables. [0014]
  • As to the use of the so-called tree-retardant additives, it is known from the U.S. Pat. Nos. 4,212,756 and 4,144,202 the use of particular organo silanes comprising an acrylic/methacrylic group and, respectively, an epoxy group. [0015]
  • According to the present invention, it has now been found that the simultaneous presence of ester groups and epoxy groups in a polyolefin polymeric composition may impart to said composition a particular resistance to the phenomenon of water trees in the working condition of an electric cable. [0016]
  • According to the invention, in fact, a surprising synergistic effect—in terms of increased resistance to the water treeing phenomenon—has been observed, due to the simultaneous presence of ester groups and epoxy groups within a selected concentration range. [0017]
  • When the aforementioned groups are simultaneously present in the polymeric base forming the insulation coating of the cable, it has been noticed in particular that the retarding effect against water tree formation is evidently greater than the sum of the effects of the same groups when the latter are present alone. [0018]
  • According to a first aspect thereof, the present invention therefore provides an electric cable comprising at least a conductor and at least an insulation coating comprising a polyolefin polymeric base, which is characterized in that said polyolefin polymeric base comprises, in parts by weight to the total weight of the same: [0019]
  • from 0.5 to 15 parts of ester groups; and [0020]
  • from 0.01 to S parts of epoxy groups. [0021]
  • According to a further aspect of the invention, the problem of an adequate resistance to the phenomenon of water trees is therefore solved by a cable which is characterized in that said polyolefin polymeric base comprises a first predetermined amount of ester groups and a second predetermined amount of epoxy groups, said first and second predetermined amounts being such as to reduce the water tree formation in the insulation coating material after electric ageing in water. [0022]
  • In the following description and the subsequent claims, the term: electric water ageing, is used to indicate an ageing treatment of the insulation coating carried out in water and in the presence of an electric field such as—for instance—the treatment proposed by EFI (Norwegian Electric Power Research Institute), illustrated below, or analogous treatments well known in the art. [0023]
  • According to a further aspect thereof, the present invention also provides a polyolefin polymeric composition resistant to water treeing, in particular for the manufacture of an insulation coating for electric cables, which is characterized in that it comprises—in parts by weight to the total weight thereof—from 0.05 to 15 parts of ester groups and from 0.01 to 5 parts of epoxy groups. [0024]
  • In the following description and the subsequent claims, the term: polyolefin polymeric base, is used to indicate a polymer selected from the group comprising high-, medium- and low-density polyethylene homopolymers, ethylene copolymers and ethylene terpolymers with an alpha-olefin having 3 to 20 carbon atoms, ethylene-alpha-olefin-diene terpolymers and mixtures thereof. [0025]
  • The term: polyolefin polymeric composition, on the other hand, is used to indicate a polymeric composition comprising a polyolefin polymeric base of the above defined type. [0026]
  • Preferably, the polyolefin polymeric base of the invention is an ethylene polymer selected from the group comprising: polyethylene, copolymers obtainable by polymerizing ethylene with at least one alpha-olefin, linear or branched, having 3 to 14 carbon atoms, terpolymers obtainable by polymerizing ethylene, an alpha-olefin, linear or branched, having 3 to 14 carbon atoms and a diene having 4 to 25 carbon atoms having a density (measured according to ASTM D-792) of from 0.860 g/cm[0027] 3 to 0.940 g/cm3 and a Melt Index (measured according to ASTM D-1238) of from 0.1 g/10′ to 40 g/10′.
  • In the terpolymers of the invention, the above diene is preferably selected from the group comprising: 1,4 pentadiene, 1,4 hexadiene, 1,5 hexadiene, dicyclopentadiene, 4-vinyl-cyclohexene, 1-vinyl-1-cyclopentene, ethyl norbornene (LNB), alkylbicyclononadiene, indene, norbornene and mixtures thereof. [0028]
  • According to the invention, it has been observed that to achieve an adequate resistance to the water tree formation, the polyolefin matrix forming the insulation coating of the cable conducting core should preferably comprise at least 0.5% by weight of ester groups and at least 0.01% by weight of epoxy groups. [0029]
  • On the other hand, it has been observed that amounts exceding 15% by weight of ester groups and, respectively, 5% by weight of epoxy groups do not produce a substantial additional benefit in terms of resistance to the phenomenon of water trees, against a marked increase in the power dissipated by the insulation coating (increase of the loss factor or tg delta), with ensuing increase in the energy transmission costs. [0030]
  • According to the invention, is has also been observed that the aforementioned improved resistance to the water trees formation is not substantially affected by the way in which the ester groups and the epoxy groups are incorporated into the polymeric composition, provided that these groups are present in the aforementioned amounts, as indicated above. [0031]
  • So, for instance, in a first embodiment of the invention, a polymeric composition comprising the above minimum amount of ester groups and epoxy groups may be prepared by adding to a polyolefin polymeric base a first compound, either polymeric or not, incorporating an ester group and, respectively, a second compound, either polymeric or not, incorporating an epoxy group. [0032]
  • Preferably, the above compound incorporating an ester group is an acrylic or vinyl polymer selected from the group comprising: [0033]
  • i) copolymers obtainable by polymerizing ethylene with at least an acrylic ester of the formula: [0034]
    Figure US20020001714A1-20020103-C00001
  • wherein R[0035] 1 is H or CH3, R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms, and R3 is hydrogen or an alkyl or aryl hydrocarbon group, preferably a phenyl, linear or branched, having 1 to 10 carbon atoms;
  • ii) copolymers obtainable by polymerizing ethylene with at least a vinyl ester of a carboxylic acid of the formula: [0036]
    Figure US20020001714A1-20020103-C00002
  • wherein R[0037] 2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms.
  • For the purposes of the invention, the acrylic copolymers having the formula (I) of preferred use comprise ethylene copolymers with a comonomer selected from the group comprising the following acrylic esters: methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, iso-butyl acrylate, methyl methacrylate, ethyl methacrylate, and mixtures thereof. [0038]
  • Among them, particularly preferred are the acrylic ester-ethylene copolymers and, more particularly, those having an amount of acrylic comonomer of from 2% to 40% by weight, such as for instance those commercially available under the trade names ENATHENE EA™ (Quantum Chemical Corporation, Cincinnati, Ohio, U.S.A.), OPTEMA™ (Exxon Chemical) and LOTRYL™ (Elf Atochem). [0039]
  • For the purposes of the invention, the vinyl copolymers of preferred use comprise ethylene copolymers with a comonomer selected from the group comprising vinyl acetate and vinyl propionate, such as for instance those commercially available under the trade names LEVAPREN™ (Bayer), ESCORENE™ (Exxon Chemical), ELVAX™ (Du Pont de Nemours International S.A.) and EVATANE™ (Elf Atochem). [0040]
  • According to an advantegeous aspect of the invention, optimal homogeneity characteristics of the polymeric composition may be achieved when the acrylic or vinyl copolymers having the formula (I) and (II) have a Melt Index value near that of the polyolefin polymeric base in which they may be easily incorporated. [0041]
  • For the purposes of the invention, such Melt Index value (measured according to ASTM D-1238) preferably ranges from 0.1 g/10′ to 40 g/10′. [0042]
  • According to a preferred embodiment, the above amount of ester groups may be reached when the polymeric composition comprises at least 5% by weight of the above acrylic or vinyl polymers having the formula (I) and (II), or greater values depending upon the ester groups content within said polymers. [0043]
  • Furthermore, the polymeric composition of the invention preferably comprises from S% to 40k by weight of the aforementioned acrylic or vinyl polmers having the formula (I) and (II). [0044]
  • According to the invention, the above-identified compound incorporating an epoxy group may be: [0045]
  • a) a glycidyl ether of the formula: [0046]
    Figure US20020001714A1-20020103-C00003
  • wherein R[0047] 4, R6 and R7 are independently a hydrogen atom, an alkyl or aryl hydrocarbon group, linear or branched, preferably an optionally substituted phenyl, having 1 to 25 carbon atoms or a glycidyl ether group of the formula:
    Figure US20020001714A1-20020103-C00004
  • b) a polyfunctional derivative of the glycidyl ether of formula (III), or [0048]
  • c) an epoxy resin. [0049]
  • For the purposes of the invention, the glycidyl ethers having the formula (III) may be mono-, bi-, tri- or tetrafunctional; those of preferred use are mono- and bifunctional glycidyl ethers selected from the group comprising: p-t-butyl-phenyl-glycidyl ether, 2-ethyl-hexyl-glycidyl ether, dodecyl-glycidyl ether, tetradecyl-glycidyl ether, glycidyl-isopropyl-etherbutyl-glycidyl ether, 1,4-butanediol-diglycidyl ether, 1,6-hexen-diol-diglycidyl ether and mixtures thereof. [0050]
  • Epoxy resins of preferred use comprise instead resins of the aliphatic, cycloaliphatic or aromatic type, preferably having a dynamic viscosity at 25° C. of from 60 to 55,000 mPa×s, preferably between 7,000 and 10,000 mPa×s, and an epoxy content (measured according to ASTM D-1652) of from 0.1 to 0.7 gram eq/100 g of resin, preferably between 0.53 and 0.55 gram eq/100 g of resin. [0051]
  • Examples of such resins are those commercially available under the trade name EUREPOX™ (SCHERING) and preferably those named EUREPOX™ 730. [0052]
  • Preferably, the polymeric composition comprises from 0.2 to 10% by weight of at least one glicydyl ether having the formula (III) or polyfunctional derivatives thereof and/or from 0.2 to 10% by weight of said epoxy resin, so as to reach the aforementioned amount of epoxy groups indicated hereinabove. [0053]
  • According to a further embodiment of the invention, the above-identified minimum amount of ester groups and epoxy groups may be reached by adding to a polyolefin polymeric base a compound, either polymeric or not, incorporating either an ester group or an epoxy group. [0054]
  • Bifunctional compounds of preferred and advantageous use are, more particularly, those selected from the group comprising the glycidyl esters of the formula: [0055]
    Figure US20020001714A1-20020103-C00005
  • wherein R[0056] 3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3.
  • Among them, the glycidyl esters of the acrylic or methacrylic acid are preferred. [0057]
  • For the purposes of the invention, particularly preferred is glycidyl methacrylate (GMA), commercially available under the trade name BLEMMER G™ (Blemmer Chemical Corp.). [0058]
  • In this case, the aforementioned amount of ester and epoxy groups may be reached when the polymeric composition preferably comprises from 0.03 to 15% by weight of at least a glycidyl ester having the formula (IV). [0059]
  • Bifunctional compounds of the polymeric type of preferred and advantageous use are those selected from the group comprising: [0060]
  • a) terpolymers obtainable by polymerizing ethylene with: [0061]
  • i) at least one acrylic ester of the formula: [0062]
    Figure US20020001714A1-20020103-C00006
  • wherein R[0063] 1 is H or CH3, R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms and R3 is hydrogen or an alkyl or aryl hydrocarbon group, preferably a phenyl, linear or branched, having 1 to 10 carbon atoms;
  • ii) at least one glycidyl ester of the formula: [0064]
    Figure US20020001714A1-20020103-C00007
  • wherein the meaning of R[0065] 1, R3 and R5 are those indicated hereinabove;
  • b) terpolymers obtainable by polymerizing ethylene with: [0066]
  • i) at least one vinyl ester of a carboxylic acid of the formula: [0067]
    Figure US20020001714A1-20020103-C00008
  • wherein R[0068] 2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
  • i) at least one glycidyl ester of the formula: [0069]
    Figure US20020001714A1-20020103-C00009
  • wherein the meaning of R[0070] 1, R3 and R5 are those indicated hereinabove;
  • c) copolymers obtainable by polymerizing ethylene with at least one glycidyl ester of the formula: [0071]
    Figure US20020001714A1-20020103-C00010
  • wherein R[0072] 3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3.
  • Also in these cases, glycidyl esters having the formula (IV) of preferred use are the glycidyl esters of the acrylic or methacrylic acids and, particularly, glycidyl methacrylate. [0073]
  • Ethylene/acrylic ester/glycidyl methacrylate terpolymers and ethylene/glycidyl methacrylate copolymers of preferred and advantageous use are commercially available under the trade names LOTADER™ GMA AX8900 and LOTADER™ GMA AX8840 (Elf Atochem), respectively. [0074]
  • As previously explained, in this case too optimum homogeneity characteristics of the polymeric composition may be obtained when the above bifunctional terpolymers or copolymers have a Melt Index of from 0.1 g/10′ to 40 g/10′. [0075]
  • In this case, the aforementioned amount of ester and epoxy groups may be reached when the polymeric composition comprises from 3 to 30% by weight of at least an ethylene/acrylic ester/glycidyl methacrylate terpolymer or ethylene/vinyl ester/glycidyl methacrylate terpolymer and from 1 to 40 by weight of at least an ethylene/glycidyl methacrylate copolymer. [0076]
  • Obviously, both the bifunctional compounds, either polymeric or not, may be used in the polymeric composition of the invention, either alone or combined with the aforementioned monofunctional compounds (acrylic or vinyl polymers, glycidyl ether, epoxy resin), so as to reach the desired amount of ester and epoxy groups. [0077]
  • According to a further aspect thereof, the present invention relates to a new use of one of the above bifunctional compounds—either polymeric or not—incorporating either an ester group or an epoxy group, as a tree retardant additive in a polymeric composition for coating an electric cable. [0078]
  • In fact, it is advantageously possible to confer to a polyolefin polymeric base the desired characteristics of resistance to the water treeing phenomenon by simply adding said bifunctional compounds to said base in the aforementioned amounts. [0079]
  • Preferably, the amount of the ester and epoxy groups falls within said range of 0.5-15% parts by weight and, respectively, of 0.01-5% parts by weight to the total weight of the composition so obtained. [0080]
  • In a preferred embodiment, the polymeric composition of the invention is cross-linked by means of one of the methods known in the art to this end. [0081]
  • Preferably, the polymeric composition is chemically cross-linked; for this purpose, it incorporates an effective amount of at least one cross-linking agent, such as for instance tei-butyl-cumyl peroxide. [0082]
  • In order to achieve an improved stability, furthermore, the polymeric composition of the invention advantageously incorporates an effective amount of at least one antioxidant agent, such as for [0083] instance 4,4′-thio-bis(3-methyl-6-ter-butyl)phenol.
  • Depending upon the particular use of the cable, moreover, the polymeric composition of the invention may incorporate other additives and fillers conventional in themselves; such as instance pigments, dyes, stabilizers, lubricants, etc. [0084]
  • Further advantages and characteristics of the invention will be better apparent from the following description of some preferred embodiments thereof, which are reported in the following by way of non-limitative illustration, with reference to the attached drawing, whose only figure shows, in perspective view and partial cross-section, a cable according to the invention. [0085]
  • In such figure, reference [0086] 1 indicates a cable comprising an electric conducting core 2 including a plurality of wires, i.e. of copper, all indicated by 3.
  • The conducting core [0087] 2 is enclosed within several coaxial coating layers, including an inner semiconducting layer 4, an insulation layer 5, an outer semiconducting layer 6, a metal screen 7 and an outer polymeric sheath 8.
  • The above described cable [0088] 1 may be produced starting from the conducting core 2 according to known methods, for instance by subsequently extruding layers 4, 5 and 6, by applying the metal screen 7 and by finally extruding the external sheath 8.
  • With reference to the description hereinabove, some merely illustrative and not limitative examples of polymeric compositions according to the invention, particularly suitable for the manufacture of the insulation layer of a cable, such as for instance the [0089] layer 5 of the cable described above, will be provided in the following.
    •  EXAMPLE 1
  • A polymeric composition according to the invention was prepared by mixing in an extruder the following ingredients, in parts by [0090]
    polymeric base 90 phr
    ethylene/acrylic ester/glycidyl methacrilate 10 phr
    terpolymer
    peroxide 2 phr
    antioxidant 0.34 phr
  • As polymeric base low-density polyethylene (LDPE) was used, having a density of 0.923 g/cm[0091] 3 and a Melt Flow Index of 2 g/10′ (Enichem).
  • As ethylene/acrylic ester/glydidyl methacrylate terpolymer, LOTADER™ GMA AX[0092] 8900™ (Elf Atochem) was used.
  • The peroxide and the antioxidant used were ter-butyl-cumyl peroxide (TRIGONOX™ T produced by AKZO) and 4-4′-thio-bis(3-methyl-6-ter-butyl)phenol (SANTONOX™R produced by MONSANTO). [0093]
    • EXAMPLE 2
  • According to the same preparation methods and using the same ingredients as the previous Example 1, a polymeric composition was prepared having the following composition in parts by weight for each 100 parts of polymeric base (phr): [0094]
    polymeric base 85 phr
    ethylene/acrylic ester/glycidyl methacrilate 15 phr
    terpolymer
    peroxide 2 phr
    antioxidant 0.34 phr
    • EXAMPLE 3
  • According to the same preparation methods and using the same ingredients as the previous Example 1, a polymeric composition was prepared having the following composition in parts by weight for each 100 parts of polymeric base (phr): [0095]
    polymeric base 80 phr
    ethylene/acrylic ester/glycidyl methacrilate 20 phr
    terpolymer
    peroxide 2 phr
    antioxidant 0.34 phr
    • EXAMPLE 4 Comparison
  • According to conventional preparation methods known in the art and using the same ingredients of the previous Example 1, a polymeric composition including only the polyolefin polymer, the cross-linking agent and the antioxidant agent was prepared, having the following composition in parts by weight for each 100 [0096]
    polymeric base 100 phr
    peroxide 2 phr
    antioxidant 0.34 phr
    • EXAMPLE 5 Comparison
  • According to conventional preparation methods known in the art and using the same ingredients of the previous Example 1, a polymeric composition including acrylic ester groups was prepared, having the following composition in parts by weight for each 100 parts of polymeric base (phr): [0097]
    polymeric base 82.5 phr
    ethylene/acrylic-ester copolymer 17.5 phr
    peroxide 2 phr
    antioxidant 0.34 phr
  • As ethylene/acrylic-ester copolymer the ethylene/butyl acrylate copolymer commercially available under the trade name ENATHENE™ EA 720 (USI QUANTUM) was used. [0098]
    • EXAMPLE 6 Comparison
  • According to conventional preparation methods known in the art and using the same ingredients of the previous Example 1, a polymeric composition according to the prior art and including epoxy groups was prepared, having the following composition in parts by weight for each 100 parts of polymeric base (phr): [0099]
    polymeric base 100 phr
    epoxy resin 1.5 phr
    peroxide 2 phr
    antioxidant 0.34 phr
  • As epoxy resin the resin commercially available under the trade name EUREPOX™ (SCHERING) was used. [0100]
    • EXAMPLE 7 Evaluation of the Water Tree Resistance
  • The resistance properties to the formation of water trees of the polymeric compositions according to Examples 1-6 hereinabove, were evaluated according to the methodology proposed by EFI (Norwegian Electric Power Research Institute) in the publication “The EFI Test Method for Accelerated Growth of Water Trees”, presented at the “1990 IEEE International Symposium on Electrical Insulation”, held in Toronto, Canada, on Jun. 3-6, 1990. [0101]
  • According to such a methodology, the cable is simulated by preparing cup-shaped multilayered test-samples, wherein the material constituting the insulation coating is sandwiched between two layers of semiconducting material. [0102]
  • More particularly, the layer of insulation material is heat-moulded in the shape of a cup at the temperature of 120° C., starting from a tape having a thickness of 5-7 mm, in an electric press capable of developing a pressure of about 90 t, so as to obtain a thickness of about 0.50 mm. [0103]
  • The layers of semiconducting material, extruded and preshaped in an analogous way until a thickness of about 0.5 mm is obtained, are then pressed and heat-welded on opposite sides of the insulation layer at a temperature of about 180° C. for 15 minutes in an electric press similar to that used to form the same layers. [0104]
  • The test-samples so obtained, once cooled at room temperature, are then submitted to an accelerated electric ageing test, filling with water the cavity defined inside the cup-shaped test-sample, immersing in the water a high voltage electrode and laying the resulting equipment on a metal plate (earth electrode). [0105]
  • The accelerated trees growth is then induced in the insulation layer by applying a voltage generally of from 2 to 15 kV between the electrodes. [0106]
  • In order to further accelerate the phenomenon, the test is heat-performed, for instance in a suitable oven. [0107]
  • In the tests carried out, the polymeric compositions of Examples 1-6 were coupled to a semiconducting screen constituted by a XLPE mix, commercially available under the trade name NCPE 0592™ (Borealis N.V., Bruxelles, Belgium). [0108]
  • According to the above described EFI methodology, 5 test-samples were produced for each polymeric composition, which were submitted to accelerated ageing in the following test conditions: [0109]
    - electric gradient: 5 kV/mm
    - temperature: 70° C.
  • At the end of a 30-day period, 20 100 μm-thick sections were taken off from each test-piece, dyed with methylene blue according to the CIGRE standards and then examined with an optical microscope at a magnification of from 100 to 200×. [0110]
  • From such observation the density of water trees, expressed in number of trees per cm[0111] 3, was then calculated for each test-sample. The mean values are shown in the following Table 1.
    TABLE 1
    Example nr. 1 2 3 4 5 6
    Trees density (nr./cm3) 190 140 95 980 470 780
  • From the data shown in the table, it may be observed that the resistance to the water tree formation of the polymeric compositions of the invention (Examples 1-3), comprising ester groups and epoxy groups, is markedly greater that that offered by the control polymeric compositions, incorporating only acrylic groups (Example 5) or epoxy groups (Example 6). [0112]
  • In this connection, it has to be observed that, quite surprisingly, the combined effects of the above ester groups and epoxy groups is of a synergistic type, i.e. much greater than the sum of the individual effects ascribable to each of them considered in isolation. [0113]
  • This synergistic effect is so marked that, in the case of the composition of Example 3, a density of water trees has been observed whose order of magnitude was even lower than that of the cross-linked polyethylene taken as control. [0114]
    • EXAMPLE 8 Evaluation of Dielectric Strength
  • The dielectric strength properties of the polymeric compositions according to the previous Examples 1-6 were evaluated on test-samples obtained by the ageing methodology proposed by EFI, described in the preceding example. [0115]
  • In this case, 20 test-samples were produced which were submitted to accelerated water ageing in the following test conditions: [0116]
    - electric gradient: 5 kV/mm
    - temperature: 70° C.
  • On a batch of 5 non-aged test-samples (control) and on three batches of 5 test-samples taken after 7, 15 and 30 days respectively from the beginning of the accelerated electric ageing, the value of the dielectric strength was then measured according to the ASTM D-149 standard. [0117]
  • The dielectric strength tests were carried out with silicone oil in the inside and on the outside of the test-samples, using a circular electrode and applying a voltage gradient of 2 kV/s. [0118]
  • The results of the tests carried out (mean values of 5 tests) are shown in the following Table 2. [0119]
    TABLE 2
    Example 1 2 3 4 5 6
    Strength as is 120  130  135  105  120  110 
    (kV/mm)  7 days 60 75 85 55 60 58
    15 days 55 70 80 45 50 47
    30 days 55 70 75 45 50 47
  • From the data shown in the table, it may be observed that—after ageing—the dielectric strength of the polymeric compositions of the invention (Examples 1-3), is as a whole greater than that of the control compositions, independently from the original starting values, with an advantageous improvement of the insulating properties of the composition. [0120]
    • EXAMPLE 9 Evaluation of the Loss Factor
  • The evaluation of the so-called loss factor (tan delta) of the polymeric compositions according to the previous Examples 1-6 was carried out according to the ASTM D-150 standard (AC Loss Characteristics and Dielectric Constant (Permettivity) of Solid Electrical Insulating Material). [0121]
  • More particularly, the loss factor was measured by using as test-samples moulded flat plates of 20×20 cm of side, 1.0 mm thick, and using circular electrodes with guard ring. [0122]
  • Before taking the measures, the test-samples had been submitted to heat treatment at 90° C. in order to remove the cross-linking by-products in each plate. [0123]
  • The results of the tests performed (mean values out of S tests) are shown in the following Table 3. [0124]
    TABLE 3
    Example nr. 1 2 3 4 5 6
    tg delta (room T) 0.0002 0.0003 0.0004 0.0001 0.0001 0.0010
    tg delta (90° C.) 0.0008 0.0024 0.0110 0.0003 0.0004 0.0110
  • As it may be observed from the above table, the presence of ester groups and epoxy groups in the polymeric composition of the invention may bring about an increase in the loss factor; hence, the content of said groups may be selected having regard to the desired resistance characteristics to the formation of water trees and to the other performances required to the cable. [0125]
  • To this end, the optimum amount of ester groups and epoxy groups in the polymeric composition may be selected by a man skilled in the art in relation to the specific application requirements of the cable. [0126]
  • From what has been described and illustrated above it is immediately evident that the cable of the invention possesses a combination of features that render the same useable for all those applications—and in particular for power transmission at medium/high voltage—where a particular resistance to water treeing is required. [0127]
  • In particular, according to the invention, the use of ester groups and epoxy groups in predetermined amount in a given polymeric composition allows to increase the resistance to the phenomenon of water treeing compared to the case when—in the same polymeric composition—such groups are not present and, as a consequence, to increase, after electric water ageing, the dielectric strength of the insulation coating of a cable manufactured with the same polymeric base. [0128]
  • Obviously, those skilled in the art may introduce variants and modifications to the above described invention, in order to satisfy specific and contingent requirements, variants and modifications which fall anyhow within the scope of protection as is defined in the following claims. [0129]

Claims (45)

1. An electric cable comprising at least one conducting core (2) and at least one insulation coating (5) including a polyolefin polymeric base, characterized in that said polyolefin polymeric base comprises, in parts by weight to the total weight thereof:
from 0.5 to 15 parts of ester groups; and
from 0.01 to 5 parts of epoxy groups.
2. An electric cable comprising at least one conducting core (2) and at least one insulation coating (5) including a polyolefin polymeric base, characterized in that said polyolefin polymeric base comprises a first predetermined amount of ester groups and a second predetermined amount of epoxy groups, said first and said second predetermined amounts being such as to reduce the formation of water trees within the material of 'the insulation coating (5) after electric ageing in water.
3. An electric cable according to claims 1 or 2, characterized in that said polyolefin polymeric base comprises:
a) at least one ethylene polymer selected from the group comprising: polyethylene, copolymers obtainable by polymerizing ethylene with at least one alpha-olefin, linear or branched, having 3 to 14 carbon atoms, terpolymers obtainable by polymerizing ethylene, an alpha-olefin, linear or branched, having 3 to 14 carbon atoms and a diene having 4 to 25 carbon atoms, having a density (measured according to ASTM D-792) of from 0.860 g/cm3 to 0.940 g/cm3 and a Melt Index (measured according to ASTM D-1238) of from 0.1 g/10′ to 40 g/10′;
b) at least one acrylic or vinyl polymer selected from the group comprising:
i) copolymers obtainable by polymerizing ethylene with at least one acrylic ester of the formula:
Figure US20020001714A1-20020103-C00011
wherein R1 is H or CH3, R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms, and R3 is hydrogen or an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
ii) copolymers obtainable by polymerizing ethylene with at least one vinyl ester of a carboxylic acid of the formula:
Figure US20020001714A1-20020103-C00012
wherein R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
c) at least one glycidyl ether of the formula:
Figure US20020001714A1-20020103-C00013
wherein R4, R6 and R7 are independently a hydrogen atom, an alkyl or aryl hydrocarbon group, linear or branched, preferably an option all y substituted phenyl, having 1 to 25 carbon atoms or a glycidyl ether group of the formula:
Figure US20020001714A1-20020103-C00014
or polyfunctional derivatives thereof.
4. An electric cable according to claim 3, characterized in that said polyolefin polymeric base comprises from 5 to 40 parts by weight of said at least one acrylic or vinyl polymer (b) for each 100 parts by weight of said ethylene polymer (a).
5. An electric cable according to claims 1 or 2, characterized in that said polyolefin polymeric base comprises:
a) at least one ethylene polymer selected from the group comprising: polyethylene, copolymers obtainable by polymerizing ethylene with at least one alpha-olefin, linear or branched, having 3 to 14 carbon atoms, terpolymers obtainable by polymerizing ethylene, an alpha-olefin, linear or branched, having 3 to 14 carbon atoms and a diene having 4 to 25 carbon atoms, having a density (measured according to ASTM D-792) of from 0.860 g/cm3 to 0.940 g/cm3 and a Melt Index (measured according to ASTM D-1238) of from 0.1 g/10′ to 40 g/10′;
b) at least one glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00015
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3.
6. An electric cable according to claim 5, characterized in that said at least one glycidyl ester is glycidyl methacrilate.
7. An electric cable according to anyone of the preceding claims, characterized in that said polyolefin polymeric base further comprises an epoxy resin.
8. An electric cable according to claims 1 or 2, characterized in that said polyolefin polymeric base comprises:
a) at least one ethylene polymer selected from the group comprising: polyethylene, copolymers obtainable by polymerizing ethylene with at least one alpha-olefin, linear or branched, having 3 to 14 carbon atoms, terpolymers obtainable by polymerizing ethylene, an alpha-olefin, linear or branched, having 3 to 14 carbon atoms and a diene having 4 to 25 carbon atoms having a density (measured according to ASTM D-792) of from 0.860 g/cm3 to 0.940 g/cm3 and a Melt Index (measured according to ASTM D-1238) of from 0.1 g/10′ to 40 g/10′;
b) at least one acrylic or vinyl polymer selected from the group comprising:
i) copolymers obtainable by polymerizing ethylene with at least one acrylic ester of the formula:
Figure US20020001714A1-20020103-C00016
wherein R1 is H or CH3, R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms, and R3 is hydrogen or an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
ii) copolymers obtainable by polymerizing ethylene with at least one vinyl ester of a carboxylic acid of the formula:
Figure US20020001714A1-20020103-C00017
wherein R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
c) at least one epoxy resin.
9. An electric cable according to claims 7 or 8, characterized in that said epoxy resin is aliphatic, cycloaliphatic or aromatic.
10. An electric cable according to claim 9, characterized in that said epoxy resin has a dynamic viscosity at 25° C. of from 60 to 55,000 mPa×s and an epoxy content of from 0.1 to 0.7 gram eq/100 g of resin.
11. An electric cable according to claims 1 or 2, characterized in that said polyolefin polymeric base further comprises a terpolymer having a Melt Index of from 0.1 g/10′ to 40 g/10′obtainable by polymerizing ethylene with
i) at least one acrylic ester of the formula:
Figure US20020001714A1-20020103-C00018
wherein R1 is H or CH3, R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms, and R3 is hydrogen or an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
ii) at least one glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00019
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3.
12. An electric cable according to claims 1 or 2, characterized in that said polyolefin polymeric base further comprises a terpolymer having a Melt Index of from 0.1 g/10′ to 40 g/10′ obtainable by polymerizing ethylene with
i) at least one vinyl ester of a carboxylic acid of the formula:
Figure US20020001714A1-20020103-C00020
wherein R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
ii) at least one glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00021
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3.
13. An electric cable according to claims 11 or 12, characterized in that said at least one glycidyl ester is glycidyl methacrilate.
14. An electric cable according to claims 1 or 2, characterized in that said polyolefin polymeric base further comprises a copolymer obtainable by polymerizing ethylene with at least one glycidyl ester of the formula
Figure US20020001714A1-20020103-C00022
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3.
15. An electric cable according to claim 14, characterized in that said at least one glycidyl ester is glycidyl methacrylate.
16. An electric cable according to anyone of the preceding claims, characterized in that said polyolefin polymeric base further comprises an effective amount of at least one cross-linking agent.
17. An electric cable according to claim 16, characterized in that said at least one cross-linking agent is ter-butyl cumylperoxide.
18. An electric cable according to anyone of the preceding claims, characterized in that said polyolefin polymeric base further comprises an effective amount of at least one antioxidant agent.
19. A polyolefin polymeric composition resistant to water treeing, in particular for the manufacture of an insulating coating for electric cables, characterized in that it comprises in parts by weights to the total weight thereof:
from 0.5 to 15 parts of ester groups; and
from 0.01 to 5 parts of epoxy groups.
20. A polymeric composition according to claim 19, characterized in that it comprises:
a) at least one ethylene polymer selected from the group comprising: polyethylene, copolymers obtainable by polymerizing ethylene with at least one alpha-olefin, linear or branched, having 3 to 14 carbon atoms, terpolymers obtainable by polymerizing ethylene, an alpha-olefin, linear or branched, having 3 to 14 carbon atoms and a diene having 4 to 25 carbon atoms having a density (measured according to ASTM D-792) of from 0.860 g/cm3 to 0.940 g/cm3 and a Melt Index (measured according to ASTM D-1238) of from 0.1 g/10′ to 40 g/10′;
b) at least one acrylic or vinyl polymer selected from the group comprising:
i) copolymers obtainable by polymerizing ethylene with at least one acrylic ester of the formula:
Figure US20020001714A1-20020103-C00023
wherein R1 is H or CH3, R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms, and R3 is hydrogen or an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
ii) copolymers obtainable by polymerizing ethylene with at least one vinyl ester of a carboxylic acid of the formula:
Figure US20020001714A1-20020103-C00024
wherein R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
c) at least one glycidyl ether of the formula:
Figure US20020001714A1-20020103-C00025
wherein R4, R6 and R7 are independently a hydrogen atom, an alkyl or aryl hydrocarbon group, linear or branched, preferably an optionally substituted phenyl, having 1 to 25 carbon atoms or a glycidyl ether group of the formula:
Figure US20020001714A1-20020103-C00026
or polyfunctional derivatives thereof.
21. A polymeric composition according to claim 20, characterized in that it comprises from 5 to 40 parts by weight of said at least one acrylic or vinyl polymer (b) for each 100 parts by weight of said ethylene polymer (a).
22. A polymeric composition according to claim 19, characterized in that it comprises:
a) at least one ethylene polymer selected from the group comprising: polyethylene, copolymers obtainable by polymerizing ethylene with at least one alpha-olefin, linear or branched, having 3 to 14 carbon atoms, terpolymers obtainable by polymerizing ethylene, an alpha-olefin, linear or branched, having 3 to 14 carbon atoms and a diene having 4 to 25 carbon atoms, having a density (measured according to ASTM D-792) of from 0.860 g/cm3 to 0.940 g/cm3 and a Melt Index (measured according to ASTM D-1238) of from 0.1 g/10′ to 40 g/10′;
b) at least one glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00027
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3.
23. A polymeric composition according to claim 22, characterized in that said at least one glycidyl ester is glycidyl methacrylate.
24. A polymeric composition according to anyone of claims 19-23, characterized in that it further comprises an epoxy resin.
25. A polymeric composition according to claim 19, characterized in that said polyolefin polymer base comprises:
a) at least one ethylene polymer selected from the group comprising: polyethylene, copolymers obtainable by polymerizing ethylene with at least one alpha-olefin, linear or branched, having 3 to 14 carbon atoms, terpolymers obtainable by polymerizing ethylene, an alpha-olefin, linear, or branched, having 3 to 14 carbon atoms and a diene having 4 to 25 carbon atoms, having a density (measured according to ASTM D-792) of from 0.860 g/cm3 to 0.940 g/cm3 and a Melt Index (measured according to ASTM D-1238) of from 0.1 g/10′ to 40 g/10′;
b) at least one acrylic or vinyl polymer selected from the group comprising:
i) copolymers obtainable by polymerizing ethylene with at least one acrylic ester of the formula:
Figure US20020001714A1-20020103-C00028
wherein R1 is H or CH3, R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms, and R3 is hydrogen or an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
ii) copolymers obtainable by polymerizing ethylene with at least one vinyl ester of a carboxylic acid of the formula:
Figure US20020001714A1-20020103-C00029
wherein R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
c) at least one epoxy resin.
26. A polymeric composition according to claims 24 or 25, characterized in that said epoxy resin is aliphatic, cycloaliphatic or aromatic.
27. A polymeric composition according to claim 26, characterized in that said epoxy resin has a dynamic viscosity at 25° C. of from 60 to 55,000 mPa×s and an epoxy content of from 0.1 to 0.7 gram eq/100 g of resin.
28. A polymeric composition according to claim 19, characterized in that it further comprises a terpolymer having a Melt Index of from 0.1 g/10′ to 40 g/10′ obtainable by polymerizing ethylene with
i) at least one acrylic ester of the formula:
Figure US20020001714A1-20020103-C00030
wherein R1 is H or CH3, R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms, and R3 is hydrogen or an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
ii) at least one glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00031
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3.
29. A polymeric composition according to claim 19, characterized in that it further comprises a terpolymer having a a Melt Index of from 0.1 g/10′ to 40 g/10′ obtainable by polymerizing ethylene with
i) at least one vinyl ester of a carboxylic acid of the formula:
Figure US20020001714A1-20020103-C00032
wherein R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
ii) at least one glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00033
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3.
30. A polymeric composition according to claims 28 or 29, characterized in that said at least one glycidyl ester is glycidyl methacrylate.
31. A polymeric composition according to claim 19, characterized in that it further comprises a copolymer obtainable by polymerizing ethylene with at least one glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00034
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3.
32. A polymeric composition according to claim 31, characterized in that said at least one glycidyl ester is glycidyl methacrylate.
33. A polymeric composition according to anyone of the preceding claims, characterized in that it further comprises an effective amount of at least one cross-linking agent.
34. A polymeric composition according to claim 33, characterized in that said at least one cross-linking agent is ter-butyl-cumylperoxide.
35. A polymeric composition according to anyone of the preceding claims, characterized in that it further comprises an effective amount of at least one antioxidant agent.
36. Use of a polymeric composition according to anyone of claims 19-35 for the insulation of electric cables.
37. Use of a glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00035
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3,
as tree retardant additive in a polymeric composition for coating an electric cable.
38. Use according to claim 37, characterized in that said at least one glycidyl ester is glycidyl methacrylate.
39. Use of a terpolymer obtainable by polymerizing ethylene with
i) at least one acrylic ester of the formula:
Figure US20020001714A1-20020103-C00036
wherein R1 is H or CH3, R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms, and R3 is hydrogen or an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
ii) at least one glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00037
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3,
as tree retardant additive in a polymeric composition for coating an electric cable.
40. Use of a terpolymer obtainable by polymerizing ethylene with
i) at least one vinyl ester of a carboxylic acid of the formula:
Figure US20020001714A1-20020103-C00038
wherein R2 is an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms;
ii) at least one glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00039
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3,
as tree retardant additive in a polymeric composition for coating an electric cable.
41. Use according to claims 39 or 40, characterized in that said terpolymer has a Melt Index of from 0.1 g/10′ to 40 g/10′.
42. Use according to claims 39 or 40, characterized in that said at least one glycidyl ester is glycidyl methacrylate.
43. Use of a terpolymer obtainable by polymerizing ethylene with at least one glycidyl ester of the formula:
Figure US20020001714A1-20020103-C00040
wherein R3 and R5 are independently H, an alkyl or aryl hydrocarbon group, linear or branched, preferably a phenyl, having 1 to 10 carbon atoms; R1 is H or CH3,
as tree retardant additive in a polymeric composition for coating an electric cable.
44. Use according to claim 43, characterized in that said at least one glycidyl ester is glycidyl methacrylate.
45. Use according to claim 43, characterized in that said copolymer has a Melt Index of from 0.1 g/10′ to 40 g/10′.
US09/791,225 1995-06-21 2001-02-22 Electric cable coated with polyolefin and polymer with ester and epoxy groups Expired - Lifetime US6436536B2 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110240330A1 (en) * 2008-10-09 2011-10-06 Arkema France Semiconducting composition for electric cables

Families Citing this family (184)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1276762B1 (en) * 1995-06-21 1997-11-03 Pirelli Cavi S P A Ora Pirelli POLYMER COMPOSITION FOR THE COVERING OF ELECTRIC CABLES HAVING AN IMPROVED RESISTANCE TO "WATER TREEING" AND ELECTRIC CABLE
SE504455C2 (en) 1995-07-10 1997-02-17 Borealis Polymers Oy Cable sheath composition, its use and methods for its manufacture
US6165387A (en) * 1997-02-04 2000-12-26 Borealis A/S Composition for electric cables
SE508564C2 (en) * 1997-02-04 1998-10-19 Borealis As Composition for electric cables comprising an ethylene copolymer which, as a comonomer, comprises a polyalkylene glycol monomethacrylate
SE9703798D0 (en) 1997-10-20 1997-10-20 Borealis As Electric cable and a method of composition for the production thereof
SE513362C2 (en) 1997-11-18 2000-09-04 Borealis As Procedure for reducing reactor fouling
SE9802087D0 (en) 1998-06-12 1998-06-12 Borealis Polymers Oy An insulating composition for communication cables
SE9802386D0 (en) 1998-07-03 1998-07-03 Borealis As Composition for electric cables
SE9803608D0 (en) * 1998-10-22 1998-10-22 Borealis As A composition for an electric cable
SE9804407D0 (en) 1998-12-18 1998-12-18 Borealis Polymers Oy A multimodal polymer composition
EP1191547A1 (en) * 2000-09-20 2002-03-27 Nexans Elongated object
US6989412B2 (en) * 2001-06-06 2006-01-24 Henkel Corporation Epoxy molding compounds containing phosphor and process for preparing such compositions
WO2004003939A1 (en) 2002-06-28 2004-01-08 Sergio Belli Impact resistant compact cable
EP1697948A1 (en) 2003-12-03 2006-09-06 Prysmian Cavi e Sistemi Energia S.r.l. Impact resistant cable
US7368150B2 (en) * 2004-05-14 2008-05-06 Joseph E Pritchett Method of applying a heat reflective coating to a substrate sheet
EP1605473B1 (en) * 2004-06-11 2011-05-25 Borealis Technology Oy An insulating composition for an electric power cable
PT1916672E (en) * 2006-10-27 2010-11-02 Borealis Tech Oy Flexible power cable with improved water treeing resistance
CN102604181B (en) * 2007-08-06 2014-08-13 通用电缆技术公司 Tree resistant insulation compositions
WO2009042364A1 (en) * 2007-09-25 2009-04-02 Dow Global Technologies Inc. Styrenic polymers as blend components to control adhesion between olefinic substrates
US9113347B2 (en) 2012-12-05 2015-08-18 At&T Intellectual Property I, Lp Backhaul link for distributed antenna system
US10009065B2 (en) 2012-12-05 2018-06-26 At&T Intellectual Property I, L.P. Backhaul link for distributed antenna system
US9999038B2 (en) 2013-05-31 2018-06-12 At&T Intellectual Property I, L.P. Remote distributed antenna system
US9525524B2 (en) 2013-05-31 2016-12-20 At&T Intellectual Property I, L.P. Remote distributed antenna system
US8897697B1 (en) 2013-11-06 2014-11-25 At&T Intellectual Property I, Lp Millimeter-wave surface-wave communications
US9209902B2 (en) 2013-12-10 2015-12-08 At&T Intellectual Property I, L.P. Quasi-optical coupler
US9692101B2 (en) 2014-08-26 2017-06-27 At&T Intellectual Property I, L.P. Guided wave couplers for coupling electromagnetic waves between a waveguide surface and a surface of a wire
US9768833B2 (en) 2014-09-15 2017-09-19 At&T Intellectual Property I, L.P. Method and apparatus for sensing a condition in a transmission medium of electromagnetic waves
US10063280B2 (en) 2014-09-17 2018-08-28 At&T Intellectual Property I, L.P. Monitoring and mitigating conditions in a communication network
US9628854B2 (en) 2014-09-29 2017-04-18 At&T Intellectual Property I, L.P. Method and apparatus for distributing content in a communication network
US9615269B2 (en) 2014-10-02 2017-04-04 At&T Intellectual Property I, L.P. Method and apparatus that provides fault tolerance in a communication network
US9685992B2 (en) 2014-10-03 2017-06-20 At&T Intellectual Property I, L.P. Circuit panel network and methods thereof
US9503189B2 (en) 2014-10-10 2016-11-22 At&T Intellectual Property I, L.P. Method and apparatus for arranging communication sessions in a communication system
US9973299B2 (en) 2014-10-14 2018-05-15 At&T Intellectual Property I, L.P. Method and apparatus for adjusting a mode of communication in a communication network
US9762289B2 (en) 2014-10-14 2017-09-12 At&T Intellectual Property I, L.P. Method and apparatus for transmitting or receiving signals in a transportation system
US9780834B2 (en) 2014-10-21 2017-10-03 At&T Intellectual Property I, L.P. Method and apparatus for transmitting electromagnetic waves
US9627768B2 (en) 2014-10-21 2017-04-18 At&T Intellectual Property I, L.P. Guided-wave transmission device with non-fundamental mode propagation and methods for use therewith
US9312919B1 (en) 2014-10-21 2016-04-12 At&T Intellectual Property I, Lp Transmission device with impairment compensation and methods for use therewith
US9769020B2 (en) 2014-10-21 2017-09-19 At&T Intellectual Property I, L.P. Method and apparatus for responding to events affecting communications in a communication network
US9520945B2 (en) 2014-10-21 2016-12-13 At&T Intellectual Property I, L.P. Apparatus for providing communication services and methods thereof
US9577306B2 (en) 2014-10-21 2017-02-21 At&T Intellectual Property I, L.P. Guided-wave transmission device and methods for use therewith
US9564947B2 (en) 2014-10-21 2017-02-07 At&T Intellectual Property I, L.P. Guided-wave transmission device with diversity and methods for use therewith
US9653770B2 (en) 2014-10-21 2017-05-16 At&T Intellectual Property I, L.P. Guided wave coupler, coupling module and methods for use therewith
US9800327B2 (en) 2014-11-20 2017-10-24 At&T Intellectual Property I, L.P. Apparatus for controlling operations of a communication device and methods thereof
US9680670B2 (en) 2014-11-20 2017-06-13 At&T Intellectual Property I, L.P. Transmission device with channel equalization and control and methods for use therewith
US9461706B1 (en) 2015-07-31 2016-10-04 At&T Intellectual Property I, Lp Method and apparatus for exchanging communication signals
US9654173B2 (en) 2014-11-20 2017-05-16 At&T Intellectual Property I, L.P. Apparatus for powering a communication device and methods thereof
US10340573B2 (en) 2016-10-26 2019-07-02 At&T Intellectual Property I, L.P. Launcher with cylindrical coupling device and methods for use therewith
US9997819B2 (en) 2015-06-09 2018-06-12 At&T Intellectual Property I, L.P. Transmission medium and method for facilitating propagation of electromagnetic waves via a core
US9742462B2 (en) 2014-12-04 2017-08-22 At&T Intellectual Property I, L.P. Transmission medium and communication interfaces and methods for use therewith
US10243784B2 (en) 2014-11-20 2019-03-26 At&T Intellectual Property I, L.P. System for generating topology information and methods thereof
US9954287B2 (en) 2014-11-20 2018-04-24 At&T Intellectual Property I, L.P. Apparatus for converting wireless signals and electromagnetic waves and methods thereof
US10009067B2 (en) 2014-12-04 2018-06-26 At&T Intellectual Property I, L.P. Method and apparatus for configuring a communication interface
US9544006B2 (en) 2014-11-20 2017-01-10 At&T Intellectual Property I, L.P. Transmission device with mode division multiplexing and methods for use therewith
FR3029003B1 (en) * 2014-11-26 2018-06-29 Nexans ELECTRICAL DEVICE WITH MEDIUM OR HIGH VOLTAGE
US10144036B2 (en) 2015-01-30 2018-12-04 At&T Intellectual Property I, L.P. Method and apparatus for mitigating interference affecting a propagation of electromagnetic waves guided by a transmission medium
US9876570B2 (en) 2015-02-20 2018-01-23 At&T Intellectual Property I, Lp Guided-wave transmission device with non-fundamental mode propagation and methods for use therewith
US9749013B2 (en) 2015-03-17 2017-08-29 At&T Intellectual Property I, L.P. Method and apparatus for reducing attenuation of electromagnetic waves guided by a transmission medium
US9705561B2 (en) 2015-04-24 2017-07-11 At&T Intellectual Property I, L.P. Directional coupling device and methods for use therewith
US10224981B2 (en) 2015-04-24 2019-03-05 At&T Intellectual Property I, Lp Passive electrical coupling device and methods for use therewith
US9793954B2 (en) 2015-04-28 2017-10-17 At&T Intellectual Property I, L.P. Magnetic coupling device and methods for use therewith
US9948354B2 (en) 2015-04-28 2018-04-17 At&T Intellectual Property I, L.P. Magnetic coupling device with reflective plate and methods for use therewith
US9748626B2 (en) 2015-05-14 2017-08-29 At&T Intellectual Property I, L.P. Plurality of cables having different cross-sectional shapes which are bundled together to form a transmission medium
US9871282B2 (en) 2015-05-14 2018-01-16 At&T Intellectual Property I, L.P. At least one transmission medium having a dielectric surface that is covered at least in part by a second dielectric
US9490869B1 (en) 2015-05-14 2016-11-08 At&T Intellectual Property I, L.P. Transmission medium having multiple cores and methods for use therewith
US10650940B2 (en) 2015-05-15 2020-05-12 At&T Intellectual Property I, L.P. Transmission medium having a conductive material and methods for use therewith
US10679767B2 (en) 2015-05-15 2020-06-09 At&T Intellectual Property I, L.P. Transmission medium having a conductive material and methods for use therewith
US9917341B2 (en) 2015-05-27 2018-03-13 At&T Intellectual Property I, L.P. Apparatus and method for launching electromagnetic waves and for modifying radial dimensions of the propagating electromagnetic waves
US10103801B2 (en) 2015-06-03 2018-10-16 At&T Intellectual Property I, L.P. Host node device and methods for use therewith
US10812174B2 (en) 2015-06-03 2020-10-20 At&T Intellectual Property I, L.P. Client node device and methods for use therewith
US10348391B2 (en) 2015-06-03 2019-07-09 At&T Intellectual Property I, L.P. Client node device with frequency conversion and methods for use therewith
US9912381B2 (en) 2015-06-03 2018-03-06 At&T Intellectual Property I, Lp Network termination and methods for use therewith
US10154493B2 (en) 2015-06-03 2018-12-11 At&T Intellectual Property I, L.P. Network termination and methods for use therewith
US9866309B2 (en) 2015-06-03 2018-01-09 At&T Intellectual Property I, Lp Host node device and methods for use therewith
US9913139B2 (en) 2015-06-09 2018-03-06 At&T Intellectual Property I, L.P. Signal fingerprinting for authentication of communicating devices
US9608692B2 (en) 2015-06-11 2017-03-28 At&T Intellectual Property I, L.P. Repeater and methods for use therewith
US10142086B2 (en) 2015-06-11 2018-11-27 At&T Intellectual Property I, L.P. Repeater and methods for use therewith
US9820146B2 (en) 2015-06-12 2017-11-14 At&T Intellectual Property I, L.P. Method and apparatus for authentication and identity management of communicating devices
US9667317B2 (en) 2015-06-15 2017-05-30 At&T Intellectual Property I, L.P. Method and apparatus for providing security using network traffic adjustments
US9640850B2 (en) 2015-06-25 2017-05-02 At&T Intellectual Property I, L.P. Methods and apparatus for inducing a non-fundamental wave mode on a transmission medium
US9509415B1 (en) 2015-06-25 2016-11-29 At&T Intellectual Property I, L.P. Methods and apparatus for inducing a fundamental wave mode on a transmission medium
US9865911B2 (en) 2015-06-25 2018-01-09 At&T Intellectual Property I, L.P. Waveguide system for slot radiating first electromagnetic waves that are combined into a non-fundamental wave mode second electromagnetic wave on a transmission medium
US10320586B2 (en) 2015-07-14 2019-06-11 At&T Intellectual Property I, L.P. Apparatus and methods for generating non-interfering electromagnetic waves on an insulated transmission medium
US9628116B2 (en) 2015-07-14 2017-04-18 At&T Intellectual Property I, L.P. Apparatus and methods for transmitting wireless signals
US9847566B2 (en) 2015-07-14 2017-12-19 At&T Intellectual Property I, L.P. Method and apparatus for adjusting a field of a signal to mitigate interference
US9882257B2 (en) 2015-07-14 2018-01-30 At&T Intellectual Property I, L.P. Method and apparatus for launching a wave mode that mitigates interference
US10148016B2 (en) 2015-07-14 2018-12-04 At&T Intellectual Property I, L.P. Apparatus and methods for communicating utilizing an antenna array
US9836957B2 (en) 2015-07-14 2017-12-05 At&T Intellectual Property I, L.P. Method and apparatus for communicating with premises equipment
US9853342B2 (en) 2015-07-14 2017-12-26 At&T Intellectual Property I, L.P. Dielectric transmission medium connector and methods for use therewith
US10341142B2 (en) 2015-07-14 2019-07-02 At&T Intellectual Property I, L.P. Apparatus and methods for generating non-interfering electromagnetic waves on an uninsulated conductor
US10044409B2 (en) 2015-07-14 2018-08-07 At&T Intellectual Property I, L.P. Transmission medium and methods for use therewith
US10170840B2 (en) 2015-07-14 2019-01-01 At&T Intellectual Property I, L.P. Apparatus and methods for sending or receiving electromagnetic signals
US9722318B2 (en) 2015-07-14 2017-08-01 At&T Intellectual Property I, L.P. Method and apparatus for coupling an antenna to a device
US10033108B2 (en) 2015-07-14 2018-07-24 At&T Intellectual Property I, L.P. Apparatus and methods for generating an electromagnetic wave having a wave mode that mitigates interference
US10205655B2 (en) 2015-07-14 2019-02-12 At&T Intellectual Property I, L.P. Apparatus and methods for communicating utilizing an antenna array and multiple communication paths
US10033107B2 (en) 2015-07-14 2018-07-24 At&T Intellectual Property I, L.P. Method and apparatus for coupling an antenna to a device
US9608740B2 (en) 2015-07-15 2017-03-28 At&T Intellectual Property I, L.P. Method and apparatus for launching a wave mode that mitigates interference
US9793951B2 (en) 2015-07-15 2017-10-17 At&T Intellectual Property I, L.P. Method and apparatus for launching a wave mode that mitigates interference
US10090606B2 (en) 2015-07-15 2018-10-02 At&T Intellectual Property I, L.P. Antenna system with dielectric array and methods for use therewith
US10784670B2 (en) 2015-07-23 2020-09-22 At&T Intellectual Property I, L.P. Antenna support for aligning an antenna
US9948333B2 (en) 2015-07-23 2018-04-17 At&T Intellectual Property I, L.P. Method and apparatus for wireless communications to mitigate interference
US9749053B2 (en) 2015-07-23 2017-08-29 At&T Intellectual Property I, L.P. Node device, repeater and methods for use therewith
US9871283B2 (en) 2015-07-23 2018-01-16 At&T Intellectual Property I, Lp Transmission medium having a dielectric core comprised of plural members connected by a ball and socket configuration
US9912027B2 (en) 2015-07-23 2018-03-06 At&T Intellectual Property I, L.P. Method and apparatus for exchanging communication signals
US10020587B2 (en) 2015-07-31 2018-07-10 At&T Intellectual Property I, L.P. Radial antenna and methods for use therewith
US9967173B2 (en) 2015-07-31 2018-05-08 At&T Intellectual Property I, L.P. Method and apparatus for authentication and identity management of communicating devices
US9735833B2 (en) 2015-07-31 2017-08-15 At&T Intellectual Property I, L.P. Method and apparatus for communications management in a neighborhood network
US9904535B2 (en) 2015-09-14 2018-02-27 At&T Intellectual Property I, L.P. Method and apparatus for distributing software
US10079661B2 (en) 2015-09-16 2018-09-18 At&T Intellectual Property I, L.P. Method and apparatus for use with a radio distributed antenna system having a clock reference
US10051629B2 (en) 2015-09-16 2018-08-14 At&T Intellectual Property I, L.P. Method and apparatus for use with a radio distributed antenna system having an in-band reference signal
US10136434B2 (en) 2015-09-16 2018-11-20 At&T Intellectual Property I, L.P. Method and apparatus for use with a radio distributed antenna system having an ultra-wideband control channel
US10009901B2 (en) 2015-09-16 2018-06-26 At&T Intellectual Property I, L.P. Method, apparatus, and computer-readable storage medium for managing utilization of wireless resources between base stations
US10009063B2 (en) 2015-09-16 2018-06-26 At&T Intellectual Property I, L.P. Method and apparatus for use with a radio distributed antenna system having an out-of-band reference signal
US9705571B2 (en) 2015-09-16 2017-07-11 At&T Intellectual Property I, L.P. Method and apparatus for use with a radio distributed antenna system
US9769128B2 (en) 2015-09-28 2017-09-19 At&T Intellectual Property I, L.P. Method and apparatus for encryption of communications over a network
US9729197B2 (en) 2015-10-01 2017-08-08 At&T Intellectual Property I, L.P. Method and apparatus for communicating network management traffic over a network
US9876264B2 (en) 2015-10-02 2018-01-23 At&T Intellectual Property I, Lp Communication system, guided wave switch and methods for use therewith
US10074890B2 (en) 2015-10-02 2018-09-11 At&T Intellectual Property I, L.P. Communication device and antenna with integrated light assembly
US9882277B2 (en) 2015-10-02 2018-01-30 At&T Intellectual Property I, Lp Communication device and antenna assembly with actuated gimbal mount
US10665942B2 (en) 2015-10-16 2020-05-26 At&T Intellectual Property I, L.P. Method and apparatus for adjusting wireless communications
US10355367B2 (en) 2015-10-16 2019-07-16 At&T Intellectual Property I, L.P. Antenna structure for exchanging wireless signals
US10051483B2 (en) 2015-10-16 2018-08-14 At&T Intellectual Property I, L.P. Method and apparatus for directing wireless signals
US9912419B1 (en) 2016-08-24 2018-03-06 At&T Intellectual Property I, L.P. Method and apparatus for managing a fault in a distributed antenna system
US9860075B1 (en) 2016-08-26 2018-01-02 At&T Intellectual Property I, L.P. Method and communication node for broadband distribution
US10291311B2 (en) 2016-09-09 2019-05-14 At&T Intellectual Property I, L.P. Method and apparatus for mitigating a fault in a distributed antenna system
US11032819B2 (en) 2016-09-15 2021-06-08 At&T Intellectual Property I, L.P. Method and apparatus for use with a radio distributed antenna system having a control channel reference signal
US10135146B2 (en) 2016-10-18 2018-11-20 At&T Intellectual Property I, L.P. Apparatus and methods for launching guided waves via circuits
US10340600B2 (en) 2016-10-18 2019-07-02 At&T Intellectual Property I, L.P. Apparatus and methods for launching guided waves via plural waveguide systems
US10135147B2 (en) 2016-10-18 2018-11-20 At&T Intellectual Property I, L.P. Apparatus and methods for launching guided waves via an antenna
US10811767B2 (en) 2016-10-21 2020-10-20 At&T Intellectual Property I, L.P. System and dielectric antenna with convex dielectric radome
US10374316B2 (en) 2016-10-21 2019-08-06 At&T Intellectual Property I, L.P. System and dielectric antenna with non-uniform dielectric
US9876605B1 (en) 2016-10-21 2018-01-23 At&T Intellectual Property I, L.P. Launcher and coupling system to support desired guided wave mode
US9991580B2 (en) 2016-10-21 2018-06-05 At&T Intellectual Property I, L.P. Launcher and coupling system for guided wave mode cancellation
US10312567B2 (en) 2016-10-26 2019-06-04 At&T Intellectual Property I, L.P. Launcher with planar strip antenna and methods for use therewith
US10224634B2 (en) 2016-11-03 2019-03-05 At&T Intellectual Property I, L.P. Methods and apparatus for adjusting an operational characteristic of an antenna
US10291334B2 (en) 2016-11-03 2019-05-14 At&T Intellectual Property I, L.P. System for detecting a fault in a communication system
US10498044B2 (en) 2016-11-03 2019-12-03 At&T Intellectual Property I, L.P. Apparatus for configuring a surface of an antenna
US10225025B2 (en) 2016-11-03 2019-03-05 At&T Intellectual Property I, L.P. Method and apparatus for detecting a fault in a communication system
US10535928B2 (en) 2016-11-23 2020-01-14 At&T Intellectual Property I, L.P. Antenna system and methods for use therewith
US10340601B2 (en) 2016-11-23 2019-07-02 At&T Intellectual Property I, L.P. Multi-antenna system and methods for use therewith
US10090594B2 (en) 2016-11-23 2018-10-02 At&T Intellectual Property I, L.P. Antenna system having structural configurations for assembly
US10178445B2 (en) 2016-11-23 2019-01-08 At&T Intellectual Property I, L.P. Methods, devices, and systems for load balancing between a plurality of waveguides
US10340603B2 (en) 2016-11-23 2019-07-02 At&T Intellectual Property I, L.P. Antenna system having shielded structural configurations for assembly
US10361489B2 (en) 2016-12-01 2019-07-23 At&T Intellectual Property I, L.P. Dielectric dish antenna system and methods for use therewith
US10305190B2 (en) 2016-12-01 2019-05-28 At&T Intellectual Property I, L.P. Reflecting dielectric antenna system and methods for use therewith
US10020844B2 (en) 2016-12-06 2018-07-10 T&T Intellectual Property I, L.P. Method and apparatus for broadcast communication via guided waves
US10755542B2 (en) 2016-12-06 2020-08-25 At&T Intellectual Property I, L.P. Method and apparatus for surveillance via guided wave communication
US10727599B2 (en) 2016-12-06 2020-07-28 At&T Intellectual Property I, L.P. Launcher with slot antenna and methods for use therewith
US10326494B2 (en) 2016-12-06 2019-06-18 At&T Intellectual Property I, L.P. Apparatus for measurement de-embedding and methods for use therewith
US10819035B2 (en) 2016-12-06 2020-10-27 At&T Intellectual Property I, L.P. Launcher with helical antenna and methods for use therewith
US10694379B2 (en) 2016-12-06 2020-06-23 At&T Intellectual Property I, L.P. Waveguide system with device-based authentication and methods for use therewith
US9927517B1 (en) 2016-12-06 2018-03-27 At&T Intellectual Property I, L.P. Apparatus and methods for sensing rainfall
US10439675B2 (en) 2016-12-06 2019-10-08 At&T Intellectual Property I, L.P. Method and apparatus for repeating guided wave communication signals
US10382976B2 (en) 2016-12-06 2019-08-13 At&T Intellectual Property I, L.P. Method and apparatus for managing wireless communications based on communication paths and network device positions
US10135145B2 (en) 2016-12-06 2018-11-20 At&T Intellectual Property I, L.P. Apparatus and methods for generating an electromagnetic wave along a transmission medium
US10637149B2 (en) 2016-12-06 2020-04-28 At&T Intellectual Property I, L.P. Injection molded dielectric antenna and methods for use therewith
US10547348B2 (en) 2016-12-07 2020-01-28 At&T Intellectual Property I, L.P. Method and apparatus for switching transmission mediums in a communication system
US10243270B2 (en) 2016-12-07 2019-03-26 At&T Intellectual Property I, L.P. Beam adaptive multi-feed dielectric antenna system and methods for use therewith
US10027397B2 (en) 2016-12-07 2018-07-17 At&T Intellectual Property I, L.P. Distributed antenna system and methods for use therewith
US10389029B2 (en) 2016-12-07 2019-08-20 At&T Intellectual Property I, L.P. Multi-feed dielectric antenna system with core selection and methods for use therewith
US9893795B1 (en) 2016-12-07 2018-02-13 At&T Intellectual Property I, Lp Method and repeater for broadband distribution
US10168695B2 (en) 2016-12-07 2019-01-01 At&T Intellectual Property I, L.P. Method and apparatus for controlling an unmanned aircraft
US10359749B2 (en) 2016-12-07 2019-07-23 At&T Intellectual Property I, L.P. Method and apparatus for utilities management via guided wave communication
US10446936B2 (en) 2016-12-07 2019-10-15 At&T Intellectual Property I, L.P. Multi-feed dielectric antenna system and methods for use therewith
US10139820B2 (en) 2016-12-07 2018-11-27 At&T Intellectual Property I, L.P. Method and apparatus for deploying equipment of a communication system
US9911020B1 (en) 2016-12-08 2018-03-06 At&T Intellectual Property I, L.P. Method and apparatus for tracking via a radio frequency identification device
US10389037B2 (en) 2016-12-08 2019-08-20 At&T Intellectual Property I, L.P. Apparatus and methods for selecting sections of an antenna array and use therewith
US10777873B2 (en) 2016-12-08 2020-09-15 At&T Intellectual Property I, L.P. Method and apparatus for mounting network devices
US10411356B2 (en) 2016-12-08 2019-09-10 At&T Intellectual Property I, L.P. Apparatus and methods for selectively targeting communication devices with an antenna array
US10326689B2 (en) 2016-12-08 2019-06-18 At&T Intellectual Property I, L.P. Method and system for providing alternative communication paths
US10069535B2 (en) 2016-12-08 2018-09-04 At&T Intellectual Property I, L.P. Apparatus and methods for launching electromagnetic waves having a certain electric field structure
US10530505B2 (en) 2016-12-08 2020-01-07 At&T Intellectual Property I, L.P. Apparatus and methods for launching electromagnetic waves along a transmission medium
US10916969B2 (en) 2016-12-08 2021-02-09 At&T Intellectual Property I, L.P. Method and apparatus for providing power using an inductive coupling
US10103422B2 (en) 2016-12-08 2018-10-16 At&T Intellectual Property I, L.P. Method and apparatus for mounting network devices
US10601494B2 (en) 2016-12-08 2020-03-24 At&T Intellectual Property I, L.P. Dual-band communication device and method for use therewith
US10938108B2 (en) 2016-12-08 2021-03-02 At&T Intellectual Property I, L.P. Frequency selective multi-feed dielectric antenna system and methods for use therewith
US9998870B1 (en) 2016-12-08 2018-06-12 At&T Intellectual Property I, L.P. Method and apparatus for proximity sensing
US10264586B2 (en) 2016-12-09 2019-04-16 At&T Mobility Ii Llc Cloud-based packet controller and methods for use therewith
US10340983B2 (en) 2016-12-09 2019-07-02 At&T Intellectual Property I, L.P. Method and apparatus for surveying remote sites via guided wave communications
US9838896B1 (en) 2016-12-09 2017-12-05 At&T Intellectual Property I, L.P. Method and apparatus for assessing network coverage
US9973940B1 (en) 2017-02-27 2018-05-15 At&T Intellectual Property I, L.P. Apparatus and methods for dynamic impedance matching of a guided wave launcher
US10298293B2 (en) 2017-03-13 2019-05-21 At&T Intellectual Property I, L.P. Apparatus of communication utilizing wireless network devices
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
CN112424278A (en) 2018-05-23 2021-02-26 博里利斯股份公司 Crosslinkable polyolefin composition comprising a first olefin polymer and a second olefin polymer
DE112020001702T5 (en) * 2019-04-04 2021-12-16 Sumitomo Electric Industries, Ltd. Electrical insulation composition and power cables

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5012477B2 (en) * 1972-03-24 1975-05-12
US4370517A (en) * 1977-12-29 1983-01-25 Hitachi Cable Limited Polyolefin compositions for electrical insulation
JPS56107405A (en) * 1980-01-30 1981-08-26 Showa Electric Wire & Cable Co Power cable insulating composition
JPS56107406A (en) * 1980-01-30 1981-08-26 Showa Electric Wire & Cable Co Power cable insulating composition
JP3175297B2 (en) * 1991-06-24 2001-06-11 日本油脂株式会社 Ethylene-based polymer crosslinking composition, crosslinking method and power cable
US5274013A (en) * 1992-06-01 1993-12-28 The Dow Chemical Company Moisture resistant thermoset cable jacket
JPH07220536A (en) * 1994-01-28 1995-08-18 Hitachi Cable Ltd Power cable
IT1276762B1 (en) * 1995-06-21 1997-11-03 Pirelli Cavi S P A Ora Pirelli POLYMER COMPOSITION FOR THE COVERING OF ELECTRIC CABLES HAVING AN IMPROVED RESISTANCE TO "WATER TREEING" AND ELECTRIC CABLE

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110240330A1 (en) * 2008-10-09 2011-10-06 Arkema France Semiconducting composition for electric cables

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