Classifications

• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F10/02—Ethene
• • 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
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • 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
  • C08L23/0892—Copolymers of ethene with unsaturated hydrocarbons containing atoms other than carbon or hydrogen with monomers containing atoms other than carbon, hydrogen or oxygen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
  • C08L33/04—Homopolymers or copolymers of esters
  • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
  • C08L33/10—Homopolymers or copolymers of methacrylic acid esters
  • C08L33/12—Homopolymers or copolymers of methyl methacrylate
• • 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
  • H01B3/002—Inhomogeneous material in general
  • H01B3/004—Inhomogeneous material in general with conductive additives or conductive layers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B9/00—Power cables
  • H01B9/02—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients
• • 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
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
  • C08K3/041—Carbon nanotubes
• • 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
  • C08K5/13—Phenols; Phenolates
  • C08K5/134—Phenols containing ester groups
  • C08K5/1345—Carboxylic esters of phenolcarboxylic acids
• • 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
  • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
  • C08L9/02—Copolymers with acrylonitrile

Definitions

• the present invention relates to a crosslinked polymer of ethylene, alkyl acrylate or alkyl methacrylate and unsaturated epoxide and compositions comprising this polymer.
• the invention particularly relates to the use of this composition for making electric cables.
• a medium voltage or high voltage electrical cable that is to say a cable whose applied voltage is greater than 5000 volts, comprises at least one electrically conductive wire, often made of copper or aluminum, and a layer of composition insulation isolating the wire from the environment.
• This insulating layer is generally composed of an apolar polymer, for example a crosslinked polyethylene.
• these cables furthermore comprise, between the conducting wire and the insulating layer, a first half-insulating half-conducting intermediate layer (commonly called an "internal semiconducting" layer).
• the main function of this layer is to capture the electrons coming out along the conductor wire and to homogenize the electric fields inside the cable in order to avoid premature cable degradation.
• a second semiconductor layer generally covers the insulating layer. This second semiconductor layer is commonly referred to as the "outer semiconductor layer"; Its main function is to improve the efficiency of the electric cable by avoiding leakage currents.
• such a cable generally comprises an electrically conductive wire surrounded successively by an inner semiconductor layer, an insulating layer, an outer semiconductor layer and a protective sheath.
• the inner semiconductor layer must be linked to the conductor wire and the insulating layer, while remaining peelable (in English "strippable”).
• the outer semiconductor layer may be peelable at its interface with the insulating layer or, conversely, be strongly bonded to the insulating layer (in English "fully bonded”).
• These inner and / or outer semiconductor layers may be made of a polymeric composition containing one or more crosslinked or non-crosslinked polymers.
• the semiconductor layers In an electric cable, the semiconductor layers must have dielectric properties to obtain a homogeneous electric field inside the cable and to avoid the phenomenon of dissipation of the electrical energy. This requires that the conductive compound is perfectly dispersed in the composition.
• the application US2008 / 0050588 discloses a semiconductor composition comprising a conductive compound and a homopolymer or a copolymer of multimodal polyethylene, produced by a polymerization process comprising a single site catalyst and whose density is 0. , 87 to 0.93, a melt index ranging from 1 to 30 and a polydispersity index of less than or equal to 10.
• This composition may further comprise up to 10% by weight of a copolymer chosen from ethylene-acrylate copolymers. butyl, ethylene-ethyl acrylate, ethylene-methyl acrylate and ethylene-vinyl acrylate.
• this document does not teach a good thermal stability of the semiconductor composition.
• the semiconductor composition has good thermal stability so that it does not degrade during operation of the cable but also when said cable is manufactured.
• the cable comprises a layer of a polymer which must be crosslinked, the cable undergoes a crosslinking step at a temperature which may be between 170 and 400 ° C.
• EP1065672 also discloses an outer or inner layer semiconductor composition based on a carbon black having specific properties and on ethylene and ester copolymers chosen from vinyl esters, acrylic acid esters and methacrylic acid esters. This composition does not improve the phenomenon of removal of these layers relative to the conductive wire. This document D2 does not teach a better thermal stability either. Finally, nothing is disclosed concerning rapid crosslinking of the polymers of the semiconductor layer.
• EP1025161 discloses, in addition, an internal semiconducting composition comprising a copolymer of ethylene and methyl (meth) acrylate, the mass quantity of which in (meth) methyl acrylate is preferably in the range ranging from 5 to 25% relative to the total weight of the polymer.
• the composition of D3 does not improve this phenomenon. It is also necessary that the semiconductor layer has a particularly smooth surface state and a constant thickness, especially for the inner layer. Indeed, in the opposite case, it is created what is commonly called “peak effects", which can also lead to the breakdown of the electric cable.
• the composition of D3 does not make it possible to improve this phenomenon. This document D3 does not disclose either the improvement of the dielectric properties of the composition. In addition, even if the composition has a slightly improved thermal stability, it does not significantly increase the rate of crosslinking of the polymers constituting it in comparison with compositions comprising copolymers of ethylene and alkyl (meth) acrylate different.
• a peelable outer semiconductor layer comprising either a copolymer of ethylene and vinyl acetate whose weight average molecular weight is greater than 30000 or whose melting temperature is going to from 60 to 80 ° C., ie a mixture of ethylene-vinyl acetate copolymer and a polyolefin having a melting point of 120 ° C. or more.
• This layer is only used in the outer layer and can not be used as an inner layer. The thermal stability of this layer is very insufficient. In addition, its dielectric properties are not fully satisfactory and the peak effect phenomenon is not improved.
• WO 2005/030870 A1 discloses a composition comprising at least 40% polyester, from 3 to 30% of a polymeric reinforcement comprising reactive functional groups, a reinforcing agent of particular size, and an electrically conductive compound .
• the polymeric reinforcement is not crosslinked.
• the composition has the advantage of being able to be painted. It has a resistivity very different from the semiconductor compositions used in the cables.
• WO 96/28510 A1 (D7) relates to a composition mainly comprising a polyacetal resin, an olefinic polymer comprising a glycidyl group, polydimethylsiloxane and in addition from 0.05 to 5% of carbon black relative to the total weight of the composition.
• the olefinic polymer is not crosslinked.
• the object of the invention is to improve the heat resistance of the polyacetal resin, as well as its resistance to grease and friction. This document does not concern electric cables either.
• the subject of the present invention is precisely a semi-conductive composition which adheres to numerous supports while remaining peelable. It is particularly useful as an inner and / or outer layer in an electric cable to overcome the above disadvantages.
• the invention relates to a novel polymer for the manufacture of peelable semiconductive compositions having very advantageous properties and which make it possible to facilitate the manufacture of electric cables.
• the polymer according to the invention is a polymer of ethylene, of unsaturated epoxide, and optionally of alkyl acrylate or of alkyl methacrylate, these esters being grouped under the term (meth) acrylate of alkyl hereinafter in the description ; this polymer comprises, with respect to its total mass:
• alkyl (meth) acrylate From 0 to 40% by weight of alkyl (meth) acrylate and in particular from 5 to 40%;
• the polymer according to the invention is crosslinked by a C-C bond.
• the polymer according to the invention allows the manufacture of semiconductor compositions having an improvement over the compositions of the prior art of at least one property previously described, ie an improvement of the dielectric properties and / or the thermal resistance and / or the rate of crosslinking of the polymers and / or the adhesion of this composition with a conductive wire and / or the surface state of a layer of this composition.
• compositions according to the invention comprising the above polymer make it possible to manufacture electrical cables whose properties are excellent, without the need to modify the manufacturing methods conventionally used.
• the summary of JP 06116362 (D8) discloses a composition comprising an olefinic polymer bearing epoxy groups, an epoxy group crosslinking agent and an electrically conductive carbon black.
• the epoxy functions therefore react with the crosslinking agent, this agent then entering the structure of the crosslinked polymer; the epoxy function reacts with the agent and the polymer is crosslinked by a COC bond.
• the polymer according to the invention is therefore different in that it is crosslinked by a DC bond, the epoxy functions do not react with the crosslinking agent and the polymer structure does not comprise the crosslinking agent.
• a problem with this composition is that it adheres strongly to the metal wire, which makes it difficult to use as an internal semiconductor layer. In addition, the peeling of the outer semiconductor layer of the insulating layer remains difficult.
• the epoxy functions are therefore available.
• the applicant assumes that the presence of these epoxy functions on the crosslinked polymer comprising ethylene allows the polymer to adhere to an apolar support, such as a crosslinked polyethylene, while being more easily peelable in comparison with a crosslinked polymer whose epoxy functions have reacted with a crosslinking agent.
• the presence of these epoxy functions in the crosslinked polymer comprising ethylene also makes it possible to reduce the shrinkage phenomenon when it is brought into molten contact with a metal. Although the polymer adheres with the metal, it can be peeled off by applying a simple stress, unlike the polymer whose functions have reacted with the crosslinking agent.
• the crosslinked polymer has a structure which does not comprise the crosslinking agent.
• An advantageous way to determine whether the crosslinking is carried out by a DC bond is to measure the amount of units derived from monomers carrying the epoxide function included in the crosslinked polymer. This quantity is greater than or equal to 98% of that included in the non-crosslinked polymer, preferably greater than or equal to 99%, most preferably 99.5% to 100%.
• the word polymer means a copolymer of ethylene, unsaturated epoxide and optionally alkyl acrylate or methacrylate resulting from the polymerization of ethylene with at least one unsaturated epoxide and optionally at least one acrylate or methacrylate alkyl, optionally combined with one or more other radical-polymerizable comonomers.
• the polymer according to the invention comprises, with respect to its total mass:
• the invention also relates to the use of the polymer for making electric cables.
• the invention more particularly relates to a semiconductor composition which comprises, in addition to the polymer, a conductive agent in amounts sufficient to obtain the semiconductor effect.
• composition according to the invention has surprisingly all the necessary characteristics to be advantageously used as a semiconductor composition and in particular in electric cables.
• Another object of the invention is a process for producing the crosslinked polymer comprising a step of mixing the non-crosslinked polymer with an organic peroxide and a step of crosslinking the polymer by heating the polymer.
• Another subject of the invention is a method for manufacturing the semiconductor composition comprising a step of mixing the various constituents as well as an electrical cable comprising this composition.
• the polymer according to the invention is a polymer crosslinked by a DC bond of ethylene, unsaturated epoxide, and alkyl acrylate or alkyl methacrylate, these esters being grouped under the term (meth) acrylate. alkyl hereinafter in the description; this polymer comprises in relation to its total mass
• alkyl (meth) acrylate From 0 to 40% by weight of alkyl (meth) acrylate and in particular from 5 to 40%;
• the polymer comprises, with respect to its total mass:
• the polymer according to the invention comprises, with respect to its total mass:
• the polymer according to the invention comprises, in relation to its total mass:
• the amount of ethylene is less than 75% by weight relative to the total weight of the polymer.
• the polymer of the invention may also comprise, preferably with respect to its total mass: between 69.5 and 75% by weight of ethylene;
• the alkyl chain can have up to 24 carbons. Preferred are those whose alkyl chain comprises from 1 to 12 carbon atoms, advantageously from 1 to 6, or even from 1 to 4.
• the (meth) acrylates of alkyl are n-butyl acrylate, acrylate isobutyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate and methyl acrylate.
• the alkyl (meth) acrylates are n-butyl acrylate, ethyl acrylate and methyl acrylate. Most preferably, it is methyl acrylate.
• the amount of alkyl (meth) acrylate in the polymer is, for example, in the range of from 22 to 32% relative to the total weight of polymer, preferably from 22.5% to 30%, more preferably from at 28%.
• unsaturated epoxides there may be mentioned aliphatic glycidyl esters and ethers such as allyl glycidyl ether, vinyl glycidyl ether, glycidyl maleate and itaconate, glycidyl (meth) acrylate, and alicyclic glycidyl esters and ethers such as 2-cyclohexene-1-glycidyl ether, cyclohexene-4,5-diglycidyl carboxylate, cyclohexene-4-glycidyl carboxylate, 5-norbornene-2-methyl-2-glycidyl carboxylate and endo cis-bicyclo (2,2,1) -5-heptene
• the amount of epoxide in the polymer is, for example, in the range from 0.1 to 6% by weight relative to the total weight of polymer, advantageously from 0.4 to 4% and preferably from 0.5 to at 2.5%.
• the amounts of the different monomers present in the polymer can be measured by infrared spectroscopy using the ISO8985 standard.
• the melt index of the non-crosslinked polymer is advantageously from 1 to
• the extrusion process of an electric cable is particularly improved; in particular they surprisingly allow rapid extrusion of the electric cable.
• the semiconductor layer has a particularly smooth surface state, particularly suitable for use as an inner layer. When crosslinking the polymer, the semiconductor layer has excellent dimensional and thermal stability.
• the vicat softening temperature of the polymer of the invention measured according to ASTM D 1525 is less than 90 ° C.
• the uncrosslinked polymer of ethylene, alkyl (meth) acrylate and unsaturated epoxide can be obtained by radical copolymerization of ethylene, alkyl (meth) acrylate and an unsaturated epoxide.
• the so-called radical polymerization processes usually operating at pressures between 200 and 2500 bar, may be used.
• These polymerization processes known to those skilled in the art are carried out industrially using two main types of reactors: an autoclave-type reactor or a tubular-type reactor.
• the polymer according to the invention is manufactured in an autoclave reactor.
• the polymer according to the invention is crosslinked by a DC bond.
• the crosslinking agent may not enter the crosslinked polymer.
• the crosslinked polymer according to the invention is obtainable for example by an organic peroxide (e.g., those of the Luperox ® range marketed by the applicant).
• organic peroxide is meant any hydrocarbon molecule comprising a function of peroxy type OO.
• crosslinking agents are generally present in amounts ranging from 0.2 to 4% by weight relative to the total weight of the composition, preferably from 0.4 to 2%.
• the crosslinking of the polymer is generally quantified by measuring the level of gel. This rate of freezing can be measured using method A of ASTM D2765-01 (2006).
• the gel level of the polymer is greater than or equal to 10, preferably greater than or equal to 20, for example greater than or equal to 50.
• the invention also relates to a process for producing the crosslinked polymer comprising a step of mixing the non-crosslinked polymer with an organic peroxide and a step of crosslinking the polymer by heating the polymer.
• the step of mixing the peroxide with the non-crosslinked polymer is carried out at a temperature below the degradation temperature of the peroxide, for example at a temperature ranging from 80 ° C. to 150 ° C., for example from 90 ° to 120 ° C. vs.
• This mixture can be prepared by the usual techniques for mixing thermoplastic compositions such as, for example, single-screw extrusion, twin-screw extrusion or with any type of mixer such as internal mixers, external mixers or BUSS mixers.
• the crosslinking step of the polymer is preferably carried out at a temperature greater than or equal to the degradation temperature of the peroxide, for example at a temperature between 170 and 400 ° C., advantageously between
• the polymer can be shaped and optionally combined with other materials in a multilayer structure to give it the desired final shape.
• the invention also relates to an object comprising the polymer according to the invention.
• the polymer may also be crosslinked when it is in admixture with other components in a composition, particularly when it is in a mixture in the composition according to the invention which is described below.
• the invention also relates to a semiconductor composition.
• a conductive compound which is generally carbon black.
• Any type of conductive carbon black such as, for example, acetylene black or furnace black, may be used in the invention.
• the composition has a semiconductor effect when it has a volume resistivity of less than 1000 ohm. cm measured according to the ISO3915 standard at 23 ° C, preferably less than 500 ohm. cm.
• a quantity of carbon black of 20 to 50% by weight relative to the total mass of the composition, preferably 25 to 45%, is generally used.
• the conductive compound may also be carbon nanotubes or a mixture of carbon nanotubes with carbon black.
• the amount of polymer in the semiconductor composition according to the invention may be from 1 to 90% by weight relative to the total weight of the composition, preferably from 50 to 80%, or even 55 and 75%.
• dilution polyolefin usable in the invention, mention may be made of homopolymers and copolymers of ethylene.
• the copolymers of ethylene may be copolymers of ethylene and olefins comprising from 3 to 20 carbon atoms.
• High-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, very low-density polyethylene, metallocene-catalyzed polyethylene or EPR-type ethylene and propylene rubbers may be mentioned.
• EPDM ethylene.
• ethylene and alkyl (meth) acrylate copolymers in which the alkyl chain preferably comprises from 1 to 12 carbon atoms, preferably from 1 to 4
• copolymers of ethylene and of vinyl ester as for example copolymers of ethylene and vinyl acetate.
• dilution polyolefin other than the homopolymers and copolymers of ethylene mention may for example be made of homopolymers and copolymers of propylene or isoprene.
• the dilution polyolefin is a homopolymer or a copolymer of ethylene, most preferably an ethylene-alkyl (meth) acrylate copolymer.
• the polyolefin dilution / polymer ratio is advantageously in the range from 0.1 to 10, preferably from 0.2 to 0.8.
• the mass ratio of epoxide relative to the total mass of the mixture is in the range of 0.5 to 3%, preferably from 1, 5 to 2.
• the polyolefins of the invention optionally entering the composition according to the invention are also crosslinked.
• the composition may also include additives commonly used in semiconductor compositions of electric cables.
• additives usually used in semiconductor compositions mention may be made of fillers, processing agents and lubricants, stabilizers, antioxidants and ozone protectors, additives preventing interface tree phenomena ( better known as “water tree” and “vented tree”), anti-sticking agents or hydrolysis protectors.
• fillers mention may be made of talc, calcium carbonate or clays.
• Microcrystalline waxes, paraffins or polyethylene glycol can be used as processing agents and lubricants.
• Phenolic compounds can be cited as antioxidants and protectors of ozone.
• An example of an anti-sticking agent is ethylene bis-stearamide.
• the polycarbodiimide agents can be used as hydrolysis protectors.
• the composition also comprises a polymer called "polymeric additive" chosen from acrylonitrile-butadiene copolymers, amide waxes, silicone oils, chlorosulphonated polyethylene, polychloroprene.
• polymeric additive chosen from acrylonitrile-butadiene copolymers, amide waxes, silicone oils, chlorosulphonated polyethylene, polychloroprene.
• the composition thus obtained is even more easily peelable on a polyethylene; it can be advantageously used as an outer layer.
• the thermal stability of the composition is better.
• the polymeric additive is an acrylonitrile-butadiene copolymer.
• Another object of the invention is an electrical cable comprising a layer of the composition according to the invention.
• a "pre-cable" consisting of the conductive wire, the inner semiconductor layer, the insulating layer and the outer semiconductor layer, is extruded and then wound around a drum.
• the external temperature of the pre-cable is generally around 70 ° C. during winding. At this temperature, the pre-cable may stick slightly on itself. It is then necessary either to add anti-sticking agents which can degrade the properties of the semiconductor layer, or to slow the speed of manufacture of the cable to allow its cooling.
• a surprising advantage of the composition according to the invention used in the outer layer is that it is less tacky at this temperature in comparison with the external compositions based on ethylene-vinyl acetate copolymer or ethylene-butyl acrylate conventionally used. Without being bound to any theory, the Applicant explains this phenomenon by a crystallization temperature or vicat softening of the terpolymer of the composition higher than that of the copolymers of ethylene-vinyl acetate or ethylene-butyl acrylate having a equal polarity.
• the total amount of additives excluding polymer additive relative to the total mass of the composition is in the range of 0.01 to 10%.
• the semiconductor composition comprises:
• the polymer according to the invention or a mixture of dilution polyolefin and polymer;
• the conducting compound in amounts sufficient to obtain a semiconductor effect
• the composition comprises with respect to its total mass:
• At least one of the additives normally used in semiconductor compositions the sum of the constituents making 100%.
• compositions of this embodiment may comprise the additive (s) in the amounts previously described.
• Another subject of the invention is a method of manufacturing the semiconductor composition comprising a step of mixing the various constituents.
• compositions of the invention can be prepared by the usual techniques for mixing thermoplastic compositions such as, for example, single-screw extrusion, twin-screw extrusion or with any type of mixer such as internal mixers, external mixers or stirring mixers.
• BUSS type Preferably, the temperature of the mixture is in the range from 80 to 170 ° C., for example from 80 to 150 ° C.
• the polymer according to the invention may be crosslinked when it is in admixture with other components in a composition.
• the invention also relates to a method of manufacturing the composition comprising a step of mixing the various constituents, that is to say the non-crosslinked polymer, the conductive compound, the organic peroxide, optionally a polyolefin dilution and optionally additives mentioned above.
• the manufacturing process comprises a step of crosslinking the composition.
• the mixing step is carried out at a temperature below the degradation temperature of the peroxide, for example at a temperature ranging from 80 ° C. to 150 ° C. or from 90 ° to 120 ° C.
• This mixture can be prepared by the usual techniques of mixing thermoplastic compositions such as, for example, single-screw extrusion, twin-screw extrusion or with any type of mixer such as internal mixers, external mixers or BUSS mixers.
• the crosslinking step of the composition is preferably carried out at a temperature greater than or equal to the degradation temperature of the peroxide, for example at a temperature between 170 and 400 ° C., advantageously between 200 and 380 ° C.
• the polymer can be shaped and optionally combined with other materials in a multilayer structure to give it the desired final shape. This shaping may be carried out simultaneously with the mixing step, for example by extruding an electric cable where a layer of the polymer to be crosslinked is included in the cable.
• compositions as a semiconductor layer in electrical cables. It relates particularly to the use of this composition as an inner layer and / or outer layer.
• the invention also relates to an electric cable comprising as an inner and / or outer layer a semiconductor composition according to the invention.
• the invention also relates to a cable manufacturing method.
• the cable may be formed by coextrusion of the various constituent layers comprising the conductive wire, the inner semiconductor layer, the insulating layer and the outer semiconductor layer, said inner and / or outer semi-conducting layer being according to invention.
• the method of manufacturing the cable may advantageously comprise a crosslinking step.
• This heat treatment is conventionally carried out in a range of between 170 and 400 ° C., advantageously between 200 and 380 ° C.
• Terpolymer comprising by weight 74% of ethylene, 24% of methyl acrylate and 2% of glycidyl methacrylate, having a melt index of 50 g / 10 min measured according to ASTM standard D 1238 at 190 ° C. and 2.16kg;
• Antioxidant pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate);
• Crosslinking agent di-cumyl peroxide.
• Example 1 The composition of Example 1 comprises, with respect to its total mass:
• Example 2 comprises, with respect to its total weight: 51.5% of terpolymer
• compositions according to Examples 1 and 2 comprise terpolymers crosslinked by a C-C bond.
• Example CP (Comparative)
• the composition of this example is identical to that of Example 1, with the difference that the crosslinking agent is not a peroxide but 1% of maleic acid.
• the composition according to the example CP comprises a terpolymer crosslinked by the epoxy function and thus by a COC bond.
• Example 1 (according to the invention) and of Example CP were used in a cable as an internal semiconductor layer.
• the composition of Example 1, 2 (according to the invention) and Example CP were used as external semiconductor layer.
• the cable has the following structure:
• compositions according to the invention have the expected advantages when they are used according to the conventional methods for the manufacture of an electric cable.
• Example 1 adheres to the conductive thread but remains peelable by pulling the layer of the composition.
• the composition also adheres to the polyethylene while remaining peelable.
• the composition of Example CP has good adhesion to the thread but is not peelable.
• the compositions according to Examples 1 and 2 are also more easily peelable on the crosslinked polyethylene than in the case of Example CP.

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  • 2008-10-09 FR FR0856851A patent/FR2937041B1/fr not_active Expired - Fee Related
• 2009
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  • 2009-10-08 CN CN2009801397379A patent/CN102177202A/zh active Pending
  • 2009-10-08 EP EP09755996A patent/EP2344584A1/de not_active Withdrawn
  • 2009-10-08 WO PCT/FR2009/051925 patent/WO2010040964A1/fr not_active Ceased

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