EP2148335B1 - Electrically insulative tubing layer for power cable - Google Patents

Electrically insulative tubing layer for power cable Download PDF

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Publication number
EP2148335B1
EP2148335B1 EP20090162135 EP09162135A EP2148335B1 EP 2148335 B1 EP2148335 B1 EP 2148335B1 EP 20090162135 EP20090162135 EP 20090162135 EP 09162135 A EP09162135 A EP 09162135A EP 2148335 B1 EP2148335 B1 EP 2148335B1
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EP
European Patent Office
Prior art keywords
composition
electric cable
electric
hydrocarbon resin
thermoplastic polymer
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EP20090162135
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German (de)
French (fr)
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EP2148335A1 (en
Inventor
Christèle KENSICHER
Valéry Alcaraz
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Nexans SA
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Nexans SA
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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
    • H01B7/29—Protection against damage caused by extremes of temperature or by flame
    • H01B7/295—Protection against damage caused by extremes of temperature or by flame using material resistant to flame
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/06—Insulating conductors or cables
    • H01B13/14—Insulating conductors or cables by extrusion
    • H01B13/148—Selection of the insulating material therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/22—Sheathing; Armouring; Screening; Applying other protective layers
    • H01B13/24—Sheathing; Armouring; Screening; Applying other protective layers by extrusion
    • 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

Definitions

  • the present invention relates to an electrical cable comprising one or more electrical conductors surrounded by a tubular (or tubular) polymeric layer, and to a method of manufacturing said electrical cable.
  • a conventional electrical cable comprises a set of insulated electrical conductors surrounded by a protective sheath.
  • the insulation of the electrical conductors or the protective sheath may be obtained by an extrusion said to be in compression or tamping, or a so-called tubular or tubular extrusion.
  • Compression extrusion requires a much larger amperage of the extruder motor than tubing extrusion, which involves premature wear of the extruder motor.
  • compression extrusion results in higher extruder head pressures than tubing extrusion which can also cause greater wear on extruder head tools such as punches, dies, clamps, or the like. the different threads.
  • the tubular extrusion induces a stretching of the hot polymer material at the exit of the extruder, which is not the case with the extrusion in compression.
  • the risk of tearing of the layer formed at the exit of the extruder is relatively high.
  • the cohesion of the polymeric material in the molten state at the exit of the extruder is generally not sufficient to allow tubular type extrusion, especially when the polymeric material is loaded.
  • the object of the present invention is to overcome the drawbacks of the solutions of the state of the art by offering in particular a composition used as a polymeric layer for electric cable having good mechanical properties in order to avoid the tearing of said layer during the extrusion of the composition and significantly limit the wear of the tools of the extruder during the extrusion of this composition.
  • the first subject of the present invention is an electrical cable characterized in that it comprises at least one multi-stranded electrical conductor, and electrical insulation as an extruded polymeric layer in the form of a tube of a certain thickness, the inner surface and the surface of which outer are respectively two substantially concentric cylinders, surrounding said electrical conductor stranded, said electrical insulation being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin, the extrusion of the composition being performed directly around said electrical conductor stranded.
  • the electrical cable may further comprise an assembly of at least two insulated electrical conductors, and a protective sheath (or electrical sheath) as an extruded polymeric layer in the form of a tube, surrounding said assembly, said protective sheath being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin.
  • the second subject of the present invention is an electrical cable, characterized in that it comprises an assembly of at least two insulated electrical conductors, and a protective sheath (or electrical sheath) as an extruded polymeric layer in the form of a tube of a certain thickness whose inner surface and the outer surface are respectively two substantially concentric cylinders, surrounding said assembly, said protective sheath being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin.
  • the electric cable may be such that the extrusion of the composition is carried out directly around said set of insulated electrical conductors.
  • the electric cable may further comprise at least one electrical conductor stranded, and electrical insulation as extruded polymeric layer in the form of a tube, surrounding said conductor electrical multi-strand, the electrical insulation being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin.
  • the tubular extrusion of the composition according to the present invention advantageously makes it possible to guarantee equivalent mechanical properties, even greater than those obtained with conventional compositions used in stuffing extrusion, the hydrocarbon resin thus helping to reduce the viscosity of the composition and to limit therefore the pressures inside the extruder.
  • tubular extrusion makes it possible, on the one hand, to significantly limit the amperage of the extruder motor, or in other words to limit the premature wear of the extruder motor, and on the other hand to significantly reduce tool wear at the extruder head, since this type of process does not generate pressures as high as compression extrusion
  • tubular layer means a tube-shaped layer of a certain thickness whose inner surface and the outer surface are respectively two cylinders substantially concentric.
  • the tubular layer may be an electrical insulation surrounding at least one electrical conductor of the electric cable and thus form at least one insulated electrical conductor, preferably each electrical conductor of the electrical cable is isolated in this way .
  • the electrical conductor may be a bulk or multi-strand conductor.
  • said electrical insulation is directly in contact with said electrical conductor.
  • the tubular layer may be a protective sheath (or electrical sheath) surrounding a set of at least two insulated electrical conductors.
  • the electrical sheath does not fill the interstices between the conductive elements and thus provides empty spaces between it and the insulated electrical conductors it surrounds, in particular empty spaces occupy at least 10% of the section of the electric cable.
  • the electrical jacket leaves the insulated electrical conductors free within said layer.
  • the first and the second variant can be combined.
  • the tubular extrusion is economically advantageous since it makes it possible to reduce the quantity of polymeric material used compared with a so-called compression extrusion.
  • the tubular extrusion inducing a stretch of the polymeric material at the hot extruder outlet, provides a material gain of up to 20% compared to a compression extrusion.
  • thermoplastic polymer of the composition according to the present invention is in no way limiting.
  • thermoplastic polymer can be any type of thermoplastic polymer well known to those skilled in the art capable of being extruded, the polymer can be crosslinkable or not.
  • the thermoplastic polymer is preferably an olefin polymer, selected from an olefin homopolymer, and an olefin copolymer, or a mixture thereof.
  • thermoplastic polymer is advantageously chosen from a homopolymer or copolymer of ethylene, and a homopolymer or copolymer of propylene, or a mixture thereof.
  • the thermoplastic polymer is chosen from an ethylene homopolymer, an ethylene-octene copolymer (PEO), a copolymer of ethylene and vinyl acetate (EVA), and a copolymer of ethyl propylene diene monomer (EPDM), or a mixture thereof.
  • PEO ethylene-octene copolymer
  • EVA ethylene and vinyl acetate
  • EPDM ethyl propylene diene monomer
  • thermoplastic polymer may be a mixture of several thermoplastic polymers, or a mixture of at least one major thermoplastic polymer in the mixture and at least one other polymer of different nature.
  • the tubular layer of the electric cable according to the present invention is crosslinked.
  • thermoplastic polymer of the composition is grafted silane to be crosslinked by a method well known to those skilled in the art called "silane crosslinking", and thus obtain said reticulated tubular layer.
  • the composition further comprises a crosslinking agent, such as, for example, an organic peroxide.
  • a crosslinking agent such as, for example, an organic peroxide.
  • the hydrocarbon resin according to the invention is a thermoplastic polymer (co- or homopolymer) comprising predominantly carbon and hydrogen, and optionally heteroatoms such as oxygen, nitrogen or sulfur, the hydrocarbon resin being different from thermoplastic polymer of the composition.
  • the hydrocarbon resin is preferably composed of carbon and hydrogen. It may be of the aliphatic and / or aromatic type. Its molecular weight is relatively low and can be generally between 300 g / mol and 10,000 g / mol.
  • the hydrocarbon resin preferably has a softening point ranging from 70 ° C to 160 ° C, preferably at most 140 ° C.
  • the hydrocarbon resin comprises as monomeric unit (or elementary unit) a C-5 alkyl chain, preferably the hydrocarbon resin is in this case aliphatic.
  • this type of resin preferably has a softening point ranging from 75 to 115 ° C.
  • the hydrocarbon resin comprises as monomeric unit (or elementary unit) a C-9 alkyl chain, preferably the hydrocarbon resin is in this case aromatic.
  • this type of resin preferably has a softening point ranging from 100 to 140 ° C.
  • the softening point of the hydrocarbon resin is determined according to the Ring & Ball method according to ASTM E 28.
  • hydrocarbon resin is typically made according to the nature of the thermoplastic polymer in the composition.
  • thermoplastic polymer of the composition Depending on the physico-chemical affinities between the thermoplastic polymer of the composition and the more or less aliphatic or aromatic nature of the hydrocarbon resin, it is well known that the mixture will be carried out so as to obtain a homogeneous mixture between the polymer and the resin hydrocarbon.
  • thermoplastic polymer is a polar polymer, for example EVA with at least 40% of vinyl acetate groups
  • hydrocarbon resin will preferably be chosen from aromatic resins.
  • thermoplastic polymer is an apolar polymer, such as, for example, ethylene-octene (PEO) copolymer or EVA with at most 28% vinyl acetate groups
  • hydrocarbon resin will preferably be chosen from aliphatic resins.
  • Table 1 summarizes the various characteristics of some hydrocarbon resins marketed by Eastman. ⁇ b> ⁇ u> Table 1 ⁇ / u> ⁇ /b> Softening point (° C) Aliphatic hydrocarbon resin Aliphatic / aromatic mixed hydrocarbon resin Aromatic hydrocarbon resin 155 Plastolyn R1 140 Endex 155 Plastolyn 290 135/145 Regalite R1125 Picco A140 110/125 Piccotac 1100E Piccotac 1105E Regalite S7125 Picoo A120 Kristalex F115 Kristalex F100 Picco A100 100 Regalite R1100 Regalite R9100 Regalite R7100 Picco B100 Picco AR100 95 Piccotac 1094E Regalite S5100 Piccotac 6095E 70/90 Regalite R1090 Regalite R1010 Kristalex F85
  • the composition according to the invention may comprise at most 10 parts by weight (phr) of hydrocarbon resin per 100 parts by weight of polymer in the composition, preferably at most 8 phr of hydrocarbon resin per 100 phr of polymer in the composition, and more preferably at most 5 phr of hydrocarbon resin per 100 phr of polymer in the composition.
  • the upper limit of 10 phr of hydrocarbon resin makes it possible to advantageously limit the disturbances of the crosslinking when the composition is crosslinked, unsatisfactory creep type disturbances, and to guarantee good resistance to oils.
  • composition according to the invention may comprise at least 1 phr of hydrocarbon resin per 100 parts by weight of polymer, preferably at least 2 phr of hydrocarbon resin, 100 parts by weight of polymer.
  • the composition further comprises a flame retardant filler.
  • the flame retardant filler may be a metal hydroxide, preferably magnesium dihydroxide (MDH) or aluminum trihydroxide (ATH).
  • MDH magnesium dihydroxide
  • ATH aluminum trihydroxide
  • the composition further comprises a wax, preferably the wax is a fatty acid amide, to facilitate the extrusion of the composition.
  • the fatty acid amide can be, for example, chosen from the following families: acetamide, propionamide, n-butyramide, n-valeramide, n-caproamide, stearamide, erucamide, lauroylamide, miristique amide, arachidamide, behenamide, oleamide, ethylene- bis-stearamide, ethylene-bis-oleamide, and oleyl palmitamide, or their mixture.
  • the composition further comprises at least one protective agent chosen from antioxidants, and metal deactivators, or their mixture, the metal deactivators making it possible to limit the catalytic degradation of the tubing layer by the metal of the metal. electrical conductor when it directly surrounds said electrical conductor.
  • at least one protective agent chosen from antioxidants, and metal deactivators, or their mixture, the metal deactivators making it possible to limit the catalytic degradation of the tubing layer by the metal of the metal. electrical conductor when it directly surrounds said electrical conductor.
  • Antioxidants can typically be thioesters or hindered phenols, while metal deactivators are phenolic compounds well known to those skilled in the art.
  • the advantage of the processes of the invention, compared to a stuffing-type extrusion process, is that the hydrocarbon resin helps to reduce the viscosity of the composition and thereby limit the pressures within the composition. extruder.
  • Tubing extrusion is well known to those skilled in the art. It typically consists in using an extruder comprising a straight extrusion head and a die with a punch. The front end of the punch at the exit of the extruder is substantially at the same level as the front end of the die. The right extrusion head allows to let the flow of material through the die which gives it the shape of the desired section through the punch, namely a tubular shape.
  • the figure 1 is a schematic sectional view of an electric cable according to the present invention.
  • the electric cable 10 shown on the figure 1 comprises three electrical conductors 1, an electrical insulation 2 around each electrical conductor 1, and an outer protective sheath 3, electrically insulating, said sheath 3 surrounding all of the insulated electrical conductors.
  • the outer sheath 3 is obtained from a tubularly extruded composition according to the present invention. This tubular outer sheath 3 thus provides empty spaces 4 between it and the insulated electrical conductors that it surrounds.
  • each electrical conductor can also be obtained from a tubularly extruded composition according to the present invention.
  • the measurement of the hot creep of a material under mechanical stress is determined according to the standard NF EN 60811-2-1.
  • This corresponding test is commonly designated by the Anglemia Hot Set Test and consists in ballasting one end of a dumbbell type test piece H2 with a mass corresponding to the application of a stress equivalent to 0.2 MPa, and placing the together in an oven heated at 200 +/- 1 ° C for a period of 15 minutes.
  • the suspended mass is then removed, and the test piece is kept in the oven for another 5 minutes.
  • the remaining permanent elongation also called remanence (or remanent elongation) is then measured before being expressed in%.
  • test result would then logically be considered a failure.
  • the mechanical properties of a crosslinked layer are determined by cutting specimens of the dumbbell type H2 according to the standard NF EN 60811-1-1.
  • the specimens thus prepared and whose thickness is measured accurately, are then tested on a mechanical test bench.
  • the pulling speed is 200 mm / min.
  • the preparation of the insulating layers, and in particular their crosslinking mode, are given by way of example and are in no way limiting.
  • a first step 95 parts by weight of an ethylene polymer, 5 parts by weight of a propylene polymer and 2.5 parts by weight of a silane crosslinking agent are continuously blended and heated. alkoxysilane or carboxysilane type together with an organic peroxide, using a Buss single-screw mixer or a twin-screw extruder.
  • the propylene polymer advantageously makes it possible to improve the breaking strength and the resistance to oils of the composition, but this polymer is not essential for producing the composition according to the present invention.
  • the temperature of the mixture of this first stage is such that it typically makes it possible to use the polymer while decomposing the organic peroxide.
  • the ethylene polymer is a homopolymer of ethylene, referenced Exceed 3518CB and sold by Exxon Mobil.
  • the propylene polymer is a propylene copolymer, referenced Moplen RP315M and sold by the company Basell.
  • silane crosslinking agent and the organic peroxide are the compound marketed by Evonik under the reference Silfin 13.
  • This first step makes it possible to obtain a silane grafted polymer, more particularly a polymer mixture whose polyethylene is grafted silane, the silane grafted polymer being typically obtained in the form of granules.
  • silane graft polymer 100 parts by weight of silane graft polymer were continuously blended with the various amounts of wax, protective agents and flame retardant fillers detailed in Table 2.
  • Table 2 The amounts mentioned in Table 2 are expressed in parts by weight per 100 parts by weight of silane graft polymer in the composition. ⁇ b> ⁇ u> Table 2 ⁇ / u> ⁇ /b> AT B Silane grafted PE 100 100 Hydrocarbon resin 0 3 Wax and protective agent 6.5 6.5 Fire-retardant loads 120 120
  • the hydrocarbon resin, the wax, the protective agents and the flame retardant fillers are added to the silane graft polymer using a conventional metering hopper.
  • the hydrocarbon resin is the resin sold by Keyser & Mackay, under the reference Piccotac 1105E (hydrocarbon resin with a softening point of 110/115 ° C) (CAS 152698-66-3).
  • the wax is a fatty acid amide referenced Crodamide 203, marketed by Croda France.
  • the protective agent is a mixture of antioxidants (Irganox 1010 and / or Irganox PS 802) and metal deactivators (Irganox 1024 and / or Naugard XL1).
  • the flame retardant fillers are a mixture of metal hydroxides and zinc borate.
  • the temperature of the mixture of this second step is such that it typically allows the granules of silane graft polymer to be used while avoiding the decomposition of the flame retardant fillers.
  • This second step makes it possible to obtain a grafted silane graft polymer, the charged silane graft polymer being typically obtained in the form of granules.
  • the granules of charged silane graft polymer are used in a single-screw extruder in the presence of a catalyst for the condensation reaction of silanol groups, such as, for example, the well-known dibutyl dilaurate (DBTL). of the skilled person.
  • a catalyst for the condensation reaction of silanol groups such as, for example, the well-known dibutyl dilaurate (DBTL). of the skilled person.
  • the catalyst is typically added to the charged silane graft polymer in the form of a respective masterbatch based on a polyolefin compatible with said graft polymer.
  • the masterbatch containing said catalyst is added in an amount of about 2% by weight to the loaded silane graft polymer.
  • the mixture of the charged silane graft polymer and the silanol condensation catalyst is extruded directly onto a multi-stranded copper wire having a section of 1 mm 2 , the extrusion being carried out in a tubular manner, with a thickness of about 2 mm to form a layer A obtained from composition A, and a layer B obtained from composition B.
  • the layer A (not containing hydrocarbon resin) can not be extruded in a tubing manner since it tears during extrusion.
  • the extrusion is carried out in a compressive manner with a minimum thickness of 2 mm, this thickness being out parts filling the interstices.
  • a fourth step the respective insulating layers A and B are crosslinked in the presence of water to obtain an insulated electrical conductor (respectively, conductors A and B).
  • the crosslinking of the composition may be carried out by photochemical means such as irradiation under beta radiation, or irradiation under ultraviolet radiation in the presence of a photoinitiator; or by self-crosslinking, i.e. due to humidity and ambient temperature.
  • photochemical means such as irradiation under beta radiation, or irradiation under ultraviolet radiation in the presence of a photoinitiator; or by self-crosslinking, i.e. due to humidity and ambient temperature.
  • Crosslinking in a salt bath or in a vapor tube in the presence of an organic peroxide are two other methods that can also be envisaged.
  • the pressure mentioned in Table 3 corresponds to the pressure measured continuously by a pressure sensor situated just before the entry of the extruder head of the extruder.
  • composition according to the present invention (B) thus makes it possible to be extruded in a tubing manner, that is to say having a material gain with respect to a so-called extrusion in compression, and to have mechanical properties superior to those extrusion compression.
  • a 100 parts by weight of a copolymer of ethylene and vinyl acetate comprising 28% of vinyl acetate groups and 2.5 parts by weight of polyethylene are continuously mixed and heated.
  • a silane crosslinking agent of the alkoxysilane or carboxysilane type together with an organic peroxide using a Buss single-screw mixer or a twin-screw extruder.
  • This first step takes place under the same conditions as those mentioned in the first step for the tubular extrusion of the crosslinked PE-based composition.
  • the copolymer of ethylene and vinyl acetate is an EVA referenced Escorene UL 328 and sold by Exxon Mobil.
  • silane crosslinking agent and the organic peroxide are a single compound marketed by Evonik under the reference Silfin 59.
  • silane graft polymer 100 parts by weight of silane graft polymer (granules) were continuously mixed and heated with the various amounts of wax, protective agents and flame retardant fillers detailed in Table 4 (compositions C to E).
  • the hydrocarbon resin, the wax, the protective agents and the flame retardant fillers are added to the silane graft polymer using a conventional metering hopper.
  • the hydrocarbon resin is the resin sold by Keyser and Mackay, under the reference Piccotac 1105E (hydrocarbon resin with a softening point of 110 ° -115 ° C.) (CAS 152698-66-3).
  • the wax is a fatty acid amide referenced Crodamide 203, marketed by Croda France.
  • the protective agent is a mixture of antioxidants (Irganox 1010 and / or Irganox PS 802) and metal deactivators (Irganox 1024 and / or Naugard XL1).
  • the flame retardant fillers are a mixture of metal hydroxides and zinc borate.
  • This second step takes place under the same conditions as those mentioned in the second step for the tubular extrusion of the crosslinked PE-based composition.
  • a third step the granules of charged silane graft polymer are used under the same conditions as those mentioned in the third step for the tubular extrusion of the crosslinked PE-based composition.
  • the mixture of the charged silane graft polymer and the silanol condensation catalyst is extruded directly onto a multi-stranded copper wire having a cross-section of 1 mm 2 , the extrusion being carried out on the one hand in a tubing manner to form the layers.
  • C1, D1 and E1 with a thickness of about 2 mm, respectively obtained from the compositions C, D and E, and secondly jamming, to form the layers C2, D2 and E2 with a minimum thickness of approximately 2 mm, respectively obtained from compositions C, D and E.
  • a fourth step the respective insulating layers C to E are crosslinked in the presence of water to obtain an isolated electrical conductor (respectively, conductors C to E).
  • the pressure mentioned in Table 5 corresponds to the pressure measured continuously by a pressure sensor situated just before the entry of the extruder head of the extruder.
  • the extruded layer of the conductor C1 is not extruded satisfactorily since the thickness of said layer is inhomogeneous.
  • the speed gain between the extrusion tubing with respect to the extrusion jamming is 15%, namely the maximum speed of the extrusion tubing before the layer tears at the exit of the extruder is 34 m / mm (extruded layer D1) against 29m / mm (extruded layer C1).
  • compositions according to the present invention (D1 and E1) thus allow to be extruded in a tubing manner, that is to say by limiting the pressure inside the extruder and thus by limiting the amperage of the motor. the extruder, and to exhibit equivalent mechanical properties (extruded layer D1) or even superior (extruded layer E1) to those of a compression extrusion.

Description

La présente invention se rapporte à un câble électrique comprenant un ou plusieurs conducteurs électriques entourés par une couche tubante (ou tubulaire) polymérique, ainsi qu'à un procédé de fabrication dudit câble électrique.The present invention relates to an electrical cable comprising one or more electrical conductors surrounded by a tubular (or tubular) polymeric layer, and to a method of manufacturing said electrical cable.

Elle s'applique typiquement, mais non exclusivement, aux domaines des câbles d'énergie et/ou de télécommunication.It typically, but not exclusively, applies to the fields of energy and / or telecommunication cables.

Un câble électrique classique comprend un ensemble de conducteurs électriques isolés entouré par une gaine de protection.A conventional electrical cable comprises a set of insulated electrical conductors surrounded by a protective sheath.

L'isolation des conducteurs électriques ou la gaine de protection peut être obtenue par une extrusion dite en compression ou bourrante, ou une extrusion dite tubante ou tubulaire.The insulation of the electrical conductors or the protective sheath may be obtained by an extrusion said to be in compression or tamping, or a so-called tubular or tubular extrusion.

L'extrusion en compression nécessite un ampérage du moteur de l'extrudeuse beaucoup plus important que l'extrusion tubante, ce qui implique une usure prématurée du moteur de l'extrudeuse. De plus, l'extrusion compression entraîne des pressions en tête d'extrudeuse plus élevées que l'extrusion tubante qui peuvent provoquer également une usure plus importante des outillages en tête d'extrudeuse tels que les poinçons, les filières, les colliers de fixation ou les différents filetages.Compression extrusion requires a much larger amperage of the extruder motor than tubing extrusion, which involves premature wear of the extruder motor. In addition, compression extrusion results in higher extruder head pressures than tubing extrusion which can also cause greater wear on extruder head tools such as punches, dies, clamps, or the like. the different threads.

De son côté, l'extrusion tubante induit un étirement de la matière polymérique à chaud à la sortie de l'extrudeuse, ce qui n'est pas le cas avec l'extrusion en compression. De ce fait, le risque de déchirement de la couche formée à la sortie de l'extrudeuse est relativement important. En effet, la cohésion de la matière polymérique à l'état fondu à la sortie de l'extrudeuse n'est généralement pas suffisante pour permettre une extrusion de type tubante, notamment lorsque la matière polymérique est chargée.For its part, the tubular extrusion induces a stretching of the hot polymer material at the exit of the extruder, which is not the case with the extrusion in compression. As a result, the risk of tearing of the layer formed at the exit of the extruder is relatively high. Indeed, the cohesion of the polymeric material in the molten state at the exit of the extruder is generally not sufficient to allow tubular type extrusion, especially when the polymeric material is loaded.

L'objet de la présente invention est de pallier les inconvénients des solutions de l'état de la technique en offrant notamment une composition utilisée comme couche polymérique pour câble électrique présentant de bonnes propriétés mécaniques afin d'éviter le déchirement de ladite couche lors de l'extrusion de la composition et de limiter significativement l'usure des outillages de l'extrudeuse lors de l'extrusion de cette composition.The object of the present invention is to overcome the drawbacks of the solutions of the state of the art by offering in particular a composition used as a polymeric layer for electric cable having good mechanical properties in order to avoid the tearing of said layer during the extrusion of the composition and significantly limit the wear of the tools of the extruder during the extrusion of this composition.

La présente invention a pour premier objet un câble électrique caractérisé en ce qu'il comprend au moins un conducteur électrique multibrins, et une isolation électrique en tant que couche polymérique extrudée en forme de tube d'une certaine épaisseur dont la surface interne et la surface externe sont respectivement deux cylindres sensiblement concentriques, entourant ledit conducteur électrique multibrins, ladite isolation électrique étant obtenue à partir d'une composition comprenant un polymère thermoplastique et une résine hydrocarbonée, l'extrusion de la composition étant réalisée directement autour dudit conducteur électrique multibrins.The first subject of the present invention is an electrical cable characterized in that it comprises at least one multi-stranded electrical conductor, and electrical insulation as an extruded polymeric layer in the form of a tube of a certain thickness, the inner surface and the surface of which outer are respectively two substantially concentric cylinders, surrounding said electrical conductor stranded, said electrical insulation being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin, the extrusion of the composition being performed directly around said electrical conductor stranded.

Le câble électrique, selon le premier objet, peut comprendre en outre un ensemble d'au moins deux conducteurs électriques isolés, et une gaine de protection (ou gaine électrique) en tant que couche polymérique extrudée en forme de tube, entourant ledit ensemble, ladite gaine de protection étant obtenue à partir d'une composition comprenant un polymère thermoplastique et une résine hydrocarbonée.The electrical cable, according to the first object, may further comprise an assembly of at least two insulated electrical conductors, and a protective sheath (or electrical sheath) as an extruded polymeric layer in the form of a tube, surrounding said assembly, said protective sheath being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin.

La présente invention a pour second objet un câble électrique, caractérisé en ce qu'il comprend un ensemble d'au moins deux conducteurs électriques isolés, et une gaine de protection (ou gaine électrique) en tant que couche polymérique extrudée en forme de tube d'une certaine épaisseur dont la surface interne et la surface externe sont respectivement deux cylindres sensiblement concentriques, entourant ledit ensemble, ladite gaine de protection étant obtenue à partir d'une composition comprenant un polymère thermoplastique et une résine hydrocarbonée.The second subject of the present invention is an electrical cable, characterized in that it comprises an assembly of at least two insulated electrical conductors, and a protective sheath (or electrical sheath) as an extruded polymeric layer in the form of a tube of a certain thickness whose inner surface and the outer surface are respectively two substantially concentric cylinders, surrounding said assembly, said protective sheath being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin.

Le câble électrique, selon le second objet, peut être tel que l'extrusion de la composition est réalisée directement autour dudit ensemble de conducteurs électriques isolés.The electric cable, according to the second object, may be such that the extrusion of the composition is carried out directly around said set of insulated electrical conductors.

Le câble électrique, selon le second objet, peut comprendre en outre au moins un conducteur électrique multibrins, et une isolation électrique en tant que couche polymérique extrudée en forme de tube, entourant ledit conducteur électrique multibrins, l'isolation électrique étant obtenue à partir d'une composition comprenant un polymère thermoplastique et une résine hydrocarbonée.The electric cable, according to the second object, may further comprise at least one electrical conductor stranded, and electrical insulation as extruded polymeric layer in the form of a tube, surrounding said conductor electrical multi-strand, the electrical insulation being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin.

L'extrusion tubante de la composition conforme à la présente invention permet avantageusement de garantir des propriétés mécaniques équivalentes, voire supérieures à celles obtenues avec des compositions classiques utilisées en extrusion bourrante, la résine hydrocarbonée aidant ainsi à diminuer la viscosité de la composition et à limiter de ce fait les pressions à l'intérieur de l'extrudeuse.The tubular extrusion of the composition according to the present invention advantageously makes it possible to guarantee equivalent mechanical properties, even greater than those obtained with conventional compositions used in stuffing extrusion, the hydrocarbon resin thus helping to reduce the viscosity of the composition and to limit therefore the pressures inside the extruder.

De plus, l'extrusion tubante permet d'une part, de limiter significativement l'ampérage du moteur de l'extrudeuse, ou en d'autres termes de limiter l'usure prématurée du moteur de l'extrudeuse, et d'autre part, de diminuer significativement l'usure des outillages en tête d'extrudeuse, puisque ce type de procédé n'engendre pas des pressions aussi élevées que l'extrusion compressionIn addition, the tubular extrusion makes it possible, on the one hand, to significantly limit the amperage of the extruder motor, or in other words to limit the premature wear of the extruder motor, and on the other hand to significantly reduce tool wear at the extruder head, since this type of process does not generate pressures as high as compression extrusion

On entend par « couche tubante » (ou « couche tubulaire ») une couche en forme de tube d'une certaine épaisseur dont la surface interne et la surface externe sont respectivement deux cylindres sensiblement concentriques.The term "tubular layer" (or "tubular layer") means a tube-shaped layer of a certain thickness whose inner surface and the outer surface are respectively two cylinders substantially concentric.

Selon une première variante conforme à l'invention, la couche tubante peut être une isolation électrique entourant au moins un conducteur électrique du câble électrique et ainsi former au moins un conducteur électrique isolé, de préférence chaque conducteur électrique du câble électrique est isolé de la sorte.According to a first variant according to the invention, the tubular layer may be an electrical insulation surrounding at least one electrical conductor of the electric cable and thus form at least one insulated electrical conductor, preferably each electrical conductor of the electrical cable is isolated in this way .

Le conducteur électrique peut être un conducteur massique ou multibrins.The electrical conductor may be a bulk or multi-strand conductor.

Plus particulièrement, lorsque le conducteur est massique, ladite isolation électrique est directement en contact avec ledit conducteur électrique.More particularly, when the conductor is mass, said electrical insulation is directly in contact with said electrical conductor.

Selon une deuxième variante conforme à l'invention, la couche tubante peut être une gaine de protection (ou gaine électrique) entourant un ensemble d'au moins deux conducteurs électriques isolés.According to a second variant according to the invention, the tubular layer may be a protective sheath (or electrical sheath) surrounding a set of at least two insulated electrical conductors.

Ainsi, la gaine électrique ne remplit pas les interstices entre les éléments conducteurs et ménage ainsi des espaces vides entre elle et les conducteurs électriques isolés qu'elle entoure, notamment les espaces vides occupent au moins 10% de la section du câble électrique.Thus, the electrical sheath does not fill the interstices between the conductive elements and thus provides empty spaces between it and the insulated electrical conductors it surrounds, in particular empty spaces occupy at least 10% of the section of the electric cable.

Dans certains modes de réalisation, la gaine électrique laisse les conducteurs électriques isolés libre à l'intérieur de ladite couche.In some embodiments, the electrical jacket leaves the insulated electrical conductors free within said layer.

Selon une troisième variante conforme à l'invention, la première et la deuxième variante peuvent être combinées.According to a third variant according to the invention, the first and the second variant can be combined.

Dans le cas où la couche tubante est une gaine électrique ou une couche entourant un conducteur multibrins, l'extrusion tubante est intéressante économiquement puisqu'elle permet de diminuer la quantité de matière polymérique utilisée par rapport à une extrusion dite en compression. En effet, l'extrusion tubante, induisant un étirement de la matière polymérique à chaud à la sortie de l'extrudeuse, permet d'obtenir un gain de matière pouvant atteindre 20% par rapport à une extrusion en compression.In the case where the tubular layer is an electrical sheath or a layer surrounding a multi-stranded conductor, the tubular extrusion is economically advantageous since it makes it possible to reduce the quantity of polymeric material used compared with a so-called compression extrusion. Indeed, the tubular extrusion, inducing a stretch of the polymeric material at the hot extruder outlet, provides a material gain of up to 20% compared to a compression extrusion.

Selon l'invention, la nature du polymère thermoplastique de la composition selon la présente invention n'est nullement limitative.According to the invention, the nature of the thermoplastic polymer of the composition according to the present invention is in no way limiting.

Ce peut être tout type de polymère thermoplastique bien connu de l'homme du métier apte à pouvoir être extrudé, le polymère pouvant être réticulable ou non.It can be any type of thermoplastic polymer well known to those skilled in the art capable of being extruded, the polymer can be crosslinkable or not.

Le polymère thermoplastique est de préférence un polymère d'oléfine, choisi parmi un homopolymère d'oléfines, et un copolymère d'oléfines, ou leur mélange.The thermoplastic polymer is preferably an olefin polymer, selected from an olefin homopolymer, and an olefin copolymer, or a mixture thereof.

Notamment, le polymère thermoplastique est avantageusement choisi parmi un homopolymère ou copolymère d'éthylène, et un homopolymère ou copolymère de propylène, ou un de leurs mélanges.In particular, the thermoplastic polymer is advantageously chosen from a homopolymer or copolymer of ethylene, and a homopolymer or copolymer of propylene, or a mixture thereof.

A titre d'exemple préféré, le polymère thermoplastique est choisi parmi un homopolymère d'éthylène, un copolymère d'éthylène-octène (PEO), un copolymère d'éthylène et d'acétate de vinyle (EVA), et un copolymère d'éthyle propylène diène monomère (EPDM), ou un de leurs mélanges.As a preferred example, the thermoplastic polymer is chosen from an ethylene homopolymer, an ethylene-octene copolymer (PEO), a copolymer of ethylene and vinyl acetate (EVA), and a copolymer of ethyl propylene diene monomer (EPDM), or a mixture thereof.

Bien entendu, le polymère thermoplastique peut être un mélange de plusieurs polymères thermoplastiques, ou un mélange d'au moins un polymère thermoplastique majoritaire dans le mélange et d'au moins un autre polymère de nature différente.Of course, the thermoplastic polymer may be a mixture of several thermoplastic polymers, or a mixture of at least one major thermoplastic polymer in the mixture and at least one other polymer of different nature.

Dans un mode de réalisation avantageux, la couche tubante du câble électrique selon la présente invention est réticulée.In an advantageous embodiment, the tubular layer of the electric cable according to the present invention is crosslinked.

Plus particulièrement, le polymère thermoplastique de la composition est greffé silane afin d'être réticulé par un procédé bien connu de l'homme du métier dit « réticulation silane », et obtenir ainsi ladite couche tubante réticulées.More particularly, the thermoplastic polymer of the composition is grafted silane to be crosslinked by a method well known to those skilled in the art called "silane crosslinking", and thus obtain said reticulated tubular layer.

Dans le cas de la réticulation silane, la composition comprend en outre un agent de réticulation, tel que par exemple un peroxyde organique.In the case of silane crosslinking, the composition further comprises a crosslinking agent, such as, for example, an organic peroxide.

La résine hydrocarbonée selon l'invention est un polymère (co- ou homopolymère) thermoplastique comprenant majoritairement du carbone et de l'hydrogène, et éventuellement des hétéroatomes tels que l'oxygène, l'azote ou le soufre, la résine hydrocarbonée étant différente du polymère thermoplastique de la composition. La résine hydrocarbonée est de préférence constituée de carbone et d'hydrogène. Elle peut être de type aliphatique et/ou aromatique. Son poids moléculaire est relativement bas et peut se situer généralement entre 300 g/mol et 10000 g/mol.The hydrocarbon resin according to the invention is a thermoplastic polymer (co- or homopolymer) comprising predominantly carbon and hydrogen, and optionally heteroatoms such as oxygen, nitrogen or sulfur, the hydrocarbon resin being different from thermoplastic polymer of the composition. The hydrocarbon resin is preferably composed of carbon and hydrogen. It may be of the aliphatic and / or aromatic type. Its molecular weight is relatively low and can be generally between 300 g / mol and 10,000 g / mol.

On connaît plus généralement ce type de résines sous le nom de « résines tackifiantes ».This type of resin is more generally known under the name of "tackifying resins".

Selon l'invention, la résine hydrocarbonée a de préférence un point de ramollissement allant de 70°C à 160°C, de préférence au plus 140°C.According to the invention, the hydrocarbon resin preferably has a softening point ranging from 70 ° C to 160 ° C, preferably at most 140 ° C.

Selon une première variante, la résine hydrocarbonée comprend comme unité monomérique (ou motif élémentaire) une chaine alkyle en C-5, de préférence la résine hydrocarbonée est dans ce cas aliphatique. A titre d'exemple, ce type de résine a de préférence un point de ramollissement allant de 75 à 115°C.According to a first variant, the hydrocarbon resin comprises as monomeric unit (or elementary unit) a C-5 alkyl chain, preferably the hydrocarbon resin is in this case aliphatic. By way of example, this type of resin preferably has a softening point ranging from 75 to 115 ° C.

Selon une seconde variante, la résine hydrocarbonée comprend comme unité monomérique (ou motif élémentaire) une chaine alkyle en C-9, de préférence la résine hydrocarbonée est dans ce cas aromatique. A titre d'exemple, ce type de résine a de préférence un point de ramollissement allant de 100 à 140°C.According to a second variant, the hydrocarbon resin comprises as monomeric unit (or elementary unit) a C-9 alkyl chain, preferably the hydrocarbon resin is in this case aromatic. By way of example, this type of resin preferably has a softening point ranging from 100 to 140 ° C.

Le point de ramollissement de la résine hydrocarbonée est déterminé selon la méthode Ring & Ball conformément à la norme ASTM E 28.The softening point of the hydrocarbon resin is determined according to the Ring & Ball method according to ASTM E 28.

Le choix de la résine hydrocarbonée est typiquement fait selon la nature du polymère thermoplastique dans la composition.The choice of the hydrocarbon resin is typically made according to the nature of the thermoplastic polymer in the composition.

Selon les affinités physico-chimiques entre le polymère thermoplastique de la composition et le caractère plus ou moins aliphatique ou aromatique de la résine hydrocarbonée, il est bien connu que le mélange s'effectuera de sorte à obtenir un mélange homogène entre le polymère et la résine hydrocarbonée.Depending on the physico-chemical affinities between the thermoplastic polymer of the composition and the more or less aliphatic or aromatic nature of the hydrocarbon resin, it is well known that the mixture will be carried out so as to obtain a homogeneous mixture between the polymer and the resin hydrocarbon.

A titre d'exemples, lorsque le polymère thermoplastique est un polymère polaire, comme par exemple l'EVA avec au moins 40% de groupements acétates de vinyles, la résine hydrocarbonée sera choisie de préférence parmi les résines aromatiques.By way of examples, when the thermoplastic polymer is a polar polymer, for example EVA with at least 40% of vinyl acetate groups, the hydrocarbon resin will preferably be chosen from aromatic resins.

Lorsque le polymère thermoplastique est un polymère apolaire, comme par exemple le copolymère d'éthylène-octène (PEO) ou l'EVA avec au plus 28% de groupements acétates de vinyles, la résine hydrocarbonée sera choisie de préférence parmi les résines aliphatiques.When the thermoplastic polymer is an apolar polymer, such as, for example, ethylene-octene (PEO) copolymer or EVA with at most 28% vinyl acetate groups, the hydrocarbon resin will preferably be chosen from aliphatic resins.

Le tableau 1 suivant résume les différentes caractéristiques de quelques résines hydrocarbonées commercialisées par la société EASTMAN. Tableau 1 Point de ramollissement (°C) Résine hydrocarbonée aliphatique Résine hydrocarbonée mixte aliphatique / aromatique Résine hydrocarbonée aromatique 155 Plastolyn R1 140 Endex 155
Plastolyn 290 135/145 Regalite R1125 Picco A140 110/125 Piccotac 1100E
Piccotac 1105E Regalite S7125 Picoo A120
Kristalex F115
Kristalex F100
Picco A100 100 Regalite R1100
Regalite R9100 Regalite R7100 Picco B100
Picco AR100 95 Piccotac 1094E Regalite S5100
Piccotac 6095E 70/90 Regalite R1090
Regalite R1010 Kristalex F85 Table 1 below summarizes the various characteristics of some hydrocarbon resins marketed by Eastman. <b><u> Table 1 </ u></b> Softening point (° C) Aliphatic hydrocarbon resin Aliphatic / aromatic mixed hydrocarbon resin Aromatic hydrocarbon resin 155 Plastolyn R1 140 Endex 155
Plastolyn 290 135/145 Regalite R1125 Picco A140 110/125 Piccotac 1100E
Piccotac 1105E Regalite S7125 Picoo A120
Kristalex F115
Kristalex F100
Picco A100 100 Regalite R1100
Regalite R9100 Regalite R7100 Picco B100
Picco AR100 95 Piccotac 1094E Regalite S5100
Piccotac 6095E 70/90 Regalite R1090
Regalite R1010 Kristalex F85

La composition selon l'invention peut comprendre au plus 10 parties en poids (pcr) de résine hydrocarbonée pour 100 parties en poids de polymère dans la composition, de préférence au plus 8 pcr de résine hydrocarbonée pour 100 pcr de polymère dans la composition, et de manière plus préférentielle au plus 5 pcr de résine hydrocarbonée pour 100 pcr de polymère dans la composition.The composition according to the invention may comprise at most 10 parts by weight (phr) of hydrocarbon resin per 100 parts by weight of polymer in the composition, preferably at most 8 phr of hydrocarbon resin per 100 phr of polymer in the composition, and more preferably at most 5 phr of hydrocarbon resin per 100 phr of polymer in the composition.

La limite supérieure de 10 pcr de résine hydrocarbonée permet de limiter avantageusement les perturbations de la réticulation quand la composition est réticulée, perturbations du type fluage à chaud non satisfaisant, et de garantir une bonne résistance aux huiles.The upper limit of 10 phr of hydrocarbon resin makes it possible to advantageously limit the disturbances of the crosslinking when the composition is crosslinked, unsatisfactory creep type disturbances, and to guarantee good resistance to oils.

Par ailleurs, la composition selon l'invention peut comprendre au moins 1 pcr de résine hydrocarbonée pour 100 parties en poids de polymère, de préférence au moins 2 pcr de résine hydrocarbonée 100 parties en poids de polymère.Furthermore, the composition according to the invention may comprise at least 1 phr of hydrocarbon resin per 100 parts by weight of polymer, preferably at least 2 phr of hydrocarbon resin, 100 parts by weight of polymer.

Dans un mode de réalisation particulier, la composition comprend en outre une charge ignifugeante.In a particular embodiment, the composition further comprises a flame retardant filler.

La charge ignifugeante peut être un hydroxyde métallique, de préférence le dihydroxyde de magnésium (MDH) ou le trihydroxyde d'aluminium (ATH).The flame retardant filler may be a metal hydroxide, preferably magnesium dihydroxide (MDH) or aluminum trihydroxide (ATH).

Elle peut également être un set de bore, tel que par exemple du borate de zinc.It can also be a set of boron, such as for example zinc borate.

Dans un mode de réalisation particulier, la composition comprend en outre une cire, de préférence la cire est un amide d'acide gras, afin de faciliter l'extrusion de la composition.In a particular embodiment, the composition further comprises a wax, preferably the wax is a fatty acid amide, to facilitate the extrusion of the composition.

L'amide d'acide gras peut être par exemple choisi parmi les familles suivantes : acétamide, propionamide, n-butyramide, n-valeramide, n-caproamide, stearamide, erucamide, lauroylamide, miristique amide, arachidamide, behenamide, oleamide, ethylene-bis-stearamide, ethylene-bis-oleamide, et oleyl palmitamide, ou leur mélange.The fatty acid amide can be, for example, chosen from the following families: acetamide, propionamide, n-butyramide, n-valeramide, n-caproamide, stearamide, erucamide, lauroylamide, miristique amide, arachidamide, behenamide, oleamide, ethylene- bis-stearamide, ethylene-bis-oleamide, and oleyl palmitamide, or their mixture.

Dans un mode de réalisation particulier, la composition comprend en outre au moins un agent protecteur choisi parmi les antioxydants, et les désactivateurs de métal, ou leur mélange, les désactivateurs de métal permettant de limiter la dégradation catalytique de la couche tubante par le métal du conducteur électrique lorsqu'elle entoure directement ledit conducteur électrique.In a particular embodiment, the composition further comprises at least one protective agent chosen from antioxidants, and metal deactivators, or their mixture, the metal deactivators making it possible to limit the catalytic degradation of the tubing layer by the metal of the metal. electrical conductor when it directly surrounds said electrical conductor.

Les antioxydants peuvent être typiquement des thioesters ou des phénols encombrés, tandis que les désactivateurs de métal sont des composés phénoliques bien connus de l'homme du métier.Antioxidants can typically be thioesters or hindered phenols, while metal deactivators are phenolic compounds well known to those skilled in the art.

Un autre objet de l'invention concerne un procédé de fabrication d'un câble électrique tel que défini selon le premier objet de l'invention, le procédé comprenant les étapes consistant à :

  • préparer une composition comprenant un polymère thermoplastique et une résine hydrocarbonée, et
  • extruder de manière tubante ladite composition directement autour du conducteur électrique multibrins, pour obtenir une couche polymérique extrudée en forme de tube.
Another object of the invention relates to a method of manufacturing an electric cable as defined according to the first subject of the invention, the method comprising the steps of:
  • preparing a composition comprising a thermoplastic polymer and a hydrocarbon resin, and
  • tubularly extruding said composition directly around the multi-stranded electrical conductor, to obtain an extruded polymeric layer in the form of a tube.

Un autre objet de l'invention concerne un procédé de fabrication d'un câble électrique tel que défini selon le second objet de l'invention, le procédé comprenant les étapes consistant à :

  • préparer une composition comprenant un polymère thermoplastique et une résine hydrocarbonée, et
  • extruder de manière tubante ladite composition autour de l'ensemble de conducteurs électriques isolés, pour obtenir une couche polymérique extrudée en forme de tube.
Another subject of the invention relates to a method of manufacturing an electric cable as defined according to the second subject of the invention, the method comprising the steps of:
  • preparing a composition comprising a thermoplastic polymer and a hydrocarbon resin, and
  • tubularly extruding said composition around the set of insulated electrical conductors, to obtain an extruded polymeric layer in the form of a tube.

L'avantage des procédés de l'invention, par rapport à un procédé d'extrusion de type bourrant, est que la résine hydrocarbonée aide à diminuer la viscosité de la composition et à limiter de ce fait les pressions à l'intérieur de l'extrudeuse.The advantage of the processes of the invention, compared to a stuffing-type extrusion process, is that the hydrocarbon resin helps to reduce the viscosity of the composition and thereby limit the pressures within the composition. extruder.

Ainsi, elle limite significativement le risque de déchirement de la couche extrudée à la sortie de l'extrudeuse lors de l'extrusion tubante et permet d'avoir un gain de vitesse en production par rapport à une extrusion bourrante.Thus, it significantly limits the risk of tearing of the extruded layer at the exit of the extruder during tubular extrusion and allows to have a speed increase in production compared to a stuffing extrusion.

L'extrusion tubante est bien connue de l'homme du métier. Elle consiste typiquement à utiliser une extrudeuse comprenant une tête d'extrusion droite ainsi qu'une filière avec poinçon. L'extrémité avant du poinçon à la sortie de l'extrudeuse se trouve sensiblement au même niveau que l'extrémité avant de la filière. La tête d'extrusion droite permet de laisser passer le flux de matière par la filière qui lui donne la forme de la section voulue grâce au poinçon, à savoir une forme tubulaire.Tubing extrusion is well known to those skilled in the art. It typically consists in using an extruder comprising a straight extrusion head and a die with a punch. The front end of the punch at the exit of the extruder is substantially at the same level as the front end of the die. The right extrusion head allows to let the flow of material through the die which gives it the shape of the desired section through the punch, namely a tubular shape.

D'autres caractéristiques et avantages de la présente invention apparaîtront à la lumière des exemples qui vont suivre en référence à la figure unique annotée, lesdits exemples et figure étant donnés à titre illustratif et nullement limitatif.Other features and advantages of the present invention will appear in the light of the examples which follow with reference to the single annotated figure, said examples and figure being given for illustrative and not limiting.

La figure 1 représente une vue schématique en coupe d'un câble électrique conforme à la présente invention.The figure 1 is a schematic sectional view of an electric cable according to the present invention.

Le câble électrique 10 représenté sur la figure 1 comporte trois conducteurs électriques 1, une isolation électrique 2 autour de chaque conducteur électrique 1, et une gaine 3 extérieure de protection, électriquement isolante, ladite gaine 3 entourant l'ensemble des conducteurs électriques isolés.The electric cable 10 shown on the figure 1 comprises three electrical conductors 1, an electrical insulation 2 around each electrical conductor 1, and an outer protective sheath 3, electrically insulating, said sheath 3 surrounding all of the insulated electrical conductors.

La gaine 3 extérieure est obtenue à partir d'une composition extrudée de manière tubante conforme à la présente invention. Cette gaine 3 extérieure tubante ménage ainsi des espaces vides 4 entre elle et les conducteurs électriques isolés qu'elle entoure.The outer sheath 3 is obtained from a tubularly extruded composition according to the present invention. This tubular outer sheath 3 thus provides empty spaces 4 between it and the insulated electrical conductors that it surrounds.

L'isolation électrique 2 de chaque conducteur électrique peuvent également être obtenue à partir d'une composition extrudée de manière tubante conforme à la présente invention.The electrical insulation 2 of each electrical conductor can also be obtained from a tubularly extruded composition according to the present invention.

Afin de montrer les avantages obtenus avec les compositions selon la présente invention, le fluage à chaud ainsi que certaines propriétés mécaniques des couches isolantes selon l'invention et l'art antérieur ont été étudiées.In order to show the advantages obtained with the compositions according to the present invention, the hot creep as well as certain mechanical properties of the insulating layers according to the invention and the prior art have been studied.

La mesure du fluage à chaud d'un matériau sous contrainte mécanique est déterminée selon la norme NF EN 60811-2-1.The measurement of the hot creep of a material under mechanical stress is determined according to the standard NF EN 60811-2-1.

Ce test correspondant est communément désigné par l'anglicisme Hot Set Test et consiste à lester une extrémité d'une éprouvette de type haltère H2 avec une masse correspondant à l'application d'une contrainte équivalente à 0,2MPa, et à placer l'ensemble dans une étuve chauffée à 200+/-1 °C pendant une durée de 15 minutes.This corresponding test is commonly designated by the Anglicism Hot Set Test and consists in ballasting one end of a dumbbell type test piece H2 with a mass corresponding to the application of a stress equivalent to 0.2 MPa, and placing the together in an oven heated at 200 +/- 1 ° C for a period of 15 minutes.

Au terme de ce délai, on relève l'allongement maximale à chaud sous contrainte de l'éprouvette, exprimé en %.At the end of this period, the maximum heat stress elongation under stress of the test piece, expressed in%, is recorded.

La masse suspendue est alors retirée, et l'éprouvette est maintenue dans l'étuve pendant 5 nouvelles minutes.The suspended mass is then removed, and the test piece is kept in the oven for another 5 minutes.

L'allongement permanent restant, également appelé rémanence (ou élongation rémanente), est alors mesuré avant d'être exprimé en %.The remaining permanent elongation, also called remanence (or remanent elongation), is then measured before being expressed in%.

On rappelle que plus un matériau est réticulé, plus les valeurs d'allongement maximal sous contrainte et de rémanence seront faibles.It is recalled that the more a material is crosslinked, the higher the values of maximum elongation under stress and remanence will be low.

On précise par ailleurs que dans le cas où une éprouvette viendrait à se rompre en cours d'essai, sous l'action conjuguée de la contrainte mécanique et de la température, le résultat au test serait alors logiquement considéré comme un échec.It is also specified that in the case where a test piece breaks during the test, under the combined action of the mechanical stress and the temperature, the test result would then logically be considered a failure.

Les propriétés mécaniques d'une couche réticulée, en particulier la contrainte à la rupture et l'allongement à la rupture, sont déterminées en découpant des éprouvettes de type haltère H2 selon la norme NF EN 60811-1-1.The mechanical properties of a crosslinked layer, in particular the tensile stress and the elongation at break, are determined by cutting specimens of the dumbbell type H2 according to the standard NF EN 60811-1-1.

Les éprouvettes ainsi préparées et dont l'épaisseur est mesurée avec précision, sont ensuite testées sur un banc de traction mécanique. La vitesse de traction est de 200 mm/mn.The specimens thus prepared and whose thickness is measured accurately, are then tested on a mechanical test bench. The pulling speed is 200 mm / min.

La préparation des couches isolantes, et notamment leur mode de réticulation, sont donnés à titre d'exemple et ne sont nullement limitatif.The preparation of the insulating layers, and in particular their crosslinking mode, are given by way of example and are in no way limiting.

Extrusion tubante d'une composition à base de polyéthylène réticuléTubular extrusion of a crosslinked polyethylene composition

Dans une première étape, on mélange en continue et en chauffant 95 parties en poids d'un polymère d'éthylène, 5 parties en poids d'un polymère de propylène, et 2,5 parties en poids d'un agent de réticulation silane du type alkoxysilane ou carboxysilane ensemble avec un peroxyde organique, à l'aide d'un mélangeur monovis Buss ou d'une extrudeuse bivis.In a first step, 95 parts by weight of an ethylene polymer, 5 parts by weight of a propylene polymer and 2.5 parts by weight of a silane crosslinking agent are continuously blended and heated. alkoxysilane or carboxysilane type together with an organic peroxide, using a Buss single-screw mixer or a twin-screw extruder.

Le polymère de propylène permet avantageusement d'améliorer la résistance à la rupture et la tenue aux huiles de la composition, mais ce polymère n'est pas essentiel à la réalisation de la composition selon la présente invention.The propylene polymer advantageously makes it possible to improve the breaking strength and the resistance to oils of the composition, but this polymer is not essential for producing the composition according to the present invention.

La température du mélange de cette première étape est telle qu'elle permet typiquement de mettre en oeuvre le polymère tout en décomposant le peroxyde organique.The temperature of the mixture of this first stage is such that it typically makes it possible to use the polymer while decomposing the organic peroxide.

Le polymère d'éthylène est un homopolymère d'éthylène, référencé Exceed 3518CB et commercialisé par la société Exxon Mobil.The ethylene polymer is a homopolymer of ethylene, referenced Exceed 3518CB and sold by Exxon Mobil.

Le polymère de propylène est un copolymère de propylène, référencé Moplen RP315M et commercialisé par la société Basell.The propylene polymer is a propylene copolymer, referenced Moplen RP315M and sold by the company Basell.

L'agent de réticulation silane et le peroxyde organique sont le composé commercialisé par la société Evonik, sous la référence Silfin 13.The silane crosslinking agent and the organic peroxide are the compound marketed by Evonik under the reference Silfin 13.

Cette première étape permet d'obtenir un polymère greffé silane, plus particulièrement un mélange de polymère dont le polyéthylène est greffé silane, le polymère greffé silane étant typiquement obtenu sous forme de granulés.This first step makes it possible to obtain a silane grafted polymer, more particularly a polymer mixture whose polyethylene is grafted silane, the silane grafted polymer being typically obtained in the form of granules.

Dans une deuxième étape, on mélange en continue et en chauffant 100 parties en poids de polymère greffé silane aux différentes quantités de cire, d'agents protecteurs et de charges ignifugeantes détaillés dans le Tableau 2.In a second step, 100 parts by weight of silane graft polymer were continuously blended with the various amounts of wax, protective agents and flame retardant fillers detailed in Table 2.

Les quantités mentionnées dans le tableau 2 sont exprimées en parties en poids pour 100 parties en poids de polymère greffé silane dans la composition. Tableau 2 A B PE greffé silane 100 100 Résine hydrocarbonée 0 3 Cire et Agent protecteur 6,5 6,5 Charges ignifugeantes 120 120 The amounts mentioned in Table 2 are expressed in parts by weight per 100 parts by weight of silane graft polymer in the composition. <b><u> Table 2 </ u></b> AT B Silane grafted PE 100 100 Hydrocarbon resin 0 3 Wax and protective agent 6.5 6.5 Fire-retardant loads 120 120

Le mélange est effectué à l'aide d'un autre mélangeur monovis Buss ou d'une autre extrudeuse bivis.Mixing is performed using another Buss single screw mixer or other twin screw extruder.

La résine hydrocarbonée, la cire, les agents protecteurs et les charges ignifugeantes sont ajoutés au polymère greffé silane à l'aide d'une trémie doseuse classique.The hydrocarbon resin, the wax, the protective agents and the flame retardant fillers are added to the silane graft polymer using a conventional metering hopper.

La résine hydrocarbonée est la résine commercialisée par la société Keyser & Mackay, sous la référence Piccotac 1105E (résine hydrocarbonée avec un point de ramollissement de 110/115°C) (CAS 152698-66-3).The hydrocarbon resin is the resin sold by Keyser & Mackay, under the reference Piccotac 1105E (hydrocarbon resin with a softening point of 110/115 ° C) (CAS 152698-66-3).

La cire est un amide d'acide gras référencé Crodamide 203, commercialisé par la société Croda France.The wax is a fatty acid amide referenced Crodamide 203, marketed by Croda France.

L'agent protecteur est un mélange d'antioxydants (Irganox 1010 et/ou Irganox PS 802) et de désactivateurs de métal (Irganox 1024 et/ou Naugard XL1).The protective agent is a mixture of antioxidants (Irganox 1010 and / or Irganox PS 802) and metal deactivators (Irganox 1024 and / or Naugard XL1).

Les charges ignifugeantes sont un mélange d'hydroxydes métalliques et de borate de zinc.The flame retardant fillers are a mixture of metal hydroxides and zinc borate.

La température du mélange de cette deuxième étape est telle qu'elle permet typiquement de mettre en oeuvre les granulés de polymère greffé silane tout en évitant la décomposition des charges ignifugeantes.The temperature of the mixture of this second step is such that it typically allows the granules of silane graft polymer to be used while avoiding the decomposition of the flame retardant fillers.

Le choix des polymères, de la résine hydrocarbonée, de la cire, des antioxydants, des désactivateurs de métal et de la charge ignifugeante sont uniquement donnés à titre d'exemple, et ne sont nullement limitatifs.The choice of the polymers, the hydrocarbon resin, the wax, the antioxidants, the metal deactivators and the flame retardant filler are only given by way of example, and are in no way limiting.

Cette deuxième étape permet d'obtenir un polymère greffé silane chargé, le polymère greffé silane chargé étant typiquement obtenu sous forme de granulés.This second step makes it possible to obtain a grafted silane graft polymer, the charged silane graft polymer being typically obtained in the form of granules.

Dans une troisième étape, les granulés de polymère greffé silane chargé sont mis en oeuvre dans une extrudeuse monovis en présence d'un catalyseur de la réaction de condensation de groupements silanols, tel que par exemple le dibutyl dilaurate d'étain (DBTL) bien connu de l'homme du métier.In a third step, the granules of charged silane graft polymer are used in a single-screw extruder in the presence of a catalyst for the condensation reaction of silanol groups, such as, for example, the well-known dibutyl dilaurate (DBTL). of the skilled person.

Le catalyseur est typiquement ajouté au polymère greffé silane chargé sous forme d'un mélange maître respectif à base d'une polyoléfine compatible avec ledit polymère greffé.The catalyst is typically added to the charged silane graft polymer in the form of a respective masterbatch based on a polyolefin compatible with said graft polymer.

A titre d'exemple, le mélange maître contenant ledit catalyseur est ajouté en une quantité d'environ 2 % en poids au polymère greffé silane chargé.By way of example, the masterbatch containing said catalyst is added in an amount of about 2% by weight to the loaded silane graft polymer.

Le mélange du polymère greffé silane chargé et du catalyseur de condensation des silanols est extrudé directement sur un fil de cuivre multibrins d'une section de 1 mm2, l'extrusion s'effectuant de manière tubante, avec une épaisseur d'environ 2 mm, pour former une couche A obtenue à partir de la composition A, et une couche B obtenue à partir de la composition B.The mixture of the charged silane graft polymer and the silanol condensation catalyst is extruded directly onto a multi-stranded copper wire having a section of 1 mm 2 , the extrusion being carried out in a tubular manner, with a thickness of about 2 mm to form a layer A obtained from composition A, and a layer B obtained from composition B.

Toutefois, la couche A (ne contenant pas de résine hydrocarbonée) ne peut être extrudée de manière tubante puisqu'elle se déchire lors de l'extrusion. Ainsi, pour cet essai, l'extrusion est effectuée de manière compressive avec une épaisseur minimum de 2 mm, cette épaisseur étant hors parties comblant les interstices.However, the layer A (not containing hydrocarbon resin) can not be extruded in a tubing manner since it tears during extrusion. Thus, for this test, the extrusion is carried out in a compressive manner with a minimum thickness of 2 mm, this thickness being out parts filling the interstices.

Dans une quatrième étape, les couches isolantes respectives A et B sont réticulées en présence d'eau pour obtenir un conducteur électrique isolé (respectivement, conducteurs A et B).In a fourth step, the respective insulating layers A and B are crosslinked in the presence of water to obtain an insulated electrical conductor (respectively, conductors A and B).

Le procédé décrit ci-avant est la réticulation silane connue de l'homme du métier, en particulier sous l'appellation réticulation « dans la piscine » ou réticulation « dans le sauna ».The process described above is the silane crosslinking known to those skilled in the art, in particular under the name crosslinking "in the pool" or crosslinking "in the sauna".

Bien entendu, tout autre procédé bien connu de l'homme du métier peut être utilisé pour la réticulation du polymère de la composition selon la présente invention.Of course, any other method well known to those skilled in the art can be used for the crosslinking of the polymer of the composition according to the present invention.

Notamment, la réticulation de la composition peut s'effectuer par voie photochimique telle que irradiation sous rayonnement béta, ou irradiation sous rayonnement ultraviolet en présence d'un photoamorceur ; ou par auto réticulation c'est-à-dire du fait de l'humidité et de la température ambiante.In particular, the crosslinking of the composition may be carried out by photochemical means such as irradiation under beta radiation, or irradiation under ultraviolet radiation in the presence of a photoinitiator; or by self-crosslinking, i.e. due to humidity and ambient temperature.

La réticulation en bain de sel ou en tube vapeur en présence d'un peroxyde organique sont deux autres procédés pouvant être également envisagés.Crosslinking in a salt bath or in a vapor tube in the presence of an organic peroxide are two other methods that can also be envisaged.

Les résultats des propriétés mécaniques sont mentionnés dans le tableau 3 suivant. Tableau 3 A B Extrusion tubante Impossible Oui Extrusion compression Oui / Pression (bars) 210 195 Contrainte à la rupture (MPa) 19 22 Allongement à la rupture (%) 85 151 The results of the mechanical properties are mentioned in the following Table 3. <b><u> Table 3 </ u></b> AT B Tubular extrusion Impossible Yes Compression extrusion Yes / Pressure (bars) 210 195 Stress at break (MPa) 19 22 Elongation at break (%) 85 151

La pression mentionnée dans le tableau 3 correspond à pression mesurée en continue par un capteur de pression situé juste avant l'entrée de la tête d'extrusion de l'extrudeuse.The pressure mentioned in Table 3 corresponds to the pressure measured continuously by a pressure sensor situated just before the entry of the extruder head of the extruder.

La composition selon la présente invention (B) permet ainsi d'être extrudée de manière tubante, c'est-à-dire en ayant un gain de matière par rapport à une extrusion dite en compression, et de présenter des propriétés mécaniques supérieures à celles d'une extrusion compression.The composition according to the present invention (B) thus makes it possible to be extruded in a tubing manner, that is to say having a material gain with respect to a so-called extrusion in compression, and to have mechanical properties superior to those extrusion compression.

Extrusion tubante d'une composition à base d'EVA réticuléTubular extrusion of a cross-linked EVA composition

Dans une première étape, on mélange en continue et en chauffant un 100 parties en poids d'un copolymère d'éthylène et d'acétate de vinyle comprenant 28% de groupements d'acétates de vinyles, et 2,5 parties en poids d'un agent de réticulation silane du type alkoxysilane ou carboxysilane ensemble avec un peroxyde organique, à l'aide d'un mélangeur monovis Buss ou d'une extrudeuse bivis.In a first step, a 100 parts by weight of a copolymer of ethylene and vinyl acetate comprising 28% of vinyl acetate groups and 2.5 parts by weight of polyethylene are continuously mixed and heated. a silane crosslinking agent of the alkoxysilane or carboxysilane type together with an organic peroxide, using a Buss single-screw mixer or a twin-screw extruder.

Cette première étape se déroule dans les mêmes conditions que celles mentionnées dans la première étape pour l'extrusion tubante de la composition à base de PE réticulé.This first step takes place under the same conditions as those mentioned in the first step for the tubular extrusion of the crosslinked PE-based composition.

Le copolymère d'éthylène et d'acétate de vinyle est un EVA référencé Escorene UL 328 et commercialisé par la société Exxon mobil.The copolymer of ethylene and vinyl acetate is an EVA referenced Escorene UL 328 and sold by Exxon Mobil.

L'agent de réticulation silane et le peroxyde organique sont un seul et même composé commercialisé par la société Evonik, sous la référence Silfin 59.The silane crosslinking agent and the organic peroxide are a single compound marketed by Evonik under the reference Silfin 59.

Dans une deuxième étape, on mélange en continue et en chauffant 100 parties en poids de polymère greffé silane (granulés) aux différentes quantités de cire, d'agents protecteurs et de charges ignifugeantes détaillés dans le tableau 4 (compositions C à E).In a second step, 100 parts by weight of silane graft polymer (granules) were continuously mixed and heated with the various amounts of wax, protective agents and flame retardant fillers detailed in Table 4 (compositions C to E).

Les quantités mentionnées dans le tableau 4 sont exprimées en parties en poids pour 100 parties en poids de polymère greffé silane dans la composition. Tableau 4 C D E EVA greffé silane 100 100 100 Résine hydrocarbonée 0 2 3 Cire et Agent protecteur 6 6 6 Charge ignifugeante 170 170 170 The amounts mentioned in Table 4 are expressed in parts by weight per 100 parts by weight of silane graft polymer in the composition. <b><u> Table 4 </ u></b> VS D E Silane grafted EVA 100 100 100 Hydrocarbon resin 0 2 3 Wax and protective agent 6 6 6 Flame retardant charge 170 170 170

Le mélange est effectué à l'aide d'un autre mélangeur monovis Buss ou d'une autre extrudeuse bivis.Mixing is performed using another Buss single screw mixer or other twin screw extruder.

La résine hydrocarbonée, la cire, les agents protecteurs et les charges ignifugeantes sont ajoutés au polymère greffé silane à l'aide d'une trémie doseuse classique.The hydrocarbon resin, the wax, the protective agents and the flame retardant fillers are added to the silane graft polymer using a conventional metering hopper.

La résine hydrocarbonée est la résine commercialisée par la société Keyser et Mackay, sous la référence Piccotac 1105E (résine hydrocarbonée avec un point de ramollissement de 110/115°C) (CAS 152698-66-3).The hydrocarbon resin is the resin sold by Keyser and Mackay, under the reference Piccotac 1105E (hydrocarbon resin with a softening point of 110 ° -115 ° C.) (CAS 152698-66-3).

La cire est un amide d'acide gras référencé Crodamide 203, commercialisé par la société Croda France.The wax is a fatty acid amide referenced Crodamide 203, marketed by Croda France.

L'agent protecteur est un mélange d'antioxydants (Irganox 1010 et/ou Irganox PS 802) et de désactivateurs de métal (Irganox 1024 et/ou Naugard XL1).The protective agent is a mixture of antioxidants (Irganox 1010 and / or Irganox PS 802) and metal deactivators (Irganox 1024 and / or Naugard XL1).

Les charges ignifugeantes sont un mélange d'hydroxydes métalliques et de borate de zinc.The flame retardant fillers are a mixture of metal hydroxides and zinc borate.

Cette deuxième étape se déroule dans les mêmes conditions que celles mentionnées dans la deuxième étape pour l'extrusion tubante de la composition à base de PE réticulé.This second step takes place under the same conditions as those mentioned in the second step for the tubular extrusion of the crosslinked PE-based composition.

Le choix des polymères, de la résine hydrocarbonée, de la cire, des antioxydants, des désactivateurs de métal et de la charge ignifugeante sont uniquement donnés à titre d'exemple, et ne sont nullement limitatifs.The choice of the polymers, the hydrocarbon resin, the wax, the antioxidants, the metal deactivators and the flame retardant filler are only given by way of example, and are in no way limiting.

Dans une troisième étape, les granulés de polymère greffé silane chargé sont mis en oeuvre selon les mêmes conditions que celles mentionnées dans la troisième étape pour l'extrusion tubante de la composition à base de PE réticulé.In a third step, the granules of charged silane graft polymer are used under the same conditions as those mentioned in the third step for the tubular extrusion of the crosslinked PE-based composition.

Le mélange du polymère greffé silane chargé et du catalyseur de condensation des silanols est extrudé directement sur un fil de cuivre multibrins d'une section de 1 mm2, l'extrusion s'effectuant d'une part de manière tubante, pour former les couches C1, D1 et E1 avec une épaisseur d'environ 2 mm, obtenues respectivement à partir des compositions C, D et E, et d'autre part de manière bourrante, pour former les couches C2, D2 et E2 avec une épaisseur minimum d'environ 2 mm, obtenues respectivement à partir des compositions C, D et E.The mixture of the charged silane graft polymer and the silanol condensation catalyst is extruded directly onto a multi-stranded copper wire having a cross-section of 1 mm 2 , the extrusion being carried out on the one hand in a tubing manner to form the layers. C1, D1 and E1 with a thickness of about 2 mm, respectively obtained from the compositions C, D and E, and secondly jamming, to form the layers C2, D2 and E2 with a minimum thickness of approximately 2 mm, respectively obtained from compositions C, D and E.

Dans une quatrième étape, les couches isolantes respectives C à E sont réticulées en présence d'eau pour obtenir un conducteur électrique isolé (respectivement, conducteurs C à E).In a fourth step, the respective insulating layers C to E are crosslinked in the presence of water to obtain an isolated electrical conductor (respectively, conductors C to E).

Les résultats des propriétés mécaniques sont mentionnés dans le tableau 5 suivant. Tableau 5 C1 D1 E1 C2 D2 E2 Extrusion tubante Oui Oui Oui / / / Extrusion compression / / / Oui Oui Oui Pression (bars) 158 141 140 242 214 212 Fluage à chaud (à 250°C et à 0,2 MPa pendant 15min) - Allongement maximale à chaud sous contrainte (%) 30 25 35 50 55 65 - Elongation rémanente (%) -5 -5 0 10 10 5 Contrainte à la rupture (MPa) 14,5 14,1 15,6 14 13,6 13,8 Allongement à la rupture (%) 196 176 192 199 216 221 The results of the mechanical properties are mentioned in the following Table 5. <b><u> Table 5 </ u></b> C1 D1 E1 C2 D2 E2 Tubular extrusion Yes Yes Yes / / / Compression extrusion / / / Yes Yes Yes Pressure (bars) 158 141 140 242 214 212 Hot creep (at 250 ° C and 0.2 MPa for 15min) - Maximum stretch under heat (%) 30 25 35 50 55 65 - Remanent elongation (%) -5 -5 0 10 10 5 Stress at break (MPa) 14.5 14.1 15.6 14 13.6 13.8 Elongation at break (%) 196 176 192 199 216 221

La pression mentionnée dans le tableau 5 correspond à pression mesurée en continue par un capteur de pression situé juste avant l'entrée de la tête d'extrusion de l'extrudeuse.The pressure mentioned in Table 5 corresponds to the pressure measured continuously by a pressure sensor situated just before the entry of the extruder head of the extruder.

La couche extrudée du conducteur C1 n'est pas extrudée de manière satisfaisante puisque l'épaisseur de ladite couche est inhomogène.The extruded layer of the conductor C1 is not extruded satisfactorily since the thickness of said layer is inhomogeneous.

En outre, avec la même configuration de vis et les mêmes outils relatifs aux essais du tableau 5, le gain de vitesse entre l'extrusion tubante par rapport à l'extrusion bourrante est de 15 %, à savoir la vitesse maximale de l'extrusion tubante avant que la couche ne se déchire à la sortie de l'extrudeuse est de 34 m/mm (couche extrudée D1) contre 29m/mm (couche extrudée C1).In addition, with the same screw configuration and the same tools relating to the tests of Table 5, the speed gain between the extrusion tubing with respect to the extrusion jamming is 15%, namely the maximum speed of the extrusion tubing before the layer tears at the exit of the extruder is 34 m / mm (extruded layer D1) against 29m / mm (extruded layer C1).

Les compositions selon la présente invention (D1 et E1) permettent ainsi d'être extrudée de manière tubante, c'est-à-dire en limitant la pression à l'intérieur de l'extrudeuse et donc en limitant l'ampérage du moteur de l'extrudeuse, et de présenter des propriétés mécaniques équivalentes (couche extrudée D1), voire supérieures (couche extrudée E1) à celles d'une extrusion compression.The compositions according to the present invention (D1 and E1) thus allow to be extruded in a tubing manner, that is to say by limiting the pressure inside the extruder and thus by limiting the amperage of the motor. the extruder, and to exhibit equivalent mechanical properties (extruded layer D1) or even superior (extruded layer E1) to those of a compression extrusion.

Claims (19)

  1. An electric cable (10) characterized in that it comprises at least one multistrand electric conductor (1), and an electric insulation (2) as a tube-shaped extruded polymeric layer with a certain thickness, the internal surface and the external surface of which are two substantially concentric cylinders respectively, surrounding said multistrand electric conductor, said electric insulation (2) being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin, the extrusion of the composition being directly produced around said multistrand electric conductor.
  2. The electric cable according to claim 1, characterized in that it further comprises a set of at least two insulated electric conductors (1), and a protective sheath (3) as a tube-shaped extruded polymeric layer, surrounding said set, said protective sheath (3) being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin.
  3. An electric cable (10), characterized in that it comprises a set of at least two insulated electric conductors (1), and a protective sheath (3) as a tube-shaped extruded polymeric layer, with a certain thickness, the internal surface and the external surface of which are two substantially concentric cylinders respectively, surrounding said set, said protective sheath (3) being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin.
  4. The electric cable (10) according to claim 3, characterizing that the extrusion of the composition is directly achieved around said set of insulated electric conductors.
  5. The electric cable (10) according to claim 3 or 4, characterized in that it further comprises at least one multistrand electric conductor (1), and an electric insulation (2) as a tube-shaped extruded polymeric layer, surrounding said multistrand electric conductor, the electric insulation (2) being obtained from a composition comprising a thermoplastic polymer and a hydrocarbon resin.
  6. The electric cable according to any of the preceding claims, characterized in that the thermoplastic polymer is selected from a homopolymer of olefins, and a copolymer of olefins, or one of their mixtures.
  7. The electric cable according to any of the preceding claims, characterized in that the thermoplastic polymer is selected from a homopolymer of ethylene, a copolymer of ethylene-octene (EOP), a copolymer of ethylene and vinyl acetate (EVA), and a copolymer of ethyl propylene diene monomer (EPDM), or one of their mixtures.
  8. The electric cable according to any of the preceding claims, characterized in that the tubing layer (2, 2) is cross-linked.
  9. The electric cable according to any of the preceding claims, characterized in that the thermoplastic polymer is grafted with a silane and the composition further comprises a cross-linking agent.
  10. The electric cable according to any of the preceding claims, characterized in that the hydrocarbon resin has a softening point ranging from 70° to 160°C, as determined according to the ring & ball method in accordance with the ASTM E28 standard.
  11. The electric cable according to any of the preceding claims, characterized in that the hydrocarbon resin comprises as a monomeric unit, a C5 alkyl chain.
  12. The electric cable according to claim 11, characterized in that the hydrocarbon resin has a softening point ranging from 75 to 115°C.
  13. The electric cable according to any of the preceding claims, characterized in that the hydrocarbon resin comprises as a monomeric unit, a C9 alkyl chain.
  14. The electric cable according to claim 13, characterized in that the hydrocarbons resin has a softening point ranging from 100 to 140°C.
  15. The electric cable according to any of the preceding claims, characterized in that the composition comprises at most 10 parts by weight of hydrocarbon resin for 100 parts by weight of polymer in the composition.
  16. The electric cable according to any of the preceding claims, characterized in that the composition further comprises a flame-retardant filler.
  17. The electric cable according to any of the preceding claims, characterized in that the composition further comprises a wax.
  18. A method for manufacturing an electric cable (10) as defined according to any of claims 1, 2, 5 to 17, the method comprising the steps of:
    - preparing a composition comprising a thermoplastic polymer and a hydrocarbon resin, and
    - extruding in a tubing way said composition directly around the multistrand electric conductor, a order to obtain a tube-shaped extruded polymeric layer (2).
  19. The method for manufacturing an electric cable (10) as defined according to any of claims 3 to 17, the method comprising the steps of:
    - preparing a composition comprising a thermoplastic polymer and a hydrocarbon resin, and
    - extruding in a tubing way said composition around the set of insulated electric conductors, in order to obtain a tube-shaped extruded polymeric layer (3).
EP20090162135 2008-06-26 2009-06-08 Electrically insulative tubing layer for power cable Not-in-force EP2148335B1 (en)

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CN103474129A (en) * 2013-09-04 2013-12-25 远程电缆股份有限公司 Aging resistant environment-friendly type power cable

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CA2048197A1 (en) * 1990-08-03 1992-02-04 Melvin F. Maringer Flame retardant crosslinkable polymeric compositions
US6524702B1 (en) * 1999-08-12 2003-02-25 Dow Global Technologies Inc. Electrical devices having polymeric members
FR2808527B1 (en) * 2000-05-05 2005-11-11 Cit Alcatel COMPOSITION WITH IMPROVED THERMOMECHANICAL PROPERTIES AND METHOD FOR ITS CROSS-LINKING
FR2822833B1 (en) * 2001-03-27 2005-06-24 Nexans PROCESS FOR PRODUCING A COMPOSITION BASED ON POLYMER RETICULATED BY MEANS OF SILANE, AND COMPOSITION OBTAINED THEREBY
JP4152614B2 (en) * 2001-10-04 2008-09-17 住友化学株式会社 Resin composition for covering electric wires or cables
FR2858262B1 (en) * 2003-08-01 2006-02-10 Nexans PROCESS FOR EXTRUSION AND RETICULATION OF CHARGED POLYMERIC COMPOSITION
FR2871285B1 (en) * 2004-06-07 2006-09-08 Nexans Sa CABLE COMPRISING SEVERAL ISOLATED CONDUCTORS ENVELOPED IN THE SAME SHEATH AND METHOD OF MANUFACTURING SUCH A CABLE

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