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    • 专利摘要:
    The invention relates to a polymer composition having improved resistance to bleaching comprising at least one thermoplastic polymer material and a dielectric liquid, a process for preparing said polymer composition, a cable comprising at least one electrically insulating layer obtained from said polymeric composition, and a method of preparing said cable.
    公开号:FR3045635A1
    申请号:FR1562790
    申请日:2015-12-18
    公开日:2017-06-23
    发明作者:Gabriele Perego；Christelle Mazel；Matthias Meyer；Dimitri Charrier；Xavier Festaz
    申请人:Nexans SA；
    IPC主号:
    专利说明:

    TABLEAU 1 L'origine des composés du tableau 1 est la suivante : - copolymère de propylène statistique commercialisé par la société Borealis sous la référence Bormed RB 845 MO ; - polyéthylène linéaire de faible densité commercialisé par la société Exxon Mobil Chemicals sous la référence LLDPE LL 1002 YB ; - copolymère hétérophasé commercialisé par la société Basell Polyolefins sous la référence Adflex Q 200F ; - liquide diélectrique constitué de l,2,3,4-tétrahydro-(l-phényléthyl)-naphtalène commercialisée par la société Dow sous la référence Dowtherm RP ; et - antioxydant commercialisé par la société Ciba sous la référence Irganox B 225 qui comprend un mélange équimolaire d'Irgafos 168 et d'Irganox 1010. 2. Préparation des couches non réticulées
    Les compositions rassemblées dans le tableau 1 sont mises en oeuvre comme suit. 130 g de liquide diélectrique et 5 g d'antioxydant ont été mélangés dans un récipient en verre sous agitation.
    Le mélange résultant a ensuite été mélangé avec 850 g de copolymère de propylène, 425 g de polyéthylène linéaire de faible densité et 425 g de copolymère hétérophasé dans un récipient, puis la composition polymère résultante a été extrudée à l'aide d'une extrudeuse à double vis (« Berstorff twin screw extruder ») à une température de 200°C environ.
    Un couche comparative non conforme à l'invention a été préparée comme décrit ci-dessus mais uniquement à partir du mélange de polymères et d'oxydant. 3. Caractérisation des couches non réticulées
    La résistance au blanchiment sous contrainte a été évaluée manuellement en courbant deux couches telles que préparées ci-avant respectivement à partir des compositions Cl et II.
    La rigidité diélectrique des couches a été mesurée à l'aide d'un dispositif comprenant deux électrodes demi-sphériques en inox de diamètre 20 mm environ (une électrode sous tension et l’autre à la masse) et une huile diélectrique commercialisée par la société Bluestar Silicones sous la référence Rhodorsil 604 V 50. Par définition, la rigidité diélectrique est le rapport entre la tension de claquage et l’épaisseur de l’isolant. La tension de claquage a été mesurée à 24°C environ, avec une humidité de 50% environ, en utilisant la méthode de montée en tension par palier. La tension appliquée était une tension alternative de fréquence 50 Hz environ et la vitesse de montée de tension était de 1 kV/s environ jusqu'au claquage. 12 mesures ont été effectuées pour chaque couche non réticulée.
    La tangente delta (tan5) (ou facteur de perte) des couches telles que préparées ci-avant été mesurée par spectroscopie diélectrique à l'aide d'un appareil vendu sous la dénomination commerciale Alpha-A par la société Novocontrol Technologies.
    La tangente de l'angle de perte donne une indication sur l'énergie dissipée dans un diélectrique sous forme de chaleur.
    Les essais ont été effectués sur des couches d'épaisseur proche de 0,5 mm à 90°C, à une fréquence de 40 à 60 Hz avec une tension de 500 V adaptée selon l'épaisseur l'échantillon testé afin d'appliquer un champ électrique de 1 kV/mm. 4. Résultats
    La couche obtenue à partir de la composition II n'a montré aucun blanchiment alors que la couche obtenue à partir de la composition comparative Cl s'est montré peu résistante puisque une marque blanche au niveau de la courbure est apparue immédiatement sous la contrainte manuelle appliquée.
    Les résultats de rigidité diélectrique et de facteur de perte sont présentés dans le tableau 2 ci-dessous :
    TABLEAU 2
    Par conséquent, les compositions polymères selon l'invention présentent de meilleures propriétés de résistance au blanchiment sous contrainte tout en garantissant de bonnes propriétés diélectriques.
    The invention relates to a polymer composition having improved resistance to stress bleaching comprising at least one thermoplastic polymer material and a dielectric liquid, a process for preparing said polymer composition, a cable comprising at least one minus an electrically insulating layer obtained from said polymer composition, and a method of preparing said cable. The invention typically, but not exclusively, applies to electrical cables intended for the transmission of energy, in particular to medium-voltage (in particular 6 to 45-60 kV) or high-voltage (in particular greater than 60 kV) energy cables, and up to 400 kV), whether DC or AC, in the field of underwater or terrestrial electricity transmission.
    A medium or high voltage power transmission cable generally comprises from inside to outside: an elongated electrically conductive element, in particular made of copper or aluminum; an inner semiconductor layer surrounding said elongated electrically conductive element; an electrically insulating layer surrounding said inner semiconductor layer; an outer semiconducting layer surrounding said insulating layer; and optionally an electrically insulating protective sheath surrounding said outer semiconductor layer.
    In this type of cable, the electrically insulating layer may be a polymer layer based on a crosslinked polyethylene (XLPE). The crosslinking is generally carried out during the step of extruding the polymer composition around the elongated electrically conductive element. The use of a crosslinked polyolefin makes it possible to lead to a cable that can operate at a temperature greater than 70 ° C., or even equal to 90 ° C. However, several problems are encountered. On the one hand, crosslinked materials can not be recycled. On the other hand, cross-linking (vulcanization) to produce a homogeneous layer requires specific reaction conditions (eg in terms of time and temperature) which reduce the speed of manufacture of the cable and increase its cost of production. Finally, the crosslinking can sometimes start prematurely in the extruder and / or the extruder head, inducing degradation of the quality of the layer obtained, especially its dielectric properties.
    Alternatives have therefore been proposed such as a thermoplastic layer of low density polyethylene (LDPE) or high density (HDPE). However, a cable comprising such an electrically insulating layer can not operate at a temperature greater than about 70 ° C. for a thermoplastic layer of LDPE and greater than 80 ° C. for a thermoplastic layer HDPE, inducing a limitation of the power that can be transported in said cable and methods of manufacture.
    Electrically insulating layers based on polypropylene (eg heterophasic propylene copolymer) have been proposed. However, these layers are difficult to withstand bleaching under stress (well known under the Anglicism "stress whitening"). Thus, when these polymers are bent and / or shocked, the curved and / or shocked area becomes opaque and whitish even when the polymer is colored. This phenomenon may for example occur during winding at the time of installation of a cable. However, stress bleaching is not desired because it increases the risk of cracks and / or causes the formation of defects in the layer, inducing degradation of the electrical properties of said layer.
    It is known to improve the resistance to bleaching under stress by adding polyethylene. In particular, EP 1510 547 A1 discloses a polymer composition comprising from 70 to 98% by weight of a heterophase propylene copolymer comprising a phase based on a propylene homopolymer and a phase based on a copolymer of propylene and propylene. ethylene and / or one or more C4-C12 olefins and from 2 to 30% by weight of an ethylene polymer. However, this polymer composition is not optimized in terms of resistance to stress whitening and dielectric strength for use in an electrically insulating layer of a medium or high voltage cable.
    Thus, the object of the present invention is to overcome the disadvantages of the prior art and to provide an economical polymer composition using recyclable materials and can lead to an electrically insulating layer having improved mechanical properties, especially in terms of resistance to bleaching under stress, while ensuring good dielectric properties, especially in terms of dielectric strength.
    The object of the present invention is also to provide an economic cable, in particular at medium or high voltage, which can operate at temperatures above 70 ° C and having improved mechanical properties, especially in terms of resistance to stress whitening, while guaranteeing good dielectric properties, especially in terms of dielectric strength.
    The objects are achieved by the invention which will be described below. The invention firstly relates to a polymer composition comprising at least one thermoplastic polymer material based on polypropylene and a dielectric liquid, characterized in that the dielectric liquid comprises at least one compound corresponding to the following formula (I): R-A -R2 (I) wherein R1 and R2, same or different, are unsubstituted aryl groups and the element A represents a single bond or an alkylene group.
    The aryl group may comprise one or more aromatic rings, condensed or non-condensed, and preferably non-condensed.
    The aryl group may comprise from 5 to 20 carbon atoms, and preferably from 6 to 12 carbon atoms.
    Each aromatic ring may include one or more heteroatoms such as a nitrogen atom, a sulfur atom or an oxygen atom. The expression "unsubstituted aryl groups" means that each aryl group of the compound of formula (I) does not contain a monovalent substituent (s), and in particular is not substituted with one or more alkyl groups of formula CtH2t + i (eg 1 <t <5) such as methyl groups.
    The aryl groups of the compound of formula (I) are therefore not alkyl-aryl groups. The element A may be a linear, cyclic or branched alkylene group, preferably linear or cyclic, and more preferably linear.
    In particular, element A may be an alkylene group having 1 to 10 carbon atoms, and preferably having 1 to 5 carbon atoms.
    Preferably, the alkylene group is - (CH 2) n- with 1 <n <10; a group - (CHR) n- with 1 <n And wherein R is an alkyl group, preferably having 1 to 5 carbon atoms; a statistical group - (CHR) P- (CH2) m- (ie including m -CH2- and p -CHR-), with 1 <p + m <10, and R being an alkyl group, preferably having 1 to 5 carbon atoms; or a - (CHR) p1- (CH2) m- (CHR ') p2- (ie, including m -CH2-, p1-CHR- and p2 -CHR'-), with 1 <pi + m + p2 <10, and R and R 'are different alkyl groups, each preferably having 1 to 5 carbon atoms.
    In the present invention, a statistical group means that the radicals which constitute it (eg -CH2-, -CHR- and / or -CHR'-) can be randomly positioned within the element A. R (respectively R ') may be a methyl, ethyl, propyl or isopropyl group.
    When the element A (linking the aryl groups) is a branched alkylene group (eg presence of at least one of the groups R or R '), it can also be connected via the branching (eg via R or R' ) to R1 and / or R2.
    The aryl group is preferably a phenyl group, a naphthyl group or a pyridyl group, and more preferably a phenyl group.
    According to a first variant of the invention, at least one of said groups R1 or R2 of the compound of formula (I) is a phenyl group.
    According to a second variant of the invention, the two aryl groups each comprise a phenyl group.
    According to a third variant, the groups R 1 and R 2 of the compound of formula (I) are each phenyl groups.
    According to a particularly preferred embodiment of the invention, the compound of formula (I) can be diphenylethane (ie R1 = R2 = phenyl and A = -CH2-), diphenylmethane (ie R1 = R2 = phenyl and A = -CH2-CH2-) or 1,2,3,4-tetrahydro- (1-phenylethyl) -naphthalene (ie R1 = R2 = phenyl and A = -CHCH3-CH- (CH2) 3-) ·
    I
    The dielectric liquid is generally liquid at about 20-25 ° C.
    The dielectric liquid may comprise at least about 50% by weight of at least one compound of formula (I), and preferably at least about 80% by weight of at least one compound of formula (I), with respect to total mass of the dielectric liquid. With this minimum amount of compound (s) (I), the resistance to stress whitening is improved.
    Preferably, the dielectric liquid consists solely of a compound of formula (I) or of several compounds of formula (I).
    The ratio of the number of aromatic carbon atoms to the total number of carbon atoms in the dielectric liquid may be greater than or equal to about 0.6; and preferably greater than about 0.6.
    The ratio of the number of aromatic carbon atoms to the total number of carbon atoms in the dielectric liquid can be determined according to ASTM D3238 or on the basis of the chemical formula.
    The presence of a compound of formula (I) in the polymer composition makes it possible to improve the resistance to stress whitening of the electrically insulating layer of an electric cable, while guaranteeing good dielectric strength. Moreover, the presence of a thermoplastic polymer material based on polypropylene makes it possible to increase the operating temperature of the cable to 90 ° C.-110 ° C.
    Preferably, the dielectric liquid has a boiling point greater than about 250 ° C.
    Thus, the dielectric liquid of the polymer composition of the invention can be handled safely at room temperature (low volatility) and at the temperatures required by the shaping process of the electrically insulating layer (eg extrusion), while ensuring the forming a homogeneous blend homogeneous with the polymeric material of the polymer composition of the invention.
    The polypropylene thermoplastic polymeric material may comprise at least one homopolymer or copolymer of propylene (Pi), and at least one homopolymer or copolymer of olefin a (P2).
    In particular, the propylene copolymer Pi may be a random copolymer of propylene. By way of examples of propylene copolymers Pi, mention may be made of propylene and olefin copolymers, the olefin being especially chosen from ethylene and an olefin a different from propylene. The olefin which is different from propylene can correspond to the formula CH 2 CHCH-R 3, in which R 3 is a linear or branched alkyl group having from 2 to 10 carbon atoms, and in particular be chosen from the following olefins: 1-butene, 1-pentene; 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, and a mixture thereof. The olefin of the propylene-olefin copolymer is preferably at most 15 mol% and more preferably at most 10 mol% of the copolymer.
    Copolymers of propylene and ethylene are preferred as the propylene copolymer Pi.
    The propylene copolymer Pi preferably has an elastic modulus of about 600 to about 1200 MPa. The propylene homopolymer P 1 preferably has an elastic modulus of about 1250 to 1600 MPa. The propylene homopolymer or copolymer P 1 may have a melting point greater than about 130 ° C, preferably greater than about 140 ° C, and more preferably from about 140 to 165 ° C.
    In particular, the propylene homopolymer P 1 can have a melting temperature of about 165 ° C and the propylene copolymer P 1 can have a melting temperature of about 140 to 150 ° C. The propylene homopolymer or copolymer Pi may have a melting enthalpy of from about 30 to 100 J / g.
    In particular, the propylene homopolymer P 1 can have a melting enthalpy ranging from about 80 to 90 J / g and the propylene copolymer P 1 can have a melting enthalpy ranging from about 30 to 70 J / g. The propylene homopolymer or copolymer Pi may have a melt index ranging from 0.5 to 3 g / 10 min, measured at about 230 ° C. with a load of about 2.16 kg according to the ASTM D1238-00 standard.
    According to a preferred embodiment of the invention, the propylene homopolymer or copolymer Pi represents from 40 to 70% by weight approximately of the thermoplastic polymer material based on polypropylene. The olefin homopolymer or copolymer of olefin at P2 may have the formula CH2 = CH-R4, wherein R4 is a hydrogen atom or a linear or branched alkyl group having from 1 to 12 carbon atoms. carbon, and in particular be selected from the following olefins: ethylene, propylene, 1-butene, isobutylene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, and one of their mixtures. The propylene olefin, 1-hexene or 1-octene is preferred. The olefin homopolymer or copolymer P2 can be a heterophasic copolymer comprising a propylene thermoplastic phase and a thermoplastic elastomer phase of the copolymer type of ethylene and an olefin, a polyethylene or a mixture thereof.
    The thermoplastic elastomer phase of the heterophase copolymer may represent at least about 20% by weight, and preferably at least about 45% by weight, based on the total weight of the heterophase copolymer. The olefin of the thermoplastic elastomer phase of the heterophasic copolymer may be propylene.
    The polyethylene may be a linear low density polyethylene. In the present invention, the term "low density polyethylene" means linear polyethylene having a density ranging from about 0.91 to about 0.925.
    According to a preferred embodiment of the invention, the P2 olefin homopolymer or copolymer represents about 30 to 60% by weight of the polypropylene thermoplastic polymer material.
    The thermoplastic polymer material of the polymer composition of the invention is preferably heterophasic (ie it comprises several phases). The presence of several phases generally comes from mixing two different polyolefins, such as a mixture of polypropylene and a copolymer of propylene or polyethylene.
    According to a particularly preferred embodiment of the invention, the thermoplastic polymer material comprises a copolymer of propylene and of ethylene [as propylene homopolymer or copolymer Pi] and a heterophase copolymer comprising a thermoplastic phase of the propylene type and a thermoplastic elastomer phase of copolymer type of ethylene and propylene [as homopolymer or copolymer of olefin at P2]
    The polymer composition of the invention comprises an intimate mixture of the dielectric liquid and the thermoplastic polymer material (eg it forms a homogeneous phase).
    The mass concentration of the dielectric liquid in the polymer composition is preferably less than or equal to the saturation mass concentration of said dielectric liquid in the thermoplastic polymer material.
    The saturation mass concentration at 20-25 ° C is generally in the range of about 15 to 20%. It can be determined by the liquid absorption method. In particular, plates (eg of dimensions 200 mm × 200 mm × 0.5 mm) made of polypropylene thermoplastic polymer material of the polymer composition are prepared from the corresponding raw materials, in particular by molding. Samples of these plates are weighed (initial weight = PO) and then immersed at about 20 ° C. in the dielectric liquid of the polymer composition. The mass concentration of saturation is measured by determining the weight change (in percentage) of the samples after different immersion times (eg 3, 6, 9, 12 and 15 days) and after having cleaned and dried their surface (final weight = Pf). The absorption of the dielectric liquid is determined according to the following formula: Dielectric liquid absorption% = [(Pf-Po) / Po] x 100
    The saturation concentration is reached when Pf shows a variation of less than 1% with respect to the increase in the total weight which corresponds to Pf-P0.
    According to a particular embodiment, the dielectric liquid represents from 1% to 20% by weight, preferably from 2 to 15% by weight, and more preferably from 3 to 12% by weight, relative to the mass. total of the polymer composition.
    According to a particular embodiment, the polypropylene thermoplastic polymer material is from 70% to 98% by weight, preferably from 80 to 95% by weight, and more preferably from 88 to 97% by weight approximately, relative to the total mass of the polymer composition
    The polymer composition may further comprise one or more additives.
    The additives are well known to those skilled in the art and may be selected from antioxidants, anti-UV agents, anti-copper agents, anti-water tree agents, and a mixture thereof.
    The polymer composition of the invention may typically comprise from about 0.01 to about 5% by weight, and preferably from about 0.1 to about 2% by weight of additives, based on the total weight of the polymeric composition.
    More particularly, the antioxidants make it possible to protect the polymer composition from the thermal stresses generated during the steps of manufacturing the cable or operating the cable.
    The antioxidants are preferably selected from hindered phenols, thioesters, sulfur-based antioxidants, phosphorus-based antioxidants, amine antioxidants and a mixture thereof. As examples of hindered phenols, mention may be made of pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) (Irganox® 1010), octadecyl 3- (3,5 -di-tert-butyl-4-hydroxyphenyl) propionate (Irganox® 1076), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) ) benzene (Irganox® 1330), 4,6-bis (octylthiomethyl) -o-cresol (Irgastab® KV10), 2,2'-thiobis (6-tert-butyl-4-methylphenol) (Irganox® 1081) 2,2'-thiodiethylene bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (Irganox® 1035), 2,2'-methylenebis (6-tert-butyl) -4-methylphenol), 1,2-bis (3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl) hydrazine (Irganox® MD 1024), or 2,2'-oxamido-bis (ethyl-3) ( 3,5-di-te / t-butyl-4-hydroxyphenyl) propionate). As examples of thioesters, mention may be made of didodecyl-3,3'-thiodipropionate (Irganox® PS800), distearylthiodipropionate (Irganox® PS802) or 4,6-bis (octylthiomethyl) -o-cresol (Irganox ® 1520). Examples of sulfur-based antioxidants include dioctadecyl-3,3'-thiodipropionate or didodecyl-3,3'-thiodipropionate. As examples of phosphorus-based antioxidants, mention may be made of tris (2,4-di-tert-butyl-phenyl) phosphite (Irgafos® 168) or bis (2,4-di-te / t). -butylphenyl) pentaerythritol diphosphite (Ultranox® 626). Examples of amine antioxidants include phenylene diamines (eg 1PPD or 6PPD), diphenylamine styrene, diphenylamines, mercapto benzimidazoles and 2,2,4-trimethyl-1,2-dihydroquinoline polymerized (TMQ). Examples of mixtures of antioxidants include Irganox B 225 which comprises an equimolar mixture of Irgafos 168 and Irganox 1010 as described above.
    The polymer composition is a thermoplastic polymer composition.
    It is therefore not crosslinkable.
    In particular, the polymer composition does not comprise crosslinking agents, silane coupling agents, peroxides and / or additives which allow crosslinking. Indeed, such agents degrade the thermoplastic polymer material based on polypropylene.
    The polymer composition is preferably recyclable. The subject of the invention is a process for the preparation of the polymer composition according to the first object, characterized in that it comprises at least one step i) of mixing a thermoplastic polymer material based on polypropylene with a dielectric liquid such as as defined in the first subject of the invention.
    In particular, the mixture is carried out according to the following sub-steps: ia) optionally the mixture of a compound of formula (I) as defined in the first subject of the invention with the additive (s) as defined in the first object of the invention, and ib) the mixture of a thermoplastic polymer material based on polypropylene as defined in the first subject of the invention with at least one compound of formula (I) or with the mixture as obtained in the previous substep ia) if substep ia) exists.
    The thermoplastic polypropylene-based material of sub-step ia) is generally in the form of granules of polymer (s), in particular granules of at least one homopolymer or copolymer of propylene Pi and at least one homopolymer or an olefin copolymer P2 as defined in the first subject of the invention.
    The mixture of the sub-step ia) can be carried out using any apparatus making it possible to dissolve the additive (s) as defined in the first subject of the invention (in particular when they are in the form of solid powders), at least in the compound of formula (I) of the dielectric liquid.
    Sub-step ia) is preferably carried out at a temperature of from about 20 to 100 ° C, preferably from about 50 to 90 ° C, and more preferably at a temperature of about 70 ° C.
    Sub-step ia) generally lasts 15 minutes to 1 hour, and preferably 20 to 30 minutes. At the end of the sub-step ia), a stable and transparent solution is obtained.
    The mixture of the sub-step ib) can be carried out by mixing the mixture obtained in the sub-step ia) with the polypropylene thermoplastic polymer material or the polymeric compounds which constitute it, in particular by means of a mixer internal, in particular tangential rotors or intermeshing rotors, or a continuous mixer, in particular screw or counter rotating double screw or a mixer type "Buss extruder".
    During the sub-step ib), the polymer composition of the invention can be shaped, especially in the form of granules.
    To do this, the temperature within the mixer is chosen to be sufficient to obtain the thermoplastic polymer material in the molten state. Then, the homogeneous mixture can be granulated, by techniques well known to those skilled in the art. These granules can then feed an extruder to manufacture the cable of the invention according to a method as defined below. The third object of the invention is a cable comprising at least one elongated electrically conductive element, and at least one electrically insulating layer obtained from a polymer composition as defined in the first subject of the invention.
    The electrically insulating layer of the invention is a non-crosslinked layer.
    The electrically insulating layer of the invention is preferably a recyclable layer.
    The electrically insulating layer of the invention may be an extruded layer, especially by methods well known to those skilled in the art.
    In the present invention, the term "electrically insulating layer" means a layer whose electrical conductivity can be at most 1.10 9 S / m, and preferably at most 1.10 10 S / m (Siemens per meter) ( at 25 ° C).
    The cable of the invention relates more particularly to the field of electric cables operating in direct current (DC) or alternating current (AC).
    The electrically insulating layer of the invention may surround the elongated electrically conductive element. The elongate electrically conductive element may be a single-body conductor such as, for example, a wire or a multi-body conductor such as a plurality of twisted or non-twisted metal wires. The elongated electrically conductive member may be aluminum, aluminum alloy, copper, copper alloy, and one of their combinations.
    According to a preferred embodiment of the invention, the electric cable may comprise: a first semiconductor layer surrounding the elongated electrically conductive element; an electrically insulating layer surrounding the first semiconductor layer, said electrically insulating layer being such defined in the invention, and a second semiconductor layer surrounding the electrically insulating layer.
    In the present invention, the term "semiconductor layer" means a layer whose electrical conductivity can be at least 1.10 -9 S / m (Siemens per meter), preferably at least 1.10 -3 S / m. and preferably may be less than 1.103 S / m (at 25 ° C).
    In a particular embodiment, the first semiconductor layer, the electrically insulating layer and the second semiconductor layer constitute a three-layer insulation. In other words, the electrically insulating layer is in direct physical contact with the first semiconductor layer, and the second semiconductor layer is in direct physical contact with the electrically insulating layer.
    The cable may further comprise an electrically insulating sheath surrounding the second semiconductor layer, and may be in direct physical contact therewith.
    The electrical cable may further comprise a metal screen surrounding the second semiconductor layer. In this case, the electrically insulating sheath surrounds said metal screen.
    This metal screen may be a "wired" screen composed of a set of copper or aluminum conductors arranged around and along the second semiconductor layer, a so-called "ribbon" screen composed of one or more ribbons conductive metallic copper or aluminum placed (s) optionally helically around the second semiconductor layer or a conductive metal strip of aluminum laid longitudinally around the second semiconductor layer and sealed with glue in the zones overlapping parts of said ribbon, or a so-called "sealed" screen of metal tube type optionally composed of lead or lead alloy and surrounding the second semiconductor layer. This last type of screen makes it possible in particular to provide a moisture barrier that tends to penetrate the electrical cable radially. The metal screen of the electric cable of the invention may comprise a so-called "wired" screen and a so-called "waterproof" screen or a so-called "wired" screen and a "ribbon" screen.
    All types of metal screens can play the role of grounding the electric cable and can thus carry fault currents, for example in the event of a short circuit in the network concerned. Other layers, such as swelling layers in the presence of moisture can be added between the second semiconductor layer and the metal screen, these layers to ensure longitudinal sealing of the electric cable to water. The fourth subject of the invention is a method of manufacturing an electric cable according to the third subject of the invention, characterized in that it comprises at least one step 1) of extruding the polymer composition according to the first object of the invention around an elongated electrically conductive member to provide an electrically insulating (extruded) layer surrounding said elongate electrically conductive member. Step 1) can be carried out by techniques well known to those skilled in the art, for example using an extruder.
    In step 1), the extruder output composition is said to be "non-crosslinked", the temperature as well as the processing time within the extruder being optimized accordingly.
    At the extruder outlet, an extruded layer is thus obtained around said electrically conductive element, which may or may not be directly in physical contact with said elongated electrically conductive element.
    The method does not preferably include a step of crosslinking the layer obtained in step 1).
    Figure 1 shows a schematic view of an electric cable according to a preferred embodiment according to the invention.
    For the sake of clarity, only the essential elements for understanding the invention have been shown schematically, and this without respect of the scale.
    The medium or high voltage power cable 1, illustrated in FIG. 1, comprises an elongated central electrically conductive element 2, in particular made of copper or aluminum. The energy cable 1 further comprises several layers arranged successively and coaxially around this central elongated electrically conductive element 2, namely: a first semiconductor layer 3 called "internal semiconductor layer", an electrically insulating layer 4, a second semiconductor layer 5 called an "outer semi-conducting layer", a metal screen 6 for grounding and / or protection, and an outer protective sheath 7.
    The electrically insulating layer 4 is a non-crosslinked extruded layer obtained from the polymer composition according to the invention.
    The semiconductor layers 3 and 5 are extruded thermoplastic layers (ie non-crosslinked).
    The presence of the metal screen 6 and the outer protective sheath 7 is preferred, but not essential, this cable structure being as such well known to those skilled in the art.
    EXAMPLES 1. Polymer Compositions
    Table 1 below gathers polymer compositions whose amounts of the compounds are expressed in percentages by weight relative to the total weight of the polymer composition.
    The composition C1 is a comparative composition, and the composition It is in accordance with the invention.
    TABLE 1 The origin of the compounds of Table 1 is the following: - random propylene copolymer marketed by Borealis under the reference Bormed RB 845 MO; linear low density polyethylene marketed by Exxon Mobil Chemicals under the reference LLDPE LL 1002 YB; heterophasic copolymer sold by the company Basell Polyolefins under the reference Adflex Q 200F; dielectric liquid consisting of 1,2,3,4-tetrahydro- (1-phenylethyl) naphthalene marketed by Dow under the reference Dowtherm RP; and - antioxidant marketed by Ciba under the reference Irganox B 225 which comprises an equimolar mixture of Irgafos 168 and Irganox 1010. 2. Preparation of non-crosslinked layers
    The compositions summarized in Table 1 are implemented as follows. 130 g of dielectric liquid and 5 g of antioxidant were mixed in a glass vessel with stirring.
    The resultant mixture was then mixed with 850 g of propylene copolymer, 425 g of linear low density polyethylene and 425 g of heterophasic copolymer in a vessel, and the resulting polymer composition was extruded using an extruder. double screw ("Berstorff twin screw extruder") at a temperature of about 200 ° C.
    A comparative layer not according to the invention was prepared as described above but only from the mixture of polymers and oxidant. 3. Characterization of uncrosslinked layers
    The resistance to stress whitening was evaluated manually by bending two layers as prepared above respectively from the compositions Cl and II.
    The dielectric strength of the layers was measured using a device comprising two stainless steel semispherical electrodes with a diameter of about 20 mm (one electrode under voltage and the other at ground) and a dielectric oil marketed by the company. Bluestar Silicones under the reference Rhodorsil 604 V 50. By definition, the dielectric strength is the ratio between the breakdown voltage and the thickness of the insulation. The breakdown voltage was measured at about 24 ° C., with a humidity of about 50%, using the stepwise voltage rise method. The applied voltage was an alternating voltage of about 50 Hz frequency and the voltage rise rate was about 1 kV / s until breakdown. 12 measurements were made for each non-crosslinked layer.
    The tangent delta (tan5) (or loss factor) of the layers as prepared above was measured by dielectric spectroscopy using a device sold under the trade name Alpha-A by the company Novocontrol Technologies.
    The tangent of the loss angle gives an indication of the energy dissipated in a dielectric in the form of heat.
    The tests were carried out on layers of thickness close to 0.5 mm at 90 ° C., at a frequency of 40 to 60 Hz with a voltage of 500 V adapted according to the thickness of the sample tested in order to apply a electric field of 1 kV / mm. 4. Results
    The layer obtained from composition II showed no whitening, whereas the layer obtained from the comparative composition Cl was not very resistant since a white mark at the level of the curvature appeared immediately under the manual stress applied. .
    The results of dielectric strength and loss factor are shown in Table 2 below:
    TABLE 2
    Therefore, the polymeric compositions according to the invention exhibit improved properties of resistance to stress whitening while guaranteeing good dielectric properties.
    权利要求:
    Claims (19)
    [1" id="c-fr-0001]
    A polymer composition comprising at least one polypropylene thermoplastic polymer material and a dielectric liquid, characterized in that the dielectric liquid comprises at least one compound corresponding to the following formula (I):

    (I) wherein R1 and R2, same or different, are unsubstituted aryl groups and the element A represents a single bond or an alkylene group.
    [2" id="c-fr-0002]
    2. Composition according to claim 1, characterized in that the aryl group comprises from 5 to 20 carbon atoms.
    [3" id="c-fr-0003]
    3. Composition according to claim 1 or 2, characterized in that each of the aryl groups is not substituted by one or more alkyl groups of formula CtH2t + i.
    [4" id="c-fr-0004]
    4. Composition according to any one of the preceding claims, characterized in that the element A is an alkylene group having 1 to 10 carbon atoms.
    [5" id="c-fr-0005]
    5. Composition according to claim 4, characterized in that the alkylene group is a - (CH2) n- group with 1 <n <10; a group - (CHR) n - with 1 <n <10 and R being an alkyl group; a - (CHR) P- (CH 2) m- group, with 1 <p + m <10, and R being an alkyl group; or a - (CHR) p1- (CH2) m- (CHR ') p2- statistical group, with 1 <pi + m + p2 <10, and R and R' being different alkyl groups.
    [6" id="c-fr-0006]
    6. Composition according to any one of the preceding claims, characterized in that at least one of said groups R1 or R2 of the compound of formula (I) is a phenyl group.
    [7" id="c-fr-0007]
    7. Composition according to any one of the preceding claims, characterized in that the compound of formula (I) is diphenylethane, diphenylmethane or 1,2,3,4-tetrahydro- (1-phenylethyl) naphthalene.
    [8" id="c-fr-0008]
    8. Composition according to any one of the preceding claims, characterized in that the dielectric liquid comprises at least 50% by weight of at least one compound of formula (I), relative to the total mass of the dielectric liquid.
    [9" id="c-fr-0009]
    9. Composition according to any one of the preceding claims, characterized in that the ratio of the number of aromatic carbon atoms to the total number of carbon atoms in the dielectric liquid is greater than or equal to 0.6.
    [10" id="c-fr-0010]
    10. Composition according to any one of the preceding claims, characterized in that the dielectric liquid is from 1% to 20% by weight, relative to the total weight of the polymer composition.
    [11" id="c-fr-0011]
    11. Composition according to any one of the preceding claims, characterized in that the thermoplastic polymer material based on polypropylene comprises at least one propylene homopolymer or copolymer Pi, and at least one homopolymer or copolymer of olefin P2.
    [12" id="c-fr-0012]
    12. Composition according to claim 11, characterized in that the propylene copolymer Pi is a copolymer of propylene and ethylene.
    [13" id="c-fr-0013]
    13. Composition according to claim 11 or 12, characterized in that the propylene homopolymer or copolymer Pi represents from 40 to 70% by weight of the thermoplastic polymer material based on polypropylene.
    [14" id="c-fr-0014]
    14. Composition according to any one of claims 11 to 13, characterized in that the olefin homopolymer or copolymer P2 is a heterophase copolymer comprising a propylene-type thermoplastic phase and a copolymer-type thermoplastic elastomer phase. ethylene and an olefin, a polyethylene or a mixture thereof.
    [15" id="c-fr-0015]
    15. Composition according to any one of claims 11 to 14, characterized in that the olefin homopolymer or copolymer P2 represents from 30 to 60% by weight of the thermoplastic polymer material.
    [16" id="c-fr-0016]
    16. Process for the preparation of the polymer composition as defined in any one of claims 1 to 15, characterized in that it comprises at least one step i) of mixing a polypropylene thermoplastic polymer material with a dielectric liquid as defined in any one of claims 1 to 15.
    [17" id="c-fr-0017]
    17. Cable comprising at least one elongated electrically conductive element, and at least one electrically insulating layer obtained from a polymer composition as defined in any one of claims 1 to 15.
    [18" id="c-fr-0018]
    18. Cable according to claim 17, characterized in that the electrically insulating layer is a non-crosslinked layer.
    [19" id="c-fr-0019]
    19. A method of manufacturing an electric cable as defined in claim 17 or 18, characterized in that it comprises at least one step 1) of extruding the polymer composition as defined in any one of the claims. 1 to 15 around an elongate electrically conductive member to provide an electrically insulating layer surrounding said elongated electrically conductive member.
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    KR20180097648A|2018-08-31|
    CL2018001617A1|2018-09-07|
    AU2016373306B2|2021-04-01|
    CA3008528A1|2017-06-22|
    WO2017103511A1|2017-06-22|
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    FR2111059A5|1970-10-06|1972-06-02|Kimberly Clark Co|Polypropylene compsns - contg maleic anhydride and an aromatic cpd with a tertiary benzzylic hydrogen-atom easily extendabl|
    JP2003160705A|2001-11-28|2003-06-06|Suzuhiro Kagaku:Kk|Flame-retardant polypropylene composition|
    WO2010023236A1|2008-08-29|2010-03-04|Akzo Nobel N.V.|Flame retardant polyolefin composition|
    US4543207A|1982-12-25|1985-09-24|Nippon Petrochemicals Company, Limited|Electrical insulating oil and oil-filled electrical appliances|
    WO2004066317A1|2003-01-20|2004-08-05|Gabriele Perego|Cable with recycable covering layer|
    US20060100466A1|2004-11-08|2006-05-11|Holmes Steven A|Cycloalkane base oils, cycloalkane-base dielectric liquids made using cycloalkane base oils, and methods of making same|
    CA2788403C|2010-01-29|2017-08-08|Prysmian S.P.A.|Energy cable|
    WO2012069864A1|2010-11-25|2012-05-31|Prysmian S.P.A.|Energy cable having a voltage stabilized thermoplastic electrically insulating layer|EA202091173A1|2017-12-18|2020-11-12|Бореалис Аг|COMPOSITION OF A MIXTURE OF POLYMERS FOR APPLICATION IN THE FIELD OF WIRES AND CABLES WITH ADVANCED ELECTRICAL PROPERTIES|
    FR3079067B1|2018-03-19|2020-03-20|Nexans|ELECTRIC CABLE COMPRISING AN EASILY PEELABLE POLYMERIC LAYER|
    KR20200105196A|2019-02-28|2020-09-07|엘지전자 주식회사|Control method for refrigerator|
    法律状态:
    2016-12-22| PLFP| Fee payment|Year of fee payment: 2 |
    2017-06-23| PLSC| Publication of the preliminary search report|Effective date: 20170623 |
    2017-12-21| PLFP| Fee payment|Year of fee payment: 3 |
    2019-12-19| PLFP| Fee payment|Year of fee payment: 5 |
    2020-12-23| PLFP| Fee payment|Year of fee payment: 6 |
    2021-12-24| PLFP| Fee payment|Year of fee payment: 7 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1562790|2015-12-18|
    FR1562790A|FR3045635B1|2015-12-18|2015-12-18|POLYMERIC COMPOSITION HAVING ENHANCED BLEACH RESISTANCE WITH IMPROVED BRAIN|FR1562790A| FR3045635B1|2015-12-18|2015-12-18|POLYMERIC COMPOSITION HAVING ENHANCED BLEACH RESISTANCE WITH IMPROVED BRAIN|
    KR1020187020341A| KR20180097648A|2015-12-18|2016-12-15|A polymer composition having improved stress whitening resistance|
    CN201680082644.7A| CN108699305A|2015-12-18|2016-12-15|Polymer composition with higher stress-whitening resistance|
    AU2016373306A| AU2016373306B2|2015-12-18|2016-12-15|Polymer composition having greater resistance to stress whitening|
    BR112018012239-4A| BR112018012239A2|2015-12-18|2016-12-15|polymer composition with improved stress whitening resistance|
    CA3008528A| CA3008528A1|2015-12-18|2016-12-15|Polymer composition having greater resistance to stress whitening|
    PCT/FR2016/053480| WO2017103511A1|2015-12-18|2016-12-15|Polymer composition having greater resistance to stress whitening|
    EP16825526.3A| EP3390529A1|2015-12-18|2016-12-15|Polymer composition having greater resistance to stress whitening|
    US16/062,416| US20200277477A1|2015-12-18|2016-12-15|Polymer composition with improved stress whitening resistance|
    CL2018001617A| CL2018001617A1|2015-12-18|2018-06-15|Polymeric composition with improved resistance to stress whitening|
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