EP3662487A1 - Method for the production of an electrical cable by extrusion of a composition comprising a propylene polymer and a dielectric liquid - Google Patents
Method for the production of an electrical cable by extrusion of a composition comprising a propylene polymer and a dielectric liquidInfo
- Publication number
- EP3662487A1 EP3662487A1 EP18752609.0A EP18752609A EP3662487A1 EP 3662487 A1 EP3662487 A1 EP 3662487A1 EP 18752609 A EP18752609 A EP 18752609A EP 3662487 A1 EP3662487 A1 EP 3662487A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- composition
- zone
- screw
- extruder
- propylene
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
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- 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
- H01B13/147—Feeding of the insulating material
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/06—Polyethene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/10—Homopolymers or copolymers of propene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/10—Homopolymers or copolymers of propene
- C08L23/12—Polypropene
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- 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
-
- 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
- H01B3/20—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils
-
- 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
- H01B3/20—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils
- H01B3/22—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils hydrocarbons
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
- H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
- H01B3/441—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from alkenes
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2203/00—Applications
- C08L2203/20—Applications use in electrical or conductive gadgets
- C08L2203/202—Applications use in electrical or conductive gadgets use in electrical wires or wirecoating
Definitions
- the invention relates to a method for manufacturing an electrical cable, in particular of the energy cable type, comprising an extruded thermoplastic layer obtained from a composition comprising at least one dielectric liquid and at least one thermoplastic polymer chosen from a homopolymer and a propylene copolymer, as well as a cable obtained by said process.
- a medium or high voltage power transmission cable generally includes from the inside to the outside:
- an elongated electrically conductive element in particular made of copper or aluminum; an inner semiconductor layer surrounding said elongated electrically conductive element;
- the electrically insulating layer may be a polymer layer based on a crosslinked polyolefin such as a crosslinked polyethylene (XLPE) or a crosslinked elastomer of ethylene-propylene or ethylene-propylene-diene.
- Crosslinking is usually carried out during the step of extruding the polymer composition around the elongated electrically conductive member.
- XLPE crosslinked polyethylene
- the use of a crosslinked polyolefin makes it possible to provide a layer having satisfactory electrical and mechanical properties and to lead to a cable that can operate at a temperature greater than 70 ° C., or even equal to 90 ° C.
- crosslinked materials can not be recycled.
- the crosslinking process limits the speed of manufacture of the cables comprising an insulating layer based on XLPE. Indeed, to obtain a satisfactory degree of crosslinking, it is necessary that the polymer can be brought to the required temperature to obtain its crosslinking for a sufficiently long period. Thus, the production speed of the cables comprising an insulating layer based on XLPE must be adjusted so that the passage time in the crosslinking tunnel is long enough to obtain a satisfactory degree of crosslinking, which represents a binding limit. not negligible in terms of production capacity.
- the crosslinking reactions must never take place during the extrusion of the polyethylene material so as to avoid any risk of XLPE particles forming in the extruder (screw, collar, head of the extruder ), which could then migrate into the insulating layer or in the semiconductor layer of the cable and create defects therein.
- XLPE particles affects the final properties of the cable insofar as these particles generate a lack of homogeneity, mainly of the material of the insulating layer or at the interface between the insulating layer and the semilimic layers. conductive. This phenomenon is known by the English name "scorch phenomena" for roasting phenomenon.
- LDPE-based materials for cable insulation layers can be an alternative to using XLPE-based materials.
- the LDPE-based materials have the disadvantage that they can not be used at temperatures above 70 ° C, which also has the effect of reducing their ability to transport energy so as to avoid overheating.
- the insulating layer at temperatures above 70 ° C.
- the manufacture of this type of electrically insulating layer is very complex and expensive (tape or composite application step and impregnation step).
- energy cables comprising at least one extruded thermoplastic electrically insulating layer based on a composition comprising a polypropylene matrix intimately mixed with a dielectric liquid have been proposed as for example in the international application WO 02/03398.
- the dielectric liquid may represent from 3 to 15% by weight relative to the total mass of the composition.
- it is necessary to develop a process that allows the homogeneous and intimate mixing of the polypropylene matrix with the dielectric liquid while ensuring that this mixture is easy to extrude.
- the presence of the dielectric liquid may allow an improvement in the electrical performance of said cables, especially in terms of dielectric strength, it can also cause problems during the extrusion process for their industrial manufacture.
- the presence of the dielectric liquid can cause irregularities in the movement and plasticization of the polypropylene matrix along the extruder sheath.
- quantities less than 15% by weight of dielectric liquid relative to the total mass of the composition eg about 3-10%
- a sliding phenomenon at the wall related to the lubricating effect of dielectric liquid appears, which can lead to degradation of the mechanical and / or electrical properties of the layer thermoplastic obtained at the extruder head (structural defects of the layer).
- the international application WO 2005/042226 has described an extrusion process comprising the following steps: a first step in which a thermoplastic polymer based on propylene in the solid form is introduced into a feed zone of an extruder, a second step in which the thermoplastic polymer is brought from the feed zone to at least one intermediate zone allowing the gradual melting of the thermoplastic polymer, then a step of injecting a dielectric liquid in a zone of the extruder adjacent to the extruder head and wherein the thermoplastic polymer is in the molten state.
- This method has the disadvantage of injecting the dielectric liquid, which is a flammable liquid, at high pressures (approximately 30-1500 bars) and in an area close to the extruder head, which leads to major safety and security problems. degradations of the injection apparatus and / or the extruder.
- the object of the present invention is to overcome the drawbacks of the prior art and to provide a method for manufacturing an electric cable, in particular of the energy cable type, comprising at least one elongated electrically conductive element and at least one an extruded thermoplastic layer surrounding said elongate electrically conductive member, said layer being obtained from a composition comprising at least one dielectric liquid and at least one thermoplastic polymer based on a propylene homo- or copolymer, said method being simple, economical, not requiring the implementation of a complex and expensive security device, and may lead to a thermoplastic electrically insulating layer having good electrical and mechanical properties, at least comparable to those obtained with a crosslinked layer XLPE.
- the invention firstly relates to a method of manufacturing a cable electrical cable, in particular of the energy cable type, comprising at least one elongated electrically conductive element and at least one extruded thermoplastic layer surrounding said elongated electrically conductive element, said method implementing a device comprising at least one extruder containing a sleeve, a screw and an extruder head, characterized in that it comprises at least the following steps:
- thermoplastic polymer in solid form chosen from a homopolymer of propylene and a copolymer of propylene
- dielectric liquid representing an amount of less than about 15% by weight, relative to the total mass of the composition
- feeding zone a first zone of the screw, called feeding zone, and located at the entrance of the extruder
- step ii) a step during which the composition resulting from step i) is brought from the feed zone to one or more intermediate zones of the screw allowing the composition to be transported to the extruder head situated at the exiting the extruder and gradually melting the thermoplastic polymer, and
- sheath is a grooved sheath and / or the screw is a barrier-type screw (i.e. barrier screw).
- the method of the invention is simple and economical, it makes it possible to avoid any safety problem related to the injection of a dielectric liquid at high pressure and any sliding problem with a wall, while guaranteeing a homogeneous and intimate mixture of the polymer.
- thermoplastic and dielectric liquid An extruder conventionally comprises a sleeve (or cylinder) in which rotates one or more screws driven in rotation, in particular by a motor-drive. The screw or screws extend along the longitudinal axis of the extruder, and are rotated about their longitudinal axis.
- a specific sheath ie grooved sheath
- a specific screw ie barrier screw
- the extruder used in the process of the invention makes it possible to implement steps i), ii) and iii). In particular, it makes it possible to convey the composition of step i), to disperse it or to homogenize it, to put it under pressure, to melt the thermoplastic polymer, and to form a thermoplastic layer, in particular of the electrically insulating layer type, around at least one elongated electrically conductive element.
- ambient temperature means a temperature ranging from about 15 to about 30 ° C, and preferably ranging from about 20 to about 25 ° C.
- the extruder implementing the method of the invention is a single screw extruder. It therefore includes a single screw.
- the propylene copolymer of the composition of step i) can be a heterophasic copolymer of propylene, a random copolymer of propylene or a mixture thereof.
- the heterophasic propylene copolymer generally comprises a propylene-type thermoplastic phase and an elastomeric copolymer-type phase of ethylene and a 1- olefin.
- the elastomeric 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 1 of the elastomeric phase of the heterophase copolymer may be propylene.
- the propylene random copolymer can be a copolymer of propylene and of olefin, the olefin being especially chosen from ethylene and a olefin a 2 different from propylene.
- the olefin a 2 is preferably at most about 15 mole% and more preferably at most about 10 mole% of the copolymer.
- a copolymer of propylene and ethylene is preferred as the propylene random copolymer.
- propylene random copolymer marketed by Borealis under the reference Bormed® RB 845 MO is particularly preferred.
- the random copolymers of propylene that can be used according to the invention preferably have an elastic modulus ranging from 600 to 1200 MPa approximately.
- the propylene homopolymers which can be used according to the invention preferably have an elastic modulus ranging from approximately 1250 to 1600 MPa.
- the homopolymer (respectively the propylene random copolymer) may have a melting temperature greater than about 130 ° C, preferably greater than about 140 ° C, and more preferably from about 140 to 165 ° C.
- the homopolymer (respectively the propylene random copolymer) may have a melting enthalpy ranging from about 30 to 100 J / g.
- the homopolymer (respectively the propylene random copolymer) may have a melt index ranging from 0.5 to 3 g / 10 min, measured at about 230 ° C. with a load of approximately 2.16 kg according to the ASTM D1238 standard. -00.
- the composition of step i) may further comprise a polyethylene in solid form.
- Said dielectric liquid represents an amount of less than 15% by weight, relative to the total mass of the composition of step i).
- the polyethylene is preferably a high density polyethylene or a linear low density polyethylene.
- a so-called "high density” polyethylene or HDPE according to the standard ISO 1183A has a density ranging from about 0.930 to 0.970 g / cm 3 , and even more preferentially from 0.940 to 0.965 g / cm 3. about.
- a so-called "low density” linear polyethylene or LLDPE according to ISO 1183A has a density ranging from about 0.91 to about 0.925 g / cm 3 .
- the propylene homopolymer may represent from about 40% to about 90% by weight, and preferably from about 40% to about 70% by weight, based on the total weight of the composition of step i).
- the random copolymer of propylene may represent from 40% to 90% by weight approximately, and preferably from 40 to 70% by weight approximately, relative to the total mass of the composition of step i).
- the heterophasic propylene copolymer may represent from 5% to 60% by weight, and preferably from 5% to 50% by weight, relative to the total mass of the composition of stage i).
- the polyethylene may represent from about 20% to about 60% by weight, and preferably from about 20% to about 50% by weight, based on the total weight of the composition of step i).
- the composition includes as polymers:
- a propylene random copolymer eg of about 50-70% by weight, based on the total weight of the composition
- a heterophasic copolymer of propylene eg of about 5-30% by weight, based on the total weight of the composition
- a linear low density polyethylene eg about 20-40% by weight, based on the total mass of the composition
- heterophasic copolymer of propylene eg of 35-55% by weight approximately, relative to the total mass of the composition
- high density polyethylene eg of 35-55% by weight approximately, relative to the total mass of the composition
- thermoplastic layer in particular of the electrically insulating layer type, having good mechanical properties, especially in terms of elastic modulus, and electrical properties.
- the polymers of the composition being in solid form, they can be in the form of pellets or granules.
- composition of step i) 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, flame retardants, dyes, anti-copper agents, anti-tree water agents and one of their mixtures.
- the composition may typically comprise from about 0.01 to about 5 weight percent, and preferably from about 0.1 to about 2 weight percent of additives, based on the total weight of the composition of step i).
- the antioxidants make it possible to protect the 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-type antioxidants and a mixture thereof.
- hindered phenols examples include the pentaérythritoltétrakis (3- (3,5-di-i "eri” -butyl-4-hydroxyphenyl) propionate)
- thioesters examples include the didodecyl-3,3'-thiodipropionate (Irganox ® PS800) ledistéarylthiodipropionate (Irganox® PS802) and 4,6-bis (octylthiométhyle) -o-cresol (Irganox ® 1520 ).
- sulfur-based antioxidants examples include dioctadecyl-3,3'-thiodipropionate and didodecyl-3,3'-thiodipropionate.
- antioxidants phosphorus-based there may be mentioned tris (2,4-di-teri - butyl-phenyl) phosphite (Irgafos ® 168) and bis (2,4-di-teri " - butylphenyl) pentaerythritoliphosphite (Ultranox ® 626).
- amine antioxidants examples include phenylene diamines (eg 1PPD or 6PPD), diphenylamine styrene, diphenylamines, mercaptobenzimidazoles and polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ).
- mixtures of antioxidants include Irganox B 225 which comprises an equimolar mixture of Irgafos 168 and Irganox 1010 as described above.
- the dielectric liquid may represent from 3 to 10% by weight, preferably from 4 to 8% by weight, and more preferably from 5 to About 7% by weight, based on the total mass of the composition.
- the pressure may be at most 5 bar, preferably at most 3 bar, and preferably at most 1.5 bar. In a particularly preferred embodiment, the pressure in step i) is approximately equal to atmospheric pressure, namely approximately equal to 1 bar.
- Step i) makes it possible to introduce the composition into the extruder.
- the feed zone or first zone of the screw is located at the entrance of the extruder.
- the composition comprising the thermoplastic polymer in solid form and the dielectric liquid is introduced into the feed zone of the screw, in particular in order to pass into the space located between the inner surface of the sheath and the outer surface of the screw.
- the dielectric liquid is introduced at the same time as the thermoplastic polymer in solid form into the feed zone, through the hopper of the extruder.
- the extruder preferably comprises a single zone for introducing the composition along its longitudinal axis, this introduction zone being located in the feed zone or first zone of the screw.
- a barrier screw or barrier profile screw has at least one zone designated "barrier zone".
- the barrier zone comprises in particular a secondary net with a slightly greater pitch (gradually sweeping the width of the channel) which separates the molten polymer from the still solid polymer, as if it materialized the boundary between the two phases.
- the height of this net is less than that of the main net to allow the molten polymer to change channels, but remains large enough to prevent the solid polymer (e.g., pellets) from crossing this gap.
- the barrier screw may have a nominal diameter D ranging from approximately 45 to 200 mm.
- the barrier screw has an L / D ratio varying from approximately 20 to 26, where L is the length of the screw in mm and D is the nominal diameter of the screw in mm.
- the diameter of the body of the barrier screw preferably increases from the rear or the entrance of the extruder (ie feed zone of the screw) towards the front or the exit of the extruder (extruder head ), either over the entire length of the screw or on only parts of the screw.
- the first zone or feed zone of the screw has a length varying from 1D to approximately 3D.
- the screw pitch in the feed zone can be about D / 2.
- the thickness of the net in the feed zone may be about D / 10.
- the diameter of the body of the screw in the feed zone is constant.
- the depth of the screw channel in the feed zone (at the inlet and outlet of the feed zone) ranges from about D / 20 to about D / 10.
- grooved sheath means a sheath comprising at least one grooved portion, or in other words a portion having grooves.
- the grooved portion of the sheath is preferably in the feed zone of the screw.
- the composition is introduced directly into a first zone of the feed zone called the introduction zone, and the composition is then fed from the zone d introduction to a second zone of the feed zone towards the extruder head.
- the grooved portion of the sleeve is then more particularly in the second zone of the feed zone.
- the grooved sheath preferably comprises 4 to 10 heating zones and 4 to 10 cooling zones, and more preferably 5 to 7 heating zones and 5 to 7 cooling zones.
- the grooved sheath may have an internal diameter varying from approximately 45 to 200 mm.
- the grooves may be straight (in the axis of the extruder) or helical.
- the grooves may be rectangular, conical (triangular) or circular, and preferably triangular conical.
- the grooves may have a length ranging from about 1.5D to 2.5D.
- the grooves may have a width varying from 1 to 4 mm approximately.
- the grooves preferably have a depth varying from about 0.2 to 3 mm.
- the grooves have an angle of 45 °, 60 °, 90 ° or 120 °, and preferably 90 °
- the angle of the grooves may in particular be defined by the helix angle of a spiral groove, measured from the plane perpendicular to the longitudinal axis of the sheath. More particularly, parallel grooves with the longitudinal axis of the sheath have an angle of 90 °.
- the grooved sheath may comprise from 6 to 24 grooves, and preferably from 14 to 22 grooves.
- the grooves of the sheath preferably extend longitudinally in the direction from the feed zone to the extruder head.
- the sheath can have a length ranging from about 20 to about 26D.
- Step i) can be performed by means of a feed hopper.
- the device then further comprises a feed hopper.
- the hopper comprising the composition of step i) opens on the sleeve at the entrance of the screw, and more particularly on the first zone of the feed zone.
- Step iO During step ii), the composition resulting from step i) is extruded. It is fed (continuously) from the feed zone to one or more intermediate zones of the screw allowing the composition to be transported to the extruder head at the outlet of the extruder and the gradual melting of the polymer thermoplastic.
- the intermediate zones may comprise one or more heating zones, making it possible to control the temperature in the extruder.
- the molten state (melting) is achieved when the thermoplastic polymer, optionally mixed with other polymers, is heated to a temperature greater than or equal to its melting temperature.
- the temperature during step ii) can vary from about 60 to 200 ° C.
- the pressure during step iii) can vary from 1 to 300 bar.
- the intermediate zones are located between the feed zone and the extruder head.
- the screw of the extruder can be divided into four zones, the first zone being the feed zone as defined above, the second, third and fourth zones being the one or more intermediate zones allowing the composition to be transported to the head. of the extruder at the exit of the extruder and the gradual melting of the thermoplastic polymer.
- the extruder comprises at least one barrier zone as defined above.
- at least one of the intermediate zones is a barrier zone.
- the second zone of the screw is a compression zone.
- the compression zone preferably has a length varying from about 4D to 8D.
- the screw pitch in the compression zone can be about 1D.
- the thickness of the net in the compression zone may vary from D / 10 to D / 15 approx.
- the diameter of the body of the screw in the compression zone is not constant. In particular, it increases from the rear or entrance of the screw towards the front or exit of the screw (i.e. in the direction of the feeding zone towards the extruder head).
- the depth of the screw channel in the compression zone (at the inlet and the outlet of the compression zone) varies from D / 20 to D / 10 approximately.
- the third zone is a barrier zone.
- the barrier zone preferably has a length varying from about 4D to about 10D.
- the screw pitch in the barrier zone can vary from D / 2 to about 1.5D.
- the thickness of the net in the barrier zone can vary from D / 10 to D / 15 approximately.
- the diameter of the body of the screw in the barrier zone is not constant. In particular, it increases from the back or the entrance of the screw towards the front or the exit of the screw (i.e. in the direction of the feeding zone towards the extruder head).
- the channel depth of the screw in the barrier zone (at the entrance and exit of the barrier zone and for the main channel and the secondary channel) ranges from D / 20 to D / 10. about.
- the fourth zone is a pumping zone.
- the pumping zone preferably has a length varying from about 2D to about 6D.
- the screw pitch in the pumping zone can be about 1D.
- the thickness of the net in the pumping zone can vary from D / 10 to D / 15 approximately.
- the diameter of the body of the screw in the pumping zone is constant.
- the depth of the screw channel in the pumping zone (at the inlet and the outlet of the pumping zone) varies from D / 20 to D / 10 approximately.
- the compression ratio varies from 1.2 to about 1.6, the compression ratio being defined as the ratio of the depth of the rear channel of the screw (ie at the inlet of the extruder or in the feeding zone of the screw) on the depth of the front channel of the screw (ie at the exit of the extruder or in the pumping zone of the screw).
- step iii) the composition comprising the melt thermoplastic polymer and the dielectric liquid is pressurized through a die to be applied around the elongate electrically conductive member.
- the method may further comprise, before step i), a step i 0 ) of bringing into contact, in particular at ambient temperature, the thermoplastic polymer in solid form chosen from a propylene homopolymer and a propylene copolymer, with the dielectric liquid to form the composition of step i) (ie a composition comprising the thermoplastic polymer and the dielectric liquid, said dielectric liquid being less than 15% by mass, based on the total mass of the composition).
- the pressure may be at most 5 bar, preferably at most 3 bar, and preferably at most 1.5 bar. In a particularly preferred embodiment, the pressure during step i 0 ) is approximately equal to the atmospheric pressure, namely approximately equal to 1 bar.
- Step i 0 can be carried out directly in a feed hopper as defined in the invention or in a mixer, in particular located upstream of the feed hopper, the mixer being preferably a static mixer.
- thermoplastic polymer and the dielectric liquid may be introduced separately, or as a mixture, into the feed hopper.
- step i 0 may comprise any one of the following S 01 or S 02 sequences:
- the device further comprises a mixer, in particular located upstream of the feed hopper, the mixer being preferably a static mixer.
- thermoplastic polymer and the dielectric liquid can be introduced separately into the mixer, and then the resulting composition can be transferred to the feed hopper.
- This embodiment makes it possible to improve the homogeneity of the composition comprising the thermoplastic polymer in solid form and the dielectric liquid.
- Step i 0 may then comprise any one of the following sequences S '01 or S' 02 : S '01 : feed the mixer with the thermoplastic polymer in solid form, then inject the dielectric liquid in the mixer comprising the thermoplastic polymer, or
- step S '01 or step S' 02 being followed by a step of transferring the resulting composition into the feed hopper.
- step i 0 implements contacting, especially at temperature.
- Step i 0 is preferably not a step of impregnating the thermoplastic polymer with the dielectric liquid.
- the dielectric liquid is not absorbed completely by the thermoplastic polymer during step i 0 ).
- a conventional impregnation step is long and requires a minimum amount of dielectric liquid (about 10-15% relative to the total mass of the composition).
- the method may further comprise a step iv) of cooling the cable obtained at the end of step iii) (ie at the exit of the extruder).
- the cooling can be carried out with water, in particular with one or more cooling tanks fed continuously with water, in particular in order to maintain a constant temperature of the cooling tanks.
- the method may further comprise a step v) of drying the cable obtained at the end of step iv). Drying removes water from the surface of the cable.
- the process of the invention is preferably a continuous process.
- the method of the invention does not preferably include a step of homogenizing the composition when the thermoplastic polymer is in the molten state.
- the extruder does not comprise a mixer, and in particular does not include a static mixer, allowing such homogenization, especially in one of the intermediate zones as defined above.
- the thermoplastic layer, in particular of the electrically insulating layer type, of the cable obtained according to the method of the invention has a variable thickness depending on the type of cable envisaged.
- the thickness of the insulating layer is typically about 4 to 5 mm, and more particularly about 4.5 mm.
- the thickness of the insulating layer typically varies from 17 to 18 mm (for voltages of the order of about 150 kV) and to go up to thicknesses ranging from 20 to 25 mm approximately for voltages higher than 150 kV (very high voltage cables).
- 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 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.
- the electrically insulating layer of the cable is uncrosslinked.
- the electrically insulating layer is preferably a recyclable layer.
- the electric cable may comprise:
- first semiconductor layer surrounding the elongated electrically conductive member; - an electrically insulating layer surrounding the first semiconductor layer, said electrically insulating layer being as defined in the invention, and
- 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 1.10 3 S / m (at 25 ° C).
- the first semiconductor layer, the electrically insulating layer and the second semiconductor layer constitute a three-layer insulation.
- the electrically insulating layer is in direct physical contact with the first semiconductor layer
- the second semiconductor layer is in direct physical contact with the electrically insulating layer.
- the first and second semiconductor layers are preferably a thermoplastic polymeric material.
- the cable may further comprise an electrically insulating sheath surrounding the second semiconductor layer, and may be in direct physical contact therewith.
- the cable may further comprise a metal screen surrounding the second semiconductor layer.
- 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 metal made of copper or aluminum laid optionally helically around the second semiconducting layer or a conductive aluminum metal strip laid longitudinally around the second semiconductor layer and sealed by glue in areas of overlapping portions of said ribbon, or a so-called “sealed” type screen metal tube 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.
- the second object of the invention is an electrical cable, in particular of the energy cable type, comprising at least one elongate electrically conductive element and at least one extruded thermoplastic layer surrounding said elongated electrically conductive element, characterized in that it is capable of be obtained according to a manufacturing method according to the first subject of the invention.
- thermoplastic layer in particular of the electrically insulating layer type, is obtained by extrusion of a composition comprising at least one thermoplastic polymer chosen from a propylene homopolymer and a propylene copolymer, and a dielectric liquid, said dielectric liquid representing a quantity less than 15% by weight, relative to the total mass of said composition.
- thermoplastic polymer as defined in the first subject of the invention.
- FIGS. 1 and 2 are non-limiting and schematically represent a device implementing the method according to the invention (FIG. 1) and an electric cable according to the invention (FIG. 2). .
- the device 1 comprises a container 2 that can be fed with granules of a thermoplastic polymer chosen from a homo- and a propylene copolymer, a container 3 that can be fed with a dielectric liquid, a feed hopper 4 being able to be fed at ambient temperature by the granules of the thermoplastic polymer contained in the container 2 and by the dielectric liquid contained in the container 3, and an extruder 5 comprising a grooved sheath 6 and / or a barrier screw 7, as well as a extruder head 8.
- a container 2 that can be fed with granules of a thermoplastic polymer chosen from a homo- and a propylene copolymer
- a container 3 that can be fed with a dielectric liquid
- a feed hopper 4 being able to be fed at ambient temperature by the granules of the thermoplastic polymer contained in the container 2 and by the dielectric liquid contained in the container 3
- an extruder 5 comprising a grooved sheath 6
- the composition comprising the granules of the thermoplastic polymer and the dielectric liquid is introduced via the feed hopper 4 into a feed zone 9 of the screw according to step i), then brought according to step ii) from the feed zone 9 to one or more intermediate zones 10 allowing the transport of the composition to the head of the extruder 8 located at the outlet of the extruder 5 and the gradual melting of the thermoplastic polymer, said intermediate zones 10 being located between the feed zone 9 and the extruder head 8. Finally, at the level of the extruder head 8, the composition is applied around an elongated electrically conductive element according to step iii).
- the medium or high voltage energy cable 11 obtained according to the method of the invention comprises a central elongated electrically conductive element 12, in particular made of copper or aluminum, and, successively and coaxially, comprises around this element 12, a first semiconductor layer 13 called “internal semiconductor layer”, an electrically insulating layer 14, a second semiconductor layer 15 called “outer semiconductor layer”, a metal screen 16 of the cylindrical tube type, and an outer protective sheath 17, the electrically insulating layer 14 being obtained from a composition comprising at least one thermoplastic polymer chosen from a propylene homopolymer and a propylene copolymer, and a dielectric liquid according to an extrusion process such as as defined in the invention.
- Layers 13 and 15 are extruded layers by methods well known to those skilled in the art.
- the presence of the metal screen 16 and the outer protective sheath 17 is preferred, but not essential.
- This cable structure is as such of known type and outside the scope of the present invention.
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1757384A FR3069799B1 (en) | 2017-08-01 | 2017-08-01 | METHOD OF MANUFACTURING AN ELECTRIC CABLE BY EXTRUSION OF A COMPOSITION BASED ON A POLYMER OF PROPYLENE AND A DIELECTRIC LIQUID |
PCT/FR2018/051964 WO2019025718A1 (en) | 2017-08-01 | 2018-07-31 | Method for the production of an electrical cable by extrusion of a composition comprising a propylene polymer and a dielectric liquid |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3662487A1 true EP3662487A1 (en) | 2020-06-10 |
Family
ID=60888471
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP18752609.0A Pending EP3662487A1 (en) | 2017-08-01 | 2018-07-31 | Method for the production of an electrical cable by extrusion of a composition comprising a propylene polymer and a dielectric liquid |
Country Status (8)
Country | Link |
---|---|
US (1) | US20210118595A1 (en) |
EP (1) | EP3662487A1 (en) |
KR (1) | KR102373770B1 (en) |
CN (1) | CN111052264B (en) |
BR (1) | BR112020001846A2 (en) |
CL (1) | CL2020000256A1 (en) |
FR (1) | FR3069799B1 (en) |
WO (1) | WO2019025718A1 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
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KR100445040B1 (en) * | 2000-10-12 | 2004-08-18 | 주식회사 한썸 | Temperature control for cooling apparatus of communication facilities |
FR3125354A1 (en) * | 2021-07-19 | 2023-01-20 | Nexans | Method for manufacturing an electric cable by extruding a composition based on a propylene polymer and a dielectric liquid with a barrier screw comprising a mixing section |
FR3135913A1 (en) * | 2022-05-31 | 2023-12-01 | Nexans | Process for manufacturing an electric cable by extrusion of a composition based on a thermoplastic polymer, dielectric liquid and homogeneously distributed nanofillers |
FR3138627A1 (en) * | 2022-08-08 | 2024-02-09 | Nexans | Extruder for extruding an electrically insulating layer comprising a sheath having a liquid injection channel |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4564349A (en) * | 1983-06-01 | 1986-01-14 | Union Carbide Corporation | Extruder assembly for extruding water-curable silane modified polymers |
JPH0550486A (en) * | 1991-08-21 | 1993-03-02 | Furukawa Electric Co Ltd:The | Multistage thermoplastic resin extruder |
WO2002003398A1 (en) | 2000-06-28 | 2002-01-10 | Pirelli Cavi E Sistemi Spa | Cable with recyclable covering |
US7744950B2 (en) * | 2000-12-06 | 2010-06-29 | Prysmian Cavi E Sistemi Energia S.R.L. | Process for producing a cable with a recyclable coating comprising a thermoplastic polymer and a dielectric liquid |
BR0115863B1 (en) * | 2000-12-06 | 2011-10-18 | process for producing a cable provided with at least one thermoplastic sheath. | |
KR101003441B1 (en) * | 2003-10-31 | 2010-12-28 | 프리즈미안 카비 에 시스테미 에너지아 에스 알 엘 | Method and plant for the introduction of a liquid into a molten mass under pressure |
DK2850619T3 (en) * | 2012-05-18 | 2019-10-14 | Prysmian Spa | Method of manufacturing a power cable with a thermoplastic electrically insulating layer |
US10297372B2 (en) * | 2012-05-18 | 2019-05-21 | Prysmian S.P.A | Process for producing an energy cable having a thermoplastic electrically insulating layer |
CN204172318U (en) * | 2014-10-29 | 2015-02-25 | 佛山市日丰企业有限公司 | A kind of polyolefin extrusion screw rod |
-
2017
- 2017-08-01 FR FR1757384A patent/FR3069799B1/en active Active
-
2018
- 2018-07-31 WO PCT/FR2018/051964 patent/WO2019025718A1/en unknown
- 2018-07-31 EP EP18752609.0A patent/EP3662487A1/en active Pending
- 2018-07-31 CN CN201880056837.4A patent/CN111052264B/en active Active
- 2018-07-31 BR BR112020001846-5A patent/BR112020001846A2/en unknown
- 2018-07-31 US US16/635,071 patent/US20210118595A1/en active Pending
- 2018-07-31 KR KR1020207003500A patent/KR102373770B1/en active IP Right Grant
-
2020
- 2020-01-30 CL CL2020000256A patent/CL2020000256A1/en unknown
Also Published As
Publication number | Publication date |
---|---|
BR112020001846A2 (en) | 2020-07-28 |
WO2019025718A1 (en) | 2019-02-07 |
KR20200028414A (en) | 2020-03-16 |
FR3069799A1 (en) | 2019-02-08 |
KR102373770B1 (en) | 2022-03-15 |
CN111052264B (en) | 2021-09-21 |
CN111052264A (en) | 2020-04-21 |
US20210118595A1 (en) | 2021-04-22 |
FR3069799B1 (en) | 2020-09-18 |
CL2020000256A1 (en) | 2020-07-03 |
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