WO2020157254A1 - Composition de polyoléfine comprenant des nanoplaquettes de graphène ayant une conductivité électrique invariante - Google Patents

Composition de polyoléfine comprenant des nanoplaquettes de graphène ayant une conductivité électrique invariante Download PDF

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WO2020157254A1
WO2020157254A1 PCT/EP2020/052388 EP2020052388W WO2020157254A1 WO 2020157254 A1 WO2020157254 A1 WO 2020157254A1 EP 2020052388 W EP2020052388 W EP 2020052388W WO 2020157254 A1 WO2020157254 A1 WO 2020157254A1
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polyolefin composition
graphene nanoplatelets
electrical conductivity
base resin
olefin polymer
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PCT/EP2020/052388
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English (en)
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Thomas Gkourmpis
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Borealis Ag
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C08K3/042—Graphene or derivatives, e.g. graphene oxides
    • 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
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/002—Physical properties
    • C08K2201/003—Additives being defined by their diameter
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/002—Physical properties
    • C08K2201/006—Additives being defined by their surface area
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/016—Additives defined by their aspect ratio

Definitions

  • the present invention relates to a polyolefin composition comprising graphene nanoplatelets. It also relates to the use of the polyolefin composition in a power cable. Further, the invention is also related to an article, preferably a cable joint, a layer of a power cable, a pipe or an automotive part, comprising said polyolefin composition.
  • carbonaceous structures in various materials, such as polymers, can lead to a mechanical reinforcement of the material but at the same time also induces electrical conductivity.
  • CNTs carbon nanotubes
  • GNPs graphene nanoplatelets
  • Electrically conductive polymer nanocomposites have been disclosed using single or multi-layers graphene nanoplatelets as in WO 2008/045778A1 and WO 2008/143692A1.
  • WO 03/024602 A1 discloses separated graphite nanostructures formed of thin graphite platelets having an aspect ratio of at least 1500: 1.
  • the graphite nanostructures are created from synthetic or natural graphite using a high- pressure mill.
  • the resulting graphite nanostructures can be added to polymeric materials to create polymer composites having increased mechanical characteristics, including an increased flexural modulus, heat deflection temperature, tensile strength, electrical conductivity, and notched impact strength.
  • the effects observed in this disclosure require filler loadings, if added to polypropylene, as high as 38 wt.% or 53 wt.%.
  • WO 2013/033603 A1 discloses a field grading material which is an insulation material used in electrical installation.
  • the composite material comprises a polymer material and reduced graphene oxide distributed within the polymer material.
  • the reduced graphene oxide supplies non-linear resistivity to the composite material.
  • the present invention therefore provides a polyolefin composition
  • a polyolefin composition comprising
  • the invention further provides an article comprising the polyolefin composition.
  • the present invention also provides the use of the polyolefin composition according to the invention in a layer of a power cable.
  • the present invention has several surprising advantages.
  • the invention provides a plastomer-based system, i.e. a system based on an olefin polymer base resin, comprising graphene nanoplatelets as fillers which surprisingly exhibits an almost invariant electrical conductivity and no electrical percolation threshold even at high filler content or loading.
  • the electrical conductivity of the polyolefin composition is similar to that of the pure olefin polymer base resin and at the same time a reinforcement of the polyolefin composition is surprisingly achieved.
  • the electrical percolation threshold (also termed the “percolation point”) is defined as the critical (minimum) concentration in wt.% of the graphene nanoplatelets (b) (b) in the olefin polymer base resin (a) where an exponential increase in electrical conductivity is observed. In other words, it indicates the minimum loading of the graphene nanoplatelets (b) in wt.%, at which the filler loading is such that an adequate network capable of facilitating current flow is created, which is followed by a sharp increase in the observed conductivity value.
  • the percolation threshold indicates the efficiency of the network formation, i.e. the degree of dispersion. Thus, low percolation threshold indicates that the dispersion of the graphene nanoplatelets (b) is good.
  • Percolation is a mathematical concept that describes the connectivity of random clusters.
  • Percolation threshold describes the onset of long-range connectivity in random systems. Below the threshold, long range connectivity does not exist while above the threshold, long range connectivity begins to materialize. Traditionally, a large and sharp change on the measured property that results from the long range connectivity is observed in the vicinity of the percolation threshold.
  • the “long range connectivity” equals the electrical conductivity. The electrical conductivity increases in the vicinity of the threshold by (at least) 2-3 orders of magnitude. This phenomenon is discussed in detail by Thomas Gkourmpis, Innovation and Technology, Borealis AB, Stenungsund SE in“Controlling the Morphology of Polymers” by Geoffrey R. Mitchell and Ana Tojeira (Eds.), incorporated herein by reference.
  • “filler loading” or“filler content” in the context of the present description refers to the added amount of the graphene nanoplatelets (b) in weight percent in relation to the weight of the total polyolefin composition.
  • the graphene nanoplatelets (b) can thus also be labelled as“filler(s)”.
  • the graphene nanoplatelets (b) according to the invention are characterized in that the material is composed of one or several layers of two-dimensional hexagonal lattice of carbon atoms.
  • the platelets have a length parallel to the graphite plane, hereafter labeled diameter, and a thickness orthogonal to the graphite plane, hereafter labeled thickness.
  • Another characteristic feature of GNPs is that the platelets are very thin yet have large diameter, hence GNPs have a very large aspect ratio, i.e. the ratio between the diameter and the thickness.
  • the thickness of the graphene nanoplatelets (b) is in the range of from 1 nm to 100 nm, more preferably 1 nm to 50 nm, more preferably of from 1 nm to 40 nm, and most preferably of from 1 nm to 20 nm.
  • the graphene nanoplatelets (b) comprise, more preferably consist of, single graphene sheets.
  • the thickness of a single graphene sheet is about 1 nm. The thickness is measured with atomic force microscope (AFM) as described in detail e.g. by Stankovich et al, Nature 442
  • the diameter of the graphene nanoplatelets (b) can also be measured by the aforementioned AFM method.
  • the diameter of the graphene nanoplatelets (b) is preferably 200 mm or less, more preferably 50 mm or less, or most preferably 10 mm or less.
  • the diameter of the graphene nanoplatelets (b) is at least 0.5 mm.
  • the graphene nanoplatelets (b) have an aspect ratio, which is defined as the ratio of their diameter to their thickness.
  • the aspect ratio of the graphene nanoplatelets (b) is 50 or more, more preferably 500 or more, and most preferably 1000 or more.
  • the aspect ratio is not more than 5000.
  • Graphene nanoplatelets may also include graphene platelets that are somewhat wrinkled such as for example described in Stankovich et al, Nature 442, (2006), pp. 282. Additionally, graphene materials with wrinkles to another essentially flat geometry are included. Also more complex secondary structures such as cones are also included, see for example Schniepp, Journal of Physical Chemistry B, 1 10 (2006), pp. 8535. The definition of GNP does not include carbon nanotubes.
  • the graphene nanoplatelets can be functionalised to improve interaction with the olefin polymer base resins.
  • Non-limiting examples of surface modifications includes treatment with nitric acid; O 2 plasma; UV/Ozone; amine; acrylamine such as disclosed in US2004/127621 A1 .
  • the graphene nanoplatelets (b) can exhibit a high density.
  • the graphene nanoplatelets (b) have a density of 500 to 4000 g/L, more preferably of 1000 to 3000 g/L, more preferably of 1500 to 2500 g/L, and most preferably 2000 to 2400 g/L when measured using ASTM D7481-09.
  • the graphene nanoplatelets (b) preferably have BET (Brunauer, Emmett and Teller, ASTM D6556) surface areas of 40 to 2500 m 2 /g, more preferably of 60 to 500 m 2 /g, more preferably of 80 to 250 m 2 /g, more preferably of 100 to 250 m 2 /g and most preferably of 120 to 160 m 2 /g, measured according to ASTM D6556.
  • the graphene nanoplatelets (b) can have a BET surface area up to 2500 m 2 /g for materials with a large fraction of single graphene sheets.
  • the graphene nanoplatelets (b) preferably have a volatile content, as measured by thermogravimetric analysis (TGA) from 125°C to 1000°C under inert gas, of lower than 15%, more preferably lower than 10%, more preferably lower than 5%, more preferably lower than 2.5%, and most preferably of lower than 1 %.
  • TGA thermogravimetric analysis
  • the volatile content is higher than 0.01 %.
  • the added amount of said graphene nanoplatelets (b) is in the range of from 0.5 to 30 wt.%, more preferably 1 to 25 wt.%, more preferably 2 to 20 wt.%, and most preferably 2 to 15 wt.%, based on the total weight of the polyolefin composition.
  • the second electrical conductivity of the polyolefin composition is lower than, the same or a factor of less than 3 higher as the first electrical conductivity of the olefin polymer base resin (a).
  • the second electrical conductivity of the polyolefin composition is lower than or the same as the first electrical conductivity of the olefin polymer base resin (a), and most preferably the second electrical conductivity of the polyolefin composition is lower than the first electrical conductivity of the olefin polymer base resin (a).
  • the second electrical conductivity of the polyolefin composition is lower than the first electrical conductivity of the olefin polymer base resin (a).
  • the second electrical conductivity of the polyolefin composition is preferably a factor of at least 2, more preferably a factor of at least 3, more preferably a factor of at least 5, and most preferably a factor of at least 10 lower than the first electrical conductivity of the olefin polymer base resin (a).
  • the second electrical conductivity of the polyolefin composition is at most a factor of 50 lower, preferably a factor of at most 20 lower, than the first electrical conductivity of the olefin polymer base resin (a).
  • the second electrical conductivity of the polyolefin composition is preferably the same as the first electrical conductivity of the olefin polymer base resin (a).
  • the second electrical conductivity of the polyolefin composition is a factor of less than 3, preferably a factor of less than 2.5, and most preferably a factor of less than 2.2, higher than the first electrical conductivity of the olefin polymer base resin (a).
  • the electrical conductivity is measured as described below.
  • polyolefin or “olefin polymer” encompasses both an olefin homopolymer and a copolymer of an olefin with one or more comonomer(s).
  • “comonomer” refers to copolymerisable monomer units.
  • copolymer refers to a polymer made from at least two monomers. It includes, for example, copolymers, terpolymers and tetrapolymers.
  • the olefin polymer base resin (a) is selected from the group consisting of a C2 to C8 olefin homo- or copolymer.
  • the olefin polymer base resin (a) is an olefin homopolymer or copolymer which contains one or more comonomer(s), more preferable an ethylene homo- or copolymer or a propylene homo- or copolymer, and most preferably a polyethylene, which can be made in a low pressure process or a high pressure process.
  • the olefin polymer base resin (a) is a copolymer of ethylene with at least one comonomer selected from unsaturated esters or a heterophasic propylene copolymer.
  • the olefin polymer base resin (a) can e.g. be a commercially available polymer or can be prepared according to or analogously to known polymerization process described in the chemical literature.
  • the olefin polymer base resin (a), preferably polyethylene is produced in a low pressure process, it is typically produced by a coordination catalyst, preferably selected from a Ziegler-Natta catalyst, a single site catalyst, which comprises a metallocene and/or non-metallocene catalyst, and/or a Cr catalyst, or any mixture thereof.
  • the polyethylene produced in a low pressure process can have any density, e.g. be a very low density linear polyethylene (VLDPE), a linear low density polyethylene (LLDPE) copolymer of ethylene with one or more comonomer(s), medium density polyethylene (MDPE) or high density polyethylene (HDPE).
  • the olefin polymer base resin (a) can be unimodal or multimodal with respect to one or more of molecular weight distribution, comonomer distribution or density distribution.
  • Low pressure polyethylene may be multimodal with respect to molecular weight distribution.
  • Such a multimodal olefin polymer base resin (a) may have at least two polymer components which have different weight average molecular weight, preferably a lower weight average molecular weight (LMW) and a higher weight average molecular weight (HMW).
  • LMW lower weight average molecular weight
  • HMW weight average molecular weight
  • a unimodal olefin polymer base resin (a), preferably low pressure polyethylene is typically prepared using a single stage polymerization, e.g. solution, slurry or gas phase polymerization, in a manner well-known in the art.
  • a multimodal (e.g. bimodal) olefin polymer base resin (a), for example a low pressure polyethylene can be produced by mechanically blending two or more, separately prepared polymer components or by in-situ blending in a multistage polymerization process during the preparation process of the polymer components. Both mechanical and in-situ blending is well-known in the field.
  • a multistage polymerization process may preferably be carried out in a series of reactors, such as a loop reactor, which may be a slurry reactor and/or one or more gas phase reactor(s). Preferably, a loop reactor and at least one gas phase reactor is used. The polymerization may also be preceded by a pre polymerization step.
  • a LDPE homopolymer or an LDPE copolymer of ethylene with one or more comonomers may be produced.
  • the LDPE homopolymer or copolymer may be unsaturated.
  • ethylene (co)polymers by high pressure radical polymerization reference can be made to the Encyclopedia of Polymer Science and Engineering, Vol. 6 (1986), pp 383- 410 and Encyclopedia of Materials: Science and Technology, 2001 Elsevier Science Ltd.: “Polyethylene: High-pressure, R.KIimesch, D.Littmann and F.-O. Mahling pp. 7181 -7184.
  • Olefin polymer base resin (a) may include, but is not limited to, copolymers of ethylene and unsaturated ester with an ester content of up to 50 wt.%, based on the weight of the copolymer.
  • unsaturated esters are vinyl esters, acrylic acid and methacrylic acid esters, typically produced by conventional high pressure processes.
  • the ester can have from 3 to about 20 carbon atoms, preferably 4 to 10 atoms.
  • Non-limiting examples of vinyl esters are: vinyl acetate, vinyl butyrate, and vinyl pivalate.
  • Non-limiting examples of acrylic and methacrylic acid esters are: methyl acrylate, ethyl acrylate, t-butyl acrylate, n-butyl acrylate, isopropyl acrylate, hexyl acrylate, decyl acrylate and lauryl acrylate.
  • the olefin polymer base resin (a) may be plastomeric ethylene/a-olefin copolymers having an a-olefin content of from 15 wt.%, preferably from 25 wt.%, based on the weight of the copolymer. These copolymers typically have an a-olefin content of 50 wt.% or less, preferably 40 wt.% or less and most preferably 35 wt.% or less, based on the weight of the copolymer.
  • the a-olefin content is measured by 13 C nuclear magnetic resonance (NMR) spectroscopy as described by Randall (Re. Macromolecular Chem. Phys. C29 (2&3)).
  • the a-olefin is preferably a C3-20 linear, branched or cyclic a-olefin.
  • C3-20 a-olefins include propene, 1 -butene, 4-methyl-1 -pentene, 1 - hexene, 1 -octene, 1 -decene, 1 -dodecene, 1 -tetradecene, 1 -hexadecene and 1 - octadecene.
  • the a-olefins can also contain a cyclic structure, such as cyclohexane or cyclopentane, resulting in an a-olefin such as 3-cyclohexyl-1 - propene and vinyl cyclohexane.
  • a-olefins in the classical sense of the term, for the purpose of this invention certain cyclic olefins such as norbornene and related olefins, particularly 5-ethylidene-2-norbornene, are encompassed by the term “a-olefins” and can be used as described above.
  • styrene and its related olefins e.g.
  • a-methylstyrene are a-olefins for the purpose of this invention.
  • Illustrative examples of copolymers in the sense of the present invention include ethylene/propylene, ethylene/butene, ethylene/1 - hexene, ethylene/1 -octene, ethylene/styrene and similar.
  • Illustrative examples of terpolymers include ethylene/propylene/1 -octene, ethylene/butene/1 -octene, ethylene/propylene/diene monomer (EPDM) and ethylene/butene/styrene.
  • the copolymer can be random or blocky.
  • the olefin polymer base resin (a) is preferably a plastomer.
  • the olefin polymer base resin (a) is an ethylene homo-or copolymer.
  • the ethylene copolymer is preferably an ethylene-octene copolymer, more preferably an LLDPE ethylene-octene copolymer.
  • Copolymerization can be carried out in the presence of one or more further comonomers which are copolymerizable with the two monomers mentioned above and which, for example, may be selected from vinylcarboxylate esters such as vinyl acetate and vinyl pivalate; (meth)acrylates such as methyl(meth)- acrylate, ethyl(meth)acrylate and butyl(meth)acrylate; (meth)acrylic acid derivatives such as (meth)acrylonitrile and (meth)acrylamide; vinyl ethers, such as vinylmethyl ether and vinylphenyl ether; a-olefins such as propylene, 1 - butene, 1 -hexene, 1 -octene and 4-methyl-1 -pentene; olefinically unsaturated carboxylic acids, such as (meth)acrylic acid, maleic acid and fumaric acid; and aromatic vinyl compounds, such as styrene and alpha-methyl sty
  • Preferred comonomers are vinyl ethers of monocarboxylic acids having 1 -4 carbon atoms, such as vinyl acetate and (meth)acrylate of alcohols having 1 -8 carbon atoms, such as methyl(meth)acrylate.
  • the expression ’’(meth)acrylic acid” used herein is intended to include both acrylic acid and methacrylic acid.
  • the comonomer content in the polymer may be present in the amount of 40 wt.% or less, preferably 0.5-35 wt.%, more preferably 1 -25 wt.%.
  • olefin polymerbase resin (a) are: polypropylene, e.g. homopolypropylene, propylene copolymer; polybutene, butene copolymers; highly short chain branched a-olefins copolymers with an ethylene co-monomer content of 50 mole percent or less; polyisoprene; EPR (ethylene copolymerized with propylene); EPDM (ethylene copolymerized with propylene and a diene such as hexadiene, dicyclopentadiene, or ethylidene norbornene); copolymers of ethylene and an a-olefin having 3 to 20 carbon atoms such as ethylene/octene copolymers; terpolymers of ethylene, a-olefin and a diene; terpolymers of ethylene, a-olefin and an unsaturated ester; copolymers of ethylene, ethylene,
  • the olefin polymer may comprise ethylene ethyl acrylate.
  • the comonomers can be incorporated randomly or in block and/or graft structures.
  • the olefin polymer base resin (a) preferably comprises or consists of a heterophasic olefin copolymer, e.g. a heterophasic propylene copolymer.
  • the heterophasic propylene copolymer may preferably be a heterophasic copolymer comprising a propylene random copolymer as matrix phase (RAHECO) or a heterophasic copolymer having a propylene homopolymer as matrix phase (HECO).
  • a random copolymer is a copolymer where the comonomer part is randomly distributed in the polymer chains and it also consists of alternating sequences of two monomeric units of random length (including single molecules). It is preferred that the random propylene copolymer comprises at least one comonomer selected from the group consisting of ethylene and C4-C8 alpha-olefins.
  • Preferred C4-C8 a-olefins are 1 -butene, 1 -pentene, 4-methyl-1 - pentene, 1 -hexene, 1 -heptene or 1 -octene, more preferred 1 -butene.
  • a particularly preferred random propylene copolymer may comprise or consist of propylene and ethylene.
  • the comonomer content of the polypropylene matrix preferably is 0.5 to 10 wt.%, more preferably 1 to 8 wt.% and even more preferably 2 to 7 wt.%.
  • the incorporation of the comonomer can be controlled in such a way that one component of the polypropylene contains more comonomer than the other.
  • Suitable polypropylenes are described e.g. in WO 03/002652.
  • the olefin polymer base resin (a) is an ethylene-a-olefin, preferably a plastomer, having a density in the range of 860 to 915 kg/m 3 , preferably 890 to 905 kg/m 3 , more preferably 860 to 900 kg/m 3 , and an MFR2 (190°C/2.16kg) measured according to ISO 1 133 in the range of 0.5 to 50.0 g/10min, more preferably in the range of 1 .0 to 25 g/10min, most preferably 1.0 to 10 g/10min.
  • G’ is the storage modulus and is measured in accordance with ISO 6721 -1 and 6721 -10. It is used as a measure of the mechanical reinforcement of the polyolefin compositions of the invention.
  • improvement of the storage modulus G’ can be achieved.
  • the polyolefin composition has a G’ of at least 400 Pa measured according to ISO 6721 -1 and 6721 -10 at an amount of 0.5 wt.% or more of graphene nanoplatelets (b) based on the amount of the total polyolefin composition, more preferably of at least 450 Pa.
  • the polyolefin composition has a G’ of at least 550 Pa measured according to ISO 6721 -1 and 6721 -10 at an amount of 5 wt.% or more of graphene nanoplatelets (b) based on the amount of the total polyolefin composition, more preferably of at least 650 Pa.
  • the polyolefin composition has a G’ of at least 1000 Pa measured according to ISO 6721 -1 and 6721 -10 at an amount of 10 wt.% or more of graphene nanoplatelets (b) based on the amount of the total polyolefin composition, more preferably of at least 1050 Pa.
  • the polyolefin composition has a G’ of at least 1700 Pa measured according to ISO 6721 -1 and 6721 -10 at an amount of 15 wt.% or more of graphene nanoplatelets (b) based on the amount of the total polyolefin composition, more preferably of at least 1800 Pa.
  • the storage modulus G’ of the polyolefin composition of the invention is not more than 5000 Pa at amounts of 0.5 to 30 wt.%, of graphene nanoplatelets (b), based on the amount of the total polyolefin composition.
  • the polyolefin compositions may be crosslinkable. “Crosslinkable” means that when the polyolefin composition is used in cable applications, the cable layer can be crosslinked before the use in the end application thereof. In crosslinking reaction of a polymer, interpolymer crosslinks (bridges) are primarily formed.
  • Crosslinking can be initiated by free radical reaction using irradiation or preferably using a crosslinking agent, which is typically a free radical generating agent, or by the incorporation of crosslinkable groups into polymer component(s), as known in the art. Moreover, in cable applications, the crosslinking step of the polyolefin composition is typically carried out after the formation of the cable.
  • the crosslinking agent is a peroxide, whereby the crosslinking is preferably initiated using a well-known peroxide crosslinking technology that is based on free radical crosslinking and is well described in the field.
  • the peroxide can be any suitable peroxide conventionally used in the field.
  • Crosslinking may also be achieved by incorporation of crosslinkable groups, preferably hydrolysable silane groups, into the polymer component(s) of the polyolefin composition.
  • the hydrolysable silane groups may be introduced into the polymer by copolymerisation of e.g. ethylene monomers with silane group containing comonomers or by grafting with silane groups containing compounds, i.e. by chemical modification of the polymer by addition of silane groups mostly in a free radical grafting process.
  • silane groups containing comonomers and compounds are well-known in the field and are commercially available.
  • the hydrolysable silane groups are typically then crosslinked by hydrolysis and subsequent condensation in the presence of a silanol-condensation catalyst and water trace in a manner known in the art. Also, silane crosslinking technique is well-known in the art.
  • the crosslinkable polyolefin composition layer comprises crosslinking agent(s), preferably free radical generating agent(s), more preferably peroxide.
  • crosslinking of at least the insulation layer, and optionally, and preferably, of the at least one semiconductive layer is preferably carried out by free radical reaction using one or more free radical generating agents, preferably peroxide(s).
  • the crosslinking agent is preferably used in an amount of less than 10 wt.%, more preferably in an amount of between 0.05 to 8 wt.%, still more preferably in an amount of 0.2 to 3 wt.% and even more preferably in an amount of 0.3 to 2.5 wt.% with respect to the total weight of the composition to be crosslinked.
  • peroxidic crosslinking agents are organic peroxides, such as di-tert-amylperoxide, 2,5-di(tert-butylperoxy)-2,5-dimethyl-3-hexyne, 2,5-di(tert-butylperoxy)-2,5-dimethylhexane, tert-butylcumylperoxide, di (tert- butyl)peroxide, dicumylperoxide, butyl-4, 4-bis(tert-butylperoxy)-valerate, 1 , 1 - bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butylperoxybenzoate, dibenzoylperoxide, bis (tert butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5- di(benzoylperoxy)hexane, 1 , 1 -di(tert-
  • the peroxide is selected from 2,5-di(tert-butylperoxy)-2,5-dimethylhexane, di(tert- butylperoxyisopropyl)benzene, dicumylperoxide, tert-butylcumylperoxide, di(tert-butyl)peroxide, or mixtures thereof.
  • the polyolefin composition comprises further additive(s), such as antioxidant(s), stabiliser(s), water tree retardant additive(s), processing aid(s), scorch retarder(s), filler(s), metal deactivator(s), free radical generating agent(s), crosslinking booster(s), flame retardant additive(s), acid or ion scavenger(s), additional inorganic filler(s), voltage stabilizer(s) or any mixtures thereof.
  • additives such as antioxidant(s), stabiliser(s), water tree retardant additive(s), processing aid(s), scorch retarder(s), filler(s), metal deactivator(s), free radical generating agent(s), crosslinking booster(s), flame retardant additive(s), acid or ion scavenger(s), additional inorganic filler(s), voltage stabilizer(s) or any mixtures thereof.
  • Additives are typical use in total amount from 0.01 wt.% to 10 wt.% based on the total polyolefin composition.
  • Non-limiting examples of antioxidants are sterically hindered or semi-hindered phenols, aromatic amines, aliphatic sterically hindered amines, organic phosphites or phosphonites, thio compounds, and mixtures thereof.
  • the antioxidant is selected from the group of diphenyl amines and diphenyl sulfides.
  • the phenyl substituents of these compounds may be substituted with further groups such as alkyl, alkylaryl, arylalkyl or hydroxy groups.
  • the phenyl groups of diphenyl amines and diphenyl sulfides are substituted with tert-butyl groups, preferably in meta or para position, which may bear further substituents such as phenyl groups.
  • the antioxidant is selected from the group of 4,4'- bis(1 , 1'dimethylbenzyl)diphenylamine, para-oriented styrenated diphenylamines, 6,6'-di-tert-butyl-2,2'-thiodi-p-cresol, tris(2-tert-butyl-4-thio-(2'- methyl-4'hydroxy-5'-tert-butyl)phenyl-5-methyl)phenylphosphite, polymerized 2,2,4-trimethyl-1 ,2-dihydroquinoline, or derivatives thereof.
  • the antioxidants may be used but also any mixture thereof.
  • the amount of an antioxidant is preferably from 0.005 to 2.5 wt.%, based on the weight of the total polyolefin composition, more preferably from 0.005 to 2 wt.%, still more preferably from 0.01 to 1.5 wt.%, and even more preferably from 0.04 to 1.2 wt.%, based on the weight of the total polyolefin composition.
  • the scorch retarder is a well-known additive type in the field and can i.e. prevent premature crosslinking. As also known the SR may also contribute to the unsaturation level of the polymer composition.
  • scorch retarders are allyl compounds, such as dimers of aromatic alpha-methyl alkenyl monomers, preferably 2,4-di-phenyl-4-methyl-1 -pentene, substituted or unsubstituted diphenylethylenes, quinone derivatives, hydroquinone derivatives, monofunctional vinyl containing esters and ethers, monocyclic hydrocarbons having at least two or more double bonds, or mixtures thereof.
  • the amount of a scorch retarder is within the range of 0.005 to 2.0 wt.%, more preferably within the range of 0.005 to 1.5 wt.%, based on the weight of the total polyolefin composition. Further preferred ranges are e.g. from 0.01 to 0.8 wt.%, 0.03 to 0.75 wt.%, 0.03 to 0.70 wt.%, or 0.04 to 0.60 wt.%, based on the weight of the total polyolefin composition.
  • One preferred SR added to the polyolefin composition is 2,4-diphenyl-4-methyl-1 -pentene.
  • processing aids include but are not limited to metal salts of carboxylic acids such as zinc stearate or calcium stearate; fatty acids; fatty amids; polyethylene wax; copolymers of ethylene oxide and propylene oxide; petroleum waxes; non-ionic surfactants and polysiloxanes.
  • Non-limiting examples of additional fillers are clays precipitated silica and silicates; fumed silica calcium carbonate.
  • compounding embraces mixing of the material according to standard methods to those skilled in the art.
  • Non-limiting examples of compounding equipments are continuous single or twin screw mixers such as FarellTM, Werner and PfleidererTM , Kobelco BollingTM and BussTM, or internal batch mixers, such as BrabenderTM or BanburyTM.
  • any suitable process known in the art may be used for the preparation of the polyolefin compositions of the present invention such as dry-mixing, solution mixing, solution shear mixing, melt mixing, extrusion, etc. It is however preferred to prepare the polyolefin composition by melt-mixing said olefin polymer base resin (a) with graphene nanoplatelets (b) in an extruder, such as a Brabender compounder. Preferably, the polyolefin composition is obtained by melt-mixing the olefin polymer base resin (a) with the graphene nanoplatelets (b).
  • the present invention also provides a polyolefin composition obtained by melt mixing the olefin polymer base resin (a) with graphene nanoplatelets (b).
  • melt-mixing is performed in an extruder.
  • the temperature for melt- mixing mainly depends on the type of olefin polymer base resin (a) employed.
  • melt-mixing is carried out at a temperature in the range of 125 °C to 230 °C, more preferably 135 °C to 220 °C.
  • polyolefin compositions described above are also preferred embodiments of the polyolefin composition obtained by melt-mixing the olefin polymer base resin (a) with graphene nanoplatelets (b).
  • the polyolefin composition obtained by melt-mixing the olefin polymer base resin (a) with graphene nanoplatelets (b) has preferably a second electrical conductivity, wherein said second electrical conductivity of said polyolefin composition is lower than, the same, or a factor of less than 3 higher as said first electrical conductivity of said olefin polymer base resin (a).
  • the present invention further provides an article comprising the polyolefin composition according to the invention. All embodiments of the polyolefin composition described above are also preferred embodiments of the article.
  • the article is a cable joint, a layer of a power cable, a pipe or an automotive part.
  • the power cable is preferably an alternating current (AC) or direct current (DC) power cable, more preferably a medium voltage (MV), a high voltage (HV) or an extra high voltage (EHV) power cable.
  • the present invention also relates to the use of the polyolefin composition according to the invention in a layer of a power cable.
  • the layer is preferably an insulating layer.
  • the polyolefin composition according to the invention can also be used in a cable joint, a pipe or in an automotive part.
  • the present invention also relates to the use of graphene nanoplatelets (b) in a polyolefin composition comprising an olefin base resin (a) for maintaining a second electrical conductivity of the polyolefin composition to be lower than, the same, or a factor of less than 3 higher as a first electrical conductivity of the olefin polymer base resin (a), wherein the added amount of said graphene nanoplatelets (b) is in the range of from 0.5-30 wt.%, based on the total weight of the polyolefin composition.
  • the olefin polymer base resin is an ethylene-octene copolymer having an MFR2 of 1.1 g/10min, a melt temperature Tm of 97 °C, and a density of 902 kg/m 3 .
  • the copolymer is produced via a metallocene catalyst in a solution based process. This olefin polymer base resin is used in all examples below.
  • GNP M-25 was obtained from XG Sciences, Lansing, Ml USA. It consists of graphene nanoplatelets having a BET surface area of 120 to 150 m 2 /g, a particle size distribution (PSD) of 5 to 25 mm, and a content of volatiles of lower than 1 wt.%. Details are given in Table 1 below.
  • DSC Differential Scanning Calorimetry
  • the polymer density is measured according to the density immersion method described in ISO 1 183.
  • Densities are determined using a method similar to ASTM D7481 - 09, i.e. weighing a specified volume of material after at least three taps.
  • BET surface area BET is determined using ASTM D6556.
  • Measurements were performed using a Novocontrol Alpha spectrometer in the frequency range of 10 -2 to 10 7 Hz, at different temperatures in the range 20- 130°C with an error of ⁇ 0.1 °C, at atmospheric pressure and under nitrogen atmosphere.
  • the sample cell consisted of two stainless steel electrodes 40 mm in diameter and the sample with a thickness of 0.1 mm. Each measurement was carried out six times, and average values were recorded.
  • the complex conductivity the real part of which is used for the analysis herein, can be deducted from the complex dielectric permittivity where is the permittivity of free space. Both permittivity and conductivity were obtained directly from the instrument.
  • the DC conductivity is extracted from the real part of the conductivity, o’, at the limit of very low frequencies. Only temperatures where a plateau in the spectra (i.e. frequency-independent o’) is observed were considered for this analysis.
  • the electrical percolation threshold as defined above was determined as follows:
  • the obtained values of the electrical conductivity under item (h) above are plotted against the values of the amount of the filler.
  • the percolation threshold was determined from the plot as the critical (minimum) concentration in wt.% of the graphene nanoplatelets (b) in the olefin polymer base resin (a) where an exponential increase (at least 2-3 order of magnitude) in electrical conductivity is observed.
  • Filled polyolefin compositions having incorporated graphene nanoplatelets were prepared as follows: All examples were produced using a Brabender mixer (Plasticoder PLE-331 ). The mixer was preheated to 135 °C prior to the addition of the resin. The resin was added first followed by the filler, i.e. the graphene nanoplatelets. As soon as all the components were added, the rotation speed was set to 20rpm and kept for 10 minutes at 135 °C. After the mixing was done, the composition was pelleted and samples were prepared for the relevant tests.
  • comparative example CE1 is the pure olefin polymer base resin
  • inventive examples IE1 to IE4 contain between 2 and 15 wt.% of filler, i.e. graphene nanoplatelets.
  • the electrical conductivity of the filled examples (IE1 to IE4) remains within an order of magnitude with respect to the electrical conductivity of pure olefin polymer resin CE1. In other words, the overall conductivity of the inventive compositions exhibit an invariant electrical conductivity behavior.
  • the polyolefin composition according to the invention can be used as a field grading material for cable joints or any other application where mechanical reinforcement, provided by the graphene nanoplatelets, and invariant conductivity is required.

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  • Polymers & Plastics (AREA)
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Abstract

La présente invention concerne une composition de polyoléfine comprenant une résine à base de polymère d'oléfine (a) ayant une première conductivité, et des nanoplaquettes de graphène (b), ladite composition de polyoléfine ayant une seconde conductivité, et ladite seconde conductivité de ladite composition de polyoléfine étant inférieure ou sensiblement égale à ladite première conductivité de ladite résine à base de polymère d'oléfine.
PCT/EP2020/052388 2019-01-31 2020-01-31 Composition de polyoléfine comprenant des nanoplaquettes de graphène ayant une conductivité électrique invariante WO2020157254A1 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4345849A1 (fr) * 2022-09-29 2024-04-03 TE Connectivity Solutions GmbH Compositions de classification de contraintes électriques et dispositifs les comprenant

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003002652A1 (fr) 2001-06-29 2003-01-09 Ciba Specialty Chemicals Holding Inc. Agents de remplissage organophiles nanometriques fonctionnalises par un additif
WO2003024602A1 (fr) 2001-09-14 2003-03-27 Cornerstone Technologies, L.L.C. Nanostructures en plaquettes de graphite
US20040127621A1 (en) 2002-09-12 2004-07-01 Board Of Trustees Of Michigan State University Expanded graphite and products produced therefrom
WO2008045778A1 (fr) 2006-10-06 2008-04-17 The Trustees Of Princeton University Nanocomposites fonctionnels de graphène caoutchouc
WO2008143692A1 (fr) 2006-10-31 2008-11-27 The Regents Of The University Of California Nanoplaquettes de graphite pour des applications thermiques et électriques
WO2013033603A1 (fr) 2011-09-01 2013-03-07 Rensselaer Polytechnic Institute Polymère d'oxyde de graphène avec résistivité non linéaire
CN108485055A (zh) * 2018-01-30 2018-09-04 天津大学 高压直流电缆用聚丙烯基纳米复合绝缘材料及制备方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003002652A1 (fr) 2001-06-29 2003-01-09 Ciba Specialty Chemicals Holding Inc. Agents de remplissage organophiles nanometriques fonctionnalises par un additif
WO2003024602A1 (fr) 2001-09-14 2003-03-27 Cornerstone Technologies, L.L.C. Nanostructures en plaquettes de graphite
US20040127621A1 (en) 2002-09-12 2004-07-01 Board Of Trustees Of Michigan State University Expanded graphite and products produced therefrom
WO2008045778A1 (fr) 2006-10-06 2008-04-17 The Trustees Of Princeton University Nanocomposites fonctionnels de graphène caoutchouc
WO2008143692A1 (fr) 2006-10-31 2008-11-27 The Regents Of The University Of California Nanoplaquettes de graphite pour des applications thermiques et électriques
WO2013033603A1 (fr) 2011-09-01 2013-03-07 Rensselaer Polytechnic Institute Polymère d'oxyde de graphène avec résistivité non linéaire
CN108485055A (zh) * 2018-01-30 2018-09-04 天津大学 高压直流电缆用聚丙烯基纳米复合绝缘材料及制备方法

Non-Patent Citations (11)

* Cited by examiner, † Cited by third party
Title
"Encyclopedia of Polymer Science and Engineering", vol. 6, 1986, pages: 383 - 410
DATABASE WPI Week 201874, Derwent World Patents Index; AN 2018-71291M, XP002792648 *
KALAITZIDOU ET AL: "Mechanical properties and morphological characterization of exfoliated graphite-polypropylene nanocomposites", COMPOSITES PART A: APPLIED SCIENCE AND MANUFACTURING, ELSEVIER, AMSTERDAM, NL, vol. 38, no. 7, 19 June 2007 (2007-06-19), pages 1675 - 1682, XP022122081, ISSN: 1359-835X, DOI: 10.1016/J.COMPOSITESA.2007.02.003 *
KALAITZIDOU ET AL: "Multifunctional polypropylene composites produced by incorporation of exfoliated graphite nanoplatelets", CARBON, ELSEVIER, OXFORD, GB, vol. 45, no. 7, 1 June 2007 (2007-06-01), pages 1446 - 1452, XP022101681, ISSN: 0008-6223, DOI: 10.1016/J.CARBON.2007.03.029 *
M. EL ACHABY ET AL: "Processing and properties of polyethylene reinforced by graphene nanosheets and carbon nanotubes", MATERIALS AND DESIGN, vol. 44, 3 August 2012 (2012-08-03), GB, pages 81 - 89, XP055386435, ISSN: 0261-3069, DOI: 10.1016/j.matdes.2012.07.065 *
R.KLIMESCHD.LITTMANNF.-O. MAHLING: "Encyclopedia of Materials: Science and Technology", 2001, ELSEVIER SCIENCE LTD., article "Polyethylene: High-pressure", pages: 7181 - 7184
SABET M.,SOLEIMANI H., MOHAMMADIAN E: "Effect of Graphene and Carbon Nanotube on Low-Density Polyethylene Nanocomposites", JOURNAL OF VINYL AND ADDITIVE TECHNOLOGY, vol. 25, no. 1, 1 January 2019 (2019-01-01), pages 35 - 40, XP002792647 *
SCHNIEPP, JOURNAL OF PHYSICAL CHEMISTRY B, vol. 110, 2006, pages 8535
STANKOVICH ET AL., NATURE, vol. 442, 2006, pages 282
VASILEIOU A A; KONTOPOULOU M; DOCOSLIS A: "A noncovalent compatibilization approach to improve the filler dispersion and properties of polyethylene/graphene composites", ACS APPLIED MATERIALS AND INTERFACES, vol. 6, no. 3, 14 January 2014 (2014-01-14), pages 1916 - 1925, XP002792649 *
XIAN JIANG ET AL: "Multifunctional high density polyethylene nanocomposites produced by incorporation of exfoliated graphite nanoplatelets 1: Morphology and mechanical properties", POLYMER COMPOSITES, vol. 31, no. 6, 11 August 2009 (2009-08-11), pages 1091 - 1098, XP055141454, ISSN: 0272-8397, DOI: 10.1002/pc.20896 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4345849A1 (fr) * 2022-09-29 2024-04-03 TE Connectivity Solutions GmbH Compositions de classification de contraintes électriques et dispositifs les comprenant

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