Semiconductive polyolefin composition comprising carbonaceous structures, power cable comprising the same and use thereof

Abstract

This invention relates to a semiconductive polyolefin composition comprising: (A) 80 wt.% to 99.5 wt.% of an olefin polymer-based resin based on the total weight of the semiconductive polyolefin composition; (B) 0.1 wt.% to 10.0 wt.% of a first carbonaceous structure based on the total weight of the semiconductive polyolefin composition; (C) 0.2 wt.% to 15.0 wt.% of carbon black and / or a second carbonaceous structure based on the total weight of the semiconductive polyolefin composition; and (D) optional additives; wherein the combined amount of component (B) and component (C) is at least 0.0 wt.% based on the total weight of the semiconductive polyolefin composition. 3 wt.% and not more than 15.0 wt.%; wherein the electroosmotic threshold of the semiconductive polyolefin composition is not greater than 5 wt.% of the combined amount of components (B) and (C) dispersed in the olefin polymer-based resin (A), the electroosmotic threshold being defined as the critical concentration, in wt.%, of components (B) and (C) in the olefin polymer-based resin (A) where an increase in conductivity exponent is observed; wherein the polyolefin composition has at least 1.10 wt.% as determined by broadband dielectric spectrum for 1.0 wt.% or less, and by 2-point electrical measurement for wt.% or greater. ‑7 The conductivity is S / cm; and wherein components (A) to (D) are added to 100 wt.%.

Description

Technical Field

[0001] This invention relates to a semi-conductive polyolefin composition comprising a carbonaceous structure. The invention also relates to the use of the semi-conductive polyolefin composition. Furthermore, the invention relates to a power cable comprising at least one semi-conductive layer, said at least one semi-conductive layer comprising the polyolefin composition. Background Technology

[0002] Semiconducting materials are defined as materials with an intermediate conductivity between that of insulators and conductors. Typical conductivity ranges for semiconductors are 10⁻⁶. -9 S / cm to 10 3 S / cm, which corresponds to 10 9 ohm·cm to 10 -3 Resistivity between ohms and cm (see, for example, McGraw-Hill Dictionary of Scientific and Technical Terms, 4th Ed., pp. 1698, 1989).

[0003] A common method for achieving semiconductive polymer composites is to incorporate carbon black (CB) into the polymer, typically in amounts between 30 wt.% and 50 wt.%, as disclosed in, for example, US 5,556,697. However, high CB loadings result in high viscosity of the compound. Lower CB loadings are desirable to improve the processability of the compound in cable extruders while maintaining high conductivity. One option is high-structure CB such as Ketjen Black, which allows for a reduction in the amount of conductive filler required, but the high structure significantly increases viscosity even at low loadings.

[0004] Another option for improving the conductivity of semiconductive materials is to incorporate carbon nanotubes (CNTs) and graphene nanosheets (GNPs). Conductive polymer nanocomposites using single-layer or multi-layer graphene nanosheets have been disclosed in WO2008 / 045778A1 and WO2008 / 143692A1.

[0005] Graphene nanoparticles can be formed from thin, freestanding graphite sheets or plates. Nanoparticles can also be shaped to have corners or edges that meet to form points. Sheets can be completely separated from the original graphite particles or can be partially attached to them. Furthermore, more complex secondary structures are also included, such as cones; see, for example, Schniepp, Journal of Physical Chemistry B, 110 (2006) pp. 8535.

[0006] Graphene nanosheets (GNPs) are characterized by being composed of one or more layers of two-dimensional hexagonal lattice carbon atoms. The sheets have a length parallel to the graphite plane (often called the transverse diameter) and a thickness orthogonal to the graphite plane (often called the thickness). Another characteristic of GNPs is that the sheets are very thin but have a large transverse diameter; therefore, GNPs have a very large aspect ratio, i.e., the ratio of the transverse diameter to the thickness.

[0007] Graphene nanosheets can also comprise slightly wrinkled graphene sheets, such as those described, for example, in Stankovich et al., Nature 442, (2006), pp. 282. Additionally, graphene materials with wrinkles leading to another substantially flat geometry are also included. On the other hand, GNPs can be functionalized to improve their interaction with the base resin. Non-limiting examples of surface modification include, for example, treatment with nitric acid; O2 plasma; ultraviolet light / ozone; amines; or acrylamine, as disclosed in US2004 / 127621A1.

[0008] Graphene nanoparticles can be derived from treated graphite sheets, such as expanded graphite exposed to high temperatures (e.g., in the range of 600°C to 1200°C), causing the graphite sheets to expand in an accordion-like manner in a direction perpendicular to the crystalline plane of the graphite, at 100 to 1000 times or more the size of their original volume. These aggregates can be elongated in shape, with dimensions ranging from approximately 1 μm to 100 μm.

[0009] Possible manufacturing processes for graphene nanosheets and single graphene sheets have been disclosed, for example, in US 2002 / 054995 A1, US 2004 / 127621 A1, US 2006 / 241237 A1, and US2006 / 231792 A1. Such processes are further discussed, for example, in Stankovich et al., Nature 442, (2006) pp. 282 and Schniepp, Journal of Physical Chemistry B, 110 (2006) pp. 853. A non-limiting example of the material is Vor-X provided by Vorbecks Materials. TM and xGNP provided by XG Science, Lansing, Michigan, USA TM .

[0010] US2002 / 054995A1 discloses how to generate nanosheets with a lateral diameter to thickness ratio of 1500:1 and a thickness of 1 nm to 100 nm using a high-pressure mill.

[0011] WO 03 / 024602 A1 discloses isolated graphite nanostructures formed from thin graphite sheets having an aspect ratio of at least 1500:1. The graphite nanostructures are produced from synthetic or natural graphite using a high-pressure mill. The resulting graphite nanostructures can be added to polymer materials to produce polymer composites with increased mechanical properties, including increased flexural modulus, thermal deflection temperature, tensile strength, electrical conductivity, and notched impact strength. The effects observed in this disclosure require filler loading, which, if added to polypropylene, is up to 38 wt.% or 53 wt.%.

[0012] EP2 374 842B1 discloses a semiconductive polyolefin composition with a low-load filler concentration, wherein graphene nanosheets are incorporated into an olefin polymer-based resin. The GNPs have a thickness of 100 nm or less and a lateral diameter of 200 μm or less, as measured by atomic force microscopy (AFM). This semiconductive polyolefin composition exhibits low viscosity, high conductivity, and excellent surface smoothness. An EVA-based resin filled with 10 wt.% xGNP™ (XG Science, Lansing, Michigan, USA) provides 9.5 × 10⁻⁶. 6 Resistivity in Ohm·cm. A portion of carbon black was added to adjust the properties of the nanocomposite.

[0013] WO 2013 / 033603 A1 discloses a field-graded material for use as an insulating material in electrical installations. The composite material comprises a polymer material and reduced graphene oxide distributed within the polymer material. The reduced graphene oxide provides the composite material with a nonlinear resistivity. A nonlinear increase in conductivity was observed through the incorporation of reduced graphene oxide, exceeding and saturating the conductivity of the pure polymer material. The conductivity was measured under a significantly high electric field.

[0014] KR 101408925 B1 discloses a lightweight power cable with excellent physical properties such as volume resistivity, thermal solidification, tensile strength, and elongation. The lightweight power cable includes a conductor and various layers, wherein an inner or outer semiconductive layer is formed of a semiconductive composition, and the semiconductive composition includes carbon nanotubes, carbon black, graphene, or a carbon nanotube-graphene hybrid composite material.

[0015] Therefore, compositions used in semiconducting applications still tend to contain excessive amounts of CB and / or graphene nanoparticles. In the case of CB, this has a detrimental effect on processing and mechanical properties, especially since wire and cable applications require significant amounts of CB (approximately 35 wt%–40 wt%) to achieve the desired conductivity. In the case of graphene nanoparticles, substantial amounts are still required in advanced wire and cable applications to achieve improved conductivity. This, in turn, reduces the processing properties of the loaded polymer compositions and increases production costs and equipment complexity. Summary of the Invention

[0016] Therefore, the object of the present invention is to provide a semiconductive polyolefin composition with low filler loading and improved conductivity and processability.

[0017] Surprisingly, this objective can be achieved by an improved semiconducting polyolefin composition comprising, preferably, the following components:

[0018] (A) 80 wt.% to 99.5 wt.% of olefin polymer-based resin based on the total weight of the semiconductive polyolefin composition;

[0019] (B) A first carbonaceous structure comprising 0.1 wt.% to 10.0 wt.% of the total weight of the semiconductive polyolefin composition;

[0020] (C) 0.2 wt.% to 15.0 wt.% of carbon black and / or a second carbonaceous structure based on the total weight of the semiconductive polyolefin composition; and

[0021] (D) Optional additives;

[0022] The combined amount of components (B) and (C) is at least 0.3 wt.% and not more than 15.0 wt.% of the total weight of the semiconductive polyolefin composition.

[0023] Wherein, the electroosmotic flow threshold of the semiconductive polyolefin composition is not greater than 5 wt.% of the combined amount of components (B) and (C) dispersed in the olefin polymer-based resin (A), and the electroosmotic flow threshold is defined as the critical concentration in wt.% of components (B) and (C) in the olefin polymer-based resin (A) where an increase in conductivity exponent is observed.

[0024] The polyolefin composition has at least 1.10 kJ / mL as determined by broadband dielectric spectrum for a percolation threshold of 1.0 wt.% or less, and by two-point electrical measurements for a percolation threshold greater than 1.0 wt.%. -7 The conductivity is S / cm; and wherein components (A) to (D) are added to 100 wt.%.

[0025] A semiconductive polyolefin composition is obtained by melt-blending an olefin polymer-based resin (A) with a first carbonaceous structure (B) and carbon black and / or a second carbonaceous structure (C).

[0026] The present invention also relates to a power cable comprising a semiconductive layer containing a semiconductive polyolefin composition as defined herein, and further relates to the use of a semiconductive polyolefin composition as defined herein in the semiconductive layer of the power cable. Detailed Implementation

[0027] The “electroosmotic threshold” (also known as the “percolation point”) is defined as the critical (minimum) concentration (wt%) of the combination of a first carbonaceous structure (B) with carbon black and / or a second carbonaceous structure (C) in an olefin polymer-based resin (A) at which an increase in conductivity exponentially is observed. In other words, it represents the minimum wt.% loading of the combined carbonaceous structure (B) and carbon black and / or second carbonaceous structure (C) at which the filler loading results in a sufficient network to facilitate current flow, subsequently leading to a sharp increase in the observed conductivity value. The percolation threshold indicates the efficiency of network formation, i.e., the degree of dispersion. Therefore, a low percolation threshold indicates good dispersion of the first carbonaceous structure and the carbon black and / or second carbonaceous structure.

[0028] Percolation is a mathematical concept used to describe the connectivity of random clusters. A percolation threshold describes the onset of long-range connectivity in a random system. Below the threshold, long-range connectivity does not exist, while above the threshold, it begins to materialize. Traditionally, large and dramatic changes in measured properties caused by long-range connectivity are observed near the percolation threshold. For the purposes of this disclosure, "long-range connectivity" is equal to electrical conductivity. Electrical conductivity increases by (at least) two to three orders of magnitude near the threshold. This phenomenon is discussed in detail below, in Thomas Gkourmpis, Innovation and Technology, Borealis AB, Stenungsund SE, in “Controlling the Morphology of Polymers” by Geoffrey R. Mitchell and Ana Tojeira (Eds.), the entire contents of which are incorporated herein by reference.

[0029] In the context of this specification, the term "filler load" refers to the amount of the first carbonaceous structure and carbon black and / or the second carbonaceous structure added, expressed as a weight percentage, based on the total weight of the semiconductive polyolefin composition.

[0030] The electrical saturation conductivity above the percolation threshold was measured at a predetermined load (wt.% of the first carbonaceous structure and carbon black and / or the second carbonaceous structure in the semiconductive polyolefin composition), where the network is fully developed and where, despite further addition of filler, the conductivity remains substantially constant relative to the percolation region. This can be explained by the schematic diagrams on pages 211 (Fig. 8.1) and 215 (Fig. 8.3) of Thomas Gkourmpis, Innovation and Technology, Borealis AB, Stenungsund SE, published by Geoffrey R. Mitchell and Ana Tojeira (Eds.) in *Controlling the Morphology of Polymers*, Springer International Publishers, Switzerland, 2016, as previously cited.

[0031] Post-percolation conductivity above the percolation threshold was observed under loading of the first carbonaceous structure and carbon black and / or the second carbonaceous structure, where the increase in filler volume resulted in a small change in conductivity (within an order of magnitude) compared to the percolation region. Post-percolation conductivity can have the same or different values ​​as saturated conductivity.

[0032] Throughout the description of this invention, the term "polyolefin" or "olefin polymer" includes olefin homopolymers and copolymers of olefins with one or more comonomers. As is well known, a "comonomer" refers to a copolymerizable monomer unit.

[0033] The term "polymer" refers to a polymer made from at least two monomers. It includes, for example, copolymers, terpolymers, and quaternary copolymers.

[0034] The term "carbonaceous structure" refers to multiple carbonaceous components and clusters of partially or completely dispersed individual components, wherein each carbonaceous component is composed of allotropes of carbon, particularly carbon nanotubes (CNTs), graphite, and graphene. Allotropes may also contain atoms other than carbon, such as oxygen, nitrogen, sulfur, phosphorus, and hydrogen. In the context of this invention, carbonaceous structures specifically refer to carbon nanotubes, modified carbon nanotubes, graphene, modified graphene, graphene oxide, reduced graphene oxide, graphite, graphene oxide, and reduced graphene oxide worm-like structures. Carbon nanotubes can be single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs).

[0035] As used herein, the term "mixing" includes mixing materials according to standard methods known in the art. Non-limiting examples of mixing equipment include continuous single-screw or twin-screw mixers such as Farell. TM Werner and Pfleiderer TMKobelco Bolling TM and Bus TM Or include internal intermittent mixers such as Brabender TM Or Banbury TM .

[0036] Component (A)

[0037] Component (A) is an olefin polymer-based resin and is included in the semiconducting polyolefin composition in an amount of 80 wt.% to 99.5 wt.%, preferably 85 wt.% to 99.5 wt.%, and more preferably 87 wt.% to 99.5 wt.%, based on the total weight of the semiconducting polyolefin composition.

[0038] There are no particular limitations on the olefin polymer-based resin (A). However, preferably, the olefin polymer-based resin (A) is selected from ethylene homopolymer, propylene homopolymer, copolymer of ethylene and at least one C3 to C8-α-olefin as comonomer, or copolymer of propylene and at least ethylene or one C4-C8-α-olefin as comonomer.

[0039] In addition, the olefin polymer-based resin (A) preferably comprises a copolymer of ethylene and at least one comonomer selected from unsaturated esters, or comprises a multiphase propylene copolymer.

[0040] Preferably, the polyolefin is an olefin homopolymer or copolymer containing one or more comonomers, more preferably an ethylene homopolymer or copolymer or a propylene homopolymer or copolymer. Preferably, the polyolefin is a copolymer of ethylene and at least one comonomer selected from unsaturated esters or a propylene homopolymer. The polyolefins of the present invention are readily available from polymer suppliers or can be prepared according to known polymerization processes described in or similar to those described in chemical literature.

[0041] When polyolefins, preferably polyethylene, are produced in a low-pressure process, they are typically produced by a coordination catalyst, preferably selected from Ziegler-Natta catalysts, single-center catalysts comprising metallocene and / or non-metallocene catalysts, and / or Cr catalysts, or any mixture thereof. Polyethylene produced in a low-pressure process can have any density, such as very low-density linear polyethylene (VLDPE), linear low-density polyethylene (LLDPE) copolymers of ethylene with one or more comonomers, medium-density polyethylene (MDPE), or high-density polyethylene (HDPE). The polyolefin can be unimodal or multimodal with respect to one or more of its molecular weight distribution, comonomer distribution, or density distribution. The molecular weight distribution of low-pressure polyethylene can be multimodal. Such multimodal polyolefins can have at least two polymer components with different weight-average molecular weights, preferably low weight-average molecular weight (LMW) and high weight-average molecular weight (HMW). Unimodal polyolefins, preferably low-pressure polyethylene, are typically prepared using single-stage polymerization, such as solution, slurry, or gas-phase polymerization, in a manner known in the art. Multimodal (e.g., bimodal) polyolefins, such as low-density polyethylene, can be produced by mechanically blending two or more separately prepared polymer components or by in-situ blending in a multi-stage polymerization process during the preparation of the polymer components. Both mechanical blending and in-situ blending are well-known in this field. The multi-stage polymerization process can preferably be carried out in a series of reactors, such as a loop reactor, which can be a slurry reactor and / or one or more gas-phase reactors. Preferably, a loop reactor and at least one gas-phase reactor are used. Polymerization can also be carried out prior to a prepolymerization step.

[0042] When producing polyolefins, preferably polyethylene, in a high-pressure process, LDPE homopolymers or LDPE copolymers of ethylene with one or more comonomers can be produced. The LDPE homopolymers or copolymers can be unsaturated. For the production of ethylene (co)polymers by high-pressure free radical polymerization, see 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. Klimesch, D. Littmann and F.-O. pp.7181-7184.

[0043] Polyolefin polymers may include, but are not limited to, copolymers of ethylene and unsaturated esters, wherein the ester content is up to 50 wt.% based on the weight of the copolymer. Non-limiting examples of unsaturated esters are vinyl esters, acrylic acid, and methacrylates, which are typically produced by conventional high-pressure processes. Esters may have 3 to about 20 carbon atoms, preferably 4 to 10 atoms. Non-limiting examples of vinyl esters are vinyl acetate, vinyl butyrate, and vinyl neopentanoate. Non-limiting examples of acrylic acid and methacrylates are methyl acrylate, ethyl acrylate, tert-butyl acrylate, n-butyl acrylate, isopropyl acrylate, hexyl acrylate, decyl acrylate, and dodecyl acrylate.

[0044] The polyolefin according to the invention can be an elastomeric ethylene / α-olefin copolymer having an α-olefin content of 15 wt.%, preferably 25 wt.%, based on the weight of the copolymer. These copolymers typically have an α-olefin content of 50 wt.%, preferably 40 wt.%, and most preferably 35 wt.%, or less based on the weight of the copolymer. The α-olefin content is determined by… 13 3C nuclear magnetic resonance (NMR) spectroscopy determination, as described by Randall (Re. Macromolecular Chem Phys C29(2&3)). α-olefins are preferably C3-20 straight-chain, branched, or cyclic α-olefins. Examples of C3-20 α-olefins include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene. α-olefins may also contain cyclic structures such as cyclohexane or cyclopentane, yielding α-olefins such as 3-cyclohexyl-1-propylene and vinylcyclohexane. Although not α-olefins in the classical sense of the term, for the purposes of this invention, certain cyclic olefins such as norbornene and related olefins, particularly 5-ethylidene-2-norbornene, are included in the term "α-olefin" and can be used as described above. Similarly, styrene and related olefins such as α-methylstyrene are α-olefins used for the purposes of this invention. Illustrative examples of copolymers in the sense of this invention include ethylene / propylene, ethylene / butene, ethylene / 1-hexene, ethylene / 1-octene, ethylene / styrene, etc. Illustrative examples of terpolymers include ethylene / propylene / 1-octene, ethylene / butene / 1-octene, ethylene / propylene / diene monomer (EPDM), and ethylene / butene / styrene. Copolymers can be random or block copolymers.

[0045] Copolymerization can be carried out in the presence of one or more additional comonomers capable of copolymerizing with the two monomers mentioned above, and the comonomers may be selected, for example, from: vinyl carboxylic acids, such as vinyl acetate and vinyl pentanoate; (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 vinyl methyl ether and vinyl phenyl ether; α-olefins, such as propylene, 1-butene, 1-hexene, 1-octene and 4-methyl-1-pentene; olefinic unsaturated carboxylic acids, such as (meth)acrylic acid, maleic acid and fumaric acid; and aromatic vinyl compounds, such as styrene and α-methylstyrene.

[0046] Preferred comonomers are vinyl ethers of monocarboxylic acids having one to four carbon atoms, such as vinyl acetate, and (meth)acrylates of alcohols having one to eight carbon atoms, such as methyl (meth)acrylate. The term "(meth)acrylate" as used herein is intended to include both acrylic acid and methacrylic acid. The comonomer content in the polymer may be 40 wt.% or less, preferably from 0.5 wt.% to 35 wt.%, more preferably from 1 wt.% to 25 wt.%.

[0047] Other examples of olefin polymers include: polypropylene, such as homopolymer polypropylene, propylene copolymers; polybutene, butene copolymers; highly short-chain branched α-olefin copolymers with an ethylene comonomer content of 50 mol% or less; polyisoprene; EPR (ethylene-propylene copolymer); EPDM (ethylene-propylene copolymer and diene such as hexadiene, dicyclopentadiene, or ethylidene norbornene copolymer); copolymers of ethylene and α-olefins having 3 to 20 carbon atoms, such as ethylene / octene copolymers; terpolymers of ethylene, α-olefins, and dienes; terpolymers of ethylene, α-olefins, and unsaturated esters; copolymers of ethylene and vinyltrialkoxysilanes; terpolymers of ethylene, vinyltrialkoxysilanes, and unsaturated esters; or copolymers of ethylene with one or more acrylonitriles and maleates. Furthermore, olefin polymers may contain ethylene ethyl acrylate. Comonomers may be randomly incorporated or incorporated in block and / or graft structures.

[0048] The olefin polymer may comprise or be a multiphase olefin copolymer, such as a multiphase propylene copolymer. The multiphase propylene copolymer may preferably be a random propylene copolymer (RAHECO) comprising a matrix phase or a multiphase copolymer having a homopolymer propylene (HECO) as a matrix phase. A random copolymer is a copolymer in which comonomers are partially randomly distributed in the polymer chain, and the random copolymer also consists of an alternating sequence of monomer units (comprising monomers) of two random lengths. Preferably, the random propylene copolymer comprises at least one comonomer selected from ethylene and a C4-C8 α-olefin. Preferred C4-C8 α-olefins are 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, or 1-octene, more preferably 1-butene. Particularly preferred random propylene copolymers may comprise or consist of propylene and ethylene. Furthermore, the comonomer content of the polypropylene matrix is ​​preferably from 0.5 wt.% to 10 wt.%, more preferably from 1 wt.% to 8 wt.%, and even more preferably from 2 wt.% to 7 wt.%. To achieve optimal processing performance and desired mechanical properties, the incorporation of comonomers can be controlled such that one component of the polypropylene contains more comonomers than the other. Suitable polypropylenes are described, for example, in WO03 / 002652A.

[0049] Semiconducting polyolefin compositions can be crosslinkable. "Crosslinkable" means that when a semiconducting polyolefin composition is used in a cable application, the cable layers can be crosslinked before being used in its final application. Crosslinking of polyolefin compositions is well known in the art and can be achieved by any conventional method. For example, details regarding the crosslinking of polyolefins, particularly semiconducting polyolefin compositions, are described in WO2019 / 115548.

[0050] Component (B)

[0051] Component (B) comprises or is composed of a first carbonaceous structure and is included in the semiconducting polyolefin composition in an amount of 0.1 wt.% to 10.0 wt.%, preferably 0.1 wt.% to 9.0 wt.%, more preferably 0.15 wt.% to 8.0 wt.%, and even more preferably 0.2 wt.% to 6.0 wt.%, based on the total weight of the semiconducting polyolefin composition.

[0052] The first carbonaceous structure (B) may be selected from the group consisting of graphene, modified graphene, reduced graphite worm-like structure, carbon nanotubes, modified carbon nanotubes, or combinations thereof, preferably from the group consisting of reduced graphite worm-like structure, carbon nanotubes, modified carbon nanotubes, or combinations thereof, and more preferably from the group consisting of carbon nanotubes, modified carbon nanotubes, or combinations thereof.

[0053] Preferably, the first carbonaceous structure has a 50m diameter as determined according to ASTM D6556-04.2 / g-1000m 2 / g, more preferably 100m 2 / g to 850m 2 / g, or even more preferably 150m 2 / g to 700m 2 / g BET surface area.

[0054] More preferably, the first carbonaceous structure has a density of 1 g / L to 150 g / L, more preferably 5 g / L to 140 g / L, as determined according to ASTM D7481–09.

[0055] Preferably, the first carbonaceous structure may be selected from reduced graphite oxide worm-like (rGOW) structures (or particles) and / or branched carbon nanotubes and / or cross-linked carbon nanotubes, more preferably from rGOW structures and / or branched carbon nanotubes. The rGOW structure may be as defined in WO2019 / 115548. The branched carbon nanotubes and cross-linked carbon nanotubes may be single-walled or multi-walled carbon nanotubes. The carbon nanotubes may also be networks of branched and / or cross-linked carbon nanotubes. Networks of branched and / or cross-linked carbon nanotubes may be in the form of sheets. The rGOW structure, the branched carbon nanotube network, and the cross-linked nanotube network exhibit high surface area and low bulk density of particles and / or sheets.

[0056] Further details regarding the appropriate first carbonaceous structure (B) are given, for example, in WO2019 / 115548.

[0057] The particularly preferred first carbonaceous structure (B) comprises carbon nanotubes, even more preferably branched and / or cross-linked carbon nanotubes, and most preferably a branched carbon nanotube network.

[0058] Preferably, the carbon nanotubes are multi-walled carbon nanotubes, and more preferably multi-walled carbon nanotubes with an average of 4 walls.

[0059] Preferably, the average diameter of the carbon nanotubes is in the range of 5 nm to 25 nm, more preferably in the range of 10 nm to 20 nm.

[0060] Further preferred carbon nanotubes have an average length in the range of 10 nanometers to 150 nanometers, more preferably in the range of 30 nanometers to 120 nanometers, and even more preferably in the range of 50 nanometers to 100 nanometers.

[0061] Further preferably, the purity of the carbon nanotubes is greater than 95%, more preferably greater than 97%, and even more preferably greater than 98%.

[0062] Preferably, the first carbonaceous structure (B) is present in the semiconductive polyolefin composition in an amount of 0.2 wt.% to 2.0 wt.%, preferably 0.25 wt.% to 1.5 wt.%, more preferably 0.25 wt.% to 1.0 wt.% based on the total weight of the semiconductive polyolefin composition.

[0063] More preferably, the first carbonaceous structure (B) comprises preferably carbon nanotubes, modified carbon nanotubes, or a combination thereof, and the first carbonaceous structure (B) is present in the semiconductive polyolefin composition in an amount of 0.2 wt.% to 2.0 wt.%, preferably 0.25 wt.% to 1.5 wt.%, more preferably 0.25 wt.% to 1.0 wt.% based on the total weight of the semiconductive polyolefin composition.

[0064] According to a preferred embodiment, the first carbonaceous structure (B) is a carbon nanotube, preferably a branched carbon nanotube; and / or the carbon nanotube is a multi-walled carbon nanotube, more preferably a multi-walled carbon nanotube having an average of 4 walls; and / or the average diameter of the carbon nanotube is in the range of 5 nm to 25 nm, more preferably in the range of 10 nm to 20 nm; and / or the average length of the carbon nanotube is in the range of 10 nm to 150 nm, more preferably in the range of 30 nm to 120 nm, even more preferably in the range of 50 nm to 100 nm; and / or the purity of the carbon nanotube is greater than 95%, more preferably greater than 97%, even more preferably greater than 98%.

[0065] Component (C)

[0066] Component (C) comprises or is composed of carbon black (C1) and / or a second carbonaceous structure (C2), and component (C) is included in the semiconducting polyolefin composition in an amount of 0.2 wt% to 15.0 wt%, preferably 0.2 wt% to 12.5 wt%, more preferably 0.25 wt% to 11.5 wt%, and most preferably 0.5 wt% to 11 wt% based on the total weight of the semiconducting polyolefin composition.

[0067] Carbon black (C1) can be selected from any commercially available carbon black. Specific examples of suitable carbon black grades include CSX-254, Vulcan XC500, Vulcan XCMax (all available from Cabot Corporation in Boston, Massachusetts, USA), and DenkaBlack (available from Denka Corporation in Japan).

[0068] Preferably, the carbon black (C1) has a strength of 10 kg / m³ as determined according to ASTM D-1513. 3 Up to 600kg / m 3 More preferably 20kg / m 3 Up to 500kg / m3 , or even more preferably 30kg / m 3 Up to 450kg / m 3 (Volume) density.

[0069] Preferably, the carbon black (C1) has an iodine value of 10 mg / g to 2000 mg / g, more preferably 30 mg / g to 1600 mg / g, and even more preferably 50 mg / g to 1400 mg / g, as determined according to ASTM D-1510.

[0070] The second carbonaceous structure (C2) may be selected from the same group of materials as described above with respect to the first carbonaceous structure (B), provided that the second carbonaceous structure (C2) is different from the first carbonaceous structure (B).

[0071] Preferably, the second carbonaceous structure (C2) has a 50m diameter as determined according to ASTM D6556-04. 2 / g to 1000m 2 / g, more preferably 300m 2 / g to 850m 2 / g, or even more preferably 500m 2 / g to 750m 2 / g BET surface area.

[0072] More preferably, the first carbonaceous structure (C2) has a density of 1 g / L to 150 g / L, more preferably 5 g / L to 50 g / L, as determined according to ASTM D7481-09.

[0073] Preferably, component (C) contains only carbon black (C1); or component (C) contains only a second carbonaceous structure (C2); or the second carbonaceous structure (C2) is selected from the group consisting of graphene, modified graphene, reduced graphene worm-like structures, or combinations thereof.

[0074] Preferably, the second carbonaceous structure (C2) is present in the semiconducting polyolefin composition in an amount of 0.2 wt% to 10 wt%, preferably 0.25 wt% to 5 wt%, more preferably 0.25 wt% to 2.5 wt% based on the total weight of the semiconducting polyolefin composition.

[0075] More preferably, particularly when the first carbonaceous structure (B) comprises carbon nanotubes, modified carbon nanotubes, or a combination thereof, component (C), preferably carbon black (C1), is included in the semiconductive polyolefin composition in an amount of 0.2 wt% to 10 wt%, preferably 0.25 wt% to 5 wt%, more preferably 0.25 wt% to 2.5 wt% based on the total weight of the semiconductive polyolefin composition.

[0076] Component (D)

[0077] Semiconducting polyolefin compositions may optionally contain other additives such as antioxidants, stabilizers, water tree flame retardants, processing aids, scorch inhibitors, fillers, metal deactivators, free radical generators, crosslinking aids, flame retardants, acid or ion scavengers, additional inorganic fillers, voltage regulators, or any mixture thereof. Additives are typically used in total amounts from 0.01 wt.% to 10 wt.%.

[0078] Non-limiting examples of antioxidants are sterically hindered or semi-sterically hindered phenols, aromatic amines, aliphatic sterically hindered amines, organophosphites or phosphonites, thio compounds and mixtures thereof.

[0079] Preferably, the antioxidant is selected from diphenylamine and diphenyl sulfide. The phenyl substituents of these compounds may be replaced by other groups such as alkyl, alkylaryl, arylalkyl, or hydroxyl groups.

[0080] Preferably, the phenyl groups of diphenylamine and diphenyl sulfide are preferably substituted with tert-butyl groups at the meta or para positions, and the tert-butyl groups may carry other substituents such as phenyl groups.

[0081] More preferably, the antioxidant is selected from 4,4'-bis(1,1'-dimethylbenzyl)diphenylamine, p-styrenated diphenylamine, 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)phenyl phosphite, polymerized 2,2,4-trimethyl-1,2-dihydroazanaphthalene, or derivatives thereof. Of course, not only one of the above antioxidants can be used, but any mixture thereof can also be used.

[0082] The amount of antioxidant is preferably from 0.005 wt.% to 2.5 wt.% based on the weight of the semiconductive composition, more preferably from 0.005 wt.% to 2 wt.%, even more preferably from 0.01 wt.% to 1.5 wt.%, and even more preferably from 0.04 wt.% to 1.2 wt.%.

[0083] Scorch inhibitors (SRs) are a well-known type of additive in the art and can prevent premature crosslinking. As is also known, SRs can contribute to the level of unsaturation in polymer compositions. Examples of scorch inhibitors are: allyl compounds such as dimers of aromatic α-methylalkenyl monomers, preferably 2,4-di-phenyl-4-methyl-1-pentene, substituted or unsubstituted diphenylethylene, quinone derivatives, hydroquinone derivatives, esters and ethers containing monofunctional vinyl groups, monocyclic hydrocarbons having at least two or more double bonds, or mixtures thereof. Preferably, the amount of scorch inhibitor is in the range of 0.005 wt.% to 2.0 wt.% based on the weight of the semiconductive composition, more preferably in the range of 0.005 wt.% to 1.5 wt.%. Further preferred ranges are, for example, 0.01 wt.% to 0.8 wt.%, 0.03 wt.% to 0.75 wt.%, 0.03 wt.% to 0.70 wt.%, or 0.04 wt.% to 0.60 wt.% based on the weight of the semiconducting composition. A preferred SR added to the semiconducting composition is 2,4-diphenyl-4-methyl-1-pentene.

[0084] Examples of processing aids include, but are not limited to: metal salts of carboxylic acids such as zinc stearate or calcium stearate; fatty acids; fatty amides; polyethylene waxes; ethylene oxide and propylene oxide copolymers; petroleum waxes; nonionic surfactants and polysiloxanes.

[0085] Non-limiting examples of additional fillers are clay-precipitated silica and silicates; calcined silica calcium carbonate.

[0086] Semiconducting polyolefin composition

[0087] The total amount of components (A) to (D) contained in the semiconductive polyolefin composition of the present invention is up to 100 wt.%.

[0088] The combined amount of components (B) and (C) in the semiconductive polyolefin composition of the present invention is at least 0.3 wt.% and not more than 15.0 wt.% based on the total weight of the semiconductive polyolefin composition.

[0089] More specifically, the combined amount of component (B) and component (C) is at least 0.4 wt.%, preferably at least 0.5 wt.%, more preferably at least 1.0 wt.%, based on the total weight of the semiconductive polyolefin composition; and / or

[0090] The combined amount of components (B) and (C) is no more than 12.5 wt.%, preferably no more than 11 wt.%, based on the total weight of the semiconductive polyolefin composition.

[0091] Furthermore, the weight ratio between component (B) and component (C) is in the range of 9:1 to 1:20, preferably in the range of 8:1 to 1:15, and more preferably in the range of 7:1 to 1:10.

[0092] More preferably, especially when the first carbonaceous structure (B) comprises carbon nanotubes, modified carbon nanotubes or a combination thereof, the combined amount of component (B) and component (C) is at least 0.5 wt.% based on the total weight of the semiconductive polyolefin composition, and preferably not more than 10 wt.%, more preferably in the range of 0.5 wt.% to 5 wt.%.

[0093] The electroosmotic threshold of the semiconductive polyolefin composition of the present invention is not greater than 5 wt.% of the combined amount of components (B) and (C) dispersed in the olefin polymer-based resin (A), preferably not greater than 4 wt.%, more preferably not greater than 3 wt.%, and is defined as the critical concentration, in wt.%, of components (B) and (C) in the olefin polymer-based resin (A) where an increase in conductivity exponent is observed.

[0094] The semiconductive polyolefin composition has a percolation threshold of at least 1.10 as determined by broadband dielectric spectrum for 1.0 wt.% or less, and a percolation threshold of greater than 1.0 wt.% as determined by two-point electrical measurements. -7 Conductivity in S / cm; preferably, at least 1.10 based on broadband dielectric spectra for a percolation threshold of 1.0 wt.% or less, and based on two-point electrical measurements for a percolation threshold greater than 1.0 wt.%. -6 Conductivity in S / cm.

[0095] More preferably, particularly when the first carbonaceous structure (B) comprises carbon nanotubes, modified carbon nanotubes, or a combination thereof, the electroosmotic threshold of the semiconductive polyolefin composition is 1 wt.% or less of the combined amount of components (B) and (C) dispersed in the olefin polymer-based resin (A); and the polyolefin composition has an electroosmotic threshold of at least 1.10 wt.% determined based on a broadband dielectric spectrum for 1.0 wt.% or less, and based on two-point electrical measurements for an electroosmotic threshold greater than 1.0 wt.%. - 5 Conductivity in S / cm.

[0096] The semiconductive polyolefin compositions of the present invention surprisingly offer a number of advantages. First, they exhibit improved processability due to their relatively low viscosity (higher MFR2 value) compared to conventional semiconductive polyolefin compositions containing only one type of conductive filler. Unexpectedly, it has been found that using a combination of components (B) and (C) as conductive fillers in semiconductive polyolefin compositions can provide the same or even higher levels of conductivity compared to compositions containing conventional carbon black or previously reported graphene fillers at lower filler loadings.

[0097] According to a preferred embodiment, the semiconductive polyolefin composition according to any one of the preceding claims comprises, and preferably consists of, the following.

[0098] (A) 90 wt.% to 99.5 wt.% of olefin polymer-based resin based on the total weight of the semiconductive polyolefin composition;

[0099] (B) A first carbonaceous structure comprising 0.2 wt.% to 2.0 wt.%, preferably 0.25 wt.% to 1.5 wt.%, and more preferably 0.25 wt.% to 1.0 wt.% of the total weight of the semiconductive polyolefin composition; and

[0100] (C) 0.2 wt.% to 10 wt.%, preferably 0.25 wt.% to 5 wt.%, and more preferably 0.25 wt.% to 2.5 wt.% of carbon black and / or a second carbonaceous structure based on the total weight of the semiconductive polyolefin composition, wherein the carbon black and / or the second carbonaceous structure is preferably carbon black;

[0101] The combined amount of component (B) and component (C) is at least 0.5 wt.% based on the total weight of the semiconducting polyolefin composition, preferably not more than 10 wt.% based on the total weight of the semiconducting polyolefin composition, and more preferably in the range of 0.5 wt.% to 5 wt.% based on the total weight of the semiconducting polyolefin composition.

[0102] The electroosmotic threshold of the semiconductive polyolefin composition is 1 wt.% or less of the combined amount of components (B) and (C) dispersed in the olefin polymer-based resin (A).

[0103] The polyolefin composition has a percolation threshold of at least 1.10 g / L, determined based on a broadband dielectric spectrum for 1.0 wt.% or less, and a percolation threshold of at least 1.10 g / L, determined based on two-point electrical measurements for a percolation threshold greater than 1.0 wt.%. -5 Conductivity in S / cm; and

[0104] Preferably, the first carbonaceous structure is a carbon nanotube, a modified carbon nanotube, or a combination thereof.

[0105] Any suitable process known in the art can be used to prepare the semiconductive polyolefin composition of the present invention, such as dry mixing, solution mixing, solution shear mixing, melt mixing, extrusion, etc. However, it is preferred to prepare the semiconductive polyolefin composition by melt mixing the olefin polymer-based resin (a) with a first carbonaceous structure and carbon black and / or a second carbonaceous structure (b) in an extruder such as a Brabender mixer.

[0106] The present invention also relates to a method for preparing preferred semiconductive polyolefin compositions of the present invention, the method comprising premixing a first carbonaceous structure and carbon black and / or a second carbonaceous structure. Premixing as used herein should indicate that the mixing occurs before the resulting mixture is contacted and mixed with an olefin polymer-based resin. Premixing can be carried out in a dispersant such as isopropanol. Preferably, the olefin polymer-based resin is then added to the dispersed mixture of the first carbonaceous structure, carbon black and / or second carbonaceous structure, and / or filler, and the complete mixture is then introduced into a mixer, preferably an extruder, such as a Brabender mixer, as will be described in more detail below.

[0107] The present invention also relates to a power cable comprising a semiconductive layer containing a semiconductive polyolefin composition according to the present invention.

[0108] The object of the present invention can also be achieved by using the semiconductive polyolefin composition of the present invention in the semiconductive layer of the power cable.

[0109] Furthermore, the present invention relates to a semiconductive polyolefin composition that can be obtained by this method.

[0110] The invention will now be described by way of non-limiting examples.

[0111] Example section

[0112] 1. Materials

[0113] polymer-based resins

[0114] Polypropylene (PP)

[0115] The polypropylene (PP) used in the example is HC300BF, which is an isotactic propylene homopolymer with an MFR2 (230℃ / 2.16kg) of 3.3g / 10min (isotacticity index: 98%) and is commercially available from Borealis AG.

[0116] High-density polyethylene (HDPE)

[0117] In all examples using HDPE, the polyolefin-based resin was Ziegler-Natta catalyzed HDPE, a unimodal high-density copolymer of ethylene and 1-butene (comonomer content 0.8 mol%), prepared in a gas-phase reactor via low-pressure polymerization, with a density of 962 kg / m³. 3 The MFR2 (2.16 kg, 190 °C) was 12 g / 10 min. The HDPE was obtained from Borealis AB.

[0118] Ethylene-butyl acrylate (EBA)

[0119] The ethylene-butyl acrylate (EBA) used in the example is an ethylene-butyl acrylate copolymer (butyl acrylate content of 17 wt.%, density of 925.5 kg / m³). 3 MFR2 (7g / 10min) was derived from Borealis Antwerp.

[0120] Low-density polyethylene (LDPE)

[0121] In all examples using LDPE, the olefin polymer-based resin was standard low-density polyethylene (LDPE). The LDPE was obtained from Borealis AB, produced in a tubular reactor, with an MFR2 (2.16 kg, 190 °C) of 2 g / 10 min and a density of 922.5 kg / m³. 3 .

[0122] carbonaceous structure

[0123] Carbonaceous structure 1 (CS1) was obtained from Cabot Corporation, Boston, MA, USA. CS1 (GPX-404) is a carbonaceous structure that forms clusters or worm-like structures and was obtained from Cabot Corporation, Boston, Massachusetts, USA. CS1 can be obtained by the method described in WO2019 / 070514.

[0124] Carbon nanostructures (CNS)(CS2)Athlos were prepared by Cabot Corporation, based in Boston, Massachusetts, USA.

[0125] The properties of carbonaceous structures are summarized in Table 1.

[0126]

[0127]

[0128] carbon black

[0129] The Vulcan XC500 (CB1) was acquired by Cabot Corporation, based in Boston, Massachusetts, USA.

[0130] The Vulcan XCMax (CB2) is owned by Cabot Corporation, based in Boston, Massachusetts, USA.

[0131] CSX-254 carbon black (CB3) is supplied by Cabot Corporation, based in Boston, Massachusetts, USA.

[0132] Denka Black (CB4) is sourced from Denka Corporation of Japan.

[0133] 2. Measurement methods and procedures

[0134] melt flow rate

[0135] MFR2 was measured according to ISO 1133 at 190°C under a 2.16 kg load and at 230°C for polyethylene. 21 Measurements were performed on polyethylene at 190°C and polypropylene at 230°C under a 21.6 kg load, according to ISO 1133.

[0136] Polymer density

[0137] The polymer density is measured according to the density impregnation method described in ISO 1183.

[0138] Density of carbonaceous structure

[0139] Density was determined using a method similar to ASTM D7481–09, which involved weighing a specified volume of material after at least three tapping operations.

[0140] BET surface area

[0141] BET was determined using ASTM D6556-04.

[0142] Volatility

[0143] Volatility was determined by thermogravimetric analysis under nitrogen conditions.

[0144] Particle size distribution (PSD)

[0145] PSD is determined using scanning electron microscopy without the need for statistical analysis.

[0146] Electroosmotic Flow Threshold

[0147] The electroosmotic flow threshold defined above is determined as follows:

[0148] The conductivity of each sample containing different amounts of filler was calculated as the reciprocal of the resistivity measured above:

[0149] σ=1 / ρ

[0150] The obtained conductivity values ​​were plotted against the amount of filler. The percolation threshold was determined from the graph as the critical (minimum) concentration in wt.% of the reduced graphene oxide worm-like structure (b) in the olefin polymer-based resin (a), where an exponential increase in conductivity (at least 2 to 3 orders of magnitude) was observed, as shown below.

[0151] electrical conductivity

[0152] The conductivity is the conductivity above the seepage threshold when the network is fully developed, and the change in conductivity is minimal (within an order of magnitude) despite further addition of filler. Therefore, the post-seepage conductivity is determined from the curve in the region where the exponential increase in conductivity has stopped and the curve has flattened.

[0153] Ingredients

[0154] The following methods are used to prepare filled polyolefin compositions with incorporated carbonaceous structures and / or carbon black:

[0155] All samples were produced using a Brabender mixer (Plasticoder PLE-331). The mixer was preheated before adding the resins (polyvinyl resin to 180°C and polypropylene resin to 210°C). The rotation speed was set to 10 rpm. The resin was added first, followed by the filler. Once all components were added, the rotation speed was increased to 50 rpm and maintained for 10 minutes. After mixing, the composition was granulated and samples were prepared for relevant tests.

[0156] 3. Results

[0157] The properties of the obtained semiconductive polyolefin compositions are shown in the table below.

[0158] Table 2

[0159]

[0160]

[0161]

[0162]

[0163] Table 3

[0164]

[0165]

[0166]

[0167] Table 4

[0168]

[0169]

[0170]

[0171]

[0172]

[0173] As can be seen from the examples of the present invention, the combination of the first carbonaceous structure with carbon black and / or the second carbonaceous structure provides favorable electrical conductivity at low filler loadings. In particular, as shown by IE1-IE4 and IE6-IE10, the amount of carbon black can be significantly reduced, which has a positive impact on the processing properties of the corresponding semiconductive polyolefin compositions.

[0174] As shown in IE5, a similar effect can be observed through the combination of the first and second carbonaceous structures. IE5 shows that the combination of the two carbonaceous structures according to the invention allows for a reduction in the amount of CS1, which is specifically used in semiconductive polyolefin compositions, while maintaining good electrical conductivity. This also has a positive impact on processing.

[0175] Although the invention has been described with reference to various embodiments, those skilled in the art will recognize that changes can be made without departing from the scope of the invention. The detailed description is intended to be illustrative, and the appended claims, including all equivalents, are intended to define the scope of the invention.

Claims

1. A semiconductive polyolefin composition comprising: (A) 80 wt.% to 99.5 wt.% of an olefin polymer-based resin based on the total weight of the semiconductive polyolefin composition; (B) A first carbonaceous structure comprising 0.1 wt.% to 10.0 wt.% of the total weight of the semiconductive polyolefin composition; (C) Carbon black, ranging from 0.2 wt.% to 15.0 wt.% based on the total weight of the semiconductive polyolefin composition; and (D) Optional additives; in, The combined amount of components (B) and (C) is at least 0.3 wt.% and not more than 15.0 wt.% based on the total weight of the semiconductive polyolefin composition. Wherein, the electroosmotic flow threshold of the semiconductive polyolefin composition is not greater than 5 wt.% of the combined amount of component (B) and component (C) dispersed in the olefin polymer-based resin (A), and the electroosmotic flow threshold is defined as the critical concentration, in wt.%, of component (B) and component (C) in the olefin polymer-based resin (A) at which an increase in conductivity exponential is observed. The polyolefin composition has at least 1×10⁻⁶ ohms as determined by broadband dielectric spectroscopy for a percolation threshold of 1.0 wt.% or less, and by two-point electrical measurements for a percolation threshold greater than 1.0 wt.%. -7 Conductivity in S / cm; Among them, components (A) to (D) are added to 100 wt.%; and Wherein, the first carbonaceous structure (B) is selected from reduced graphite oxide worm-like (rGOW) structures, branched and / or cross-linked carbon nanotube networks, wherein the branched and / or cross-linked carbon nanotube networks are in the form of sheets.

2. The semiconductive polyolefin composition according to claim 1, wherein, The weight ratio between component (B) and component (C) is in the range of 9:1 to 1:

20.

3. The semiconductive polyolefin composition according to claim 2, wherein, The weight ratio between component (B) and component (C) is in the range of 8:1 to 1:

15.

4. The semiconductive polyolefin composition according to claim 2, wherein, The weight ratio between component (B) and component (C) is in the range of 7:1 to 1:

10.

5. The semiconductive polyolefin composition according to claim 1, wherein, The olefin polymer-based resin (A) is present in an amount of 85 wt.% to 99.5 wt.% based on the total weight of the semiconductive polyolefin composition.

6. The semiconductive polyolefin composition according to claim 5, wherein, The olefin polymer-based resin (A) is present in an amount of 87 wt.% to 99.5 wt.% based on the total weight of the semiconductive polyolefin composition.

7. The semiconductive polyolefin composition according to claim 1, wherein, The first carbonaceous structure (B) is present in an amount of 0.1 wt.% to 9.0 wt.% based on the total weight of the semiconductive polyolefin composition.

8. The semiconductive polyolefin composition according to claim 7, wherein, The first carbonaceous structure (B) is present in an amount of 0.15 wt.% to 8.0 wt.% based on the total weight of the semiconductive polyolefin composition.

9. The semiconductive polyolefin composition according to claim 7, wherein, The first carbonaceous structure (B) is present in an amount of 0.2 wt.% to 6.0 wt.% based on the total weight of the semiconductive polyolefin composition.

10. The semiconductive polyolefin composition according to claim 1, wherein, The carbon black (C) is present in an amount of 0.2 wt.% to 12.5 wt.% based on the total weight of the semiconductive polyolefin composition.

11. The semiconductive polyolefin composition according to claim 10, wherein, The carbon black (C) is present in an amount of 0.25 wt.% to 11.5 wt.% based on the total weight of the semiconductive polyolefin composition.

12. The semiconductive polyolefin composition according to claim 10, wherein, The carbon black (C) is present in an amount of 0.5 wt.% to 11 wt.% based on the total weight of the semiconductive polyolefin composition.

13. The semiconductive polyolefin composition according to claim 1, in, The combined amount of component (B) and component (C) is at least 0.4 wt.% based on the total weight of the semiconductive polyolefin composition; and / or The combined amount of component (B) and component (C) is no more than 12.5 wt. based on the total weight of the semiconductive polyolefin composition.

14. The semiconductive polyolefin composition according to claim 13, in, The combined amount of component (B) and component (C) is at least 0.5 wt.% based on the total weight of the semiconductive polyolefin composition; and / or The combined amount of component (B) and component (C) is no more than 11 wt. based on the total weight of the semiconductive polyolefin composition.

15. The semiconductive polyolefin composition according to claim 13, in, The combined amount of component (B) and component (C) is at least 1.0 wt. based on the total weight of the semiconductive polyolefin composition.

16. The semiconductive polyolefin composition according to any one of claims 1-15, wherein, The electroosmotic current threshold of the semiconductive polyolefin composition is no greater than 4 wt. of the combined amount of component (B) and component (C) dispersed in the olefin polymer-based resin (A).

17. The semiconductive polyolefin composition according to claim 16, wherein, The electroosmotic current threshold of the semiconductive polyolefin composition is no greater than 3 wt. of the combined amount of component (B) and component (C) dispersed in the olefin polymer-based resin (A).

18. The semiconductive polyolefin composition according to any one of claims 1-15, wherein, The polyolefin composition has at least 1×10⁻⁶ ppm as determined by broadband dielectric spectrum for a percolation threshold of 1.0 wt.% or less, and by two-point electrical measurements for a percolation threshold greater than 1.0 wt.%. -6 Conductivity in S / cm.

19. The semiconductive polyolefin composition according to any one of claims 1-15, wherein, The olefin polymer-based resin is selected from the group consisting of ethylene homopolymer, propylene homopolymer, copolymer of ethylene and at least one C3 to C8-α-olefin as comonomer, or copolymer of propylene and at least ethylene or one C4-C8-α-olefin as comonomer.

20. The semiconductive polyolefin composition according to any one of claims 1-15, wherein, The olefin polymer-based resin (A) comprises a copolymer of ethylene and at least one comonomer selected from unsaturated esters.

21. The semiconductive polyolefin composition according to any one of claims 1-15, comprising: (A) 90 wt.% to 99.5 wt.% of an olefin polymer-based resin based on the total weight of the semiconductive polyolefin composition; (B) A first carbonaceous structure comprising 0.2 wt.% to 2.0 wt.% of the total weight of the semiconductive polyolefin composition; and (C) 0.2 wt.% to 10 wt.% carbon black based on the total weight of the semiconductive polyolefin composition; in, The combined amount of component (B) and component (C) is at least 0.5 wt.% based on the total weight of the semiconductive polyolefin composition. Wherein, the electroosmotic flow threshold of the semiconductive polyolefin composition is 1 wt.% or less of the combined amount of component (B) and component (C) dispersed in the olefin polymer-based resin (A); and The polyolefin composition has at least 1×10⁻⁶ ohms as determined by broadband dielectric spectroscopy for a percolation threshold of 1.0 wt.% or less, and by two-point electrical measurements for a percolation threshold greater than 1.0 wt.%. -5 Conductivity in S / cm.

22. The semiconductive polyolefin composition according to claim 21, comprising: (B) A first carbonaceous structure comprising 0.25 wt.% to 1.5 wt.% of the total weight of the semiconductive polyolefin composition; and (C) 0.25 wt.% to 5 wt.% carbon black based on the total weight of the semiconductive polyolefin composition; in, The combined amount of component (B) and component (C) shall not exceed 10 wt. based on the total weight of the semiconductive polyolefin composition.

23. The semiconductive polyolefin composition according to claim 21, comprising: (B) A first carbonaceous structure comprising 0.25 wt.% to 1 wt.% of the total weight of the semiconductive polyolefin composition; and (C) 0.25 wt.% to 2.5 wt.% carbon black based on the total weight of the semiconductive polyolefin composition; in, The combined amount of component (B) and component (C) is in the range of 0.5 wt.% to 5 wt.% based on the total weight of the semiconductive polyolefin composition.

24. A power cable comprising a semiconductive layer, the semiconductive layer comprising a semiconductive polyolefin composition as described in any one of claims 1-23.

25. Use of a semiconductive polyolefin composition as described in any one of claims 1 to 23 in a semiconductive layer of an electrical cable.

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