Polypropylene composition for wire and cable applications

Abstract

A cable with good thermal conductivity includes an electrical conductor and a thermoplastic layer surrounding the electrical conductor, wherein the thermoplastic layer includes a polyolefin composition (I) comprising: -10 wt% to 40 wt% of fraction (a), fraction (a) comprising a propylene homopolymer or copolymer having up to and including 10 wt% of comonomer selected from ethylene and C4-C10 α-olefins, fraction (a) having a solubility of ≤15 wt% in xylene at 25°C; -20 wt% to Fraction (b) of 60% by weight, comprising an ethylene homopolymer or an ethylene copolymer having a comonomer selected from C4-C10 α-olefins and containing at least 75% by weight of ethylene-derived units; and fraction (c) of -30% to 60% by weight, comprising an ethylene copolymer having at least one comonomer selected from propylene and C4-C10 α-olefins and 40% to less than 75% by weight of ethylene-derived units.

Description

Technical Field

[0001] This disclosure relates to a polypropylene composition containing a propylene polymer and an ethylene polymer, the polypropylene composition being suitable for use in wire and cable applications. Background Technology

[0002] In the ever-evolving field of electrical and communication systems, the development of advanced wire and cable solutions plays a crucial role in enabling the efficient and reliable transmission of power, data, and signals across numerous industries and applications.

[0003] Polyolefins have proven to be excellent materials for cable insulation, possessing good electrical and mechanical properties.

[0004] For example, patent application WO2020 / 229687 discloses a polyolefin composition with good creep resistance for cable insulation, the polyolefin composition comprising a combination of LDPE, propylene homopolymer and a small amount of random heteropolymer propylene copolymer.

[0005] Patent document EP3033390B1 discloses a polymer composition with good mechanical and electrical properties suitable for manufacturing an electrical insulating layer, the polymer composition comprising an ethylene-propylene copolymer and a propylene homopolymer in a weight ratio of 90:10 to 10:90.

[0006] Patent document EP3747030B1 discloses a cable insulation or sheath comprising ethylene interpolymer T1), peroxide and component T2, wherein component T2 contains propylene homopolymer A), ethylene / α-olefin copolymer B and ethylene / propylene copolymer C, and the cable has improved compressive strength.

[0007] International patent application WO2012 / 000885 discloses a composition suitable for wire and cable applications, comprising: a propylene homopolymer or copolymer A) having a solubility of less than 20% by weight in xylene; an ethylene / propylene copolymer containing 42% to 70% by weight of ethylene; and a blend of an ethylene copolymer having a Shore hardness A of less than 90 and a propylene copolymer having a Shore hardness A of less than 90. The composition has low hardness and very good rheological properties.

[0008] European patent EP2528968B1 discloses an energy cable having at least one polypropylene nanocomposite electrical insulation layer, wherein the insulation layer comprises at least one heterogeneous copolymer.

[0009] Polypropylene-based insulation materials used in cables typically possess excellent electrical properties, but their thermal conductivity is less than ideal. Against this backdrop, there remains a pressing need for insulation materials for wires and cable systems that exhibit good thermal conductivity to improve heat dissipation in wires and cable systems that include polyolefin insulation layers.

[0010] The applicant discovered that, compared with known insulating materials used in wire and cable systems, polyolefin compositions containing a combination of propylene and ethylene polymers exhibit good thermal conductivity while maintaining good mechanical properties. Summary of the Invention

[0011] The purpose of this disclosure is to provide a cable comprising an electrical conductor and a thermoplastic layer surrounding the electrical conductor, wherein the thermoplastic layer comprises a polyolefin composition (I) comprising:

[0012] - A fraction (a) comprising 10% to 40% by weight, the fraction (a) comprising a propylene homopolymer or a propylene copolymer having up to and including 10.0% by weight of a comonomer selected from ethylene and C4-C10 α-olefins, the fraction (a) having a solubility in xylene at 25°C equal to or less than 15.0% by weight of the fraction (a);

[0013] - A fraction (b) comprising 20% ​​to 60% by weight, the fraction (b) comprising an ethylene homopolymer or an ethylene copolymer having a comonomer selected from C4-C10 α-olefins, the ethylene copolymer containing at least 75.0% by weight of ethylene-derived units based on fraction (b); and

[0014] - A fraction (c) comprising 30% to 60% by weight, the fraction (c) comprising an ethylene copolymer having at least one comonomer selected from propylene and C4-C10 α-olefins, the copolymer containing 40.0% to less than 75.0% by weight of ethylene-derived units based on fraction (c).

[0015] The quantities of grade (a), grade (b), and grade (c) are based on the total weight of grade (a), grade (b), and grade (c).

[0016] Another object of this disclosure is to provide a method for insulating an electrical conductor, the method comprising the following steps:

[0017] (i) Provide an electrical conductor;

[0018] (ii) Provide the polyolefin composition (I) as described above; and

[0019] (iii) The electrical conductor is surrounded by the polyolefin composition (I).

[0020] The polyolefin composition (I) disclosed herein has a combination of good thermal conductivity and good mechanical properties, thereby forming an insulating layer with a corresponding combination of good properties.

[0021] While several embodiments have been disclosed, other embodiments will become apparent to those skilled in the art from the following detailed description. As will be apparent, certain embodiments disclosed herein can be modified in various obvious respects without departing from the spirit and scope of the claims presented herein. Therefore, the following detailed description should be considered illustrative rather than restrictive in nature. Detailed Implementation

[0022] In the context of this disclosure;

[0023] - Unless otherwise stated, percentages are expressed by weight;

[0024] - Unless otherwise stated, the total weight of the polymer composition is 100% by weight.

[0025] - The term "comprising / including" when referring to polymers or polymer compositions, mixtures or blends shall be interpreted as meaning "comprising / including or substantially consisting of";

[0026] The term "consistently made up of" means that other components, besides those that are mandatory, may also be present in the material, provided that the fundamental properties of the material are not substantially affected by their presence. Examples of components that, when present in conventional amounts, do not substantially affect the properties of polymers or polyolefin compositions, mixtures, or blends are catalyst residues, antistatic agents, and processing aids;

[0027] - The term "copolymer" refers to a polymer derived from at least two different comonomers through intentional polymerization; that is, the term "copolymer" includes terpolymers.

[0028] In a first aspect, this disclosure provides a cable comprising an electrical conductor and a thermoplastic layer surrounding the electrical conductor, wherein the thermoplastic layer comprises a polyolefin composition (I) comprising:

[0029] - A fraction (a) comprising 10% to 40% by weight, preferably 10% to 30% by weight, the fraction (a) comprising a propylene homopolymer or a propylene copolymer having up to and including 10.0% by weight of a comonomer selected from ethylene and C4-C10 α-olefins, the fraction (a) having a solubility in xylene at 25°C equal to or less than 15.0% by weight of the fraction (a);

[0030] - A fraction (b) comprising 20% ​​to 60% by weight, preferably 30% to 40% by weight, the fraction (b) comprising an ethylene homopolymer or an ethylene copolymer having a comonomer selected from C4-C10 α-olefins, the ethylene copolymer containing at least 75.0% by weight of ethylene-derived units based on fraction (b); and

[0031] - A fraction (c) comprising 30% to 60% by weight, preferably 40% to 50% by weight, the fraction (c) comprising an ethylene copolymer having at least one comonomer selected from propylene and C4-C10 α-olefins, the copolymer containing 40.0% to less than 75.0% by weight of ethylene-derived units based on fraction (c).

[0032] The quantities of grade (a), grade (b), and grade (c) are based on the total weight of grade (a), grade (b), and grade (c).

[0033] Preferably, the C4-C10 α-olefins in fractions (a), (b) and (c) are independently selected from butene-1, hexene-1, octene-1, 3-methyl-1-pentene and decene-1; butene-1 is particularly preferred.

[0034] The various polymer fractions (a), (b) and (c) of the polyolefin composition (I) are defined in more detail below.

[0035] The polymer fraction (a) preferably has at least one of the following characteristics, more preferably all of the following characteristics:

[0036] - Contains a propylene homopolymer having a solubility in xylene at 25°C equal to or less than 5.0% by weight based on fraction (a); or a propylene-ethylene copolymer containing 0.5% to 7.0%, preferably 1.0% to 6.0% by weight, and more preferably 1.5% to 4.5% by weight of ethylene-derived units based on polymer fraction (a), having a solubility in xylene at 25°C equal to or less than 12.0% by weight based on polymer fraction (a); and / or

[0037] - Melt flow rate (MFR(a)) in the range of 10 to 150 g / 10 min, more preferably 30 to 120 g / 10 min (ISO 1133-1:2011, 230 °C / 2.16 kg).

[0038] The polymer fraction (b) preferably has at least one of the following characteristics, more preferably all of the following characteristics:

[0039] - Contains an ethylene homopolymer having a solubility in xylene at 25°C equal to or less than 7.0% by weight based on polymer fraction (b); or an ethylene / butene-1 copolymer containing 0.1% to 20.0%, preferably 5.0% to 15.0% by weight, more preferably 7.0% to 12.0% by weight of butene-1-derived units based on polymer fraction (b), and having a solubility in xylene at 25°C equal to or less than 25.0% by weight, preferably equal to or less than 17.0% by weight based on polymer fraction (b); and / or

[0040] - Between 940 and 965 kg / m 3 Density within the range (ISO 1183-1 / A:2019, at 23°C).

[0041] In one embodiment, polymer fraction (c) comprises an ethylene-propylene copolymer containing 45.0% to 70.0%, preferably 45.0% to 65.0%, more preferably 50.0% to 60.0% by weight of ethylene-derived units based on the weight of polymer fraction (c), and having a solubility in xylene at 25°C of 65.0% to 95.0%, preferably 75.0% to 85.0% by weight based on the weight of polymer fraction (c).

[0042] In a preferred embodiment, polymer fraction (c) comprises an ethylene / propylene / butene-1 terpolymer, the terpolymer containing:

[0043] -Based on fraction (c), 45.0% to 65.0% by weight, preferably 48.0% to 62.0% by weight, more preferably 50.0% to 57.0% by weight of units derived from ethylene;

[0044] -Based on fraction (c), 10.0% to 30.0% by weight, preferably 12.0% to 25.0% by weight, more preferably 15.0% to 22.0% by weight of units derived from butene-1; and

[0045] - The weight of fraction (c) is up to and includes 100% propylene-derived units by weight; preferably 5% to 45% by weight, more preferably 13% to 40% by weight, and still preferably 21% to 35% by weight, propylene-derived units by weight.

[0046] Preferably, the polyolefin composition (I) has at least one of the following characteristics, more preferably all of the following characteristics:

[0047] - Melt flow rate (MFR(I)) in the range of 0.5 to 10.0 g / 10 min, more preferably 1.0 to 5.0 g / 10 min (ISO 1133-1:2011, 230 °C / 2.16 kg); and / or

[0048] - At 25°C, the total weight of fractions (a), (b), and (c) is equal to or less than 60.0% by weight, preferably in the range of 30.0% to 55.0% by weight; and / or

[0049] - equal to or less than 910 kg / m 3 Preferably, the concentration is between 890 and 910 kg / m³. 3 More preferably 895 to 905 kg / m 3 Density within the range (ISO 1183-1 / A:2019, at 23°C).

[0050] The polyolefin composition (I) more preferably also has at least one of the following characteristics, and more preferably has all of the following characteristics:

[0051] -Density [Kg / m³] 3 The ratio of the total ethylene content (wt%) to the total ethylene content is equal to or less than 25, preferably equal to or less than 20, more preferably equal to or less than 18; and / or

[0052] - The total ethylene content, based on the weight of the polyolefin composition (I), is equal to or greater than 50.0% by weight; and / or

[0053] - At 23℃, it is equal to or greater than 50 kJ / m 2 Preferably, the concentration at 23°C is not higher than 100 kJ / m 2 Charpy impact strength (ISO 179-1:2010 eA); and / or

[0054] -Equal to or greater than 85kJ / m at -40℃ 2 Preferably, the value is not higher than 180 kJ / m at -40℃.2 Charpy impact strength (ISO 179-1:2010 eA); and / or

[0055] - Tensile modulus in the range of 120 to 350 MPa, preferably 170 to 300 MPa (ISO 527-1, ISO 527-2); and / or

[0056] - A Vicat softening temperature equal to or greater than 60°C, preferably equal to or greater than 70°C, more preferably ranging from 70°C to 90°C (ISO 306, A50); and / or

[0057] - Heat distortion temperature B in the range of 33°C to 50°C, preferably 35°C to 43°C (ISO 75B-1, ISO 75B-2, 0.45MPa, 48h, unannealed); and / or

[0058] - A thermal conductivity at 90°C equal to or greater than 220.0 mV / m • K, preferably equal to or greater than 230.0 mV / m • K, and more preferably in the range of 250.0 to 280.0 mV / m • K, wherein the thermal conductivity is measured using the method described in the Examples section.

[0059] The polyolefin composition (I) is preferably prepared by polymerizing the relevant monomers in successive polymerization stages, wherein all polymerization stages, except for the first polymerization stage, are carried out in the presence of the polymer material formed in the immediately preceding polymerization stage and the catalyst used. Preferably, polymer fraction (a) is prepared in the first polymerization stage, polymer fraction (b) is prepared in the second polymerization stage, and polymer fraction (c) is prepared in the third polymerization stage, with each stage after the first polymerization stage being carried out in the presence of the polymer material prepared in the immediately preceding polymerization stage. The amounts of fraction (a), fraction (b), and fraction (c) correspond to the distribution between polymerization stages. Each polymerization stage is carried out in at least one polymerization reactor.

[0060] The polymerization stage is preferably carried out in the presence of a Ziegler-Natta catalyst. More preferably, the polymerization stage is carried out in the presence of a Ziegler-Natta catalyst comprising the reaction products of:

[0061] i) A solid catalyst component comprising Ti, Mg, Cl and at least an internal electron donor compound;

[0062] ii) Alkyl aluminum compounds; and

[0063] iii) External electron donor compounds.

[0064] The internal electron donor compound is preferably selected from ethers, ketones, lactones, organic compounds containing N, P, and / or S atoms of monocarboxylic or dicarboxylic organic acids and esters, such as benzoates, malonates, phthalates, and certain succinates. Examples of internal donors are described in US4,522,930, EP045977A2, and international patent applications WO00 / 63261 and WO01 / 57099. Phthalate esters, such as diisobutyl phthalate, dioctyl phthalate, diphenyl phthalate, benzyl butyl phthalate, and succinates, are particularly suitable. Another particularly suitable internal electron donor compound is a 1,3-diether, as illustrated in EP361493A1 and EP728769.

[0065] The particles of the solid component (i) may have a substantially spherical morphology and an average diameter ranging from 5 to 150 μm, preferably from 20 to 100 μm, and more preferably from 30 to 90 μm. Particles having a substantially spherical morphology are those in which the ratio between the longer axis and the shorter axis is equal to or less than 1.5, and preferably less than 1.3.

[0066] According to one method, a solid catalyst component (i) can be prepared by reacting the following: a titanium compound of the formula Ti(OR)q-yXy, where q is the valence of titanium and y is a number between 1 and q, preferably TiCl4; and magnesium chloride (where p is a number between 0.1 and 6, preferably 2 to 3.5, and R is a hydrocarbon group having 1 to 18 carbon atoms) with an adduct derived from the formula MgCl2 • pROH. By mixing the alcohol and magnesium chloride under stirred conditions at the melting temperature of the adduct (100°–130°C), a spherical adduct can be suitably prepared. The adduct is then mixed with an inert hydrocarbon immiscible with the adduct to produce an emulsion, which is rapidly quenched, resulting in the solidification of the adduct in the form of spherical particles. Examples of spherical adducts prepared according to this procedure are described in USP 4,399,054 and US 4,469,648. The adduct thus obtained can react directly with the Ti compound, or it can be pre-treated with thermally controlled alcoholization (80°–130°C) to obtain an adduct in which the molar number of alcohol is typically less than 3, preferably between 0.1 and 2.5. The reaction with the Ti compound can be carried out by suspending the adduct (alcoholized or as is) in cold TiCl4; the mixture is then heated to 80°C to 130°C and held at that temperature for 0.5 to 2 hours. The treatment with TiCl4 can be performed once or multiple times. Electron donor compounds can be added in desired proportions during the TiCl4 treatment.

[0067] The alkyl-Al compound (ii) is preferably selected from trialkylaluminum compounds, such as, for example, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, and tri-n-octylaluminum. Alkylaluminum halides, alkylaluminum hydrides, or alkylaluminum sesquichlorides, such as AlEt2Cl and Al2Et3Cl3, may also be used (possibly in the form of mixtures with the above-mentioned trialkylaluminum compounds). The Al / Ti ratio is greater than 1 and the range may preferably be between 50 and 2000.

[0068] Among the external electrons, silicon compounds having the following general formula are preferred: (R 1 )a(R 2 )bSi(OR 3 R(a+b+c) = 4, where a and b are integers from 0 to 2, c is an integer from 1 to 4, and the sum of (a+b+c) is 4; 1 R 2 and R 3 It may optionally contain a heteroatom of an alkyl, cycloalkyl, or aryl radical having 1 to 18 carbon atoms.

[0069] Particularly preferred is silicon compound (iii), where a is 1, b is 1, c is 2, and R... 1 and R 2 At least one of them is selected from branched alkyl, cycloalkyl, or aryl groups having 3 to 10 carbon atoms, optionally containing heteroatoms, and R 3 These are C1-C10 alkyl groups, particularly methyl groups. Examples of such preferred silicon compounds are methylcyclohexyldimethoxysilane (C donor), diphenyldimethoxysilane, methyl-tert-butyldimethoxysilane, dicyclopentyldimethoxysilane (D donor), diisopropyldimethoxysilane, (2-ethylpiperidinyl)tert-butyldimethoxysilane, (2-ethylpiperidinyl)tert-hexyldimethoxysilane, (3,3,3-trifluoro-n-propyl)(2-ethylpiperidinyl)dimethoxysilane, and methyl(3,3,3-trifluoro-n-propyl)dimethoxysilane.

[0070] Preferably, such silicon compounds are used, where a is 0, c is 3, and R... 2 It may optionally contain a branched alkyl or cycloalkyl group with heteroatoms, and R 3 It is methyl. Examples of such preferred silicon compounds are cyclohexyltrimethoxysilane, tert-butyltrimethoxysilane, and tert-hexyltrimethoxysilane.

[0071] The amount of external electron donor compound (iii) is such that the molar ratio between the organoaluminum compound and the external electron donor compound (iii) is 0.1 to 200, preferably 1 to 100, and more preferably 3 to 50.

[0072] All polymerization stages are preferably carried out in the gas phase. The reaction temperature for each polymerization stage is independently selected from values ​​ranging from 40°C to 90°C. The pressure for each polymerization stage ranges independently from 5 to 30 bar. The residence time of the two stages depends on the desired ratio between fractions (a) and (b) and is preferably in the range of 15 minutes to 8 hours. Conventional molecular weight modifiers known in the art, such as chain transfer agents (e.g., hydrogen or ZnEt2), may optionally be used.

[0073] Examples of polymerization processes for preparing polyolefin compositions (I) can be found in WO2020 / 148105, WO2020 / 148106 and WO2020 / 144102, the relevant portions of which are incorporated herein by reference.

[0074] If desired, the polymer obtained at the end of the polymerization reaction may be optionally chemically treated with an organic peroxide to reduce the average molecular weight and increase the melt flow rate to the value required for a particular application.

[0075] Optionally, the polyolefin composition (I) comprises up to and includes 5.0% by weight, more preferably 0.01% to 5.0% by weight, of an additive (d), which is preferably selected from the group consisting of nucleating agents, antioxidants, light stabilizers, slip agents, acid stabilizers, melt stabilizers, pigments, and combinations thereof, wherein the amount of the additive (d) is based on the total weight of the polyolefin composition (I) containing the additive.

[0076] The polyolefin composition (I) has a good balance of thermal conductivity and physical and mechanical properties, and is particularly, but not exclusively, suitable for use in insulation layers for power cables.

[0077] The cable disclosed herein includes at least one electrical conductor, wherein the electrical conductor is at least one metal wire or rod, preferably the electrical conductor is a bundle of wires.

[0078] In a preferred embodiment, the electrical conductor is made of aluminum or copper.

[0079] The cables disclosed herein are preferably power cables that transmit energy at any voltage level, such as at low voltage (LV, below 1kV), medium voltage (MV, 1kV to 35kV), high voltage (HV, above 35kV), or ultra-high voltage (EHV, above 35kV).

[0080] The cable of this disclosure optionally includes one or more semiconductor layers interposed between an electrical conductor and a thermoplastic layer comprising a polyolefin composition (I), the thermoplastic layer being an insulating layer. Preferably, the cable of this disclosure further includes a sheath layer surrounding the insulating layer.

[0081] The cable disclosed herein is manufactured by extruding a thermoplastic layer comprising a polyolefin composition (I) around an electrical conductor or by extruding the thermoplastic layer around a semiconductor layer (if present) surrounding the electrical conductor. Optionally, one or more semiconductor layers and / or sheath layers may be extruded onto the thermoplastic layer comprising the polyolefin composition (I).

[0082] In the cables disclosed herein, the polyolefin composition (I) or the thermoplastic layer composed of the polyolefin composition (I) preferably has a thermal conductivity at 90°C equal to or greater than 220.0 mV / m • K, preferably equal to or greater than 230.0 mV / m • K, and more preferably in the range of 250.0 to 280.0 mV / m • K, wherein the thermal conductivity is measured using the method described in the Examples section.

[0083] On the other hand, this disclosure provides a method for insulating an electrical conductor, the method comprising the following steps:

[0084] (i) Provide an electrical conductor;

[0085] (ii) Provide the polyolefin composition (I) as described above; and

[0086] (iii) The electrical conductor is surrounded by the polyolefin composition (I).

[0087] Preferably, step (i) includes providing at least one metal wire or rod, more preferably a bundle of wires.

[0088] Preferably, the at least one electrical conductor is made of aluminum or copper.

[0089] Preferably, step (iii) is performed by surrounding the electrical conductor with a continuous layer of the polyolefin composition (I). In a preferred embodiment, step (III) includes extruding the polyolefin composition (I) onto the electrical conductor to form an insulating thermoplastic layer comprising or composed of the polyolefin composition (I).

[0090] In another respect, this disclosure provides the use of the polyolefin composition (I) as described above in forming an insulating layer on an electrical conductor.

[0091] In particular, according to this disclosure, a polyolefin composition (I) is used to form an insulating layer on an electrical conductor having a thermal conductivity of 220.0 mV / m • K, preferably equal to or greater than 230.0 mV / m • K, more preferably in the range of 250.0 to 280.0 mV / m • K, wherein the thermal conductivity is measured using the method described in the Examples section.

[0092] Preferably, according to this disclosure, a polyolefin composition (I) is used to form an insulating layer on an electrical conductor, which is one or more metal wires or rods, preferably comprising or composed of aluminum or copper.

[0093] Therefore, in another aspect, this disclosure relates to a method for manufacturing a power cable, the power cable comprising an electrical conductor and an insulating layer, the method comprising:

[0094] (I) Provide electrical conductors;

[0095] (II) Provide the polyolefin composition (I) as described above; and

[0096] (III) The electrical conductor is at least partially surrounded by the polyolefin composition (I).

[0097] The insulating layer has a thermal conductivity of 220.0 mV / m • K at 90°C, preferably equal to or greater than 230.0 mV / m • K, and more preferably in the range of 250.0 to 280.0 mV / m • K, and the thermal conductivity is measured using the method described in the Examples section.

[0098] Step (I) includes providing an electrical conductor, which is preferably one or more metal wires or rods, which preferably comprise or consist of aluminum or copper.

[0099] Preferably, step (III) is performed by completely surrounding the electrical conductor with a continuous layer comprising or composed of a polyolefin composition (I). In a preferred embodiment, step (III) comprises extruding the continuous layer comprising or composed of a polyolefin composition (I) onto the electrical conductor to form an insulating thermoplastic layer comprising or composed of the polyolefin composition (I).

[0100] The features describing the subject matter of this disclosure are not inextricably linked to each other. Therefore, a preferred range of a feature can be combined with more or less preferred ranges of different features, regardless of their level of preference.

[0101] Example

[0102] The following embodiments are given to illustrate the invention and not to limit it.

[0103] Characterization methods: The following methods are used to determine the properties indicated in the specification, claims and examples.

[0104] Melt flow rate: determined according to method ISO 1133-1:2011 (230℃ / 2.16kg).

[0105] Solubility in xylene at 25°C: 2.5 g of polymer sample and 250 ml of xylene were introduced into a glass flask equipped with a refrigerator and a magnetic stirrer. The temperature was raised to 135°C over 30 minutes. The resulting clear solution was kept under reflux and stirred for another 30 minutes. The solution was cooled in two stages. In the first stage, the temperature was lowered to 100°C in air with stirring for 10 to 15 minutes. In the second stage, the flask was transferred to a temperature-controlled water bath at 25°C for 30 minutes. The temperature was lowered to 25°C without stirring for the first 20 minutes and maintained at 25°C with stirring for the next 10 minutes. The resulting solid was filtered through rapid filter paper (e.g., Whatman filter paper grade 4 or 541). 100 ml of the filtered solution (S1) was poured into a pre-weighed aluminum container and heated to 140°C on a hot plate under a nitrogen stream to remove the solvent by evaporation. The container was then kept under vacuum in an oven at 80°C until constant weight was achieved. The amount of polymer soluble in xylene at 25°C was then calculated. XS(I) and XSA values ​​were determined experimentally. The fraction (XSB) of the xylene-soluble component (B) at 25°C can be calculated using the following formula:

[0106] XS = W(A)×(XS A ) + W(B)×(XS B )

[0107] Where W(A) and W(B) are the relative quantities of component (A) and component (B) respectively, and W(A) + W(B) = 1.

[0108] Ethylene content of the propylene-ethylene copolymer determined by NMR: 131H-13C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with a cryopreservation probe, operated at 160.91 MHz in Fourier transform mode at 120 °C. A peak at 29.9 ppm for Sββ carbon (nomenclature according to “Monomer Sequence Distribution in Ethylene-Propylene Rubber by 13C NMR Measurement. 3. Use of Reaction Probability Mode”, CJ Carman, RA Harrington, and CE Wilkes, *Macromolecules*, 1977, 10, 536) was used as an internal reference. The sample was dissolved in 1,1,2,2-tetrachloroethane-d2 at 8% wt / v at 120 °C. Each spectrum was acquired with a 90° pulse, with a 15-second delay between the pulse and the CPD to remove 1H-13C coupling. 512 transients were stored in 32 K data points using a 9000 Hz spectral window. The spectral assignment, triplet state distribution, and compositional assessment were performed according to Kakugo (“Carbon-13 NMR determination of monomer sequence distribution in ethylene-propylene copolymers prepared with δ-titanium trichloride-diethylaluminum chloride”, M. Kakugo, Y. Naito, K. Mizunuma, and T. Miyatake, *Macromolecules*, 1982, 15, 1150) using the following equations:

[0109] PPP = 100 Tββ / S PPE = 100 Tβδ / S EPE = 100 Tδδ / S

[0110] PEP = 100 Sββ / S PEE= 100 Sβδ / S EEE = 100 (0.25 Sγδ+0.5 Sδδ) / S

[0111] S = Tββ + Tβδ + Tδδ + Sββ + Sβδ + 0.25 Sγδ + 0.5 Sδδ

[0112] The molar percentage of ethylene content is evaluated using the following equation:

[0113] E% mol = 100 * [PEP+PEE+EEE]

[0114] The weight percentage of ethylene content is evaluated using the following equation:

[0115]

[0116] Where P% mol is the molar percentage of propylene content, and MW E and MW P These are the molecular weights of ethylene and propylene, respectively.

[0117] The stereoregularity of the propylene sequence is determined by PPP mmT ββ (28.90-29.65ppm) and total T ββ The ratio of (29.80-28.37ppm) is calculated as mm content.

[0118] Density: determined at 23°C according to ISO 1183-1 / A:2019.

[0119] Tensile properties: determined according to ISO 527-1 and ISO 527-2 on 4 mm thick injection-molded T-bars.

[0120] Charpy impact strength: determined according to ISO 179-1:2010 eA on a 4mm thick injection-molded T-bar.

[0121] Preparation of injection molded specimens: Test specimens of 80x10x4mm were obtained according to method ISO 1873-2:2007.

[0122] Vicat softening temperature: ISO 306, A50.

[0123] Heat distortion temperature: ISO 75B-1, ISO 75B-2, 0.45MPa, 48h, unannealed.

[0124] Thermal conductivity: A 75x75x6mm injection molded plate was tested at 90°C using a Hot Disk® TPS 3500 instrument, operated according to ISO / FDIS 22007-2 method. Test conditions: bulk module; sensor 5465 (r=3.189mm); power 15mW; time = 40s.

[0125] Volume resistivity: ASTM D257.

[0126] Dielectric strength: ASTM D149.

[0127] Examples E1 to E3 and Comparative Example CE4

[0128] The following polyolefin compositions were tested:

[0129] PP(1): This polyolefin composition was prepared according to the process reported in Example 1 of WO2020 / 148105A1 and has the following composition:

[0130] - 22% by weight of polymer fraction (a), which comprises propylene homopolymer having a solubility of 4.5% by weight in xylene at 25°C and an MFR (a) of 45 g / 10 min.

[0131] - 34% by weight of polymer fraction (b), which comprises ethylene homopolymer having a solubility of 3.8% by weight in xylene at 25°C; and

[0132] - 44% by weight fraction (c), which comprises an ethylene-propylene-butene terpolymer containing 53% by weight ethylene-derived units and 16% by weight butene-1-derived units.

[0133] The amounts of polymer fraction (a), polymer fraction (b), and polymer fraction (c) are based on the total weight of fractions (a), (b), and (c).

[0134] Based on the total weight of the composition with additives, the composition was added with 0.1% by weight of Irganox 1010 (pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, sold by BASF) and 0.1% by weight of Irgafos 168 (tris(2,4-di-tert-butylphenyl) phosphite, sold by BASF). Characterization is reported in Table 1.

[0135] PP(2): This polyolefin composition was prepared according to the process reported in Example 1 of WO2020 / 148106A1. The polyolefin composition comprises:

[0136] - 22% by weight of polymer fraction (a), which comprises a propylene-ethylene copolymer containing 3.0% by weight of ethylene-derived units, having a solubility of 9.3% by weight in xylene at 25°C and an MFR (a) of 100 g / 10 min.

[0137] - 34% by weight of polymer fraction (b), which comprises ethylene homopolymer having a solubility of approximately 6.8% by weight in xylene at 25°C; and

[0138] - 44% by weight fraction (c), which comprises an ethylene-propylene-butene terpolymer containing 53% by weight ethylene-derived units and 16% by weight butene-1-derived units.

[0139] The amounts of polymer fraction (a), polymer fraction (b), and polymer fraction (c) are based on the total weight of fractions (a), (b), and (c).

[0140] Based on the total weight of the composition with additives, the composition was added with 0.1% by weight of Irganox 1010 (pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, sold by BASF) and 0.1% by weight of Irgafos 168 (tris(2,4-di-tert-butylphenyl) phosphite, sold by BASF). Characterization is reported in Table 1.

[0141] PP(3): This polyolefin composition was prepared according to the process reported in Example 1 of WO2020 / 144102A1. The polyolefin composition comprises:

[0142] - 20% by weight of polymer fraction (a), which comprises propylene homopolymer having a solubility of 4.2% by weight in xylene at 25°C and an MFR (a) of 100 g / 10 min;

[0143] - 34% by weight of polymer fraction (b), which comprises an ethylene-butene copolymer containing 10.5% by weight of butene-1-derived units, having a solubility of approximately 14.2% by weight in xylene at 25°C; and

[0144] - Fraction (c) of 46% by weight, comprising an ethylene-propylene copolymer, which, based on its weight, contains 54% by weight units derived from ethylene and has a solubility of 81% by weight in xylene.

[0145] The amounts of polymer fraction (a), polymer fraction (b), and polymer fraction (c) are based on the total weight of fractions (a), (b), and (c).

[0146] Based on the total weight of the composition with additives, the composition was added with 0.1% by weight of Irganox 1010 (pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, sold by BASF) and 0.1% by weight of Irgafos 168 (tris(2,4-di-tert-butylphenyl) phosphite, sold by BASF). Characterization is reported in Table 1.

[0147] CA7441A: The Hifax CA7441A is sold by LyondellBasell.

[0148] Table 1

[0149]

Claims

1. A cable comprising an electrical conductor and a thermoplastic layer surrounding the electrical conductor, wherein the thermoplastic layer comprises a polyolefin composition (I), the polyolefin composition (I) comprising: - A fraction (a) comprising 10% to 40% by weight, the fraction (a) comprising a propylene homopolymer or copolymer having a weight of up to and including 10.0% comonomer based on fraction (a), the comonomer being selected from ethylene and C4-C10 α-olefins, the fraction (a) having a solubility in xylene at 25°C equal to or less than 15.0% by weight based on fraction (a); - A fraction (b) comprising 20% ​​to 60% by weight, said fraction (b) comprising an ethylene homopolymer or an ethylene copolymer having a comonomer selected from C4-C10 α-olefins, said ethylene copolymer containing at least 75.0% by weight of ethylene-derived units based on fraction (b); and - A fraction (c) comprising 30% to 60% by weight, said fraction (c) comprising an ethylene copolymer having at least one comonomer selected from propylene and C4-C10 α-olefins, said copolymer containing 40.0% to less than 75.0% by weight of ethylene-derived units based on fraction (c). The quantities of grade (a), grade (b), and grade (c) are based on the total weight of grade (a), grade (b), and grade (c).

2. The cable according to claim 1, wherein the polyolefin composition (I) comprises: - 10% to 30% by weight (a). -The 30% to 40% fraction by weight (b), and - 40% to 50% by weight (c).

3. The cable according to any one of the preceding claims, wherein the fraction (a) has a melt flow rate MFR(a) in the range of 10 to 150 g / 10 min, preferably 30 to 120 g / 10 min (ISO 1133-1:2011, 230 °C / 2.16 kg).

4. The cable according to any one of the preceding claims, wherein the fraction (a) comprises a propylene homopolymer having a solubility in xylene equal to or less than 5.0% by weight based on the fraction (a); or a propylene-ethylene copolymer containing 0.5% to 7.0%, preferably 1.0% to 6.0% by weight, and more preferably 1.5% to 4.5% by weight of ethylene-derived units based on the polymer fraction (a), the copolymer having a solubility in xylene equal to or less than 12.0% by weight based on the polymer fraction (a) at 25°C.

5. The cable according to any one of the preceding claims, wherein the polymer fraction (b) comprises an ethylene homopolymer having a solubility in xylene at 25°C equal to or less than 7.0% by weight based on the polymer fraction (b); or an ethylene / butene-1 copolymer containing 0.1% to 20.0%, preferably 5.0% to 15.0% by weight, more preferably 7.0% to 12.0% by weight of butene-1-derived units based on the polymer fraction (b), the copolymer having a solubility in xylene at 25°C equal to or less than 25.0% by weight, preferably equal to or less than 17.0% by weight based on the polymer fraction (b).

6. The cable according to any one of the preceding claims, wherein the polymer fraction (b) has a strength of 940 to 965 kg / m. 3 Density within the range of (ISO 1183-1 / A:2019, at 23°C).

7. The cable according to any one of the preceding claims, wherein the polymer fraction (c) comprises a terpolymer of propylene, ethylene, and butene-1, and the terpolymer contains, based on the weight of the polymer fraction (c): -45.0% to 65.0% by weight, preferably 48.0% to 62.0% by weight, more preferably 50.0% to 57.0% by weight of units derived from ethylene; - 10.0% to 30.0% by weight, preferably 12.0% to 25.0% by weight, more preferably 15.0% to 22.0% by weight of units derived from butene-1; and - Up to 100% propylene-derived units by weight.

8. The cable according to any one of the preceding claims, wherein the polyolefin composition (I) has a melt flow rate (MFR) in the range of 0.5 to 10.0 g / 10 min, preferably 1.0 to 5.0 g / 10 min (ISO 1133-1:2011, 230°C / 2.16 kg).

9. The cable according to any one of the preceding claims, wherein the polyolefin composition (I) has a content equal to or less than 910 kg / m 3 Preferably, the concentration is between 890 and 910 kg / m³. 3 More preferably 895 to 905 kg / m 3 Density within the range (ISO 1183-1 / A:2019, at 23°C).

10. The cable according to any one of the preceding claims, wherein the polyolefin composition (I) further comprises, based on the total weight of the polyolefin composition (I), up to and including at least one additive (d) by weight of 5.0%, preferably from 0.01% to 5.0% by weight, said at least one additive (d) preferably selected from the group consisting of: nucleating agents, antioxidants, light stabilizers, slip agents, acid stabilizers, melt stabilizers, pigments, and combinations thereof.

11. The cable according to any one of the preceding claims, wherein the electrical conductor is at least one metal wire or rod, preferably a bundle of wires.

12. The cable according to any one of the preceding claims, wherein the electrical conductor is made of aluminum or copper.

13. A method for insulating an electrical conductor, the method comprising the following steps: (i) Provide an electrical conductor; (ii) Providing a polyolefin composition (I) according to any one of claims 1 to 10; (iii) The electrical conductor is surrounded by the polyolefin composition (I) as described in any one of claims 1 to 10.

14. The method of claim 13, wherein step (i) comprises providing at least one metal wire or rod, preferably a bundle of wires.

15. The method according to claim 13 or 14, wherein the electrical conductor is made of aluminum or copper.

16. Use of the polyolefin composition (I) as described in any one of claims 1 to 10 in forming an insulating layer on an electrical conductor.

17. The use according to claim 16, wherein the insulating layer has a thermal conductivity of 220.0 mV / m • K, preferably equal to or greater than 230.0 mV / m • K, more preferably in the range of 250.0 to 280.0 mV / m • K, wherein the thermal conductivity is measured using the method described in the Examples section.

18. The use according to claim 16 or 17, wherein the electrical conductor is one or more metal wires or rods, wherein the one or more metal wires or rods preferably comprise or are composed of aluminum or copper.

19. A method for manufacturing a power cable, the power cable comprising an electrical conductor and an insulating layer, the method comprising: (I) Provide electrical conductors; (II) Provide the polyolefin composition (I) as described in any one of claims 1 to 10; as well as (III) The electrical conductor is at least partially shielded by the polyolefin composition (I). The insulating layer has a thermal conductivity of 220.0 mV / m • K at 90°C, preferably equal to or greater than 230.0 mV / m • K, and more preferably in the range of 250.0 to 280.0 mV / m • K, and the thermal conductivity is measured using the method described in the Examples section.

20. The method of claim 19, wherein the electrical conductor is one or more metal wires or rods, wherein the one or more metal wires or rods preferably comprise aluminum or copper or are composed of aluminum or copper.

21. The method according to claim 19 or 20, wherein step (III) comprises extruding the polyolefin composition (I) onto the electrical conductor to form an insulating thermoplastic layer comprising the polyolefin composition (I).

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