Polypropylene composition for cable insulation

Abstract

The invention relates to a cable comprising a polypropylene composition comprising: (A) 80.0 to 99.0% by weight, preferably 82.5 to 97.2% by weight, most preferably 85.0 to 95.0% by weight of a copolymer of propylene and comonomer units selected from ethylene and an alpha-olefin having 4 to 12 carbon atoms, preferably of propylene; the copolymer has comonomer units in a total amount of 10.0 to 16.0 wt%, preferably 11.0 to 15.0 wt%, most preferably 12.0 to 14.0 wt%, based on the total amount of monomer units in the copolymer (A) of propylene; a melt flow rate MFR2 of from 0.5 to 2.5 g / 10 min, preferably from 0.8 to 2.3 g / 10 min, also more preferably from 1.0 to 2.0 g / 10 min, and most preferably from 1.2 to 1.7 g / 10 min; a total amount, based on the total weight of the propylene copolymer (A), of 25.0 to 50.0 wt%, preferably 27.5 to 45.0 wt%, more preferably 30.0 to 42.5 wt%, and most preferably 32.5 to 40.0 wt%, of a xylene cold soluble (XCS) fraction; and (B) 1.0 to 20.0 wt%, preferably 2.5 to 17.5 wt%, most preferably 5.0 to 15.0 wt%, of a copolymer of ethylene and comonomer units selected from alpha-olefins having 4 to 12 carbon atoms, which copolymer can be obtained in the presence of a single active site catalyst and has a density determined according to ISO 1183 of 860 to 930 kg / m3, preferably 865 to 925 kg / m3, most preferably 870 to 920 kg / m3.

Description

Technical Field

[0001] The present invention relates to a cable comprising an insulating layer containing a flexible polypropylene composition. Background Art

[0002] Today, ethylene polymer products are used as insulation and semiconductor shields for low, medium and high voltage cables due to their easy processability and their favorable electrical properties. In addition, in low voltage applications, polyvinyl chloride (PVC) is also commonly used as an insulating material, usually in combination with softeners to achieve the desired softness of the cable. PVC is a thermoplastic and, by incorporating various plasticizers, this PVC can be used over a wide temperature range. For standard PVC, a maximum continuous conductor temperature of 70 °C is normal. At low temperatures, PVC becomes hard and service temperatures below -10 °C should be avoided. At conductor temperatures above 100 °C, the plasticizers migrate out and the material loses its flexibility. However, by adding special plasticizers and stabilizers, PVC materials can be produced for conductor temperatures of 90 to 105 °C. Substantially, however, PVC is mainly used in the 1 kV region because the higher dielectric constant and dissipation factor of the material mean that the losses increase too much at higher voltages, so PVC cables are generally not used above 1 kV. In addition, in order to maintain a high level of flexibility, softeners must be added to the PVC. Insufficient amounts of softeners significantly reduce the low temperature properties of the PVC. From an environmental perspective, these softeners are not always considered to be problem-free, so there is a desire to eliminate them.

[0003] Especially for medium voltage, high voltage and extra high voltage (MV, HV and EHV) cables as well as high voltage direct current (HVDC) cables, the insulating materials currently consist mainly of crosslinked ethylene polymer (XLPE) products. These products have a high operating temperature, a high electrical breakdown strength and good mechanical properties. However, due to their crosslinking, XLPE cannot be recycled by remelting.

[0004] Therefore, attempts have been made to use thermoplastic materials, especially thermoplastic propylene polymers, as insulating materials for medium voltage, high voltage and extra high voltage (MV, HV and EHV) cables as well as high voltage direct current (HVDC) cables. In addition, network owners are increasingly interested in cables that can be recycled by remelting.

[0005] Therefore, there is an increasing interest in polymer compositions based on thermoplastic propylene polymers for insulating layers of medium voltage (MV), high voltage (HV), extra high voltage (EHV) and high voltage direct current (HVDC) cables.

[0006] Therefore, propylene polymers need to exhibit a good balance of properties with respect to flexibility, mechanical properties, impact properties and electrical breakdown strength.

[0007] Accordingly, there is a need in the art for a polypropylene composition that is suitable for use as cable insulation and that exhibits a good balance of properties with respect to flexibility, mechanical properties, impact properties, and electrical breakdown strength when used as cable insulation for MV or HV cables. SUMMARY OF THE INVENTION

[0008] The present invention relates to a cable comprising at least one layer comprising a polypropylene composition, the polypropylene composition comprising

[0009] (A) a copolymer of propylene and comonomer units selected from ethylene and α-olefins having 4 to 12 carbon atoms, in an amount of 80.0 to 99.0% by weight, preferably 82.5 to 97.2% by weight, most preferably 85.0 to 95.0% by weight, based on the total weight of the polypropylene composition, the copolymer having

[0010] a total amount of comonomer units of 10.0 to 16.0% by weight, preferably

[0011] 11.0 to 15.0% by weight, most preferably 12.0 to 14.0% by weight, based on the total amount of monomer units in the propylene-based copolymer (A);

[0012] a melt flow rate MFR2 of 0.5 to 2.5 g / 10 min, preferably 0.8 to 2.3 g / 10 min, still more preferably 1.0 to 2.0 g / 10 min and most preferably 1.2 to 1.7 g / 10 min;

[0013] a xylene cold soluble (XCS) fraction of 25.0 to 50.0% by weight, preferably 27.5 to 45.0% by weight, more preferably 30.0 to 42.5% by weight and most preferably 32.5 to 40.0% by weight, based on the total weight of the propylene-based copolymer (A); and

[0014] (B) a copolymer of ethylene and comonomer units selected from α-olefins having 4 to 12 carbon atoms, in an amount of 1.0 to 20.0% by weight, preferably 2.5 to 17.5% by weight, most preferably 5.0 to 15.0% by weight, based on the total weight of the polypropylene composition, the copolymer being obtainable in the presence of a single-site catalyst and having

[0015] a density of 860 to 930 kg / m 3 , preferably 865 to 925 kg / m 3 , most preferably 870 to 920 kg / m 3 as determined according to ISO

[0016] 1183.

[0017] DEFINITIONS

[0018] Multi-phase polypropylene is a propylene-based copolymer having a semi-crystalline matrix phase and an elastomeric phase dispersed therein, and the semi-crystalline matrix phase may be a propylene homopolymer or a random copolymer of propylene and at least one α-olefin comonomer. The elastomeric phase may be a propylene copolymer having a high comonomer content, and the comonomer is not randomly distributed in the polymer chain, but is distributed in a comonomer-rich block structure and a propylene-rich block structure.

[0019] Multi-phase polypropylene is generally different from single-phase propylene copolymers because it exhibits two different glass transition temperatures Tg attributable to the matrix phase and the elastomeric phase.

[0020] A propylene homopolymer is a polymer consisting essentially of propylene monomer units. Due to impurities, especially during commercial polymerization processes, a propylene homopolymer may contain up to 0.1 mol% of comonomer units, preferably up to 0.05 mol% of comonomer units and most preferably up to 0.01 mol% of comonomer units.

[0021] A propylene random copolymer is a copolymer of propylene monomer units and comonomer units, wherein the comonomer units are randomly distributed on the polypropylene chain. Thus, a propylene random copolymer comprises a fraction (xylene cold insoluble (XCI) fraction) that is insoluble in xylene in an amount of at least 85 wt%, most preferably at least 88 wt%, based on the total amount of the propylene random copolymer. Thus, a propylene random copolymer does not contain an elastomeric polymer phase dispersed therein.

[0022] Generally, a propylene polymer containing at least two propylene polymer fractions (components) is referred to as "multimodal", and the at least two propylene polymer fractions (components) have been produced under different polymerization conditions (resulting in different (weight average) molecular weights and / or different comonomer contents of the fractions), preferably by polymerization in a plurality of polymerization stages having different polymerization conditions. The prefix "multi" relates to the number of different polymer fractions constituting the propylene polymer. As an example of a multimodal propylene polymer, a propylene polymer consisting of only two fractions is referred to as "bimodal", while a propylene polymer consisting of only three fractions is referred to as "trimodal".

[0023] A unimodal propylene polymer consists of only one fraction.

[0024] Thus, the term "different" means that the propylene polymer fractions are different from each other in at least one property, preferably in the weight average molecular weight (which can also be measured at different melt flow rates of the fractions) or the comonomer content or both.

[0025] An elastomer is a polymer having viscoelasticity and weak intermolecular forces. The term "elastomer" can be used interchangeably with "rubber".

[0026] Polyolefin-based elastomers (such as polyethylene-based elastomers, i.e., elastomers having a molar majority of olefin monomer units (such as ethylene monomer units)) are generally thermoplastic elastomers.

[0027] Thermoplastic elastomers have both thermoplastic and elastomeric properties.

[0028] Polyolefin-based elastomers (such as polyethylene-based elastomers) generally exhibit low density and low viscosity. They can be ethylene-α-olefin copolymers, such as ethylene-propylene copolymers, ethylene-1-butene copolymers, or ethylene-1-octene copolymers. A specific class of polyethylene-based elastomers are ethylene-α-olefin copolymers (such as ethylene-propylene copolymers, ethylene-1-butene copolymers, or ethylene-1-octene copolymers), which are generally polymerized in a solution polymerization process in the presence of a single-site catalyst.

[0029] Waxes are organic compounds composed of long aliphatic alkyl chains, which generally have a melting temperature Tm of at least 40 °C and melt into a low-viscosity liquid at a temperature above their melting temperature.

[0030] Polyethylene waxes are resins composed of a molar majority of ethylene monomer units with a relatively low weight-average molecular weight Mw of not more than 20,000 g / mol.

[0031] Visbreaking is a post-reactor chemical process for modifying semi-crystalline polymers (such as propylene polymers). During the visbreaking process, the propylene polymer backbone is degraded, for example, by β-scission with the aid of peroxides (such as organic peroxides). The degradation is generally used to increase the melt flow rate and narrow the molecular weight distribution.

[0032] Hereinafter, unless otherwise specified, amounts are given in % by weight (wt%). Detailed Description

[0033] Polypropylene composition

[0034] The polypropylene composition in at least one layer of the cable of the present invention comprises

[0035] (A) A copolymer of propylene and comonomer units selected from ethylene and α-olefins having 4 to 12 carbon atoms, which is 80.0 to 99.0 wt%, preferably 82.5 to 97.2 wt%, most preferably 85.0 to 95.0 wt% based on the total weight of the polypropylene composition, and the copolymer has

[0036] The total amount of monomer units in the propylene-based copolymer (A) is 10.0 to 16.0 wt%, preferably

[0037] 11.0 to 15.0% by weight, most preferably 12.0 to 14.0% by weight of comonomer units;

[0038] A melt flow rate MFR2 of 0.5 to 2.5 g / 10 min, preferably 0.8 to 2.3 g / 10 min, still more preferably 1.0 to 2.0 g / 10 min and most preferably 1.2 to 1.7 g / 10 min;

[0039] A xylene cold soluble (XCS) fraction of 25.0 to 50.0% by weight, preferably 27.5 to 45.0% by weight, more preferably 30.0 to 42.5% by weight and most preferably 32.5 to 40.0% by weight, based on the total weight of the propylene-based copolymer (A); and

[0040] (B) A copolymer of ethylene and comonomer units selected from α-olefins having 4 to 12 carbon atoms, in an amount of 1.0 to 20.0% by weight, preferably 2.5 to 17.5% by weight, most preferably 5.0 to 15.0% by weight, based on the total weight of the polypropylene composition, which copolymer can be obtained in the presence of a single-site catalyst and has

[0041] 860 to 930 kg / m 3 , preferably 865 to 925 kg / m 3 , most preferably 870 to 920 kg / m 3 and a density determined according to ISO

[0042] 1183.

[0043] The polypropylene composition preferably comprises 80.0 to 99.0% by weight, preferably 82.5 to 97.2% by weight, most preferably 85.0 to 95.0% by weight of a copolymer (A) of propylene and comonomer units selected from ethylene and α-olefins having 4 to 12 carbon atoms and 1.0 to 20.0% by weight, preferably 2.5 to 17.5% by weight, most preferably 5.0 to 15.0% by weight of a copolymer (B) of ethylene and comonomer units selected from α-olefins having 4 to 12 carbon atoms, all amounts being based on the total weight of the polypropylene composition.

[0044] Based on the total weight of the polypropylene composition, the polypropylene composition may further comprise a polymer component different from components (A) and (B) in an amount of preferably 0.0 to 10.0% by weight.

[0045] In a preferred embodiment, the polymer component of the polypropylene composition consists of components (A) and (B).

[0046] In addition to these polymer components, the polypropylene composition may further comprise one or more additives in an amount of 0.0 to 5.0 wt% based on the total weight of the polypropylene composition. The one or more additives are preferably selected from acid scavengers, antioxidants, α-nucleating agents, β-nucleating agents, etc. Such additives are commercially available and are described, for example, in "Plastic Additives Handbook" by Hans Zweifel, 6th Edition 2009 (pages 1141 to 1190).

[0047] Typically, for each single component, these additives are added in an amount of 1 to 50000 ppm.

[0048] The one or more additives can be added to the polymer components during the blending step.

[0049] Thus, the one or more additives can be added to the polymer components in the form of a masterbatch, in which the one or more additives are blended with a carrier polymer in a concentrated amount. Any optional carrier polymer is calculated as part of the amount of the additives based on the total amount of the propylene copolymer composition.

[0050] Based on the total amount of monomer units in the polypropylene composition, the polypropylene composition preferably has a total amount of units derived from ethylene of 12.5 to 35.0 wt%, more preferably 15.0 to 32.5 wt% and most preferably 17.5 to 30.0 wt%.

[0051] Furthermore, based on the total amount of monomer units in the polypropylene composition, the polypropylene composition preferably has a total amount of units derived from propylene of 70.0 to 87.5 wt%, more preferably 72.5 to 85.0 wt% and most preferably 75.0 to 82.5 wt%.

[0052] In addition, based on the total amount of monomer units in the polypropylene composition, the polypropylene composition preferably has a total amount of units derived from α-olefins having 4 to 12 carbon atoms of 0.1 to 10.0 wt%, more preferably 0.2 to 7.5 wt% and most preferably 0.3 to 5.0 wt%.

[0053] The units derived from α-olefins having 4 to 12 carbon atoms are preferably selected from 1-butene, 1-hexene or 1-octene. The polypropylene composition may comprise one type of units derived from α-olefins having 4 to 12 carbon atoms, or two or more types, such as two types of units derived from α-olefins having 4 to 12 carbon atoms. It is preferred that the polypropylene composition comprises one type of units derived from α-olefins having 4 to 12 carbon atoms. Particularly preferred are 1-butene or 1-octene.

[0054] Based on the total weight of the polypropylene composition, the polypropylene composition preferably has a xylene cold soluble (XCS) fraction in an amount of from 30.0 to 55.0% by weight, more preferably from 32.5 to 52.5% by weight, still more preferably from 34.0 to 50.0% by weight and most preferably from 36.0 to 47.5% by weight.

[0055] Based on the total amount of monomer units in the xylene cold soluble (XCS) fraction, the xylene cold soluble (XCS) fraction preferably has units derived from ethylene in an amount of from 25.0 to 47.5% by weight, more preferably from 27.5 to 45.0% by weight and most preferably from 30.0 to 42.5% by weight.

[0056] Furthermore, based on the total amount of monomer units in the xylene cold soluble (XCS) fraction, the xylene cold soluble (XCS) fraction preferably has units derived from propylene in an amount of from 47.5 to 75.0% by weight, more preferably from 50.0 to 72.5% by weight and most preferably from 52.5 to 70.0% by weight.

[0057] In addition, based on the total amount of monomer units in the xylene cold soluble (XCS) fraction, the xylene cold soluble (XCS) fraction preferably has units derived from α-olefins having 4 to 12 carbon atoms in an amount of from 0.1 to 12.5% by weight, more preferably from 0.2 to 10.0% by weight and most preferably from 0.3 to 7.5% by weight.

[0058] The units derived from α-olefins having 4 to 12 carbon atoms are preferably selected from 1-butene, 1-hexene or 1-octene. The polypropylene composition may contain one type of units derived from α-olefins having 4 to 12 carbon atoms, or two or more types, such as two types of units derived from α-olefins having 4 to 12 carbon atoms. Preferably, the polypropylene composition contains one type of units derived from α-olefins having 4 to 12 carbon atoms. Particularly preferred is 1-butene or 1-octene.

[0059] Furthermore, the xylene cold soluble (XCS) fraction preferably has an intrinsic viscosity measured in decalin of from 150 to 300 cm 3 / g, preferably from 175 to 275 cm 3 / g and most preferably from 200 to 250 cm 3 / g.

[0060] In addition, the xylene cold soluble (XCS) fraction preferably has a weight average molecular weight Mw of from 150,000 to 300,000 g / mol, more preferably from 175,000 to 275,000 g / mol and most preferably from 200,000 to 250,000 g / mol.

[0061] In addition, the xylene cold soluble (XCS) fraction preferably has a polydispersity index of from 4.5 to 13.0, preferably from 4.7 to 12.5 and most preferably from 5.0 to 12.0, which is the ratio of the weight average molecular weight to the number average molecular weight Mw / Mn.

[0062] Furthermore, based on the total weight of the polypropylene composition, the polypropylene composition preferably has a fraction insoluble in cold xylene (XCI) in an amount of from 45.0 to 70.0% by weight, more preferably from 47.5 to 67.5% by weight, still more preferably from 50.0 to 66.0% by weight and most preferably from 52.5 to 64.0% by weight.

[0063] In the polypropylene composition, the xylene cold soluble (XCS) fraction and the fraction insoluble in cold xylene (XCI) together amount to 100% by weight of the polypropylene composition.

[0064] Based on the total amount of monomer units in the fraction insoluble in cold xylene (XCI), the fraction insoluble in cold xylene (XCI) preferably has units derived from ethylene in an amount of from 3.5 to 20.0% by weight, more preferably from 5.0 to 17.5% by weight and most preferably from 6.0 to 15.0% by weight.

[0065] Furthermore, based on the total amount of monomer units in the fraction insoluble in cold xylene (XCI), the fraction insoluble in cold xylene (XCI) preferably has units derived from propylene in an amount of from 80.0 to 96.5% by weight, more preferably from 82.0 to 95.0% by weight and most preferably from 84.0 to 94.0% by weight.

[0066] In addition, based on the total amount of monomer units in the fraction insoluble in cold xylene (XCI), the fraction insoluble in cold xylene (XCI) preferably has units derived from α-olefins having 4 to 12 carbon atoms in an amount of from 0 to 2.5% by weight, more preferably from 0 to 2.0% by weight and most preferably from 0 to 1.5% by weight.

[0067] The units derived from α-olefins having 4 to 12 carbon atoms are preferably selected from 1-butene, 1-hexene or 1-octene. The polypropylene composition may contain one type of units derived from α-olefins having 4 to 12 carbon atoms, or two or more types, such as two types of units derived from α-olefins having 4 to 12 carbon atoms. It is preferred that the polypropylene composition contains one type of units derived from α-olefins having 4 to 12 carbon atoms. Particularly preferred is 1-butene or 1-octene.

[0068] Furthermore, the fraction insoluble in cold xylene (XCI) preferably has 175 to 350 cm 3 / g, preferably 200 to 325 cm3 / g and most preferably 225 to 300 cm 3 / g of intrinsic viscosity measured in decalin.

[0069] Furthermore, the fraction insoluble in cold xylene (XCI) preferably has a weight average molecular weight Mw of 250,000 to 400,000 g / mol, more preferably 275,000 to 375,000 g / mol and most preferably 300,000 to 350,000 g / mol.

[0070] Furthermore, the fraction insoluble in cold xylene (XCI) preferably has a polydispersity index of 4.0 to 10.0, preferably 4.7 to 9.0 and most preferably 5.0 to 8.5, which is the ratio of the weight average molecular weight to the number average molecular weight Mw / Mn.

[0071] The ratio of the intrinsic viscosity of the XCI fraction to the XCS fraction of the polypropylene composition is preferably in the range of 0.9 to 1.7, more preferably in the range of 1.0 to 1.5 and most preferably in the range of 1.0 to 1.4.

[0072] The polypropylene composition preferably has a melt flow rate MFR2 of 0.5 to 7.5 g / 10 min, more preferably 0.8 to 7.0 g / 10 min, still more preferably 1.0 to 6.5 g / 10 min and most preferably 1.2 to 6.0 g / 10 min.

[0073] The polypropylene composition preferably has a flexural modulus of 150 MPa to 350 MPa, more preferably 175 MPa to 335 MPa and most preferably 200 MPa to 315 MPa.

[0074] Preferably, the polypropylene composition has 50 to 110 kJ / m 2 , more preferably 60 to 100 kJ / m 2 and most preferably 65 to 95 kJ / m 2 of the Charpy notched impact strength at 23 °C.

[0075] Furthermore, the polypropylene composition preferably has 3.5 to 25.0 kJ / m 2 , more preferably 4.0 to 20.0 kJ / m 2 and most preferably 4.5 to 15.0 kJ / m 2 of the Charpy notched impact strength at -20 °C.

[0076] Furthermore, the polypropylene composition has a melting temperature Tm of 140 to 159 °C, preferably 143 to 157 °C and most preferably 145 to 153 °C.

[0077] Furthermore, the polypropylene composition preferably has a crystallization temperature Tc of 85 to 130 °C, more preferably 87 to 128 °C and most preferably 90 to 125 °C.

[0078] The difference between the melting temperature and the crystallization temperature Tm-Tc is preferably in the range of 20 to 65 °C, preferably in the range of 25 to 60 °C and most preferably in the range of 27 to 55 °C.

[0079] The polypropylene composition preferably has at least two glass transition temperatures. The two glass transition temperatures can be attributed to the matrix phase (Tg (matrix)) and the elastomeric phase (Tg (EP)).

[0080] Furthermore, the polypropylene composition has a glass transition temperature Tg (matrix) attributed to the matrix phase, preferably in the range of -1.0 to -15.0 °C, preferably in the range of -2.5 to -12.5 °C and most preferably in the range of -5.0 to -11.0 °C.

[0081] Still further, the polypropylene composition preferably has a glass transition temperature Tg (EP) attributed to the elastomeric phase of -40.0 to -55.0 °C, preferably -42.5 to -52.5 °C and most preferably -45.0 to -50.0 °C.

[0082] Preferably, the polypropylene composition has a shear thinning index SHI of 2.5 to 20.0, more preferably 5.0 to 17.5 and most preferably 7.5 to 15.0 1 / 100 。

[0083] Furthermore, the polypropylene composition preferably has 1.0 to 4.5 s -1 more preferably 1.5 to 4.0 s -1 and most preferably 2.0 to 3.5 s -1 of the polydispersity index PI.

[0084] Preferably, the polypropylene composition is prepared by melt blending components (A) and (B), optional additional polymer components and optional other additives, all as described above or below.

[0085] The polypropylene composition preferably does not undergo visbreaking.

[0086] Preferably, the polypropylene composition does not contain a dielectric fluid such as that described in EP 2 739 679, i.e., it does not contain this dielectric fluid.

[0087] Hereinafter, a copolymer (A) of propylene and a comonomer unit selected from ethylene and an α-olefin having 4 to 12 carbon atoms (abbreviated as "copolymer (A) of propylene" or component (A)) and a copolymer (B) of ethylene and a comonomer unit selected from an α-olefin having 4 to 12 carbon atoms (abbreviated as "copolymer (B) of ethylene" or component (B)) are described in more detail.

[0088] Copolymer (A) of propylene

[0089] The polypropylene composition contains a copolymer (A) of propylene and a comonomer unit selected from ethylene and an α-olefin having 4 to 12 carbon atoms (hereinafter referred to as "copolymer (A) of propylene").

[0090] The comonomer units are selected from ethylene and an α-olefin having 4 to 12 carbon atoms, such as ethylene, 1-butene, 1-hexene or 1-octene. The copolymer (A) of propylene may contain one type of comonomer unit or two or more types, for example, two types of comonomer units. Preferably, the copolymer (A) of propylene contains one type of comonomer unit. Particularly preferably, it is ethylene.

[0091] Based on the total amount of monomer units in the copolymer (A) of propylene, the copolymer (A) of propylene preferably has comonomer units in a total amount of 10.0 to 16.0% by weight, preferably 11.0 to 15.0% by weight, and most preferably 12.0 to 14.0% by weight, preferably ethylene.

[0092] Preferably, the copolymer (A) of propylene is a multiphase copolymer of propylene.

[0093] The multiphase propylene copolymer has a matrix phase and an elastomeric phase dispersed in the matrix phase.

[0094] The matrix phase is preferably an atactic copolymer of propylene.

[0095] The comonomer units of the atactic copolymer of propylene in the matrix phase are generally the same as those of the copolymer of propylene described above. The comonomer units are preferably selected from ethylene and an α-olefin having 4 to 12 carbon atoms, such as ethylene, 1-butene, 1-hexene or 1-octene. The atactic copolymer of propylene in the matrix phase may contain one type of comonomer unit or two or more types, such as two types of comonomer units. Preferably, the atactic copolymer of propylene in the matrix phase contains one type of comonomer unit. Particularly preferably, it is ethylene.

[0096] A typical characteristic of the multiphase propylene copolymer is that it includes at least two glass transition temperatures. The two glass transition temperatures can be attributed to the matrix phase (Tg (matrix)) and the elastomeric phase (Tg (EPR)).

[0097] The multiphase propylene copolymer preferably has a glass transition temperature Tg(matrix) attributable to the matrix phase in the range of -1.0 to -15.0 °C, preferably in the range of -2.5 to -12.5 °C, and most preferably in the range of -5.0 to -10.0 °C.

[0098] Furthermore, the multiphase propylene copolymer preferably has a glass transition temperature Tg(EPR) attributable to the elastomeric phase in the range of -40.0 °C to -55.0 °C, preferably in the range of -42.5 °C to -52.5 °C, and most preferably in the range of -45.0 °C to -50.0 °C.

[0099] In the copolymer (A) of propylene (such as a multiphase propylene copolymer), the matrix phase and the elastomeric phase generally cannot be precisely separated from each other. To characterize the matrix phase and the elastomeric phase of the multiphase propylene copolymer, several methods are known. One method is to extract the fraction containing most of the elastomeric phase with xylene, thereby separating the xylene cold-insoluble (XCI) fraction from the xylene cold-soluble (XCS) fraction. The XCS fraction contains most of the elastomeric phase and only a small part of the matrix phase, while the XCI fraction contains most of the matrix phase and only a small part of the elastomeric phase.

[0100] Based on the total weight of the propylene copolymer (A), the propylene copolymer (A) preferably has a total amount of xylene cold-soluble (XCS) fraction of 25.0 to 50.0 wt%, more preferably 27.5 to 45.0 wt%, still more preferably 30.0 to 42.5 wt%, and most preferably 32.5 to 40.0 wt%.

[0101] Based on the total amount of monomer units in the xylene cold-soluble (XCS) fraction, the xylene cold-soluble (XCS) fraction preferably has a copolymer monomer unit content of 23.0 to 35.0 wt%, more preferably 23.5 to 32.5 wt%, and most preferably 24.0 wt% to 30.0 wt%, preferably ethylene.

[0102] Furthermore, the xylene cold-soluble (XCS) fraction preferably has an intrinsic viscosity measured in decalin of 150 to 350 cm 3 / g, preferably 200 to 325 cm 3 / g, and most preferably 225 to 300 cm3 / g.

[0103] In addition, the xylene cold-soluble (XCS) fraction preferably has a weight-average molecular weight Mw of 185,000 to 350,000 g / mol, more preferably 200,000 to 325,000 g / mol, and most preferably 210,000 to 315,000 g / mol.

[0104] Furthermore, the xylene cold soluble (XCS) fraction preferably has a polydispersity index of from 3.5 to 8.5, preferably from 3.7 to 8.0 and most preferably from 4.0 to 7.5, which is the ratio of the weight average molecular weight to the number average molecular weight Mw / Mn.

[0105] Furthermore, based on the total weight of the propylene-based copolymer (A), the propylene-based copolymer (A) preferably has a fraction insoluble in cold xylene (XCI) in a total amount of from 50.0 to 75.0% by weight, more preferably from 55.0 to 72.5% by weight, still more preferably from 57.5 to 70.0% by weight and most preferably from 60.0 to 67.5% by weight.

[0106] Based on the total amount of monomer units in the fraction insoluble in cold xylene (XCI), the fraction insoluble in cold xylene (XCI) preferably has a comonomer unit content of from 3.0 to 9.0% by weight, preferably from 4.0 to 8.5% by weight and most preferably from 4.5 to 7.5% by weight, preferably ethylene.

[0107] Furthermore, the fraction insoluble in cold xylene (XCI) preferably has an intrinsic viscosity measured in decalin of from 185 to 350 cm 3 / g, preferably from 220 to 325 cm 3 / g and most preferably from 210 to 300 cm 3 / g.

[0108] Furthermore, the fraction insoluble in cold xylene (XCI) preferably has a weight average molecular weight Mw of from 225,000 to 450,000 g / mol, more preferably from 240,000 to 425,000 g / mol and most preferably from 260,000 to 400,000 g / mol.

[0109] Furthermore, the fraction insoluble in cold xylene (XCI) preferably has a polydispersity index of from 3.5 to 7.5, preferably from 3.7 to 7.0 and most preferably from 4.0 to 6.5, which is the ratio of the weight average molecular weight to the number average molecular weight Mw / Mn.

[0110] The ratio of the intrinsic viscosity of the XCI fraction to the XCS fraction of the propylene-based copolymer is preferably in the range of from 0.9 to 1.5, more preferably in the range of from 1.0 to 1.4 and most preferably in the range of from 1.0 to 1.3.

[0111] The propylene-based copolymer (A) preferably has a melt flow rate MFR2 of from 0.5 to 2.5 g / 10 min, preferably from 0.8 to 2.3 g / 10 min, still more preferably from 1.0 to 2.0 g / 10 min and most preferably from 1.2 to 1.7 g / 10 min.

[0112] The copolymer (A) of propylene preferably has a flexural modulus of from 130 MPa to 400 MPa, more preferably from 150 MPa to 390 MPa and most preferably from 175 MPa to 380 MPa.

[0113] Preferably, the copolymer (A) of propylene has from 50 to 110 kJ / m 2 , more preferably from 65 to 100 kJ / m 2 and most preferably from 75 to 95 kJ / m 2 of the notched Izod impact strength at 23 °C.

[0114] Furthermore, the copolymer (A) of propylene preferably has from 5.0 to 10.0 kJ / m 2 , more preferably from 5.5 to 9.0 kJ / m 2 and most preferably from 6.0 to 8.0 kJ / m 2 of the notched Izod impact strength at -20 °C.

[0115] Furthermore, the copolymer (A) of propylene has a melting temperature Tm of from 140 to 159 °C, preferably from 143 to 157 °C and most preferably from 145 to 153 °C.

[0116] In addition, the copolymer (A) of propylene has a crystallization temperature Tc of from 85 to 130 °C, preferably from 87 to 128 °C and most preferably from 90 to 125 °C.

[0117] The difference between the melting temperature and the crystallization temperature Tm - Tc is preferably in the range of from 20 to 65 °C, preferably in the range of from 25 to 60 °C and most preferably in the range of from 27 to 55 °C.

[0118] Preferably, the copolymer (A) of propylene has from 185 to 350 cm 3 / g, preferably from 200 to 325 cm 3 / g and most preferably from 210 to 300 cm 3 / g of the intrinsic viscosity measured in decalin.

[0119] The copolymer (A) of propylene can be polymerized in a sequential multi-stage polymerization process, i.e. in a polymerization process in which two or more polymerization reactors are connected in series. Preferably, in the sequential multi-stage polymerization process, two or more, more preferably three or more, such as three or four polymerization reactors are connected in series. The term "polymerization reactor" shall indicate where the main polymerization takes place. Thus, in the case where the process consists of four polymerization reactors, this definition does not exclude the option that the whole process includes a pre-polymerization step in a pre-polymerization reactor, for example.

[0120] When the copolymer (A) of propylene is a multiphase propylene copolymer, the matrix phase of the multiphase propylene copolymer is polymerized in a first polymerization reactor to produce a unimodal matrix phase, or in the first and second polymerization reactors to produce a multimodal matrix phase.

[0121] The elastomeric phase of the multiphase propylene copolymer is preferably polymerized in one or two subsequent polymerization reactors in the presence of the matrix phase to produce a unimodal elastomeric phase or a multimodal elastomeric phase.

[0122] Preferably, the polymerization reactor is selected from slurry-phase reactors such as loop reactors and / or gas-phase reactors such as fluidized-bed reactors, more preferably selected from loop reactors and fluidized-bed reactors.

[0123] A preferred sequential multistage polymerization process is the "loop-gas phase" process, such as that developed by Borealis A / S of Denmark (known as technology), as described in, for example, patent documents such as EP 0 887 379, WO 92 / 12182, WO2004 / 000899, WO 2004 / 111095, WO 99 / 24478, WO 99 / 24479 or WO 00 / 68315.

[0124] Another suitable slurry-gas phase process is that of LyondellBasell's process.

[0125] Suitable sequential polymerization processes for polymerizing the copolymer (A) of propylene, preferably a multiphase propylene copolymer, are disclosed, for example, in EP 1 681 315A1 or WO 2013 / 092620 A1.

[0126] The copolymer (A) of propylene, preferably a multiphase propylene copolymer, can be polymerized in the presence of a Ziegler-Natta catalyst or a single-site catalyst.

[0127] Suitable Ziegler-Natta catalysts are disclosed, for example, in US 5,234,879, WO 92 / 19653, WO 92 / 19658, WO 99 / 33843, WO 03 / 000754, WO 03 / 000757, WO 2013 / 092620 A1 or WO 2015 / 091839.

[0128] Suitable single-site catalysts are disclosed, for example, in WO 2006 / 097497, WO 2011 / 076780 or WO2013 / 007650.

[0129] The copolymer (A) of propylene is preferably not subjected to a visbreaking step as described, for example, in WO 2013 / 092620 A1.

[0130] Multiphase propylene copolymer resins suitable as the copolymer (A) of propylene are also commercially available. These resins usually already have a stabilizer package added. Therefore, when using a commercially available resin as the copolymer of propylene, the addition of the additives described above may have to be adjusted for the additives already present.

[0131] Copolymer (B) of ethylene

[0132] The polypropylene composition comprises a copolymer (B) of ethylene.

[0133] The comonomer units are selected from α-olefins having 4 to 12 carbon atoms, such as 1-butene, 1-hexene or 1-octene. The copolymer (B) of ethylene may contain one type of comonomer unit or two or more types, such as two types of comonomer units. Preferably, the copolymer (B) of ethylene contains one type of comonomer unit. Particularly preferred is 1-butene or 1-octene.

[0134] Preferably, the copolymer (B) of ethylene is a copolymer of ethylene and 1-octene or a copolymer of ethylene and 1-butene.

[0135] The copolymer (B) of ethylene has a density of 860 to 930 kg / m 3 , preferably 865 to 925 kg / m 3 , most preferably 870 to 920 kg / m 3 of the density.

[0136] Furthermore, the copolymer (B) of ethylene has a crystallinity of 10.0 to 65.0%, preferably 12.5 to 62.5%, most preferably 15.0 to 60.0%.

[0137] A low crystallinity of not more than 65.0% by weight indicates that the copolymer (B) of ethylene includes a considerable amount of irregular structures upon freezing, indicating a large amount of amorphous structures and elastomeric properties.

[0138] The crystallinity can be determined by density measurement, calorimetry, X-ray diffraction IR spectroscopy or NMR spectroscopy as known in the art.

[0139] Still further, the copolymer (B) of ethylene preferably has a melting temperature Tm of 40 to 110 °C, more preferably 42 to 107 °C, most preferably 45 to 105 °C.

[0140] The copolymer (B) of ethylene is polymerized in the presence of a single-site catalyst.

[0141] A suitable polymerization method is a solution polymerization method.

[0142] The copolymer (B) of ethylene is preferably an ethylene copolymer elastomer or an ethylene copolymer wax.

[0143] Ethylene copolymer resins suitable as the copolymer (B) of ethylene are also commercially available. These resins usually already have a stabilizer package added. Therefore, when using a commercially available resin as the copolymer (B) of ethylene, the addition of the additives described above may have to be adjusted according to the additives already present.

[0144] In one embodiment, the copolymer (B) of ethylene is an ethylene copolymer elastomer.

[0145] Preferably, the ethylene copolymer elastomer is a copolymer of ethylene and 1-octene.

[0146] Preferably, the ethylene copolymer elastomer (preferably a copolymer of ethylene and 1-octene) has a crystallinity of 10.0 to 40.0%, preferably 12.5 to 35.0%, more preferably 15.0 to 30.0%.

[0147] The ethylene copolymer elastomer (preferably a copolymer of ethylene and 1-octene) preferably has a density of 860 to 895 kg / m 3 , more preferably 865 to 890 kg / m 3 , most preferably 870 to 885 kg / m 3 of density.

[0148] Furthermore, the ethylene copolymer elastomer (preferably a copolymer of ethylene and 1-octene) preferably has a melt flow rate MFR2 (190 °C, 2.16 kg) of 1.0 to 50.0 g / 10 min, preferably 2.5 to 40 g / 10 min, most preferably 5.0 to 35 g / 10 min.

[0149] Still further, the ethylene copolymer elastomer (preferably a copolymer of ethylene and 1-octene) preferably has a glass transition temperature Tg of -60 to -40 °C, preferably -57 to -42 °C, most preferably -55 to -45 °C.

[0150] In addition, the ethylene copolymer elastomer (preferably a copolymer of ethylene and 1-octene) preferably has a melting temperature Tm of 40 to 85 °C, preferably 42 to 82 °C, most preferably 45 to 80 °C.

[0151] In addition, the ethylene copolymer elastomer (preferably a copolymer of ethylene and 1-octene) preferably has a flexural modulus of 1 to 50 MPa, preferably 3 to 40 MPa, most preferably 5 to 30 MPa.

[0152] The ethylene copolymer elastomer as the copolymer (B) of ethylene is usually polymerized in the presence of a single-site catalyst.

[0153] Such ethylene copolymer elastomers may be commercially available. Suitable examples are, for example, those distributed by Borealis AG under the trade name "Queo", such as, for example, Queo 8230 or Queo 7007LA.

[0154] In the case of commercially available ethylene copolymer elastomers, the properties described above can be measured using common measurement methods or verified through technical documents provided by the supplier.

[0155] In another embodiment, the copolymer (B) of ethylene is a polyethylene wax, such as a polyethylene wax that is a copolymer of ethylene and 1-butene.

[0156] Preferably, the polyethylene wax (preferably the polyethylene wax is a copolymer of ethylene and 1-butene) has a crystallinity of 40.0 to 65.0%, preferably 42.5 to 62.5%, most preferably 45.0 to 60.0%.

[0157] The polyethylene wax (preferably the polyethylene wax is a copolymer of ethylene and 1-butene) preferably has a density of 900 to 930 kg / m 3 , preferably 905 to 925 kg / m 3 , most preferably 910 to 920 kg / m 3 .

[0158] Furthermore, the polyethylene wax (preferably the polyethylene wax is a copolymer of ethylene and 1-butene) preferably has a weight average molecular weight Mw of 1000 to 5000 g / mol, preferably 1500 to 4000 g / mol, most preferably 2000 to 3500 g / mol.

[0159] Still further, the polyethylene wax (preferably the polyethylene wax is a copolymer of ethylene and 1-butene) preferably has a melting temperature Tm of 90 to 110 °C, preferably 92 to 107 °C, most preferably 95 to 105 °C.

[0160] In addition, the polyethylene wax (preferably the polyethylene wax is a copolymer of ethylene and 1-butene) preferably has a melt viscosity at 140 °C of 100 to 500 mPas, preferably 150 to 400 mPas, most preferably 200 to 350 mPas.

[0161] Polyethylene waxes suitable as the copolymer (B) of ethylene are generally polymerized in the presence of a single-site catalyst.

[0162] Such polyethylene waxes may be commercially available. A suitable example is Excerex 30200B from Mitsui Chemicals, Inc.

[0163] In the case of commercially available polyethylene wax, the properties described above can be measured using common measurement methods or verified through technical documents provided by the supplier.

[0164] Cable

[0165] The present invention relates to a cable that includes at least one layer containing a polypropylene composition as defined above or below.

[0166] The cable preferably includes an insulating layer that includes a polypropylene composition as described above or below.

[0167] The cable generally includes at least one conductor and at least one insulating layer that includes a polypropylene composition as described above or below.

[0168] As used herein, the terms "conductor" above and below mean that the conductor includes one or more wires. The wire can be used for any purpose and can be, for example, an optical wire, a telecommunications wire, or an electrical wire. In addition, the cable can include one or more such conductors. Preferably, the conductor is an electrical conductor and includes one or more metal wires. The cable is preferably a power cable. A power cable is defined as a cable that transmits energy and operates at any voltage (usually at a voltage higher than 1 kV). The voltage applied to the power cable can be alternating current (AC), direct current (DC), or transient (pulse). The polypropylene composition of the present invention is very suitable for power cables, especially for power cables operating at voltages from 6 kV to 36 kV (medium voltage (MV) cables) and power cables operating at voltages higher than 36 kV, known as high voltage (HV) cables and extra high voltage (EHV) cables. As is well known, EHV cables operate at very high voltages. These terms have well-known meanings and represent the operating levels of such cables.

[0169] For low-voltage applications, the cable system typically consists of a conductor and an insulating layer containing a polypropylene composition as described above or below, or consists of a conductor, an insulating layer containing a polypropylene composition as described above or below, and an additional sheath layer, or consists of a conductor, a semiconductor layer, and an insulating layer containing a polypropylene composition as described above or below.

[0170] For medium-voltage and high-voltage applications, the cable system typically consists of a conductor, an inner semiconductor layer, an insulating layer containing a polypropylene composition as described above or below, and an outer semiconductor layer optionally covered by an additional sheath layer.

[0171] The semiconductor layer mentioned preferably comprises a thermoplastic polyolefin composition, more preferably consists of a thermoplastic polyolefin composition, preferably a polyethylene composition or a polypropylene composition containing a sufficient amount of electrically conductive solid filler (preferably carbon black). Preferably, the thermoplastic polyolefin composition of one or more semiconductor layers is a polypropylene composition, more preferably a polypropylene composition containing a multiphase propylene copolymer as a polymer component. Particularly preferably, the thermoplastic polyolefin composition of at least one semiconductor layer, preferably two semiconductor layers, of the cable contains the same copolymer of propylene as the insulating layer, i.e., the copolymer of propylene as described above or below.

[0172] A cable including an insulating layer comprising the polypropylene composition as described above exhibits an AC electrical breakdown strength in the form of a Weibull alpha-value and a Weibull beta-value.

[0173] When measured on a 10 kV cable, the cable preferably has a Weibull alpha-value of 35.0 to 65.0 kV / mm, preferably 37.5 to 65.0 kV / mm and most preferably 40.0 to 65.0 kV / mm.

[0174] Furthermore, when measured on a 10 kV cable, the cable preferably has a Weibull beta-value of 5.0 to 250.0, preferably 5.5 to 250.0, most preferably 6.0 to 250.0.

[0175] Therefore, an insulating layer comprising the polypropylene composition as described above or below can be used for medium-voltage and high-voltage cables.

[0176] In yet another aspect, the present invention relates to the use of the polypropylene composition as described above or below as cable insulation for medium-voltage and high-voltage cables.

[0177] The medium-voltage and high-voltage cables preferably meet all the performance requirements described above and below for the cables.

[0178] Advantages of the present invention:

[0179] The polypropylene composition exhibits a good balance of properties with respect to high flexibility, good mechanical strength, good impact properties, and high crystallization and melting temperatures, which allows it to be used as cable insulation, for example, for medium-voltage and high-voltage cables at high operating temperatures. The flexibility and impact properties can be further improved by adding a copolymer (B) of ethylene to the polypropylene composition, while maintaining the high crystallization and melting temperatures.

[0180] The polypropylene composition can be easily compounded to prepare an insulating layer without the need to increase the melt flow rate by visbreaking the composition or the copolymer (A) of propylene.

[0181] Cables comprising an insulating layer containing a polypropylene composition surprisingly exhibit good AC breakdown strength in the form of Weibull α and Weibull β values. Thus, the addition of a copolymer (B) of ethylene to the polypropylene composition further improves the AC breakdown strength as compared to a polypropylene composition containing only a copolymer (A) of propylene as the polymeric compound.

[0182] Good AC breakdown strength in the form of Weibull α and Weibull β values can be obtained without adding a dielectric fluid such as that described in EP 2739679.

[0183] Examples

[0184] Unless otherwise defined, the following definitions of terms and measurement methods apply to the above general description of the invention and the following examples.

[0185] 1. Measurement methods

[0186] a) Melt flow rate (MFR2)

[0187] The melt flow rate is the amount of polymer extruded in 10 minutes at a specific temperature under a specific load by a test device standardized according to ISO 1133 or ASTM D1238, in grams.

[0188] The melt flow rate MFR2 of the propylene-based polymer and the polypropylene composition is measured according to ISO 1133 at 230 °C under a load of 2.16 kg.

[0189] The melt flow rate MFR2 of the ethylene-based polymer and the polyethylene composition is measured according to ISO 1133 at 190 °C under a load of 2.16 kg.

[0190] The melt flow rate can also be measured according to ASTM D 1238.

[0191] b) Density

[0192] The density is measured according to ISO 1183. Sample preparation is carried out by compression molding according to ISO 17855-2.

[0193] The density can also be measured according to ASTM D 792.

[0194] c) Comonomer content

[0195] Method I (HECO)

[0196] Quantification of the comonomer content of poly(propylene-co-ethylene) copolymer

[0197] Recorded in solution using a Bruker Avance NEO 400 NMR spectrometer operating at 400.15 MHz for 1 H and 13 100.62 MHz for 13 C{ 1 H} NMR spectra. Nitrogen was used for all pneumatic devices and all spectra were recorded using a 13 C-optimized 10 mm extended temperature probe at 125 °C. Approximately 200 mg of the material was dissolved in 3 ml of 1,2-tetrachloroethane-d2 (TCE-d2) together with chromium(III) acetylacetonate (Cr(acac)3) and approximately 3 mg of BHT (2,6-di-tert-butyl-4-methylphenol, CAS 128-37-0) to give a 60 mM solution of the relaxant in the solvent {8}. To ensure a homogeneous solution, after initial sample preparation in a heating block, the NMR tube was further heated in a rotary oven for at least 1 hour. After insertion into the magnet, the tube was rotated at 10 Hz. This setting was chosen mainly for high resolution and was required quantitatively due to accurate ethylene content quantification. A standard single-pulse excitation without NOE was employed, using an optimized tip angle, a 1 s recycle delay, and a two-stage WALTZ16 decoupling scheme {3,4}. A total of 6144 (6k) transients were acquired for each spectrum. A dedicated computer program was used to process, integrate, and determine the relevant quantitative properties from the integrals of the 13 C{ 1 H} NMR spectra. Using the chemical shift of the solvent, all chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm. Even if this structural unit is absent, this method allows for comparable referencing. Characteristic signals corresponding to the incorporation of ethylene were observed {7}.

[0198] Using the method of Wang et al. {6}, the comonomer fraction was quantified by integrating multiple signals over the entire spectral region in the 13 C{ 1 H} spectra. This method was chosen because of its robustness and its ability to account for the presence of regio-defects when needed. The integration regions were slightly adjusted to improve applicability over the entire range of comonomer contents encountered.

[0199] For systems where only isolated ethylene in the PPEPP sequence was observed, the method of Wang et al. was modified to reduce the effect of non-zero integrals at sites known to be absent. This method reduces the overestimation of the ethylene content in such systems and was achieved by reducing the number of sites used to determine the absolute ethylene content to the following:

[0200] E = 0.5(Sββ + Sβγ + Sβδ + 0.5(Sαβ + Sαγ))

[0201] By using this set of sites, the corresponding integral equation becomes:

[0202] E = 0.5(I H + I G + 0.5(I C + I D ))

[0203] The same symbols as those used in the article by Wang et al. {6} are used. The equation for the absolute propylene content is not modified.

[0204] Calculate the mole percentage of comonomer incorporation from the mole fraction:

[0205] E [mol%] = 100 * fE

[0206] Calculate the weight percentage of comonomer incorporation from the mole fraction:

[0207] E [wt%] = 100 * (fE * 28.06) / ((fE * 28.06) + ((1 - fE) * 42.08))

[0208] Bibliography:

[0209] 1) Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443.

[0210] 2) Busico, V., Cipullo, R., Monaco, G., Vacatello, M., Segre, A. L., Macromolecules 30 (1997) 6251.

[0211] 3) Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225.

[0212] 4) Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128.

[0213] 5) Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253.

[0214] 6) Wang, W-J., Zhu, S., Macromolecules 33(2000), 1157.

[0215] 7) Cheng, H.N., Macromolecules 17(1984), 1950.

[0216] 8) Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5(2009), 475.

[0217] 9) Kakugo, M., Naito, Y., Mizunuma, K., Miyatake, T. Macromolecules 15(1982)1150.

[0218] 10) Randall, J. Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.

[0219] 11) Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253.

[0220] Method II (Composite material)

[0221] Quantification of the total C2, C3, C4 and C8 contents in the composite material

[0222] Measurement conditions and sample preparation

[0223] Use the Bruker Avance Neo 400 NMR spectrometer operating at 400.15 and 100.62 MHz for 1 H and 13 C respectively to record quantitative 13 C{ 1 H} NMR spectra in solution state. Nitrogen is used for all pneumatic devices and all spectra are used 13C-optimized 10 mm extended temperature probe was recorded at 125 °C. Approximately 200 mg of the material was dissolved in approximately 3 ml of 1,2-tetrachloroethane-d2 (TCE-d2) together with approximately 3 mg of BHT (2,6-di-tert-butyl-4-methylphenol, CAS 128-37-0) and chromium(III) acetylacetonate (Cr(acac)3) to obtain a 60 mM solution of the relaxant in the solvent, as described in G. Singh, A. Kothari, V. Gupta, Polymer Testing 2009, 28(5), 475.

[0224] To ensure a homogeneous solution, after initial sample preparation in a heating block, the NMR tube was further heated in a spinning oven for at least 1 h. After insertion into the magnet, the tube was spun at 10 Hz.

[0225] Standard single-pulse excitation without NOE was employed, using an optimized tip angle, 1 s recycle delay, and double-stage WALTZ16 decoupling scheme, as described in Z. Zhou, R. Kuemmerle, X. Qiu, D. Redwine, R. Cong, A. Taha, D. Baugh, B. Winniford, J. Mag. Reson. 187(2007)225 and V. Busico, P. Carbonniere, R. Cipullo, C. Pellecchia, J. Severn, G. Talarico, Macromol. Rapid Commun. 2007, 28, 1128. A total of 6144 (6k) transients were acquired for each spectrum.

[0226] For quantification 13 C{ 1 H} NMR spectra were processed, integrated, and the relevant quantitative properties were determined from the integrals. Using the chemical shift of the solvent, all chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm. Even if this structural unit is absent, this method allows for comparable referencing.

[0227] Quantification of total C2, C3 and C8

[0228] Characteristic signals corresponding to various incorporations of ethylene were observed, as described in Cheng, H. N., Macromolecules 1984, 17, and A. J. Brandolini, D. D. Hills, “NMR spectra of polymers and polymer additives”, Marcel Deker Inc., 2000.

[0229] As reported in L. Abis, Mackromol. Chem. 187, 1877 - 1886 (1986), a triad method equivalent to the ZN C2C3 copolymer was used to quantify the comonomer fractions, but C8 quantification was introduced and a compensation procedure for overlapping signals was established. To quantify the C8 content, three α - methylene signals at 34.7 ppm were selected and the signal at 22.9 ppm was selected to compensate for the C2C8 chains of the observable saturated end - groups. In terms of the C2 content, the total amount generated only by both the C2C3 and C2C8 blend components can be quantified by using the methylene sequence at 30.0 ppm.

[0230] Assignment table 13 C NMR spectrum

[0231] Chemical shift [ppm] Assignment Label 33.4 EPE(CH) A 31.3-30.7 PPE(CH)+Sgg+BHT B 30.4 Sgd(C2C3, C2C8) C 29.9 Sdd(C2C3, C2C8) D 29.6-28.2 PPP(CH) E 27.8-26.5 Sbd+SbdC2C8 F 25.2-24.3 Sbb G 34.7 Sad C8 H 152 Quaternary carbon (quart C) BHT BHT 22.9 2s J

[0232] Triad equation

[0233] Triad sequence Signal / Equation PEP G PEE F-(H / 3) EEE (D+(J*3)) / 2+C / 4+H / 3 PPP E PPE (B - 6*BHT)-(((F - H / 3)-C) / 2) EPE A EOE H / 3

[0234] After quantifying the molar fractions and normalizing, the amounts of C2, C3, and C8 can be calculated by summing the triads centered on E, P, and O:

[0235] Sum of triads = PEP + PEE + EEE + PPP + PPE + EPE + EOE

[0236] f molar PEP = PEP / sum of triads, molar% PEP = f molar PEP * 100

[0237] f molar PEE = PEE / sum of triads, molar% PEE = f molar PEE * 100

[0238] f molar EEE = EEE / sum of triads, molar% EEE = f molar EEE * 100

[0239] f molar PPP = PPP / sum of triads, molar% PPP = f molar PPP * 100

[0240] f molar PPE = PPE / sum of triads, molar% PPE = f molar PPE * 100

[0241] f molar EPE = EPE / sum of triads, molar% EPE = f molar EPE * 100

[0242] f molar EOE = EOE / sum of triads, molar% EOE = f molar EOE * 100

[0243] C2 [mol%] = mol% PEP + mol% PEE + mol% EEE

[0244] C3 [mol%] = mol% PPP + mol% PPE + mol% EPE

[0245] C8 [mol%] = mol% EOE

[0246] The weight percentages of the comonomers are calculated from the mole percentages in the usual way:

[0247] wt% C2 total = 100 * (C2 [mol%] * 28.06) / ((C2 [mol%] * 28.06) + (C3 [mol%] * 42.08) + C8 [mol%] * 112.24)

[0248] wt% C3 total = 100 * (C3 [mol%] * 42.08) / ((C2 [mol%] * 28.06) + (C3 [mol%] * 42.08) + C8 [mol%] * 112.24)

[0249] wt% C4 total = 100 * (C8 [mol%] * 112.24) / ((C2 [mol%] * 28.06) + (C3 [mol%] * 42.08) + C8 [mol%] * 112.24)

[0250] Quantification of C2, C3 and C4

[0251] Characteristic signals corresponding to the various incorporations of ethylene were observed, as described in Cheng, H.N., Macromolecules 1984, 17, and A.J. Brandolini, D.D. Hills, “NMR Spectra of Polymers and Polymer Additives”, Marcel Deker Inc., 2000.

[0252] As reported by L. Abis, Mackromol. Chem. 187, 1877 - 1886 (1986), a triad method equivalent to that for ZN C2C3 copolymers was used to quantify the comonomer fractions, but C4 quantification was introduced and a compensation procedure for overlapping signals was established. To quantify the C4 content, the branched signal at 39.8 ppm was selected and the signal at 22.9 ppm was selected to compensate for the C2C4 chains of the observable saturated end groups. In terms of the C2 content, the total amount generated only by both the C2C3 and C2C4 blend components can be quantified by using the methylene sequence at 30.0 ppm.

[0253] Assignment Table13 C NMR spectrum

[0254] Chemical shift [ppm] Assignment Label 33.4 EPE(CH) A 31.3-30.7 PPE(CH)+Sgg+BHT B 30.4 Sgd(C2C3, C2C4) C 29.9 Sdd(C2C3, C2C4) D 29.6-28.2 PPP(CH) E 27.8-26.5 Sbd+SbdC2C4 F 25.2-24.3 Sbb G 39.8 EBE H 152 Quaternary carbon BHT BHT 22.9 2s J

[0255] Triad equation

[0256] Triad sequence Signal / Equation PEP G PEE F EEE (D+(J*3)) / 2+C / 4+H PPP E PPE (B - 6*BHT)-((F - C) / 2) EPE A EBE H

[0257] After quantifying the mole fractions and normalizing, the amounts of C2, C3, and C4 can be calculated by summing the triads centered on E, P, and B:

[0258] Sum of triads = PEP + PEE + EEE + PPP + PPE + EPE + EBE

[0259] f mole PEP = PEP / Sum of triads; mole% PEP = f mole PEP * 100

[0260] f mole PEE = PEE / Sum of triads; mole% PEE = f mole PEE * 100

[0261] f mole EEE = EEE / Sum of triads; mole% EEE = f mole EEE * 100

[0262] f mole PPP = PPP / Sum of triads; mole% PPP = f mole PPP * 100

[0263] f mole PPE = PPE / Sum of triads; mole% PPE = f mole PPE * 100

[0264] f mole EPE = EPE / Sum of triads; mole% EPE = f mole EPE * 100

[0265] f mole EBE = EBE / Sum of triads; mole% EBE = f mole EBE * 100

[0266] C2 [mole%] = mole% PEP + mole% PEE + mole% EEE

[0267] C3 [mole%] = mole% PPP + mole% PPE + mole% EPE

[0268] C4 [mole%] = mole% EBE

[0269] The weight percentages of the comonomers are calculated from the mole percentages in the usual way:

[0270] Weight% C2 total = 100 * (C2 [mole%] * 28.06) / ((C2 [mole%] * 28.06) + (C3 [mole%] * 42.08) + C4 [mole%] * 56.11))

[0271] Total weight % C3 = 100 * (C3 [mol%] * 42.08) / ((C2 [mol%] * 28.06) + (C3 [mol%] * 42.08) + C4 [mol%] * 56.11))

[0272] Total weight % C4 = 100 * (C4 [mol%] * 56.11) / ((C2 [mol%] * 28.06) + (C3 [mol%] * 42.08) + C4 [mol%] * 56.11))

[0273] d) Differential scanning calorimetry (DSC) analysis, melting temperature (Tm) and crystallization temperature (Tc):

[0274] Measurements were carried out on 5 to 7 mg samples using a TA Instrument Q2000 differential scanning calorimeter (DSC). The DSC was run at a scan rate of 10 °C / min at temperatures in the range of -30 °C to +225 °C during a heating / cooling / heating cycle according to ISO11357 / Part 3 / Method C2.

[0275] The crystallization temperature and heat of crystallization (Hc) were determined from the cooling step, while the melting temperature and heat of fusion (H f ) were determined from the second heating step.

[0276] When the sample shows two or more melting temperatures and / or crystallization temperatures, only the main melting temperature (at the highest Hc) and the main crystallization temperature (at the highest Hf) are presented in the corresponding table. The difference between the melting temperature and the crystallization temperature (Tm - Tc) for the main melting temperature and the main crystallization temperature is given.

[0277] e) Xylene cold soluble (XCS) content

[0278] The amount of xylene-soluble matter in polypropylene was determined according to ISO16152 (First Edition; 2005-07-01).

[0279] Weighed amounts of the sample were dissolved in hot xylene under reflux conditions at 135 °C. Then, the solution was cooled under controlled conditions and held at 25 °C for 30 minutes to ensure controlled crystallization of the insoluble fraction. The insoluble fraction was then separated by filtration. The xylene was evaporated from the filtrate, leaving the soluble fraction as a residue. The percentage of this fraction was determined by gravimetric analysis.

[0280]

[0281] where

[0282] m0 is the mass of the weighed sample test portion in grams

[0283] m1 is the mass of the residue in grams

[0284] v0 is the original volume of the solvent taken.

[0285] v1 is the volume of the aliquot taken for the determination.

[0286] f) Glass transition temperature (Tg)

[0287] The glass transition temperature Tg is determined by dynamic mechanical analysis (DMTA) according to ISO 6721-7. Measurements are carried out in torsion mode on compression-molded samples (40×10×1 mm3) at a heating rate of 2 °C / min and a frequency of 1 Hz between -100 °C and +150 °C. Tg is determined from the curve of the loss angle (tan(δ)).

[0288] g) Intrinsic viscosity (IV)

[0289] The reduced viscosity (also known as the viscosity number) η red and the intrinsic viscosity IV are determined according to ISO 1628-3: "Determination of the viscosity of polymers in dilute solution using capillary viscometers".

[0290] The relative viscosity of a dilute polymer solution at a concentration of 1 mg / ml and the pure solvent (decahydronaphthalene stabilized with 200 ppm of 2,6-bis(1,1-dimethylethyl)-4-methylphenol) is determined in an automatic capillary viscometer (Lauda PVS1) equipped with 4 Ubbelohde capillaries placed in a thermostatic bath filled with silicone oil. The bath temperature is maintained at 135 °C. The sample is dissolved with continuous stirring until complete dissolution is achieved (usually within 90 min).

[0291] The efflux times of the polymer solution and the pure solvent are measured several times until three consecutive readings differ by no more than 0.2 s (standard deviation).

[0292] The relative viscosity of the polymer solution is determined as the ratio of the average efflux times (in seconds) obtained for both the polymer solution and the solvent:

[0293]

[0294] The reduced viscosity (η red ) is calculated using the following equation:

[0295]

[0296] where C is the polymer solution concentration at 135 °C:

[0297] and m is the polymer mass, V is the solvent volume, and γ is the ratio of the solvent density at 20 °C to that at 135 °C (γ = ρ 20 / ρ 135 = 1.107).

[0298] The intrinsic viscosity IV is calculated from single concentration measurements using the Schulz - Blaschke equation:

[0299]

[0300] where K is a coefficient depending on the polymer structure and concentration. For calculating an approximate value of IV, K = 0.27.

[0301] h) Molecular weight averages, polydispersity (Mn, Mw, Mz, MWD) by GPC-analysis (GPC)

[0302] For GPC analysis, a universal calibration (according to ISO 16014 - 2:2003) column set with 19 narrow MWD polystyrene (PS) standards in the range of 0.5 kg / mol to 11 500 kg / mol is used. The PS standards are dissolved for 15 min at 160 °C or alternatively at room temperature, at a concentration of 0.2 mg / ml for molecular weights higher than or equal to 899 kg / mol and 1 mg / ml for molecular weights lower than 899 kg / mol. The conversion of polystyrene peak molecular weight to polyethylene molecular weight is achieved using the Mark - Houwink equation and the following Mark Houwink constants:

[0303] K PS = 19×10 -3 ml / g, α PS = 0.655

[0304] K PE = 39×10 -3 ml / g, α PE = 0.725

[0305] A third - order polynomial fit is used to fit the calibration data.

[0306] The molecular weight averages (Mz, Mw, and Mn), the molecular weight distribution (MWD), and its width described by the polydispersity index PDI = Mw / Mn (where Mn is the number - average molecular weight and Mw is the weight - average molecular weight) are determined using the following formulae:

[0307]

[0308] i) Flexural modulus

[0309] The flexural modulus was determined on 80 mm × 10 mm × 4 mm specimens according to ISO 178 Method A (3-point bending test). According to this standard, a test speed of 2 mm / min and a span length of 16 times the thickness were used. The test temperature was 23 ± 2 °C. Injection molding was carried out according to ISO 19069-2. For all materials, a melt temperature of 230 °C was used, independent of the melt flow rate of the material.

[0310] j) Notched Izod impact strength

[0311] The notched Izod impact strength was determined on notched specimens of 80 mm × 10 mm × 4 mm (specimens prepared according to ISO 179-1 / 1eA) according to ISO 179-1 / 1eA. The test temperature was 23 ± 2 °C or -20 ± 2 °C. Injection molding was carried out according to ISO 19069-2. For all materials, a melt temperature of 230 °C was used, independent of the melt flow rate of the material.

[0312] k) Rheological measurement

[0313] Dynamic shear measurement (swept frequency measurement)

[0314] In the context, the characterization of the melt of the polymer composition or polymer given by dynamic shear measurements, as above or below, conforms to ISO standards 6721-1 and 6721-10. Measurements were carried out on an Anton Paar MCR501 stress-controlled rotational rheometer equipped with a 25 mm parallel plate geometry. A nitrogen atmosphere was used and the strain was set within the linear viscoelastic range. Measurements were carried out on compression-molded plates. An oscillatory shear test was carried out at 190 °C over a frequency range applied between 0.01 and 600 rad / s and a gap of 1.3 mm was set.

[0315] In a dynamic shear experiment, the probe undergoes uniform deformation under a sinusoidally varying shear strain or shear stress (strain-controlled mode and stress-controlled mode, respectively). In a controlled strain experiment, the probe undergoes a sinusoidal strain that can be represented by the following equation:

[0316] γ(t) = γ0sin(ωt) (1)

[0317] If the applied strain is within the linear viscoelastic range, the resulting sinusoidal stress response can be given by the following equation:

[0318] σ(t) = σ0sin(ωt + δ) (2)

[0319] where

[0320] σ0 and γ0 are the stress and strain amplitudes, respectively

[0321] ω is the angular frequency

[0322] δ is the phase shift (loss angle between the applied strain and stress response)

[0323] t is the time

[0324] The results of dynamic tests are typically represented by means of a number of different rheological functions, namely the shear storage modulus G’, the shear loss modulus G”, the complex shear modulus G*, the complex shear viscosity η*, the dynamic shear viscosity η', the out-of-phase component η” of the complex shear viscosity, and the loss tangent tanδ, which can be expressed as follows:

[0325]

[0326] G * =G′ + iG″ [Pa] (5)

[0327] η * =η′ - iη″ [Pa·s] (6)

[0328]

[0329] The determination of the so-called shear thinning index, which is related to MWD and independent of Mw, is carried out as described in Equation 9.

[0330]

[0331] For example, SHI (2 / 100) is defined by dividing the value of the complex viscosity (in Pa·s) determined for a G* value equal to 1 kPa by the value of the complex viscosity (in Pa·s) determined for a G* value equal to 100 kPa.

[0332] As a function of the frequency (ω), values of the storage modulus (G'), the loss modulus (G"), the complex modulus (G*), and the complex viscosity (η*) are obtained.

[0333] Thus, for example, η* 300rad / s (eta* 300rad / s or eta 300 ) is used as an abbreviation for the complex viscosity at a frequency of 300 rad / s, and η* 0.05rad / s (eta* 0.05rad / s or eta 0.05 ) is used as an abbreviation for the complex viscosity at a frequency of 0.05 rad / s.

[0334] The polydispersity index PI is defined by Equation 10.

[0335]

[0336] where ω COP is the cross-over angular frequency, defined as the angular frequency at which the storage modulus G' equals the loss modulus G".

[0337] These values were determined by means of a single-point interpolation procedure defined by the Rheoplus software. In cases where the given G* value was not reached experimentally, the value was determined by extrapolation, using the same procedure as before. In both cases (interpolation or extrapolation), the options "Interpolate y-values to x-values from parameter" and "logarithmic interpolation type" in Rheoplus were applied.

[0338] References:

[0339] [1] "Rheological characterization of polyethylene fractions” Heino, E.L., Lehtinen, A., Tanner J., J., Neste Oy, Porvoo, Finland, Theor.Appl.Rheol., Proc.Int.Congr.Rheol, 11th(1992), 1, 360 - 362

[0340] [2] "The influence of molecular structure on some rheological properties of polyethylene”, Heino, E.L., Borealis Polymers Oy, Porvoo, Finland, Annual Transactions of the Nordic Rheology Society, 1995.).

[0341] [3] "Definition of terms relating to the non-ultimate mechanical properties of polymers", Pure&Appl.Chem., Vol. 70, No. 3, pp. 701 - 754, 1998.

[0342] l) AC electrical breakdown strength (ACBD)

[0343] The AC breakdown test is carried out in accordance with CENELEC HD 605 5.4.15.3.4 for 6 / 10 kV cables. Therefore, the cable is cut into 6 test samples with an effective length of 10 m (plus ends). The samples are subjected to a breakdown test by 50 Hz AC step testing at ambient temperature according to the following procedure:

[0344] · Start at 18 kV for 5 minutes

[0345] · Increase the voltage in steps of 6 kV every 5 minutes until breakdown occurs

[0346] The calculation of the Weibull parameters of the data set of six breakdown values (conductor stress, i.e., the electric field at the inner semiconductive layer) follows the least squares regression procedure described in IEC62539 (2007). The Weibull α parameter in this document refers to the scale parameter of the Weibull distribution, i.e., the voltage at a failure probability of 0.632. The Weibull β value refers to the shape parameter.

[0347] 2. Propylene copolymer composition

[0348] The following resins are used to prepare the propylene copolymer compositions in the examples:

[0349] a) Polymerization of the multiphase propylene copolymer powder A1

[0350] · Catalyst

[0351] The catalyst used in the polymerization process of the multiphase propylene copolymer powder A1 is a Ziegler-Natta catalyst, which is described in patent publications EP491566, EP591224, and EP586390. Triethylaluminum (TEAL) is used as a cocatalyst, and dicyclopentyldimethoxysilane (D-donor) is used as a donor.

[0352] · Polymerization of multiphase propylene copolymer powder

[0353] The multiphase propylene copolymer powder A1 is produced in a Borstar TM plant using one liquid-phase loop reactor and two gas-phase reactors connected in series under the conditions shown in Table 1 in the presence of the polymerization catalyst described above. The first reaction zone is a loop reactor, and the second and third reaction zones are gas-phase reactors. The matrix phase is polymerized in the loop reactor and the first gas-phase reactor, and the elastomeric phase is polymerized in the second gas-phase reactor. The catalyst described above is fed into the prepolymerization reactor before the first reaction zone.

[0354] Table 1: Polymerization conditions for multiphase propylene copolymer powder:

[0355] A1-powder Prepolymerization TEAL / Ti ratio [mol / mol] 342 Donor / Ti ratio [mol / mol] 26.9 Temperature [℃] 19.9 Residence time [h] 0.16 Loop reactor Temperature [℃] 70.0 Pressure [bara] 55 Split ratio (loop reactor + prepolymerization) [％] 33.7 H2 / C3 ratio [mol / kmol] 5.5 C2 / C3 ratio [mol / kmol] 16.7 MFR (230°C / 2.16 kg) [g / 10 min] 6.5 C2 content (calculated) [wt%] 2.0 GPR 1 Temperature [℃] 74.9 Pressure [bara] 21.0 Split ratio (GPR1) [％] 48.2 H2 / C3 ratio [mol / kmol] 21.3 C2 / C3 ratio [mol / kmol] 53.4 MFR (230°C / 2.16 kg) [g / 10 min] 1.3 C2 content (calculated) [wt%] 6.5 GPR 2 Temperature [℃] 79.99 Pressure [bara] 16.03 Split ratio (GPR2) [％] 18.2 C2 / C3 ratio [mol / kmol] 401 H2 / C3 ratio [mol / kmol] 69 MFR (230°C / 2.16 kg) [g / 10min] 1.2 XCS [wt%] 35.3 C2 (Calculated content) [wt%] 10.5

[0356] b) Preparation of polypropylene compositions

[0357] The multiphase propylene copolymer powder A1 from the polymerization reaction was compounded in a twin-screw extruder with different stabilizer packages to obtain the polypropylene compositions of reference examples RE1 and RE2.

[0358] For reference example RE2, an α-nucleating agent was added to the powder and the composition was devolatilized to a melt flow rate MFR2 (230 °C, 2.16 kg) of 3.9 g / 10 min, as disclosed in the example section of WO 2017 / 198633.

[0359] An overview of the production of the polypropylene compositions of examples RE1 and RE2 is shown in Table 2.

[0360] Table 2: Compounding of RE1 and RE2 in a twin-screw extruder:

[0361] RE1 RE2 HECO - powder A1 - powder A1 - powder Visbreaking No Yes Stabilizer single pack 1 [wt%] 0.2 - Stabilizer single pack 2 [wt%] - 0.14 α - NA BNT [wt%] No 2.0 Temperature range in extruder zone [℃] 140 to 300 150 to 280 Specific energy input (SEI) kWh / kg 0.155 0.146 Polymer melt temperature at melt pump [℃] 244 231

[0362] The polypropylene compositions RE1 and RE2 exhibit the properties listed in Table 3 below.

[0363] Table 3: Properties of polypropylene compositions RE1 and RE2:

[0364] RE1 RE2 α - NA No BNT <![CDATA[MFR2]]> [g / 10min] 1.2 3.9 Flexural modulus [MPa] 335 378 Simply supported beam NIS (-20°C) <![CDATA[[kJ / m 2 > 6.3 4.2 Simply supported beam NIS (23°C) <![CDATA[[kJ / m 2 > 83.9 78.9 Tm [℃] 148.9 147.4 Tc [℃] 95.7 114.5 Tm - Tc [℃] 53.2 32.9 C2 (Total) (by FT - IR) [wt%] 12.4 11.3 IV (Total) <![CDATA[[cm 3 / g]]]> 277 213 XCS fraction [wt%] 35.6 35.6 C2 (XCS) (by FT - IR) [wt%] 26.1 24.5 IV (XCS) <![CDATA[[cm 3 / g]]]> 251 189 Mw (XCS) [g / mol] 294500 215000 Mn (XCS) [g / mol] 45650 48900 PDI (Mw / Mn) (XCS) [-] 6.4 4.4 XCI fraction [wt%] 64.4 64.4 C2 (XCI) (by FT - IR) [wt%] 4.8 5.8 IV (XCI) <![CDATA[[cm 3 / g]]]> 286 216 Mw (XCI) [g / mol] 384500 271000 Mn (XCI) [g / mol] 69500 62000 PDI (Mw / Mn) (XCI) [-] 5.5 4.4 IV ratio (XCI / XCS) [-] 1.14 1.14 Mw ratio (XCI / XCS) [-] 1.31 1.26

[0365] To produce the polymer compositions of examples IE1, IE2 and IE3 and comparative example CE1 of the present invention, the compounded pellets of reference example RE1 were compounded in a second compounding step in a Buss 100MDK L / D 11D co-kneader with different additives. Table 4 shows an overview of the production of the polypropylene compositions CE1, IE1, IE2 and IE3. Table 6 shows the properties of CE1, IE1, IE2 and IE3.

[0366] Table 4: Compounding of IE1 to IE3 and CE1 in a Buss 100MDK L / D 11D co-kneader:

[0367] CE1 IE1 IE2 IE3 Pellets RE1 RE1 RE1 RE1 Excerex 30200B [wt%] - 10 - - Queo 8230 [wt%] - - 10 - Queo 7007LA [wt%] - - - 10 Mixer zone temperature [℃] 97 to 192 115 to 209 125 to 208 Mixer RPM 146 148 150 Specific energy input SEI [kWh / kg] 0.24 0.28 0.25

[0368] Stabilizer packages and additives:

[0369] · Stabilizer single package 1 consists of 21.8 wt% of pentaerythritol tetrakis(3-(3’,5’-di-tert-butyl-4-hydroxyphenyl)propionate) (CAS No. 6683-19-8), 43.6 wt% of tris(2,4-di-tert-butylphenyl) phosphite (CAS No. 31570-04-4) and 34.6 wt% of calcium stearate (CAS No. 1592-23-0), all of which are commercially available from multiple companies.

[0370] · Stabilizer single package 2 consists of 29 wt% of pentaerythritol tetrakis(3-(3’,5’-di-tert-butyl-4-hydroxyphenyl)propionate) (CAS No. 6683-19-8), 58 wt% of tris(2,4-di-tert-butylphenyl) phosphite (CAS No. 31570-04-4) and 13 wt% of magnesium oxide (CAS No. 1309-48-4), all of which are commercially available from multiple companies.

[0371] · α-Nucleation via BNT is achieved by adding 2 wt% of an isotactic polypropylene homopolymer having an MFR2 (230 °C) of 8.0 g / 10 min and a melting temperature of 162 °C, which is produced with Borealis Nucleation Technology (BNT) using a Ziegler-Natta type catalyst, contains a polymer α-nucleating agent, and is distributed by Borealis AG (Austria).

[0372] · Excerex 30200B is a single-site catalyzed poly(ethylene-co-1-butene) wax having a density of 905 kg / m 3 ³, a weight average molecular weight Mw of 2700 g / mol, a melt viscosity at 140 °C of 265 mPas, a crystallinity of 57% and a melting temperature of 91 °C, and is commercially available from Mitsui Chemicals, Inc. (data taken from the technical data sheet).

[0373] · Queo 8230 is a single-site catalyzed poly(ethylene-co-1-octene) elastomer having a density of 882 kg / m 3 ³, a melt flow rate MFR2 (190 °C, 2.16 kg) of 30 g / 10 min and a crystallinity of less than 25%, and is commercially available from Borealis AG.

[0374] · Queo 7007LA is a single-site catalyzed poly(ethylene-co-1-octene) elastomer having a density of 870 kg / m 3with a density, a melt flow rate MFR2 (190 °C, 2.16 kg) of 6.6 g / 10 min and a crystallinity of less than 20%, is commercially available from Borealis AG.

[0375] For the polypropylene composition IE1, the total content of ethylene (C2), propylene (C3) and 1-butene (C4) and the content of ethylene (C2), propylene (C3) and 1-butene (C4) in the XCS and XCI fractions have been measured by 13 13C NMR measurements as described above.

[0376] Table 5 shows the content of ethylene (C2), propylene (C3) and 1-butene (C4) for Example IE1 and other properties of CE1, IE1, IE2 and IE3.

[0377] For the polypropylene compositions CE1, IE1, IE2 and IE3, the total content of ethylene (C2), propylene (C3) and 1-octene (C8) and the content of ethylene (C2), propylene (C3) and 1-octene (C8) in the XCS and XCI fractions have been measured by 13 13C NMR measurements as described above.

[0378] Table 5 shows the content of ethylene (C2), propylene (C3) and 1-octene (C8) and other properties of CE1, IE1, IE2 and IE3.

[0379] Table 5: Properties of the composite compositions of CE1, IE1, IE2, CE2 and IE3

[0380] CE1 IE1 IE2 IE3 <![CDATA[MFR2]]> [g / 10min] 1.3 5.0 1.6 1.5 Flexural modulus [MPa] 352 301 281 281 Simply supported beam NIS 23°C <![CDATA[[kg / m 3 > 75.9 69.9 75.7 72.9 Simply supported beam NIS - 20°C <![CDATA[[kg / m 2 > 5.9 5.1 9.4 9.9 Tm [℃] 149.7 150.2 149.8 150.0 Tc [℃] 97.5 96.1 96.1 95.8 Tm - Tc [℃] 52.2 54.1 53.7 54.2 Tg (EP) [℃] -47.4 -46.8 -48.4 -48.9 Tg (Matrix) [℃] -8.6 -9.7 -8.5 -8.3 C2 (Total) [wt%] 12.4 21.1 20.1 20.0 C3 (Total) [wt%] 87.6 77.9 77.4 76.9 C4 (Total) [wt%] n.a. 0.9 n.a. n.a. C8 (Total) [wt%] n.a. n.a. 2.5 3.1 XCS fraction [wt%] 35.8 36.4 40.9 42.7 C2 (XCS) [wt%] 25.6 32.0 39.0 39.7 C3 (XCS) [wt%] 74.4 67.2 55.7 53.4 C4 (XCS) [wt%] n.a. 0.8 n.a. n.a. C8 (XCS) [wt%] n.a. n.a. 5.3 6.9 IV (XCS) <![CDATA[[cm 3 / g]]]> 247 231 222 217 Mw [g / mol] 260500 229500 221500 224500 Mn [g / mol] 40750 21950 34600 36950 Mw / Mn [-] 6.4 10.5 6.4 6.1 XCI fraction [wt%] 64.2 63.6 59.2 57.3 C2 (XCI) [wt%] 5.2 13.4 7.4 6.4 C3 (XCI) [wt%] 94.8 85.9 92.0 93.3 C4 (XCI) [wt%] n.a. 0.7 n.a. n.a. C8 (XCI) [wt%] n.a. n.a. 0.7 0.3 IV (XCI) <![CDATA[[cm 3 / g]]]> 278 237 274 274 Mw [g / mol] 329500 271500 314000 327000 Mn [g / mol] 59350 35050 53400 54500 Mw / Mn [-] 5.6 7.8 5.9 6.1 IV (XCI) / IV (XCS) [-] 1.13 1.03 1.22 1.26 Mw (XCI) / Mw (XCS) [-] 1.26 1.18 1.42 1.46 <![CDATA[ω COP > [1 / s] 14.0 30.7 16.4 17.2 SHI 1 / 100 [-] 10.8 11.5 12.9 10.9 PI [1 / s] 2.7 3.0 2.9 2.7

[0381] n.a. not applicable

[0382] It can be seen that compared with the comparative composition CE1, the compositions IE1 to IE3 of the present invention show higher flexibility and comparable impact properties (IE1) or higher impact properties (IE2 and IE3) in addition to having comparable crystallization and melting temperatures.

[0383] Production of 3.10 kV cables

[0384] The 10 kV test cables were produced on a Maillefer test cable line of the contacting continuous vulcanization (CCV) type.

[0385] The conductor of the cable core has stranded aluminum with a cross-section of 50 mm 2 and a cross-section of 50 mm 2。The inner semiconductor layer is produced from the semiconductor composition SC2 as described below and has a thickness of 1.0 mm. The insulating layer is produced from the compositions CE1 and IE1 to IE3 as described above and has a thickness of 3.4 mm. The outer semiconductor layer is produced from the semiconductor composition SC1 as described below and has a thickness of 1.0 mm.

[0386] The cable (i.e., the cable core) is produced by extrusion via a triple head. The size of the insulation extruder is 100 mm, the size of the conductor shield (inner semiconductor layer) extruder is 45 mm, and the size of the insulation shield (outer semiconductor layer) extruder is 60 mm. The line speed is 6.0 m / min.

[0387] The total length of the vulcanization tube is 52.5 meters and consists of a curing section followed by a cooling section. The curing section is filled with N2 at 10 bar but not heated. The 33-meter-long cooling section is filled with water at 20 to 25 °C.

[0388] Then, an AC breakdown test is performed on the test cable.

[0389] Semiconductor layer 1 (SC1) is prepared from the ready-to-use semiconductor composition Borlink LE7710, which is a non-crosslinkable polyethylene-based composition containing carbon black and is commercially available from Borealis AG.

[0390] Semiconductor layer 2 (SC2) is prepared from a polypropylene-based composition of 66.5 wt% of RE2, 33.0 wt% of carbon black Printex Alpha (commercially available from Orion Engineered Carbons GmbH), and 0.5 wt% of maleic anhydride-functionalized polypropylene Exxelor PO1020 (commercially available from Exxon Mobil).

[0391] Table 6 shows the electrical properties of the 10 kV cables of Examples C1 to C4, in which the insulating layers IE1 to IE3 of the present invention are compared with the comparative insulating layer CE1.

[0392] Table 6: Electrical properties of the 10 kV cables of C1 to C4

[0393] C1 C2 C3 C4 Insulation layer CE1 IE1 IE2 IE3 Inner semiconductor layer SC2 SC2 SC2 SC2 Outer semiconductor layer SC1 SC1 SC1 SC1 Weibull - α (scale) [kV / mm] 42.3 49.1 44.1 45.6 Weibull - β (shape) 14.3 10.5 8.1 23.5

[0394] It can be seen that compared with the cables including the corresponding comparative insulating layer CE1, all the cables including the insulating layers IE1, IE2, and IE3 of the present invention show an increased Weibull-α value. Compared with cable C1 including the comparative insulating layer CE1, cable C4 including the insulating layer IE3 of the present invention even shows an increased Weibull-β value.

Claims

1. A cable, said cable comprising at least one layer comprising a polypropylene composition, said polypropylene composition comprising (A) a copolymer of 80.0 to 99.0% by weight, preferably 82.5 to 97.2% by weight, most preferably 85.0 to 95.0% by weight of propylene and comonomer units selected from ethylene and α-olefins having 4 to 12 carbon atoms, based on the total weight of the polypropylene composition, said copolymer having By quantitative 13 C{ 1 H} NMR measurement, the total amount of the monomer units in the propylene-based copolymer (A) to be determined is 10.0 to 16.0% by weight, preferably 11.0 to 15.0% by weight, and most preferably 12.0 to 14.0% by weight of comonomer units; a melt flow rate MFR2 of 0.5 to 2.5 g / 10 min, preferably 0.8 to 2.3 g / 10 min, still more preferably 1.0 to 2.0 g / 10 min and most preferably 1.2 to 1.7 g / 10 min as determined according to ISO 1133 at 230 °C and 2.16 kg; a total amount of 25.0 to 50.0% by weight, preferably 27.5 to 45.0% by weight, more preferably 30.0 to 42.5% by weight and most preferably 32.5 to 40.0% by weight of xylene cold soluble (XCS) fraction based on the total weight of the copolymer (A) of propylene and determined according to ISO 16152; and (B) a copolymer of 1.0 to 20.0% by weight, preferably 2.5 to 17.5% by weight, most preferably 5.0 to 15.0% by weight of ethylene and comonomer units selected from α-olefins having 4 to 12 carbon atoms, based on the total weight of the polypropylene composition, said copolymer being obtainable in the presence of a single-site catalyst and having 860 to 930 kg / m 3 , preferably 865 to 925 kg / m 3 , most preferably 870 to 920 kg / m 3 of density determined according to ISO 1183.

2. The cable according to claim 1, wherein the copolymer (A) of propylene is a multiphase copolymer of propylene, said multiphase copolymer of propylene comprising a matrix phase and an elastomeric phase dispersed in the matrix phase, said multiphase copolymer of propylene preferably comprises two glass transition temperatures attributable to the matrix phase and the elastomeric phase, wherein the glass transition temperature Tg (matrix) attributable to the matrix phase is in the range of -1.0 to -15.0 °C, preferably in the range of -2.5 to -12.5 °C and most preferably in the range of -5.0 to -10.0 °C, and / or the glass transition temperature Tg (EP) attributable to the elastomeric phase is in the range of -40.0 to -55.0 °C, preferably in the range of -42.5 to -52.5 °C and most preferably in the range of -45.0 to -50.0 °C, wherein Tg (matrix) and Tg (EP) are determined by dynamic mechanical analysis.

3. The cable according to claim 1 or 2, wherein the xylene cold-soluble (XCS) fraction of the copolymer (A) of propylene has, based on the total amount of monomer units in the xylene cold-soluble (XCS) fraction and determined by quantitative 13 C{ 1 H} NMR measurement, an amount of 23.0 to 35.0% by weight, more preferably 23.5 to 32.5% by weight and most preferably 24.0 to 30.0% by weight of comonomer units, preferably ethylene, and / or a intrinsic viscosity measured in decalin according to ISO 1628-3 of 150 to 350 cm 3 / g, preferably 200 to 325 cm 3 / g and most preferably 225 to 300 cm 3 / g.

4. The cable according to any one of claims 1 to 3, wherein the copolymer (A) of propylene has a fraction insoluble in cold xylene (XCI) in an amount of 50.0 to 75.0% by weight, more preferably 55.0 to 72.5% by weight, still more preferably 57.5 to 70.0% by weight and most preferably 60.0 to 67.5% by weight, based on the total weight of the copolymer (A) of propylene and determined according to ISO 16152, and wherein the fraction insoluble in cold xylene (XCI) preferably has an amount of 3.0 to 9.0% by weight, preferably 4.0 to 8.5% by weight and most preferably 4.5 to 7.5% by weight of comonomer units, preferably ethylene, based on the total amount of monomer units in the fraction insoluble in cold xylene (XCI) and determined by quantitative 13 C{ 1 H} NMR measurement, and / or a specific viscosity measured in decalin according to ISO 1628-3 of 185 to 350 cm 3 / g, more preferably 220 to 325 cm 3 / g and most preferably 210 to 300 cm 3 / g.

5. The cable according to any one of claims 1 to 4, wherein the copolymer (A) of propylene has one or more of the following properties, preferably has all of the following properties: ● a flexural modulus of 130 MPa to 400 MPa, more preferably 150 MPa to 390 MPa and most preferably 175 MPa to 380 MPa as determined according to ISO 178 method A; and / or ● 50 to 110 kJ / m 2 , more preferably 65 to 100 kJ / m 2 and most preferably 75 to 95 kJ / m 2 of the notched Izod impact strength at 23 °C determined according to ISO 179-1 / 1eA; and / or ● 5.0 to 10.0 kJ / m 2 , more preferably 5.5 to 9.0 kJ / m 2 and most preferably 6.0 to 8.0 kJ / m 2 of the notched Izod impact strength at -20 °C determined according to ISO 179-1 / 1eA.

6. The cable according to any one of claims 1 to 5, wherein the copolymer (B) of ethylene is a copolymer of ethylene and 1-octene or a copolymer of ethylene and 1-butene.

7. The cable according to any one of claims 1 to 6, wherein the copolymer (B) of ethylene is a copolymer of ethylene and 1-octene, and the copolymer has one or more of the following properties, preferably all of the following properties: ● 860 to 895 kg / m 3 , preferably 865 to 890 kg / m 3 , most preferably 870 to 885 kg / m 3 density determined according to ISO 1183; and / or ● A crystallinity of 10.0 to 40.0%, preferably 12.5 to 35.0%, more preferably 15.0 to 30.0%; and / or · A melt flow rate MFR2 measured according to ISO 1133 at 190 °C and 2.16 kg of 1.0 to 50.0 g / 10 min, preferably 2.5 to 40 g / 10 min, most preferably 5.0 to 35 g / 10 min; and / or · A glass transition temperature Tg measured by dynamic mechanical analysis of -60 to -40 °C, preferably -57 to -42 °C, most preferably -55 to -45 °C; and / or · A melting temperature Tm measured by differential scanning calorimetry of 40 to 85 °C, preferably 42 to 82 °C, most preferably 45 to 80 °C; and / or · A flexural modulus measured according to ISO 178 method A of 1 to 50 MPa, preferably 3 to 40 MPa, most preferably 5 to 30 MPa.

8. The cable according to any one of claims 1 to 6, wherein the copolymer (B) of ethylene is a polyethylene wax, the polyethylene wax is a copolymer of ethylene and 1-butene and has one or more of the following properties, preferably all of the following properties: · 900 to 930 kg / m 3 , preferably 905 to 925 kg / m 3 , most preferably 910 to 920 kg / m 3 density determined according to ISO 1183; and / or · A crystallinity of 40.0 to 65.0%, preferably 42.5 to 62.5%, most preferably 45.0 to 60.0%; and / or · A weight average molecular weight Mw measured by GPC of 1000 to 5000 g / mol, preferably 1500 to 4000 g / mol, most preferably 2000 to 3500 g / mol; and / or · A melting temperature Tm measured by differential scanning calorimetry of 90 to 110 °C, preferably 92 to 107 °C, most preferably 95 to 105 °C; and / or ● A melt viscosity at 140 °C of 100 to 500 mPas, preferably 150 to 400 mPas, most preferably 200 to 350 mPas 9. The cable according to any one of claims 1 to 8, wherein the polypropylene composition has A total of 70.0 to 87.5% by weight, more preferably 72.5 to 85.0% by weight and most preferably 75.0 to 82.5% by weight of units derived from propylene; A total of 12.5 to 35.0% by weight, more preferably 15.0 to 32.5% by weight and most preferably 17.5 to 30.0% by weight of units derived from ethylene; and A total of 0.1 to 10.0% by weight, more preferably 0.2 to 7.5% by weight and most preferably 0.3 to 5.0% by weight of units derived from α-olefins having 4 to 12 carbon atoms, 10. The cable according to any one of claims 1 to 9, wherein the polypropylene composition has a xylene cold soluble (XCS) fraction, and the xylene cold soluble (XCS) fraction has All amounts are based on the total amount of monomer units in the polypropylene composition and are determined using quantitative 13 C{ 1 H} NMR measurements. 13 C{ 1 H}NMR measurements. ​ Units derived from propylene in an amount of 47.5 to 75.0% by weight, more preferably 50.0 to 72.5% by weight and most preferably 52.5 to 70.0% by weight; From 25.0 to 47.5% by weight, more preferably from 27.5 to 45.0% by weight and most preferably from 30.0 to 42.5% by weight of ethylene-derived units; and Units derived from α-olefins having 4 to 12 carbon atoms in an amount of 0.1 to 12.5% by weight, more preferably 0.2 to 10.0% by weight and most preferably 0.3 to 7.5% by weight, All amounts are based on the total amount of monomer units in the xylene cold soluble (XCS) fraction and are determined using quantitative 13 C{ 1 H} NMR measurements; and / or 13 C{ 1 H}NMR measurements; and / or The polypropylene composition has a fraction insoluble in cold xylene (XCI), and the fraction insoluble in cold xylene (XCI) has Units derived from propylene in an amount of 80.0 to 96.5% by weight, more preferably 82.0 to 95.0% by weight and most preferably 84.0 to 94.0% by weight; Units derived from ethylene in an amount of 3.5 to 20.0% by weight, more preferably 5.0 to 17.5% by weight and most preferably 6.0 to 15.0% by weight; and Units derived from α-olefins having 4 to 12 carbon atoms in an amount of 0 to 2.5% by weight, more preferably 0 to 2.0% by weight and most preferably 0 to 1.5% by weight, All amounts are based on the total amount of monomer units in the fraction insoluble in cold xylene (XCI) and are determined using quantitative 13 C{ 1 H} NMR measurements. 13 C{ 1 H}NMR measurements.

11. The cable according to any one of claims 1 to 10, wherein the polypropylene composition has one or more of the following properties, or has all of the following properties: · A melt flow rate MFR2 measured according to ISO 1133 at 230 °C and 2.16 kg of 0.5 to 7.5 g / 10 min, preferably 0.8 to 7.0 g / 10 min, more preferably 1.0 to 6.5 g / 10 min and most preferably 1.2 to 6.0 g / 10 min; and / or · A melting temperature Tm measured by differential scanning calorimetry of 140 to 159 °C, preferably 143 to 157 °C and most preferably 145 to 153 °C; and / or · A crystallization temperature Tc measured by differential scanning calorimetry of 85 to 130 °C, more preferably 87 to 128 °C and most preferably 90 to 125 °C; and / or · A difference between the melting temperature and the crystallization temperature Tm - Tc, preferably in the range of 20 to 65 °C, preferably 25 to 60 °C and most preferably 27 to 55 °C; and / or · A glass transition temperature Tg(matrix) attributable to the matrix phase measured by dynamic mechanical analysis in the range of -1.0 °C to -15.0 °C, preferably in the range of -2.5 °C to -12.5 °C and most preferably in the range of -5.0 °C to -11.0 °C; and / or ● A glass transition temperature Tg(EP) attributable to the elastomeric phase measured by dynamic mechanical analysis of -40.0 to -55.0 °C, preferably -42.5 to -52.5 °C and most preferably -45.0 to -50.0 °C; and / or · A shear thinning index SHI determined by dynamic shear measurement of from 2.5 to 20.0, more preferably from 5.0 to 17.5 and most preferably from 7.5 to 15.0 1 / 100 ; and / or · 1.0 to 4.5 s -1 , more preferably 1.5 to 4.0 s -1 and most preferably 2.0 to 3.5 s -1 of the polydispersity index PI determined by dynamic shear measurement; and / or · A flexural modulus measured according to ISO 178 method A of 150 MPa to 350 MPa, more preferably 175 MPa to 335 MPa and most preferably 200 MPa to 315 MPa; and / or · 50 to 110 kJ / m 2 , more preferably 60 to 100 kJ / m 2 and most preferably 65 to 95 kJ / m 2 of the notched Izod impact strength at 23 °C determined according to ISO 179-1 / 1eA; and / or · 3.5 to 25.0 kJ / m 2 , more preferably 4.0 to 20.0 kJ / m 2 and most preferably 4.5 to 15.0 kJ / m 2 of the notched Izod impact strength at -20 °C determined according to ISO 179-1 / 1eA.

12. The cable according to any one of claims 1 to 11, wherein the polypropylene composition does not contain a dielectric fluid.

13. The cable according to any one of claims 1 to 12, wherein the at least one layer is an insulating layer.

14. The cable according to any one of claims 1 to 13, which is a medium voltage cable or a high voltage cable and comprises an insulating layer containing the polypropylene composition.

15. The cable according to any one of claims 1 to 14, which is a cable comprising an insulating layer containing the polypropylene composition and having a Weibull α value measured on a 10 kV cable in accordance with CENELEC HD 605 5.4.15.3.4 for a 6 / 10 kV cable of 35.0 to 65.0 kV / mm, preferably 37.5 to 65.0 kV / mm and most preferably 40.0 to 65.0 kV / mm and / or a Weibull β value measured on a 10 kV cable in accordance with CENELEC HD 605 5.4.15.3.4 for a 6 / 10 kV cable of 5.0 to 250.0, preferably 5.5 to 250.0 and most preferably 6.0 to 50.0.

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