Polypropylene composition for cable insulation

Abstract

The present invention relates to 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 alpha-olefins having 4 to 12 carbon atoms, the total amount of comonomer units being 10.0 to 16.0% by weight, based on the total amount of monomer units of propylene copolymer (A), the total amount of comonomer units being 0.5 to 5.0% by weight, based on the total amount of monomer units of propylene copolymer (A); preferably 11.0 to 15.0% by weight, most preferably 12.0 to 14.0% by weight; a melt flow rate MFR2 in the range of 0.5 to 2.5 g / 10 min, preferably in the range of 0.8 to 2.3 g / 10 min, more preferably in the range of 1.0 to 2.0 g / 10 min, most preferably in the range of 1.2 to 1.7 g / 10 min; the total amount of xylene cold soluble (XCS) fraction is 25.0 to 50.0 wt%, preferably 27.5 to 45.0 wt%, more preferably 30.0 to 42.5 wt%, most preferably 32.5 to 40.0 wt%, based on the total weight of propylene copolymer (A); and (B) 1.0 to 20.0 wt.%, preferably 2.5 to 17.5 wt.%, most preferably 5.0 to 15.0 wt.%, of an ethylene-butyl acrylate copolymer wherein the ethylene-butyl acrylate copolymer has a butyl acrylate content, determined by FT-IR, in the range of 15.0 to 40.0 wt.%, based on the total weight of the ethylene-butyl acrylate copolymer, and wherein the ethylene-butyl acrylate copolymer has a butyl acrylate content, determined by FT-IR, in the range of 15.0 to 40.0 wt.%, based on the total weight of the ethylene-butyl acrylate copolymer. The invention relates to an article comprising said polypropylene composition, preferably a cable comprising an insulating layer comprising said polypropylene composition, and to the use of said polypropylene composition as a cable insulation material for medium and high voltage cables.

Description

Technical Field

[0001] The present invention relates to a flexible polypropylene composition, an article comprising the polypropylene composition, preferably a cable including an insulation layer comprising the polypropylene composition and the use of the polypropylene composition as cable insulation material for medium and high voltage cables. Background Art

[0002] Today, vinyl polymer products are used as insulation and semi-conductor shielding for low, medium and high voltage cables due to their easy processing and good electrical properties. In addition, in low voltage applications, polyvinyl chloride (PVC) is also commonly used as an insulation material, usually in combination with a softener to achieve the desired cable softness. PVC is a thermoplastic that can be used over a wide temperature range by adding various plasticizers. For standard PVC, a continuous conductor temperature of up to 70°C is normal. At low temperatures, PVC becomes hard and should be avoided at temperatures below -10°C. When the conductor temperature exceeds 100°C, the plasticizer migrates out and the material loses its flexibility. However, by adding special plasticizers and stabilizers, PVC materials with conductor temperatures of 90-105°C can be produced. But in practice, PVC is mainly used in the 1kV area, because the material's higher dielectric constant and dissipation factor mean that the losses will be too large at higher voltages, so PVC cables are not usually used above 1kV. In addition, softeners must be added to PVC to maintain a high level of flexibility. Insufficient amounts of softeners can significantly reduce the low temperature performance of PVC. These softeners are not always problematic from an environmental perspective, so it is best to eliminate them.

[0003] Especially for medium voltage, high voltage and extra high voltage (MV, HV and EHV) cables and high voltage direct current (HVDC) cables, the insulation materials are currently dominated by cross-linked ethylene polymer (XLPE) products. These products have high operating temperatures, high electrical breakdown strength and good mechanical properties. However, due to cross-linking, XLPE cannot be recycled by remelting.

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

[0005] Therefore, there is a growing interest in polymer compositions based on thermoplastic propylene polymers for use in insulation 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 show a good balance of properties in terms of flexibility, mechanical properties, impact properties and electrical breakdown strength.

[0007] Therefore, there is a need in the art for a polypropylene composition suitable for cable insulation material, which composition exhibits a good balance of properties in terms of flexibility, mechanical properties, impact properties and electrical breakdown strength when used as cable insulation material for MV or HV cables. Summary of the invention

[0008] One aspect of the present invention relates to a polypropylene composition comprising:

[0009] (A) 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, of a copolymer of propylene with comonomer units selected from ethylene and α-olefins having 4 to 12 carbon atoms,

[0010] The total amount of comonomer units of the copolymer of propylene and comonomer units is from 10.0 to 16.0 wt%, preferably from 11.0 to 15.0 wt%, most preferably from 12.0 to 14.0 wt%, based on the total amount of monomer units of the propylene copolymer (A);

[0011] The melt flow rate MFR2 of the copolymer of propylene and comonomer units is 0.5 to 2.5 g / 10 min, preferably 0.8 to 2.3 g / 10 min, more preferably 1.0 to 2.0 g / 10 min, most preferably 1.2 to 1.7 g / 10 min;

[0012] the total amount of xylene cold soluble (XCS) fraction of the copolymer of propylene and comonomer units is from 25.0 to 50.0 wt.-%, preferably from 27.5 to 45.0 wt.-%, more preferably from 30.0 to 42.5 wt.-%, most preferably from 32.5 to 40.0 wt.-%, based on the total weight of the propylene copolymer (A); and

[0013] (B) 1.0 to 20.0 wt.-%, preferably 2.5 to 17.5 wt.-%, most preferably 5.0 to 15.0 wt.-%, based on the total weight of the polypropylene composition, of an ethylene-butyl acrylate copolymer, wherein the ethylene-butyl acrylate copolymer has a butyl acrylate content in the range of 15.0 to 40.0 wt.-%, more preferably in the range of 20.0 to 35.0 wt.-%, most preferably in the range of 25.0 to 30.0 wt.-%, based on the total weight of the ethylene-butyl acrylate copolymer.

[0014] In another aspect the present invention relates to an article comprising a polypropylene composition as described above or below.

[0015] Preferably, the article is a cable comprising an insulation layer comprising the polypropylene composition as described above or below.

[0016] In another aspect the present invention relates to the use of a polypropylene composition as described above or below as cable insulation material for medium and high voltage cables.

[0017] definition

[0018] Heterophasic polypropylene is a propylene-based copolymer having a semi-crystalline matrix phase and an elastomeric phase dispersed therein, the semi-crystalline matrix phase being either a propylene homopolymer or a random copolymer of propylene and at least one α-olefin comonomer. The elastomeric phase can be a propylene copolymer having a large amount of comonomers which are not randomly distributed in the polymer chain but are distributed in comonomer-rich block structures and propylene-rich block structures.

[0019] Heterophasic polypropylene typically differs from monophasic propylene copolymers in that it has two different glass transition temperatures Tg, which are attributed to the matrix phase and the elastomeric phase.

[0020] Propylene homopolymers are polymers consisting mainly of propylene monomer units. Due to impurities, especially in commercial polymerization processes, propylene homopolymers may contain up to 0.1 mol% comonomer units, preferably up to 0.05 mol% comonomer units, most preferably up to 0.01 mol% comonomer units.

[0021] The random propylene copolymer is a copolymer of propylene monomer units and comonomer units, wherein the comonomer units are randomly distributed on the polypropylene chain. Therefore, the random propylene copolymer includes a xylene-insoluble part, a cold xylene insoluble (XCI) part, based on the total amount of the random propylene copolymer, and the content of the cold xylene insoluble (XCI) part is at least 85% by weight, most preferably at least 88% by weight. Therefore, the random propylene copolymer does not contain an elastic polymer phase dispersed therein.

[0022] Typically, a propylene polymer comprising at least two propylene polymer fractions (components) is referred to as "multimodal", which propylene polymer is prepared under different polymerization conditions, resulting in different (weight average) molecular weights and / or different comonomer contents in each fraction, preferably by polymerization in a plurality of polymerization stages under different polymerization conditions. The prefix "multi" is related to the number of different polymer fractions the propylene polymer comprises. 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] Unimodal propylene polymers consist of only one fraction.

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

[0025] Visbreaking is a post reactor chemical process used to modify semi-crystalline polymers such as propylene polymers. During the visbreaking process, the propylene polymer backbone is degraded, for example by beta scission degradation with peroxides such as organic peroxides. Degradation is generally used to increase melt flow rate and narrow molecular weight distribution.

[0026] Unless otherwise stated, the following amounts are expressed as weight percent (wt %). DETAILED DESCRIPTION

[0027] Polypropylene composition

[0028] One aspect of the present invention relates to a polypropylene composition comprising:

[0029] (A) 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, of a copolymer of propylene with comonomer units selected from ethylene and α-olefins having 4 to 12 carbon atoms,

[0030] The total amount of comonomer units of the copolymer of propylene and comonomer units is from 10.0 to 16.0 wt%, preferably from 11.0 to 15.0 wt%, most preferably from 12.0 to 14.0 wt%, based on the total amount of monomer units of the propylene copolymer (A);

[0031] The melt flow rate MFR2 of the copolymer of propylene and comonomer units is 0.5 to 2.5 g / 10 min, preferably 0.8 to 2.3 g / 10 min, more preferably 1.0 to 2.0 g / 10 min, most preferably 1.2 to 1.7 g / 10 min;

[0032] the total amount of xylene cold soluble (XCS) fraction of the copolymer of propylene and comonomer units is from 25.0 to 50.0 wt.-%, preferably from 27.5 to 45.0 wt.-%, more preferably from 30.0 to 42.5 wt.-%, most preferably from 32.5 to 40.0 wt.-%, based on the total weight of the propylene copolymer (A); and

[0033] (B) 1.0 to 20.0 wt.-%, preferably 2.5 to 17.5 wt.-%, most preferably 5.0 to 15.0 wt.-%, based on the total weight of the polypropylene composition, of an ethylene-butyl acrylate copolymer, wherein the ethylene-butyl acrylate copolymer has a butyl acrylate content in the range of 15.0 to 40.0 wt.-%, more preferably in the range of 20.0 to 35.0 wt.-%, most preferably in the range of 25.0 to 30.0 wt.-%, based on the total weight of the ethylene-butyl acrylate copolymer.

[0034] The polypropylene composition preferably comprises a copolymer of propylene and a comonomer unit (A) selected from ethylene and an α-olefin having 4 to 12 carbon atoms, wherein the content of the copolymer (A) is 80.0 to 99.0 wt%, preferably 82.5 to 97.2 wt%, most preferably 85.0 to 95.0 wt%, and an ethylene-butyl acrylate copolymer (B) is 1.0 to 20.0 wt%, preferably 2.5 to 17.5 wt%, most preferably 5.0 to 15.0 wt%, all contents based on the total weight of the polypropylene composition.

[0035] The polypropylene composition may further comprise polymer components different from components (A) and (B), preferably in an amount of 0.0 to 10.0 wt.-% (based on the total amount of the polypropylene composition).

[0036] In a preferred embodiment the polymer component of the polypropylene composition consists of components (A) and (B).

[0037] In addition to these polymer components, the polypropylene composition may also contain one or more additives in an amount of 0.0 to 5.0 wt % (based on the total amount 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, for example, as described in Hans Zweifel's "Handbook of Plastic Additives", 6th edition, 2009 (pp. 1141 to 1190).

[0038] Typically, these additives are added to each individual component in an amount of 1 to 50,000 ppm.

[0039] One or more additives may be added to the polymer components during the mixing step.

[0040] Thus, one or more additives may be added to the polymer component in the form of a masterbatch, wherein the one or more additives are mixed with a carrier polymer in concentrated amounts. Any optional carrier polymer is calculated as an additive based on the total amount of the propylene copolymer composition.

[0041] Preferably, the total amount of units derived from ethylene in the polypropylene composition is 10.0 to 25.0 wt.-%, more preferably 12.5 to 22.5 wt.-%, most preferably 15.0 to 20.0 wt.-%, based on the total amount of monomer units in the polypropylene composition.

[0042] Furthermore, preferably the total amount of propylene derived units in the polypropylene composition is 72.5 to 87.5 wt.-%, more preferably 75.0 to 85.0 wt.-%, most preferably 77.5 to 82.5 wt.-%, based on the total amount of monomer units in the polypropylene composition.

[0043] Furthermore, preferably the total amount of units derived from butyl acrylate in the polypropylene composition is 0.1 to 10.0 wt%, more preferably 0.5 to 7.5 wt%, most preferably 1.0 to 5.0 wt%, based on the total amount of monomer units in the polypropylene composition.

[0044] The total amount of xylene cold soluble (XCS) fraction of the polypropylene composition is preferably 30.0 to 55.0 wt.-%, more preferably 32.5 to 52.5 wt.-%, more preferably 34.0 to 50.0 wt.-%, most preferably 36.0 to 47.5 wt.-%, based on the total weight of the polypropylene composition.

[0045] The total amount of units derived from ethylene in the xylene cold soluble (XCS) fraction is preferably from 25.0 to 45.0 wt.-%, based on the total amount of monomer units in the xylene cold soluble (XCS) fraction, more preferably from 27.5 to 40.0 wt.-%, most preferably from 30.0 to 37.5 wt.-%.

[0046] Further, the total amount of units derived from propylene in the xylene cold soluble (XCS) fraction is preferably 50.0 to 73.0 wt. %, more preferably 52.5 to 70.0 wt. %, most preferably 55.0 to 65.0 wt. %, based on the total amount of monomer units in the xylene cold soluble (XCS) fraction.

[0047] Furthermore, the total amount of units derived from butyl acrylate in the xylene cold soluble (XCS) fraction is preferably 0.5 to 12.5 wt. %, more preferably 1.0 to 10.0 wt. %, most preferably 2.0 to 7.5 wt. %, based on the total amount of monomer units in the xylene cold soluble (XCS) fraction.

[0048] Furthermore, the intrinsic viscosity of the xylene cold soluble (XCS) fraction (measured in decalin) is preferably from 150 to 300 cm 3 / g, preferably 175 to 275 cm 3 / g, most preferably 200 to 250cm 3 / g.

[0049] Furthermore, the weight average molecular weight Mw of the xylene cold soluble (XCS) fraction is preferably from 150,000 to 300,000 g / mol, more preferably from 175,000 to 275,000 g / mol, most preferably from 200,000 to 250,000 g / mol.

[0050] Furthermore, the polydispersity index of the xylene cold soluble (XCS) fraction (ie the ratio of weight average molecular weight to number average molecular weight Mw / Mn) is preferably from 4.5 to 13.0, preferably from 4.7 to 12.5, most preferably from 5.0 to 12.0.

[0051] Furthermore, the total amount of cold xylene insoluble (XCI) fraction of the polypropylene composition is preferably 45.0 to 70.0 wt.-%, more preferably 47.5 to 67.5 wt.-%, even more preferably 50.0 to 66.0 wt.-%, most preferably 52.5 to 64.0 wt.-%, based on the total weight of the polypropylene composition.

[0052] In the polypropylene composition the xylene cold soluble (XCS) fraction and the xylene cold insoluble (XCI) fraction together make up 100 wt.-% of the polypropylene composition.

[0053] The total amount of units derived from ethylene in the cold xylene insoluble (XCI) fraction is preferably 3.5 to 20.0 wt.-%, more preferably 5.0 to 17.5 wt.-%, most preferably 6.0 to 15.0 wt.-%, based on the total amount of monomer units in the cold xylene insoluble (XCI) fraction.

[0054] Furthermore, the total amount of units derived from propylene in the cold xylene insoluble (XCI) fraction is preferably 80.0 to 96.5 wt%, more preferably 82.0 to 95.0 wt%, most preferably 84.0 to 94.0 wt%, based on the total amount of monomer units in the cold xylene insoluble (XCI) fraction.

[0055] Furthermore, the total amount of units derived from butyl acrylate in the cold xylene insoluble (XCI) fraction is preferably 0 to 2.5 wt %, more preferably 0 to 2.0 wt %, most preferably 0 to 1.5 wt %, based on the total amount of monomer units in the cold xylene insoluble (XCI) fraction.

[0056] Furthermore, the intrinsic viscosity of the cold xylene insoluble (XCI) fraction (measured in decalin) is preferably from 175 to 350 cm 3 / g, preferably 200 to 325cm 3 / g, most preferably 225 to 300cm 3 / g.

[0057] Furthermore, the weight average molecular weight Mw of the cold xylene insoluble (XCI) fraction is preferably from 250,000 to 400,000 g / mol, more preferably from 275,000 to 375,000 g / mol, most preferably from 300,000 to 350,000 g / mol.

[0058] Furthermore, the polydispersity index of the cold xylene insoluble (XCI) fraction (ie, the ratio of weight average molecular weight to number average molecular weight, Mw / Mn) is preferably from 3.0 to 9.0, preferably from 3.7 to 8.0, and most preferably from 4.0 to 7.5.

[0059] 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, most preferably in the range of 1.0 to 1.4.

[0060] The melt flow rate MFR2 of the polypropylene composition is preferably from 0.5 to 7.5 g / 10 min, more preferably from 0.8 to 7.0 g / 10 min, more preferably from 1.0 to 6.5 g / 10 min, most preferably from 1.2 to 6.0 g / 10 min.

[0061] The flexural modulus of the polypropylene composition is preferably from 150 MPa to 350 MPa, more preferably from 175 MPa to 335 MPa, most preferably from 200 MPa to 315 MPa.

[0062] Preferably, the polypropylene composition has a Charpy notched impact strength at 23°C of 50 to 110 kJ / m 2 , more preferably 60 to 100 kJ / m 2 , most preferably 65 to 95 kJ / m 2 .

[0063] Furthermore, the Charpy notched impact strength of the polypropylene composition at -20°C is preferably 4.0 to 25.0 kJ / m 2 , more preferably 5.5 to 20.0 kJ / m 2 , most preferably 7.0 to 15.0 kJ / m 2 .

[0064] Furthermore, the polypropylene composition has a melting temperature Tm of 140 to 159 °C, preferably of 143 to 157 °C, most preferably of 145 to 153 °C.

[0065] Furthermore, the polypropylene composition preferably has a crystallization temperature Tc of 85 to 130 °C, more preferably 87 to 128 °C, most preferably 90 to 125 °C.

[0066] 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, most preferably in the range of 27 to 55°C.

[0067] The polypropylene composition preferably has at least two glass transition temperatures. The two glass transition temperatures are attributable to a matrix phase (Tg(matrix)) and an elastomeric phase (Tg(EP)).

[0068] Furthermore, the polypropylene composition preferably has a glass transition temperature Tg(matrix) attributed 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, most preferably in the range of -5.0 to -11.0 °C.

[0069] Furthermore, the polypropylene composition preferably has a glass transition temperature due to the elastomeric phase Tg(EP) of -40.0 to -55.0 °C, preferably -42.5 to -52.5 °C, most preferably -45.0 to -50.0 °C.

[0070] Preferably, the shear thinning index SHI of the polypropylene composition is 1 / 100 It is 2.5 to 20.0, more preferably 5.0 to 17.5, most preferably 7.5 to 15.0.

[0071] Furthermore, the polydispersity index PI of the polypropylene composition is preferably between 1.0 and 4.5 s -1 , more preferably 1.5 to 4.0s -1 , most preferably 2.0 to 3.5s -1 .

[0072] 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.

[0073] The polypropylene composition is preferably not visbroken.

[0074] It is preferred that the polypropylene composition does not comprise a dielectric fluid, ie is free of a dielectric fluid, such as described in EP 2739679.

[0075] Hereinafter, copolymers (A) of propylene with comonomer units selected from ethylene and α-olefins having 4 to 12 carbon atoms (abbreviated as “propylene copolymer (A)” or component (A)) and ethylene-butyl acrylate copolymers (B) (abbreviated as component (B)) are described in more detail.

[0076] Propylene copolymer (A)

[0077] The polypropylene composition of the present invention comprises a copolymer (A) of propylene and comonomer units selected from ethylene and α-olefins having 4 to 12 carbon atoms (hereinafter referred to as "propylene copolymer (A)").

[0078] The comonomer units are selected from ethylene and α-olefins having 4 to 12 carbon atoms, such as ethylene, 1-butene, 1-hexene or 1-octene. The propylene copolymer (A) may comprise one type of comonomer units or two or more types of comonomer units, such as two types of comonomer units. The propylene copolymer (A) preferably comprises one type of comonomer units. Ethylene is particularly preferred.

[0079] The total amount of comonomer units, preferably ethylene, in propylene copolymer (A) is preferably 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 propylene copolymer (A).

[0080] Preferably the propylene copolymer (A) is a heterophasic copolymer of propylene.

[0081] The heterophasic propylene copolymer has a matrix phase and an elastomeric phase dispersed in the matrix phase.

[0082] The matrix phase is preferably a propylene random copolymer.

[0083] The comonomer units of the propylene random copolymer of the matrix phase are usually the same as the comonomer units of the above-mentioned propylene copolymer. The comonomer units are preferably selected from ethylene and alpha-olefins with 4 to 12 carbon atoms, such as ethylene, 1-butene, 1-hexene or 1-octene. The propylene random copolymer of the matrix phase can include one type of comonomer unit or two or more types of comonomer units, such as two types of comonomer units. Preferably, the propylene random copolymer of the matrix phase includes one type of comonomer unit. Particularly preferred is ethylene.

[0084] The heterophasic propylene copolymer is typically characterized by comprising at least two glass transition temperatures. The two glass transition temperatures are attributable to a matrix phase (Tg(matrix)) and an elastomeric phase (Tg(EP)).

[0085] The glass transition temperature Tg(matrix) due to the matrix phase of the heterophasic propylene copolymer is preferably from -1.0 to -15.0 °C, preferably from -2.5 to -12.5 °C, most preferably from -5.0 to -10.0 °C.

[0086] Furthermore the heterophasic propylene copolymer preferably has a glass transition temperature due to the elastomeric phase Tg(EP) of -40.0 to -55.0 °C, preferably -42.5 to -52.5 °C, most preferably -45.0 to -50.0 °C.

[0087] In propylene copolymers (A) (e.g. heterophasic propylene copolymers), the matrix phase and the elastomeric phase cannot usually be separated accurately from each other. In order to characterize the matrix phase and the elastomeric phase of heterophasic polypropylene copolymers, several methods are known. One method is to use xylene to extract the part containing the elastomeric phase for the most part, thereby separating the xylene cold solubles (XCS) part from the cold xylene insolubles (XCI) part. The XCS part contains most of the elastomeric phase and only contains a small part of the matrix phase, while the XCI part contains most of the matrix phase and only contains a small part of the elastomeric phase.

[0088] The total amount of xylene cold soluble (XCS) fraction of propylene copolymer (A) is preferably 25.0 to 50.0 wt.-%, more preferably 27.5 to 45.0 wt.-%, more preferably 30.0 to 42.5 wt.-%, most preferably 32.5 to 40.0 wt.-%, based on the total weight of propylene copolymer (A).

[0089] The total amount of comonomer units of the xylene cold soluble (XCS) fraction is preferably from 23.0 to 35.0 wt.-%, preferably ethylene, more preferably from 23.5 to 32.5 wt.-%, most preferably from 24.0 to 30.0 wt.-%, based on the total amount of monomer units in the xylene cold soluble (XCS) fraction.

[0090] In addition, the intrinsic viscosity of the xylene cold soluble (XCS) portion (measured in decalin) is preferably from 150 to 350 cm 3 / g, preferably 200 to 325cm 3 / g, most preferably 225 to 300cm 3 / g.

[0091] Furthermore, the weight average molecular weight Mw of the xylene cold soluble (XCS) fraction is preferably from 185,000 to 350,000 g / mol, more preferably from 200,000 to 325,000 g / mol, most preferably from 210,000 to 315,000 g / mol.

[0092] Furthermore, the polydispersity index of the xylene cold soluble (XCS) fraction (ie the ratio of weight average molecular weight to number average molecular weight Mw / Mn) is preferably from 3.5 to 8.5, preferably from 3.7 to 8.0, most preferably from 4.0 to 7.5.

[0093] Further, the total amount of the cold xylene insoluble (XCI) fraction of the propylene copolymer (A) is preferably from 50.0 to 75.0 wt.-%, more preferably from 55.0 to 72.5 wt.-%, still more preferably from 57.5 to 70.0 wt.-%, most preferably from 60.0 to 67.5 wt.-%, based on the total weight of the propylene copolymer (A).

[0094] The amount of comonomer units (preferably ethylene) in the xylene insoluble (XCI) fraction is preferably 3.0 to 9.0 wt. %, preferably 4.0 to 8.5 wt. %, most preferably 4.5 to 7.5 wt. %, based on the total amount of monomer units in the xylene insoluble (XCI) fraction.

[0095] Furthermore, the intrinsic viscosity of the cold xylene insoluble (XCI) fraction (measured in decalin) is preferably from 185 to 350 cm 3 / g, preferably 220 to 325cm 3 / g, most preferably 210 to 300 cm 3 / g.

[0096] In addition, the weight average molecular weight Mw of the cold xylene insoluble (XCI) fraction is preferably 225,000 to 450,000 g / mol, more preferably 240,000 to 425,000 g / mol, most preferably 260,000 to 400,000 g / mol.

[0097] Furthermore, the polydispersity index of the cold xylene insoluble (XCI) fraction (ie the ratio of weight average molecular weight to number average molecular weight Mw / Mn) is preferably from 3.5 to 7.5, preferably from 3.7 to 7.0, and most preferably from 4.0 to 6.5.

[0098] The ratio of the intrinsic viscosity of the XCI fraction to the XCS fraction of the propylene copolymer is preferably from 0.9 to 1.5, more preferably from 1.0 to 1.4, most preferably from 1.0 to 1.3.

[0099] The melt flow rate MFR2 of the propylene copolymer (A) is preferably from 0.5 to 2.5 g / 10 min, preferably from 0.8 to 2.3 g / 10 min, more preferably from 1.0 to 2.0 g / 10 min, most preferably from 1.2 to 1.7 g / 10 min.

[0100] The flexural modulus of the propylene copolymer (A) is preferably from 130 MPa to 400 MPa, more preferably from 150 MPa to 390 MPa, most preferably from 175 MPa to 380 MPa.

[0101] Preferably, the propylene copolymer (A) has a Charpy notched impact strength at 23°C of 50 to 110 kJ / m 2 , more preferably 65 to 100 kJ / m 2 , most preferably 75 to 95 kJ / m 2 .

[0102] Furthermore, the propylene copolymer (A) preferably has a Charpy notched impact strength at -20°C of 5.0 to 10.0 kJ / m 2 , more preferably 5.5 to 9.0 kJ / m2 , most preferably 6.0 to 8.0 kJ / m 2 .

[0103] Furthermore, the propylene copolymer (A) has a melting temperature Tm of 140 to 159 °C, preferably 143 to 157 °C, most preferably 145 to 153 °C.

[0104] Furthermore, the propylene copolymer (A) has a crystallization temperature Tc of 85 to 130 °C, preferably 87 to 128 °C, most preferably 90 to 125 °C.

[0105] The difference between the melting temperature and the crystallization temperature, Tm-Tc, is preferably from 20 to 65°C, preferably from 25 to 60°C, most preferably from 27 to 55°C.

[0106] The intrinsic viscosity (measured in decalin) of the propylene copolymer (A) is preferably from 185 to 350 cm 3 / g, preferably 200 to 325cm 3 / g, most preferably 210 to 300 cm 3 / g.

[0107] The propylene copolymer (A) may be polymerized in a sequential multistage polymerization process, i.e. in a polymerization process of two or more polymerization reactors connected in series. Preferably, in a sequential multistage polymerization process, two or more, more preferably three or more (e.g. three or four) polymerization reactors are connected in series. The term "polymerization reactor" shall mean that the main polymerization takes place. Thus, if the process consists of four polymerization reactors, this definition does not exclude the option that the overall process includes a prepolymerization step, e.g. in a prepolymerization reactor.

[0108] When the propylene copolymer (A) is a heterophasic propylene copolymer the matrix phase of the heterophasic propylene copolymer is polymerized in a first polymerisation reactor to produce a unimodal matrix phase or in a first and a second polymerisation reactor to produce a multimodal matrix phase.

[0109] The elastomeric phase of the heterophasic propylene copolymer is preferably polymerized in the presence of the matrix phase in one or two subsequent polymerization reactors to produce a unimodal elastomeric phase or a multimodal elastomeric phase.

[0110] Preferably, the polymerization reactor is selected from a slurry phase reactor (eg a loop reactor) and / or a gas phase reactor (eg a fluidized bed reactor), more preferably the polymerization reactor is selected from a loop reactor and a fluidized bed reactor.

[0111] A preferred sequential multistage polymerization process is a "loop-gas phase" process, such as the process developed by Borealis A / S of Denmark (known as Technology), for example, is described in the patent literature, for example in EP 0887379, WO 92 / 12182, WO 2004 / 000899, WO 2004 / 111095, WO 99 / 24478, WO 99 / 24479 or WO 00 / 68315.

[0112] Another suitable slurry-gas phase process is LyondellBasell's Craftsmanship.

[0113] Suitable sequential polymerization processes for polymerizing the propylene copolymer (A), preferably a heterophasic propylene copolymer, are disclosed for example in EP 1 681 315 A1 or WO 2013 / 092620 A1.

[0114] The propylene copolymer (A), preferably a heterophasic propylene copolymer, can be polymerized in the presence of a Ziegler-Natta catalyst or a single site catalyst.

[0115] 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.

[0116] Suitable single-site catalysts are disclosed, for example, in WO 2006 / 097497, WO 2011 / 076780 or WO 2013 / 007650.

[0117] The propylene copolymer (A) has preferably not been subjected to a visbreaking step as described in WO 2013 / 092620 A1.

[0118] Heterophasic propylene copolymer resins suitable for use as propylene copolymer (A) are also commercially available. These resins usually already have stabilizer packages added. Therefore, when using commercially available resins as propylene copolymers, the addition of the above mentioned additives may have to be adjusted depending on the additives already present.

[0119] Ethylene copolymer (B)

[0120] The polypropylene composition of the present invention comprises an ethylene-butyl acrylate copolymer (B).

[0121] As will be appreciated by those skilled in the art, ethylene-butyl acrylate copolymers comprise ethylene monomers and butyl acrylate comonomers. No other comonomers may be present.

[0122] The ethylene-butyl acrylate copolymer (B) has a butyl acrylate content of 15.0 to 40.0 wt % as measured by FT-IR. More preferably, the ethylene-butyl acrylate copolymer (B) has a butyl acrylate content of 20.0 to 35.0 wt % as measured by FT-IR, and most preferably, has a butyl acrylate content of 25.0 to 30.0 wt % as measured by FT-IR.

[0123] Furthermore, the density of the ethylene-butyl acrylate copolymer (B) measured according to ISO1183 is preferably 900 to 950 kg / m 3 , more preferably 910 to 945 kg / m 3 , most preferably 920 to 940 kg / m 3 .

[0124] Furthermore, the melt flow rate MFR2 of the ethylene-butyl acrylate copolymer (B) measured at 190° C. and 2.16 kg according to ISO 1133 is preferably 1.0 to 20.0 g / 10 min, preferably 2.0 to 15.0 g / 10 min, most preferably 3.0 to 10.0 g / 10 min.

[0125] Furthermore, the melting temperature Tm of the ethylene-butyl acrylate copolymer (B) as measured by differential scanning calorimetry is preferably from 60 to 110°C, preferably from 70 to 100°C, most preferably from 80 to 95°C.

[0126] The ethylene-butyl acrylate copolymer (B) can be produced by free radical polymerization in a high pressure polymerization process.

[0127] Ethylene-butyl acrylate copolymer resins suitable for use as ethylene-butyl acrylate copolymer (B) are also available on the market. These resins usually have stabilizer packages added. Therefore, when using commercially available resins as ethylene-butyl acrylate copolymer (B), the addition of the above-mentioned additives may have to be adjusted according to the additives already present.

[0128] For the preparation of ethylene-butyl acrylate copolymers, polymerization processes well known to those skilled in the art can be used. Within the scope of the present invention, multimodal (e.g. at least bimodal) polymers can be produced by mixing each component in situ during the polymerization (so-called in situ process) or by mechanically mixing two or more separately produced components in a manner known in the art.

[0129] Products

[0130] In another aspect the present invention also relates to an article comprising the polypropylene composition as defined above or below.

[0131] The article is preferably a cable comprising an insulation layer comprising the polypropylene composition as described above or below.

[0132] The cable typically comprises at least one conductor and at least one insulation layer comprising a polypropylene composition as described above or below.

[0133] In the above and below of this article, the term "conductor" means that the conductor includes one or more wires. The wire can be used for any purpose, such as optical fiber, telecommunications or wires. 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 works at any voltage, usually at a voltage higher than 1kV. The voltage applied to the power cable can be an alternating current (AC), a direct current (DC) or a transient (pulse). The polypropylene composition of the present invention is very suitable for power cables, especially power cables (medium voltage (MV) cables) with an operating voltage of 6kV to 36kV and power cables (called high voltage (HV) cables and extra-high voltage (EHV) cables) with an operating voltage higher than 36kV, and it is well known that EHV cables work at very high voltages. These terms have well-known meanings and indicate the working level of such cables.

[0134] For low voltage applications, the cable system usually consists of a conductor and an insulating layer comprising the above or below polypropylene composition, or consists of a conductor, an insulating layer comprising the above or below polypropylene composition and an additional sheath layer, or consists of a conductor, a semiconducting layer and an insulating layer comprising the above or below polypropylene composition.

[0135] For medium and high voltage applications the cable system usually consists of a conductor, an inner semiconductive layer, an insulating layer comprising the above or below mentioned polypropylene composition and an outer semiconductive layer, which is optionally covered by an additional sheath layer.

[0136] The semiconductive layer preferably comprises, more preferably consists of, a thermoplastic polyolefin composition, preferably a polyethylene composition or a polypropylene composition, said thermoplastic polyolefin composition containing a sufficient amount of conductive solid filler, preferably carbon black. Preferably, the thermoplastic polyolefin composition of the semiconductive layer is a polypropylene composition, more preferably a polypropylene composition comprising a heterophasic propylene copolymer as polymer component. It is particularly preferred that the thermoplastic polyolefin composition of at least one semiconductive layer of the cable, preferably both semiconductive layers, comprises the same propylene copolymer as the insulating layer, i.e. a propylene copolymer as described above or below.

[0137] The cable comprising an insulation layer comprising the polypropylene composition according to the present invention as described above shows the alternating current breakdown strength in the form of Weibull alpha value and Weibull beta value.

[0138] The Weibull alpha value of the cable is preferably from 35.0 to 65.0 kV / mm, preferably from 40.0 to 65.0 kV / mm, most preferably from 44.0 to 65.0 kV / mm, when measured using a 10 kV cable.

[0139] Furthermore, the Weibull beta value of the cable is preferably from 15.0 to 250.0, preferably from 20.0 to 250.0, and most preferably from 22.0 to 250.0, when measured with a 10 kV cable.

[0140] Thus, the insulation layer comprising the polypropylene composition according to the present invention can be used in medium and high voltage cables.

[0141] Another aspect of the present invention relates to the use of the polypropylene composition as described above or below as cable insulation material for medium and high voltage cables.

[0142] The medium voltage and high voltage cables preferably meet all performance requirements of cables as described above and below.

[0143] Beneficial effects of the present invention:

[0144] The polypropylene composition exhibits a good balance of properties, including high flexibility, good mechanical strength, good impact properties, and high crystallization temperature and melting temperature, and can be used as a cable insulation material, such as for medium voltage and high voltage cables at high operating temperatures. By adding ethylene-butyl acrylate copolymer (B) to the polypropylene composition, the flexibility and impact properties can be further improved, thereby maintaining high crystallization temperature and melting temperature.

[0145] The polypropylene composition can be easily compounded to prepare the insulation layer without increasing the melt flow rate by visbreaking the composition or the propylene copolymer (A).

[0146] The cable comprising the insulating layer comprising the polypropylene composition of the present invention unexpectedly exhibits good AC breakdown strength (in the form of Weibull α value and Weibull β value). Therefore, adding the ethylene-butyl acrylate copolymer (B) to the polypropylene composition can further improve the AC breakdown strength compared to the polypropylene composition comprising only the propylene copolymer (A) as the polymer compound.

[0147] Good AC breakdown strength (in the form of Weibull alpha and Weibull beta values) can be obtained without the addition of dielectric fluids such as those described in EP2739679.

[0148] Example

[0149] Unless otherwise defined, the following definitions of terms and assay methods apply to the above general description of the invention as well as to the following examples.

[0150] 1. Measurement method

[0151] a) Melt flow rate (MFR2)

[0152] Melt flow rate is the amount of polymer (in grams) that a test apparatus standardized to ISO 1133 or ASTM D 1238 will extrude in 10 minutes at a specific temperature and a specific load.

[0153] The melt flow rate MFR2 of the propylene based polymer and the polypropylene composition is measured according to ISO 1133 at 230°C and a load of 2.16 kg.

[0154] The melt flow rate MFR2 of the ethylene-based polymer and the polyethylene composition is measured according to ISO 1133 at 190°C and a load of 2.16 kg.

[0155] Melt flow rate can also be measured according to ASTM D1238.

[0156] b) Density

[0157] Density was measured according to ISO 1183. Sample preparation was done by compression molding according to ISO 17855-2.

[0158] Density can also be measured according to ASTM D 792.

[0159] c) Comonomer content

[0160] Method I (HECO)

[0161] Quantification of comonomer content of poly(propylene-co-ethylene) copolymers

[0162] Quantitative analysis in solution was recorded using a Bruker Avance NEO 400 NMR spectrometer. 13 C{ 1 H}NMR spectrum, 1 H and 13 C operated at 400.15 and 100.62 MHz, respectively. All spectra were acquired using 13C optimized 10 mm extended temperature probe was recorded at 125 °C, and nitrogen was used for all pneumatics. Approximately 200 mg of material was dissolved in 3 ml of 1,2-tetrachloroethane-d2 (TCE-d2) together with chromium-(III)-acetylacetonate (Cr(acac)3) to give a 60 mM relaxation agent solution in solvent {8} and containing approximately 3 mg of BHT (2,6-di-tert-butyl-4-methylphenol CAS 128-37-0). To ensure a homogeneous solution, the NMR tube was further heated in a rotary oven for at least 1 h after initial sample preparation in a heating block. After insertion into the magnet, the tube was rotated at 10 Hz. This setup was chosen primarily because of the high resolution and quantitative requirements for accurate ethylene content quantification. Standard single pulse excitation was employed without NOE, using an optimized tip angle, 1 s recycle delay, and a two-stage WALTZ16 decoupling scheme {3,4}. A total of 6144 (6k) transients were acquired for each spectrum.

[0163] A proprietary computer program was used to quantify 13 C{ 1 The H} NMR spectra were processed, integrated, and the relevant quantitative properties were determined from the integrals. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. This approach allows for comparable referencing even when this building block is not present. Characteristic signals corresponding to ethylene incorporation were observed {7}.

[0164] Using the method of Wang et al. {6}, by 13 C{ 1 The comonomer fraction is quantified by integrating multiple signals across the spectral region of the {H} spectrum. This approach was chosen due to its robustness and ability to account for the presence of regio defects when required. The integration region was slightly adjusted to improve applicability to the entire range of comonomer content encountered.

[0165] 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 approach reduces the overestimation of ethylene content in such systems and is achieved by reducing the number of sites used to determine absolute ethylene content to:

[0166] E=0.5(Sββ+Sβγ+Sβδ+0.5(Sαβ+Sαγ))

[0167] Using this set of sites, the corresponding integral equation becomes:

[0168] E=0.5(I H +I G +0.5(I C +ID ))

[0169] The same symbols as in Wang et al. {6} are used. The formula used for absolute propylene content is not modified.

[0170] The comonomer mole percentage is calculated by the following mole fractions:

[0171] E[mol%]=100*fE

[0172] The weight percent of the comonomer is calculated from the mole fraction:

[0173] E[weight%]=100*(fE*28.06) / ((fE*28.06)+((1-fE)*42.08))

[0174] References:

[0175] 1) Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443.

[0176] 2) Busico, V., Cipullo, R., Monaco, G., Vacatello, M., Segre, AL, Macromolecules 30 (1997) 6251.

[0177] 3) Zhou, Z., Kuemmerle, R., Qiu,

[0178] 4) Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128.

[0179] 5)Resconi,L.,Cavallo,L.,Fait,A.,Pimontesi,F.,Chem.Rev.2000,100,1253.

[0180] 6) Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157.

[0181] 7)Cheng, HN, Macromolecules 17 (1984), 1950.

[0182] 8)Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475.

[0183] 9) Kakugo, M., Naito, Y., Mizunuma, K., Miyatake, T. Macromolecules 15 (1982) 1150.

[0184] 10) Randall, J. Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.

[0185] 11) Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253.

[0186] Method II (composite materials)

[0187] Quantification of BA content

[0188] Quantitative analysis in solution was recorded using a Bruker Avance III 400 NMR spectrometer. 1 H NMR spectroscopy, 1 H and 13 C operated at 400.15 and 100.62 MHz, respectively. All spectra were acquired using 13 C optimized 10 mm selective excitation probe was recorded at 125 °C, and nitrogen was used for all pneumatics. About 200 mg of material was dissolved in 1,2-tetrachloroethane-d2 (TCE-d2), and about 3 mg of BHT (CAS 128-37-0) was used as a stabilizer.

[0189] Standard single pulse excitation was employed, using a 30 degree pulse, a 3 second relaxation delay and 10 Hz sample rotation. Four virtual scans were used, acquiring 64 transients per spectrum. A total of 32k data points were collected per FID with a dwell time of 60 μs, which corresponds to a spectral window of approximately 20 ppm. The FID was then zero-filled to 64k data points and an exponential window function with 0.3 Hz line broadening was applied.

[0190] Processing, integration and quantification 1 H NMR spectroscopy and determination of quantitative properties. All chemical shifts were referenced to the residual protonated solvent signal at 5.95 ppm.

[0191] Characteristic signals corresponding to butyl acrylate and aliphatic entities were observed (AJ Brandolini, DD Hills, "NMR spectra of polymers and polymer additives", Marcel Deker Inc., 2000) and the content was calculated.

[0192] Distribution of BA incorporation

[0193]

[0194] The incorporation of butyl acrylate (BA) was quantified by the integration of the 4.1 ppm signal assigned to the 4BA site, which accounts for the number of reported cores per comonomer in the different sequences:

[0195] BA=I 4BA / 2

[0196] Characteristic signals due to the additional use of BHT as a stabilizer were observed. For the BHT compensation, the integration of the 4.8 ppm signal assigned to the -OH site of BHT was used to account for the number of reported nuclei per molecule:

[0197] BHT=I OH-BHT

[0198] Use bulk aliphatic (I 本体 ) signal to quantify the aliphatic entity content. This integral includes 1BA(3), 2BA(2), 3BA(2), *BA(1), and αBA(2) sites to which butyl acrylate binds as well as the associated sites of BHT. The entity content is calculated from the entity integrals with compensation for the associated BA signal and BHT, taking into account the number of reported nuclei for each entity.

[0199] Ontology=[I 本体 -(21*BHT)-(10*BA)] / 4

[0200] The mole fraction of butyl acrylate in the polymer is calculated as follows:

[0201] fBA=BA / (BA+body)

[0202] The molar percentage content of butyl acrylate is calculated as follows:

[0203] BA[mol%]=100*fBA

[0204] The weight percentage content of butyl acrylate is calculated as follows:

[0205] BA [weight %] = 100 * (fBA * 128.17) / ((fBA * 128.17) + ((1-fBA) * 28.05))

[0206] Quantification of total C2 and C3 content in composite materials

[0207] Quantitative analysis in solution was recorded using a Bruker Avance Neo 400 NMR spectrometer. 13 C{ 1 H}NMR spectrum, 1 H and 13 C were operated at 400.15 and 100.62 MHz, respectively. All spectra were taken using 13 C optimized 10 mm extended temperature probe was recorded at 125 ° C, and all pneumatic components used nitrogen. About 200 mg of material was dissolved in about 3 ml of 1,2-tetrachloroethane-d2 (TCE-d2), and about 3 mg of BHT (2,6-di-tert-butyl-4-methylphenol CAS 128-37-0) and chromium-(III)-acetylacetonate (Cr(acac)3) were dissolved to obtain a 60 mM relaxation agent solution in the solvent as described in G. Singh, A. Kothari, V. Gupta, Polymer Testing 2009, 28(5), 475.

[0208] To ensure that the solution was homogeneous, the NMR tube was further heated in a rotating oven for at least 1 h after initial sample preparation in a heating block. After insertion into the magnet, the tube was rotated at a speed of 10 Hz.

[0209] Standard single pulse excitation was employed without NOE, using an optimized tip angle, 1 second recycle delay, and a two-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.

[0210] Processing, integration and quantification 13 C{ 1 H} NMR spectra and the relevant quantitative properties were determined from the integration. All chemical shifts were indirectly referenced to the central methylene of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent.

[0211] Characteristic signals corresponding to various ethylene incorporations were observed as described in Cheng, HN, Macromolecules 1984, 17, 1950.

[0212] The comonomer fraction was quantified using a comparable triad method for ZN C2C3 copolymers reported in L. Abis, Mackromol. Chem. 187, 1877-1886 (1986). For C2 content, only the total amount from C2C3, EBA copolymers and additional blending components containing C2 can be quantified by using the methylene sequence at 30.0 ppm.

[0213] Allocation table 13 C NMR spectroscopy

[0214]

[0215]

[0216] Triple equation

[0217] Triple sequence Signal / Equation PEP G PEE F EEE D / 2+C / 4 PPP E PPE B–(6*BHT)–((F–C) / 2) EPE A

[0218] After quantifying and normalizing the mole fractions, the amount of C2 and C3 can be calculated by summing the E and P center triplets:

[0219] The sum of the triplets = PEP + PEE + EE + PPP + PPE + EPE

[0220] fmol PEP = PEP / sum of the three mol% PEP = fmol PEP * 100

[0221] fmol PEE = PEE / sum of the three mol% PEE = fmol PEE*100

[0222] fmol EEE = EEE / sum of the triplet mol% EEE = fmol EEE * 100

[0223] fmol PPP = PPP / sum of triplets mol% PPP = fmol PPP * 100

[0224] fmol PPE = PPE / sum of triplets mol% PPE = fmol PPE*100

[0225] fmol EPE = EPE / sum of the three mol% EPE = fmol EPE*100

[0226] C2[mol%]=mol%PEP+mol%PEE+mol%EEE

[0227] C3[mol%]=mol%PPP+mol%PPE+mol%EPE

[0228] The weight percentage of the comonomer is calculated from the mole percentage in the usual manner:

[0229] Weight% C2 = 100*(C2[mol%]*28.06) / ((C2[mol%]*28.06)+(C3[mol%]*42.08))

[0230] Weight% C3 = 100*(C3[mol%]*42.08) / ((C2[mol%]*28.06)+(C3[mol%]*42.08))

[0231] By introducing 1 The total amount of C2 and C3 was quantified by the butyl acrylate value calculated by H NMR:

[0232] wt% C2 total = wt% C2*(100-BA[wt%]) / 100

[0233] wt% C3 total = wt% C3*(100 - BA [wt%]) / 100

[0234] Determination of Ethylene-Butyl Acrylate Content in EBA

[0235] The following example illustrates the determination of the polar comonomer content of ethylene-butyl acrylate. The weight percentages can be converted to mole percentages by calculation, which is well documented in the literature.

[0236] Polymer film samples were prepared for FTIR measurements: for ethylene-butyl acrylate with butyl acrylate content > 6 wt %, use a thickness of 0.5 to 0.7 mm, for ethylene-butyl acrylate with butyl acrylate content < 6 wt %, use a thickness of 0.05 to 0.12 mm.

[0237] After FT-IR analysis, the -1 The maximum absorbance of the peak of butyl acrylate>6 wt% minus 3510 cm -1 The baseline absorbance at 2020 cm -1 The maximum absorbance of the polyethylene peak at 2120 cm minus -1 The baseline absorbance value at (A2020-A2120) is then calculated in the conventional manner between (Abutyl acrylate-A3510) and (A2020-A2120), which is well documented in the literature.

[0238] Use 1165cm -1 The maximum absorbance of the peak with comonomer butyl acrylate <6 wt% minus 1865 cm -1 The baseline absorbance at 2660 cm -1 The maximum absorbance of the polyethylene peak at 1865 cm minus -1 The baseline absorbance value at (A2660-A1865) was then calculated and the ratio between (Abutyl acrylate-A1865) and (A2660-A1865) was calculated.

[0239] d) Differential Scanning Calorimetry (DSC) analysis, melting temperature (Tm) and crystallization temperature (Tc):

[0240] The measurements were performed on 5 to 7 mg samples using a TA Instrument Q2000 Differential Scanning Calorimetry (DSC). The DSC was run according to ISO 11357 / Part 3 / Method C2 with a scan rate of 10°C / min in a temperature range of -30°C to +225°C with a heating / cooling / heating cycle.

[0241] The crystallization temperature and the heat of crystallization (Hc) are determined by the cooling step, while the melting temperature and the heat of fusion (Hf) are determined by the second heating step.

[0242] When a sample shows more than two melting temperatures and / or crystallization temperatures, only the main melting temperature (highest Hc) and the main crystallization temperature (highest Hf) are shown in the corresponding table. The difference between the melting temperature and the crystallization temperature (Tm-Tc) is given for the main melting temperature and the main crystallization temperature.

[0243] e) Xylene cold soluble matter (XCS) content

[0244] The amount of xylene solubles in polypropylene is determined according to ISO 16152 (first edition; 2005-07-01).

[0245] A weighed sample is dissolved in hot xylene at reflux at 135°C. The solution is then cooled under controlled conditions and kept at 25°C for 30 minutes to ensure controlled crystallization of the insoluble fraction. This insoluble fraction is then separated by filtration. The xylene evaporates from the filtrate, leaving the soluble fraction as a residue. The percentage of this fraction is determined gravimetrically.

[0246]

[0247] in

[0248] m0 is the mass of the sample test portion weighed, in grams

[0249] m1 is the mass of the residue in grams

[0250] v0 is the original volume of the solvent taken

[0251] v1 is the sampling volume used for the measurement.

[0252] f) Glass transition temperature (Tg)

[0253] The glass transition temperature Tg was determined by dynamic mechanical analysis (DMTA) according to ISO 6721-7. The measurement was performed on compression molded samples (40×10×1 mm 3 ) in the temperature range of -100°C to +150°C, at a heating rate of 2°C / min and a frequency of 1 Hz. Tg is determined from the loss angle (tan(δ)) curve.

[0254] g) Intrinsic viscosity (IV)

[0255] Reduced viscosity (also called viscosity number) η red The intrinsic viscosity IV is determined according to ISO 1628-3: "Determination of the viscosity of polymers in dilute solution using a capillary viscometer".

[0256] The relative viscosity of the diluted polymer solution at a concentration of 1 mg / ml and the pure solvent (decalin stabilized with 200 ppm 2,6-bis(1,1-dimethylethyl)-4-methylphenol) was measured using an automatic capillary viscometer (Lauda PVS1) equipped with 4 Ubbelohde capillaries placed in a thermostatic bath filled with silicone oil. The thermostatic bath temperature was maintained at 135°C. The sample was dissolved under constant stirring until it was completely dissolved (usually within 90 minutes).

[0257] The elution time of the polymer solution and the pure solvent was measured repeatedly until three consecutive readings differed by no more than 0.2 seconds (standard deviation).

[0258] The relative viscosity of a polymer solution is determined by the ratio of the average elution times (in seconds) of the polymer solution and the solvent:

[0259]

[0260] Reduced viscosity (η red ) is calculated using the following formula:

[0261]

[0262] Where C is the concentration of the polymer solution at 135°C: m is the mass of the polymer, V is the volume of the solvent, and γ is the ratio of the density of the solvent at 20°C and 135°C (γ = ρ 20 / ρ 135 =1.107).

[0263] The intrinsic viscosity IV is calculated from a single concentration measurement using the Schulz-Blaschke equation:

[0264]

[0265] where K is a coefficient that depends on polymer structure and concentration. To calculate an approximate value for IV, K = 0.27.

[0266] h) Average molecular weight, polydispersity (Mn, Mw, Mz, MWD) determined by gel permeation chromatography (GPC)

[0267] For GPC analysis, the column set was calibrated using universal calibration (according to ISO 16014-2:2003) with 19 narrow molecular weight distribution polystyrene (PS) standards ranging from 0.5 kg / mol to 11500 kg / mol. The PS standards were dissolved at 160 °C for 15 min or at room temperature at a concentration of 0.2 mg / ml for molecular weights greater than or equal to 899 kg / mol and 1 mg / ml for molecular weights less than 899 kg / mol. The polystyrene peak molecular weights were converted to polyethylene molecular weights using the Mark Houwink equation and the following Mark Houwink constants:

[0268] K PS =19x10 -3 ml / g,α PS =0.655

[0269] K PE =39x10 -3 ml / g,α PE =0.725

[0270] A third-order polynomial fit was used to fit the calibration data.

[0271] The molecular weight averages (Mz, Mw and Mn), the molecular weight distribution (MWD) and its breadth (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 formula:

[0272]

[0273] i) Flexural modulus

[0274] The flexural modulus is measured according to ISO 178 method A (3-point bending test) on a 80 mm x 10 mm x 4 mm sample. According to the standard, a test speed of 2 mm / min and a span length of 16 times the thickness are used. The test temperature is 23 ± 2 ° C. Injection molding is carried out according to ISO 19069-2, and a melt temperature of 230 ° C is used for all materials (regardless of the material melt flow rate).

[0275] j) Charpy notched impact strength

[0276] Charpy notched impact strength was measured according to ISO 179-1 / 1eA on notched 80 mm x 10 mm x 4 mm specimens (samples were prepared according to ISO 179-1 / 1eA). The test temperature was 23 ± 2 °C or -20 ± 2 °C. Injection molding was performed according to ISO 19069-2, using a melt temperature of 230 °C for all materials (regardless of the material melt flow rate).

[0277] k) Rheological measurements

[0278] Dynamic shear measurement (frequency sweep measurement)

[0279] The polymer compositions or melts of the polymers provided above or below were characterized by dynamic shear measurements in accordance with ISO standards 6721-1 and 6721-10. The measurements were performed on an Anton Paar MCR501 stress-controlled rotational rheometer equipped with a 25 mm parallel plate geometry. The measurements were performed on compression molded plates, using a nitrogen atmosphere and setting the strain in the linear viscoelastic range. The oscillatory shear test was performed at 190° C., with an applied frequency range of 0.01 to 600 rad / s and a gap of 1.3 mm.

[0280] In a dynamic shear experiment, the probe is subjected to 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 is subjected to a sinusoidal strain, which can be expressed as:

[0281] γ(t)=γ0sin(ωt) (1)

[0282] If the applied strain is in the linear viscoelastic range, the resulting sinusoidal stress response can be given by:

[0283] σ(t)=σ0sin(ωt+δ) (2)

[0284] in

[0285] σ0 and γ0 are stress amplitude and strain amplitude respectively

[0286] ω is the angular frequency

[0287] σ is the phase shift (loss angle between the applied strain response and the stress response)

[0288] t is time

[0289] Dynamic test results are usually expressed in terms of several different rheological functions, namely shear storage modulus G', shear loss modulus G", complex shear modulus G*, complex shear viscosity η*, dynamic shear viscosity η', multiphase component of complex shear viscosity η", and loss tangent tanδ, which can be expressed as follows:

[0290]

[0291] G * =G′+iG″[Pa] (5)

[0292] η * =η′-iη″[Pa·s] (6)

[0293]

[0294] The so-called shear thinning index (related to MWD and independent of Mw) is determined as shown in Equation 9.

[0295]

[0296] For example, SHI (2 / 100) It is defined as the complex viscosity value (in Pa·s) determined when G* is equal to 1 kPa divided by the complex viscosity value (in Pa·s) determined when G* is equal to 100 kPa.

[0297] The values ​​of storage modulus (G'), loss modulus (G"), complex modulus (G*), and complex viscosity (η*) are all functions of frequency (ω).

[0298] So, 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, 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.

[0299] The polydispersity index PI is defined by Equation 10.

[0300]

[0301] where ω COP is the crossover angular frequency, determined by the angular frequency at which the storage modulus G' equals the loss modulus G".

[0302] These values ​​were determined by means of a single-point interpolation procedure defined in the Rheoplus software. In cases where a 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 ​​into x values ​​of parameter" and "Logarithmic interpolation type" in Rheoplus were applied.

[0303] refer to:

[0304] [1]Rheological characterization of polyethylene fractions” Heino, EL, Lehtinen, A., Tanner J., J.,Neste Oy,Porvoo,Finland,Theor.Appl.Rheol.,Proc.Int.Congr.Rheol,11th(1992),1,360-362

[0305] [2]The influence of molecular structure on some rheologicalproperties of polyethylene", Heino, EL, Borealis Polymers Oy, Porvoo, Finland, Annual Transactions of the Nordic Rheology Society, 1995.).

[0306] [3]Definition of terms relating to the non-ultimate mechanicalproperties of polymers,Pure&Appl.Chem.,Vol.70,No.3,pp.701-754,1998.

[0307] l) Alternating current breakdown strength (ACBD)

[0308] The AC breakdown test is performed according to CENELEC HD 605 5.4.15.3.4 for 6 / 10kV cables. Therefore, the cable is cut into six test samples with an effective length of 10m (with terminations in addition). The samples are subjected to breakdown tests using a 50Hz AC step test at ambient temperature, as follows:

[0309] ·Starting from 18kV for 5 minutes

[0310] The voltage is increased in steps of 6 kV every 5 minutes until breakdown occurs

[0311] The calculation of the Weibull parameters for the six breakdown value (conductor stress, i.e., electric field in the inner semiconducting layer) data sets follows the least squares regression procedure described in IEC62539 (2007). The Weibull α parameter in this paper refers to the scale parameter of the Weibull distribution, i.e., the voltage at which the failure probability is 0.632. The Weibull β value refers to the shape parameter.

[0312] 2. Propylene copolymer composition

[0313] The following resins were used to prepare the propylene copolymer compositions of the examples:

[0314] a) Polymerization of heterophasic propylene copolymer powder A1

[0315] ·catalyst

[0316] The catalyst used in the polymerization of the heterophasic propylene copolymer powder A1 is a Ziegler-Natta catalyst which is described in patent publications EP 491566, EP 591224 and EP 586390. Triethylaluminium (TEAL) was used as cocatalyst and dicyclopentyldimethoxysilane (D-donor) as donor.

[0317] Polymerization of heterophasic propylene copolymer powder

[0318] Heterophasic propylene copolymer powder A1 in Borstar TM The plant was produced in the presence of the above polymerization catalyst using a liquid phase loop reactor and two gas phase reactors connected in series under the conditions shown in Table 1. The first reaction zone was a loop reactor, and the second and third reaction zones were gas phase reactors. The matrix phase was polymerized in the loop reactor and the first gas phase reactor, and the elastomer phase was polymerized in the second gas phase reactor. The catalyst as described above was fed into the prepolymerization reactor before the first reaction zone.

[0319] Table 1: Polymerization conditions of heterophasic propylene copolymer powders:

[0320]

[0321]

[0322] b) Preparation of polypropylene composition

[0323] The heterophasic propylene copolymer powder A1 from the polymerization was compounded in a twin screw extruder together with different stabilizer packages to obtain the polypropylene compositions of reference examples RE1 and RE2.

[0324] For reference example RE2, an α-nucleating agent was added to the powder and the composition was visbroken to a melt flow rate MFR2 (230° C., 2.16 kg) of 3.9 g / 10 min, as disclosed in the Examples section of WO 2017 / 198633.

[0325] An overview of the production of the polypropylene compositions of Examples RE1 and RE2 is shown in Table 2.

[0326] Table 2: Compounding of RE1 and RE2 in a twin screw extruder:

[0327]

[0328]

[0329] The polypropylene compositions RE1 and RE2 exhibit the properties listed in Table 3 below.

[0330] Table 3: Properties of polypropylene compositions RE1 and RE2:

[0331] RE1 RE2 α-NA none BNT <![CDATA[MFR2]]> [g / 10min] 1.2 3.9 Flexural modulus [MPa] 335 378 Charpy NIS (-20℃) <![CDATA[[kJ / m 2 ]]]> 6.3 4.2 Charpy NIS (23℃) <![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) [weight%] 12.4 11.3 IV(Total) <![CDATA[[cm 3 / g]]]> 277 213 XCS Section [weight%] 35.6 35.6 C2(XCS) [weight%] 26.1 24.5 IV(XCS) <![CDATA[[cm 3 / g]]]> 251 189 Mw(XCS) [g / mol] 294,500 215,000 Mn(XCS) [g / mol] 45,650 48,900 PDI(Mw / Mn)(XCS) [-] 6.4 4.4 XCI Section [weight%] 64.4 64.4 C2(XCI) [weight%] 4.8 5.8 IV(XCI) <![CDATA[[cm 3 / g]]]> 286 216 Mw(XCI) [g / mol] 384,500 271,000 Mn(XCI) [g / mol] 69,500 62,000 PDI(Mw / Mn)(XCI) [-] 5.5 4.4 IV Ratio (XCI / XCS) [-] 1.14 1.14 Mw ratio (XCI / XCS) [-] 1.31 1.26

[0332] To produce the polymer compositions of Inventive Example IE1 and Comparative Example CE1, the composite pellets of Reference Example RE1 were mixed in a Buss 100MDK L / D 11D co-kneader in a second mixing step together with different additives. An overview of the production of polypropylene compositions CE1 and IE1 is shown in Table 4. The properties of CE1 and IE1 are shown in Table 5.

[0333] Table 4: Mixing of IE1-IE3 and CE1 in a Buss 100MDK L / D 11D co-kneader:

[0334] CE1 IE1 Granules RE1 RE1 EBA [weight%] - 10 Temperature in mixer zone [℃] 130-212 118-210 Mixer speed 150 146 Unit energy input SEI [kWh / kg] 0.26 0.28

[0335] Stabilizer Packages and Additives:

[0336] Stabilizer Single Pack 1 consists of 21.8 wt% pentaerythritol tetrakis(3-(3',5'-di-tert-butyl-4-hydroxyphenyl) propionate (CAS-No. 6683-19-8), 43.6 wt% tris(2,4-di-tert-butylphenyl) phosphite (CAS No. 31570-04-4) and 34.6 wt% calcium stearate (CAS No. 1592-23-0), all of which can be purchased from various companies.

[0337] Stabilizer Single Pack 2 consists of 29 wt% pentaerythritol tetrakis(3-(3',5'-di-tert-butyl-4-hydroxyphenyl) propionate (CAS No. 6683-19-8), 58 wt% tris(2,4-di-tert-butylphenyl) phosphite (CAS No. 31570-04-4) and 13 wt% magnesium oxide (CAS No. 1309-48-4), all of which can be purchased from a number of companies.

[0338] α-Nucleation by BNT was achieved by adding 2 wt% of a propylene homopolymer having an MFR2 (230°C) of 8.0 g / 10 min and a melting temperature of 162°C, produced using a Ziegler-Natta type catalyst in Borealis Nucleation Technology (BNT), containing a polymeric α-nucleating agent, distributed by Borealis AG (Austria).

[0339] EBA is ethylene-butyl acrylate copolymer, which is produced as follows:

[0340] Fresh ethylene and recycled ethylene and comonomer butyl acrylate are compressed to an initial reactor pressure of 2500 bar and supplied to the front and side of the split feed zone 2 reactor in the form of two parallel streams, where L / D varies between about 17300 and 30400. The amount of comonomer added is such that the comonomer in the final polymer reaches 27% by weight. The MFR2 of the final polymer is maintained at 4.5 g / 10 min. After compression, the front stream is heated to 160°C in the preheating section and then enters the front area of ​​the reactor, and the side stream is cooled and enters the side of the reactor. After the preheating section and at another position in the reactor, a mixture of commercially available peroxide free radical initiators dissolved in a substantially inert hydrocarbon solvent is injected in an amount sufficient to make the exothermic polymerization reaction reach peak temperatures of 275°C and 275°C, respectively, and intermediate cooling to 165°C. The reaction mixture is depressurized and cooled by a pressure control valve, and the polymer is separated from the unreacted gas.

[0341] The melt flow rate MFR5 (190°C, 2.16 kg) of EBA is 4.5 g / 10 min, the butyl acrylate content is 27.0% by weight, and the density is 927 kg / m 3 , the melting temperature Tm is 92℃.

[0342] For the polypropylene composition IE1, the total content of ethylene (C2), propylene (C3) and butyl acrylate (BA) as well as the contents of ethylene (C2), propylene (C3) and butyl acrylate (BA) in the XCS and XCI fractions have been determined by 13 C NMR measurements. These measurement results for example IE1 are shown in Table 5 together with other characteristics of CE1 and IE1.

[0343] Table 5: Properties of mixed compositions of CE1 and IE1

[0344]

[0345]

[0346] It can be seen that the inventive composition IE1 shows improved flexibility and impact properties compared to the comparative composition CE1, in addition to having comparable crystallization and melting temperatures.

[0347] 3.10kV cable production

[0348] The 10 kV test cable was produced on the Maillefer test cable production line, which is a catenary continuous vulcanization (CCV) type.

[0349] The conductor of the cable core has a 50mm 2 cross section, made of stranded aluminum, with a cross section of 50mm 2 The inner semiconducting layer was made of the semiconducting composition SC2 described below and had a thickness of 1.0 mm. The insulating layer was made of the above compositions CE1 and IE1 and had a thickness of 3.4 mm. The outer semiconducting layer was made of the semiconducting composition SC1 described below and had a thickness of 1.0 mm.

[0350] The cable, i.e. the cable core, is produced by a three-head extruder. The size of the insulation extruder is 100 mm, the conductor shield (inner semiconductor layer) extruder is 45 mm, and the insulation shield (outer semiconductor layer) extruder is 60 mm. The line speed is 6.0 m / min.

[0351] The total length of the vulcanizing tube is 52.5m, consisting of a curing section and a subsequent cooling section. The curing section is filled with 10 bar N2 but not heated. The 33m long cooling section is filled with water at 20-25℃.

[0352] The test cable is then subjected to an AC breakdown test.

[0353] The semiconductive layer 1 (SC1) was prepared from the ready-to-use semiconductive composition Borlink LE7710, which is a non-crosslinked polyethylene-based composition comprising carbon black, commercially available from Borealis AG.

[0354] Semiconductor layer 2 (SC2) was made of 66.5 wt% of RE2 polypropylene-based composition, 33.0 wt% of carbon black Printex Alpha (available from Orion Engineered Carbons GmbH), and 0.5% maleic anhydride functionalized polypropylene Exxelor PO1020 (available from Exxon Mobil).

[0355] Table 6 shows the electrical properties of 10 kV cables of Examples C1 and C2, wherein the insulating layer IE1 according to the invention is compared with the comparative insulating layer CE1.

[0356] Table 6: Electrical properties of 10kV cables of C1 and C2

[0357] C1 C2 Insulation layer CE1 IE1 Semiconductor inner layer SC2 SC2 Outer semiconductor layer SC1 SC1 Weibull-α(scale)[kV / mm] 42.3 45.7 Weibull-beta (shape) 14.3 23.5

[0358] It can be seen that the cable comprising the insulating layer IE1 according to the invention shows increased Weibull-alpha and Weibull-beta values ​​compared to the cable comprising the corresponding comparative insulating layer CE1.

Claims

1. A polypropylene composition comprising: (A) 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, of a copolymer of propylene with comonomer units selected from ethylene and α-olefins having 4 to 12 carbon atoms, The copolymer of propylene and comonomer units is quantitatively 13 C{ 1 The total amount of comonomer units, determined by H}NMR measurement, is from 10.0 to 16.0 wt. %, preferably from 11.0 to 15.0 wt. %, most preferably from 12.0 to 14.0 wt. %; The copolymer of propylene and comonomer units has a melt flow rate MFR2 measured at 230°C and 2.16 kg according to ISO 1133 of 0.5 to 2.5 g / 10 min, preferably 0.8 to 2.3 g / 10 min, more preferably 1.0 to 2.0 g / 10 min, most preferably 1.2 to 1.7 g / 10 min; the total amount of xylene cold soluble (XCS) fraction of the copolymer of propylene and comonomer units determined according to ISO 16152 is from 25.0 to 50.0 wt.-%, preferably from 27.5 to 45.0 wt.-%, more preferably from 30.0 to 42.5 wt.-%, most preferably from 32.5 to 40.0 wt.-%, based on the total weight of the propylene copolymer (A); and (B) 1.0 to 20.0 wt%, preferably 2.5 to 17.5 wt%, most preferably 5.0 to 15.0 wt%, based on the total weight of the polypropylene composition, of ethylene-butyl acrylate copolymer, wherein The ethylene-butyl acrylate copolymer has a butyl acrylate content determined by FT-IR in the range of 15.0 to 40.0 wt%, more preferably in the range of 20.0 to 35.0 wt%, and most preferably in the range of 25.0 to 30.0 wt%, based on the total weight of the ethylene-butyl acrylate copolymer.

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

3. The polypropylene composition according to claim 1 or 2, wherein The xylene cold soluble (XCS) fraction of the propylene copolymer (A) is quantitatively determined based on the total amount of monomer units in the xylene cold soluble (XCS) fraction. 13 C{ 1 % to 35.0 wt.-%, more preferably 23.5 to 32.5 wt.-%, most preferably 24.0 to 30.0 wt.-% of the propylene copolymer (A), and / or the xylene cold soluble (XCS) fraction of the propylene copolymer (A) has an intrinsic viscosity, measured in decalin according to ISO 1628-3, of 150 to 350 cm 3 / g, preferably 200 to 325cm 3 / g, most preferably 225 to 300cm 3 / g.

4. The polypropylene composition according to claim 1 or 2, wherein The total amount of the cold xylene insoluble (XCI) fraction of the propylene copolymer (A) determined according to ISO 16152 is from 50.0 to 75.0 wt.-%, based on the total weight of the propylene copolymer (A), more preferably from 55.0 to 72.5 wt.-%, still more preferably from 57.5 to 70.0 wt.-%, most preferably from 60.0 to 67.5 wt.-%, and the cold xylene insoluble (XCI) fraction is quantitatively determined using 13 C{ 1 The amount of comonomer units, preferably ethylene, determined by H}NMR measurement is preferably from 3.0 to 9.0 wt. %, preferably from 4.0 to 8.5 wt. %, most preferably from 4.5 to 7.5 wt. %, and / or the intrinsic viscosity of the cold xylene insoluble (XCI) fraction, measured in decalin according to ISO 1628-3, is preferably from 185 to 350 cm 3 / g, more preferably 220 to 325 cm 3 / g, most preferably 210 to 300 cm 3 / g.

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

6. The polypropylene composition according to any one of claims 1 to 5, wherein The ethylene-butyl acrylate copolymer (B) has one or more, preferably all, of the following properties: Density measured according to ISO 1183 is 900 to 950 kg / m 3 , preferably 910 to 945 kg / m 3 , most preferably 920 to 940 kg / m 3 ; and / or The melt flow rate MFR2 measured at 190°C and 2.16 kg according to ISO 1133 is 1.0 to 20.0 g / 10 min, Preferably 2.0 to 15.0 g / 10 min, most preferably 3.0 to 10.0 g / 10 min; and / or The melting temperature Tm measured by differential scanning calorimetry is from 60 to 110°C, preferably from 70 to 100°C, most preferably from 80 to 95°C.

7. The polypropylene composition according to any one of claims 1 to 6, wherein The polypropylene composition has: The total amount of units derived from propylene is from 72.5 to 87.5 wt%, more preferably from 75.0 to 85.0 wt%, most preferably from 77.5 to 82.5 wt%; the total amount of units derived from ethylene is from 10.0 to 25.0 wt%, more preferably from 12.5 to 22.5 wt%, most preferably from 15.0 to 20.0 wt%; and The total amount of units derived from butyl acrylate is from 0.1 to 10.0% by weight, more preferably from 0.5 to 7.5% by weight, most preferably from 1.0 to 5.0% by weight, All amounts are based on the total amount of monomer units of the polypropylene composition and are quantitatively 13 C{ 1 H}NMR measurement method.

8. The polypropylene composition according to any one of claims 1 to 7, wherein The polypropylene composition has a xylene cold soluble (XCS) fraction and / or a xylene cold insoluble (XCI) fraction, The xylene cold soluble (XCS) fraction has: The total amount of units derived from propylene is from 50.0 to 73.0 wt%, more preferably from 52.5 to 70.0 wt%, most preferably from 55.0 to 65.0 wt%; the total amount of units derived from ethylene is from 25.0 to 45.0 wt%, more preferably from 27.5 to 40.0 wt%, most preferably from 30.0 to 37.5 wt%; and The total amount of units derived from butyl acrylate is from 0.5 to 12.5% ​​by weight, more preferably from 1.0 to 10.0% by weight, most preferably from 2.0 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 quantitatively determined using 13 C{ 1 H}NMR measurement method; The cold xylene insolubles (XCI) fraction has: The total amount of units derived from propylene is from 80.0 to 96.5 wt%, more preferably from 82.0 to 95.0 wt%, most preferably from 84.0 to 94.0 wt%; the total amount of units derived from ethylene is from 3.5 to 20.0 wt%, more preferably from 5.0 to 17.5 wt%, most preferably from 6.0 to 15.0 wt%; and The total amount of units derived from butyl acrylate is from 0 to 2.5% by weight, more preferably from 0 to 2.0% by weight, most preferably from 0 to 1.5% by weight, All amounts are based on the total amount of monomer units in the cold xylene insoluble (XCI) fraction and are quantitatively determined using 13 C{ 1 H}NMR measurement method.

9. The polypropylene composition according to any one of claims 1 to 8, wherein The polypropylene composition has one or more or all of the following properties: The melt flow rate MFR2 measured at 230°C and 2.16 kg according to ISO 1133 is 0.5 to 3.5 g / 10 min, Preferably 0.8 to 7.0 g / 10 min, more preferably 1.0 to 3.0 g / 10 min, most preferably 1.2 to 2.0 g / 10 min; and / or a melting temperature Tm of 140 to 159°C, preferably 143 to 157°C, most preferably 145 to 153°C, as determined by differential scanning calorimetry; and / or a crystallization temperature Tc of 85 to 130°C, more preferably 87 to 128°C, most preferably 90 to 125°C, as determined by differential scanning calorimetry; and / or The difference between the melting temperature and the crystallization temperature, Tm-Tc, is preferably from 20 to 65°C, preferably from 25 to 60°C, most preferably from 27 to 55°C; and / or The glass transition temperature Tg(matrix) attributed to the matrix phase, determined by dynamic mechanical analysis, is between -1.0 and -15.0°C, Preferably -2.5 to -12.5°C, most preferably -5.0 to -11.0°C; and / or The glass transition temperature Tg(EP) attributed to the elastomeric phase, determined by dynamic mechanical analysis, is between -40.0 and -55.0°C, Preferably -42.5 to -52.5°C, most preferably -45.0 to -50.0°C; and / or Shear thinning index (SHI) determined by dynamic shear measurement 1 / 100 is 2.5 to 20.0, more preferably 5.0 to 17.5, Most preferably 7.5 to 15.0; and / or Polydispersity index PI determined by dynamic shear measurement is 1.0 to 4.5 s -1 , more preferably 1.5 to 4.0s -1 , Most preferably 2.0 to 3.5s -1 ; and / or · a flexural modulus of from 150 MPa to 350 MPa, more preferably from 175 MPa to 335 MPa, most preferably from 200 MPa to 315 MPa, as determined according to ISO 178, method A; and / or Charpy notched impact strength at 23°C measured according to ISO 179-1 / 1eA is 50 to 110 kJ / m 2 , more preferably 60 to 100 kJ / m 2 , most preferably 65 to 95 kJ / m 2 ; and / or Charpy notched impact strength at -20°C measured according to ISO 179-1 / 1eA is 4.0 to 25.0 kJ / m 2 , more preferably 5.5 to 20.0 kJ / m 2 , most preferably 7.0 to 15.0 kJ / m 2 .

10. The polypropylene composition according to any one of claims 1 to 9, which is free of dielectric fluid.

11. An article comprising the polypropylene composition according to any one of claims 1 to 10, preferably a cable, more preferably a medium voltage cable or a high voltage cable, comprising an insulation layer comprising the polypropylene composition.

12. The article according to claim 11, which is a cable comprising an insulation layer, the insulation layer comprising the polypropylene composition and the cable having a Weibull alpha value of 35.0 to 65.0 kV / mm, preferably 40.0 to 65.0 kV / mm, most preferably 44.0 to 65.0 kV / mm and / or a Weibull beta value of 15.0 to 250.0, preferably 20.0 to 250.0, most preferably 22.0 to 250.0, the Weibull alpha value and / or the Weibull beta value being measured on a 10 kV cable according to CENELEC HD 6055.4.15.3.4 for 6 / 10 kV cables.

13. Use of the polypropylene composition according to any of claims 1 to 10 as cable insulation material for medium and high voltage cables.

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