Polypropylene composition for cable insulation
The present invention relates to a cable comprising at least one layer comprising a polypropylene composition comprising (A) from 80.0 to 99.0 wt.-%, preferably from 82.5 to 97.2 wt. %, most preferably from 85.0 to 95.0 wt.-% of a copolymer of propylene and comonomer units selected from ethylene and alpha-olefins having from 4 to 12 carbon atoms having a total amount of comonomer units of 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 copolymer of propylene (A); 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; a xylene cold soluble (XCS) fraction in a total amount of from 25.0 to 50.0 wt %, preferably from 27.5 to 45.0 wt %, more preferably from 30.0 to 42.5 wt % and most preferably from 32.5 to 40.0 wt %, based on the total weight amount of the copolymer of propylene (A); and (B) from 1.0 to 20.0 wt.-%, preferably from 2.5 to 17.5 wt %, most preferably from 5.0 to 15.0 wt.-% of a propylene polymer having a density of from 855 to 890 kg/m, preferably from 860 to 885 kg/m 3 , mot preferably from 865 to 880 kg/m 3 .
1 . A cable comprising at least one layer comprising a polypropylene composition comprising:
(A) from 80.0 to 99.0 wt.-%, based on the total weight of the polypropylene composition, of a copolymer of propylene and comonomer units selected from ethylene and alpha-olefins having from 4 to 12 carbon atoms having
a total amount of comonomer units of from 10.0 to 16.0 wt %, based on the total amount of monomer units of the copolymer of propylene (A), determined by quantitative 13 C{ 1 H} NMR measurement;
a melt flow rate MFR 2 of from 0.5 to 2.5 g/10 min, determined according to ISO 1133 at 230° C. and 2.16 kg;
a xylene cold soluble (XCS) fraction in a total amount of from 25.0 to 50.0 wt %, based on the total weight amount of the copolymer of propylene (A) and determined according to ISO16152; and
(B) from 1.0 to 20.0 wt.-%, based on the total weight of the polypropylene composition, of a propylene polymer having
a density of from 855 to 890 kg/m 3 , determined according to ISO 1183 or ASTM D 792,
wherein the polypropylene composition has an intrinsic viscosity of the xylene cold soluble (XCS) fraction of from 150 to 240 cm 3 /g, measured in decalin, a glass temperature attributed to a matrix phase Tg (matrix) in the range of from −1.0 to −17.5° C. and a glass temperature attributed to an elastomeric phase Tg (EP) of from −40.0 to −55.0° C., both determined by dynamic mechanical analysis.
2 . The cable according to claim 1 , wherein the copolymer of propylene (A) is a heterophasic copolymer of propylene which comprises a matrix phase and an elastomeric phase dispersed in said matrix phase, which preferably comprises two glass transition temperatures attributed to the matrix phase and the elastomeric phase, wherein the glass transition temperature attributed to the matrix phase Tg (matrix) is in the range of from −1.0 to −15.0° C. and/or the glass transition temperature attributed to the elastomeric phase Tg (EP) is in the range of from −40.0 to −55.0° C., wherein Tg (matrix) and Tg (EP) are determined by dynamic mechanical analysis.
3 . The cable according to claim 1 , wherein xylene cold soluble (XCS) fraction of the copolymer of propylene (A) has an amount of comonomer units, preferably of ethylene, of from 23.0 to 35.0 wt %, 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 and/or an intrinsic viscosity of from 150 to 350 cm 3 /g, measured in decalin according to ISO 1628-3; and/or the copolymer of propylene (A) has a fraction insoluble in cold xylene (XCI) in a total amount of from 50.0 to 75.0 wt %, based on the total weight amount of the copolymer of propylene (A) and determined according to ISO16152, and wherein the fraction insoluble in cold xylene (XCI) preferably has an amount of comonomer units, preferably of ethylene, of from 3.0 to 9.0 wt %, 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 an intrinsic viscosity of preferably from 185 to 350 cm 3 /g, measured in decalin according to ISO 1628-3.
4 . The cable according to claim 1 , wherein the copolymer of propylene
(A) has one or more or all of the following properties:
a flexural modulus of from 130 MPa to 400 MPa, determined according to ISO 178 method A; and/or
a Charpy notched impact strength at 23° C. of from 50 to 110 kJ/m 2 , determined according to ISO 179-1/1 eA; and/or
a Charpy notched impact strength at −20° C. of from 5.0 to 10.0 kJ/m 2 , determined according to ISO 179-1/1 eA.
5 . The cable according to claim 1 , wherein the propylene polymer (B) is a propylene homopolymer, an elastomeric copolymer of propylene and ethylene or a wax of copolymer of propylene and ethylene.
6 . The cable according to claim 1 , wherein the propylene polymer (B) is a propylene homopolymer having one or more or all of the following properties:
a melt flow rate MFR 2 of from 500 to 5000 g/10 min, determined according to ISO 1133 at 230° C. and 2.16 kg; and/or
a melting temperature Tm of from 65 to 95° C., determined by differential scanning calorimetry; and/or
a weight average molecular weight Mw of from 20 to 100 kg/mol, measurable by GPC; and/or
a viscosity at 190° C. of from 1000 to 50000 mPas; and/or
a tensile modulus of from 25 to 150 MPa, measurable by ISO 527-1.
7 . The cable according to claim 1 , wherein the propylene polymer (B) is an elastomeric copolymer of propylene and ethylene having one or more or all of the following properties:
a melt flow rate MFR 2 of from 5000 to 50000 g/10 min, determined according to ISO 1133 at 230° C. and 2.16 kg; and/or
a melting temperature Tm of from 80 to 110° C., determined by differential scanning calorimetry; and/or
a glass transition temperature Tg of from −40 to −10° C., determined by dynamic mechanical analysis; and/or
a viscosity at 190° C. of from 500 to 10000 mPas; and/or
an ethylene content of from 2.5 to 10.0 wt.-%, measurable using quantitative nuclear-magnetic resonance (NMR) spectroscopy.
8 . The cable according to claim 1 , wherein the propylene polymer (B) is an elastomeric copolymer propylene and ethylene having one or more or all of the following properties:
a melt flow rate MFR 2 of from 5.0 to 100 g/10 min, determined according to ISO 1133 at 230° C. and 2.16 kg; and/or
a melting temperature Tm of from 50 to 95° C., determined by differential scanning calorimetry; and/or
a glass transition temperature Tg of from −40 to −10° C., determined by dynamic mechanical analysis; and/or
a crystallinity of from 5 to 50%; and/or
a flexural modulus of from 15 to 200 MPa, determined according to ISO 178 method A.
9 . The cable according to claim 1 , wherein the propylene polymer (B) is wax of copolymer propylene and ethylene having one or more or all of the following properties:
a melt viscosity at 170° C. of from 50 to 500 mPas; and/or
a melting temperature Tm of from 65 to 95° C., determined by differential scanning calorimetry; and/or
a crystallization temperature Tc of from 25 to 55° C., determined by differential scanning calorimetry; and/or
a drop point of from 75 to 105° C., measurable according to ASTM D 3954.
10 . The cable according to claim 1 , wherein the polypropylene composition has one or more or all of the following properties:
a melt flow rate MFR 2 of 0.5 to 3.5 g/10 min, determined according to ISO 1133 at 230° C. and 2.16 kg; and/or
a melting temperature Tm of from 140 to 159° C., determined by differential scanning calorimetry; and/or
a crystallization temperature Tc of from 85 to 130° C., determined by differential scanning calorimetry; and/or
a difference of the melting temperature to the crystallization temperature Tm-Tc is in the range of from 20 to 65° C.; and/or
shear thinning index SHI 1/100 of from 2.5 to 22.5, determined by dynamic shear measurements; and/or
a polydispersity index PI of from 1.0 to 4.5 s −1 , determined by dynamic shear measurements.
11 . The cable according to claim 1 , wherein the polypropylene composition has one or more or all of the following properties:
a flexural modulus of from 150 MPa to 450 Mpa, determined according to ISO 178 method A; and/or
a Charpy notched impact strength at 23° C. of from 50 to 110 KJ/m 2 , determined according to ISO 179-1/1 eA; and/or
a Charpy notched impact strength at −20° C. of from 1.5 to 25.0 kJ/m 2 , determined according to ISO 179-1/1 eA.
12 . The cable according to claim 1 , wherein the polypropylene composition is free of a dielectric fluid.
13 . The cable according to claim 1 , wherein the at least one layer is an insulation layer.
14 . The cable according to claim 1 being a medium voltage cable or high voltage cable, comprising an insulation layer comprising the polypropylene composition.
15 . The cable according to claim 1 having a Weibull alpha-value of from 35.0 to 65.0 kV/mm and/or a Weibull beta-value of from 5.0 to 250.0, measured on a 10 kV cable in agreement with CENELEC HD 605 5.4.15.3.4 for 6/10 kV cables.