Power cable

An insulating composition comprising a heterophasic polypropylene resin,

• wherein, in the heterophasic polypropylene resin, a rubbery propylene copolymer is dispersed in a crystalline polypropylene matrix,
• wherein an insulating sample formed of the insulating composition has a flexural modulus of 50 to 1,200 MPa at room temperature, measured according to the ASTM D790 standard, and tensile strength of 1.27 kg/mm2 or more and elongation of 350% or more, measured according to the KS C IEC 60811-501 standard, wherein the insulating sample formed of the insulating composition and heated at 135±3° C. for 240 hours according to the NEN-HD 620 S2 standard has tensile strength of 1.27 kg/mm2 or more and elongation of 350% or more, wherein the insulating sample formed of the insulating composition has a brittle temperature of −35° C. or less, measured according to the ASTM D746 standard, and wherein a peak ratio of a propylene monomer is in a range of 0.3 to 2.0 according to the following Equation 1 and xylene insolubility is in a range 10% or less according to the following Equation 2:
• peak ratio=peak of CH3 symmetric bend/peaks of CH2 and CH3 bends, [Equation 1]
• wherein the peak of CH3 symmetry bend represents a peak value of an absorption rate with respect to the CH3 symmetry bend between 1400 cm−1 and 1340 cm−1, which are wave numbers indicating a propylene monomer in an FT-IR analysis of the insulating composition, and the peaks of CH2 and CH3 bends represent peak values of absorption rates with respect to CH2 and CH3 bends between 1500 cm−1 and 1420 cm−1, which are wave numbers respectively indicating an ethylene monomer and a propylene monomer in the FT-IR analysis of the insulating composition, and
• xylene insolubility=(mass of insulating sample after eluted with xylene solvent/mass of insulating sample before eluted)×100, [Equation 2]
• wherein the mass of insulating sample after eluted with xylene solvent represents mass of an insulating sample, measured after 0.3 grams of the insulating sample is immersed into a xylene solvent, heated at a boiling point or higher for six hours, cooled to room temperature, taken out of the xylene solvent, dried in an oven at 150° C. for four hours, and cooled to the room temperature.