A multimodal ethylene copolymer having the following properties: i) density comprised in the range from 0.880 to 0.955 g/cm3; ii) total comonomer content ranging from 6% to 25% by weight; iii) content of 1-butene derived units ranging from 0 to 2% by weight; iv) Mw/Mn comprised from 4 to 20; v) intrinsic viscosity (decalin at 135° C. as determined according to EN ISO 1628-312003) comprised between 1.0 and 4.0 dL/g; said multimodal ethylene copolymer comprises from 10% to 80% by weight of a first polyethylene component and being detected at the Crystaf® apparatus at a temperature higher than 75° C. and from 90% to 20% by weight of a second polyethylene component being a copolymer being detected at a Crystaf® apparatus at a temperature lower than 75° C.; wherein said multimodal ethylene copolymer being fractionated into 12 fractions by means of the Holtrup analysis, the fractions containing more than 2% by weight of the total amount of material meet the following relationship: Cf/HDPE>−0.0075HDPE+0.58; wherein Cf is the amount (% wt) of comonomer of formula CH2═CHT in the copolymer of the fraction and HDPE is the amount (% wt) of the homopolymer component present in the fraction.