A 1-butene ethylene copolymer having an ethylene derived units content ranging from 15.10% by molto 18.00% by mol having the following properties: a) distribution of molecular weight lower than 3; preferably b) hardness shore A (measured according to ISO 868) lower than 65; c) tension set lower than 30% at 100% of deformation (ISO 2285) d) no melting pointdetectable at the DSC; e) Melting enthalpy measured after 10 days of aging at room temperature comprised between 4 and 15 J/g.
