POLYOLEFIN MULTILAYER MEMBRANES

A membrane comprising a base layer (A) and a top layer (B), where the base layer (A) comprises a heterophasic composition (I) containing the following polymer components, all percent amounts being by weight: a) 10-40% of a propylene homopolymer, or copolymer containing over 85% of propylene, and having a fraction insoluble in xylene at room temperature greater than 80%; and b) 60-90% of one or more α-olefin/ethylene copolymers containing less than 40% of ethylene and having solubility in xylene at room temperature greater than 70%; the amounts of (a) and (b) being referred to the total weight of (a) and (b); and the top layer (B) comprises one or more of a homopolymer and copolymer(s) of propylene containing from 65 to 99% by weight of propylene; said top layer (B) being at least partially bonded to the base layer (A).