Random propylene polymer composition and use in extrusion blow moulding

A propylene polymer composition comprising at least one propylene copolymer (C-PP), and an α-nucleating agent (N), wherein the propylene copolymer (C-PP) comprises two propylene copolymer fractions (PP1) and (PP2), wherein

• propylene copolymer fraction (PP1) is contained in the propylene copolymer (C-PP) in an amount of 30 to 70 wt. % and the propylene copolymer fraction (PP2) is contained in the propylene copolymer (C-PP) in an amount of 70 to 30 wt. %,
• the comonomer content of propylene copolymer fraction (PP1) is in the range of 0.5 to 2.6 wt.-% and the comonomer content of the propylene copolymer fraction (PP1) is lower compared to the comonomer content of the propylene copolymer fraction (PP2), and the propylene polymer composition has
• (a) a melt flow rate MFR2 (230° C.) measured according to according to ISO 1133 of 1 to 5 g/10 min.,
• (b) a comonomer content of 4.0 to 8.0 wt. %, the comonomer(s) being ethylene and/or at least one C4 to C12 α-olefin, and
• (c) a soluble fraction (SF), determined by CRYSTEC fractionation with CRYSTEX QC, Polymer Char (Valencia, Spain), of from 8 to 20 wt. %,
• wherein propylene copolymer (C-PP) is obtained in a multi-stage polymerization process in the presence of
• (a) a Ziegler-Natta catalyst (ZN-C) that comprises a titanium compound (TC), a magnesium compound (MC) and an internal donor (ID), wherein said internal donor (ID) is a non-phthalic acid ester,
• (b) optionally a co-catalyst (Co), and
• (c) optionally an external donor (ED),
• wherein the ratio C2(SF)/C2(CF) between the ethylene content C2(SF) of soluble fraction of the propylene copolymer (C-PP) and the ethylene content C2(CF) of crystalline fraction of the propylene copolymer (C-PP) is 4.0 to 6.0.