Extrusion blown molded bottles with high stiffness and transparency
View Patent ↗A polypropylene composition comprising a random propylene copolymer, a high melt strength polypropylene having a branching index g′ of 0.9 or less and a clarifier, wherein the polypropylene composition has a MFR 2 (230° C.) of at least 2.0 g/10 min.
1. A method for producing an extrusion blown molded product, comprising the steps of:
providing a visbroken polypropylene composition comprising a random propylene copolymer (R-PP), a high melt strength polypropylene (HMS-PP) and a clarifier, wherein
(a) the R-PP comprises units derived from propylene and at least another C 2 to C 20 α-olefin, and has a xylene cold soluble fraction (XCS) of not more than 15.0 wt-%,
(b) optionally the HMS-PP has a branching index g′ of less than 1.0,
(c) the C comprises at least one α-nucleating agent clarifier, and
(d) the polypropylene composition has a MFR 2 (230° C.) in the range of 2.0 to 6.0 g/10 min. and a visbreaking ratio of (final MFR 2 (230° C.)/initial MFR 2 (230° C.)) of 1.4 to 2.5,
wherein further the α-nucleating agent is selected from the group consisting of
(i) C 1 -C 8 -alkyl-substituted dibenzylidenesorbitol derivatives, and
(ii) vinylcycloalkane polymer and vinylalkane polymer; and
extrusion blow molding said polypropylene composition to produce an extrusion blown molded product.
2. The method according to claim 1 , wherein the extrusion blown molded product is a bottle.