Process for the production of propylene random copolymers for injection moulding applications

摘要

Process for the production of polypropylene random copolymers containing 2.5 to 5.0 wt % of ethylene as comonomer and having an MFR2 in accordance with ISO 1 133 (230° C., 2.16 kg load) of ≧25 g/10 min to 100 g/10 min and a hexane-solubles content, determined according to FDA CFR 21 §177.1520 below 5 wt %, said process comprising the step of polymerizing propylene and ethylene in the presence of a catalyst system comprising (i) a Ziegler-Natta procatalyst which contains a trans-esterification product of a lower alcohol and a phthalic ester as internal donor and (ii) an organometallic cocatalyst and (iii) an external donor represented by formula (I) or (II) Si(OCH2CH3)3(NR1R2) (I) or Si(OCH3)2(CH3(cyclohexyl) (II) wherein R1 and R2 can be the same or different and represent a hydrocarbon group having 1 to 12 carbon atoms, the polypropylene random copolymers with a low level of odor and taste themselves and their use for injection molding applications, preferably for thin-wall packaging for food packaging in non-cooking applications and for medical packaging.

主权项

1. Process for the production of polypropylene random copolymers with a low level of odour and taste containing 2.5 to 5.0 wt % of ethylene as comonomer and having an MFR2 in accordance with ISO 1133 (230° C., 2.16 kg load) of ≧25 g/10 min to 100 g/10 min and a hexane-solubles content, determined according to FDA CFR 21 §177.1520 below 5 wt %, said process comprising the step of polymerizing propylene and ethylene in the presence of a catalyst system comprising
(i) a Ziegler-Natta procatalyst which contains a trans-esterification product of a lower alcohol and a phthalic ester as internal donor and (ii) an organometallic cocatalyst and (iii) an external donor represented by formula (I)
Si(OCH2CH3)3(NR1R2)  (I) wherein R1 and R2 can be the same or different and represent a hydrocarbon group having 1 to 12 carbon atoms, wherein the polypropylene random copolymer has a xylene soluble fraction of less than 8 wt %.