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 MFR 2 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) or (II)
€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ Si(OCH 2 CH 3 ) 3 (NR 1 R 2 ) (I) or Si(OCH 3 ) 2 (CH 3 )(cyclohexyl)€ƒ€ƒ€ƒ€ƒ€ƒ(II)
wherein R 1 and R 2 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 odour and taste themselves and their use for injection moulding applications, preferably for thin-wall packaging for food packaging in non-cooking applications and for medical packaging.