Patent ID: 8894911

Claim:
A method for preparing vials comprising: providing a Ziegler-Natta formed random copolymer of propylene and from 2 to 3.5 wt. % ethylene exhibiting a melt index (MI 2 ) of from 1 to 3 dg/min., wherein an entirety of the random copolymer is prepared with a Ziegler-Natta catalyst; and two-stage injection-stretch-blow-moulding the random copolymer to form a vial, wherein the two-stage injection-stretch-blow-moulding includes forming a perform at a preform injection temperature of at least 330° C. and a mould filling rate over gate diameter ratio that is at least 5 cc/s/mm; and wherein the two-stage-stretch-blow moulding comprises the following steps: providing the preform by injection moulding on a multi-cavity mould; cooling the preform to room temperature; transporting the preform to the stretch-blow moulding machine; re-heating the preform in the stretch-blow moulding machine; optionally passing the heated preform through an equilibration zone to allow the heat to disperse evenly through the preform wall; optionally, submitting the preform to a pre-blow step; and stretching the preform axially by a centre rod and simultaneously orienting the preform radially by high pressure air, wherein a ratio of the centre rod diameter to the diameter of the preform is within 3% of 2/3.