Patent ID: 8075831

Claim:
A method for preparing a bottle by two-stage injection- stretch-blow-moulding (ISBM) that comprises the steps of: a) selecting a polypropylene resin produced with a Ziegler-Natta catalyst system and having a melt flow index MI2 of from 1 to 20 dg/min, wherein the polypropylene resin is a random copolymer of propylene containing at most 6 wt % of ethylene; b) injecting the polypropylene resin of step a) in a mould at a melt temperature of at least 265° C. and at an injection rate of at most 20 g/s to prepare a preform; c) cooling the preform to room temperature; d) transporting the preform to the stretch-blow moulding machine; e) re-heating the preform in the stretch-blow moulding machine in a reflective radiant heat oven following a pre-determined temperature profile for the preform; f) stretching the preform axially by a centre rod and simultaneously orienting the stretched preform radially by high pressure air wherein the rod diameter is selected to be ⅔ of that of the preform.