Patent ID: 8822611

Claim:
A process for preparing rotomoulded articles comprising: preparing a polyethylene having a spherulite size of less than 20 μm by: a) injecting into a reactor a catalyst system comprising: i) a metallocene catalyst component of general formula: R″(Ind) 2 MQ 2 wherein (Ind) is an indenyl or an hydrogenated indenyl, substituted or unsubstituted; R″ is a structural bridge between the two indenyls that comprises a C 1 -C 4 alkylene radical, dialkyl germanium, silicon, siloxane, phosphine or amine radical; which bridge is substituted or unsubstituted; Q is a hydrocarbyl radical having from 1 to 20 carbon atoms or a halogen; and M is a transition metal Group 4 of the Periodic Table or Vanadium; and ii) an activating agent; b) injecting into the reactor ethylene monomer; c) maintaining the reactor under polymerisation conditions at a temperature of less than 90° C.; and d) modifying polymerization conditions to tailor long chain branching (LCB) of the polyethylene, thereby retrieving polyethylene exhibiting a melt index (MI 2 ) modified to be at least 3 and a long chain branching index (LCBI) that is tailored to be greater than 0; and rotomoulding the polyethylene to form a rotomoulded article exhibiting a permeability of less than 0.5 g/day, wherein the permeability is determined by filling a 10 liter rotomoulded bottle having a wall thickness of 6 mm with fuel at a temperature of 40° C., wherein the fuel is a fuel as defined by CEC RF08-A-85 according to norm Standard ECE34- annex 5.