Process for preparing polyolefin fluff using metallocene catalyst

Claim 1

Process for the preparation of olefin polymers and copolymers having controlled morphology by bulk or slurry polymerization, comprising the steps of: (i) providing a homogeneous non-supported system comprising a metallocene transition metal catalysts of general formula (Cp) m R n MQ k wherein each Cp is a cyclopentadienyl or a cyclopentadienyl substituted by one or more hydrocarbyl radical having from 1 to 20 carbon atoms, R is a structural bridge between two Cp rings, M is a transition metal selected from groups 4 or 5, Q is a hydride or a hydrocarbyl group having from 1 to 20 carbon atoms or an alkenyl group having from 2 to 20 carbon atoms or a halogen, m=1-3 with the proviso that if m=2 or 3 each Cp may be the same or different, n=0 or 1 with the proviso that n=0 if m=1, and k is such that the sum of m+k is equal to the oxidation state of M with the proviso that if k is greater than 1 each Q may be the same or different, and an alumoxane cocatalyst; and (ii) prepolymerizing said homogeneous system in the present of at least one olefin for a period of from 1.5 to 3.5 minutes and at a temperature of from -10° to +35° C.; (iii) introducing said prepolymerized system either into at least one olefin in the liquid state for bulk polymerization or into an inert liquid hydrocarbon containing at least one olefin for slurry polymerization, the polymerization being carried out at a temperature of from 55° C. to 70° C.; and (iv) recovering polyolefin fluff.