Patent ID: 7321015

Claim:
A process for controlling one or more of the ratio of high molecular weight polymer to low molecular weight polymer and the comonomer distribution in a continuous fluidized bed gas phase polymerization at a temperature from 50 to 120° C. of a reaction mixture comprising one or more of hydrogen, C 1-7 non polymerizable hydrocarbons, and C 2-8 olefins polymerized in the presence of a dual catalyst wherein both catalyst components are on the same support: (i) the first component of which comprises a catalyst of the formula: wherein M is Zr; R 1 and R 6 are independently selected from the group consisting of C 1-6 alkyl and C 6-10 aryl radicals; R 2 and R 7 are independently selected from the group consisting of C 3-5 secondary and tertiary alkyl radicals; R 3 , R 4 , R 5 , R 8 , R 9 and R 10 are independently selected from the group consisting of a hydrogen atom, C 1-4 alkyl radicals, C 6-10 aryl radicals, C 1 -C 4 alkoxy radicals which substituents have a Hammett σσ ρρ value of less than 0.2; and X and X′ are selected from the group consisting of a halogen atom, C 1-4 alkyl radicals, C 7-12 arylalkyl radicals, C 6-10 phenoxy radicals, amido radicals which may be substituted by up to two C 1-4 alkyl radicals and C 1-4 alkoxy radicals; and (ii) the second component of which comprises a catalyst of the formula: wherein M is a group 4 metal; Pl is a phosphinimine ligand; L is a monoanionic ligand selected from the group consisting of a cyclopentadienyl-type ligand; Y is an activatable ligand; m is 1 or 2; n is 0 or 1; and p is an integer and the sum of m+n+p equals the valence state of M; and an activator, which comprises one or more steps selected from the group consisting of: (a) altering the temperature of the reaction by at least 2° C. within the range from 50 to 120° C.; (b) altering the partial pressure of the hydrogen component of the reaction mixture by at least 0.02 psi; (c) altering the partial pressure of ethylene in the reaction mixture by not less than 20 psi; and (d) altering the amount of non polymerizable hydrocarbon in the reaction mixture by not less than 0.5 mole %.