Adjusting polymer characteristics through process control

Abstract

Properties of a polymer produced in gas phase or slurry phase using a dual catalyst such as polydispersity and comonomer incorporation, may be controlled by controlling reaction parameters such as temperature, (co)monomer pressure, hydrogen partial pressure and the presence of non-polymerizable hydrocarbon. This provides an easy method to control the bimodality of a polymer as well as comonomer incorporation.

1 - 21 . (canceled)  
     
     
         22 . A multimodal polyethylene resin comprising not less than 60 weight % of ethylene and up to 40 weight % of one or more C 3-8  alpha olefins, said polymer having a weight average molecular weight greater than 50,000 and a density greater than 0.89 g/cc comprising from 10 to 90 weight % of a lower molecular weight portion and from 90 to 10 weight % of a higher molecular weight portion, said lower molecular weight portion having a weight average molecular weight from 5,000 to 100,000 as estimated by deconvolution of a GPC curve and a polydispersity greater than 3 and said higher molecular weight portion having a weight average molecular weight from 200,000 to 800,000 as estimated by deconvolution of a GPC curve and a polydispersity less than 10 when prepared by 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 polymerization process selected from the group consisting of a continuous fluidized bed gas phase polymerization at a temperature from 50 to 120° C. and a slurry polymerization in a single reactor at a temperature from 20 to 150° 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 a group 4 transition metal; 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 1 , 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 1  alkoxy radicals which substituents have a Hammett σ ρ  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 1-10  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:      (L) n -M—(Y) p      wherein M is selected from the group consisting of Ti, Zr, and Hf; L is a monoanionic ligand independently selected from the group consisting of cyclopentadienyl-type ligands, and a bulky heteroatom ligand containing not less than five atoms in total of which at least 20%, numerically are carbon atoms) and further containing at least one heteroatom selected from the group consisting of boron, nitrogen, oxygen, phosphorus, sulfur and silicon said bulky heteroatom ligand being sigma or pi-bonded to M; Y is independently selected for the group consisting of activatable ligands; n may be from 1 to 3; and p may be from 1 to 3, provided that the sum of n+p equals the valence state of M, and further provided that two L ligands may be bridged 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. for a gas phase polymerization and within the range from 20 to 150° C. for a slurry phase polymerization;    (b) altering the partial pressure of the hydrogen component of the reaction mixture by at least 0.02 psi (0.138 KPa);    (c) altering the partial pressure of one or more monomers in the reaction mixture by not less than 10 psi (68.94 KPa); and    (d) altering the amount of non polymerizable hydrocarbon in the gas phase reaction mixture by not less than 0.5 mole %.    
     
     
         23 . A polyethylene film made from the resin according to claims  22 .  
     
     
         24 . A polyethylene pipe made from the resin according to  claim 22 .  
     
     
         25 . A polyethylene rotomolded article made from the resin according to  claim 22 .  
     
     
         26 . A polyethylene injection molded article made from the resin according to  claim 22 .  
     
     
         27 . A polyethylene blow molded article made from the resin according to  claim 22 .  
     
     
         28 . A polyethylene geomembrane made from the resin according to  claim 22 .  
     
     
         29 . (canceled)