Polyolefin catalysts, production thereof and method of use
A method of modifying a Ziegler-Natta type polyolefin catalyst comprises contacting the Ziegler-Natta catalyst with olefin monomer to form a prepolymerized catalyst. The prepolymerized catalyst can comprise a reduced number of catalyst particles having a size of 40 microns or less. The prepolymerized catalyst can be used in a polymerization process to produce polymer fluff particles with a reduced number of polymer fluff fines than the Ziegler-Natta type catalyst.
1. A polymerization process comprising:
providing a Ziegler-Natta type catalyst;
contacting the catalyst with olefin monomer to form a prepolymerized catalyst; and
contacting the prepolymerized catalyst with olefin monomer under polymerization reaction conditions to produce polymer fluff particles;
wherein less than 5% of the polymer fluff particles are 700 microns or less in size.
2. The process of claim 1 wherein the prepolymerized catalyst is capable of producing a reduced number of polymer fluff fines than the Ziegler-Natta type catalyst.
3. The process of claim 1 wherein the prepolymerized catalyst produces at least 50% fewer polymer fluff fines as compared to the Ziegler-Natta type catalyst.
4. The process of claim 1 wherein the number of polymer fines produced is less than 0.5%.
5. A process for altering a Ziegler-Natta type catalyst particle size comprising:
preparing a Ziegler-Natta type catalyst using a magnesium precursor solution having a magnesium solution concentration;
wherein the catalyst particle size increases with an increase in magnesium solution concenfration; and
wherein contacting the catalyst with olefin monomer to form a prepolymerized catalyst, and then contacting the prepolymerized catalyst with olefin monomer under polymerization reaction conditions to produce polymer fluff particles results in a polymer fluff wherein less than 5% of the polymer fluff particles are 700 microns or less in size.
6. The process of claim 5 , wherein the Ziegler-Natta type catalyst is made using a magnesium precursor chosen from the group consisting of dibutylmagnesium and butylethylmagnesium.
7. The process of claim 5 , wherein the resulting catalyst particle size is increased from between about 3 to about 10% for each solution concentration multiple that is utilized, when the solution concentration ranges are between about 10 mmol Mg/L to about 250 mmol Mg/L.
8. A polymerization process comprising:
preparing a Ziegler-Natta type catalyst using a magnesium precursor solution having a magnesium solution concentration, wherein the catalyst particle size increases with an increase in magnesium solution concentration; and
contacting the catalyst with olefin monomer under polymerization reaction conditions to produce polymer fluff particles wherein less than 5% of the polymer fluff particles are 700 microns or less in size.
9. The process of claim 8 further comprising:
contacting the catalyst with olefin monomer to form a prepolymerized catalyst.
10. The process of claim 8 wherein the number of polymer fluff particles less than 125 microns decreases with an increase in magnesium solution concentration.
11. A polymerization process comprising:
providing a Ziegler-Natta type catalyst;
contacting the Ziegler-Natta type catalyst with triisobutylaluminum to form a precontacted catalyst;
contacting the precontacted catalyst with olefin monomer to form a prepolymerized catalyst; and
contacting the prepolymerized catalyst with olefin monomer under polymerization reaction conditions to produce polymer fluff particles;
wherein the precontacted catalyst is at least 20% larger in average particle size than the Ziegler-Natta type catalyst;
wherein the prepolymerized catalyst has at least 50% fewer particles with a size of 40 microns or less than the precontacted catalyst;
wherein less than 5% of the polymer fluff particles are 700 microns or less in size; and wherein the number of polymer fines produced is less than 0.5%.