Ethylene copolymerization process
AssigneePhillips Petrolium Company
InventorsMax P. McDaniel, Elizabeth A. Benham
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Abstract
A process as disclosed for producing a low density polyethylene using a particle form polymerization process and a titanium-containing catalyst wherein the ratio of comonomer to ethylene is at least about 1:1 and the titanium-containing catalyst is a special catalyst which has been pretreated with an organometallic reducing agent.
Claims58
A process for preparing an ethylene copolymer having a density of 0.93 g/mL or less in a particle form polymerization process using a titanium-containing catalyst, the process comprising contacting ethylene and at least one higher alpha-olefin in a liquid diluent consisting essentially of isobutane with the titanium-containing catalyst and a cocatalyst in a continuous loop reactor under particle form polymerization conditions wherein, the molar ratio of the comonomer to ethylene is at least about 1:1, wherein the polymerization is conducted at a temperature in the range of 80° C. to about 90° C. and wherein the titanium-containing catalyst is prepared by contacting a titanium alkoxide and magnesium dihalide in a liquid to obtain a solution, contacting the solution with a precipitating agent selected from organoaluminum compounds to obtain a solid, contacting the solid with titanium tetrachloride before or after a prepolymerization step to result in a prepolymerized catalyst precursor, contacting the resulting prepolymerized catalyst precursor with an organometallic reducing agent to produce a resulting solid, washing the resulting solid with a hydrocarbon to remove soluble material to result in a washed solid which is the titanium-containing catalyst.
A process for preparing an ethylene copolymer having a density of 0.93 g/mL, or less in a particle form polymerization which results in a processable fluff of desirable particle size, the process comprising contacting ethylene and 1-hexene in a liquid diluent consisting essentially of isobutane with a particulate titanium-containing catalyst and a cocatalyst consisting essentially of triethylaluminum in a loop reactor under particle form polymerization conditions, wherein the molar ratio of the comonomer to ethylene is at least about 1:1, wherein the polymerization temperature is in the range of about 80° C. to about 90° C, wherein the level of triethylaluminum in the cocatalyst relative to the diluent does not exceed 30 ppm, further characterized by the fact that the particulate titanium-containing catalyst is prepared by contacting a titanium alkoxide and magnesium dihalide in a liquid to obtain a solution, contacting the solution with a precipitating agent selected from organoaluminum compounds to obtain a solid, contacting the solid with titanium tetrachloride before or after a prepolymerization step to result in a prepolymerized catalyst precursor, contacting the resulting prepolymerized catalyst precursor with an organometallic reducing agent to produce a resulting solid, washing the resulting solid with a hydrocarbon to remove soluble material to result in a washed solid which is the particulate titanium-containing catalyst.
A process for preparing an ethylene copolymer having a density of 0.93 g/mL or less in a particle form polymerization process using a titanium-containing catalyst, the process comprising contacting ethylene and at least one higher alpha-olefin in a liquid diluent with the titanium-containing catalyst and a cocatalyst in a continuous reactor under particle form polymerization conditions, wherein the molar ratio of the comonomer to ethylene is at least about 1:1, wherein the polymerization is conducted at a temperature in the range of about 60° C. to about 95° C. and wherein the titanium-containing catalyst is prepared by contacting a titanium alkoxide and magnesium dihalide in a liquid to obtain a solution, contacting the solution with a precipitating agent selected from organoaluminum compounds to obtain a solid, contacting the solid with titanium tetrachloride before or after a prepolymerization step to result in a prepolymerized catalyst precursor, contacting the resulting prepolymerized catalyst precursor with an organometallic reducing agent to produce a resulting solid, washing the resulting solid with a hydrocarbon to remove soluble material to result in a washed solid which is the titanium-containing catalyst.
Dependencies are inferred from the claim text.