Process for controlling the MWD of a broad/bimodal resin produced in a single reactor
First Claim
1. A process for controlling the relative amount of a high molecular weight component and a low molecular weight component in a bimodal molecular weight distribution resin or a broad molecular weight distribution resin which comprises said high molecular weight component and said low molecular weight component, said process comprisingcontacting a feed comprising ethylene, under ethylene polymerization conditions, with a catalyst comprising a support containing two sources of transition metals, wherein the catalyst comprisesa dry, anhydrous, support containing composition comprising an activated metallocene compound of a transition metal and a non-metallocene transition metal compound,wherein the support is the reaction product of(1) silica having OH groups, impregnated with RMgR'"'"', wherein each of R and R'"'"' is alkyl of 4 to 10 carbon atoms,wherein RMgR'"'"' is present in an amount to provide a RMgR'"'"':
- OH molar ratio of 0.5;
1 to 4;
1; and
(2) an organic alcohol reagent having a formula R"OH, wherein R" is an alkyl group of 1 to 12 carbon atoms;
wherein said alcohol reagent is used in an amount effective to provide an alcohol/Mg molar ratio of 0.5 to 2.0;
producing said bimodal molecular weight distribution resin or a broad molecular weight distribution resin product;
introducing additional feed for said contacting with said catalyst in which the activated metallocene compound exhibits a first productivity relative to the non-metallocene transition metal compound;
adding an amount of a reagent selected from the group consisting of water, carbon dioxide and admixtures thereof,wherein the amount of reagent is effective to alter the first productivity relative to the non-metallocene transition metal compound; and
recovering a modified product which has a second relative ratio of said high molecular weight component and said low molecular weight component which second relative ratio differs from said relative amount.
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Abstract
A bimetallic catalyst produces broad or bimodal molecular weight distribution polyolefin resin whose composition depends on the ratio of the concentration of the two metals of the catalyst producing the HMW and LMW components. The bimetallic catalyst produces a broad/bimodal MWD resin whose HMW and LMW components depend on the relative productivity of each of the transition metal sites of the catalyst. Water and/or carbon dioxide are cofed to the polymerization reactor at levels necessary to modify the weight fractions of the HMW and LMW components, thus achieving a target molecular weight distribution, MWD. The invention allows the resin MWD to be adjusted in the reactor. The weight fraction of the high molecular weight component decreases with the addition of the water and or the carbon dioxide and the FI of the overall product increases with a decrease in the HMW component weight fraction in the product.
314 Citations
30 Claims
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1. A process for controlling the relative amount of a high molecular weight component and a low molecular weight component in a bimodal molecular weight distribution resin or a broad molecular weight distribution resin which comprises said high molecular weight component and said low molecular weight component, said process comprising
contacting a feed comprising ethylene, under ethylene polymerization conditions, with a catalyst comprising a support containing two sources of transition metals, wherein the catalyst comprises a dry, anhydrous, support containing composition comprising an activated metallocene compound of a transition metal and a non-metallocene transition metal compound, wherein the support is the reaction product of (1) silica having OH groups, impregnated with RMgR'"'"', wherein each of R and R'"'"' is alkyl of 4 to 10 carbon atoms, wherein RMgR'"'"' is present in an amount to provide a RMgR'"'"': - OH molar ratio of 0.5;
1 to 4;
1; and(2) an organic alcohol reagent having a formula R"OH, wherein R" is an alkyl group of 1 to 12 carbon atoms; wherein said alcohol reagent is used in an amount effective to provide an alcohol/Mg molar ratio of 0.5 to 2.0; producing said bimodal molecular weight distribution resin or a broad molecular weight distribution resin product; introducing additional feed for said contacting with said catalyst in which the activated metallocene compound exhibits a first productivity relative to the non-metallocene transition metal compound; adding an amount of a reagent selected from the group consisting of water, carbon dioxide and admixtures thereof, wherein the amount of reagent is effective to alter the first productivity relative to the non-metallocene transition metal compound; and recovering a modified product which has a second relative ratio of said high molecular weight component and said low molecular weight component which second relative ratio differs from said relative amount. - View Dependent Claims (2, 3, 4, 7, 8, 9, 10, 11, 12, 13, 14, 20, 28)
- OH molar ratio of 0.5;
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5. A process for increasing the FI of bimodal molecular weight distribution resin or a broad molecular weight distribution resin of ethylene which comprises a high molecular weight component and a low molecular weight component, by decreasing the relative amount of a high molecular weight component, said process comprising
contacting a feed comprising ethylene, under ethylene polymerization conditions, with a catalyst comprising a support and two sources of transition metals, wherein the catalyst comprises a dry, anhydrous, support containing composition comprising an activated metallocene compound of a transition metal and a non-metallocene transition metal compound, wherein the support is the reaction product of (1) silica having OH groups, impregnated with RMgR'"'"', wherein each of R and R'"'"' is an alkyl group of 4 to 10 carbon atoms, wherein RMgR'"'"' is present in an amount to provide a RMgR'"'"': - OH molar ratio of 0.5;
1 to 4;
1; and(2) an organic alcohol reagent having a formula R"OH, wherein R" is an alkyl group of 1 to 12 carbon atoms; wherein said alcohol reagent is used in an amount effective to provide an alcohol/Mg molar ratio of 0.5 to 2.0; producing bimodal molecular weight distribution resin or a broad molecular weight distribution resin each of which is further characterized as unmodified; introducing additional feed for said contacting with said catalyst; adding an amount of a reagent selected from the group consisting of water, carbon dioxide and admixtures thereof, wherein the amount of reagent is effective to alter the first productivity relative to the non-metallocene transition metal compound; wherein the amount ranges from 0-20 ppm H2 O based on ethylene;
0-10 ppm CO2 based on ethylene; andrecovering a modified product which has a second relative ratio of said high molecular weight component to said low molecular weight component which second relative ratio is less than the corresponding ratio in said unmodified bimodal molecular weight distribution resin or a broad molecular weight distribution resin. - View Dependent Claims (15, 16, 17, 18, 19, 29)
- OH molar ratio of 0.5;
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6. A process for increasing the FI of bimodal molecular weight distribution resin or a broad molecular weight distribution resin of ethylene which comprises a high molecular weight component and a low molecular weight component, by decreasing the relative amount of said high molecular weight component, said process comprising
contacting a feed comprising ethylene, under ethylene polymerization conditions, with a catalyst comprising a support and two sources of transition metals, wherein the catalyst comprises a dry, anhydrous, support containing composition comprising an activated metallocene compound of a transition metal and a non-metallocene transition metal compound, wherein the support is the reaction product of (1) silica having OH groups, impregnated with RMgR'"'"', wherein each of R and R'"'"' is an alkyl group of 4 to 10 carbon atoms, wherein RMgR'"'"' is present in an amount to provide a RMgR'"'"': - OH molar ratio of 0.5;
1 to 4;
1; and(2) an organic alcohol reagent having a formula R"OH, wherein R" is an alkyl group of 1 to 12 carbon atoms; wherein said alcohol reagent is used in an amount effective to provide an alcohol/Mg molar ratio of 0.5 to 2.0; producing bimodal molecular weight distribution resin or a broad molecular weight distribution resin unmodified product; introducing additional feed for said contacting with said catalyst; adding an amount of a reagent selected from the group consisting of water, carbon dioxide and admixtures thereof, wherein the amount of reagent ranges from 0.1 to 1000 ppm H2 O based on ethylene;
0.1 to 50 ppm CO2 based on ethylene; andrecovering a modified product which has an FI that is at least 10 percent higher than that of the unmodified product. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 30)
- OH molar ratio of 0.5;
Specification