Molecular weight distribution modification in tubular reactor

• US 4,789,714 A
• Filed: 12/26/1985
• Issued: 12/06/1988
• Est. Priority Date: 06/15/1983
• Status: Expired due to Term

• Current Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Original Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Inventors: Cozewith, Charles, Verstrate, Gary W., Ju, Shiaw
• Primary Examiner(s): Ivy, C. Warren
• Assistant Examiner(s): WALKER, ALEXANDER
• Application Number:
  US06/840,562
• Time in Patent Office: 1,076 Days
• Field of Search: 526/64, 526/66, 526/67, 526/88, 526/72, 526/169.2, 526/280, 526/918, 526/922, 526/348, 526/348.2
• US Class Current: 526/88
• CPC Class Codes: B01J 19/2415 Tubular reactors
• CPC Class Codes: B01J 2219/00099 the reactor being immersed in the heat exchange medium
• CPC Class Codes: B01J 2219/00159 controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling
• CPC Class Codes: B01J 2219/00186 controlling the composition of the reactive mixture
• CPC Class Codes: C08F 2/00 Processes of polymerisation
• CPC Class Codes: C08F 210/02 Ethene
• CPC Class Codes: C08F 210/06 Propene
• CPC Class Codes: C08F 210/16 Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• CPC Class Codes: C08F 210/18 with non-conjugated dienes, e.g. EPT rubbers
• CPC Class Codes: C08F 2500/02 Low molecular weight, e.g. <100,000 Da.
• CPC Class Codes: C08F 2500/03 Narrow molecular weight distribution, i.e. Mw/Mn < 3
• CPC Class Codes: C08F 2500/05 Bimodal or multimodal molecular weight distribution
• CPC Class Codes: C08F 2500/06 Comonomer distribution, e.g. normal, reverse or narrow
• CPC Class Codes: C08F 2500/25 Cycloolefine
• CPC Class Codes: C08F 297/08 polymerising mono-olefins
• CPC Class Codes: C08F 4/68 Vanadium, niobium, tantalum or compounds thereof
• CPC Class Codes: C10M 143/00 Lubricating compositions characterised by the additive being a macromolecular hydrocarbon or such hydrocarbon modified by oxidation
• CPC Class Codes: C10M 2205/00 Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
• CPC Class Codes: C10M 2205/02 containing acyclic monomers
• CPC Class Codes: C10M 2205/022 Ethene
• CPC Class Codes: C10M 2205/08 : containing non-conjugated dienes
• CPC Class Codes: C10M 2205/10 : containing cycloaliphatic monomers
• CPC Class Codes: C10N 2020/01 : Physico-chemical properties
• CPC Class Codes: Y10S 526/918 : Polymerization reactors for addition polymer preparation
• CPC Class Codes: Y10S 526/922 : Polymerization process of ethylenic monomers using manipulative technique

Abstract

A method for preparing a polymodal MWD ethylene-alpha olefin copolymer using at least two catalysts to initiate growth of polymer chains that attain different average molecular weights. The polymodal MWD ethylene copolymer comprises at least two different molecular weight modes each mode having a narrow MWD and at least one of two characteristics (1) an Mw/Mn of less than 2 and (2) Mz/Mw of less than 1.8.

Claims

1. In a polymerization process for producing copolymer from a reaction mixture comprised of catalyst and a monomer feed comprising ethylene and at least one other alpha-olefin monomer, the improvement which comprises producing a polymodal MWD copolymer by conducting the polymerization:

(a) a substantially mix free reactor;

(b) with essentially one active catalyst species wherein said catalyst species exhibits a decay in activity with respect to polymerization time;

(c) using at least one reaction mixture which is essentially transfer-agent free;

(d) in such a manner and under conditions sufficient to initiate propagation of essentially all copolymer chains formed from the catalyst species simultaneously;

(e) adding a catalyst reactivator to the reaction mixture after polymerization has progressed for a finite time; and

(f) recovering polymer at the completion of polymerization;

thereby producing a polymodal MWD ethylene copolymer comprising at least two different molecular weight modes wherein each mode having a narrow MWD and at least one of two characteristics, (1) an M_w /M_n of less than 2 and and M_z /M_w of less than 1.8.

2. The process according to claim 1 wherein the catalyst components are premixed.

3. The process according to claim 1 wherein the monomer feed additionally comprises a non-conjugated diene.

4. In a polymerization process for producing copolymer from a reaction mixture comprised of catalyst and a monomer feed comprising ethylene and at least one other alpha-olefin monomer, the improvement which comprises producing a polymodal MWD copolymer by conducting the polymerization:

(a) in at least one reactor, said reactor being a substantially mix free reactor;

(b) with essentially one catalyst system which generates multiple active catalyst species each catalyst species initiating the growth of polymer chains that attain a different average molecular weight than those produced by other catalyst species;

(c) using at least one reaction mixture which is essentially transfer-agent free;

(d) in such a manner and under conditions sufficient to initiate propagation of essentially all copolymer chains made with a particular catalyst species simultaneously;

(e) recovering polymer at the completion of polymerization;

thereby producing a polymodal MWD ethylene copolymer comprising at least two different molecular weight modes wherein each mode has a narrow MWD and at least one of two characteristics, (1) an M_w /M_n of less than 2 and and M_z /M_w of less than 1.8.

5. The process according to claim 4 wherein the catalyst components are premixed.

6. The process according to claim 4 wherein the monomer feed additionally comprises a non-conjugated diene.

7. In a polymerization process for producing copolymer from a reaction mixture comprised of catalyst and a monomer feed comprising ethylene and at least one other alpha-olefin monomer, the improvement which comprises producing a polymodal MWD copolymer by conducting the polymerization:

(a) in at least one reactor, said reactor being a substantially mix free reactor;

(b) using at least one reaction mixture which is essentially transfer-agent free;

(c) with at least one first catalyst in such a manner and under conditions sufficient to initiate propagation of essentially all copolymer chains simultaneously;

(d) introducing at least one additional catalyst feed together with additional monomer at one or more finite times after initiation of polymerization;

thereby initiating additional copolymer chains wherein the propagation of essentially all such additional copolymer chains is initiated simultaneously and wherein the additional catalyst feed is the same or different than the first catalyst;

thereby producing a polymodal MWD ethylene copolymer comprising at least two different molecular weight modes wherein each mode having a narrow MWD and at least one of two characteristics, (1) an M_w /M_n of less than 2 and and M_z /M_w of less than 1.8.

8. The process according to claim 7 wherein the catalyst components are premixed.

9. The process of claim 7 wherein the monomer feed additionally comprises a non-conjugated diene.