Process for preparing a polyethylene in at least one continuously stirred tank reactor

Patent metadata

Field	Value
Publication number	US-10100135-B2
Application number	US-201515318010-A
Country	US
Kind code	B2
Filing date	Jun 11, 2015
Priority date	Jun 12, 2014
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

Processes for preparing a polyethylene in at least one continuously stirred tank reactor are described herein. The process may comprise the step of: polymerizing ethylene in the presence of at least one supported metallocene catalyst, a diluent, optionally one or more co-monomers, and optionally hydrogen, thereby obtaining the polyethylene, wherein the supported metallocene catalyst comprises a solid support, a co-catalyst and at least one metallocene, wherein the solid support has a surface area within the range of from 100 to 500 m2/g, and has a D50 value within the range of from 4 μm to 18 μm, with D50 being defined as the particle size for which fifty percent by weight of the particles has a size lower than the D50; and D50 being measured by laser diffraction analysis on a Malvern type analyzer. Polyethylene obtained by the disclosed process and articles comprising the polyethylene are also described.

First claim

The invention claimed is:

1. A process for preparing a polyethylene resin in at least one continuously stirred tank reactor, comprising the step of:
polymerizing ethylene in the presence of at least one supported metallocene catalyst, a diluent, optionally one or more co-monomers, and optionally hydrogen, thereby obtaining the polyethylene resin,
wherein said supported metallocene catalyst comprises a solid support, a co-catalyst and at least one metallocene, wherein the solid support has a surface area within the range of from 100 to 350 m 2 /g, and has a D50 value within the range of from 4 μm to 18 μm, with D50 being defined as the particle size for which fifty percent by weight of the particles has a size lower than the D50; and D50 being measured by laser diffraction analysis on a Malvern type analyzer.

2. The process according to claim 1 , wherein the polyethylene resin at the end of said process has a D50 of at least 100 and at most 400 μm; and Si content lower than 60 ppm by weight.

3. The process according to claim 1 , wherein said at least one supported metallocene catalyst comprises a silica-containing support, an alumoxane, and least one metallocene.

4. The process according to claim 1 , wherein said at least one supported metallocene catalyst comprises a silica- and titania-containing support an alumoxane, and least one metallocene.

5. The process according to claim 4 , wherein the supported catalyst has a Ti content of from 0.1 to 10% by weight based on the total weight of the supported metallocene catalyst, preferably from 0.5 to 5% by weight, and most preferably from 1.0 to 2.5% by weight.

6. The process according to claim 5 , wherein the solid support of said at least one supported metallocene catalyst has an average pore volume of at least 1.0 and at most 3.0 ml/g, preferably at least 1.0 and at most 2.5 ml/g, more preferably at least 1.2 and at most 2.0 ml/g.

7. The process according to claim 1 , wherein the metallocene catalyst is a compound of formula (I) or (II)
(Ar)2MQ2  (I)

R″(Ar)2MQ2  (II)

wherein the metallocenes according to formula (I) are non-bridged metallocenes and the metallocenes according to formula (II) are bridged metallocenes;
wherein said metallocene according to formula (I) or (II) has two Ar bound to M which can be the same or different from each other;
wherein Ar is an aromatic ring, group or moiety and wherein each Ar is independently selected from the group consisting of cyclopentadienyl, indenyl (IND), tetrahydroindenyl (THI), and fluorenyl, wherein each of said groups are optionally substituted with one or more substituents each independently selected from the group consisting of halogen, and a hydrocarbyl having 1 to 20 carbon atoms, and wherein said hydrocarbyl optionally contains one or more atoms selected from the group comprising B, Si, S, O, F, and P;
wherein M is a transition metal selected from the group consisting of titanium, zirconium, hafnium, and vanadium; and preferably is zirconium;

wherein each Q is independently selected from the group consisting of halogen, a hydrocarboxy having 1 to 20 carbon atoms, and a hydrocarbyl having 1 to 20 carbon atoms and wherein said hydrocarbyl optionally contains one or more atoms selected from the group comprising B, Si, S, O, F, and P; and
wherein R″ is a divalent group or moiety bridging the two Ar groups and selected from the group consisting of C1-C20 alkylene, germanium, silicon, siloxane, alkylphosphine, and an amine, and wherein said R″ is optionally substituted with one or more substituents each independently selected from the group consisting of halogen, a hydrocarbyl having 1 to 20 carbon atoms, and wherein said hydrocarbyl optionally contains one or more atoms selected from the group comprising B, Si, S, O, F, and P.

8. The process according to claim 1 , wherein the metallocene is a compound selected from one of the following formula (III) or (IV):

wherein each R in formula (III) or (IV) is the same or different and is selected independently from hydrogen or XR′v in which X is chosen from Group 14 of the Periodic Table, oxygen or nitrogen and each R′ is the same or different and is chosen from hydrogen or a hydrocarbyl of from 1 to 20 carbon atoms and v+1 is the valence of X, R″ is a structural bridge between the two indenyl or tetrahydrogenated indenyls that comprises a C1 C4 alkylene radical, a dialkyl germanium, silicon or siloxane, or an alkyl phosphine or amine radical; Q is a halogen or a hydrocarbyl radical having from 1 to 20 carbon atoms, preferably Q is F, Cl or Br; and M is a transition metal selected from the group consisting of titanium, zirconium, hafnium, and vanadium.

9. The process according to claim 1 , wherein the metallocene catalyst comprises a bridged unsubstituted bis-indenyl and/or a bridged unsubstituted bis-tetrahydrogenated indenyl.

10. The process according to claim 1 , wherein the solid support of said at least one supported metallocene catalyst has a particle size distribution of a span value lower than 2.0,
wherein the span is defined as:

span
=

D
⁢

⁢
90

-

D
⁢

⁢
10

D
⁢

⁢
50

with D90 being defined as the particle size for which ninety percent by weight of the particles has a size lower than the D90;
with D10 being defined as the particle size for which ten percent by weight of the particles has a size lower than the D10;
with D50 being defined as the particle size for which fifty percent by weight of the particles has a size lower than the D50; and
with the D90, D10 and D50 being measured by laser diffraction analysis on a Malvern type analyzer.

11. The process according to claim 1 , wherein the co-monomer is 1-butene.

12. The process according to claim 1 , wherein said polymerization process is performed in the presence of at least one antifouling agent.

13. The process according to claim 1 , wherein said process is performed in at least two continuously stirred tank reactors connected in series.

14. The process according to claim 1 , wherein said diluent is selected from hexane, isohexane, or heptane.

Assignees

• Total Res & Technology Feluy

Inventors

• Vantomme Aurelien
• Willocq Christopher
• Welle Alexandre
• Slawinski Martine

Classifications

• C08F4/025

  Metal oxides · CPC title

• C08F2/14

  Organic medium · CPC title

• C08F110/02 Primary

  Ethene · CPC title

• C08F2500/07

  High density, i.e. > 0.95 g/cm3 · CPC title

• C08F2500/24

  Polymer with special particle form or size · CPC title