Ziegler-Natta produced polyethylene and methods thereof

Patent metadata

Field	Value
Publication number	US-11780942-B2
Application number	US-202017080594-A
Country	US
Kind code	B2
Filing date	Oct 26, 2020
Priority date	Oct 25, 2019
Publication date	Oct 10, 2023
Grant date	Oct 10, 2023

Abstract

A process of producing a composition comprising a copolymer of ethylene and one or more C4-C8 α-olefins, may include copolymerizing the ethylene and the one or more C4-C8 α-olefins in the presence of a procatalyst and an alkylaluminum cocatalyst. The procatalyst may be a Ti-containing Ziegler Natta procatalyst and the polymerization may include the procatalyst and the alkylaluminum cocatalyst in amounts such that a molar ratio of Al:Ti ranges from about 0.5 to about 50.0.

First claim

What is claimed is:

1. A process of producing a composition comprising a copolymer of ethylene and one or more C4-C8 α-olefins, the process comprising:
copolymerizing the ethylene and the one or more C4-C8 α-olefins in the presence of a procatalyst and an alkylaluminum cocatalyst,
wherein the procatalyst is a Ti-containing Ziegler Natta procatalyst,
wherein polymerization comprises the procatalyst and the alkylaluminum cocatalyst in amounts such that a molar ratio of Al:Ti ranges from about 0.5 to about 50.0, and
wherein the composition satisfies one or more of the following as determined by cross fractionation chromatography (CFC):
a weight average molecular weight (M w ) of a room temperature soluble fraction, eluted at 35° C. to 40° C., is at least 70 kDa, and a ratio S×1/Stotal is 0.35 or less, where S×1 is a sum of total peak areas of components that are eluted at 35° C. to 40° C., and Stotal is a sum of total peak areas of components that are eluted at 0 to 120° C.;
a weight average molecular weight (Mw) of a fraction eluted at 43° C. to 79° C., ranges from 140 kDa to 1750 kDa, and a ratio S×2/Stotal is 0.43 or more, where S×2 is a sum of total peak areas of components that are eluted at 43° C. to 79° C.; and
a weight average molecular weight (Mw) of a fraction eluted at 82° C. to 120° C. ranges from 1800 kDa to 3600 kDa and a ratio S×3/Stotal ranges from 0.20 to 0.28, where S×3 is a sum of total peak areas of components that are eluted at 82° C. to 120° C.

2. The process of claim 1 , wherein the composition has a substantially constant comonomer composition distribution (CCD) profile across the elution curve in the temperature rising elution fractionation (TREF) profile, as measured by CFC.

3. The process of claim 1 , wherein the composition has, according to gel permeation chromatography coupled with Fourier transform infrared spectroscopy (GPC-FTIR), an angular coefficient b that ranges from −5 to 5 over a molecular weight (M) range of log(M) of 3.5 to 5.5,
where the angular coefficient b is provided by a linear regression of a curve obtained by plotting short chain branches per 1000 total carbon atoms (SCB/1000TC) vs. log(M) according to equation SCB/1000TC=blog(M)+a, where a is a linear coefficient.

4. The process of claim 1 , wherein the composition satisfies one or more of the following as determined by crystallization elution fractionation (CEF):
a room temperature soluble fraction, F sol , which is soluble at a temperature below 30° C., has a ratio of A1/Atotal of 30 or less, where A1 is a sum of total peak areas of components that are eluted below 30° C. and Atotal is a sum of total peak areas of components that are eluted at 0 to 140° C.;
a fraction eluted at 40° C. to 80° C. has a ratio A2/Atotal of 40 or more, where A2 is a sum of total peak areas of components that are eluted at 40° C. to 80° C.; and
a fraction eluted at 80° C. to 140° C. has a ratio A3/Atotal ranging from 28 to 40, where A3 is a sum of total peak areas related to components that are eluted at 80° C. to 140° C.

5. The process of claim 1 , wherein the composition comprises a monomeric unit derived from one of the one or more C4-C8 α-olefins in an amount of 1 to 10 mol %, as measured by 13 C NMR.

6. The process of claim 1 , wherein S×1/Stotal is 0.35 or less and S×2/Stotal is 0.65 or more.

7. The process of claim 1 , wherein the composition has an SCB/1000TC variation, as measured by GPC-FTIR, of 30% or less.

8. The process of claim 1 , wherein the composition has a number average molecular weight (Me) of at least about 10 kDa.

9. The process of claim 1 , wherein the composition has a weight average molecular weight (M w ) that ranges from about 118 kDa to about 1,250 kDa.

10. The process of claim 1 , wherein a molecular weight distribution (MWD) of the composition ranges from about 2 to 30.

11. The process of claim 1 , wherein the composition has a crystallinity (w c ), as measured by DSC, ranging from about 20% to 50% and a melting temperature (T m ) ranging from about 110° C. to 125° C.

12. The process of claim 1 , wherein the composition has a density, as measured in accordance with ASTM D-792, ranging from about 0.900 to 0.950 g/cm 3 .

13. The process of claim 1 , wherein the polymerization is a gas-phase polymerization.

14. The process of claim 1 , wherein the polymerization occurs in a plurality of reactors in series.

15. The process of claim 1 , wherein the alkylaluminum cocatalyst is a trialkylaluminum, wherein the trialkylaluminum is one or more selected from the group consisting of trimethylaluminum, triethylaluminum, and trisobutylaluminum.

16. The process of claim 1 , wherein the molar ratio of Al:Ti ranges from 3 to 24.

17. The process of claim 1 , wherein the Ti-containing Ziegler-Natta procatalyst comprises:
a particulate silica carrier in an amount of 65 to 85% by weight of the procatalyst; and
a catalytically active portion in an amount of 15 to 35% by weight of the procatalyst.

18. The process of claim 17 , wherein the Ti-containing Ziegler-Natta procatalyst is synthesized by a process comprising the steps of:
(a) impregnating an activated particulate silica using a solution of a group 13 organometallic compound in an amount ranging from 0.1 to 1 mmole of an organometallic solution per mmole of OH on a silica surface, in an inert organic solvent;
(b) removing a supernatant liquid from the step (a);
(c) preparing a solution obtained by reacting at least one magnesium compound, selected from magnesium halides or magnesium alkoxides, in an amount ranging from 0.0024 to 0.24 g of magnesium per g of silica, and at least one titanium compound, selected from titanium alkoxides or titanium halogen alkoxides, in an amount ranging from 0.01 to 1 g of titanium per g of silica;
(d) impregnating the silica obtained in (b) using the solution prepared in (c);
(e) optionally reacting a solid obtained in (d) with a reducing agent selected from the group consisting of Na alkyls, Li-alkyls, Zn-alkyls, Mg-alkyls and corresponding aryl-derivatives, Grignard compounds of the type RMgX, polyhydrosiloxanes,
wherein R represents a linear or branched alkyl group, containing from 1 to 10 carbons or aryl-derivatives and X represents a halogen atom, and A1-alkyl halide or silicon compounds;
(f) reacting a solid obtained in (d) or (e) with a halogenating agent selected from the group consisting of methylaluminum dichloride, methylaluminum sesquichloride, isobutylaluminum dichloride, isobutylaluminum sesquichloride, ethylaluminum dichloride (EADC), diethylaluminum chloride (DEAC), ethylaluminum sesquichloride (EASC), SiCl4, SnCl4, HCl, Cl2, HSiCl3, aluminium chloride, ethylboron dichloride, boron chloride, diethylboron chloride, HCCl3, PCl3, POCl3, acetyl chlorides, thionyl chloride, sulfur chloride, methyl trichlorosilane, dimethyl dichlorosilane, TiCl4, VCl4, CCl4, t-butylchloride, n-butyl chloride, chloroform, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,2-dichloroethane and dichloromethane;
(g) maintaining a solid obtained in (f) at a temperature from 60° C. to 120° C. from 0.5 hour to 5 hours;
(h) washing a solid obtained in (g) with an inert organic solvent;
(i) optionally washing the solid obtained in (h) with a solution of one or more organometallic compounds of group 13 of the periodic table in an amount ranging from 0 to 3 g of the organometallic compound per g of a dry procatalyst component obtained.

19. The process of claim 17 , wherein the Ti-containing Ziegler-Natta procatalyst is free of polar solvents and electron donors

Assignees

• Braskem Sa

Inventors

• Miranda Márcia Silva Lacerda
• Martins Junior Olavo
• Yu Yue
• Boisson Christophe
• Mckenna Timothy Frederick Llewellyn

Classifications

• C08F210/16 Primary

  Copolymers of ethene with alpha-alkenes, e.g. EP rubbers · CPC title

• C08F4/76

  selected from titanium, zirconium, hafnium, vanadium, niobium or tantalum · CPC title

• C08F210/08

  Butenes · CPC title

• C08F2500/05

  Bimodal or multimodal molecular weight distribution · CPC title

• C08F2500/37

  Elution or crystallisation fractionation, e.g. as determined by. TREF or Crystaf · CPC title