Porous propylene polymers

Patent metadata

Field	Value
Publication number	US-9725569-B2
Application number	US-201615142021-A
Country	US
Kind code	B2
Filing date	Apr 29, 2016
Priority date	Jun 5, 2015
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

This invention relates to high porosity (≧15%) and/or low pore diameter (PD<165 μm) propylene polymers and propylene polymerization processes using single site catalyst systems with supports having high surface area (SA≧400 m 2 /g), low pore volume (PV≦2 mL/g), a specific mean pore diameter range (PD=1-20 nm), and high average particle size (PS≧30 μm).

First claim

What is claimed is:

1. A propylene polymer comprising at least 50 mol % propylene and having:
1) a 1% Secant flexural modulus of at least 1000 MPa, determined according to ASTM D 790 (A, 1.0 mm/min);
2) greater than 5 and less than 200 regio defects, defined to be the sum of 2,1-erythro and 2,1-threo insertions and 3,1-isomerizations, per 10,000 propylene units, determined by 13 C NMR;
3) when comonomer is present, a composition distribution breadth index (CDBI) of 50% or more;
4) a matrix having a porosity of 15% or more and a median pore diameter of between greater than 6 and less than 160 μm, as determined by mercury intrusion porosimetry.

2. The propylene polymer of claim 1 , wherein the porosity is 30% or more.

3. The propylene polymer of claim 1 , comprising a multimodal molecular weight distribution.

4. The propylene polymer of claim 1 , wherein the polymer is in a particulated form wherein at least 95% by volume has a particle size greater than about 120 μm.

5. The propylene polymer of claim 1 , comprising a multimodal particle size distribution.

6. The propylene polymer of claim 1 , further comprising an active catalyst system dispersed in the matrix, the catalyst system comprising a single site catalyst precursor compound, an activator for the precursor compound, and a support having a specific surface area of 400 m 2 /g or more, a pore volume of from 0.5 to 2 mL/g, and a mean pore diameter of from 1 to 20 nm (10 to 200 Å).

7. A polypropylene impact copolymer comprising the propylene polymer of claim 1 , where a fill phase at least partially filling the pores in the matrix of the propylene polymer.

8. The propylene polymer of claim 1 , further comprising:
a total propylene content of at least 75 wt %;
when comonomer is present, a total co-monomer content from about 3 wt % up to about 25 wt %
and a CDBI of at least 60%;
a matrix porosity of at least 35%;
a matrix median pore diameter greater than 8 μm and less than 150 μm, as determined by mercury intrusion porosimetry;
at least 50% isotactic pentads;
more than 10 regio defects per 10,000 propylene units, determined by 13 C NMR;
a 1% Secant flexural modulus of at least 1800 MPa;
a melting point (Tm, DSC peak second melt) of at least 145° C.;
at least 95% by volume having a particle size greater than 150 μm up to 10 mm;
a melt flow rate (MFR, ASTM 1238, 230° C., 2.16 kg) from about 0.1 dg/min up to about 300 dg/min;
an Mw (as measured by GPC-DRI) from 50,000 to 1,000,000 g/mol; or
a combination thereof.

9. A process to polymerize propylene comprising:
(a) contacting propylene monomer under polymerization conditions with a catalyst system, the catalyst system comprising a single site catalyst precursor compound, an activator, and a support, wherein the support has an average particle size of from 30 microns up to 200 microns, a surface area of 400 m 2 /g or more, a pore volume of from 0.5 to 2 mL/g, and a mean pore diameter of from 1 to 20 nm (10 to 200 Å), as determined by BET nitrogen adsorption; and
(b) forming a matrix of propylene polymer comprising at least 50 mol % propylene and a porosity of 15% or more and a median pore diameter of between greater than 6 and less than 160 μm, as determined by mercury intrusion porosimetry, wherein the propylene polymer has:
1) a 1% Secant flexural modulus of at least 1000 MPa, determined according to ASTM D 790 (A, 1.0 mm/min);
2) greater than 5 and less than 200 regio defects, defined to be the sum of 2,1-erythro and 2,1-threo insertions and 3,1-isomerizations, per 10,000 propylene units, determined by 13 C NMR; and
3) when comonomer is present, a composition distribution breadth index (CDBI) of 50% or more.

10. The process of claim 9 , wherein the support comprises agglomerates of a plurality of primary particles.

11. The process of claim 10 , further comprising fragmenting the agglomerates to disperse catalyst sites in the propylene polymer matrix.

12. The process of claim 9 , wherein the support comprises spray dried silica, the spray dried silica having an average particle size of more than 50 μm, a specific surface area less than 1000 m 2 /g, or a combination thereof.

13. The process of claim 9 , wherein the specific surface area is more than 650 m 2 /g and the mean pore diameter is less than 7 nm (70 Å).

14. The process of claim 9 , wherein the specific surface area is less than 650 m 2 /g or the mean pore diameter is greater than 7 nm (70 Å).

15. The process of claim 9 , wherein the activator comprises alumoxane.

16. The process of claim 9 , wherein the catalyst system further comprises a co-activator, selected from the group consisting of: trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-octylaluminum, trihexylaluminum, and diethylzinc.

17. The process of claim 9 , wherein the contacting of the propylene monomer with the catalyst system is carried out in a slurry.

18. The process of claim 9 , wherein the polymerization conditions comprise a pressure of from about 0.96 MPa (140 psi) to about 7 MPa (1 kpsi), a temperature of from about −20° C. to 150° C., a residence time from 15 to 720 minutes, with or without hydrogen present, and with or without an ethylene or C 4 to C 20 comonomer present.

19. The process of claim 9 , wherein the propylene monomer in (a) is essentially free of ethylene and C 4 to C 20 alpha olefins, and the propylene polymer formed is a propylene homopolymer.

20. The process of claim 9 , further comprising varying a concentration of hydrogen or other chain transfer agent in (a), and wherein the propylene polymer formed in (b) comprises a multimodal molecular weight distribution.

21. The process of claim 9 , further comprising contacting the propylene polymer matrix from (b) with one or more alpha-olefin monomers under polymerization conditions to form a heterophasic copolymer comprising a fill phase at least partially filling the pores in the matrix.

22. The process of claim 9 , further comprising melt processing the propylene polymer at a shear rate of 1000 sec −1 or more.

23. The process of claim 9 , wherein the single site catalyst precursor compound is represented by the following formula:
(Cp) m R A n M 4 Q k
wherein:
each Cp is a cyclopentadienyl moiety or a substituted cyclopentadienyl moiety substituted by one or more hydrocarbyl radicals having from 1 to 20 carbon atoms;
R A is a structural bridge between two Cp moieties;
M 4 is a transition metal selected from groups 4 or 5;
Q is a hydride or a hydrocarbyl group having from 1 to 20 carbon atoms or an alkenyl group having from 2 to 20 carbon atoms, or a halogen;
m is 1, 2, or 3, with the proviso that if m is 2 or 3, each Cp may be the same or different;
n is 0 or 1, with the proviso that n=0 if m=1; and
k is such that k+m is equal to the oxidation state of M 4 , with the proviso that if k is greater than 1, each Q may be the same or different.

24. The process of claim 9 , wherein the single site catalyst precursor compound is represented by the formula:
R A (CpR″ p )(CpR* q )M 5 Q r

wherein:
each Cp is a cyclopentadienyl moiety or substituted cyclopentadienyl moiety;
each R* and R″ is a hydrocarbyl group having from 1 to 20 carbon atoms and may the same or different;
p is 0, 1, 2, 3, or 4;
q is 1, 2, 3, or 4;
R A is a structural bridge between the Cp moieties imparting stereorigidity to the metallocene compound;
M 5 is a group 4, 5, or 6 metal;
Q is a hydro

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Holtcamp Matthew W
• Day Gregory S
• Yang Jian
• Luo Lubin
• Brown Steven D
• Hule Rohan A

Classifications

• C08F10/06 Primary

  Propene · CPC title

• C08J9/00 Primary

  Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof (mechanical aspects of shaping of plastics or substances in a plastic state for the production of porous or cellular articles B29C) · CPC title

• C08F2500/18

  Bulk density · CPC title

• C08F4/6492

  containing aliphatic unsaturation · CPC title

• C08F110/06

  Propene · CPC title