High molecular weight multimodal elastomer compositions with good processability

Patent metadata

Field	Value
Publication number	US-10815325-B2
Application number	US-201615781486-A
Country	US
Kind code	B2
Filing date	Dec 15, 2016
Priority date	Jan 19, 2016
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

Provided herein are multimodal elastomer compositions comprising a first polymer fraction and a second polymer fraction, and methods for making such compositions. The elastomer compositions are preferably ethylene, α-olefin, copolymers or ethylene, α-olefin, polyene terpolymers. The elastomer compositions have high Mooney viscosity, thereby providing for improved elastomeric properties in compounds and other articles formed from the elastomer compositions. Surprisingly, the high Mooney viscosity compositions exhibit a much lower than expected viscosity when formulated into elastomer compounds. Thus, the processing detriments typically associated with high Mooney viscosity elastomers are minimized through the use of the elastomer compositions, and methods for making them, disclosed herein.

First claim

We claim:

1. A composition comprising:
a blend of 85 to 95 wt % of a first polymer fraction and 5 to 15 wt % of a second polymer fraction, said wt % s determined on the basis of total weight of the blend;
wherein said first polymer fraction has Mooney viscosity of at least 50 MU (ML, 1+8@150° C.);
wherein said second polymer fraction has Mooney viscosity that is at least 150 MU (ML, 1+8@150° C.) greater than the Mooney viscosity of the first polymer fraction;
wherein each of the first and second polymer fractions independently comprises units derived from ethylene, one or more C 3 -C 20 α-olefins, and, optionally, one or more non-conjugated polyenes; and further
wherein the blend has one or more of the following properties:

(i) Mooney viscosity within a range of 70 to 100 MU (ML, 1+8@150° C.);
(ii) a Mooney relaxation area to Mooney viscosity ratio (MLRA/ML) measured at 150° C. within the range of 10 to 15;
(iii) a molecular weight distribution (Mw(LS)/Mn(DRI)) within a range of 4 to 7; and
(iv) a branching index (BI) of 6 to 10, measured by Rubber Process Analyzer at 150° C., 0.63 radian/second and 1000% oscillation amplitude.

2. The composition of claim 1 , wherein the first polymer fraction has Mooney viscosity within a range of 60 to 75 MU (ML, 1+8@150° C.), and the second polymer fraction has Mooney viscosity within a range of 275 to 400 MU (ML, 1+8@150° C.).

3. The composition of claim 1 , wherein the blend has all of the properties (i)-(iv).

4. The composition of claim 1 , wherein the blend comprises 88.5 to 89.5 wt % of the first polymer fraction and 10.5 to 11.5 wt % of the second polymer fraction.

5. The composition of claim 1 , wherein the Mooney viscosity of the blend is within a range of 77 to 87 MU (ML, 1+8@150° C.), and further wherein MLRA/ML at 150° C. of the blend is within a range of 10 to 12.

6. The composition of claim 1 , wherein the ethylene content of the blend is within the range from 40 to 80 wt %, the α-olefin content of the blend is within a range from 5 to 60 wt %, and a non-conjugated polyene content is within a range from 0 to 15 wt %, where the wt % s are based upon a total weight of the blend.

7. The composition of claim 1 , wherein the α-olefin is propylene, and the non-conjugated polyene, if present, is 5-ethylidene-2-norbornene (ENB).

8. The composition of claim 7 , wherein the blend comprises 50 to 60 wt % ethylene-derived units, 5 to 8 wt % ENB-derived units, and a balance propylene-derived units, the wt % s on a basis of total weight of the blend.

9. The composition of claim 1 , wherein the composition includes substantially no extender oil.

10. The composition of claim 1 , wherein the blend is a reactor blend.

11. The composition of claim 10 , wherein the reactor blend is formed by Ziegler-Natta polymerization.

12. The composition of claim 11 , wherein the reactor blend is formed using a Ziegler-Natta catalyst system comprising a VCl 4 catalyst and an ethyl alumnium sesquichloride co-catalyst.

13. An at least partially cross-linked elastomeric compound made by mixing a formulation comprising:
(a) a multimodal elastomer composition according to claim 1 ;
(b) one or more vulcanization activators;
(c) one or more vulcanizing agents; and
(d) optionally, one or more further additives.

14. The compound of claim 13 , wherein the compound further comprises a paraffinic process oil present in the formulation between 1 and 150 phr, said paraffinic process oil having a viscosity at 40° C. within a range from 80 to 600 CSt.

15. The compound of claim 13 , wherein the compound comprises one or more further additives selected from the group consisting of a carbon black and a mineral filler.

16. The compound of claim 13 , wherein the mixing comprises mixing in one of an open mill, an internal mixer, and an extruder.

17. The compound of claim 13 , wherein the Mooney viscosity of the blend is within a range from 77 to 87 MU (ML, 1+8@150° C.), and the Mooney viscosity of the compound is within a range from 80 to 100 MU (ML 1+4 at 100° C.).

18. The compound of claim 17 , wherein the Mooney viscosity of the compound is within a range from 85 to 95 MU (ML, 1+4@100° C.).

19. The compound of claim 13 , wherein a ratio of compound Mooney viscosity (ML, 1+4@100° C.) to composition Mooney viscosity (ML, 1+8@150° C.) is between 1.0 and 1.1.

20. A method for making a reactor blend, the method comprising:
(a) feeding to a first polymerization reaction zone (i) a plurality of monomers comprising ethylene, one or more C 3 -C 20 α-olefins, and, optionally, one or more non-conjugated polyenes, and (ii) a Ziegler-Natta catalyst system comprising a Ziegler-Natta catalyst and one or more co-catalysts;
(b) forming, in the first polymerization reaction zone, a first polymer reaction product having Mooney viscosity within a range of 65 to 74 MU (ML, 1+8@150° C.);
(c) withdrawing a first polymerization reaction effluent comprising at least a portion of the first polymer reaction product from the first polymerization reaction zone;
(d) providing to a second polymerization reaction zone at least a portion of the first polymerization reaction effluent, ethylene, one or more C 3 -C 20 α-olefins, and, optionally, one or more polyenes;
(e) forming, in the second polymerization reaction zone, a second polymer reaction product having Mooney viscosity that is at least 150 MU (ML, 1+8@150° C.) greater than the Mooney viscosity of the first polymer reaction product; and
(f) withdrawing from the second polymerization reaction zone a second polymerization reaction effluent comprising the reactor blend;
wherein the reactor blend comprises an unreacted portion of the first polymer reaction product and the second polymer reaction product, and further has Mooney viscosity within a range from 77 to 87 MU (ML, 1+8@150° C.), and a molecular weight distribution (Mw(LS)/Mn(DRI) within a range from 4 to 7.

21. The method of claim 20 , wherein the reactor blend further has a Mooney relaxation area to Mooney viscosity ratio (MLRA/ML) within a range of 10 to 15 sec and branching index (BI) within a range from 6 to 10.

22. The method of claim 20 , wherein the Ziegler-Natta catalyst system comprises a VCl 4 catalyst and an ethyl aluminum sesquichloride co-catalyst.

23. The method of claim 20 , further comprising:
(g) providing the second polymerization reaction effluent to a devolatilization process without adding oil; and
(h) obtaining a devolatilized elastomer composition that is substantially free of extension oil.

24. The method of claim 20 , wherein the reactor blend comprises 50 to 60 wt % ethylene-derived units, 5 to 8 wt % ENB-derived units, and a balance propylene-derived units, the wt % s on a basis of total weight of the reactor blend.

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Jourdain Eric P
• Arinal Clement
• Jachowski Hans D

Classifications

• C08K3/04 Primary

  Carbon · CPC title

• C08L2314/02

  Ziegler natta catalyst · CPC title

• C08F2/34

  Polymerisation in gaseous state · CPC title

• C08F210/18 Primary

  with non-conjugated dienes, e.g. EPT rubbers · CPC title

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title