High molecular weight multimodal elastomer compositions with good processability

Patent metadata

Field	Value
Publication number	US-10815326-B2
Application number	US-201616063308-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 foamable elastomer 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 within a range from 65 to 90 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 80 to 120 MU (ML, 1+8 @ 150° C.);
(ii) a Mooney relaxation area to Mooney viscosity ratio (MLRA/ML) measured at 150° C. within a range of 11 to 15;
(iii) a molecular weight distribution (Mw(LS)/Mn(DRI)) within a range of 4 to 7; and
(iv) branching index (BI) within a range from 3 to 7, 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 70 to 80 MU (ML, 1+8 @ 150° C.), and the second polymer fraction has Mooney viscosity within a range of 250 to 1200 MU (ML, 1+8 @ 150° C.).

3. The composition of claim 1 , wherein the blend has all of the properties (i)-(iv), and further has one or more of the following properties:
(v) tan(δ) at 11 rad/sec within a range from 0.3 to 0.5;
(vi) dynamic viscosity η′ (11 rad/sec) within a range from 11,000 to 14,000 Pa-sec;
(vii) dynamic viscosity η′ (300 rad/sec) within a range from 500 to 600 Pa-sec; and
(viii) shear thinning ratio (STR, η′(11 rad/sec)/η′ (300 rad/sec)) within a range from 20 to 30.

4. The composition of claim 1 , wherein the blend comprises 88 to 92 wt % of the first polymer fraction and 8 to 12 wt % of the second polymer fraction.

5. The composition of claim 1 , wherein the Mooney viscosity of the blend is within a range from 85 to 100 MU (ML, 1+8 @ 150° C.).

6. The composition of claim 1 , wherein an ethylene content of the blend is within a range from 40 to 80 wt %, an 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, 7 to 12 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 blend comprises substantially no extender oil.

10. The composition of claim 1 , wherein the blend is a reactor blend formed using a Ziegler-Natta catalyst system comprising a VCl 4 catalyst and an ethyl aluminum sesquichloride co-catalyst.

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

12. The composition of claim 11 , wherein the blend further has all of the properties (v)-(viii).

13. An at least partially cross-linked and foamed elastomeric compound made by mixing and foaming a formulation comprising:
(a) a foamable elastomer composition according to claim 1 ;
(b) one or more vulcanization activators;
(c) one or more vulcanizing agents;
(d) a paraffinic process oil present in the formulation in an amount within a range from 80 to 150 parts by weight per 100 parts by weight of the foamable elastomer composition, said paraffinic process oil having a viscosity at 40° C. within a range from 80 to 600 CSt;
(e) one or more foaming agents; and
(f) optionally, one or more further additives.

14. 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.

15. The compound of claim 13 , wherein a Mooney viscosity of the blend is within a range from 80 to 120 MU (ML, 1+8 @ 150° C.), and the Mooney viscosity of the compound is within a range from 30 to 60 MU (ML 1+4 at 100° C.).

16. The compound of claim 15 , wherein a Mooney viscosity of the compound is within a range from 40 to 50 MU (ML, 1+4 @ 100° C.).

17. The compound of claim 13 , wherein a ratio compound Mooney viscosity (ML, 1+4 @ 100° C.) to elastomer composition Mooney viscosity (ML, 1+8 @ 150° C.) is between 0.25 to 0.35.

18. 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 90 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 80 to 120 MU (ML, 1+8 @ 150° C.), and molecular weight distribution (Mw(LS)/Mn(DRI) within a range from 4 to 7.

19. The method of claim 18 , wherein the reactor blend further has a Mooney relaxation area to Mooney viscosity ratio (MLRA/ML) within a range of 11 to 15 sec and branching index (BI) within the range from 3 to 7.

20. The method of claim 18 , wherein the Ziegler-Natta catalyst system comprises a VCl 4 catalyst and an ethyl aluminum sesquichloride co-catalyst.

21. The method of claim 18 , 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 extender oil.

22. The method of claim 18 , wherein the reactor blend comprises 50 to 60 wt % ethylene-derived units, 7 to 12 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
• Gallez Vincent B

Classifications

• C08K3/04 Primary

  Carbon · CPC title

• C08F2500/01

  High molecular weight, e.g. >800,000 Da. · CPC title

• C08L2205/06

  having improved processability or containing aids for moulding methods · CPC title

• C08K2003/2296

  of zinc · CPC title

• C08K5/39

  Thiocarbamic acids; Derivatives thereof, e.g. dithiocarbamates · CPC title