Thermoplastic vulcanizates comprising broad molecular weight distribution polypropylene

Patent metadata

Field	Value
Publication number	US-10323140-B2
Application number	US-201615132484-A
Country	US
Kind code	B2
Filing date	Apr 19, 2016
Priority date	May 29, 2015
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

Provided herein are thermoplastic vulcanizates that comprise rubber, broad molecular weight distribution polypropylene, and oil, where the rubber forms a rubber phase that is dispersed and at least partially cross-linked within a continuous thermoplastic component that comprises the broad molecular weight distribution polypropylene. The broad molecular weight distribution polypropylene preferably has a molecular weight distribution (Mw/Mn) of greater than 4; a melt flow rate of greater than 1 g/10 min; and a weight average molecular weight (Mw) of greater than 380,000 daltons.

First claim

We claim:

1. A thermoplastic vulcanizate comprising:
(i) a rubber comprising an ethylene-propylene diene rubber and 5-ethylidene-2-norbornene ENB diene content;
(ii) a broad molecular weight distribution polypropylene, where the broad molecular weight distribution polypropylene has:
(a) a molecular weight distribution (Mw/Mn) from 5 to 10;
(b) a melt flow rate (ASTM D1238 Condition L at 230° C. and 2.16 kg) of greater than 1 g/10 min; and
(c) a weight average molecular weight (Mw) of greater than 380,000 daltons; and

(iii) a hydrocarbon oil in the amount of 5 to 300 phr;
wherein the thermoplastic vulcanizate has an ultimate elongation (ASTM D638) of greater than 400%; wherein the thermoplastic vulcanizate has a Shore A hardness of greater than 50; wherein the thermoplastic vulcanizate comprises a rubber phase that is dispersed and at least partially cross-linked within a continuous thermoplastic component that comprises the broad molecular weight distribution polypropylene, wherein the thermoplastic vulcanizate further comprises a propylene-based elastomer comprising propylene and from about 5 to about 30 wt % of one or more comonomers selected from ethylene and/or C 4 -C 12 α-olefins, and wherein the propylene-based elastomer is a propylene-ethylene copolymer that has from about 9 wt % to about 15 wt % ethylene-derived units and has: (i) a melt index of from about 0.5 to about 3.0 g/10 min; (ii) a melt flow rate of from about 0.5 to about 7.0 g/10 min; and (iii) a Mooney viscosity of from about 10 to about 40.

2. The thermoplastic vulcanizate of claim 1 , wherein the thermoplastic vulcanizate comprises from about 7 wt % to about 45 wt % of the rubber, based on the total weight of the thermoplastic vulcanizate.

3. The thermoplastic vulcanizate of claim 1 , wherein the thermoplastic vulcanizate comprises from about 3 wt % to about 60 wt % of the broad molecular weight distribution polypropylene, based on the total weight of the thermoplastic vulcanizate.

4. The thermoplastic vulcanizate of claim 1 , wherein the broad molecular weight distribution polypropylene has a melt strength of at least 20 cN determined using an extensional rheometer at 190° C.

5. The thermoplastic vulcanizate of claim 1 , wherein the broad molecular weight distribution polypropylene has a molecular weight distribution greater than 5.

6. The thermoplastic vulcanizate of claim 1 , wherein the broad molecular weight distribution polypropylene has a viscosity ratio of greater than or equal to 17 as determined at an angular frequency ratio of 0.1 and at an angular frequency ratio of 100 rad/s (at an angular frequency ratio of 0.1 to 100 rad/s) at a fixed strain of 10% at 190° C.

7. The thermoplastic vulcanizate of claim 1 , wherein the broad molecular weight distribution polypropylene has a melt flow rate greater than 2 g/10 min.

8. The thermoplastic vulcanizate of claim 1 , wherein the broad molecular weight distribution polypropylene has a high load MFR (ASTM D1338 at 230° C.; 21.6 kg) of greater than 150 g/10 min.

9. The thermoplastic vulcanizate of claim 1 , wherein the broad molecular weight distribution polypropylene has a zero shear viscosity of greater than 28,000 Pa·s.

10. The thermoplastic vulcanizate of claim 1 , wherein the broad molecular weight distribution polypropylene has a number average molecular weight (Mn) of greater than 55,000 daltons.

11. The thermoplastic vulcanizate of claim 1 , wherein the broad molecular weight distribution polypropylene has a weight average molecular weight (Mw) of greater than 400,000 daltons.

12. The thermoplastic vulcanizate of claim 1 , wherein the broad molecular weight distribution polypropylene has a z-average molecular weight (Mz) of greater than 1,000,000.

13. The thermoplastic vulcanizate of claim 1 , wherein the broad molecular weight distribution polypropylene is made by a process that comprises contacting propylene monomers at a temperature and a pressure in the presence of catalyst system to produce a propylene resin comprising at least 50 mol % propylene, wherein the catalyst system comprises:
a Ziegler-Natta catalyst comprising a non-aromatic internal electron donor;
a first external electron donor having the formula R 1 2 Si(OR 2 ) 2 , wherein each R 1 is independently a hydrocarbyl radical comprising from 1 to 10 carbon atoms in which the carbon adjacent to the Si is a secondary or a tertiary carbon atom, and wherein each R 2 is independently a hydrocarbyl radical comprising from 1 to 10 carbon atoms; and
a second external electron donor having the formula R 3 n Si(OR 4 ) 4-n , wherein each R 3 and R 4 are independently a hydrocarbyl radical comprising from 1 to 10 carbon atoms, and n is 1, 2, or 3; and
where the second external electron donor is different than the first external electron donor.

14. The thermoplastic vulcanizate of claim 1 , wherein the thermoplastic vulcanizate comprises from about 10 wt % to about 55 wt % oil, based on the total weight of the thermoplastic vulcanizate.

15. A thermoplastic vulcanizate comprising a rubber phase dispersed and at least partially cross-linked in a continuous thermoplastic phase, the thermoplastic vulcanizate having:
(a) an ultimate elongation (ASTM D638) of greater than 400%;
(b) a Shore A hardness of greater than 50; and
(c) an ultimate tensile strength (ASTM D638) of greater than 7 MPa;
wherein the rubber phase comprises an ethylene-propylene diene rubber that has about 64 wt % ethylene content (as measured by ASTM D3900) and 4.5 wt % 5-ethylidene-2-norbomene ENB diene content (as measured by ASTM D6047) and the thermoplastic phase comprises a broad molecular weight distribution polypropylene having:
(i) a molecular weight distribution (Mw/Mn) from 5 to 10;
(ii) a melt flow rate (ASTM D1238 Condition L at 230° C. and 2.16 kg) of greater than 2 g/10 min; and
(iii) a weight average molecular weight (Mw) of greater than 410,000 daltons.

16. The thermoplastic vulcanizate of claim 15 , wherein the thermoplastic vulcanizate comprises from about 7 wt % to about 45 wt % of the rubber phase, based on the total weight of the thermoplastic vulcanizate.

17. The thermoplastic vulcanizate of claim 15 , wherein the thermoplastic vulcanizate comprises from about 3 wt % to about 60 wt % of the broad molecular weight distribution polypropylene, based on the total weight of the thermoplastic vulcanizate.

18. The thermoplastic vulcanizate of claim 15 , wherein the broad molecular weight distribution polypropylene has a melt strength of at least 20 cN determined using an extensional rheometer at 190° C.

19. The thermoplastic vulcanizate of claim 15 , wherein the broad molecular weight distribution polypropylene has a viscosity ratio of greater than or equal to 17 as determined at an angular frequency ratio of 0.1 and at an angular frequency ratio of 100 rad/s (at an angular frequency ratio of 0.1 to 100 rad/s) at a fixed strain of 10% at 190° C.

20. The thermoplastic vulcanizate of claim 15 , wherein the broad molecular weight distribution polypropylene has a zero shear viscosity of greater than 28,000 Pa·s.

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Shannon Porter C
• Chung Oscar O

Classifications

• C08L2205/22

  Mixtures comprising a continuous polymer matrix in which are dispersed crosslinked particles of another polymer · CPC title

• C08L2205/06

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

• C08L2205/02

  containing two or more polymers of the same C08L -group · CPC title

• C08L23/12 Primary

  Polypropene · CPC title

• C08L2205/03

  containing three or more polymers in a blend · CPC title