Thermoplastic vulcanizate compositions

Patent metadata

Field	Value
Publication number	US-10927207-B2
Application number	US-201916356951-A
Country	US
Kind code	B2
Filing date	Mar 18, 2019
Priority date	Apr 6, 2018
Publication date	Feb 23, 2021
Grant date	Feb 23, 2021

Abstract

A thermoplastic vulcanizate comprises an isotactic polypropylene matrix phase in which cross-linked rubber particles are dispersed, the rubber particles comprising an ethylene-propylene-diene terpolymer (EPDM) containing at least 40 wt % of ethylene-derived units. A propylene-ethylene-diene terpolymer (PEDM) containing at least 60 wt % propylene-derived units and less than or equal to 25 wt % of ethylene-derived units and having a heat of fusion (Hf) of 2 to 10 J/g is added to compatibilize the propylene/EPDM blend.

First claim

The invention claimed is:

1. A thermoplastic vulcanizate comprising an isotactic polypropylene matrix phase in which cross-linked rubber particles are dispersed, the thermoplastic vulcanizate comprising the reaction product of a mixture comprising:
(a) at least 10 wt % of isotactic polypropylene;
(b) at least 25 wt % of an ethylene-propylene-diene terpolymer (EPDM) containing at least 40 wt % of ethylene-derived units;
(c) at least 0.5 wt % of a propylene-ethylene-diene terpolymer (PEDM) containing at least 60 wt % propylene-derived units and less than or equal to 25 wt % of ethylene-derived units and having a heat of fusion (H f ) of 2 to 10 J/g; and
(d) at least 0.015 wt % of at least one curative,
wherein the percentages of components (a) to (d) are based on the total weight of the mixture.

2. The thermoplastic vulcanizate of claim 1 , wherein the PEDM comprises 5 to 18 wt % of ethylene-derived units.

3. The thermoplastic vulcanizate of claim 1 , wherein the PEDM comprises 0.3 to 10 wt % of diene-derived units; where the diene is selected from the group consisting of 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, divinyl benzene, and dicyclopentadiene.

4. The thermoplastic vulcanizate of claim 1 , wherein the PEDM has a Mooney viscosity of MST (5+4) at 230° C. from 10 to 90.

5. The thermoplastic vulcanizate of claim 1 , in which the amount of PEDM is from 2 to 30 wt % of the amount of EPDM.

6. The thermoplastic vulcanizate of claim 1 , wherein the particle size dispersity index (PSDI) of the rubber particles is less than 3.

7. The thermoplastic vulcanizate of claim 1 and further comprising at least 5 wt % of a diluent based on the total weight of the mixture.

8. A thermoplastic vulcanizate comprising an isotactic polypropylene matrix phase in which cross-linked rubber particles are dispersed, the thermoplastic vulcanizate comprising the reaction product of a mixture comprising:
a) 20 to 30 wt % of isotactic polypropylene (iPP);
b) 35 to 55 wt % of an ethylene-propylene-diene terpolymer (EPDM) containing at least 40 wt % of ethylene-derived units;
c) 0.5 to 15 wt % of a propylene-ethylene-diene terpolymer (PEDM) containing at least 60 wt % propylene-derived units and less than or equal to 25 wt % of ethylene-derived units and having a heat of fusion (H f ) of 2 to 10 J/g;
d) 5 to 25 wt % of a diluent; and
e) 0.015 to 0.03 wt % of at least one curative;
wherein the percentages of components (a) to (e) are based on the total weight of the mixture.

9. The thermoplastic vulcanizate of claim 8 , wherein the PEDM comprises 5 to 18 wt % of ethylene-derived units.

10. The thermoplastic vulcanizate of claim 8 , wherein the PEDM comprises 0.3 to 10 wt % of diene-derived units; where the diene is selected from the group consisting of 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, divinyl benzene, and dicyclopentadiene.

11. The thermoplastic vulcanizate of claim 8 , wherein the PEDM has a Mooney viscosity of MST (5+4) at 230° C. from 10 to 90.

12. The thermoplastic vulcanizate of claim 8 , in which the amount of PEDM is from 2 to 30 wt % of the amount of EPDM.

13. The thermoplastic vulcanizate of claim 8 , wherein the particle size dispersity index (PSDI) of the rubber particles is less than 3.

14. A process for producing a thermoplastic vulcanizate (TPV) comprising:
i) providing a mixture comprising:
(a) at least 10 wt % of isotactic polypropylene;
(b) at least 25 wt % of an ethylene-propylene-diene terpolymer (EPDM) containing at least 50 wt % of ethylene-derived units;
(c) at least 0.5 wt % of a propylene-ethylene-diene terpolymer (PEDM) containing at least 60 wt % propylene-derived units and less than or equal to 25 wt % of ethylene-derived units and having a heat of fusion (H f ) of 2 to 10 J/g;
(d) at least 5 wt % of a diluent; and
(e) at least 0.015 wt % of at least one curative,
wherein the percentages of components (a) to (e) are based on the total weight of the mixture, and

(ii) reacting the mixture under shear and at a temperature above the melting point of the polypropylene to at least partially cross-link the EPDM and PEDM and produce a polypropylene matrix phase in which cross-linked rubber particles are dispersed.

15. The process of claim 14 , wherein the reacting (ii) is performed in a twin-screw extruder.

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Walker Ron
• Datta Sudhin
• Tsou Andy H
• Rohde Brian J
• Blanton Tamara L

Classifications

• C08F210/06

  Propene · CPC title

• C08F2500/17

  Viscosity · CPC title

• C08F236/20

  unconjugated · CPC title

• C08J3/212

  and solid additives · CPC title

• C08J3/005 Primary

  Processes for mixing polymers · CPC title