Thermoplastic Vulcanizate Compositions

• US 20190309153A1
• Filed: 03/18/2019
• Published: 10/10/2019
• Est. Priority Date: 04/06/2018
• Status: Active Grant

• Current Assignee: Celanese International Corporation (Celanese Corporation)
• Original Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Inventors: Walker, Ron, Datta, Sudhin, Tsou, Andy H., Rohde, Brian J., Blanton, Tamara L.
• Granted Patent: US 10,927,207 B2
• Time in Patent Office: Days
• CPC Class Codes: C08F 210/02 Ethene
• CPC Class Codes: C08F 210/06 Propene
• CPC Class Codes: C08F 210/18 with non-conjugated dienes, e.g. EPT rubbers
• CPC Class Codes: C08F 236/045 conjugated hydrocarbons other than butadiene or isoprene
• CPC Class Codes: C08F 236/20 unconjugated
• CPC Class Codes: C08F 2500/03 Narrow molecular weight distribution, i.e. Mw/Mn < 3
• CPC Class Codes: C08F 2500/12 Melt flow index or melt flow ratio
• CPC Class Codes: C08F 2500/17 Viscosity
• CPC Class Codes: C08F 2500/21 Rubbery or elastomeric properties
• CPC Class Codes: C08F 2500/24 Polymer with special particle form or size
• CPC Class Codes: C08F 2500/27 Amount of comonomer in wt% or mol%
• CPC Class Codes: C08F 4/65908 in combination with an ionising compound other than alumoxane, e.g. (C6F5)4B-X+
• CPC Class Codes: C08F 4/65927 two cyclopentadienyl rings being mutually bridged
• CPC Class Codes: C08J 2323/16 Ethene-propene or ethene-propene-diene copolymers
• CPC Class Codes: C08J 2423/12 Polypropene
• CPC Class Codes: C08J 3/005 Processes for mixing polymers
• CPC Class Codes: C08J 3/212 and solid additives
• CPC Class Codes: C08J 3/24 Crosslinking, e.g. vulcanising, of macromolecules mechanical aspects B29C35/00; crosslinking agents C08K
• CPC Class Codes: C08K 5/0025 Crosslinking or vulcanising agents; including accelerators
• CPC Class Codes: C08L 2205/025 containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
• CPC Class Codes: C08L 2205/03 : containing three or more polymers in a blend
• CPC Class Codes: C08L 2205/08 : containing additives to improve the compatibility between two polymers
• CPC Class Codes: C08L 2205/22 : Mixtures comprising a continuous polymer matrix in which are dispersed crosslinked particles of another polymer
• CPC Class Codes: C08L 2207/02 : Heterophasic composition
• CPC Class Codes: C08L 2207/10 : Peculiar tacticity
• CPC Class Codes: C08L 23/12 : Polypropene
• CPC Class Codes: C08L 23/142 : at least partially crystalline copolymers of propene with other olefins
• CPC Class Codes: C08L 23/16 : Elastomeric ethene-propene or ethene-propene-diene copolymers, e.g. EPR and EPDM rubbers
• CPC Class Codes: C08L 2312/00 : Crosslinking
• CPC Class Codes: C08L 2312/02 : with dienes

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 (H_f) of 2 to 10 J/g is added to compatibilize the propylene/EPDM blend.

Claims

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 (Hf) 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.