Compatibilized Thermoplastic Vulcanizate Compositions

• US 20190309152A1
• 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: Datta, Sudhin, Tsou, Andy H., Walker, Ron, Anantha Narayana Iyer, Krishnan, Khakdaman, Hamidreza, Slaughter, Kimari T.M., Vasquez, Sebastian
• Granted Patent: US 11,174,332 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

This invention relates to a thermoplastic vulcanizate having excellent elongation comprising an isotactic polypropylene matrix phase in which a cross-linked ethylene-propylene-diene terpolymer (EPDM) is dispersed, the vulcanizate comprising the reaction product of:

• a) 35 to 55 wt % of an ethylene-propylene-diene terpolymer (EPDM);
• b) 10 to 40 wt % of isotactic polypropylene (iPP);
• c) 0.5 to 25 wt % of a propylene-ethylene-diene terpolymer (PEDM) compatibilizer, said compatibilizer having a heat of fusion of less than 2 J/g; and
• d) 0.015 to 0.03 wt % of curatives;
• wherein the percentages of components (a) to (d) are based on the total weight of the mixture.

Claims

1. A thermoplastic vulcanizate comprising an isotactic polypropylene matrix phase in which a cross-linked ethylene-propylene-diene terpolymer (EPDM) is dispersed, the vulcanizate comprising the reaction product of:

a) 35 to 55 wt % of an ethylene-propylene-diene terpolymer (EPDM);

b) 10 to 40 wt % of isotactic polypropylene (iPP);

c) 0.5 to 25 wt % of a propylene-ethylene-diene terpolymer (PEDM) compatibilizer, said compatibilizer having a heat of fusion of less than 2 J/g; and

d) 0.015 to 0.03 wt % of curatives;

wherein the percentages of components (a) to (d) are based on the total weight of the mixture.

2. The thermoplastic vulcanizate of claim 1, further comprising at least 10 wt % of a diluent.

3. The thermoplastic vulcanizate of claim 1, in which the EPDM comprises propylene, 55 to 75 wt % ethylene, and 2 to 10 wt % 5-ethylidene-2-norbornene.

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

5. The thermoplastic vulcanizate of claim 1, in which the PEDM has viscosity of MST (5+4) @230C is from 5 to 90.

6. The thermoplastic vulcanizate of claim 1, in which the PEDM comprises 5 to 18 wt % ethylene and 2 to 12 wt % 5-ethylidene-2-norbornene.

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

8. The thermoplastic vulcanizate of claim 1, further comprising clay and carbon black.

9. The thermoplastic vulcanizate of claim 1, wherein the PEDM has a heat of fusion (Hf) which is less than 0.5 J/g.

10. The thermoplastic vulcanizate of claim 1, wherein the PEDM has no detectable heat of fusion (Hf) when measured by DSC.

21. The thermoplastic vulcanizate of claim 1, wherein the thermoplastic vulcanizate has a Dw/Dn of 7 or less.

22. The thermoplastic vulcanizate of claim 1, wherein the thermoplastic vulcanizate has a tension set at 50% elongation of 14% or less.

23. The thermoplastic vulcanizate of claim 1, wherein the thermoplastic vulcanizate has a tension set at 50% elongation of 14% or less and a Dw/Dn of 7 or less.

24. The thermoplastic vulcanizate of claim 1, wherein the thermoplastic vulcanizate has:

1) a Dw/Dn of 7 or less;

2) a tension set at 50% elongation of 14% or less;

3) an elongation at break of 200% or more;

4) a break stress of 4 MPa or more;

5) a tension set from 25% elongation of 7% or less;

6) a number average particle size diameter of the rubber particles of 800 nm or less;

7) a dispersity of crosslinked particle size diameter of the rubber particles of 1.6 or less.

11. A method for preparing a thermoplastic vulcanizate (TPV) comprising:

i) mixing an iPP, EPDM, and PEDM having a heat of fusion of less than 2 J/g, and a diluent to prepare a TPV formulation;

ii) adding one or more curatives to the TPV formulation and continuing mixing to perform dynamic vulcanization; and

iii) recovering A TPV composition.

12. The method of claim 11, further comprising adding a diluent to the TPV formulation prior to step ii) and continuing mixing.

13. The method of claim 12, further comprising adding a further portion of diluent following step ii) and continuing mixing and dynamic vulcanization to form a TPV composition.

14. The method of claim 13, in which the curatives are a phenolic resin in oil (RIO) composition, stannous chloride, and zinc oxide.

15. The method of claim 14, in which the ethylene-propylene-diene terpolymer (EPDM) is added in an amount from 35-55 wt % of the TPV formulation, the isotactic polypropylene (iPP) is added in an amount from 10 to 40 wt % of the TPV formulation;

diluent is added in an amount from 13 to 21 wt % of the TPV formulation, a propylene-ethylene-diene terpolymer (PEDM) compatibilizer is added in an amount from 0.5-15 wt % of the TPV formulation.

16. The method of claim 15, which is performed at a temperature of from 150 to 200°

C. in an internal mixer running at from 80 to 120 rpm and mixing continues for about 1 minute prior to step ii), for about 2 minutes after the first addition of diluent, for about 5 minutes after the second addition of diluent and for about 3 minutes after step iii).

17. The method of claim 15, which is performed at a temperature from 200 to 250°

C. in a continuous twin-screw extruder running at from 50 to 200 RPM with 1 to 5 minutes of residence time wherein the iPP, EPDM, and PEDM, and first portion of a diluent are added to the extruder at a first position of the extruder, and at least one of the second portion of diluent, the curatives and the third portion of diluent are added to the extruder at least a second position downstream from the first position.

18. The method of claim 15, that is performed at a temperature of from 150 to 200°

C. in an internal mixer running at from 80 to 120 rpm and mixing continues for about 1 minute after step i), for about 2 minutes after the first addition of diluent, for about 5 minutes after the second addition of diluent and for about 3 minutes after step iii); and

then mixing is performed for about 1 to 5 additional minutes.

19. The method of claim 15, that is performed at a temperature from 200 to 250°

C. in a continuous twin-screw extruder running at from 50 to 200 RPM with 1 to 5 minutes of residence time; and

in which the RIO composition is added to the extruder at a first position, followed by additional mixing.

20. The method of claim 11, wherein the PEDM has a heat of fusion (Hf) which is greater than or equal to 0 and less than or equal to 2 J/g.