Thermoplastic vulcanizates and compositions therefrom
Disclosed is the preparation of thermoplastic vulcanizates with reduced crosslinked rubber dispersion sizes and dispersity. The thermoplastic vulcanizates include a polypropylene matrix phase in which cross-linked rubber particles are dispersed. The thermoplastic vulcanizates include the reaction product of a mixture that includes at least 10 wt % of isotactic polypropylene at least 30 wt % of an amorphous propylene-ethylene-diene terpolymer containing at least 60 wt % propylene-derived units and less than or equal to 25 wt % of ethylene-derived units; at least 10 wt % of a diluent and at least 0.015 wt % of at least one curative. The mixture is preferably formed without adding an ethylene-propylene-diene terpolymer.
1. A thermoplastic vulcanizate comprising a 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 30 wt % of a propylene-ethylene-diene terpolymer (PEDM) rubber containing at least 60 wt % propylene-derived units and less than or equal to 25 wt % of ethylene-derived units, where the PEDM is amorphous; and
(c) at least 0.015 wt % of at least one curative,
wherein the mixture is formed without adding an ethylene-propylene-diene terpolymer (EPDM) rubber, and the percentages of components (a) to (c) 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 viscosity from 10 to 90 MST (5+4) at 230° C.
5. The thermoplastic vulcanizate of claim 1 , in which the amount of PEDM is from 35 to 70 wt % of the mixture.
6. The thermoplastic vulcanizate of claim 1 , in which the amount of PEDM is from 40 to 60 wt % of the mixture.
7. The thermoplastic vulcanizate of claim 1 , wherein the particle size dispersity index (PSDI) of the crosslinked rubber particles is less than 3.
8. The thermoplastic vulcanizate of claim 1 , wherein the PEDM has a melting point (mp) which is undetectable.
9. The thermoplastic vulcanizate of claim 1 , wherein the PEDM has a heat of fusion (Hf) which is undetectable.
10. 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 70 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, where the PEDM is amorphous;
(c) at least 10 to 30 wt % of a diluent;
(d) 0 to less than 30 wt % of an ethylene-propylene-diene terpolymer (EPDM) containing at least 50 wt % of ethylene-derived units; and
(e) 0.5 to 5.0 wt % of at least one curative;
wherein the percentages of components (a) to (e) are based on the total weight of the mixture.
11. The thermoplastic vulcanizate of claim 10 , wherein the PEDM comprises 5 to 18 wt % of ethylene-derived units.
12. The thermoplastic vulcanizate of claim 10 , 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.
13. The thermoplastic vulcanizate of claim 10 , wherein the PEDM has a viscosity from 10 to 90 MST (5+4) at 230° C.
14. The thermoplastic vulcanizate of claim 10 , in which the amount of PEDM is from 40 to 60 wt % of the mixture.
15. The thermoplastic vulcanizate of claim 10 , wherein the particle size dispersity index (PSDI) of the crosslinked rubber particles is less than 3.
16. The thermoplastic vulcanizate of claim 10 , wherein the PEDM has a melting point (mp) which is undetectable.
17. The thermoplastic vulcanizate of claim 10 , wherein the PEDM has a heat of fusion (Hf) which is undetectable.
18. The thermoplastic vulcanizate of claim 10 , wherein the ethylene-propylene-diene terpolymer (EPDM) contains at least 50 wt % of ethylene-derived units.
19. The composition of claim 1 , wherein, the TPV has an elongation at break of 200% or more.
20. The composition of claim 1 , wherein, the TPV has a break stress of 3 MPa or more.
21. The composition of claim 1 , wherein, the TPV has a tension set at 25% elongation of 7% or less.
22. The composition of claim 1 , wherein, the TPV has a tension set at 50% elongation of 14% or less.
23. The composition of claim 1 , wherein, the TPV has a number average particle size diameter of the rubber particles (PEDM, and EPDM if present) of 800 nm or less.
24. The composition of claim 1 , wherein, the TPV has a dispersity of crosslinked particle size diameter of the rubber particles (PEDM, and EPDM if present) of 1.6 or less.
25. The thermoplastic vulcanizate of claim 1 , wherein the thermoplastic vulcanizate has a Dw/Dn of 7 or less.
26. The thermoplastic vulcanizate of claim 1 , wherein the thermoplastic vulcanizate has a tension set at 50% elongation of 14% or less.
27. 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.
28. The composition of claim 1 , wherein, the TPV has:
1) an elongation at break of 200% or more;
2) a break stress of 3 MPa or more;
3) a tension set at 25% elongation of 7% or less;
4) a tension set at 50% elongation of 14% or less;
5) an number average particle size diameter of the rubber particles (PEDM, and EPDM if present) of 800 nm or less; and
6) a dispersity of crosslinked particle size diameter of the rubber particles (PEDM, and EPDM if present) of 1.6 or less.