Roofing compositions comprising propylene-based elastomers

1. A roofing membrane comprising a blend composition of:

(a) from about 10 wt % to about 50 wt %, based upon the weight of the blend composition, of a propylene-based elastomer, where the propylene-based elastomer has an ethylene content of from 5 to 30 wt %, based upon the weight of the propylene-based elastomer, wherein the propylene-based elastomer is a reactor blend of a first polymer component and a second polymer component, wherein the first polymer component has an α-olefin content R 1 of from greater than 5 to less than 30 wt % α-olefin, based upon the total weight of the first polymer component, and wherein the second polymer component has an α-olefin content R2 of from greater than 1 to less than 10 wt % α-olefin, based upon the total weight of the second polymer component;

(b) from about 5 wt % to about 40 wt %, based upon the weight of the blend composition, of a thermoplastic resin;

(c) at least one flame retardant; and

(d) at least one ultraviolet stabilizer.

2. The roofing membrane of claim 1 , wherein the blend composition further comprises from about 1 wt % to about 10 wt % of a polyalphaolefin having a kinematic viscosity (KV) at 100° C. of from 3 to 3000 cSt.

3. The roofing membrane of claim 1 , wherein the propylene-based elastomer has an ethylene content of from 16 to 18 wt %, based on the weight of the propylene-based elastomer.

4. The roofing membrane of claim 1 , wherein the propylene-based elastomer has a melting temperature of less than 120° C. and a heat of fusion of less than 75 J/g.

5. A roofing membrane comprising a blend composition of:

(a) from about 10 wt % to about 50 wt % of a propylene-based elastomer, where the propylene-based polymer elastomer has an ethylene content of from 16 to 18 wt %, a melting temperature of less than 120° C., and a heat of fusion of less than 75 J/g;

(b) from about 1 wt % to about 10 wt % of a polyalphaolefin having a kinematic viscosity (KV) at 100° C. of from 3 to 3000 cSt;

(c) from about 5 wt % to about 40 wt % of a thermoplastic resin;

(d) at least one flame retardant; and

(e) at least one ultraviolet stabilizer.

6. The roofing membrane of claim 5 , wherein the propylene-based elastomer is a reactor blend of a first polymer component and a second polymer component, wherein the first polymer component has an α-olefin content R 1 of from greater than 5 to less than 30 wt % α-olefin, where the percentage by weight is based upon the total weight of the first polymer component, and wherein the second polymer component has an α-olefin content R2 of from greater than 1 to less than 10 wt % α-olefin, where the percentage by weight is based upon the total weight of the second polymer component.

7. The roofing membrane of claim 1 , wherein the first polymer component has an α-olefin content R 1 of from 10 to 25 wt % α-olefin.

8. The roofing membrane of claim 1 , wherein the second polymer component has an α-olefin content R2 of from greater than 2 to less than 8 wt % α-olefin.

9. The roofing membrane of claim 1 , wherein the propylene-based elastomer comprises from 1 to 25 wt % of the second polymer component and from 75 to 99 wt % of the first polymer component, based on the weight of the propylene-based elastomer.

10. The roofing membrane of claim 2 , wherein the polyalphaolefin comprises oligomers of α-olefins having from 5 to 24 carbon atoms.

11. The roofing membrane of claim 2 , wherein the polyalphaolefin comprises oligomers of 1-octene, 1-decene, 1-dodecene, and blends thereof.

12. The roofing membrane of claim 2 , wherein the polyalphaolefin has a weight average molecular weight (Mw) of less than 5,000 g/mole.

13. The roofing membrane of claim 2 , wherein the polyalphaolefin has a kinematic viscosity (KV) at 100° C. of from 5 to 100 cSt.

14. The roofing membrane of claim 1 , wherein the thermoplastic resin comprises polypropylene or an impact propylene copolymer.

15. The roofing membrane of claim 1 , wherein the thermoplastic resin comprises a polypropylene that has an MFR (230° C.; 2.16 kg) of greater than 15 g/10 min.

16. The roofing membrane of claim 1 , wherein the thermoplastic resin comprises an impact propylene copolymer that has a MFR (230° C.; 2.16 kg) of less than 30 g/10 min.

17. The roofing membrane of claim 1 , wherein the blend composition has an MFR (230° C.; 2.16 kg) of less than 5 g/10 min.

18. The roofing membrane of claim 1 , wherein the blend composition has at least three of the following properties:

(i) a storage modulus (E′) at −40° C. of less than 2.5×10 10 dynes/cm 2 ;

(ii) a storage modulus (E′) at −30° C. of less than 1.5×10 10 dynes/cm 2 ;

(iii) a storage modulus (E′) at −20° C. of less than 5×10 9 dynes/cm 2 ;

(iv) a storage modulus (E′) at 0° C. of less than 2×10 9 dynes/cm 2 ;

(v) a storage modulus (E′) at 20° C. of less than 1.5×10 9 dynes/cm 2 ;

(vi) a storage modulus (E′) at 40° C. of greater than 6.5×10 8 dynes/cm 2 ;

(vii) a storage modulus (E′) at 60° C. of greater than 4×10 8 dynes/cm 2 ;

(viii) a storage modulus (E′) at 80° C. of greater than 2×10 8 dynes/cm 2 ; or

(ix) a storage modulus (E′) at 100° C. of greater than 1×10 8 dynes/cm 2 .

19. The roofing membrane of claim 1 , where the blend composition comprises from about 30 to 50 wt % of the propylene-based elastomer, from 10-20 wt % of the thermoplastic resin, and from about 1 to about 5 wt % of the polyalphaolefin, based on the weight of the composition.

20. The roofing membrane of claim 1 , where the blend composition comprises from about 10 to about 30 wt % of the flame retardant, based on the weight of the blend composition.

21. The roofing membrane of claim 1 , where the blend composition comprises from about 1 to about 5 wt % of the ultraviolet stabilizer, based on the weight of the blend composition.

22. The roofing membrane of claim 1 , wherein the blend composition further comprises an ethylene-based polymer.

23. The roofing membrane of claim 22 , wherein the ethylene-based polymer is an ethylene-based plastomer having a glass transition temperature (Tg) of from −40 to −50° C.

24. A roofing composition comprising the roofing membrane of claim 1 .