Propylene-based elastomers for roofing compositions and methods for preparing the same
Provided herein are membranes including a blend of a propylene-based elastomer and an ethylene copolymer, a thermoplastic resin, a flame retardant, and an ultraviolet stabilizer.
1. A reactor blend composition comprising:
(a) from about 70 wt % to about 95 wt % of a propylene-based elastomer,
wherein the propylene-based elastomer has an ethylene content of about 15 wt % to about 30 wt % based upon the weight of the propylene-based elastomer, and
(b) from about 5 wt % to about 30 wt % of an ethylene copolymer, where the ethylene-copolymer has an ethylene content of greater than or equal to about 70 wt % based upon the weight of the ethylene copolymer.
2. The composition of claim 1 , wherein the propylene-based elastomer has an ethylene content of about 16 wt % to about 18 wt %, a melting temperature of less than 120° C., and a heat of fusion less than 75 J/g.
3. A membrane composition comprising:
(a) from about 20 wt % to about 50 wt % of a polymer blend, comprising:
(i) from about 70 wt % to about 95 wt % of a propylene-based elastomer, wherein the propylene-based elastomer has an ethylene content of about 15 wt % to about 30 wt % based upon the weight of the propylene-based elastomer, and (ii) from about 5 wt % to about 30 wt % of an ethylene copolymer, where the ethylene-copolymer has an ethylene content of greater than or equal to about 70 wt % based upon the weight of the ethylene copolymer;
(b) from about 5 wt % to about 30 wt % of a thermoplastic resin based on the composition;
(c) at least one flame retardant; and
(d) at least one ultraviolet stabilizer.
4. The membrane of claim 3 , wherein the polymer blend is a reactor blend of the propylene-based elastomer and the ethylene copolymer.
5. The membrane of claim 3 , wherein the polymer blend is a physical blend of the propylene-based elastomer and the ethylene copolymer.
6. The membrane of claim 3 , wherein the thermoplastic resin is a propylene homopolymer.
7. The membrane of claim 6 , wherein the thermoplastic resin has a melt flow rate (230° C.; 2.16 kg) of greater than about 25 g/10 min.
8. The membrane of claim 3 , wherein the thermoplastic resin is a propylene impact copolymer.
9. The membrane of claim 8 , wherein the thermoplastic resin has a melt flow rate (230° C.; 2.16 kg) of less than about 5 g/10 min.
10. The membrane of claim 3 , wherein the propylene-based elastomer has an ethylene content of from 16 to 18 wt % based upon the weight of the propylene-based elastomer.
11. The membrane of claim 3 , wherein the thermoplastic resin is present in the composition in the amount of about 20 wt % to about 30 wt %.
12. The membrane of claim 3 , 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.
13. The membrane of claim 3 , wherein 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.
14. The membrane of claim 3 , 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 ethylene 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 ethylene content R 2 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.
15. The membrane of claim 14 , wherein the first polymer component has an α-olefin content R 1 of from 10 to 25 wt % α-olefin and the second polymer component has an α-olefin content R 2 of from greater than 2 to less than 8 wt % α-olefin.
16. The membrane of claim 3 , 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 .
17. The membrane of claim 3 , where the blend composition comprises from about 10 to about 30 wt % of the flame retardant, based on the weight of the blend composition.
18. The membrane of claim 3 , where the blend composition comprises from about 1 to about 20 wt % of the ultraviolet stabilizer, based on the weight of the blend composition.
19. A roofing composition comprising the membrane of claim 3 .