Thermoplastic roofing membranes for fully-adhered roofing systems
A thermoplastic roofing membrane comprising a planar-shaped thermoplastic body, said planar body having opposed first and second external planar surfaces, where said first surface includes an ethylene-based olefinic block copolymer and a fatty acid amide, where the amount of fatty acid amide provides the surface with a coefficient of friction (ASTM D 1894) of less than 0.250.
1. A thermoplastic roofing membrane comprising:
a first thermoplastic layer laminated to a second thermoplastic layer with a reinforcing scrim disposed between the first and second thermoplastic layers;
wherein the first thermoplastic layer includes compositionally distinct coextruded layers;
wherein a first coextruded layer of the first thermoplastic layer, which forms a planar surface of the membrane and is exposed to weather upon installation, includes an ethylene-based olefinic block copolymer and a fatty acid amide, where the fatty acid amide is present at from about 0.20 wt % to about 2.0 wt % based upon the total weight of the first coextruded layer of the first thermoplastic layer, where the amount of fatty acid amide provides the planar surface with a coefficient of friction (ASTM D 1894) of less than 0.250;
wherein a second coextruded layer of the first thermoplastic layer, which is adjacent to said reinforcing scrim, includes a fatty acid amide, where the fatty acid amide is present at less than 0.20 wt % based upon the total weight of the second coextruded layer of the first thermoplastic layer;
wherein the second thermoplastic layer includes coextruded layers, wherein the coextruded layers of the second thermoplastic layer are optionally compositionally distinct coextruded layers;
wherein a first coextruded layer of the second thermoplastic layer, which is adjacent to said reinforcing scrim, optionally includes less than 0.20 wt % of a fatty acid amide based upon the total weight of the first coextruded layer of the second thermoplastic layer; and
wherein a second coextruded layer of the second thermoplastic layer, which forms a planar surface of the membrane and is adjacent to a roof when installed, includes an ethylene-based olefinic block copolymer and a fatty acid amide.
2. The roofing membrane of claim 1 , where the fatty acid amide is present within the first coextruded layer of the first thermoplastic layer at from about 0.3 wt % to about 1.8 wt % based upon the total weight of the first coextruded layer of the first thermoplastic layer.
3. The roofing membrane of claim 1 , where the fatty acid amide is present within the first coextruded layer of the first thermoplastic layer at greater than 0.10 pbw per 100 parts by weight of the ethylene-based olefinic block copolymer within the first coextruded layer of the first thermoplastic layer.
4. The roofing membrane of claim 1 , where the fatty acid amide is present within the first coextruded layer of the first thermoplastic layer at from about 0.20 pbw to about 1.0 pbw per 100 parts by weight of the ethylene-based olefinic block copolymer within the first coextruded layer of the first thermoplastic layer.
5. The roofing membrane of claim 1 , where the fatty acid amide is an unsaturated fatty acid amide.
6. The roofing membrane of claim 5 , where the ethylene-based olefinic block copolymers are characterized by a melt temperature less than 130° C.
7. The roofing membrane of claim 1 , where the fatty acid amide is selected from the group consisting of myristoleamide, palmitoleamide, sapienamide, oleamide, elaidamide, vaccenamide, linoleamide, linoelaidamide, alpha-linolenamide, arachidonamide, eicosapentaenoamide, erucamide, and docosahexaenoamide.
8. The roofing membrane of claim 1 , where the fatty acid amide is erucamide.
9. The roofing membrane of claim 1 , where the fatty acid amide includes a double bond having a cis configuration.
10. The roofing membrane of claim 1 , where the fatty acid amide has a molecular weight of greater than 250 g/mol.
11. The roofing membrane of claim 1 , where the fatty acid amide has a molecular weight of from about 300 to about 750 g/mol.
12. The roofing membrane of claim 1 , where the ethylene-based olefinic block copolymers include block copolymers including a first plurality of ethylene-α-olefin blocks having low α-olefin content and a second plurality of ethylene-α-olefin blocks having a high α-olefin content.
13. The roofing membrane of claim 12 , where the α-olefin content of the first plurality is less than 5 wt % with the balance of the polymeric units deriving from ethylene.
14. The roofing membrane of claim 13 , where the first plurality includes greater than 95 wt % polymeric units deriving from ethylene.
15. The roofing membrane of claim 12 , where the α-olefin content of the second plurality is greater than 5 wt % with the balance including ethylene-derived units.
16. The roofing membrane of claim 15 , where the ethylene-based olefinic block copolymers are characterized by a melt temperature of at least 105° C.
17. A method of forming an adhered roof system, the method comprising:
adhering the membrane of claim 1 to a roof substrate so that the first coextruded layer of the first thermoplastic layer is exposed to the environment upon installation.
18. The method of claim 17 , where said method includes folding the membrane onto itself so that a second portion of the membrane is disposed on a first portion of the membrane with the first coextruded layer of the first thermoplastic layer of the first portion contacting the first coextruded layer of the first thermoplastic layer of the second portion.
19. The method of claim 18 , further comprising the step of manipulating the second portion of the membrane to thereby slide the first coextruded layer of the first thermoplastic layer of the second portion across the first coextruded layer of the first thermoplastic layer of the first portion while adhering the membrane to the roof substrate.
20. The method of claim 17 , further comprising the step of adhering a second membrane to the roof surface, where the second membrane is adjacent to the first membrane, and further comprising the step of mating the first and second membranes to each other along a lap edge.