ROOFING MEMBRANES, COMPOSITIONS, AND METHODS OF MAKING THE SAME
A roofing membrane and a method of making the same is provided. The roofing membrane includes a top layer having a flame retardant and a first silane-crosslinked polyolefin elastomer with a density less than 0.90 g/cm 3 ; a scrim layer; and a bottom layer having a flame retardant and a second silane-crosslinked polyolefin elastomer with a density less than 0.90 g/cm 3 . The top and bottom layers of the roofing membrane both exhibit a compression set of from about 5.0% to about 35.0%, as measured according to ASTM D 395 (22 hrs @ 70° C.).
1 . A roofing membrane comprising:
a top layer comprising a flame retardant and a first silane-crosslinked polyolefin elastomer having a density less than 0.90 g/cm 3 ;
a scrim layer; and
a bottom layer comprising a flame retardant and a second silane-crosslinked polyolefin elastomer having a density less than 0.90 g/cm 3 ,
wherein the top and bottom layers of the roofing membrane both exhibit a compression set of from about 5.0% to about 35.0%, as measured according to ASTM D 395 (22 hrs @ 70° C.).
2 . The roofing membrane of claim 1 , wherein the compression set is from about 10% to about 30%.
3 . The roofing membrane of claim 1 , wherein the first and second silane-crosslinked polyolefin elastomers both exhibit a crystallinity of from about 5% to about 25%.
4 . The roofing membrane of claim 1 , wherein the first and second silane-crosslinked polyolefin elastomers have a glass transition temperature of from about −75° C. to about −25° C.
5 . The roofing membrane of claim 1 , wherein the first and second silane-crosslinked polyolefin elastomers each comprise a first polyolefin having a density less than 0.86 g/cm 3 , a second polyolefin, a silane crosslinker, a grafting initiator, and a condensation catalyst.
6 . The roofing membrane of claim 1 , wherein the density is from about 0.85 g/cm 3 to about 0.89 g/cm 3 .
7 . The roofing membrane of claim 1 , wherein the roofing membrane exhibits a weathering color difference of from about 0.25 ΔE to about 2.0 ΔE, as measured according to ASTM D2244.
8 . The roofing membrane of claim 1 , wherein the first silane-crosslinked polyolefin elastomer and the second silane-crosslinked polyolefin elastomer are chemically distinct from each other.
9 . A method of making a roofing membrane, the method comprising:
extruding a first silane-crosslinkable polyolefin elastomer to form a top layer;
extruding a second silane-crosslinkable polyolefin elastomer to form a bottom layer;
calendaring a scrim layer between the top and the bottom layers to form an uncured roofing membrane element; and
crosslinking the silane-crosslinkable polyolefin elastomers of the top and the bottom layers in the uncured roofing membrane element at a curing temperature and a curing humidity to form the roofing membrane,
wherein the top and bottom layers of the roofing membrane both exhibit a compression set of from about 5.0% to about 35.0%, as measured according to ASTM D 395 (22 hrs @ 70° C.).
10 . The method of claim 9 , wherein the first silane-crosslinkable polyolefin elastomer and the second silane-crosslinkable polyolefin elastomer are chemically distinct from each other.
11 . The method of claim 9 , wherein the curing temperature is an ambient temperature.
12 . The method of claim 9 , wherein the curing humidity is an ambient humidity.
13 . The method of claim 9 , wherein the first and second silane-crosslinkable polyolefin elastomers each comprise a first polyolefin having a density less than 0.86 g/cm 3 , a second polyolefin, a silane crosslinker, a grafting initiator, and a condensation catalyst.
14 . The method of claim 9 , wherein the roofing membrane exhibits a weathering color difference of from about 0.25 ΔE to about 2.0 ΔE, as measured according to ASTM D2244.
15 . The method of claim 9 , wherein the roofing membrane exhibits a flame retardance rating of classification D as measured in accordance with the EN ISO 11925-2 surface exposure test.
16 . A method of making a high-load flame retardant thermoplastic polyolefin (TPO) roofing membrane, the method comprising:
adding a silane-grafted polyolefin elastomer, a flame retardant, and a condensation catalyst to a reactive single screw extruder to produce a silane-crosslinkable polyolefin elastomer;
calendaring the silane-crosslinkable polyolefin elastomer to form a top layer and a bottom layer;
calendaring a scrim layer between the top and the bottom layers to form an uncured roofing membrane element; and
crosslinking the silane-crosslinkable polyolefin elastomers of the top and the bottom layers in the uncured roofing membrane element at an ambient temperature and an ambient humidity to form the thermoplastic polyolefin (TPO) roofing membrane,
wherein the top and bottom layers of the thermoplastic polyolefin (TPO) roofing membrane both exhibit a compression set of from about 5.0% to about 35.0%, as measured according to ASTM D 395 (22 hrs @ 70° C.).
17 . The method of claim 16 , wherein the top and bottom layers are chemically equivalent to each other.
18 . The method of claim 16 , wherein the single ply roofing membrane exhibits a flame retardance rating of classification D as measured in accordance with the EN ISO 11925-2 surface exposure test.
19 . The method of claim 16 , wherein the silane-grafted polyolefin elastomer comprises a first polyolefin having a density less than 0.86 g/cm 3 , a second polyolefin, a silane crosslinker, a grafting initiator.
20 . The method of claim 16 , wherein the high-load flame retardant thermoplastic polyolefin (TPO) roofing membrane exhibits a weathering color difference of from about 0.25 ΔE to about 2.0 ΔE, as measured according to ASTM D2244.