Roofing underlayment
A breathable synthetic roofing underlayment having a hydrophobic nonwoven layer on top to deflect water, a liquid water-resistant and vapour-permeable membrane layer in the middle, and a bottom nonwoven layer which is hydrophilic and has rapid and high liquid water absorbency. This accelerates the movement of liquid water from a roofing deck into the nonwoven bottom layer and increases the rate of transfer of water through the underlayment. The bottom layer comprises a carrier resin and a hydrophilic agent, which may be a polyamide such as polycaprolactam (Nylon 6) or poly(hexamethylene adipamide), a polysorbate or other composition. The underlayment is especially useful for application to wet roofing decks.
1. A roofing underlayment comprising:
(a) a first layer that is nonwoven, vapour-permeable, and has a hydrophobic surface, comprising a polymer or mixture of polymers, the first layer being an outer layer configured to contact an exterior roofing material;
(b) a second layer that is water vapour-permeable and a liquid water barrier, comprising a carrier resin and a breathability agent, and
(c) a third layer configured to contact a roofing deck, the third layer being nonwoven, hydrophilic and liquid water absorptive,
wherein the second layer between the third layer and the first layer;
wherein the third layer comprises a carrier resin and a hydrophilic agent;
wherein the carrier resin comprises a polyolefin;
wherein the hydrophilic agent comprises between 2 and 10 weight % of the third layer;
wherein the roofing underlayment has a water absorbency of at least 9 g/m 2 in 10 minutes; and
wherein the roofing underlayment has a breathability of at least 10 perms when measured in accordance with standard test method ASTM E96; and
wherein the roofing underlayment has a surface wettability on its bottom surface such that a contact angle between the bottom surface and water decreases to 0° in less than 6 seconds, measured in accordance with standard test method ASTM D724.
2. A roofing underlayment according to claim 1 , wherein the water absorbency is at least 20 g/m 2 in 10 minutes.
3. A roofing underlayment according to claim 1 , wherein the water absorbency is least 40 g/m 2 in 10 minutes.
4. A roofing underlayment according to claim 1 , wherein surface wettability is such that the contact angle decreases to 0° in less than 2 seconds, measured in accordance with standard test method ASTM D724.
5. A roofing underlayment according to claim 1 , wherein the breathability is at least 70 perms.
6. A roofing underlayment according to claim 1 , wherein the hydrophilic agent comprises a polyamide.
7. A roofing underlayment according to claim 6 , wherein the polyamide comprises polycaprolactam (Nylon 6).
8. A roofing underlayment according to claim 6 , wherein the polyamide comprises poly(hexamethylene adipamide).
9. A roofing underlayment according to claim 1 , wherein the hydrophilic agent comprises a polysorbate.
10. A roofing underlayment according to claim 9 , wherein the polysorbate comprises polyoxyethylene (20) sorbitan monooleate (polysorbate 80).
11. A roofing underlayment according to claim 9 , wherein the polysorbate comprises polyoxyethylene (20) sorbitan monolaurate (polysorbate 20).
12. A roofing underlayment according to claim 1 , wherein the hydrophilic agent comprises a mixture of polyethylene, polypropylene, wax and polyacrylamide.
13. A roofing underlayment according to claim 1 , wherein the hydrophilic agent comprises silica-alumina.
14. A roofing underlayment according to claim 1 , wherein the hydrophilic agent comprises at least 4 weight % of the third layer.
15. A roofing underlayment according to claim 1 , wherein the carrier resin of the third layer comprises a polyolefin.
16. A roofing underlayment according to claim 8 , wherein the polyolefin comprises polyethylene, polypropylene, or both.
17. A roofing underlayment according to claim 1 , wherein the third layer has a weight of more than 20 g/m 3 .
18. A roofing underlayment according to claim 1 , wherein the carrier resin comprises from 90 to 98 weight percent of the third layer.
19. A roofing underlayment according to claim 1 , wherein the polymer of the first layer comprises a polyolefin.
20. A roofing underlayment according to claim 19 , wherein the polyolefin of the first layer comprises polyethylene, polypropylene or both.
21. A roofing underlayment according to claim 1 , wherein the first layer comprises from 35% to 40% of the underlayment weight.
22. A roofing underlayment according to claim 1 , wherein the breathability agent of the second layer comprises polyether block amide.
23. A roofing underlayment according to claim 1 , wherein the breathability agent of the second layer is a polyolefin with calcium carbonate filler.
24. A roofing underlayment according to claim 1 , wherein the carrier resin of the second layer comprises a polyolefin.
25. A roofing underlayment according to claim 24 , wherein the polyolefin of the second layer comprises polyethylene, polypropylene, or both.
26. A roofing underlayment according to claim 1 , wherein the carrier resin of the second layer comprises from 20 to 70 weight % of the second layer.
27. A roofing underlayment according to claim 1 , wherein the breathability agent of the second layer comprises from 30 to 75 weight % of the second layer.
28. A roofing underlayment according to claim 1 , wherein the second layer comprises from 10 to 15% of the underlayment weight.
29. A roofing underlayment according to claim 1 , wherein the second layer bonds the first layer to the third layer.
30. A roofing underlayment according to claim 1 , wherein the underlayment has a thickness in the range of 10-30 mils.
31. A roofing underlayment according to claim 1 , wherein the underlayment has a weight in the range of 100-300 g per square meter.
32. A roofing system comprising:
a roof deck;
a roofing material; and
a roofing underlayment comprising:
(a) a nonwoven first layer comprising at least one polymer, the first layer in contact with the roofing material;
(b) a second layer comprising a carrier resin and a breathability agent, the second layer in contact with the first layer; and
(c) a nonwoven third layer comprising a carrier resin and a hydrophilic agent, the third layer in contact with the second layer and the roof deck;
wherein the hydrophilic agent comprises between 2 and 10 weight % of the third layer;
wherein the roofing underlayment has a water absorbency of at least 9 g/m 2 in 10 minutes; and
wherein the roofing underlayment has a breathability of at least 10 perms when measured in accordance with standard test method ASTM E96; and
wherein the roofing underlayment has a surface wettability on its bottom surface such that a contact angle between the bottom surface and water decreases to 0° in less than six seconds, measured in accordance with standard test method ASTM D724.
33. A roofing system according to claim 32 , wherein the at least one polymer of the first layer comprises a polyolefin that comprises a thermoplastic resin.
34. A roofing system according to claim 32 , wherein the carrier resin of the third layer comprises polyethylene or polypropylene.