Roofing underlayment

Abstract

A roofing underlayment that resists water ingress around fasteners that are used to secure the underlayment to a substrate, such as a roof deck, is provided. The roofing underlayment includes a base layer, a coating layer applied to the base layer, and a water-swellable composition. An upper surface of the roofing underlayment may have a water contact angle of at least 120°.

What is claimed is: 
     
         1 . A roofing underlayment comprising:
 a base layer; and   a coating layer applied to the base layer,   wherein at least one of the base layer and the coating layer includes a water-swellable composition.   
     
     
         2 . A roofing underlayment comprising:
 a baser layer;   a coating layer applied to the base layer; and   a layer comprising a water-swellable composition.   
     
     
         3 . The roofing underlayment according to  claim 2 , wherein the layer comprising the water-swellable composition is applied to the base layer. 
     
     
         4 . The roofing underlayment according to  claim 2 , wherein the layer comprising the water-swellable composition is applied to the coating layer. 
     
     
         5 . The roofing underlayment according to  claim 1 , wherein the base layer is selected from a woven material, a nonwoven material, and a film material. 
     
     
         6 . The roofing underlayment according to  claim 1 , wherein the base layer comprises at least one of a polyolefin, a polyester, a polystyrene, a polyamide, an ethylene-acrylic copolymer, a polyvinyl chloride, a polyvinylidene chloride, and an ionomer resin. 
     
     
         7 . The roofing underlayment according to  claim 1 , wherein the coating layer is a film material. 
     
     
         8 . The roofing underlayment according to  claim 1 , wherein the coating layer comprises at least one of a polyolefin, a polyester, a polystyrene, a polyamide, an ethylene-acrylic copolymer, a polyvinyl chloride, a polyvinylidene chloride, and an ionomer resin. 
     
     
         9 . The roofing underlayment according to  claim 1 , wherein the water-swellable composition comprises at least one of a bentonite, a polyacrylic acid or a salt thereof, a polyethylene oxide, a polyacrylamide, a crosslinked polyacrylate, a crosslinked polyacrylamide, a polyacrylamide copolymer, an ethylene maleic anhydride copolymer, a cross-linked carboxymethylcellulose, a polyvinyl alcohol copolymer, a starch grafted copolymer of polyacrylonitrile, a hydrolyzed cellulose-polyacrylonitrile, a polyurethane, and a hydrophilic swelling rubber. 
     
     
         10 . The roofing underlayment according to  claims 1 , wherein an upper surface of the roofing underlayment has a water contact angle of 120° to 180°. 
     
     
         11 . A roofing underlayment comprising:
 a base layer; and   a coating layer applied to the base layer;   wherein an upper surface of the roofing underlayment has a water contact angle of at least 120°.   
     
     
         12 . The roofing underlayment according to  claim 11 , wherein the upper surface of the roofing underlayment comprises a surfactant layer comprising at least one surfactant selected from a silane, a stearic acid compound, and a fluoropolymer. 
     
     
         13 . The roofing underlayment according to  claim 11 , wherein the upper surface of the roofing underlayment comprises at least one of nanostructures and microstructures. 
     
     
         14 . The roofing underlayment according to  claim 13 , wherein the nanostructures are formed by at least one of inorganic nanoparticles, carbon nanoparticles, and etching the upper surface of the roofing underlayment; and
 wherein the microstructures are formed by at least one of inorganic microparticles, carbon microparticles, and etching the upper surface of the roofing underlayment.   
     
     
         15 . The roofing underlayment according to  claim 13 , wherein the upper surface of the roofing underlayment comprises nanostructures formed by inorganic nanoparticles, wherein the inorganic nanoparticles comprise at least one of silica, alumina, titania, zirconia, ceria, zinc oxide, iron oxide, vanadia, antimony oxide, and tin oxide. 
     
     
         16 . The roofing underlayment according to  claim 11 , wherein the base layer is selected from a woven material, a nonwoven material, and a film material. 
     
     
         17 . The roofing underlayment according to  claim 11 , wherein the base layer comprises at least one of a polyolefin, a polyester, a polystyrene, a polyamide, an ethylene-acrylic copolymer, a polyvinyl chloride, a polyvinylidene chloride, and an ionomer resin. 
     
     
         18 . The roofing underlayment according to  claim 11 , wherein the coating layer is a film material. 
     
     
         19 . The roofing underlayment according to  claim 11 , wherein the coating layer comprises at least one of a polyolefin, a polyester, a polystyrene, a polyamide, an ethylene-acrylic copolymer, a polyvinyl chloride, a polyvinylidene chloride, and an ionomer resin. 
     
     
         20 . The roofing underlayment according to  claim 11 , wherein the upper surface of the roofing underlayment has a water contact angle of 120° to 180°.