Method for forming polymer modified asphalt
A superhydrophobic asphalt and a method of its preparation. The superhydrophobic asphalt contains an asphalt layer containing a polymer modified asphalt, preferably a radial SBS modified asphalt, and a polypropylene layer. The polypropylene layer comprises granules of polypropylene thermally fused to the asphalt layer. The superhydrophobic asphalt has a water contact angle of 145 to 170°, above the classification threshold for superhydrophobicity. The method of preparing the superhydrophobic asphalt involves distributing polypropylene granules over the surface of a polymer modified asphalt and curing below the melting temperature of the polypropylene. The asphalt may find use in waterproofing applications such as roofing.
1 . A method of modifying asphalt to form a superhydrophobic asphalt, comprising:
blending styrene-butadiene-styrene with a non-modified asphalt to form a polymer modified asphalt,
applying a layer of polypropylene granules to a surface of the polymer modified asphalt,
wherein the polymer modified asphalt has a softening point of 80 to 95° C., a viscosity at 135° C. of 1575 to 1650 cP, a ductility at 25° C. of 11.5 to 17.5 cm, a flash point of 300 to 360° C., and a performance grade of 76-10,
wherein the polypropylene granules are substantially free of fluoropolymers, have a maximum particle size of 250 μm, a minimum particle size of 100 μm, and are present on the uncured coated asphalt in an amount of 185 to 275 g polypropylene granules per m 2 of surface of the polymer modified asphalt,
to form an uncured coated asphalt; and
curing the uncured coated asphalt
at 75 to 150° C. and at a temperature less than the melting point of said polypropylene granules, for 15 to 90 minutes,
to form the superhydrophobic asphalt, wherein:
the superhydrophobic asphalt comprises a polypropylene layer disposed upon a polymer modified asphalt layer, has a water contact angle of 145 to 170°; and
wherein the polypropylene layer is present in an amount of 50 to 125 g per m 2 of polymer modified asphalt layer, has a R a surface roughness of 10 to 50 μm, and the polypropylene particles are mostly attached to the asphalt surface perpendicularly, as opposed to sideways, and
wherein the superhydrophobic asphalt has a work of adhesion of 1 to 15 mN/m.
2 . The method of claim 1 , wherein the styrene-butadiene-styrene is a radial styrene-butadiene-styrene and is present in an amount of 0.5 to 10 wt % based on a total weight of the polymer modified asphalt.
3 . The method of claim 1 , wherein the polymer modified asphalt has a softening point of 84 to 88° C., a viscosity at 135° C. of 1605 to 1620 cP, a ductility at 25° C. of 13.75 to 15.25 cm, a flash point of 320 to 340° C., and a performance grade of 76-10.
4 . The method of claim 1 , wherein the polypropylene granules are present on the uncured coated asphalt in an amount of 215 to 245 g polypropylene granules per m 2 of surface of the polymer modified asphalt.
5 . The method of claim 1 , wherein the polypropylene granules have a minimum particle size of 149 μm.
6 . The method of claim 1 , wherein the curing is performed for 40 to 55 minutes.
7 . The method of claim 1 , wherein the polypropylene layer is present in an amount of 80 to 90 g per m 2 of polymer modified asphalt layer.
8 . The method of claim 1 , wherein the superhydrophobic asphalt has a work of adhesion of 6.50-9.60 mN/m.
9 . The method of claim 1 , wherein the polypropylene layer has a R a surface roughness of 20 to 40 μm.