Superhydrophobic coating

Abstract

A coating comprises a polymer binder layer and a plurality of porous protrusions projecting from the surface of the polymer binder layer, the polymer binder layer and the protrusions independently (a) consisting essentially of at least one hydrophobic material; and/or (b) bearing a film that consists essentially of at least one hydrophobic material; wherein the distances between the protrusions are essentially shortest at the polymer binder layer surface.

1 . A coating comprising a polymer binder layer and a plurality of porous protrusions projecting from the surface of said polymer binder layer, said polymer binder layer and said protrusions independently (a) consisting essentially of at least one hydrophobic material; and/or (b) bearing a film that consists essentially of at least one hydrophobic material; wherein the distances between said protrusions are essentially shortest at said polymer binder layer surface.  
     
     
         2 . The coating of  claim 1 , wherein both said polymer binder layer and said protrusions consist essentially of at least one hydrophobic material, and said film is absent.  
     
     
         3 . The coating of  claim 2 , wherein said coating comprises a plurality of particles that are partially embedded in said polymer binder layer so as to partially project from the surface of said polymer binder layer to form said protrusions, said particles being selected from the group consisting of porous particles, particle aggregates, and mixtures thereof.  
     
     
         4 . The coating of  claim 2 , wherein said polymer binder layer consists essentially of at least one hydrophobic material that contains no fluorine.  
     
     
         5 . The coating of  claim 2 , wherein said polymer binder layer consists essentially of at least one hydrophobic material selected from silicone-based adhesives, silicone-based resins, polyurethanes, polyureas, polyepoxides, and mixtures thereof.  
     
     
         6 . The coating of  claim 3 , wherein said particles consist essentially of at least one hydrophobic material that contains no fluorine.  
     
     
         7 . The coating of  claim 3 , wherein said particles consist essentially of at least one hydrophobic material selected from polyethylene, polypropylene, polystyrene, and mixtures thereof.  
     
     
         8 . The coating of  claim 3 , wherein said particles are selected from substantially spherical particles, conical particles, pyramidal particles, truncated conical particles, truncated pyramidal particles, and mixtures thereof.  
     
     
         9 . The coating of  claim 8 , wherein said particles are substantially spherical particles.  
     
     
         10 . The coating of  claim 9 , wherein said particles have at least 25% and less than 75% of their average particle size embedded in said polymer binder layer.  
     
     
         11 . The coating of  claim 3 , wherein said particles are microparticles.  
     
     
         12 . The coating of  claim 1 , wherein neither said polymer binder layer nor said protrusions consist essentially of at least one hydrophobic material, and said film is present.  
     
     
         13 . The coating of  claim 12 , wherein said coating comprises a plurality of particles that are partially embedded in said polymer binder layer so as to partially project from the surface of said polymer binder layer to form said protrusions, said particles being selected from the group consisting of porous particles, particle aggregates, and mixtures thereof.  
     
     
         14 . The coating of  claim 12 , wherein the polymer binder of said polymer binder layer comprises a material selected from silicone-based, urethane-based, acrylic-based, olefin-based, and rubber-based resins; silicone-based, urethane-based, acrylic-based, olefin-based, and rubber-based adhesives; and mixtures thereof.  
     
     
         15 . The coating of  claim 13 , wherein said particles comprise a material selected from acrylic- and methacrylic-based resins, metals, ceramics, and mixtures thereof.  
     
     
         16 . The coating of  claim 13 , wherein said particles are selected from substantially spherical particles, conical particles, pyramidal particles, truncated conical particles, truncated pyramidal particles, and mixtures thereof.  
     
     
         17 . The coating of  claim 16 , wherein said particles are substantially spherical particles.  
     
     
         18 . The coating of  claim 17 , wherein said particles have at least 25% and less than 75% of their average particle size embedded in said polymer binder layer.  
     
     
         19 . The coating of  claim 13 , wherein said particles are microparticles.  
     
     
         20 . The coating of  claim 12 , wherein said hydrophobic material of said film contains no fluorine.  
     
     
         21 . The coating of  claim 12 , wherein said hydrophobic material of said film is selected from organic silicone derivatives and mixtures thereof.  
     
     
         22 . The coating of  claim 13 , wherein the thickness of said film is 0.1-30 percent of the size of said particles.  
     
     
         23 . The coating of  claim 1 , wherein said coating exhibits a rolling angle, for a deposited 0.02 mL water droplet, of 10° or less.  
     
     
         24 . The coating of  claim 1 , wherein said coating exhibits a rolling angle, for a deposited 0.02 mL water droplet, of 25° or less after immersion in water for a period of one hour.  
     
     
         25 . A coating comprising a polymer binder layer and a plurality of porous polystyrene microparticles partially embedded in and partially projecting from the surface of said polymer binder layer to form protrusions, said polymer binder layer consisting essentially of at least one hydrophobic material selected from silicone-based adhesives, silicone-based resins, polyurethanes, and mixtures thereof; wherein the distances between said protrusions are essentially shortest at said polymer binder layer surface.  
     
     
         26 . A coated sheet comprising a base film and the coating of  claim 1  on at least a portion of at least one surface of said base film.  
     
     
         27 . A coated sheet comprising a base film and the coating of  claim 25  on at least a portion of at least one surface of said base film.