Method of Producing Roofing Shingles With Enhanced Granule Adhesion

Abstract

The retention of roofing granules on bituminous roofing products is enhanced by providing an adherent material in the interstices between the exterior surface of the roofing granules and the exposed upper surface of the base sheet.

1 - 20 . (canceled) 
     
     
         21 . A bituminous roofing product, comprising:
 a bituminous base sheet having an upper surface;   roofing granules partially embedded in the upper surface of the bituminous base sheet, the roofing granules extending a height above the upper surface of the base sheet, the base sheet having an exposed upper surface extending between the partially embedded roofing granules; and   a continuous thermoplastic polymer coating disposed between the exterior surfaces of the partially embedded roofing granules on the exposed upper surface of the base sheet, the coating disposed on the exposed upper surface of the base sheet not extending to the height of the roofing granules above the base sheet, the continuous thermoplastic polymer coating securing the roofing granules to the base sheet while leaving the upper surfaces of the granules exposed, the adherent polymer coating lacking a solar-reflective additive.   
     
     
         22 . The bituminous roofing product according to claim  1 , wherein the roofing granules are mineral particles, the mineral particles ranging from about #8 to about #50 US mesh. 
     
     
         23 . The bituminous roofing product according to claim  1 , wherein the thermoplastic polymer coating is formed from a polymer selected from the group consisting of polyethylene, polyolefins, acid-containing polyolefins, ethylene vinyl acetate, acrylics, ethylene-alkyl acrylate copolymers, polyvinylbutyral, polyurethane and mixtures thereof. 
     
     
         24 . The bituminous roofing product according to  claim 23 , wherein the thermoplastic polymer of the thermoplastic polymer coating makes up from about 0.01 percent to 1.0 percent by weight of the total weight of the bituminous roofing product. 
     
     
         25 . The bituminous roofing product according to  claim 23  wherein the thermoplastic polymer coating comprises at least one additive selected from the group consisting of tackifiers, wetting agents, thermal stabilizers, and algaecides. 
     
     
         26 . The bituminous roofing product according to  claim 21  wherein the coating is translucent or transparent. 
     
     
         27 . The bituminous roofing product according to  claim 21 , wherein the ratio of the surface area of the exposed upper surface of the bituminous base sheet that is not covered by the thermoplastic polymer coating to the total area of the exposed upper surface of the bituminous base sheet extending between the partially embedded roofing granules less than about 0.10. 
     
     
         28 . The bituminous roofing product according to  claim 21 , wherein the ratio of the surface area of the exposed upper surface of the bituminous base sheet that is not covered by the thermoplastic polymer coating to the total area of the exposed upper surface of the bituminous base sheet extending between the partially embedded roofing granules less than about 0.05. 
     
     
         29 . The bituminous roofing product of  claim 21 , wherein the thermoplastic polymer has a fusion temperature from about 93° C. to about 149° C. 
     
     
         30 . The bituminous roofing product of  claim 21 , wherein the thermoplastic polymer coating consists of the thermoplastic polymer; or consists of the thermoplastic polymer and one or more of tackifiers, wetting agents, thermal stabilizers, and UV stabilizers.