Roofing shingles with enhanced granule adhesion and method for producing same

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 . A process for enhancing the retention of roofing granules on bituminous roofing products, the process comprising:
 (a) embedding roofing granules having an exterior surface in a bituminous base sheet having an upper surface, the roofing granules being embedded in the upper surface of the bituminous base sheet, the base sheet having an exposed upper surface extending between the partially embedded roofing granules;   (b) providing an adherent material between the exterior surface of the roofing granules and the exposed upper surface of the base sheet;   (c) processing the adherent material to secure the roofing granules to the base sheet.   
   
   
       2 . A process according to  claim 1  wherein the roofing granules are mineral particles. 
   
   
       3 . A process according to  claim 2  wherein the mineral particles range from about #8 to #50 US mesh. 
   
   
       4 . A process according to  claim 1  wherein the adherent material comprises a polymeric powder. 
   
   
       5 . A process according to  claim 4  wherein the polymeric powder comprises 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. 
   
   
       6 . (canceled) 
   
   
       7 . A process according to  claim 4  wherein the polymeric powder has a particle size of from about 1 micrometer to 400 micrometers. 
   
   
       8 . (canceled) 
   
   
       9 . A process according to  claim 4  wherein the adherent material further comprises at least one additive selected from the group consisting of tackifiers, wetting agents, thermal stabilizers, UV stabilizers, algaecides, and solar reflection agents. 
   
   
       10 . A process according to  claim 4  wherein the adherent material is provided between the exterior surface of the roofing granules and the upper surface of the base sheet by:
 (a) depositing an adherent powder mixture on the upper surface of bituminous base sheet in which roofing granules are embedded; and   (b) subjecting the base sheet to mechanical oscillation to assist in lodging the adherent powder mixture on the exterior surface of the granules sheet and on the upper surface of the base sheet.   
   
   
       11 . (canceled) 
   
   
       12 . A process according to  claim 10  wherein processing the adherent material to secure the roofing granules to the base sheet comprises melting the polymeric powder mixture to form a coating. 
   
   
       13 . A process according to  claim 10  wherein the polymeric powder mixture is processed to form a coating using energy provided by a source selected from the group consisting of heat lamp, open flame, UV radiation, microwave radiation, and electron beam radiation and combinations thereof. 
   
   
       14 . A process according to  claim 12  wherein the coating is translucent or transparent. 
   
   
       15 . A process according to  claim 1  wherein the adherent material comprises a fluid adhesive, and an adherent material is provided between the exterior surface of the roofing granules and the upper surface of the base sheet by applying the fluid adhesive to the upper surface of the base sheet in which the roofing granules are embedded to form a coating, and wherein processing the adherent material to secure the roofing granules to the base sheet comprises curing the coating of the fluid adhesive. 
   
   
       16 . (canceled) 
   
   
       17 . A process according to  claim 15  wherein the fluid adhesive is applied to the upper surface of the base sheet in which the roofing granules are embedded to form a discontinuous coating. 
   
   
       18 . A process according to  claim 15  wherein the fluid adhesive comprises a polymer selected from the group consisting of polyethylene, polyolefins, acid-containing polyolefins, ethylene vinyl acetate, ethylene-alkyl acrylate copolymers, polyvinylbutyral, acrylates, polyurethanes and mixtures thereof. 
   
   
       19 . A process according to  claim 15  wherein the fluid adhesive is applied by a method selected from the group consisting of spraying, rolling, curtain coating, extrusion coating and brushing. 
   
   
       20 . A process according to  claim 15  wherein the fluid adhesive has a solids content of from about 10 percent to 90 percent by weight. 
   
   
       21 . (canceled) 
   
   
       22 . A process according to  claim 15  wherein the cured coating is translucent or transparent. 
   
   
       23 . A process according to  claim 15  wherein the coating is cured by a curing method selected from the group consisting of thermal means, chemical means and radiation means. 
   
   
       24 . A process according to  claim 15  wherein the thickness of the cured coating is from 12 micrometers to 50 micrometers. 
   
   
       25 . (canceled) 
   
   
       26 . A process according to  claim 15  wherein the adherent material further comprises at least one additive selected from the group consisting of tackifiers, wetting agents, thermal stabilizers, UV stabilizers, algaecides, and solar reflection agents. 
   
   
       27 . A process according to  claim 1  wherein the adherent material comprises a polymeric web, and the adherent material is provided between the exterior surface of the roofing granules and the upper surface of the base sheet by applying the polymeric web to the upper surface of the base sheet in which the roofing granules are embedded, and wherein processing the adherent material to secure the roofing granules to the base sheet comprises heating the polymeric web to cause the polymeric material to flow and form a coating covering at least a portion of the exterior surface of the roofing granules and at least a portion of the upper surface of the base sheet. 
   
   
       28 . (canceled) 
   
   
       29 . (canceled) 
   
   
       30 . A process according to  claim 27  wherein the polymeric web is a web material comprising a polymer selected from the group consisting of polyethylene, polyolefins, acid-containing polyolefins, ethylene vinyl acetate, ethylene-alkyl acrylate copolymers, polyvinylbutyral, acrylics, polyurethane, and mixtures thereof. 
   
   
       31 . (canceled) 
   
   
       32 . (canceled) 
   
   
       33 . A process according to  claim 32  wherein the polymeric web is in a form selected from the group consisting of continuous film, woven mat, nonwoven mat, mesh, netting, and scrim. 
   
   
       34 . A process according to  claim 27  wherein the polymer web is heated by application of an external heat source. 
   
   
       35 . An improved bituminous roofing product having enhanced retention of roofing granules, the roofing product comprising:
 (a) a bituminous base sheet having an upper surface;   (b) roofing granules partially embedded in the upper surface of the bituminous base sheet and having an exterior surface protruding from the base sheet; the base sheet having an exposed upper surface extending between the partially embedded roofing granules and an interior surface embedded within and in contact with bituminous base sheet, and   (c) an adherent material extending between the exterior surface of the roofing granules and the exposed upper surface of the base sheet.   
   
   
       36 . An improved bituminous roofing product according to  claim 35  wherein the adherent material comprises a polymer selected from the group consisting of polyethylene, polyolefins, acid-containing polyolefins, ethylene vinyl acetate, ethylene-alkyl acrylate copolymers, polyvinylbutyral, acrylics, polyurethane and mixtures thereof and forms a coating at least partially covering the exterior surface of the roofing granules and the exposed upper surface of the base sheet. 
   
   
       37 . An improved roofing product according to  claim 35  wherein the adherent material further comprises at least one additive selected from the group consisting of tackifiers, wetting agents, thermal stabilizers, UV stabilizers, algaecides, and solar reflection agents. 
   
   
       38 . An improved roofing product according to  claim 36  wherein the coating of the adherent material is discontinuous. 
   
   
       39 . An improved roofing product according to  claim 38  wherein the coating of the adherent material forms net-like, physically porous layer. 
   
   
       40 . A process for enhancing the retention of roofing granules on bituminous roofing products, the bituminous roofing product comprising roofing granules having an exterior surface and a bituminous base sheet having an upper surface, the roofing granules being embedded in the upper surface of the bituminous base sheet, the base sheet having an exposed upper surface extending between the partially embedded roofing granules, the process comprising:
 (a) providing an adherent material between the exterior surface of the roofing granules and the exposed upper surface of the base sheet; and   (b) processing the adherent material to secure the roofing granules to the base sheet.   
   
   
       41 . A process according to  claim 40  wherein the adherent material comprises a fluid adhesive, and an adherent material is provided between the exterior surface of the roofing granules and the upper surface of the base sheet by applying the fluid adhesive to the upper surface of the base sheet in which the roofing granules are embedded to form a coating, and wherein processing the adherent material to secure the roofing granules to the base sheet comprises curing the coating of the fluid adhesive. 
   
   
       42 . A process according to  claim 41  wherein the fluid adhesive comprises a polymer selected from the group consisting of polyethylene, polyolefins, acid-containing polyolefins, ethylene vinyl acetate, ethylene-alkyl acrylate copolymers, polyvinylbutyral, acrylates, polyurethanes and mixtures thereof. 
   
   
       43 . A process according to  claim 41  wherein the fluid adhesive is applied by a method selected from the group consisting of spraying, rolling, curtain coating, extrusion coating, and brushing.