Photocatalytic roofing granules, photocatalytic roofing products and process for preparing same

Abstract

Photocatalytic roofing granules include a binder and inert mineral particles, with photocatalytic particles dispersed in the binder.

1 . Photocatalytic roofing granules comprising:
 (a) a binder;   (b) inert mineral particles; and   (c) photocatalytic particles selected from the group consisting of anatase titanium dioxide and zinc oxide; the inert mineral particles and the photocatalytic particles being dispersed in the binder, the granules having an average particle size from about 0.1 mm to 3 mm.   
     
     
         2 . (canceled) 
     
     
         3 . Photocatalytic roofing granules according to  claim 1  wherein the photocatalytic particles have an average particle size from about 5 nanometers to 5 microns. 
     
     
         4 . (canceled) 
     
     
         5 . Photocatalytic roofing granules according to  claim 1  wherein the inert mineral particles have an average particle size from about 0.1 micrometers to 40 micrometers. 
     
     
         6 . (canceled) 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . Photocatalytic roofing granules according to  claim 1  wherein the binder is selected from the group consisting of silicate, silica, phosphate, titanate, zirconate, and aluminate binders, and mixtures thereof. 
     
     
         10 . Photocatalytic roofing granules according to  claim 9  wherein the binder further comprises an inorganic material selected from the group consisting of aluminosilicate and kaolin clay. 
     
     
         11 . Photocatalytic roofing granules comprising:
 (a) a porous body comprising inert mineral particles; and   (b) photocatalytic particles selected from the group consisting of anatase titanium dioxide and zinc oxide within the pores of the body, the granules having an average particle size from about 0.1 mm to 3 mm.   
     
     
         12 . (canceled) 
     
     
         13 . Photocatalytic roofing granules according to  claim 11  wherein the photocatalytic particles have an average particle size from about 5 nanometers to 5 microns. 
     
     
         14 . (canceled) 
     
     
         15 . Photocatalytic roofing granules according to  claim 11  wherein the inert mineral particles have an average particle size from about 0.1 micrometers to 40 micrometers. 
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . (canceled) 
     
     
         19 . Photocatalytic roofing granules according to  claim 11  further comprising a binder selected from the group consisting of silicate, silica, phosphate, titanate, zirconate, and aluminate binders, and mixtures thereof. 
     
     
         20 . Photocatalytic roofing granules according to  claim 19  wherein the binder further comprises an inorganic material selected from the group consisting of aluminosilicate and kaolin clay. 
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . A process for preparing photocatalytic roofing granules, the process comprising:
 (a) providing a binder and inert mineral particles to form a mixture; photocatalytic particles;   (b) forming the mixture into porous granules;   (c) curing the binder to form a porous granule body; and   (d) dispersing the photocatalytic particles in the pores of the granule body.   
     
     
         24 . A roofing product comprising photocatalytic roofing granules according to  claim 1 . 
     
     
         25 . A process for preparing photocatalytic roofing granules, the process comprising:
 (a) providing ceramic particles;   (b) forming the ceramic particles into uncured granule bodies having an exterior surface;   (c) sintering the uncured granule bodies to form sintered granule bodies; and   (d) adhering photocatalytic particles to the exterior surface of the sintered granule bodies to form photocatalytic roofing granules.   
     
     
         26 . A process according to  claim 25  further comprising providing a sintering binder and mixing the sintering binder with the ceramic particles to form a mixture and subsequently forming the mixture including the ceramic particles into uncured granule bodies. 
     
     
         27 . A process according to  claim 25  wherein the photocatalytic particles are mechanically adhered to the exterior surface of the uncured granule bodies. 
     
     
         28 . A process according to  claim 25  further comprising:
 (a) mixing the photocatalytic particles with an exterior binder to form an exterior coating composition; 
 (b) applying the exterior coating composition to the cured granule bodies; and 
 (c) curing the exterior coating composition. 
 
     
     
         29 . (canceled) 
     
     
         30 . (canceled)