Silicate coated roofing granules
AssigneeGAF Corporation
InventorIngo B. Joedicke
Life of this patent
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Abstract
Roofing granules coated with insolubilized reaction product of a coating composition comprising water, kaolin clay, sodium silicate, pigment, and gas forming compound such as hydrogen peroxide or sodium perborate.
Claims12
A roofing granule comprising a base mineral granule substrate having a dehydrated, pigmented, moisture permeable, substantially water insoluble sodium silicate kaolin clay coating, said coating comprising an opaque, solid matrix having a layered plate-like structure aligned parallel with the substrate and containing light scattering closed voids uniformly and individually dispersed therein to thereby enhance the opacity of the coating, said voids also having a plate-like shape and being aligned parallel with the substrate with at least a majority of the voids being between about 0.05 and about 0.5 micron thick.
A roofing granule comprising a base mineral granule having a coating comprising insolubilized reaction product of a mixture of:
- (a) water;
- (b) kaolin clay;
- (c) sodium silicate;
- and
- (d) inorganic gas forming compound which is soluble in said mixture and decomposes to gaseous products below about 500.degree. F. when dispersed in an alkaline silicate film.
Dependencies are inferred from the claim text.