Patent ID: 6214466
Filing Date: 2001-04-10
Classification: A01N,E04D,Y10T

Abstract:
Algae-retardant roofing granules having an enhanced ability, over an extended period of time, to release bimetallic algicidal ions to prevent or inhibit the growth of algae and fungi upon atmospheric exposure of roofing surfaces coated with such granules comprising:a) a base material of crushed mineral aggregates in the form of granules coated with:b) a first layer of semi-ceramic composition consisting of a fired silicate-clay matrix containing from about 80 pounds to about 180 pounds of cuprous oxide per ton of said base material, and from about 6 pounds to about 60 pounds of zinc sulfide per ton of said base material; andc) a second layer of semi-ceramic composition consisting of a fired silicate-clay matrix containing: about 22.4 pounds of sodium silicate per ton of said base material; about 25 pounds of Kaolin clay per ton of said base material; and about 0-15 pounds of a pigment per ton of said base material.