| 摘要 |
Metal algicides, such as zinc and copper, are sprayed in the form of droplets of molten metal onto the surface of roofing granules or onto the surface of asphalt roofing compositions in which said granules are embedded. The metal algicides solidify and adhere on the surface of said granules or compositions as relatively fine, randomly distributed, irregular shaped metal globules. During periods of rain or dew upon atmospheric exposure of roofing compositions thus flame treated, or incorporating therein roofing granules so treated, the oxidized globules become ionized so that metallic algicidal ions are slowly released therefrom and leached over the roofing surface, thus retarding the biological growth of algae and/or fungi over extended periods of time. The invention permits an effective distribution of algicidal material over the surface treated, requires the use of advantageously low dosage levels of said metals for satisfactory, long-term algicidal action, and provides a high degree of compatibility with the requirements of conventional roofing granule and asphalt roofing composition production.
|
