CONTROLLED TIME-RELEASE ALGAE RESISTANT ROOFING SYSTEM

摘要

Time-release algae-resistant roofing granules have a base particle including an algaecide and an outer coating layer including another algaecide. The at least two algaecides are released over different predetermined periods. The outer layer protects the base particle from exposure to the environment for a predetermined period, then fails catastrophically so that the interior algaecide can be released.