Mineral-filled roofing membrane compositions and uses therefor

A bilaminant roofing membrane comprising a first ply of white polymeric sheeting material and a second ply of polymeric sheeting material, said first ply of white polymeric sheeting material being laminated to said second ply of polymeric sheeting material and being prepared from a composition of matter consisting essentially of

• 100 parts by weight of at least one polymeric rubber selected from the group consisting of ethylene-propylene-diene terpolymers, ethylene-propylene copolymers and other polyolefinic type polymers;
• from about 60 to about 150 parts by weight of a blend of at least two mineral fillers, per 100 parts of said polymeric rubber, wherein one of said mineral fillers is a reinforcing silica and wherein another of said mineral fillers is a clay surface modified with a polvfimctional silane coupling agent;
• from about 35 to about 100 parts by weight of a processing oil per 100 parts of said polymeric rubber;
• from about 2.5 to about 5 parts by weight of a sulfur cure package having at least one accelerator but being devoid of any thiuram accelerators, said cure package allowing said first ply of sheeting material to cure at about the same rate as said second ply of sheeting material at 160.degree. C.

A method for covering a roof comprising:

• applying a bilaminant of sheeting material comprising a white-colored top ply and a black-colored bottom ply to the roof being covered;
• said white colored ply being prepared from a composition of matter comprising
• 100 parts by weight of at least one polymeric rubber selected from the group consisting of ethylene-propylene-diene terpolymers, ethylene-propylene copolymers and other polyolefinic type polymers;
• from about 20 to about 300 parts by weight of a blend of at least two non-black mineral fillers, per 100 parts of said polymeric rubber, wherein one of said mineral fillers is a reinforcing silica and wherein another of said mineral fillers is a chemically modified clay;
• from about 20 to about 150 parts by weight of a processing oil, per 100 parts of said polymeric rubber;
• from 1 to about 6 parts by weight of a sulfur cure package having at least one accelerator but being devoid of any thiuram accelerators, said cure package allowing said sheeting material to cure at about the same rate as a comparable black roof sheeting material at 160.degree. C.