US Patent 10570263 Degradable sheet material

A sheet material formed of a degradeable composition comprising 30 to 80 wt % calcium carbonate, an additive, and the balance a polymer selected from polyethylene, polypropylene and copolymers and blends thereof. The additive comprises (a) two or more transition metal compounds, (b) a mono- or poly-unsaturated C14-C24 carboxylic acid, or an ester, anhydride or amide thereof, (c) a synthetic rubber. The addition optionally comprises (d) dry starch, and/or (e) calcium oxide, and/or (f) a phenolic antioxidant stabilizer. The two or more transition metal compounds are selected from iron, manganese, copper, zinc, titanium, cobalt and cerium compounds and the transition metals in the two or more transition metal compounds are different.