The invention relates to a formulation suitable to provide polyurethane, the formulation comprising (a) at least one polyurethane forming mixture; (b) at least one phosphate component selected from the group consisting of ammonium polyphosphate (APP) and melamine phosphates, and mixtures thereof, and; (c) at least one metal or metalloid oxide particle having a maximum particle size of less than 300 μm, wherein the metal or metalloid is selected from the group consisting of Mg, and Al, and wherein said at least one phosphate component is present in an amount ranging from 20 to 45% by weight based on 100% by weight of the formulation.