Abstract: A filtering multilayer is described, having at least two layers, one input layer and one output layer, made of non-woven fabric, wherein each fiber of said non-woven fabric consists of a polymer matrix of thermoplastic material, wherein the average diameter of the fibers that form the input layer is larger than the average diameter of the fibers that form the output layer, characterized in that the diameters of the fibers that form the input layer and the output layer have a Gaussian distribution, wherein the diameter of the single fibers that form said input layer varies around the average with a normal distribution of width at least equal to 10% of the average value and the diameter of the single fibers that form said output layer varies around the average with a normal distribution of width at least equal to 14% of the average value. In a preferred embodiment, said polymer matrix contains a carbon-based filler or additive, preferably in the form of powder.

Abstract: A filtering multilayer is described, having at least two layers, one input layer and one output layer, made of non-woven fabric, wherein each fiber of said non-woven fabric consists of a polymer matrix of thermoplastic material, wherein the average diameter of the fibers that form the input layer is larger than the average diameter of the fibers that form the output layer, characterized in that the diameters of the fibers that form the input layer and the output layer have a Gaussian distribution, wherein the diameter of the single fibers that form said input layer varies around the average with a normal distribution of width at least equal to 10% of the average value and the diameter of the single fibers that form said output layer varies around the average with a normal distribution of width at least equal to 14% of the average value. In a preferred embodiment, said polymer matrix contains a carbon-based filler or additive, preferably in the form of powder.