Composite filtering medium and method for production thereof

A method for producing a composite filtering medium comprising a base fabric, of the type with weft and warp of threads of monofilaments (2) of polyether ether ketone (PEEK), characterized in that said method comprises a step of electrospinning for formation of nanofibres (3) of polyimide (PI) and a subsequent step of deposition of said nanofibres on said base fabric;

• said method comprising injection of the material for formation of the nanofibres, dissolved in a mixture of dimethyl acetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) in excess of NMP solvents, through a nozzle in order to spread it on an electrode, said method comprising application of a difference of potential between said nozzle and an electrode;
• said nanofibres being formed as a result of evaporation of said solvent or mixture of solvents, due to the electrical field, and stretching of the polymer deposited on the electrode, by means of the nozzle;
• said nanofibres thus formed being subsequently stretched and deposited on said base fabric;
• wherein said nanofibres (3) firmly adhere to said base fabric, without the aid of glues and/or adhesive agents applied on the base fabric and/or on the nanofibre layer, at the swellings (4) of the threads (2) of said base fabric, which are formed on the surfaces of contact of the threads (2) themselves with said nanofibres (3) when adding said nanofibres.