Mono- or multi-material filter and process for its manufacture

Material mono or multilayer filter, wherein at least one layer thereof consisting of cellulose, glass fibers, synthetic fibers or a mixture thereof is impregnated with a binder consisting of an epoxy resin and a curing medium, characterized in that curing media includes a first hardener crosslinking at low temperature and a second hardener crosslinking at a higher temperature, whereby the epoxy resin hardens stepwise depending on the temperature.