Multilayered membrane and the method of producing the membrane

摘要

The present invention relates to the production of filter membranes (10) and in particular to multilayered filters. The invention related to a method of producing a filter membrane (10) wherein at least two layers (12, 14) are sequentially built upon a forming member (18) such that, when the forming member (18) is removed, the resultant membrane (10) includes a plurality of apertures extending therethrough, and at least some of said apertures increase in cross-sectional area from a first surface of the membrane to a second surface of the membrane. The method of production reduces the risk of permanent plugging from particulates being trapped within the membrane itself and has strong bonds between the layers which reduce the risk of separation of the layers. The present method produces an even coverage of the forming member (18) which in turn results in a layer of uniform thickness. The layer can be controlled by changing the viscosity of the mixture into which the former (18) is dipped.