Laminated non-woven fabric filtering medium and method for producing same

摘要

A laminated non-woven fabric for filtering medium, which is composed of a plurality of non-woven fabric layers having different average pore sizes and laminated in the order of the average pore size, and a plurality of entangled regions interposed between any of adjacent two non-woven fabric layers which is formed by causing fibers of one of the adjacent two non-woven fabric layers to penetrate into the other layers to entangle the penetrated fibers with fibers of the other layers. The presence of the entangled regions provide a gradual change of the pore size from a non-woven fabric layer to another non-woven fabric layer to result in a good filtering efficiency and an elongated lifetime of a filter.