Abstract: A filter cartridge formed by winding, in a twill construction, a band-shaped unwoven cloth, which contains thermoplastic fibers and at least a part of its fiber intersections are stuck thereon, so that a cylindrical shape can be obtained, wherein 1. two types of filtrating layers are used, 2. unwoven cloth having opening hole parts is used, 3. an end face seal part is provided on both end parts of the cartridge, 4. unwoven cloth having a tongue piece part is used, or 5. two or more pieced of unwoven cloth are wound simultaneously, whereby those characteristic of the filter cartridge such as liquid permeability, filterable life, and stability of filtration accuracy can be kept in balance with each other.

Abstract: Filters having a high accuracy, small pressure loss, and long filtration life compared with conventional filters are provided. The filters are composed of non-woven fibrous agglomerates and are constructed in such a way that at least two layers of a non-woven fibrous agglomerate of a pre-filtration layer and a precision filtration layer are disposed therein; the pre-filtration layer is constructed in such a way that the diameter of the fibers in the pre-filtration layer becomes gradually smaller toward the direction of filtration; and at least 10% by weight of the fibers in the precision filtration layer are fibers having a diameter smaller than that of the fibers having a smallest diameter in the pre-filtration layer.