METHOD FOR MOULDING A FILTER

A method of molding a micro-fibrous filter including the steps of: (a) forming an aqueous slurry of micro-fibers; (b) introducing the slurry under pressure into the top of an annular molding space so that a mass of fibers becomes compacted on a vertical cylindrical screen and liquid is discharged from the molding space through the screen; (c) increasing the effective open area of the screen by moving upwardly a sleeve in sliding contact with the screen at a rate substantially equal to the rate at which the height of the mass of fibers increases above the support; then (d) removing, drying, and curing the resulting tubular mass of fibers. Acrylate binder resin compatible with the e.g. acidic conditions needed to stabilize the resin, can form part of the fiber slurry used for molding the filter, and after filter formation and drainage can be cured by heat to form the filter.