초록

Filter media sheets comprising particulate retention aid consisting of cellulose pulp of +100 to -100 Canadian Standard Freeness, and method of making the same.

대표청구항 ▼

A method for the manufacture of microporous filter sheet of uniform porosity for the removal of submicron contaminants from liquids comprising at least 50% by weight of fine particulate distributed within an interfelted matrix of cellulose fibers, the method comprising: providing a cationically disp

A method for the manufacture of microporous filter sheet of uniform porosity for the removal of submicron contaminants from liquids comprising at least 50% by weight of fine particulate distributed within an interfelted matrix of cellulose fibers, the method comprising: providing a cationically disperse aqueous slurry mixture, comprising: (a) an unrefined cellulose pulp having a Canadian Standard Freeness of +400 to +800 ml; (b) a highly refined cellulose pulp having a Canadian Standard Freeness of from +100 to about -1000 ml, the weight ratio of said unrefined pulp to said highly refined pulp being from 2:1 to about 10:1; and (c) fine particulate, constituting at least 50% by weight of the total solids; and forming said slurry into said microporous filter sheet by vacuum felting, and drying. A microporous filter sheet of uniform porosity for the removal of submicron contaminants from liquids which comprises at least about 50 weight percent of fine particulate distributed within an interfelted matrix of cellulose fibers, said cellulose fibers being prepared from a cellulose pulp mixture comprising an unrefined cellulose pulp having a Canadian Standard Freeness of from about +400 to about +800 ml., and a highly fefined cellulose pulp having a Canadian Standard Freeness of from +100 to about -1000 ml., the weight ratio of unrefined pulp to highly refined pulp being from about 2:1 to about 10:1, said particulate and said pulp mixture being dispersed in a cationically disperse aqueous slurry mixture and formed into a microporous sheet by vacuum-felting.