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摘要

A process for manufacturing a filter medium comprises the following operations: preparing in a pulper or beater a pH 3-5 aqueous suspension of cellulose fibres with a concentration of between 3% and 5%; preparing in a pulper or beater a pH 2.8-3.8 aqueous suspension of glass fibres with a fibre concentration of between 0.5% and 1.2%; preparing a first pulp consisting exclusively of cellulose fibres, to which a moisture-resistant resin is added; preparing a second pulp consisting of cellulose fibres and glass fibres in proportions of between 30% and 70%, to which a moisture-resistant resin is added; forming two superposed layers of said pulps by methods used in paper manufacture; collecting said two layers on a layer of material able to absorb water; pressing the two superposed layers of pulp to a pressure of between 0.1 and 1 kg/cm2; drying the resultant sheet to a moisture content of 1%; impregnating the dried material with a 50 wt% solution of acrylic latex; again drying and winding on a reel.