Apparatus and method for the manufacture of a non-woven fibrous web

Abstract

Apparatus and method for the manufacture of a non-woven fibrous web, such as paper, from a dispersion of fibers in a foamed liquid. In a preferred embodiment, a solution of surfactant in water is initially discharged from a headbox into the nip of a twin forming wire prior to its passage over a curvilinear path defined by a forming roll. The water-surfactant solution is caused repeatedly to pass through the outer one of the twin forming wires until there is created, and stored in a silo, a foamed liquid containing about 65% air in the form of bubbles of from about 20 to about 200 microns in diameter. The foamed liquid is directed from the silo into a mix tank wherein a slurry containing fibers at 20% to 55% solids is added and mixed. The mixture is pumped to the headbox and into the nip of the forming wires. The outer wire retains the fibers while passing and again foaming the liquid for return to the silo and the mix tank for addition of fibers and return to the headbox. The process is continued in formation of a fibrous web. In an alternative embodiment, the curvilinear path is defined by an arcuate surface that is fluid pervious so that the solution to be foamed may pass through both the inner and outer wires. A further alternative embodiment utilizes a single forming wire for receiving the solution prior to passage over a suction breast roll which receives the solution then centrifuges it outwardly in formation of foamed liquid.