Viscous dispersion for forming wet-laid, non-woven fabrics

A process for forming a non-woven fabric by wet-laying, on paper making equipment, staple length, synthetic fibers having a length to diameter ratio of about 400 to 3000, the fabric having a microvariation in basis weight of not more than about 10% and a macrovariation in basis weight of not more than about 5%, and the fabric being essentially free of knits, bundles and strings, comprising the steps of:

• adding about 0.1% to 3.0% by weight of a fiber furnish containing said fibers to a high-shear agitated mixture of water and at least 0.0001% by weight of a dispersant, to separate the fibers and to completely and uniformly distribute the individual fibers throughout the resulting, high-shear agitated mixture containing about 1% to 4% by volume of entrained air;
• the high-shear agitated mixture being agitated vigorously enough to create tumbling surface conditions with little or no vortex and without creating any substantial amount of surface foam;
• then, slowly adding a thixotropic thickener, over a period of about 10 minutes or longer, to the high-shear agitated mixture to form the viscous dispersion;
• the viscous dispersion containing about 1% to 50% by volume of entrained air and having a nascent viscosity of about 10 to 125 cps., when measured at a shear rate of 30.5 sec..sup.-1 ;
• and individual fibers in the viscous dispersion being restrained from becoming entangled and from forming knits, bundles and strings;
• diluting the viscous dispersion with a viscous, diluting medium, having about the same nascent viscosity as the viscous dispersion to form a once-diluted, viscous dispersion;
• and
• diluting the once-diluted, viscous dispersion in an eductor with a white water;
• the once-diluted, viscous dispersion being pumped to the annulus ring of the eductor utilizing a helical progressive cavitation pump;
• and the white water having a nascent viscosity of 5 to 30 cps., at a shear rate of 30.5 sec..sup.-1, and containing about 1% to 10% by volume of entrained air.