Manufacture of wet laid nonwoven webs

Abstract

A method for forming a fibrous web by wet-laying fibers on paper-making equipment, the web comprising staple length natural or synthetic fibers and wood cellulose paper-making fibers wherein a water furnish of the fibers is made up with an associative thickener in the absence of a conventional surfactant. A preferred associative thickener for use with hydrophobic fibers is a urethane block copolymer having a polyethylene glycol backbone, the associative thickener acting as both surfactant and thickener. With predominately cellulosic fibers, i.e. conventional wood cellulose fibers, or a mixture of conventional and contorted wood fibers, and synthetic cellulosic fibers, such as rayon, a hydroxyethyl cellulose having a long alkyl side chain is preferred. Excellent consistency of the water and fiber dispersion is obtained at relatively low viscosity with rapid drainage of water from the wire and uniform formation of the web.