PROCESS FOR THE CONTINUOUS MANUFACTURE OF PAPER SHEETS OF FIBROUS MATERIALS AND LATEX

摘要

An improvement is provided in a process provided for manufacturing sheets of fibrous materials in a paper making machine by the admission, to the paper-making machine, of a pulp containing fibrous material and latex in an aqueous medium. The process involves preparing the pulp in the following way: (a) providing an aqueous suspension of the fibres having an anionic charge; (b) providing an aqueous suspension of finely divided latex particles, having an anionic charge stabilized at a pH of between 4 and 5, the amount of latex in the dry state being between 3 and 75% with respect of the total weight of fibrous material, the diameter of the latex particles being between 0.01 and 0.5.mu. ; (c) adding, to the aqueous suspension of fibers prepared in step (a), a polyelectrolyte having a molecular weight greater than 15,000 and a cationic charge, said polyelectrolyte being used in the form of a solution containing between 0.2 and 10% by weight of polyelectrolyte, the amount of polyelectrolyte added to the aqueous suspension of fibers being between 0.1 and 3.5% with respect to the total dry weight of the latex, to be added later; (d) adjusting the pH of the obtained mixture to a value between 4 and 5.5; and (e) adding, to the obtained mixture, the aqueous suspension of latex prepared in step (b). The homogeneous and porous paper sheets so formed are ones in which the later particles are substantially completely fixed on the fibers, so that the latex particles remain substantially unflocculated, and substantially uncoagulated.