Hercules Corporation

Harry J Goldy

Ronald Richard Staib

Daniel H Craig

Douglas C Smith

Jay A Dickerson

This invention is directed to a process for preparing an aqueous papermaking suspension containing a polyelectrolyte complex comprising providing an aqueous suspension of pulp fibers containing a water-soluble cationic polymer and a water-soluble anionic polymer that are reactable in the aqueous suspension to form the polyelectrolyte complex, and a multivalent cation having at least a &plus;3 charge, and forming the polyelectrolyte complex. It also includes the process wherein the aqueous suspension of pulp fibers contains surface active carboxyl compounds and water-soluble anionic compounds. It further includes the process wherein the aqueous papermaking suspension is sheeted and dried to obtain paper of improved strength.

Strength of paper made from pulp containing surface active, carboxyl compounds

Acrylate copolymers comprising (a) repeating units derived from at least one acrylic or methacrylic ester and, by weight of the total copolymer, (b) about 0.1 to 3% of repeating units derived from at least one water-soluble monomer possessing conjugated unsaturation and (c) about 0.1 to 3% of repeating units derived from at least one water-soluble allyl monomer; aqueous polyacrylate dispersions comprising such polymers; and a process of preparing the same. Optionally, the copolymers contain other free-radical polymerizable monomers.

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Woodlyn, PA, United States of America

Harry J Goldy