Patent ID: 8846138
Filing Date: 2014-09-30
Classification: B41M,D21H

Abstract:
1. A method for surface treatment of a paper substrate comprising: applying a salt-containing solution to at least one surface of the paper substrate by aerosol spraying; and separately applying a surface sizing composition to the at least one surface of the paper substrate using a size press either before or after applying the salt-containing solution and without drying in between the separate application steps, said salt-containing solution comprising at least one water-soluble metal salt having a metal cation in an aqueous solvent and being void of any optical brightening agent (OBA), the surface sizing composition comprising a water-soluble or water-dispersible binder, a surface sizing agent, and an OBA, wherein the salt-containing solution has a metal salt concentration of up to 30% by weight and a solids content of less than 30%, wherein aerosol spraying the salt-containing solution comprises using a flow rate ranging from 1400 cubic centimeters/min (cc/min) to 5500 cc/min, a pressure ranging from 400 pounds per square inch (psi) to 850 psi, and nozzles that produce a fan-shaped aerosol spray, and wherein the amount of metal salt applied is greater than 0 and up to 10 kilograms per ton of paper substrate, and the metal salt distribution through the thickness of the treated paper substrate achieved after applying the salt-containing solution is non-uniform with the highest concentration of metal salt being present in the outermost portion of the paper substrate.