Method of coating paper with pigmented protein containing oil-in-water emulsions having epoxy resin dispersed in oil phase

Claim 1

IN THE PRODUCTION OF PIGMENTS OCATED PAPER HAVING A CELLULAR STRUCTURE AND PROTEIN AS THE ESSENTIAL BINDER CONSTITUENT, THE STEPS OF: (A) APPLYING TO A PAPER WEB A COATING COMPOSITION WHICH IS AN OIL-IN-WATER EMULSION, SAID EMULSION HAVING IN THE CONTINUOUS AQUEOUS PHASE DISPERSED MINERAL PIGMENT AND SOLUBILIZED PROTEIN, SAID EMULSION HAVING IN THE DISCONTINUOUS PHASE AN OIL OF A LOWER VAPOR PRESSURE THAN WATER AND AN UNCURED EPOXY RESIN DISPERSED IN THE OIL, SAID EPOXY BEING REACTIVE WITH THE PROTEIN AND PRESENT OT THE EXTENT OF BETWEEN ABOUT 2% TO 20% BY WEIGHT OF THE PROTEIN AND THE RATIO OF PROTEIN TO OIL BY WEIGHT BEING BETWEEN ABOUT 1:1 TO 1:2.25; (B) HEATING THE WEB WITH THE COATING COMPOSITION THEREON TO BREAK THE EMULSION; (C) EVAPORATING THE WATER AND OIL BY THE HEATING STEP TO DRY THE COMPOSITION AND PRODUCE A MULTIPLICITY OF MINUTE LIGHT DISPERSING CELLS IN THE COATING COMPOSITION ON THE WEB AND TO CAUSE THE EPOXY RESIN TO COAT AND PENETRATE THE WALLS OF THE CELLS; AND (D) REACTING THE EPOXY RESIN WITH THE PROTEIN ON THE DRIED WEB TO STRENGTHEN THE STRUCTURE OF THE CELL WALLS, HARDEN THE COATING AND PROVIDE FOR UNIFORM LIGHT REFLECTANCE FROM THE COATED WEB.