Manufacture of combined paperboard and silicate-clay adhesives therefor

Claim 1

A CLAY-SILICATE ADHESIVE WHICH WHEN HEATED TO TEMPERATURES OF FROM ABOUT 50* TO 85* C. IS SUITABLE FOR USE ON HIGH-SPEED LAMINATING MACHINES, WHICH COMPRISES FROM ABOUT 12 TO 25 PER CENT OF A COLLOIDAL CLAY DISPERSED IN AN AQUEOUS PHASE COMPRISING A SODIUM SILICATE SOLUTION HAVING A PER CENT BY WEIGHT RATIO OF SIO2 TO NA2O WITHIN THE RANGE OF ABOUT 3.2:1 TO 3.9:1, HAVING A VISCOSITY OF FROM ABOUT 1 TO 8 POISES AT 20* C. AND A GRAVITY OF FROM ABOUT 33* TO 44* BE''., SUFFICIENT CLAY BEING PRESENT TO PRODUCE A FILTER TEST OF FROM ABOUT 0.01 TO 3 ML. AND AN OVER-AL VISCOSITY AT 20* C. OF FROM ABOUT 5 TO 15 POISES, THE OVER-ALL VISCOSITIES VARYING INVERSELY WITH THE FILTER TESTS WITHIN THE RANGES SET OUT, THE AQUEOUS PHASE VISCOSITY AND THE SILICATE RATIO OF THE ADHESIVE BEING SO CORRELATED THAT THE LOWER VISCOSITIES OCCUR WITH THE HIGHER SILICATE RATIOS; THE AQUEOUS PHASE VISCOSITY AND THE SILICATE RATIO OF THE ADHESIVE BEING SO CORRELATED THAT THE LOWER VISCOSITIES OCCUR WITH THE HIGHER SILICATE RATIOS; THE COMPOSITION OF THE AQUEOUS PHASE OF SAID ADHESIVE BEING SUCH THAT ITS VISCOSITY AND GRAVITY FALL ON ITS VISCOSITY-GRAVITY CURVE ALONG THAT PORTION WHICH EXTENDS FROM THE KNEE TO MAXIMUM VALUES, FALLING ON THE HIGH VISCOSITY LEG OF SAID CURVE, OF ABOUT 8 POISE AND 44* BE''.; THE GRAVITY AND THE SILICATE RATIO BEING SO CORRELATED THAT THE HIGHER GRAVITIES OCCUR WITH THE LOWER SILICATE RATIOS; AND SAID ADHESIVE HAVING THE CAHRACTERISTIC PROPERTY OF HAVING AN OVER-ALL VISCOSITY WHICH EVEN WITHOUT LOSS OF MOISTURE PASSES THROUGH A MINUMUM VALUE OF FROM ABOUT 0.5 TO 5 POISES WITHIN THE TEMPERATURE RANGE OF FROM 50* TO 85* C. AND WHICH RISES WITH INCREASE OF TEMPERATURE ABOVE SAID MINUMUM WHEREBY A FLASH SET IS PRODUCED UPON APPLICATION OF SAID ADHESIVE TO A SURFACE WHICH IS PREHEATED TO A TEMPERATURE ABOVE THAT OF SAID VISCOSITY MINIMUM; THE CLAY CONTENT OF THE ADHESIVE BEING UNDISSOLVED AND UNREACTED.