Forming colored patterns upon polyolefin surfaces

Claim 1

A METHOD OF FUSING A HEAT-SET, INK COMPOSITION INTO THE SURFACE OF SUPPORTED FILMS OF POLYETHYLENE OR POLYPROPYLENE TO OBTAIN PERMANENT PRINTED MATTER THEREON WHICH COMPRISES (1) PRINTING ON THE SURFACE OF SAID FILMS WITH A LETTERPRESS INK COMPOSITION AND (2) SUBSEQUENTLY HEATING THE PRINTED SURFACE TO A TEMPERATURE RANGING FROM ABOUT 275*-350*F. BY PASSING THE REVERSE SIDE OF SAID SUPPORTED PRINTED SURFACE AT THE RATE OF ABOUT 200-600 FEET PER MINUTE OVER A HEATING ELEMENT HAVING A TEMPERATURE OF ABOUT 325*F. TO 375*F. WHILE (3) SIMULTANEOUSLY SUBJECTING THE PRINTED SIDE OF THE FILM''S SURFACE TO A CURRENT OF HOT AIR HAVING A TEMPERATURE OF ABOUT 200*-500*F.; SAID INK COMPOSITION CONSISTING ESSENTIALLY OF 25-35 PARTS-BY-WEIGHT OF A COLORING PIGMENT, 9-10 PARTS-BY-WEIGHT OF LINSEED OIL, ABOUT ONE PART-BY-WEIGHT OF COBALT NAPHTHENATE AND 55-64 PARTS-BY-WEIGHT OF A VARNISH-SOLVENT MIXTURE CONSISTING OF A HEAT-SET VARNISH AND AN ORGANIC SOLVENT HAVING A BOILING RANGE OF ABOUT 472*-504*F. WHEREIN THE VARNISH IS PRESENT IN AN AMOUNT OF 45-60% BY WEIGHT.