Removable pressure-sensitive adhesive sheet material

Claim 1

IN ADHESIVE-COATED SHEET MATERIAL COMPRISING IN COMBINATION A SELF-SUSTAINING BACKING SHEET HAVING A LAYER OF NORMALLY TACKY AND PRESSURE-SENSITIVE ADHESIVE BONDED TO AT LEAST ONE FACE THEREOF, THE IMPROVEMENT WHICH COMPRISES USING AS SAID ADHESIVE A COPOLYMER OF MONOMERS CONSISTING ESSENTIALLY OF A. FROM 88 TO 99 PARTS BY WEIGHT OF AT LEAST ONE TERMINALLY UNSATURATED VINYL MONOMER, 70 TO 100 WEIGHT PERCENT OF SAID VINYL MONOMER BEING SELECTED FROM THE CLASS OF NON-TERITARY ALKYL ACRYLATES WHEREIN EACH ALKYL GROUP HAS AT LEAST HALF OF ITS CARBON ATOMS IN A SINGLE CHAIN AND THE AVERAGE LENGTH OF THE ALKYL CHAIN IS MORE THAN 4 AND NOT MORE THAN 12. B. FROM 0.2 TO 5 PARTS BY WEIGHT OF AT LELAST ONE VINYLUNSATURATED, HOMOPOLYMERIZABLE EMULSIFIER MONOMER WHICH IS A SURFACTANT HAVING BOTH A HYDROPHOBIC AND A HYDROPHILIC MOIETY, CONTAINS AT LEAST 5 BUT NOT MORE THAN 40 CARBON ATOMS AND IS NONIONIC AND OR WATER-DISPERSIBLE, AND C. FROM 0 TO 10 PARTS BY WEIGHT OF AT LAST ONE ZWITTERION MONOMER HAVING A FREE RADICALLY POLYMERIZABLE UNSATURATED GROUP, THE TOTAL PARTS BY WEIGHT OF (B) PLUS (C) BEING AT LEAST 1 AND NOT MORE THAN 12, AND THE TOTAL PARTS BY WEIGHT OR (A) PLUS (B) PLUS (C) BEING 100, WHEREBY SAID ADHESIVE-COATED SHEET MATERIAL CAN BE SUFFICIENTLY FIRMLY ADHERED TO ENAMELED OR LACQURED SURFACES TO SATISFY THE REQUIREMENTS OF A MASKING TAPE AND REMOVED CLEANLY THEREFROM, EVEN AFTER EXPOSURE TO HEAT, FOR EXAMPLE, 250*F FOR 1 HOUR, AND LIGHT.