Adhesive composition comprising crosslinked maleic ester copolymers, method of preparation and a backing coated with said composition

Claim 1

AN ADHESIVE COMPOSITION ADAPTED TO STICK TO UNPRIMED POLYVINYLCHLORIDE RESIN FILM TO PROVIDE AN ADHESIVE LAYER SURFACE WHICH IS CHARACTERIZED BY TENACIOUS ADHESION TO OTHER OBJECTS INCLUDING HUMAN SKIN BUT RELATIVELY LITTLE ADHESION TO ITSELF, WHEREBY UPON CONTACT OF TWO PORTIONS OF THE ADHESIVE SURFACE THEY WILL NOT ADHERE TO EACH OTHER TO SUCH AN EXTENT THAT UPON THEIR SEPARATION FROM EACH OTHER THERE IS DISRUPTION OF THE ADHESIVE MASS AND UNDUE DEFORMATION OF THE FILM BACKING, SAID COMPOSITION COMPRISING AN ESTER OF A COPOLYMER OF MALEIC ANHYDRIDE AND A VINYL ETHER HAVING AN ALKYL GROUP OF 1 TO 8 CARBON ATOMS COPOLYMERIZED IN APPROXIMATELY EQUIMOLECULAR PROPORTIONS, THE COPOLYMER HAVING AN INTRINSIC VISCOSITY IN THE APPROXIMATE RANGE OF 0.2 TO 2.0 AS MEASURED IN CYCLOHEXANONE AT 30*C., AT LEAST 70% OF THE POTENTIAL CARBOXYL GROUPS PRESENT IN THE ANHYDRIDE GROUPS IN SAID COPOLYMER BEING ESTERIFIED WITH AN ALIPHATIC PRIMARY MONOHYDRIC SATURATED ALCOHOL HAVING 6 TO 16 CARBON ATOMS SAID ESTER HAVING BEEN HEATED IN THE PRESENCE OF ADDED PEROXIDE POLYMERIZATION CATALYST TO PROVIDE A GEL CONTENT IN THE RANGE OF 10 TO 100% BY WEIGHT, THE PLASTICITY OF SAID COMPOSITION BEING NOT GREATER THAN ABOUT 4.0 MM. AND THE COLD FLOW OF SAID COMPOSITION BEING NOT GREATER THAN 2.5 INCHES, SAID GEL CONTENT BEING 100 MINUS THE PERCENT OF THE ADHESIVE COMPOSITION WHICH IS REMOVED FROM 0.4 GRAM OF THE ADHESIVE COMPOSITION BY MIXING IT WITH 100 CC. OF BENZENE, ALLOWING THE MIXTURE TO STAND WITHOUT STIRRING FOR 48 HOURS AT 30*C., THEN FILTERING THE MIXTURE THROUGH A STAINLESS STEEL WIRE SCREEN OF 100 MESH AND SEPARATING THE RESIDUE FROM 25 CC. OF THE FILTRATE BY EVAPORATING THIS FILTRATE TO DRYNESS AT 100*C., SAID PLASTICITY BEING THE HEIGHT OF A CYLINDRICAL PELLET OF THE COMPOSITION WEIGHTING 2.0 GRAMS AND HAVING AN INITIAL DIAMETER OF 16 MM. PLACED ON A PARALLEL PLATE PLASTOMETER AND MAINTAINED AT 100*F. UNDER A LOAD OF 5000 GRAMS MEASURED AT THE END OF A 14 MINUTE PERIOD, AND SAID COLD FLOW BEING MEASURED BY STICKING A BALL OF THE ADHESIVE WEIGHING 3.0 GRAMS AGAINST A VERTICAL GLASS PLATE AND MEASURING THE DOWNWARD FLOW THEREOF AT ROOM TEMPERATURE AT THE END OF A 24 HOUR PERIOD.