Method of preparing adhesive composition comprising a maleic anhydride copolymer andproduct obtained

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 COMPOUND SELECTED FROM THE GROUP CONSISTING OF STYRENE AND VINYL TOLUENE COPOLYMERIZED IN APPROXIMATELY EQUIMOLECULAR PROPORTIONS, THE COPOLYMER HAVING AN INTRISIC 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, AND A HIGHLY POLYMERIZED MATERIAL FROM THE GROUP CONSISTING OF POLYVINYL ETHYL ETHER, BUTADIENE-STYRENE, POLYISOBUTYLENE AND POLYETHYLACRYLATE IN AN AMOUNT EQUAL TO AT LEAST 5% BY WEIGHT OF THE COMPOSITION, 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 PLASTICITY BEING THE HEIGHT OF A CYLINDRICAL PELLET OF THE COMPOSITION WEIGHING 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.