Pressure-Sensitive Adhesives for Medical Applications

Since their introduction half a century ago, pressure-sensitive acrylic adhesive has been successfully applied in many fields. They are used in self-adhesive tapes, labels, sign and marking films and protective films as well as in dermal dosage systems for pharmaceutical applications, in biomedical electrodes, plasters, the assembly of automotive parts, toys, and electronic circuits and keyboards. In the last sixty years or so, pressure-sensitive adhesive (PSA) acrylics have made tremendous strides from what was virtually a black art to what is now a sophisticated science. So much so that both the few larger manufacturers of pressure-sensitive adhesive articles and their even larger suppliers now use very expensive equipment to study pressure-sensitive adhesive behavior: tack, adhesion and cohesion. Three properties which are useful in characterizing the nature of pressure-sensitive adhesives are tack, peel (adhesion) and shear (cohesion). The first measures the adhesive's ability to adhere quickly, the second its ability to resist removal by peeling, and the third its ability to hold in position when shearing forces are exerted. Generally speaking the first two are directly related to each other but are inversely related to the third.