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CONTROLLING PEEL ADHESION VIA HETEROGENEOUS (MICROSPHERE) PSA SYSTEMS

Steven Correa, Chemist, National Starch and Chemical Company, Bridgewater, NJ
Dawn Smith*, Sr. Project Supervisor, National Starch and Chemical Company, Bridgewater, NJ
Dorothy Maglioeea, Sr. Project Supervisor, National Starch and Chemical Company, Bridgewater, NJ
Nabil Zahlan, Group Scientist, Strategic Technology Group, ICI, Wilton, United Kingdom

* current address: LifeLines Technology Inc., Morris Plains, NJ

The concept of removable pressure sensitive adhesives via a heterogeneous (microsphere) system has been around for more than two decades. Microsphere technology offers significant improvements over traditional removable PSA's, including clean removability from a variety of surfaces, consistent peel characteristics, and multiple use (re-seal) capabilities. These adhesives have a unique composite structure in which micron-sized spheres are held together by a continuous phase known as the binder. The characteristics of the adhesive are achieved, in part, through the discontinuous surface morphology. Unlike traditional homogeneous PSA's, the microsphere adhesive film does not completely wet the substrate to which it is applied. As a result, peel forces are lower and they do not build significantly over time. This class of adhesives was invented and patented by 3M in the 1970's and the technology was successfully commercialized in 1980 with the introduction of Post-It ™ Notes. The utility of this technology goes far beyond just removable notes, however. PSA manufacturers and converters have found a variety of applications including "magnetic" photo albums, removable piggyback labels, temporary wallpaper borders and posters, children's craft activities, and non-staining price tags for clothing. Microsphere technology can be used almost anywhere a low peel, cleanly removable application exists. The possibilities are only limited by the imagination.

In this work, microscopy, peel testing and surface analysis techniques were used to study the application and removal of several model microsphere systems from standard surfaces under controlled conditions. The results give a better understanding of commercial, formulated heterogeneous PSA's in their end-use applications.