Pilot-scale evaluation of environmentally benign PSA stamps

Along with the increased use of pressure-sensitive adhesive products, concerns have emerged about their environmental impact. To address these concerns, the U.S. Postal Service initiated an environmentally benign pressure-sensitive adhesive (PSA) program to develop postal stamps that do not adversely affect the environment. As part of this program, experimental adhesives were evaluated for stamp performance specifications, laboratory recycling, and pilot-scale recycling. Laboratory and pilot-scale recycling trial results are presented in this paper. Synthetic rubber or acrylic-type experimental PSAs were rupulpable, and adhesive levels were removed satisfactorily by screening, cleaning, and flotation processes. Compared with synthetic rubber or acrylic-types, dispersible acrylic-type experimental PSAs produced adhesive levels that were not as effectively removed in pilot-scale recycling trials.