Water-soluble/dispersible cationic pressure-sensitive adhesives. I. Adhesives from solution polymerization

Pressure-sensitive adhesives (PSAs) have long been a problem as sticky contaminants for paper recycling mills. The main problem associated with such stickies is that the PSAs in the waste papers deposit on the felts, press rolls, and drying cylinders of paper machines, and this creates problems with paper formation, reducing the paper quality and paper machine runnability. The annual cost of stickies to the U.S. paper industry is estimated to be about $600,000,000-650,000,000. To solve this problem, a series of cationic water-soluble/dispersible PSAs have been synthesized by the free-radical solution polymerization of butyl acrylate and [3-(methacryloylamino)propyl]trimethylammonium chloride in ethanol. The PSA end-use properties, repulpability in paper recycling, and the effects on the properties of recycled paper products have been studied. The cationic PSAs can be dissolved or dispersed in water if the cationic charge density in the PSA backbone is controlled, and so they do not deposit as stickies during recycling and papermaking processes. Because the PSAs are cationically charged, they can easily be removed from the papermaking system by adsorption onto the negatively charged fibers and fine surfaces. Furthermore, the adsorbed colloidal or dissolved PSAs have little effect on the final paper properties. (C) 2003 Wiley Periodicals, Inc.