Effect of the n-butyl acrylate/2-ethylhexyl acrylate weight ratio on the performances of waterborne core-shell PSAs

A series of core-shell pressure-sensitive adhesives (PSAs) containing a poly(n-butyl-co-2-ethylhexyl acrylate) shell copolymer were synthesized via a multi-step emulsion process. The weight ratio of n-butyl acrylate (BA) to 2-ethylhexyl acrylate (2-EHA) was manipulated to vary the PSA properties. Measuring performance parameters of the resulting PSAs showed that increasing the relative amount of BA led to a decrease in the tack strength but an increase in the peel strength. In addition, the resistance of the PSAs to heat and humidity increased with increasing BA concentration. This result was correlated with the rheological and thermal properties of the PSA polymer. Finally, the dispersion stability levels of the PSAs were investigated by taking dynamic light scattering (DLS) measurements and applying the Turbiscan technique. Increasing the BA concentration in the PSA was found to lead to the formation of smaller particles and to faster fusion of the dispersed particles