Effect of the charging method of chain-transfer agent on emulsion polymerization process and pressure-sensitive adhesive properties

The preparation of three kinds of poly (n-butyl acrylate-co-acrylic acid) latexes with different charging methods of chain-transfer agent was reported, and investigations into the pressure-adhesive properties of the latexes were made. The latexes were prepared at a solid content of 50% by a two-stage sequential emulsion polymerization with the monomers n-butyl acrylate (BA) and acrylic acid (AA). Dynamic light scattering was used to monitor the particle diameters and showed that the particles grew without significant secondary nucleation occurring. The molecular parameters were characterized by gel permeation chromatography and dynamic mechanical analysis. The adhesive properties measured were loop tack force, peel strength and shear resistance according to FINAT test methods. The relationship between pressure-sensitive properties and molecular parameters, such as gel content and molecular weight, was evaluated.