Effects of Compatibility of Acrylic Block Copolymer and Tackifier on Phase Structure and Peel Adhesion of Their Blend

The effect of compatibility of polymer and tackifier on the adhesion properties of pressure-sensitive adhesive tape was investigated. For this purpose, a model pressure-sensitive adhesive tape was prepared. A mixture of poly(methyl methacrylate)-block-poly(butyl acrylate)-block-poly(methyl methacrylate) triblock copolymer and a similar diblock copolymer was used as the base polymer. And three kinds of tackifiers, namely a rosin phenolic resin (A), a special rosin ester resin (B) and a hydrogenated cycloaliphatic resin (C) were used. The compatibility with the base polymer was in the order of tackifier A > B > C. Transmission electron microscopy studies confirmed that the tackifier A had good compatibility, where agglomerates of the tackifier with a size of about 10 nm only were observed. Larger and distinct agglomerates of tackifier were observed for tackifier B and the size increased with the tackifier content. The tackifier C formed domains with a mean size of several tens μm. Dynamic mechanical analysis indicated that both the glass transition temperature and modulus increased at low temperature and the modulus at high temperature decreased by the addition of tackifier for tackifiers A and B. This tendency was more remarkable for tackifier A as compared to tackifier B. An increase of the glass transition temperature was never observed for tackifier C. The peel adhesion was in the order of tackifier A > B > C. It was found that the compatibility of tackifier and base polymer had strong effect on adhesion properties.