Temperature Dependence of Tack for Polyacrylic Block Copolymer/Tackifier Blend

The effect of polymer and tackifier compatibility on tack of pressure-sensitive adhesive (PSA) tape was investigated. Poly(methyl methacrylate)-block-poly(butyl acrylate)-block-poly(methyl methacrylate) triblock copolymer was used as the base polymer and three types of tackifiers, an aliphatic petroleum resin (A), a special rosin ester resin (B), and a rosin phenolic resin (C), were mixed at 10–30 wt.%. Compatibility with the base polymer was greater in the order of C > B > A. Tackifier agglomerates of approximately 10 nm were observed by transmission electron microscopy for the PSA with tackifier C. Similar agglomerates were observed for tackifier B, but the size increased with content. The size for tackifier A was several tens of micrometers. Dynamic mechanical analysis indicated that the glass transition temperature of the poly(butyl acrylate) phase increased upon addition of tackifiers B and C. This trend was more significant for tackifier C. It was not observed for tackifier A. The temperature dependence of tack was measured using a probe tack test. Tack was greater in the order of C = B > A. Tack at higher temperatures was superior for greater tackifier C contents. Tackifier and base polymer compatibility has a strong effect on tack and its temperature dependence.