Synthesis of polyurethane acrylate and application to ultraviolet-curable pressure-sensitive adhesive

Synthesis of polyurethane acrylates (PUA) using dimer acid-based polyester diol and hydrogenated castor oil (HCO) and preparations of the UV-curable pressure-sensitive adhesive (PSA) were reported. The effect of hydroxyl from dimer acid polyester diol/hydroxyl from HCO ratio (OHDiol/OHHCO), hydroxyl from both HCO and DAPD/2-hydroxyethyl acrylate ratio (OHPolyol/HEA), and tackifying resin/PUA ratio on the dynamic viscoelastic properties and performance of UV-cured PSA were investigated. The study revealed that, with OHDiol/OHHCO and OHPolyol/HEA increased, the storage modulus (G'), the loss modulus (G"), and complex viscosity (Eta*) of UV-cured PSA increased, and so did the corresponding holding power (HP). Peeling strength, however, decreased. As increasing the tackifying resin/PUA ratio, G', G" and Eta* decreased, and so did HP, whereas the peeling strength increased. Catalysts affected the dynamic properties and the performance of PSA. In contrast with PSA corresponding to dibutyltin dilaurate (DBTDL), the PSA corresponding to organic bismuth (OB) had higher dynamic modulus, complex viscosity, and holding power, but lower peeling strength.