The Electron-Beam Curing of Dialkyltin Diacrylates

Dibutyltin diacrylate, di-2-methylpropyltin diacrylate and dioctyltin diacrylate cure to give tack-free films at much lower doses than the commonly used diluents hexanediol diacrylate, trimethylolpropane, triacrylate etc. Their reactivity is ascribed to their greater stopping power due to the presence of the tin atom and to the homolysis of the weak tin-carbon bond which leads to the production of initiating radicals. Film formation is also aided by the tin carboxylates being able to form an intermolecularly associated structure. The tin acrylates can be used in conjunction with prepolymers, e.g. an epoxidized soya bean oil (Synocure 3111) and a urethane acrylate (Synocure 3134). The tin acrylates are less effective than tripropyleneglycol diacrylate (TPGDA) in reducing the viscosity of the prepolymers. Electron beam curing of mixtures of the tin acrylates and prepolymers gave films possessing greater solvent resistance than those obtained from corresponding mixtures of TPGDA and the prepolymers.