Abstract
UV-curable 2,4-toluene diisocyanate (TDI) and isophorone diisocyanate (IPDI) based urethane acrylate prepolymers for secondary optical fiber coating were prepared from the two isocyanates, and two diols, poly(tetramethylene oxide) glycol (PTMG, MW=650) and hexane diol (HD), and 2-hydroxyethyl acrylate (HEA) with dibutyl tin dilaurate as a catalyst. UV-curable coating materials were formulated from the prepolymer and five different diluents and 1-hydroxy cyclohexyl phenyl ketone (Irgacure 184) as a photoinitiator. The effects of chemical structure on the refractive index of W-curable coating materials and the mechanical and dynamic mechanical properties of W-cured films were studied. The refractive index of viscose UV-curable coating material increased with increasing hard segment component (HD) content. The TDI based system has higher refractive index than that of IPDI based system at the same composition. As the content of HD increased, the Young's modulus, ultimate tensile strength, and dynamic storage modulus of UV-cured films of both TDI and IPDI based systems increased, however, the elongation at break decreased. The glass transition temperature of leV-cured films of both TDI and IPDI based systems increased as the content of HD increased.