Synthesis and Properties of Phenol-Blocked Toluene Diisocyanate Crosslinkers

Phenol, 2,4-di-t-butylphenol, and 3-methyl-4-nitrophenol blocked TDI adducts were prepared and characterized by elemental analysis and IR and 1H-NMR spectra. The dissociation temperatures were determined by the carbon dioxide evolution method and extrapolation of TG curves. It was found that the adducts based on 2,4-di-t-butylphenol and 3-methyl-4-nitrophenol dissociate at a lower temperature than the adduct based on phenol. It was also found that the 3-methyl-4-nitrophenol-blocked TDI adduct shows a low curing time compared to other adducts. The kinetic parameters are reported. The dissolution temperatures of the blocked TDI adducts were determined in four different polyols having different molecular weights.