STUDY ON A COMPOSITE CATALYST FOR SILYLATED POLYURETHANE
硅烷化聚氨酯复合催化剂的研究

To obtain an environment friendly and stable silylated polyurethane/clay composite,a composite catalyst containing montmorillonite and organic bismuth compounds was developed for the preparation of polyurethane based on polypropylene glycol (PPG),toluene diisocyanate (TDI),N-butyl-γ-aminopropyl trimethoxysilane and montmorillonite via in situ polymerization.The montmorillonite can catalyze the reaction of isocyanate (NCO) and hydroxyl group (OH) effectively,and interestingly,a synergistic catalytic effect between montmorillonite and organic bismuth compound was observed in this system and verified by dibutylamine titration and online IR sptctrum measurement.Fourier transform infrared spectroscopy (FTIR) results showed that the silylated polyurethane prepolymer was successfully synthesized.In addition,the influence of the catalyst composition on the storage stability of prepolymer was evaluated with an accelerated aging method.The result indicated that all the silylated polyurethane/montmorillonite composite had relatively good storage stability.Furthermore,the montmorillonite-catalyzed silylated polyurethane prepolymers are found to be more stable than those catalyzed by organic bismuth compound,showing that the montmorillonite as a catalyst can not only catalyze the reaction between NCO and OH,but also inhibit the hydrolysis and condensation of the prepolymers,which was confirmed by using viscosity increases of these prepolymers induced with excessive miosture.Hence,our results provide a facile and effective composite catalyst for the preparation of silylated polyurethane,which holds great promise for further investigation and applications.