The Study Of Adhesive Of Diphenylmethane-4,4’-Diisocyanate Diblocked By ε-caprolactam

The isocyanate blocking technology is of great significance to further development and application of isocayanate adhesives. The blocked isocyanate adhesives that applied as rub adhesive should be unblocked under less than250℃, and the good blocking ability and good storage at room-temperature are demanded of abundant blocking agents, the e-caprolactam has special properties such as low unblocking temperature, low price and almost no pollution. So conditions of diblocking reaction between ε-caprolactam and Diphenylmethane-4,4’-Diisocyanate (MDI) was studied.Firstly, blocking reaction of MDI with ε-caprolactam were well investigated, which included the route and sequence of addition of reactants, dosage of catalyst, temperature, raw material ratio, reaction time, stirring speed and solvent. The choice of reaction conditions was based on a Latin Square design.Secondly, it also well discussed the blocking technology of crude product with sodium bisulfate and the effect of each technological paramaters on the purification reaction such as reaction temperature and solvent. The purification technology for cude product was optimized. Meanwhile the purity of the treated product and crude product was analyzed by HPLC.Thirdly, the purity of the treated product was analyzed by melting point and TLC. The structure of the treated product is identified by ESI-MS, NMR and GC-MS. The thermal decomposition temperature of the purified production was184.1℃, measured by TG-DSC. It is well proved that a good ability of storage at room temperature.Finally, imported product was successfully analyzed by FTIR, GC-MS, ESI-MS. The ingredient of imported product was recognized. Imitating foreign product has been tried.