Synthesis of blocked isocyanate and study of unblocking reaction

The isocyanate terminated prepolymer was blocked with methyl ethyl ketoximel(MEKO),the effect of different blocking percentage on the prepolymer viscosity was studied.The unblocking reaction was characterized by TGA,DSC and TG-IR.Experiment results showed that when the NCO% is less than 0.1% the blocked isocyanate has good stability for overed year.The H1 NMR analysis showed that the prepolymer was successfully blocked and the unblocking temperature was 105 ℃.The blocked isocyanate was used in PET/VMCPP laminating when mixing with polyether amine,the PET/VMCPP laminate was activate at 110 ℃ for 1 hour,and the peeling strength reached 2.0 N/15mm.