Research On Hot-melt Polyurethane Adhesive Based On Diels-Alder Reaction

Hot-melt Polyurethane Adhes ive(HMPA) is one of the most popular adhesives in the world. In this paper, we brought a new synthesis route to prepare the non-isocyanate HMPAs which contained DA bonds. It was synthesized from a furan-terminated prepolymer and a commercial Bismaleimide(BMI). The prepolymer was obtained from Polyols and Furfurylamine(FA) through reacting with N,N’-carbonyldiimidazole(CDI). This new kind of HMPA has good adhesive properties and can be used repeatedly.1) A new kind of Hot-melt Polyester Polyurethane Adhesive(PBA-PU) contained DA bonds was prepared with Poly(1,4-butanediol adipate)(PBA) as soft segment. The structure of PCF and PBA-PU were characterized by 1H-NMR, FT-IR, DSC and TGA. The 1H-NMR and DSC test indicated the good thermal revers ibility of PBA-PU, nearly 50% of the DA bonds can regenerate in only 30 min, and this process can be repeated at least three times. The tens ile test showed the good mechanical properties of PBA-PU, the tensile strength can reach 8.64 MPa and it will increase with the hard segment ratio in a certain range. The rheology test showed that the viscosity of PBA-PU will decrease rapidly when the temperature went up, the lowest viscosity under 110℃ for 10 min was 5.2 Pa·s and 8.8 Pa·s after four cycles. The lap joint test indicated the good adhesive performance of PBA-PU, the sample PBA-PU-25 had the best shear adhesive strength, which was 7.07 MPa in the first time and 6.97 MPa after three cycles.2) A new kind of Hot-melt Polyether Polyurethane Adhesive(PTMG-PU) which contained DA bonds was prepared with polytetrahydrofuran glycol(PTMG) as the soft segment. The structure of the intermediate product PMCF and the final product PTMG-PU were characterized by 1H-NMR, FT-IR, DSC and TGA. The 1H-NMR and DSC test indicated the good thermal revers ibility of PTMG-PU, over 60% of the DA bonds can regenerate in only 30 min, and this process can be repeated at least three times. The tens ile test showed the good mechanical properties of PTMG-PU, the largest tensile strength can reach 7.59 MPa. The rheology test showed that the viscosity of PTMG-PU will decrease rapidly when the temperature went up, the lowest viscosity under 110℃ for 10 min was 3.2 Pa·s and 7.4 Pa·s after four cycles. The lap joint test indicated the good adhesive performance of PTMG-PU, the sample PTMG-PU-25 had the best shear adhesive strength, which was 6.11 MPa in the first time and 6.84 MPa after three cycles.