Study On The Synthesis、modification And Performance Of One-component Moisture-cure Polyurethane Adhesive

Polyurethane adhesive (PU) has become one of the important and indispensable materials because of the excellent overall performance and is widely used in civil, sports, aerospace, military and other fields. To improve the mechanical properties and heat resistance, polyurethane adhesive need to be modified.In this study, influences of-NCO, different polyester polyols and tackifiers on the properties of hot melt adhesive were discussed in detail. The results showed that:(1) with an increase of the mass fraction of the-NCO, the strength of the adhesive was gradually increased, but the viscosity decreased. When the-NCO content was2.5%, the adhesive had higher adhesive strength and shorter opening time.(2) Different polyols had a significant impact on the performance of the PU adhesive. PU adhesive which prepared by the polyester polyols PBA-3000had better bonding performance, but longer opening time. PU adhesive which prepared by the polyester polyol PHA-4000had higher strength and shorter opening time. With an increasing ratio of the PHA-4000. the opening time of the PU adhesive decreased, and the initial bonding strength, the final adhesive strength firstly increased and then decreased. When the ratio of PHA-4000and PBA-3000was6:4. the properties of the adhesive was better, the initial strength and the final strength of adhesive was2.02MPa,3.54MPa respectively.(3) With an increasing content of TPU, the opening time and the initial bonding strength reduced, however the final strength increased. When the content of TPU was20%, the adhesive strength was1.98MPa,3.62MPa respectively.Mixed nano-SiO2or TiO2particles with polyurethane matrix under the condition of ultrasonic and mechanical agitation. The mechanical performance, structure identification, thermal properties and morphology of PU/SiO2and PU/TiO1adhesives were analyzed by materials testing machine, thermogravimetric analyzer and scanning electron microscopy (SEM). The results showed that:-OH groups on the surface of nano-SiO2nanoparticles reacted with the-NCO groups of PU prepolymer and the SiO2/PU adhesive was obtained. Both the initial strength and the final strength were firstly increased and then decreased with an increase of nano-SiO2. reaching the maximum at the content of1.2%. the opening time significantly increased and the viscosity was gradually reduced with an increase of nano-SiO2. When the content of nano-silica particles was lower than1.2%. the dispersibility was excellent. The further increasing of Nano-TiO2would lead to deteriorate dispersed and large aggregates. The overall performance was better at the content of0.8%. The initial strength and the final strength had a31%.62%increase of respectively compared to the Pure PU adhesive. The results also showed that the melting temperature(Tm) and the decomposition temperature of1.2%nano-SiO2/PU adhesive was2.67℃and2.92℃, higher than the Pure PU adhesive. Meanwhile, the melting temperature(Tm) and the decomposition temperature of TiO2/PU adhesive with0.8%nano-TiO2particles content was2.34℃and2.51℃higher than the Pure PU adhesive.