Synthesis and characterization of waterborne polyurethane-based ink binder modified via a silane coupling agent

The development of high-performance waterborne polyurethane ink binder presents challenges due to the lack of outstanding water resistance, adhesion, and heat resistance in traditional waterborne polyurethane. Herein, series of waterborne polyurethane emulsions were synthesized using the pre-polymerization chain expansion and self-emulsification method, with varying contents of 3-aminopropyl triethoxysilane as the modified post-chain extender. The effect of varying the concentration of 3-aminopropyl triethoxysilane on the characteristics of waterborne polyurethane dispersions and films was investigated. The results indicated that there was a significant improvement in adhesion, thermal stability, and water resistance with an increase in the concentration of 3-aminopropyl triethoxysilane. Specifically, When the introduction amount was 3 wt%, the resulting film exhibited the best overall properties, including a tensile strength of 48.4 MPa, water absorption of 4.3 wt%, shear strength and adhesion of 3.9 MPa and 3.86 MPa respectively, as well as a T-peel strength of 14.9 N/mm. This work provided meaningful guidance for developing a novel waterborne polyurethane-based ink binder with strong adhesion, high mechanical properties, and excellent water resistance.