Waterborne polyurethane based on dual crosslinked structure with excellent mechanical properties, water and corrosion resistance

Due to the increased presence of hydrophilic groups in waterborne polyurethane (WPU) coatings, consequently leading to compromised corrosion resistance and reduced service life. To solve the problem, a series of waterborne polyurethanes were synthesized via internal emulsification using dicyclohexylmethane diisocyanate (HMDI) and polytetrahydrofuran ether diol (PTMG) as the primary raw materials. The triethanolamine (TEOA) was used as a crosslinking agent and corrosion inhibitor, while N- (β-aminoethyl) -γ-aminopropyl trimethyl-(ethyl) oxy-silane (KH-792) was introduced as a coupling agent to establish a system with a dual crosslinking structure. The crosslinking degree of the double network structure can be adjusted by changing the amount of KH-792. Then the influence of KH-792 content on the performance of SWPU dispersions and film were studied. The research shows that the waterborne polyurethane with a KH-792 content of 3 wt% exhibits exceptional mechanical strength, reaching 34.64 MPa, with only 3.32 % water absorption and an adhesion strength of 2.64 MPa. Furthermore, it exhibited a high impedance modulus (2976.4 Ω/cm²) at low frequencies. Therefore, this compound holds promising potential for application in anti-corrosion coatings field.