Triethoxysilane End-Functional Branched Waterborne Polyurethane Adhesives for Leather Substrates

In order to improve the adhesion and water resistance of waterborne polyurethane (WPU) adhesive, a kind of amino-terminated hyperbranched organosilicon (HPSi-NH 2 ) was first synthesized by using trimethylchlorosilane, diethoxydimethylsilane, and γ-aminopropyltriethoxysilane (KH550) as raw materials. Then, HPSi-NH 2, as the cross-linking agent, was used to modify the polyurethane prepolymer to obtain HPSi-NH 2 -modified WPU (HSiPU). The single-factor experiment results showed that when the amount of HPSi-NH 2 was 2.0 wt %, the adhesion properties of HSiPU-2 were the best. Compared with the HSiPU-0 film, the water absorption rate of the HSiPU-2 film decreased by 10.9%, the water contact angle increased by 26.3°, the tensile strength increased by 10.1 MPa, and the elongation at break increased from 630.7 to 813.0%. HSiPU adhesive was used in the bonding of the goat leather substrate, and the results showed that the peel strength of leather bonded by HSiPU-2 was increased from 1.38 to 3.15 N/mm, and the maximum peel force was increased from 1.67 to 5.51 N/mm, which indicated that the bond strength of HSiPU adhesive with different contents of HPSi-NH 2 can be used for bonding substrates with different cohesion strengths.