Environmental-friendly bio-based thermosetting non-isocyanate polyurethane adhesive with enhanced bonding strength

Although Non-isocyanate polyurethane (NIPU) is a burgeoning environmental-friendly material, however, due to the water absorption capacity of NIPU, the wet bonding strength of NIPU was often not ideal when used as an adhesive in the field of wood-based panel. Amine terminated hyperbranched siloxane (HPSi), endows the material with excellent bonding properties, while combining the superiority of the rich and adjustable terminal groups of hyperbranched polymers as well as water proof properties of siloxanes. Therefore, the addition of HPSi during the synthesis of NIPU could enhance it's wet adhesive strength to a certain extent. In the study, the NIPU modified with HPSi (NIPU.Si) adhesives were synthesized from glycerol triglycidyl ether, CO 2, bio-based diamine Priamine 1074 extracted from vegetable oil, Diethylenetriamine(DETA) and Amine-terminated Hyperbranched Siloxane (HPSi) synthesized by (3-Aminopropyl)triethoxysilane(KH550) and Trimethoxyphenylsilane(PTMS) in a relatively sustainable synthesis route to improve the wet bonding strength of NIPU. The synthetic NIPU.Si(5 %) adhesive exhibits a good wet bonding strength of 1.93 MPa, representing a 34.0 % growth compared to NIPU.Si(0 %). Additionally, the synthetized NIPU.Si(5 %) adhesive shows wide applicability to different substrates, good adaptability to extreme cold temperatures, good adaptability to high temperatures aging as well as solvent resistance due to strong cohesion and high-density hydrogen bonds formed at the interface of the substrate. This study reports a new method to enhance the bonding performance of NIPU through introducing HPSi with high-density hydrogen bonds, avoids using any hazardous chemical raw materials and solvents, meets the criteria of cleaner production, further expands the application of NIPU in wood-based panel, cleaner production and other industries fields.