脲基超支化氨基树脂与柠檬酸协同改性pMDI木材胶黏剂的制备及性能OA

To address issues such as insufficient sustainability and high raw material costs of isocyanate adhesives in manufacturing of wood-based panels,while further expanding their environmental friendliness,this study used urea-based hyperbranched amino resin(UHA)and biomass-derived citric acid(CA)as composite modifiers to synergistically modify polymeric methylene diphenyl diisocyanate(pMDI)adhesives.A ternary wood adhesive(UCM)was successfully developed and applied in the production of three-layer Eucalyptus plywood.The influence of UHA addition amount on the microstructure,physical and chemical properties,chemical structure of UCM,as well as the bonding strength of UCM plywood was investigated.The results indicated that the optimal compounding process for the UCM adhesive was a UHA-CA-pMDI mass ratio of 7∶2∶1(with the pMDI content being only 10%),and the various components of the adhesive form an effective cross-linked network,enhancing the adhesive's cohesion and interface bonding strength.The optimal process conditions for preparing the glued specimens using this adhesive system are a hot-pressing temperature of 180 ℃,a hot-pressing time of 8 minutes,and a hot-pressing pressure of 1.5 MPa.Under this condition,the plywood could comply with with the standard GB/T 9846-2015"Plywood for general use".The dry strength,cold water strength(after immersion in water at 20±3 ℃ for 24 hours),hot water strength(after immersion in water at 63±3 ℃ for 3 hours),and boiling water strength(after immersion in boiling water for 3 hours)of the specimens were 1.24 MPa,1.26 MPa,1.08 MPa,and 0.92 MPa,respectively.This study effectively reduced the usage of pMDI adhesive,demonstrating excellent economic benefits and providing new ideas for the development of new low-cost adhesives.