Preparation Of Adhesive Of Phenolic Resin Modified By Myrica Esculenta Extract And Its Performance

With the rapid development of economy and infrastructure,the artificial board industry is in rapid development period of China,it is playing an important role in furniture,housing and transport.Phenolic resin adhesives is the second largest demand in the man-made board industry,nevertheless,due to the shortage of oil resources and the rising price of the petrochemical downstream products,Phenolic resin adhesives,using phenol as the main synthetic raw materials,has to face many uncertain factors.In recent years,researchers around the world has been utilizing biomass pyrolysis oils,tannin,bark,lignin and other cheap renewable biomass raw materials to manufacture low-cost,high-performance and environmental-friendly phenolic resin adhesive through multivariate copolymerization.It is important to study the substitute of petrochemical raw material in the production of phenolic resin,optimize the preparation technology of the phenolic resin to improve the bonding properties of phenolic resin adhesives,which it is not only get high-performance and environmentally friendly wood-based phenolic resin adhesives,but also provide high value-added utilization way for forestry waste and improve the market competitiveness of China's timber processing industry.Therefore,it is significant to develop and apply new synthesis technology of tannin instead of phenol to modify phenolic resin.Based on the factors that influence the bonding performance,curing properties of Myrica esculenta extract tannin-phenol-formaldehyde(MET-PF)resin adhesive,the influence of the preparation process,platen curing process and curing agents on bonding performance of MET-PF resin adhesives were investigated.And the fraction section structure,curing behavior and thermal degradation performance were analyzed by Fourier Transform Infrared Spectroscopy(FTIR),Differential Scanning Calorimeter(DSC),Thermo Gravimetric Analysis(TGA)and Scanning Electron Microscope-Energy Dispersive Spectrometer(SEM-EDS).The research showed that:1.In the process of preparation of modified Myrica esculenta extract phenolic resin,the influence of P/F mole ratio,the ratio of Myrica esculenta extract replace phenol,pre-reaction temperature,pre-reaction time,co-reaction temperature,co-reaction time and addition of degradation agent(Na2SO3)on solid content,viscosity,shear strength and free formaldehyde emission of MET-PF resin adhesives were investigated.Orthogonal experiments results indicated that the optimal conditions for modified resin process of Myrica esculenta extract replace phenol ratio of 50%were as follows:P/F ratio of 1:1.3,pre-reaction temperature of 90?,pre-reaction time of 100min,co-reaction temperature of 80?,co-reaction time of 20 min and degradation agent(Na2SO3)ratio of 25%.2.In the process of platen curing process,the influence of platen temperature,platen time,the pressure and curing agent ratio on shear strength and free formaldehyde emission of MET-PF resin adhesives were investigated.The analysis of orthogonal experiments results indicated that the optimal conditions for platen curing process were as follows:platen temperature of 120?,platen time of 120min,the platen pressure of 2.5MPa and curing agent ratio of 14%.3.Curing agents had certain influences on the bonding performance of MET-PF resin adhesives.The study illustrated that when added paraformaldehyde,Mg(OH)2 and Al(OH)3 mixed in 2:1:1(w:w:w)as curing agent,the water resistance and shear strength of MET-PF resin adhesive were excellent,and the initial curing temperature of MET-PF resin adhesive was relatively suitable.4.The analysis of the FTIR indicated that hydroxymethyl would be gradually consumed in the progress of curing reaction.The curing studies conducted by DSC method revealed that curing reaction activation energy of modified resins could be effectively reduced when the level of Myrica esculenta extract replacement phenol level is no more than a 30%.And the cure kinetic data demonstrated that all the cured reaction of resins including the conventional pure PF resin and modified MET-PF resin correspond to a first-order reaction mechanism.The thermal degradation studies revealed that the thermal degradation reaction of resins gradually shifted to the low temperature when the amount of Myrica esculenta extract were increased.The SEM-EDS studies showed that the cross section of specimen which has low bond strength was neater,and the content of adhesives on cross section was relatively high.