Preparation And Application Of Formaldehyde-free Soybean Protein-based Antiseptic Wood Adhesive

Formaldehyde-free soy protein-based adhesive is a green environmentally-friendly wood adhesive widely used in the production process of wood-based panels and plywood.In this paper,soy protein as the main raw material,through the addition of acid-base modification,suitable cross-linking agent and preservative,to prepare anti-corrosion soy protein adhesive with excellent bonding performance and water resistance,and apply it to three-layer birch plywood Optimize the production process of plywood.The main research carried out in this paper is as follows:The soy protein was modified by alkali solution,and the effect of the introduction of alkali on the spatial structure of soybean protein were analyzed by single factor experiment and XRD,FT-IR and SEM.The optimal conditions for the alkali-modified soybean protein were obtained:mass concentration 8.2%soy protein isolate powder 20 g,alkali amount 4%,reaction temperature 60°C,reaction time 0.5 h.At this time,the internal structure of the soy protein molecule was sufficiently opened,and the viscosity of the soy protein glue was improved.When the 30%PAE cross-linking agent was continuously added,the PAE cross-links with the protein molecules,and the soy protein film had good water resistance.Soy protein base modified gum was adjusted with acid to observe the effect of pH change on the molecular structure of modified soybean protein.It was found that when pH=7,the water absorption rate of the glue liquid decreased,the protein structure did not change,and the color of the glue liquid became light.Through experimental research,it was selected to add 0.7%of the compound preservative(copper sulfate mass:sodium tetraborate mass=3:1),4%lye,30%PAE crosslinker and adjust the solution pH=7.It was better to form the modified liquid and then add the soy protein isolate to prepare the antiseptic soy protein adhesive.At this time,the anticorrosive days of the adhesive were as long as 40 days,and it was added to the three-layer birch plywood.The dry gluing strength was 1.7 MPa and the wet gluing strength was 0.98MPa.The anti-corrosion soy protein adhesive was added to the production process of the three-layer plywood,and the plywood production process was optimized by the single factor test method.The experiment produced the best production process of plywood:coating amount of 250 g/m~2,aging time 2 h,pre-pressing time 60 min,hot pressing pressure 5 MPa,hot pressing temperature 110°C,hot pressing time 6 min.At this time,the dry bonding strength of the three-layer plywood was 1.78 MPa,and the wet bonding strength was 1.07MPa,which meeted the standards for industrial production applications.