Preperation And Application Of Modified VAE Emulsion Wood Adhesive

To get rosin esters emulsion,rosin glycerol ester was dissolved in green solvent dimethyl carbonate,and reverse phase emulsification method at normal temperatures and pressures was used.Ethylene-vinyl acetate emulsion(VAE)was modified by rosin ester emulsion,pure diphenylmethane diisocyanate(MDI)and precipitated calcium carbonate in order to prepare one wood adhesives,which was environmental and had fine property.The following are the main research content of the preparation:Reaching the preparation processes of rosin ester emulsion.Discussing the effect of components of modified VAE emulsion on the properties of adhesive.To optimize pressing process conditions of fast-growing eucalyptus plywood,and to investigate the influence of conditions on bonding strength by using single factor and orthogonal experiments.The results are as follows:The result showed that HLB value,the types of surfactants,the amount of surfactant,mixing time,agitation speed,phase inversion water dosage,the amount of DBP and stabilizer were the main influencing factors.By experiments,the influence of these factors above on preparing rosin ester emulsion were studied.So the optimal conditions was:the HLB value of 14.5,initiator dosage of 8%,mixing time of 20 min,agitation speed of 1500 r min-1,phase inversion water dosage of 55 g,DBP dosage of 2 g,PVA dosage of 8%.In this process,the average of particles for rosin ester emulsion was 570 nm as well as its stability was good.The effects of various parameters(rosin ester,MDI,Precipitated calcium carbonate)on the bonding strength have been reported via signal and orthogonal experiments at the study of modified VAE emulsion adhesive.The results showed that the optimal condition was:the mass radio of VAE emulsion,rosin ester emulsion,MDI and precipitated calcium carbonate was 85:15:3:6.The influence extent of these factors was in following order:rosin ester emulsion weight>the amount of MDI>precipitated calcium carbonate consumption,and the effects of the dosage of rosin ester emulsion on the bonding strength of modified VAE emulsion adhesive was significant.According to DSC test,it was showing that glass transition process of modified VAE emulsion adhesive appeared in 13.78??21.23?.It indicated that modified VAE emulsion can be solidified at room temperature.The study exhibited the influence of pressing process of fast-growing eucalyptus plywood on bonding strength.According to analysis of signal and orthogonal experiments,the order of the four factors on bonding strength was hot-press pressure>glue spread>hot-press temperature>pressing time.The result that had synthetically considered the production cost,production efficiency and product quality also revealed that the optimum process was hot-press temperature of 125?,hot-press pressure of 1.0 MPa?glue spread of 280 g m-2 and hot-press time of 8 min.Under this prescription,the bonding strength of fast-growing eucalyptus plywood manufactured by modified VAE emulsion adhesive have reached 1.11 MPa,and the plywood didn't open glue after dipping 90 days at atmospheric temperature.Compared with pure VAE emulsion adhesive,modified VAE emulsion adhesive significantly improved the bonding strength,which was superior to the technique indexes of related standards,and water resistance.The rate of RMB yuan against US dollar concluded at 6.15,the price of VAE emulsion was$1,306 per ton,raw material of modified VAE emulsion cost $1,209 a ton.