Research Of Polyvinyl Alcohol Latex Adhesive For Wood Working Cross-linking Modified By Toluene Diisocyanate

I researched chemical reaction process and performance of reactant of polyvinyl alcohol (PVA) cross-linked by toluene diisocynate (TDI) by the orthogonal matrix experimental method to make cross-linking polyvinyl alcohol adhesive whose capability of water-resistance is good. Then I added filling agent such as ethane- vinyl acetate copolymer latex (VAE) and modified amylum to concoct a kind of single component and normal temperature curing environmental wood-working adhesive whose capability of water-resistance and damp-resistance is good and cohesive strength is high.The study analyzed influence of factors such as mass fraction of polyvinyl alcohol, mass fraction of toluene diisocynate, mass fraction of FH catalyzer, reaction temperature and reaction time on the capability of water-resistance of cross-linking polyvinyl alcohol adhesive. By variance analysis I get primary and secondary relation of every factor: mass fraction of TDI→mass fraction of PVA→mass fraction of FH catalyzer→reaction temperature→reaction time. When mass fraction of PVA is 8%, mass fraction of TDI is 3‰, reaction temperature is 45℃, reaction time is 60min and mass fraction of catalyzer is 2‰, the capability of water-resistance of cross-linking polyvinyl alcohol adhesive is best and its elution rate can under 5%. From the experiment I also find that cross-linking reaction temperature has great influence on the color stability of cross-linking polyvinyl alcohol latex. When cross-linking reaction temperature above 45℃, the color stability of cross-linking polyvinyl alcohol latex becomes bad.I also analyzed and discussed the influence of adding quantity of cross-linking polyvinyl alcohol latex, synthesizing technique of cross-linking polyvinyl alcohol latex, adding quantity of ethane- vinyl acetate copolymer latex and adding quantity of modified amylum on dry and wet compression shear strength of modified polyvinyl alcohol latex adhesive. I find that when tree species is different, dry and wet compression shear strength is different obviously. The cohesive strength of the wood based materials cemented by cross-linking polyvinyl alcohol latex adhesive system can reach the cohesive strength of ordinary latex. The capability of water-resistance of cross-linking polyvinyl alcohol latex adhesive is better than polyvinyl acetate latex and its price is much lower than polyvinyl acetate latex. So cross-linking polyvinyl alcohol latex adhesive has good application foreground on wood cementation.