Study On Water-Resistance Of Polyvinyl Acetate Emulsion

Polyvinyl acetate emulsion has advantage of low cost, easily produced, high bondingstrength, enviromental protection but disadvantage of poor water resistance. The articlesummarized the studyies on the improving water resistance of polyvinyl acetate in and abroadrecent years. From vinylacetate monomer, emulsifier, protect colloid, analyzing the reasons ofpoor water resistance. Discussing the methods of improving the water resistance of polyvinylacetate, such as: copolymerization with vinyl acetate, addition of compounding agent,modification of protective colloid, changing the emulsifier, designing latex particle and so on.These modification improve the water resistance of polyvinyl acetate emulsion, satisfy theeconomic development, has good using foreground.Firstly, the paper studies the influence of different emulsifiers on polymerization andperformance of polyvinyl acetate emulsion. Using the normal emulsifier, amphoteric emulsifier,reactive emulsifier to vinyl acetate polymerization, contrast the performance of emulsion.Especially discuss the influence of emulsifier on particle size, water resistance and stability ofpolyvinyl acetate emulsion. The studies show that using the normal emulsifier withoutprotective colloid, the dosage of emulsifier is big and the storage stability is poor. Usingcomplex emulsifier of reactive emulsifier DNS-86 and amphoteric emulsifier DNS-628, thedosage of emulsifier is small, and the emulsion has good performance.Secondly, through a lots of experiments, eventually seleceting three monmers as modifiers.The modification which was optimized with orthogonal design, lastly gained a emulsion withexcellent water resistance. It can achieving 80℃boiling, the resin water resistance is stronglyimproved.Finally, the paper is to modify the aqueous vinyl polymer solution-isocyanate adhesive(API), by which improve its bonding strength, water- and heat resistance when bonded tohardwood. The effects of different PVA and plasticizer on API properties were investigated,respectively. After then, it evaluated the effects of some functional resins, such as MF, PF andNAM, on API bonding. It indicated that the modification with MF resin gave best performance,which was optimized with orthogonal design. During the study the Standard JIS K6806^-2003was applied with Quercus Mongolica specimens instead of Betula specimens. The APIformulation suited to hardwood bonding was obtained with good water- and heat resistance.