Preparation And Application Of Environment-Friendly Starch-based Adhesive

Recently, the study of natural adhesive was developed, which is non-toxic andenvironment-friendly, to avoid formaldehyde adhesive releasing toxic gas and pollutingenvironment. This paper adopted corn starch as raw materials to prepare high performancewood adhesive and tried to improve water resistance and bonding performance to meet theapplication demand of class II plywood by a series of chemical modification means whichinclude low-molecular-weight treatment by oxidation and adding cross-linking agent toreduce the number of hydroxyl groups and introduce other active bases.The paper firstly studied the oxidization of corn starch. The oxidized starch wasprepared via the reaction of corn starch with ammonium persulfate as oxidant and wasanalyzed by infrared spectrum and X-ray diffraction. It has a moderate viscosity and carboxylcontent. The results showed that the optimal conditions of reaction correspond to aconcentration of15%(wt) for starch suspend fluid, a reacting temperature of70℃, a reactingtime of3h, a ammonium persulfate quantity of5%and a polyvinyl alcohol quantity of3%ofdry starch weight.On the base of oxidation process of corn starch, hot-pressing technologic parameter ofglued veneers by starch adhesive and starch adhesive formulations was studied. The besthot-pressing technical parameters were confirmed through observing influence factors ofhot-pressing temperature, hot-pressing pressure and hot-pressing time. The optimalhot-pressing process is: hot-pressing temperature120℃,hot-pressing pressure1.2MPa,hot-pressing time15min.Effect of the content of cross-linking agent and catalyst on bonding strength was studied.At the same time, the influnce of polyacrylate emulsion with different functional groups, glasstransition temperature and emulsion content on bonding strength were analyzed. The resultsshowed that a cross linking agent of5%of dry starch weight and a catalyst of3%of totaladhesive weight. Polyacrylate emulsion with carboxyl and epoxy composite functional groupsof which glass transition temperature is10℃was added in starch adhesive.The bonding strength of starch adhesive was best added emulsion content of30%and talcum powdercontent of one third of dry starch weight.Starch-based wood adhesive has good properties, abundant source and low cost, so it willhave a very good application in wood industry.