Study On The Antisepsis Capability And Water Resistance Of Soy Based Wood Adhesive

Soy-based wood adhesives usually have poor antisepsis capability and weakwater resistance. This research focuses on solving the problems by controllingchemical denaturalization, adding high efficient and environmental benignantiseptic and adjusting inner and surrounding conditions to prolong the conservationtime of the adhesives; by incorporating, crosslinking chemicals to import other activefunction groups, to reduce the number of hydrophilic group in adhesive system.Through these comprehensive methods, antisepsis capability and water resistance ofsoy-based wood adhesives were improved and the products could meet the GB-9848CLASS-Ⅱadhesive standards.This research can be divided into two parts: study on antisepsis capability ofsoy-based wood adhesives and study on water resistance of soy-based woodadhesives.1. Antiseptic can disturb and destroy metabolism of microbe cell, and finally killmicrobe or prevent it from breed. Because the most damaging microbe in soy-basedwood adhesives is epiphyte, this research uses BIT (1,2-benzeisotHiazoline).BaiJunqing(chlorothalonil), zinc borate, butyl p—hydroxy benzoate and sodiumBenzoate for testing, Through comparing with economic costs and antisepsis effect,we found that the BIT is much better than other antiseptic, and the optimal dosage ofBIT is 0.1% and the preserve periods could exceed two months when the pHvalue of the adhesive is near neutral and surroundings temperature is lower than30.9℃.The Box-Behnken experimented design method was used to optimize the threemain factors, influencing the soy-based wood adhesive preserve period. BITdosage,pH of adhesive and environmental temperature. SAS covariance analysissoftware was used to educe BIT dosage of 0.1%, pH of 7.64, when storagetemperature is 30.9℃, undering above condition, the storage period of soy-basedwood adhesives is more long than 2 months.2. The experimental result shows that the dosage of denaturant, the liquir ratio of denaturant solution to dry soymeal, the pH value, and concentration of crosslinkingreagent influence the shearstrength (GB-9848 classⅡstandards) of plywoodmanufactured by using soy-based wood adhesives significantly. The optimum liqiuorratio of the denaturant solution to dry soymeal is 3, determined by MagneticResonance Imaging (MRI) techniques and through single factor experiment, thedosage of denaturant and natural crosslinking reagent is 5% and 500 ppm of soymeal,respectively. The result had also been confirmed by the specific experiment.3. The result of the single factor experiment suggested that the optimal hot presstemperature is 140℃, the optimal pressure is 0.5 MPa, the optimal press time is 10Mins/3.6mm and the optimal rate of soy adhesive sub to the veneer is 300g/m~2. Acomprehensive parameters obtained through an orthogonal test are hot presstemperature of 140℃, hot press pressure of 0.5 MPa, hot press time of 10 mins, andthe rate of adhesive sub sub to the veneer of 311g/m~2. This result was furtherconfirmed by many times of specific experiment, of which the water resistent shearstrength of the plywood is between 0.95 MPa-1.12MPa.4. The mechanism of antisepsis properties and water resistance of soy-basedwood adhesives was also discussed. Adding BIT in soybased wood adhesive couldprolong the period of antisepsis, because BIT could interfere and destroy microbe cell.Adding Tannin in soybased wood adhesive could improve the water resistance,because after acid hydrolyzation Tannin could reduce its molecular weight andincrease fluidity or pliability.5.The antisepsis period of plywood manufactured by using soy basedadhesivewas observed. The period of antisepsis of plywood was tested under naturalcondition, by now plywoods have not decayed, so the antisepsis degree of plywoodwas first degree.