Preparation And Properties Of Epoxy Compound Modified Soy Protein Adhesive

Traditional soy protein adhesive has low bonding strength and poor water resistance,which limit its industrial application in the production of wood-based panels.In this study,soy protein was used as the main raw material,Na OH was used as a denaturing agent,and trimethylolpropane triglycidyl ether(THPTG)was used as a crosslinking agent to prepare aldehyde-free soy protein adhesive which meet the standard conforming to the national class II plywood through the hydrolysis and cross-linking polymerization of protein molecules.Nuclear magnetic resonance(~1H-NMR),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),thermal analyzer(DSC)and other analytical methods were used to explore the effect of alkali modification and crosslinking agent on chemical structure and properties of soy protein.The main conclusions are as follows:(1)Soy protein was degraded by Na OH to obtain low molecular weight,low viscosity,high reactivity soy protein degradation solution(DSP).The most suitable treating conditions were:1.5h denaturation treatment,degradation temperature of 80?,Na OH content of 1.5%.The soy protein were degraded into chains by ordered spherical structure and dispersed in the water solution.The viscosity of DSP was 8 m Pa?s and the molecular weight was 4.643e+4.(2)THPTG can cross-link with DSP to improve the bonding strength and water resistance of soy protein adhesive.The experimental results showed that when the reaction temperature was 80?,reaction time was 50 min,THPTG adding amount was 9%,the soy adhesive has good bonding properties.The bonding strength of soy protein adhesive was 0.76 m Pa,the viscosity was 80-130 m Pa?s,and it had good fluidity on the wood surface.(3)Under alkaline conditions,THPTG was ring-opened and reacted with hydroxyl,amino and carboxyl groups and other active functional groups in soy protein to generate a cross-linked structure.(4)When single glue quantity was 244 g/m~2,hot pressing time was 1.3 min/mm,hot pressing temperature was 120?,hot pressing pressure was 0.7 MPa,the soy protein adhesive was moderate.The bonding strength of soy protein adhesive was 0.82 m Pa.