Study On The Modification And Application Of Soy-Bean Protein Adhesive

The traditional adhesive for wood, for example urea-formaldehyde resin, is not in line with current international standards for application requirements because of issues such as excessive release of formaldehyde. With the gradual strengthening of the awareness of environmental protection and the reduction of oil resources, the traditional wood adhesives soy protein go into the people's vision. Soy protein adhesive need for chemical modification because of shortcomings as low wet strength,perishable and so on.The main idea of this paper is property integrated between urea-formaldehyde and soy protein. The low-formaldehyde, water-resistant wood adhesive is acquired by blending or copolymerization between urea-formaldehyde and soy protein. The research is divided into three main methods. The first is the synthesis of urea-formaldehyde resin and soy protein blend at room temperature directly. The second is the first synthesis of methylol urea between urea and formaldehyde, and then add it into soy protein solution to be copolymerization. The third is the formaldehyde, urea, sodium dodecyl sulfate added directly into the soy protein solution. The solid content,UF content,formaldehyde content and the other core parameters on modified soy protein adhesive has be researched.The results show that under alkaline modification, solid content is 6.7%, pH value is 10, hydrolysis temperature is 60℃, the highest water intensity is 3.08MPa. The viscosity of soybean protein gel increases as the pH value increases and then decreased.The adhesive has the maximum viscosity when pH value is 8. As the temperature increases, intensity of dry and water show a decreasing trend. With the increase of pH value, dry and water strength firstly increased and then decreased.The composite modified method has the best results when the solid content is 20%, UF resin is 40%, the amount of substance ratio between formaldehyde and urea 1:1. At this method the dry strength can be achieved 10.98MPa, wet strength is not instability. The blending method has the best results when the solid content is 20%, UF resin is 40%, the ratio of the amount of substance between formaldehyde and urea is 1.5. At this method dry strength is 8MPa, wet strength is 2.78MPa. The copolymerization method has the best results as the solid content is 20%, urea formaldehyde content is 60%, the amount of substance ratio between formaldehyde and urea is 1.5. At this method dry strength is 10.8MPa, no wet strength.