The Research of E_0 Grade Urea-Formaldehyde Resin Adhesives for Plywood

In this paper,a formula for preparing melamine modified low molar ratio UF(F/U)resin was designed,and the melamine dosage,the type and dosage of curing agent were also investigated.The research results showed that:secondary poly-condensation synthesis could effectively reduce the content of free formaldehyde and increase the solid content of the urea-formaldehyde resin,but lower the mechanical properties of the plywood bonded with the adhesive.With the increase of melamine and curing agent content,the formaldehyde emission from the plywood decreased.Under the conditions of different curing agents being respectively used,though the mechanical properties of the plywood were distinct,the fomaldehyde emission from the plywood met the requirements for E_0 grade plywood,and the bonding strength reached gradeⅡspecified in national standard.Through testing bond strength and formaldehyde emission from the plywood,it could be drawn that best properties of the plywood could be reached by using the resin NQ-J0-1(molar ratio:1,0:1 )adding 5%of curing system A.