Preparation And Properties Of Biomass-based Resin Adhesive

The adhesive used in the wood industry is mainly composed of “trialdehyde glue”(i.e.urea-formaldehyde,phenolic-formaldehyde,melamine-formaldehyde).Ureaformaldehyde(UF)resin is vast amounts and as the most important adhesive in the wood industry due to its low cost and simple process.There has been serious formaldehyde pollution because the large use of UF resin adhesive.One the other hand,the non-renewable resources represented by petrochemical products are gradually shortageing with the development of society,so the energy problem is intensifying.It is extremely urgent to find and use renewable resources to replace petrochemical products.Aim at above problems,this thesis uses biomass as raw material to extract and prepare alkali lignin solution and furfural solution.Lignin–urea-formaldehyde(LUF)resin was prepared by lignin with low formaldehyde content;and preparation of furfural-urea-formaldehyde(FUF)resin by furfural under ultra-low formaldehyde dosage;final preparation of lignin-furfural resin without formaldehyde.The research results obtained are as follows:1.Reducing the molar ratio of formaldehyde to urea by reducing the amount of formaldehyde can effectively reduce the content of free formaldehyde in UF resin.But the bonding strength of resin adhesives will also decline rapidly.2.The problem of a decrease in the bonding strength due to a decrease in the amount of formaldehyde can be solved by lignin.The effects of different lignin additions on the properties of resin adhesives with different F/U were systematically studied.The optimum process parameters were determined: F/U=0.91:1,lignin addition amount is 20%,the bonding strength is 0.99 MPa,and the free formaldehyde content is 0.26%.3.The introduction of furfural into the reaction system solves the problem of a decrease in the bonding strength.The effect of the amount of furfural on the properties of resin adhesives was systematically studied.Combined with the actual situation in the preparation process,the optimum process parameters were determined: F/U=0.91:1,furfural addition amount is 20%,the bonding strength of the resin adhesive is 1.54 MPa,and the free formaldehyde content is 0.15%.4.Synthesis of biomass-based formaldehyde-free resin from lignin and furfural,the effects of the amount of urea,furfural and lignin modifiers on the properties of resin adhesives were systematically explored.The synthetic resin adhesive has a maximum bonding strength of 1.27 MPa,the bonding strength of resin adhesive synthesized without lignin modifier is 0.70 MPa.