Study On Preparation Of Phenol-formaldehyde Resin Adhesive With Waste Furfural Residue

Phenol-formaldehyde resin adhesive was widely used in wood industry because it has the advantages of strong bonding strength, water-tolerant, heat-resistant, abrasion resistant and chemical stability. But its application has been limited owing to its high prime cost, dark color and highly toxic. In order to resolve these problem, in this article, a new synthesis process was established in which furfural slag of industrial waste was used as raw materials, through the strong acid hydrolysis generating available reducing sugar, the reaction of sugar instead of formaldehyde or partly replaced with phenol so that a new synthesis of phenolic resin adhesives, glucose-phenol resin adhesives, was obtained. Moreover, these technological conditions, such as using concentrated sulfuric acid to produce reducing suger, solvent extraction to separate sugar and acid, and cross-linked reaction using reducing suger and phenol, were optimized by scientific test method. The various performance of the resin adhesives were determined.First, pyrolysis thermal characteristics and kinetics of furfural residue were investigated using thermogravimetric analysis. A number of experiments with different heating rates (5-25℃/min) were performed and analyzed by thermogravimetric analysis and differential scanning calorimetry. The results showed that the non-isothermal weight-loss process of the sample is composed of dehydration, decomposing process of hemicellulose, lignin and cellulose. The kinetic parameters were calculated by means of four kinds of method, such as Flynn-Wall-Ozawa method, Friedman method, Kissinger method, and Satava-Sestak method, respectively. The dynamic parameters of non-isothermal decomposition kinetics were obtained according to the experimental data for furfural residues, and found to be anti-Jander equation of which is three dimensional diffusion,3D.The furfural residue was hydrolyzed by concentrated sulfuric acid to obtain reducing suger. The effect of various factors on the process was discussed by the orthogonal experimental design method. So the results showed that the optimum hydrolysis conditions for furfural residue with concentrated sulfuric acid were as follows:the weight ratio of pure acid to dry wood was 5:1, the soak time was 2.5h, the soak temperature was 30℃, the mass fraction of sulfuric acid was 35%, the hydrolyzing temperature was 90℃, the hydrolyzing time was 60min. The yield of reducing sugar was found to be 92.3%. The yield of redurcing sugar was obviously higher than those by diluted sulfuric acid 45%, and the reaction conditions was facile.To solve the problems of the separation of sugar and acid, and recovery of concentrated sulfuric acid, C4-C7 alcohol were used as extraction agent, the monothetic experiment method was adopted to acquire the optimization condition of acid concentration, extraction progression, oscillation time, oscillation tempreture. The optimal acid concentration was 35%, extraction progression was 3 and oscillation time and tempreture were respectively 5min and 30℃. In order to verify the accuracy of the results, precision and acid recovery experiments were adopted. Finally, the extractant was choosed n-amyl alcohol.The glucose-phenol resin adhesive was prepared successfully using D-glucose which instead of formaldehyde under the condition of alkali, and the optimum conditions of the reaction were obtained by the orthogonal experiment method. That were pH value 11, reaction temperature 120℃, the weight of the catalyst(mNH4NO3+mcuso4)11g+2.0g, the molar(nC6H12O6:nC6H6oratio) of glucose to phenol 7:1, reaction time 4h. And the viscosity of the resin adhesive was found to be 63.4mPa·s.The performance of the resin adhesive was determined such as appearance, viscosity,pH, solid content, free phenol and thermal stability,and the results showed that it can reach the level of the international phenolic resin adhesive standard. The glucose-phenol resin adhesive was conformed to the national requirements, it not only can solve the problem of raw material sources, lower production costs, reduce formaldehyde content, but also the furfural residue pollution issue can be resolved.