The Research Of The Composite Modification Furan Resin Of Low Nitrogen For Foundry And Its Mechanism

Used as a foundry binder, the no-bake furan resin sand is a good process with a highstrength, a high dimensional accuracy, a fast curing speed, a high efficiency and a lowlabor intensity, but in the production of furan resin sand, there are still some problems,such as a high cost of the binder, a high percent of free formaldehyde in resin and highlevels of environmental pollution, so seriously affected the furan resin production andapplications.The synthesis of a no-bake furan resin with a high strength and a low cost wasresearched in this paper. Through the analysis of main effect factors on the strength offuran resin, a orthogonal experiment was done to optimize synthesis of urea-formaldehydefuran resin with a certain nitrogen, the key influence factors and their levels was confirmedand a high strength was obtained.Then, some active substitute materials such as glycerol, methyl alcohol, mother liquidof xylitol, polyols A agent and ethanol were used for partly substitution of furfural alcoholwhich is the main material of furan resin. Through the analysis of the above experimentresults of the substitution groups, the composite substitution was operated with glyceroland ethanol. Then a better combination of the substitute materials was got with a highstrength and the overall proportion of substitute materials is20%to the resin with a deepdecrease on the cost of raw material.Through the analysis of test data, the optimized process were obtained which showsthat urea was added by3times,21%of the total resin of furfural alcohol was added at thebasic addition reaction,6%of the total resin of ethanol was added at the earlier stage,10%of the total of resin of glycerol and4%of the total of resin of ethanol were added at thelater stage, the time of basic reaction was120min, the pH of basic reaction was9.5, thetemperature of basic reaction was85℃, the time of acid condensation reaction was75min,the temperature of acid condensation reaction was98℃, the pH of acid condensation reaction was3.8and dehydration is operate at the early stage of the reaction, the amount ofdehydration is accounted according60%of the formaldehyde added. The performance testfrom the final test on the resin is as followed: the final strength of resin sand was2.57MPa,the free formaldehyde content is0.27%, the viscosity is40mpa.s. The free formaldehydewas reduced by the composite way and the free formaldehyde content was lowed under0.1%to meet the requirement of environment.At last, the modification mechanism on furan resin was characterized and analyzed byIR. Then some process performance of the furan resin was tested by experiment.Finally, the resin with a nitrogen content≤3%, a free formaldehyde≤0.1%, a tensilestrength≥2.3MPa, a moisture≤10%can meet the requirement of casting. So the goodeconomic benefits and social significance were obtained.