Development New Preparation Process Of Aluminum Tripolypho-Sphate Anticorrosive Pigment

Because chromium and Lead traditional anticorrosive pigments cause several environmental pollution problems, a lot of researches have been done on the development of non-toxic, highly effective, environmental friendly anticorrosive pigments at home and abroad. As a new anticorrosive pigment in the coatings industry, aluminum tripolyphosphate shows non-toxic, environment friendly, corrosion resistant as well as high adhesion, wide adaptability properties, widely used in railway, vehicle, chemical equipment, building industry and so on. At present, the traditional preparation process of aluminum tripolyphosphate is a long cycle, high energy consumption, the high price limit its promotion, so it has great important significance to study and develop the preparation process of aluminum tripolyphosphate.Liquid phase and solid phase method was used in this paper to study the preparation processes of aluminum tripolyphosphate, the effect of raw materials ratio, the reaction temperature, condensation temperature, condensation time, grinding time and other factors on the experimental results, the main contents and experimental results are listed as follows:(1) Liquid phase method:Aluminum tripolyphosphate was prepared in two steps. At first, Al(H2PO4)3was prepared through neutralization reaction of phosphoric acid and aluminum hydroxide, then, Al(H2PO4)3through condensation reaction to prepare aluminum tripolyphosphate. The scope and condition of the main influencing factor on the synthetic reaction was determined by single factor experiments. The effect of various reaction conditions on n(P2O5)/n(Al2O3) was studied by orthogonal experiment on the basis of single factor experiments. The optimal preparation conditions:n(H3PO4)/n(Al(OH)3)=2.5:1, the condensation temperature300℃, the temperature neutralization reaction90℃, the condensation time4hours, neutralization reaction time2hours.(2) Solid phase method:Aluminum tripolyphosphate was prepared by the reaction aluminium chloride and ammonium dihydrogen phosphate under the action of surfactant polyethylene glycol400(peg400) after grinding, washing, air pump filtration and condensation. The effect of reaction conditions on n(P2O5)/nAl2O3was studied by single factor, the optimal process conditions: n(NH4H2PO4):n(AlCl36H2O)=4:1, the temperature reaction110℃, the condensation temperature350℃, the condensation time6hours.(3) The synthetic products of two processes were analysed and characterized by X-ray diffraction, infrared spectra analysis and thermogravimetric analysis. The results showed that the two methods were successfully synthesized aluminum tripolyphosphate. the products quality indicators was in line with the requirement of anticorrosive pigment through the chemical analysis.(4) Liquid phase method generates a large number of wastewater, because of using water as solvent in the neutralization reaction; solid phase method operation is simple, it does not need solvent, so it accords with the sustainable development concept of environmental protection. Moreover, ammonium dihydrogen phosphate as a raw material in this paper, it has a wide source and low price, development a new preparation process.