Titanium And Cobalt Spinel Pigments Preparation And Performance Study

Inverse Spinel Cobalt Titanate Green pigment is an excellent Mixed Metal Oxide Pigment. It has excellent chemical resistance, outdoor durability, light fastness, heat stability and is non-bleeding and non-migratory. It have been used in a wide range of applications include RPVC, Polyolefins, Engineering Resins, Paints and Coatings including General industrial Coil and Extrusion coatings. The preparation of the pigments has been paid more attention because of the development of Mixed Metal Oxide Pigment. The pigments are usually prepared by solid state reaction required the high calcination temperature and long time. As the chemical synthesis methods Co-precipitation method and the citric acid sol-gel method is able to provide high chemical purity, precise composition, and uniform microstructure. Therefore, Co-precipitation method and the sol-gel method has been extensively employed in the preparation of many pigments.In this thesis we prepared the pigments by Co-precipitation method and the citric acid sol-gel method. Thermo gravimetric (TG-DTA) analysis, Laser particle size analyzer, X-ray diffraction(XRD), Transmission electron microscope(TEM), FT-IR and UV-vis Spectrophotometer were used to characterize pigments. The major work is summarized as follows:For Cobalt Titanate Green pigment prepared by Co-precipitation method, the effect of the species of precipitator, the species and dosage of the dispersant, raw material ratio, calcination temperature on the crystal morphology, particle size and distribution infrared absorption property, heat stability and coloring power were discussed. The results indicated that When Co:Ti=2:1, NaHCO3 is used as the precipitant, and reaction temperature is 75℃, Crystalline with Uniform morphology, bright color and Pure spinel Phase of Co2TiO4 pigments can be synthesized, with an average primary particle size around about100-200nm, after two hours'calcinations at a temperature of 1000℃.Cobalt Titanate Green pigments were also successfully prepared by the citric acid gel method using Cobalt nitrate and tetra-n-butyl titanate as Co,Ti sources, and citric acid as complexing reagent. The results indicated that single inverse spinel phase and well-crystallized Co2TiO4 pigments with particle size around 100 nm could be obtained after calcining the dried gel at 1000℃for 2h. The results show that the processes of the preparation of sol, sol to gel conversion and heating were affected by the pH value, the concentration of citric acid, water in sol, raw material ratio and the calcination temperature. Compared to the citric acid Sol-Gel method, Cobalt Titanate Green pigments prepared by Co-precipitation method have better dispersion and color performance. These two methods have better thermal stability and no obvious change of infrared absorption.In the research on the ions doping based Cobalt Titanate Green pigments by the citric acid sol-gel method, Cobalt Titanate Green pigments was modified by doping Zn2+, Ni2+ Doping different level of metal ions has some influence on the crystal structure, thermal stability, color performance and infrared absorption of Cobalt Titanate Green pigments. The researches indicated that composite Cobalt Titanate Green pigments have a spinel crystal structure and better thermal stability. And the Cobalt Titanate Green pigments with different hue were prepared by doping different metal ions. Moreover, with the doping dosage increasing, the color performance decreases under the condition of doping same metal ion.