Synthesis And Study Of Complex Metallic Oxide Pigment Of Copper Chromite Black

The copper chromite black (CuCr2O4) is a novel pigment with spinel structure which is prepared at high temperature using copper oxide and chromium oxide as raw materials. As a representative of the high performance pigment, it is the most widely used inorganic black. Because copper and chromium ions in a stable crystal lattic, presents outstanding color stability and environmental properties, and its largest applications are in thermostability paintings, engineering plastics, art prints and so on.In this paper, the copper chromite black pigment was prepared by high temperature solid phase method and chemical coprecipitation method respectively. For the high temperature solid phase method, the copper chromite black pigment with spinel structure was successfully prepared by solid phase calcinations method at high temperature using copper oxide and chromium oxide as raw materials. The crystal structure, morphology and grain size of the CuCr2O4were determined by XRD, SEM and the particle si2e analyzer respectively. The influence of processing parameters such as the mixing process, the time of ball milling, calcination temperature and time of the precursor on the crystal structure and grain size of the CuCr2O4were studied in detail, and the effect of its tinting strength was systematically discussed by adding modifiers. The results show that high energy ball milling can effectively control the grain size and homogenization of particles of the pigment and the tinting strength of pigment was greatly improved by the presence of NiO and CoO modifiers. The CuCr2O4with strong tinting strength and particle size distribution uniformity was synthesized under the condition ofball milling for10minutes and calcination at900℃for3hours.For the chemical coprecipitation method, the ultrafine copper chromite black pigment was successfully prepared using sodium dodecyl benzene sulfonate (SDBS) as a surface active agent and urea as a precipitation agent. The effect of processing parameters such as the precipitation agent, calcination temperature and surface active agent on the crystal structure, grain size and morphology of the CuCr2O4using chromium and copper nitrates as raw materials, and the effect of its tinting strength was systematically discussed. The results show that the urea and SDBS can effectively control the grain size, morphology and crystal structure of the pigment. Ultrafine CuCr2O4with a300nm in size and hexagonal structure was synthesized under the conditions of400%calculated amount of urea,5%SDBS and800℃of calcination temperature, exhibiting excellent tinting strength compared with commercial samples.Chromium ion and sulfate ion can produce basic complexes in the preparation of chromium compounds using chemical method, and the sulfate ion has counter-ion effect. According to above principles, the copper chromite black pigment was prepared using copper sulfate instead of copper nitrate as raw material, on the basic study of the NO3-system. The effects of process parameters such as the Cr3+concentration, the types and amount of surfactant on the grain size and tinting strength of copper chromite black pigment were studied. Addition of SO42-can significantly improve the agglomeration of the precursor of copper chromite black pigment, and is benefit for gaining the very loosen precursor, and then the epigranular copper chromite black pigment with excellent tinting strength was obtained.On the basis of the above experiments, the expanding tests of the copper chromite black pigment prepared by chemical coprecipitation method using chromium sulfate and chromium nitrate as raw materials were carried out, and the copper chromite black pigment with good performance was obtained.