Study On Mica Pigments Preparation And The Mechanism

Mica pigment industry started late in China and it is at the primary stage at present, so there are many problems from substrate preparation to mica pigment products. Such as, too small diameter-thickness ratio, low classifying precision, poor pearlescent luster, bad color, poor wettability and dispersibility. It is difficult to use muscovite in China with a large number of iron to produce pigment with high purity and brilliance. The research on.new type of mica Pigments isn't enough. According to the problems above, The thesis studies the preparation of mica powder, coloring mica preparation, optically variety mica pigment, fluorescent mica powder systematically. In order to improve the quality of mica pearlescent pigment, enhance its lightness and color degree of saturation and extend the application field of mica pigments, Which has an important theoretical and practical significance to improve the utilization of resources in China and high value-added of the mica.The results and innovations of this research were as follows:(1)Using self-developed HWJM-A high pressure water jet mill for mica superfine strip, the prepared ultrafine mica powder has a diameter-thick ratio of 61.0～91.5. Together with the horizontal centrifugal classification to form a new craft of preparing mica powder in pigment level mica, being superfinely stripped and narrowly classificated. The productivity in 10～40μm is more than 90%.(2)Through the surface-modification method, strontium aluminate fluorescent mica powders are successfully prepared for the first time. Based on calculation, the cost reduces by 50% than fluorescent powder when reaching the same optical effect, and has better suspend index and covering rate. Its suspend index increases by 50%, and the covering rate increases by more than 30%. Therefore, fluorescent mica has a good application prospect.(3)The mica is colored with phthalocyanine blue by the coupling drug film method and the best craft is got. The modifier used is WD50 and the dosage of which is 8% of the heft of mica by colored in wet method. The dosage of phthalocyanine blue is 2% of the mica. The reaction last 30 minutes at 100℃,and then coloring for one and half hours. The concentration of initial slurry is 15% and the PH is 8.(4)Using urea neutralization method to produce optically variety mica pigment. After doping into Er, the saturation of products increases by 40.95%, tone angle decreases by 24.84°; after doping into Er and Nd, the saturation of products increases by 49.34%, tone angle decreases by 39.64°. The results show the color of mica pigment is more pure and brighter by doping rare-earth element. The color of mica pearlescent pigment varys from intense red, rosiness to golden yellow, then adversely from silvery white, rosiness to intense red.(5)The performance of the coloring mica and optically variety mica,such as acidity-resistant, alkali-resistance, heat- resistant, light- resistant, solvents-resistant and dispersibility are measured. It shows, coloring mica has well acidity-resistant, alkali-resistance, light- resistant, solvents-resistant and wettability.;the coloring mica produced in urea neutralization and with rare earth-doped has well acidity-resistant, alkali-resistance, light-resistant, solvents-resistant and aging-resistance, especially solvents-resistant.(6)Basing on the preparation of mica pigment, systematically analyzed and characterized mica pigment using modern testing technology, such as, Colour chromatic meter, X-ray diffraction, IR spectra, Thermogravimetric-differential thermal analysis. All properties of the blue coloring mica which made by the coupling drug film method are very steady-going. The reason of that is one functional group of WD50 in the coloring mica form to be hydrogen bond at the mica surface and then turn to be SiO-M covalent bond. The other functional group amidogen combined with the centel metal Cu atom in the phthalocyanine blue and then come into being coordinate bond. WD50 put the mica and pigment together. The results of fluorescent mica excitation spectra, emission spectrum and three-dimensional fluorescence spectra show that excitation spectra is the same as phosphors emission spectrum, fluorescent mica emission spectrum has the blue-shift. SEM analysis indicates the phosphors can uniformly distribute on the surface of mica, and the size of powder is between 50 and 1000nm.