Method for preparing laminar alpha-Al2O3 pearlescent pigment base material by use of compound aluminum salt

Abstract

The invention discloses a method for preparing a laminar alpha-Al2O3 pearlescent pigment base material by use of compound aluminum salt. The compound aluminum salt (aluminium potassium sulfate or aluminum sodium sulfate) is selected as the aluminium source, and is hydrolyzed to produce a required fused salt in situ; under the condition of adding laminar alpha-Al2O3 seed crystals and crystal growth regulators (a titanium salt and a phosphate), a gel produced by reaction is dried and calcined at 850-1100 DEG C to prepare laminar alpha-Al2O3 with favorable properties, so that the method is simple in process. The obtained laminar alumina (0.2-0.5 [mu]m in average thickness, 11-15 [mu]m in average particle diameter, larger than 20 in diameter-to-thickness ratio and no clustering or crystal twinning) can serve as the pearlescent pigment base material.

Description

technical field [0001] The invention belongs to the field of materials, and relates to a method for preparing flake-shaped α-Al by using a composite aluminum salt 2 o 3 Method for pearlescent pigment substrates. Background technique [0002] Due to the fact that natural mica contains impurities and has an uneven diameter-thickness ratio after grinding, traditional mica titanium pearlescent pigments have defects in pearlescent properties such as color and color saturation, while artificially synthesized flake substrates (such as flake iron oxide, Flaky titanium oxide, flake aluminum oxide) have become new research hotspots for pearlescent pigment substrates due to their high refractive index. In particular, flaky α-Al 2 o 3 Due to the advantages of high melting point, high hardness, high stability, crystal morphology and controllable diameter-thickness ratio during the synthesis process, it becomes an ideal substrate for high-quality pearlescent pigments, which can be fur...

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Problems solved by technology

However, most of the methods used in the domestic invention patents involved (CN 1150165A, CN 101541681A, CN 1936114A and CN 101660204A) choose simple inorganic aluminum salts as the aluminum source, such as aluminum sulfate, and need to add a mixture of potassium sulfate and sodium sulfate as an additional Molten salt medium, one or two of titanyl sulfate, tin sulfate, zinc sulfate and sodium phosphate are crystal growth regulators, and then calcined at high temperature, the process is relatively complicated, and the prepared flaky α-Al 2 o 3 The properties are mixed, and the thin-flaky α-Al obtained by high-temperature calcination 2 o 3 The properties basically meet the conditions for the base material of pearlescent pigments, and the addition of powdered α-Al 2 o 3 α-Al obtained by calcining seeds at 700°C 2 o 3 The particle size is small and cannot be used as a base material for pearlescent pigments

To sum up, at present, flake α-Al 2 o 3 All of the preparation methods need to add a large amount of molten salt, which not only increases the cost of raw materials, but also complicates the preparation process. The calcination temperature is mostly 900-1200 ° C, and the energy consumption is high. The particle size of alumina is small, which cannot meet the requirements of being a pearlescent pigment base material

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