FLAKY Α-ALUMINA CTYSTALS WITH LARGE ASPECT RATIO AND NANO-METAL COATING PEARLESCENT PIGMENTS MANUFACTURING METHOD

摘要

The present invention relates to a manufacturing method for a flaky alpha-alumina with a high squareness ratio and a nanometal coating pearlescent pigment capable of expressing various colors and exhibiting excellent reflectivity. The manufacturing method for a pearlescent pigment according to the present invention comprises: (a) a step of manufacturing a metal precursor solution by mixing a precursor solution consisting of 3-6 wt% of a zinc precursor, 1-3 wt% of a tin precursor and a remainder of an aluminum oxide based on 100 parts by weight of an aluminum precursor: (b) a step of manufacturing a mixed gel by hydrolyzing the metal precursor solution after titrating the metal precursor solution with a sodium salt solution at a range of pH 6.0-8.0; (c) a step of aging the mixed gel at a temperature of 60-100°C for 4-30 hours; (d) a step of drying the aged mixed gel at a temperature of 60-200°C for 5-20 hours; (e) a step of manufacturing a crystallized cake by crystallizing the dried mixed gel at a temperature of 850-1,300°C for 2-10 hours; (f) a step of manufacturing an alpha-alumina crystal by dispersing the crystallized cake with 0.5-35% of a sulfuric acid solution at a temperature of 20-100°C after cooling the crystallized cake at the room temperature, and performing filtering, washing and drying on the crystallized cake; and (g) a coating layer formation step of forming a multi-stage coating layer of at least two stages on the alpha-alumina crystal.