Mica pearlescent pigments are relatively common in our lives, but we may not be familiar with it. I will now introduce to you some factors that affect the quality of mica pearlescent pigments for your reference.
(1) Particle morphology and diameter-thickness ratio of matrix mica powder: The matrix mica powder is the carrier for stacking and coating the nano-TiO2 particle film. The particle shape and diameter-thickness ratio of the matrix mica powder have a great influence on the quality of mica pearlescent pigments. The aspect ratio of the matrix mica powder usually used to prepare the mica pearlescent pigment is required to be greater than 50.
(2) Inclusions in mica flakes: The chemical composition of natural sericite raw materials is complex, especially the chromogenic metal ion oxides such as iron, manganese, chromium, vanadium, etc., which not only directly affect the original whiteness and gloss of mica flakes , and also affects the whiteness and gloss of pearlescent pigments after chemical stacking reaction coating. Especially when making snow-white pearlescent pigments with high whiteness and gloss, this effect is more prominent, which is manifested as low whiteness of the pigment, poor gloss, grayish, yellowish or black color. If these mica flakes with a high impurity content are used to make magic and colored pearlescent pigments, the color shift of the pigment and the decrease in chroma will appear.
(3) Process elements of the coating process: For the chemical liquid phase deposition process, the process elements of the deposition coating process are closely related to the hydrolysis reaction of titanium salts, the accumulation of hydrolyzed products on the mica matrix to form a nanoparticle coating film and the growth of the film. related. In particular, factors such as pH value, temperature, stirring speed, and drug dropping speed have a great influence. In the experiment, the parameters of these elements are determined to adjust and control the process of the above-mentioned processes.
The research shows that no matter what type of mica pearlescent pigment is produced, the reaction is required to be carried out in an environment with relatively constant reaction conditions such as pH value, temperature, etc., so that the hydrolysis rate of titanium salt and the nucleation and growth rate of hydrated titanium dioxide particles are the same. It is relatively stable and harmonious with each other, so that an average lubricating and dense coating layer of titanium dioxide particles can be obtained. The rough surface of the pigment particles will diffusely reflect light in different directions. As a result, the reflected light interferes with each other and reduces the gloss. Only a smooth surface of the object can obtain light reflection in a single direction, and the parallel reflected light enhances the gloss.