The Preparation and Characteristics of a Blue Pearlescent Pigment with LTA-Type Ultramarine Coated on the Mica Substrate

Abstract

Ultramarine is a nontoxic and cheap inorganic pigment, which has been rarely used in blue pearlescent pigments. This work reports the synthesis of nano-ultramarine with LTA structure by calcining the polysulfide impregnated zeolite at 600∘C for 1[Formula: see text]h. Then the ultramarine colored mica composite was prepared by using [Formula: see text]-(2,3-epoxypropoxy) propytrimethoxysilane (KH-560) to attach ultramarine to the mica substrate through a covalent bond. Scanning electron microscope with energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Ultraviolet and Visible Spectrophotometry (UV-Vis) were employed to characterize the structure and properties of the ultramarine, composites as well as the intermediates. The results showed that LTA framework was retained in ultramarine during the calcination at the temperature below 700∘C. The FTIR spectra demonstrated that ultramarine was successfully modified by KH-560. The SEM, UV-Vis and [Formula: see text]*[Formula: see text]*[Formula: see text]* values revealed the increasing the amount of KH-560-modified ultramarine contributing to the formation of the dense coating layer on mica and changed the color of the ultramarine-coated mica composite. The optimum mass ratio of mica to ultramarine was 1:2 and the composite demonstrated an ideal blue pearlescent effect.