The color rendering and near infrared reflection properties of coated iron oxide green pigments

Abstract

In this study, a novel iron oxide green pigment (FePc), composed of phthalocyanine blue (CuPc) and iron oxide yellow pigments (FeOOH), was prepared by intermittent stirring. The FePc was coated with the hydrolysate of sodium metasilicate and silane coupling agent KH602. The structure and properties of prepared pigments were characterized by TEM, SEM, XRD, FT-IR, XPS, and TG-DTA techniques. The aspect ratio of FePc decreased compared to FeOOH. XPS analysis showed that CuPc and FeOOH were bound by hydrogen bonds. The thermal decomposition temperature of the coated pigments increased from 266 °C to 314 °C, and the color difference ΔE of pigment was 1.623 after baking at 240 °C for 30 min, indicating the prepared pigments had excellent heat resistance. The surface modification of FePc improved their hydrophobicity and dispersibility in organic media. The pigments with CuPc/FeOOH ratio of 0.2 exhibited well color properties (L* = 55.44, a* = −9.9, b* = 6.63), and green tone. The coating and surface modification had little impact on a* value. Particularly, all the newly prepared green pigments displayed high NIR reflectance. The prepared pigments have high heat resistance and dispersion properties, and are expected to be used in fields such as plastics and high-temperature coatings.