Synthesis and thermal insulation properties of heat resistant near infrared reflective green composite pigments

The development of environmentally friendly green pigments with high near-infrared reflection to replace traditional chrome green pigments is one of the key areas of pigment research. This paper proposes a composite green pigment FAT 4 Z 0.5 P 0.15 using heat-resistant iron oxide hydroxide (FA) and phthalocyanine blue (CuPc) as pigments, and constructing a TiO 2 and hydrotalcites interface layer to achieve a green tone comparable to Cr 2 O 3 while enhancing the near-infrared reflectivity. The XRD and SEM test results show that components belonging to TiO 2 , hydrotalcites and CuPc have formed on the surface of FA pigment, with their crystal structures and morphological characteristics, and a multi-layer heterogeneous composite structure has been formed. The XPS test results indicate that there are interactions between the interface layers formed by each component. After the coating treatment, the heat resistance of prepared pigment has improved. The near-infrared reflectance of FAT 4 Z 0.5 P 0.15 ( L∗= 56.88, a∗= -9.91, b∗= 1.61) reaches 70.28 %, which is much higher than that of Cr 2 O 3 pigment ( L∗  = 55.34, a∗= -6.65, b∗= 3.86) at 49 %. The results of radiant heat flow reduction performance test show that the heat flux of FAT 4 Z 0.5 P 0.15 -coating and FAT 4 N 0.5 P 0.15 -coating are 21.08 W/m 2 and 22.36 W/m 2 , respectively. The composite pigment coatings can significantly reduce the temperature inside a simulated house and are expected to be used as energy-saving pigments to reduce energy consumption.