Polymer-Encapsulated TiO₂ for the Improvement of NIR Reflectance and Total Solar Reflectance of Cool Coatings

Abstract

Cool coatings are solar reflective coatings and are applied on roofs, facades, and other exterior surfaces. In this work, the effect of polymer encapsulation was investigated aiming to improve near-infrared (NIR) reflectance of cool coatings. Cool coatings formulated using polymer-encapsulated TiO2 resulted in improvement (up to 10%) of NIR reflectance and, therefore, total solar reflectance in comparison to the coatings formulated using bare TiO2, especially in a high pigment volume concentration system. This is mainly due to the TiO2–TiO2 spacing and improved light scattering from the coating films. Enhanced cooling (2.5–11.2 °C) was also observed during heat buildup measurement tests conducted both in the lab under an artificial IR light source and at outdoor conditions under natural light.

Synthesis of Blue Gahnite (ZnAl2O4:Co, Nd): A Cost-Effective Method for Producing Solar-Reflective Pigments for Cool Coatings

“…The Near Infrared spectra were also obtained for the pigments applied in waterborne acrylic paint to evaluate the performance of the pigments in a coating ( Figure 7 ). The commercial paint used in this study contains the white pigment titanium dioxide, as observed in our previous work [ 35 ], which can influence the NIR reflectance of the surface coatings due to its high solar reflectivity [ 5 ]. The NIR solar reflectance curves of the coatings were calculated by ASTM standard G173-03 ( Figure 7 b).…”

“…As temperatures rise, it is essential that buildings’ energy codes and local planning include cooling-oriented design strategies, including passive and nature-based solutions, which may reduce cooling needs and prevent heat islands in expanding urban areas. Cool coatings have become superior passive cooling technologies for urban surfaces and areas [ 2 , 5 , 6 ], developed with materials with high solar reflection in the NIR region [ 2 , 7 , 8 , 9 ], which can reduce the energy consumption required for building cooling and improves the thermal comfort of urban living [ 5 ].…”

Fabrication of SiO2/Al2O3 Composite-Coated TiO2 by Pulsed Chemical Vapor Deposition and Its Applications

“…The organic layer has normally been used to improve the pigmentary property, especially for dispersibility . The improvement of infrared reflectance and visible reflectance has been observed in polymer-coated TiO 2 . , The SiO 2 /Al 2 O 3 composite film can improve the brightness and whiteness of TiO 2 pigments but accompanied by a reduced relative scattering index caused by Al 2 O 3 . In addition, TiO 2 coated with AlPO 4 and CePO 4 hybrid films shows inhibited photoactivity and excellent whiteness and brightness, but the whiteness and brightness decreased slightly with CePO 4 content above 0.5 wt % …”

Development and performance evaluation of cool black surface on thermoplastic polyolefins via incorporation of non‐near infrared absorptive pigments

“…Instead, titanium dioxide is a highly NIR reflective pigment (REF) but due to its white color it cannot be used in automotive parts because the reflecting sunlight from the window distracts the driver. [9][10][11] Therefore, a possible solution, especially for automotive industry, can be the use of cool black pigments which are colorant additives that maintain its black color by absorbing solar radiation at UV range while keeping the surface cool by reflecting or transmitting the light at NIR range. 12 These pigments can be classified among them as NIR reflective or NIR transparent according to their content, particle size or density.…”