Colored Paints Containing NIR-Reflective Pigments Exposed to Accelerated Ultraviolet Radiation Aging with Possible Application as Roof Coatings

Stefano Rossi,Hampus Lindmark,Michele Fedel

doi:10.3390/coatings10111135

Stefano Rossi, Hampus Lindmark + Show 1 more

Open Access

https://doi.org/10.3390/coatings10111135

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Journal: Coatings	Publication Date: Nov 23, 2020
Citations: 8	License type: CC BY 4.0

Affiliation: University of Trento, Chalmers University of Technology

Abstract

This study aims to evaluate the difference in thermal behavior among paints with the presence of traditional and NIR pigments by means of a simple and cheap laboratory-scale test. Considering these goals, the thermal and esthetical properties of two different cool coatings were assessed, highlighting their positive and limited aspects. Two different complex near-infrared inorganic reflective (NIR) pigments with yellow and black respectably colors were mixed in an acrylic waterborne copolymer binder. The paint formulations were applied on steel panels. The thermal performance of the coatings was investigated in the NIR-region of the light spectrum by exposing the samples to an IR-lamp. The outer and inner surface temperatures of the painted panels were recorded using thermocouples and an IR camera. The samples were aged by artificial UV-B light exposure. Color and specular gloss changes at different exposure times were evaluated. The behavior of the cool coatings was compared with that of conventional coatings with similar color characteristics. The black cool coating achieved a maximum temperature decrease, compared to the conventional black one, of approximately 12 °C. The stability for the cool coatings was very similar to that of the conventional coating, indicating that black pigment could be a potential candidate for cool-coating applications. The yellow cool coatings did not show a significant decrease in temperature compared to the conventional paint. The gloss and color changes resulted as influenced by the types and amount of pigments.

Highlights

Following the global increase of population, the urbanization and expansion of cities increased with unprecedented speed throughout the last century [1]
(0 h), a noticeable temperature the cool coatings, these results suggest that a significant reduction of absorbeddifference light was between achievedNIR
The characteristic peaks were similar for each spectrum, which indicated that only small traces of chemical degradation of the coatings due to exposure time to UV-B radiation were analyzed, regardless of the pigment type/load

Summary

Introduction

Following the global increase of population, the urbanization and expansion of cities increased with unprecedented speed throughout the last century [1]. Upon replacing natural material with building materials, an increase of absorbed irradiated solar light was observed in these regions, which caused a relevant rise in temperatures [3,4,5,6]. Literature studies reported that the UHI effect contributes to temperature increments that may exceed several degrees Celsius when compared to the adjacent rural environment [7]. An increase in usage of cooling devices, such as air conditioning, was observed in these areas, contributing to a rise of emission produced by fossil fuel use [8]. Previous studies showed that the UHI effect might cause severe health risks in major cities that already experience high peak temperatures during summer due to their geographical location [9]

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