Behaviour of Thermochromic Coatings under Thermal Exposure

Abstract

Interactive thermochromic coatings based on Leuco dye are most commonly used in research for building cooling applications. The coatings developed by the authors are primarily aimed at industrial applications on metal substrates, mainly for safety reasons. Thanks to a higher transition temperature associated with a significant change in shade, they have the potential to prevent burns and can be used as an element of active protection in exposed areas. Interactive thermochromic materials with different base matrices and two dispersion methods have been monitored and tested over the long term to gain an overall impression of their behaviour and applicability. The monitoring of colour characteristics helps to understand the behaviour of the thermochromic pigment in different primer matrices. The values of L*, a*, and b* and the spectral curves measured by a spectrophotometer were compared. Colour differences between the cold and heated conditions were also evaluated. ΔE* values for acrylate polyol reached up to 39. For waterborne paint, they varied according to the method of dispersion—when using a saw tooth stirrer, ΔE* was 23, and when mixing with a rotor-stator device, up to 56. Similarly, for the polyurethane matrix: ΔE* went up to 39 for stirring with a saw tooth stirrer while ΔE* was 64 for the rotor-stator. From the measurement of the behaviour of the coatings during temperature exposure, it can be concluded that most of the samples show a decrease in the transition temperature. Monitoring the behaviour of coatings during cooling is important for choosing a suitable base matrix that will ensure the long-term functionality of the coating and declare the temperature range of its use for safety applications.

Research on the Production of Pigments Based on Composite Pellets in the Recycling of Industrial Waste

“…The increase in anticorrosion properties is due to the presence of Zn, Cr, Ni, and Cu compounds in industrial wastes, which, to one degree or another, pass into the composition of the obtained pigments [15]. The development of the technology of mixed pigments allows one to rationally dispose of technogenic wastes of complex composition [16,17].…”

Transition Temperature of Color Change in Thermochromic Systems and Its Description Using Sigmoidal Models

“…There are currently two systems that are based on a change of color depending on a specific temperature. The first of these systems is liquid crystals, which have the advantage of covering a temperature range of approximately 20 • C and are typically used as contact thermometers that can be placed on different surfaces [1][2][3][4][5][6][7]. The second system is usually a three-component composite system consisting of Leuco dye, a developer, and a suitable solvent [8][9][10][11][12].…”