Packaging added value solutions by Thermochromic Liquid Crystal-based printed labels

Abstract

Thermochromic liquid crystals (TLC) printing inks show specific, temperature dependant optical properties. The color change of TLC ink appears only inside the activation region where the color changes gradually, due to specific structural changes in the microencapsulated active thermochromic material, the TLCs. Throughout the activation region the color changes as a rainbow, i.e. the spectral color along the whole visible spectrum, the effect is called “the color play”. Temperature dependant optical properties of TLC materials enable the usage of these inks in various fields of application, including the functional packaging. Divers kinds of temperature indicators facilitate monitoring and control of the conditions of the packed goods. Still, the usage of TLC printing inks is not widely applied in the area of functional packaging, despite the expansion of application options. The paper presents a number of possible applications of TLC inks in the area of functional packaging and/or labels for added value packaging. The spectral reflections for each temperature within the activation region of the used TLC ink was acquired by spectrometric measurements. The CIELAB colorimetric values were calculated and presented, showing the “color play” throughout the whole spectra. The results of the presented measurements may contribute in defining the colorimetric parameters of dynamic color change of TLC printing inks as well as to the development of new applications in the field of functional packaging.