Review article
https://doi.org/10.25027/agj2017.28.v28i1.119
Colorimetric description of thermochromic printing inks
Maja Jakovljević
orcid.org/0000-0002-3500-8577
; Grafički fakultet Sveučilišta u Zagrebu, Zagreb, Hrvatska
Rahela Kulčar
orcid.org/0000-0003-3599-9806
Dario Tomašegović
Mojca Friškovec
; Cetis, Graphic and Documentation Services, d.d., Čopova 24, Celje, Slovenia
Marta Klanjšek Gunde
orcid.org/0000-0001-9102-4670
; National Institute of Chemistry, Ljubljana, Hajdrihova 19, Slovenia
Abstract
The dynamic colour of three commercial reversible thermochromic inks were studied. Thermochromic print-ing inks change their colour according to a change in temperature. The two types of thermochromic inks are based on leuco dyes and liquid crystals. The thermochromic effect achieved by liquid crystals is quite different from the effect achieved with leuco dyes. Leuco dyes change from a coloured to a colourless state, or from one colour shade to another due to structural changes inside leuco dye molecules under assistance of developer. Liquid crystal inks change colour continuously throughout the spectrum, producing iridescent colours starting from red and shifting to blue part of the spectrum with temperature. The colour change results from the way light interacts with special arrangement of liquid crystal molecules to produce coloured reflection by interfer-ence, and with the variation of this structure with temperature. In this paper we will present differences between two types of thermochromic printing inks giving careful colorimetric characterization.
Keywords
Thermochromic inks; leuco dye; liquid crystals; colorimetric properties
Hrčak ID:
185220
URI
Publication date:
24.7.2017.
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