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Dynamic colorimetric properties of mixed thermochromic printing inks
Author(s) -
Kulčar Rahela,
Friškovec Mojca,
Gunde Marta Klanjšek,
Knešaurek Nina
Publication year - 2011
Publication title -
coloration technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 1472-3581
DOI - 10.1111/j.1478-4408.2011.00338.x
Subject(s) - thermochromism , hysteresis , materials science , inkwell , loop (graph theory) , thermal , thermal hysteresis , thermodynamics , chemistry , composite material , phase transition , condensed matter physics , organic chemistry , mathematics , physics , combinatorics
Leuco dye‐based thermochromic inks reversibly change from the coloured to the discoloured state in a defined, comparatively wide temperature region. Inside this region, the colour of a sample depends on the temperature and thermal history, which is known as the hysteresis effect. The colour of such a sample as a function of temperature has the shape of a hysteresis loop. Commercially available thermochromic inks have different loops, narrow or broad, and their shapes range from approximately symmetric to highly asymmetric. These properties are also important in mixtures of inks. The hysteresis loop of a mixture reveals its binary nature if the individual pure inks have well‐separated hysteresis. When inks with close‐separated loops, i.e. with similar activation temperatures, are mixed together, the loop of the mixture fuses together into an apparently single loop. Our research shows that some of their dynamic colour properties could be predicted in advance. However, optic and colorimetric properties of mixtures are not additive.