engleski

Thermochromic printing inks for smart packaging applications

Thermochromic printing inks (TC inks) are the type of chromogenic or colour chang-ing inks that change colour under certain circumstances. The colour change in TC inks is caused by the exposure to temperature gradient. TC printing inks are one of the candidates for active and smart packaging of the future. TC inks can be used not only for security printing and brand protection, but also for marketing and novelty printing. Furthermore TC inks have great potential to be used as temperature indica-tors and heat sensitive pharmaceuticals. TC inks can be based on leuco dyes or liq-uid crystals. Leuco dye - based inks are more common, with several know applica-tions. On the other hand, liquid crystal - based inks are rather uncommon. The rea-son why liquid crystals are used less frequently than leuco dyes lies in the fact that they are both, more difficult to work with and more expensive than leuco dyes. How-ever, liquid crystals are more sensitive to temperature change than leuco dyes, meaning that they can be used in delicate experiments where small change in tem-perature has to be noted. Leuco dyes are in greater use than liquid crystals in a vari-ety of different products that require less accurate temperature readings. Communication mechanism of these inks is based on temperature dependence of the colour, occurring inside the working temperature range. They are available as water – based, solvent – based or without solvent as UV curable products, and can be produced for screen, flexo or offset printing. The possible applications of both leuco dye - and liquid crystal - based TC printing inks will be thoroughly discussed through our research, which will be presented through two separate case studies. Each study will show the potential of TC printing inks for use in active and smart packaging based on specific examples. Possible limitations as well as benefits of those inks will also be presented.

thermochromic inks; leuco dyes; liquid crystals; smart packaging

Sudjelovanje na skupu djelomično je financirano iz sredstava COST FP 1003 projekta te pomoću sredstava kratkoročne financijske potpore istraživanju Sveučilišta u Zagrebu (teme istraživanja Funkcionalne aplikacije termokromnim tiskarskim bojama, voditeljice prof. dr. sc. Branke Lozo).