engleski

Chromogenic inks for packaging labels application

Chromogenic printing inks are variable inks that change color upon influences they are sensitive on: Thermochromic inks are sensitive on temperature changes ; Photochromic inks are sensitive on luminance ; Halochromic inks on pH value changes ; Biochromic inks on biochemical reactions ; Piezochromic inks on pressure influence, etc. Chromogenic inks differ not only on the cause of the color change but on the duration of the color change as well: Reversible color changes are influence-dependent in a way that the ink will regain the initial color in absence of the causative agent ; Irreversible color changes are influence-independent and permanent in the sense that once the influence factor caused the color change, the initial color cannot be regain no matter the absence of causative agent. Irreversible chromogenic inks are in use for packaging labels as Time and temperature indicators, TTI, and Freshness indicators, FI. Mostly thermochromic and biochromic inks are used, indicating the state of the packed goods, or as chromo-visual addition to the product expiring date. Despite the attractiveness of the labels and relative ease in understanding the message addressed to the consumer, TTIs and FIs did not spread as fast as might have been expected. There are some possible technological as well as communicational reasons, like un-uniformity in chromo-visual information of different indicators or insufficient distinction of color change. However, once reached the market, chromogenic indicators will overcome the drawbacks and improve to more variable labelling applications.

Chromogenic inks; Time and Temperature Indicatior; Freshness Indicators

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