engleski

Stability of thermochromic printing inks

Thermochromic (TC) printing inks change their colour regarding the change in temperature. One of the most frequently used TC material in printing inks are leuco dyes. This TC composite usually consists of a colour former (leuco dye), a colour developer and a solvent, protected in polymer capsules. The colour of TC prints is dynamic, it is not just temperature dependend, but also depends on thermal history. The effect is described by colour hysteresis. Leuco dye-based TC inks are known for their short pot life, poor lightfastness and low resistivity to high temperatures and many chemicals. The effect of UV light and high temperatures on dynamic colour properties was tested. The effect was evaluated by total colour difference between fully coloured states of exposed and unexposed samples, by the total colour contrast between fully coloured and totally discoloured states of the samples and by the sample discolouration ability.

thermochromic printing inks; stability; laboratory weathering; xenon arc; lightfastness; resistance to high temperatures; total colour contrast

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