The influence of printing substrate on colorimetric properties of thermochromic offset prints

Abstract

This paper investigates the colorimetric properties of reversible thermochromic offset printing ink on different paper substrates. Reversible thermochromic (TC) printing ink is printed by offset printing on four different printing substrates. Colorimetric measurements are performed by measuring diffuse reflection by determining uniform measurable physical size in the CIELAB colour space of the examined sample at temperatures ranging from 35°C to 75°C during heating and at the same temperatures up to 20°C. As the colour of the TC prints depends on the temperature, which results in colour hysteresis, it is noted that the colour hysteresis is affected by the printing substrate. The activation temperature given by the producer (63°C), is above the obtained temperatures, for print on filter paper 61,3°C, for print on synthetic paper 61,5°C, for print on bulky paper 60,9°C, with the highest deviation in the case of print on recycled paper (59,4°C). The results of total colour difference of samples measured between heating and cooling at the temperature well below the final chromic temperature and the CIEDE2000 total colour difference between the samples in the heated and cooled state as a function of temperature showed that the highest colour difference was obtained in TC print on the filter paper.