Colorimetric changes of thermochromic ink printed on smart textile materials exposed to different heat transfer methods

Abstract

This research aims to determine the influence of heat and printing substrate type on the colorimetric properties of the thermochromic ink printed on various textile materials while subjected to heating simulating realistic conditions of usage. The results of the research can be used as a recommendations for the development of a smart temperature indicators for textile packaging. Four specific groups of textile materials were used as printing substrates and magenta leuco thermochromic water-based screen printing ink (activation temperature 31°C) in order to analize resulting colorimetric properties. Experiment based on analysis of resulting color differences confirmed that the screen thread count influences the rate of the material color change. Namely, the higher the thread count the faster the color change i.e. the sample returns faster from the discolored to the colored state. It was also confirmed that the lower the fabric weight of the material is, the sample returns faster from discolored to the colored state. In addition, this article presents a comparison of the contact and contactless method of sample heating at the same temperature. It was shown that the samples were cooled slower and consequently changed the colorimetric values after the contact method.