Our previous papers (Viková & Vik, 2005) described a unique device, now patented in the Czech Republic in the author's name, for photochromic measurement in a reflectance mode together with a methodology. This device allows photochromic sensors to test the colorimetric and spectral characteristics of photochromic textiles, and also fatigue tests for control of colour change stability. This concept of colorimetric and spectral parameters also finds the dependence of colour change on the intensity of UV irradiation and temperature. In this paper, we would like to describe the dependence of colour change on temperature for the photochromic Photopia AQ Ink system (Blue, Purple and Yellow) produced by Matsui Shikiso Chemical Co.Ltd.
It is known that the reversion of photochromic compounds from coloured to colourless is promoted thermally. The photochromic structure can achieve a lower level of saturated absorbance at higher temperatures when thermo reversible photochromic systems, such as spirooxazines and chromenes, increase the rate of thermal bleaching reaction and thus decrease light stimulated coloration.
