A photocatalytically active functional printing ink records exposure to UV light through reversible or irreversible change of colour. The change of colour can provide information necessary to protect ourselves against harmful effects of UV light and help us to indicate the sufficient amount of the received UV light in an easy and accurate way. In such inks chemically stable substances - redox inks - in contact with photocatalysts and UV light may disintegrate and change colour. We have prepared and used such a photocatalytically active functional printing ink as a simple UV indicator. Ink was formulated applying hidroxiethylcelulose , photocatalyst (nanodimensional anatase), redox dye (2,6-dichloroindophenol), glycerol, some additives and water, as a solvent. Ink mixture was applied on different substrates, such as cardboard, paper and foil, by the cube applicator. Dried samples were exposed to UV light and analyzed colorimetrically by spectrophotometer (CIELAB colour values were measured in dependence on exposure time). We found out that the pH value crucially influenced on the coluor of the samples. Additionally , the effect of amount of photocatalyst ), reducing agent (glycerol) and UV radiation on colour change of inks were observed as well.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 2005863PhD thesis contains three parts: analysis of optical properties of thermochromic (TC) printing inks, stability analysis, and colour prediction of mixtures of TC printing inks. For these purposes, 21 commercially available reversible TC inks were applied, 14 for screen printing and 7 for offset. This represents majority of currently available TC inks on the market. In the first art she have analysed the properties of temperature dependent colour of TC prints. The discoloration occurs during heating at higher temperature than re-colouration at cooling, thus the colour hysteresis exists. The colours of mixtures of TC inks were analysed. The two-inks nature is possible to detect only if the applied TC inks have well apart activation temperatures. Most analysed TC inks have poor lightfastness – they lose their majority of their dynamic colour already after 24h of UV exposure, even if the UV protection is applied. It proves that the visible light with shorter wavelengths has also important role in this process. Higher temperatures have larger effects only if temperature rises above 200 C. Poor stability against light and hogher temperatures do not have the same origin. The colour of mixtures with two TC inks and TC inks with conventional inks were predicted by two-parametric theory of Kubelka-Munk. During preparation of the corresponding database, she was comparing the size of both optical effects (scattering, absorption) for TC and conventional inks. She found that the applied theory allow to predict the colour of dynamic color of mixtures prepared by two TC inks or TC ink with conventional, but it is not reliable enough for very thick samples. The thesis contains innovative ways for description of optical properties of TC printing inks and their binary mixtures in temperature region where their colour changes. It is an important contribution to science on this area which considerably helps in understanding of temperature-dependent optical effects and enables development of new applications with temperature dependent colour effects.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 271400192International prize for contribution on international conference 3rd European Symposium on Photocatalysis, September 25 27 2013, Portorož, Slovenia untitled: Photocatalytic undoped and doped nanotitania for building applications was received Abstract of presentation A photocatalytically active functional printing ink records exposure to UV light through reversible or irreversible change of colour. The change of colour can provide information necessary to protect ourselves against harmful effects of UV light by indicating the sufficient exposure to UV light in an easy recognizable and accurate way. In such inks chemically stable substances - redox inks – are in contact with photocatalysts; illumination by UV light may disintegrate organic substances and change the ink’s colour. We have prepared and used such a photocatalytically active functional printing ink as a simple UV indicator. Ink was formulated applying hidroxiethylcelulose , photocatalyst (nanodimensional anatase), redox dye (2,6-dichloroindophenol), glycerol, some additives, and water as a solvent. The mixture was applied on cardboard, paper and foil, by the cube applicator. Dried samples were exposed to UV light and analyzed colorimetrically by spectrophotometer (CIELAB colour values were measured in dependence on exposure time). We found out that the pH value of the functional printing ink and the applied substrate crucially influenced on the coluor of the samples. Additionally, the effect of amount of photocatalyst, reducing agent (glycerol) and UV radiation on colour change of inks were observed as well. The results confirm that it is possible to prepare UV indicators applying photocatalytically active functional printing ink for
E.02 International awards
COBISS.SI-ID: 2006119