Vukoje Marina, Kulčar Rahela, Itrić Ivanda Katarina, Bota Josip, Cigula Tomislav
University of Zagreb Faculty of Graphic Arts, Getaldićeva 2, 10000 Zagreb, Croatia.
Polymers (Basel). 2022 Apr 6;14(7):1484. doi: 10.3390/polym14071484.
Thermochromic (TC) printing inks change their colouration as a response to a change in temperature. This ability renders them attractive for various applications such as smart packaging, security printing, and marketing, but their application is limited due to their low UV stability, i.e., loss of their thermochromic effect when exposed to UV radiation. In order to improve the UV stability of TC prints, one offset TC printing ink was printed and coated with nanomodified polycaprolactone (PCL) coating. The coating was prepared with the incorporation of 1%, 2%, and 3% mass ratios of ZnO and TiO nanoparticles in the PCL matrix. The prepared nanocomposite coatings were applied onto the TC print and exposed to UV radiation; afterwards, they were characterized by the colour properties of prints, SEM microscopy, FTIR, and fluorescence spectroscopy. SEM microscopy, FTIR, and fluorescence spectroscopy showed higher rates of polymer degradation, and the results of colour stability indicated that 3% TiO in PCL matrix gave the best UV stability and protection of TC prints.
热致变色（TC）印刷油墨会随着温度变化而改变颜色。这种特性使其在智能包装、防伪印刷和市场营销等各种应用中颇具吸引力，但由于其紫外线稳定性较低，即在紫外线辐射下会失去热致变色效果，其应用受到限制。为了提高热致变色印刷品的紫外线稳定性，一种胶印热致变色印刷油墨被印刷并涂上了纳米改性聚己内酯（PCL）涂层。该涂层是在聚己内酯基质中加入质量比为1%、2%和3%的氧化锌和二氧化钛纳米颗粒制备而成。将制备好的纳米复合涂层应用于热致变色印刷品上并暴露于紫外线辐射下；之后，通过印刷品的颜色特性、扫描电子显微镜（SEM）、傅里叶变换红外光谱（FTIR）和荧光光谱对其进行表征。扫描电子显微镜、傅里叶变换红外光谱和荧光光谱显示出较高的聚合物降解率，颜色稳定性结果表明，聚己内酯基质中3%的二氧化钛赋予了热致变色印刷品最佳的紫外线稳定性和保护效果。
