The international group of researchers has developed light printing technology using an ultraviolet lamp that allows you to apply and wash the text on the same surface up to 80 times. The secret lies in a thin film of nanoparticles changing color under external exposure.
Researchers at the University of Shandun, headed by Van Show Vong, together with colleagues from the University of California and the National Laboratory of Lorens, called their technology “lighting paper”.
A coating is applied to special paper, consisting of two types of nanoparticles-Berlin Lazuri, inexpensive non-toxic blue pigment and titanium dioxide (TIO2), photocatalytic material that accelerates chemical reactions when exposed to UV radiation.
When the Berlin azure and TIO2 nanoparticles are evenly mixed and applied to paper, they give a continuous blue color together. To print the text or image, the effect of UV radiation is necessary, which excites TIO2 nanoparticles. At the same time, they give electrons “borrowed” before that from the blue nanoparticles of the Berlin Lazuri, which can change its color from blue to colorless.
In the process of printing, a combination of “blue color on a colorless background” is usually formed, since it is better perceived when reading, although it is possible and vice versa.
After printing, the document retains the image with a high resolution for 5 days, after which it slowly disappears, leaving behind the original blue background. To quickly delete the text, it is necessary to heat the paper to 120 ° C for 10 minutes.
The new technology will provide tremendous saving of natural resources throughout the paper production chain, starting from the harvesting of the forest.