Researchers at the University of California, Riverside, in the laboratory have created a novel rewrite "paper" that is printed without ink, in the form of glass or plastic film, based on redox dyes, with three primary colors of blue, red, and green. After using it for more than 20 times, there was no significant loss in contrast and resolution. The relevant research results were published on the online version of Nature Communication on December 2.
Around 150 AD, paper was first invented by China and used for a variety of purposes, the most common being for writing and printing. In fact, the development and spread of civilization is largely due to the use of paper as a writing material. According to the survey, 90% of today's commercial information is kept on paper, although a large amount of printed paper is discarded after being used only once. And the use of traditional paper, discarded paper (and ink cartridges) is accompanied by a series of environmental problems, such as deforestation, chemical pollution of air, water and land, if the paper can be “wiped†many times. Then this situation can be changed.
According to a recent report by the Physicist Organization Network, Yin Yadong, a professor of chemistry at the university, said: "This dye forms the 'paper' imaging layer, which is achieved by using UV light to bleach the dye. Erasing 'paper' does not require additional ink printing, making it economically and environmentally viable. It represents an attractive alternative to conventional paper that meets the world's growing needs for sustainability and environmental protection."
This novel "paper" is basically a rewritable medium in the form of a glass or plastic film, the letters and patterns can be printed repeatedly, retained for several days, and then erased by simple heating. It has three primary colors: blue, red, and green, prepared by the use of commercial redox dyes methylene blue, neutral red, and acid green, including titanium dioxide nanocrystals in dyes (these act as catalysts) and thickener hydrogen cellulose. (HEC). Mixed dyes, catalysts, and HEC add high reversibility and repeatability to this "paper."
In the writing phase of "paper", the ultraviolet light reduces the dye to its colorless state. In the erasing phase, the redox dye recovers its original color, that is, the imaged material recovers its original color by reacting with oxygen in the surrounding environment. Heating it to 115 ° C usually accelerates the reaction, allowing the erase process to complete in less than 10 minutes.
The researchers said: "The text printed with this 'paper' has a high resolution, is clearly visible, and can be kept for more than three days under external environmental conditions, which is long enough in practical applications, such as reading newspapers. Even better It is simple to make, low in production cost, low in toxicity and low in energy consumption."
In order to reduce the total cost, the researchers are working hard to increase the number of such "papers" in the laboratory with a goal of recycling 100 times. And study how to extend the clarity of printed text or images for more than three days to expand its potential use, as well as the possibility of taking multi-color printing.
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