According to the Science and Technology Daily on November 22nd, on November 16th, the research team of Professor Zhang Xiao'an, the State Key Laboratory of Supramolecular Structures and Materials, College of Chemistry, Jilin University, made breakthroughs in inkless waterjet printing, and its innovations were published again. In the journal Nature Communications. The ink-free water-jet printing technology is a technology that realizes printing by water-based ink. The core technology is printing paper, which not only helps to solve the problem that the ink-jet printing consumers face the clogging of the ink cartridges and the frequent replacement of the ink cartridges, but also helps the problem. Reduce environmental pollution and waste of resources.

The original technology is very difficult

In January 2014, "Nature Communications" magazine first reported the inkless water-jet printing technology of Professor Zhang Xiao'an's research team, which attracted high praise and wide attention from experts and scholars at home and abroad, industry peers and mainstream domestic and international media.

The ink-free water-jet printing technology has many advantages. However, since the previous water-chromic reproducible printing paper is based on a single water-chromic dye system, it is often required when a new color of reproducible paper is required. Designing and synthesizing new water-chromic dyes, followed by more complex synthetic techniques, higher costs, and longer cycles.

Among them, development of black water-chromic dyes is particularly difficult. In addition, the short retention time of the writing and the water resistance of the substrate are also technical bottlenecks restricting the practical application of the technology.

A lot of new technology benefits

In response to the bottleneck of the original technology, Zhang Xiao'an research team was inspired by the life system to subtly extend the single hydrochromic dye system into a bimolecular water synergistic color-changing system constructed by acid-chromic dyes and color developers. The agent does not develop color, and the developer and the dye react with water to display color (Fig. a). The color development of different colors can be achieved by using different color human acid color-changing dyes, which makes the color expansion of the rewritable paper simple (Fig. b).

Figure a: Mechanism intention of water-chromic rewritable paper (right) and previous work (left); Figure b: Water jet printing of different colors shows physical map

“Because most of the acid-chromic dyes and developers used have been industrially produced, they can be purchased directly, eliminating the complicated synthesis process and greatly reducing the preparation cost of water-chromic rewritable paper.” In particular, by purchasing a commercially available black dye, the long-awaited black water jet print display can be realized very simply.

The new black water-chromic reproducible paper, the black color and color purity obtained by water jet printing is very high, basically comparable to the existing black inkjet printing, the writing retention time can be several months to six months. . Of course, during this time, the information can be erased at any time by the printer's heating program.

Black water jet printing process and printing effect chart

Industrialization will not be a dream

In order to rapidly promote the industrialization process of inkless water jet printing technology and realize the marketization of products at an early date, Zhang Xiao'an research team has carried out in-depth cooperation with Lekai Medical Technology Co., Ltd. under China Aerospace Science and Technology Corporation to achieve high strength and strong water resistance. The preparation of a water-chromic rewritable paper significantly improves the paper recycling performance and enables large-scale mechanized production.

Workshop photos and black waterjet prints

In another episode, the research progress has laid a solid foundation for the completion of environmentally friendly inkless printing technology from laboratory to market. Related technologies have been declared and authorized by domestic invention patents and US invention patents.