In recent years, people's awareness of environmental protection is getting higher and higher. In addition to waste sorting, paper products are playing a growing role in replacing non-biodegradable plastics. Many milk tea shops began to use paper straws, paper shopping bags and so on. While paper products are more environmentally friendly than traditional plastics, they are less usable than traditional plastics, especially when it comes to water resistance. Especially for girls, drinking milk tea, straw will soften, very inconvenient. Paper bags are also much less load-bearing than plastic ones.


In order to solve the waterproof performance of paper products mainly rely on plastic film, PE polyethylene film + paper is the most common process. However, it is difficult to separate plastic film from paper, difficult to recycle paper products, and discarded paper cups can not degrade in the environment. Therefore, in the Eu single-use plastics Directive, the single-use paper or paperboard based products with plastic coating or lining made of plastic are included in the scope of the directive and prohibited.


In a new study published Friday in the journal Industrial and Engineering Chemistry Research, Photocatalytic Silica Resin Coating for Environmental Protection of Paper as a Plastic Substitute), researchers at the University of Tokyo created a liquid compound -- called Choetsu -- that forms a durable waterproof coating when applied to paper.
"Some materials can degrade safely, such as paper, but clearly paper is not sufficient for the wide use of plastic cans," Zenji Hiroi, a professor at the University of Tokyo's Institute of Solid State Physics and co-author of the study, said in the press release. "However, we have found a way to give paper some of the good properties of plastic without causing any damage. We call it Choetsu, a low-cost biodegradable coating that adds water resistance and strength to simple paper." The substance is made up of low-cost chemicals such as isopropyl alcohol, methyltrimethoxysilane and tetraisopropyl titanate. By using a low-viscosity alkoxy silicane alkyl liquid and drying it at ambient temperatures, a silica-resin layer several microns thick is formed around the cellulose fibers of the paper. Siloxane bonded films enhance the strength of the paper while retaining its flexibility and texture, while alkyl groups (such as methyl groups) left in the voids of the film provide water resistance.


The coating is not permanent. Over time, the coating breaks down into what researchers claim are harmless elements such as carbon, water and granular silicon. As a result, coated paper can be used instead of most plastics and degrades in an environmentally sound manner after treatment.