Rigid Waterproof Coating for Paper

Hard Waterproof Coating for Paper Aims to Reduce Plastic Dependency Regarding plastic reduction, there is considerable important research for various applications. Researchers have found, for the first time, a way to imbue relatively sustainable paper materials with some of plastic's useful properties. This can be done easily, cost-effectively and efficiently. A coating called Choetsu not only makes paper waterproof, but also preserves its flexibility and degrades safely. It is difficult to escape the fact that plastic materials are generally harmful to the environment. You have likely seen images of plastic pollution washing ashore, damaging rivers and killing countless animals. Yet, considering that plastic materials are everywhere in daily life, the problem often seems to be beyond our control. Professor Zenji Hiroi and his team from the Institute of Solid State Physics at Tokyo University are exploring ways that materials science can help, and their latest discovery aims to replace some plastic uses with something more sustainable: paper. Hiroi said, "From what I can see, the fundamental problem with plastic materials is that they do not decompose quickly and safely." "There are materials that decompose safely, like paper, but frankly paper cannot meet the wide range of uses of a plastic container. However, we found a way to give paper some of plastic's nice properties without any harm. We call this Choetsu, a low-cost, biodegradable coating that adds waterproofing and strength to plain paper." When applied to paper, Choetsu is a combination of materials that automatically form a strong and waterproof film when exposed to moisture in the air. The coating consists mostly of methyltrimethoxysilane, some isopropyl alcohol and a small amount of tetraisopropyl titanate—safe and low-cost chemicals. Paper structures, such as food containers, are sprayed with or dipped into this liquid mixture and dried at room temperature. After drying, a thin silica layer containing methyl, a type of alcohol, forms on the cellulose that makes up the paper, providing strong and waterproof properties. Additionally, reactions occurring during the coating process automatically create a layer of titanium dioxide nanoparticles. These lead to photocatalytic activity and dirt and bacteria repellent properties that protect the coated product for a long time. All chemicals in the coating gradually convert over time into harmless substances such as carbon, water and sand-like silicon. Hiroi said, "The technical challenges have been completed and some applications such as food consumption, packaging or storage could soon be implemented." "We now hope to apply this approach to other types of materials as well. The liquid composition can be adjusted for other materials, and we can create a coating that resists dirt and mold that can form on glass, ceramics and even other plastics. Together with researcher Yoko Iwamiya and the rest of my team, who have been working in this field for some time, we hope to do something truly beneficial for the world." Source:More information: Yoko Iwamiya et al, Photocatalytic Silica–Resin Coating for Environmental Protection of Paper as a Plastic Substitute, Industrial & Engineering Chemistry Research (2022). DOI: 10.1021/acs.iecr.2c00784 / Journal information: Industrial & Engineering Chemistry Research / Provided by University of Tokyo / https://phys.org/news/2022-05-paper-plastic-rigid-waterproof-coating.html