Physical adsorption. In order to adsorb, it is necessary to select and physically adsorb the filler, add it to the coating system, evenly disperse it after coating grinding and other processes, and release the free formaldehyde in the absorption environment through the surface structure of the adsorbed filler coating film, and store it in the packaging. At present, the internationally popular adsorption fillers, including activated carbon, diatomite, wheat grain and other fillers, are such an adsorption principle. They are treated by special coating process to make them fully dispersed and keep adsorption function for a long time. As a natural material, diatomite is widely used in coatings. Diatomite is a kind of phytoplankton, belonging to algae. This unicellular phytoplankton can absorb silicate in water abnormally, form cell wall, and form diatomite with silicic acid as main component. This microporous structure makes diatomite have good properties of absorbing harmful gases such as formaldehyde and hygroscopic. With natural materials, green environmental protection, deeply loved by consumers. In recent years, the bamboo charcoal coating, which is also the upgraded version of activated carbon and the principle of physical adsorption, has also won the hearts of many consumers.
Compared with physical adsorption, chemical decomposition is more thorough in the treatment of formaldehyde and other harmful gases. In addition, in the form of additives, the chemical additives that can decompose formaldehyde are added to the coating system to ensure that the component can capture formaldehyde, absorb and decompose into harmless components after the coating film is formed. The principle is simple, but it's not easy to find the right additives. The additives must have good compatibility and coordination with the coating system. Secondly, other components in the coating cannot destroy the structure of the chemical decomposition additives and do not affect their normal function, which is not all the coating formulations can achieve. At present, we can find more kinds of catalyst additives, including silver ion catalyst, anion catalyst and other different catalyst materials. According to the production principle of catalyst, photocatalyst is the most suitable coating product. In particular, the reusable photocatalysis material, which can produce catalysis under the light radiation, absorb and decompose formaldehyde, has the same recyclability as plant photosynthesis, and is the most ideal additive.
If you can combine physical and chemical methods, formaldehyde removal will be better. Adsorption and decomposition complement each other, learn from each other, and the environmental protection effect will be more obvious. As one of the decoration materials for home, coating should not only consider not releasing formaldehyde, but also consider how to eliminate formaldehyde gas. Other material production, it can be said that this design idea is that functional material is designed as an air purification of coating.
In addition, I would like to talk about the research and development of zero VOC coating substrate, solvent and additive, which is a fundamental way to remove formaldehyde and other harmful substances. The international popular zero VOC design concept has two directions: one is the high solid content of the coating, no volatilization; the other is all the raw materials based on water, to eliminate the participation of organic solvents. However, due to the particularity of architectural coatings, it is impossible to use high solid coatings, which are mainly used in industry, automobile and other fields, so waterborne architectural coatings have become the development direction. From the current trend, as long as water-based technology can find a balance between performance and cost, our consumers will usher in the real water-based coating products, formaldehyde, will disappear without trace.