Many industries have begun to use optical brighteners, such as paper, plastics, leather, and detergents. At the same time, fluorescent whitening agents are also used in many high-tech fields, such as fluorescence detection, dye lasers, anti-counterfeiting printing, etc., and even high-sensitivity films for high-altitude photography. In order to improve the sensitivity of photosensitive latexes, fluorescence is also used. Brightener. In China, optical brighteners were first classified as printing and dyeing auxiliary products, and then classified as dye products. Due to its unique properties and large amount of demand, it has been separated from the above two industries and has become a separate class of fine chemical products. The first largest user of domestic fluorescent whitening agents is detergents, the second largest user is paper, and textiles are the third largest user.