A fluorescent whitening agent, also known as a fluorescent agent or fluorescent bleaching agent, is a fluorescent dye (white dye). Its whitening effect is achieved by using physical optical principles, that is, optical color complementation and brightening to achieve the effect of increasing visual effects. Fluorescent whitening agents have a wide range of applications, and the following are its main application areas:

Textile industry: It is the earliest application field of fluorescent whitening agents. Natural fiber and synthetic fiber fabrics still have a slight yellow color after designing and refining. Fluorescent whitening agents can neutralize yellow by absorbing ultraviolet light and emitting blue-purple fluorescence on textiles, thereby whitening the fabric; at the same time, it can use its characteristics of increasing fabric brightness to make light-colored fabrics brighter.
Papermaking industry: Papermaking whiteness is an important technical indicator of paper products, and the whiteness of pulp for producing paper products is obtained through chemical bleaching in the pulping process. For some paper products, it is sometimes necessary to add an appropriate amount of fluorescent whitening agent to improve the visual whiteness. Fluorescent whitening agents are a functional additive for the production of paper products. It can increase the visual whiteness of paper products by more than 10% based on chemical bleaching without causing chemical loss of pulp.
Plastic industry: Fluorescent brighteners can be used in the molding and processing of various plastics and plastic products, such as ABS, PS, HIPS, PA, PC, PP, EVA, and hard PVC, and can also be used for whitening polyester stock solution. Among them, fluorescent brightener OB-1 is particularly resistant to high temperatures and is mainly used for whitening by hot melt pad dyeing. It is suitable for whitening polyester fibers and whitening polyester and cotton and other fiber-blended fabrics.
Washing industry: Adding a certain variety and appropriate amount of fluorescent brighteners to detergents can improve the appearance of detergents, while also increasing the whiteness or brightness of washed fabrics, improving washing effects, making white fabrics white and bright, and light-colored fabrics bright and beautiful. Therefore, fluorescent brighteners have become one of the important additives in fabric detergent formulas.
Food industry: In addition to the obvious whitening effect, fluorescent brighteners also have certain preservation and antiseptic effects. However, it should be noted that fluorescent brighteners are not allowed to be added to food at present, but their use in food contact materials can improve the whiteness and brightness of the product, thereby reducing packaging costs.
Daily chemical industry: In my country, the regulations do not explicitly prohibit the use of fluorescent whitening agents in daily necessities and cosmetics. The appropriate amount of fluorescent whitening agents complies with the regulations.
In addition, fluorescent whitening agents can also be used in coatings, inks, leather, anti-counterfeiting, laser detection, and other fields, and even in biomedicine. Its application areas are still expanding and are closely related to people's production and life.

In general, fluorescent whitening agents play an important role in many fields, but when using them, it is also necessary to pay attention to comply with relevant regulations and standards to ensure the safety and compliance of products.