Application of fluorescent whitening agent:
Fluorescent whitening agent, commonly known as white dye, is an organic compound that is colorless and can emit fluorescence under ultraviolet light irradiation. It can improve the whiteness and luster of substances. The whitening effect is to use the principle of optical complementary color, so that after being treated with fluorescent whitening agents, yellowing substances can not only reflect visible light, but also absorb ultraviolet light outside of visible light and transform it into visible light with purple blue or cyan color, which is reflected out. Yellow and blue complement each other, offsetting the original yellow color of the substance and making it appear pure white.
Fluorescent whitening agents can be classified into five categories based on their chemical structure:
① Styrene type, used in industries such as cotton fibers and certain synthetic fibers, papermaking, soap making, etc., with blue fluorescence;
② Coumarin type, with a basic structure of coumarinone, used in materials such as cellulose and polyvinyl chloride plastics, with strong blue fluorescence;
③ Pyrazoline type, used for fibers such as wool, polyamide, and acrylic, with green fluorescent color;
④ Benzoxo nitrogen type, used for fibers such as acrylic and plastics such as polyvinyl chloride and polystyrene, with red fluorescence; ⑤ Phthalimide type, used for fibers such as polyester, acrylic, and nylon, with blue fluorescence.