Application of fluorescent brightener

The first theoretical explanation of fluorescence was in 1852, when Stokes proposed what later became known as Stokes' law.  In 1921, Lagorio observed that the visible fluorescent energy emitted by fluorescent dyes was lower than that absorbed by visible light. For this reason, Lagorio theorized that fluorescent dyes had the ability to convert invisible ultraviolet light into visible fluorescence.  He also found that the whiteness of natural fibres could be improved by treating them with an aqueous solution of a fluorescent substance.  In 1929, Krais used Lagorio's principle to prove that the yellowing rayon was dipped into a solution of 6, 7-dihydroxy coumarin ligand. After drying, it was found that the whiteness of the rayon was significantly improved.  
The rapid development of fluorescent whitening agents has led to the emergence of reactive dyes and organic pigments DPP as one of the three major achievements in the dye field in the late 20th century.  
Fluorescent brighteners have been used in many industries, such as paper, plastics, leather, and detergents.  At the same time, fluorescent whitening agent is also used in many high-tech fields, such as fluorescence detection, dye laser, anti-counterfeiting printing, etc., and even the high-sensitivity film used for aerial photography is used to improve the sensitivity of the photographic latex, fluorescent whitening agent will also be used.  

In China, fluorescent brighteners were first classified as printing and dyeing auxiliaries, and then as dyestuff products.  Due to its unique nature and large amount of demand, it has been separated from the above two industries and become a separate kind of fine chemical products.  The largest user of fluorescent whitening agent in China is detergent, the second largest user is paper, and the third largest user is textiles.