Optical Brightener, are organic compounds that can absorb ultraviolet light and emit blue or blue-violet light. The national standard GB/T 6687-2006 "Terms of Dyes" defines it as follows: Optical Brighteners are colorless fluorescent dyes that can emit blue and purple light under ultraviolet light, which complement the yellow light on the substrate and have a whitening effect.
In layman's terms, Optical Brighteners use optical complementary color effects to whiten, brighten or enhance the color of white or light-colored objects (such as textiles, plastics, paper, etc.). They do not react chemically with the objects, but rely on optical effects to increase the whiteness of the objects and use fluorescence to increase the visual sense of whiteness. Therefore, Optical Brighteners are also called "optical whitening agents", "white fluorescent dyes", etc.
Optical Brighteners are substances specially created by humans to produce fluorescence. Natural substances that can emit fluorescence are not included in this list. Substances that are not intended to produce fluorescence and are not Optical Brighteners are not Optical Brighteners."
As we all know, white substances generally have a slight absorption of blue light in visible light, which causes a lack of blue to some extent, making it slightly yellow and old.
Through some method, Optical Brighteners are dyed onto substrates such as textiles, paper, plastics, detergents, etc. with a certain degree of whiteness. When exposed to sunlight or other light sources containing ultraviolet light, the Optical Brightener will absorb ultraviolet light (wavelength 300-400nm) that is invisible to the naked eye and emit bright and gorgeous blue-purple fluorescence (wavelength 420-480nm), which complements the yellow light on the substrate to obtain white light, thereby having a whitening effect on the object.
Because the Optical Brightener converts invisible ultraviolet light into visible light, it increases the intensity of the reflected light, so it makes the object look whiter and brighter.
