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Whitening Principle Of Fluorescent Whitening Agent

Nov. 01, 2019

Fluorescent Brightener For Detergent, also known as optical brighteners, make white objects (such as textiles, paper, plastics, paints, etc.) whiter and more beautiful. It can turn the yellow brown pigment on fabric or other objects that cannot be removed by chemical means into white, so that the whiteness is not ideal or the yellowish object absorbs the ultraviolet light part of sunlight through the fluorescent whitening agent to emit blue fluorescence. Make corrections to get a more white visual effect. Unlike blue whitening and chemical bleaching, although blue can be whitened, one effect is limited, and the second is reduced in brightness; chemical bleaching has a destructive effect on cellulose, and the bleached object inevitably has a yellow color. However, bleaching is a necessary prerequisite for whitening. Direct bleaching without bleaching has no effect. Fluorescent whitening agents provide optical whitening while also increasing brightness or brilliance.


So what is the principle of whitening of fluorescent whitening agents? Fluorescent Brightener Agent Manufacturer will come to tell you.


Optical Brightener For Textile Dyes


Optical Brightener For Textile Dyes


Whitening principle and structural characteristics of fluorescent whitening agent:


White matter generally absorbs blue light in the visible light from 450 to 480 nm, causing blue deficiency, giving it a yellowish color and giving an old feeling. To this end, people have taken different measures to make the items whiter and brighter. The commonly used methods are: 1 plus blue whitening method. Adding blue can whiten, but the effect is limited, and the color of the item is darkened due to a reduction in the total amount of reflected light. 2 chemical bleaching method, mainly through the redox reaction to make the material fade, so it will cause some damage to cellulose, and the bleached object often has yellow, which affects the whitening effect.


Fluorescent whitening agent is an important functional additive. It is a colorless organic compound that absorbs ultraviolet light (reproduces the blue-violet fluorescence visible to the human eye and complements the yellow light on the substrate. The fluorescent whitening agent absorbs the energy of the near-ultraviolet light to make the molecule enter the excited state, and then the excited molecule transitions to the lower energy ground state and emits fluorescence. Due to the energy loss, the wavelength of the fluorescent light becomes longer. , about 450 nm blue light, the yellow color of the yellowed object can be compensated by the blue light reflected by the fluorescent whitening agent, thereby increasing the apparent whiteness of the article. Since the intensity of the emitted light exceeds the original visible light projected onto the processed object. Intensity, so it produces a whitening effect with a slight color.


Fluorescent whitening agent with practical value, in addition to absorbing ultraviolet light and emitting purple-blue fluorescence and high fluorescence efficiency, itself must be close to colorless or yellowish, with the characteristics of common dyes, for whitened substances. If the fiber has good affinity, good solubility or dispersion performance and good fastness to washing, drying and ironing, the textile textile industry mainly uses Optical Brightener For Textile Dyes.


The whitening properties of optical brighteners are determined by the particular structure of their molecules. Its chromophoric group has a conjugated system, the most common of which are benzene rings, naphthalene rings, triazine rings, vinyl groups, five-membered heterocyclic rings and other fused ring systems. An electronic system with a small degree of conjugation generally absorbs only a short wavelength of light. As the conjugated system increases, the wavelength of the absorbable light increases, and the electrons are more easily excited. The fluorescent efficiency of the whitening agent is greater, thereby satisfying Fluorescent whitening agent requirements.


The above is about the principle of whitening of fluorescent whitening agents, I hope to help everyone.