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Why Use Fluorescent Whitening Agents In Textiles?

Nov. 08, 2019

In the textile industry, the whiteness of the fiber itself often does not meet the aesthetic requirements of people. Especially for natural fibers, the whiteness varies greatly depending on the growth environment and growth cycle. White matter generally absorbs light from 450 to 480 nm in the visible light, causing blue deficiency, giving the textile a yellowish color and giving an old feeling. To this end, people have taken different measures to whiten and brighten textiles.

Before the appearance of fluorescent whitening agents, there are two commonly used whitening methods:

1 On the blue plus white, the blue is to add blue dye to the textile. Although blue gives a feeling of whitening, since the blue dye itself absorbs part of the visible light and reduces the total amount of reflected light, the textile looks dull or dark.

2 chemical bleaching method, mainly through the redox reaction to destroy the color system on the textile, to achieve color reduction, to improve the whiteness, but will cause certain damage to cellulose, such as strength, etc., and bleached textiles often with yellow, it affects the whitening effect.

The appearance of fluorescent whitening agents compensates for the shortcomings of traditional whitening methods and shows great advantages. Fluorescent whitening agents are physical whitening agents. For example, Fluorescent Whitener For Polyester Fiber can not damage textiles, but also achieve whitening and brightening effect. The fluorescent whitening agent can absorb the near-ultraviolet light with higher energy, and the molecule enters the excited state, and then the excited molecule transitions to the lower energy ground state and emits fluorescence.

Optical Brightener For Cotton Fabric

Optical Brightener For Cotton Fabric

Due to the energy loss, the wavelength of the fluorescent light becomes longer (approximately 450 nm of blue light), and the yellow color of the yellowed textile 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 intensity of the original visible light projected onto the treated textile, a whitening effect of the slightly colored light is produced. 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 ordinary dyes, for whitened textiles. Such as fiber has good affinity, good solubility or dispersion properties and good fastness to wash, dry and hot.

The textile industry is the earliest field of application of fluorescent whitening agents and still accounts for a high proportion, accounting for about a quarter of the world's total production. 20% of domestic fluorescent whitening agents are used in the textile field, including printing whitening, dyeing whitening and brightening of light-colored fiber fabrics. Fluorescent whitening agents are popular because of their unique whitening and brightening effects on textiles. At present, no corresponding technology has been found to replace the whitening effect of fluorescent whitening agents on textile fibers. Therefore, fluorescent whitening agents play an important role in the textile industry.

Depending on the type of chemical structure, fluorescent whitening agents used in textile fibers can be divided into six categories:

(1) Ditriazine stilbene type, Optical Brightener For Cotton Fabric is suitable for cellulosic fiber and polyamide fiber (nylon, nylon) such as cotton, hemp and viscose;

(2) Dibenzoxazole type, suitable for polyamide fiber (nylon, nylon) and polyacrylonitrile fiber (acrylic fiber) and acetate fiber;

(3) Distyrene biphenyl type, suitable for cellulosic fibers such as cotton and mucilage, and protein fibers such as wool and silk, and polyamide fibers (nylon, nylon);

(4) stilbene benzene type, suitable for polyester fiber (polyester) and acetate fiber;

(5) Pyrazoline type, suitable for wool, polyamide, acrylic fiber and polyacrylonitrile fiber (acrylic fiber) and acetate fiber;

(6) Coumarin type, suitable for protein fiber such as wool and silk and polyamide fiber (nylon, nylon).

In the textile industry, different fibers use different amounts of fluorescent whitening agents, such as 42% cotton, 25% synthetic fiber, viscose, 23% cellulose acetate, and 10% wool (as a percentage of fiber). Therefore, when using fluorescent whitening agents in textiles, Lunda Chemical recommends using more reference fiber types and physical properties, and using a suitable dose of fluorescent whitening agent to obtain a satisfactory whitening effect.

The above is a description of the Optical Brightener Manufacturer's use of fluorescent whitening agents for textiles, hoping to help everyone.