Sep. 16, 2019
Fluorescent agent, commonly known as white dye, is a colorless or light-colored fluorescent dye that absorbs ultraviolet light and emits visible blue-violet light, resulting in a visual whitening effect. The whitening effect is to use the optical complementary color principle, so that after the yellowing substance is treated by the fluorescent whitening agent, not only the visible light but also the ultraviolet light other than visible light can be absorbed and converted into visible light having purple blue or cyan. Yellow and blue complement each other, offsetting the original yellow color of the material, making it appear white. There are many kinds of fluorescent whitening agents, mainly Fluorescent Whitening Agents For Detergents .They are also widely used in papermaking, textile and other fields, among which the paper industry has the largest amount of fluorescent whitening agents.
Optical Brightener For Paper Industry
Factors affecting the whitening effect of Optical Brightener For Paper Industry
1. Metal ion effect
The presence of metal ions in the papermaking system can adversely affect the fluorescent whitening agent, with Fe3+ having the greatest effect and producing insoluble colored materials.
2. PH effect
The whitening effect of the fluorescent whitening agent is affected by the pH of the medium, and the effect is good under medium and alkaline conditions. Therefore, the water used for papermaking or paper machine should be as close to neutral as possible, which is beneficial to increase the increase of fluorescent whitening agent. White effect.
3. Effect of retention aids and fillers
The cationic polymer produces a quenching effect on the effect of the optical brightener, thereby reducing the whitening effect of the disulfonic acid and tetrasulfonic acid fluorescent whitening agents. When using fluorescent whitening agents and retention aids, the addition position of the two should not be too close to avoid reaction. In addition, different types of fillers have different effects on fluorescent whitening agents. Commonly used fillers in papermaking are calcium carbonate, talc and kaolin. Under moderate alkaline conditions, calcium carbonate and talc have no negative effect on the fluorescent whitening agent, which will enhance the effect of the fluorescent whitening agent.
4. Effect of whiteness of puree
The higher the whiteness of the puree, the more obvious the whitening effect after adding the fluorescent whitening agent, and the brighter the color tone, when the whiteness of the original pulp is lower than 65% ISO, the fluorescent whitening agent almost loses the whitening effect.
5. Damage to paper
The cationic compound contained in the damaged paper will quench the fluorescent whitening agent, and the whitening effect of the whitening agent is greatly reduced. However, adding the fluorescent whitening agent to the primary slurry before the paper is mixed can significantly improve the whiteness. Therefore, in the production process, it is necessary to control the addition position of the damaged paper, and to ensure the stable copying of the damaged paper, so as to ensure the stability of whiteness and color tone.
6. Effect of the amount of fluorescent whitening agent
On the basis of a certain degree of whiteness, the whiteness of the pulp will increase to some extent with the increase of the amount of fluorescent whitening agent. When the amount of whitening agent reaches a certain level, the whiteness of the pulp reaches the maximum; however, continue Increasing the amount of brightener will reduce the whiteness of the pulp.
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