The whitening of paper may usually be carried out in the process of papermaking, such as beating, sizing and surface coating. The method of making paper by adding optical brightening agent directly into pulp is mostly used. It is also very economical and practical to add optical brightening agent to the surface sizing liquid for paper brightening. The brightening agent tends to stay on the surface of the paper, and the whiteness of the paper is easy to adjust.
In the field of food wrapping paper, there are stricter regulations. For example, popcorn buckets, etc., must be made of food grade white cardboard. In order to reduce costs, some businesses use recycled paper production, but because the pulp quality is not up to standard, have to add a lot of optical brightening agent to achieve beautiful effect. Under UV analyzer, popcorn tubs laced with optical brightener turned a bright, harsh blue, while a qualified package made of food-grade white cardboard turned naturally milky white. Therefore, when people buy disposable paper cups and other paper food packaging, they should pay attention to the fact that the whiter the paper, the cleaner it is.
■ Detergent
Many clothes become old and yellow in the wearing process due to various reasons (including the partial loss of optical brightening agent added in the dyeing and finishing stage), such as the whiteness of white clothes decreases and colorful clothes are no longer bright. Although the cleaning products play the role of decontamination is surfactants and aid, optical brightening agent itself does not decontamination function. However, under the same decontamination function, the clothes will appear brighter after washing with appropriate optical brightening agent detergent.
■ Textiles
Optical brightening agent has been used in textile fiber field for nearly 70 years. Fiber is divided into cellulose fiber, protein fiber and synthetic fiber three categories, so in the use of optical brightening agent, we must first understand the chemical composition and physical properties of the fiber, in order to choose the appropriate optical brightening agent. optical brightener used in textile fiber industry should meet multiple conditions, such as no damage to fiber, and have good affinity with it; With good water solubility; Have good chemical stability; Have better uniform whitening, etc.
■ Other
With the rapid development of plastic industry, people's requirements on the appearance of plastic products are constantly improving, so the use of optical brightener to improve the appearance of plastic products has been paid more and more attention. In addition, optical brightening agents are also used in pearl brightening, paint, leather and other fields.