Since it is a whitening agent, it starts with the concept of "whitening" and "bleaching".
"Bleaching", my understanding is to wash your face, whether it is with facial cleanser or cleansing milk, used on the fiber is the chemical substance that is reduced or oxidized to remove the chromophoric material on the fiber. For example, the commonly used hydrogen peroxide is oxidative bleaching, while the insurance powder is a reducing bleach.
And "whitening" is a whitening cream or lotion that is applied to the face after washing the face, and the whitening on the fiber is achieved by a fluorescent whitening agent. The fluorescent whitening agent is one kind of It absorbs the invisible ultraviolet light in the light and reflects the visible blue light. It overlaps with the yellow light on the fiber to form white light, which increases the white light on the fiber and increases the whiteness of the human eye.
So is there any brightener that does not contain fluorescence?
If it does not contain fluorescence, that is, the substance cannot absorb ultraviolet light in the light and emit blue light, it is not a category of fluorescent whitening agent. So what is the whitening principle of this fluorescent-free brightener? Is it a concept of bleach replacement?
In fact, in the printing and dyeing auxiliaries market, enzyme-free scouring enzymes have been selling well for many years, and enzyme-free soaping enzymes are also used.
Some people will say that it is successful to sell, maybe!
Let's generalize the knowledge of fluorescent whitening agents:
1. The discovery of fluorescent dyes was first discovered in 1921. Lagorio found that fluorescent dyes have the ability to convert invisible ultraviolet light into visible fluorescence, and it is inferred that the whitening of natural fibers can be improved by aqueous solutions of fluorescent substances.
2. In 1929, Krais put yellowish viscose fiber in the solution of 6,7-dihydroxycoumarin glycoside, and the whiteness of viscose fiber was greatly improved.
3. Types of fluorescent whitening agents on different fibers:
Cellulose fiber: mainly stilbene, such as commonly used CBS (distyrylbiphenyl) and 33# (bistriazinylaminostilbene).
Polyester fiber: phthalimide type
Acrylic fiber: benzooxazole type, phthalimide type, pyrazoline type
Nylon: pyrazoline type
Protein fiber such as wool: pyrazoline type
4. Fluorescent whitening agents were originally classified as printing and dyeing auxiliaries in China, and later classified into the dye category (the dyes were used to color the brighteners), and then they were separately classified as a large increase in dosage. class.
5, detergent, paper, textiles are the three major users of fluorescent whitening agents.