Principle of fluorescence whitening agent

In the textile industry, the whiteness of the fiber itself often does not meet people's aesthetic requirements. Especially natural fibers, because the growth environment is different from the growth cycle, its whiteness difference is very different. White substances are generally absorbed slightly in the blue light of 450 to 480nm in the visible light, causing the blue insufficiency, making it slightly yellow to give people a sense of oldness. To this end, people have taken different measures to make items white and gorgeous.

Before the fluorescent whitening agent appears, there are two main types of whitening methods:

① Add blue -increase white method, this method can play a role in explaining, but the effect is limited, and due to the decrease in the total reflection light amount, the color of the items darker.

② The chemical bleaching method is mainly to fade the substance by oxidizing the reaction, but it will cause some destruction to cellulose, and the bleaching fabrics often have yellow, which will affect the white effect.

Fluorescent whitening agents can make up for the lack of traditional white -leukering methods and show huge superiority. The fluorescent whitening agent can absorb near -ultraviolet light with higher energy, make its molecules enter the exciting state, and then jump into a low -energy base state and emit fluorescence.

Due to the loss of energy, the radiation fluorescent wavelel length (about 450nm blue light), the yellow of the yellowing item can be compensated by the blue light reflected by the fluorescent whitening agent, thereby increasing the apparent whiteness of the item. Because the intensity of the transmitted light exceeds the intensity of the original visible light projected on the fabric, it produces a slightly white white effect. A fluorescent whitening agent with practical value, in addition to absorbing ultraviolet light and emitting purple -blue fluorescent and high fluorescence efficiency, it must also be close to colorless or slightly yellow, with the characteristics of ordinary dyes. For example, fiber has good affinity, good solubility or decentralized performance, and good -tolection, sun resistance, and hotness.

The whitening characteristics of the fluorescent whitening agent are determined by the special structure of its molecules. Its hair color group has a co -pyramid system that can occur in π*jump. The most common systems are benzene, pyradic ring, triathin, ethylene, five -yuan heter ring, and other thick ring systems. The electronic system with a small degree of common levels generally only absorbs the light of short wavelengths. As the common cricket system increases, the wavelength of absorption of light increases, the more vulnerable to the electrons will be stimulated. Black requirements for fluorescent whitening agents.

Fluorescence reaction and fluorescent whitening agent

The fluorescence reaction refers to the process of being irradiated with the irradiation of the inferior light of the ultraviolet rays, and then converts the intensified energy into the process of lightly interpreted by the naked eye. This is a cold glowing phenomenon.

Fluorescent reactions are extremely common in nature, a variety of animals (such as shrimp, crab, jellyfish, etc.), food (such as soy sauce, Pu'er tea, white wine, coffee, etc.), drugs, plant extracts (such as ginkgo brass, peony, bitterness, bitterness Votoine, chlorophyll, microorganisms (bacteria, mold) can produce fluorescence reactions under ultraviolet lamps. This is natural fluorescence, which is the characteristics of material inherent and harmless.

People absorb daily absorption of substances necessary for nutrition and maintaining life, such as vitamin A, B2, B12, E, protein, hydinine, tyrosine, etc., can also produce fluorescence reactions. Normal healthy nails can also have fluorescent reactions.

The fluorescent agent can produce fluorescence reactions, but it is not only a fluorescent agent that produces fluorescent reactions. In the fluorescent lamp, the substances that appear fluorescent reactions are not all fluorescent whitening agents. It is normal for some natural ingredients such as vitamin E and glycerin to add vitamin E and glycerin to some high -quality daily chemical products. Therefore, don't see the fluorescent agent in the product as soon as you see the fluorescent reaction. In this pot, the fluorescent response is not back.

Therefore, it can only prove that there is a fluorescent reaction through purple light, but it cannot recognize whether it is a fluorescent whitening agent.