What is the whitening mechanism of the fluorescent whitening agent

In order to eliminate the yellow color tone that many products do not want, and improve the appearance of the product, there are usually three methods, chemical bleaching, blue and fluorescent white. Chemical bleaching is the oxidation of yellow substances through oxidation to fade it into white products. The disadvantage of chemical bleaching is that it has certain damage to the matrix of the bleach, such as the decreased strength of the fiber fabric after bleaching. The blue or blue -purple dyes that have a optical complementary effect on yellow substances are added to correct the yellow on the fabric and make the vision feel white. It is a blue light on the fabric by absorbing the yellow light in the spectrum, and the blue light in the reflection light can cause the visual illusion (when the blue light is more than the yellow light, the fabric seems to be white) and improves it) Black degree. In fact, this can only reduce the total amount of reflected light on the fabric, so the whiteness decreases and causes the gray degree. Therefore, the blueness does not increase the whiteness, just to meet the visual needs of people. This method often uses this method when it is bleached by fabrics. Although the vitamin of the fluorescent whitening agent is also an optical effect on objects, it can increase the total amount of light on the fabric, thereby increasing the whiteness.

A fluorescent whitening agent is an organic compound that contains a co -dual -bond and has a good flat -type special structure. Under sunlight, it can absorb the ultraviolet rays that are invisible to the naked eye in the light (wavelength is 300 ~ 400mm), which makes the molecule excite. When the base state is returned, the ultraviolet energy disappears, and then transformed into a lower energy blue purple light (wavelength wavelength (wavelength length It was launched for 420 ~ 480mm). In this way, the reflection volume of the blue -purple light on the action is increased, which offsets the yellow sensation caused by the large amount of reflection in the raw object, and has a visually white and dazzling effect. However, the vaporrian whitening agent is just a glittering color replenishment effect, and it cannot be given the true "white" of the fabric instead of chemical bleaching. If you use fluorescent whitening agents alone, you cannot get satisfactory whiteness.

Different varieties of fluorescent white -increase agents are different. This is because under the action of ultraviolet rays, the molecules of the whitening agent will gradually be destroyed. Therefore, the products that have been treated with fluorescent white agents can easily reduce the whiteness in the sun in the sun. Generally speaking, the daily exposure of polyester white agent is better. Nylon and acrylic are medium, and the wool and silk are lower. Nikko sunscreen and fluorescent effect depend on the molecular structure of fluorescent whitening agents and the properties and positions of the substituent. Increase the fluorescence effect, while the nitro and puppet nitrogen group are reduced or eliminated the fluorescent effect to increase the accuracy of the sun tolerance.

The fluorescent color of various types of fluorescent whitening agents is different. This depends on the wavelength range of its absorption of ultraviolet light and the absorption of less than 335nm, the fluorescence is reddish; the absorption of more than 365nm, the fluorescent is green, which depends on the molecular structure Instead of the nature of the base, you can add dye correction if necessary.