How does the optical brightener make white garment a whiter appearance?

What is optical brightener?

First of all, we must understand what is optical brightener?

The optical whitening agent itself is a kind of almost colorless dye, it can absorb the harmful ultraviolet rays in the light, part of it is converted into its own vibration energy, and the other part is converted into a visible blue Light. In this way, the clothes look whiter and brighter. In fact, it uses a visual effect.

What does optical brightener agent rely on to brighten clothes?

The optical brightener converts the harmful and invisible ultraviolet rays in the light into visible blue light, making the clothes visually brighter and whiter. The energy of ultraviolet rays is relatively high. Although part of the energy is lost during conversion, the intensity of the blue light formed is still high, which "neutralizes" the unsightly grayish yellow color and makes the fabric look brighter.

Optical brighteners do not "cover" unwashed stains like paint. Because its adsorption capacity on the fabric is too small, only at the ppm level, that is, on the order of one part per million, is not enough to "cover" stains tens of thousands of times its size. It mainly relies on the bright blue-violet light converted from ultraviolet light to achieve a visually brighter, whiter and brighter effect.

Can optical brighteners cause skin irritation or allergies?

A large amount of toxicological data shows that the optical brighteners currently used in detergents, even if the maximum dosage is 10 times or more, will not cause skin irritation or allergies and are very safe. In the early days, there was a kind of pyrazoline whitening agent used on acrylic fiber that had slight skin irritation, but it stopped production 30 years ago. It has never been used in China, and it has never been used in detergents.

What is the difference between optical brightener agent and bleaching powder?

Optical brighteners use the optical conversion principle of absorbing ultraviolet rays to emit visible blue-violet light for "physical" whitening; bleaching powder use strong chemical effects on the substrate to destroy the color structure of yellow or colored substances to achieve bleaching.