What Is Fluorescent Fabric
Fluorescent dye: A dye that absorbs strongly in the visible range and radiates fluorescence. The fluorescent reflectance of the fluorescent dye on the fabric depends on the intensity of the ultraviolet light source, the amount of the fluorescent substance dyed on the fabric and the fluorescence quantum efficiency of the fluorescent substance. Different fluorescent dyes have different fluorescence quantum efficiencies and different amounts of dyeing. Generally, the dyeing concentration of fluorescent dyes is about medium color, not too deep and not too light. When the fluorescent dye solution is dilute, the fluorescence intensity is proportional to the concentration. If the concentration of the solution is too high, the fluorescent substance will have a "self-extinguishing" reaction, and the fluorescence intensity will decrease. The concentration of the solution is too small, the fluorescence is not obvious, and the brightness is not enough.
Different fabrics make fluorescent dyes exhibit different fluorescent properties. For example, when disperse fluorescent yellow 8GFF, polyester, ester fiber, and nylon show bright fluorescent yellow with green light, but when dyed with acrylic fiber, there is bright yellow light, less green light, and no fluorescence.
The pH value has an effect on the fluorescent reflectance. Generally speaking, dyeing in acidic and weakly acidic dye baths (PH value between 4-6) is beneficial to improve the fluorescent reflectance. Adding a fluorescent enhancer to the fluorescent dye helps to increase the fluorescent reflectance; when the fluorescent dye is mixed with a non-fluorescent dye, the fluorescent reflectance decreases, and the proportion of the non-fluorescent dye increases, and the fluorescent reflectance decreases rapidly.
Fluorescent pigments have heterocyclic rings in the molecular structure. Common structures such as azocyanines, xanthenes, ketones, and hemicyanines. Fluorescent dyes are mainly yellow, orange and red, such as disperse fluorescent yellow 10GN, disperse fluorescent yellow 8GFF, disperse fluorescent red G, disperse fluorescent pink BG, disperse fluorescent pink FBS, disperse fluorescent orange 2GFL, etc.
Principle of fluorescence generation:
Fluorescence is a photoluminescent phenomenon. When ultraviolet light, or some kind of light, is irradiated on a fluorescent substance, the substance will absorb energy consistent with its characteristic frequency, and transition from the ground state to a higher-energy excited state.
Molecules in an unstable excited state will transfer relaxation to the lowest vibrational energy level of the excited state in a short period of time, balance the excited state, and then fall back to the higher vibrational energy level of the ground state. During the falling process, the energy decays in the form of fluorescence, and the fluorescence disappears when the irradiation is stopped.
Fluorescent Dyes for Textiles:
1. Fluorescent whitening agent
2. Disperse fluorescent dyes
3. Fluorescent paint
Disperse fluorescent dyes have small molecules and no water-soluble groups in their structure. They are uniformly dispersed in the dyeing solution and enter the interior of the fiber with the help of a dispersant. After dipping the dyeing solution, it is dried immediately, and then heat-melted. Under the action of high temperature, the dyes deposited on the fabric can diffuse into the fiber in the form of single molecules, and the dyeing of chemical fibers can be completed in a very short time.
Due to the fusion of small fluorescent dye molecules and fibers, the color fastness to rubbing and washing is good, but the color fastness to light is poor.
