White pigments generally have a slight absorption of the blue light on the short-wave side of visible light, so they bring yellow and affect their whiteness, giving people a sense of old and unclean. One of the ways to eliminate the yellowish light of plastics is to add fluorescent brightener, which can absorb ultraviolet light with a wavelength of 300-400mm, convert the absorbed energy, and radiate 400-500mm purple or blue fluorescence, which can compensate for the absorption The blue light improves the whiteness.
Mainly series of Fluorescent brighteners as follows,
(1) Fluorescent brightener OB-1 (Similar foreign species Eastobrite OB-1)
This variety has excellent thermal stability and can withstand high temperatures of 360°C. It is one of the best heat-resistant varieties among all brightener products. Especially suitable for high melting point plastics. The whiteness is high, and the usage amount is 25-300ppm under normal circumstances.Fluorescent brightener OB-1 has low toxicity and can be used for whitening food packaging plastic products after strict control. Fluorescent brightener OB-1 is mainly used for whitening polypropylene and polyester fibers, and also used for whitening nylon, ABS, and rigid PVC.
(2) Fluorescent brightener OB (similar foreign varieties Uvitex OB) This variety is used in various plastics: PVC, PS, ABS, PE/PP, PC PET, and the usage amount is 10-50PPM, which can make polypropylene achieve higher whiteness.
(3) Fluorescent brightener FP-127 or CBS-127 (Uvitex FP-127 of the same foreign species) has a better whitening effect than the whitening agent OB. It is especially used for the whitening of PVC cable materials and should be used with caution for polyethylene plastics.
(4) Fluorescent brightener KCB This variety is mainly used for whitening EVA.