Fluorescent Whitening Agents (also called optical brightener) absorb high energy
radiation in the ultraviolet to violet region (330nm-380nm) on the part of
characteristic molecules and emit lower energy radiation in blue region in
visible spectrum (400nm-450nm), which yields the counteracting the yellowing
appearance. FWA should be transparent on the substrate and should not absorb the
visible region of the spectrum. Many FWAs contain the structure of stilbene.
Stilbene is an unsaturated hydrocarbon with the formula C6H5CH=CHC6H5. Other
nucleus of FWAs are coumarin, imidazole, 1,3-diphenyl-2-pyrazolin, naphtalimid,
benzoxazole and heteroaromatics. FWAs are used in thermoplastics, detergents,
plastic films, fibers, papers, adhesives and leathers to enhance the appearance.
vinyl) dibenzoxazol is
a Fluorescent Whitening Agent specially suitable for
shaping various kinds of plastics and their products
under high temperature. It has an extra ideal whitening
effect on polyester fibers as well as polyester fiber
containing fabrics including polyester-cotton blend
fabric. This whitening agent is equivalent to Eastobrite
OB-1 made in Eastman USA.