EFFECT OF ULTRAVIOLET ABSORBING AGENTS ON PHOTODEGRADATION BEHAVIOR OF A DISPERSE DYE

The action and effect of ultraviolet absorbing agents (UVA) on the pho tofading of dyed fiber, in particular polyester, were investigated usi ng a monochromatic light source, Polyester fiber itself and the dyed f iber were affected markedly by spectroirradiation at a specific wavele ngth, viz, 316 nm: yellowing of the fiber alone and photofading of C.I . Disperse Red 73 on the fiber occurred maximally at this wavelength. UVAs of the benzotriazole and phenyl salicylate types, which show abso rption spectra around 316 nm, protected the decomposition of polyester at 316 nm irradiation, and hence the photodegradation of the dye on t he fiber. Diacetate and triacetate fibers were decomposed maximally by irradiation at 230 nm and 259 nm, respectively. These wavelengths als o affected the photodegradation of the disperse dye on the fibers. A U VA which does not absorb light below 260 nm was found not to be operat ive for improving the photodegradation of the fibers themselves and of the dye on the fibers. The relationship between the added UVA and the photodegradation behavior of the fiber and of the dyed fiber is discu ssed. (C) 1997 Elsevier Science Ltd.