Katsumasa Otake

Photodegradation of a disperse dye on polyester fiber and in solution

The photodegradation behavior of dyes on fibers such as nylon, cotton fibers, and in particular, polyester, and in a solution has been investigated. The undyed and dyed fibers were irradiated with monochromatic light of various wavelengths. The light source was separated into 20 distinct wavelengths and the photodegradation behavior at each wavelength was examined. It was found that the most effective wavelength for the photodegradation of a disperse dye on polyester fiber was near 320 nm. The wavelength also affected the photodegradation of the fiber itself. Similar phenomena were observed for nylon fiber: light near 370 nm influenced significantly both the dye on the fiber and the fiber itself. With cotton, light at 260 nm was significant. To clarify these results, photodegradation of the dye in ethyl acetate containing dissolved polyester was also carried out. The same phenomena as those observed on the fiber were shown to be operative.

Effect of ultraviolet absorbing agents on photodegradation behavior of a disperse dye

Abstract The action and effect of ultraviolet absorbing agents (UV A) on the photofading of dyed fiber, in particular polyester, were investigated using a monochromatic light source. Polyester fiber itself and the dyed fiber were affected markedly by spectroirradiation at a specific wavelength, viz. 316 nm: yellowing of the fiber alone and photofading of C.I. Disperse Red 73 on the fiber occurred maximally at this wavelength. UV As of the benzotriazole and phenyl salicylate types, which show absorption spectra around 316 nm, protected the decomposition of polyester at 316 nm irradiation, and hence the photodegradation of the dye on the fiber. Diacetate and triacetate fibers were decomposed maximally by irradiation at 230 nm and 259 nm, respectively. These wavelengths also affected the photodegradation of the disperse dye on the fibers. A UV A which does not absorb light below 260 nm was found not to be operative for improving the photodegradation of the fibers themselves and of the dye on the fibers. The relationship between the added UV A and the photodegradation behavior of the fiber and of the dyed fiber is discussed.