The Effects of Fluorescent Brightening Agents on the Photofading of Blue Acid Azo Dyes

Abstract

Blue acid azo dyes (AB 92, AB 116, ABk 1 and AG) have been irradiated with monochropa. atic lights of various wavelengths, and the influences of flurescent brightening agentsts of stilbene (FBg) and pyrazoline type (FwG) on the photofading have been investigated.
The light from visible near ultraviolet region gave rise to s1ight fading of dyes. The rates of photodegradation increased sharply on irradiation with the light at the wave length shorter tAan 300Tnm. lrradiation with 252 nm light gave the quantum yield of 3x10dNl, 1x10ews for the air saturated solution. The fluorescent agents faded to a certain extent by the irradiation with the light of the 300-400nm region where the fluorescence had the excitation maximal and the rate of photofading was more rapidly at shorter wavelength. Dissolved oxygen depressed the degradation of the dyes and accelerated that of FwGi
T-heVfluorescent'agents'quenched the photofading reaction of thedyes when they were applied without oxygen. Oh the other hand, acceleration of the reaction was observed'.in thg.air sa.tur rated solutfoWn. The acceleration effects were most prominent on 300At400 nm, irradiation(cf.Figs. 5 and 6). The effect of Fwo was three times as strong as FBs. IMTdshe Effects of Fluorescent substances en the phetofading of Celers. 1.