アゾ染料の発色および光退色におよぼす金属塩の影響

抄録

Quantum yields (φa) of photofading were measured on azo dyes, 2-(substituted phenyl-azo)-1-naphtho1-4-sulfonic acid (SBD-NW). The reaction constant (ρ) of φα-Hammett's substituent constant (σ) plots was negative, which suggests photofading of SBD-NW proceeding through photooxidation by oxygen. The colored image formed with an azo dye derived from a photosensitive diazonium compound faded faster than that from an imsemsltive one. The coloring and photofading of the azo dye were controlled by addition of metallic salts. The absorption maxima of colored paper added with MgCl₂, AICl₃, ZnCl₂ and NiCl₂ showed bathocromic effect. It was detected by IR spectrum that the metal ion was combined with N=N bond and hydroxyl group of SBD-NW. The degree of bathocromic effect and retardation of photofading of azo dyes added metallic salts decreased in the following order; NiCl₂>ZnCl₂>AlCl₃>MgCl₂. This order is the same as electronegativity of the metal.