STUDIES ON THE RELATIONSHIP BETWEEN THE STRUCTURE OF 1:2 TYPE METAL COMPLEX DYES AND THE BEHAVIOURS OF DIFFUSION OF THESE DYES INTO NYLON

Abstract

The diffusion of 1:2 type metal complex dyes into nylon film was measured by the roll film method. Dyes used were 15 symmetrical and 1 unsymmetrical 1:2 type metal complex obtained from substituted o, o′-dihydroxy or o-carboxyl-o′-hydroxy-benzene-azo-naphthalenes (metal is Cr³⁺, Co³⁺ or Al³⁺). Most of the symmetrical complex dyes were Drew-Pfitzner type (type_??_) and 2 dyes were Pfeiffer-Schetty type (type //). The substituted group is H, SO₂NH₂, SO₂CH₃, CH₃, OCH₃, Cl, NO₂, phenyl or SO₃H. Dyeing conditions were as follows: dyebath concentration 2_??_5×10^-5 mol/l in water or in 25% ethanol-water, 80°C, 3_??_6 days. Diffusion profiles obtained can be divided into two parts, i.e., part I (boxlike diffusion) and part N (Fickian diffusion). Diffusion coefficients of both parts (D_OI, D_ON and _??__N ) and the fraction of part I, (I/I+N), were calculated under the assumption that the diffusion of both parts occur competitively. Both parts were affected by the molecular size, shape and hydrophilic property of metal complex dyes, especially part I was influenced by the molecular size of the dyes. As the hydrophilic property of dyes increases, diffusion profiles of the dyes become nearly same as in the case of acid dyes. When the hydrophobic property of dyes increases, the amounts of dye uptake at the surface of nylon increase and diffusion profiles are nearly same as in the case of disperse dyes.