Theoretical Considertions of Anomalous Fading of Some Substantive Azo Dyes on Cellophane Film

몇 가지 Azo계 직접 염료의 셀로판 막 위에서의 이상(이상)광 퇴색에 관한 이론적고찰

The anomalous fading behavior of C.I. Direct Red 81, C.I. Direct Blue 76, and Congo Red on cellophane film has been investigated and discussed, considering with theoretical characteristic fading curve and characteristic fading equation for each dye. In case of Congo Red, the theoretical characteristic fading curve, which varies with fading rate of aggregatively sorbed component and shape of sorption isotherm of the dye, is particularly introduced. As a result, the cause of the anomalous fading of the dyes on cellophane film is shown to be contribution of physical state of the dyes. It is assumed that the anomalous fading of Congo Red in a range of certain dye concentration on film occurs in the moment the dye is growing to partly aggregate in the substrate. Therefore, the fading behavior of Congo Red suggests that many other substantive azo dyes known to be a normal fading dye may also show the same anomalous fading behavior as Congo Red.