Carbon black as a dulling agent for nylon 6 filaments and the lightfastness of dyes on dulled filaments

Abstract

Nylon 6 filaments containing 0–1.5% carbon‐black pigment are dyed to different depths of shade. The colour on the substrate is evaluated on CIELAB a* b* diagrams at given concentrations of carbon black and dye. The carbon‐black pigment acts essentially as a neutral dulling agent and only with a few dyes does it appear to alter the hue angle slightly. Thus, it is possible to use nylon 6 filaments containing carbon‐black pigment to produce dull shades by the overdyeing process. The dyed samples thus produced are exposed to mercury‐lamp light as well as daylight. The lightfastness is evaluated visually using the Blue Wool Scale. There is a remarkable improvement in the lightfastness of all dyes on nylon 6 containing carbon‐black pigment. The carbon black in the filament appears to protect both the dye and the polymer from the degrading action of actinic radiation. However, the remarkable improvement in the lightfastness is essentially due to the optical effect.