The relationship between the substitution position of hydrophobic groups on near‐magenta anthraquinone dyestuffs and the dyeing performance for polypropylene fabric dyed in supercritical carbon dioxide

Abstract A series of 1‐amino‐4‐hydroxy‐2‐phenoxyanthraquinone derivatives, substituted with various hydrophobic groups, were applied as dyestuffs in the carbon dioxide supercritical fluid dyeing (SFD) of unmodified polypropylene (PP) fabrics. The dyeability, colour strength, and colour fastness of the dyeing process were evaluated for 14 dyestuffs. The hue of the PP fabrics dyed with a series of dyestuffs was red of near‐magenta, but it was slightly less bluish rather than magenta. The differences in dyeing performance regarding the type and position of the substituents were observable in terms of colour strength and colour fastness. On the basis of the evaluation of the colour strength and the colour fastness, this study showed that the type and position of the hydrophobic group attached to the substituted phenoxy ring affected dyeing performance. Comparisons of the dyeing performance of 2‐ and 4‐substituted dyestuffs with the same groups attached suggested that replacement of the 2‐position affected colour strength while 4‐position affected colour fastness. Similarly, 2,4‐disubstituted dyestuff was more suitable on the dyeing performance than 4‐monosubstituted dyestuff in which alkyl had twice the amount of aliphatic carbon at one position, and 3,5‐disubstituted dyestuff.