Three dyeing methods are applicable to hair dying such as permanent hair dyeing which is major in the market, semi permanent hair dyeing, and temporary hair dyeing.
The dyestuffs used for permanent hair dyeing are oxidative dyes showing excellent wash...
Three dyeing methods are applicable to hair dying such as permanent hair dyeing which is major in the market, semi permanent hair dyeing, and temporary hair dyeing.
The dyestuffs used for permanent hair dyeing are oxidative dyes showing excellent wash fastness because the individual dye molecules in the cuticle layer are clustered and polymerized after penetrating the layer. Although permanent hair dyeing gives an advantage to wash fastness, it may introduce damages on hair skin from the oxidant used. On the contrary, when acid dyes are used for semi permanent hair dyeing, they show poor wash fastness in the absence of damages on the hair.
In the present study, the milling acid dyes, such as C.I. Acid Red 114 and C.I. Acid Blue 90 were chosen to approach the appropriate conditions for semi permanent hair dyeing. The chemical structures of dyestuffs were characterized by UV and FT-IR analysis. The maximum absorption wavelength determined by the UV-visible spectrum were 620㎚ and 520㎚ for the respective dyestuff of C.I. Acid Red 114 and C.I. Acid Blue 90.
The milling type acid dyes showed good affinity to hair. As the concentration of acid dyes increased from 0.1% up to 1.0%, the dye adsorption to hair was sharply increased at relatively lower concentration and reached saturation at above 0.4 - 0.5% showing almost Langmuir type isotherm. Therefore, the dyeing process can be explained as ionic bonding of the dye molecules on the positive site in the hair. The dyeing mechanism can be confirmed by the effects of pH on dye exhaustion shown as dye uptake increase at lower pH.
Additive effects were also studied. When benzyl alcohol was added in the bath, the uptake of C.I. Acid Red 114 was increased dramatically, and acetophenone for C.I. Acid Blue 90. The addition of cationic surfactant increased the dye uptake into hair. The behavior was explained by the caionic surfactant accessed to the hair surface in advance of the dye molecules and improved affinity of the dye molecules the hair surface. An addition of chitosan improved wash-fastness of C.I. Acid Red 114 produced by PR color and C.I. Acid Blue 90 produced PB color and even introduced antibacterial activity at relatively high concentration.