Evaluation of Hair Coloring Agent Using Diphenyl Indo Dyes

Most hair coloring involves oxidative polymerization of oxidation dye intermediates (precursor and coupler) with an oxidizing agent. A dyeing method for simultaneously carrying out this reaction and decomposition reaction of melanin in the hair by an oxidizing agent is widely used with high convenience. However, it is known that oxidizing agents damage the cuticles and cortex constituting the hair. In addition, allergies due to oxidative dye intermediates have been reported. In this study, we synthesized oxidative polymerization dye (diphenyl indo dye) with oxidation dye intermediates during oxidation in advance before use for dyeing hair. The dyeing of the hair was carried out with a model cream formulated with the oxidation dye. Then, we confirmed the functionality of that hair dyeing method using oxidation dyes added to the hair. In addition to sensory evaluation based on the appearance and feel of the hair, the evaluation of the functionality of the hair was carried out by protein dissolution measurement from the hair, luster measurement, friction measurement, compression measurement and the like. As a result, it became clear that hair coloring agents containing oxidation dyes make it possible to dye without damaging the hair, giving the hair a glossy feeling, smoothness and flexibility. Since the hair dyeing method using oxidation dyes imparts new functionality to the hair, development of a further hair dye making use of its properties is expected.