The invention discloses a preparation method of polydihydroxyindole and application of the polydihydroxyindole in hair
dyeing, and belongs to the field of functional materials and the field of daily
cosmetics. The polydihydroxyindole is obtained in the mode that Boc-true
melanin is formed after true
melanin is protected through phenolic hydroxyl groups, the Boc-true
melanin is subjected to
oxidative degradation, separation and purification and then deprotection, the true melanin is naturally extracted melanin or chemically synthesized melanin or melanin synthesized through a microbiological method, and the
oxidative degradation method is an enzymatic
oxidative degradation method. The obtained polydihydroxyindole is moderate in molecular weight and has excellent permeability on hair, a strong alkaline condition is not needed in the
oligomer dyeing process, and hair quality damage can be reduced; the polydihydroxyindole is oxidized again in the hair
dyeing process to generate melanin, and under the condition that the pH is 5-7, and in the presence of
ferric ions, the polydihydroxyindole can be more tightly combined with
keratin on the hair to coat the outer layer of the hair, so that the hair color is deepened, and the effects of dyeing and protecting the hair are achieved.