Composition for simultaneously lightening and coloring hair utilizing bleach-stable acid and basic dyes

Abstract From the Canadian patent

A composition of certain dyes with a category-2 hair bleach can simultaneously lighten hair up to seven levels and deposit various shades of color in a single step. The dyes are bleach-stable derivatives of azo triarylmethane, thiazine, or nitro dyes. When linked at the ortho- and/or para- positions relative to the chromophoric centers and auxochrome groups located on or attached to the aromatic rings of these dyes deactivating or weakly , activating chemical groups enhance the dye stability in the alkaline bleach. The absence of ortho and/or para positioned deactivating or weakly-activating substituents, or the presence of strongly activating groups in these positions render the dye …