There are generally three types of hair colouring system in widespread use: permanent, semi-permanent, or temporary. The term “permanent hair colorant” generally refers to oxidative hair colouring agents in which oxidative dye precursors diffuse into the hair through the cuticle and into the cortex, where they can then undergo oxidative coupling reactions in the presence of suitable oxidizing agents to form the end dye molecules which produce colour inside the hair.
Permanent hair colorants are very popular with consumers since they provide vibrant and multi-dimensional colour which is relatively unaffected by light, shampooing and perspiration. However the process is not without drawbacks. Repeated oxidative treatments over prolonged periods may damage or weaken hair, making it prone to breakage and reduced lustre. In an effort to address this problem, many permanent hair colorants are sold with a conditioner. The application of a conditioner deposits a protective layer of conditioning agent onto the hair and results in an improved feel, but it does not protect against damage as such, since it is applied on hair after the colorant has been rinsed off.
Accordingly, there remains a need for oxidative hair colouring compositions which can provide an improved level of hair damage protection during the colouring process. In particular there remains a need for oxidative hair colouring compositions which can provide this improved protection without compromising on colour delivery.
The present invention addresses this problem.