Oxidation Dye Precursor with Alkoxyalkyl Substituents for Uniform Hair Coloring
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Solution Overview
Problem
Existing hair dye compositions using oxidation dye precursors often result in unsatisfactory dyeing power, limited color range, poor persistence against external agents, and excessive selectivity along the hair fiber, particularly failing to provide intense, uniform color with good grey hair coverage.
Innovation Solution
A process involving a composition comprising para-phenylenediamine derivatives, N,N-dicarboxymethylglutamic acid, and a chemical oxidizing agent, which is applied to keratin fibers to achieve intense, uniform color with improved fastness and grey hair coverage, using a kit with separate compartments for the oxidation base and oxidizing agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional oxidation dye precursors are used, then the dyeing process is simple, but the dyeing power is weak and color intensity is insufficient
Solution Approach 1:
The patent modifies the chemical structure of the oxidation dye precursor by introducing specific substituents (alkoxyalkyl or hydroxyalkyl groups at positions 2 and/or 6 of the phenylenediamine ring) to enhance dyeing power while maintaining the fundamental oxidation dyeing mechanism. This structural parameter change increases color intensity without complicating the overall process
2Ease of operation
If conventional dyeing compositions are used, then the application is straightforward, but the color uniformity along the fiber is poor and selectivity is excessive
Solution Approach 1:
The patent introduces specific chemical parameters (substituents at positions 2 and/or 6 of the phenylenediamine ring) that modify the reactivity and diffusion characteristics of the dye precursor, enabling more uniform penetration along the hair fiber and reducing selective staining between root and ends while keeping the application process simple
3Adaptability or versatility
If standard oxidation bases are used, then the formulation is conventional, but the persistence against external agents is poor
Solution Approach 1:
The patent modifies the oxidation base structure by adding specific substituents (alkoxyalkyl or hydroxyalkyl groups) that enhance the stability and fastness of the resulting dye molecules against external agents such as light, shampoo, and perspiration, while maintaining compatibility with conventional formulation approaches
4Ease of manufacture
If traditional dye precursors are used, then the color range is limited, but the process remains simple
Solution Approach 1:
The patent extends the color range by systematically varying the substituents (different alkoxyalkyl or hydroxyalkyl groups) at positions 2 and/or 6 of the phenylenediamine ring, which enables access to multiple shades from light to dark and various color families while maintaining a consistent and simple oxidation dyeing process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process delivers intense, uniform color with a wide range of shades, excellent grey hair coverage, and sustained performance even after storage, addressing the limitations of traditional dyeing methods.
Implementation Method 1
oxidation bases, such as ortho- or para-phenylenediamines, ortho- or para-aminophenols, or heterocyclic compounds such as pyrazoles, pyrazolinones or pyrazolo-pyridines. These oxidation bases are colourless or weakly coloured compounds which, when combined with oxidizing products, can give rise to coloured compounds via a process of oxidative condensation
Data Source
AI summary
The invention relates to a process for dyeing keratin fibres, preferably the hair, comprising the application to said keratin fibres of a composition comprising at least one oxidation dye base chosen from para-phenylenediamine derivatives of formula (I), their addition salts, their solvates and/or the solvates of their salts, in which R is chosen from a (C1-C4)alkoxy(C1-C4)alkyl radical and a C1-C4 hydroxyalkyl radical, at least one compound chosen from N,N-dicarboxymethylglutamic acid, one of its salts and mixtures thereof and a chemical oxidizing agent. The process may comprise the step of mixing a dyeing composition comprising the oxidation dye base and the N,N-dicarboxymethylglutamic acid compound with an oxidizing composition comprising one or more chemical oxidizing agents and applying the obtained mixture to the keratin fibres. A multi-compartment device comprises a first compartment containing the dyeing composition and a second compartment containing the oxidizing composition.