Cationic Azo Dyes for Gentle Keratin Coloring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hair dye technologies face challenges in achieving durable, light-fast, and toxicologically safe dark colors, particularly black shades, which often require mixtures of dyes and can damage hair structures or have sensitization potential.
Innovation Solution
Development of cationic, anionic, or neutral azo dyes compatible with water-based formulations that are stable to oxidizing agents, allowing for gentle application and use in both non-oxidative coloring and lightening processes, including the use of hydrogen peroxide, to produce natural-looking dark shades without hair damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxidation dyes are used to achieve dark colors, then color durability is improved, but hair structure damage increases
Solution Approach 1:
The patent changes the chemical parameters of the dyeing system by using direct dyes with specific molecular structures (sulfonated or carboxylated groups) that enable direct binding to keratin without oxidation. This parameter change allows achieving dark colors while eliminating the harmful oxidative damage to hair structure.
Solution Approach 2:
The invention extracts and eliminates the oxidation step from the traditional dyeing process. By using direct dyes that bind directly to keratin through non-covalent interactions, the patent removes the need for harsh oxidizing agents, thereby preventing hair structure damage while maintaining color durability.
2Adaptability or versatility
If mixtures of several direct dyes are used to achieve black shades, then color variety is improved, but formulation complexity increases
Solution Approach 1:
The patent develops universal direct dye molecules with specific structural features (sulfonated or carboxylated groups combined with appropriate chromophores) that can produce a range of dark shades through variations in substitution patterns. This multi-functionality allows a single dye class to achieve color variety without requiring complex mixtures of different dye types.
Solution Approach 2:
The invention achieves color variety by introducing local structural variations (different substituents at specific positions on the dye molecule) rather than using completely different dye molecules. This local quality approach allows tuning of color shades while maintaining the same fundamental dye structure and binding mechanism.
3Object-affected harmful factors
If direct dyes are used for gentle hair coloring, then hair damage is reduced, but color fastness to oxidizing agents deteriorates
Solution Approach 1:
The patent converts the potential vulnerability of direct dyes to oxidation into a benefit by incorporating structural features (sulfonated or carboxylated groups) that not only enable direct keratin binding but also provide oxidation resistance. The same functional groups that facilitate gentle binding also protect against oxidizing agent degradation.
Solution Approach 2:
The invention creates composite dye molecules that combine multiple functional elements: chromophores for color, sulfonated or carboxylated groups for keratin binding and oxidation resistance, and hydrophobic regions for membrane interaction. This composite structure achieves both gentle application and improved fastness to oxidizing agents.
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 new azo dyes provide even, long-lasting, and natural colorations with good fastness to light, washing, and perspiration, while being gentle on hair and safe for use, eliminating the need for multiple dye mixtures and reducing damage.
Implementation Method 1
special cationic as well as anionic or neutral (uncharged) azo arrangements provide dark colours
Implementation Method 2
Since these dyes are also stable towards oxidizing agents (e.g. hydrogen peroxide)
Data Source
AI summary
The present invention relates to a) a non-oxidative colouring agent for keratin fibres, in particular human hair, comprising at least one dye according to formula (I) or (II), b) an oxidative colouring agent for keratin fibres, in particular human hair, which comprises at least one oxidizing agent (e.g. hydrogen peroxide), at least one oxidative dye precursor and at least one dye according to formula (I) or (II), and c) a lightening agent for keratin fibres, in particular human hair, which comprises at least one oxidizing agent (e.g. hydrogen peroxide) and at least one dye according to formula (I) or (II), with R4 being a cationic group.