Anionic Azo Dyes for Keratin Fiber Coloring
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Solution Overview
Problem
Current hair dyes, particularly oxidation dyes, can cause damage to hair fibers and have inadequate fastness properties, especially when used for simultaneous coloring and lightening, leading to uneven results and sensitivity issues in some individuals.
Innovation Solution
Development of anionic azo dyes with a sulfate unit bound to the azo chromophore, specifically compounds of formula (I), which provide intense and stable color shades even in the presence of oxidizing agents like hydrogen peroxide, ensuring good fastness properties and stability during hair lightening and coloring processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxidation dyes are used for coloring keratinic fibers, then intense colors with good fastness properties can be obtained, but the oxidizing agents may result in damage to the fiber
Solution Approach 1:
The patent uses substantive dyes instead of oxidation dyes, changing the chemical mechanism from oxidative coupling to direct adsorption. This parameter change eliminates the need for harsh oxidizing agents while maintaining acceptable fastness properties through the dye's molecular structure and affinity for keratin.
Solution Approach 2:
The patent employs substantive dyes that work in gentler, shorter-duration applications without requiring strong oxidizing agents. These dyes provide sufficient fastness for cosmetic hair coloring without the long-term damage associated with repeated oxidation treatments.
2Object-affected harmful factors
If substantive dyes are used for coloring keratinic fibers, then gentler application conditions are achieved, but the colors have inadequate fastness properties
Solution Approach 1:
The patent modifies the dye molecular structure by introducing specific sulfonate groups and aromatic amine components that enhance both substantivity (affinity for hair) and fastness. This structural parameter change allows substantive dyes to achieve oxidation-dye-level durability without the harsh chemical process.
Solution Approach 2:
The invention uses composite dye molecules combining aromatic amine groups, sulfonate groups, and azo linkages in specific configurations. This composite molecular structure provides multiple interaction points with keratin, enhancing both binding strength and color fastness while maintaining gentle application conditions.
3Speed
If a mixture of hydrogen peroxide and persulfates is used for extreme lightening of dark hair, then significant lightening can be achieved, but the choice of stable dyes is very limited
Solution Approach 1:
The patent uses substantive dyes that provide sufficient coloration for cosmetic purposes without requiring extreme lightening. This approach eliminates the need for harsh lightening mixtures, expanding dye selection to include the full range of substantive dye colors while achieving satisfactory results on dark hair.
Solution Approach 2:
The invention changes the approach from lightening-first to direct coloring with substantive dyes that work across various hair colors. This parameter change in the coloring mechanism allows versatile dye selection without being constrained by lightening compatibility.
4Manufacturing precision
If substantive dyes are used for coloring pretreated hair, then uniform coloring is difficult to achieve, but repeated washing causes dyes to be washed out to varying degrees
Solution Approach 1:
The patent optimizes the dye molecular structure with specific sulfonate groups and aromatic amine components that provide uniform penetration and binding across differently pre-damaged hair areas. This structural parameter change ensures consistent coloration and uniform wash-fastness across the entire hair shaft.
Solution Approach 2:
The invention creates homogeneous color distribution by using substantive dyes with consistent molecular properties that bind uniformly to keratin regardless of local hair damage variations. This homogeneity in dye-hair interaction ensures even coloration and consistent fastness across all treated areas.
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 azo dyes deliver intense, bright, and long-lasting color shades with excellent wash fastness, light fastness, and stability, suitable for both bleached and dark hair, while minimizing damage and sensitivity concerns.
Implementation Method 1
Substantive dyes are applied under gentler conditions
Implementation Method 2
the development of the color generally takes place under the influence of oxidizing agents such as, for example, H2O2
Data Source
AI summary
The present specification provides for an agent for coloring keratinic fibers. The agent includes, a cosmetic carrier, a compound of formula (I),R1 and R2 independently of one another denote hydrogen, a C1-C6 alkyl group, a C2-C6 alkenyl group, a hydroxyl group, a halogen, a C1-C6 alkoxy group, an amino group, a nitro group, an acetyl amino group, or a sulfonamide group; or when in ortho-position to one another, form a 5- or 6-membered, saturated or unsaturated ring, which optionally include further heteroatoms.