Imidazolium Azo Dye Stability in Alkaline Hair Color
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Solution Overview
Problem
Current hair dye technologies face challenges in achieving stable blue hues in alkaline pH conditions, particularly in highly aqueous systems, due to the instability of thiazolium and imidazolium azo compounds, which are essential for vibrant blue colors.
Innovation Solution
Development of hair color compositions featuring novel violet-blue to blue imidazolium azo compounds with electron-donating groups in the donor portion, enhancing solubility and stability in aqueous systems, including the presence of oxidants like hydrogen peroxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If electron-withdrawing groups are added to the acceptor (imidazolium) end of the molecule to achieve desired color shift, then the color wavelength increases, but the stability of the dye decreases, especially at alkaline pH
Solution Approach 1:
The patent changes the chemical parameters of the dye molecule by replacing electron-withdrawing groups with electron-donating groups (such as hydroxyl, alkoxy, amino, or carboxyl groups) on the acceptor portion. This parameter change shifts the color to the desired violet-blue to blue range while maintaining stability at alkaline pH, resolving the contradiction between color wavelength and dye stability.
2Illumination intensity
If thiazolium azo compounds are used to achieve brilliant and water-soluble blue colors, then the color intensity increases, but the stability under basic conditions deteriorates
Solution Approach 1:
The patent changes the chemical structure from thiazolium to imidazolium azo compounds with electron-donating groups, which fundamentally alters the stability parameters while maintaining color intensity. This structural parameter change enables the dye to remain stable under basic conditions while still providing brilliant blue colors.
3Stability of the object's composition
If common imidazolium dyes are used to achieve stable orange to violet-red colors, then the stability improves, but the blue hue capability is lost
Solution Approach 1:
The patent changes the electronic parameters of the imidazolium azo compound by introducing electron-donating groups on the acceptor portion. This parameter change shifts the absorption spectrum to produce blue hues while maintaining the stability characteristic of imidazolium dyes, thus achieving both blue color and stability simultaneously.
4Illumination intensity
If highly substituted acceptor portions with electron-withdrawing groups are used to achieve violet-blue to blue colors, then the desired color range is obtained, but the solubility in aqueous systems decreases
Solution Approach 1:
The patent changes the substituent parameters from electron-withdrawing groups to electron-donating groups (hydroxyl, alkoxy, amino, carboxyl) on the acceptor portion. This parameter change maintains the violet-blue to blue color range while improving solubility in aqueous systems, as electron-donating groups generally enhance water solubility compared to highly substituted electron-withdrawing groups.
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 compositions provide stable and intense blue-violet to blue colors on hair and keratinaceous materials, maintaining stability under conditions of use and storage, addressing the limitations of existing dyes in alkaline pH and aqueous environments.
Implementation Method 1
stable violet-blue to blue chromophores based on a combination of the imidazolium azo core with electron-donating groups in the donor portion of the molecule that previously has not been exploited to produce blue colors
Implementation Method 2
stability under conditions of use and storage, including in the presence of oxidants such as hydrogen peroxide
Data Source
AI summary
Disclosed are hair color compositions comprising novel stable violet-blue to blue imidazolium azo compounds that have a simplified chromophore and high relative solubility in aqueous systems, and that are surprisingly stable under the conditions of use and storage. These compositions are useful for dyeing fibers such as hair and other keratinaceous materials. The compositions can optionally include an oxidant.