Dimeric Ring-Bridged Azo Dyes for Hair Fastness
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Solution Overview
Problem
Current hair dye technologies face challenges in achieving stable, intense, and long-lasting color results, especially when used with strong oxidizing agents, and there is a need for dyes that maintain fastness characteristics under extreme conditions.
Innovation Solution
Development of dimeric dicationic azo dyes with specific structural formulas that are compatible with oxidation dyes and oxidizing agents, providing intense and bright colorations while maintaining stability and fastness characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxidation dyes are used to achieve intense colorations with good fastness characteristics, then color intensity and fastness are improved, but fiber damage increases due to oxidizing agents like H2O2
Solution Approach 1:
The patent changes the chemical structure of the dye molecules by using dimeric, ring-bridged azo dyes with specific formulas (I)-(III) instead of conventional monomeric dyes. This structural parameter change allows the dye to achieve better fastness characteristics while being compatible with oxidizing agents, thereby reducing fiber damage during the dyeing process.
2Object-affected harmful factors
If direct dyes are used under gentler conditions, then fiber damage is reduced, but coloration fastness characteristics become inadequate
Solution Approach 1:
The patent creates a composite dyeing system by combining dimeric azo dyes with specific chemical structures (formulas I-III) that integrate the benefits of both direct dyes (gentle application) and oxidation dyes (superior fastness). The ring-bridged dimeric structure acts as a composite molecular architecture that provides both fiber compatibility and enhanced fastness properties.
3Productivity
If strong oxidizing agents like hydrogen peroxide and persulfates are used for pronounced lightening of dark hair, then lightening effect is improved, but dye stability and fastness characteristics deteriorate
Solution Approach 1:
The patent converts the harmful effect of strong oxidizing agents on dye stability into a benefit by designing dimeric azo dyes with ring-bridged structures (formulas I-III) that are specifically engineered to be oxidation-resistant. The ring-bridged structure acts as a protective framework that allows the dye to withstand and even benefit from the oxidative environment, maintaining stability and fastness during pronounced lightening processes.
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 dimeric dicationic azo dyes achieve intense and stable colorations on keratin fibers, ensuring good fastness and compatibility with cationic azo dyes like Basic Orange 31 and Basic Red 51, even under conditions involving hydrogen peroxide and persulfates.
Implementation Method 1
Cationic dyes are often characterized by an especially high affinity for keratin fibers, which can be attributed to the interactions of the positive charges of the dyes with negatively charged structural components of the keratin fibers.
Implementation Method 2
the dyes should, if possible, also be compatible with the oxidizing agents usually used in blonding processes (such as hydrogen peroxide and/or persulfates, for example)... highly stable in the presence of strong oxidizing agents in order to enable the simultaneous dyeing and pronounced lightening of hair
Data Source
AI summary
The present disclosure relates to agents for dyeing keratin fibers, in particular human hair, containing, in a cosmetic carrier (a) at least one direct dye of formula (I), wherein Het 1, Het 2 represent a cationic heterocycle, and A1, A2, independently of one another, represent a grouping of formulas (VIII) or (IX), wherein n represents a whole number of between 2-6, and m, p, independently of one another, represent the numbers 2 or 3.