Hair Dye Composition Stability via Alkali Metal Salt Mediator
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Solution Overview
Problem
Hair dyes containing cationic compounds and anion-state azo dyes form salts, leading to precipitation issues, poor handling, and reduced hair-dyeability, with increasing dye amounts causing stability problems.
Innovation Solution
A hair dye composition with a specific combination of dissociative azo dyes and cationic compounds, including alkali metal salts, maintains stability and hair-dyeability without forming salts, even in alkaline conditions, providing excellent feel and color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cationic compounds and anion-state azo dyes are combined in hair dye composition, then hair-dyeability is improved, but salt formation occurs leading to precipitation and reduced stability
Solution Approach 1:
The patent introduces a specific intermediary substance (compound with formula (1) containing carbonyl and hydroxyl groups in a 1:2 or 1:3 ratio) that mediates between the cationic compound and anion-state azo dye. This intermediary prevents direct salt formation while enabling effective hair dyeing, resolving the contradiction between hair-dyeability and composition stability.
Solution Approach 2:
The patent changes the chemical parameters by specifying precise structural ratios (carbonyl:hydroxyl = 1:2 or 1:3) and chemical composition of the intermediary substance. By controlling these parameters, the formulation achieves both stability prevention and effective dyeing performance.
2Reliability
If dye amount is increased to improve hair-dyeability, then color intensity is improved, but formulation stability deteriorates
Solution Approach 1:
The intermediary substance acts as a buffer that allows higher dye concentrations to be incorporated without causing instability. It mediates the interaction between dye and cationic compounds, enabling increased dye loading while maintaining formulation stability.
3Reliability
If alkali conditions are used to activate azo dye dissociation, then hair-dyeability is improved, but salt formation between cationic compounds and anionic dyes is promoted
Solution Approach 1:
The intermediary substance with specific carbonyl and hydroxyl groups acts as a protective mediator in alkaline conditions. It prevents direct electrostatic interaction between cationic compounds and anionic azo dyes even when the dye is dissociated, thereby preventing salt formation while maintaining alkali-activated dyeing performance.
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 composition ensures stable and effective hair dyeing with improved texture and reduced dripping, while maintaining stability and preventing salt formation, thus enhancing the hair's feel and color retention.
Implementation Method 1
A hair dye composition comprising the following components (A), (B) and (C) and having pH (25° C.) of 7.5 or more and 12 or less: (A) one or more azo dyes... (B) a cationic compound... (C) 0.1 mass % or more and 8 mass % or less of at least one alkali metal salt of an acid selected from the group consisting of hydrochloric acid, carbonic acid and sulfuric acid
Implementation Method 2
Patent Document 1 proposes an azo dye containing a dissociative proton as a direct dye suitable for use in dyeing the hair and teaches that hair-dyeability is produced in an anionic state where a dissociative proton(s) dissociates in an alkaline condition
Implementation Method 3
The present invention provides a hair dye composition... comprising (A) one or more azo dyes... (B) a cationic compound... (C) 0.1 mass % or more and 8 mass % or less of at least one alkali metal salt of an acid... The composition ensures stable and effective hair dyeing with improved texture and reduced dripping, while maintaining stability and preventing salt formation
Data Source
AI summary
A hair dye composition comprising the following components (A), (B) and (C) and having pH (25° C.) of 7.5 or more and 12 or less:(A): one or more azo dyes selected from the group consisting of the following (A-1), (A-2) and (A-3):(B): a cationic compound(C): 0.1 mass % or more and 8 mass % or less of at least one alkali metal salt of an acid selected from the group consisting of hydrochloric acid, carbonic acid and sulfuric acid.