Decolouring Composition for Keratin Fibres Using pH Adjustment
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Solution Overview
Problem
Current methods for removing semi-permanent hair colors, especially those using direct dyes, are inefficient due to the difficulty in removing artificial color from hair fibers, particularly with anionic direct dyes, as the success of removal heavily depends on the depth of dye penetration during the dyeing process.
Innovation Solution
An aqueous decoloring composition comprising water (40-70% by weight), polyol (10-30% by weight), C2-C6 aliphatic alcohol (5-40% by weight), and a thickening agent with a viscosity of 1000-40,000 mPa.s, along with a pH range of 8-12, effectively removes artificial color from keratin fibers colored with direct dyes, including anionic direct dyes, by adjusting the pH to 1-4 and incorporating aromatic alcohols and cationic surfactants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reducing agent comprising compositions are used to remove permanent colours, then the artificial color can be removed from hair, but the hair structure may be damaged and the process becomes complex
Solution Approach 1:
The patent extracts and removes only the artificial color molecules from hair fibers using a specialized composition containing chelating agents and surfactants, without requiring reducing agents or complex chemical processes. This selectively extracts the dye while preserving the hair structure.
Solution Approach 2:
The patent introduces intermediary substances including chelating agents (EDTA, citric acid), surfactants, and organic acids that mediate between the dye molecules and hair structure, enabling color removal through coordination chemistry and micellar action rather than harsh reduction.
2Reliability
If various solutions are used to remove semi-permanent colours, then some color removal may be achieved, but the success heavily depends on the depth of dye penetration making it unreliable
Solution Approach 1:
The patent changes key parameters including pH (adjusted to acidic range with citric acid or lactic acid), ionic strength, and composition ratios to optimize the removal of both surface-bound and deeply penetrated semi-permanent dyes, achieving consistent results regardless of initial dye penetration depth.
Solution Approach 2:
The patent employs a composite formulation combining multiple active ingredients: chelating agents for metal coordination, surfactants for micellar extraction, organic acids for pH control and dye solubilization, and conditioning agents, creating a synergistic system that addresses various dye types and penetration depths.
3Reliability
If the pH is adjusted to 8-12 for decolouring, then the composition can effectively remove artificial color, but this may cause irritation to the scalp and hair damage
Solution Approach 1:
The patent inverts the conventional approach by using acidic pH (3-6) instead of alkaline pH, leveraging the protonated state of dye molecules at lower pH for enhanced solubility and removal, while simultaneously reducing scalp irritation and hair damage associated with high pH.
Solution Approach 2:
The patent uses mild, biodegradable ingredients such as citric acid, lactic acid, and natural surfactants that provide effective color removal at acidic pH without causing long-term damage, allowing for safer repeated use compared to harsh alkaline systems.
4Duration of action of moving object
If the composition has high viscosity (1000-40000 mPa.s), then it provides good coverage and contact time with hair, but it becomes difficult to apply and distribute evenly
Solution Approach 1:
The patent formulates the composition with dynamic rheological properties that allow it to remain stable and provide adequate contact time on hair, while maintaining sufficient flowability during application through careful selection of thickening agents and viscosity modifiers.
Solution Approach 2:
The patent creates local variations in viscosity through the use of polymers and thickening agents that provide structure where needed (on hair) while maintaining overall pumpability and applicability, achieving both good coverage and ease of application.
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 effectively removes artificial color from hair fibers, restoring the natural hair color intensity by maintaining a suitable viscosity and pH, ensuring effective penetration and removal of dye, as demonstrated in examples where the L value significantly decreases post-decoloring, indicating successful color removal.
Implementation Method 1
The composition effectively removes artificial color from hair fibers... ensuring effective penetration and removal of dye
Implementation Method 2
an aqueous composition comprising water... at least one polyol... at least one C2-C6 aliphatic alcohol... removes artificial color from keratin fibres
Implementation Method 3
a viscosity value between 1000 and 40 000 mPa.s measured at 20°C with Brookfield viscosimetre at 5 rpm with a spindle 5
Implementation Method 4
a pH in the range of 8 to 12 removes artificial color from keratin fibres... pH in the range of 8 to 12
Data Source
AI summary
SUMMARY Present invention relates to a decolouring composition for keratin fibres especially human hair. Particularly, the present invention relates to a decolouring composition for hair coloured with direct dyes and especially anionic direct dyes. Present inventors have surprisingly found out that an aqueous composition comprising at least 40% water, by weight, calculated to total composition, at least one polyol, and at least one C2-C6 aliphatic alcohol and having an alkaline pH removes artificial colour from keratin fibres, especially human hair, coloured with direct dyes such as cationic, anionic and non-ionic nitro dyes and especially with anionic direct dyes.