Hair Colouring Formulation Using Cationic and Anionic Polymers
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Solution Overview
Problem
Current hair coloring methods, particularly oxidative systems, cause hair damage and scalp irritation due to high pH and oxidizing agents, and temporary systems suffer from poor washfastness and scalp staining.
Innovation Solution
A hair coloring formulation using a combination of cationic and anionic polymers with linked chromophores or fluorophores, applied in layers to achieve a multilayer structure that enhances washfastness and stability while minimizing hair and scalp damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If oxidative hair coloring compositions are used to permanently change hair colour, then the colour permanency is improved, but the hair structure is damaged and scalp irritation occurs
Solution Approach 1:
The patent extracts and eliminates the harmful oxidizing agents and high pH alkalizing agents from the hair coloring composition, retaining only the essential dye precursors and conditioning agents. This removal of harmful components resolves the contradiction by maintaining colour permanency through the remaining reactive dye system while eliminating the damaging effects on hair structure and scalp.
Solution Approach 2:
The patent fundamentally changes the pH parameter from highly alkaline (pH 10-11) to a milder range, and eliminates the oxidizing agent parameter entirely. By using a non-oxidative dyeing mechanism with conditioning polymers, the system achieves permanent color change without the damaging high pH and oxidation conditions, thus resolving the contradiction between permanency and hair damage.
2Object-affected harmful factors
If direct dye compositions are used for temporary hair colour change, then the aggressiveness to hair is reduced, but the washfastness becomes weaker
Solution Approach 1:
The patent creates a composite material system combining direct dyes with cationic conditioning polymers. The polymer component provides strong adhesion to the negatively charged hair surface, while the attached dye molecules provide coloration. This composite structure resolves the contradiction by maintaining the low aggressiveness of direct dyes while achieving permanent or semi-permanent washfastness through the polymer's binding properties.
Solution Approach 2:
The cationic polymer acts as an intermediary between the dye molecules and the hair surface. It mediates the attachment process by providing positive charges that bind to negative charges on hair, thereby anchoring the dye molecules firmly to the hair shaft. This intermediary mechanism achieves strong washfastness without requiring aggressive chemicals, resolving the contradiction between gentleness and durability.
3Ease of operation
If direct dyes are used for temporary hair colouring, then the application is simpler, but the scalp staining occurs
Solution Approach 1:
The cationic polymer serves as a selective intermediary that preferentially binds to the negatively charged hair surface rather than the scalp. This mediation directs the dye deposition to hair while preventing scalp staining, as the polymer-hair complex forms on the hair shaft and does not migrate to or stain the scalp. The application remains simple while the harmful scalp staining effect is eliminated.
4Illumination intensity
If standard oxidative hair colouring compositions are used, then the colour intensity is achieved, but the odour becomes undesirable
Solution Approach 1:
The patent extracts and removes the source of undesirable odour, which is the oxidizing agent (typically hydrogen peroxide) and its decomposition products. By eliminating these oxidizing components while retaining effective dye precursors and polymer carriers, the system maintains strong color intensity through alternative mechanisms without generating the characteristic unpleasant odour of oxidative hair dyes.
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 solution provides improved washfastness, stability, and control over color intensity, reducing damage to hair and scalp irritation, with the ability to achieve a range of color shades from pastel to intense without hair damage.
Implementation Method 1
The hair colouring formulation comprises a coloured polymer selected from the group consisting of: a coloured cationic polymer formed by a cationic polymer backbone and at least a cationic chromophore linked to the cationic polymer backbone; a coloured cationic polymer formed by a cationic polymer backbone and at least an anionic chromophore linked to the cationic polymer backbone
Implementation Method 2
The coloured polymer comprises one or more chromophores as a pendant group
Implementation Method 3
a coloured cationic polymer formed by a cationic polymer backbone and at least a cationic fluorophore linked to the cationic polymer backbone
Data Source
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AI summary
Formulation for colouring hair having at least one coloured polymer.