Ampholytic Polymer Mediator Prevents Precipitation in Hair Dye Formulations
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Solution Overview
Problem
Conventional melanin precursor-based hair dyes, such as those using 5,6-dihydroxyindole or its derivatives, suffer from poor hair dyeing properties and require extensive time and effort for application, leading to stability and appearance issues due to precipitation when combined with cationic polymers.
Innovation Solution
A hair cosmetic formulation containing a melanin precursor, a cationic polymer, and an ampholytic polymer with specific structural units, which prevents precipitation and enhances storage stability and hair dyeing properties by dispersing aggregates effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a melanin precursor (5,6-dihydroxyindole or derivative) is used in a hair cosmetic with a cationic polymer, then the hair dyeing properties are improved, but precipitation occurs leading to poor storage stability and appearance
Solution Approach 1:
The patent introduces an ampholytic polymer as an intermediary substance that mediates between the melanin precursor and the cationic polymer. This ampholytic polymer has both cationic and anionic groups, allowing it to interact with both components without forming harmful complexes. The ampholytic polymer acts as a bridge that prevents direct interaction between the melanin precursor and cationic polymer, thereby preventing precipitation while maintaining the beneficial hair dyeing properties.
Solution Approach 2:
The patent creates a composite formulation by combining the melanin precursor, cationic polymer, and ampholytic polymer in specific proportions. This composite approach allows the system to exhibit synergistic effects where the ampholytic polymer modifies the interaction between the other two components. The composite structure enables the formulation to maintain stability while achieving effective gray hair dyeing.
2Object-affected harmful factors
If conventional melanin precursor-based hair dye is used, then oxidation damage is reduced, but hair dyeing properties are insufficient and extensive time is required for application
Solution Approach 1:
The patent modifies the formulation parameters by introducing the ampholytic polymer in specific concentrations (0.01-5% by mass) and adjusting the pH level (8.0-11.0). These parameter changes enable the melanin precursor to function more effectively without requiring extensive application time. The ampholytic polymer enhances the penetration and deposition of the melanin precursor onto the hair shaft, improving dyeing efficiency while maintaining the low-oxidation-damage advantage.
3Ease of operation
If a cationic polymer is added to improve hair touch and reduce damage, then hair care properties are improved, but complex formation with melanin precursor causes precipitation
Solution Approach 1:
The ampholytic polymer serves as a mediator that prevents direct complex formation between the cationic polymer and melanin precursor. By having both cationic and anionic groups, the ampholytic polymer can interact with the cationic polymer through its anionic groups while its cationic groups prevent direct contact with the melanin precursor, thereby eliminating precipitation while maintaining the hair care benefits.
Solution Approach 2:
The ampholytic polymer introduces local regions of different charge densities within the formulation. The cationic groups of the ampholytic polymer interact with the anionic groups of the melanin precursor locally, while the anionic groups interact with the cationic polymer locally. This localized interaction strategy prevents global complex formation and precipitation while maintaining the beneficial effects of both the cationic polymer and melanin precursor.
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 formulation provides improved hair dyeing properties, storage stability, and ease of use by preventing precipitation, allowing for effective and efficient gray hair dyeing through daily hair care routines.
Implementation Method 1
it forms a complex together with the cationic substance, to generate precipitation
Implementation Method 2
When the precipitation is generated, not only storage stability or appearance of the product is impaired
Implementation Method 3
it forms a complex together with the cationic substance, to generate precipitation
Implementation Method 4
an air-oxidative hair dye using 5,6-dihydroxyindole, 5,6-dihydroxyindoline, or a derivative thereof, each of which is a melanin precursor
Implementation Method 5
5,6-dihydroxyindole, 5,6-dihydroxyindoline, or a derivative thereof, each of which is a melanin precursor
Data Source
AI summary
The present invention relates to a hair cosmetic containing the following components (A) to (C): (A) a compound represented by the following general formula (1) or a salt thereof: wherein a broken line represents the presence or absence of a π bond; R1 represents a hydroxy group or an acetoxy group; R2 represents a hydrogen atom or -COOR (R is a hydrogen atom, a methyl group, or an ethyl group); and R3 represents a hydrogen atom, an acetyl group, a methyl group, or an ethyl group; (B) a cationic polymer; and (C) an ampholytic polymer having a predetermined cationic structural unit and an anionic structural unit, a mass ratio of the component (C) to the component (A) [(C)/(A)] being 0.7 or more and 10 or less.