pH-Responsive Fluorescent Compounds for Hair Washfastness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for treating hair with fluorescent compounds face challenges in achieving washfastness, as anionic and zwitterionic fluorophores bleed easily, cationic fluorophores fade with shampoo use, and polycationic fluorophores struggle to penetrate the hair cortex due to strong binding forces that limit their intensity and uniformity of effect.
Innovation Solution
A method involving the application of hair treatment compositions containing fluorescent compounds with one or two permanent cations and one to four incipient cations, which change from neutral to positively charged at a lower pH, allowing for enhanced binding and penetration within the hair shaft, thereby improving washfastness and maintaining optical effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If anionic or zwitterionic fluorophores are used to treat hair, then the application process is simple, but the fluorophores bleed easily and washfastness is poor
Solution Approach 1:
The patent changes the charge parameter of the fluorophore from anionic/zwitterionic to cationic, and specifically introduces a pH-responsive charge transition mechanism where incipient cations change from neutral to positively charged at lower pH, fundamentally altering the binding behavior to achieve both ease of application and improved washfastness
Solution Approach 2:
The patent introduces dynamic charge characteristics where the fluorophore's charge state changes in response to pH conditions - neutral at high pH during application, then becomes positively charged at low pH during rinsing, enabling adaptive binding behavior that solves the washfastness problem while maintaining application simplicity
2Reliability
If cationic fluorophores are used to improve washfastness, then bleeding is reduced, but the fluorophores fade with repetitive shampoo use
Solution Approach 1:
The patent employs dynamic charge transition where incipient cations remain neutral at high pH during initial application to facilitate penetration, then become positively charged at low pH during rinsing to provide strong binding and prevent fading with repetitive shampoo use, thereby extending color longevity while maintaining washfastness
Solution Approach 2:
The patent prepares the fluorophore in a neutral charge state at high pH before application, allowing easy penetration into hair, then triggers the charge transition to positive during the rinsing phase, creating strong binding bonds in advance to prevent subsequent fading during shampooing
3Reliability
If polycationic fluorophores are used to enhance binding strength, then washfastness improves, but penetration into the hair cortex is limited
Solution Approach 1:
The patent uses dynamic charge transition where incipient cations are neutral at high pH during application, reducing electrostatic repulsion and enabling deep penetration into the hair cortex, then become positively charged at low pH during rinsing to provide strong binding and washfastness, thus resolving the penetration-depth versus binding-strength contradiction
Solution Approach 2:
The patent changes the pH parameter from high (during application) to low (during rinsing), which triggers the charge transition of incipient cations from neutral to positive, enabling the fluorophore to achieve both deep penetration and strong binding at different stages of the treatment process
4Reliability
If polycationic fluorophores are used to provide strong binding, then bleeding is minimized, but the fluorophores remain bound to the surface rather than penetrating into the fiber
Solution Approach 1:
The patent employs dynamic charge characteristics where incipient cations transition from neutral to positively charged based on pH, enabling the fluorophore to penetrate deeply during high pH application and then form strong surface and internal bonds during low pH rinsing, achieving both penetration and binding strength
Solution Approach 2:
The patent performs preliminary penetration action at high pH when incipient cations are neutral, allowing the fluorophore to reach deep into the hair cortex, then triggers bond formation at low pH when incipient cations become positive, ensuring strong binding throughout the hair fiber structure
5Reliability
If dimerization of fluorophores is used to increase binding sites, then bleeding and loss during rinsing are minimized, but penetration into the hair shaft becomes difficult
Solution Approach 1:
The patent changes the pH parameter to control the charge state of incipient cations, enabling monomeric fluorophores to penetrate easily at high pH and then form strong bonds at low pH, achieving the benefits of dimerization (strong binding) without the penalty of increased molecular size and reduced penetration
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 approach results in improved washfastness and minimal loss of fluorescence, ensuring the desired optical effects are maintained with reduced bleeding and enhanced deposition within the hair, providing a more stable and even color appearance.
Implementation Method 1
the pH of the hair after rinsing is from about 3.5 to about 6; and wherein the rinsing of the hair causes one or more of the one to four incipient cations to change from neutral to positively charged inside of the hair shaft
Implementation Method 2
Fluorophores provide many desirable effects on hair that cannot be provided by direct dyes and oxidative dyes alike
Data Source
AI summary
Described herein is a hair treatment composition for the hair. The hair treatment composition includes one or more fluorescent compounds and one or more additional ingredients. The one or more fluorescent compounds each include a fluorophore, one or two permanent cations, and one to four incipient cations. The one to four incipient cations are pendant to the core structure and are neutral. The one or more fluorescent compounds enter the hair shaft after the hair treatment composition is applied to the hair. The hair treatment composition has a pH of from about 7 to about 11.