Guanidine Mediator Enhances Direct Dye Wash Fastness
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Solution Overview
Problem
Direct dyes for keratin fibers suffer from unsatisfactory dyeing properties and low wash fastness, making it difficult to achieve intense and long-lasting color.
Innovation Solution
A kit-of-parts comprising two or three separate compositions: Composition A with direct dyes and an alkalizing agent, Composition B with guanidine compounds, lipophilic compounds, and optionally oxidizing agents at a pH of 1 to 6, and Composition C with persalts or persulfate salts, which are mixed to create a ready-to-use dyeing solution with a pH of 7 to 12 for application on keratin fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If direct dyes are used for keratin fibers, then the dyeing process causes less damage to fibers and provides better color predictability, but the dyeing properties and wash fastness are unsatisfactory
Solution Approach 1:
The patent introduces guanidine compounds as intermediary substances that facilitate the bonding between direct dyes and keratin fibers. The guanidine compounds act as a mediator that enhances the interaction between the dye and fiber, improving wash fastness without causing the harsh effects of oxidative dyes. This resolves the contradiction by providing a third component that enables better dye fixation while maintaining the gentleness of direct dyes.
Solution Approach 2:
The patent modifies the chemical environment by controlling pH levels and introducing specific chemical compounds (guanidine derivatives) to change the conditions under which direct dyes interact with keratin fibers. By adjusting parameters such as pH and chemical composition, the dyeing properties and wash fastness are significantly improved while maintaining the non-damaging characteristics of direct dyes.
2Reliability
If oxidative dyes are used for keratin fibers, then the dyeing properties and color intensity are improved, but the process causes more damage to the fibers and the color predictability is reduced
Solution Approach 1:
The guanidine compounds serve as a gentle intermediary that enables strong dye-fiber bonding without the harsh oxidizing conditions. This mediator approach achieves the color intensity and dyeing properties of oxidative dyes while avoiding their damaging effects on keratin fibers.
Solution Approach 2:
The patent converts the typically harmful oxidative process into a beneficial one by using guanidine compounds that provide strong dye fixation without fiber damage. The chemical reactivity that normally causes damage in oxidative dyes is harnessed in a controlled manner through guanidine-mediated bonding, turning potential harm into benefit.
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 enhances color intensity and wash fastness of direct dyes on keratin fibers, improving dyeing efficiency and storage stability by using guanidine compounds to penetrate and lock the dyes into hair fibers.
Implementation Method 1
guanidine compounds to penetrate and lock the dyes into hair fibers
Implementation Method 2
guanidine compounds to penetrate and lock the dyes into hair fibers
Implementation Method 3
one separate composition is composition A comprising one or more direct dye(s) and one or more alkalizing agent(s)
Implementation Method 4
one or more oxidizing agent(s)
Implementation Method 5
Guanidine compounds are disclosed to catalyze polymerization of oxidative dyes
Data Source
AI summary
The present invention is directed to the provision of a kit-of-parts, a dyeing composition, and a method for dyeing keratin fibres. The kit comprises separate compositions A and B and optionally separate composition C. Composition A comprises a direct dye and an alkalising agent. The aqueous composition B comprises guanidine and/or its salts together with one or more lipophilic compounds and/or one or more thickening polymers. Composition C comprises a persalt and/or persulfate salt. A method for dyeing keratin fibres comprises mixing compositions A and B, and optionally C, to yield a ready-to-use composition with pH in the range of 7 to 12. Composition B may be used for enhancing colour intensity and/or wash fastness of a direct dye on keratin fibres with the provision that it is mixed with composition A directly prior to application.