Polyion Complex Particles With Multi-pKa Acid for Stable Films
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Solution Overview
Problem
Existing polyion complex particle dispersions are unstable, leading to precipitation issues, and methods for forming films from these particles are difficult, especially on keratin substrates like skin, and achieving a relatively thick film is challenging.
Innovation Solution
A composition comprising cationic and anionic polymers, non-polymeric acids with multiple pKa values, and a physiologically acceptable volatile medium, which can be applied to form a stable dispersion and a thick film on keratin substrates by drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polyion complex particle dispersion is used to form a film on a keratin substrate, then the film can be prepared in-situ without spin coating, but the dispersion is unstable and particles precipitate
Solution Approach 1:
A non-ionic surfactant is introduced as an intermediary substance to stabilize the polyion complex particle dispersion. The surfactant adsorbs at the particle interface, preventing aggregation and precipitation while allowing the dispersion to remain stable during film formation on keratin substrates.
Solution Approach 2:
The pH of the dispersion is adjusted to optimize stability. By controlling the pH within a specific range, the electrostatic repulsion between particles is enhanced, preventing precipitation while maintaining the ability to form films on keratin substrates without spin coating.
2Ease of operation
If conventional spraying methods are used to apply polyion complex solutions, then in-situ film formation is possible, but controlling the amount sprayed and achieving thick films is difficult
Solution Approach 1:
The polyion complex particles are pre-formed and stabilized in a dispersion with controlled concentration and stability characteristics. This preliminary preparation allows the dispersion to be applied by simple methods such as spraying or dipping, where the stable particles settle and form uniform thick films without requiring precise control of spray amount.
Solution Approach 2:
The dispersion is formulated with specific particle size distribution and concentration gradients that allow different regions of the applied coating to contribute differently to film formation, enabling thick and uniform film deposition through simple application methods.
3Ease of manufacture
If polyion complex particles are used to simplify film preparation, then spin coating is avoided, but the particles tend to precipitate from the dispersion
Solution Approach 1:
A non-ionic surfactant serves as a mediator between the polyion complex particles and the dispersion medium, providing steric stabilization that prevents particle aggregation and precipitation, thereby ensuring reliable dispersion stability while maintaining ease of film manufacture.
Solution Approach 2:
The dispersion is formulated as a composite system containing polyion complex particles, non-ionic surfactant, and appropriate solvents in optimized ratios. This composite formulation provides both the ease of film preparation from particle dispersions and the reliability of long-term stability without precipitation.
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 provides a stable dispersion and enables the formation of a thick, water-resistant cosmetic film that can be easily removed under alkaline conditions, offering cosmetic benefits such as odor absorption, UV shielding, and skin protection.
Implementation Method 1
comprising: (a) at least one particle comprising at least one cationic polymer, at least one anionic polymer selected from polysaccharides, and at least one non-polymeric acid having two or more pKa values or salt(s) thereof selected from the group consisting of terephthalylidene dicamphor sulfonic acid and salts thereof (Mexoryl SX), Yellow 6 (Sunset Yellow FCF), and a mixture thereof; and (b) at least one physiologically acceptable volatile medium
Data Source
AI summary
The present invention relates to a composition according to the present invention comprises: (a) at least one particle comprising at least one cationic polymer, at least one anionic polymer, and at least one non-polymeric acid having two or more pKa values or salt(s) thereof; and (b) at least one physiologically acceptable volatile medium. The composition according to the present invention is stable, and can have a variety of cosmetic functions. For example, the composition according to the present invention can prepare a film which can have cosmetic effects such as absorbing or adsorbing malodor, changing the appearance of a keratin substrate such as skin, changing the feel to the touch of the keratin substrate, and/or protecting the keratin substrate from, for example, dirt or pollutants.