Stabilizing Oligodynamic Metal Aqueous Compositions
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Solution Overview
Problem
Antimicrobial cleansing compositions containing oligodynamic metals like silver face issues with destabilization, discolouration, and uneven distribution, especially under high pH, heat, and sunlight exposure, leading to instability and limited shelf life.
Innovation Solution
An aqueous composition with reduced free alkali content, incorporating an oligodynamic metal, a chelating agent, and a salt of an organic acid, which stabilizes the metal ions and maintains uniform distribution, thereby controlling discolouration and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oligodynamic metal like silver is included in antimicrobial cleansing compositions, then antimicrobial effectiveness is improved, but stability and colour retention deteriorate under high pH, heat and sunlight exposure
Solution Approach 1:
The patent introduces an intermediary substance (stabilizer or chelating agent) that mediates between the oligodynamic metal and the harsh environment (high pH, heat, sunlight). This intermediary protects the metal ions from destabilization and oxidation, preventing discolouration and agglomeration while maintaining antimicrobial activity. The stabilizer acts as a buffer that absorbs the harmful effects of extreme conditions on the metal ions.
Solution Approach 2:
The patent modifies the chemical parameters of the composition by controlling pH levels, adding specific stabilizing agents, and adjusting metal ion concentration. By optimizing these parameters - particularly maintaining appropriate pH ranges and using specific stabilizers - the composition achieves both antimicrobial effectiveness and stability under varying climatic conditions.
2Quantity of substance
If oligodynamic metal is used at low concentrations (ppm or ppb levels), then antimicrobial activity is maintained, but uniform distribution within the composition matrix becomes difficult to ensure
Solution Approach 1:
The patent uses dispersing agents and surfactants as intermediaries to facilitate uniform distribution of low-concentration metal ions throughout the composition matrix. These intermediaries prevent metal ion aggregation and ensure even dispersion, making it possible to achieve uniform distribution at trace concentrations (ppm or ppb levels) without compromising antimicrobial activity.
3Object-generated harmful factors
If free alkali content is high in the composition, then cleansing effectiveness is improved, but destabilisation and discolouration of oligodynamic metal increases
Solution Approach 1:
The patent introduces buffering agents and pH stabilizers as intermediaries that allow the composition to maintain high cleansing effectiveness (through appropriate alkali content) while protecting the oligodynamic metal from destabilization. These intermediaries buffer the pH to prevent extreme alkalinity from causing metal precipitation or discolouration.
Solution Approach 2:
The patent optimizes the pH parameter by controlling free alkali content within a specific range and adding pH-stabilizing agents. This parameter optimization ensures that the composition maintains sufficient alkalinity for effective cleansing while preventing the metal ions from undergoing destabilizing reactions that lead to discolouration and reduced stability.
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 significantly improves the stability and colour retention of oligodynamic metal compositions, ensuring uniform distribution in soap bars and extending the shelf life of antimicrobial products, even under varying climatic conditions.
Implementation Method 1
a chelating agent; wherein the composition comprises 0.01 wt% to 2 wt% of a salt of an organic acid
Implementation Method 2
stability of alkaline aqueous compositions containing an oligodynamic metal can be markedly improved and tendency to discolour can also be controlled by lowering the free alkali content of the composition by the addition of an organic acid
Data Source
AI summary
Disclosed is an aqueous composition having viscosity from 1 to 100 cP at 20 °C, said composition comprising: (i) an oligodynamic metal or ions thereof; (ii) a chelating agent; and, (iii) free alkali less than 1 wt%, wherein said composition comprises 0.01 wt% to 2 wt% of a salt of an organic acid; pH of the composition is from 9 to 12 and molar ratio of said oligodynamic metal to said chelating agent is 1:0.25 to 1:10. The composition provides a robust solution for technical problems of discolouration and instability.