Silver-Containing Alkali Silicate Coating for Antimicrobial Efficacy
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Solution Overview
Problem
There is a need for articles with improved antimicrobial properties, particularly for surfaces that can harbor microbes, bacteria, and viruses, such as touch screens, where existing technologies have not effectively addressed the transfer and inhibition of microbial growth.
Innovation Solution
The development of antimicrobial articles with a silver-containing alkali silicate coating on a substrate, which includes curing a mixture of alkali silicate with silver nitrate and alkali nitrate, providing antimicrobial efficacy of greater than or equal to 90% according to EPA Test Method for Efficacy of Copper Alloy Surfaces as a Sanitizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silver-containing coating is applied to impart antimicrobial properties, then antimicrobial efficacy is improved, but the complexity of the coating process and composition increases
Solution Approach 1:
The patent combines multiple functions into a single coating layer: the alkali silicate provides both the structural base and the ion exchange capability, while silver ions are incorporated during the ion exchange process. This merging eliminates the need for separate antimicrobial agent application steps and simplifies the overall coating structure while maintaining high antimicrobial efficacy
Solution Approach 2:
The alkali silicate coating acts as an intermediary between the substrate and the antimicrobial environment. It provides a controlled release mechanism for silver ions, mediating the interaction between the coating and microorganisms. This intermediary function allows the coating to maintain stability while actively combating microbial growth
2Reliability
If silver is added to the coating to enhance antimicrobial properties, then antimicrobial effectiveness is improved, but the risk of silver reduction and coating degradation increases
Solution Approach 1:
The patent carefully controls the oxidation state parameters of the coating environment. By maintaining the silicate in an oxidizing environment and controlling the release of silver ions, the coating prevents silver reduction while preserving antimicrobial effectiveness. The ion exchange process parameters are optimized to ensure silver remains in the active ionic form
Solution Approach 2:
The alkali silicate coating creates an oxidizing environment that prevents silver reduction. The silicate structure acts as an oxidizing medium that maintains silver in the +1 oxidation state, preventing formation of metallic silver particles. This accelerated oxidation approach ensures long-term stability of the antimicrobial coating
3Reliability
If the coating is made more aggressive to improve antimicrobial action, then microbial inhibition is enhanced, but the transparency and aesthetic properties of the substrate may deteriorate
Solution Approach 1:
The patent applies the antimicrobial function locally at the coating-substrate interface and at the molecular level within the coating structure. The silver ions are distributed at the molecular level within the silicate network, providing antimicrobial activity without creating visible aggregates. This local quality approach maintains bulk optical transparency while achieving effective microbial inhibition
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 silver-containing alkali silicate coating achieves significant antimicrobial efficacy, effectively inhibiting microbial growth on surfaces, maintaining effectiveness over time, and maintaining transparency and durability while reducing non-bridging oxygen to prevent silver reduction.
Implementation Method 1
contacting the coating with an antimicrobial medium comprising silver nitrate and an alkali nitrate
Implementation Method 2
curing the coating at a temperature from greater than or equal to about 300° C. to less than or equal to about 620° C. for a duration of greater than or equal to about 15 minutes to less than or equal to about 120 minutes
Implementation Method 3
Silver ions interact with a wide range of molecular processes within microorganisms resulting in a range of effects from inhibition of growth and loss of infectivity to cell death (cytotoxicity)
Data Source
AI summary
An antimicrobial article having a substrate, and a coating on a surface of the substrate. The coating includes a silver-containing alkali silicate. The antimicrobial article has an antimicrobial efficacy of greater than or equal to about 90.0% according to EPA Test Method for Efficacy of Copper Alloy Surfaces as a Sanitizer. The coating may further include at least one of a boron-containing compound and an aluminum-containing compound. A method for forming antimicrobial articles includes coating a substrate with a mixture comprising an alkali silicate; curing the coating at a temperature from greater than or equal to about 300° C. to less than or equal to about 620° C. for a duration of greater than or equal to about 15 minutes to less than or equal to about 120 minutes; and contacting the coating with an antimicrobial medium comprising silver nitrate and an alkali nitrate.