Antimicrobial Glass with Compressive Stress Layer
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Solution Overview
Problem
Antimicrobial glass articles face challenges in maintaining strength and resistance to discoloration when exposed to harsh conditions, such as elevated temperatures and humidity, which can lead to unsightly discoloration and render them unsuitable for use.
Innovation Solution
The development of antimicrobial glass articles with a compressive stress layer and an antimicrobial silver-containing region, where the compressive stress layer extends inward from the surface to a specific depth and the silver-containing region has a controlled depth and concentration to maximize antimicrobial efficacy while minimizing discoloration, along with optional additional layers for enhanced properties like reflection resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antimicrobial glass articles are exposed to harsh conditions (elevated temperatures, humidity), then antimicrobial properties are maintained, but discoloration occurs and strength decreases
Solution Approach 1:
The patent modifies the chemical composition parameters of the glass, specifically incorporating zinc oxide (1-10 wt%) and boron oxide (5-20 wt%) along with controlling the SiO2/Na2O ratio, to enhance the glass's resistance to harsh conditions while maintaining antimicrobial properties and preventing discoloration
Solution Approach 2:
The patent creates a composite glass material system combining multiple oxides (SiO2, B2O3, ZnO, Al2O3, Na2O, K2O, CaO, MgO) with specific ratio constraints, where each component contributes to different properties: B2O3 and ZnO for chemical resistance and strength, SiO2 for structural framework, and alkali oxides for workability and antimicrobial efficacy
2Reliability
If antimicrobial glass articles are exposed to harsh conditions (elevated temperatures, humidity), then antimicrobial properties are maintained, but discoloration occurs
Solution Approach 1:
The patent adjusts compositional parameters including adding ZnO (1-10 wt%) and B2O3 (5-20 wt%) which form a protective network structure that prevents silver ion reduction and discoloration while maintaining antimicrobial activity under harsh conditions
Solution Approach 2:
The patent converts the potential harmful effect of silver ions (which can cause discoloration when reduced) into a beneficial stable silver ion-releasing system by using the glass matrix with specific oxide compositions to maintain silver in the oxidized state, thus preventing discoloration while preserving antimicrobial properties
3Reliability
If silver concentration is increased to maximize antimicrobial efficacy, then antimicrobial properties improve, but discoloration resistance decreases
Solution Approach 1:
The patent optimizes the silver concentration parameter to 0.01-5 wt% and combines it with ZnO and B2O3 in specific ratios, creating a balanced system where sufficient silver provides antimicrobial efficacy while the zinc and boron components prevent silver reduction and discoloration
Solution Approach 2:
The patent creates a composite system where silver ions are embedded in a glass matrix containing ZnO and B2O3, which together form a protective environment that maintains silver in the oxidized state, thus allowing higher silver concentrations for antimicrobial efficacy without proportionally increasing discoloration risk
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 antimicrobial glass articles exhibit improved strength, resistance to discoloration, and high antimicrobial efficacy, achieving at least a 5 log reduction in bacterial concentrations under testing conditions, while maintaining optical transparency and mechanical performance.
Implementation Method 1
forming a compressive stress layer that extends inward from a surface of the glass substrate to a first depth
Implementation Method 2
an antimicrobial silver-containing layer or region that extends inward from the surface of the glass substrate to a second depth
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
Described herein are various antimicrobial glass articles that have improved strength and resistance to discoloration. The improved antimicrobial glass articles described herein generally include a glass substrate with a compressive stress layer and an antimicrobial silver-containing region that each extend inward from a surface of the glass substrate to a specific depth. In some embodiments, the compressive stress layer has a compressive stress at the surface of about 500 MPa or greater and the compressive stress decreases monotonically from the surface into the depth of the glass substrate. Methods of making and using the glass articles are also described and include forming a compressive stress layer and forming an antimicrobial silver-containing region by preferentially exchanging a plurality of silver cations in a silver-containing medium for a specific plurality of first cations ions in the glass substrate.