Display Cover Glass Substrate with Antibacterial Ion Diffusion
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Solution Overview
Problem
Glass substrates for display cover glasses face challenges in achieving high strength, antibacterial properties, and transparency due to excessive diffusion of silver ions, which leads to coloring and reduced visible transmittance.
Innovation Solution
A glass substrate with a surface compressive stress layer and a silver ion diffusion layer, where the transmittance ratio at 428 nm to 650 nm is maintained at 0.95 or higher, and the silver amount is controlled between 0.2 to 100 μg/cm² at a depth of 40 μm, is produced using chemical tempering and heat treatment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass is treated with molten salt containing silver nitrate and potassium nitrate to replace sodium ions with potassium ions and silver ions, then antibacterial properties and high strength are improved, but silver ions diffuse excessively and form colloids that color the glass and reduce visible transmittance
Solution Approach 1:
The patent changes the chemical composition parameters of the glass, specifically limiting Na2O to 0.1-15 mol% and K2O to 2-10 mol%, while controlling silver ion diffusion through heat treatment temperature (300-475°C) and time parameters to prevent excessive diffusion and colloid formation, thereby maintaining both antibacterial properties and visible transmittance
Solution Approach 2:
The patent creates a localized antibacterial substance-containing layer on the glass surface through controlled silver ion diffusion, where the silver concentration is highest at the surface and decreases with depth, providing antibacterial properties where needed while minimizing overall silver content to prevent coloring
2Strength
If treatment is conducted to obtain desired strength, then bending strength is improved, but silver ions are excessively diffused and form colloids that color the glass
Solution Approach 1:
The patent applies partial action by conducting heat treatment at temperatures of 300-475°C for controlled durations to diffuse silver ions only to the extent needed for antibacterial effectiveness, rather than excessive diffusion that would cause colloid formation and coloring, achieving sufficient strength without harmful side effects
Solution Approach 2:
The patent ensures continuous useful action by maintaining silver ions in a diffused but controlled state within the glass matrix, where they continuously provide antibacterial properties without reaching concentrations that would cause colloid formation and coloring during the service life of the glass
3Reliability
If the proportion of compound capable of donating M+ to antibacterial substance is increased, then antibacterial properties are improved, but transparency is reduced
Solution Approach 1:
The patent optimizes the proportion parameter by limiting K2O to 2-10 mol% and controlling silver content through heat treatment conditions, achieving the right balance where sufficient antibacterial substances are present for effectiveness while maintaining transparency by preventing excessive silver colloid formation
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 results in a glass substrate with high strength, excellent antibacterial properties, and high visible transmittance, preventing coloring caused by silver colloid, making it suitable for display devices.
Implementation Method 1
treating glass containing sodium with a molten salt of silver nitrate and potassium nitrate to replace sodium ions contained in glass with both of potassium ions and silver ions
Implementation Method 2
silver ions are diffused quickly as compared with potassium ions, and when treatment is conducted to obtain a desired strength, silver ions will excessively be diffused in glass
Implementation Method 3
a glass substrate having increased strength by a chemical tempering method is commonly used
Data Source
AI summary
To provide a glass substrate for a display cover glass not only having excellent strength and antibacterial properties but also having a high transparency and a high visible transmittance suitable as a cover glass for a display device. A glass substrate for a display cover glass, which comprises a surface compressive stress layer and an antibacterial substance-containing layer formed on the glass substrate surface, characterized by having a ratio (T1/T2) of the transmittance T1 at a wavelength of 428 nm to the transmittance T2 at a wavelength of 650 nm of the glass substrate of at least 0.95, and a transmittance at a wavelength of 428 nm of at least 86% when the thickness of the glass substrate is from 0.1 to 3.0 mm.