High-Transparency Glass Composition Reducing Iron Oxide Absorption
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Solution Overview
Problem
High-transparency glass applications face challenges with light absorption in the visible region due to iron ions, particularly divalent iron (Fe2+), leading to decreased luminance and color unevenness, and it is difficult to reduce iron content to match acrylic plates' transparency without compromising melting conditions and bubble quality.
Innovation Solution
A glass composition with controlled iron oxide content, specific oxide ratios, and a bubble disappearance-starting temperature of 1485°C or lower, which reduces divalent iron content and maintains high fining action at lower temperatures, ensuring low redox and improved bubble quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass melting is performed at higher temperature to improve fining action and bubble quality, then bubble quality is improved, but redox increases leading to higher light absorption and lower transparency
Solution Approach 1:
The invention changes the chemical composition parameters of the glass to achieve a bubble disappearance-starting temperature of 1485°C or lower. This is accomplished by controlling the content of specific oxides (SiO2: 50-81%, Al2O3: 1-20%, B2O3: 0-5%, Li2O+Na2O+K2O: 5-20%, MgO+CaO+SrO+BaO: 5-27%) and iron oxide (1-500 ppm), which allows the glass to maintain low redox and high transparency while achieving sufficient fining action at lower melting temperatures
Solution Approach 2:
The invention creates a composite glass system combining multiple oxide components in specific proportions. The synergistic effect of these components (silica, alumina, boron, alkali metals, alkaline earth metals) produces a glass composition that simultaneously achieves low melting temperature, high fining action, and low iron content for maximum transparency
2Object-affected harmful factors
If glass melting is performed at lower temperature to reduce redox and improve transparency, then light absorption is reduced, but fining action decreases leading to poor bubble quality
Solution Approach 1:
The invention modifies the glass composition parameters to lower the bubble disappearance-starting temperature to 1485°C or below. This enables effective fining action and bubble removal at lower melting temperatures, allowing the glass to maintain low redox (0-25%) and high transparency without compromising bubble quality
Solution Approach 2:
The invention optimizes the local chemical environment by controlling the content of specific oxide components. The balanced composition of network formers (SiO2, B2O3), network modifiers (alkali and alkaline earth metals), and intermediates (Al2O3) creates localized conditions that promote bubble disappearance at lower temperatures while maintaining overall glass stability and transparency
3Object-affected harmful factors
If iron content is reduced to match acrylic plate transparency, then transparency is improved, but it becomes substantially difficult to achieve under industrial manufacturing constraints
Solution Approach 1:
The invention sets the iron oxide content parameter to 1-500 ppm, which is achievable through standard industrial purification processes. This parameter range provides sufficient transparency improvement while remaining feasible for industrial manufacturing, unlike the extremely low iron contents required to match acrylic plates
Solution Approach 2:
The invention controls the redox parameter to 0-25% by optimizing the glass composition and melting conditions. This parameter control, combined with the iron content reduction to 1-500 ppm, achieves transparency levels that are substantially difficult to obtain through iron content reduction alone, while remaining industrially manufacturable
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 achieves reduced light absorption in the visible region, maintaining high transparency and luminance while allowing for lower melting temperatures, thus improving product quality and bubble quality without increasing redox.
Implementation Method 1
A main factor of the light absorption is an iron ion contained as an impurity. The iron ion exists as a divalent one (Fe2+) and a trivalent one (Fe3+) in a glass but particularly problematic one is Fe2+ that has broad absorption in the wavelength of 490 to 780 nm.
Implementation Method 2
Since it is known that the redox increases as the melting condition of the glass becomes higher temperature due to the influence of heat reduction, glass melting at a lower temperature is preferable for redox lowering. On the other hand, when the melting temperature of the glass is lowered, fining at melting remarkably decreases and bubble quality of the glass to be produced cannot be maintained.
Data Source
AI summary
The present invention provides a high-transparency glass having a high fining action at a low temperature and capable of achieving redox lowering more than before. The present invention relates to a glass containing 1 to 500 ppm of a total iron oxide (t-Fe2O3) in terms of Fe2O3, having a redox ([divalent iron (Fe2+) in terms of Fe2O3]/[total (Fe2++Fe3+) of divalent iron (Fe2+) and trivalent iron (Fe3+) in terms of Fe2O3]) of 0% or more and 25% or less, containing, as expressed by mass percentage based on oxides, 50 to 81% of SiO2, 1 to 20% of Al2O3, 0 to 5% of B2O3, 5 to 20% of Li2O+Na2O+K2O, and 5 to 27% of MgO+CaO+SrO+BaO, and having a bubble disappearance-starting temperature (TD) of 1485° C. or lower.