Optical Glass Composition for Precision Press Molding
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Solution Overview
Problem
High refractive index, low dispersion glasses used in precision press molding face challenges with thermal stability and moldability, leading to decreased productivity due to increased crystallization and thermal degradation, which affects the quality and quantity of optical elements produced.
Innovation Solution
The development of an optical glass composition characterized by specific molar percentages of B2O3, La2O3, ZnO, Gd2O3, and other components, which balances refractive index, dispersion, and thermal stability to enhance moldability and reduce the risk of glass fusion with the pressing mold, thereby improving the productivity of precision press molding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If large quantities of rare earth components (La2O3, Gd2O3) are incorporated to achieve high refractive index and low dispersion, then the refractive index increases and dispersion decreases, but thermal stability decreases and crystallization increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar percentages of rare earth components (La2O3: 5-30%, Gd2O3: 0-20%) and other glass components (B2O3: 5-45%, ZnO: 10-40%, etc.) to optimize the balance between achieving high refractive index/low dispersion properties and maintaining thermal stability. This systematic parameter optimization prevents crystallization while ensuring moldability during precision press molding.
2Reliability
If glass transition temperature is lowered to prevent thermal degradation of pressing mold, then thermal degradation is reduced, but productivity drops due to decreased viscosity at liquidus temperature making molding difficult
Solution Approach 1:
The patent resolves this contradiction by changing the chemical composition parameters of the glass, specifically incorporating ZnO (10-40 mol%) and controlling the ratio of B2O3 (5-45 mol%) to achieve an optimal balance. This composition adjustment allows the glass to have sufficiently low glass transition temperature to protect the mold while maintaining high enough viscosity at liquidus temperature for successful molding.
Solution Approach 2:
The patent uses a composite glass material system combining multiple components (B2O3, ZnO, La2O3, Gd2O3, and other oxides) where each component contributes specific properties. This composite approach enables simultaneous achievement of low glass transition temperature for mold protection and appropriate viscosity for moldability, resolving the contradiction between mold reliability and productivity.
3Adaptability or versatility
If high refractive index and low dispersion are achieved through glass composition, then optical functionality increases, but moldability decreases due to increased crystallization tendency
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar composition ranges of glass components. Specifically, La2O3 is set at 5-30 mol% and Gd2O3 at 0-20 mol% to achieve the desired optical properties (high refractive index, low dispersion) while keeping crystallization tendency under control. The B2O3 content is optimized at 5-45 mol% to maintain appropriate viscosity and moldability during precision press molding.
Data Source
AI summary
An optical Glass characterized by comprising, denoted as molar percentages: B2O5—5 to 45 percent; SiO2—0 to 6 percent (excluding 6 percent); Li2O, Na2O, K2O in total—0 to 3 percent; ZnO—10 to 40 percent; La2O3—5 to 30 percent; Gd2O3—1 to 20 percent; and ZrO2, TaO2, TiO2, Nb2O5, WO3, and Bi2O3 in total—2.5 to 20 percent. The cation ratio of the Ti4+ content relative to the total content of Zr4+, Ta5+, Ti4+, Nb5+, W6+, and Bi3+ is 0.30 or lower; in that the temperature Tp at which a viscosity of 107.2 dPa·s is exhibited is 706° C. or lower. The refractive index nd and the Abbé number v(nu)d satisfy all of the following relations (I) to (IV): 34.0≦vd<40 (I); nd≧1.87 (II); nd≧2.245−0.01×vd (III) and nd≦2.28−0.01×vd (IV).