Boron-Free Glass Composition for Pharmaceutical Packaging Durability
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Solution Overview
Problem
Existing glass compositions used in pharmaceutical packaging lack both chemical durability and mechanical strength, particularly in complex geometries and thin walls, leading to breakage issues and safety concerns.
Innovation Solution
A glass composition with a high silica content (>70 mol.%) and specific ratios of alkali oxide, alumina, and alkaline earth oxides, which are free from boron, to enhance chemical durability and susceptibility to chemical strengthening by ion exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass is used for pharmaceutical packaging, then chemical durability is improved, but mechanical strength deteriorates leading to breakage
Solution Approach 1:
The glass composition is pre-formulated with specific oxide ratios (SiO2: 70-80 mol%, Al2O3: 5-15 mol%, alkali oxide: 5-20 mol%) to inherently possess both chemical durability and susceptibility to ion exchange strengthening. This preliminary compositional design enables subsequent mechanical strengthening without compromising chemical stability.
Solution Approach 2:
The patent modifies the chemical composition parameters by controlling the ratio of alkali oxide to alumina (Y:X > 1) and limiting boron content to achieve optimal balance between chemical durability and ion exchangeability. These parameter changes enable the glass to undergo chemical strengthening while maintaining chemical resistance.
2Strength
If thermal tempering is used to strengthen glass, then mechanical strength is improved, but it cannot be applied to complex geometries and thin walls
Solution Approach 1:
The patent replaces thermal tempering (mechanical/thermal process) with chemical tempering via ion exchange. The glass is treated in a molten salt bath where alkali ions are exchanged with larger ions, inducing compressive stress. This chemical process can penetrate complex geometries and thin walls that thermal tempering cannot effectively treat.
Solution Approach 2:
A molten salt bath serves as an intermediary medium to transfer strengthening ions to the glass surface. The salt bath enables ion exchange without direct thermal contact, allowing complex geometries to be strengthened uniformly while maintaining chemical durability through controlled ion penetration.
3Strength
If chemical tempering is used to strengthen glass, then mechanical strength is improved, but chemical durability deteriorates
Solution Approach 1:
The glass composition is precisely controlled with SiO2 (70-80 mol%) to provide chemical resistance, while alkali oxide (5-20 mol%) and alumina (5-15 mol%) are added in specific ratios to enable ion exchange. The constraint on boron content ( < 4 mol%) ensures both chemical durability and susceptibility to chemical strengthening, resolving the contradiction between these two properties.
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 proposed glass composition achieves improved chemical and mechanical durability, allowing for effective ion exchange strengthening, increased resistance to hydrolytic and acidic degradation, and enhanced mechanical performance, making it suitable for pharmaceutical packaging.
Implementation Method 1
The stress is introduced by submerging the article in a molten salt bath. As ions from the glass are replaced by larger ions from the molten salt, a compressive stress is induced in the surface of the glass.
Implementation Method 2
the glass used in pharmaceutical packaging must have adequate chemical durability so as not to affect the stability of the pharmaceutical compositions contained therein
Data Source
AI summary
The embodiments described herein relate to chemically and mechanically durable glass compositions and glass articles formed from the same. In embodiments, the glass composition may include 74-78 mol. % SiO2; X mol. % Al2O3, wherein X is 5-7; alkaline earth oxide comprising MgO and CaO, wherein: CaO is 0.1-1.0 mol. %; MgO is 4-7 mol. %; and a ratio (CaO (mol. %)/(CaO (mol. %)+MgO (mol. %)) is less than or equal to 0.5. The glass composition may further include Y mol. % alkali oxide, wherein the alkali oxide comprises 9-13 mol. % Na2O and less than or equal to 0.4 mol. % of a fining agent. The glass composition may be free of boron and compounds of boron.