Borosilicate Glass Composition for Pharmaceutical Containers
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Solution Overview
Problem
Borosilicate glass for pharmaceutical containers faces challenges in maintaining chemical durability and hydrolytic resistance, especially after thermal treatments, due to the evaporation of B2O3 or Na2O, leading to the formation of heterogeneous layers and the generation of insoluble precipitates, which affect the stability of aqueous-based medicaments.
Innovation Solution
A borosilicate glass composition with a molar ratio of (Na2O + K2O + Li2O - Al2O3)/B2O3 between 0.315 and 0.350, excluding BaO, and with specific ratios of SiO2, Al2O3, and B2O3, is developed to enhance chemical durability and hydrolytic resistance, reducing the evaporation of alkali metal oxides and maintaining stability during thermal treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If B2O3 or Na2O is used in borosilicate glass for pharmaceutical containers, then the glass can be processed by local heating with a burner, but B2O3 or Na2O evaporates during heating and condenses on the inner surface to form a heterogeneous layer, lowering chemical durability and hydrolytic resistance
Solution Approach 1:
The invention changes the compositional parameters of the glass by strictly controlling the ratio of (Na2O+K2O+Li2O-Al2O3)/B2O3 to be 0.315-0.350 and setting SiO2/B2O3/(Na2O+K2O+Li2O) < 1.6, which prevents excessive evaporation of B2O3 or Na2O during local heating while maintaining processability
Solution Approach 2:
The invention creates a composite glass system combining multiple oxide components (SiO2, B2O3, Al2O3, and controlled amounts of Na2O, K2O, Li2O, CaO, MgO) where each component plays a specific role in balancing processability and chemical durability, with the synergistic effect preventing heterogeneous layer formation
2Reliability
If the amount of K2O is increased to improve hydrolytic resistance, then hydrolytic resistance improves, but K2O is easily evaporated during burner heating, still causing formation of heterogeneous layer and elution of B2O3 or Na2O
Solution Approach 1:
The invention changes the compositional parameters by setting specific ranges for K2O content (0.1-5.0 mol%) and more importantly controlling the ratio SiO2/B2O3/(Na2O+K2O+Li2O) to be less than 1.6, which balances the volatility of alkali metal oxides with the network structure stability, preventing excessive evaporation while maintaining hydrolytic resistance
Solution Approach 2:
The invention introduces B2O3 as an intermediary component that forms a stable network structure with SiO2 and Al2O3, which acts as a barrier to reduce the evaporation rate of K2O and other alkali metal oxides during heating, thereby preventing heterogeneous layer formation while maintaining hydrolytic resistance
3Reliability
If BaO is included in the glass composition, then the glass can achieve certain properties, but barium-feldspar crystals precipitate during glass melting reducing productivity, and Ba ions react with sulfate ions in aqueous-based medicament to generate insoluble precipitate
Solution Approach 1:
The invention extracts BaO from the glass composition entirely, replacing it with a combination of other oxide components (particularly B2O3, Al2O3, and controlled amounts of CaO and MgO) that can achieve the desired chemical stability without causing crystal precipitation or harmful reactions with medicament components
Solution Approach 2:
The invention changes the compositional parameters by setting CaO content to 0-0.5 mol% and MgO content to 0-2.0 mol%, and controlling the ratio (Na2O+K2O+Li2O-Al2O3)/B2O3 to be 0.315-0.350, which achieves chemical stability through a different compositional pathway that avoids the problems associated with BaO
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
This composition effectively prevents the formation of heterogeneous layers, reduces the generation of flakes, and maintains excellent chemical durability and hydrolytic resistance, even after thermal treatments, ensuring the stability and integrity of the glass container for pharmaceutical use.
Implementation Method 1
At the time of performing the heating with a burner, B2O3 or Na2O in the glass is evaporated and condensed on an inner surface of a pharmaceutical container
Implementation Method 2
Chemical durability and hydrolytic resistance are high so as not to contaminate an aqueous-based medicament present in the container
Data Source
Figure 1
AI summary
To provide a borosilicate glass for a pharmaceutical container which does not include BaO, has excellent chemical durability and hydrolytic resistance, and in which excellent chemical durability and hydrolytic resistance may be maintained even after various thermal treatments at the time of converting process. There is provided a borosilicate glass for a pharmaceutical container including SiO2, Al2O3, B2O3, and R2O (R is one or more kinds selected from Li, Na, and K) as essential components, in which a content of CaO is equal to or greater than 0 and smaller than 0.5 mol%, a value of (Na2O + K2O + Li2O - Al2O3)/B2O3 is 0.315 to 0.350 in terms of a molar ratio, and BaO is not substantially included.