Aluminoborosilicate Glass Cl–CeO2 Refining for Low Bubbles and Neutral Color
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Solution Overview
Problem
Existing aluminoborosilicate glasses used in pharmaceutical packaging struggle to achieve a neutral white color impression while maintaining a low bubble content and high chemical resistance, particularly due to the yellow tint caused by CeO2 refining agents.
Innovation Solution
A glass composition with specific proportions of SiO2, B2O3, Al2O3, Na2O, K2O, and CaO, incorporating Cl and CeO2 in controlled ranges, along with a weight ratio of Cl to CeO2 not exceeding 10, to achieve a neutral white color and low bubble content, and a hydrolytic resistance exceeding 75% of the HGA1 limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CeO2 is used as a refining agent to reduce bubble content, then the number of bubbles decreases, but the glass develops a yellow color tinge
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration of CeO2 (10-500 ppm) and Cl (75-800 ppm) to achieve optimal refining效果 while minimizing yellow discoloration. It also controls the weight ratio of Cl to CeO2 not exceeding 10, transforming the refining process from a粗放 approach to a precise parameter-controlled process that balances bubble removal with color neutrality.
Solution Approach 2:
The patent introduces Cl as an intermediary substance that works synergistically with CeO2 to enhance refining effectiveness. By adding Cl in controlled amounts (with weight ratio Cl/CeO2 ≤ 10), the system achieves better bubble removal with reduced CeO2 dosage, thereby minimizing the yellow color tinge while maintaining low bubble content.
2Illumination intensity
If the glass composition is optimized for neutral white color, then color neutrality is achieved, but bubble content increases
Solution Approach 1:
The patent creates a composite refining system combining CeO2 and Cl in specific proportions within the glass matrix. This composite approach leverages the oxidizing power of CeO2 and the refining capability of Cl to achieve both color neutrality and low bubble content simultaneously, overcoming the limitation of using either agent alone.
Solution Approach 2:
The patent systematically adjusts multiple parameters including CeO2 concentration (10-500 ppm), Cl concentration (75-800 ppm), and their weight ratio (≤10), along with base glass composition (SiO2: 69-75 wt.%, B2O3: 6-12 wt.%, Al2O3: 5-8 wt.%, Na2O: 5-9 wt.%) to find the optimal balance point where both color neutrality and low bubble content are achieved.
3Manufacturing precision
If traditional refining agents (As, Sb) are used to achieve low bubble content, then bubble content decreases, but safety concerns arise
Solution Approach 1:
The patent replaces toxic, persistent refining agents (As, Sb) with safer alternatives (CeO2, Cl) that are effective at much lower concentrations and pose minimal safety risks. CeO2 and Cl can be easily removed or decomposed during processing, leaving no harmful residues, thus eliminating the toxicity issue while maintaining refining effectiveness.
Solution Approach 2:
The patent converts the potential harm of using refining agents into a benefit by selecting CeO2 and Cl that provide effective refining without the toxic side effects of traditional agents. The controlled use of these substances at low concentrations (CeO2: 10-500 ppm, Cl: 75-800 ppm) transforms the refining process from a hazardous operation to a safe one, maintaining bubble removal effectiveness while eliminating toxicity concerns.
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 glass exhibits excellent visual appearance with a neutral white color impression, low bubble content, and high chemical resistance, suitable for pharmaceutical containers without lamp ring formation, while maintaining high transparency and cost-efficiency.
Implementation Method 1
refining agents comprising oxides of As and/or Sb have been used. For safety reasons new refining agents have been developed, in particular Cl-based refining agents. An alternative refining agent is CeO2
Implementation Method 2
the glass exhibits a hydrolytic resistance exceeding 75% of the HGA1 limit according to ISO 720:2020(E)
Data Source
Figure 1
AI summary
The present invention relates to an aluminoborosilicate glass with excellent visual appearance, and to a method of producing such glass. The invention also relates to the use of the glass, in particular for pharmaceutical packaging, for example pharmaceutical containers such as glass vials, glass ampoules, glass cartridges or glass syringes.