Ion-Exchange Glass Composition Balancing Temperability and Resistance
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Solution Overview
Problem
Existing glasses lack a combination of high chemical prestressability, good alkali and hydrolytic resistance, acid resistance, scratch resistance, and impact strength, particularly for thin and thinnest glasses used in pharmaceutical packaging and touch-sensitive displays, with a coefficient of thermal expansion that meets regulatory standards.
Innovation Solution
A targeted combination of stoichiometric glasses with specific constituent phases, including reedmergnerite, albite, orthoclase, natrosilite, sodium metasilicate, parakeldyshite, narsarsukite, disodium zinc silicate, cordierite, and danburite, optimized for ion transport and resistance, using a conversion matrix to ensure amorphous form and desired properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass-like albite is used as main constituent to achieve high chemical prestressability, then ion exchange depth is improved, but alkali resistance deteriorates
Solution Approach 1:
The patent uses a composite glass system combining multiple phases (reedmergnerite, albite, orthoclase, natrosilite, sodium metasilicate, parakeldyshite, narsarsukite, disodium zinc silicate, cordierite, and danburite) to achieve both high chemical prestressability and good alkali resistance. This composite approach allows the glass to benefit from the high sodium ion mobility of albite for ion exchange while the other phases contribute to overall chemical stability and resistance.
2Reliability
If high proportion of aluminum is used to achieve high sodium ion mobility, then chemical temperability is improved, but acid resistance deteriorates
Solution Approach 1:
The patent employs a multi-phase composite glass where aluminum is distributed across different phases (reedmergnerite, albite, orthoclase, cordierite, danburite) rather than concentrated in one phase. This distribution allows sufficient aluminum content for sodium ion mobility while other phases (particularly those with lower aluminum content like natrosilite and disodium zinc silicate) maintain acid resistance.
Solution Approach 2:
Different phases in the composite glass have different local compositions optimized for specific functions: reedmergnerite and albite provide high sodium ion mobility, while other phases like cordierite and danburite provide structural stability and chemical resistance. This local differentiation of properties within the composite resolves the contradiction between temperability and acid resistance.
3Reliability
If chemical prestressability is enhanced for thin glasses, then ion exchange depth is improved, but scratch resistance deteriorates
Solution Approach 1:
The composite glass structure with multiple phases provides both the ion exchange capability for chemical prestressability and the structural integrity for scratch resistance. The diverse phases create a more robust glass network that can undergo ion exchange while maintaining surface hardness and resistance to mechanical damage.
4Weight of moving object
If thin glass design is used to reduce weight, then device weight is reduced, but chemical stability deteriorates
Solution Approach 1:
The multi-phase composite glass composition enables thin glass designs to maintain high chemical stability despite reduced thickness. The synergistic combination of phases provides enhanced chemical resistance that compensates for the reduced material quantity in thin applications.
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 provides glasses with enhanced alkali resistance, hydrolytic resistance, acid resistance, scratch resistance, and impact strength, meeting ISO standards and thermal expansion requirements, suitable for modern flat glass drawing processes.
Implementation Method 1
chemical tempering by exchange of sodium with potassium
Data Source
AI summary
The present invention relates to glasses, such as e.g. thin or thinnest glasses, but also to glasses for the production of tubular glass, carpules and syringes as well as other pharmaceutical vessels. The glasses are characterized by a high chemical prestressability (tem-perability) with very well alkali, hydrolytic and/or acid resistance as well as an advantageous coefficient of thermal expansion. The glass has a composition characterized by the following constituent phases: 0-60 mol % reedmergnerite; 20-60 mol % albite; 0-30 mol % orthoclase; 0-20 mol % natrosilite; 0-20 mol % sodium metasilicate; 0-20 mol % parakeldyshite; 0-20 mol % narsarsukite; 0-20 mol % disodium zinc silicate; 0-21 mol % cordierite; and 0-20 mol % danburite. A quotient of a coefficient of thermal expansion of the glass multiplied by 1000 (in ppm/K) and the product of a pH value and a removal rate in alkaline environment (in mg/(dm23 h)) according to ISO 695 is at least 9.0.