Sol-Gel Coating Reduces Alkali Ion Release in Glass Containers
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Solution Overview
Problem
Existing methods for coating the internal surfaces of containers, particularly glass bottles, are complex, expensive, and not always reliable, often requiring toxic or polluting substances and introducing unwanted elements that can contaminate products, especially in the pharmaceutical and cosmetic industries, and do not effectively prevent the release of alkaline ions which can react with contents.
Innovation Solution
A process using a solution with water, a molecular precursor with alkoxyl groups, and an acid catalyst, such as citric acid, applied to the container's internal face, which gels and solidifies at room temperature, reducing ion release and allowing for a durable, neutral coating without the need for harmful chemicals or extensive processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If sulfur dioxide and difluoroethane treatments are used to prevent alkali migration, then the release of alkali ions is reduced, but the process complexity and cost increase significantly
Solution Approach 1:
The invention changes the chemical parameters of the coating solution by using sol-gel precursors (silane or silica-based compounds) that transform into a vitrified protective layer through controlled hydrolysis and condensation reactions. This chemical parameter change enables effective alkali ion barrier properties without requiring complex sulfur-based treatment processes
Solution Approach 2:
The sol-gel coating process uses inexpensive precursor materials (silane or silica compounds) that can be applied as a thin solution layer and then transformed into a durable protective coating. This replaces expensive and complex sulfur-based treatments with a more economical and simpler coating approach
2Object-affected harmful factors
If sulfur or fluorine hot treatment is applied to glass bottles, then alkali migration is prevented, but toxic and polluting products must be handled
Solution Approach 1:
The invention converts the naturally occurring alkali ions in glass, which cause harmful migration, into a beneficial protective mechanism. The sol-gel coating acts as a barrier that prevents alkali ion release without requiring toxic sulfur or fluorine treatments. The coating itself is formed from harmless precursors that undergo beneficial chemical transformation
Solution Approach 2:
The sol-gel coating creates an inert barrier layer between the glass and the product, preventing harmful interactions. This inert protective layer is formed from silane or silica precursors that create a chemically stable, non-reactive barrier without requiring toxic treatment atmospheres
3Temperature
If conventional Sol-Gel coating is applied after bottle formation, then cold coating at room temperature is achieved, but the coating does not leave contents in contact with the Sol-Gel layer for proper protection
Solution Approach 1:
The invention applies the sol-gel coating to the interior surface of the bottle after formation but before filling with contents. This preliminary action allows the coating to be properly applied and then cured in place, ensuring the protective layer is present when the bottle is filled and stored, unlike external coatings that cannot protect internal contents
4Strength
If organometallic Sol-Gel elements (Zr, Al, Ti) are used for coating, then adhesion is improved, but harmful residues are introduced into the product
Solution Approach 1:
The invention changes the material composition parameters by using purely silane or silica-based precursors instead of organometallic compounds containing Zr, Al, or Ti. This parameter change maintains the sol-gel coating's adhesion and protective properties while eliminating harmful metal residues from the final product
Solution Approach 2:
The invention uses simple, inexpensive silane or silica precursors that can be completely transformed into a stable vitrified coating without leaving harmful residues. These precursor materials are safer and more suitable for pharmaceutical and cosmetic applications compared to organometallic alternatives
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 process achieves a significant reduction in ion release from the container, improving hydrolytic resistance and allowing for the storage of biocompatible products without contamination, while being simpler, less expensive, and more adaptable to various container shapes and materials.
Implementation Method 1
a solution is formed containing a solvent, water, a molecular precursor comprising alkoxyl groups, and an acid as a catalyst
Implementation Method 2
The glassy material, based on silica, is obtained without melting, by polymerization of at least one molecular precursor... then a more or less long gelation step with evaporation of the solvent until complete solidification
Implementation Method 3
Such a coating then modifies the surface properties, both physical and/or chemical, of this other material (when it comes into contact with a product)... The release of ions from the container is very limited
Data Source
Figure 1~3
Figure 4A~4B
AI summary
The present invention relates to a method for producing a layer for coating the inner surface of a container and a glass or plastic container obtained by said method, wherein said container is suitable for containing products biocompatible with humans and/or animals. The method includes: forming a solution containing a solvent, water, a molecular precursor comprising alkoxy groups and an acid as a catalyst, - mixing said solution to initiate hydrolysis and condensation, - applying the resulting solution onto at least one portion of the inner surface of the container, while the solution is in the process of gelling, - the resulting applied solution is then dried at a temperature for a predetermined time, before curing. The acid is citric acid, and the invention is characterized in that said citric acid is at a concentration of less than 6 mol/l, and in that the solution comprises less than 1.5 units of precursor for each volume unit of acid.