Gas Barrier Coatings Using Silicate-Clay-Polymer Composites
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Solution Overview
Problem
Existing gas barrier coatings, particularly those using metal silicates, face challenges such as loss of oxygen barrier properties at high temperatures, brittleness, and opacity, as well as inefficiencies when using polymer emulsions, which often result in high oxygen permeation values.
Innovation Solution
A composition comprising a water-soluble alkali metal silicate, a nanoparticulate clay mineral, and a film-forming polymer emulsion, with specific weight ratios and molar ratios of alkali metal oxide to silicon dioxide, applied as a coating to provide improved oxygen barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal silicate coatings are used to provide gas barrier properties, then oxygen blocking ability is improved, but the coating becomes brittle and loses barrier properties when flexed
Solution Approach 1:
The patent applies composite materials by combining metal silicates with polymer matrices (such as polyvinyl alcohol, cellulose derivatives, or acrylic polymers) to create a coating that integrates the oxygen-blocking capability of metal silicates with the flexibility and toughness of polymers. This composite structure prevents the brittleness issue while maintaining the gas barrier properties.
2Reliability
If inorganic layers are deposited to provide barrier properties, then oxygen transmission is reduced, but the laminate becomes opaque and cannot display contents
Solution Approach 1:
The patent applies local quality by using nanoscale metal silicate particles (1-100 nm) dispersed within the polymer matrix. At this nanoscale, the particles provide effective oxygen barrier properties through tortuous path mechanisms while being sufficiently small to not scatter visible light significantly, thus maintaining the transparency of the coating and allowing customers to see the package contents.
3Reliability
If pure metal silicate coatings are applied to achieve low oxygen permeability, then barrier performance is improved, but the coating effloresces when exposed to atmosphere
Solution Approach 1:
The patent applies the intermediary principle by using a polymer matrix as a mediating medium that binds the metal silicate particles together and protects them from direct atmospheric exposure. The polymer coating acts as an intermediate layer that prevents the efflorescence phenomenon (where metal silicates form powdery crystalline deposits on the surface) while still allowing the metal silicate particles to provide their oxygen barrier function.
4Stability of the object's composition
If polymer solutions are used with metal silicates to form barrier coatings, then coating homogeneity is improved, but the process is limited to specific polymer types and requires solvents
Solution Approach 1:
The patent applies parameter changes by transitioning from solvent-based polymer solutions to water-based polymer emulsions. This changes the dispersion medium parameter, allowing the use of a broader range of polymers that are available as water-based emulsions (such as acrylic emulsions, vinyl emulsions, and other water-dispersible polymers) while maintaining film homogeneity through proper emulsion formulation and processing.
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 achieves significantly reduced oxygen permeation rates, maintaining barrier performance across varying humidity levels and temperatures, while being transparent and flexible, thus suitable for packaging sensitive materials like food and pharmaceuticals.
Implementation Method 1
Gas barrier coatings, having, in particular, the ability to block the passage of oxygen
Implementation Method 2
an emulsion of film-forming polymer
Data Source
AI summary
A composition having good gas barrier properties can be prepared from a metal silicate, clay and a polymer emulsion, provided that the proportions of these components are maintained such that the silicate comprises at least 70% by weight of the solids in the composition, and the clay and polymer each comprise at least 1% by weight of the total solids in the composition.