PVOH EVOH Barrier Coatings High Alcohol Solvent Stability
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Solution Overview
Problem
Conventional barrier coatings comprising polyvinyl alcohol and ethylene vinyl alcohol co-polymers dissolved in aqueous mixtures typically do not tolerate higher proportions of lower alcohols, limiting their stability and drying speed, and fail to effectively prevent the migration of nuisance substances through packaging materials.
Innovation Solution
A barrier coating composition comprising polyvinyl alcohol and/or ethylene vinyl alcohol co-polymer dissolved in an aqueous mixture with at least 45% by weight of one or more lower alcohols, having a solids content greater than 7.5% and a coating viscosity of less than 30 seconds flow time, which allows for faster drying and improved barrier properties against gases and nuisance substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If higher proportions of lower alcohols are added to aqueous coating formulations containing PVOH and EVOH polymers, then drying speed is improved, but solution stability deteriorates
Solution Approach 1:
The patent changes the concentration parameter of lower alcohols in the aqueous solution from conventional 20-30% to 45% or higher, while simultaneously adjusting the polymer type to low molecular weight PVOH and EVOH copolymers. This parameter change enables the formulation to tolerate higher alcohol content without precipitation, achieving faster drying speed while maintaining solution stability through optimized polymer-solvent composition ratios.
2Speed
If higher proportions of lower alcohols are added to aqueous coating formulations containing PVOH and EVOH polymers, then drying speed is improved, but barrier performance deteriorates
Solution Approach 1:
The patent creates a composite coating system combining low molecular weight PVOH polymers with EVOH copolymers in a high-alcohol aqueous solution. This composite formulation achieves synergistic effects where the polymer combination maintains gas barrier performance (preventing migration of nuisance substances) while the high alcohol content enables fast drying. The composite material approach resolves the contradiction between drying speed and barrier reliability.
3Stability of the object's composition
If conventional PVOH and EVOH polymer formulations are used, then solution stability is maintained, but drying speed deteriorates
Solution Approach 1:
The patent fundamentally changes the alcohol concentration parameter from conventional 20-30% to 45% or higher in the aqueous polymer solution. This parameter change directly accelerates drying speed by increasing the volatile content, while the specific selection of low molecular weight PVOH and EVOH copolymers ensures the formulation remains stable and does not precipitate, thus resolving the contradiction between stability and drying speed.
4Stability of the object's composition
If conventional PVOH and EVOH polymer formulations are used, then solution stability is maintained, but ability to prevent migration of nuisance substances deteriorates
Solution Approach 1:
The patent formulates a composite coating system combining low molecular weight PVOH with EVOH copolymers in a high-alcohol aqueous solution. This composite structure provides enhanced barrier properties that effectively prevent migration of nuisance substances (such as ink components and odors) through the packaging material, while maintaining solution stability. The synergistic interaction between the polymer components creates a more effective barrier than conventional single-polymer formulations.
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 enables the formulation of fast-drying, high-solids barrier coatings that effectively block the ingress of gases and nuisance substances, suitable for food and pharmaceutical packaging, while maintaining compatibility with in-line printing processes and ensuring storage stability for extended periods.
Implementation Method 1
A barrier coating composition comprising a poly vinyl alcohol and/or ethylene vinyl alcohol co-polymer dissolved in an aqueous mixture which comprises at least 45% by weight of one or more lower alcohols
Implementation Method 2
effectively block the ingress of gases and nuisance substances
Implementation Method 3
provide a barrier to the migration of nuisance substances
Data Source
Figure 1
AI summary
Barrier coatings with efficacy against oxygen and nuisance substances are described that comprise lower molecular weight PVOH and EVOH co-polymers, when coated on flexible substrates. Coating formulations comprising these co-polymers advantageously tolerate moderate to higher proportions of organic solvents in aqueous blends, and thus produce faster drying coating formulations.