Gas Barrier Laminate Coating for High-Humidity Packaging
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Solution Overview
Problem
Existing gas barrier laminates using PVA polymers suffer from deteriorating gas barrier properties in high humidity atmospheres due to moisture absorption, and methods involving polycarboxylic acid polymers require strict moisture control to prevent premature reaction, which can damage substrates like polyolefins and complicate the process.
Innovation Solution
A coating liquid containing a carboxy group-containing polymer with a number average molecular weight of 100,000 or less, polyvalent metal-containing particles, a surfactant, and an organic solvent, allowing for ion-crosslinking without strict moisture control, forming a gas barrier laminate with high humidity resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVA polymers are used as gas barrier layers, then gas barrier properties are improved in low humidity atmospheres, but gas barrier properties deteriorate in high humidity atmospheres due to moisture absorption
Solution Approach 1:
The patent uses a composite material system consisting of PVA polymer combined with inorganic lamellar compounds (such as montmorillonite) to create a gas barrier layer that maintains low oxygen permeability even in high humidity environments. The inorganic lamellar compounds fill the spaces between PVA chains and prevent moisture-induced loosening of hydrogen bonds, thereby stabilizing the gas barrier properties.
Solution Approach 2:
The patent modifies the molecular weight parameters of the PVA polymer, specifying a number average molecular weight of 100,000 or less, to optimize the balance between gas barrier properties and moisture resistance. This parameter optimization enables the PVA-based gas barrier layer to maintain effectiveness in high humidity atmospheres without requiring cross-linking or high-temperature treatment.
2Reliability
If polycarboxylic acid polymer and polyvalent metal compound are mixed in coating liquid, then ion-crosslinking can occur, but premature reaction and precipitate formation occur due to moisture
Solution Approach 1:
The patent extracts the polyvalent metal compound from the coating liquid formulation, replacing it with inorganic lamellar compounds that do not require ion-crosslinking with polycarboxylic acid polymers. This eliminates the risk of premature reaction and precipitate formation while still achieving high gas barrier properties through the physical barrier effect of the lamellar structure.
Solution Approach 2:
The patent introduces inorganic lamellar compounds as intermediary materials that mediate between the polymer matrix and the gas barrier function, eliminating the need for direct chemical interaction between polycarboxylic acid polymer and polyvalent metal compounds. The lamellar compounds serve as physical barriers without requiring moisture-sensitive cross-linking reactions.
3Reliability
If cross-linked structure is formed by heat treatment at high temperature, then gas barrier properties are improved, but substrate is damaged
Solution Approach 1:
The patent replaces the need for high-temperature cross-linking treatment with a formulation approach using low molecular weight PVA polymers and inorganic lamellar compounds that achieve effective gas barrier properties through simple coating and drying processes, avoiding thermal damage to temperature-sensitive substrates.
Solution Approach 2:
The patent substitutes the thermal-mechanical cross-linking process with a chemical-formulation approach where the desired gas barrier properties are achieved through molecular-level interactions and physical barriers in the coating formulation itself, eliminating the need for high-temperature heat treatment.
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 coating liquid enables the production of a gas barrier laminate with excellent barrier properties under high humidity conditions without requiring stringent moisture control, suitable for various substrates including polyolefins, and simplifies the production process.
Implementation Method 1
it has been proposed a method including forming a layer containing a polycarboxylic acid polymer, such as a polymer of a polyacrylic acid, and ion-crosslinking the polycarboxylic acid polymer with polyvalent metal ions
Implementation Method 2
Layers made of PVA polymers become highly dense due to hydrogen bonding of the hydroxyl group, and exhibit high gas barrier properties in low humidity atmospheres
Implementation Method 3
layers made of PVA polymers suffer from significant deterioration in gas barrier properties in high humidity atmospheres due to absorbing moisture and thereby loosening the hydrogen bonding
Data Source
AI summary
High gas barrier properties can be achieved without requiring strict control for preventing entry of moisture. A coating liquid for producing a gas barrier laminate contains a carboxy group-containing polymer, polyvalent metal-containing particles, a surfactant, and an organic solvent. In the coating liquid, the carboxy group-containing polymer has a number average molecular weight of 100,000 or less.