Gas-Barrier Coating Material for Thermoplastic Films
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Solution Overview
Problem
Current methods for forming gas-barrier layers on thermoplastic resin films, such as those used in food packaging, face challenges including high gas permeability, environmental concerns due to organic solvents, high energy requirements for heat treatment, and degradation under high humidity and temperature conditions.
Innovation Solution
A coating material comprising a polyalcohol polymer, a polycarboxylic acid polymer, and a divalent or higher-valent metal compound with a poorly water-soluble component is applied to form a gas-barrier layer, which maintains excellent gas-barrier properties under high humidity and temperature without repeated heat treatments or the use of organic solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDC is used to form a gas-barrier layer, then gas-barrier property is improved, but environmental harm increases due to generation of poisonous gases at incineration
Solution Approach 1:
The patent changes the chemical composition parameters by replacing PVDC with a copolymer of vinyl alcohol and carboxylic acid (where the carboxylic acid component is 10-60 mol%). This compositional parameter change enables the material to maintain gas-barrier properties while eliminating poisonous gas generation during incineration, thus resolving the environmental harm issue.
Solution Approach 2:
The patent adopts a water-soluble copolymer coating that can be applied as a thin layer on thermoplastic resin films. This coating provides effective gas-barrier protection during use but can be easily disposed of without generating harmful emissions, making it an environmentally friendly alternative to PVDC.
2Object-generated harmful factors
If PVA is used to form a gas-barrier layer, then environmental compatibility is improved, but gas-barrier property degrades under high humidity conditions
Solution Approach 1:
The patent creates a composite material by copolymerizing vinyl alcohol with carboxylic acid groups. The carboxylic acid component (10-60 mol%) provides hydrophobic character and maintains gas-barrier properties under high humidity, while the vinyl alcohol component ensures water solubility and environmental compatibility. This composite structure resolves the contradiction between environmental friendliness and humidity resistance.
Solution Approach 2:
The patent introduces local hydrophobic regions through the carboxylic acid groups within the copolymer structure. These local hydrophobic zones prevent water penetration and maintain gas-barrier properties in humid environments, while the overall copolymer remains water-soluble and environmentally compatible.
3Reliability
If heat treatment at high temperature is applied to cross-link PVA, then gas-barrier property is improved, but energy consumption increases and substrate deformation occurs
Solution Approach 1:
The patent changes the chemical structure parameters by incorporating carboxylic acid groups into the copolymer. These carboxylic acid groups enable cross-linking reactions at lower temperatures compared to conventional PVA cross-linking, thereby reducing energy consumption while maintaining effective gas-barrier properties.
Solution Approach 2:
The patent replaces the mechanical/thermal cross-linking process (which requires high temperature and energy) with a chemical cross-linking mechanism inherent to the copolymer structure. The carboxylic acid groups naturally facilitate cross-linking at lower temperatures, substituting the need for intensive thermal processing and reducing energy consumption.
4Reliability
If heat treatment at high temperature is applied to cross-link PVA, then gas-barrier property is improved, but substrate deformation occurs
Solution Approach 1:
The patent changes the cross-linking temperature parameter by utilizing the carboxylic acid groups in the copolymer structure. These groups enable cross-linking to occur at lower temperatures that do not cause deformation of the thermoplastic resin substrate, thereby maintaining substrate integrity while achieving effective gas-barrier properties.
Solution Approach 2:
The patent replaces high-temperature thermal cross-linking (which causes substrate deformation) with a chemical cross-linking mechanism based on carboxylic acid groups. This chemical approach enables cross-linking at lower temperatures that preserve the thermoplastic resin substrate's structural integrity while still achieving the desired gas-barrier performance.
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 effectively enhances the gas-barrier property of the multilayer body, preventing gas penetration even under long-term high temperature and high humidity conditions without degrading the substrate or requiring excessive energy, thus addressing environmental and economic drawbacks of existing methods.
Implementation Method 1
a coating material for forming a gas-barrier layer... is applied to a thermoplastic resin film to form a gas-barrier layer
Implementation Method 2
these thermoplastic resin films are high in the permeability for a gas such as oxygen... a polyvinylidene chloride (hereinafter abbreviated as 'PVDC') layer having a high gas-barrier property
Data Source
AI summary
Disclosed is a coating material for forming a gas barrier. The coating material includes a polyalcohol polymer, a polycarboxylic acid polymer, and a divalent or higher-valent metal compound whose surface is coated with a poorly water-soluble component, or alternatively a monovalent metal compound whose surface is coated with a poorly water-soluble component and a divalent or higher-valent metal compound whose surface is coated with a poorly water-soluble component. By applying this coating material to a plastic substrate layer, a gas-barrier multilayer body having a gas-barrier layer formed thereon is obtained.