EVOH Multilayer Packaging for High-Pressure Gas Barrier Retention
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Solution Overview
Problem
Existing high-pressure processing methods for multilayer structures with an ethylene-vinyl alcohol copolymer (EVOH) layer and olefin resin layer fail to improve the gas barrier property due to moisture absorption by EVOH, leading to deterioration.
Innovation Solution
A production method involving a multilayer structure with an EVOH layer formed from a resin composition with a saponification degree greater than 99.7 mol% and an olefin resin layer less than 100 μm thick, processed under 200 MPa and 20°C for at least 3 minutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-pressure processing is applied to multilayer structure with EVOH layer, then content sterilization effect is achieved, but the EVOH layer absorbs moisture and gas barrier property deteriorates
Solution Approach 1:
The patent changes the saponification degree parameter of EVOH to greater than 99.7 mol% (higher than conventional 95-98 mol%), which fundamentally alters the molecular structure to reduce hydroxyl group content and eliminate moisture absorption during high-pressure processing
Solution Approach 2:
The patent creates a composite multilayer structure combining high-saponification EVOH layer with olefin resin layers (polyethylene, polypropylene, or polybutene-1), where the olefin resin layers provide moisture barrier protection while the EVOH layer provides gas barrier protection, achieving synergistic effect
2Object-generated harmful factors
If EVOH layer with high saponification degree is used, then gas barrier property is improved, but moisture absorption occurs during high-pressure processing
Solution Approach 1:
The patent precisely controls the saponification degree parameter to greater than 99.7 mol%, which creates a molecular structure with reduced hydrophilic character, thereby improving gas barrier properties while minimizing moisture absorption tendency during high-pressure processing
3Strength
If olefin resin layer thickness is increased, then structural integrity is improved, but gas barrier property deteriorates
Solution Approach 1:
The patent assigns different functional qualities to different layers: the olefin resin layers (thickness 1-100 μm) provide structural integrity and moisture barrier, while the thin EVOH layer (thickness 1-30 μm) provides gas barrier function, optimizing each layer's thickness for its specific purpose
Solution Approach 2:
The patent designs a composite structure where olefin resin layers and EVOH layer work synergistically, with the olefin resin providing mechanical strength and the EVOH providing gas barrier, achieving both structural integrity and 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 method enhances the gas barrier property by compressing the amorphous portion of EVOH, increasing its crystallinity and improving the multilayer structure's resistance to gas permeation.
Implementation Method 1
the gas barrier property of the multilayer structure can be improved by compressing an amorphous portion of the EVOH layer through high-pressure processing
Implementation Method 2
high-pressure processing processes are widely employed, because the contents are substantially free from deterioration
Data Source
AI summary
A production method for a high-pressure processed multilayer structure to be used for packages for foods and the like is provided. The production method includes: preparing a multilayer structure including an ethylene-vinyl alcohol copolymer (EVOH) layer formed from a resin composition containing an ethylene-vinyl alcohol copolymer having a saponification degree of greater than 99.7 mol % as a main component and an olefin resin layer having a thickness of less than 100 μm; and high-pressure processing the multilayer structure under a pressure of not lower than 200 MPa in an atmosphere at not lower than 20° C.