Multilayer Structure Resin Composition Retort Gas Barrier
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Solution Overview
Problem
Existing multilayer structures with polyolefin and EVOH layers face challenges in maintaining gas barrier properties after retort processing, often resulting in defective appearances and insufficient compatibility, leading to issues like gelation, phase separation, and poor thermal stability.
Innovation Solution
A multilayer structure comprising a resin composition layer with polyolefin, a saponified ethylene-vinyl acetate copolymer, and an acid-modified ethylene-vinyl acetate copolymer, where the resin composition contains specific ratios of these components to enhance compatibility and maintain gas barrier properties after retort processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multilayer structure including polyolefin and EVOH layers is reused through melt molding, then waste reduction and economic efficiency are improved, but gelation occurs due to thermal degradation and continuous melt molding becomes difficult
Solution Approach 1:
A compatibility promoter is introduced as an intermediary substance between polyolefin and EVOH layers. This promoter prevents thermal degradation and gelation during melt molding by facilitating compatible interaction between the two polymers, enabling continuous production without degradation issues
Solution Approach 2:
The chemical structure parameters of the polymer layers are modified by incorporating specific compatibility promoters that change the thermal and rheological properties of the multilayer structure, allowing it to withstand repeated melt molding cycles without gelation
2Reliability
If polyolefin and EVOH are combined in a multilayer structure, then barrier properties are improved, but compatibility between the two materials deteriorates causing phase separation and die build-up
Solution Approach 1:
A compatibility promoter acts as a mediator between polyolefin and EVOH layers, preventing phase separation and die build-up by promoting compatible interaction while maintaining the barrier properties of the EVOH layer
Solution Approach 2:
The patent creates a composite multilayer structure where polyolefin and EVOH are combined with a compatibility promoter, forming a stable composite material that maintains both the barrier properties of EVOH and the processability of polyolefin
3Reliability
If EVOH is used in multilayer structures for retort processing, then gas barrier properties are improved, but EVOH loses gas barrier properties under high temperature and high humidity conditions
Solution Approach 1:
The chemical composition parameters of the EVOH layer are modified by adding compatibility promoters that enhance thermal and humidity resistance, allowing the EVOH to maintain its gas barrier properties even under retort processing conditions of high temperature and humidity
4Productivity
If recovery materials are reused in multilayer structures, then waste reduction is improved, but degraded material mixes into molded products causing fish eyes and phase separation foreign matter
Solution Approach 1:
A compatibility promoter is introduced as an intermediary that prevents degraded recovery material from mixing into the molded product by maintaining stable layer separation and preventing fish eyes and phase separation foreign matter during the molding process
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 proposed multilayer structure achieves good gas barrier properties and a defect-free appearance even after retort processing, with improved compatibility and thermal stability, allowing for efficient reuse of recycled materials.
Implementation Method 1
a layer made of a saponified ethylene-vinyl acetate copolymer (hereinafter, may be abbreviated as an EVOH) excellent in barrier properties
Implementation Method 2
improved compatibility and thermal stability, allowing for efficient reuse of recycled materials
Data Source
AI summary
Provided is a multilayer structure, comprising: a layer of a resin composition (A); a layer of a saponified ethylene-vinyl acetate copolymer (B) having an ethylene content of from 20 to 65 mol% and having a degree of saponification of vinyl acetate units of 96% or more; and a layer of polyolefin (C) arranged on one side or both sides of those layers, wherein the resin composition (A) contains polyolefin (D), a saponified ethylene-vinyl acetate copolymer (E) having an ethylene content of from 20 to 65 mol% and having a degree of saponification of vinyl acetate units of 96% or more, and a saponified ethylene-vinyl acetate copolymer (F1) having an ethylene content of from 68 to 98 mol% and having a degree of saponification of vinyl acetate units of 20% or more and/or an acid-modified ethylene-vinyl acetate copolymer (F2) having an ethylene content of from 68 to 98 mol%, the saponified ethylene-vinyl acetate copolymer (E) has a mass ratio [E/(F1 + F2)] of from 0.05 to 30 to a total amount of the saponified ethylene-vinyl acetate copolymer (F1) and the acid-modified ethylene-vinyl acetate copolymer (F2), the polyolefin (D) has the saponified ethylene-vinyl acetate copolymer (E) having an average particle diameter of from 0.1 to 1.8 µm dispersed in a matrix thereof, the layer of the resin composition (A) has a thickness of from 50 to 1000 µm, and the layer of the polyolefin (C) has a thickness of from 25 to 1000 µm. This enables to provide a multilayer structure having good gas barrier.properties after retort processing and a good appearance.