Modified Ethylene-Vinyl Alcohol Copolymer Flexibility Barrier Trade-off
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Solution Overview
Problem
Current ethylene-vinyl alcohol copolymers face challenges in achieving high flexibility, secondary processability, and interlayer adhesion while maintaining excellent barrier properties, leading to increased production costs and environmental concerns, particularly in the production of heat shrink films and stretch blow molded containers.
Innovation Solution
A modified ethylene-vinyl alcohol copolymer with a specific monomer composition and degree of saponification, represented by formula (I), is produced through radical polymerization and saponification, incorporating monomer units with a 1,3-diol structure to enhance flexibility and adhesion, and is used in combination with alkali metal salts and boron compounds to improve interlayer adhesion and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVOH is used to maintain excellent barrier properties, then gas barrier property and flavor retention are improved, but flexibility and secondary processability deteriorate
Solution Approach 1:
The patent changes the chemical structure parameters of EVOH by introducing copolymer units (vinyl acetate and 3,4-dihydroxy-1-butene) to modify the polymer chain flexibility and intermolecular forces, thereby improving flexibility and secondary processability while maintaining barrier properties
Solution Approach 2:
The patent creates a composite polymer system by copolymerizing ethylene, vinyl acetate, and 3,4-dihydroxy-1-butene, combining the barrier properties of EVOH with the flexibility and adhesion benefits of the copolymer units
2Ease of operation
If modified EVOH is obtained by reacting epoxy compound with EVOH in molten state, then flexibility and secondary processability are improved, but production steps and production costs increase
Solution Approach 1:
The patent incorporates the modification units (3,4-dihydroxy-1-butene) directly into the polymer chain during the copolymerization step, performing the modification action in advance during polymerization rather than requiring a separate post-polymerization reaction step
Solution Approach 2:
The patent merges the polymerization process with the modification process by incorporating functional monomers during copolymerization, combining what were previously separate steps (polymerization and modification) into a single integrated process
3Ease of operation
If 3,4-diacetoxy-1-butene is copolymerized to improve stretchability, then flexibility is improved, but polymerization reactivity increases and remaining monomer after polymerization increases
Solution Approach 1:
The patent changes the chemical structure of the diol-containing monomer from 3,4-diacetoxy-1-butene to 3,4-dihydroxy-1-butene, which has different polymerization reactivity characteristics that allow for better control of the copolymerization process and reduced residual monomer
4Strength
If EVOH is laminated with thermoplastic resin via adhesive resin, then interlayer adhesion is improved, but delamination occurs and production complexity increases
Solution Approach 1:
The patent creates a homogeneous interface between layers by incorporating 3,4-dihydroxy-1-butene units that form strong hydrogen bonds with thermoplastic resin, achieving intimate molecular-level adhesion without requiring separate adhesive resin layers
Solution Approach 2:
The patent extracts and eliminates the adhesive resin layer from the multilayer structure by providing inherent adhesion through the modified EVOH copolymer, simplifying the overall structure to fewer layers
5Reliability
If blending multiple EVOHs with different vinyl alcohol contents is done, then gas barrier property is improved, but transparency decreases and management difficulty increases
Solution Approach 1:
The patent changes the approach from blending different EVOHs to copolymerization with controlled composition, maintaining a homogeneous molecular structure that preserves transparency while achieving the desired gas barrier properties through controlled copolymer composition
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 modified copolymer exhibits improved flexibility, secondary processability, and interlayer adhesion, reducing production costs and environmental impact while maintaining excellent barrier properties, making it suitable for various packaging applications, including heat shrink films and stretch blow molded containers.
Implementation Method 1
wherein a content (mol%) of monomer units containing Y and Z based on the total monomer units is from 0.01 to 20 mol%, and a degree of saponification (DS) defined by the following formula (4) is not less than 90 mol%
Implementation Method 2
a modified ethylene-vinyl alcohol copolymer, a method of producing the same, and use of the same
Implementation Method 3
is used in combination with alkali metal salts and boron compounds to improve interlayer adhesion and thermal stability
Implementation Method 4
maintaining excellent barrier properties, making it suitable for various packaging applications
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Provided is a modified ethylene-vinyl alcohol copolymer, wherein the copolymer is represented by a following formula (I), contents (mol%) of a, b, and c based on the total monomer units satisfy following formulae (1) through (3), and a degree of saponification (DS) defined by a following formula (4) is not less than 90 mol%, 18≤a≤55 0.01≤c≤20 100-a+c×0.9≤b≤100-a+c DS=Total Number of Moles of Hydrogen Atoms in XYand Z/Total Number of Moles of XYand Z×100