EVOH Resin Composition for Fuel Containers
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Solution Overview
Problem
Current resin compositions based on ethylene-vinyl alcohol copolymers face challenges in balancing impact resistance, secondary processability, and barrier properties while maintaining productivity, with existing solutions either increasing production costs or compromising on transparency and gas barrier properties.
Innovation Solution
A resin composition comprising a modified ethylene-vinyl alcohol copolymer and an unmodified ethylene-vinyl alcohol copolymer, with specific molecular content ratios and a high degree of saponification, along with the inclusion of alkali metal salts, to enhance impact resistance, secondary processability, and barrier properties without increasing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease 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 increase and production costs rise
Solution Approach 1:
The invention incorporates flexible chain structures directly into the EVOH polymer chain during the polymerization stage, rather than modifying the polymer after production. This preliminary action integrates the flexibility-enhancing function into the base resin, eliminating the need for separate modification steps and reducing production costs while maintaining improved secondary processability
Solution Approach 2:
The invention uses a specific copolymer structure containing flexible chain segments as an intermediary between the rigid EVOH backbone and the desired flexibility. These flexible chain segments act as internal modifiers that provide the required flexibility and secondary processability without requiring external modifying agents or additional production steps
2Strength
If stretching at higher draw ratio is performed to improve mechanical strength and deepen drawing shape, then impact resistance and formability are improved, but the high modulus of elasticity of EVOH makes this difficult
Solution Approach 1:
The invention changes the molecular structure parameters of EVOH by incorporating flexible chain segments through copolymerization. This structural modification reduces the modulus of elasticity and enables higher draw ratios during stretching, while simultaneously improving impact resistance through the energy-absorbing flexible chains
Solution Approach 2:
The invention creates a composite-like structure within the polymer chain itself, combining rigid EVOH segments with flexible chain segments. This internal composite structure provides both the strength of EVOH and the flexibility needed for high draw ratio stretching and improved impact resistance
3Reliability
If multiple EVOHs with different vinyl alcohol contents are blended to improve gas barrier property and mechanical properties, then processability is improved, but transparency decreases and gas barrier property management becomes difficult
Solution Approach 1:
The invention applies local quality by incorporating flexible chain segments at specific locations within the polymer chain structure rather than blending different EVOHs. This localized modification maintains the overall homogeneity and transparency of the resin while providing the desired gas barrier properties and processability improvements in specific regions
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 resin composition achieves excellent impact resistance, secondary processability, and barrier properties while maintaining productivity, making it suitable for various applications including fuel containers and packaging materials.
Implementation Method 1
a resin composition containing a modified ethylene-vinyl alcohol copolymer and an unmodified ethylene-vinyl alcohol copolymer
Data Source
Figure 1~2
AI summary
A resin composition comprising a modified ethylene-vinyl alcohol copolymer (A) and an unmodified ethylene-vinyl alcohol copolymer (B), wherein the modified ethylene-vinyl alcohol copolymer (A) is represented by a following formula (I), contents (mol%) of a, b, and c based on the total monomer units satisfy following formulae (1) to (3), and a degree of saponification is not less than 80 mol%, thereby providing a resin composition that is excellent in a barrier property, impact resistance, and secondary processability and moreover excellent in productivity. 18≤a≤55 0.01≤c≤20 100−a+c×0.9≤b≤100−a+c