EVOH Resin Composition for Stable Melt Molding and Microplastic Resistance
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Solution Overview
Problem
Existing ethylene-vinyl alcohol copolymers (EVOHs) suffer from poor thermal stability, leading to aggregate formation during melt molding and are prone to breaking down into microplastics when exposed to heat, light, or outdoor conditions, without adequate consideration for long-term durability and environmental impact.
Innovation Solution
A resin composition comprising ethylene-vinyl alcohol copolymers with specific amounts of carboxylic acid units and lactone ring units at the polymer ends, combined with aluminum ions, and optionally other additives like fatty acid aluminum salts, cinnamic acid components, polyamides, thermoplastic elastomers, antioxidants, and inorganic particles, to enhance thermal stability and resistance to microplastic degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ratio of carboxylic acid units and lactone ring units at polymer ends is kept low (0.12 mol% or less), then long-run workability at melt molding is improved, but thermal stability deteriorates and aggregates are generated during heat treatment
Solution Approach 1:
The invention changes the parameter of end-unit ratio from being minimized (0.12 mol% or less) to being controlled within a specific range (0.12-0.60 mol%). This parameter change allows sufficient end units to interact with aluminum ions for thermal stability while preventing excessive aggregation that would harm workability
Solution Approach 2:
Aluminum ions are introduced as an intermediary substance that interacts with carboxylic acid units and lactone ring units at polymer ends. This intermediary forms complexes that stabilize the polymer structure during heat treatment and molding, resolving the thermal stability issue without requiring high end-unit ratios
2Stability of the object's composition
If the ratio of carboxylic acid units and lactone ring units is increased to improve thermal stability, then aggregate generation is reduced, but heat/light resistance deteriorates
Solution Approach 1:
The invention optimizes the end-unit ratio parameter to a balanced range (0.12-0.60 mol%) rather than maximizing it. This optimized parameter level provides sufficient thermal stability while maintaining heat/light resistance by preventing excessive end-unit content that would compromise long-term durability
Solution Approach 2:
Aluminum ions serve as a mediator that enables thermal stability at moderate end-unit ratios. The aluminum ion complexes provide the necessary thermal stabilization without requiring high concentrations of carboxylic acid units and lactone ring units, thereby preserving heat/light resistance
3Reliability
If conventional EVOH is used without sufficient end units, then gas barrier properties are maintained, but the material breaks down into microplastics under outdoor conditions
Solution Approach 1:
Aluminum ions act as a protective intermediary that stabilizes the polymer structure against environmental degradation. The aluminum ion complexes at polymer ends prevent chain scission and microplastic formation during outdoor exposure, while maintaining the intact polymer structure needed for gas barrier properties
Solution Approach 2:
The invention applies preliminary stabilization by incorporating aluminum ions that preemptively protect against thermal and environmental degradation. This preliminary anti-action prevents the polymer from breaking down into microplastics during outdoor use, addressing the degradation issue before it occurs
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 composition inhibits aggregate formation during melt molding and improves heat/light resistance, reducing the likelihood of breaking down into microplastics, while maintaining the properties of EVOHs without altering their structure.
Implementation Method 1
containing: an ethylene-vinyl alcohol copolymer (A); and an aluminum ion (B), wherein at least a part of the ethylene-vinyl alcohol copolymer (A) has, at a polymer end, at least one of a carboxylic acid unit (I) and a lactone ring unit (II)... a content (b) of the aluminum ion (B) per gram of the ethylene-vinyl alcohol copolymer (A) is 0.002 μmol/g or more and 0.17 μmol/g or less
Implementation Method 2
improving the thermal stability, or in other words, inhibiting aggregates which are generated in heat treatment and mold processing... enables obtaining a molded product having sufficient heat/light resistance and being unlikely to break down into microplastics
Implementation Method 3
a molded product having sufficient heat/light resistance and being unlikely to break down into microplastics after being discarded
Data Source
AI summary
Provided are: a resin composition which inhibits the generation of aggregates at the time of melt molding and enables obtaining a molded product which has sufficient heat/light resistance and is unlikely to break down into microplastics after being discarded, the above-mentioned characteristics being sufficiently improved compared to a resin composition obtained using the same ethylene-vinyl alcohol copolymer (EVOH), and the like. The resin composition contains: an ethylene-vinyl alcohol copolymer (A); and an aluminum ion (B), wherein at least a part of the ethylene-vinyl alcohol copolymer (A) comprises, at a polymer end, at least one of a carboxylic acid unit (I) and a lactone ring unit (II), a total content (i+ii) of the carboxylic acid unit (I) and the lactone ring unit (II) per gram of the ethylene-vinyl alcohol copolymer (A) is 14 μmol/g or more and 78 μmol/g or less, and a content (b) of the aluminum ion (B) per gram of the ethylene-vinyl alcohol copolymer (A) is 0.002 μmol/g or more and 0.17 μmol/g or less.