EVOH Resin Composition Inhibiting Flow Marks via Crosslinking
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Solution Overview
Problem
Ethylene-vinyl alcohol copolymers (EVOH) used in packaging materials face issues with poor suitability for secondary processing, leading to cracks, reduced mechanical strength, and unstable gas barrier properties due to high crystallinity and poor compatibility with elastomers, resulting in flow marks and coloring during long-run operations.
Innovation Solution
A resin composition comprising two types of EVOHs with specific ethylene content ranges and an unsaturated aldehyde, which inhibits flow marks and enhances heat stretching properties by crosslinking effects, improving the compatibility and stability of the material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If elastomers such as ethylene-vinyl acetate copolymer (EVA) are blended into EVOH to improve suitability for secondary processing, then heat stretching properties are improved, but compatibility with EVOH is poor resulting in reduced transparency
Solution Approach 1:
The patent changes the chemical parameter of the elastomer by using ethylene-acrylic acid copolymer instead of conventional EVA, and further modifies it through grafting with styrene and/or butadiene. This parameter change enables compatibility with EVOH while maintaining heat stretching properties and transparency.
Solution Approach 2:
The patent creates a composite material system where ethylene-acrylic acid copolymer is grafted with styrene and/or butadiene to form a compatible elastomeric phase that can be integrated with EVOH. This composite approach achieves both improved heat stretching properties and maintained transparency through proper phase compatibility.
2Stability of the object's composition
If different types of EVOHs are blended to improve transparency and heat stretching properties, then these properties are improved, but flow marks are generated due to viscosity difference between the two types of EVOHs in long-run operation
Solution Approach 1:
The patent introduces a specific elastomer (ethylene-acrylic acid copolymer grafted with styrene and/or butadiene) as an intermediary component that mediates between different EVOH types. This intermediary improves compatibility and reduces viscosity differences, preventing flow marks while maintaining transparency and heat stretching properties.
3Stability of the object's composition
If polyamide resin or reacetylated EVOH is used to improve transparency and heat stretching properties, then these properties are improved, but long-run workability is poor with increased generation of gels and seeds
Solution Approach 1:
The patent uses a specifically designed elastomer (ethylene-acrylic acid copolymer grafted with styrene and/or butadiene) that provides the necessary performance improvement without the long-term stability issues of polyamide resin or reacetylated EVOH. This elastomer maintains transparency and heat stretching properties while ensuring reliable long-run operation without gel or seed formation.
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 effectively inhibits flow marks and coloring, while maintaining superior heat stretching properties and gas barrier performance, ensuring stable and high-quality packaging materials.
Implementation Method 1
an unsaturated aldehyde, wherein a value obtained by subtracting the ethylene content of the ethylene-vinyl alcohol copolymer (A) from the ethylene content of the ethylene-vinyl alcohol copolymer (B) is 8 mol % or more, a mass ratio (A/B) of the ethylene-vinyl alcohol copolymer (A) to the ethylene-vinyl alcohol copolymer (B) is 60/40 or more and 95/5 or less, and a content of the unsaturated aldehyde (C) with respect to a resin content is 0.01 ppm or more and less than 100 ppm
Data Source
AI summary
The present invention provides a resin composition containing: (A) an ethylene-vinyl alcohol copolymer having an ethylene content of 20 mol % or more and 50 mol % or less; (B) an ethylene-vinyl alcohol copolymer having an ethylene content of 30 mol % or more and 60 mol % or less; and (C) an unsaturated aldehyde, a value obtained by subtracting the ethylene content of the ethylene-vinyl alcohol copolymer (A) from the ethylene content of the ethylene-vinyl alcohol copolymer (B) being 8 mol % or more, a mass ratio (A/B) of the ethylene-vinyl alcohol copolymer (A) to the ethylene-vinyl alcohol copolymer (B) being 60/40 or more and 95/5 or less, and the content of the unsaturated aldehyde (C) with respect to a resin content being 0.01 ppm or more and less than 100 ppm.