EVOH Resin Composition Impact Resistance Gas Barrier
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Solution Overview
Problem
EVOH-based multilayer structures face challenges in achieving both excellent gas barrier properties and impact resistance due to the brittleness caused by high crystallinity, which can lead to cracking and pinholes under impact, and blending with other resins to improve impact resistance often compromises gas barrier properties.
Innovation Solution
An EVOH resin composition containing an ethylene-vinyl alcohol copolymer, an aliphatic carboxylic acid metal salt with a metal moiety from Periodic Table 4th-period d-block metals, and a very small amount of sorbic acid ester, which enhances impact resistance without compromising gas barrier properties and reduces odor emanation during film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVOH is used to provide gas barrier properties, then oxygen barrier property is improved, but impact resistance deteriorates due to brittleness from high crystallinity
Solution Approach 1:
The invention changes the chemical parameter by introducing a specific aliphatic carboxylic acid metal salt (containing Ca, Sr, or Ba) at controlled concentrations (1-100 ppm Ca equivalent) to modify the crystalline structure and intermolecular interactions of EVOH, thereby improving impact resistance while preserving gas barrier properties
Solution Approach 2:
The invention creates a composite system by combining EVOH with specific aliphatic carboxylic acid metal salts to form a modified resin composition that exhibits both excellent gas barrier properties and improved impact resistance, avoiding the need to blend with other resins that would compromise barrier performance
2Strength
If other resins are blended with EVOH to improve impact resistance, then mechanical strength is improved, but gas barrier properties deteriorate
Solution Approach 1:
Instead of changing the resin composition by blending, the invention changes the chemical environment parameters by adding specific metal salts that modify EVOH's properties in situ, maintaining 100% EVOH content while improving impact resistance through controlled chemical interaction
Solution Approach 2:
The aliphatic carboxylic acid metal salt acts as an intermediary substance that mediates between the EVOH molecules, modifying intermolecular forces and crystalline structure to improve impact resistance without forming a separate phase that would compromise gas barrier properties
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 EVOH resin composition exhibits improved impact resistance and maintains excellent gas barrier properties, making it suitable for packaging materials that require durability and protection against gas permeation, such as food and chemical packaging, without the need for blending with other resins.
Implementation Method 1
It is generally known that aliphatic carboxylic acid metal salts promote the thermal decomposition of the EVOH to reduce the impact resistance of the EVOH resin composition
Implementation Method 2
the EVOH resin composition containing the EVOH and the specific aliphatic carboxylic acid metal salt and further containing the very small amount of the sorbic acid ester is unexpectedly improved in mechanical properties (impact resistance), and is less susceptible to odor emanation during the film formation
Implementation Method 3
EVOH has crystalline portions formed due to firm hydrogen bonds between hydroxyl groups richly present in its molecular chains, and these crystalline portions prevent intrusion of oxygen from the outside
Data Source
AI summary
An ethylene-vinyl alcohol copolymer composition is provided, which is excellent in impact resistance even without a resin other than an ethylene-vinyl alcohol copolymer blended therein. The ethylene-vinyl alcohol copolymer resin composition contains: (A) an ethylene-vinyl alcohol copolymer; (B) an aliphatic carboxylic acid metal salt; and (C) a sorbic acid ester; wherein the aliphatic carboxylic acid metal salt (B) contains a metal moiety selected from the group consisting of long Periodic Table 4th-period d-block metals; wherein the sorbic acid ester (C) is present in an amount of 0.00001 to 10 ppm based on the total amount of the ethylene-vinyl alcohol copolymer (A), the aliphatic carboxylic acid metal salt (B), and the sorbic acid ester (C).