EVOH Resin Coloration Suppression via Sorbic Acid Ester

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Solution Overview

Problem

EVOH resin compositions used in packaging materials face challenges with heat stability and coloration issues due to thermal degradation during melt-forming, particularly when EVOHs with different melting points are processed at a single temperature, leading to poorer gas barrier properties and susceptibility to coloration.

Innovation Solution

Incorporating a specific small amount of sorbic acid ester into an EVOH resin composition containing EVOHs with different ethylene contents, where the ethylene-vinyl alcohol copolymer constitutes at least 70 wt.%, significantly improves the heat stability and suppresses coloration, even when EVOHs with varying melting points are used.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If EVOHs with different melting points are melt-formed at a single temperature, then the gas barrier property and stretchability requirements can be satisfied, but thermal degradation occurs leading to coloration and poorer heat stability

Engineering Contradiction:

Improvegas barrier property and stretchabilityVSAvoidheat stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the chemical composition parameter of the EVOH resin by incorporating a hydroxycarboxylic acid component, which modifies the thermal properties and stability of the copolymer, allowing it to resist thermal degradation during single-temperature melt-forming processes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The hydroxycarboxylic acid component acts as an intermediary substance that mediates between the different EVOH components with varying melting points, preventing thermal degradation and coloration while maintaining the functional requirements of gas barrier and stretchability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If EVOHs with different ethylene contents are used in combination, then both gas barrier property and stretchability can be satisfied, but the EVOH resin composition becomes more susceptible to coloration

Engineering Contradiction:

Improvegas barrier property and stretchabilityVSAvoidcoloration

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent creates a composite EVOH resin system by combining multiple EVOH components with different ethylene contents and adding a hydroxycarboxylic acid component, forming a multi-component system that achieves both functional requirements and resistance to coloration

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical composition parameters of the EVOH resin by incorporating hydroxycarboxylic acid components, which changes the thermal and chemical stability properties of the copolymer, thereby suppressing coloration while maintaining gas barrier and stretchability properties

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3715417B1Ethylene-vinyl alcohol copolymer composition, melt-forming material, multilayer structure, and container

Publication Date: 2023.04.26 MITSUBISHI CHEM CORP

AI summary

A thermoformable ethylene-vinyl alcohol copolymer composition contains: (A) an ethylene-vinyl alcohol copolymer comprising two or more ethylene-vinyl alcohol copolymers having different ethylene structural unit contents; and (B) a sorbic acid ester; wherein the sorbic acid ester (B) is present in an amount of 0.00001 to 10 ppm based on the weight of the ethylene-vinyl alcohol copolymer composition. The ethylene-vinyl alcohol copolymer composition is excellent in coloration-suppressing effect.