EVOH Composition Stabilization Against Melt-Forming Coloration
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Solution Overview
Problem
EVOH resin compositions are prone to coloration and degradation during melt forming due to thermal instability, leading to issues in packaging materials and multilayer pipes, especially when exposed to high temperatures or sunlight.
Innovation Solution
Incorporating a specific combination of antioxidants and sorbic acid esters, such as methyl sorbate or ethyl sorbate, within a defined weight ratio, into the EVOH resin composition to enhance thermal stability and prevent coloration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVOH is used for melt forming, then gas barrier properties and mechanical strength are improved, but coloration and degradation occur due to thermal decomposition
Solution Approach 1:
A boron compound is introduced as an intermediary substance between EVOH and oxygen/heat to prevent thermal decomposition. The boron compound acts as a heat stabilizer that interferes with the degradation mechanism, allowing EVOH to maintain its excellent gas barrier properties without undergoing coloration during melt forming processes.
Solution Approach 2:
The invention changes the chemical composition parameters of the resin system by adding specific amounts of boron compounds (0.001-1 part by weight per 100 parts of EVOH). This parameter change transforms the thermal stability characteristics of EVOH, enabling it to withstand melt forming temperatures without degradation while preserving its functional properties.
2Reliability
If EVOH is exposed to high temperature for prolonged period, then oxygen barrier property is maintained, but degradation occurs due to oxidation
Solution Approach 1:
The invention converts the harmful oxidative degradation process into a beneficial protective mechanism. The boron compound reacts with oxygen and free radicals generated during thermal exposure, transforming the harmful oxidation process into a controlled protective action that extends service life while maintaining oxygen barrier properties.
Solution Approach 2:
The boron compound serves as a mediator between EVOH and environmental oxygen/UV factors. It creates a protective interface that prevents direct interaction between oxygen and the polymer chains, thereby extending service life without compromising the oxygen barrier function of the material.
3Duration of action of stationary object
If antioxidant is added to suppress degradation, then service life is improved, but coloration during melt forming is not sufficiently suppressed
Solution Approach 1:
The invention changes the type and concentration of stabilizing agents from conventional antioxidants to boron compounds at specific low concentrations (0.001-1 part by weight per 100 parts of EVOH). This parameter change provides dual functionality: suppressing coloration during melt forming and preventing long-term degradation, achieving both goals simultaneously with a single additive system.
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 resistance to coloration and degradation, ensuring the stability and performance of packaging materials and multilayer pipes, particularly in applications involving high temperatures or prolonged exposure.
Implementation Method 1
A resin composition is provided which contains: an ethylene-vinyl alcohol copolymer; and a boron compound. The resin composition is less susceptible to coloration and degradation, and is useful as a formed product obtained by melt forming, and as a raw material therefor.
Implementation Method 2
the resin composition is less susceptible to coloration and degradation
Data Source
AI summary
An ethylene-vinyl alcohol copolymer composition contains: (A) an ethylene-vinyl alcohol copolymer; (B) an antioxidant; and (C) a sorbic acid ester; wherein the sorbic acid ester (C) is present in an amount of 0.00001 to 10 ppm based on the weight of the ethylene-vinyl alcohol copolymer composition; wherein the weight ratio (B)/(C) of the antioxidant (B) to the sorbic acid ester (C) is 500 to 1,000,000. The resulting ethylene-vinyl alcohol copolymer composition is less susceptible to coloration.