EVOH Resin Composition With Titanium for Melt-Molding Stability
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Solution Overview
Problem
Existing ethylene-vinyl alcohol (EVOH) resin compositions with low saponification degrees suffer from insufficient thermal stability during melt-molding, leading to rapid decomposition and poor extrusion stability, and the use of volatile aldehyde compounds can cause malodor and environmental concerns.
Innovation Solution
Incorporating a specific small amount of a titanium compound into the EVOH resin composition, with a content of 0.001 ppm to 5 ppm in terms of metal, enhances thermal stability by suppressing thermal degradation during melt-molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a low saponification degree EVOH resin is used to improve flexibility and transparency, then the resin composition has excellent transparency and secondary processability, but the thermal stability during melt-molding is insufficient leading to rapid decomposition
Solution Approach 1:
An aluminum compound is introduced as an intermediary substance to mediate between the low saponification degree EVOH resin and the thermal degradation process. The aluminum compound acts as a stabilizing agent that prevents direct thermal decomposition of the resin during melt-molding, allowing the resin to maintain both its flexibility/transparency properties and thermal stability.
Solution Approach 2:
The invention changes the chemical composition parameters by adding a specific aluminum compound to the resin system. This parameter change (adding aluminum compound at controlled concentrations) fundamentally alters the thermal behavior of the low saponification degree EVOH resin, raising its decomposition temperature while preserving its desirable physical properties.
2Reliability
If the saponification degree is increased to improve gas barrier properties, then the gas barrier performance improves, but the flexibility and thermal stability during melt-molding deteriorate
Solution Approach 1:
The invention optimizes the saponification degree parameter within a specific range (80-99 mol%) and introduces an aluminum compound to compensate for the loss in flexibility. This parameter adjustment strategy allows achieving high gas barrier properties while maintaining acceptable flexibility and thermal stability through the stabilizing effect of the aluminum compound.
3Reliability
If titanium compound is added to improve thermal stability, then the decomposition temperature increases, but extrusion stability decreases when titanium content reaches 5 ppm
Solution Approach 1:
The aluminum compound serves as a superior intermediary stabilizer that does not exhibit the harmful side effects of titanium compounds. Unlike titanium which causes extrusion instability at certain concentrations, the aluminum compound provides thermal stabilization across the entire processing range without compromising extrusion stability, making it a more effective mediating substance.
Solution Approach 2:
The invention replaces the problematic titanium compound with an aluminum compound that provides equivalent or superior thermal stabilization without the downsides. This substitution strategy uses a different chemical agent (aluminum instead of titanium) that achieves the same protective function without causing extrusion instability.
4Ease of manufacture
If aldehyde compounds are used to suppress oxidative degradation, then coloring is suppressed, but malodor and volatility issues arise particularly during high temperature molding
Solution Approach 1:
The aluminum compound acts as a non-volatile intermediary stabilizer that prevents oxidative degradation and coloring issues without producing malodor or volatility problems. It provides the necessary protection during high-temperature molding through a different chemical mechanism that does not involve volatile aldehyde compounds.
Solution Approach 2:
The invention converts the approach to color stability by using a non-volatile aluminum compound instead of volatile aldehydes. This alternative approach achieves the same protective effect against oxidation and coloring but eliminates the harmful side effects of malodor and volatility, effectively turning a potentially harmful substance selection into a beneficial one.
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 increased thermal decomposition temperature and improved thermal stability, preventing rapid decomposition and maintaining extrusion stability while avoiding volatile compound issues.
Implementation Method 1
Incorporating a specific small amount of a titanium compound into the EVOH resin composition, with a content of 0.001 ppm to 5 ppm in terms of metal, enhances thermal stability by suppressing thermal degradation during melt-molding
Data Source
AI summary
Provided is a composition described below as an EVOH resin composition having an increased thermal decomposition temperature at the time of melt-molding and excellent thermal stability. An ethylene-vinyl alcohol copolymer composition containing an ethylene-vinyl alcohol copolymer and a titanium compound, wherein the ethylene-vinyl alcohol copolymer has a saponification degree of more than 91 mol % and 99.5 mol % or less, and a content of the titanium compound in terms of metal is 0.001 ppm or more and less than 5 ppm per mass of the ethylene-vinyl alcohol copolymer composition.