EVOH Resin Composition with Unsaturated Aldehyde for Melt Workability
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Solution Overview
Problem
Conventional resin compositions containing ethylene-vinyl alcohol copolymers (EVOH) suffer from insufficient long-run workability and defects like fish eyes and streaks during melt molding, which affect the appearance and performance of molded articles, and are exacerbated by thermal deterioration and oxidation reactions at high temperatures.
Innovation Solution
A resin composition comprising EVOH and an unsaturated aldehyde, with specific concentrations of 0.05 ppm to 50 ppm, along with additional components such as a boron compound, conjugated polyene compound, acetic acid, and phosphorus compound, to suppress thermal degradation and oxidative processes, thereby improving appearance characteristics and long-run workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If EVOH is used as a molding material, then barrier properties and mechanical strength are improved, but thermal deterioration occurs at high temperatures leading to poor long-run workability
Solution Approach 1:
An unsaturated aldehyde compound is introduced as an intermediary substance that mediates between the EVOH polymer chains during melt molding. This intermediary prevents direct oxidation and crosslinking reactions by acting as a sacrificial agent, thereby maintaining long-run workability without compromising the inherent mechanical strength of EVOH
Solution Approach 2:
The invention changes the chemical environment parameters during melt molding by introducing the unsaturated aldehyde compound. This parameter change (adding a reactive carbonyl compound) modifies the thermal behavior of EVOH, suppressing deterioration reactions while preserving the material's mechanical properties
2Reliability
If conventional additives are used to improve long-run workability, then thermal stability is enhanced, but yellowing occurs leading to unfavorable appearance
Solution Approach 1:
The unsaturated aldehyde compound functions as a disposable protective agent that is consumed during the molding process. It sacrifices itself to prevent oxidation of EVOH, and since it is used in small amounts (0.01-5 parts by mass per 100 parts EVOH), it prevents yellowing while improving long-run workability
Solution Approach 2:
The invention changes the chemical composition parameters by selecting a specific type of additive (unsaturated aldehyde) with different chemical properties than conventional antioxidants. This parameter change allows improvement of long-run workability without the yellowing side effect that plagues traditional additives
3Productivity
If melt molding is performed for long periods, then productivity is improved, but thermal deterioration products accumulate causing fish eyes and streaks
Solution Approach 1:
The unsaturated aldehyde compound enables continuous melt molding operations by continuously suppressing oxidation and crosslinking reactions. It maintains the polymer's processability throughout extended operation periods, preventing the accumulation of deterioration products that cause fish eyes and streaks
Solution Approach 2:
The unsaturated aldehyde acts as a mediator that prevents direct harmful interactions between EVOH chains during prolonged heating. This intermediary protection ensures manufacturing precision (appearance uniformity) is maintained even during continuous operations that prioritize productivity
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 reduces the occurrence of defects like fish eyes and streaks, enhancing the appearance and long-run workability of molded articles, even under prolonged melt molding conditions, making it suitable for various packaging materials.
Implementation Method 1
since EVOH has a comparatively active hydroxyl group in its molecule, an oxidation reaction and/or a crosslinking reaction is caused in a molten state at high temperatures
Implementation Method 2
thermal deterioration products may be generated
Data Source
AI summary
The present invention provides a resin composition containing (A) an ethylene-vinyl alcohol copolymer and (B) an unsaturated aldehyde (B), in which the content of the unsaturated aldehyde (B) with respect to the resin composition containing the ethylene-vinyl alcohol copolymer is 0.01 ppm or more and 100 ppm or less. The unsaturated aldehyde (B) is preferably crotonaldehyde, 2,4-hexadienal, 2,4,6-octatrienal or a combination thereof. In addition, it is preferred that the resin composition further contains a boron compound, and the content of the boron compound is 100 ppm or more and 5,000 ppm or less. Also, it is preferred that the resin composition further contains a conjugated polyene compound, and the content of the conjugated polyene compound is 0.01 ppm or more and 1,000 ppm or less.