EVOH Pellets Suppressing Fisheyes via Surface Polyene
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Solution Overview
Problem
Current EVOH composition pellets struggle to reliably suppress the occurrence of minute fisheyes during melt formation, particularly those with diameters not greater than 200 µm, while maintaining melt formability and gas barrier properties.
Innovation Solution
EVOH composition pellets with a conjugated polyene content of not less than 30 ppb on the surface and containing a predetermined amount of a fisheye-suppressing component, such as a lubricant, boron compound, or alkali metal, are developed. These pellets are produced by contacting EVOH pellets with a treatment liquid containing the conjugated polyene and the fisheye-suppressing component, ensuring effective incorporation and control of the conjugated polyene on the pellet surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If EVOH is heat-melted at higher temperature to improve processability, then melt formability is improved, but thermal degradation occurs causing fisheyes and gel-like blobs
Solution Approach 1:
The conjugated polyene is added to the EVOH composition before melt processing to preemptively prevent thermal degradation. This preliminary action allows the polyene to suppress oxidation and crosslinking reactions that would otherwise occur during high-temperature melting, enabling improved processability without the harmful effects of thermal degradation
Solution Approach 2:
The invention converts the potentially harmful thermal degradation process into a beneficial effect by using the conjugated polyene to suppress the harmful oxidation and crosslinking reactions. The polyene acts as a protective agent that transforms the high-temperature melting process from a source of degradation into a controlled processing condition that improves formability while preventing fisheyes
2Object-affected harmful factors
If conjugated polyene is added to suppress fisheyes, then fisheye occurrence is reduced, but odor emanation and bleeding occur in the final product
Solution Approach 1:
The invention precisely controls the concentration parameter of the conjugated polyene, specifying a range of 0.00002 to 1 wt.% (0.2 to 10,000 ppm). This parameter optimization ensures sufficient polyene is present to suppress fisheyes during processing while maintaining low enough concentration to prevent odor emanation and bleeding in the final packaged product
Solution Approach 2:
The conjugated polyene is distributed throughout the EVOH composition at controlled concentrations, providing localized protection against thermal degradation at each point in the material. This uniform but controlled distribution ensures fisheye suppression throughout the film while preventing excessive polyene that would cause odor and bleeding defects
3Reliability
If conventional EVOH composition is used to maintain gas barrier properties, then oxygen barrier property is maintained, but fisheyes occur during film formation
Solution Approach 1:
The invention creates a composite material system by combining EVOH with a conjugated polyene (such as sorbic acid or its derivatives). This composite composition maintains the excellent gas barrier properties of EVOH while the polyene component provides protection against thermal degradation, eliminating the fisheye problem without sacrificing barrier performance
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 solution significantly reduces the occurrence of fisheyes in EVOH films, enhancing melt formability and maintaining excellent gas barrier properties, as evidenced by a substantial decrease in fisheye count and improved processing stability.
Implementation Method 1
The EVOH is liable to experience oxidation reaction and crosslinking reaction even in a generally oxygen-free environment in an extruder to thereby produce a thermal degradation product when being heat-melted at a higher temperature
Implementation Method 2
EVOH composition pellets with a conjugated polyene content of not less than 30 ppb on the surface are produced by contacting EVOH pellets with a treatment liquid containing the conjugated polyene and the fisheye-suppressing component
Data Source
AI summary
Ethylene-vinyl alcohol copolymer composition pellets comprise: an ethylene-vinyl alcohol copolymer, a conjugated polyene, and a predetermined amount of at least one fisheye-suppressing component; wherein pellet surface portions of the ethylene-vinyl alcohol copolymer composition pellets have a conjugated polyene content of not lower than 30 ppb based on the weight of the pellets. Such ethylene-vinyl alcohol copolymer composition pellets are capable of reliably suppressing occurrence of minute fisheyes having a diameter of 200 µm or smaller.