EVOH Resin Composition for Neck-In and Die Buildup Control
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Solution Overview
Problem
EVOH resin compositions face issues of neck-in and die buildup during melt molding, particularly when used as the top layer in multilayer structures, leading to defects such as fisheyes and streaks, which affect long-run workability.
Innovation Solution
A resin composition containing EVOH with specific ratios of crotonaldehyde, 2,4-hexadienal, and 2,4,6-octatrienal, along with optional additives like inorganic particles, nonionic surfactants, antioxidants, and thermoplastic elastomers, to inhibit neck-in and die buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVOH resin composition contains unsaturated aldehydes to inhibit fisheyes and gelling, then long-run workability is improved, but neck-in occurs during film molding
Solution Approach 1:
The patent changes the chemical parameters by specifying precise content ranges of multiple unsaturated aldehydes (crotonaldehyde: 0.01-5 ppm, 2,4-hexadienal: 0.01-1 ppm, 2,4,6-octatrienal: 0.01-1 ppm) to simultaneously achieve neck-in inhibition and prevent fisheyes, resolving the contradiction through quantitative parameter optimization
Solution Approach 2:
The patent uses a composite approach by combining multiple types of unsaturated aldehydes with different molecular structures and reactivities, where each aldehyde contributes differently to neck-in inhibition and fisheye prevention, achieving synergistic effects that resolve the technical contradiction
2Shape
If EVOH resin composition contains multiple types of unsaturated aldehydes to inhibit neck-in, then neck-in is suppressed, but die buildup adheres to the outer face of the die lip
Solution Approach 1:
The patent optimizes the concentration parameters of unsaturated aldehydes to very low levels (total content 0.03-7 ppm) and specifies precise ratio relationships between different aldehydes, achieving neck-in suppression while minimizing die buildup through careful parameter control
Solution Approach 2:
The patent applies different aldehyde types with specific local functions: crotonaldehyde primarily for neck-in inhibition, while 2,4-hexadienal and 2,4,6-octatrienal contribute to both neck-in suppression and die buildup prevention, creating localized functional differentiation within the additive system
3Reliability
If EVOH is used as the top layer in multilayer structures for synergistic barrier effect, then gas barrier properties are improved, but die buildup becomes a significant problem due to large contact area with die lip
Solution Approach 1:
The patent reduces the content of unsaturated aldehydes to extremely low levels (total 0.03-7 ppm) and optimizes their ratio composition, enabling the EVOH top layer to maintain excellent gas barrier properties while significantly reducing die buildup through precise chemical parameter control
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 composition effectively prevents neck-in and die buildup, ensuring stable melt molding and improved long-run workability, while maintaining gas barrier properties and mechanical strength.
Implementation Method 1
an oxidizing and crosslinking reaction proceeds in a molten state at high temperatures even in the interior of an extrusion molding machine in a state being almost free from oxygen
Implementation Method 2
in molding of the containers and the like, melt molding is often used
Data Source
AI summary
Provided are: a resin composition containing an ethylene-vinyl alcohol copolymer (EVOH), the resin composition allowing for inhibition of neck-in and die buildup at a time of melt molding; and the like.The resin composition contains: an ethylene-vinyl alcohol copolymer (A) having an ethylene unit content of 20 mol % or more and 60 mol % or less; and crotonaldehyde (B1), wherein the resin composition further comprises at least one selected from the group consisting of 2,4-hexadienal (B2) and 2,4,6-octatrienal (B3), and the following inequalities (1) and (2) are satisfied. In the inequalities (1) and (2): b1 represents a content (ppm) of crotonaldehyde (B1) with respect to the ethylene-vinyl alcohol copolymer (A); b2 represents a content (ppm) of 2,4-hexadienal (B2) with respect to the ethylene-vinyl alcohol copolymer (A); and b3 represents a content (ppm) of 2,4,6-octatrienal (B3) with respect to the ethylene-vinyl alcohol copolymer (A).2.≤b1/(b2+b3)<150.(1)b2+2b3≤0.65.(2)