Saponified EVOH Pellets With Low Turbidity for Low-Gel Films
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Solution Overview
Problem
Conventional ethylene-vinyl ester based copolymer pellets, such as EVOH resins, suffer from issues like non-uniform mixing of polymerization inhibitors, high aggregate content, high gel concentration, and high oxygen permeability, leading to poor quality films.
Innovation Solution
Saponified pellets of ethylene-vinyl ester based copolymers with controlled ethylene content and turbidity in methanol aqueous solution, combined with polymerization inhibitors like conjugated polyenes, are used to form films with reduced gels and low oxygen transmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional EVOH pellets are used, then production is simpler, but the films have high aggregate content and high gel concentration leading to poor quality
Solution Approach 1:
The patent applies preliminary action by adding polymerization inhibitors during the polymerization process itself, rather than attempting to address aggregate formation after pellet production. This preventive approach ensures uniform inhibition of secondary polymerization reactions that cause aggregates, thereby improving film quality without requiring complex post-processing steps.
Solution Approach 2:
The patent changes the parameter of inhibitor concentration and timing during polymerization. By optimizing the amount and addition stage of polymerization inhibitors, the process controls aggregate formation at its source, achieving high-quality films with low gel concentration while maintaining a manageable production process.
2Manufacturing precision
If polymerization inhibitors are insufficiently mixed, then the manufacturing process is simpler, but aggregates and gels increase significantly
Solution Approach 1:
The patent applies preliminary action by incorporating polymerization inhibitors into the polymerization mixture at the beginning of the reaction process. This ensures that inhibitors are distributed throughout the reacting monomers before polymerization begins, preventing localized areas of uncontrolled polymerization that would create aggregates and gels.
Solution Approach 2:
The patent addresses homogeneity by ensuring uniform distribution of polymerization inhibitors throughout the reaction mixture. By achieving homogeneous mixing of inhibitors with monomers and initiators before polymerization starts, the process prevents non-uniform inhibition that would lead to aggregate formation and high gel concentration in the final film.
3Manufacturing precision
If aggregates are present in pellets, then the raw material production is easier, but the resulting films have high gel concentration and poor quality
Solution Approach 1:
The patent applies preliminary action by adding polymerization inhibitors during the polymerization process to prevent aggregate formation in the first place. This preventive measure ensures that pellets are produced with uniform structure and low aggregate content, resulting in homogeneous films without requiring reprocessing or rejection of defective material.
Solution Approach 2:
The patent changes the parameter of inhibitor concentration and addition timing during polymerization to control aggregate formation. By optimizing these parameters, the process achieves both high pellet production efficiency and high film homogeneity, as aggregates are prevented rather than treated after formation.
4Reliability
If oxygen permeability is high, then the film allows better gas exchange, but the barrier performance for preserving perishable goods deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the copolymer by controlling ethylene content (24-48 mole %) and saponification degree (≥99.5 mole %). These parameter changes optimize the balance between oxygen barrier performance and other film properties, achieving low oxygen permeability suitable for preserving perishable goods while maintaining adequate gas exchange capability through the controlled copolymer structure.
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 results in films with fewer aggregates and gels, and lower oxygen transmission rates, improving film quality and performance.
Implementation Method 1
a turbidity of the pellets as dissolved in a 60% (w/w) methanol aqueous solution is less than 300 NTU
Data Source
AI summary
The instant disclosure relates to saponified pellets of an ethylene-vinyl ester based copolymer as well as a film and a multilayer structure formed therefrom. The saponified pellets of an ethylene-vinyl ester based copolymer has an ethylene content of 24-35 mole %, and the pellets have a turbidity of less than 300 NTU when dissolved in a 60% (w/w) methanol aqueous solution; or the pellet has an ethylene content of 36-48 mole %, and the pellets have a turbidity of less than 200 NTU when dissolved in a 80% (w/w) methanol aqueous solution. The present invention controls the amount of aggregates by controlling the turbidity of the saponified pellets of an ethylene-vinyl ester based copolymer dissolved in methanol aqueous to reduce the amount of gel produced after film formation.