EVOH Copolymer Particles Balancing Water Solubility and Gas Barrier
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Solution Overview
Problem
Existing ethylene-vinyl alcohol copolymers face issues with insolubility in water, leading to prolonged dissolution times and reduced gas barrier performance under high humidity, and previous modifications result in voids or agglomeration during crosslinking.
Innovation Solution
Production of ethylene-vinyl alcohol copolymer particles with specific ethylene unit content, saponification degree, and viscosity-average polymerization degree, combined with a controlled crystallinity ratio determined by pulse NMR, ensuring rapid solubility and minimal lump formation in water, and a production method involving polymerization, saponification, pulverization, deliquoring, and drying steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ethylene unit content is increased to reduce hygroscopicity, then gas barrier performance is improved, but water solubility deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ethylene unit content within 1-19 mol%, viscosity-average polymerization degree within 200-2000, and saponification degree within 80-99.99 mol%. These parameter optimizations balance the hydrophobicity needed for gas barrier performance with the hydrophilicity required for water solubility, resolving the contradiction between improved gas barrier properties and maintained solubility.
2Loss of time
If saponification degree is lowered to improve water solubility, then dissolution time is reduced, but gas barrier performance under high humidity deteriorates
Solution Approach 1:
The patent optimizes the saponification degree parameter within the range of 80-99.99 mol%, finding the optimal balance point that enables adequate water solubility and reasonable dissolution time while maintaining sufficient gas barrier performance under high humidity conditions. This parameter optimization resolves the trade-off between dissolution speed and barrier performance.
3Reliability
If crosslinking is introduced to improve gas barrier performance, then barrier properties are enhanced, but voids are formed during crosslinking
Solution Approach 1:
The patent extracts the crosslinking step from the preparation process, avoiding the formation of voids and lumps that occur during crosslinking reactions. By using a non-crosslinked ethylene-vinyl alcohol copolymer with optimized composition parameters, the invention achieves good gas barrier performance without the manufacturing defects associated with crosslinking, thus resolving the contradiction between barrier enhancement and film uniformity.
4Productivity
If elevated temperature dissolution is used to improve solubility, then dissolution rate is increased, but cost increases
Solution Approach 1:
The patent changes the intrinsic parameters of the copolymer (ethylene unit content, polymerization degree, saponification degree) to achieve good water solubility at lower temperatures. This parameter optimization allows dissolution to proceed efficiently without requiring elevated temperatures, thereby reducing energy consumption and dissolution costs while maintaining high dissolution rates.
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 resulting copolymer particles exhibit high solubility in water with reduced lump formation, enabling efficient aqueous solution preparation and formation of coating films with excellent gas barrier properties under high humidity.
Implementation Method 1
ethylene-vinyl alcohol copolymer particles with excellent solubility in water... highly soluble in water so that when being dissolved in water, fewer lumps are formed with a higher solution rate
Implementation Method 2
excellent gas barrier performance... coating film with excellent barrier properties... oxygen transmission rate of the film obtained was 10.3 cc/m2
Data Source
AI summary
The present invention relates to ethylene-vinyl alcohol copolymer particles, comprising an ethylene-vinyl alcohol copolymer having an ethylene unit content of 1 mol% or more and less than 20 mol%, a viscosity-average polymerization degree of 200 to 5000, and a saponification degree of 80 to 99.99 mol%, wherein a crystallinity in water Cw (30 °C) at 30 °C and a crystallinity in water Cw (70 °C) at 70 °C as determined by pulse NMR satisfy formula (I). There is thus provided ethylene-vinyl alcohol copolymer particles having excellent solubility in water and excellent gas barrier performance.