Resin Composition EVOH Compatibility via Copolymer Mediator
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Solution Overview
Problem
Resin compositions made from polyolefins and EVOH often exhibit poor compatibility, leading to film surface anomalies such as wavy patterns and aggregation issues during melt molding, which impair the appearance and reusability of molded articles.
Innovation Solution
A resin composition comprising polyolefin, saponified ethylene-vinyl acetate copolymer, higher fatty acid metal salts, conjugated polyene compounds, and saponified ethylene-vinyl acetate copolymer, with specific mass ratios and additives to enhance dispersibility and prevent aggregation, resulting in improved micro-scale dispersion and appearance of molded articles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyolefin and EVOH are blended to create resin composition, then gas barrier properties are improved, but compatibility between components deteriorates causing phase separation and film surface anomalies
Solution Approach 1:
The patent introduces an ethylene-vinyl acetate copolymer as an intermediary component between polyolefin and EVOH. This copolymer acts as a compatibility modifier that facilitates mixing between the otherwise incompatible components, preventing phase separation while maintaining the gas barrier properties provided by EVOH.
Solution Approach 2:
The patent creates a composite resin composition containing polyolefin, EVOH, and ethylene-vinyl acetate copolymer in specific proportions. This composite approach allows combining the gas barrier properties of EVOH with the processability of polyolefin, while the copolymer ensures homogeneous distribution and prevents aggregation.
2Stability of the object's composition
If higher fatty acid metal salts and ethylenediaminetetraacetate metal salts are added to improve compatibility, then phase separation is reduced, but long-run processability deteriorates due to increased foreign matter formation
Solution Approach 1:
The patent removes problematic higher fatty acid metal salts and ethylenediaminetetraacetate metal salts from the composition, replacing them with ethylene-vinyl acetate copolymer. This extraction eliminates the source of foreign matter formation during long-term operation while maintaining compatibility through the copolymer's inherent mixing ability.
3Shape
If saponified ethylene-vinyl acetate copolymer with high degree of saponification is used to prevent wavy patterns, then surface appearance is improved, but micro-scale aggregation of EVOH increases
Solution Approach 1:
The patent optimizes the degree of saponification parameter of the ethylene-vinyl acetate copolymer to a specific range (70-90%). This parameter adjustment balances two competing requirements: sufficient saponification to prevent wavy patterns on the surface, while limiting excessive saponification that would cause micro-scale EVOH aggregation. The controlled parameter change achieves both surface quality and internal homogeneity.
Data Source
AI summary
A method of making a resin composition comprising; a polyolefin (A); a saponified ethylene-vinyl acetate copolymer (EVOH) (B) having an ethylene content of 20-65 mol % and a degree of saponification of 96% or more; a higher fatty acid metal salt (C) having 8 to 22 carbon atoms; a conjugated polyene compound (D) having a boiling point of 20° C. or higher; an ethylene-vinyl acetate copolymer (E); and a saponified ethylene-vinyl acetate copolymer (F) having an ethylene content of 68-98 mol % and a degree of saponification of 20% or more, wherein the mass ratio (A:B) is 60:40 to 99.9:0.1, the amount of the higher fatty acid metal salts (C) is in the range of 0.0001 to 10 pbm per 100 pbm of the total of the polyolefin (A) and the EVOH (B), the amount of conjugated polyene compound (D) is in the range of 0.000001 to 1 pbm, and the total amount of the ethylene-vinyl acetate copolymer (B) and the saponified ethylene-vinyl acetate copolymer (F) is 0.3 pbm or more.