Polyester Resin Composition for Oxygen Barrier Packaging
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Solution Overview
Problem
Polyester-based packaging materials lack sufficient gas-barrier performance against oxygen and carbon dioxide, and existing methods to improve this, such as coating with aluminum oxide or mixing with high gas-barrier resins like ethylene-vinyl alcohol copolymers, compromise transparency and recyclability.
Innovation Solution
A polyester-based resin composition containing a specific combination of polyester resins with sulfophthalic acid units and alicyclic structures, along with a polyamide resin, which maintains transparency and enhances gas-barrier performance across various draw ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If polyester is used as packaging material, then transparency and mechanical properties are excellent, but gas-barrier performance against oxygen and carbon dioxide is insufficient
Solution Approach 1:
The patent employs a composite resin system combining polyester (for transparency and mechanical properties) with polyamide MXD6 and cyclic carbonate-modified polyester (for gas-barrier performance). This multi-component composite achieves both high transparency and excellent gas-barrier properties against oxygen and carbon dioxide, resolving the contradiction between these two requirements.
2Object-affected harmful factors
If coating with aluminum oxide or silicon oxide is applied, then gas-barrier performance is improved, but production complexity increases and recyclability is impaired
Solution Approach 1:
The patent merges the gas-barrier function directly into the resin matrix by incorporating polyamide MXD6 and cyclic carbonate-modified polyester as blend components. This integration eliminates the need for separate coating steps with aluminum oxide or silicon oxide, thereby maintaining simple production processes while achieving improved gas-barrier performance.
3Object-affected harmful factors
If ethylene-vinyl alcohol copolymer resin is mixed with polyester, then gas-barrier performance is improved, but transparency is impaired and processing stability deteriorates
Solution Approach 1:
The patent modifies the chemical structure of the polyester component by introducing cyclic carbonate groups, which changes the polarity and compatibility parameters of the resin system. This parameter modification enables stable mixing with polyamide MXD6 while maintaining transparency and processing stability, avoiding the gelation and scorching issues associated with ethylene-vinyl alcohol copolymer.
4Object-affected harmful factors
If polyamide resin is added to improve gas-barrier performance, then gas-barrier performance increases, but transparency of stretched portions decreases
Solution Approach 1:
The patent introduces cyclic carbonate groups at specific positions within the polyester chain, creating local polar regions that enhance compatibility with polyamide MXD6. This local modification ensures uniform dispersion and intimate mixing of the polyamide phase, maintaining transparency even in stretched portions while preserving the gas-barrier enhancement.
Data Source
AI summary
A polyester-based resin composition containing a polyester resin (A) that has a dicarboxylic acid unit containing units selected from a sulfophthalic acid unit and a sulfophthalic acid metal salt unit in a total amount of 0.01 to 15.0 mol % and a diol unit, a polyester resin (B) having a cyclic acetal structure or an alicyclic hydrocarbon structure, and a polyamide resin (C), wherein the content of the polyester resin (B) in the resin composition is 0.5 to 15.0% by mass.