Transparent Oxygen-Scavenging Polyester Blends for Packaging
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Solution Overview
Problem
Conventional packaging materials with oxygen and moisture barrier properties are expensive, unstable, and difficult to recycle due to their multilayer structures, which often result in hazy or opaque blends that are not suitable for transparent applications like beverage containers.
Innovation Solution
A transparent, immiscible polymer blend comprising a thermoplastic polymer and a transamidized blend of polyamides with closely matched refractive indices, allowing for the creation of clear, high-barrier polymer compositions that can incorporate a high proportion of regrind and be used in various packaging applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional barrier materials (EVOH, PVOH, polyamides) are used to create oxygen and moisture barriers, then barrier performance is improved, but cost increases and structural stability deteriorates
Solution Approach 1:
The patent uses composite materials by combining conventional barrier polymers (EVOH, PVOH, polyamides) with a novel cyclobutanediol-containing polyester. This composite approach allows the barrier materials to maintain their oxygen and moisture barrier performance while the cyclobutanediol polyester provides structural stability and processability, resolving the contradiction between barrier performance and structural stability.
2Quantity of substance
If multilayer structures are used to reduce the amount of expensive barrier material, then cost is reduced, but manufacturing complexity increases and recycling becomes difficult
Solution Approach 1:
The patent merges the barrier polymer and the cyclobutanediol-containing polyester into a single-layer miscible blend. This combining approach eliminates the need for complex multilayer structures while maintaining barrier performance, as the cyclobutanediol polyester acts as both a structural matrix and a compatibility enhancer that ensures uniform distribution and performance of the barrier material throughout the single layer.
3Productivity
If barrier materials are blended with regrind polymer, then recyclability is improved, but transparency deteriorates due to haze and opaqueness
Solution Approach 1:
The patent changes the chemical parameters of the cyclobutanediol-containing polyester to achieve refractive index matching with common barrier polymers and regrind materials. By adjusting the chemical composition and structure of the cyclobutanediol polyester, the refractive index is optimized to match that of EVOH, PVOH, and polyamides, thereby eliminating interfacial scattering and haze when these materials are blended, thus maintaining transparency while enabling effective recycling of barrier materials.
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 provides transparent, high-barrier polymer compositions that are economically viable, recyclable, and suitable for packaging applications, maintaining product quality by reducing oxygen and moisture exposure while allowing for the use of a high percentage of recycled materials.
Implementation Method 1
immiscible blends have small differences in the absolute value of their refractive indices
Implementation Method 2
compositions containing an oxidation catalyst
Implementation Method 3
oxygen-scavenging compositions
Data Source
AI summary
Disclosed are oxygen-scavenging polymer compositions having high transparency and low haze comprising immiscible blends of at least one polyester comprising 2,2,4,4-tetramethyl-1,3-cyclobutanediol, a copolyamide or a transamidized, homogeneous blend of a least two polyamides, and a metal catalyst. The components of the immiscible blend which have refractive indices which differ by about 0.006 to about −0.0006. The small difference in the refractive indices enable the incorporation of regrind into the polymer composition to produce transparent shaped articles. The blends of the present invention are useful in producing shaped articles such as, for example, sheeting, films, tubes, bottles, preforms and profiles. These articles may have one or more layers and can exhibit improved excellent barrier properties and good melt processability while retaining excellent mechanical properties.