Recyclable Polyester Barrier Packaging via Homogeneous Coextrusion
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Solution Overview
Problem
Conventional thermoplastic multilayer packaging structures, used for shelf-stable, frozen, or refrigerated food products, lack recyclability due to chemically dissimilar materials, making them unsuitable for cost-effective recycling in post-consumer recycle streams.
Innovation Solution
A moldable sheet material composed of coextruded layers of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and optionally additional ingredients, excluding adhesives and conventional barrier materials, which maintains desirable oxygen and water vapor barrier properties while being suitable for recycling in a polyethylene terephthalate recycle stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermoplastic multilayer structures are used to provide barrier properties, then oxygen and water vapor barrier properties are improved, but recyclability deteriorates
Solution Approach 1:
The patent applies homogeneity by using polyester materials throughout all layers of the packaging structure. The base polyester polymer is selected from polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, or polyethylene furanoate, and these same polyester materials are used in the barrier layer and tie layer, creating a homogeneous material composition that enables recyclability while maintaining barrier properties.
Solution Approach 2:
The patent employs composite materials by creating a multilayer structure where different polyester variants are combined. The base layer uses one polyester type, the barrier layer incorporates the same polyester with barrier agents dispersed throughout, and tie layers use compatible polyester materials, forming a composite structure that maintains both barrier functionality and material compatibility for recycling.
2Reliability
If chemically dissimilar materials are used in multilayer structures to provide barrier properties, then barrier performance is improved, but manufacturing complexity and recycling difficulty increase
Solution Approach 1:
The patent eliminates material composition complexity by ensuring all layers are made from the same polyester family. The base polyester polymer is consistently used across base layers, barrier layers, and tie layers, removing the need for chemically dissimilar materials and simplifying both manufacturing and recycling processes while maintaining effective barrier properties.
Solution Approach 2:
The patent uses tie layers composed of the same polyester material to mediate between different functional layers. These tie layers provide adhesion between the base layer and barrier layer without introducing chemically dissimilar materials, thus maintaining material homogeneity while ensuring proper layer bonding and structural integrity.
Data Source
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AI summary
Moldable sheet materials include a first layer including a first polyester, a second layer including a second polyester, and, optionally, a third layer including a third polyester. The first polyester, the second polyester, and the third polyester are the same as or different from each other of the first polyester, the second polyester, and the third polyester. The sheet materials exclude one or more of adhesives, ethylene vinyl alcohol, polyvinyl alcohol, polyvinylidene chloride, polyamides, polyolefins, polystyrenes, and the like. Molded packages made from the sheet materials exhibit desirable oxygen and water vapor barrier properties while also being suitable for recycling in a polyethylene terephthalate recycle stream.