Multi-layer Polycarbonate Containers with Barrier Inner Layer
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Solution Overview
Problem
Current polycarbonate containers face challenges with gas permeation and substance migration, losing transparency and dimensional stability during sterilization processes, and lack effective barrier properties compared to glass containers.
Innovation Solution
A multi-layer article comprising a bisphenol A polycarbonate layer and an inner layer of poly(2,2,4,4-tetramethyl-1,3-cyclobutylene terephthalate)-co-poly(cyclohexanedimethylene terephthalate) is developed, which maintains transparency and dimensional stability during sterilization and provides improved barrier properties through specific layer configurations and manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass containers are used to provide transparency, barrier properties, and sterilization resistance, then these properties are improved, but weight increases and fragility causes production interruptions
Solution Approach 1:
The patent employs a multi-layer composite structure combining polycarbonate (PC) and polyethylene naphthalate (PEN) materials. The PC layer provides impact resistance and toughness, while the PEN layer contributes barrier properties against gas and moisture permeation. This composite approach achieves the reliability and performance characteristics of glass containers while maintaining the weight and durability advantages of plastic materials.
2Strength
If polycarbonate containers are used to provide transparency and strength, then these properties are improved, but gas barrier properties deteriorate compared to glass
Solution Approach 1:
The patent utilizes a multi-layer composite structure where the polycarbonate layer provides mechanical strength and impact resistance, while the polyethylene naphthalate layer provides superior gas and moisture barrier properties. This composite design allows the container to achieve both high strength and effective gas barrier performance, overcoming the limitations of single-material polycarbonate containers.
3Reliability
If heat treatment is applied to polycarbonate containers above glass transition temperature, then sterilization is achieved, but transparency is lost due to haze formation
Solution Approach 1:
The patent employs a multi-layer composite structure where the polycarbonate layer can withstand high-temperature sterilization processes, while the polyethylene naphthalate layer maintains optical clarity and resistance to haze formation. This composite design allows the container to achieve effective sterilization while preserving transparency, overcoming the limitation of single-material polycarbonate containers that develop haze after heat treatment.
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 multi-layer structure maintains greater than 90% transmission and less than 2.5% haze after sterilization, offering enhanced mechanical strength, thermal stability, and improved gas barrier properties, making it suitable for food and healthcare packaging applications.
Implementation Method 1
the inner layer forms a barrier between the polycarbonate layer and the interior; wherein the multi-layer article is a bi-layer
Implementation Method 2
the article has a decrease in transparency of less than or equal to 5% after sterilization in an autoclave for 30 minutes at 120°C
Data Source
Figure 1A~3
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Figure 6
AI summary
In an embodiment, a multi-layer article having an interior, the article comprises a second layer comprising a bisphenol A polycarbonate; and an inner layer comprising a terephthalic copolyester; polyethylene furanoate; or a combination comprising at least one of the foregoing; wherein the inner layer forms a barrier between the second layer and the interior. The article has at least one of: a decrease in transparency of less than or equal to 5% after sterilization in an autoclave for 30 minutes at 120°C, and a decrease in transparency of less than or equal to 5% after 50 cycles of hot filling with water for 30 minutes at 90°C.