Thermoformed Polyester Closure for Pressurized PET Sealing
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Solution Overview
Problem
Conventional container closures made from HDPE and PP are not recyclable with PET containers, leading to contamination and inefficiencies in recycling streams due to material incompatibility, and they lack effective sealing properties for pressurized contents.
Innovation Solution
Developing closures from thermoformed polyester resin, particularly polyethylene furandicarboxylate (PEF) or PET-based copolymers, which can be recycled with PET containers and provide enhanced sealing through interference fits and tailored designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional closures are made from HDPE or PP through injection molding, then the closures have sufficient structural strength and sealing capability, but they are incompatible with PET recycling streams and cause contamination
Solution Approach 1:
The closure is made from the same polyester material (PET) as the container it seals, creating material homogeneity. This allows both the container and closure to be recycled together in the same PET recycling stream without contamination, while still providing adequate sealing capability through the polyester material properties and design features like the interference fit mechanism
Solution Approach 2:
The invention changes the material parameter from conventional HDPE/PP to polyester resin, and changes the manufacturing process parameter from injection molding to thermoforming. These parameter changes enable recycling compatibility while maintaining sealing function through alternative mechanisms such as the interference fit between the closure's inner cylindrical wall and the container finish
2Loss of substance
If closure wall thickness is reduced to improve recyclability and material efficiency, then recycling compatibility improves, but structural strength and sealing reliability may be compromised
Solution Approach 1:
The closure design applies different wall thicknesses to different regions: the inner cylindrical wall has sufficient thickness to provide the interference fit sealing mechanism, while the outer cylindrical wall and non-sealing portions can be thinner. This localized quality distribution maintains sealing reliability where needed while reducing overall material usage and improving recycling efficiency
Solution Approach 2:
The closure incorporates a multi-layer composite structure with an inner layer and outer layer, where each layer can be optimized for specific functions. The inner layer provides the sealing interface with appropriate thickness for interference fit, while the outer layer provides structural support and can be thinner, achieving a balance between sealing reliability and material efficiency
3Object-generated harmful factors
If thermoforming is used instead of injection molding, then material compatibility with PET recycling is achieved, but manufacturing precision and dimensional control may be affected
Solution Approach 1:
The thermoforming process uses a pre-heated polyester sheet that is formed over a mold before final cooling and setting. This preliminary heating and forming action allows the material to be shaped with good dimensional control, and the interference fit mechanism is built into the mold design itself, ensuring consistent dimensions for sealing without requiring post-forming adjustments
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 polyester resin closures maintain container integrity, reduce contamination, enhance recyclability, and improve sealing performance for pressurized contents, while being compatible with PET containers for thermal bonding and tamper-evident features.
Implementation Method 1
an inner cylindrical wall that extends downwardly from the annular wall, the inner cylindrical wall configured such that an outwardly facing surface of the inner cylindrical wall has an interference fit with an inwardly facing surface of the finish of the container for sealing against the inwardly facing surface of the finish
Implementation Method 2
compatible with PET containers for thermal bonding
Data Source
AI summary
Thermoformed polyester resin closures for closing containers, the polyester resins including polyethylene terephthalate (“PET”), polyethylene furandicarboxylate (“PEF”), or a copolymer including PET and PEF, are provided herein. Methods of making the thermoformed closures are further provided. Methods of sterilizing the thermoformed closures are further provided.