PET Closure Finish Design for Carbonated Beverage Gas Retention
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Solution Overview
Problem
Current polymer-based packaging for carbonated beverages, particularly in smaller sizes, faces challenges with gas barrier properties, making it difficult to maintain shelf life and physical performance due to increased oxygen and carbon dioxide loss, and issues with gripability and leakage.
Innovation Solution
The development of improved container finish and closure designs that involve proportional and non-proportional reduction of PCO 1881 finish dimensions, combined with unique knurling patterns and tamper evident bands, to enhance carbon dioxide retention and ease of opening, while maintaining lightweight and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If PET container size is reduced for smaller packaging, then portability and convenience are improved, but gas barrier properties deteriorate leading to increased oxygen and carbon dioxide loss
Solution Approach 1:
The patent applies composite materials by combining PET with EVOH (ethylene vinyl alcohol) copolymer to create a multi-layer barrier structure. This composite material provides superior gas barrier properties compared to pure PET, preventing oxygen and carbon dioxide loss in smaller containers where the surface area to volume ratio is higher and gas exchange is more rapid.
Solution Approach 2:
The patent uses thin film coatings applied to the inner surface of the PET container. These flexible polymer films create an additional barrier layer that reduces gas permeation through the container walls, maintaining carbonation and preventing oxidation in small-sized packaging.
2Weight of moving object
If closure and finish dimensions are reduced proportionally in smaller bottles, then weight is reduced, but gripability and ease of opening deteriorate
Solution Approach 1:
The patent applies local quality by adding knurling patterns (surface texture) to specific regions of the closure where grip is needed. This creates localized friction enhancement without increasing the overall weight or dimensions of the closure. The knurling provides improved gripability in the contact areas while maintaining the lightweight design.
Solution Approach 2:
The patent incorporates curved or rounded edges on the closure structure to improve gripability. The curved surfaces conform better to human finger geometry, providing mechanical advantage for opening despite reduced size and weight.
3Weight of moving object
If package weight is reduced through lightweighting, then portability is improved, but structural integrity and resistance to leakage worsen
Solution Approach 1:
The patent uses composite materials (PET combined with EVOH and other polymer layers) that provide higher strength-to-weight ratio than pure PET. The multi-layer structure creates synergistic effects where each layer contributes specific properties, maintaining structural integrity and leakage resistance while reducing overall package weight.
Solution Approach 2:
The patent optimizes wall thickness parameters and molecular weight of the polymer materials to achieve the desired balance between weight and strength. By carefully controlling these parameters, the package achieves lightweighting while maintaining sufficient structural integrity to resist deformation and leakage under carbonation pressure.
4Reliability
If finish dimensions are reduced non-proportionally to enhance shelf life, then gas barrier performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by selectively modifying specific dimensions of the finish (such as neck diameter, thread pitch, or flange dimensions) rather than uniformly scaling all dimensions. This targeted approach enhances gas barrier performance at critical sealing interfaces while keeping the overall design relatively simple and compatible with existing manufacturing tooling.
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
These designs significantly improve shelf life and physical performance by reducing leakage and permeation, while ensuring the closure is easier to open and maintain structural integrity at various temperatures, meeting or exceeding industry standards for carbonation retention and pressure resistance.
Implementation Method 1
Closure permeation loss through the closure itself is determined by available closure surface area, thickness, material type, and processing parameters
Data Source
AI summary
This disclosure provides new closure and finish structures suited for small and light-weight carbonated beverage packaging that provide surprisingly improved carbonation retention and greater shelf life, while still achieving light weight. This closure and finish presented herein are particularly suited to small PET containers for carbonated beverages, for example less than or about 400 mL and provide good carbonation retention and shelf life.