Rotatable Cap Closure for Hot-Fill Container Pressure Compensation
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Solution Overview
Problem
Hot-fill plastic containers experience deformation due to pressure differences caused by thermal contraction, which current solutions attempt to mitigate with vacuum panels that complicate labeling and structural integrity.
Innovation Solution
A rotatable cap closure with sealing features, such as a diaphragm, slider ring, and flexible bellows, that compresses air in the headspace to maintain internal pressure and prevent deformation, eliminating the need for vacuum panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If vacuum panels are used to compensate for vacuum, then container structural integrity is maintained, but device complexity increases and labeling becomes difficult
Solution Approach 1:
The patent removes the vacuum panel feature from the container structure entirely. Instead of adding structural reinforcements to counteract vacuum, the invention extracts the problematic vacuum state by providing a venting mechanism that allows air to enter the container during cooling, thereby eliminating the need for complex vacuum compensation structures.
Solution Approach 2:
The patent introduces an intermediary venting mechanism (such as a venting valve or air vent hole) that mediates between the internal vacuum pressure and external atmospheric pressure. This intermediary component allows controlled air entry to equalize pressure without requiring complex structural reinforcements throughout the container.
2Stability of the object's composition
If vacuum panels are used to compensate for vacuum, then container deformation is prevented, but manufacturing difficulty increases
Solution Approach 1:
The patent eliminates the vacuum panel feature that complicates manufacturing. By removing the need for vacuum compensation structures, the container can be manufactured using simpler, more conventional molding processes without requiring complex vacuum-reactive mechanisms or multi-step manufacturing procedures.
Solution Approach 2:
The patent employs a simple, inexpensive venting mechanism (such as a basic venting valve or air hole) that is easier and cheaper to manufacture than vacuum panels. This simple component achieves the same functional goal of preventing deformation while being significantly more economical and easier to produce.
3Reliability
If vacuum panels are used to compensate for vacuum, then pressure balance is maintained, but label surface area is reduced
Solution Approach 1:
The patent removes the vacuum panel feature that consumes label surface area. By eliminating the need for vacuum compensation structures, the entire container surface is available for labeling, maximizing the label area while maintaining pressure balance through the venting mechanism.
4Stress or pressure
If headspace air is compressed during capping, then internal pressure increases to compensate for vacuum, but container bursting risk increases
Solution Approach 1:
The patent introduces an intermediary venting mechanism that mediates between the pressurized headspace and external atmosphere. This venting component allows excess air to escape during capping and cooling, preventing dangerous pressure buildup while still providing sufficient pressure compensation to prevent container deformation.
Solution Approach 2:
The patent employs a partial venting action that allows controlled air escape during capping rather than complete sealing. This partial venting provides sufficient pressure compensation to prevent deformation while avoiding excessive pressure buildup that could cause bursting, by allowing just enough air to escape to maintain balanced pressure.
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 effectively maintains container structural integrity by compensating for pressure changes, allowing for easier labeling and reducing material usage while preventing deformation and bursting.
Implementation Method 1
A rotatable cap closure with sealing features, such as a diaphragm, slider ring, and flexible bellows, that compresses air in the headspace to maintain internal pressure and prevent deformation
Implementation Method 2
When the cap is positioned on a container neck, the sealing features hermetically seal the cap to the container
Implementation Method 3
The temperature of the liquid varies from a high of about 185 degrees Fahrenheit, the typical hot-fill temperature, to about 40 degrees Fahrenheit, the typical refrigeration temperature. A change in temperature, from hot to cold, decreases the internal pressure of the sealed container and creates a vacuum within the container primarily as a result of the thermal contraction of the liquid in the container
Data Source
AI summary
The present invention is directed to a method and apparatus for accommodating the pressure decrease of the fluid in a hot-filled plastic container.