Plastic Cap Structure to Prevent Rubber Stopper Rotation
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Solution Overview
Problem
Existing plastic caps for pharmaceutical containers are prone to rotation of the rubber stopper when subjected to lateral forces, compromising airtightness, especially when used with glass containers that have higher dimensional errors.
Innovation Solution
A plastic cap design with an inner cover having a higher coefficient of friction with the rubber stopper than with the cap itself, featuring protrusions and slits to prevent rotation, along with locking mechanisms to secure the cap to the container.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a plastic cap is designed with claws for engagement inside the cap to fix the cap to the pharmaceutical container, then the cap can be applied to both synthetic resin and glass containers, but the cap easily comes off when the pharmaceutical container and cap are engaged loosely
Solution Approach 1:
The invention applies different engagement mechanisms to different parts of the cap structure. The skirt portion engages with the container lip through localized protrusions and grooves, while the inner cover portion engages with the rubber stopper through localized protrusions. This localized quality differentiation allows the cap to adapt to different container types while maintaining secure retention through multiple engagement points.
2Reliability
If the plastic cap is made to engage tightly with the pharmaceutical container to prevent coming off, then cap retention is improved, but it becomes difficult to perform capping itself
Solution Approach 1:
The cap is segmented into distinct functional portions: a skirt portion for engaging with the container lip and an inner cover portion for engaging with the rubber stopper. Each portion has specialized engagement features (protrusions and grooves) that provide secure retention while allowing smooth assembly. The segmentation enables independent optimization of engagement strength for each interface, preventing premature tightening that would hinder capping operation.
3Reliability
If the inner cover has a high coefficient of friction with the rubber stopper to prevent rotation, then airtightness is maintained, but the cap structure becomes more complex
Solution Approach 1:
The inner cover portion is designed with localized high-friction protrusions that contact the rubber stopper at specific points. These protrusions provide the necessary friction to prevent rotation and maintain airtightness without requiring the entire cap structure to be complex. The grooves in the inner cover work in conjunction with the protrusions to create a simple yet effective anti-rotation mechanism that maintains airtightness while minimizing structural complexity.
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
Maintains airtightness by preventing the rubber stopper from rotating, even under lateral forces, ensuring secure sealing and easy application to both synthetic resin and glass containers.
Implementation Method 1
a coefficient of friction between the inner cover and the rubber stopper is higher than a coefficient of friction between the inner cover and the cap
Data Source
AI summary
To provide a plastic cap that can be smoothly applied to either a synthetic resin or glass pharmaceutical container, which can maintain airtightness with no rotation of a rubber stopper when applied to a mouth portion of the pharmaceutical container capped with the rubber stopper.Provided is a plastic cap attached to a pharmaceutical container, and the cap includes a top surface portion having an opening at the center thereof, a cylindrical skirt portion extending downward from an outer periphery of the top surface portion and opening at a lower end, and an inner cover inside the skirt portion, in which a coefficient of friction between the inner cover and the rubber stopper is higher than a coefficient of friction between the inner cover and the cap.