Screw Cap Sterilization with Tear-Off Cover
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Solution Overview
Problem
Existing screw cap systems for containers are not effectively sterilizable and tamper-proof, especially in the area of the cover section and pierceable projection, leading to potential contamination and sterility issues during superheated steam sterilization, and are often cumbersome to handle with gloves.
Innovation Solution
A screw cap design featuring a sealed cover connected to the cover section surrounding the projection, with a gripping means for easy removal, manufactured using a multi-component injection molding process, ensuring the cover adheres to the cap and projection during sterilization but can be easily pulled off, incorporating a tamper-proof tear-off ring and materials like thermoplastic elastomers for sterility and ease of handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional screw cap with puncture closure is used, then the container can be closed and samples can be introduced, but sterility cannot be guaranteed during superheated steam sterilization and the system is not tamper-proof
Solution Approach 1:
The screw cap is divided into distinct functional segments: a cover section that can be separated from the cap part, a pierceable projection for sample introduction, and a sealing element. This segmentation allows the cover to be sterilized separately and ensures that the puncture area remains sterile until needed, while maintaining a relatively simple overall structure.
Solution Approach 2:
The cover section is designed to be pre-sterilized and attached to the cap part before use. The pierceable projection is pre-positioned to ensure proper alignment and sterility. This preliminary preparation ensures that sterility is maintained without requiring complex sterilization procedures during the actual sampling process.
2Reliability
If aluminum foil is heat sealed to the surface, then contamination is prevented, but this is an additional expensive work step and handling with gloves is difficult
Solution Approach 1:
The sealing function previously requiring separate aluminum foil application is merged into the plastic cap structure itself through integrated sealing elements and a sealed connection between the cover and cap part. This eliminates the need for additional foil sealing steps while maintaining contamination prevention, reducing manufacturing complexity and cost.
Solution Approach 2:
The sealing system uses homogeneous plastic materials throughout the cap structure, including the sealing element and cap part, eliminating the need for heterogeneous materials like aluminum foil. This simplifies manufacturing and improves handling consistency, especially when wearing gloves.
3Ease of operation
If the cover is detached or flipped away, then the puncture site can be accessed, but the system is no longer tamper-proof and sterility cannot be guaranteed
Solution Approach 1:
The cover connection is designed with dynamic characteristics - it remains firmly attached during normal handling and sterilization but can be easily removed when needed for puncture access. The tear-off ring provides a controlled failure mode that clearly indicates when the cover has been removed, maintaining tamper-evident functionality while enabling operational access.
Solution Approach 2:
The tear-off ring provides a visual indication system - when the cover is intact, the ring remains in place providing a clear visual cue of originality. When removed for puncture access, the absence or displacement of the ring clearly indicates the cover has been opened, maintaining tamper-evident capability without requiring complex mechanisms.
4Reliability
If steam accumulates under the lid during sterilization, then condensation occurs after cooling, but a sealed connection prevents this accumulation
Solution Approach 1:
The potential problem of steam accumulation is extracted and eliminated by designing the cover-section connection to be sealed from the outset. This prevents steam entrapment during sterilization and subsequent condensation, ensuring effective sterilization without requiring complex venting or drainage structures.
Solution Approach 2:
The sealed connection between cover and cap part, which might seem to trap steam during sterilization, actually converts this potential harm into a benefit by ensuring complete sterilization of the entire cap assembly including internal surfaces, while preventing post-sterilization condensation issues.
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 provides a sterilizable, tamper-proof system with reduced contamination risks, guaranteed sterility, and easy handling, ensuring the puncture site remains sterile and tamper-evident, while being cost-effective and integrated into the production process.
Implementation Method 1
The cover (14) is connected in a sealed manner to the cover section (5) surrounding the projection (7)... the cover preferably rests flat on the cover section and the projection substantially over the entire area facing the cover section... the cover adheres to the cover portion essentially over its entire surface facing the cover portion and the cover adheres to the surface of the projection facing the cover
Data Source
Figure 1~2
Figure 3~4
AI summary
The screw cap (1) has cap portion (2) that is provided with wall section (3) connected with internal thread (4). A sealing element (6) located on inner side of lid portion (5) has pierceable projection (7) that passes through passage (8) in lid portion. A cover portion (14) made of synthetic resin is provided on outer side of lid portion and connected to projection in circumferentially sealed manner. The lid portion and projection are connected to cover portion, and gripping unit (15) tears the cover portion from lid portion.