Thermoplastic Elastomer Medical Cap with Pre-Compressed Plug
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Solution Overview
Problem
Conventional medical caps for infusion bottles face challenges in achieving a balance between cost-effectiveness and sealing properties, with rubber caps being costly due to contamination risks and thermoplastic elastomer caps experiencing residual distortion and leakage issues.
Innovation Solution
The medical cap design features a plug with a non-fused contact between the side surface and the outer frame's side circuit part, with pressure applied from the outer frame's leg part, and a molding process that maintains this configuration to enhance sealing and re-sealing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rubber plugs are used for medical caps, then re-sealing property and needle-holding capability are improved, but production cost increases and environmental contamination occurs due to vulcanizing process
Solution Approach 1:
The patent changes the material parameter from rubber to thermoplastic elastomer, which eliminates the need for vulcanizing process while maintaining elastic properties. This parameter change resolves the contradiction by enabling production without contamination-prone processes, thereby reducing cost while preserving re-sealing capability
Solution Approach 2:
The patent adopts thermoplastic elastomer plugs that can be produced via injection molding without requiring expensive vulcanizing equipment or post-cleansing processes. This makes the plug more cost-effective and environmentally friendly while maintaining functional performance
2Ease of manufacture
If thermoplastic elastomer plugs are used, then production cost decreases and manufacturing becomes easier, but residual distortion increases and re-sealing property deteriorates
Solution Approach 1:
The patent applies preliminary compression to the plug during the molding process, pre-compressing the thermoplastic elastomer material before it sets. This preliminary action compensates for the material's tendency to exhibit residual distortion, ensuring the plug maintains proper shape and sealing capability after cooling
Solution Approach 2:
The patent introduces a dynamic compression mechanism where the mold applies varying pressure during different stages of molding. The plug is compressed more intensely during initial formation and then maintained under controlled pressure, allowing the thermoplastic elastomer to set in a pre-compressed state that prevents later distortion
3Productivity
If thermoplastic elastomer plugs are used, then manufacturing process can be integrated and productivity increases, but needle-holding capability and sealing property deteriorate due to residual distortion
Solution Approach 1:
The plug is pre-compressed during injection molding before the material fully sets, ensuring proper density and shape. This preliminary compression prevents residual distortion that would otherwise compromise needle-holding capability, while still allowing the plug to be produced in one integrated molding step with the cap
Solution Approach 2:
The patent uses thermoplastic elastomer, which combines properties of both thermoplastics (easy molding) and elastomers (elasticity and sealing). This composite material approach enables mass production via injection molding while maintaining the elastic recovery needed for needle-holding and re-sealing functions
Data Source
AI summary
In the medical cap comprising a plug 10 made of thermoplastic elastomer and an outer frame 20 made of synthetic resin, the side surface part of the plug is contacted with an inner wall 211 of the side circuit part of the outer frame in a non-fused state and is held in a state with pressure applied from the leg part of the outer frame 22. As a result, the wetted surface of the plug is not flat shaped but has an inclination downward to the circle center. Protrusion 14 can also be provided on the wetted surface and in such a case, the bottom part of the protrusion part that is one part of the wetted surface has an inclination downward to the circle center.