Two-Part Syringe Sealing Cap with Composite Housing and Insert
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Solution Overview
Problem
Existing syringe caps are too large due to the need for a single material that balances softness for sealing with stiffness for contact force, leading to increased packaging size and a trade-off in material properties for effective contamination prevention.
Innovation Solution
A two-part sealing cap with a housing and a sealing insert of different material properties, where the insert is softer and more flexible than the housing, allowing for a smaller size while maintaining effective sealing and contact pressure, and optionally featuring recesses and ribs for enhanced fit and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single material is used for the cap to provide both sealing softness and contact force stiffness, then the sealing interface quality is maintained, but the cap diameter increases and packaging space increases
Solution Approach 1:
The cap is divided into two distinct parts: a housing made of stiffer material and a sealing insert made of softer material. This segmentation allows each component to be optimized for its specific function - the housing provides structural support and contact force, while the sealing insert provides the necessary softness for the sealing interface, thereby reducing the overall cap size while maintaining sealing quality.
Solution Approach 2:
The cap uses composite construction with two different materials - a stiffer housing material (e.g., polypropylene or polyethylene) and a softer sealing insert material (e.g., thermoplastic elastomer or thermoset rubber). This composite approach allows the cap to simultaneously achieve the stiffness needed for contact force and the softness needed for sealing, without requiring increased cap diameter.
2Force
If a single material is used for the cap to provide sufficient thickness for contact force, then the necessary contact force is achieved, but the overall size of the cap increases
Solution Approach 1:
The cap structure is segmented into a housing and sealing insert, where the housing bears the primary load for providing contact force. This allows the sealing insert to be thinner since it doesn't need to provide the full contact force, thereby reducing the overall cap thickness while maintaining sufficient contact force through the housing structure.
Solution Approach 2:
By using a stiffer material for the housing and a softer material for the sealing insert, the housing can be designed with optimal thickness to provide the necessary contact force, while the sealing insert can be thinner since its primary function is sealing rather than force generation. This composite material approach optimizes the thickness distribution.
3Reliability
If a single material is used for the cap to ensure softness for sealing interface, then the sealing interface quality is improved, but the stiffness for contact force is reduced
Solution Approach 1:
The cap is segmented into a housing and sealing insert, with the housing made of stiffer material to provide contact force and the sealing insert made of softer material to ensure sealing interface quality. This segmentation resolves the contradiction by assigning different material properties to different functional zones of the cap.
Solution Approach 2:
The cap uses composite materials where the housing is made of a stiffer material (e.g., polypropylene with higher modulus) and the sealing insert is made of a softer material (e.g., thermoplastic elastomer with lower modulus). This composite construction allows the cap to simultaneously achieve the softness needed for the sealing interface and the stiffness needed for contact force generation.
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 reduces the overall size of the syringe cap while maintaining effective sealing and contamination prevention, ensuring a strong contact force without significant deformation or increased diameter, thus improving container closure integrity.
Implementation Method 1
The material of the housing may have a higher Young's modulus, higher strength, higher hardness, and/or lower elasticity than the material of the sealing insert
Implementation Method 2
create a seal between the sealing insert and an outer surface of the distal tip to keep air and contaminants from entering
Data Source
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AI summary
A sealing cap for a syringe having a syringe barrel defining a reservoir for containing a medicament and a distal tip having a passageway in fluid communication with the reservoir, the sealing cap including a housing having an open proximal end, a closed distal end, and a sidewall extending from the proximal end to the distal end and defining a cavity for receiving the distal tip, and a sealing insert covering at least a portion of an inner surface of the sidewall of the housing. The material properties of the housing are different from the material properties of the sealing insert, the inner diameter of the sealing insert is less than the outer diameter of at least a portion of the distal tip, and the sealing cap is adapted to cover the passageway and create a seal between the sealing insert and an outer surface of the distal tip.