PVC Medical Needle Hub and Protector for Easy Separation
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Solution Overview
Problem
The replacement of di-2 ethylhexyl phthalate (DEHP) with trimellitates as plasticizers in medical needle hubs and protectors results in difficulty in separating the protector from the hub and concerns of misalignment with the needle body due to differing material properties.
Innovation Solution
A medical needle design with a hub and protector where the hub contains 10 to 20 phr of trimellitate in a polyvinyl chloride (PVC) resin composition and the protector contains 40 to 50 phr of trimellitate in a PVC resin composition, facilitating easy separation and retention of the protector from the hub.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If trimellitate is used as a plasticizer in both the hub and protector with the same concentration, then the material properties are simplified, but the protector becomes difficult to separate from the hub and the needle body may misalign with the hub
Solution Approach 1:
The patent applies different concentrations of trimellitate plasticizer in different components: 10-20 phr in the hub and 40-50 phr in the protector. This local differentiation optimizes each component's properties - the hub maintains sufficient hardness for structural support and needle retention, while the protector achieves appropriate flexibility and hardness for easy separation through rotational torque application.
Solution Approach 2:
The patent changes the plasticizer concentration parameter from a uniform value to differentiated values across components. By adjusting the trimellitate content from 10-20 phr in the hub to 40-50 phr in the protector, the material achieves optimal balance between separation ease and structural integrity without requiring complex multi-component formulations.
2Ease of operation
If the protector has high hardness for easy separation, then separation torque is reduced, but the retaining force on the needle body may be insufficient causing misalignment
Solution Approach 1:
The patent creates local quality differentiation by assigning different plasticizer concentrations to different components. The hub (10-20 phr trimellitate) provides strong retaining force for needle alignment, while the protector (40-50 phr trimellitate) provides optimal hardness for easy separation. This resolves the contradiction by making each component specialized for its function.
Solution Approach 2:
The patent uses composite resin compositions combining PVC base resin with trimellitate plasticizer at different ratios in different components. This composite material approach allows independent optimization of mechanical properties in the hub versus the protector, achieving both reliable needle retention and easy protector separation simultaneously.
Data Source
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AI summary
A medical needle (10) includes a needle body (12), a hub (14), and a protector (16). The hub includes a first resin composition. The protector has a needle sheath (50) that covers a part of the needle body. The needle sheath includes a second resin composition. The first resin composition and the second resin composition each contain polyvinyl chloride and a trimellitate. In the first resin composition, the trimellitate accounts for 10 to 20 phr. In the second resin composition, the trimellitate accounts for 40 to 50 phr.