Gradient Silicone Elastomeric Tube for Delamination Resistance
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Solution Overview
Problem
Single-layer silicone rubber lumens lack desired properties, while dual-layer lumens often experience delamination issues, especially under shear forces, and fail to meet the demands of emerging applications.
Innovation Solution
Coaxially coextruding two medical-grade silicone rubber compositions to form a gradient of properties throughout the tube, ensuring at least 1% to 99% of the tube is blended, with similar curing conditions using platinum or peroxide cross-linking, to create a stable and customizable elastomeric tube with enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dual-layer silicone rubber lumens are used to maximize desirable properties, then the tube can provide different properties at different surfaces, but delamination occurs at the interface particularly when subjected to shear forces
Solution Approach 1:
The patent applies local quality by creating a gradient structure where the composition transitions continuously from one layer to another. The outer layer has properties optimized for external environment resistance while the inner layer has properties optimized for internal contact, with intermediate transition zones that blend both compositions. This eliminates the sharp interface of dual-layer structures, preventing delamination while maintaining different properties at different surfaces.
Solution Approach 2:
The patent uses composite materials by combining multiple silicone rubber compositions with different properties in a single continuous structure. Instead of separate layers, the invention creates a composite gradient material where compositions are blended in specific ratios through the wall thickness, achieving both the benefits of multiple materials and the integrity of a single-layer structure.
2Reliability
If single-layer lumens are used, then the structure is simple and reliable, but the tube cannot possess all desired properties simultaneously
Solution Approach 1:
The patent applies parameter changes by varying the composition ratio continuously through the wall thickness of the tube. Instead of abrupt layer changes, the invention creates a gradient where the proportions of different silicone compositions change smoothly from the outer surface to the inner surface. This allows the tube to exhibit different properties at different locations while maintaining structural simplicity and reliability of a single continuous layer.
3Ease of manufacture
If conventional coextrusion is used to form dual-layer tubes, then the manufacturing process is straightforward, but the interface between layers creates delamination issues under shear forces
Solution Approach 1:
The patent applies dynamics by creating a dynamic gradient structure during the coextrusion process. Instead of forming static, distinct layers, the invention implements a dynamic blending mechanism that continuously mixes the compositions as they extrude. This dynamic approach ensures intimate mixing and strong interfacial bonding throughout the tube wall, eliminating delamination risks while maintaining ease of manufacture through the coextrusion process.
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 method produces a tube with maximized desired properties, avoiding delamination and providing improved abrasion resistance, tear strength, and crush resistance, while being compact and suitable for various medical and industrial applications.
Implementation Method 1
The curing method can be, for example, through hydrosilylation where an addition reaction of silicon-bonded lower alkenyl radicals with silicon-bonded hydrogen atoms occurs. Further, curing can be catalysed with, for example, platinum.
Implementation Method 2
Another curing option is peroxide initiated curing, where peroxide free radicals initiate the combination of pendant vinyl groups to form cross links.
Data Source
AI summary
In an elastomeric tube and a method for making such a tube, two medical-grade silicone rubber compositions are coaxially coextruded to form a tube. The compositions respectively differ in at least one physical property and respectively have similar curing conditions. The two compositions are blended at an interface formed between the two compositions during the coextruding, so that between 1-99% of the tube forms a blended gradient. The coextruded tube is then cured.