Flexible Tubing Flow Rate Stability via Elastomer Composition
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Solution Overview
Problem
Conventional flexible tubing used in peristaltic pumps experiences significant variations in flow rate over time, leading to inconsistent chemical delivery, especially in the first several days of use, which can impact the quality of processes relying on precise chemical dispensing.
Innovation Solution
Development of flexible tubing with an annular cross-section comprising a continuous polypropylene phase and a non-cross-linked styrene block copolymer elastomer miscible with polypropylene, along with a cross-linked rubber phase, where the non-cross-linked styrene block copolymer elastomer is present in a range of 2 wt % to 15 wt %, resulting in a material that maintains a stable flow rate variation of less than 20% over 480 hours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional thermoplastic elastomer tubing is used, then the tubing can be processed via extrusion and is flexible enough for routing and compression, but the flow rate changes over time (dropping up to 30% in the first several days)
Solution Approach 1:
The patent changes the chemical composition parameters of the tubing material by incorporating a non-crosslinked styrene block copolymer elastomer (2-15 wt%) into the polypropylene matrix. This compositional parameter change stabilizes the flow rate while maintaining extrusion processability and flexibility, resolving the contradiction between ease of manufacture and reliability.
Solution Approach 2:
The patent creates a composite material system consisting of polypropylene as the continuous phase and non-crosslinked styrene block copolymer elastomer as the dispersed phase. This composite structure combines the processability and flexibility of polypropylene with the flow stability provided by the elastomer, simultaneously achieving ease of manufacture and flow rate stability.
2Reliability
If tubing material composition is modified to stabilize flow rate, then flow rate stability improves, but material composition complexity increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration range of the non-crosslinked styrene block copolymer elastomer (2-15 wt%). This quantitative parameter optimization achieves flow rate stability while avoiding excessive material complexity, as the modification involves adding a single polymer component within a defined concentration range rather than complex multi-component systems.
Data Source
AI summary
The present disclosure relates generally to flexible tubing, for example, suitable for use in peristaltic pumps. The present disclosure relates more particularly to flexible tubing having a stable flow rate despite being extruded from thermoplastic polymer and methods for making such tubing. In one aspect, at least 50% of the material volume of a flexible tubing of the disclosure is formed from a first polymer material that includes a continuous phase that includes polypropylene and a non-cross-linked styrene block copolymer elastomer miscible with the polypropylene, as well as, dispersed within the continuous phase (e.g., discontinuously dispersed within the continuous phase), a cross-linked rubber phase. The non-cross-linked styrene block copolymer elastomer is present in the first polymeric material in an amount in the range of 2 wt % to 15 wt %. In certain desirable embodiments of the flexible tubings described herein, the flexible tubing has a flow rate variation over the 480 hours of use of less than 20%.