PVC Fluid Circuit Bonding With Reduced Plasticizer Migration

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Solution Overview

Problem

Existing blood processing systems face issues with plasticizer migration from PVC medical tubing, leading to potential leaks and compromised bond integrity in fluid processing assemblies, which can compromise sterility and longevity of the system.

Innovation Solution

Incorporating high molecular weight plasticizers (≥540 g/mol) and polymeric plasticizers, such as TEHTM and acrylate copolymers, into PVC tubing, and bonding these with solvent-compatible surfaces like polyester elastomers and polycarbonate to reduce plasticizer migration and enhance bond strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional plasticizers are used in PVC tubing, then the tubing achieves adequate flexibility, but plasticizer migration occurs leading to bond failure and potential leaks

Engineering Contradiction:

Improvetubing flexibilityVSAvoidbond integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent changes the molecular weight parameter of the plasticizer from conventional low molecular weight (e.g., DEHP with MW ~390) to high molecular weight (≥540 g/mol). This parameter change reduces the plasticizer's mobility and volatility, thereby minimizing migration to the bond interface while maintaining the required flexibility of the PVC tubing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite approach by combining high molecular weight plasticizers with polymeric plasticizers in the PVC tubing formulation. This composite material strategy creates a more stable plasticizer system that resists migration, thereby protecting the bond integrity between tubing and medical device components while preserving flexibility.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If solvent bonding is used to attach PVC tubing to medical device components, then assembly is simplified, but plasticizer migration compromises the bond strength over time

Engineering Contradiction:

Improveassembly simplicityVSAvoidbond longevity

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent applies preliminary anti-action by selecting plasticizers with high molecular weight and polymeric structures that inherently resist migration before the bonding process occurs. This preliminary selection prevents plasticizer from migrating to the bond interface during or after solvent bonding, thereby preserving bond strength and longevity without complicating the assembly process.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

By changing the molecular weight parameter of the plasticizer to ≥540 g/mol and using polymeric plasticizers, the patent reduces the plasticizer's tendency to migrate. This parameter change ensures that the solvent-bonded joint maintains its integrity over time, extending the duration of action of the bonded assembly.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If PVC tubing is used in blood processing systems, then the system benefits from PVC's processing advantages, but plasticizer migration poses health risks and compromises sterility

Engineering Contradiction:

ImprovePVC processing advantageVSAvoidplasticizer migration risk

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the molecular weight parameter of the plasticizer to high molecular weight (≥540 g/mol) and uses polymeric plasticizers, which significantly reduce migration potential. This allows continued use of PVC tubing with its manufacturing advantages while eliminating the harmful migration effect that poses health risks and compromises sterility in blood processing applications.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of plasticizer migration into a benefit by selecting high molecular weight and polymeric plasticizers that are too large and stable to migrate. This transforms the plasticizer from a harmful migrating substance into a stable, non-migrating component that maintains PVC flexibility without compromising patient safety or system sterility.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This approach minimizes plasticizer migration, reduces the risk of leaks, and strengthens the longevity of bonds between PVC tubing and medical device components, maintaining sterility and system integrity during blood processing.

Implementation Method 1

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

bonding these with solvent-compatible surfaces like polyester elastomers and polycarbonate

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 3

bonding these with solvent-compatible surfaces like polyester elastomers and polycarbonate to reduce plasticizer migration and enhance bond strength

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS12048782B2Fluid circuit having reduced plasticizer migration

Publication Date: 2024.07.30 FENWAL INC

AI summary

A fluid flow circuit assembly for a biological fluid processing device, comprising a PVC tubing comprising a polymeric plasticizer and/or a high molecular weight plasticizer having a molecular weight of 540 g/mol or more. The fluid flow circuit assembly also comprises a medical device component comprising a bond surface to which the PVC tubing is bonded by a solvent, wherein the bond surface comprises a polyester elastomer, plasticized PVC, and/or a polycarbonate.