Electrospun ePTFE Composite Structure for Uniform PTFE Nanofibers

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Solution Overview

Problem

Conventional electrostatic spinning processes for polytetrafluoroethylene (PTFE) face challenges in achieving uniform and consistent fiber formation due to low viscosity dispersions and reverse polarity degradation, as well as failure to accommodate material shrinkage during sintering.

Innovation Solution

A process involving the formation of a dispersion with a viscosity of at least 50,000 cPs, comprising polymeric particles, a fiberizing polymer, and a solvent, which is electrospun onto an expanded polytetrafluoroethylene (ePTFE) layer, allowing for the creation of multilayered composite structures with improved mechanical and adhesive properties through controlled fiber formation and sintering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If low viscosity PTFE dispersions (15,000 cPs) are used in conventional electrostatic spinning processes, then the process is easier to operate, but uniform and consistent fiber formation cannot be achieved

Engineering Contradiction:

Improveease of operationVSAvoidfiber formation uniformity

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent changes the viscosity parameter of the PTFE dispersion from conventional low viscosity (15,000 cPs) to high viscosity (at least 50,000 cPs). This parameter change enables uniform and consistent fiber formation while maintaining ease of operation, directly resolving the technical contradiction between operational ease and manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If conventional electrostatic spinning processes are used with grounded spinning head and charged target, then the process setup is simple, but sample degradation occurs due to reverse polarity

Engineering Contradiction:

Improveprocess setup complexityVSAvoidsample integrity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent inverts the conventional polarity arrangement by using a charged spinning head and a grounded target, rather than the conventional grounded spinning head and charged target. This inversion eliminates sample degradation from reverse polarity while maintaining simple process setup, resolving the contradiction between device complexity and reliability.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of manufacture

If conventional electrostatic spinning processes are used, then the process is straightforward, but shrinkage of mat during sintering is not accommodated, resulting in limited mechanical integrity

Engineering Contradiction:

Improveease of manufactureVSAvoidmechanical integrity

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent applies preliminary action by pre-coating the target with an ePTFE layer before electrospinning the PTFE dispersion. This preliminary layer accommodates the shrinkage that occurs during sintering, preventing defects and enhancing mechanical integrity while maintaining ease of manufacture through a simple additional coating step.

Inventive Principle:

Principle #10Preliminary action

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 process results in multilayered composite structures with enhanced mechanical integrity, adhesion, and modified surface properties, suitable for various applications including medical, industrial, filtration, and consumer uses, by ensuring uniform fiber formation and accommodating material shrinkage during sintering.

Implementation Method 1

electrostatic spinning of polytetrafluoroethylene (PTFE) into continuous fiber

Methodology Applied

Scientific EffectElectrostatic spinning: Electrostatics

Implementation Method 2

Nanofibers from the dispersion are electrospun onto a first ePTFE layer

Methodology Applied

Scientific EffectElectrostatic deposition: Electrostatic Deposition

Implementation Method 3

The composite structure is heated

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 4

Conventional processes also fail to accommodate for shrinkage of a mat during sintering

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS8257640B2Multilayered composite structure with electrospun layer

Publication Date: 2012.09.04 ZEUS CO LLC

AI summary

In accordance with certain embodiments of the present disclosure, a process for forming a multilayered electrospun composite is provided. The process includes forming a dispersion of polymeric particles, a fiberizing polymer, and a solvent, the dispersion having a viscosity of at least about 50,000 cPs. Nanofibers from the dispersion are electrospun onto a first ePTFE layer. A second ePTFE layer is applied onto the nanofibers to form a composite structure. The composite structure is heated.