Hydrophobic Filter Separating Layer for Water Intrusion Resistance

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Solution Overview

Problem

Existing filter elements experience a significant reduction in air flow rate when exposed to water during a water intrusion test, leading to potential blockage and reduced performance in sterile filtration applications.

Innovation Solution

A sheet material with a hydrophobically modified fibrous separating layer, which maintains permeability to gaseous fluids by reducing wettability with polar liquids, is developed. This layer has a contact angle of at least 120° and is preferably oleophobic, ensuring minimal reduction in air flow rate even under pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a hydrophobic separating layer is used to prevent wetting by aqueous fluids, then water intrusion resistance is improved, but air flow rate is reduced during water intrusion test

Engineering Contradiction:

Improvewater intrusion resistanceVSAvoidair flow rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies parameter changes by modifying the surface properties of the separating layer through hydrophobic treatment, changing the contact angle parameter to at least 120°. This surface property modification prevents water wetting while maintaining air permeability, resolving the contradiction between water intrusion resistance and air flow rate retention.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining a base separating layer material with hydrophobic modifying agents or coatings. This composite structure provides both the functional properties of the base material and the water repellency of the hydrophobic treatment, enabling simultaneous achievement of water intrusion resistance and maintained air flow.

Inventive Principle:

Principle #40Composite materials

2Productivity

If the separating layer is made nonwoven fabric for drainage and support, then permeability to fluids is improved, but wettability by aqueous liquids increases

Engineering Contradiction:

Improvefluid permeabilityVSAvoidwettability by aqueous liquids

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the surface energy parameter of the nonwoven fabric through hydrophobic modification, increasing the contact angle to at least 120°. This parameter change maintains the permeability needed for fluid drainage while preventing wetting by aqueous liquids, resolving the contradiction between fluid permeability and wettability.

Inventive Principle:

Principle #35Parameter changes

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 hydrophobically modified fibrous separating layer maintains high air flow rates through the filter element, with a reduction of no more than 35% after a water intrusion test, ensuring effective sterile filtration without blockage.

Implementation Method 1

a hydrophobically modified fibrous separating layer (B), wherein the separating layer (B) has a contact angle of at least 120° in relation to water

Methodology Applied

Scientific EffectHydrophobic modification: Hydrophobe

Data Source

PatentUS11285424B2Sheet material and filter element with hydrophobic separating layer, use thereof and process for production of same

Publication Date: 2022.03.29 SARTORIUS STEDIM BIOTECH GMBH

AI summary

The present invention relates to a sheet material and filter element, where the sheet material and the filter element have a hydrophobic separating layer, and also to use thereof and to a process for production of same.