Single layer expansion tank membrane

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Solution Overview

Problem

Existing expansion tank membranes made of vulcanized rubber are not suitable for potable water systems due to permeability issues, oxygen leakage, and difficulty in recycling, while multi-layer membranes are complex to produce.

Innovation Solution

A single-layer membrane composed of a thermoplastic olefin block copolymer (TOBC) with a cross-linked network of olefinic hard and soft segments, eliminating the need for chemical cross-linking and enabling easy production and recycling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If vulcanized rubber membranes are used, then gas barrier properties are improved, but water permeability increases and they are not suitable for potable water systems

Engineering Contradiction:

Improvegas barrier propertiesVSAvoidwater permeability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses a multi-layer composite membrane structure combining EPDM rubber layer (for gas barrier properties) and a potable water-safe layer (for water impermeability and food contact safety). This composite approach allows the membrane to simultaneously achieve excellent gas barrier properties while maintaining water impermeability and suitability for potable water systems.

Inventive Principle:

Principle #40Composite materials

2Reliability

If multi-layer membranes are used, then water and gas impermeability are improved, but manufacturing complexity increases

Engineering Contradiction:

Improvewater and gas impermeabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple functional layers into a single integrated membrane structure where the EPDM rubber layer and potable water-safe layer are combined in one component. This unified design maintains the water and gas impermeability benefits of multi-layer membranes while simplifying manufacturing by reducing the number of separate components that need to be assembled.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If vulcanized rubber membranes are used, then mechanical strength is improved, but recyclability decreases

Engineering Contradiction:

Improvemechanical strengthVSAvoidrecyclability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the chemical parameters of the membrane by using thermoplastic materials with controlled crystallinity and molecular weight. These parameter changes allow the membrane to maintain mechanical strength through physical entanglement and crystalline structures while enabling recyclability through melting and reshaping capabilities, eliminating the need for chemical cross-linking.

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If TPU membranes are used, then ease of processing is improved, but water permeability increases

Engineering Contradiction:

Improveease of processingVSAvoidwater permeability

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent combines TPU (for ease of processing) with a potable water-safe layer (for water impermeability). This composite structure allows the membrane to benefit from TPU's excellent processability and elasticity while the additional layer provides the necessary water barrier properties, resolving the contradiction between ease of processing and water permeability.

Inventive Principle:

Principle #40Composite materials

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 single-layer membrane provides improved gas and water barrier properties, reduced permeability, and ease of production, with a lifespan comparable to vulcanized rubber membranes.

Implementation Method 1

A membrane for an expansion tank can separate two compartments of an expansion tank. This means that such a membrane requires a peripheral edge which is configured to be clenched between a first housing part and a second housing part of an expansion tank.

Methodology Applied

Scientific EffectPhysical cross-linking:

Implementation Method 2

The single layer membrane provides improved gas and water barrier properties, reduced permeability

Methodology Applied

Scientific EffectPermeation barrier: Permeation

Implementation Method 3

Expansion tank membranes should be able to withstand a large number of pressure cycles, in which the membrane is expanded and retracted as a result of pressure variations within the system.

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP3781874B1Single layer expansion tank membrane

Publication Date: 2026.03.18 AALBERTS HFC BV

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Figure 2a~2b
Figure 2c~2d

AI summary

The invention relates to a single layer membrane for an expansion tank. The single layer membrane comprises an thermoplastic olefin block copolymer. The properties of the membrane are at least comparable to those of conventional single layer expansion tank membranes made from vulcanized rubber. The present single layer membrane is recyclable and easy to produce.