Flexible PVC-EVOH Multilayer Geomembrane Barrier

Solution Overview

Problem

Existing geomembranes lack a practical solution for combining PVC and EVOH layers due to thermal sensitivity and adhesion issues, resulting in a multilayer sheet that is neither flexible nor effective as a barrier against organic solvents and gases.

Innovation Solution

A multilayer sheet comprising a PVC outer layer, an EVOH core layer, and an ethylene terpolymer internal layer, which can be thermally laminated without adhesives, achieving flexibility and barrier properties suitable for geomembrane applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If PVC is used for geomembrane to achieve good flexibility, then flexibility is improved, but resistance to organic solvent migration deteriorates due to plasticizer bleeding

Engineering Contradiction:

ImproveflexibilityVSAvoidresistance to organic solvent migration

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The geomembrane is divided into multiple functional layers: a PVC layer (providing flexibility) and an EVOH layer (providing barrier properties). This segmentation allows each layer to specialize in one function, resolving the contradiction between flexibility and solvent resistance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining PVC and EVOH materials. The PVC layer provides flexibility and ease of operation, while the EVOH layer provides excellent barrier properties against organic solvent migration, achieving both requirements simultaneously.

Inventive Principle:

Principle #40Composite materials

2Reliability

If EVOH is used as multilayer sheet to achieve excellent barrier properties, then resistance to organic solvent migration is improved, but flexibility deteriorates making it difficult to apply

Engineering Contradiction:

Improvebarrier propertiesVSAvoidflexibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The geomembrane is divided into multiple functional layers: a PVC layer (providing flexibility) and an EVOH layer (providing barrier properties). This segmentation allows each layer to specialize in one function, resolving the contradiction between flexibility and solvent resistance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining PVC and EVOH materials. The PVC layer provides flexibility and ease of operation, while the EVOH layer provides excellent barrier properties against organic solvent migration, achieving both requirements simultaneously.

Inventive Principle:

Principle #40Composite materials

3Ease of operation

If PVC and EVOH layers are combined to achieve both flexibility and barrier properties, then both flexibility and barrier properties are improved, but manufacturing complexity increases due to thermal sensitivity and adhesion issues

Engineering Contradiction:

ImproveflexibilityVSAvoidmanufacturing process

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The invention controls the thickness parameters of each layer (PVC layer 50-500 μm, EVOH layer 10-100 μm) and uses thermal lamination at controlled temperatures to join layers without adhesives. This parameter optimization resolves the manufacturing complexity while maintaining both flexibility and barrier properties.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses thermal energy as an intermediary to join the PVC and EVOH layers through thermal lamination, eliminating the need for adhesive intermediaries. This simplifies the manufacturing process while achieving strong interlayer bonding despite thermal sensitivity differences.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution provides a flexible and effective barrier against organic solvents and gases, suitable for long-term geomembrane use, with a permeation coefficient for benzene, toluene, ethyl benzene, and xylene of less than 0.1*10−10 m2/s.

Implementation Method 1

EVOH is known for its low permeation of gases and VOC relative to other commonly-used thermoplastic polymers

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

an ethylene terpolymer can adhere to PVC by thermal laminating

Methodology Applied

Scientific EffectThermal lamination: Welding

Data Source

PatentUS10836146B2Flexible geomembrane

Publication Date: 2020.11.17 KURARAY CO LTD

AI summary

Provided is a polyvinyl chloride (“PVC”)/ethylene-vinyl alcohol (“EVOH”) multilayer sheet used for the fabrication of liners and covers for the geotechnical industry (“geomembrane”), which sheet has both good flexibility and excellent barrier properties to organic solvents and gases.