Flexible Polyurea-EVOH Geomembrane Adhesion

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Solution Overview

Problem

Existing geomembranes lack both good flexibility and excellent barrier properties to organic solvents and gases, particularly in geotechnical applications requiring high flexibility, and do not effectively combine a chemical-resistant polyurea layer with an ethylene-vinyl alcohol copolymer (EVOH) barrier layer without an adhesive layer.

Innovation Solution

A multilayer article comprising a chemical-resistant polyurea layer and a barrier layer of EVOH, where the polyurea layer is mixed and allowed to react before being applied to the EVOH barrier layer, achieving adhesion without a separate adhesive layer, and optionally including a thermoplastic resin or tie layer for enhanced adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a multilayer sheet is made with EVOH and polyolefin layers bonded together, then barrier properties to gases and VOC are improved, but flexibility deteriorates making the material stiff and difficult to apply

Engineering Contradiction:

Improvebarrier propertiesVSAvoidflexibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the material parameters by replacing polyolefin layers with polyurea layers, which have different physical and chemical properties. Polyurea provides both the required barrier properties and the necessary flexibility, resolving the contradiction between barrier performance and ease of operation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system combining EVOH and polyurea layers. This composite structure leverages the strengths of both materials: EVOH provides excellent barrier properties against gases and VOC, while polyurea contributes flexibility and toughness, achieving both improved reliability and ease of operation simultaneously.

Inventive Principle:

Principle #40Composite materials

2Strength

If a polyurea layer is thermally pressed with EVOH layer, then adhesion between layers is improved, but no significant adhesion is achieved instead

Engineering Contradiction:

ImproveadhesionVSAvoidbonding effectiveness

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent replaces the mechanical/thermal bonding system (thermal pressing) with a chemical bonding system. By introducing a polyurea-compatible resin layer with appropriate polarity and surface energy, the bonding mechanism shifts from physical adhesion through heat and pressure to chemical adhesion through molecular interactions, achieving reliable layer bonding.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a polyurea-compatible resin layer as an intermediary between the polyurea layer and EVOH layer. This intermediate layer facilitates adhesion by providing compatible surface properties that enable bonding, solving the problem of poor adhesion between the incompatible polyurea and EVOH materials.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If a separate adhesive layer is added between polyurea and EVOH layers, then adhesion is improved, but device complexity increases

Engineering Contradiction:

ImproveadhesionVSAvoidlayer structure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent merges the adhesive function into the existing polyurea-compatible resin layer, eliminating the need for a separate adhesive layer. This integration maintains strong adhesion between layers while reducing structural complexity, as the same layer serves both as a structural component and as the bonding interface.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The polyurea-compatible resin layer is designed to serve multiple functions: it provides structural integrity, ensures chemical compatibility with polyurea, enables adhesion between layers, and contributes to the overall barrier properties. This multi-functionality eliminates the need for separate adhesive layers, reducing device complexity while maintaining adhesion strength.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 geomembrane with superior flexibility, toughness, and chemical resistance, effectively barrier-resistant to organic solvents and gases, suitable for long-term geotechnical applications without the need for additional adhesive layers.

Implementation Method 1

when the liquid polymer components for polyurea were mixed, allowed to react, and applied prior to curing onto a barrier layer containing a polyurea-compatible resin

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

It was believed that both polarity and surface energy of the polyurea-compatible resin directly contacting polyurea may contribute to good adhesion to the liquid polyurea in uncured or partially cured form

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS20230294378A1Flexible geomembrane

Publication Date: 2023.09.21 KURARAY CO LTD

AI summary

A multilayer article including a chemical-resistant layer comprising a polyurea, where the chemical-resistant layer is not an adhesive layer between two layers, and a barrier layer comprising an ethylene-vinyl alcohol copolymer. The multilayer article has good flexibility and toughness, resistance to water and chemicals, and excellent barrier properties to organic solvents and gases.