Essential Oil Separating Medium for Adhesive Bond Breakdown

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Solution Overview

Problem

Multilayer composites used for food packaging face challenges in separating individual layers after consumption, as crosslinked adhesive polymers have low solubility, making it difficult to recycle and sort materials effectively, with existing methods being limited in applicability and often requiring hazardous or flammable substances.

Innovation Solution

A separating medium containing essential oils such as phenols, phenylpropanoids, and furanocoumarins is used to weaken adhesive bonds, allowing for the separation of adherends without damaging them, using an aqueous emulsion with a preferred concentration of ≥0.5% essential oils by volume, which can be applied directly or encapsulated in adhesives and precoats.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If crosslinked adhesive polymers are used to bond multilayer composites, then bonding strength and stability are improved, but separability and recyclability deteriorate due to low solubility

Engineering Contradiction:
Improvebonding strengthVSAvoidseparability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The adhesive is formulated with encapsulated essential oils incorporated during the adhesive manufacturing stage. These encapsulated oils remain dormant during bonding but are activated during separation, preliminarily preparing the adhesive for controlled degradation without compromising initial bond strength

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The chemical properties of the adhesive are changed by incorporating essential oils (phenols, phenylpropanoids, furanocoumarins) that can chemically interact with the crosslinked polymer structure. This modification allows the adhesive to maintain crosslinked stability during use but become susceptible to degradation when exposed to specific chemical agents, enabling separability

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If conventional separating agents are used to release adhesive bonds, then separation is achieved, but hazardous and flammable substances are introduced

Engineering Contradiction:
Improveseparation capabilityVSAvoidhazardous substances
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The invention uses natural essential oils that are biodegradable and environmentally friendly alternatives to conventional hazardous separating agents. These natural substances perform the separation function temporarily and then degrade, leaving no harmful residues

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

Certain essential oils contain phenolic compounds with oxidizing properties that can break down the crosslinked adhesive polymers through oxidation reactions, providing an effective separation mechanism that avoids the need for harsh chemical solvents or flammable substances

Inventive Principle:
Principle #38Strong oxidants (Accelerated oxidation)

3Productivity

If existing separation methods are applied to multilayer composites, then some bonds are released, but applicability is limited and complete separation is difficult

Engineering Contradiction:
Improveseparation efficiencyVSAvoidapplicability
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The adhesive formulation incorporates multiple types of essential oils (phenols, phenylpropanoids, furanocoumarins) that can interact with different types of polymer structures. This multi-component approach gives the adhesive universal compatibility with various multilayer composite configurations, enabling complete separation across different material combinations

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The essential oils act as intermediary substances between the crosslinked adhesive and the separation process. These oils penetrate the adhesive layer and mediate the breakdown of crosslinks, facilitating complete separation of all layers in the composite structure

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 method effectively reduces the strength of adhesive bonds, enabling complete separation of multilayer composite materials with minor mechanical stress, facilitating recycling and material sorting without using hazardous substances, and demonstrating enhanced separation efficiency with phenylpropanoids like eugenol.

Implementation Method 1

A separating medium, containing at least one essential oil or consisting of at least one essential oil, selected from the group consisting of phenols, phenylpropanoids and furanocoumarins, for the separation of adherends which are bonded to one another by means of adhesive bonds

Methodology Applied
Scientific EffectChemical interaction: Chemical Bonding

Data Source

PatentUS12084600B2Use of essential oils for separating adhesive bonds
Publication Date: 2024.09.10 COVESTRO DEUTSCHLAND AG

AI summary

The invention relates to the use of a separating medium, containing at least one essential oil or consisting of at least one essential oil, selected from the group consisting of phenols, phenylpropanoids and furanocoumarins, for separating at least two joining parts which are joined by means of an adhesive bond.