Lignin-Based Epoxy Resin Coating for Metal Food Containers

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Solution Overview

Problem

The challenge lies in replacing Bisphenol-A (BPA) based epoxy resin coatings in metal food and beverage cans due to toxicity concerns and regulatory pressures, while maintaining the properties of non-renewable petrochemical precursors, as BPA is an endocrine disruptor and has widespread human exposure, leading to contamination and spoilage issues.

Innovation Solution

A composition comprising lignin, a catalyst such as triethylenetriamine or triethylamine, and an epoxy-group containing compound is used to create a lignin-based epoxy resin coating, which can be directly applied or modified to enhance reactivity, reducing BPA usage and providing a renewable alternative with similar properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If BPA-based epoxy resin coatings are used to provide protective coating on metal containers, then excellent adhesiveness and protective properties are achieved, but toxicity concerns and endocrine disruption effects occur leading to contamination and spoilage issues

Engineering Contradiction:
Improveprotective propertiesVSAvoidtoxicity
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters by replacing BPA-based epoxy resin with lignin-based epoxy resin. This substitution maintains the protective functionality while eliminating the toxic effects of BPA, thereby resolving the contradiction between reliability and harmful factors.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes lignin, a renewable and abundant by-product from the pulp and paper industry, as a substitute for BPA. This approach not only eliminates toxicity but also provides a cost-effective and sustainable alternative, addressing both the harmful factors and economic considerations.

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

2Object-affected harmful factors

If lignin is used as a substitute for BPA to reduce toxicity, then renewable and non-toxic properties are achieved, but maintaining similar performance properties to petrochemical precursors becomes challenging

Engineering Contradiction:
ImprovetoxicityVSAvoidperformance properties
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent creates a composite epoxy resin system by combining lignin with other compatible materials. This composite approach allows the lignin-based resin to achieve performance properties similar to traditional petrochemical precursors while maintaining its non-toxic and renewable characteristics.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical and physical parameters of lignin through various processing techniques to enhance its reactivity and performance. By adjusting parameters such as molecular weight, functional group content, and crosslinking density, the lignin-based epoxy resin achieves performance comparable to BPA-based systems.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If conventional epoxy resin formulations are replaced with lignin-based formulations, then sustainability and renewability are improved, but manufacturing process complexity increases

Engineering Contradiction:
ImprovesustainabilityVSAvoidmanufacturing process
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent performs preliminary modification of lignin before incorporating it into the epoxy resin formulation. This pre-processing step, which may include depolymerization, purification, or functionalization, simplifies the subsequent manufacturing process by ensuring the lignin is in the optimal form for reaction, thereby reducing overall process complexity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces intermediary substances or catalysts that facilitate the reaction between lignin and epoxy compounds. These intermediaries help overcome the inherent complexity of working with natural polymers by providing well-defined reaction pathways and improving process control.

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 lignin-based epoxy resin coatings demonstrate excellent adhesiveness, flexibility, and resistance to various solvents and pH levels, offering a sustainable and non-toxic solution for metal coatings, particularly in food containers, while reducing BPA dependency.

Implementation Method 1

A composition comprising lignin, a catalyst selected from the group consisting of triethylenetriamine (TETA), triethylamine (TEA) and combinations thereof and one or more epoxy-group containing compounds

Methodology Applied
Scientific EffectCatalysis: Catalysis

Implementation Method 2

one or more epoxy-group containing compounds

Methodology Applied
Scientific EffectChemical Bonding: Chemical Bonding

Data Source

PatentEP3049489B1A composition comprising lignin and epoxy compound for coating and method for the manufacturing thereof and use thereof
Publication Date: 2018.11.14 STORA ENSO OYJ

AI summary

The present invention relates to a composition for coating, in particular a composition comprising lignin and one or more epoxy-group containing compounds,and methods for the manufacturing thereof and uses thereof. The present invention also relates to products obtainable by said methods and uses thereof.