Functionalized Lignin Adhesive Bonding Strength

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Solution Overview

Problem

Current commercial adhesives derived from petrochemical feedstocks are not sustainable, and existing lignin-based adhesives struggle to bond effectively with a diverse range of substrates, including brittle materials like metals and wood.

Innovation Solution

A lignin-based adhesive composition that includes functionalized lignin and a hardener, such as a silyl ether crosslinker, at a weight ratio of 1:10 to 10:1, which is applied to substrates and cured to form a strong, durable adhesive resin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If conventional adhesives are used, then bonding strength is achieved, but sustainability is poor due to petrochemical feedstocks

Engineering Contradiction:

ImprovesustainabilityVSAvoidtoxic emissions

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters by using functionalized lignin with specific hydroxyl group contents (phenolic hydroxyl groups of 0.5-2.0 mmol/g and aliphatic hydroxyl groups of 1.0-3.0 mmol/g) to achieve both sustainability and bonding performance. This parameter optimization allows lignin-based adhesives to replace petrochemical adhesives while maintaining adhesion strength through controlled functional group content.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite adhesive system by combining functionalized lignin with specific hardeners (isocyanates, carboxylic acids, or anhydrides) in optimized weight ratios. This composite approach enhances the inherent properties of lignin while adding complementary functions from the hardener, achieving both environmental sustainability and mechanical bonding strength.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If lignin-based adhesives are used, then sustainability is improved, but adhesion to diverse substrates is insufficient

Engineering Contradiction:

ImprovesustainabilityVSAvoidadhesion to diverse substrates

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent applies local quality by creating specific functional zones within the adhesive composition. The functionalized lignin contains concentrated hydroxyl groups at specific locations within the molecular structure, enabling targeted adhesion to different substrate surfaces. This localized functional group distribution allows the adhesive to interact effectively with various substrate chemistries while maintaining overall composition sustainability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent achieves universality by designing functionalized lignin with multiple types of hydroxyl groups (phenolic and aliphatic) that can interact with different substrate types. The adhesive composition can bond to diverse substrates including metals, woods, and plastics through different adhesion mechanisms activated by the various functional groups, making the sustainable adhesive universally applicable across multiple material types.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Strength

If adhesive composition is optimized for strong bonding, then adhesion strength is improved, but resistance to environmental stress may be compromised

Engineering Contradiction:

Improveadhesion strengthVSAvoidresistance to water and thermal stress

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-functionalizing the lignin with specific hydroxyl groups before adhesive application. This pre-prepared functionalized lignin is designed to react with hardeners in controlled ways that create environmentally resistant bonds. The preliminary functionalization ensures that when the adhesive cures, it forms a crosslinked network that simultaneously achieves strong adhesion and resistance to water and thermal stress without requiring post-application adjustments.

Inventive Principle:

Principle #10Preliminary action

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 adhesive composition demonstrates strong adhesion to a variety of substrates, including metals, wood, and plastics, while maintaining mechanical strength and resistance to water and thermal stress for extended periods.

Implementation Method 1

The adhesive composition may include a functionalized lignin and a hardener. For instance, the hardener may include a silyl ether. The functionalized lignin and hardener may be present in the adhesive composition at a weight ratio of from about 1:10 to about 10:1.

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

curing the adhesive composition disclosed herein and the substrate to form an adhesive resin at the surface of the substrate

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentUS20250188332A1Lignin-based adhesives

Publication Date: 2025.06.12 UNIVERSITY OF SOUTH CAROLINA

AI summary

In general, the present disclosure is directed to an adhesive composition. The adhesive composition may include a functionalized lignin and a hardener. For instance, the hardener may include a silyl ether. The functionalized lignin and hardener may be present in the adhesive composition at a weight ratio of from about 1:10 to about 10:1.