Epoxy Diene Rubber Crosslinking for Strength and Recyclability

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Solution Overview

Problem

Sulfur-crosslinked rubbers are difficult to recycle due to irreversible crosslinking, and existing alternatives may not provide sufficient strength or material recycling properties.

Innovation Solution

A rubber composition is developed using a diene rubber with epoxy groups crosslinked by a dicarboxylic acid and an imidazole, introducing both ester and ionic bonds for re-bindable properties and improved strength, allowing for enhanced material recycling and strength improvement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If sulfur crosslinking is used to achieve strong rubber, then strength is improved, but recyclability deteriorates because the crosslinking is irreversible

Engineering Contradiction:

ImprovestrengthVSAvoidrecyclability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the chemical nature of crosslinking bonds from irreversible sulfur bonds to reversible ester bonds through transesterification reaction. This parameter change in bond reversibility enables both strong rubber properties and recyclability, resolving the contradiction between strength and ease of manufacture.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes sulfur crosslinking mechanism with ester bond crosslinking mechanism. By replacing the sulfur-based crosslinking system with a carboxylic acid-based esterification system, the rubber achieves both strength and recyclability through reversible ester bonds that can be broken and reformed.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If dicarboxylic acid crosslinking is used to achieve recyclability, then material recycling property is improved, but strength deteriorates due to insufficient crosslinking strength

Engineering Contradiction:

Improvematerial recycling propertyVSAvoidstrength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent creates a composite crosslinking system combining dicarboxylic acid ester bonds with imidazole ionic bonds. This composite approach integrates two different bonding mechanisms - the reversible ester bonds for recyclability and the strong ionic bonds for enhanced strength, thereby resolving the contradiction between material recycling property and strength.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent merges two crosslinking mechanisms - ester bond crosslinking from dicarboxylic acid and ionic bond crosslinking from imidazole - into a unified crosslinked rubber network. This combination allows the rubber to simultaneously achieve recyclability through ester bond reversal and sufficient strength through the synergistic effect of both bonding mechanisms.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If epoxide groups are crosslinked by dicarboxylic acid to form ester bonds, then self-restoring property is improved, but strength deteriorates due to insufficient crosslinking

Engineering Contradiction:

Improveself-restoring propertyVSAvoidstrength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent develops a composite crosslinked structure where epoxide groups crosslinked by dicarboxylic acid provide self-restoring property through reversible ester bonds, while additional imidazole ionic crosslinking provides enhanced strength. This composite material approach resolves the contradiction between self-restoring property and strength.

Inventive Principle:

Principle #40Composite materials

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 introduction of ionic crosslinking by imidazole in addition to ester bonds significantly improves the strength of the crosslinked rubber while maintaining self-restoring and reprocessing properties, enabling effective material recycling.

Implementation Method 1

the epoxy group is reacted with a carboxy group to form an ester bond

Methodology Applied

Scientific EffectEster bond formation: Chemical Bonding

Implementation Method 2

introducing ionic crosslinking by an imidazole

Methodology Applied

Scientific EffectIonic bonding: Chemical Bonding

Implementation Method 3

An ester bond is a re-bindable bond because it can be recombined by transesterification

Methodology Applied

Scientific EffectTransesterification: Chemical Bonding

Data Source

PatentUS20250019521A1Rubber composition, crosslinked rubber and tire

Publication Date: 2025.01.16 TOYO TIRE CORP

AI summary

A crosslinked rubber according to an embodiment contains a diene rubber having epoxy groups crosslinked with a dicarboxylic acid represented by the general formula (1) and an imidazole represented by the general formula (2). R1 in the formula (1) represents a divalent hydrocarbon group having 3 to 50 carbon atoms which is optionally interrupted by one or more hetero atoms. R2 in the formula (2) represents a hydrogen atom or a methyl group.HOOC—R1—COOH (1)