Cationic Silica Tire Rubber Compounds With Reversible Filler Bonding

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Solution Overview

Problem

The recycling of diene rubber compounds reinforced with silica is hindered by strong covalent bonds formed during the sulfur vulcanization process and silane coupling, making it difficult and energetically costly to break these bonds, thus limiting the recyclability and sustainability of tire materials.

Innovation Solution

Chemically modifying the silica surface with a cationic moiety that forms a reversible cation-π interaction with diene rubber chains, reducing the extent of covalent bonding and allowing for easier recycling while maintaining mechanical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If silane coupling agents are used to form covalent bonds between silica and diene rubber chains, then filler dispersion and mechanical reinforcement are improved, but recyclability is severely restricted due to the strength of covalent bonds

Engineering Contradiction:

Improvemechanical reinforcementVSAvoidrecyclability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the chemical nature of the interaction between silica and rubber from covalent bonds to non-covalent cation-π interactions. This parameter change in bond type allows the filler-rubber interface to maintain strong mechanical reinforcement while enabling reversible separation during recycling, thus resolving the contradiction between strength and recyclability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a reversible, non-permanent bonding mechanism (cation-π interaction) instead of permanent covalent bonds. This allows the rubber compound to be effectively 'disassembled' during recycling without requiring energy-intensive bond breaking, making the recycling process economically viable while maintaining performance during use

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Strength

If sulfur vulcanization is used to cross-link diene rubber chains, then mechanical properties are improved, but the energy required to break these covalent bonds for recycling becomes prohibitively high

Engineering Contradiction:

Improvemechanical propertiesVSAvoidenergy required for recycling

Core Design Contradiction:

StrengthVSUse of energy by moving object

Solution Approach 1:

The patent introduces a dual-crosslinking system where sulfur cross-links provide mechanical strength during use, but the silica-filler interface uses reversible cation-π interactions instead of covalent bonds. This parameter change in bonding mechanism at the filler interface reduces the total energy required for recycling while maintaining mechanical properties

Inventive Principle:

Principle #35Parameter changes

3Strength

If conventional silica fillers with polar silanol groups are used, then rubber reinforcement is achieved, but aggregation occurs leading to poor dispersion and high compound viscosity

Engineering Contradiction:

Improverubber reinforcementVSAvoiddispersion quality

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent fundamentally changes the surface chemistry parameter of silica from polar silanol groups to cationic moieties. This parameter change eliminates the aggregation tendency of conventional silica while maintaining reinforcement capability through cation-π interactions with rubber chains, thus improving dispersion quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention converts the typically harmful polar surface chemistry of silica (which causes aggregation) into a beneficial cationic surface that actively promotes dispersion through electrostatic and cation-π interactions with rubber chains, transforming a disadvantage into an advantage

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 modified silica filler enhances the recyclability of diene rubber compounds while retaining key performance characteristics, such as mechanical strength and traction, and reduces the energy required for recycling, promoting sustainability in tire production.

Implementation Method 1

The surface of silica is chemically modified by covalent linkage of cationic moieties which are capable of forming a reversible cation-π interaction with the polymeric chains of the diene rubber

Methodology Applied

Scientific EffectCation-π interaction:

Data Source

PatentUS20230416502A1Rubber compounds for use in producing vehicle tires

Publication Date: 2023.12.28 BRIDGESTONE EURO NV SA

AI summary

The invention provides diene rubber-silica compounds comprising a diene rubber matrix having dispersed therein a silica filler, wherein said silica filler is surface-modified by covalent attachment of a cationic moiety which forms a cation-π interaction with the diene rubber matrix. In particular, it provides such compounds in which the diene rubber is styrene-butadiene rubber. Such compounds can be vulcanized and are suitable for producing vehicle tire components, such as tire treads.