Derivatized Silica Reinforcement for Low Hysteresis Elastomers
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Solution Overview
Problem
Current elastomeric materials for tires face challenges in achieving a balance between mechanical reinforcement and low hysteresis, particularly in ultra-low rolling resistance and self-supporting tires, where silica fillers do not provide sufficient reinforcement and are prone to the Payne effect, leading to reduced dynamic modulus under deformation.
Innovation Solution
The use of derivatized silica, obtained by reacting silica with specific silanising agents and silsesquioxanes featuring reactive alkenyl functionalities, which enhances cross-linking and prevents re-aggregation of silica particles, thereby improving mechanical performance and reducing hysteresis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If silica fillers are used to reduce hysteresis, then rolling resistance decreases, but reinforcement is insufficient for demanding applications
Solution Approach 1:
The patent uses composite materials by combining silica particles with silane coupling agents that have reactive alkenyl functionalities. This creates a hybrid filler system where the silane acts as a bridge between the silica surface and the elastomer matrix, providing both the low hysteresis benefit of silica and the reinforcement needed for demanding tire applications through improved interfacial bonding.
Solution Approach 2:
The patent changes the chemical parameters of the silica filler by introducing silane coupling agents with specific reactive alkenyl groups. This modification transforms the surface chemistry of silica, enabling covalent bonding with the elastomer and fundamentally altering the filler-matrix interaction from physical adsorption to chemical bonding, thereby enhancing reinforcement while maintaining low hysteresis.
2Strength
If carbon black is used to improve reinforcement, then mechanical properties improve, but hysteresis increases leading to higher rolling resistance
Solution Approach 1:
The patent replaces the traditional carbon black filler with a silica-based system. While silica itself provides insufficient reinforcement, the addition of silane coupling agents creates a durable bonding interface that compensates for silica's inherent limitations, effectively substituting carbon black's reinforcement mechanism with a different chemical approach that also reduces hysteresis.
Solution Approach 2:
The silane coupling agent acts as an intermediary between the silica filler and the elastomer matrix. It provides reactive alkenyl groups that form covalent bonds with the polymer chains, mediating the interaction between filler and matrix to achieve both reinforcement and low hysteresis, thereby resolving the trade-off between mechanical properties and energy loss.
3Stress or pressure
If cross-linking is increased to improve reinforcement, then modulus increases, but material becomes brittle and strength decreases
Solution Approach 1:
The patent applies local quality by concentrating cross-linking at the filler-matrix interface through silane coupling agents. The reactive alkenyl groups on the silane form localized cross-links between the silica surface and elastomer chains, providing reinforcement at the critical interface region without requiring bulk cross-linking of the entire polymer matrix, thus avoiding brittleness.
Solution Approach 2:
The silane coupling agents are incorporated during the mixing stage, before vulcanisation, allowing them to adsorb onto the silica surface and prepare the interface for subsequent cross-linking. This preliminary action ensures that when vulcanisation occurs, the cross-links form preferentially at the filler-matrix interface rather than uniformly throughout the bulk material.
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
This approach results in elastomeric materials with significantly higher moduli and reduced hysteresis, enabling the use of smaller filler amounts and expanding application possibilities, including demanding applications like bead and bead protective layers without increasing cross-linking or using hardening resins.
Implementation Method 1
derivatized silica, obtained by reacting silica with specific silanising agents and silsesquoxanes featuring reactive alkenyl functionalities, which enhances cross-linking
Implementation Method 2
prevents re-aggregation of silica particles
Data Source
AI summary
The present invention relates to new elastomeric materials for the production of tyres for vehicle wheels with good mechanical properties, in particular high moduli associated with low hysteresis values, including new reinforcement materials. Said reinforcement materials are obtainable by derivatising silica—in-situ during the mixing of the elastomeric composition, or previously—with special silanising agents (A) and silsesquioxanes (B), both substituted with reactive alkenyl functionalities.