Sulfoxide Silane Coupling Agent for Silica-Filled Rubber Mixing
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Solution Overview
Problem
The dispersion of silica particles in rubber compositions for vehicle tires is challenging due to their hydrophilic nature, leading to difficulties in mixing with hydrophobic rubber, and existing silane coupling agents can cause unpleasant odors, premature curing, and scorching.
Innovation Solution
A sulfoxide-functionalized silane coupling agent with a first coupling unit capable of forming a covalent bond with mineral oxide fillers and a second unit that reacts with unsaturated polymers, improving filler-polymer interactions without premature crosslinking, and reducing viscosity in filler-polymer mixtures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional silane coupling agents are used to improve silica dispersion in rubber, then filler-polymer bonding is enhanced, but unpleasant odors, premature curing, and scorching occur
Solution Approach 1:
The invention changes the chemical structure of the silane coupling agent by incorporating a sulfoxide group instead of traditional sulfur-containing groups. This parameter change in molecular structure eliminates the harmful effects (odors, premature curing, scorching) while maintaining the dual functionality of bonding to both silica and polymer matrix
Solution Approach 2:
The coupling agent represents a composite molecular structure combining silane functionality (for silica bonding) with sulfoxide functionality (for polymer interaction without harmful side effects). This composite approach integrates the beneficial properties of different functional groups while avoiding their individual drawbacks
2Reliability
If silica particles are added to improve wear resistance and reduce rolling resistance, then tire performance is enhanced, but dispersion difficulty arises due to hydrophilic-hydrophobic incompatibility
Solution Approach 1:
The silane coupling agent acts as an intermediary substance between hydrophilic silica particles and hydrophobic rubber matrix. The silane end bonds to silica surface while the organic end interacts with rubber, mediating the interface and enabling effective dispersion and bonding despite the hydrophilic-hydrophobic incompatibility
Solution Approach 2:
The coupling agent changes the surface properties of silica particles by introducing organic functional groups that are compatible with the hydrophobic rubber matrix. This parameter change in surface chemistry enables improved dispersion while maintaining the performance benefits of silica reinforcement
3Strength
If dual functionality silanes are used to bond polymer matrix to silica surface, then chemical bonding is achieved, but processability issues arise due to premature curing and scorching
Solution Approach 1:
The invention changes the reactivity parameters of the silane coupling agent by using sulfoxide functionality instead of traditional reactive groups. This reduces premature curing and scorching during processing while maintaining the ability to form strong chemical bonds between the polymer matrix and silica surface during vulcanization
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 silane coupling agent enhances the processability of rubber compositions, improves tread wear resistance, and balances rolling resistance and wet braking performance without the drawbacks of existing agents.
Implementation Method 1
The alkoxy group hydrolyzes in the presence of moisture typically found on the surface of the silica to form the corresponding silanol which reacts with or condenses in the presence of the silica surface to bond the silicon atom to the silica surface
Implementation Method 2
The second coupling unit is capable of reacting with an unsaturated polymer to form a covalent bond between the coupling agent and the polymer
Data Source
AI summary
A silane coupling agent suited to use in a rubber composition includes first and second coupling units. The first coupling unit including a silicon atom directly linked to a hydrolyzable group, which enables the silane coupling agent to bond to mineral filler particles. The second coupling unit includes a sulfoxide group linked to a leaving group, which enables the silane coupling agent to bond to an alkenyl group of an unsaturated polymer. A linking group connects the silicon atom of the first coupling unit to the sulfoxide group of the second coupling unit, to form a connection between the mineral filler particles and the polymer.