Mercaptofunctional Silane Coupling Agent for Filled Elastomers
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Solution Overview
Problem
Existing mercaptosilanes used in filled elastomers are highly reactive, leading to short scorch times, poor filler dispersion, and high VOC emissions, which hinder the processing and performance of filled elastomers, such as tires, by increasing rolling resistance and heat build-up.
Innovation Solution
Development of mercaptofunctional silanes with specific structures, such as those represented by Formula (1), which are prepared by reacting mercaptosilanes with polyhydroxy-containing compounds, reducing VOC emissions and improving filler dispersion and coupling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mercaptosilanes are used as coupling agents in filled elastomers, then filler coupling performance is improved, but scorch time becomes short and filler dispersion becomes poor
Solution Approach 1:
The mercaptosilane is pre-reacted with the filler surface during the mixing stage before vulcanization occurs. This preliminary coupling action ensures that the silane is already bonded to the filler when vulcanization begins, preventing premature crosslinking and maintaining adequate scorch time while achieving good filler coupling performance
Solution Approach 2:
The invention changes the chemical structure parameters of the mercaptosilane by using specific alkoxysilyl groups (such as trialkoxysilyl) and controlling the mercaptan content within specific ranges (0.1-10 mmol/g). These parameter changes optimize the reactivity to achieve balanced coupling performance and processing time
2Reliability
If conventional mercaptosilanes are used at levels necessary for optimum coupling, then filler coupling is improved, but filler dispersion becomes poor
Solution Approach 1:
The mercaptosilane provides localized coupling functionality at the filler surface through its mercaptan groups, while the alkoxysilyl groups provide localized bonding to the filler surface. This local quality differentiation ensures that coupling occurs primarily at the filler-elastomer interface without causing aggregate formation, maintaining good dispersion
Solution Approach 2:
The mercaptosilane acts as an intermediary coupling agent between the inorganic filler and the organic elastomer matrix. It mediates the interface by providing both inorganic-compatible (alkoxysilyl) and organic-compatible (mercaptan) functional groups, achieving good coupling without compromising filler dispersion
3Reliability
If monoalcohol-based silanes are used, then coupling performance is achieved, but volatile organic compound emissions increase
Solution Approach 1:
The invention changes the chemical composition parameters by replacing monoalcohol-based silanes with polyol-based silanes containing multiple hydroxyl groups. This parameter change reduces VOC emissions because polyols have lower volatility and the silane structure itself is designed to minimize harmful emissions while maintaining coupling performance through the mercaptosilane functionality
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 use of mercaptofunctional silanes with cyclic and bridging dialkoxysilyl groups enhances the processing and end-use properties of filled elastomers by reducing VOC emissions, improving filler dispersion, and maintaining low processing viscosity, thereby enhancing wear resistance and reducing rolling resistance and heat build-up.
Implementation Method 1
mercaptosilanes and their use as coupling agents in filled elastomers are known in the art
Implementation Method 2
the uncured filled elastomer typically exhibits short scorch times and poorly dispersed filler
Implementation Method 3
reduce or eliminate the generation of volatile organic compounds (VOC's) during use
Implementation Method 4
maintaining low processing viscosity
Data Source
AI summary
A filled elastomer composition comprises:a) at least one rubber component;b) at least one particulate filler; and,c) at least one mercaptofunctional silane of a particular structure.