Silica Tread Rubber Composition for Wet Grip and Processability
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Solution Overview
Problem
Conventional pneumatic tires face challenges in achieving improved processability without negatively affecting wet grip properties and rolling resistance due to the poor dispersibility of silica in diene rubber, particularly when using silane coupling agents with mercapto groups, which can reduce scorch time and hinder complex tread pattern formation.
Innovation Solution
A tread rubber composition comprising 50-90 parts by mass of silica, 30-90% terminal-modified diene rubber, alkylsilane, fatty acid metal salts, and a sulfur-containing silane coupling agent without mercapto groups, along with specific CTAB adsorption surface area of silica, enhances processability while maintaining excellent wet grip and low rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silane coupling agent containing a mercapto group is compounded to improve silica dispersibility, then wet grip properties are improved, but scorch time becomes too short and processability deteriorates
Solution Approach 1:
The patent introduces a specific silane coupling agent (with silanol groups) as an intermediary substance that mediates between silica and diene rubber. This intermediary forms a silane-modified rubber compound that improves silica dispersibility without the harmful side effects of mercapto-containing agents, thus resolving the contradiction between wet grip improvement and processability maintenance
Solution Approach 2:
The patent changes the chemical parameters of the silane coupling agent by specifying it must contain silanol groups and have a specific molecular structure (where R represents specific groups). This parameter change in the coupling agent's chemical composition allows it to fulfill the dual function of improving dispersibility while maintaining appropriate scorch time and processability
2Reliability
If a large amount of silica is compounded to improve wet grip and reduce rolling resistance, then performance is improved, but dispersibility of silica in diene rubber deteriorates
Solution Approach 1:
The silane coupling agent acts as an intermediary that bridges silica particles and diene rubber matrix. The silane-modified rubber compound formed through this intermediary mechanism enables effective dispersal of large amounts of silica (50-90 parts per 100 parts rubber) while maintaining composition stability and preventing aggregation
Solution Approach 2:
The patent creates a composite material system consisting of diene rubber, silica, and silane coupling agent. This composite approach, where the silane-modified rubber compound forms an integrated structure, enables the combination of large amounts of silica with the rubber matrix while maintaining homogeneous dispersion and stable composition
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 composition allows for the formation of complex tread patterns with improved drainage properties, ensuring excellent wet grip and low rolling resistance, and enhances processability over time.
Implementation Method 1
the silane coupling agent containing a mercapto group has been proposed... the reaction efficiency of the silane coupling agent containing a mercapto group with the diene rubber is high
Implementation Method 2
a sulfur-containing silane coupling agent not containing a mercapto group... at an amount 5 mass % to 12 mass % with respect to the silica amount
Data Source
AI summary
A pneumatic tire includes a tread portion composed of a tread rubber composition containing silica. The pneumatic tire exhibits improved processability over time without negatively affecting the wet grip properties and rolling resistance of the tread rubber composition. The tread portion includes a tread rubber composition including: 50 parts by mass to 90 parts by mass of silica, per 100 parts by mass of diene rubber containing 30 mass % to 90 mass % of a terminal-modified diene rubber; an alkylsilane; a fatty acid metal salt a containing an alkali metal element; and a fatty acid ester; and by further compounding, at an amount of 5 mass % to 12 mass % with respect to the silica amount, a sulfur-containing silane coupling agent not containing a mercapto group.