Tire Tread Rubber Composition Ice Grip and Wear Resistance
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Solution Overview
Problem
Rubber compositions for tire treads often suffer from inadequate performance on ice, wet grip, low heat build-up, and wear resistance, as seen in existing studless tire technologies.
Innovation Solution
A rubber composition comprising diene rubber, silica, and a cured product, with specific formulations of natural rubber, modified butadiene rubber having a polyorganosiloxane group, and an aromatic modified terpene resin, along with thermally expanding microcapsules, to enhance traction, grip, and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a crosslinkable oligomer or polymer that is not compatible with the diene rubber is used to form a cured product, then wear resistance is improved, but the rubber composition becomes heterogeneous and processing difficulty increases
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the diene rubber and the incompatible crosslinkable oligomer or polymer. The silane coupling agent has affinity for both rubber and inorganic fillers/cured products, acting as a bridge that reduces interfacial tension and improves compatibility. This mediator enables better dispersion of the cured product particles in the rubber matrix while maintaining the wear resistance benefits of the incompatible crosslinkable system.
Solution Approach 2:
The patent controls the particle size of the cured product within a specific range (5-250 μm, preferably 10-200 μm) and adjusts the crosslinking degree of the oligomer or polymer. By optimizing these parameters, the patent achieves a balance between maintaining wear resistance (which requires sufficient crosslinking) and improving processability (which benefits from smaller, more uniformly dispersed particles).
2Reliability
If silica content is increased to improve wet grip performance, then traction on wet surfaces is enhanced, but heat build-up in the tire increases
Solution Approach 1:
The patent creates localized regions with different silica concentrations and crosslinking densities within the tire tread. The silane coupling agent enables formation of silica-rubber interfacial zones that provide enhanced wet grip through improved adhesion, while the bulk rubber matrix maintains lower silica content to reduce overall heat build-up. This spatial differentiation of composition allows simultaneous optimization of both wet grip and heat dissipation.
Solution Approach 2:
The patent employs a composite system combining diene rubber, silica, and the incompatible crosslinkable oligomer or polymer with silane coupling agent. This multi-component composite structure allows the silica to provide wet grip enhancement at the surface interface while the rubber matrix and crosslinked network manage heat dissipation in the bulk material, achieving performance optimization through compositional synergy.
3Reliability
If a soft cured product with low hardness is used to improve performance on ice, then friction on ice is enhanced, but the structural integrity of the tire tread may be compromised
Solution Approach 1:
The patent creates a differentiated structure where soft, low-hardness cured product particles (JIS A hardness 3-45) are dispersed throughout the rubber matrix. These soft particles contact the ice surface to provide enhanced friction and grip, while the continuous rubber matrix and interparticle bonding maintain the overall structural integrity of the tread. The silane coupling agent strengthens the interfaces between soft cured product particles and the rubber matrix, preventing structural failure.
Solution Approach 2:
The patent uses a composite structure combining soft cured product particles with the diene rubber matrix. The cured product particles provide ice friction enhancement at the contact surface, while the rubber matrix provides structural support. The silane coupling agent creates strong interfacial bonding between these components, ensuring that the soft particles remain embedded in the matrix and do not detach under stress, thus maintaining both ice performance and structural integrity.
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 achieves excellent performance on ice, improved wet grip, reduced heat build-up, and enhanced wear resistance, making it suitable for studless tires.
Implementation Method 1
a modified butadiene rubber having a polyorganosiloxane group at a terminal
Implementation Method 2
a cured product obtained by curing a crosslinkable oligomer or polymer that is not compatible with the diene rubber
Implementation Method 3
thermally expanding microcapsules
Implementation Method 4
thermally expanding microcapsules
Data Source
AI summary
A rubber composition for a tire tread contains a diene rubber, silica, and a cured product; a content of the silica being from 20 to 100 parts by mass per 100 parts by mass of the diene rubber, a content of the cured product being from 0.3 to 30 parts by mass per 100 parts by mass of the diene rubber; the diene rubber containing a natural rubber and a modified butadiene rubber having a polyorganosiloxane group at a terminal, a content of the natural rubber in the diene rubber being from 30 to 90 mass %, a content of the modified butadiene rubber in the diene rubber being from 10 to 70 mass %; the cured product being a cured product obtained by curing a crosslinkable oligomer or polymer that is incompatible with the diene rubber; and a JIS A hardness of the cured product being from 3 to 45.