Tire Tread Rubber Composition for Wet Grip Across Temperature Ranges
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Solution Overview
Problem
Existing rubber compositions for tire treads fail to provide optimal wet grip performance at both low (5° C.) and high (25° C.) temperatures.
Innovation Solution
A rubber composition comprising specific ratios of modified styrene butadiene rubbers with varying glass transition points, silica, thermoplastic resins, and a silane coupling agent, optimized to achieve a balanced storage modulus and grip performance across temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single type of modified styrene butadiene rubber is used, then the formulation is simple, but wet grip performance cannot be optimized at both low and high temperatures
Solution Approach 1:
The rubber composition is segmented into two distinct modified styrene butadiene rubber components with different glass transition points. The first modified SBR has a glass transition point of -30°C or higher, while the second modified SBR has a glass transition point of -50°C or lower. This segmentation allows each component to contribute to wet grip performance in different temperature ranges, with the higher Tg component providing grip at warmer temperatures and the lower Tg component providing grip at colder temperatures.
Solution Approach 2:
The invention changes the physical parameter of glass transition point by selecting two modified SBRs with significantly different Tg values. This parameter change enables the rubber composition to maintain appropriate flexibility and grip characteristics across a wide temperature range, as each rubber component remains in its optimal performance range at different temperatures.
2Reliability
If high-softening-point resin is used to improve grip performance, then grip performance improves, but low-temperature wet grip performance remains insufficient
Solution Approach 1:
The invention changes the glass transition point parameter of the rubber components to address low-temperature performance. By incorporating a modified SBR with a glass transition point of -50°C or lower, the composition maintains flexibility and grip capability at low temperatures where high-softening-point resins alone would be too rigid.
Solution Approach 2:
The invention creates a composite rubber system combining two modified SBRs with different Tg values, along with silica, thermoplastic resin, and oil. This composite material approach allows the synergistic interaction between components to achieve both high-temperature and low-temperature wet grip performance that cannot be achieved by any single component alone.
3Ease of manufacture
If modified styrene butadiene rubber with glass transition point of -30 to 0°C is used, then processing is easier, but low-temperature wet grip performance deteriorates
Solution Approach 1:
The rubber system is segmented into two components where the first modified SBR (Tg ≥ -30°C) provides ease of processing and manufacturing, while the second modified SBR (Tg ≤ -50°C) specifically addresses low-temperature wet grip performance. This segmentation allows each component to fulfill its specialized function without compromise.
Solution Approach 2:
The invention changes the glass transition point parameter by introducing a second modified SBR with a much lower Tg value. This parameter change enables the composition to achieve low-temperature flexibility and grip performance that the single higher-Tg rubber component cannot provide alone.
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 delivers enhanced wet grip performance at both low and high temperatures, demonstrated by improved braking distances on wet roads.
Implementation Method 1
a modified styrene butadiene rubber having a glass transition point of −30° C. or more and (b) 25 to 65 parts by mass of a modified styrene butadiene rubber having a glass transition point of −50° C. or less
Implementation Method 2
15 to 50 parts by mass of a thermoplastic resin having a softening point of 40° C. or more
Data Source
AI summary
A rubber composition for a tire tread is disclosed, which provides a tire excellent in wet grip performance at low temperatures and wet grip performance at high temperatures. The rubber composition for a tire tread includes, per 100 parts by mass of diene-based rubbers including (a) 25 to 65 parts by mass of a modified styrene butadiene rubber having a glass transition point of −30° C. or more and (b) 25 to 65 parts by mass of a modified styrene butadiene rubber having a glass transition point of −50° C. or less: 80 to 140 parts by mass of silica; 15 to 50 parts by mass of a thermoplastic resin having a softening point of 40° C. or more; and 5 to 15 parts by mass of an oil.