Functionalized Polybutadiene Rubber Composition for Tire Tread
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Solution Overview
Problem
Tire tread rubber compositions face challenges in achieving optimal wet traction and cold weather performance, as existing solutions struggle to balance high glass transition temperature (Tg) for wet traction with low stiffness at lower temperatures for winter driving.
Innovation Solution
A rubber composition combining functionalized high Tg and low Tg polybutadiene elastomers with precipitated silica reinforcement, along with traction resins, to optimize tan delta at 0°C for wet traction and minimize stiffness at -20°C for cold weather performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relatively high Tg elastomer is used in the tread rubber composition, then wet traction performance is improved, but stiffness at lower temperatures increases which deteriorates cold weather performance
Solution Approach 1:
The elastomer component is segmented into multiple types with different Tg values. The tread rubber composition contains a combination of high Tg elastomer (20-40 phr) for wet traction and low Tg elastomer (60-80 phr) for cold weather flexibility, allowing each component to contribute its specific functional advantage without compromise
Solution Approach 2:
The invention creates a composite elastomer system by combining multiple elastomer types with complementary properties. The composite composition leverages the high Tg elastomer's wet surface adhesion capability while integrating the low Tg elastomer's low-temperature flexibility, achieving a synergistic effect that resolves the temperature-dependent performance contradiction
2Temperature
If a relatively low Tg elastomer is used to reduce stiffness at lower temperatures, then cold weather performance is improved, but wet traction performance deteriorates
Solution Approach 1:
The elastomer component is segmented into multiple types with different Tg values. The tread rubber composition contains a combination of high Tg elastomer (20-40 phr) for wet traction and low Tg elastomer (60-80 phr) for cold weather flexibility, allowing each component to contribute its specific functional advantage without compromise
Solution Approach 2:
The invention creates a composite elastomer system by combining multiple elastomer types with complementary properties. The composite composition leverages the high Tg elastomer's wet surface adhesion capability while integrating the low Tg elastomer's low-temperature flexibility, achieving a synergistic effect that resolves the temperature-dependent performance contradiction
3Reliability
If high vinyl content polybutadiene rubber is used to improve wet traction, then tan delta at 0°C is maximized, but processing difficulty increases
Solution Approach 1:
The invention adjusts the vinyl content parameter of the polybutadiene rubber to an optimized range (40-80% vinyl content) rather than using extremely high vinyl content. This parameter optimization maintains the tan delta at 0°C above 0.100 for wet traction while reducing processing difficulty and improving manufacturing ease
Solution Approach 2:
The invention applies different elastomer types with specific localized properties to different functional requirements. The high vinyl content elastomer (40-80%) is used specifically for wet traction enhancement, while the overall composition is balanced to maintain processability, creating local optimization without global compromise
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 solution enhances predictive wet traction and cold weather performance by maintaining similar wet traction while improving rolling resistance and treadwear, with a significant reduction in stiffness at lower temperatures, as demonstrated in laboratory tests.
Implementation Method 1
functionalized relatively high Tg relatively high vinyl content polybutadiene rubber and functionalized relatively low Tg relatively low vinyl content polybutadiene rubber which contain functional groups reactive with hydroxyl groups contained on said silica reinforcing filler
Implementation Method 2
the improved predictive wet traction performance for the tread rubber composition is based on a relative maximization of its tan delta physical property at 0°C
Implementation Method 3
the predictive cold weather performance for the tread rubber composition is based on its stiffness physical property at -20°C as a measure of indication of such predictive cold weather performance (e.g. stiffness property such as storage modulus E')
Data Source
AI summary
A rubber composition for use in a tire tread is disclosed. The rubber composition comprises, based on parts by weight per 100 parts by weight elastomer (phr): (A) 100 phr of conjugated diene-based elastomers comprising: (1) 20 to 80 phr of a first functionalized vinyl polybutadiene rubber having a Tg in a range of from -40°C to -10°C and an isomeric vinyl 1,2-content in a range of from 65 to 85 percent, wherein the first functionalized vinyl polybutadiene rubber contains functional groups reactive with hydroxyl groups on a silica reinforcement of the rubber composition; (2) 80 to 20 phr of a second functionalized vinyl polybutadiene rubber having a Tg in a range of from -108°C to -90°C and an isomeric vinyl 1,2-content in a range of from 0 to 15 percent, wherein the second functionalized low vinyl polybutadiene rubber contains functional groups reactive with hydroxyl groups on a silica reinforcement of the rubber composition; wherein the weight ratio of the second functionalized vinyl polybutadiene rubber to the first functionalized vinyl polybutadiene rubber is at least 1/1 or at least 1.5/1; and (B) 60 to 200 phr of a rubber reinforcing filler comprising a combination of silica, preferably precipitated silica or amorphous synthetic precipitated silica, and carbon black in a weight ratio of silica to carbon black of at least 9/1, together with a silica coupling agent having a moiety reactive with hydroxyl groups on the silica and another different moiety interactive with the diene-based elastomers.