Polybutadiene Tread Rubber Composition with Terpene Resin
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Solution Overview
Problem
Existing rubber compositions for treads face challenges in achieving a balanced improvement in fuel economy, abrasion resistance, and wet grip performance while maintaining good processability, as these properties often have a trade-off relationship.
Innovation Solution
A rubber composition containing a polybutadiene with specific properties, such as a ratio of toluene solution viscosity to Mooney viscosity between 0.9 and 2.3, a stress relaxation time of 10.0 to 40.0 seconds, and a molecular weight distribution of 2.50 to 4.00, combined with a terpene resin having a glass transition temperature of 40°C to 90°C, along with silica and additional rubber components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terminally modified rubber, high molecular weight polymer, or high glass transition temperature polymer is used to improve fuel economy, abrasion resistance, and wet grip performance, then these performance properties are improved, but the hardness of the rubber composition increases leading to deterioration of processability
Solution Approach 1:
The invention changes the molecular weight distribution parameters of the polybutadiene, specifically controlling Mw/Mn to be 2.0-4.0 and using a polybutadiene with Mooney viscosity of 30-80. This parameter optimization allows the rubber to achieve good processability while maintaining improved fuel economy, abrasion resistance, and wet grip performance, resolving the contradiction between performance improvement and processability deterioration.
Solution Approach 2:
The invention uses a composite rubber composition containing polybutadiene combined with other rubber components (styrene-butadiene rubber, polyisoprene rubber, or epoxidized natural rubber) in specific ratios. This composite approach allows the polybutadiene to provide the performance improvements while the other rubber components help maintain processability, thus resolving the contradiction between enhanced performance and manufacturing ease.
2Reliability
If high molecular weight polymer or high glass transition temperature polymer is used to improve abrasion resistance and wet grip performance, then these properties are improved, but the hardness of the rubber composition increases leading to deterioration of processability
Solution Approach 1:
The invention optimizes the molecular weight distribution of polybutadiene by controlling Mw/Mn to be 2.0-4.0 and Mooney viscosity to be 30-80. This parameter control enables the rubber to achieve high abrasion resistance and wet grip performance while maintaining low enough hardness for good processability, resolving the contradiction between performance improvement and manufacturing ease.
3Reliability
If terminally modified rubber is used to improve fuel economy, then this property is improved, but the hardness of the rubber composition increases leading to deterioration of processability
Solution Approach 1:
The invention changes the molecular weight distribution parameters of polybutadiene, specifically controlling Mw/Mn to be 2.0-4.0 and using polybutadiene with Mooney viscosity of 30-80. These parameter changes allow the rubber to achieve improved fuel economy through better silica dispersion and reduced rolling resistance while maintaining good processability, resolving the contradiction between fuel economy improvement and processability deterioration.
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
This composition achieves a synergistic improvement in fuel economy, abrasion resistance, and wet grip performance while ensuring good processability, addressing the trade-off challenges faced by previous compositions.
Implementation Method 1
a stress relaxation time (T80) is 10.0 to 40.0 seconds, which is a time required for torque to decay by 80%
Implementation Method 2
a ratio (Tcp/ML 1+4, 100°C) of 5% by mass toluene solution viscosity (Tcp) to Mooney viscosity (ML 1+4, 100°C) is 0.9 to 2.3
Data Source
AI summary
Provided are a rubber composition for treads which achieves a balanced improvement in fuel economy, abrasion resistance, and wet grip performance while offering good processability, and a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition for treads containing: a polybutadiene; and a terpene resin having a glass transition temperature (Tg) of 40°C to 90°C, the polybutadiene satisfying the following conditions (A), (B) and (C) : (A) a ratio (Tcp/ML1+4, 100°C) of 5% by mass toluene solution viscosity (Tcp) to Mooney viscosity (ML1+4, 100°C) is 0.9 to 2.3; (B) a stress relaxation time (T80) is 10.0 to 40.0 seconds, which is a time required for torque to decay by 80%, where 100% represents torque at the end of a ML1+4, 100°C measurement; and (C) a molecular weight distribution (Mw/Mn) is 2.50 to 4.00.