Low Tg Rubber Composition for Winter Tire Tread
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Solution Overview
Problem
Tires face challenges in balancing wet traction and low-temperature performance while maintaining wear characteristics, as traditional rubber compositions either sacrifice wet skid resistance or rolling resistance for improved treadwear.
Innovation Solution
A rubber composition using low Tg rubbers like cis 1,4-polybutadiene, styrene/butadiene, and hydrocarbon resin, combined with silica-rich filler reinforcement, to enhance wet traction and reduce cured stiffness at low temperatures, while maintaining good wear characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high rebound rubber is used to reduce rolling resistance and improve treadwear, then wear characteristics improve, but wet skid resistance deteriorates
Solution Approach 1:
The patent utilizes rubber compounds with specifically controlled glass transition temperatures (Tg), employing low Tg rubbers (such as polybutadiene with Tg around -100°C to -90°C) to achieve the desired balance. By changing the thermal parameter (Tg) of the rubber compound, the invention enables simultaneous improvement in wet skid resistance and treadwear characteristics without the traditional trade-off.
2Object-generated harmful factors
If rubber with large energy loss is used to increase wet skid resistance, then wet traction improves, but rolling resistance increases
Solution Approach 1:
The patent employs rubber compounds with specifically controlled glass transition temperatures and viscoelastic properties. By selecting rubbers with appropriate Tg values and controlling the compounding ingredients, the invention achieves optimal energy dissipation characteristics that provide wet skid resistance while minimizing rolling resistance through precise parameter optimization.
3Object-generated harmful factors
If traditional rubber composition is used to maintain wet traction, then wet skid resistance is preserved, but low temperature performance deteriorates
Solution Approach 1:
The patent utilizes rubber compounds with low glass transition temperatures (specifically polybutadiene with Tg around -100°C to -90°C and styrene-butadiene rubber with Tg around -60°C to -50°C). This parameter change in the rubber compound's Tg ensures the tread remains flexible and maintains wet traction at low temperatures where traditional rubber compositions would become too stiff.
Solution Approach 2:
The patent employs composite rubber compositions combining multiple rubber types (polybutadiene, styrene-butadiene rubber, and optionally natural rubber) with specific Tg ranges. This composite approach allows the tread to exhibit both low-temperature flexibility and adequate wet traction by leveraging the complementary properties of different rubber materials.
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 effectively improves winter performance and wet traction while reducing rolling resistance and treadwear, achieving a balance previously difficult to attain in tire tread rubber compositions.
Implementation Method 1
low Tg rubbers, such as cis 1,4-polybutadiene rubber, styrene/butadiene rubber and optionally cis 1,4 polyisoprene rubber having relatively low Tg values below -55°C to improve, or beneficially lower, the stiffness of the cured rubber composition at -20°C
Implementation Method 2
it is desired to use a silica-rich filler reinforcement for the rubber composition containing the low Tg elastomer(s) to promote wet traction combined with promoting a reduction in its cured stiffness at low temperatures
Implementation Method 3
pseudo-solid resin materials that possess a glass-to-viscous transition state at ambient temperature, can also be envisioned to be used as traction promoting resins in tread rubber formulations
Data Source
AI summary
A rubber composition for use in a tread of a pneumatic tire is disclosed. The rubber composition comprises, based on 100 parts by weight of elastomer (phr), (A) from 40 to 90 phr of a solution polymerized styrene-butadiene rubber having a glass transition temperature (Tg) in a range of from -65 °C to -55 °C; (B) from 60 to 10 phr of polybutadiene having a cis 1,4 content greater than 95 percent and a Tg in a range of from -80 °C to -110 °C; and (C) from 45 to 65 phr of a hydrocarbon resin having a Tg in a range of from -40 °C to 20°C; (D) less than 10 phr of oil; and (E) from 120 to 160 phr of silica; wherein the total amount of resin and oil is less than 70 phr, and wherein the weight ratio of silica to resin is greater than 2.