Pneumatic Tire Tread Rubber Composition for Winter Performance
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Solution Overview
Problem
Tires face challenges in balancing wet skid resistance, low rolling resistance, and wear characteristics, particularly in low-temperature winter conditions, as existing rubber compositions struggle to maintain traction while reducing cured stiffness and improving treadwear.
Innovation Solution
A pneumatic tire design featuring a tread with a base layer and an outer cap layer, comprising solution polymerized styrene-butadiene rubber functionalized with alkoxysilane groups, polybutadiene with high cis 1,4-content, silica, and a combination of resin and oil, with specific weight ratios to optimize viscoelastic properties for improved traction and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rubbers with high energy loss are used to increase wet skid resistance, then wet traction is improved, but rolling resistance increases
Solution Approach 1:
The patent utilizes the viscoelastic properties of rubber compounds by carefully selecting and controlling the glass transition temperatures (Tg) of different rubber components. The SBR with Tg of -65°C to -55°C provides wet traction through appropriate energy loss, while the polybutadiene with Tg of -80°C to -110°C maintains low rolling resistance by remaining in a more elastic state, thus optimizing the balance between these two opposing requirements through parameter control.
Solution Approach 2:
The patent employs a composite rubber composition combining solution polymerized SBR functionalized with alkoxysilane groups and polybutadiene with high cis 1,4-content. This composite material integrates the advantages of both rubber types: the SBR contributes to wet skid resistance through controlled energy dissipation, while the polybutadiene reduces rolling resistance through its elastic recovery, achieving a balance that neither component could accomplish alone.
2Loss of energy
If rubbers with high rebound are used to reduce rolling resistance and improve treadwear, then wear characteristics are improved, but wet skid resistance decreases
Solution Approach 1:
The patent controls the glass transition temperature parameter of each rubber component to achieve the desired balance. The polybutadiene with Tg of -80°C to -110°C provides high rebound and low rolling resistance, while the SBR with Tg of -65°C to -55°C ensures adequate wet skid resistance through appropriate energy loss, thus resolving the contradiction through precise parameter selection.
3Temperature
If the cured stiffness of tread rubber is reduced for low temperature winter performance, then snow traction is improved, but wet traction may be compromised
Solution Approach 1:
The patent utilizes the glass transition temperature as a key parameter to address temperature-dependent performance. The polybutadiene with Tg of -80°C to -110°C remains flexible and provides low cured stiffness at low temperatures for winter performance, while the SBR with Tg of -65°C to -55°C maintains adequate wet traction through controlled energy dissipation, thus resolving the temperature-performance contradiction.
Solution Approach 2:
The patent creates different zones within the tread with varying rubber composition ratios. The central zone and lateral zones have different weight ratios of resin to oil, allowing each zone to be optimized for its specific function: the central zone for straight-ahead wet traction and the lateral zones for cornering and snow traction, thus maintaining overall wet traction while improving low-temperature performance.
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 tire composition achieves enhanced wet traction, reduced rolling resistance, and improved treadwear characteristics, effectively addressing the balance between viscoelastic properties for winter performance.
Implementation Method 1
These properties depend, to a great extent, on the dynamic viscoelastic properties of the rubbers utilized in making the tire
Implementation Method 2
In order to reduce the rolling resistance and to improve the treadwear characteristics of tires, rubbers having a high rebound have traditionally been utilized
Implementation Method 3
the challenge is to reduce the cured stiffness of such tread rubber compositions, as indicated by having a lower storage modulus G' at -20°C
Data Source
Figure 1~2
AI summary
A pneumatic tire having a tread (10, 110) comprising a tread base layer (14, 114) and a tread cap layer (12, 120) disposed radially outward of the base layer (14, 114) is disclosed. The tread cap layer (12, 120) comprising an axially central zone (20, 120) and a first lateral zone (18a, 118a) and a second lateral zone (18b, 118b). The central zone (20, 120) comprises a central zone rubber composition, the first lateral zone (18a, 118a) comprises a first lateral zone rubber composition and the second lateral zone (18b, 118b) comprises a second lateral zone rubber composition. The central zone rubber composition, the first lateral zone rubber composition and the second lateral zone rubber composition each comprise, based on 100 parts by weight of elastomer (phr): from 50 to 90 phr of a solution polymerized styrenebutadiene rubber having a glass transition temperature (Tg) in a range of from -65 °C to -55 °C and functionalized with an alkoxysilane group and at least one functional group selected from the group consisting of primary amines and thiols; from 50 to 10 phr of a polybutadiene having a cis 1,4-content greater than 90 percent and a Tg in a range of from -80 to -110 °C; from 100 to 180 phr of silica; and from 30 to 80 phr of a combination of a resin having a Tg of at least 30 °C and an oil, wherein the weight ratio of the amount of silica to the total amount of resin and oil is less than 3. The weight ratio of resin to oil in at least one of the central zone rubber composition, the first lateral zone rubber composition and the second lateral zone rubber composition is greater than 2, and the weight ratio of resin to oil in at least one of the central zone rubber composition, the first lateral zone rubber composition and the second lateral zone rubber composition is less than 2.