Snow Tire Tread Rubber Composition for Low-Temperature Traction
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Solution Overview
Problem
Existing tires struggle with propulsion performance on snow-covered roads, particularly when the tread portion fails to contact the road surface due to increased snowfall, leading to spinning and difficulty in escaping snowy areas.
Innovation Solution
A tire design with a tread portion featuring a cap rubber layer composed of a specific rubber composition containing 40-80 parts by mass of styrene-butadiene rubber (SBR) with a styrene content of 25% or less, 60 parts by mass or more of filler, and a glass transition temperature (Tg) of -40°C or lower, combined with silica and carbon black, and groove depth satisfying the formula Tg ≤ -0.5 × G - 35, to enhance traction on snow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tread portion is designed with conventional rubber composition, then the tire structure is simple and easy to manufacture, but the propulsion performance on snow-covered roads deteriorates when snow accumulates and the tread fails to contact the road surface
Solution Approach 1:
The patent applies parameter changes by precisely controlling the glass transition temperature (Tg ≤ -40°C) and loss tangent (10°C tan δ < 0.28) of the rubber composition, along with specific SBR content (40-80 parts by mass) and filler content (60 parts by mass or more). These parameter optimizations enable the rubber to maintain appropriate hardness and elasticity at low temperatures, improving propulsion performance on snow-covered roads while managing composition complexity through defined ranges.
Solution Approach 2:
The patent employs composite materials by combining silica and carbon black as fillers in the rubber composition, with carbon black limited to 50 parts by mass or less. This composite filler system provides both reinforcement and low-temperature flexibility, enhancing the rubber's ability to maintain traction on snow while managing the overall composition complexity through specified proportions.
2Temperature
If the rubber composition uses high SBR content with low styrene content, then the low-temperature flexibility improves, but the heat generation during deformation increases
Solution Approach 1:
The patent resolves this contradiction through parameter changes by simultaneously optimizing the glass transition temperature (Tg ≤ -40°C) and loss tangent (10°C tan δ < 0.28). The specific SBR content range (40-80 parts by mass) with low styrene content (≤25%) provides the necessary low-temperature flexibility, while the controlled loss tangent ensures minimal heat generation during deformation by reducing energy dissipation in the rubber matrix.
Solution Approach 2:
The patent applies local quality by creating a rubber composition with specific local characteristics: low styrene content SBR regions provide flexibility and low Tg, while the silica-carbon black filler network provides reinforcement and controls heat generation. This spatial and compositional differentiation allows the material to simultaneously achieve low-temperature flexibility and reduced energy loss.
3Reliability
If the groove depth is increased to improve snow expulsion, then the propulsion performance on snow improves, but the relationship between groove depth and rubber composition becomes more complex
Solution Approach 1:
The patent applies parameter changes by establishing a quantitative relationship between groove depth and rubber composition parameters (Tg and loss tangent). The formula Tg ≤ -0.5 × G - 35 provides a systematic way to optimize groove depth based on the rubber's glass transition temperature, ensuring effective snow expulsion while maintaining manageable design complexity through this clear parameter linkage.
4Reliability
If the filler content is increased to enhance traction, then the propulsion performance improves, but the manufacturing cost and processing difficulty increase
Solution Approach 1:
The patent applies parameter changes by optimizing the filler content to 60 parts by mass or more while specifically limiting carbon black to 50 parts by mass or less in favor of silica. This composition optimization enhances traction through increased filler-reinforced friction, while managing processing difficulty by controlling the total filler amount and using silica which generally offers better processability compared to high carbon black formulations.
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 design improves propulsion performance on snow-covered roads by effectively compressing and expelling snow from grooves, maintaining traction and reducing heat generation, thereby enhancing driving efficiency in snowy conditions.
Implementation Method 1
the rubber composition having a loss tangent 10°Ctan δ measured under the conditions of temperature of 10°C, frequency of 10 Hz, initial strain of 5%, and dynamic strain rate of 1 % and in deformation mode; tensile of less than 0.28, and a glass transition temperature Tg (°C) of -40°C or lower
Implementation Method 2
the cap rubber layer forming the tread portion contains 40 parts by mass or more and 80 parts by mass or less of styrene-butadiene rubber (SBR) having a styrene content of 25% by mass or less
Data Source
AI summary
An object of the present invention is to improve propulsion performance on a snow-covered road surface, and provided is a tire with a tread portion having a groove, wherein the cap rubber layer forming the tread portion contains 40 parts by mass or more and 80 parts by mass or less of styrene-butadiene rubber (SBR) having a styrene content of 25% by mass or less in 100 parts by mass of its rubber component, and 60 parts by mass or more of a filler with respect to 100 parts by mass of the rubber component, and is formed from a rubber composition having a loss tangent 10°Ctan δ measured under the conditions of temperature of 10°C, frequency of 10 Hz, initial strain of 5%, and dynamic strain rate of 1 % and in deformation mode; tensile of less than 0.28, and a glass transition temperature Tg (°C) of -40°C or lower; and the glass transition temperature Tg (°C) and the depth G(mm) of the groove satisfy Tg ≤ -0.5 × G - 35.