Dual-Tg Rubber Compound for Wet Grip and Rolling Resistance
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Solution Overview
Problem
Tyre manufacturers face a challenge in balancing the conflicting requirements of maximizing hysteresis for improved grip on wet surfaces while minimizing hysteresis to reduce rolling resistance, which is typically achieved through the use of high-content inorganic fillers that can degrade wet grip properties.
Innovation Solution
A rubber compound with specific properties, including two glass transition temperatures (Tg1 and Tg2) and a unique loss factor profile, utilizing a combination of sulfur vulcanization and two rubber compositions with different elastomers and a reinforcing filler, particularly silica, to enhance rolling resistance while maintaining or improving wet grip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high content of inorganic reinforcing fillers is used to minimize rolling resistance, then rolling resistance is reduced, but wet grip properties are adversely affected
Solution Approach 1:
The patent applies parameter changes by precisely controlling the glass transition temperature difference (ΔTg ≥ 23°C) between the two rubber compositions and optimizing the content ranges of both inorganic fillers (20-80 phr) and organic fillers (20-80 phr). This dual-parameter optimization allows the compound to achieve low rolling resistance while maintaining adequate wet grip properties through the specific hysteresis profile created by the temperature difference.
Solution Approach 2:
The patent uses composite materials by combining two distinct rubber compositions (C1 and C2) with different glass transition temperatures, along with both inorganic fillers and organic fillers. This creates a multi-phase composite system where each component contributes differently to the overall performance, enabling the compound to balance rolling resistance and wet grip properties that cannot be achieved with single-phase compounds.
2Loss of energy
If complex rubber compositions with multiple elastomers are used to improve the rolling resistance/wet grip compromise, then the compromise is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the rubber compound into two distinct compositions (C1 and C2), each with specific glass transition temperature ranges and filler content specifications. This segmentation allows independent optimization of each phase's properties while maintaining overall compound performance, making the complex system more manageable and manufacturable.
3Reliability
If maximum hysteresis potential is used to improve grip on wet ground, then wet grip is improved, but rolling resistance increases
Solution Approach 1:
The patent applies local quality by creating different hysteresis characteristics at different temperature ranges through the two-phase composition. Composition C1 (with higher Tg) provides higher hysteresis at service temperatures for wet grip, while composition C2 (with lower Tg) provides lower hysteresis at lower temperatures to reduce rolling resistance. Each phase contributes its optimal properties locally to the overall 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 rubber compound achieves improved rolling resistance and wet grip performance by optimizing the difference in glass transition temperatures and using specific vulcanization accelerators, resulting in a balance between hysteresis and dynamic friction properties.
Implementation Method 1
based on at least one sulfur vulcanization system
Implementation Method 2
the rubber compound has at least two glass transition temperatures Tg, namely Tg1 and Tg2... the glass transition temperature Tg1 of the composition C1 is above or equal to −50° C.... the rubber compound satisfies the mathematical relationship Tg1-Tg2≥23° C.
Implementation Method 3
the rubber compound has a loss factor profile exhibiting the change in tan δ as a function of the temperature... the loss factor profile being measured over a temperature range extending from −80° C. to 60° C. at a frequency of 10 Hz and a constant stress of 0.7 MPa
Data Source
AI summary
A rubber compound has at least two glass transition temperatures Tg1 and Tg2, based on at least one vulcanization system and at least two rubber compositions C1 and C2, the composition C1 comprising at least one elastomer E1 and having a Tg1, the composition C2 comprising at least one elastomer E2 different from E1, and a reinforcing filler, and the composition C2 having a Tg2, in which: Tg1≥−50° C.; the rubber compound satisfies Tg1-Tg2≥23° C.; the rubber compound has a loss factor profile which is such that all the tan δ peaks present at a temperature above the temperature Tg1 have a width at half height of ≤23° C.; E1 is predominant in the rubber compound; E2 is an isoprene diene elastomer; and the vulcanization system comprises at least one vulcanization accelerator A selected from thiurams, dithiocarbamates, dithiophosphates, xanthates and mixtures thereof.