Tire Tread Stiffness Gradient via Ethylene-Butadiene Copolymer
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Solution Overview
Problem
Current tire tread designs face challenges in balancing grip performance, road behavior, and rolling resistance, with existing solutions either compromising on grip or deteriorating road behavior when attempting to improve rolling resistance.
Innovation Solution
A tire tread design featuring a rubber composition with a copolymer of ethylene and 1,3-butadiene, where the lateral parts contain more than 50 phr of the copolymer, a reinforcing filler, and a plasticizing system, while the central part has a lower copolymer content, creating a stiffness gradient that enhances grip and road behavior while reducing rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a very soft rubber composition is used to increase contact surface and improve grip performance, then grip performance is improved, but road behavior deteriorates
Solution Approach 1:
The tread is divided into different zones with different rubber compositions: lateral parts use a soft composition (greater than 50 phr copolymer) for grip, while the central part uses a harder composition (less than 50 phr copolymer) for road behavior. This spatial differentiation of material properties resolves the contradiction between grip and road behavior.
Solution Approach 2:
The patent uses composite rubber compositions in each tread zone, combining the copolymer of ethylene and 1,3-butadiene with reinforcing fillers and plasticizing systems. The lateral parts have a composite formulation optimized for softness and grip, while the central part has a composite formulation optimized for rigidity and road behavior, allowing both requirements to be satisfied simultaneously.
2Stability of the object's composition
If reinforcing fillers or higher reinforcing load rate is used to increase tread rigidity for road behavior, then road behavior is improved, but rolling resistance deteriorates
Solution Approach 1:
The central part of the tread uses a specific composition with less than 50 phr copolymer and optimized filler content to provide sufficient rigidity for road behavior, while the lateral parts use greater than 50 phr copolymer with plasticizing systems to reduce hysteresis and rolling resistance. This localized optimization allows the tread to be rigid where needed and compliant where it contacts the road surface.
Solution Approach 2:
The patent changes the copolymer content parameter differently across tread zones: less than 50 phr in the central part for rigidity, and greater than 50 phr in the lateral parts for reduced hysteresis. It also adjusts the plasticizing system content to optimize the balance between road behavior and rolling resistance, specifically reducing energy loss during tire rolling.
3Loss of energy
If a copolymer with more than 50 mol% ethylene units is used to reduce rolling resistance, then rolling resistance is reduced, but grip performance deteriorates
Solution Approach 1:
The copolymer of ethylene and 1,3-butadiene with more than 50 mol% ethylene units is used specifically in the lateral parts of the tread where grip is less critical, allowing rolling resistance to be reduced in these zones. The central part uses a different composition optimized for grip, creating a spatial distribution that resolves the contradiction between rolling resistance and grip performance.
Solution Approach 2:
The patent creates composite rubber compositions that combine the low-rolling-resistance copolymer (greater than 50 mol% ethylene) with reinforcing fillers and plasticizing systems. In the lateral parts, this composite formulation achieves both reduced rolling resistance and adequate grip through the synergistic effect of the copolymer's low hysteresis and the plasticizing system's ability to maintain surface compliance.
Data Source
Figure 1~3
AI summary
A tyre having a tread axially separated into at least three portions, a central portion and two lateral portions, in which the rubber composition of the lateral portions comprises more than 50 phr of an ethylene/1,3-diene copolymer, a reinforcing filler and a plasticising system, the 1,3-diene being 1,3-butadiene or isoprene and the ethylene units in the copolymer representing more than 50 mol% of all the monomer units of said copolymer.