Dual-Layer Tire Tread Copolymer Composition for Grip and Road Behavior
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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 often compromising on one aspect at the expense of others, particularly due to limitations in rubber composition and reinforcement strategies.
Innovation Solution
A tire tread design featuring a dual-layer structure with a first radially inner layer comprising a copolymer of ethylene and 1,3-butadiene, a reinforcing filler, and a plasticizing system, where the copolymer represents more than 50% of the monomer units, and a second radially outer layer with a lower copolymer content, optimized to achieve a dynamic shear modulus ratio greater than 1.1 and less than 2.5, enhancing road behavior and grip performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
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 two distinct layers: a first layer (C1) with higher copolymer content (50-90 phr) providing grip performance, and a second layer (C2) with lower copolymer content (10-50 phr) providing road behavior stability. This segmentation allows each layer to optimize its properties independently, resolving the contradiction between grip and road behavior.
Solution Approach 2:
Different regions of the tread are assigned different material properties. The first layer uses a softer rubber composition with higher copolymer content to maximize contact surface and grip, while the second layer uses a stiffer composition to maintain structural stability and road behavior. This local differentiation of material quality resolves the contradiction between these two opposing requirements.
2Stability of the object's composition
If reinforcing fillers or resins are incorporated to increase tread rigidity and improve road behavior, then road behavior is improved, but rolling resistance deteriorates
Solution Approach 1:
The invention changes the compositional parameters by using a copolymer with more than 50 mol% ethylene units, which inherently provides higher rigidity and better road behavior without requiring excessive reinforcing fillers. Additionally, the copolymer's saturation level (less than 10% unsaturation) is optimized to reduce hysteresis and rolling resistance while maintaining the desired mechanical properties.
Solution Approach 2:
The tread uses a composite rubber composition combining the copolymer of ethylene and 1,3-diene with specific reinforcing fillers (silica, carbon black) and plasticizing resins. This composite approach allows the base copolymer to provide inherent rigidity for road behavior, while the controlled addition of fillers and plasticizers fine-tunes the properties without excessive reinforcement that would increase rolling resistance.
3Loss of energy
If a copolymer with more than 50 mol% ethylene units is used to reduce rolling resistance, then rolling resistance is improved, but grip performance deteriorates
Solution Approach 1:
The tread is segmented into two layers with different copolymer contents. The first layer (C1) has higher copolymer content (50-90 phr) to provide grip performance, while the second layer (C2) has lower copolymer content (10-50 phr) to maintain structural integrity. This segmentation allows the copolymer's low rolling resistance benefit to be preserved while compensating for reduced grip through the layered structure.
Solution Approach 2:
The invention optimizes the copolymer composition parameters by ensuring more than 50 mol% ethylene units to reduce rolling resistance, while controlling the unsaturation level (less than 10%) to maintain adhesion. The dynamic shear modulus is specifically tuned to be between 1.0-2.5 MPa, balancing the competing requirements of low rolling resistance and adequate grip 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 dual-layer structure improves the trade-off between grip performance, road behavior, and rolling resistance, providing better stiffness and adherence while maintaining efficient energy dissipation, thus enhancing the overall tire performance.
Implementation Method 1
a first radially inner layer C1 and a second radially outer layer C2... the rubber composition of the first layer C1 comprises more than 50 phr of a copolymer of ethylene and a 1,3-diene
Implementation Method 2
The tread of a tire is responsible for a large part of the rolling resistance of that tire... the rubber composition of the first layer C1 comprises more than 50 phr of a copolymer of ethylene and a 1,3-diene
Implementation Method 3
the rubber composition of the first layer C1 comprises more than 50 phr of a copolymer of ethylene and a 1,3-diene, a reinforcing filler
Implementation Method 4
the rubber composition of the first layer C1 comprises more than 50 phr of a copolymer of ethylene and a 1,3-diene... and a plasticizing system
Implementation Method 5
enhancing road behavior and grip performance... optimized to achieve a dynamic shear modulus ratio greater than 1.1 and less than 2.5
Data Source
Figure 1
AI summary
Disclosed is a tyre having a rubbery tread comprising a first radially inner layer C1 and a second radially outer layer C2, the first and second layers being intended to be in contact with driving ground when in a new condition or in a used condition, wherein the rubbery composition of the first layer C1 comprises more than 50 phr of a copolymer of ethylene and a 1,3-diene, 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 the copolymer.