Cap Tread Rubber Composition for Low-Resistance All-Season Tires
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Solution Overview
Problem
All-season tires face challenges in achieving compatible performance in off-road durability, wet traction, and snow performance while reducing rolling resistance, as improvements in one area often compromise others due to conflicting rubber composition requirements.
Innovation Solution
A pneumatic tire design featuring a cap tread layer with a specific rubber composition of 50-100 parts silica, 5-25 parts carbon black, and a blend of natural rubber, styrene-butadiene rubber, and optional butadiene rubber, along with a unique tread pattern, which balances rolling resistance, off-road durability, and snow performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tan δ at 0° C. is increased to improve wet performance, then wet performance is improved, but tan δ at 60° C. increases and rolling resistance cannot be reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the glass transition temperature Tg within -40°C to -10°C and the tan δ at 0°C within 0.08 to 0.15. This specific parameter range optimization allows the rubber composition to achieve excellent wet performance while maintaining low rolling resistance, resolving the contradiction between these two performance requirements.
Solution Approach 2:
The patent uses composite materials by combining multiple rubber components (natural rubber, styrene-butadiene rubber, butadiene rubber) with specific fillers (silica, carbon black) and additives in optimized proportions. This composite approach enables simultaneous achievement of low Tg for wet performance and controlled tan δ for low rolling resistance.
2Reliability
If the blended amount of butadiene rubber is increased to improve snow performance, then snow performance is improved, but the dispersibility of silica degrades and rolling resistance reduction becomes difficult
Solution Approach 1:
The patent controls the butadiene rubber content within 5 mass% to 30 mass% and optimizes the silica to carbon black ratio between 2:1 and 10:1. This parameter optimization ensures good silica dispersibility while maintaining excellent snow performance and low rolling resistance.
Solution Approach 2:
The patent uses a composite material system combining butadiene rubber (5-30 mass%), natural rubber (40-60 mass%), styrene-butadiene rubber (5-30 mass%), silica (50-150 parts per 100 parts rubber), and carbon black (10-50 parts per 100 parts rubber). This optimized composite formulation achieves snow performance while maintaining low rolling resistance through improved silica dispersibility.
3Reliability
If the blended amount of butadiene rubber is increased to improve snow performance, then snow performance is improved, but elongation and strength of the rubber composition decrease and off-road durability performance degrades
Solution Approach 1:
The patent optimizes the butadiene rubber content (5-30 mass%) and controls the tensile product TB×EB to be 12000 or more. This parameter control ensures that snow performance is improved while maintaining sufficient elongation and strength for off-road durability.
Solution Approach 2:
The patent employs a balanced composite material formulation where butadiene rubber (5-30 mass%) is combined with natural rubber (40-60 mass%) and styrene-butadiene rubber (5-30 mass%), along with optimized filler amounts. This composite approach achieves snow performance while maintaining the mechanical strength and elongation required for off-road durability.
Data Source
AI summary
Provided is a pneumatic tire. The cap tread layer is made of a rubber composition in which 50 parts by mass to 100 parts by mass of silica and 5 parts by mass to 25 parts by mass of carbon black are blended per 100 parts by mass of diene rubber containing 50 mass % or more of natural rubber and 20 mass % or more and 40 mass % or less of styrene-butadiene rubber. As the styrene-butadiene rubber, terminal-modified styrene-butadiene rubber having a vinyl content of 35 mass % to 70 mass % is used. As the carbon black, carbon black having a nitrogen adsorption specific surface area N2SA of less than 130 m2/g is used. The rubber composition constituting the cap tread layer is set to have a tensile product TB×EB of 12000 or more and a hardness of 60 or more and 70 or less.