Tire Undertread Rubber Composition for Low Rolling Resistance
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Solution Overview
Problem
Existing rubber compositions for tire undertreads struggle to balance low rolling resistance with excellent steering stability and durability, often compromising on these properties when attempting to reduce heat build-up.
Innovation Solution
A rubber composition for tires comprising 50% or more natural rubber, 15-50% terminal-modified butadiene rubber, carbon black, and silica fillers, with a specific mass ratio and hardness/modulus of repulsion elasticity, enhancing affinity and dispersibility to improve steering stability and durability while maintaining low heat build-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If carbon black blended amount is reduced or particle size is increased to reduce tan δ (60°C), then heat build-up is suppressed, but rubber hardness and fatigue resistance deteriorate
Solution Approach 1:
The patent uses a composite filler system combining carbon black and silica in a specific ratio (0.1 to 0.5 mass ratio of silica to total filler). This composite approach allows the carbon black to provide reinforcement and hardness while silica contributes to reducing heat build-up and improving fatigue resistance, resolving the contradiction between hardness and heat build-up suppression.
Solution Approach 2:
The patent specifies precise parameter ranges: carbon black blended amount of 3-5 parts per 100 parts rubber, silica blended amount of 1-3 parts per 100 parts rubber, and silica particle size of 0.5-2 μm. By optimizing these parameters, the composition achieves both low tan δ (60°C) for heat build-up suppression and adequate hardness (73 or greater) and fatigue resistance.
2Temperature
If silica is blended into the rubber component to reduce tan δ (60°C), then heat build-up is suppressed, but steering stability and durability are compromised
Solution Approach 1:
The patent optimizes silica parameters including particle size (0.5-2 μm), blended amount (1-3 parts per 100 parts rubber), and specific surface area (5-50 m²/g). This precise parameter control ensures silica reduces heat build-up while maintaining steering stability and durability through adequate reinforcement.
Solution Approach 2:
The patent creates a synergistic composite system where carbon black (3-5 parts) and silica (1-3 parts) work together. Carbon black provides reinforcement for durability and steering stability, while silica contributes to heat build-up reduction, achieving a balance that neither filler alone could provide.
3Loss of energy
If filler amount is reduced to lower rolling resistance, then fuel economy is improved, but steering stability and durability deteriorate
Solution Approach 1:
The patent uses a composite filler system with carbon black (3-5 parts) and silica (1-3 parts) that provides adequate reinforcement at low total filler amounts. This composite approach maintains steering stability and durability while minimizing rolling resistance, as the synergistic interaction between fillers maximizes reinforcement efficiency per unit mass.
Solution Approach 2:
The patent optimizes filler parameters including carbon black particle size (20-50 nm), silica particle size (0.5-2 μm), and their blended amounts. These optimized parameters ensure high reinforcement efficiency at low filler concentrations, achieving low rolling resistance while maintaining steering stability and durability.
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 composition achieves reduced rolling resistance, enhanced steering stability, and improved durability by using a combination of natural rubber, terminal-modified butadiene rubber, and carbon black/silica fillers, maintaining well-balanced performance characteristics.
Implementation Method 1
a terminal-modified butadiene rubber... enhancing affinity and dispersibility
Implementation Method 2
tan δ at 60°C... determined by dynamic viscoelasticity measurement
Implementation Method 3
heat build-up of a rubber composition... has been suppressed
Data Source
AI summary
Provided is a rubber composition for tires that is intended mainly for use in an undertread portion of a pneumatic tire, the rubber composition having a low rolling resistance, and excellent steering stability and durability in tires. It is set that the rubber composition includes a rubber component containing 50 mass% or greater of a natural rubber and from 15 mass% to 50 mass% of a terminal-modified butadiene rubber per 100 parts by mass of the rubber component, and a filler containing carbon black and silica that is blended into the rubber component at a mass ratio from 0.1 to 0.5 between a blended amount of the silica and a blended amount of the filler, the rubber composition having a hardness of 73 or greater, and a modulus of repulsion elasticity at 40°C of 60% or greater.