Tire Tread Rubber Composition for Low Rolling Resistance
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Solution Overview
Problem
Existing tire technologies fail to reduce rolling resistance consistently across both low and high temperatures, leading to unstable fuel efficiency.
Innovation Solution
A tire design incorporating a tread rubber composition with high natural rubber content and specific thermoplastic resins, along with silica fillers and a dynamic storage modulus configuration for the bead fillers, to minimize rolling resistance across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If rolling resistance is reduced at high temperatures, then fuel efficiency improves at high temperatures, but fuel efficiency remains unstable due to large temperature-dependent differences
Solution Approach 1:
The patent modifies the rubber compound composition parameters, specifically setting natural rubber content at 50 mass% or more and incorporating polybutadiene rubber with 90% or more 1,4-cis structure. These parameter changes result in a rubber compound whose rolling resistance remains consistently low across different temperatures, thereby stabilizing fuel efficiency and reducing the temperature-dependent variation.
2Loss of energy
If natural rubber content is increased to reduce rolling resistance, then rolling resistance decreases, but compatibility with thermoplastic resin and flexibility are affected
Solution Approach 1:
The patent optimizes the rubber compound composition by setting natural rubber content at 50 mass% or more and incorporating a specific liquid rubber (polybutadiene rubber with 90% or more 1,4-cis structure). This composition achieves low rolling resistance while maintaining adequate compatibility with thermoplastic resin and flexibility, as evidenced by the dynamic storage modulus being 50 MPa or lower at 25°C and 1% strain.
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 solution effectively reduces rolling resistance at both low and high temperatures, achieving a small temperature-dependent difference and enhancing braking performance and steering stability.
Implementation Method 1
a rubber component (A) including 50 mass% or more of natural rubber that is highly compatible with a thermoplastic resin and having compounded therein a particular type of thermoplastic resin that contributes to increasing the flexibility of the tire
Implementation Method 2
setting the dynamic storage modulus (E') measured at 1% strain to a low value for the bead fillers disposed on the radial outside of the bead cores
Data Source
Figure 1
AI summary
A tire has a rolling resistance that is reduced at both low and high temperatures and that exhibits a small difference between low and high temperatures. The tire includes a tread portion and a pair of bead portions each with a bead core and a bead filler disposed on the radial outside of the bead core. Tread rubber forming the tread portion includes a rubber composition including a rubber component (A) and, per 100 parts by mass of the rubber component (A), 5 to 50 parts by mass of at least one kind of thermoplastic resin (B) selected from the group consisting of C5-based resins, C5- to C9-based resins, C9-based resins, terpene-based resins, terpene-aromatic compound-based resins, rosin-based resins, dicyclopentadiene resins, and alkylphenol-based resins, and 20 to 120 parts by mass of a filler (C) including silica. The dynamic storage modulus (E') of the bead filler is 50 MPa or lower.