Motorcycle Tire Rubber Composition for Dry Grip and Sag Resistance
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Solution Overview
Problem
Motorcycle tires face a challenge in maintaining dry grip performance during high-speed running due to temperature-dependent changes in viscoelasticity, leading to decreased grip and increased risk of cracking at low temperatures.
Innovation Solution
A rubber composition for motorcycle tires is developed, containing diene-based rubber and silica, with specific ranges for loss factor (tanδ) at 70°C and glass transition temperature (Tg) to enhance dry grip and sag resistance, including a minimum of 40 parts by mass of silica per 100 parts by mass of rubber component, and a diene-based rubber composition with styrene-butadiene rubber as the primary component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If grip resin is added to improve dry grip performance, then grip force is improved, but temperature-dependent change in viscoelasticity increases causing sag during high-speed running
Solution Approach 1:
The patent applies parameter changes by precisely controlling the glass transition temperature (Tg) to be -50°C to -100°C and the loss factor tanδ at 70°C to be 0.40 or less. These parameter specifications optimize the rubber composition's viscoelastic properties to maintain consistent grip performance across temperature variations, preventing sag during high-speed running while preserving dry grip force.
Solution Approach 2:
The patent uses composite materials by combining specific rubber components (polybutadiene rubber with 80-95 mass% of the total rubber, styrene-butadiene rubber with 5-20 mass%) with silane-modified polysiloxane resin. This composite formulation achieves both improved dry grip and reduced temperature-dependent viscoelasticity changes, resolving the contradiction between grip force and sag resistance.
2Strength
If grip resin is added to improve grip performance, then grip force is improved, but glass transition temperature increases causing cracks at low temperature
Solution Approach 1:
The patent applies parameter changes by setting the glass transition temperature (Tg) to a specific range of -50°C to -100°C, which is lower than conventional formulations. This parameter optimization allows the rubber composition to maintain flexibility and crack resistance at low temperatures while still achieving improved grip performance through the use of polybutadiene rubber and silane-modified polysiloxane resin.
3Strength
If silica content is increased to improve dry grip performance, then grip force is improved, but processing difficulty increases
Solution Approach 1:
The patent uses silane-modified polysiloxane resin as an intermediary substance that facilitates the dispersion and bonding of silica particles within the rubber matrix. This intermediary agent enables the use of high silica content (40-80 parts by mass per 100 parts by mass of rubber component) while maintaining processability and manufacturing ease, as the resin modifies the silica-rubber interface to prevent aggregation and improve mixing.
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 improves dry grip performance and sag resistance, maintaining high grip during high-speed running while reducing the risk of cracking at low temperatures.
Implementation Method 1
a temperature-dependent change in viscoelasticity tan8 increases
Implementation Method 2
the glass transition temperature (Tg) of the rubber composition
Data Source
Figure 1
Figure 2~3
AI summary
Provided is a motorcycle tire in which dry grip performance and sag resistance are improved. The motorcycle tire has a tread made from a rubber composition including: a rubber component containing a diene-based rubber; and a filler containing not less than 40 parts by mass of silica per 100 parts by mass of the rubber component. The rubber composition satisfies the following expression (1) and expression (2), tanδ at70°C≥0.23, and Tg≤−8°C.