Rubber Composition Tread for Wet Grip and Wear Balance
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Solution Overview
Problem
Tires face a challenge in balancing wet skid resistance, low rolling resistance, and wear characteristics, as rubbers with high rebound are needed for treadwear but those with high energy loss are required for wet skid resistance, making it difficult to achieve both effectively.
Innovation Solution
A vulcanizable rubber composition comprising 70-100 phr of isoprene-butadiene rubber with a Tg range of -100 °C to -50 °C, 0-30 phr of a second elastomer, 30-80 phr of a resin with a Tg of at least 20 °C, 0-4 phr of oil, and 80-180 phr of carbon black or silica filler, which is synthesized through solution polymerization to achieve a balance of dynamic viscoelastic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If rubbers with high rebound are utilized to improve treadwear characteristics, then wear resistance is improved, but wet skid resistance deteriorates
Solution Approach 1:
The invention changes the glass transition temperature parameter of the elastomer to a specific range (-100°C to -50°C) to simultaneously achieve high rebound for wear resistance and appropriate hysteresis for wet skid resistance. This parameter optimization allows the rubber to exhibit low hysteresis at service temperatures (improving wear life) while maintaining adequate grip on wet surfaces.
Solution Approach 2:
The invention uses a composite rubber composition combining specific elastomers with fillers (carbon black or silica) and resins. This composite structure enables the material to exhibit both high rebound characteristics for wear resistance and controlled energy dissipation for wet skid resistance, resolving the contradiction between these two opposing requirements.
2Reliability
If rubbers with high energy loss are utilized to increase wet skid resistance, then wet skid resistance is improved, but rolling resistance increases
Solution Approach 1:
The invention optimizes the glass transition temperature parameter to a specific range that creates a hysteresis curve with a peak at low temperature (providing wet skid resistance) and lower values at service temperatures (minimizing rolling resistance). This precise parameter control allows the rubber to exhibit temperature-dependent viscoelastic properties that satisfy both contradictory requirements.
Solution Approach 2:
The invention utilizes the dynamic viscoelastic behavior of the rubber, where the hysteresis characteristics change with temperature and frequency. The rubber dynamically adjusts its energy dissipation properties: high hysteresis at low temperatures for wet grip, and low hysteresis at service temperatures for low rolling resistance, thereby resolving the contradiction between wet skid resistance and rolling resistance.
3Ease of operation
If low Tg elastomers are utilized to achieve low stiffness at low temperatures, then low temperature flexibility is improved, but high temperature hysteresis increases
Solution Approach 1:
The invention carefully selects and optimizes the glass transition temperature parameter within a specific range (-100°C to -50°C) rather than using the lowest possible Tg. This optimized parameter ensures sufficient low-temperature flexibility while limiting the increase in high-temperature hysteresis, as extreme low Tg values would cause excessive softening and energy loss at service temperatures.
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 rubber composition enhances traction on snowy and icy roads while maintaining low rolling resistance, by optimizing the glass transition temperatures and filler content, thereby improving the tire's overall performance.
Implementation Method 1
an isoprene-butadiene rubber having a Tg ranging from -100 °C to -50 °C
Implementation Method 2
a resin having a Tg of at least 20 C
Implementation Method 3
from 80 to 180 of a filler selected from the group consisting of carbon black and silica
Data Source
AI summary
A vulcanizable rubber composition is disclosed comprising: (A) 100 parts by weight of elastomer consisting of 70 to 100 parts by weight, per 100 parts by weight of the elastomer (phr), of an isoprene-butadiene rubber having a Tg in a range of from -100 °C to -50 °C, and 0 to 30 phr of a second elastomer selected from the group consisting of isoprene-butadiene rubber having a Tg in a range of from from -49 to -20 °C, natural rubber, synthetic polyisoprene, and polybutadiene; (B) from 30 to 80 phr of a resin having a Tg of at least 20 C; (C) from 0 to 4 phr of an oil; and (D) from 80 to 180 phr of a filler selected from the group consisting of carbon black and silica. The rubber composition may be used in a pneumatic tire such as in a tire tread.