Tire Tread Rubber Composition Low Temperature Stiffness
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Solution Overview
Problem
Existing tire tread rubber compositions face challenges in balancing wet traction and low-temperature performance, as high molecular weight diene-based elastomers with precipitated silica reinforcement tend to have high stiffness, which is detrimental for winter conditions.
Innovation Solution
A rubber composition combining high Tg styrene/butadiene elastomers extended with triglyceride vegetable oil, lower Tg cis 1,4-polybutadiene rubber, and pre-hydrophobated precipitated silica, along with carbon black, to reduce cured stiffness while maintaining wet traction capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high molecular weight diene-based elastomers with precipitated silica reinforcement are used to improve wet traction, then wet traction performance is improved, but cured stiffness increases which is detrimental for low-temperature performance
Solution Approach 1:
The patent changes the chemical composition parameters of the rubber compound by incorporating specific elastomers (styrene-butadiene rubber with 20-40 phr, polybutadiene rubber with 30-60 phr) and controlling the glass transition temperatures of the elastomer blend. This parameter adjustment allows the compound to achieve both high wet traction through silica reinforcement and low cured stiffness through the specific elastomer composition and their different Tg values, resolving the contradiction between wet traction and low-temperature performance
Solution Approach 2:
The patent uses a composite material system combining multiple elastomers (styrene-butadiene rubber and polybutadiene rubber) with precipitated silica reinforcement and specific additives. This composite approach allows the synergistic interaction between different materials to achieve both high wet traction (through silica-elastomer interaction) and low cured stiffness (through the flexible polybutadiene component with low Tg), simultaneously satisfying both performance requirements
2Reliability
If high Tg styrene/butadiene elastomers are used to promote wet traction, then wet traction is improved, but cold weather performance deteriorates due to higher stiffness
Solution Approach 1:
The patent adjusts the glass transition temperature parameters of the elastomer blend by combining S-SBR (with higher Tg for wet traction) with polybutadiene rubber (with lower Tg for flexibility). The specific ratio and Tg range of the blend are controlled to achieve the optimal balance: the higher Tg component provides wet traction while the lower Tg component maintains flexibility at low temperatures, resolving the contradiction between wet traction and cold weather performance
3Ease of manufacture
If petroleum based rubber processing oil is added to reduce uncured viscosity, then processing conditions are improved, but cured stiffness increases reducing low temperature performance
Solution Approach 1:
The patent replaces traditional petroleum-based rubber processing oil with a vegetable oil-based processing oil that is specifically designed for this application. This alternative processing oil provides the necessary lubrication and viscosity reduction during processing while having a more favorable effect on the final cured compound's flexibility and low-temperature performance, resolving the contradiction between processing ease and cured stiffness
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 improved cold weather performance with lower stiffness at -20°C, maintaining wet traction and rolling resistance, as demonstrated by experimental tire tread samples.
Implementation Method 1
the high Tg S-SBR is extended with from about 10 to about 38 parts by weight per 100 parts of said high Tg S-SBR of triglyceride vegetable oil
Implementation Method 2
pre-hydrophobated precipitated silica (hydrophobated prior to its addition to the rubber composition) comprised of precipitated silica pre-hydrophobated (pre-reacted) with an alkoxyorganomercaptosilane or bis(3-triethoxysilylpropyl) polysulfide
Implementation Method 3
a combination of high Tg and lower Tg styrene/butadiene elastomers together with a low Tg cis 1,4-polybutadiene rubber to beneficially promote a lower stiffness of the cured rubber composition at about −20° C.
Data Source
AI summary
This invention relates to a rubber composition containing cis 1,4-polybutadiene and dual styrene/butadiene elastomers with reinforcing filler comprised of pre-hydrophobated precipitated silica and rubber reinforcing carbon black. The rubber composition may contain triglyceride vegetable oil such as soybean oil. The rubber composition is used for a tire tread.