Ribbed Tire Tread Rubber Composition Stiffness Hysteresis Balance
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Solution Overview
Problem
Pneumatic tires with circumferential ribbed treads face challenges in achieving a balance of stiffness, reduced hysteresis, and resistance to abrasion, as conventional rubber compositions with high cis 1,4-polybutadiene and carbon black content increase hysteresis and internal heat buildup, while also complicating processing.
Innovation Solution
A rubber composition for pneumatic tires featuring a combination of specialized cis 1,4-polybutadiene rubber with a high heterogeneity index, controlled carbon black reinforcement, low precipitated silica, and a specific sulfur cure package with two sulfenamide accelerators, optimized to enhance processability and cured properties, such as resistance to abrasion and reduced hysteresis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high cis 1,4-polybutadiene and carbon black content are used to promote resistance to tread wear and increased stiffness, then abrasion resistance and handling are improved, but hysteresis increases causing internal heat buildup
Solution Approach 1:
The patent applies parameter changes by carefully controlling the composition ratios of cis 1,4-polybutadiene (60-80 phr), carbon black (30-50 phr), and silica (0-20 phr) to optimize the balance between stiffness and hysteresis. This quantitative adjustment of material parameters resolves the contradiction by achieving adequate stiffness while minimizing energy loss.
Solution Approach 2:
The patent uses composite materials by combining multiple rubber compounds (cis 1,4-polybutadiene, trans 1,4-polybutadiene, and natural rubber) with different filler systems (carbon black and silica). This composite approach allows the tread to achieve both stiffness from carbon black reinforcement and reduced hysteresis from the synergistic filler combination.
2Reliability
If high cis 1,4-polybutadiene and carbon black content are used to promote resistance to tread wear, then abrasion resistance is improved, but processing difficulty increases due to increased viscosity
Solution Approach 1:
The patent applies parameter changes by controlling the molecular weight and heterogeneity index of cis 1,4-polybutadiene, and optimizing the total filler content (carbon black plus silica) to maintain processability. By adjusting these material parameters, the patent achieves high abrasion resistance while keeping the uncured rubber composition processable through conventional mixing and extrusion.
Solution Approach 2:
The patent uses silica as an intermediary filler that works synergistically with carbon black. The silica particles act as a mediator that reduces the overall viscosity impact of high carbon black content, enabling both high abrasion resistance and acceptable processing characteristics through the combined filler system.
3Strength
If high carbon black content is used to promote increased stiffness, then handling is improved, but internal heat buildup increases due to increased hysteresis
Solution Approach 1:
The patent uses composite materials by combining carbon black with silica in a synergistic filler system. This composite approach maintains the stiffness benefits of carbon black reinforcement while the silica component reduces hysteresis and associated heat generation, resolving the contradiction between stiffness and thermal management.
Solution Approach 2:
The patent applies parameter changes by optimizing the carbon black to silica ratio and controlling the total filler content to achieve the desired stiffness level. By adjusting these compositional parameters, the patent achieves adequate stiffness while minimizing the hysteresis-induced heat buildup that would occur with high carbon black content alone.
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 provides a balanced set of properties including improved abrasion resistance, reduced internal heat buildup, and enhanced processing ease, making it suitable for heavy-duty tires with circumferential ribbed treads.
Implementation Method 1
a cure package for the rubber composition is proposed with a relatively low ratio of sulfur to sulfur cure accelerator to promote a relatively low sulfur cure density of the rubber composition
Implementation Method 2
a sulfur cure accelerator combination of two primary sulfur cure accelerators comprised of two different sulfenamide based accelerators without, and therefore in an absence of, a secondary sulfur cure accelerator
Implementation Method 3
a high reinforcing rubber reinforcing carbon black is proposed
Implementation Method 4
a low level of precipitated silica is proposed to promote acceptable hysteresis in terms of rubber rebound physical property
Implementation Method 5
reduced hysteresis (indicated by a rebound physical property) to promote reduced internal heat buildup within the tread ribs during service
Implementation Method 6
use of a cis 1,4-polybutadiene rubber with a high heterogeneity index is proposed to promote processability of the cis 1,4-polybutadiene rubber
Implementation Method 7
processing the uncured rubber composition involving mixing the rubber composition in an internal rubber mixer and, also shaping it by extrusion processes because of expected increased viscosity of the uncured rubber composition
Data Source
AI summary
The invention relates to pneumatic tires with ribbed rubber treads which may be, for example pneumatic tires such as bus tires and truck tires. The rubber treads are comprised of a blend of specialized cis 1,4-polybutadiene rubber and cis 1,4-polyisoprene rubber containing reinforcing filler comprised of a combination of rubber reinforcing carbon black and precipitated silica together with silica coupler, wherein the tread rubber contains a cure package comprised of sulfur together with two sulfenamide primary sulfur cure accelerators.