Pneumatic Tire Tread Compound Suppressing Cold Crystallization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Snow/ice tires face challenges in maintaining grip performance at low temperatures due to cold crystallization caused by high levels of cis-BR in tread compounds, which also increases rolling resistance.
Innovation Solution
A vulcanizable rubber composition for tire treads is developed, incorporating a specific blend of polybutadiene rubber with 1,2 vinyl butadiene units (5-15% of total polybutadiene weight) to disrupt polymer chain stereoregularity and suppress crystallization, along with a filler system including carbon black and silica, to balance viscoelastic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high levels of cis-BR are used in the tread compound to achieve low stiffness at low temperatures and low rolling resistance, then grip performance and rolling resistance are improved, but cold crystallization occurs leading to increased stiffness that undermines grip performance
Solution Approach 1:
The patent changes the chemical composition parameters of the polybutadiene rubber by controlling the cis-1,4 content (95-99%) and vinyl-1,2 content (1-5%), thereby modifying the polymer's crystallization behavior and viscoelastic properties to maintain grip performance while reducing cold crystallization
Solution Approach 2:
The patent creates a composite rubber system by combining high-cis polybutadiene with specific fillers (carbon black, silica) and process oils, where the filler-rubber interaction modifies the polymer matrix behavior to suppress unwanted crystallization while maintaining low rolling resistance
2Loss of energy
If high levels of cis-BR are used in the tread compound, then rolling resistance is reduced, but treadwear characteristics deteriorate
Solution Approach 1:
The patent optimizes the vinyl-1,2 content parameter (1-5%) which affects both the hysteresis loss (rolling resistance) and the abrasion resistance (treadwear) of the rubber compound, achieving a balance between these two properties
Solution Approach 2:
The patent uses a composite system of high-cis polybutadiene combined with specific ratios of carbon black and silica fillers, where the filler network provides structural support that enhances treadwear while the rubber matrix maintains low hysteresis for reduced rolling resistance
3Reliability
If mixtures of various types of synthetic and natural rubber are used to balance viscoelastically inconsistent properties, then wet skid resistance and wear characteristics are improved, but the complexity of the rubber compound increases
Solution Approach 1:
The patent extracts and eliminates the need for complex multi-rubber blends by using a single high-cis polybutadiene rubber with specifically controlled composition (95-99% cis-1,4, 1-5% vinyl-1,2), which alone can provide the required balance of wet skid resistance, wear characteristics, and low rolling resistance
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 inhibits undesirable crystallization, maintaining grip performance while reducing rolling resistance and improving treadwear characteristics.
Implementation Method 1
This exposure may induce a phenomenon called 'cold crystallization' leading to a significant increase in the stiffness of tread
Implementation Method 2
a tread comprising a vulcanizable rubber composition
Data Source
AI summary
The present invention is directed to a pneumatic tire having a tread comprising a vulcanizable rubber composition comprising, based on 100 parts by weight of elastomer (phr),(A) from about 50 to about 100 phr of a first polybutadiene rubber comprising from 65 to 95 percent of repeat units derived from butadiene in cis-1,4 insertion, 4 to 30 percent by weight of repeat units derived from butadiene in vinyl-1,2 insertion, and less than or equal to 5 percent by weight of repeat units derived from butadiene in trans-1,4 insertion, −80 to −105° C.;(B) up to 50 phr of at least one rubber selected from the group consisting of a second polybutadiene having a cis-1,4 content greater than 95 percent and a Tg ranging from −80 to −110° C., natural rubber, and synthetic polyisoprene having a cis-1,4 content greater than 95 percent by weight and a Tg ranging from −50 to −80° C.;(C) from 20 to 70 phr of a process oil having a polycyclic aromatic content of less than 3 percent by weight as determined by the IP346 method; and(D) from 50 to 150 of a filler selected from the group consisting of carbon black and silica.