Rubber Composition for Low Temperature and Wet Traction
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Solution Overview
Problem
Existing tire tread rubber compositions face challenges in balancing wet traction, winter performance, rolling resistance, and treadwear properties, particularly in maintaining stiffness at low temperatures while reducing stiffness at higher operating temperatures, which affects handling and treadwear resistance.
Innovation Solution
A rubber composition combining high Tg styrene/butadiene elastomer with low Tg cis-1,4-polybutadiene rubber, using pretreated precipitated silica as a reinforcing filler, and incorporating polyethylene glycol to adjust viscosity and maintain stiffness across temperature ranges, along with a minor amount of carbon black for improved traction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relatively high Tg styrene/butadiene elastomer is used to improve wet traction, then wet traction performance is improved, but stiffness at low temperatures increases which deteriorates winter performance
Solution Approach 1:
The patent uses a composite rubber composition combining high Tg SBR (for wet traction) with low Tg polybutadiene rubber (for low temperature flexibility), along with silica filler and polyethylene glycol. This composite approach allows the tread to achieve both wet traction and winter performance by leveraging the complementary properties of different materials.
Solution Approach 2:
The patent modifies the glass transition temperature characteristics of the rubber composition by blending elastomers with different Tg values and adding polyethylene glycol. This parameter adjustment allows the composition to maintain appropriate stiffness across a wide temperature range, from cold winter conditions to warmer operating temperatures.
2Temperature
If stiffness is reduced at low temperatures to improve winter performance, then winter performance is improved, but stiffness at operating temperatures may decrease which deteriorates handling performance
Solution Approach 1:
The patent creates a dynamically responsive rubber composition whose stiffness characteristics change with temperature. The composition is designed to be soft at low temperatures for winter performance while automatically becoming stiffer at operating temperatures for proper handling, achieving adaptive behavior across different thermal conditions.
Solution Approach 2:
The composite rubber system combines materials with different thermal responses, including high Tg SBR, low Tg polybutadiene, silica filler, and polyethylene glycol. This composite structure enables the tread to exhibit temperature-dependent stiffness, being compliant in cold conditions and rigid in warm conditions.
3Reliability
If silica filler content is increased to improve wet traction, then wet traction is improved, but rolling resistance increases which deteriorates fuel efficiency
Solution Approach 1:
The patent optimizes the silica filler characteristics by using pretreated precipitated silica with specific surface area and hydrophobic treatment. This parameter optimization allows achieving high wet traction with reduced silica content or improved dispersion, thereby minimizing the negative impact on rolling resistance while maintaining fuel efficiency.
Solution Approach 2:
The patent uses polyethylene glycol as an intermediary substance that interacts with the silica filler and rubber matrix. This intermediary improves the dispersion and interaction of silica particles, enhancing wet traction while reducing agglomeration that would otherwise increase rolling resistance and energy loss.
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 enhances wet traction, reduces rolling resistance, and improves treadwear resistance while maintaining desired stiffness at higher temperatures, thereby enhancing both winter and dry handling performance of tires.
Implementation Method 1
incorporating polyethylene glycol to adjust viscosity and maintain stiffness across temperature ranges
Implementation Method 2
a reinforcing filler comprising silica such as pretreated precipitated silica
Data Source
AI summary
A rubber composition for use in a pneumatic tire tread is disclosed. The rubber composition comprises, based on parts by weight per 100 parts by weight elastomer (phr): (A) 100 phr of diene-based elastomers comprising: (1) from 50 to 90 phr of a styrene/butadiene elastomer having a Tg in a range of from -35°C to -5°C or in a range of from -30°C to -10°C; (2) from 10 to 50 phr of cis 1,4-polybutadiene rubber having a Tg in a range of from -100°C to -109°C; (3) optionally zero up to 25 of at least one additional diene-based elastomer; (4) from 10 to 50 phr or from 20 to 40 phr of rubber processing oil comprising at least one of a petroleum based rubber processing oil and a vegetable triglyceride oil; (5) from 2 to 40 phr or from 4 to 20 phr of polyethylene glycol having an average molecular weight in a range of from 2000 to 6000; (B) from 40 to 250 phr or from 50 to 175 phr of a rubber reinforcing filler comprising silica and carbon black in a ration of silica to carbon black of at least 9/1; and (C) optionally 2 to 20 phr of a resin, preferably a traction promoting resin.