Tire Tread Rubber Composition for Wet Traction and Winter Grip
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Solution Overview
Problem
Existing tire tread rubber compositions face challenges in balancing wet traction and winter performance, as they tend to lose stiffness at higher temperatures, leading to reduced wet and dry handling performance.
Innovation Solution
A rubber composition combining high or low Tg styrene/butadiene elastomers with 1,4-polybutadiene rubber, reinforced with silica and carbon black, and incorporating tris(2-ethyl hexyl) phosphate to maintain stiffness at higher temperatures while reducing stiffness at low temperatures, along with vegetable triglyceride oils to enhance processing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tread rubber composition contains high or low Tg styrene/butadiene elastomer with precipitated silica for wet traction, then tan delta at 0°C is maximized for improved wet traction performance, but stiffness at higher temperatures (40°C to 60°C) is reduced leading to poorer wet and dry handling performance
Solution Approach 1:
The patent applies parameter changes by carefully controlling the glass transition temperature (Tg) of the styrene/butadiene elastomer within a specific range (-50°C to -10°C) and optimizing the ratio of polybutadiene rubber to SBR (0.5 to 2.0). This parameter optimization allows the composition to achieve both high tan delta at 0°C for wet traction and adequate stiffness at higher temperatures for handling performance
Solution Approach 2:
The patent uses a composite material system combining polybutadiene rubber (60-90 parts) with styrene/butadiene elastomer (10-40 parts), along with precipitated silica (50-150 parts) and specific coupling agents. This composite formulation creates a synergistic effect where the low Tg polybutadiene provides flexibility and high tan delta at 0°C, while the SBR component and silica reinforcement maintain stiffness at higher operating 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 solution achieves improved wet traction and cold weather performance by optimizing tan delta and stiffness properties, maintaining desired stiffness at higher temperatures for better wet and dry handling while providing enhanced low-temperature performance.
Implementation Method 1
providing tris(2-ethyl hexyl) phosphate to promote a lowering of the stiffness of the rubber composition at low temperatures while substantially maintaining a higher stiffness of the rubber composition at the operating temperature range of the tire tread
Implementation Method 2
containing a petroleum and/or vegetable triglyceride based rubber processing oil to reduce the viscosity of the uncured rubber composition and to thereby promote more desirable processing conditions
Implementation Method 3
a reinforcing filler comprising silica, preferably precipitated silica
Data Source
AI summary
A rubber composition for use in a tread of a pneumatic tire is disclosed comprising, based on parts by weight per 100 parts by weight elastomer (phr): (A) 100 phr of diene-based elastomers comprising: (1) from 25 to 75 phr of a styrene/butadiene elastomer having a Tg in a range of from -35°C to -5°C or having a Tg in a range of from -85°C to - 50°C; (2) from 25 to 75 phr of a 1,4-polybutadiene rubber having a Tg in a range of from -100°C to -109°C; (3) optionally from zero to 25 phr of at least one of 1,4-polyisoprene, copolymers of isoprene and butadiene and copolymers of isoprene and styrene; (4) from 10 to 50 phr of a rubber processing oil comprising at least one of petroleum based rubber processing oil and vegetable triglyceride oil; (5) from 2 to 40 phr of tris(2-ethyl hexyl) phosphate; (B) from 50 to 250 phr of a rubber reinforcing filler comprising a combination of silica and carbon black; and (C) from 5 to 60 phr of a resin comprising at least one of terpene, coumarone indene and styrene-alphamethylstyrene resin, the resin having a softening point (ASTM E28) in a range of from 60°C to 150°C.