Tire Rubber Composition for Hardness Stability During Heat Aging
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Solution Overview
Problem
Conventional rubber compositions for tires experience increased hardness over time, leading to decreased grip performance, as they fail to maintain consistent hardness during the service life of the tire.
Innovation Solution
A rubber composition is developed that includes a copolymer obtained by copolymerizing an aromatic vinyl compound and a conjugated diene compound, with a heat aging resistance index of 10 or less, incorporating a hydrogenated styrene-butadiene rubber with a high degree of hydrogenation and a compatible softener, along with specific filler and carbon black content, to minimize changes in hardness over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rubber compositions are used to improve abrasion resistance, then hardness increases, but grip performance decreases
Solution Approach 1:
The patent applies parameter changes by controlling the degree of hydrogenation (60-80 mol%) and molecular weight (200,000-2,000,000) of the hydrogenated styrene-butadiene rubber, along with optimizing softener content (30-70 parts per 100 parts rubber) to achieve a heat aging resistance index of 10 or less, thereby maintaining grip performance while improving abrasion resistance
Solution Approach 2:
The patent uses composite materials by combining hydrogenated styrene-butadiene rubber with specific softeners and fillers in optimized proportions, creating a multi-component system where the interaction between components achieves both high abrasion resistance and maintained grip performance through controlled hardness stability
2Strength
If rubber hardness is increased to improve durability, then abrasion resistance improves, but changes in hardness over time increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the degree of hydrogenation (60-80 mol%) and molecular weight range (200,000-2,000,000) of the rubber polymer, along with optimizing softener content (30-70 parts per 100 parts rubber), to achieve a heat aging resistance index of 10 or less, thereby maintaining hardness consistency while improving durability
Solution Approach 2:
The patent uses softeners with specific Hansen solubility parameters that provide temporary plasticization effect, which are consumed or depleted over time, allowing the rubber to maintain appropriate hardness during service life without excessive hardening, effectively using consumable components to protect the main rubber structure
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 rubber composition effectively maintains reduced changes in hardness, ensuring consistent tire performance and grip over a long period, even after 50,000 km of use, by simulating actual tire service conditions through controlled heat treatment.
Implementation Method 1
the copolymer is a hydrogenated styrene-butadiene rubber having a weight average molecular weight of 200,000 to 2,000,000 and a degree of hydrogenation of 60 mol % or more
Data Source
AI summary
The purpose is to provide rubber compositions and pneumatic tires which have reduced changes in hardness over time. The present invention relates to a rubber composition containing a copolymer obtained by copolymerizing an aromatic vinyl compound and a conjugated diene compound, the rubber composition having a heat aging resistance index defined by equation (1) of 10 or less.