Rubber Composition with Functionalized Elastomer Chain Ends
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Solution Overview
Problem
Current rubber compositions reinforced with carbon black and diene elastomers rich in ethylene units face a trade-off between rolling resistance and wear resistance, with high hysteresis and rigidity making them unsuitable for semi-finished tire articles, and existing methods fail to effectively modify the chain ends of these elastomers to reduce hysteresis while maintaining performance.
Innovation Solution
A rubber composition featuring a highly saturated diene elastomer with ethylene units, modified with a functional group comprising a silanol or alkoxysilane and an amine function at the chain end, combined with a carbon black reinforcing filler, to achieve reduced hysteresis and rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If diene elastomers rich in ethylene units are used to reduce hysteresis, then rolling resistance performance is improved, but rigidity increases making the composition unsuitable for semi-finished tire articles
Solution Approach 1:
The patent modifies the chemical parameters of the elastomer by introducing functional groups (silane, amine) at chain ends, which changes the physical properties of the rubber composition. This allows reducing rigidity while maintaining low hysteresis through chemical modification rather than compositional changes
Solution Approach 2:
The functional groups act as intermediaries between the elastomer chains and carbon black filler, creating improved interfacial interactions. This mediator effect reduces the rigidity contribution from filler-e elastomer interactions while preserving the low hysteresis benefit
2Loss of energy
If functional groups are grafted on diene units by 1,3-dipolar reaction, then hysteresis is reduced, but the stiffness remains high
Solution Approach 1:
Instead of modifying all diene units throughout the polymer chain, the patent applies functionalization only at specific locations (chain ends), creating local quality differences. This localized modification reduces stiffness impact while maintaining the hysteresis benefit in the bulk material
Solution Approach 2:
The patent changes the functional group type from associative groups (which maintain high stiffness) to silane/amine groups (which reduce stiffness). This parameter change in group chemistry achieves the dual goal of low hysteresis and reduced rigidity
3Quantity of substance
If coordination catalytic polymerization is used to produce diene copolymers rich in ethylene, then ethylene content is increased, but the chain end structure becomes difficult to modify
Solution Approach 1:
The patent incorporates the functionalization step during the polymerization process itself, before the polymerization is complete. This preliminary action allows the functional groups to be introduced at chain ends as they form, making the modification inherent to the synthesis rather than a subsequent difficult step
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 composition achieves a balance between reduced hysteresis and stiffness, enhancing the performance of the rubber, making it suitable for tire applications by modifying the chain ends of the diene elastomer with a silanol or alkoxysilane and amine function, resulting in improved rolling resistance and wear resistance.
Implementation Method 1
The replacement of these elastomers rich in diene unit in these same compositions by diene elastomers rich in ethylene unit can be accompanied by both a reduction in hysteresis of the rubber composition and an increase in its rigidity
Implementation Method 2
a reinforcing filler which mainly contains by mass a carbon black
Data Source
AI summary
The present invention relates to a rubber composition which comprises a reinforcing filler that contains more than 50% by mass of a carbon black, a cross-linking system and a highly saturated elastomer comprising 1,3-diene units and more than 50 mol% of ethylene units and carrying at the chain end a functional group bearing an alkoxysilane or silanol function and an amine function. Such a rubber composition is an improved compromise between the stiffness and hysteresis properties.