Rubber composition based on a highly saturated elastomer and a polar liquid plasticizer
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Solution Overview
Problem
Existing rubber compositions for tires face a challenge in achieving a balanced compromise between low rolling resistance and high wet grip, as these properties are often contradictory.
Innovation Solution
A rubber composition comprising a highly saturated copolymer with ethylene units and 1,3-diene units, a polar liquid plasticizer with a glass transition temperature below -80°C, at least 30 phr of silica, a coupling agent for silica, and a crosslinking system, which improves both rolling resistance and wet grip simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If highly unsaturated diene elastomers (polybutadienes, polyisoprenes, SBR) are used in rubber compositions, then wear resistance is improved, but rolling resistance increases
Solution Approach 1:
The invention changes the saturation parameter of the diene elastomer from highly unsaturated (customary) to highly saturated (more than 80% saturation). This parameter change in the elastomer structure, combined with the specific polar liquid plasticizer having Tg below -80°C, resolves the contradiction by achieving both low rolling resistance and high wear resistance simultaneously.
Solution Approach 2:
The invention creates a composite rubber composition system combining highly saturated diene elastomer with polar liquid plasticizer (having Tg below -80°C), silica reinforcement, and specific coupling agents. This composite approach allows the components to work synergistically, achieving improved wear resistance through silica reinforcement while maintaining low rolling resistance through the saturated elastomer-plasticizer system.
2Loss of energy
If rolling resistance is reduced to improve fuel efficiency, then wet grip performance deteriorates
Solution Approach 1:
The invention changes the glass transition temperature parameter of the liquid plasticizer to below -80°C (specifically mentioning -80°C to -120°C range). This parameter change ensures the plasticizer remains sufficiently flexible at low temperatures to maintain wet grip adhesion while the highly saturated elastomer structure keeps rolling resistance low.
Solution Approach 2:
The polar liquid plasticizer acts as an intermediary substance that mediates between the rigid silica reinforcement (which improves wear resistance) and the elastomer matrix (which provides flexibility). The specific requirement of Tg below -80°C ensures this intermediary maintains adequate flexibility and adhesion for wet grip while allowing the silica to provide reinforcement without excessively increasing 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 composition achieves a significant improvement in both rolling resistance and wet grip, enhancing the overall performance of tire materials.
Implementation Method 1
a polar liquid plasticizer having a Tg below −80° C.
Implementation Method 2
at least one agent for coupling silica to a diene elastomer
Implementation Method 3
a crosslinking system
Data Source
AI summary
Rubber compositions having improved rolling resistance and wet grip are based on at least one elastomer matrix comprising at least one copolymer containing ethylene units and 1,3-diene units, the molar fraction of ethylene units in the copolymer being within a range extending from more than 50% to 95%, the copolymer not containing any unit of a 1,3-diene of formula CH2═CR—CH═CH2, the symbol R representing a hydrocarbon chain having 3 to 20 carbon atoms; a polar liquid plasticizer having a Tg below −80° C.; at least 30 phr of silica; at least one agent for coupling the silica to a diene elastomer; and a crosslinking system. Rubber articles, in particular pneumatic or non-pneumatic tires, may comprise the rubber compositions, especially in the tread of such tires.