Middle-Functionalized Diene Elastomer for Tire Tread
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Solution Overview
Problem
Current rubber compositions for tire manufacturing face challenges in achieving a compromise between low hysteresis for reduced rolling resistance, improved abrasion resistance, and maintaining elastomer flow properties, which are often contradictory and difficult to achieve simultaneously.
Innovation Solution
A modified diene elastomer comprising at least 70% by weight of a linear diene elastomer functionalized predominantly in the middle with an alkoxysilane group and up to 30% by weight of a star-branched diene elastomer, with specific Mooney viscosity and glass transition temperature ranges, which enhances raw processing, hysteresis, and abrasion resistance while retaining elastomer flow resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diene polymers are functionalized at the end of polymerization by coupling agents or star-branching agents to improve interaction with filler, then reinforcement and hysteresis properties improve, but raw processing suitability and resistance to flow deteriorate
Solution Approach 1:
The patent applies local quality by functionalizing the elastomer chains at specific locations (middle of chain versus end of chain) with different functional groups. The alkoxysilane-functionalized elastomer has functional groups distributed along the polymer chains rather than concentrated at ends, creating local interaction zones with fillers that improve reinforcement without compromising overall processability
Solution Approach 2:
The patent creates a composite system by combining alkoxysilane-functionalized diene elastomer with specific fillers (carbon black and/or silica). The functionalized elastomer acts as a matrix that interacts with multiple filler types, creating a composite material system where the functional groups mediate the interface between organic polymer and inorganic fillers, achieving both reinforcement and acceptable processing
2Strength
If tread stiffness is increased to improve wear resistance, then abrasion resistance improves, but rolling resistance increases due to increased hysteresis losses
Solution Approach 1:
The patent changes the chemical parameters of the elastomer by introducing alkoxysilane functional groups with specific side chains (amino, epoxy, thiol, or cyano functions). These parameter changes modify the elastomer-filler interaction strength and the elastomer's dynamic mechanical properties, achieving a balance where wear resistance is improved through better filler bonding while hysteresis losses are controlled through the specific chemical structure of the functional groups
3Loss of energy
If diene elastomers are functionalized with alkoxysilane derivatives to improve hysteresis, then rolling resistance reduces, but the compromise between hysteresis and abrasion properties deteriorates
Solution Approach 1:
The patent achieves multi-functionality by designing alkoxysilane derivatives that bear multiple functional groups (e.g., amino and cyano groups, or epoxy and thiol groups) on the same molecule. These multifunctional agents simultaneously improve hysteresis through silane-hydroxyl interactions and enhance abrasion resistance through strong chemical bonding with fillers, eliminating the need to choose between conflicting performance criteria
Data Source
AI summary
A modified diene elastomer having a good flow resistance, and imparting to a rubber composition containing the same a good compromise of hysteresis and abrasion properties and a satisfactory processing with a view to a tire application is provided. This modified elastomer comprises: a) at least 70% by weight of a linear diene elastomer predominantly functionalized in the middle of the chain by an alkoxysilane group, optionally partly or completely hydrolyzed to silanol, the alkoxysilane group optionally bearing another function capable of interacting with a reinforcing filler, the silicon atom of the alkoxysilane group lying in the main chain of the diene elastomer; b) more than 0 and up to 30% by weight of a star-branched diene elastomer, the Mooney viscosity of said modified diene elastomer varying from 50 to 80 and the glass transition temperature (Tg) thereof varying from −100° C. to −80° C.