Modified Diene Elastomer with Narrow PDI for Tire Tread
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Solution Overview
Problem
Current rubber compositions for tire applications face challenges in achieving a balance between low hysteresis and good processing properties without compromising the resistance to flow, which is essential for manufacturing and storage.
Innovation Solution
A modified diene elastomer comprising at least 70% by weight of a linear diene elastomer functionalized predominantly in the middle of the chain with an alkoxysilane group, optionally hydrolysed to silanol, and up to 30% by weight of a star-branched diene elastomer, with a narrow molecular weight distribution, which improves the raw processing/hysteresis compromise while maintaining elastomer resistance to flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If diene polymers are functionalized by alkoxysilane derivatives to reduce hysteresis, then hysteresis and abrasion resistance are improved, but processing properties become insufficient for tire tread applications
Solution Approach 1:
The patent changes the molecular weight distribution parameter of the diene polymer, specifically using a narrow PDI (1.05-1.30) combined with controlled molecular weight (20,000-100,000 g/mol). This parameter change allows the polymer to maintain both low hysteresis through functionalization and adequate processing properties, resolving the contradiction between energy loss reduction and manufacturability.
Solution Approach 2:
The patent creates a composite system by combining diene polymer with alkoxysilane functional groups and reinforcing fillers (carbon black or silica). This composite approach enables simultaneous achievement of reduced hysteresis, improved abrasion resistance, and maintained processing properties that none of the components could achieve alone.
2Strength
If elastomers are functionalized to improve interaction with reinforcing filler, then mechanical properties are improved, but raw processing capability deteriorates
Solution Approach 1:
The patent optimizes the functional group content parameter to 0.1-5 mmol/kg, which is sufficient to provide good interaction with reinforcing fillers for improved mechanical properties but not excessive to cause severe processing difficulties. This balanced parameter setting resolves the contradiction between strength enhancement and processing ease.
Solution Approach 2:
The patent applies functional groups locally rather than uniformly throughout the polymer structure. The functional groups are present at controlled low concentrations (0.1-5 mmol/kg), providing localized interaction sites with fillers while the bulk polymer maintains its inherent processability, thus resolving the contradiction between mechanical property improvement and raw processing capability.
3Loss of energy
If hysteresis is reduced for fuel savings, then rolling resistance is reduced, but resistance to flow of elastomers deteriorates
Solution Approach 1:
The patent carefully selects molecular weight (20,000-100,000 g/mol) and PDI (1.05-1.30) parameters that create a balance between hysteresis reduction and flow resistance maintenance. The narrow PDI ensures uniform chain lengths that reduce energy loss, while the controlled molecular weight range maintains adequate viscosity and flow resistance for practical applications.
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 modified diene elastomer enhances the hysteresis and processing properties of rubber compositions, ensuring better raw processing and resistance to flow, making them suitable for tire applications by improving the hysteresis/raw processing compromise without damaging the elastomer's properties.
Implementation Method 1
functionalized predominantly in the middle of the chain by an alkoxysilane group
Implementation Method 2
optionally partially or completely hydrolysed to give silanol
Data Source
AI summary
A modified diene elastomer is provided. The elastomer comprises:at least 70% by weight, with respect to the total weight of the modified diene elastomer, of a linear diene elastomer functionalized predominantly in the middle of the chain by an alkoxysilane group, optionally partially or completely hydrolysed to give silanol, the alkoxysilane group optionally bearing another functional group capable of interacting with a reinforcing filler, the alkoxysilane group bonded to the two branches of the diene elastomer via the silicon atom, the functionalized diene elastomer exhibiting a polydispersity index before fractionalization of less than or equal to 1.6; andmore than 0 and up to 30% by weight, with respect to the total weight of the modified diene elastomer, of a star-branched diene elastomer exhibiting a polydispersity index before star-branching of less than or equal to 1.6,the Mooney viscosity of the modified diene elastomer varying from 30 to 80.