Functionalized High-Cis Polybutadiene for Aging-Stable Tire Rubber
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Solution Overview
Problem
High-cis polybutadiene polymers used in tire rubber compositions face challenges with Mooney viscosity growth upon aging, leading to storage issues and performance degradation.
Innovation Solution
A modified high-cis polybutadiene polymer is developed using a catalyst system comprising lanthanide, nickel, or cobalt compounds to polymerize 1,3-butadiene, followed by reaction with a functionalizing compound and stabilizing agents to control Mooney viscosity and aging characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-cis polybutadiene polymers are modified by functionalizing compounds to increase filler-polymer interactions, then initial Mooney viscosity is desirable, but Mooney viscosity growth upon aging occurs creating storage challenges
Solution Approach 1:
A silane-based crosslinking agent is introduced as an intermediary substance between the polybutadiene polymer and filler particles. This crosslinking agent contains both polymer-compatible groups and filler-reactive groups, enabling it to mediate the interaction between polymer and filler while controlling the crosslinking process to prevent excessive viscosity growth during storage.
Solution Approach 2:
The crosslinking degree and network density are precisely controlled by adjusting parameters such as crosslinking agent concentration, catalyst amount, and processing conditions. This parameter control enables optimization of filler-polymer interactions while maintaining stable Mooney viscosity during storage by preventing over-crosslinking.
2Strength
If modification is performed to improve filler interaction, then tire performance is enhanced, but storage stability deteriorates due to viscosity growth
Solution Approach 1:
The polymer is pre-modified with controlled amounts of functional groups and low-level crosslinking during synthesis, but the full crosslinking reaction is deferred until the tire manufacturing process. This preliminary action prepares the polymer for enhanced filler interaction while delaying complete crosslinking to maintain storage stability.
Solution Approach 2:
The polymer composition is designed with built-in buffers including specific stabilizers and controlled crosslinking kinetics that prevent rapid viscosity increase during storage. The crosslinking reaction is engineered to proceed gradually, cushioning against sudden performance degradation while maintaining long-term storage stability.
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 polymer maintains an initial Mooney viscosity of 20-100 and aged Mooney viscosity of no more than 120, addressing storage challenges and ensuring consistent tire performance.
Implementation Method 1
providing a catalyst system comprising (a) a lanthanide-based catalyst system comprising (i) a lanthanide compound, (ii) an alkylating agent, and (iii) a halogen source... (b) a nickel-based catalyst system... (c) a cobalt-based catalyst system... using the catalyst system of (A) to polymerize 1,3-butadiene to produce polymer chains with a living end
Implementation Method 2
reacting the living end polymer chains from (B) with a functionalizing compound having formula (I)... where X is a cyano group... thereby producing a modified high-cis polybutadiene
Data Source
AI summary
Disclosed herein area process for preparing a modified high-cis polybutadiene polymer, a modified high-cis polybutadiene polymer, and tires having a component made using the modified high-cis polybutadiene polymer. The processes make use of a functionalizing compound of formula (I) to prepare the modified high-cis polybutadiene from a quantity of 1,3-butadiene monomer using a specified catalyst system.