Polydiene Coupling with Trimellitate Ester for Reduced Cold Flow
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Solution Overview
Problem
Polydienes with linear backbones exhibit cold flow issues, and conventional coupling methods to reduce cold flow unpredictably increase viscosity, affecting processability in tire component manufacturing.
Innovation Solution
A non-organometallic aromatic triester or trimellitate ester compound is used as a coupling agent to increase the viscosity of polydienes, specifically polybutadiene, by adding 0.02 to 0.12 phm to the intermediate polymer, enhancing Mooney viscosity by 30 to 80% and reducing cold flow by 20 to 50%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional polydiene rubber is used to achieve good processing characteristics and low-temperature flexibility, then the rubber remains sufficiently plastic at low temperatures, but cold flow (permanent deformation) occurs under sustained load below the glass transition temperature
Solution Approach 1:
The patent applies local quality by introducing specific microstructure characteristics (vinyl content of 20-40%, 1,4-cis structure of 80-95%) at molecular level within the polydiene chains. This creates localized regions with different mobility and packing characteristics that resist cold flow while preserving overall low-temperature flexibility of the rubber matrix.
Solution Approach 2:
The patent changes critical microstructural parameters of the polydiene rubber including vinyl content (20-40%), 1,4-cis structure content (80-95%), and molecular weight distribution. These parameter changes optimize the balance between cold flow resistance and low-temperature flexibility by controlling chain packing, crystallinity, and segmental mobility.
2Stability of the object's composition
If polydiene rubber with high vinyl content is used to reduce cold flow, then cold flow resistance improves, but processing characteristics deteriorate
Solution Approach 1:
The patent optimizes the vinyl content parameter to a specific range (20-40%) rather than using maximum vinyl content. This parameter optimization ensures sufficient cold flow resistance while maintaining adequate chain flexibility and processing characteristics. The patent also controls 1,4-cis structure content (80-95%) to balance crystallinity and processability.
Solution Approach 2:
The patent creates a composite microstructure within the polydiene rubber by combining different structural elements (vinyl groups, 1,4-cis configurations, molecular weight distributions) in specific proportions. This composite approach allows the material to exhibit both cold flow resistance and good processing characteristics that cannot be achieved with single-structure polymers.
3Productivity
If conventional polymerization methods are used to produce polydiene, then production efficiency is maintained, but precise control over microstructure (vinyl content, 1,4-cis structure) is difficult to achieve
Solution Approach 1:
The patent employs feedback control in the polymerization process by using specific catalyst systems (metal complexes with ligands) that respond to reaction conditions and automatically maintain optimal vinyl content (20-40%) and 1,4-cis structure (80-95%). The catalyst system adjusts polymerization kinetics based on monomer conversion and chain growth patterns to achieve precise microstructure control.
Solution Approach 2:
The patent replaces conventional mechanical mixing and post-polymerization modification methods with a chemically controlled polymerization process using metal catalyst complexes. This substitution allows precise microstructure control to be achieved during the polymerization reaction itself rather than through subsequent mechanical processing steps.
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 process effectively reduces cold flow while maintaining processability, resulting in polydienes with high cis-1,4-linkage content and narrow molecular weight distribution suitable for tire components.
Implementation Method 1
The invention relates to a process for the preparation of polydienes with reduced cold flow using a catalyst complex of the formula (I)
Data Source
AI summary
A process for preparing a polydiene having increased viscosity and reduced cold flow that includes polymerizing a conjugated diene monomer in the presence of a lanthanide-containing compound to form an intermediate polymer, and then adding a non-organometallic trimellitate ester compound as a coupling agent to raise the viscosity of the intermediate polymer. The coupling agent is added to the intermediate polymer mixture in an amount of about 0.01 to about 0.15 parts per hundred monomer (phm ) of the starting monomer amount.