Bis-imine Titanium Complex for High 1,4-cis Polybutadiene
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Solution Overview
Problem
Current catalytic systems for the polymerization of conjugated dienes, particularly for producing polybutadiene with a high 1,4-cis unit content, are not efficient enough to meet the demands for high-quality rubber products used in tire treads.
Innovation Solution
A bis-imine titanium complex with a specific general formula is used in a catalytic system that includes a co-catalyst, such as aluminum alkyls or aluminoxanes, to achieve a prevalent 1,4-cis unit content of ≥60% in polybutadiene, enhancing the microstructure control and polymerization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional catalytic systems (TiCl4/AlR3) are used for polymerization of conjugated dienes, then polymerization can be achieved, but the 1,4-cis unit content is limited to 65-70% and cannot meet high-quality rubber product requirements
Solution Approach 1:
The patent changes the chemical parameters of the catalytic system by introducing a bis-imine titanium complex with specific ligand structure (formula I) instead of conventional TiCl4. This parameter change in catalyst composition enables achieving 1,4-cis unit content ≥60% while maintaining good polymerization efficiency, resolving the contradiction between manufacturing precision and productivity.
Solution Approach 2:
The patent creates a composite catalytic system combining bis-imine titanium complex with co-catalysts (aluminoxanes or aluminum alkyls) in specific ratios. This composite approach enhances both the stereoselectivity (1,4-cis content) and activity (polymerization efficiency) of the catalyst system, simultaneously addressing both requirements.
2Reliability
If titanium-based catalytic systems are used to achieve high 1,4-cis content, then stereospecificity is improved, but catalytic activity and polymerization efficiency are insufficient
Solution Approach 1:
The patent modifies the titanium complex parameters by introducing bis-imine ligands with specific substituents (R1-R6 groups) that tune the electronic and steric properties of the catalyst. This parameter optimization enhances both stereospecificity (1,4-cis content ≥60%) and catalytic activity, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent introduces co-catalysts (aluminoxanes or aluminum alkyls) as intermediaries that activate the bis-imine titanium complex. This intermediary system enhances the catalytic activity while preserving the stereospecificity provided by the titanium complex, achieving both high reliability and productivity.
3Manufacturing precision
If existing catalytic formulations are used, then polymerization process is simple, but microstructure control of polybutadiene is insufficient for high-quality applications
Solution Approach 1:
The patent optimizes the parameters of the catalytic system by selecting specific bis-imine ligand structures and co-catalyst types, achieving precise microstructure control (1,4-cis ≥60%, 1,4-trans ≤10%, 1,2 ≤10%). While the catalyst structure becomes more complex, the process remains straightforward, effectively balancing manufacturing precision with acceptable system complexity.
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 bis-imine titanium complex catalytic system effectively produces polybutadiene with a high 1,4-cis unit content, suitable for tire tread applications, by improving the microstructure control and polymerization efficiency, addressing the limitations of existing systems.
Implementation Method 1
A bis-imine titanium complex with a specific general formula is used in a catalytic system that includes a co-catalyst, such as aluminum alkyls or aluminoxanes, to achieve a prevalent 1,4-cis unit content of ≥60% in polybutadiene
Data Source
AI summary
Bis-imine titanium complex having general formula (I): wherein: R1 and R2, mutually identical or different, represent a hydrogen atom; or are selected from linear or branched, optionally halogenated, C1-C20 alkyl groups, preferably C1-C15, optionally substituted cycloalkyl groups; R3 and R4, mutually identical or different, represent a hydrogen atom; or are selected from linear or branched, optionally halogenated, C1-C20 alkyl groups, preferably C1-C15, optionally substituted cycloalkyl groups, optionally substituted aryl groups; X1, X2, X3 and X4, mutually identical or different, represent a halogen atom such as chlorine, bromine, iodine; or are selected from linear or branched C1-C20 alkyl groups, preferably C1-C15, —OCOR5 groups or —OR5 groups wherein R5 is selected from linear or branched C1-C20 alkyl groups, preferably C1-C15; or represent an acetylacetonate group (acac); provided that when R1 and R2 represent a methyl group and X1, X2, X3 and X4 represent a chlorine atom, R3 and R4 are different from 2,6-di-isopropylphenyl.