1,4-cis Polybutadiene Polymerization via Lanthanide Catalyst Segmentation
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Solution Overview
Problem
Conjugated diene-based polymers, particularly 1,4-cis polybutadiene, with high linearity are needed to reduce rolling resistance and enhance fuel efficiency in rubber compositions, but existing methods fail to achieve sufficient cis-1,4 bond content and molecular weight modification efficiently, leading to poor mechanical properties and processibility.
Innovation Solution
A method involving the polymerization of 1,3-butadiene or butadiene derivatives using a catalyst composition with a lanthanide rare earth element-containing compound, modified methylaluminoxane, a halogen compound, and an aliphatic hydrocarbon-based solvent, which includes a molecular weight modifier such as trihydrocarbylaluminum or silane compounds, to produce 1,4-cis polybutadiene with a high cis-1,4 bond content and controlled molecular weight distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If DIBAH is used as molecular weight modifier in the catalyst composition, then alkylation and molecular weight modification are achieved, but processibility declines due to polymer blocking catalyst input line and chain transfer occurs causing low linearity
Solution Approach 1:
The patent removes DIBAH from the catalyst composition and replaces it with separate components: an organic aluminum compound for alkylation and a molecular weight modifier (hydrogen, silane, or other organic aluminum compounds). This extraction eliminates the harmful side effects of DIBAH (polymer blocking, chain transfer) while maintaining its beneficial functions through alternative substances.
Solution Approach 2:
The patent segments the dual function of DIBAH (alkylation + molecular weight modification) into separate steps and components. First, alkylation is performed using organic aluminum compound, then molecular weight modification is achieved separately using molecular weight modifiers. This segmentation allows each function to be optimized independently without the trade-offs inherent in using DIBAH.
2Stability of the object's composition
If preforming is carried out with small amount of butadiene to reduce active catalyst species production, then catalyst stability is improved, but polymer blocks catalyst input line causing processibility decline
Solution Approach 1:
The patent eliminates the preforming step entirely by using a catalyst composition that does not require it. The catalyst system with separate organic aluminum compound and molecular weight modifier achieves both catalyst stability and processibility without the harmful side effect of polymer blocking the catalyst input line.
3Productivity
If chain transfer occurs during polymerization reaction, then molecular weight modification is achieved, but linearity decreases causing high branching and increased rolling resistance
Solution Approach 1:
The patent removes the harmful chain transfer side reactions by eliminating DIBAH from the catalyst composition. Molecular weight modification is achieved through controlled mechanisms using molecular weight modifiers (hydrogen, silane compounds, other organic aluminum compounds) that do not cause excessive branching and maintain high linearity.
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 resulting 1,4-cis polybutadiene exhibits high linearity, reduced rolling resistance, and improved fuel efficiency when used in rubber compositions, with enhanced mechanical properties and processibility due to its optimized molecular weight distribution and high cis-1,4 bond content.
Implementation Method 1
a method using a polymerization system including a lanthanide rare earth element-containing compound, particularly a neodymium-based compound
Implementation Method 2
catalyst composition including an organic aluminum compound, a halogen compound and butadiene together with a neodymium-based compound
Data Source
AI summary
The present invention provides a 1,4-cis-polybutadiene which has a high linearity with a stress/relaxation (S/R) value of greater than 1 at 100°C, thereby being capable, when applied to a rubber composition, of reducing resistance characteristics, in particular rolling resistance or rotation resistance, and significantly improving fuel efficiency characteristics, and a rubber composition comprising the same.