Polymorphogenate-Modified Isoolefin Polymerization for MWD Control
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Solution Overview
Problem
The production of butyl rubber in polymerization processes faces challenges in controlling molecular weight distribution (MWD) due to unpredictable effects of adventitious components in reactor feeds, leading to variations in polymer quality across different plants and diluents, and the inability to produce polymers with targeted MWD.
Innovation Solution
The introduction of polymorphogenates, such as molecular oxygen and chalcogenates, into the catalyst system to modulate the molecular weight characteristics of isoolefin polymers by controlling the formation of active catalyst complex species, allowing for precise adjustment of MWD through the rate of polymorphogenate supply in the polymerization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional carbocationic polymerization processes are used without polymorphogenates, then polymerization can proceed with standard catalyst systems, but molecular weight distribution (MWD) cannot be controlled and varies unpredictably due to adventitious components
Solution Approach 1:
Polymorphogenates act as intermediary substances that mediate between the catalyst system and monomer polymerization. These compounds (oxygenates or thio compounds) modify the catalyst complex to create multiple active species with different polymerization rates, enabling MWD control without fundamentally changing the conventional catalyst system architecture.
Solution Approach 2:
The invention changes the chemical parameters of the catalyst system by introducing polymorphogenates that alter the polymerization kinetics. By adjusting the type and amount of polymorphogenate, the distribution of active catalyst species and their polymerization rates are modified, enabling precise control of MWD while maintaining system compatibility.
2Manufacturing precision
If polymorphogenates are introduced to control MWD, then precise adjustment of molecular weight characteristics is achieved, but the catalyst system requires additional components and modulation mechanisms
Solution Approach 1:
The polymorphogenate is introduced into the catalyst system before polymerization begins, allowing the formation of the desired distribution of active catalyst species in advance. This preliminary modification ensures that the correct MWD is established during propagation without requiring complex real-time adjustments during the polymerization process.
Solution Approach 2:
The catalyst system becomes dynamic with the presence of polymorphogenates, which enable the formation of multiple active species with different polymerization rates. This dynamic system can adapt the MWD by adjusting the polymorphogenate type or concentration, providing flexibility while maintaining ease of manufacture through simple parameter changes.
3Reliability
If multiple active catalyst complex species are formed to achieve controlled MWD, then polymer quality consistency across different plants is improved, but the mechanism becomes more complex requiring modulation of active species formation rates
Solution Approach 1:
Polymorphogenates serve as universal intermediary compounds that can be applied across different plants and catalyst systems to achieve consistent MWD control. By using the same polymorphogenate chemistry, the formation of multiple active species is standardized, ensuring polymer quality consistency without requiring plant-specific complex mechanisms.
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
This approach enables the production of isoolefin polymers and copolymers with controlled MWD greater than 2.0, allowing for consistent polymer quality across different production facilities and the ability to tailor molecular weight distributions in new processes, thereby matching product specifications and producing new grades of polymers.
Implementation Method 1
The catalyst system is typically composed of two components: an initiator and a Lewis acid... isobutylene reacts with the Lewis acid/initiator pair to produce a carbenium ion
Implementation Method 2
additional monomer units add to the formed carbenium ion in what is generally called the propagation step
Data Source
AI summary
The disclosure provides for a process and polymerization system to produce isoolefin polymers (72) utilizing polymorphogenates (16, 26) in the catalyst system to control polydispersity (MWD). The disclosure also provides a catalyst system (20) comprising a plurality of active catalyst complex species (34) formed by combination of a Lewis acid (24), an initiator (22) and a polymorphogenate (26), as well as polymers made using the catalyst system or process. The polymorphogenate (16, 26) can promote or mimic the formation of different active catalyst complex species (34) having different polymerization rates, i.e. different rates of propagation, chain transfer, or termination, as observed by different polydispersities resulting from the presence of relatively different proportions of the polymorphogenate.