Polyolefin-Polystyrene Multiblock Copolymer via Staged Polymerization
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Solution Overview
Problem
Conventional methods for preparing polyolefin-polystyrene-based multiblock copolymers face challenges such as non-uniform structure, high production costs, and difficulties in heat removal and reactant recycling due to batch-type polymerization, leading to deteriorated physical properties.
Innovation Solution
A method involving continuous type coordination polymerization of ethylene and alpha-olefin-based monomers followed by batch type anionic polymerization of styrene-based monomers, using hafnium and organozinc compounds, to form a polyolefin-polystyrene-based multiblock copolymer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If batch type polymerization is used for coordination polymerization and anionic polymerization, then the polymerization process can be completed, but heat removal becomes difficult and operation costs increase
Solution Approach 1:
The patent divides the polymerization process into two separate stages: (1) coordination polymerization in a continuous reactor to form polyolefin blocks, and (2) anionic polymerization in a batch reactor to form polystyrene blocks. This segmentation allows the heat-intensive coordination polymerization to be performed continuously with efficient heat removal, while the anionic polymerization is performed in a controlled batch mode, thereby resolving the heat removal difficulty while maintaining productivity.
Solution Approach 2:
The patent implements continuous coordination polymerization using a continuous reactor where monomers, catalysts, and other reagents are continuously fed and the polymerization reaction proceeds continuously. This continuous operation enables efficient heat removal through continuous heat exchange and eliminates the heat accumulation problems associated with batch processing, thereby improving both heat removal capability and operational efficiency.
2Productivity
If batch type polymerization is used, then the polymerization can be performed, but control of reactant concentration uniformity is limited and physical properties deteriorate
Solution Approach 1:
The patent segments the polymerization process into continuous coordination polymerization for polyolefin blocks followed by batch anionic polymerization for polystyrene blocks. The continuous coordination polymerization ensures uniform reactant concentration and consistent polyolefin block formation, while the subsequent batch anionic polymerization adds polystyrene blocks with controlled uniformity, thereby achieving overall structure uniformity that cannot be obtained through single batch processing.
Solution Approach 2:
The patent changes the operational mode parameter from batch to continuous for the coordination polymerization step, which fundamentally improves reactant concentration uniformity throughout the reaction. Continuous flow ensures that all reaction zones experience identical conditions over time, eliminating the concentration gradients and variability inherent in batch processes, thereby producing polyolefin blocks with superior structural uniformity.
3Reliability
If conventional two-step process with hydrogenation reaction is used to prepare SEBS or SEPS, then thermoplastic elastomer properties are achieved, but manufacturing cost increases significantly
Solution Approach 1:
The patent extracts and eliminates the hydrogenation reaction step from the conventional two-step process. Instead of performing anionic polymerization of styrene and butadiene/isoprene followed by hydrogenation, the patent directly performs coordination polymerization of ethylene and butadiene/isoprene to form polyolefin blocks with terminal double bonds, then adds polystyrene blocks through anionic polymerization. This extraction of the hydrogenation step significantly reduces manufacturing cost while maintaining thermoplastic elastomer properties through the multiblock structure.
Solution Approach 2:
The patent discards the conventional approach of fully hydrogenating double bonds and instead retains the terminal double bonds in the polyolefin blocks. These retained double bonds serve as anchoring points for the subsequent anionic polymerization of styrene, forming the multiblock structure. By discarding the hydrogenation step and recovering the utility of terminal double bonds for block copolymer formation, the patent achieves cost reduction while maintaining functional properties.
4Productivity
If continuous type coordination polymerization is used, then productivity increases and manufacturing cost reduces, but requires sophisticated reactor system
Solution Approach 1:
The patent segments the overall polymerization system into two distinct reactor types: a continuous reactor for coordination polymerization and a batch reactor for anionic polymerization. This segmentation allows each reactor to be optimized for its specific function - the continuous reactor handles the complexity of continuous feeding, heat removal, and product discharge, while the batch reactor provides simple, flexible operation for the second polymerization step, thereby managing overall system complexity while achieving high productivity.
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 enhances productivity and reduces manufacturing costs while improving the physical properties of the copolymer, making it suitable for various industrial applications.
Implementation Method 1
preparing a polyolefin by performing coordination polymerization of ethylene and an alpha-olefin-based monomer, while continuously injecting a hafnium compound, an organozinc compound
Implementation Method 2
performing anionic polymerization of the polyolefin and a styrene-based monomer in the presence of an alkyllithium compound
Data Source
AI summary
The present invention relates to a method for preparing a polyolefin-polystyrene-based multiblock copolymer having a uniform structure and showing excellent physical properties through continuous type coordination polymerization and batch type anionic polymerization.