Polyol Block Copolymer Process for High CO2 Content at Mild Pressure
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Solution Overview
Problem
Existing methods using DMC catalysts for producing polyether carbonate polyols are limited in CO2 incorporation, require high pressures, and struggle to produce low molecular weight polyols with substantial CO2 content, resulting in polymers with uneven linkage distribution and stability.
Innovation Solution
A two-reactor system is employed, using a carbonate catalyst in the first reactor to produce a polycarbonate polyol with high carbonate content, followed by a DMC catalyst in the second reactor to introduce polyether linkages, optimizing conditions for each catalyst separately to achieve a balanced polymer structure with high CO2 content and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a DMC catalyst is used alone to produce polyether carbonate polyols, then the polymerization reaction can proceed, but the CO2 incorporation is limited to a maximum of around 50% even under high pressures (more than 40 bar)
Solution Approach 1:
The patent divides the polymerization process into two separate reactions conducted in sequence: first using a carbonate catalyst to produce a polycarbonate polyol with high CO2 content, then using a DMC catalyst to extend the polymer chains with polyether linkages. This segmentation allows each catalyst to perform its optimal function without compromise, achieving high CO2 incorporation without requiring high pressures throughout the entire process.
Solution Approach 2:
The patent performs preliminary action by first producing a polycarbonate polyol with high CO2 content using a carbonate catalyst before introducing the DMC catalyst. This preliminary polycarbonate block serves as a foundation that already contains the desired high CO2 incorporation, allowing the subsequent DMC-catalyzed reaction to focus on chain extension rather than CO2 incorporation.
2Quantity of substance
If a DMC catalyst is used alone to produce polyether carbonate polyols, then the reaction can proceed, but the molecular weight distribution is limited and low molecular weight polyols with substantial CO2 content cannot be produced
Solution Approach 1:
The patent segments the polymerization into two distinct stages: first forming low molecular weight polycarbonate oligomers with high CO2 content using a carbonate catalyst, then using the DMC catalyst to control further chain growth. This segmentation enables precise control over the final molecular weight while maintaining high CO2 content in the polycarbonate blocks.
Solution Approach 2:
The patent changes reaction parameters between the two stages: the first reaction uses a carbonate catalyst under conditions optimized for high CO2 incorporation and low molecular weight product formation, while the second reaction uses a DMC catalyst under conditions optimized for controlled chain extension. This parameter change allows independent optimization of each reaction step.
3Stability of the object's composition
If a DMC catalyst is used alone to produce polyether carbonate polyols, then the reaction can proceed, but the resulting polymer has uneven linkage distribution with ether groups in the centre and carbonate groups towards terminals, reducing stability
Solution Approach 1:
The patent segments the polymer structure into distinct blocks: a polycarbonate block with high carbonate content produced first, followed by polyether block extension. This structural segmentation creates a block copolymer architecture where carbonate and ether linkages are segregated into different blocks rather than randomly distributed, improving overall polymer stability.
Solution Approach 2:
The patent applies local quality by creating different chemical compositions in different parts of the polymer chain: the polycarbonate blocks contain high concentrations of carbonate linkages (high CO2 content), while the polyether blocks contain ether linkages. This local differentiation of chemical properties optimizes the specific benefits of each linkage type in its appropriate location.
4Productivity
If a two-reactor system is used with separate carbonate catalyst and DMC catalyst reactions, then optimisation of conditions for each catalyst can be achieved, but the device complexity increases
Solution Approach 1:
The patent segments the production process into two separate reactors, each dedicated to a specific catalytic reaction. This segmentation allows independent optimization of reaction conditions for each catalyst without compromise, improving overall productivity and product quality despite the increased equipment complexity.
Solution Approach 2:
The patent merges the products of two separately optimized reactions to create a block copolymer with superior properties. By combining the high CO2-content polycarbonate block from the first reactor with the polyether block from the second reactor, the final product achieves both high carbonate content and controlled molecular weight characteristics.
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 low molecular weight polycarbonate block polyether polyols with significant CO2 content under mild pressures, resulting in polymers with enhanced strength, chemical resistance, and thermal stability, suitable for polyurethanes.
Implementation Method 1
the reaction of a carbonate catalyst with CO2 and epoxide, in the presence of a starter and/or solvent to produce a polycarbonate polyol copolymer
Implementation Method 2
the reaction of a DMC catalyst with the polycarbonate polyol compound of the first reaction and epoxide to produce a polyol block copolymer
Data Source
AI summary
A process for producing a polyol block copolymer in a multiple reactor system including a first and second reactor in which a first reaction takes place in the first reactor and a second reaction takes place in the second reactor. The first reaction is the reaction of a carbonate catalyst with CO2 and epoxide, in the presence of starter and/or solvent to produce polycarbonate polyol copolymer and the second reaction is the reaction of DMC catalyst with the polycarbonate polyol compound of the first reaction and epoxide to produce polyol block copolymer. The product of the first reaction is fed into the second as crude reaction mixture, the epoxide and the polycarbonate polyol compound of the first reaction are fed in a continuous or semi-batch manner, and/or the product of the first reaction has neutral or alkaline pH on addition to the second. The invention further relates to the copolymers and products incorporating such copolymers.