Polyether Polyol Preparation via DMC Catalyst Neutralization
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Solution Overview
Problem
Current methods for preparing polyether polyols face challenges such as high-molecular impurity formation, difficulty in producing polyethers with block structures, and the need for costly working-up steps, especially when dealing with high-melting or decomposing starter compounds like sugar or sorbitol, which affect the quality and efficiency of polyurethane production.
Innovation Solution
A method involving the reaction of H-functional starter compounds with alkylene oxides in the presence of a basic catalyst, followed by neutralization with sulfuric acid to create a polymerization-active form, which is then further reacted with DMC catalysts without separation of salts, allowing for the production of polyether polyols with reduced high-molecular impurities and accessible hydrophilic internal blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If base-catalysed addition of alkylene oxides to H-functional starter compounds is used, then the addition reaction can proceed, but high-molecular impurities form and isomerisation of propylene oxide to allyl alcohol occurs at high equivalent weights
Solution Approach 1:
The patent changes the catalyst parameter from base catalyst to DMC catalyst (double metal cyanide complex), which fundamentally alters the reaction pathway and eliminates isomerisation side reactions while maintaining high addition rates. This parameter change in catalyst type resolves the contradiction between productivity and harmful impurity formation.
Solution Approach 2:
The patent converts the harmful effect of high hydroxyl group concentration (which normally deactivates DMC catalysts) into a benefit by using it to activate the DMC catalyst in situ. The high concentration of hydroxyl groups from starters like sugar or sorbitol, which would normally be problematic, actually serve to generate the active catalytic species, eliminating the need for working-up steps.
2Productivity
If DMC catalysts are used with high activity, then catalyst concentration can be reduced to 25 ppm or less, but the catalyst becomes sensitive to high concentrations of hydroxyl groups and polar impurities, causing deactivation
Solution Approach 1:
The patent converts the harmful effect of high hydroxyl group concentration (which would normally deactivate DMC catalysts) into a benefit by using it to activate the DMC catalyst in situ. The high concentration of hydroxyl groups from starters like sugar or sorbitol, which would normally be problematic, actually serve to generate the active catalytic species, eliminating the need for working-up steps.
Solution Approach 2:
The patent introduces an intermediary mechanism where water or alcohol acts as a mediator between the hydroxyl groups and the DMC catalyst. The hydroxyl groups react with water or alcohol to form species that can activate the DMC catalyst without directly deactivating it, thus protecting the catalyst while maintaining high activity.
3Adaptability or versatility
If starters with high concentrations of OH groups or polar impurities are used, then the desired polyether polyol can be produced, but the DMC catalyst cannot be converted into polymerisation-active form or existing reactions halt
Solution Approach 1:
The patent converts the harmful effect of high hydroxyl group concentration (which would normally deactivate DMC catalysts) into a benefit by using it to activate the DMC catalyst in situ. The high concentration of hydroxyl groups from starters like sugar or sorbitol, which would normally be problematic, actually serve to generate the active catalytic species, eliminating the need for working-up steps.
Solution Approach 2:
The patent performs preliminary activation of the DMC catalyst by the hydroxyl groups present in the starter compound or added water/alcohol before the main polymerisation begins. This preliminary action converts the catalyst into its active form in situ, ensuring that even starters with high concentrations of OH groups or polar impurities can successfully initiate polymerisation without deactivating the catalyst.
4Adaptability or versatility
If prepolymers are prepared by base catalysis and then converted by DMC catalysis, then starters with high OH group concentrations can be used, but careful working-up is required to avoid deactivating the DMC catalyst with basic catalyst traces
Solution Approach 1:
The patent converts the harmful effect of high hydroxyl group concentration (which would normally deactivate DMC catalysts) into a benefit by using it to activate the DMC catalyst in situ. The high concentration of hydroxyl groups from starters like sugar or sorbitol, which would normally be problematic, actually serve to generate the active catalytic species, eliminating the need for working-up steps.
Solution Approach 2:
The patent extracts the harmful basic catalyst traces from the system by eliminating the base catalysis step entirely. Instead of preparing prepolymers with base catalyst and then requiring careful removal of basic traces, the method uses DMC catalyst directly with high concentrations of hydroxyl groups, which actually activate rather than deactivate the catalyst, thus removing the need for working-up procedures.
5Manufacturing precision
If working-up steps are performed to separate catalyst and remove impurities, then product quality improves, but production cost and time increase
Solution Approach 1:
The patent converts the harmful effect of high hydroxyl group concentration (which would normally deactivate DMC catalysts) into a benefit by using it to activate the DMC catalyst in situ. The high concentration of hydroxyl groups from starters like sugar or sorbitol, which would normally be problematic, actually serve to generate the active catalytic species, eliminating the need for working-up steps.
Solution Approach 2:
The reaction system performs self-service by using the hydroxyl groups present in the starter compound or added water/alcohol to automatically activate the DMC catalyst in situ. This self-activation eliminates the need for external working-up steps to remove catalyst or adjust pH, as the system self-regulates and the final product already has the desired properties.
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 method enables the production of polyether polyols with lower high-molecular impurity content and higher compressive strength in flexible foams, improving the quality and efficiency of polyurethane production without the need for costly working-up steps.
Implementation Method 1
base-catalysed addition of alkylene oxides to H-functional starter compounds
Implementation Method 2
the component A1) is neutralised with sulfuric acid, the neutralisation of the alkaline, polymerisation-active centres of the crude alkylene oxide addition product being carried out by addition of sulfuric acid
Implementation Method 3
the component A) is reacted with one or more alkylene oxides B1) in the presence of a DMC catalyst B2)
Data Source
AI summary
The invention relates to methods for the preparation of polyether polyols by DMC-catalysed alkylene oxide addition to starter compounds comprising acidic sulfuric acid salts, to the use thereof for the preparation of polyurethanes, and to polyurethanes comprising the polyether polyols according to the invention.