Double Metal Cyanide Catalyst Reactivity Control
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Solution Overview
Problem
Conventional polyol synthesis using KOH catalysts results in undesirable unsaturated polyols, leading to poor physical properties in polyurethane products due to side reactions and requires costly separation processes, while highly active double metal cyanide (DMC) catalysts are excessively reactive and difficult to control, causing sudden exothermic reactions.
Innovation Solution
A double metal cyanide catalyst with controlled reactivity is developed, comprising specific metal elements and ether-glycol complexing agents, allowing for controlled reactivity and targeted unsaturation degree in polyol production, preventing sudden exothermic reactions and enabling the use of conventional reactors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If KOH catalyst is used for polyol synthesis, then the catalyst is inexpensive and easy to handle, but unsaturated polyols are produced through side reactions leading to poor physical properties and requiring costly separation processes
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by replacing KOH with DMC catalyst and modifying the complexing agent from alcohol to ether-glycol mixture, thereby controlling the reaction pathway to achieve desired unsaturation degree while maintaining ease of manufacture
Solution Approach 2:
The patent uses a composite catalyst system comprising DMC catalyst combined with ether-glycol complexing agents, where the synergistic interaction between components provides both ease of handling and precise control over unsaturation degree, eliminating the need for costly separation processes
2Manufacturing precision
If highly active DMC catalyst is used to minimize unsaturated polyol content, then the unsaturation degree is reduced to about 0.005 meq/g, but the catalyst is excessively reactive causing sudden exothermic reactions that are difficult to control
Solution Approach 1:
The patent modifies the chemical parameters of the catalyst system by introducing ether-glycol complexing agents that moderate the reactivity of DMC catalyst, thereby maintaining low unsaturation degree (0.015-0.05 meq/g) while preventing sudden exothermic reactions and enabling controlled temperature progression
Solution Approach 2:
The ether-glycol complexing agents act as intermediaries between the DMC catalyst and the epoxide monomers, moderating the catalyst's excessive reactivity while still enabling effective polymerization, thus controlling the exothermic reaction rate without sacrificing catalytic activity
3Manufacturing precision
If highly active DMC catalyst is used to produce polyol with very low unsaturation degree, then the polyol properties are greatly different from conventional polyols, but this necessitates significant modification of the conventional polyurethane manufacturing process
Solution Approach 1:
The patent optimizes the unsaturation degree parameter to a moderate range (0.015-0.05 meq/g) rather than minimizing it to 0.005 meq/g, thereby maintaining compatibility with conventional polyurethane manufacturing processes while still achieving improved physical properties and catalyst ease of handling
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 catalyst produces polyols with a suitable unsaturation degree, enhancing polyurethane foam properties such as elongation and breathability, and can be used in standard reactors, improving productivity and process efficiency.
Implementation Method 1
The preparation of a polyol is generally conducted by the polymerization of one or more hydrocarbon epoxides in the presence of a polymerizing initiator and an alkaline catalyst such as KOH
Implementation Method 2
A DMC catalyst is conventionally prepared from a mixture of a metal salt, a metal cyanide salt and a complexing agent, and it can be represented by Ma[M′(CN)6]b LcL′d, wherein M and M′ are metal elements; L and L′ are complexing agents
Implementation Method 3
the highly active DMC catalyst is excessively reactive, which makes it difficult to control the reaction temperature because it induces a sudden exothermic reaction
Data Source
AI summary
A double metal cyanide catalyst of the present invention having a controlled reactivity for preparing a polyol, which contains an ether ligand having a molecular weight of less than 200 and a glycol ligand having a molecular weight of less than 200 can be used in the preparation of a polyol having a unsaturation degree suitable for direct use for producing a polyurethane having suitable properties.