Polyether Polyol Storage Stability via Double Metal Cyanide Catalyst Activation
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Solution Overview
Problem
Flexible polyurethane foams produced using polyether polyols with double metal cyanide complex catalysts experience a deterioration in mechanical properties over time, particularly when the polyol system solution is stored for extended periods, leading to decreased tear strength, tensile strength, and elongation.
Innovation Solution
A process involving ring-opening addition polymerization of propylene oxide and ethylene oxide in the presence of a double metal cyanide complex catalyst, followed by an initial activation step and additional polymerization, to produce a polyether polyol with controlled hydroxy groups and low degree of unsaturation, which is then used to produce flexible polyurethane foam with improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyether polyol is produced using a double metal cyanide complex catalyst to achieve low degree of unsaturation, then the mechanical properties of the foam are improved, but the foam physical properties deteriorate when the polyol system solution is stored for extended periods
Solution Approach 1:
The patent applies preliminary action by conducting an initial activation step before the main polymerization reaction. The reaction mixture is heated to 120-165°C and held for 0.5-2 hours to activate the double metal cyanide complex catalyst before adding propylene oxide. This preliminary activation ensures the catalyst is fully prepared, preventing degradation during storage and maintaining both mechanical properties and foam physical properties stability.
Solution Approach 2:
The patent applies parameter changes by optimizing the initial temperature (120-165°C) and holding time (0.5-2 hours) of the activation step, as well as controlling the amount of propylene oxide added in the initial step (5-20 mass% relative to initiator). These parameter optimizations ensure complete catalyst activation while maintaining product stability during storage, resolving the contradiction between mechanical properties and storage stability.
2Productivity
If the polyol system solution is stored for extended periods to allow for production scheduling, then manufacturing flexibility is improved, but the mechanical properties of the resulting foam decrease
Solution Approach 1:
The patent performs preliminary activation of the catalyst system before polymerization, creating a stable intermediate state that can be stored. The activated catalyst complex remains stable during storage, allowing the polyol system solution to be stored for extended periods without degradation, thus maintaining mechanical properties while providing manufacturing flexibility.
Solution Approach 2:
The patent uses the activated catalyst complex as an intermediary state between catalyst preparation and final polymerization. This intermediate activated complex is stable during storage, acting as a mediator that preserves mechanical properties while enabling time delays in production scheduling.
3Ease of manufacture
If an alkali catalyst is used to produce polyether polyol, then the production process is simple, but monool with unsaturated bonds forms as a by-product deteriorating foam physical properties
Solution Approach 1:
The patent changes the catalyst type from alkali catalyst to double metal cyanide complex catalyst, and changes the reaction conditions by adding an initial activation step with specific temperature (120-165°C) and time (0.5-2 hours). This parameter change eliminates monool by-product formation while maintaining production feasibility, resolving the contradiction between manufacturing simplicity and product quality.
Solution Approach 2:
The double metal cyanide complex catalyst acts as an intermediary that enables selective polymerization without forming monool by-products. The catalyst's unique structure mediates the reaction to proceed through a pathway that avoids unsaturated bond formation, eliminating the harmful by-product while keeping the process manageable.
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 process effectively suppresses the decrease in mechanical properties of flexible polyurethane foam when using a stored polyol system solution, resulting in a foam suitable for applications like automobile seat cushions with enhanced hardness and durability.
Implementation Method 1
a step of subjecting propylene oxide to ring-opening addition polymerization to a polyhydric alcohol initiator in the presence of a double metal cyanide complex catalyst to produce an intermediate polyol
Implementation Method 2
a step of subjecting ethylene oxide to ring-opening addition polymerization in an amount of from 1 to 23 mol per 1 mol of the initiator to the intermediate polyol in the presence of an alkali metal hydroxide to produce a polyether polyol
Implementation Method 3
a step of subjecting propylene oxide to ring-opening addition polymerization to a polyhydric alcohol initiator
Data Source
AI summary
To suppress deterioration of mechanical properties of a foam, by using a polyol system solution stored. A polyol system solution is prepared by using a polyether polyol (A1) having a hydroxy value of from 5 to 45 mgKOH/g and an average number of hydroxy groups of from 2 to 8, obtainable by subjecting an alkylene oxide to ring-opening addition polymerization to an initiator, in the presence of a double metal cyanide complex catalyst, to obtain an intermediate polyol; and subjecting ethylene oxide to a ring-opening addition polymerization in an amount of from 1 to 23 mol per 1 mol of the initiator to the intermediate polyol, in the presence of an alkali metal hydroxide as a polymerization catalyst, and a flexible polyurethane foam is produced by using the polyol system solution.