Polyurethane Synthesis Using Alkoxylated Mannich Bases
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Solution Overview
Problem
The use of metal and amine catalysts in polyurethane production is associated with environmental and health concerns, and they can reduce the shelf life of isocyanate-terminated prepolymers and lead to depolymerization at high temperatures, affecting the material's performance and stability.
Innovation Solution
A method for producing polyurethane without metallic and low molecular weight amine catalysts, using a reaction product of organic polyisocyanate and polyols, including alkoxylated Mannich bases, which allows for a commercially useful curing rate and results in a polymer with high thermal and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal or amine catalysts are used in polyurethane production, then curing rate is improved, but environmental and health concerns increase and shelf life of prepolymers decreases
Solution Approach 1:
The patent removes metal and amine catalysts from the polyurethane production system entirely. Instead of using external catalysts, the invention employs alkoxylated Mannich bases as chain extenders that react with isocyanate groups to provide curing functionality without requiring separate catalysts, thereby eliminating the harmful factors associated with catalysts while maintaining productive curing rates
Solution Approach 2:
The alkoxylated Mannich base serves multiple functions simultaneously: it acts as a chain extender, a curing agent, and replaces the need for separate catalysts. This multi-functional component consolidates several roles into one substance, eliminating the need for harmful catalysts while maintaining efficient curing performance
2Productivity
If metal or amine catalysts are used in polyurethane production, then curing rate is improved, but shelf life of isocyanate-terminated prepolymers decreases
Solution Approach 1:
By removing catalysts from the system, the patent eliminates the primary cause of premature reaction and shelf life reduction. The alkoxylated Mannich base-based system does not require catalysts to proceed at useful rates, thereby preserving the shelf life of isocyanate-terminated prepolymers while maintaining productive curing performance
3Productivity
If metal or amine catalysts are used in polyurethane production, then curing rate is improved, but depolymerization at high temperatures increases
Solution Approach 1:
The patent eliminates catalysts that are known to catalyze depolymerization reactions at elevated temperatures. The alkoxylated Mannich base system provides curing functionality without requiring catalysts, thereby preventing catalyst-induced depolymerization and improving thermal stability while maintaining acceptable curing rates
Solution Approach 2:
The patent converts the potential harm of slow reaction rates (which would occur without catalysts) into a benefit by using alkoxylated Mannich bases that provide both chain extension and curing functionality. This approach eliminates the need for catalysts that cause depolymerization, turning a potential disadvantage into an improvement in thermal stability
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 method eliminates the need for catalysts, reducing costs and environmental concerns, while producing polyurethanes with improved mechanical and thermal stability, even at elevated temperatures, and low void volumes.
Implementation Method 1
The reaction of the alkoxylated Mannich base towards isocyanate groups proceeds at commercially useful rates even in the absence of a metallic and/or amine urethane catalysts
Implementation Method 2
The polyurethane is in many cases a reaction product of an organic polyisocyanate, a hydroxyl-terminated chain extender and a polyether polyol
Data Source
AI summary
Polyurethanes are made by reacting, in one or more reaction steps, a) at least one organic polyisocyanate, b-1) one or more polyols having a hydroxyl equivalent weight of greater than 250 g/mol and a nominal hydroxyl functionality of 2 to 4 and b-2) at least one alkoxylated Mannich base to produce a polyurethane polymer having a density of at least 750 kg/m3 and a hard segment content of 20 to 80% by weight.