Polyurethane System with Alkali Metal Catalyst for Open Time and Cure Trade-off
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Solution Overview
Problem
Current polyurethane systems for producing fiber composites with large surface areas require a balance between long open time and rapid curing, which is difficult to achieve with existing acid-blocked catalysts, resulting in either insufficient processing life or excessively long cure times.
Innovation Solution
A polyurethane system comprising polyisocyanate, a mixture of alkali metal or alkaline earth metal salt with urethane groups, and optional epoxide groups, polyol, and chain extenders, where the alkali metal or alkaline earth metal ions are present in a specific concentration, allowing for extended open time and rapid curing by using monodentate urethane groups for enhanced catalytic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If acid-blocked catalysts are used to extend open time, then processing life is extended, but curing time becomes excessively long
Solution Approach 1:
The invention changes the chemical structure of the catalyst from conventional acid-blocked amines to metal halide complexes with urea or biuret groups. This parameter change in catalyst chemistry enables simultaneous achievement of long open time at room temperature and rapid curing at elevated temperatures, resolving the time trade-off contradiction
Solution Approach 2:
The catalyst system combines metal halide salts (LiCl, NaCl, KCl, etc.) with organic compounds containing urea or biuret groups to form composite catalytic systems. This composite approach integrates the benefits of both inorganic metal ions and organic functional groups, achieving enhanced catalytic efficiency with extended open time and rapid cure capability
2Duration of action of moving object
If urea, carboxylate or biuret blocked catalysts are used, then open time is extended, but material brittleness increases
Solution Approach 1:
The invention changes the catalyst type from organic blocked catalysts to inorganic metal halide complexes, altering the chemical parameters of the catalytic system. This change maintains long open time while producing more ductile and less brittle polyurethane materials
Solution Approach 2:
The invention copies the beneficial catalytic effect of metal halides known from epoxy systems and applies it to polyurethane systems with urea/biuret groups, achieving similar open time extension without the brittleness problem
3Reliability
If large quantities of blocked catalysts are added, then catalytic activity is sufficient, but material brittleness increases and efficiency decreases
Solution Approach 1:
The invention changes the catalyst chemistry to metal halide complexes which exhibit higher catalytic activity per unit mass. This parameter change allows achieving sufficient catalytic activity with much smaller quantities (0.01-5 wt%) compared to conventional blocked catalysts, reducing material brittleness and improving efficiency
Solution Approach 2:
The invention merges the catalytic functions of metal halides with the open time extension capability of urea/biuret groups in a single integrated catalyst system, achieving multiple benefits simultaneously with minimal catalyst loading
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 system achieves a significantly longer open time at room temperature while curing rapidly at elevated temperatures, improving processing efficiency and mechanical properties of the polyurethane, allowing for the production of a wide range of mechanical properties in polyurethane systems.
Implementation Method 1
a polyurethane system comprising a) polyisocyanate, b) a mixture obtainable by introducing an alkali metal or alkaline earth metal salt into a compound comprising urethane groups... where the amount of alkali metal or alkaline earth metal ions per urethane group in the compound (b) is 0.0001 to 1
Data Source
AI summary
The present invention relates to a process for preparing polyurethanes by mixing a) polyisocyanate, b) a mixture obtainable by introducing an alkali metal or alkaline earth metal salt into a compound comprising urethane groups, c) compounds comprising one or more epoxide groups, and, optionally, d) polyol, e) chain extenders, and f) fillers and further additives to form a reaction mixture and fully reacting the mixture to give the polyurethane, where the amount of alkali metal or alkaline earth metal ions per equivalent urethane groups in the compound (b) is 0.0001 to 3.5. The present invention further relates to a polyurethane obtainable by such a process, and to the use of such a polyurethane for producing bodywork components for vehicles.