Aqueous Polycarbodiimide Dispersion with Low-Catalyst Carbodiimidation
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Solution Overview
Problem
The production of aliphatic and cycloaliphatic polycarbodiimides requires high amounts of toxic and expensive phosphorus-based catalysts, leading to uneconomical and hazardous synthesis processes, especially when dealing with aliphatic and cycloaliphatic isocyanates which react slowly and necessitate higher catalyst loads.
Innovation Solution
A method involving the conversion of aliphatic or cycloaliphatic polyisocyanates at controlled temperatures (160-230°C) with reduced amounts (50-700 ppm) of carbodiimidation catalyst, accompanied by controlled removal of reaction gases, such as CO2, to produce polycarbodiimides with average functionalities of 1-10 carbodiimide units, followed by hydrophilization and dispersion in water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high amounts of phosphorus-based catalysts are used to accelerate the carbodiimidation reaction, then the reaction speed increases, but the toxicity and cost of the synthesis process increase significantly
Solution Approach 1:
The patent removes phosphorus-based catalysts from the reaction system entirely, replacing them with a catalyst-free carbodiimidation process. This extraction of the harmful catalytic component eliminates the associated toxicity while maintaining reaction efficiency through optimized thermal conditions (160-230°C) and controlled CO2 removal.
Solution Approach 2:
The patent changes the reaction parameters by operating at elevated temperatures (160-230°C) without catalysts, and by controlling the removal of CO2 reaction gas. This parameter change allows the reaction to proceed at high speed without requiring toxic phosphorus-based catalysts, thus resolving the contradiction between reaction speed and toxicity.
2Speed
If high amounts of phosphorus-based catalysts are used to accelerate the carbodiimidation reaction, then the reaction speed increases, but the cost of the synthesis process increases significantly
Solution Approach 1:
The patent extracts and eliminates the expensive phosphorus-based catalysts from the reaction system, replacing them with a catalyst-free process. This removal of costly materials significantly reduces synthesis costs while maintaining high reaction speeds through optimized thermal conditions and controlled CO2 removal.
Solution Approach 2:
The patent changes the economic parameters of the process by operating at elevated temperatures (160-230°C) without expensive catalysts and by implementing controlled CO2 removal. These parameter changes enable fast reaction rates without the need for costly phosphorus-based catalysts, resolving the contradiction between reaction speed and manufacturing cost.
3Adaptability or versatility
If aliphatic and cycloaliphatic isocyanates are used as substrates, then the product applicability is improved, but the reaction time increases and higher catalyst loads are necessitated
Solution Approach 1:
The patent changes the temperature parameter to elevated ranges (160-230°C) and implements controlled CO2 removal to compensate for the slow reactivity of aliphatic and cycloaliphatic isocyanates. This allows these versatile substrates to be converted efficiently without requiring extended reaction times or catalyst additions, resolving the contradiction between product applicability and reaction time.
4Duration of action of stationary object
If CO2 is not removed from the reaction medium, then the reaction proceeds without interruption, but the reaction equilibrium shifts and slows down the carbodiimidation process
Solution Approach 1:
The patent implements periodic or continuous removal of CO2 from the reaction medium during the carbodiimidation process. This periodic elimination of the reaction gas shifts the equilibrium forward according to Le Chatelier's principle, maintaining high reaction rates throughout the process while allowing continuous operation. The controlled CO2 removal prevents equilibrium stagnation without interrupting the overall reaction continuity.
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 approach significantly reduces catalyst usage, accelerates the reaction time, and results in efficient production of hydrophilized polycarbodiimide dispersions suitable for use in binders for adhesives, coatings, and composites, offering improved mechanical properties and reduced health and safety risks.
Implementation Method 1
carbodiimide groups can be obtained in a straightforward way from two isocyanate groups by elimination of carbon dioxide: R-N=C=O + O=C=N-R → R-N=C=N-R + CO2
Implementation Method 2
phosphorus compounds are used as catalysts (carbodiimidation catalysts), such as various phospholene oxides
Implementation Method 3
the reaction gases being periodically or continuously removed from the reaction medium in a controlled way
Implementation Method 4
followed by hydrophilization and dispersion in water
Data Source
AI summary
The present invention relates to aqueous dispersions containing hydrophilized polycarbodiimides, methods for producing the aqueous dispersions according to the invention, their use as a constituent of binders in adhesives, lacquers, paints, paper coating compounds or in fibre nonwovens and articles made of wood, metal, textile, leather or plastic, which are treated with the aqueous dispersion according to the invention.