Polyurethane-Polyurea Dispersions with Side Chains
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Solution Overview
Problem
The production of aqueous polyurethane-polyurea dispersions with incorporated side chains is complex, expensive, and involves hazardous reagents like alkylene oxides and azides, making it difficult to handle and scale up industrially.
Innovation Solution
Reacting primary and/or secondary monoamines or diamines with cyclic carbonates, followed by reaction with polyisocyanates and other isocyanate-reactive compounds, to form polyurethane-polyurea prepolymers that can be dispersed in water and extended with isocyanate-reactive polyamines, allowing for the incorporation of side chains in a simple and cost-effective manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyethers with two free hydroxyl groups and long polyalkylene side chains are used for steric stabilization, then stabilization effectiveness is improved, but production complexity and cost increase significantly
Solution Approach 1:
The patent uses dimethylolpropionic acid (DMPA) as an intermediary substance to introduce side chains into the polyurethane structure. Instead of directly incorporating complex polyethers with multiple hydroxyl groups, DMPA serves as a simpler mediator that provides the necessary steric stabilization through its carboxylate groups while being easier to handle and process during production.
Solution Approach 2:
The invention changes the chemical parameters of the side chain introduction process by using compounds with exactly one hydroxyl group (like glycol carbonates) instead of traditional multifunctional alcohols. This parameter change simplifies the reaction stoichiometry and reduces production complexity while maintaining the essential steric stabilization function.
2Ease of manufacture
If alkylene oxides are used to introduce side chains, then side chain incorporation is achieved, but handling difficulty and safety risks increase due to high reactivity
Solution Approach 1:
The patent replaces hazardous, long-lived reactive reagents like alkylene oxides with safer, shorter-lived alternatives such as glycol carbonates. These alternative reagents can be used and consumed in the reaction without posing long-term handling risks, effectively substituting dangerous materials with safer temporary substitutes.
Solution Approach 2:
The invention converts the potential harm of using highly reactive reagents into a benefit by selecting reagents that are sufficiently reactive to achieve side chain incorporation but not so reactive as to pose handling dangers. The moderate reactivity of glycol carbonates provides the necessary chemical transformation while eliminating safety concerns associated with more aggressive reagents.
3Adaptability or versatility
If azides are used for click chemistry to introduce functionalities, then diverse side chain functionalities are achieved, but production safety and handling difficulty worsen
Solution Approach 1:
The patent extracts the hazardous azide functionality from the reaction system and replaces it with safer alternative reagents that achieve the same functional diversity goal. By removing the dangerous azide component while maintaining the ability to introduce various side chain functionalities through glycol carbonate-based chemistry, the invention eliminates safety risks while preserving adaptability.
4Reliability
If traditional multi-stage processes are used for producing aqueous dispersions with side chains, then product performance is achieved, but production time and cost increase
Solution Approach 1:
The patent merges multiple traditional production stages into a simplified process by using glycol carbonates that can be directly incorporated during the main polyurethane synthesis. This consolidation eliminates separate side chain introduction steps and reduces the number of processing stages while maintaining product performance, thereby improving overall production efficiency.
Solution Approach 2:
The invention performs the side chain incorporation action preliminarily during the initial polyurethane prepolymer formation stage, rather than requiring subsequent separate processing steps. By integrating the side chain introduction into the main synthesis reaction, the process achieves both product performance and production efficiency simultaneously.
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 method enables the production of polyurethane-polyurea dispersions with side chains in a straightforward and inexpensive process, reducing the complexity and cost associated with existing methods and avoiding the handling challenges of hazardous reagents.
Implementation Method 1
H. Tomita et al. Journal of Polymer Science Part A: Polymer Chemistry 2001 (39), pages 162-168 that amines react with cyclic carbonates in an addition reaction with ring opening to give hydroxyurethanes.
Implementation Method 2
In addition to the electrostatic stabilization by carboxylate groups, aqueous polyurethane dispersions are also produced by nonionic, hydrophilic, sterically stabilizing groups.
Implementation Method 3
aqueous polyurethane dispersions are also produced by nonionic, hydrophilic, sterically stabilizing groups. Achieving this steric stabilization of polyurethane dispersions therefore requires long, hydrophilic side chains
Implementation Method 4
subsequently an NCO-containing polyurethane prepolymer by reacting B1) polyisocyanates with B2) polymeric polyols and/or polyamines
Data Source
AI summary
The present invention relates to a process for the production of aqueous polyurethane-polyurea dispersions for which A) firstly A1) primary and/or secondary monoamines or diamines are reacted with A2) cyclic carbonates which contain precisely one hydroxy group, where the molar ratio of A1) and A2) is such that in the case of monoamines A1) the theoretical ratio of the entirety of the primary and secondary amine groups to the cyclic carbonate groups is from 0.8 to 1.2 and in the case of diamines A1) the theoretical ratio of the entirety of the primary and secondary amine groups to the cyclic carbonate groups is from 1.8 to 2.2, and A3) in the case of diamines A1) the remaining primary and secondary amine groups are reacted with compounds which bear precisely one functional group which reacts with primary or secondary amines in an addition reaction, in such a way that there are no resultant isocyanate-reactive groups, where the molar amount of A3) is such that the theoretical ratio of the entirety of the theoretically remaining primary and secondary amine groups after reaction of A1) and A2) to the amine-reactive groups in A3) is from 0.8 to 1.2, where the reaction with A3) can take place after, at the same time as or prior to the reaction with A2), B) then a polyurethane prepolymer containing NCO groups is produced by reaction of B1) polyisocyanates with B2) polymeric polyols and/or polyamines with number-average molar masses of more than 400 to 8000 g/mol and B3) optionally low-molecular-weight compounds with number-average molar masses of 17-400 g/mol selected from the group consisting of mono- and polyalcohols, mono- and polyamines and aminoalcohols and B4) optionally isocyanate-reactive, ionically or potentially ionically hydrophilizing compounds and/or isocyanate-reactive non-ionically hydrophilizing compounds and B5) the reaction products of A), C) the prepolymer from B) is dispersed in water, and D) optionally the remaining free NCO groups of the prepolymer are reacted with isocyanate-reactive monoamines, polyamines, hydrazine and/or hydrazides, where the molar amount of these is such that the theoretical ratio of the isocyanate-reactive NH groups to the NCO groups is from 0 to 1.2, where the reaction D) can take place to some extent or else entirely prior to or during the dispersion step C).