Polyurethane Dispersion Stability via Urea Ratio Control
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Solution Overview
Problem
High solid content concentrations of polyurethane resin in aqueous dispersions lead to increased urethane and urea group concentrations, causing stability issues due to aggregation and reduced water dispersion stability.
Innovation Solution
A polyurethane dispersion with a controlled ratio of urethane and urea groups and a low carbonate ion concentration, achieved by using a specific reaction product of polyisocyanate and active hydrogen compounds, and adjusting the chain extension reaction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the solid content concentration of the polyurethane resin is increased to above 20% by mass for production efficiency and cost reduction, then the production efficiency and transportation cost are improved, but the water dispersion stability is lowered due to high concentration of urethane and urea groups causing aggregation
Solution Approach 1:
The patent changes the chemical composition parameters of the polyurethane resin by controlling the ratio of urethane groups to urea groups to be 1.5 or more. This parameter adjustment allows the resin to maintain high solid content concentration (above 20% by mass) while preventing aggregation and maintaining water dispersion stability, thus resolving the contradiction between productivity and stability.
2Loss of substance
If the solid content concentration of the polyurethane resin is increased to above 20% by mass, then the transportation cost is reduced, but the storage stability is lowered due to aggregation of polyurethane resin
Solution Approach 1:
The patent adjusts the chemical structure parameters of the polyurethane resin by ensuring the urethane group to urea group ratio is 1.5 or more. This parameter change enables the resin to be formulated at high solid content concentration (above 20% by mass) without suffering from aggregation during storage, thereby reducing transportation cost while maintaining storage stability.
3Strength
If the concentration of urethane and urea groups is increased for high solid content, then the cohesive force of polyurethane resin is improved, but the mechanical stability is lowered due to aggregation
Solution Approach 1:
The patent optimizes the chemical composition by controlling the urethane group to urea group ratio to be 1.5 or more. This parameter adjustment allows the polyurethane resin to achieve high cohesive force through increased concentration of functional groups while preventing aggregation, thus maintaining mechanical stability during machine application.
Data Source
AI summary
In a polyurethane dispersion obtained by water-dispersing a polyurethane resin, the polyurethane resin is a reaction product obtained by reacting at least a polyisocyanate component with an active hydrogen group-containing component containing an active hydrogen compound having an anionic group, a ratio of the total moles of a urethane group and a urea group is 1.5 mol or more with respect to 1 kg of the polyurethane dispersion, and the carbonate ion concentration is 700 ppm or less with respect to the polyurethane dispersion.