Tertiary Amine Hydrophobe for pH-Stable Viscosity
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Solution Overview
Problem
Amine-modified hydrophobically modified ethylene oxide urethane polymers (HEURs) are sensitive to pH changes in paint formulations, leading to a decrease in viscosity over time and heat aging, resulting in a poorer formulation performance.
Innovation Solution
A stable aqueous dispersion of hydrophobically modified alkylene oxide urethane polymers with tertiary amine groups, characterized by specific structural units, is developed to maintain viscosity across a wide pH range, incorporating a compound with the formula Ia and prepared by reacting a diisocyanate with a water-soluble polyalkylene glycol and a tertiary amine-modified hydrophobe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If amine-modified HEUR polymers are used to provide pH-triggered viscosity control, then viscosity control through pH trigger is achieved, but the formulation becomes sensitive to pH changes over time and heat aging
Solution Approach 1:
The patent changes the chemical structure of the amine groups from secondary to tertiary amines with specific alkyl substitutions (formula Ia). This structural parameter change modifies the pKa and protonation behavior, making the hydrophobe less sensitive to pH changes over time while maintaining the associative thickening mechanism at high pH.
Solution Approach 2:
The invention creates a composite structure combining the polyalkylene oxide urethane backbone with tertiary amine-containing hydrophobic side chains. This composite architecture integrates the water solubility and polymer chain flexibility of HEUR with the pH-responsive associative thickening of amine-modified hydrophobes, achieving both adaptability and reliability.
2Stability of the object's composition
If the pH of the formulation decreases over time and heat aging, then the basic groups become protonated and viscosity decreases, but this results in poorer formulation performance
Solution Approach 1:
The patent modifies the amine structure to tertiary amines with specific alkyl groups (formula Ia) that have different basicity compared to secondary amines. This parameter change in the chemical structure alters the protonation equilibrium, making the system less sensitive to pH decreases during storage and heat aging, thereby maintaining viscosity stability.
Solution Approach 2:
The invention design anticipates the pH decrease that occurs during storage and heat aging by pre-engineering the hydrophobe structure with tertiary amines that have optimized basicity. This beforehand cushioning through structural design ensures that even when pH decreases, sufficient deprotonated amine groups remain to maintain associative thickening and viscosity.
3Adaptability or versatility
If secondary or tertiary amines are incorporated into HEUR polymers, then associative thickening occurs at high pH, but the polymer becomes sensitive to pH-lowering mechanisms
Solution Approach 1:
The patent changes the amine type from secondary to tertiary with specific alkyl substitutions (formula Ia). This parameter change in the chemical structure modifies the basicity and steric environment, enabling the hydrophobe to maintain associative thickening capability while reducing sensitivity to pH-lowering mechanisms during storage.
Solution Approach 2:
The invention introduces local structural differentiation by using tertiary amines with specific alkyl groups (formula Ia) at the hydrophobic side chain positions, while maintaining the polyalkylene oxide urethane backbone structure. This local quality change in the amine groups provides the desired balance between associative thickening and pH 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 solution effectively preserves the desired viscosity of paint formulations during pH-lowering mechanisms, demonstrating improved heat age stability with minimal viscosity drop compared to conventional rheology modifiers.
Implementation Method 1
when the pH is sufficiently high, associative thickening occurs. Thus, incorporation of basic hydrophobes into the HEUR polymer allows relatively high concentration of polymer to be dissolved in water at low pH; once the solution is added to the high pH environment of paint coatings, the base is deprotonated and the associative thickening mechanism activated
Implementation Method 2
when the pH is sufficiently high, associative thickening occurs
Implementation Method 3
hydrophobically modified alkylene oxide urethane polymers with hydrophobic side chains that contain tertiary amines
Data Source
AI summary
The present invention relates to a compound characterized by the following formula: where R1, R2, Y, m, and p are described herein. The compound of the present invention is useful as a precursor to hydrophobically modified alkylene oxide urethane polymers, which are useful as rheology modifiers for coatings formulations.