Polyurea Rheology Control Agents for Coatings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rheology control agents for liquid coating systems are not storage-stable, are tied to the medium they are intended to thicken, have limited shear stability, and are temperature-dependent, leading to issues like clouding, haze, and sagging in coatings.
Innovation Solution
Development of polyureas with a specific molecular structure and weight-average molecular weight range (5000 to 70000 g/mol) that are fully reacted, easy to process, and can be added independently to formulations, providing strong rheological activity and stability across varying temperatures and polarities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dry solid rheology control agents (organically modified bentonites, silicas, hydrogenated castor oil, polyamide waxes) are used, then rheology control is achieved, but processing complexity increases and dust formation occurs
Solution Approach 1:
The invention changes the physical state parameter from solid to liquid by providing rheology control agents in solution form. This eliminates the need for complex processing steps like shearing, temperature control, and prevents dust formation during handling and application
Solution Approach 2:
The invention uses solvents as intermediaries to dissolve the rheology control agents, creating liquid solutions that are easier to handle and apply. The solvent acts as a carrier that simplifies processing while maintaining the rheology control function
2Reliability
If isocyanate and amine are reacted in the presence of film-forming resin to form urea, then sag control is achieved, but storage stability deteriorates and lumps form
Solution Approach 1:
The invention performs the reaction between isocyanate and amine components in advance to pre-form the urea rheology control agent in solution. This preliminary action allows the product to be stored ready-to-use without requiring on-site mixing, thereby improving storage stability while maintaining sag control properties
Solution Approach 2:
The pre-formed solution is self-stable and can be stored without special conditions or immediate use. The system serves itself by maintaining stability during storage, eliminating the need for complex handling procedures or immediate processing after preparation
3Reliability
If polyisocyanates or polyisocyanurates are reacted with monoamines or polyamines to form polyureas, then rheology control is achieved, but the process requires mandatory presence of binder increasing complexity
Solution Approach 1:
The invention extracts the binder requirement from the rheology control agent preparation process. The polyurea rheology control agent can now be prepared and supplied independently without mandatorily requiring the presence of binder, simplifying the overall formulation process while maintaining effective rheology control
4Reliability
If pre-gel is used to prepare thixotroped media, then thickening is achieved, but processing time window decreases and immediate processing is required
Solution Approach 1:
The invention replaces the short-lived pre-gel system with a stable liquid solution that maintains its rheology control properties over extended periods. This eliminates the urgency for immediate processing after preparation, providing a longer processing time window while maintaining effective thickening
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 polyureas enhance storage and shear stability, reduce sagging, and offer broad compatibility, allowing for effective rheology control in high-build systems and baking operations, while being easy to incorporate and process without forming dust or crystallites.
Implementation Method 1
The weight-average molecular weight of the polyureas is 5000 to 70000 g/mol, which provides optimal rheological activity through molecular chain entanglement
Implementation Method 2
The polyureas exhibit strong rheological activity due to hydrogen bonding and dipole-dipole interactions between urea groups
Implementation Method 3
The polyureas form a weak gel network structure in the liquid coating system, which provides sag resistance and improves storage stability without complete gelation
Data Source
AI summary
The invention relates to polyureas having a weight-average molecular weight ranging from 5,000 to 70,000 g/mol, the preparation thereof, and the use thereof as rheology control agents. The invention further relates to rheology control agents containing polyureas and to the use thereof. The invention moreover relates to formulations containing polyureas.