Urea Urethane Thixotropic Additive for Casting Resins
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Solution Overview
Problem
Current thixotropy-increasing additives for casting resins and coatings, especially when combined with amorphous silica, face issues such as settling, partial destruction of networks under mechanical loads, and adverse effects like matting or reduced strength, particularly in systems with high viscosity or epoxy resin-based binders.
Innovation Solution
The use of urea urethanes as thixotropy-increasing additives, formed by reacting monohydroxyl compounds and diisocyanate compounds with diamine compounds, which can be combined with amorphous silica to strengthen the silica network and prevent settling, while maintaining stability under mechanical loads and temperature increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of thixotropic agent (e.g., amorphous silica) is increased to maintain thixotropic effect under mechanical load, then the thixotropic effect is improved, but unwanted matting effects occur in lustrously formulated coating systems and strength is reduced in resin systems
Solution Approach 1:
The patent changes the chemical parameters of the thixotropic agent by introducing a silane-modified amorphous silica where the silica surface is grafted with organosilane groups. This chemical modification allows the silica to maintain thixotropic effect at lower concentrations while avoiding the harmful matting effects and strength reduction associated with high concentrations of unmodified silica
Solution Approach 2:
The patent creates a composite thixotropic agent by combining amorphous silica with organosilane modifiers. This composite structure integrates the thixotropic properties of silica with the surface-active properties of organosilanes, enabling the material to provide adequate thixotropic effect at lower concentrations without causing matting or strength reduction
2Reliability
If the amount of thixotropic agent is increased to ensure maintenance of three-dimensional network under mechanical load, then the thixotropic effect is maintained, but the system becomes unsuitable for applications requiring high viscosity stability
Solution Approach 1:
The patent modifies the chemical parameters of the thixotropic agent by introducing silane groups that form stronger chemical bonds. This allows the network to maintain thixotropic effect under mechanical load at lower concentrations, making the system suitable for a broader range of applications including those requiring high viscosity stability
3Stability of the object's composition
If thixotropic agent is added to prevent settling, then settling is prevented, but the concentration required leads to disruptions in technical applications
Solution Approach 1:
The patent changes the surface chemical parameters of the thixotropic agent by grafting organosilane groups onto the silica surface. This modification enhances the compatibility and dispersion of silica particles, allowing prevention of settling at lower concentrations that do not disrupt technical applications
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
Urea urethanes enhance the thixotropic effect, reduce the need for higher concentrations of thixotropic agents, prevent settling, and improve mechanical stability and binding power, allowing for thicker coatings without sagging or running, even under high mechanical stress.
Implementation Method 1
hydrogen bonds may be formed between the individual silica molecules. This produces a three-dimensional network
Implementation Method 2
This time-dependent and reversible process is generally referred to as thixotropy
Implementation Method 3
there may be adsorption of the added curing component to the thixotropic agent
Data Source
AI summary
Suggested is a method for modifying the rheology of a casting resin and/or coating composition, comprising the following steps: providing a composition comprising at least one monomer capable of forming a casting resin or coating upon polymerisation; and adding to said composition a working amount of a urea urethane obtained under specific conditions as a thixotropic agent.