Non-polymeric Coatings Using Urea Crystals for Sag Control
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Solution Overview
Problem
Coatings with carbamate-functional resins require high organic solvent content to achieve acceptable viscosity, leading to increased regulated emissions and sagging issues during application and curing, which are not effectively addressed by existing sag control agents.
Innovation Solution
A thermosetting, non-polymeric coating composition incorporating monomeric materials with active hydrogen groups, a crystalline reaction product of a primary monoamine and a polyisocyanate, and a crosslinker, formulated to reduce volatile organic compounds and prevent sagging, while maintaining superior coating properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbamate-functional resins are used to achieve superior coating properties, then coating performance is improved, but organic solvent content must be increased to achieve acceptable viscosity
Solution Approach 1:
The patent changes the molecular weight parameter of the carbamate-functional resin from low molecular weight to high molecular weight, which inherently increases viscosity. This parameter change allows the formulation to use less organic solvent while maintaining acceptable coating viscosity and achieving the desired coating performance.
Solution Approach 2:
The patent creates a composite coating formulation by combining high molecular weight carbamate-functional resin with specific crosslinking agents and optional rheology control agents. This composite approach allows the system to achieve both high performance and reduced solvent content through synergistic interactions between components.
2Object-generated harmful factors
If very low molecular weight polymeric or oligomeric materials are used to reduce VOC content, then volatile organic compounds are reduced, but sagging occurs during initial stages of baking
Solution Approach 1:
The patent changes the molecular weight parameter from very low to high, which fundamentally alters the rheological behavior of the resin. High molecular weight carbamate-functional resins maintain adequate viscosity and sag resistance during baking while still allowing for reduced VOC formulations.
Solution Approach 2:
The patent introduces crosslinking agents as intermediaries that react with the carbamate-functional resin to form a crosslinked network. This crosslinked structure provides sag resistance during baking, enabling the use of high molecular weight resins with reduced solvent content without sacrificing stability.
3Stability of the object's composition
If rheology control agents are added to control sagging, then sag resistance is improved, but viscosity of the coating composition significantly increases
Solution Approach 1:
The patent uses high molecular weight carbamate-functional resin, which provides inherent sag resistance without requiring excessive amounts of rheology control agents. The resin's molecular weight itself acts as a partial rheology modifier, reducing the need for additional viscous additives.
Solution Approach 2:
The patent employs crosslinking agents as intermediaries that provide structural support and sag resistance through chemical crosslinking, rather than relying solely on physical thickening from rheology control agents. This approach controls sagging through chemical network formation rather than excessive viscosity increase.
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 achieves a clearcoat composition with lower organic solvent content that is resistant to sagging, providing improved appearance and performance without the drawbacks of high solvent use or sagging issues.
Implementation Method 1
a sag control agent that is a crystalline reaction product of a primary monoamine and a polyisocyanate
Implementation Method 2
at least one crosslinker reactive with the at least one monomeric material
Data Source
AI summary
The thermosetting, non-polymeric coating composition includes at least one monomeric material having a plurality of carbamate and/or urea groups, at least one crosslinker reactive with the at least one monomeric material, and a sag control agent that is a crystalline reaction product of an amine and an isocyanate.