Cyclic Urea-Aldehyde Crosslinker for Low-Temperature Coatings
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Solution Overview
Problem
Existing crosslinkers based on amino resins, such as those derived from formaldehyde and melamine, suffer from formaldehyde emission and require high temperatures for curing, which is energy-intensive and environmentally undesirable, while crosslinkers from cyclic ureas and multifunctional aldehydes face challenges in controlling the composition and achieving satisfactory appearance and performance in coatings.
Innovation Solution
The development of at least partially etherified reaction products of cyclic ureas and multifunctional aldehydes, which can be used as crosslinkers for hydroxyl and/or acid-functional binder resins, allowing for curing at ambient temperatures without formaldehyde emission and providing improved properties like higher hardness, chemical resistance, and lower yellowness in coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amino resins (formaldehyde and melamine) are used as crosslinkers, then good crosslinking performance is achieved, but formaldehyde emission occurs and high curing temperatures are required
Solution Approach 1:
The patent extracts and eliminates the harmful formaldehyde component from the crosslinking system by replacing amino resins with cyclic urea-aldehyde reaction products that do not contain formaldehyde, thereby maintaining crosslinking performance while removing the harmful emission
Solution Approach 2:
The patent changes the chemical composition parameters of the crosslinker from formaldehyde-based amino resins to cyclic urea-aldehyde adducts, fundamentally altering the chemical structure to eliminate formaldehyde emission while preserving crosslinking functionality
2Reliability
If amino resins are used as crosslinkers, then effective crosslinking is achieved, but high curing temperatures (at least 80°C) are required which increases energy consumption
Solution Approach 1:
The patent modifies the chemical parameters of the crosslinking system by using cyclic urea-aldehyde adducts with different reactivity characteristics, enabling the crosslinking reaction to proceed effectively at ambient temperatures without requiring thermal activation
Solution Approach 2:
The crosslinking system performs self-service at ambient temperature through the inherent reactivity of the cyclic urea-aldehyde adducts with active hydrogen-containing groups, eliminating the need for external energy input in the form of heating
3Temperature
If reaction products of cyclic ureas and multifunctional aldehydes are used as crosslinkers, then ambient temperature curing is enabled, but the composition is difficult to control leading to inconsistent coating quality
Solution Approach 1:
The patent applies preliminary action by pre-forming cyclic urea-aldehyde adducts with controlled structures before use as crosslinkers, ensuring consistent composition and predictable performance in coating applications
Solution Approach 2:
The patent controls the molecular weight and structural parameters of the cyclic urea-aldehyde adducts through systematic variation of reaction conditions and selection of specific cyclic ureas and aldehydes, achieving consistent composition and coating quality
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 partially etherified reaction products of cyclic ureas and multifunctional aldehydes enable the formation of coatings with enhanced hardness, chemical resistance, and gloss, while avoiding the drawbacks of traditional amino resin crosslinkers by allowing ambient temperature curing and reducing environmental impact.
Implementation Method 1
at least partially etherified reaction products UA of cyclic ureas U and multifunctional aldehydes A... which are produced by an addition reaction of an aldehyde to a cyclic urea
Implementation Method 2
Such crosslinking may be caused by chemical reaction of low molar mass molecules, oligomers or macromolecules between themselves, such as addition or condensation reactions
Data Source
AI summary
The invention relates to a reaction product UA of at least one cyclic urea U and at least one multifunctional aldehyde A which reaction product has as substituents on the carbonyl carbon atoms of the aldehyde A at least one kind of functional groups selected from the group consisting of hydroxyl groups —OH and alkoxy groups —OR characterised in that the groups —OR comprise at least two kinds of alkoxy groups —OR1 and —OR2, where R1 and R2 are both selected from the group consisting of linear, branched or cyclic alkyl groups having from one to twelve carbon atoms, where R1 and R2 may be the same or may be different from each other, to a process of making these, and to a method of use as crosslinker in coating compositions.