Waterborne Coating Composition with Alkylated Melamine Crosslinking
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Solution Overview
Problem
Waterborne coating compositions face limitations in storage, processing, and handling, and traditional solvent-borne coatings emit volatile organic compounds (VOCs) contributing to air pollution, necessitating a low foaming, high-gloss, and high-hardness coating solution.
Innovation Solution
A waterborne coating composition is developed using a crosslinkable component with 20-80% water and a crosslinking component comprising alkylated melamines unreactive to polyisocyanates, mixed without acid catalysts, and cured at 80-200°C to form a hard, glossy layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If waterborne coating compositions are used to reduce VOC emissions, then environmental friendliness is improved, but foam formation and gassing resistance deteriorate
Solution Approach 1:
The patent changes the chemical parameters of the coating system by using alkylated melamines with specific reactivity characteristics and adjusting the water content to 20-80% in the crosslinkable component. These parameter changes enable the formulation of waterborne coatings that maintain gassing resistance while reducing VOC emissions.
Solution Approach 2:
The patent employs a composite crosslinking system combining alkylated melamines and polyisocyanates. This composite approach creates a synergistic effect where the melamine provides structural framework and the isocyanate forms crosslinks, achieving both low foam formation and high gassing resistance in waterborne coatings.
2Object-affected harmful factors
If waterborne coating compositions are used to reduce VOC emissions, then environmental friendliness is improved, but coating gloss and hardness deteriorate
Solution Approach 1:
The patent achieves high gloss in waterborne coatings by optimizing the water content parameter (20-80%) and selecting specific alkylated melamine compounds. These parameter changes allow the coating to form a smooth, reflective surface despite the presence of water, which typically compromises gloss.
Solution Approach 2:
The composite crosslinking system of alkylated melamines and polyisocyanates creates a dense, uniform coating matrix that enhances light reflection. This composite approach maintains high gloss by ensuring uniform crosslinking and smooth surface formation, overcoming the typical gloss reduction associated with waterborne systems.
3Object-affected harmful factors
If waterborne coating compositions are used to reduce VOC emissions, then environmental friendliness is improved, but coating hardness deteriorates
Solution Approach 1:
The patent achieves high hardness in waterborne coatings by changing the crosslinking parameters - specifically using alkylated melamines with controlled reactivity and optimizing the water content to 20-80%. These parameter changes enable the formation of a highly crosslinked, hard coating matrix despite the waterborne nature of the system.
Solution Approach 2:
The composite crosslinking system combining alkylated melamines and polyisocyanates creates a highly crosslinked three-dimensional network. This composite approach significantly enhances coating hardness by forming numerous crosslinks that restrict polymer chain mobility and increase crosslink density, overcoming the typical softness associated with waterborne coatings.
4Illumination intensity
If traditional solvent-borne coatings are used to achieve high gloss and hardness, then coating appearance is improved, but VOC emissions and air pollution deteriorate
Solution Approach 1:
The patent changes the solvent parameter from organic solvents to water, with water content controlled at 20-80% in the crosslinkable component. This parameter change eliminates VOC emissions while maintaining coating gloss through optimized water content and selection of appropriate alkylated melamine compounds.
Solution Approach 2:
The composite crosslinking system of alkylated melamines and polyisocyanates provides a mechanism to achieve high gloss without organic solvents. The crosslinks created by this composite system ensure proper film formation and surface smoothness, maintaining aesthetic appearance while using environmentally friendly waterborne chemistry.
5Object-affected harmful factors
If waterborne coating compositions are used to reduce VOC emissions, then environmental friendliness is improved, but foam formation increases
Solution Approach 1:
The patent reduces foam formation in waterborne coatings by changing the chemical composition parameters - specifically using alkylated melamines with controlled reactivity and optimizing water content to 20-80%. These parameter changes reduce the tendency for foam formation during application and curing while maintaining low VOC emissions.
Solution Approach 2:
The composite crosslinking system of alkylated melamines and polyisocyanates creates a formulation that is less prone to foaming. The specific interaction between these components, combined with the water content optimization, reduces gas entrapment and foam formation during the coating process, addressing a common issue with waterborne systems.
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 results in a coating with improved gloss, distinctness of image, and hardness while minimizing VOC emissions and foam formation, enhancing gassing resistance and coating properties.
Implementation Method 1
one or more polyisocyanates each having two or more free isocyanate crosslinking functional groups
Implementation Method 2
curing said wet coating layer at a temperature in a range of from 80° C. to 200° C. to form said coating layer
Data Source
AI summary
The present disclosure is directed to a waterborne coating composition having neutral pH that is low foaming and forms dry coating layer that has high hardness and high gloss. This disclosure is further directed to a coating composition comprising a crosslinking component comprising: (a) one or more alkylated melamines that are essentially unreactive to a polyisocyanate; and (b) a polyisocyanate. The coating composition can be particularly suitable for vehicle coatings and other industrial or consumer applications.