Waterborne Polyurethane-Epoxy Primer for Wet-on-Wet Coating
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Solution Overview
Problem
Current waterborne coatings are not suitable for the wet-on-wet process due to slow drying speed, resulting in coating layers with low gloss, poor adhesion, and inadequate mechanical and chemical resistance.
Innovation Solution
A waterborne polyurethane-epoxy resin based primer composition comprising hydroxyl functional acrylic-epoxy resin, hydrocarbon resin, cosolvent, and polyisocyanate, with a specific weight ratio and formulation that enhances drying speed, adhesion, and resistance, allowing for its use in the wet-on-wet process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If waterborne coatings are used to comply with VOC regulations, then environmental friendliness is improved, but drying speed becomes too slow for wet-on-wet process
Solution Approach 1:
The patent modifies the chemical composition parameters of the waterborne coating by incorporating polyurethane-epoxy resin with specific molecular weight and functionality, along with carefully selected solvents and curing agents. This changes the chemical parameters to enable faster drying while maintaining waterborne characteristics and low VOC emissions.
Solution Approach 2:
The patent creates a composite waterborne coating system combining multiple components: polyurethane-epoxy resin, hydrocarbon resin, solvents, and curing agents. This composite formulation leverages the fast drying properties of polyurethane while maintaining the environmental benefits of waterborne coatings through proper formulation balance.
2Object-affected harmful factors
If slow drying speed is accepted in waterborne coatings, then environmental friendliness is maintained, but coating quality deteriorates with low gloss, foaming, and poor adhesion
Solution Approach 1:
The patent adjusts critical formulation parameters including resin type, solvent composition, and curing agent selection to simultaneously achieve fast drying and high coating quality. The specific parameter changes enable the coating to cure properly without foaming or adhesion failures while maintaining low VOC content.
Solution Approach 2:
The patent introduces carefully selected solvents and curing agents as intermediary substances that facilitate proper coating formation. These intermediaries enable the waterborne coating to dry quickly and form a high-quality film with good adhesion and gloss, mediating between the conflicting requirements of fast drying and quality maintenance.
3Reliability
If epoxy-based primer is used for wet-on-wet process, then adhesion is improved, but drying speed becomes excessively slow in wet and cold weather
Solution Approach 1:
The patent creates a composite primer formulation combining polyurethane-epoxy resin with hydrocarbon resin and specific curing agents. This composite approach maintains the strong adhesion properties of epoxy while incorporating components that enable faster drying, particularly in challenging wet and cold weather conditions.
Solution Approach 2:
The patent modifies the chemical parameters of the primer by selecting polyurethane-epoxy resin with specific molecular weight and functionality, along with appropriate curing agents. These parameter changes enable the primer to achieve fast drying in wet and cold weather while maintaining reliable adhesion to substrates.
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 primer composition achieves fast drying, strong adhesion, and improved water and chemical resistance, making it suitable for the wet-on-wet process while reducing VOC emissions and maintaining storage stability.
Implementation Method 1
a waterborne polyurethane-epoxy resin based primer composition comprising: (A) a paint composition comprising, based on the total weight of Component (A): from 37% to 50% by weight of hydroxyl functional acrylic-epoxy resin, from 3% to 10% by weight of hydrocarbon resin containing at least one phenolic hydroxyl group
Data Source
AI summary
Disclosed herein is a waterborne polyurethane-epoxy resin-based primer composition and its preparation method. Further disclosed herein is a primer layer obtained from curing the waterborne polyurethane-epoxy resin-based primer composition on substrates as well as a method of curing the primer composition on substrates.