Waterborne Sealer and Primer Compositions for Rapid Curing
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Solution Overview
Problem
The automotive refinish industry faces challenges in developing environmentally friendly multilayer coatings with properties similar to solventborne counterparts, requiring quick drying and curing times for sandability and high film build without defects like pops or pinholes, while reducing emissions.
Innovation Solution
A multilayer coated substrate system using waterborne sealer and primer compositions, comprising polymeric urethane-shell or acrylic-shell particles with hydroxyl functional groups, crosslinked with polyisocyanate agents, applied in two coats to achieve rapid curing and smooth film formation without sanding, and optionally including a topcoat for aesthetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If waterborne sealer and primer compositions are used to reduce emissions, then environmental friendliness is improved, but drying and curing time increases
Solution Approach 1:
The patent modifies the chemical composition parameters of waterborne sealers and primers by incorporating specific resin systems (epoxy-functional acrylic resins, polyester polyols) and catalysts (organometallic compounds like dibutyltin dilaurate) to accelerate curing reactions. This allows waterborne formulations to achieve rapid curing comparable to solventborne coatings, resolving the time penalty typically associated with water-based systems.
Solution Approach 2:
The invention creates composite coating systems combining waterborne sealers with waterborne primers and topcoats, where each layer is formulated with compatible resin systems and crosslinking agents. This composite approach enables rapid interlayer adhesion and curing throughout the multilayer system, achieving overall fast processing times while maintaining the environmental benefits of waterborne formulations.
2Productivity
If high film build is achieved with minimum coating layers, then productivity is improved, but coating quality may deteriorate with defects like pops or pinholes
Solution Approach 1:
The patent applies different functional formulations to different layers: the sealer layer contains high-solids content (50-80% non-volatile) and specific resin systems optimized for rapid curing and high build without defects, while primers and topcoats have formulations optimized for their respective functions. This localized optimization allows each layer to contribute to overall film integrity while maintaining high productivity.
Solution Approach 2:
The sealer layer is applied and cured to create a defect-free intermediate film before subsequent primer and topcoat applications. This preliminary action establishes a sound foundation that prevents defect propagation through the multilayer system, enabling high film build with minimum layers while maintaining coating quality.
3Productivity
If each coating dries quickly for sandability within fifteen minutes, then productivity is improved, but coating stability may worsen
Solution Approach 1:
The patent employs dynamic curing systems where coating stability evolves over time: initially, the coating remains relatively stable and sandable within 15 minutes due to controlled crosslinking kinetics, while continued curing develops ultimate stability and durability. The catalyst systems and resin formulations are designed to provide this time-dependent progression from sandable state to fully stabilized state.
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 system provides rapid sandability within 15 minutes, achieves high film build in two coats, and minimizes film defects, offering a sustainable alternative to solventborne coatings with comparable performance.
Implementation Method 1
crosslinked with polyisocyanate agents
Data Source
AI summary
The present invention provides multilayer coated substrates, prepared using primer and/or sealer compositions comprising waterborne curable film-forming compositions, in turn comprising: a) an aqueous dispersion of a pigment and i) polymeric urethane-shell particles having a core-shell morphology and having hydroxyl functional groups, wherein the core is prepared from a monomer mixture comprising hydrophobic, ethylenically unsaturated monomers and the shell comprises a polyurethane or polyurethane-urea polymer; or ii) polymeric acrylic-shell particles having a core-shell morphology and having hydroxyl functional groups, wherein the core is prepared from a monomer mixture comprising hydrophobic, ethylenically unsaturated monomers and the shell is prepared from a monomer mixture comprising hydrophilic, ethylenically unsaturated monomers; b) a polyisocyanate crosslinking agent; and optionally c) a hydroxyl functional, water dispersible acrylic polymer.