Water-based Coating Composition for 3-Coat 1-Bake Systems
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Solution Overview
Problem
The 3-coat, 1-bake system for forming multilayer coating films faces challenges in achieving an excellent finished appearance and storage stability due to layer mixing and viscosity issues during coating material storage.
Innovation Solution
A water-based coating composition comprising acrylic or polyester resin, a curing agent, and urethane resin particles derived from xylylene diisocyanates or hydrogenated xylylene diisocyanates, applied in a 3-coat, 1-bake process with specific molecular weight ranges and content ratios, to form a multilayer coating film with improved appearance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a water-based intercoat material is used in a 3-coat, 1-bake system to eliminate preheating and reduce energy consumption, then energy savings are achieved, but coating film layer mixing occurs between the intercoat layer and base coat layer, resulting in poor finished appearance
Solution Approach 1:
The patent changes the chemical composition parameters of the water-based coating material by incorporating specific resin combinations (acrylic resin with polyester resin in 95:5 to 50:50 mass ratio), curing agents, and urethane resin particles with controlled molecular weights and functional groups. These parameter changes enable the coating to maintain layer integrity while using water as solvent, thus achieving both energy savings and good finished appearance.
Solution Approach 2:
The patent uses a composite material system combining multiple resin types (acrylic, polyester, and urethane resins) with specific functional groups. This composite approach creates a coating formulation that prevents layer mixing while maintaining water-based properties, resolving the contradiction between energy efficiency and appearance quality.
2Manufacturing precision
If the viscosity of coating material is increased to prevent layer mixing, then coating film layer mixing is reduced, but increasing viscosity or precipitation during storage hamper application and reduce storage stability
Solution Approach 1:
The patent carefully controls the molecular weight parameters of the resin components (acrylic resin: 10,000-1,000,000, polyester resin: 1,000-100,000) and their mass ratios to achieve optimal viscosity. This parameter optimization prevents layer mixing during application while maintaining storage stability by avoiding excessive viscosity and precipitation.
Solution Approach 2:
The patent introduces urethane resin particles with specific local properties (core-shell structure, controlled molecular weight 1,000-100,000) that provide localized functionality. These particles prevent layer mixing at the interface between coats while the overall formulation maintains stable viscosity during storage, resolving the contradiction between layer separation and storage stability.
3Loss of energy
If preheating after aqueous intercoat material application is eliminated to increase energy savings, then energy consumption is reduced, but coating film layer mixing occurs and finished appearance deteriorates
Solution Approach 1:
The patent modifies the chemical parameters of the coating formulation by incorporating specific resin combinations and curing agents that enable direct curing without preheating. The acrylic-polyester-urethane resin system with controlled molecular weights and functional group ratios allows the coating to cure properly at lower temperatures, preventing layer mixing and maintaining excellent finished appearance while eliminating the energy-intensive preheating step.
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 enables the formation of multilayer coating films with excellent finished appearance and enhanced storage stability by preventing layer mixing and maintaining viscosity stability during storage.
Implementation Method 1
urethane resin particles (D) obtained from a constituent component including a polyisocyanate component (d1) comprising at least one type of diisocyanate (d1-1) selected from among xylylene diisocyanates and hydrogenated xylylene diisocyanates, and a polyol component (d2)
Implementation Method 2
a curing agent (C), and urethane resin particles (D) obtained from a constituent component including a polyisocyanate component (d1)
Data Source
AI summary
Provided is a water-based coating composition capable of forming a multilayer coating film having an excellent finished appearance and having excellent storage stability. A water-based coating composition to be used as a water-based first colored coating (X) in a 3-coat-1-bake multilayer coating formation method which sequentially applies a water-based first colored coating (X), a water-based second colored coating (Y), and a clear coating (Z) and heats and cures the obtained three-layer multilayer coating film simultaneously, wherein the water-based coating composition contains at least one resin selected from acrylic resins (A) and polyester resins (B), a curing agent (C), and urethane resin particles (D) obtained from structural components including a polyisocyanate component (d1) containing at least one diisocyanate (d1-1) selected from xylylene diisocyanate and hydrogenated xylylene diisocyanate and a polyol component (d2).