Multilayer Coating Film Wet-on-Wet Application
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Solution Overview
Problem
Conventional methods for forming multilayer coating films using water-based compositions require a preheat step to prevent layer mixing, which increases energy consumption and environmental impact, while omitting this step often results in defects like sagging and poor film appearance.
Innovation Solution
A method involving a first water-based base coating composition with a hydrophilic associated type viscosity agent and a second water-based base coating composition comprising an acrylic emulsion resin, a water-soluble acrylic resin, and a water-soluble polyester resin, applied without a preheat step, to form a multilayer coating film by simultaneously heating and curing all layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a preheat step is performed to prevent layer mixing, then layer mixing is prevented and film appearance is maintained, but energy consumption increases and environmental impact worsens
Solution Approach 1:
The invention changes the chemical composition parameters of the coating compositions, specifically incorporating a polycarbodiimide compound and an aqueous resin with carboxyl groups in controlled ratios. This compositional parameter change enables the system to achieve layer stabilization without requiring thermal energy input from a preheat step, thus resolving the contradiction between maintaining film appearance and reducing energy consumption
Solution Approach 2:
The polycarbodiimide compound acts as a chemical intermediary that mediates the interaction between water-based coating layers. It controls the affinity and bleeding between layers through chemical reactions with the carboxyl-containing resin, preventing layer mixing without requiring thermal energy, thereby eliminating the need for the preheat step while maintaining excellent film appearance
2Manufacturing precision
If a preheat step is performed to prevent layer mixing, then layer mixing is prevented, but coating process complexity and time increase
Solution Approach 1:
The invention extracts and eliminates the preheat step from the coating process by incorporating functional chemical components directly into the coating compositions. The polycarbodiimide compound and carboxyl-containing resin provide inherent layer stabilization, allowing the process to proceed without the separate preheat operation, thus reducing process complexity while maintaining layer mixing prevention
Solution Approach 2:
The desired layer stabilization effect is built into the coating compositions themselves through preliminary chemical formulation. The polycarbodiimide compound and carboxyl-containing resin are pre-mixed into the coating layers, so that when applied, they automatically prevent layer mixing without requiring subsequent preheat treatment, thereby simplifying the overall process
3Manufacturing precision
If a preheat step is performed to prevent layer mixing, then layer mixing is prevented and film appearance is maintained, but coating time increases
Solution Approach 1:
The invention merges the layer stabilization function into the coating composition formulation itself. By combining the polycarbodiimide compound and carboxyl-containing resin within the coating layers, the stabilization effect is achieved as an inherent property of the coating material, eliminating the need for a separate preheat step and thus reducing total coating time while maintaining excellent film appearance
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
This approach prevents sagging and layer mixing, achieving excellent film appearance and smoothness without the need for a preheat step, thereby reducing energy consumption and environmental footprint.
Implementation Method 1
the first water-based base coating composition comprises a hydrophilic associated type viscosity agent
Implementation Method 2
simultaneously heating and curing the uncured first water-based base coating film, the uncured second water-based base coating film and the uncured clear coating film
Implementation Method 3
simultaneously heating and curing the three layers
Data Source
AI summary
Provided is a method for forming a multilayer coating film, said method being suitably applicable to a wet-on-wet coating process comprising: applying a first water-borne base coating material to form an uncured first water-based base coating; and then applying a second water-based base coating material without preheating the uncured first water-borne base coating. A method for forming a multilayer coating film according to a wet-on-wet coating process which comprises applying a first water-based base coating material to the surface of a substrate to be coated and then applying, without preheating the thus formed coating, a second water-based base coating material, characterized in that: the first water-borne base coating material contains a hydrophilic association-type viscous material; and the composition of the second water-based base coating material is controlled.