Basecoat Composition Curing During Dehydration
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Solution Overview
Problem
The existing automotive coating processes require multiple steps, including an intermediate primer surfacer layer, which can lead to issues with uncured basecoat layers allowing solvent migration and affecting pigment orientation and intercoat adhesion, necessitating higher curing temperatures for the clearcoat.
Innovation Solution
A method involving a basecoat composition that cures during the dehydration step, allowing for a higher degree of cure before applying the clearcoat, thereby enabling lower temperature curing of the clearcoat and eliminating the need for a primer surfacer layer, reducing energy consumption and coating steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the basecoat layer is only dehydrated but not cured before application of the clearcoat, then the coating process can be simplified and energy consumption reduced, but the uncured basecoat does not have sufficient hold out properties allowing solvent migration that adversely affects pigment orientation and intercoat adhesion
Solution Approach 1:
The invention changes the chemical composition parameters of the basecoat by incorporating reactive functional groups (carboxyl, hydroxyl, or amine groups with specific concentrations) that enable the basecoat to cure during the dehydration step. This parameter change allows the basecoat to achieve sufficient cure degree before clearcoat application, providing adequate hold out properties while maintaining process efficiency
Solution Approach 2:
The basecoat is formulated with reactive groups that initiate curing action during the dehydration step itself, rather than requiring a separate curing step before clearcoat application. This preliminary curing action during dehydration ensures the basecoat has sufficient hold out properties before the clearcoat is applied, preventing solvent migration issues
2Reliability
If the basecoat is cured before application of the clearcoat, then intercoat adhesion and pigment orientation are improved, but an additional energy-consuming step is added to the coating process
Solution Approach 1:
The invention merges the dehydration step with the curing step by formulating the basecoat with reactive functional groups that enable curing to occur during dehydration. This consolidation of steps eliminates the need for a separate curing step before clearcoat application, reducing energy consumption while ensuring adequate basecoat cure and hold out properties
Solution Approach 2:
By changing the chemical composition of the basecoat to include reactive groups at specific concentrations, the curing reaction is triggered during the dehydration step itself. This parameter change allows the basecoat to achieve sufficient cure degree without requiring additional energy-intensive curing steps
3Reliability
If the clearcoat is cured at high temperature to ensure proper curing, then the curing completeness is improved, but energy consumption increases
Solution Approach 1:
The basecoat undergoes preliminary curing during the dehydration step, achieving a high degree of cure before clearcoat application. This preliminary action reduces the curing burden on the clearcoat, allowing it to be cured at lower temperatures while still achieving complete curing of the overall coating system
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 results in improved adhesion and appearance by ensuring the basecoat is fully cured before clearcoat application, reducing energy consumption and simplifying the coating process while maintaining high physical and chemical properties.
Implementation Method 1
the basecoat layer is formed by depositing a polyhydrazide-containing curable aqueous composition
Implementation Method 2
the basecoat composition that cures through the dehydration step resulting in a high degree of cure
Implementation Method 3
polymeric particles prepared from the polymerization of a mixture of ethylenically unsaturated monomer compounds
Data Source
Figure 1
AI summary
A method for applying a multilayer coating comprising a basecoat and a clearcoat is disclosed. The basecoat is a curable aqueous composition comprising (1) polymeric particles prepared from ethylenically unsaturated compounds including a multi-ethylenically unsaturated monomer and a keto or aldo-functional monomer, and (2) a polyhydrazide.