Multicoat Paint Basecoat Admixed with Polyamide Dispersion
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Solution Overview
Problem
Multicoat paint systems produced without separate curing steps often suffer from issues like pinholes, pops, and slumping due to air, solvent, and moisture inclusions, leading to poor esthetic and technological properties, especially at higher coat thicknesses.
Innovation Solution
A method involving the direct application of a basecoat and clearcoat on a substrate with the basecoat material admixed with an aqueous dispersion containing polyamide and amide wax, followed by joint curing, to eliminate sag resistance problems and prevent slumping without affecting the appearance or run properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multicoat paint systems are produced without separate curing steps (joint curing of basecoat and clearcoat), then productivity is improved and process complexity is reduced, but manufacturing precision deteriorates due to pinholes, pops, and slumping defects
Solution Approach 1:
The basecoat is applied and allowed to flash off solvents and level out before clearcoat application, but without complete curing. This preliminary action removes air and solvent inclusions that would cause pinholes and pops during joint curing, while maintaining the productivity benefit of joint curing by not requiring full cure of the basecoat before clearcoat application.
Solution Approach 2:
The invention controls the flash-off time and solvent evaporation rate by adjusting basecoat formulation and application parameters. This allows the basecoat to release trapped air and solvents before clearcoat application, preventing pinholes and pops while maintaining the efficiency of joint curing processes.
2Manufacturing precision
If basecoat coat thickness is increased to improve coverage and esthetic properties, then manufacturing precision improves, but stability deteriorates due to slumping and sagging
Solution Approach 1:
The basecoat formulation includes anti-sagging agents and rheology modifiers that prevent slumping and sagging even at higher coat thicknesses. This preliminary anti-action counteracts gravitational forces on the wet coating, allowing thicker applications for better coverage without compromising coat stability.
Solution Approach 2:
The basecoat is formulated as a composite material combining pigments, binders, solvents, and rheology modifiers in specific proportions. This composite structure provides both the thickness needed for coverage and the stability to prevent slumping, resolving the contradiction between coverage quality and coat stability.
3Object-affected harmful factors
If aqueous basecoat materials are used to improve environmental properties, then harmful factors are reduced, but manufacturing precision deteriorates due to poor sag resistance and slumping
Solution Approach 1:
The aqueous basecoat formulation is optimized with specific pH ranges, solvent mixes, and rheology modifiers to achieve both environmental compatibility and adequate sag resistance. By adjusting these parameters, the coating maintains stability at higher thicknesses without slumping while remaining an environmentally friendly aqueous system.
Solution Approach 2:
The aqueous basecoat is designed as a composite system where water-based binders, pigments, and thickening agents work together to provide both environmental benefits and sufficient sag resistance for high-quality coating application without slumping defects.
Data Source
AI summary
Described herein is a method for producing a multicoat paint system by producing a basecoat or a plurality of directly successive basecoats directly on a substrate coated with a first coat, producing a clearcoat directly on the one or the topmost of the plurality of basecoats, and subsequently jointly curing the one or the plurality of basecoats and the clearcoat. At least one of the basecoat materials is admixed, directly before application, either with an aqueous dispersion (D1) including a polyamide (PA) having an acid number of 15 to 60 mg KOH/g or with an aqueous dispersion (D2) including a polyamide (PA) and an amide wax (AW).