Substrate Coating With Gas-Assisted Surface Leveling
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Solution Overview
Problem
Conventional inkjet coatings for automotive applications face challenges in achieving uniform coating thickness and sag control when using high transfer efficiency applicators due to non-Newtonian properties and rheology control agents that impede flow and leveling, leading to visible defects and overspray issues.
Innovation Solution
A non-Newtonian coating composition with controlled viscosity is applied using a high transfer efficiency applicator, followed by impinging the coating layer with gas to smooth and level the surface, creating a uniform appearance or desired texture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rheology control agents are incorporated into the coating composition to prevent sag, then sag resistance is improved, but flow and leveling are impeded causing visible defects
Solution Approach 1:
The patent utilizes temperature as a controllable parameter to modify the viscosity of the coating composition. By heating the coating, the viscosity decreases enabling better flow and leveling. By cooling or allowing temperature to stabilize, viscosity increases providing sag resistance. This dynamic parameter change resolves the contradiction between needing low viscosity for flow and high viscosity for sag prevention.
2Stability of the object's composition
If the coating composition has high viscosity to resist sagging, then sag control is improved, but flow through the high transfer efficiency applicator is impeded
Solution Approach 1:
The patent applies dynamic temperature control during the coating process. The coating composition is heated before and during application to reduce viscosity for optimal flow through the high transfer efficiency applicator. After application, the temperature is allowed to decrease or is actively cooled to increase viscosity and prevent sagging. This dynamic adjustment of physical conditions resolves the contradiction between flowability and sag control.
3Productivity
If conventional spray equipment is used to apply coating, then application speed is improved, but overspray loss and volatile loss increase
Solution Approach 1:
The patent employs a high transfer efficiency applicator that uses pneumatic principles to deliver coating material. The applicator uses pressurized gas to atomize and direct the coating composition precisely onto the substrate surface, minimizing overspray and bounce-back. This pneumatic delivery system maintains high application speed while significantly reducing coating material loss compared to conventional spray equipment.
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 method ensures uniform coating thickness and reduces visible defects by allowing the coating to flow and level after application, minimizing overspray and enhancing appearance.
Implementation Method 1
The coating layer is impinged with a gas such that a coating layer surface moves upon impingement with the gas
Implementation Method 2
the coating composition is non-Newtonian such that a coating composition viscosity decreases when the shear rate is increased
Data Source
AI summary
Methods of coating a substrate are provided. In an exemplary embodiment, a coating composition is applied to the substrate with a high transfer efficiency applicator to produce a coating layer, where the high transfer efficiency applicator and the substrate remain spatially separate while the coating composition is applied. A droplet of the coating composition expelled from the high transfer efficiency applicator has a particle size of about 10 microns or greater. The coating composition has a viscosity of from about 1,000 to about 1,000,000 centipoise when the coating composition is subject to a shear rate of about 0.1 reciprocal seconds (s−1). However, the coating composition is non-Newtonian such that a coating composition viscosity decreases when the shear rate is increased to the coating composition. The coating layer is impinged with a gas such that a coating layer surface moves upon impingement with the gas.