Transport Coating Dynamic Squeegee for Thin Layer Application
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Solution Overview
Problem
Multilayer coating processes struggle to simultaneously coat fluids with significantly different properties, such as surface tension and viscosity, onto a substrate without forming air pockets or defects, especially when using difficult-to-coat substrates.
Innovation Solution
A method involving a dual-slot coating die system where a viscoelastic transport layer from one die acts as a 'dynamic squeegee' to spread and even a wetting layer from another die, manipulating rheological properties and die positioning to achieve a thinner, uniform coating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple coating fluids with different properties are applied simultaneously using conventional multilayer coating processes, then coating efficiency is improved, but the ability to coat fluids with significantly different surface tension and viscosity deteriorates
Solution Approach 1:
A transport coating is introduced as an intermediary layer between the substrate and the coating fluid. This transport coating has specific rheological properties that enable it to carry and distribute the coating fluid uniformly across the substrate, allowing simultaneous coating of fluids with widely different properties without forming air pockets or defects.
2Device complexity
If conventional coating methods are used to apply coating fluids onto difficult-to-coat substrates, then coating process simplicity is maintained, but coating quality and adhesion deteriorate
Solution Approach 1:
The transport coating serves as a mediating layer that facilitates uniform distribution and strong adhesion of the coating fluid to difficult-to-coat substrates. It bridges the gap between the coating fluid and the substrate, ensuring quality coating without requiring complex process adjustments.
3Reliability
If air pockets are present in multilayer coatings, then coating defects increase, but eliminating them requires complex process control
Solution Approach 1:
The rheological parameters of the transport coating are specifically optimized to prevent air pocket formation. By adjusting the viscosity, surface tension, and other rheological properties of the transport coating, the system naturally eliminates air pockets during the coating process without requiring complex real-time process control.
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 allows for a wider range of fluid properties to be coated simultaneously, reducing air pockets and improving adhesion and cohesion on structured liners, enabling efficient coating of large-scale adhesive graphics without damage or trapped air bubbles.
Implementation Method 1
applying a viscoelastic second coating fluid from the second coating die over the first coating layer on the substrate forming a second coating layer
Implementation Method 2
Manipulation of the rheological properties of the transport layer can both be used as process parameters to accomplish the amount of spreading of the underlying coating layer
Implementation Method 3
The interaction between the substrate and the layer deposited closest to that substrate is also a consideration
Implementation Method 4
for a given set of fluids to be coated simultaneously, the particular applicator and process conditions used in a multilayer coating process often dictate how different the fluids can be with respect to a particular property such as surface tension, viscosity
Data Source
AI summary
It has now been determined that a first coating layer may be applied to a substrate by a first coating die in a much thinner layer than its rheological properties and/or surface properties would normally allow. This is accomplished by using a second coating fluid dispensed from a second coating die acting as a “dynamic liquid squeegee” to transport, spread, even, or meter the first coating layer on the substrate by varying a gap between the second coating die and the substrate.