Extrusion Coating Roller for High Aspect Ratio Nanostructured Foil
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Solution Overview
Problem
Current methods for producing high aspect ratio micro or nanostructures on thermoplastic surfaces are limited by slow throughput rates and inability to cover large areas continuously without significant seam lines, making them economically unfeasible for applications like self-cleaning surfaces and food packaging.
Innovation Solution
The use of extrusion coating or casting processes with micro or nanostructured cooling rollers to continuously apply and solidify thermoplastic melts onto carrier foils, enabling high throughput rates and seamless, large-area micro or nanostructured coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variotherm injection molding or embossing processes are used to produce high aspect ratio micro or nanostructures, then the surface structures can be formed, but the throughput rate is limited to 0.001-0.01 m2/s due to slow heating and cooling cycles
Solution Approach 1:
The patent replaces the thermal field-based variotherm injection molding and embossing processes with a mechanical extrusion coating system. The extrusion coating apparatus uses a doctor blade to mechanically control the thickness and structure of the polymer layer as it is deposited and cooled on the substrate, eliminating the need for slow thermal heating and cooling cycles while achieving high aspect ratio micro and nanostructures.
Solution Approach 2:
The patent changes the fundamental processing parameters from thermal control (heating/cooling cycles) to mechanical control (extrusion rate, doctor blade gap, substrate speed). This parameter transformation enables throughput rates of 0.5-10 m2/s, representing a 50-1000 fold increase in productivity compared to conventional thermal processes.
2Area of stationary object
If conventional lithographic embossing is used to create micro or nanostructures, then the structures can be formed, but the process cannot cover large areas continuously and produces significant seam lines
Solution Approach 1:
The extrusion coating process operates continuously as the substrate moves through the coating head, with the doctor blade constantly controlling the polymer layer formation. This continuous action eliminates the periodic start-stop nature of conventional embossing, allowing seamless coverage of large areas without visible seam lines between processing zones.
Solution Approach 2:
The patent transitions from planar 2D embossing to a 3D extrusion process where the doctor blade creates controlled thickness variations in the z-dimension. This dimensional addition allows the formation of high aspect ratio micro and nanostructures (depths of 1-100 micrometers) while maintaining continuous coverage across the substrate surface.
3Manufacturing precision
If high aspect ratio structures are produced using variotherm processes, then the micro or nanostructures can be formed, but the cycle time increases considerably due to temperature variation requirements
Solution Approach 1:
The polymer material is prepared and conditioned before the extrusion process, and the substrate is pre-coated with a release layer. The extrusion coating head is pre-adjusted with the doctor blade at the precise gap setting required for the desired structure height. These preliminary preparations enable immediate high aspect ratio structure formation without iterative heating and cooling cycles, significantly reducing the overall process time.
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 achieves throughput rates of up to 5-10 m2/s, producing high-quality, seamless micro or nanostructured thermoplastic coatings that cover entire foil areas, significantly improving productivity and cost-effectiveness compared to existing methods.
Implementation Method 1
The use of extrusion coating or casting processes with micro or nanostructured cooling rollers to continuously apply and solidify thermoplastic melts onto carrier foils
Implementation Method 2
applying a high aspect ratio nanostructured surface on the said extrusion coating roller thereby forming a high aspect ratio nanostructured extrusion coating roller
Data Source
AI summary
A solid nano- or micro-structured thermoplastic foil including a nano- or micro-structured surface area is produced by providing an extrusion casting roller for an industrial polymer extrusion casting process using a thermoplastic material, applying a nano- or micro-structured surface on the extrusion casting roller, maintaining a temperature of the casting roller below a solidification temperature of the thermoplastic material while the casting roller and the counter roller are rotating, and continuously applying a melt of the thermoplastic material between a counter roller and the casting roller while the casting roller and the counter roller are rotating. A rotational velocity of the casting roller may be 10 meters/minute. The melt of the thermoplastic material is moved between the casting roller and the counter roller while the rollers are rolling, and the melt of the thermoplastic material is solidified upon contact with the casting roller to form the thermoplastic foil.