Rotating Rod Melt Coating for Ultrathin High Viscosity Layers
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Solution Overview
Problem
Current methods for producing high-quality melt coatings of high molecular weight, high viscosity materials are limited by their thickness and speed, often resulting in coatings with defects and requiring costly drying processes.
Innovation Solution
A method involving a rotating rod with a diameter less than 3 inches and a backup roller, where the rod rotates at greater than 20 rpm, is used to convey a molten coating composition through a die slot, allowing for the formation of ultrathin, high-quality melt coatings without a liquid carrier medium, eliminating the need for drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high molecular weight, high viscosity materials are coated using conventional extrusion methods, then coating quality can be maintained, but coating thickness is limited to greater than 100 μm and processing speed is slow
Solution Approach 1:
The patent changes the physical parameters of the coating process by heating the high viscosity material to reduce its viscosity, enabling it to flow through a thin die slot. This parameter change allows ultrathin coatings to be formed while maintaining coating quality, resolving the contradiction between coating thickness and coating quality.
Solution Approach 2:
The patent introduces a rotating rod that contacts the extruded melt and the substrate, creating a new dimensional control mechanism. The rod's rotation and positioning in the nip region provide precise control over coating thickness, enabling ultrathin coatings below 100 μm while maintaining quality.
2Length of moving object
If high molecular weight materials are coated using calendar coating, then coating thickness can be increased, but extremely high nip pressures (more than 3000 psi) are required and processing speed is slow
Solution Approach 1:
The patent changes the viscosity parameter of the coating material by heating it before extrusion. This reduces the material's resistance to flow, allowing thin coatings to be formed at much lower nip pressures compared to calendar coating of high viscosity materials, eliminating the need for extremely high pressures.
3Productivity
If low viscosity, low molecular weight polymers are coated using roll coating or slot die coating, then processing speed can be increased, but coating weight is limited to greater than 20-25 g/m²
Solution Approach 1:
The patent uses a rotating rod that can be positioned at different heights and rotation speeds, adding a new dimensional control variable. By adjusting the rod's position and rotation, ultrathin coatings below 20-25 g/m² can be formed at high processing speeds, overcoming the coating weight limitation of conventional methods.
4Ease of manufacture
If conventional extrusion methods are used for high viscosity materials, then coating can be formed, but the process requires extrusion pumping and mixing operations increasing device complexity
Solution Approach 1:
The patent combines the extrusion, coating, and rod contact operations into an integrated process. The material is extruded through a thin die slot and immediately contacted by the rotating rod in the same operational sequence, eliminating separate pumping and mixing steps, thereby reducing device complexity while maintaining coating formation capability.
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 method enables the production of high-quality, thin caliper melt coatings at high speeds, reducing material costs and improving product performance, while avoiding defects and post-coating treatments.
Implementation Method 1
high viscosity (i.e., more than 50 Pa-s), high molecular weight (i.e., more than 200,000 g/mol) hot melt coatable polymers are not liquid-like in the melt state due to the presence of polymer chain entanglements
Implementation Method 2
the pressure of the nip point preferably causes deformation of the backup roller
Data Source
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AI summary
Articles with thin caliper melt coatings of high molecular weight, high viscosity materials and methods of making such coatings.