In industrial processes for manufacturing plastic and aluminum coils, it is essential to be able to treat the material very quickly, and if possible, with the same speed with which the films or sheets circulate through the production line. These speeds can reach several meters per second, so it is essential in these cases to find fast processes that can provide new properties to these materials. This is where the “Roll to roll” (R2R) texturing processes get their most benefit.
What is the R2R texturing process?
The Roll to Roll texturing process uses many of the typical tools of the winding and unwinding processes, so its integration into these processes is easy and straightforward. Basically the Roll to roll texturing consists of the following elements:
- Two cylinders or rollers: they come into contact with the film or sheet on both sides, and they apply pressure, temperature, ink, or another substance, which modify the properties of the base material. Depending on the process, they can be the two active cylinders and provide the new property to the material, or just one.
- Pressure applicator: in order to ensure good contact between the material to be treated and the cylinders, there must be an element that can make the cylinder exert pressure.
- Unwinder: is the element in charge of unwinding the reels of plastic or aluminum film and leaving them flat and linear for their subsequent processing using Roll to roll texturing.
- Winder: it is the element in charge of rewinding the reels of plastic or aluminum film once they have passed the Roll to roll texturing process.
Types of roll to roll texturing processes
There are different types of Roll to roll texturing processes depending on the technique used to cause the modification of the surface properties of the material to be treated:
Reduction of the thickness of a plastic film or metal sheet by applying pressure by the rollers.
Through grooves made in the rollers, paint is applied on them, which is transferred to the material by means of a small pressure.
Application of roughness or textures to plastic films or metal sheets by applying pressure from the rollers, which have been previously machined with the negative of the motifs to be transferred.
It is the same as texturing, but with roughness and micrometric scale motifs.
Properties to be achieved with the Roll to roll texturing process through microstructuring
As we have mentioned, the microstructuring technique in the Roll to roll texturing process consists in the realization of a controlled roughness, or of some specific patterns on the rollers. However, the peculiarity of this technique is the small scale of these roughnesses and patterns, which can be from a single micrometer to hundreds of micrometers.
The modification of the roughness on a micrometric scale in the materials can provide, depending on the pattern or roughness chosen, different surface properties, such as the following, among others:
Advantages of microstructuring using a Roll to roll texturing process
Compared with other microstructuring processes, microstructuring using a Roll to roll texturing process provides certain advantages that are very important in the industry:
- Speed: Roll to roll texturing processes have the potential to go at very high speeds, so the cycle time of the line need not be affected.
- Incorporation into the current process: it is not necessary to mount a different installation to be able to apply the microstructure, as would be the case with the application by means of laser, so the costs in time and money are significantly reduced.
- Productivity: if we compare it with discrete microstructuring processes, being able to provide the microstructure continuously and long lengths at the same time, makes the productivity of the process very high.
- Without consumables: to transfer the microstructure, you only need to apply pressure on the material, so there is no type of consumable that is necessary in the process.
Steps to carry out a microstructuring project using a Roll to roll texturing process
To carry out a microstructuring project through a Roll to roll texturing process, based on our experience and the projects we have developed, we can list the following steps:
Define the property to obtain
It is the fundamental step on which the entire project is built. You have to be clear about what property you want to achieve or improve in the material
Find the most suitable microstructure
Once we know the property we want to influence, we must find the microstructure that can achieve the desired effects. For this one can build on similar projects carried out previously, or can develop microstructures from scratch.
Application of microstructure to roller material on a laboratory scale
With the microstructure (s) selected in the previous step, a laboratory roller or similar element will be microstructured using laser or another technique, with which the microstructure can be transferred to the target material.
By applying pressure, the microstructure is transferred from the roller to the target material.
Evaluación de las propiedades
Una vez obtenida la microestructura en el material que queremos mejorar, se deben realizar pruebas de laboratorio que puedan medir y cuantificar si se ha obtenido la propiedad deseada, o si se ha mejorado.
If the desired properties have been achieved in the laboratory tests, the next step is to carry out a pilot installation, in which the rollers can be microstructured and the microstructure applied as it would be done in the final application
Final factory installation
Once it has been verified that the production objectives and the improvements in the material properties have been achieved, the rollers can be installed at the factory and the film or sheets with the new functionality can be obtained.
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