Corona discharge treatment is a well-established and commonly utilized surface treatment procedure in engineering applications worldwide. The method, which primes materials with a high-voltage, high-frequency discharge, increases wettability and adhesion, boosting the surface’s receptiveness to adhesives, inks, and coatings.
Corona treatment, often used on a wide range of metals and polymers, works by boosting surface energy, allowing several bonding or printing processes to take place.
It is an excellent technique to raise the efficiency of your manufacturing output since it improves print quality, allows for faster printing processes, and increases correct first-time processing, decreasing waste or the number of faulty items.
It is also quite good at increasing adhesive characteristics, allowing you to attach the surface to certain other materials.
Corona Treatment’s History
Corona therapy dates back to 1951 when engineers first implemented it in the industrial and manufacturing sector. Verner Eisby, a Danish engineer, had been charged by a customer with figuring out how to print on plastic, which they found extremely difficult.
Following significant experimentation, the engineer developed a solution that would permanently transform the field of surface treatments. He hypothesized that a high-frequency laser or corona discharge might cure a surface while keeping heating within control. As a result, the engineer has created corona discharge treatment, a technique that has played an essential role in our modern society.
So why do manufacturers require Corona Discharge for surface modification and treatment?
Polymer films feature chemically non-porous and inert surfaces with low surface tensions, making them incompatible with substrates, coatings, printing inks, and adhesives.
Pretreated films, or films that have been surface processed at the time of manufacture, have tremendous surface energy, which is essential for generating high-quality printed, coated, or laminated goods.
The untreated films throughout the manufacturing process will not receive printing, coating, or lamination satisfactorily. The inverse is not always true. Even if the film is treated at the time of manufacture, it does not necessarily ensure that printing, coating, or laminating will be simple in the future.
Each film type has an intrinsic surface energy (dyne level) that may be raised during manufacture by corona treatment. This level of care decreases over time. As a result, material that may be readily printed and coated soon after production might lose enough surface energy to become uncoatable and unprintable within a few days or weeks.
Receding in line is sometimes necessary since ensuring that the film you acquire will be transformed within the requisite time frame is practically challenging. You should note that treating in-line cannot substitute primary treatment during manufacturing. In reality, many films, particularly polyolefins (Polyethylene and Polypropylene), are nearly untreatable after manufacture.
Use films modified at the manufacturing time and retract in-line to maintain uniform quality. The substrates must be corona treated twice to produce a product of acceptable quality to both the converter and the final customer:
- At the time of manufacture.
- Before converting.
How does it benefit manufacturers?
The treatment improves the qualities of components, allowing them to function better under certain operating situations. Surface events without the necessary attributes might cause a device to fail (or the system containing it). Corona discharge is just one kind of surface modification.
Here are four critical advantages that corona discharge plasma provides to manufacturers:
Increase Manufacturing Output
Corona discharge, as well as other surface modification procedures, can remove impurities from sensitive surfaces, resulting in lower part failure and higher total production yields. This is especially true for fiber applications.
Increased Treatment Duration
Corona discharge treatments extend component life and corrosion resistance by eliminating all signs of organic contamination. Manufacturers frequently use it to treat components in the medical, pharmaceutical, biotech, aerospace, and other sectors.
Selective Surface Control
Corona treatment is a two-dimensional procedure. It provides a stable and simple-to-use system. Corona can be performed in-house with the necessary equipment, or you may outsource the job with a speedy turnaround.
Better Bonding Outcomes
Corona treatment can increase the binding strength of paints or inks, or the bond of one element to another plasma operates well with in-line processes, such as plastic film, by eradicating all signs of contamination.
Surface Effects Of A Corona Discharge
Surfaces treated with corona discharge plasma can have a range of impacts. Fluoroplastics such as polytetrafluoroethylene (PFTE) or fluorinated ethylene propylene (FEP), for example, show better adhesion following treatment.
This enables painting and printing on such materials, which would be considerably more difficult on untreated surfaces. Corona discharges can improve wettability and prevent shrinkage in natural fibers such as wool.
In previous research on polymers such as low-density polyethylene (LDPE), this type of plasma treatment modifies the surface roughness and the hydrophobicity of the substrate. The fact that corona plasmas may be sparked at atmospheric pressure and in reactive gases is a significant benefit.
Another significant factor is that there are few ions or free electrons present. As a result, there is no actual electrical breakdown, and the surface treatment is relatively moderate.
However, there is also the chance that the surface chemistry has changed. It has been demonstrated, for example, that polypropylene (PP) films absorb oxygen into the surface layer, resulting in a significant shift in wettability.
Corona treatment of non-conductive and polymer surfaces can also result in improved adhesion. Polymers come in a wide variety. PEEK and PET also showed improved adherence.
Corona discharge may help with which materials and products?
Corona discharge modifications are successful on any surface format, including dimensional items, sheets, and web-handled roll products.
Corona discharges are widely employed in the plastic film, extrusion, and conversion industries to treat a broad range of materials and products, including:
- Terephthalic polyethylene (PET)
- Polyvinylchloride (PVC) (PVC)
- Paperboard stock
There are various basic corona treatment system setups for treating web-based materials. They are classified based on where you locate the dielectric material in the station: double dielectric, conventional, bare roll, and convertible. The ideal configuration for a specific application is determined mainly by the material you process.
Corona discharge surface treatment is a quick and easy way to increase the surface tension of a wide range of materials, components, and packaging to make them more responsive to inks, coatings, and adhesives. The technique is consistent, controlled, and constantly being developed for new uses, utilizing familiar and novel materials.