Corona treatment generates a high voltage electrical discharge that is applied to the surface to be treated (plastics, paper, metallized surfaces, sheets...).

Corona treatment is mainly used by packaging companies: extrusion processes, converting, laminating, printing and all flexible packaging processing lines in general. It also has other applications: treatment of tubes, sheets, refrigerator panels.

Corona treatment is mainly used on plastics: polyethylene, polypropylene, polystyrene, PET and PVC, but it can also be applied to metals and plastic-coated paper.

Corona treatment is a faster and easier process than chemical treatments. It is also more environmentally friendly as it does not involve the use of harmful chemicals.

The effectiveness of corona treatment is measured using the Dyne kit in the form of liquid mixtures, pens or markers by measuring the surface tension of the substrate with the appropriate solution.

• Type of substrate treated: each substrate reacts differently to corona treatment.
• Discharge intensity: the intensity and duration of the treatment will affect its effectiveness.
• Environmental conditions: factors such as dust, moisture, and contaminants can reduce the effectiveness of treatment.
• Line speed: higher speeds require more power and surface area.

Yes, corona treatment is a safe and user-friendly treatment as long as the safety regulations, the instructions in the supplied user manual and the provider's instructions are followed. Proper handling of the systems and regular maintenance are key to avoid risks.

Corona treatment consists of an electrical discharge generated in a confined, linear space between an electrode and an insulated, grounded counter-electrode. Corona discharge treats large substrates such as plastic films, foils, sheets, metallized films, and plastic-coated paper.

Plasma treatment consists of an in air plasma discharge that removes contaminating particles from surfaces by increasing their surface energy. Plasma treatment acts on small areas (treatment area between 10 and 140 mm) of plastic objects, small flat surfaces, tubes and pipes, electrical and special cables.

Yes, from the control panel on the generator.

Corona treatment works on paper (e.g. to help anchor PE in the extrusion coating process). However, it is not possible to measure the level of surface treatment achieved using the Dyne test kit. This problem does not exist when treating plastic-coated paper.

Aspects to consider in determining whether your substrate should be treated are:

• Difficulty of the substrate to hold inks, adhesives and coatings
• The final quality you want to achieve (good adhesion of labels, printing, coatings)
• Adhesion tests that may have been performed on the substrate, indicating it has a low surface tension.

The air gap in corona treatment refers to the distance between the electrode and the surface of the substrate to be treated. The air gap affects the intensity of treatment: too much distance could reduce the effectiveness of treatment.

Corona treatment occurs when high voltage electrical discharges are applied to the surface of the substrate. These discharges ionize the surrounding air and break up oxygen molecules in the air. Oxygen atoms can then combine with other oxygen molecules to form ozone.

Ozone poses a risk to human health when present in high concentrations in the air. Therefore, ozone must be removed from the work environment, an ozone destruction equipment must be used, and ozone levels in treatment areas must be controlled to ensure operator safety.

The effect of corona treatment on the surface of a substrate is temporary and its duration varies depending on the substrate type, environment and storage conditions. For this reason, it is recommended that the treatment be performed in-line, i.e. immediately prior to the application of inks, adhesives or coatings. In particular, surface migration of lubricants and additives may rapidly reduce the effectiveness of the treatment and a treatment reinstatement may be required to restore the surface tension.

The data to be provided are: type of application requiring corona treatment, type of substrate, width and thickness of substrate, number of sides to be treated, and line speed. It is also advisable to provide the surface tension level that the substrate must achieve to be considered suitable for adhesion.

For plastics, measuring surface tension is essential to determine how inks, varnishes, adhesives or other coatings adhere to the surface of a substrate. The surface tension must be sufficiently high to achieve a quality print or optimum adhesion.

Surface tension is expressed in dyne per centimetre (dyne/cm) or mN/m.

Dyne tests can be carried out on a wide range of substrates: plastics, metals, glass and rubber. For the test to work, the surfaces to be tested must be smooth and non-porous (porous surfaces will absorb ink and invalidate the test).

Dyne Test Ink is a liquid mixture used to measure accurately the surface tension of plastic and non-plastic substrates. The mixture is applied to the surfaces to be tested to determine the exact value in dyne/cm and whether the adhesion will be good or poor.

The main causes can be:

• contamination of the surface by dust, oils, residues
• previous processing, such as hot forming or extrusion, which can leave residues on the surface
• type of plastic. For instance, polypropylene or polyethylene have a naturally low surface tension
• surface migration of additives and/or lubricants.

• Polyethylene (PE)
• Polypropylene (PP)
• Polystyrene (PS)
• Polyethylene terephthalate (PET)
• POLYVINYL CHLORIDE (PVC)
• Teflon (PTFE)
• Polyamide (PA)
• Recycled materials

Yes, Dyne Test Ink can be used on recycled plastics such as PET, PE or PP plastics, which often have a lower surface tension than virgin materials and therefore require careful testing to determine if adhesion with inks, paints or coatings of any kind is possible.

The test is very quick. It usually only takes a few seconds to apply the ink to the surface and observe its behaviour.

Yes, factors such as humidity, temperature and surface contamination can affect test results. To obtain accurate results, the test should be carried out in a controlled environment and the surface of the material should be as clean as possible.

Dyne Test Ink is a liquid mixture applied to the surface of the material to be tested using a brush or applicator. It is designed for extensive testing and laboratory use and accurately indicates the numerical value, expressed in dyne/cm, of the surface tension measured.

The Dyne Test Pen is available in a pen format and does not require an applicator. The Dyne Test Pen is a quick test that defines whether a surface has been treated. It is available in a single gradation (38 dyne/cm) and is ideal for quick testing in production environments as it is a more practical, portable and easy to use solution.

• The Dyne Test Pen quickly measures whether a material has been previously corona treated, leaving the surface untouched after the test. In fact, the ink does not penetrate the surface and in case of residual stains, a soft cloth or paper towel with water or a mild detergent may be used to remove them.
• Corona Marker contains a special type of ink that reacts with surfaces, leaving a permanent mark on the tested areas when previously treated with corona discharge.

Considering that most inks and adhesives still have surface tensions above 38, 38 is considered the threshold for accepting or rejecting a substrate.

No, the Dyne Test inks produced and marketed by Ferrarini & Benelli are only available in bottle format.

No, refills are not available.

To ensure accurate test results, it is recommended that inks and markers are used no later than 6 months from the date of opening.

Of course, the composition of the pack is at the discretion of the customer, who can choose to compose the pack with the desired values.

Atmospheric plasma is a process that uses an ionized gas (plasma) to modify the surface of polymers and other substrates. Plasma is created by applying very high energy to a gas - in the specific case of atmospheric plasma, the air we breathe - transforming it into a collection of charged particles. These particles come into contact with the surface being treated, improving adhesion or removing contaminants.

By way of indication, and not exhaustively, we list some substrates and applications:

• Polyethylene (in bottles, containers, components of various shapes)
• Polypropylene (automotive parts and medical devices)
• Polycarbonate (lenses, aircraft parts and electrical equipment)
• ABS (molds, automotive parts and toys)
• Polyamides (cables, mechanical parts and industrial components)
• PVC (profiles for furniture, profiles for window frames)

Plasma can also be used to process: metals, glass, ceramics, textiles and composites (an example of a composite is the combination of a shoe upper and sole).

Compared to other types of treatment, plasma treatment is:

• Green: eliminates the need to use hazardous chemicals and solvents, reducing waste and environmental impact
• Precise: Allows very small areas or surface details to be treated without affecting areas that do not need treatment. This level of precision is difficult to achieve with traditional chemical treatments.
• Effective at low temperatures: useful for heat-sensitive substrates such as polymers
• Fast: fast process that can be easily integrated into production lines without downtime
• Safe: plasma treatment eliminates the risk of operator exposure to hazardous chemicals and toxic agents
• Economically sustainable: reduces costs associated with chemical waste disposal and consumes little energy

• Treatment power: Plasma power affects the density of charged particles and their energy, thus determining their effectiveness.
• Exposure time: exposure to the plasma discharge for an appropriate amount of time is critical.
• Distance between the plasma discharge and the treated surface: this distance affects the uniformity and intensity of the treatment.
• Temperature: the temperature of the substrate and the working environment affect the process and the results of the surface treatment.

Yes, atmospheric plasma treatment is particularly effective for treating objects with irregular geometries. In fact, plasma penetrates hard-to-reach areas and treats irregular surfaces uniformly, saving considerable time and energy. The nozzle may also be mounted on a collaborative robot, ensuring maximum precision in the treatment of details.

The duration of the effect of plasma treatment on plastic surfaces can vary depending on the type of polymer (or other substrate being treated) and the environmental conditions to which it is exposed. Over time, as the substrate is exposed to atmospheric factors and additives migrate to the surface, it is best to perform the treatment directly in-line.

Plasma treatment is safe and will not damage the treated substrate if performed correctly, in line with the instructions in the user manual provided. Periodic maintenance of the treatment system will prevent risks.

Before delivering the plasma system, Ferrarini & Benelli offers a laboratory service for testing the customer's substrate samples. This way, it is possible to determine all the correct parameters in order to optimize the treatment and prevent damage to the substrate.

Done correctly, plasma treatment, in addition to improving adhesion, optimizes the quality of the finished product by improving the treated substrate’s resistance to abrasion, scratches and adverse environmental conditions (such as extreme temperature changes) and by optimizing surface cleanliness.

Yes, atmospheric plasma treatment is considered safe for workers, provided that proper safety precautions are taken, such as the use of PPE and routine maintenance of the equipment. Unlike corona treatment, plasma treatment does not produce ozone.

• Automotive: to improve adhesion of seals, coatings and paints, and to clean surfaces
• Aerospace: Surface cleaning and activation of substrates used in aircrafts
• Medical: Sterilization and surface activation of medical devices
• Packaging: to improve adhesion of inks and adhesives on folding paste lines in carton production
• Textile: to improve adhesion of dyes and coatings to fabrics
• Printing: to improve wettability and adhesion of inks on difficult-to-print surfaces, including allowing the use of water-based, solvent-free inks or digital printing inks

Yes, plasma treatment can contribute to the sustainability of the manufacturing process because it eliminates the use of solvents and toxic chemicals, uses less energy than chemical treatments, and generates no waste for disposal because it does not produce harmful chemical by-products.

To determine if plasma treatment is appropriate for a particular substrate or production process, it is important to conduct a preliminary test in the laboratory to evaluate the substrate properties, define the treatment objectives, and ensure that the system can be integrated without disrupting the existing production process.

Atmospheric plasma operates at atmospheric pressure, so there is no need to maintain a low-pressure environment, as is the case with vacuum plasma, which requires complex and energy-intensive vacuum systems. Very good results can be achieved with only a few kilowatt hours.