Table of Contents
Introduction
In the world of blown film extrusion, achieving high-quality
output The film’s performance is often dependent on the successful interaction
of its surface with adhesives, coatings, and inks. This is the point at which
Corona treatment is implemented. By increasing the surface energy of the film,
corona treatment ensures better adhesion and printability, making it a
necessary process in modern packaging and film applications. This article
explores the science, benefits, and practical considerations of corona
treatment in blown film extrusion.
What is Corona Treatment in Blown Film Extrusion?
Corona treatment is a surface modification technique used to
enhance the surface energy of films produced through blown film extrusion. It
involves exposing the film’s surface to a high-voltage electrical discharge,
which modifies its properties to improve adhesion with coatings, inks, and
adhesives.
This treatment is crucial because most polymer films, like
polyethylene and polypropylene, have inherently low surface energy, making them
resistant to adhesives and printing materials unless properly modified.
How Corona Treatment Works for Blown Film Extrusion:
Corona treatment for blown film extrusion is a surface modification process used to improve the printability, coatability, and adhesive bonding properties of plastic films. The gap between the corona treatment electrode and the sleeve roller in blown film extrusion typically ranges from 1.5 to 3 mm.
Maintaining the correct gap is essential for consistent and effective corona treatment, leading to improved product quality and performance.
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Corona treatment for blown film extrusion |
The Science Behind Corona Treatment: How Does It Work?
1. High Voltage:
A high voltage is applied to electrodes near the film surface
2. Ionization of Air:
A high-voltage electrical field is established across the electrodes. It created a strong electric field in the air around the electrodes. The extreme electric field removes electrons from neutral air molecules like oxygen (O₂) and nitrogen (N₂). Positively charged ions and free electrons are formed during this process.
3. Plasma Formation:
The ionized air forms plasma, a partially ionized gas containing charged particles.
4. Surface Modification:
The blown film passes through this plasma field. The surface of the plastic film is bombarded by these charged particles.
5. Increased Surface Energy:
This bombardment modifies the chemical composition of the film surface, introducing polar groups (like hydroxyl groups) that were not present before. This substantially increases the surface energy of the film.
Key Components of a Corona Treatment System
A Corona treatment system generally includes
Power Supply: Generates the high voltage
required for Corona discharge.
discharge to the film’s surface.
flow and reduces sparking
Rollers: Support the film during
treatment, ensuring smooth contact.
Types of Electrode:
Conclusion of Electrode:
Sleeve roller and sleeve material:
Sleeve roller:
Sleeve:
Key Point to Remember:
The gap between the electrodes and the sleeve roller is critical for the most efficient corona treatment performance.
Silicon rubber is the preferred material for sleeves due to its excellent insulating properties and temperature resistance.
Challenges and Maintenance
Common Challenges in Corona Treatment Systems
Tips for Maintaining Optimal Corona Treatment Performance
Regular Cleaning: Clean electrodes and rollers regularly to remove dust and junk.
Conclusion
Corona treatment serves a crucial purpose in optimizing the performance of blown film by enhancing its surface energy. This process ensures that films are more suited to adhesives, inks, and coatings, ultimately elevating product quality and market value. By understanding the science, applications, and maintenance of corona treatment, manufacturers can maximize its potential and deliver superior results in blown film extrusion.
Note: Read more about corona treatment.
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