CORONA & ALDYNE
Most plastics have a non-polar, electrically well insulating and water-repellent surface. It is poorly wettable by printing inks, solvents, aqueous plastic dispersions, adhesives or adhesion promoters. This is especially true for polyethylene, polypropylene and polyester films. Printing on such plastics (films or spatial bodies) or their further processing by laminating or coating is therefore not possible. The printing inks would not adhere and delamination would occur in the production of composite films.
Corona treatment, the most commonly used form of surface treatment, is a solution to this problem. The aim of this method is to increase the polarity of the surface, which significantly improves wettability and chemical affinity.
Corona treatment provides the necessary basis for the further processing of blown-film material. AFS systems are the classic on the blown film extruder and have been covering every need for years, successfully and worldwide.
Not all film materials can be treated equally well, and for this reason, the corona treatment of PP is especially important. This places particularly high demands on the design of a corona treatment system for PP films.
Extrusion coaters operate at extreme speeds. The corona treatment system must therefore be both reliable and robust. AFS systems show their value.
Good preparation for printing and lamination ensures excellent results.
The increasing use of low-solvent and solvent-free adhesives requires a higher surface energy than in the past. For this reason, placement of a corona treatment inline to the lamination process is becoming more and more prevalent.
Treated material for lamination is often stored for some time before use. During storage, the surface energy decreases because waxes slip-agents diffuse to the outer surface and cover the treated surface.
A relatively low dose then restores the surface energy achieved during the initial film production. For this reason compact corona treatment stations can be installed even in high-speed laminating machines.
Textiles and non-wovens
Hydrophilic or hydrophobic.
Textiles and non-wovens are usually made of woven or spun fibres. The materials are wool, cotton and synthetic fibres. The corona treatment therefore does not take place on a homogeneous surface, but on a variety of surfaces contained within the web.
The aim of the treatment is to improve the absorbency. How effective the treatment is you can tell by how quickly a drop of liquid is absorbed.
The corona treatment must be carried out gently in order not to thermally damage the individual filaments, but intense enough to activate hard to treat synthetic fibres.
This creates the prerequisite for further process steps. Specific coatings adhere and provide a wide range of properties, i.e. flame retardent or water repellent.
AFS pipe-treatment systems are ideal for the treatment of PE pipes, especially of jacketted pipes for district heating. For foaming the inside must be pretreated. For printing the outside must be treated.
District heating pipes transport hot water or steam. For insulation reasons, they are not placed directly into the soil, but embedded in a PE jacket pipe. PUR foam fills the intermediate space.
Double-sided treatment of sheet
Various treatment station designs are available to cover the wide range of rigid and semi-rigid web materials.
Single or double-sided treatment of such materials require special web guidance and an extremely robust design. Although the working speeds are low, the mechanical forces are extremely high.