Corona treatments

A few papers have reported that cellulose-based natural fiber surfaces can be modified with corona treatment and that the resulting polymer composites exhibited the improved properties through the surface modification of natural fibers [102,103]. 

---

Adhesion of paints and adhesives to TPOs is especially problematical due to the aliphatic nature of the substrate material. In Europe, plasma and corona treatment is employed to render these surfaces wettable and obtain strong adhesion by adhesives and paints in automotive manufacture. In the United States, however, primers based on solvent-borne chlorinated polyolefin oligomers (CPOs) have become the treatment of choice for these substrate materials. The VOC emissions from these primers are considerable (as in all solvent-borne adhesives), but the less... 

Gas plasma treatment operates at low pressure and relatively low temperature. While the corona treatment is applicable to substrates in sheet or film form, the gas plasma process can treat objects of virtually any shape. The gases most widely used to generate plasma by free-radical reactions include air, argon, helium, nitrogen, and oxygen. All these, with the exception of oxygen. 

Electric discharge (corona, cold plasma) is another method of physical treatment. Corona treatment is one of the most interesting techniques for surface oxidation activation. This process changes the surface energy of the cellulose fibers [28]. In the case of wood surface activation it increases the amount of aldehyde groups [291. 

Some physical techniques can be classified into flame treatments, corona treatments, cold plasma treatments, ultraviolet (UV) treatment, laser treatments, x-ray treatments, electron-beam treatments, ion-beam treatments, and metallization and sputtering, in which corona, plasma, and laser treatments are the most commonly used methods to modify silicone polymers. In the presence of oxygen, high-energy-photon treatment induces the formation of radical sites at surfaces these sites then react with atmospheric oxygen forming oxygenated functions. 

Atmospheric corona discharge has been used to increase the surface energy of wood surfaces by oxidative activation (Back and Danielsson, 1987). Improved bonding of a water-based acrylate lacquer was found following corona treatment of the wood surface, with no improvement found when a solvent-based alkyd system was used. 

Podgorski, L., Chevet, B., Onic, L. and Merlin, A. (2000). Modification of wood wettability by plasma and corona treatments. International Journal of Adhesion and Adhesives, 20(2), 103-111. 

Surface-Grafted Polymers Through Corona Treatment. 59... 

In general, Ecoflex and Ecovio can be printed and welded on standard equipment for PE-LD. Both alcohol-based or water-based inks can be used after testing. Prior to printing, the material has to be corona-treated if the surface tension is below 38 dyn. In most cases printing of Ecoflex and Ecovio using alcohol-based inks does not require corona treatment. The drying temperatures should be kept below... 

Instead of the simultaneously extmded polymer film, a pre-extmded or laminated film can be laminated on the substrate (e.g., paper or paper board). In this case, the extruder can be used to extrude the polymer providing adhesion (e.g., Ecoflex ) in a thin layer between the polymer coating film or laminate and the substrate. Another option is to apply a dispersion or heat in the laminator (Fig. 10, 4) to obtain adhesion. After thickness measurement and second subsequent corona treatment, substrate and polymer coating are wound on a winder (Fig. 10, 6) in order to obtain rolls for transport to subsequent processes (e.g., printing, cutting, cup forming, box making). 

THV Fluoroplastic can be readily bonded to itself and to many plastics and elastomers and unlike other fluoroplastics does not require surface treatment, such as chemical etching or corona treatment. However, in some cases tie layers are required to achieve a good bonding to other materials.92... 

P. B. Sherman, Additive influence on corona treatment, TAPPI Film Extrusion, 1991. 

In order to obtain sufficient adhesion of printing inks on PE surfaces, oxidation of the surface must take place. This can be accomplished either with flame or by corona treatment. Significant off-odors can be produced as a result of the oxidation process. In particular unsaturated ketones and aldehydes are implicated in these off-odors (Chapter 13). 

There are many different methods for modifying polymer surfaces to improve their adhesion and wetting properties. They include chemical etching and oxidation, ion bombardment, plasma treatments, flame treatment, mechanical abrasion and corona-discharge treatments (1.2). Especially flame and corona treatments are widely used for the modification of polyolefin surfaces to enhance, for instance, their printabilify. Despite the widespread use of such processes in industry, the understanding of the fundamental processes which occur at the polymer surface is very limited. This is undoubtedly due to the shallow depth to which the polymer is modified, typically 5 nm or less. 

---