Corona-discharge treatments

Uehara, T., Corona discharge treatment of polymers. In Mittal, K.L. and Pizzi, A. (Eds.), Adhesion Promotion Techniques — Technological Applications. Dekker, New York, 1999, pp. 191-204. 

Corona discharge treatment results in the formation of high-polarity functional groups, such as carbonyl, at the polymer surface. Various mechanisms have been proposed for the improvement of the adhesive properties... 

Figure 14 Carbonyl index as a function of corona discharge treatment of PP film. Reproduced with permission from Sellin and Campos [39].

In this technique, radio-frequency corona discharge treatment was first used to create oxygen-rich moieties on a polyethylene (PE) substrate [22,23]. The... 

The surface modification of polymers for improvement of adhesive bonding, and altering surface properties in general without concomitant modification of bulk properties is an active area of research in both industrial and academic laboratories and has been accomplished by a variety of means ranging from Corona discharge treatment, direct chemical modification and by interaction with plasmas excited in inert gases either capacitively or inductively27. ... 

Following the corona-discharge treatment of a silicone surface and the subsequent graft polymerization of AAc, type I atelocollagen was immobilized onto the grafted surface with the use of water-soluble carbodiimide [176, 177]. As depicted in Fig. 17, the immobilization reaction involves two steps, i.e., activation of carboxylic acids and the following nucleophilic substitution with prima-... 

Fig. 9 XPS Cl s core-level spectra of ungrafted and HEMA-grafted LDPE films with copolymerisation times of a 0 h and b 2.0 h (72 s corona discharge treatment time, 15 kV corona discharge voltage, 50 °C copolymerisation temperature, 5% HEMA concentration)...

Some additives can interfere with the effects of others—like titanium dioxide diminishing the usefulness of slip agents—and many of them influence the efficiency of corona discharge treatment. The results vary with the additives concerned and with their concentration.19 The presence of additives on the surface will screen the film against the effects of the discharge, while difficulties may be caused after treatment when additives migrate to the surface (it is intended that they should so do) and impair in consequence the keying of ink. 

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. 

Journal of Applied Polymer Science 81, No.10, 6th Sept.2001, p.2419-25 CORONA DISCHARGE TREATMENTS OF PLASTIFIED PVC SAMPLES USED IN BIOLOGICAL ENVIRONMENT Dumitrascu N Borcia G Popa G Jassy,Cuza A.I. University... 

In order to increase the moisture resistance of cardboard (wood product) the extrusion coating of polyethylene (PE) is often applied on the surface of the cardboard. In order to make the surface of PE-coated cardboard printable, the corona discharge was applied on the PE surface. The PE coating as well as the corona discharge treatment is applied in line at the site of cardboard manufacturing. PE-coated cardboards with printable surface manufactured in Canada were shipped to a customer in Japan after printability of the treated surface was confirmed. 

Pure ozone for ozonolysis of OA was generated from pure carbon dioxide by electric corona-discharge treatment, thus offering an industrially affordable process [65]. 

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