Surface modification corona discharge

Several environment-friendly surface preparation for the treatment of mbber soles with radiations have been recently studied. These treatments are clean (no chemicals or reactions by-products are produced) and fast, and furthermore online bonding at shoe factory can be produced, so the future trend in surface modification of substrates in shoe industry will be likely directed to the industrial application of those treatments. Corona discharge, low-pressure RF gas plasma, and ultraviolet (UV) treatments have been successfully used at laboratory scale to improve the adhesion of several sole materials in shoe industry. Recently, surface modification of SBR and TR by UV radiation has been industrially demonstrated in shoe industry... 

Romero-Sanchez M.D., Pastor-Bias M.M., Martm-Martmez J.M., Zhdan P.A., and Watts J.M., 2001, Surface modifications in a vulcanized rubber using corona discharge and ultraviolet radiation treatments, J. Materials Sci., 36(24), 5789-5799. 

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. ... 

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. 

With the help of complementary surface analysis techniques such as XPS, Static SIMS and AES, we have been able to show how a short (23 msfilms leads to a slight oxidation of the surface as well as to the formation of N2 containing species. These modifications are necessary for the improvement of the adhesion observed with a scotch-tape test. However, the presence of oxygen is not the only factor responsible for a good adhesion, since the AES profiles of die deposited aluminium, show the same oxidized interface in the case of the non treated metallized polymeric film. The films are pretreated in a corona discharge configuration (hollow electrode-grounded cylinder) and the aluminium is deposited onto the film in situ. 

Surface modification of a polymer prior to metallization is widely used to improve adhesion. The most common surface modifications employed are electric discharge (corona and plasma) and, more recently, ion-beam treatments QJ- Several mechanisms have been proposed for the improved adhesion after such surface modifications (2). These include mechanical interlocking, the elimination of weak boundary layers, electrostatic attractions, and chemical bonding. All of these can play a role in adhesion depending on the surface modification used, metal/polymer system, type of metal deposition, and the extent of polymer preparation employed. However, for low power, short exposure modifications, the formation of new chemical species which can provide nucleation and chemical bonding sites for subsequent overlayers is considered to be of prime importance (3-51. 

Physical methods include plasma treatments, UV irradiation, corona discharge, and flame treatment. Among these, plasma treatment is widely used for the surface modification of synthetic polymers. Plasma can be obtained by exciting gases into an energetic state by radio frequency, microwave, or electrons from a hot filament discharge. Generation of plasma requires a vacuum, which normally poses several... 

As a special source of particles, low-temperature plasmas are included in this section, which strictly speaking are sources of ionized atoms or molecules as well as photons and electrons that all may interact with the polymer. In addition to well-established low-pressure plasma sources, corona discharge or recently developed atmospheric pressure plasma sources may be used for surface modification. 

The practical aspect of the iPP surface modification by the corona discharge can be demonstrated on the adhesive properties of modified and unmodified iPP carp>et fabrics treated by rubbing pastes based on butyl acrylate-vinyl acetate copolymer. The results are summarized in Table 1. According to Table 1 the value of mechanical work of adhesion towards PP is rising with the increase of the rubbing paste mass. 

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