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Automotive Plastic Coatings in Europe
Published in Rose A. Ryntz, Philip V. Yaneff, Coatings Of Polymers And Plastics, 2003
Hans Christian Gruner, Klaus-Werner Reinhart
sional geometry, cannot be sufficiently treated. Typical defects are poor paint adhesion, for example, on bumpers in lamp-openings or grille areas due to deviations in positioning of the skids to the flaming robot. Therefore, for optimum results, most painters often combine flaming with use of an adhesion-promoting primer (usually chlorinated polyolefin). Once the process is established by pre-trials and testing, the flame treatment provides optimum adhesion to meet even the toughest specifications and the primer ensures good adhesion for performance in practical use even on zones not treated properly.
Electron Beam Processing of Rubber
Published in Anil K. Bhowmick, Current Topics in ELASTOMERS RESEARCH, 2008
Rajatendu Sengupta, Indranil Banik, Papiya Sen Majumder, V. Vijayabaskar, Anil K. Bhowmick
Other direct methods of oxidation have also been used to modify polymer adherends effectively. With flame treatment [211,212] in air, an oxidizing flame briefly impinges on the surfaces. XPS analysis [213] has shown that amide surface groups are generated as well as typical oxidation functionalities. Biaxially oriented films of PP and PET have been surface modified with this treatment [214]. XPS analysis shows that the polymeric surfaces are rapidly oxidized, attaining XPS O/C atomic ratios on PP of greater than 0.10 in less than 0.5 s. PP surface is chemically modified to render it hydrophilic using ArF excimer laser radiation [215]. It is considered that H atoms are selectively pulled out from the area irradiated with ArF excimer laser light and are replaced by OH functional groups in the presence of water. In this treatment, the irradiated sample becomes hydrophilic with enhanced adhesion properties. The treated PP and stainless steel bonded with epoxy adhesive shows a tensile shear strength of 4.6 MPa. Polyimide films have also been surface modified using ArF excimer laser and Xe2* excimer lamp irradiation [216] in an atmosphere of CF4. In this treatment, the contact angle of water is increased to 134° as compared to the original 58°. CO2 pulsed laser-induced surface grafting of acrylamide onto EPR in the presence and absence of sensitizers, investigated by Mirzadeh et al. [217,218], produces bio- and water compatible polymers. Water compatibility has been evaluated by measuring water drop contact angle. Breuer et al. [219] have carried out photolytic surface modification of PP with UV laser. On the basis of such activation, a significant enhancement of the adhesive bond strength between a polymer and an adhesive (in this case epoxy resin) has been achieved. Pulsed UV lasers and ArF excimer laser at 1934 nm have been used for surface modification of polymer surfaces, nanostructure fabrications on polymers and diamond deposition using photoablated polymer plumes [220].
Joining Technologies
Published in Raghu Echempati, Primer on Automotive Lightweighting Technologies, 2021
These are techniques where the surface is cleaned and chemically modified by exposure to highly energetic charges or other ionic species. The most common methods are flame treatment, corona discharge, and plasma. These pretreatment methods have been applied to metals and, in particular, composites and plastics. Flame treatment of the substrate surface for just a few seconds with an oxygen-containing (blue) propane or acetylene gas flame leads to the incorporation of oxygen-containing groups at the surface. This improves the wetting properties and, hence, the adhesion. Flame treatment is used almost exclusively for polyethylene and polypropylene substrates. The effect of the pretreatment subsides within a short time so that flame-treated substrates must be bonded immediately.Reference [43] shows the photograph of a corona discharge, which is essentially plasma generated in air at atmospheric pressure by applying a high frequency and high voltage between two electrodes. It contains a number of energetic species that can clean and introduce polar groups, mostly oxidation products, at the substrate surface. The corona discharge may also lead to crosslinking of the polymer surface. The pretreatment effects are shortlived. So. bonding should be carried out immediately. It is used mainly for polyolefin films and is capable of high processing speeds.Plasma cleaning is another method which is usually generated in a low-pressure chamber and so is best suited to batch processing. Commercial units of various sizes are available. The advantage of this method is that it allows treatment of substrates by plasmas of gasses other than oxygen, for example, argon, ammonia, or nitrogen. Plasmas created from inert gases are generally used to clean substrate surfaces.
Adhesion testing of printed inks while varying the surface treatment of polymer substrates
Published in The Journal of Adhesion, 2021
Clayton Neff, Edwin Elston, Amanda Schrand, Nathan Crane
Chemical treatments can be readily integrated into a multi-tooled AM machine with the use of micro-pen flame torches or plasma pens. Flame treatment only shows a marginal improvement in adhesive strength with the parameters in this work. Higher temperature polymers may show more benefit from flame treatment as the treatment could be more intense without deforming the substrate. Modifications to the heating parameters could also increase the benefit while use of a torch with a forced continuous flow or a wider flame may increase treatment consistency. Plasma treatments of one, five, and 10 min show equivalent shear strengths when deposited on the gloss side of the ABS substrates. This suggests that the shear strength increase has plateaued and perhaps a shorter treatment time could be used to achieve an equivalent shear strength. Furthermore, a combination of mechanical features and a chemical surface treatment could provide maximum adhesion with benefits from mechanical interlocking and surface chemistry changes. For instance, a knurling tool that is being torched as it is being rotated could provide a texturized surface with adhesion promoting surface chemistry changes.