Pietro Mandoloni, sales manager at Esseci, advocates flame treatment as the best method for film production
Among different treatment methods such as flame, corona, vacuum plasma, atmosphere plasma, UV and primer, the most popular and widely used systems on the market are flame and corona.
Around three decades ago, corona treatment was used more because of its simple technology and low costs, and the performance needed by the market then was limited compared to today. In fact, production speed was, at that time, limited to 150m/min on web widths of 2-3m, while the treatment level was not more than 38dyne/cm.
Contrary to that, today we are getting speeds on BOPP lines of up to 550m/min, while on converting lines up to 1000m/min, on web width up to 10m and with treatment level in the range of 42-55 dyne/cm.
Besides, the market is demanding film with stable adhesion over time, with no backside treatment to avoid any possible blocking, or printing and coating problems.
Under these running conditions, corona has big limitations. Moreover, atmosphere plasma, which is an improvement of such technology, also falls short of expectations. The only system that can meet such performance requirements is flame treatment.
The only limit of flame treatment 20 years ago was treating sensitive films. But this problem was overcome later by improving the technology with an efficient exhaust system to remove the combustion heat, with a reliable treater chill roll to cool down the film during the passage over the flame and with the introduction of polarization to improve the contact between film and chill roll surface.
Special attention was also dedicated to the design of burner grid to avoid surface defects when treating co-extruded and white opaque films at high dyne levels.
Other interesting applications of flame treatment are on paper or aluminium foil on extrusion coating lines, where it is very important to cool down or warm the paper, according to different grades and thickness. Also in this case the flame method gives better adhesion, increases production speed, and saves polyethylene layer and temperature extrudate.
All kind of films and paper can be treated with flame treatment under severe safety conditions, while corona is a dangerous system because it uses high voltage. For example, in tropical countries where the humidity is very high, flame treatment has no problem to run, while corona has some risk and is not completely safe.
Moreover, flame treatment does not produce ozone, fumes, and residual gas. It can be used for flexible packaging on extrusion coating lines where the speed is in the range of 400-600m/min or even more. In such lines, usually a first flame treater is installed prior to coating in order to improve surface adhesion on paper, and then a second flame treater is added after the extruder to treat the coated surface for printing or for lamination.
The market trend is to increase line speed and surface adhesion in order to have good bonds and avoid delamination in the packaging complex. Besides, it is possible to treat the printed surface and reduce or eliminate the primer and limit the costs and pollution.
The technology used in flame treatment is integrated in the production line and all controls, adjustments and reading of running conditions are well visible on a control panel located near the station, for easy operation.
What’s more, it can run without presence of an operator and the life of its components lasts over 20 years. It’s no wonder that so many companies today use polarized flame treatment manufactured by Esseci in applications such as BOPP films plain, coex, white opaque, synthetic paper, PET, PVC, paper, aluminium for printing, coating, metallization and lamination.
Esseci has installed more than 950 treaters in 48 countries and organizes international conferences in Italy and the USA on the latest technology and new applications of flame treatment.
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