Flame Treaters for BOPP Line

The flame treatment system for film production involves a mixture generator, with integrated electric panel and operator panel for automation and control of equipment, along with a treatment station unit. The system, designed to work with all common industrial combustible gases, is equipped with automatic ignition and continuous flame detection. It includes safety devices to detect any fault, in line with European regulations.

The system can be amply integrated online to connect with production line machinery, offering the possibility to be managed from the main console. The EsseCI Treatment Station is equipped with a unit for the analysis and continuous control of working mixture composition.

Flame treatment composition

When a flame passes over the surface of a plastic material, it increases the temperature on its outer layers and modifies the surface energy. For both polyethylene and polypropylene plastic film, the thickness ranges from 10-100 microns, the dwell time is in the range of hundreds of millseconds and the material’s cooling capacity is negligible. Consequently, a flame treatment system needs a cooling system first of all.

The system is thus arranged with:

  • A flame burner that produces the suitable treating flame.
  • A treatment roll, duly cooled by circulating water that constitutes the “cold side” of the film passing through the flame.
  • A rubbered nip roll that flattens the film over the treatment roll surface.
Treating WidthAny width is avaible in the range between 1 to 10 m
Mechanical Integration in the production lineYes
Stand Alone ExecutionYes
Burner Frame Cooling SystemYes
Burner Position ControlYes
Burner Profile AdjustmentYes
Burner PolarizationOptional
Hot Air Suction SystemYes
Flame Width AdjustmentOptional
SafetyPlc, Compliant with EN 13849:2006

The burner position can be at the top or bottom of the treatment roll.
The burner produces a constant and even flame along its body, at a length suitable to the film to be treated.
The distance between the burner and the treatment roller depends on certain process parameters such as the film speed, the level of treatment required, type of film, and so on.

Burner FaceAny width is available
Burner ScreenAny screen is available
Burner CoolingWater cooled
Burner PolarizationOptional
Flame Width AdjustmentOptional
Flame treater esseci
Using jackscrews with double shaft at 90° means 2 movements are possible: a spot shaft to compensate for non-linearity and a general one that moves the burner from the rest position to the working position.
Flame treater esseci jackscrews
The treatment roll

The roll’s surface temperature is a fundamental parameter in the uniformity the treated surface.

Poor attention to this component can cause:

  • Irregular temperature along the roller
  • Too great a difference between the roll surface and cooling water temperatures
  • Water flow that is not constant with respect to the roller rotation
  • Difficulty in obtaining high heat exchange coefficients

EsseCi has solved these problems by designing treatment rolls with an active radial system in which the distribution of cooling water in the input and outlet positions is able to almost completely compensate the centrifugal force. Moreover, a labyrinth system guarantees the uniformity of the surface temperature along the entire roll surface.

Roll FaceAny width ranging from 1 to 11 m
Roll DiameterFrom 270 to 800 mm
Water Circulation1 double or single rotary joint execution
Delta TMax. 3° C along the entire surface length
Flame treater esseci treatment roll
Nip roll

The nip serves to achieve a flat film on the treated roll surface, free from bubbles or air trapped beneath the film, wrinkles or any other mechanical defect on the film exterior. The pinching against the treatment roll must be uniform and constant, whilst the nip roll dynamic profile must reflect the dynamic profile treatment roll.
The outcome depends on the static and dynamic balancing of both rolls and on the position of the nip roll in respect of the treatment roll. The best position is that shown in Image 1, where the nip roll is slightly over the treatment roll and the nip roll surface is straight. Different positions could involve using a bowed nip roll profile (bombeè), in order to compensate the arrow due to the weight of the nip itself.

Roll FaceAny width ranging from 1 to 11 m
Roll DiameterFrom 80 to 560 mm
SurfaceRubber coated, with or without crowning
Surface HardnessTypically 55-65 ShA
Flame treater esseci nip roll
The mixture generator

Several tests have proven that the best flame for plastic material treatment is an oxidising flame in which a small quantity (0.5-3 %) of free oxygen is present. The simplest system to achieve such a flame is the pre-mixer set-up, just like a car carburettor. Once you find the right balance between air and gas, the issue then becomes how to maintain this ratio over time.

Today, generators designed and created by EsseCi to produce combustible mixtures (gas/air) necessary for feeding the burner are made from a gas supply tube and a fan that sucks air from the environment, pushing it inside a venturi that contains the air and gas mixer. Once the mixture has been formed in a controlled composition and quantity, it is sent to the Esseci burner on the Treatment Station. The flow of gas necessary to obtain an established ratio and quantity of gas/air mixture for the flame treatment is regulated by means of the special GOG device and the GCV1 valve, driven by the Jonoflame J combustion analyser through the TIC1 temperature regulator. The Jonoflame analyser is composed of a combustion chamber in which a small amount of the gaseous mixture, directed towards the burner, feeds a burner nozzle. To ensure proper operation, the mixture pressure sent to the nozzle must be controlled.

This system permits real time control of the mixture composition used, expressed in terms of a temperature. This combustion temperature is in fact calculated on the basis of the air/gas mixture ratio; the higher the combustion temperature, the richer the mixture is in gas. Mixtures that contain an excess of air (lean gas mixtures) produce flames in the Jonoflame that are transparent violet in colour, whilst gas rich mixtures generate flames in the Jonoflame with a greenish hue that appear surrounded by mist.

Mixture Flow CapacityRange between 150 and 1800 m3/h
Gas SupplyAny gas can be used
Power SupplyAny power supply can be used
Mixture Flow ControlYes
Air-Gas ratio ControlYes
Air DehumidifierOptional
SafetyPlc, Compliant with EN 13849:2006
Flame treater esseci mix generator
Flame treater esseci mix generator
Cooling Unit

The roll and burner cooling systems consist in a closed circuit in which a pump is sized so as to circulate the right amount of water within the unit. The circuits are connected to the temperature control systems in order to keep it constant. The cooling medium is water, which may originate from the tower, shaft or chiller. The water is sent to a heat exchanger through an automatic control valve.

Loop Water Flow CapacityRanging from 4 to 100 m3/h
Net Water SupplyChilled water 12-16 °C; Tower water 25-35 °C
Power SupplyAny power supply can be used
Loop Water temperature ControlYes
SafetyPlc, Compliant with EN 13849:2006
Flame treater esseci cooling

The adhesion test (measurement of the wettability tension or treatment level) are made by means of liquid solutions having known surface tension according to the international ASTM D2578 method, being the most common and universally used. In practice, it is applied with a cotton ball a thin layer of liquid solution on a surface that has only been partially treated. The liquid on the treated area extends like a veil, whilst the liquid in the non-treated area tends to form droplets.

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