Flame Treatment For Film Production

The flame treatment system for film production is composed by a mixture generator, with integrated electric board and operator panel, for automation and control of equipment, then, the treatment station unit. The system, designed to work with all common industrial combustible gases, is equipped with automatic ignition and continuous detection of flame. It includes safety devices to detect any fault, as from European rules.

The system permits a wide integration, via network data, with the machinery of the production line, where it will be installed in, by giving possibilities to be managed from the main console. EsseCI Treatment Station is equipped with a unit of analysis and continuous control of working mixture composition

Flame treatment composition

When a flame passes over a plastic material surface, produce an increasing of temperature on its boundary layers, and a modification of the surface energy. For the plastic film, both polyethilene and polypropylene, the thickness is in the range 10÷100 microns, the dwell time is in the range of hundreds of seconds and the cooling capacity of the material is negligible; conseguentely a flame treatment system needs first of a cooling system. The system is then arranged in this way:

  • A flame burner that produce 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 nip-roll, duly rubbered, that provide the flattering of 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
Burner

The burner position can be at the top as at the bottom of the treatment roll.
The burner produce a costant and even flame along its body, of a lenght suitable to the film to be tratment.
The distance between the burner and the treatment roller depends on some process parameters such as the film speed, the level of treatment required, type of film, etc..

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 ° is possible to obtain 2 movements: a local for the compensation of non-linearity and a general that moves all the burner from the rest position to the working position.
Flame treater esseci jackscrews
The treatment roll

The surface temperature of the roll is a fundamental parameter involved in the uniformity of the treatment achieved on the treated surface.

Poor attention to this component can cause:

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

EsseCi has solved these problems by designing treatment rolls so that the distribution of cooling water in the inlet and outlet positions, using an active radial system, is able to almost completely compensate the centrifugal force; moreover a labyrinth system guarantees the uniformity of the surface temperature along the roll surface.

Roll FaceAny width is available in the range between 1 to 10 m
Roll DiameterAny diameter is available in the range 270 to 800 mm
SurfaceChrome Plated
Water Circulation1 Double or single rotary joint execution
Delta TMaximun 3 °C along the entire face length
Flame treater esseci treatment roll
Nip roll

The fuction of nip is to achieve the film flat on the trater roll surface, without bubbles or air trapped under the film and without wrinkles or any other mechanical defect on the film surfacd. The pinching against the treatment roll must be uniform and costant and the nip roll dinamic profile must be copy the treatment roll dimanic profile.
This result depends on the static and dinamic balancing of both rolls aand on the position of the nip-roll respect the treatment roll: the best position is that shown in the fig. 1, wherethe nip roll is slighrly over the treatment roll and the nip roll surface is straight. Different position could require a nip roll profile bowed (bombeè), in order to compensate the arrow due to the own weight of the nip.

Roll FaceAny width is available in the range between 1 to 10 m
Roll DiameterAny diameter is available in the range 80 to 560 mm
SurfaceRubber coated, with or without crowning
Surface HardnessTypically 55-65 ShA
Flame treater esseci nip roll
The mixture generator

Several test proved that the best flame for treatment of plastic materials is an oxiding flame, that is a flame where free oxygen is present in small quantity (0,5 -3 %). The simplest system to get such flame is the pre-mixer arrangement, like in a car carburator. Once you find the right balance between air and gas the problem has always been how to maintain this ratio over time.

Today the generator designed and realized by EsseCi, to generate combustible mixture (gas/air) necessary for feeding the burner, it is made from a gas supply pipe and a fan that sucks air from the environment, pushing it inside a venturi. In the venturi is the mixing between air and gas. The formed mixture, controlled in composition and quantity, is sent to the burner Esseci on Treatment Station. The flow of gas that is necessary to obtain an established ratio and quantity of gas/air mixture for flame treatment is regulated by means of the special GOG device and the GCV1 valve, driven by the Jonoflame J combustion analyzer through the TIC1 temperature regulator. The Jonoflame Analyser is composed of a combustion chamber where a small part of the gaseous mixture, directed to the burner, feeds a burner nozzle. To ensure proper operation, the mixture pressure sent to the nozzle must be controlled.

This system it enables the control, in real time, of mixture composition used, expressing this in terms of a temperature. This combustion temperature is in fact calculated on the basis of the air/gas mixture ratio; the higher is the combustion temperature and the richer in gas is the mixture. Mixtures that contain an excess of air (gas lean mixtures) produce flames in the Jonoflame trans- parent violet in colour, while gas rich mixtures generate flames in the Jonoflame that tend to a greenish colour and that appear surrounded by mist all around themselves.

Mixture Flow CapacityDifferent capacities are available in the range between 150 and 1500 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 are constituted by a closed circuit in which a pump is sized so as to circulate the right amount of water in the unit. In circuits are connected to the temperature control systems, in order to keep it constant. The cooling medium is water which may come from the tower, shaft or chiller. The water is sent to a heat exchanger through an automatic control valve.

Loop Water Flow CapacityDifferent capacities are available in the range between 4 and 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
VERIFICATION OF THE RESULTS OBTAINED

The adhesion test (measurement of the wettability tension or the level of treatment) are made by means of liquid solutions having known surface tension according to the international method ASTM D2578 which is the most common and used universally. In practice it is applied with a cotton ball a thin layer of liquid solution on a surface partially treated and partly not; it is evident how the liquid in the treated area extends like a veil, while in the area not treated the liquid tends to form droplets.

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