Магистерская диссертация тема работы Разработка цифрового двойника технологического процесса с использованием производственных данных

1.6.3 Flame treatment

The flame treatment has the same function as corona treatment.

Flaming consists of exposing the surface to be decorated to a suitable oxidizing flame for a period in the range of 0,2 to 3,0 seconds. This treatment brings about a change to the polymer surface that makes it wettable and permits a strong adhesive bond between the film surface and the coating. This change in surface properties can be readily seen by immersing an untreated and treated film in water.

On removal, the water will run off in globules from the untreated surface but will form a continuous film on the treated surface which will last for a varying length of time depending on the present flaming conditions used.

The following major parameters should be monitored for effective flaming conditions:

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  Gas/air ratio: it depends on the type of gas used (town gas, methane, propane, and butane are suitable). A laminar flow flame is preferable to the turbulent flame.
  

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  The distance of the burner to the film surface.
  

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  The residence time of the film in the flame.
  

It has been established that the gas/air ratio is the most important and critical factor in flame treatment. The importance of control over this parameter cannot be overstressed and the gas/air flow must be maintained at a pre-determined level.

The effect of incorporating antistatic additives depends on the type of additive used, its concentration, and the type of flame treater. Additives, which by their diffusivity and compatibility characteristics, become active immediately after processing, demand more critical flaming conditions, and can give rise to difficulty if used at higher concentrations than those recommended. The level of addition at which difficulty is encountered in achieving acceptable print adhesion dependents on the type of burner used for treatment. Most anti-static additives are only effective after flaming, and these additives do not affect on the flaming conditions necessary for acceptable print adhesion.

1.6.4 Nip rolls

Tension isolation between TDO and winder is provided by nip rolls on the treater stations. It is important to have a controlled tension between TDO and inside treater, between inside and outside treater, between outside treater and pull rolls and pull rolls to winder otherwise the winder will pull the film through the trim removal section and cut the web on blades.

Attached to every corona treatment roll there is a nip roll to prevent slipping of the film on the rolls. Thus, the winder cannot pull the film through the pull roll stand. Moreover, the proper nip roll operation is essential for the elimination of reverse treatment created by air between the film and the corona roll.