The answer to this question is much like an earlier post on handling mono and biax oriented films. The coating and drying processes are straight forward and should be easily applied to CPP or other “weak” films. The goal is to coat and dry without exceeding a couple of key film parameters. First and foremost we need to know the tensile properties of the film so we know the mechanical limits of the film. Second we need to measure the heat shrinkage profile of the film so we don’t exceed the thermal limits of the film and thirdly we need to measure the tensile properties of the film at the drying temperature so we don’t stretch it in the drier.
Once these tensile and thermal film property parameters are know it is a straightforward engineering problem to design a coater / drier within the constraints of the film. If the coating head will be driven and if the film needs to be nipped at the coater then perhaps the nip should be driven as well and perhaps the film cannot tolerate the force from a reverse direct gravure system. Therefore, a different coating method is needed which can work without applying too much stress to the film. Perhaps an air knife or Myer rod coater is necessary instead of a gravure coater. At any rate the optimum coating method compatible with the films properties has to be determined. Once the coating method is determined then the web transport system can be engineered for the film.
As far as drying goes, it is straightforward to determine the maximum temperature we can apply based on the film shrinkage properties and the tensile strength at the maximum temperature so determined. These factors relate back to the sizing of the drive and the characteristics of the transport rolls and drive. The drying temperature and the mass transfer coefficient for the drying nozzles will also determine the length of the oven needed to run at a defined line speed. Mass transfer and heat transfer coefficients are controlled by the dryer nozzle design and air flow rates.
This is how you would start from scratch. However, I think the real thrust of the question was how to do it “on my coater” which I already have and have to use. In this case the approach is the same except we also have to determine what the characteristics of the coater are. We have to measure the turning force of the rolls and “fix it” if it is too high. We have to consider the coating head and if it is incompatible with the film strength re-engineer it for the film. The same for the dryer, it might be it runs “to hot” for the film and if so we will need to change the temperature range in which it works (I once had a gas oven where the pilots for the burner delivered too many BTU’s and we had to change burner pilots). Once the drying temperature is controllable at the proper temperature in the dryer, then the maximum line speed can be determined for a given coating weight and solvent loading. If it is to slow then additional drying length will have to be added or the mass transfer coefficient increased with increased air velocity.
In almost any instance it is possible to engineer your way to a successful conclusion. Then the question is can we make enough product to supply customers and what is the cost of doing the coating and this determines the margin and the ROI of the product.