We have 2 metallizer in our company. We have faced the metal peeling off problem. We have -20oC cooling in our chill drum and using the gas wedge also. After metallizing we measuring the temperature its 40oC . How to reduce the output roll temp? Waiting for your reply.
Answer
There are a number of aspects to your problem.
In general if you cool down the deposition drum from -20 Deg C to -30 Deg C the final temperature could be expected to reduce by a similar amount from 40 Deg C to 30 Deg C.
This reduction of the drum temperature may not be possible; it depends on the cooling capacity of the system.
A second method of improving the cooling is to increase the gas flow to the gas wedge. The heat transfer coefficient is dependent on the volume and pressure of gas trapped between the film and drum. The higher the trapped pressure the more gas collisions on both the hot film and cold deposition drum and so the higher the heat transfer coefficient.
Again this might not be possible in your system as there will always be a proportion of the gas the leaks out of the edge of the film as it passes around the deposition drum and this has to be pumped away. IF you increase the gas into the wedge the leaking gas might take the chamber pressure higher that you would like for your metal deposition process.
A final possibility is to replace one of the standard rolls following deposition with a cooled roll. This needs to be chosen well as it not only requires the roll to be cooled but also the film has to have sufficient wrap around the cooled roll to take benefit of the cooling. If the wrap is too short there will not be sufficient time to remove enough heat to make a significant difference to the temperature.
This final solution does require changing the winding system and requires an additional leadthrough for a further cooling liquid.
If the metal coating is flaking off this is more indicative of not having the right level of adhesion rather than it being a problem of overheating. Adhesion can be poor because of too little or too much plasma treatment. Have you optimised the plasma treatment on the film?
If not I would suggest that this might be more useful than reducing the temperature of the final roll alone. The roll is not very hot it is warm and so I would have thought it unlikely that reducing the temperature is going to make too much difference to the metal adhesion. I would suspect that even after increasing the cooling the metal would still be prone to peeling off. Check what type of plasma treatment is done, is it argon, argon/oxygen and has it been optimised for that grade of film? If the process has not been optimised it could easily be either too little or too much and giving the poor adhesion. The treatment can be too much where the surface energy would be reading a high value but the surface damage would be enough to generate low molecular weight chain fragments that the metal would adhere to but where the low molecular weight material is no longer well bound to the polymer film.
I hope these suggestions help.
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