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[Eldridge M Mount III]

Does the temperature gained on the surface of the BOPP film after metallising ,cause a rapid reduction in treatment? Is it necessary to have a minimum dyne level of 36 on metallised BOPP to laminate it to polyester?

In general, the surface energy of the aluminum surface is high and stays high if kept clean and free of contamination. Decreases in aluminum surface energy are due to transfer of additives from the unmetallized OPP surface to the metal surface while wound in the roll. Because the bloom of additives to the surface of OPP films is driven by heat, I would assume that warmer rolls exiting the metallizer may indeed accelerate the bloom and transfer of additives from the OPP film. However, it is the total thermal history during storage and transport to the customer which will affect the time to contaminate the metal surface. In order to have consistent adhesive lamination bonds it is always best to prime the metal surface to obtain the best adhesive bond when using OPP. However the adhesive must wet the aluminum surface and in order to insure the best most uniform wetting of the primer, the metal surface should be treated to "burn off" the additive tuypically with a bare roll corona treater, being careful not to hurt the heat sealing layer in the process (treatment of copolymer surfaces will increase the minimum sealing temperature so be careful not to have any back side treatment when cleaning the metal surface with a corona. The minimum dyne level will depend on the cleanlyness of the metal surface and the contamination level. I would always retreat the metal prior to priming to obtain the most consistant bonds

[Shaheen]

I am a student attending the University of Waterloo. I am now on my work term working for a company producing BOPP.

This company has a plasma treatment unit (in a vacuum)(within a metallizer [for 250 cm rolls]) that does not function well. Due to some software problems, we can only restrict the Plasma Power up to around 2kW (maximum when fixed: around 11kW). Plasma Power exceeding around 2.5kW will cause the arc value to increase signifcantly (which is undesireable).

My job is to optimize the effectivness of plasma treatment (in a vacuum) process with a constant gas composition being of 80% Argon and 20% oxygen (in one cylinder). Are the only other parameters from which I can alter, record and graph against optical density, OTR, and WVTR values :

>gas flow rate
>plasma power (within the limit)
>vacuum level (If so, how will it effect the process?)

Moreover, to test for the effect of the plasma treatment process, what properties, other than optical density, OTR, and WVTR can we measure to get QUANTATIVE results?

Any other tips??
Please advise.

Thank you

[Shaheen]

Hello;

Can you kindly advise the different methods of surface treatment we can use for treating BOPP film (e.g.: flame treatment, plasma treatment in vacuum....)?
What are the advantages and disadvantages of each of the treatments? At the right conditions (can you pls also advise the conditions), what is the rate of improvement for different plasma powers, gas flow rates, and web speeds when we compare it with no
plasma treatment BOPP film

Thank you in advance for yr help

Regards
Shaheen Zangooi

[Shaheen]

Hello;

Can you kindly advise the different methods of surface treatment we can use for treating BOPP film (e.g.: flame treatment, plasma treatment in vacuum....)?
What are the advantages and disadvantages of each of the treatments? At the right conditions (can you pls also advise the conditions), what is the rate of improvement for different plasma powers, gas flow rates, and web speeds when we compare it with no
plasma treatment BOPP film

Thank you in advance for yr help

Regards
Shaheen Zangooi

[szangooi]

1)What do we try to achieve with plasma treatment (in vacuum) on BOPP film.

2)How is BOPP film effected when treated by plasma treatment in vacuum. In other words, how is the structure of the surface altered.

3)If there are any disadvantages of plasma treatment (in vacuum) what are they?

Thanks.

[Ghelghelloo]

1)What is the 'Plasma Theory'?
2)What is the background of low pressure (vacuum) plasma treatment plasma surface treatment?
3)After corona treatment of BOPP film, why is it required to further treat the film by low pressure (vacuum)plasma treatment?

Thanks

[Charles A. Bishop]

Hi, relating to the questions you posed to the VacuumCoatingBlog.

Have you read the posting of 13th Feb about treating surfaces?
This posting explains some of what you are wishing to know.

For vacuum web plasma treatment the pressure used can have a wide range depending on the plasma treater used and the position the treater is placed in. In some systems the unit is placed in the winding zone and with some gas introduction this makes the pressure quite high. Whereas in other systems the unit is positioned in the deposition zone and so the background pressure is 1 x 10E-5 Torr. The pressure in the unit is often at least a couple of orders of magnitude greater than this. This too can have a wide range of pressure depending on the design of the plasma treater and if it has magnetic confinement how strong the magnets are.


Regarding corona treatment. Good corona treatment that is metallized soon after treatment may well be acceptable in most instances. However for some products it may not be good enough or in other cases if the metallization is delayed there is the possibility that the surface degrades with time or is recontaminated from slip agents or other additives that are used to make give some of the mechanical properties as well as to make the polymer web handlable. In this case either the corona treatment needs to be re-done or the web needs to be vacuum plasma treated.
Often the corona treatment is only done on one side & so the reverse side has all the contaminants left in place and as soon as the polymer web is wound up the back surface will come in contact with the front surface and start to re-contaminate the front surface.
In vacuum plasma treatment the cleaning process is done immediately before the metal deposition & so there is the minimum chance of re-contaminating the surface & so if the vacuum plasma treatment has been done to the correct level this will lead to the optimum adhesion between coating and substrate.


I hope this has clarified the topic for you.
Best regards
Charles A.Bishop
C.A.Bishop Consulting Ltd

Tel +44 (0)1509 502076
www.cabuk1.co.uk

[Ranjit Jundre]

I am student of packaging institute presently working in multinational company.please tell me what is the method to find out optical density of metallized film which is laminated to other film and in with print or without print? thank u very much for the information u have display on web.

[Ranjit Jundre]

I am student of packaging institute presently working in multinational company.please tell me how can we prevent oxidation of aluminium in metallized films. Is there any lacquer or coating available to prevent oxidation.Thank u very much in advance for ur help.

[Sam]

In general, which of the following processes in low pressure plasma treatment are accomplished by inert gases, reactive gases, or electrons.

Ablation (Etching)
Deposition
Cross-linking
Functionalisation (Surface Activation)

Thanks